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Comprehensive Storm
Drainage Plan
Prepared for the
Community Development and
Public Works Department
City of Auburn, Washington
October 2015
DRAFT
701 Pike St., Suite 1200
Seattle, WA 98101
Comprehensive Storm Drainage Plan
Prepared for the
Community Development and Public Works Department
City of Auburn, Washington
October 2015
This is a draft and is not intended to be a final representation
of the work done or recommendations made by Brown and Caldwell.
It should not be relied upon; consult the final report.
DRAFT
v
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Table of Contents
List of Figures ............................................................................................................................................. viii
List of Tables ................................................................................................................................................ ix
List of Abbreviations .................................................................................................................................... xi
Executive Summary ..................................................................................................................................... 1
ES-1 LOS Goals ................................................................................................................................... 1
ES-2 Evaluation of the Storm Drainage Utility .................................................................................. 4
ES-3 Implementation Plan ................................................................................................................. 5
ES-3.1 6-Year and 20-Year CIP ............................................................................................... 5
ES-3.2 Monitoring .................................................................................................................... 7
ES-3.3 Programmatic Measures for NPDES Compliance ..................................................... 9
ES-3.4 Future Staffing and Equipment Needs ................................................................... 10
ES-3.5 Assessment Management ....................................................................................... 10
ES-3.6 Recommendations for Additional Activities ............................................................ 10
ES-4 Financial Plan .......................................................................................................................... 11
1. Introduction .........................................................................................................................................1-1
Purpose and Objectives ..........................................................................................................1-1 1.1
Approach and Document Organization .................................................................................1-2 1.2
2. Background .........................................................................................................................................2-1
Storm Drainage Utility .............................................................................................................2-1 2.1
2.1.1 Organizational Structure ..........................................................................................2-1
2.1.2 Funding Mechanisms ...............................................................................................2-2
Development Code and Design Standards Updates ............................................................2-4 2.2
Regulatory Considerations .....................................................................................................2-5 2.3
2.3.1 Growth Management Act .........................................................................................2-6
2.3.2 Phase II Municipal Stormwater Permit ....................................................................2-7
2.3.3 Governmental Accounting Standards Board ..........................................................2-8
3. Utility Policies and Level-of-Service Goals.........................................................................................3-1
Level-of-Service Goals within Storm Drainage Utilities ........................................................3-1 3.1
Storm Drainage Utility Policies and Levels of Service ..........................................................3-2 3.2
4. Drainage System ................................................................................................................................4-1
Natural Drainage.....................................................................................................................4-1 4.1
4.1.1 Green River ...............................................................................................................4-1
4.1.2 White River ................................................................................................................4-2
4.1.3 Mill Creek ..................................................................................................................4-2
4.1.4 Drainage Areas .........................................................................................................4-3
4.1.5 Climate and Precipitation ........................................................................................4-3
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4.1.6 Geology and Groundwater ....................................................................................... 4-4
4.1.7 Soils and Runoff Potential ....................................................................................... 4-5
4.1.8 Land Use and Development .................................................................................... 4-5
4.1.9 Flood Hazard Mapping ............................................................................................. 4-6
Stormwater Drainage Infrastructure ..................................................................................... 4-7 4.2
Critical Facilities ..................................................................................................................... 4-8 4.3
Water Quality .......................................................................................................................... 4-9 4.4
4.4.1 Existing Conditions ................................................................................................... 4-9
4.4.2 Regulatory Compliance .......................................................................................... 4-10
Existing Drainage Problems ................................................................................................. 4-10 4.5
5. Evaluation of the Storm Drainage Utility .......................................................................................... 5-1
Hydraulic Evaluation .............................................................................................................. 5-1 5.1
5.1.1 Updating Existing Models ........................................................................................ 5-2
5.1.2 Creating New Models ............................................................................................... 5-2
Asset Management Evaluation .............................................................................................. 5-3 5.2
Environmental Investigation .................................................................................................. 5-6 5.3
6. Maintenance and Operations ............................................................................................................ 6-1
Utility Responsibility and Authority ........................................................................................ 6-1 6.1
6.1.1 Organizational Structure .......................................................................................... 6-1
6.1.2 Staffing Level............................................................................................................ 6-1
6.1.3 Level of Service ........................................................................................................ 6-2
6.1.4 Training and Education ............................................................................................ 6-2
Routine Operations Provided by the Storm Drainage Utility ................................................ 6-3 6.2
6.2.1 Catch Basin and Manhole Inspection, Cleaning, and Repair ................................ 6-3
6.2.2 Stormwater Pipeline Cleaning and CCTV ................................................................ 6-3
6.2.3 Stormwater Outfall Inspection, Cleaning, and Maintenance ................................ 6-4
6.2.4 Drainage Ditch Maintenance and Restoration ...................................................... 6-4
6.2.5 Stormwater Pond and Swale Inspection, Maintenance, and Restoration ........... 6-4
6.2.6 Culvert Inspection and Cleaning ............................................................................. 6-5
6.2.7 General Facility Maintenance and Other Field Tasks ............................................ 6-5
Routine Operations Provided to the Storm Drainage Utility ................................................ 6-5 6.3
6.3.1 Vegetation Maintenance ......................................................................................... 6-5
6.3.2 Stormwater Pump Station Maintenance ................................................................ 6-5
6.3.3 Stormwater Pond Maintenance by King County .................................................... 6-6
6.3.4 Stormfilter Maintenance.......................................................................................... 6-6
Non-Routine and Emergency Operations.............................................................................. 6-6 6.4
6.4.1 Customer Service Requests .................................................................................... 6-7
6.4.2 Emergency Response Program ............................................................................... 6-7
Data Collection and Record-Keeping .................................................................................... 6-8 6.5
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M&O Staffing Requirements ..................................................................................................6-9 6.6
6.6.1 Existing Staffing Requirements ...............................................................................6-9
6.6.2 Future Staffing Requirements and Equipment Needs ........................................ 6-11
Potential Improvement Opportunities and Capital Needs ................................................ 6-13 6.7
7. Capital Improvements ........................................................................................................................7-1
Project Prioritization ...............................................................................................................7-2 7.1
Proposed Drainage Projects...................................................................................................7-4 7.2
Programmatic Drainage Projects ........................................................................................ 7-47 7.3
8. Implementation Plan ..........................................................................................................................8-1
6-Year and 20-Year CIP ..........................................................................................................8-1 8.1
Monitoring ...............................................................................................................................8-4 8.2
8.2.1 Precipitation ..............................................................................................................8-4
8.2.2 Flow ...........................................................................................................................8-4
8.2.3 Stream and Pond Water Level .................................................................................8-7
8.2.4 Water Quality ............................................................................................................8-8
Programmatic Measures for NPDES Compliance .................................................................8-8 8.3
Future Staffing and Equipment Needs ..................................................................................8-9 8.4
8.4.1 Engineering Services ................................................................................................8-9
8.4.2 M&O Services ........................................................................................................ 8-10
Continue Implementation of Best Practices for Asset Management ............................... 8-11 8.5
8.5.1 Continue System Inventory ................................................................................... 8-12
8.5.2 Implement Economic Life Model Using Cartegraph Data ................................... 8-12
8.5.3 Economic Life Model Improvements .................................................................... 8-12
8.5.4 Maintenance and R&R Prioritization .................................................................... 8-13
8.5.5 M&O Activities........................................................................................................ 8-14
Recommendations for Additional Activities ....................................................................... 8-14 8.6
8.6.1 Develop Easement Review and Acquisition Program ......................................... 8-14
8.6.2 Risk Assessment/Asset Vulnerability Analysis .................................................... 8-14
8.6.3 Incorporate Sustainability ..................................................................................... 8-15
9. Finance ................................................................................................................................................9-1
Past Financial Performance ...................................................................................................9-1 9.1
9.1.1 Statement of Revenues, Expenses, and Changes in Net Position ........................9-1
9.1.2 Statement of Net Position ........................................................................................9-2
9.1.3 Outstanding Debt Principal ......................................................................................9-4
Available Capital Funding Resources ....................................................................................9-5 9.2
9.2.1 Internal Utility Resources .........................................................................................9-5
9.2.2 Government Programs and Resources ...................................................................9-7
9.2.3 Public Debt Financing ..............................................................................................9-9
9.2.4 Capital Resource Funding Summary .................................................................... 9-10
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Financial Plan ....................................................................................................................... 9-10 9.3
9.3.1 Utility Fund Structure ............................................................................................. 9-11
9.3.2 Financial Policies ................................................................................................... 9-11
9.3.3 Capital Funding Plan .............................................................................................. 9-13
Financial Forecast ................................................................................................................ 9-14 9.4
9.4.1 Cash Test ................................................................................................................ 9-14
9.4.2 Coverage Test ......................................................................................................... 9-14
9.4.3 Financial Forecast Assumptions ........................................................................... 9-15
9.4.4 City Funds and Reserve Balances ........................................................................ 9-17
Existing Rate Structure and Projected Schedule ............................................................... 9-18 9.5
Affordability ........................................................................................................................... 9-19 9.6
Conclusion ............................................................................................................................ 9-19 9.7
10. Limitations .................................................................................................................................... 10-1
11. References ................................................................................................................................... 11-1
Appendix A: Western Washington Phase II Municipal Stormwater Permit ........................................... A-1
Appendix B: Phase II NPDES Stormwater Permit Compliance Work Plan ............................................. B-1
Appendix C: Hydrologic and Hydraulic Modeling and Evaluation .......................................................... C-1
Appendix D: SEPA Compliance ................................................................................................................ D-1
List of Figures
Figure ES-1. NPDES Compliance Schedule ............................................................................................... 9
Figure ES-2. Implementation Plan Activities Timeline ............................................................................. 13
Figure 2-1. Community Development and Public Works Department Staff Organizational Chart ...... 2-2
Figure 4-1. Natural Drainage Features of the City of Auburn .............................................................. 4-13
Figure 4-2. Drainage Subareas for the City of Auburn Storm Drainage Utility .................................... 4-15
Figure 4-3. Surface Geology in the Vicinity of the City of Auburn ........................................................ 4-17
Figure 4-4. Land Use Designations for the City of Auburn ................................................................... 4-19
Figure 4-5. Drainage Infrastructure for the City of Auburn Storm Drainage Utility ............................. 4-21
Figure 4-6. City and Storm Drainage Critical Facilities for the City of Auburn .................................... 4-23
Figure 4-7. Drainage Problem Locations for the Storm Drainage Utility ............................................. 4-25
Figure 5-1. Drainage Pipe Summary ....................................................................................................... 5-5
Figure 7-1. Project Locations, Storm Drainage Utility Capital Improvement Program ......................... 7-3
Figure 7-2. Project 1: West Main Street Pump Station Upgrade ........................................................... 7-7
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Figure 7-3. Project 2: 37th and I Streets NW Storm Improvements ................................................... 7-11
Figure 7-4. Project 3: Hillside Drainage Assessment........................................................................... 7-15
Figure 7-5. Project 4A: 30th Street NE Area Flooding, Phase 2 .......................................................... 7-19
Figure 7-6. Project 4B: 30th Street NE Area Flooding, Phase 3 ......................................................... 7-21
Figure 7-7. Project 5A: West Hills Drainage Improvements, S 330th St. and 46th Pl. S .................. 7-25
Figure 7-8. Project 5B: West Hill Drainage Improvements, S 314th St. and 54th Ave. S ................. 7-29
Figure 7-9. Project 6: North Airport Area Improvements ..................................................................... 7-33
Figure 7-10. Project 7: D St. SE Storm Improvements ........................................................................ 7-37
Figure 7-11. Project 8: 23rd St. SE Drainage Improvements.............................................................. 7-41
Figure 8-1. Annual Costs for 6-year CIP ...................................................................................................8-3
Figure 8-2. Proposed Monitoring Locations ............................................................................................8-6
Figure 8-3. NPDES Compliance Schedule ...............................................................................................8-9
Figure 8-4. Implementation Plan Activities Timeline ........................................................................... 8-17
List of Tables
Table ES-1. Level-of-Service Goals .............................................................................................................. 2
Table ES-2. Project Cost Summary for 6- and 20-Year CIP ....................................................................... 6
Table ES-3. Proposed Flow Monitoring Sites .............................................................................................. 7
Table ES-4. Proposed Water Level Monitoring Sites ................................................................................. 8
Table 2-1. 2015 and 2016 Utility Rates for Storm Drainage Service ...................................................2-3
Table 2-2. Federal, State, and City Regulations and Programs Relevant to the Auburn Storm
Drainage Utility ..................................................................................................................................2-5
Table 3-1. Storm Drainage Utility Policies and LOS Goals .....................................................................3-2
Table 4-1. Precipitation Frequency Data for Auburn, Washington, from NOAA Atlas 2 ........................4-4
Table 4-2. FEMA Flood Insurance Rate Maps Applicable to Auburn .....................................................4-6
Table 4-3. Stormwater Drainage Infrastructure Summary .....................................................................4-7
Table 4-4. Critical City Facilities ...............................................................................................................4-8
Table 4-5. Critical Stormwater Facilities ..................................................................................................4-9
Table 4-6. Existing Drainage Problems ................................................................................................. 4-11
Table 6-1. Storm Drainage Utility M&O Personnel ..................................................................................6-2
Table 6-2. Existing Storm Drainage System Maintenance and Staffing Requirements .......................6-9
Table 6-3. Existing Vegetation Maintenance and Staffing Requirements .......................................... 6-10
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Table 6-4. Future Storm Drainage System Maintenance and Staffing Requirements ...................... 6-12
Table 7-1. Summary Programmatic Drainage Projects ........................................................................ 7-47
Table 8-1. Annual Project Cost Summary for 6-Year CIP ....................................................................... 8-2
Table 8-2. Cost Summary for 20-Year CIP .............................................................................................. 8-4
Table 8-3. Proposed Flow Monitoring Sites ............................................................................................ 8-5
Table 8-4. Proposed Water Level Monitoring Sites ................................................................................ 8-7
Table 8-5. Future Engineering Services Staffing Needs ...................................................................... 8-10
Table 8-6. Future Maintenance and Operations Staffing Needs ......................................................... 8-11
Table 9-1. Statement of Revenues, Expenses and Changes in Fund Net Position .............................. 9-2
Table 9-2. Statement of Net Position ...................................................................................................... 9-2
Table 9-3. Outstanding Debt .................................................................................................................... 9-4
Table 9-4. Current System Development Charge Schedule .................................................................. 9-5
Table 9-5. Drainage CIP ......................................................................................................................... 9-13
Table 9-6. Capital Financing Plan .......................................................................................................... 9-13
Table 9-7. Financial Forecast ................................................................................................................ 9-17
Table 9-8. Cash Balance Summary ....................................................................................................... 9-18
Table 9-9. Projected Rate Schedule ...................................................................................................... 9-18
Table 9-10. Affordability Test ................................................................................................................. 9-19
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List of Abbreviations
§ section
ACC Auburn City Code
BAB Build America Bonds
BMP best management practice
CCTV closed-circuit television
CEMP City’s Emergency Management Plan
CERB Community Economic Revitalization Board
cfs cubic foot/feet per second
CIP Capital Improvement Program
CMMS computerized maintenance management
system
Comp Plan Comprehensive Plan for the City of
Auburn (Land Use Plan)
CWA Clean Water Act
DEM Digital Elevation Model
Drainage Plan Comprehensive Storm Drainage Plan
Ecology Washington State Department of Ecology
Engineering Engineering Services (division within
Community Development and Public
Works)
EPA Environmental Protection Agency
ESA Endangered Species Act
ESU equivalent service unit
EWE Energy and Water Efficiency
FEMA Federal Emergency Management Agency
FIRM Flood Insurance Rate Map
FIS Flood Insurance Study
FTE full-time equivalent
GASB Governmental Accounting Standards Board
GIS geographic information system
GMA Growth Management Act
GO general obligation
HDPE high-density polyethylene
H&H hydrologic and hydraulic
HPA Hydraulic Project Approval
IDDE illicit discharge detection and elimination
KCFCD King County Flood Control Zone District
LFC local facilities charge
LID low-impact development
LOS level of service
LOMR Letter of Map Revision
MACP Manhole Assessment and Certification
Program
MEP maximum extent practicable
M&O maintenance and operations
MS4 municipal separate storm sewer system
NASSCO National Association of Sewer Service
Companies
NAVD88 North American Vertical Datum 1988
NFIP National Flood Insurance Program
NOAA National Oceanic and Atmospheric
Administration
NPDES National Pollutant Discharge Elimination
System
NPDES Permit Western Washington Phase II
Municipal Stormwater Permit
NRCS Natural Resources Conservation Service
NSF non-single-family
PACP Pipeline Assessment and Certification Program
PWB Public Works Board
RCW Revised Code of Washington
ROW right-of-way
R&R repair and replacement
RSI required supplementary information
SCADA supervisory control and data acquisition
SDC system development charge
SEPA State Environmental Policy Act
SFAP Stormwater Financial Assistance Program
SFHA Special Flood Hazard Area
SR State Route
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SRS software requirement specification
SWIF System Wide Improvement Framework
SWMM Surface Water Management Manual
SWMP Stormwater Management Program
TMDL total maximum daily load
ULID utility local improvement district
USACE U.S. Army Corps of Engineers
VRFA Valley Regional Fire Authority
WAC Washington Administrative Code
WRCC Western Regional Climate Center
WSDOT Washington State Department of
Transportation
ES-1
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Executive Summary
This Comprehensive Storm Drainage Plan (Drainage Plan) for the City of Auburn (City) updates the
previous plan, which was completed in 2009. The update was done to address new regulatory
requirements, refine and document maintenance and operations (M&O) practices and assess staffing
needs, update the list of projects for the Capital Improvement Program (CIP), and develop a current
financial plan. This new Drainage Plan is intended to guide future activities and improvements for the
storm drainage system based on an asset management approach.
This Drainage Plan was developed through the following steps:
• Review relevant information regarding the Storm Drainage Utility organizational structure, funding
mechanisms, and regulatory drivers (Chapter 2).
• Review and update the level-of-service (LOS) goals in light of current Storm Drainage Utility
responsibilities and new regulatory requirements (Chapter 3). LOS goals are policy- and community-
based objectives for capital facility infrastructure development, operation, maintenance, and other
Storm Drainage Utility activities.
• Characterize the current and expected future conditions of the natural and constructed drainage
systems (Chapter 4) and identified drainage problems. The constructed drainage system requires a
detailed system inventory for use in analyses and asset management.
• Evaluate the Storm Drainage Utility to identify potential gaps between the LOS goals and current or
expected future service levels (Chapter 5). Evaluations included hydraulic analyses of the drainage
system, asset life-cycle analyses, environmental investigations, and review of M&O activities
(Chapter 6).
• Evaluate alternatives to reduce or eliminate identified gaps in service (Chapter 7) and select the
measures to be included in the Drainage Plan based on detailed hydraulic modeling, estimated
costs, and other factors.
• Establish the implementation plan, which is the future work plan for the Storm Drainage Utility
(Chapter 8). Capital improvement projects from Chapter 7 were prioritized and placed into 6-year
and 20-year CIP time frames. Non-capital works recommendations such as flow monitoring,
regulatory compliance, future staffing needs improvements, additional asset management best
practices, and additional programs and analysis are also included in the implementation plan.
• Prepare a financial plan (Chapter 9) to support the costs associated with proposed improvements.
This Drainage Plan contains implementation for future actions and decisions. These time frames could
change depending on factors such as scheduling of project work, funding, and future opportunities to
coordinate with non-Storm Drainage Utility projects such as road improvements. Therefore, the time
frames are intended as guidance only and do not represent actual commitments by the City.
The following sections summarize the development of the Drainage Plan and outline the
recommendations contained in the implementation plan and a summary of the financial plan.
ES-1 LOS Goals
LOS goals provide a framework for the Storm Drainage Utility to assess its staffing levels, prioritize its
resources, justify its rate structure, and document its successes. It is important that LOS goals include
clear criteria for evaluating Storm Drainage Utility performance.. LOS goals and associated City policies
are summarized in Table ES-1.
Executive Summary Comprehensive Storm Drainage Plan
ES-2
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Table ES-1. Level-of-Service Goals
Item Policy description 2015 Drainage Plan LOS goal
Policy category: business practices
1
The City desires to employ recognized best business
practices that result in the efficient and cost-effective
operation of the utility.
The City shall identify the key business functions within the utility (e.g., billing,
permitting, asset management, and planning) and develop supporting best
business practices for each. The utility will conduct a performance audit every 6
years in conjunction with its capital projects planning cycle to evaluate how well
best business practices are being implemented and how effective they are.
2
The City shall seek to employ the best practices for
asset management by systematically basing choices on
an understanding of asset performance, risks, and
costs in the long term.
The City shall begin implementing the following best practices for all stormwater
facilities during the next planning period and report progress annually:
• Have knowledge about assets and costs (i.e., detailed inventories and
condition assessments)
• Maintain desired levels of service confirmed by customers
• Take a life-cycle approach to asset management planning
Implement the planned solutions to provide reliable, cost-effective service
Policy category: protection of public safety and property
3
The City shall seek to manage stormwater runoff within
the public right-of-way (ROW) to allow access to and
functionality of critical services such as hospitals, fire
and police stations, Emergency Operations Center,
maintenance and operations, and City Hall. 7.
Public drainage infrastructure will be designed and maintained so that the
annual chance of occurrence of surface water flooding that disrupts the function
of critical facilities (i.e., with floodwaters reaching the building structure,
damaging the structure, and permitting no ingress/egress) will be no greater
than 1% (i.e., an average recurrence interval of 100 years).
4
The City shall seek to manage stormwater runoff within
the public ROW to preserve mobility on major
transportation routes (i.e., arterial roads) and
residential roads.
Public drainage infrastructure will be designed and maintained so that the
annual chance of occurrence of flooding disruption that inundates city roadways
to an impassable level will be no greater than 4% (i.e., an average recurrence
interval of 25 years).
5
The City shall seek to manage stormwater runoff from
the public ROW to protect real property structures (e.g.,
residences and businesses).
Public drainage infrastructure will be designed and maintained so that the
annual chance of occurrence of flooding (surface water from ROW runoff entering
premises and damaging building structures) will be no greater than 2 percent
(i.e., an average recurrence interval of 50 years).
6
The City shall seek to prevent erosion and landslides
related to construction, operation, and maintenance of
the publicly owned drainage system.
Public drainage infrastructure will be constructed, operated, and maintained so
that there is no resulting erosion or landslides.
7
The City shall seek to maintain storm drainage
infrastructure to ensure proper function of drainage
facilities. The City shall seek to seasonally maintain
storm drain inlets, conveyance, and outfalls to preserve
design conveyance capacity.
The City will continue to refine its maintenance practices and reallocate staff as
needed to address seasonal concerns, with an emphasis on maintaining
facilities that have a high “consequence of failure.” An example would be
focusing extra M&O staff on catch basin inlet cleaning during autumn when
leaves are falling. All activities will be documented within the City’s Cartegraph
computerized maintenance management system (CMMS).
Policy category: reliability of the storm drainage infrastructure
8
The City shall seek to maintain an asset criticality
database to be used in prioritizing asset maintenance
and R&R.
The existing criticality database (developed for the 2008 Drainage Plan) will be
refined to include more asset information, such as pipe material, diameter, age,
consequence of failure, etc. The criticality database will be validated using the
results of previous and ongoing M&O inspections. Activities will be documented
within the City’s Cartegraph CMMS.
9 The City shall seek to perform condition assessments of
critical assets.
The City will develop and implement a condition assessment schedule for all
critical assets as identified through criticality analyses of stormwater
infrastructure assets. Criticality is based on the risk and consequences of failure.
Criticality data will be stored in a criticality database, and all condition
assessment activities will be documented in the City’s Cartegraph CMMS.
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Table ES-1. Level-of-Service Goals
Item Policy description 2015 Drainage Plan LOS goal
10 The City shall seek to repair or replace system assets
before they exceed their economic lives.
The number of high-criticality pipe segments beyond their economic lives will be
determined. After the criticality database inventory is complete, the City’s goal
will be to limit the number of pipe segments beyond their economic lives,
including setting specific numeric goals for replacement of those segments.
11
The City shall seek to conduct maintenance activities in
accordance with a schedule developed to comply with
Ecology requirements and asset criticality.
No deferred maintenance on all critical or Ecology-required assets. The City will
prioritize its inspection activities based on the combined “risk of failure” and
“consequence of failure” computed by the criticality database and meet current
NPDES inspection schedule (e.g., inspecting catch basins). The experience of
M&O staff should be incorporated into the criticality database (see item 8
above). All inspection activities will be documented in the CMMS.
12
The City shall seek to maintain storm drainage
infrastructure to ensure proper function of drainage
facilities in accordance with Ecology requirements..
The City will develop a ditch maintenance program. The City will secure proper
permits as well as coordinate with other agencies for work in the associated
ROW. The ditch maintenance program will consist of inspecting and maintaining
all ditches within the permit cycle and then on an as-needed basis.
13
The City shall seek to manage stormwater runoff from
the public ROW with City-owned facilities located in the
public ROW or on City-owned property. The City shall
maintain or seek access to City-owned facilities for
necessary maintenance and operation.
The City’s Storm Drainage Utility will be responsible for maintenance and
operation of the City’s drainage system. The City shall seek to have access to all
City-owned drainage infrastructure. The City shall seek to obtain easements or
relocate infrastructure as necessary to maintain access.
Policy category: protection of the environment
14
The City shall seek to comply with all federal and state
regulations applied to stormwater management
activities.
Meet all requirements of the Western Washington Phase II Municipal Stormwater
Permit with no enforcement actions of the CWA for violations as a result of City
stormwater operations.
15
The City shall seek to provide pump redundancy and
backup power generators or dual power feeds at City-
owned and -operated drainage pump stations.
All pump stations will be designed with two or more pumps to ensure proper
function during maintenance. Backup and/or dual-feed power supplies will be
installed as needed.
16
The City shall seek to comply with all federal, state, and
local regulations in operation and maintenance of the
City’s storm drainage infrastructure.
Meet all specific targets. Examples include complying with NPDES Phase II
inspection cycle, performing all necessary ESA consultations, etc.
17
The City shall protect and preserve existing native
vegetation and drainage courses while maintaining
their conveyance capacity.
The City will maintain existing habitat along drainage ways so there is no net loss
of native vegetation (in terms of area) or natural drainage systems (in terms of
stream length) . This does not apply to constructed or maintained facilities.
18
The City shall seek to comply with all federal, state, and
local regulations to reduce runoff volumes and
pollutant loads associated with new development and
redevelopment.
The City will comply with the elements of the Western Washington Phase II
Municipal Stormwater Permit and will adopt or implement the Ecology manual or
equivalent for new development and redevelopment.
19
The City shall place emphasis on onsite approaches
such as LID as the first consideration for runoff and
pollutant load reduction for new development and
redevelopment.
The City will identify feasibility criteria and provide guidance for the
implementation of LID drainage management measures for new development
and redevelopment (including City-owned properties).
20 The City shall seek to evaluate Storm Drainage Utility
activities to emphasize sustainability.
City staff will identify specific areas to measure sustainability by examining how
Storm Drainage Utility operations affect energy resources, natural resources,
and the community. City staff will benchmark practices and log changes over the
next planning period.
21
The City shall continue to participate in regional storm
drainage, water resources, and water quality planning
efforts.
The City will continue to actively participate in developing and implementing
regional water quality planning and flood hazard reduction efforts within the
Green River, Mill Creek, and White River drainage basins. The City will participate
in the state’s water quality monitoring program.
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Table ES-1. Level-of-Service Goals
Item Policy description 2015 Drainage Plan LOS goal
22
The City shall comply with all federal, state, and local
regulations in the inspection of the City’s publicly
owned storm drainage infrastructure and privately
owned LID facilities.
For all new LID systems constructed after 2016, the City will develop authority
and an inspection frequency for stormwater facilities developed in compliance
with the NPDES Phase II Stormwater Permit. The City will develop an inspection
assessment database to monitor and schedule facility maintenance for all
publicly owned storm drainage infrastructure and privately owned LID facilities.
This database will provide maintenance information for the criticality database
in the City’s Cartegraph CMMS.
Policy category: Storm Drainage Utility financial performance
23
The City shall continue to fund and provide storm
drainage services through the existing Storm Drainage
Utility.
The City’s Storm Drainage Utility should be responsible for implementation,
maintenance, and operation of the City’s drainage system, with a goal of 100%
of the cost of drainage service delivery recovered via Storm Drainage Utility fees.
Seek opportunities to provide public drainage benefits through grant funding
and/or development partnerships where applicable.
24
The City shall assess appropriate rates and SDCs to
fund the ongoing maintenance, operation, and capital
expenditures of the utility, in accordance with the
Drainage Plan.
Periodic cost-of-service studies shall be completed to reassess the monthly
service fees and SDCs. Updates to coincide with all 6-year CIP updates.
25 The City shall seek to track the cost of claims as a
metric.
City staff will summarize the annual costs of claims for the recent past to
establish a baseline measurement of existing practices. If the current costs are
deemed excessive, City staff will evaluate methods to reduce the risk of claims
and measure its progress at reducing the overall cost of claims.
26
The City shall seek to track elements of capital
improvement project implementation: (1) individual
schedule, (2) project budget accuracy, and (3) overall
performance in implementing CIP..
City staff will summarize current methods for capital improvement project
implementation to create a baseline (e.g., schedule and costs) against which
future improvements can be evaluated.
Policy category: customer satisfaction
27
The City shall seek to evaluate and strive to maintain
customer satisfaction with Storm Drainage Utility
service delivery.
To effectively measure the public perception of utility performance, City staff will
conduct the following: (1) summarize annual customer complaint reports, (2)
communicate proactively with community and stakeholders regarding drainage
infrastructure improvements, and (3) comply with Western Washington Phase II
Municipal Stormwater Permit requirements for public education and outreach.
28
The City shall seek to build, operate, and maintain
storm drainage infrastructure within an overarching
goal of protecting employee safety.
City staff will track health and safety incidents to create a baseline against which
to evaluate future improvements.
ES-2 Evaluation of the Storm Drainage Utility
A series of analyses were conducted to evaluate the Storm Drainage Utility and identify gaps between
existing service levels and the desired LOS goals. The following evaluations were completed as:
• Hydraulic: Hydraulic evaluations consisted of using hydraulic models covering locations of existing
problems to evaluate problems and develop capital improvement projects. Existing hydraulic models
were updated based on recent geographic information system (GIS) data, design drawings, and
record drawings. Some model updates also included calibration to flow monitoring data that were
collected in 2010 and 2011. For problem areas that had not been previously modeled, new models
were developed to estimate flow for capital improvement project sizing.
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• Asset management: Asset life-cycle evaluations require detailed system information. System data
(e.g., pipe material, pipe age, and proximity to critical facilities), which are stored in the City’s
Cartegraph CMMS, are used for such an analysis. This Drainage Plan includes a recommendation for
implementing the economic life model using the data in Cartegraph.
• Environmental: Environmental evaluations centered on regulatory compliance for the 2013–18
National Pollutant Discharge Elimination System (NPDES) Western Washington Phase II Municipal
Stormwater Permit (NPDES Permit). The permit was compared to the previous permit to identify
additional requirements that could affect City regulations, facilities, and activities. The results were
used to identify gaps and develop potential actions to comply with the NPDES Permit conditions over
the permit period. The results of that effort, including as they affect Storm Drainage Utility staffing
needs, are summarized in this Drainage Plan. The Compliance Work Plan, which outlines and guides
compliance activities over the current permit term, was also updated based on the results of the
analysis and is provided as an appendix to this Drainage Plan.
• Maintenance and operations: Existing M&O activities were evaluated to establish a baseline
understanding of the preventive and responsive maintenance procedures currently performed by
City Storm Drainage Utility M&O staff. The results were compared to LOS goals in order to estimate
Storm Drainage Utility staffing, data collection, computerized record-keeping, and other Storm
Drainage Utility needs. This plan identifies recommendations for improving existing services or work
productivity and for regulatory compliance.
ES-3 Implementation Plan
The implementation plan is intended to serve as the work plan for the Storm Drainage Utility. The
implementation plan consists of 6-year and 20-year CIPs, recommendations including monitoring and
data collection, activities for NPDES compliance, and recommendations for using asset management
strategies to improve utility M&O with an outlook on long-term sustainability.
ES-3.1 6-Year and 20-Year CIP
The 6-year CIP focuses mainly on existing flooding problems where recent storm events have revealed
deficiencies in the drainage system. The capital improvement projects are designed to mitigate flooding
in these areas and are expected to provide immediate benefits. The 6-year CIP also contains ongoing
programmatic efforts, such as the Storm Drainage Utility’s participation in the Street Utility
Improvements program.
As current problems are addressed in the near term, the focus of the CIP begins to shift toward a more
proactive program, where repair and replacement (R&R) of storm drainage assets can be prioritized
according to the optimal timing for interventions. Ultimately, this process will allow the City to meet
customer service levels, effectively manage risks, and minimize the City’s costs of ownership. The 20-
year CIP includes R&R. Table ES-2 lists the 12 capital improvement projects included in this Drainage
Plan and lays out annual expenditures for the 6-year and 20-year CIP time frames.
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Table ES-2. Project Cost Summary for 6- and 20-Year CIP
Project
number Project name Priority Repair/
Replacement
Upgrade/
Expansion
6-year CIP 2022–35 Total project
costs, $a 2016 2017 2018 2019 2020 2021
1 West Main Street Pump Station
Upgrade 1 100% 2,968,000 2,968,000
2 37th and I Streets NW Storm
Improvements 1 100% 291,000 291,000
3 Hillside Drainage Assessment 1 100% 139,000 150,000 289,000
4A 30th Street NE Area Flooding, Phase 2 2 100% 896,000 896,000
4B 30th Street NE Area Flooding, Phase 3 3 100% 2,124,000 2,124,000
5A West Hills Drainage Improvements at S
330th St. and 46th Pl. S 2 100% 317,000 317,000
5B West Hills Drainage Improvements near
S 314th St. and 54th Ave. S 3 100% 408,000 304,000 712,000
6 North Airport Area Improvements 2 100% 218,000 218,000
7 D St. SE Storm Improvements 2 100% 1,827,000 1,827,000
8 23rd St. SE Drainage Improvements 3 100% 316,500 316,500 633,000
9 Comprehensive Storm Drainage Plan
update 1 35% 65% 300,000 300,000
10 Vegetative Waste Sorting Facility 1 100% 750,000 75,000 825,000
11 Storm Drainage Infrastructure Repair &
Replacement Program 1 100% 100,000 1,000,000 100,000 1,000,000 100,000 1,000,000 7,700,000 11,000,000
12 Street Utility Improvements 1 100% 100,000 100,000 100,000 100,000 100,000 100,000 1,400,000 2,000,000
Total CIP cost for priority 1 projects 3,598,000 2,000,000 275,000 1,100,000 500,000 1,100,000 9,100,000 17,673,000
Total CIP cost for priority 2 projects 535,000 896,000 1,827,000 0 0 0 0 3,258,000
Total CIP cost for priority 3 projects 0 0 724,500 2,124,000 304,0000 316,500 0 3,469,000
Total CIP cost $4,133,000 $2,896,000 $2,826,500 $3,224,000 $804,000 $1,416,500 $9,100,000 $24,400,000
a. Project costs are in 2014 dollars.
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ES-3.2 Monitoring
Precipitation, stormwater flow, and water level data are needed to simulate rainfall-runoff processes with
hydrologic and hydraulic (H&H) models. Precipitation is the source of stormwater runoff, and
precipitation intensity and duration data are needed to drive H&H models. The City currently collects
rainfall data with a rain gauge at City Hall. Stormwater flow data, such as flow rates, runoff volumes, and
flooding elevations, are needed to calibrate models to assess the current capacity of the storm drainage
system and develop potential capital improvement projects. Water level data can be useful for
evaluating the performance of stormwater ponds and assessing the risk of overtopping. Water level
monitoring in creeks to which the City’s system discharges can be helpful to evaluate water level
changes due to restoration and culvert replacement activities, and their impacts on the storm drainage
system.
The City should continue to collect these types of data and store them in a consistent and organized
manner. Table ES-3 summarizes specific recommendations for additional flow monitoring data collection
for two potential problem areas. Table ES-4 summarizes specific recommendations for ongoing water
level data collection at existing creek and pond locations, as well as additional pond locations.
Table ES-3. Proposed Flow Monitoring Sites
Site numbera Location Purpose Measurement Start
year Approx. durationb
Potential problem area: Riverwalk Drive and Howard Road (increasing the tributary area to 17th and 21st street ponds)
P1012-
C690_C689
Intersection of
Auburn Way S and
Riverwalk Dr. SE
Quantify flow from upstream areas tributary to
flow control device in CB1012-C688 Depth and velocity 2016 1 to 2 wet seasons
CB1012-C688
Intersection of
Auburn Way S and
Riverwalk Dr. SE
Estimate flows to high flow ditch on Riverwalk Dr.
SE Depth 2016 1 to 2 wet seasons
C1111-
C1469_C1470
Intersection of
Howard Rd. and
Riverwalk Dr. SE
Quantify flows to support modeling flows that
may be connected to the City’s system at
CB1011-C1474
Depth and velocity 2016 1 to 2 wet seasons
P1011-
C1452_C1453
Howard Rd. between
21st St. SE and
Riverwalk Dr. SE
Quantify flows to support modeling flows that
may be connected to the City’s system at
CB1011-C1474
Depth and velocity 2016 1 to 2 wet seasons
P1011-
C1086_C1137
Howard Rd. between
21st St. SE and
Riverwalk Dr. SE
Quantify flows to support modeling flows that
may be connected to the City’s system at
CB1011-C1474
Depth and velocity 2016 1 to 2 wet seasons
P1010-C3_C29 Howard Rd. near
Auburn Way S
Provide data for H&H model calibration
(subbasin C) Depth and velocity 2016 1 to 2 wet seasons
P1010-
B220_B221
21st and K Streets
SE
Provide data for H&H model calibration
(subbasin C) post-CIP (AWS Phase 2)c Depth and velocity 2016 1 to 2 wet seasons
Potential problem area: 2nd and G streets SE
P909-
C122_C121
Auburn Way S, near
9th St. SE
Quantify flows upstream of flow split (at MH 909-
C12) between subbasins B and C, and provide
data for H&H model calibration
Depth and velocity Post-AWS
Phase 2c,d
1 to 2 wet seasons
P809-
C113_C112
F St. SE, north of SR
18
Quantify flows upstream of sewer crossing, and
provide data for H&H model calibration Depth and velocity Post-AWS
Phase 2c,d
1 to 2 wet seasons
P810-
C701_809-C18
G St. SE and E Main
St.
Provide data for H&H model calibration
(subbasin C) Depth and velocity Post-AWS
Phase 2c,d
1 to 2 wet seasons
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Table ES-3. Proposed Flow Monitoring Sites
Site numbera Location Purpose Measurement Start
year Approx. durationb
P810-C698_C16 M St. SE, south of E
Main St.
Provide data for H&H model calibration since M
St. Grade Separation and Well 1 Transmission
Projects implementation
Depth and velocity Post-AWS
Phase 2c,d
1 to 2 wet seasons
P810-C15_C241 E Main St. and N St.
SE Estimate backwater effects on drainage system Depth and velocity Post-AWS
Phase 2c,d 1 to 2 wet seasons
a. P = pipe, C = culvert, CB = catch basin, MH = manhole.
b. Data to support CIP need at least one wet season of good data—approximately October through April; if sufficiently large storms occur
during the first season, then year 2 data may not be necessary. Monitoring period and duration within a potential problem area should be
the same.
c. Relieve Auburn Way S Flooding; Phase 2 (AWS Phase 2) is planned for construction in 2015.
d. Detailed survey of the flow split at MH 909-C12 should be completed prior to flow monitoring, to understand system hydraulics at this
location.
Table ES-4. Proposed Water Level Monitoring Sites
Site number Location Purpose Start year Approx.
duration
WL-Mill-01 Mill Creek at 37th St. NW Evaluate stages in Mill Creek and assess backwater
effects on drainage system Ongoing since 2011 10 yearsa
WL-Mill-02 Mill Creek at 29th St. NW Evaluate stages in Mill Creek and assess backwater
effects on drainage system Ongoing since 2011 10 yearsa
WL-Mill-03 Mill Creek at 15th St. NW Evaluate stages in Mill Creek and assess backwater
effects on drainage system Ongoing since 2011 10 yearsa
WL-Mill-04 Mill Creek at West Main St. Evaluate stages in Mill Creek and assess backwater
effects on drainage system Ongoing since 2011 10 yearsa
WL-Pond-17thSt 17th and A streets SE Monitor pond performance (water levels and infiltration
rates) Ongoing since 2010 Indefiniteb
WL-Pond-21stSt 21st and D streets SE Monitor pond performance (water levels and infiltration
rates) Ongoing since 2011 Indefiniteb
WL-Pond-RiverN Riverwalk Dr. SE and U St. SE
Monitor pond performance (water levels and infiltration
rates) and evaluate capacity in support of analysis for
potential problem area at Riverwalk and Howard Road
2015 Indefiniteb
WL-Pond-LakeS1 Lakeland South Pond 1 Monitor water level to evaluate hazard risk (dam safety) 2015 Indefiniteb
WL-Pond-LakeS2 Lakeland South Pond 2 Monitor water level to evaluate hazard risk (dam safety) 2015 Indefiniteb
WL-Pond-LakeEP Lakeland East Pond Monitor water level to evaluate hazard risk (dam safety) 2015 Indefiniteb
WL-Pond-Mill Mill Pond (Oravetz Rd. SE) Monitor water level to evaluate hazard risk (dam safety) 2015 Indefiniteb
a. Based on need to examine backwater effects on system; if new capital improvements are identified for Mill Creek, additional years may be
needed.
b. To be continually reevaluated; if data indicate that stormwater pond is performing adequately or has low risk of failure, then monitoring
could cease.
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ES-3.3 Programmatic Measures for NPDES Compliance
As part of NPDES, the City of Auburn is covered by the NPDES Permit, which regulates stormwater
discharges from the City’s municipal separate storm sewer system (MS4). The City is actively engaged in
stormwater management activities to comply with the Permit, including the following:
• Stormwater management plan administration
• Public education and outreach
• Public involvement and participation
• Illicit discharge detection and elimination (IDDE)
• Control of runoff from new development, redevelopment, and construction sites
• Municipal operations and maintenance
• Monitoring and assessment
The compliance schedule for key NPDES Permit requirements is included in Figure ES-1. The City of
Auburn 2015 Stormwater Management Program Plan (City of Auburn, March 2015) provides additional
details regarding the City’s NPDES compliance activities.
Figure ES-1. NPDES Compliance Schedule
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ES-3.4 Future Staffing and Equipment Needs
Current Engineering Services (Engineering) and M&O staff and equipment were reviewed in light of
anticipated NPDES Permit requirements as well as existing and future M&O responsibilities. Based on
this evaluation, the following additional staff and equipment are recommended:
• 1.15 full-time equivalent (FTE) Engineering Services
• 3.3 FTE Storm Drainage Utility M&O Services
• 1.2 FTE Vegetation Maintenance Division Services
• Closed-circuit television (CCTV) inspection equipment for pipe inspection
• Excavator for drainage ditch and stormwater pond maintenance and restoration
• Excavator mower attachment for pond vegetation maintenance
ES-3.5 Assessment Management
Additional recommendations were made for activities to support asset management and ongoing M&O:
• Continue system inventory: The City should continue its comprehensive system inventory and the
inventory should be continually updated to reflect additional data collected during maintenance
activities (i.e., condition assessment and frequency of maintenance activities) and drainage system
changes through capital improvement projects.
• Implement economic life model using Cartegraph data: The City should implement the economic life
model for the pipes in its stormwater collection system using Cartegraph CMMS as a primary data
source. Improvements to the model should also be implemented including incorporating City data on
costs and failure rates, as well as adding catch basins and manholes to the model.
• Optimize M&O program: The City should continue to use the economic life model to optimize M&O
activities. Model results can be used to prioritize M&O activities and R&R for the assets for which the
City is carrying most of its risk. The City should continue the implementation of the National
Association of Sewer Service Companies (NASSCO) Pipeline Assessment and Certification Program
(PACP) and Manhole Assessment and Certification Program (MACP) certified inspection programs to
allow integration of inspection and condition assessment results with Cartegraph. The City should
also provide staff training to ensure assessment consistency.
ES-3.6 Recommendations for Additional Activities
Additional recommendations were made for activities that will support the Storm Drainage Utility in
meeting its LOS:
• Develop easement review and acquisition program: Parts of the City’s drainage network, particularly
in areas annexed from King County, are located outside of the right-of-way (ROW) and cross private
property without easements. The City should develop a process to ensure that it can meet the LOS
goal related to having access to City-owned facilities for M&O activities.
• Conduct risk assessment/asset vulnerability analysis: The City should conduct a vulnerability
analysis on the entire stormwater drainage system to examine the potential for natural disasters
such as flood, erosion, earthquake, or volcanic activity to cause system failures. Of particular
concern are critical facilities such as pump stations, hospitals, fire stations, M&O, City Hall, and City
Hall Annex. The probabilities of failure associated with natural hazards should be weighed with the
consequences of failure to determine if action is necessary and to identify appropriate mitigation
measures.
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• Incorporate sustainability: The City should take steps toward incorporating sustainability into Storm
Drainage Utility activities. Recommended actions include developing specific and measurable
sustainability goals for the Storm Drainage Utility and establishing standards that incorporate
sustainability into project and activities.
A timeline (Figure ES-2) was developed to illustrate how each of the recommended activities in the
implementation plan fit together within the 6-year and 20-year time frames.
ES-4 Financial Plan
A financial plan was developed to identify the total cost of providing storm drainage service and to
provide a financial program that allows the Storm Drainage Utility to remain financially viable during
execution of the CIP. The viability analysis considered the historical financial condition of the Storm
Drainage Utility, sufficiency of utility revenues to meet current and future financial and policy obligations,
and financial impact of executing the CIP. The plan also provides a review of the Storm Drainage Utility’s
rate structure with respect to rate adequacy and customer affordability.
The financial analysis indicated that the adopted rates should be sufficient to meet the predicted Storm
Drainage Utility financial obligations through 2018 with minimal bonds. An average rate increase of 2.6
percent is required to meet Storm Drainage Utility financial obligations for 2019 through 2021. The
evaluation also found that the projected rates would remain well within the defined threshold of
affordability
2016 2017 2018 2019 2020 2021 2022 2035
1. West Main Street Pump Station Upgrade
2. 37th and I Streets NW Storm Improvements
3. Hillside Drainage Assessment
4A. 30th Street NE Area Flooding, Phase 2
4B. 30th Street NE Area Flooding, Phase 3
5A. West Hills Drainage Improvements at S 330th St. & 46th Pl. S
5B. West Hills Drainage Improvements near S 314th St. & 54th Ave. S
6. North Airport Area Improvements
7. D St. SE Storm Improvements
9. Comprehensive Storm Drainage Plan update
11. Storm Drainage Infrastructure Repair & Replacement
12. Street Utility Improvements
Q1Q2Q3Q4
Pipe 1011-C1086_1011-C1137
Pipe 1011-C1452_1011-C1453
Culvert 1111-C1469_1111-C1470
Catch basin 1012-C688
Pipe 1012-C690_1012-C689
Pipe 1010-C3_1010-C29
Pipe 1010-B220_1010-B221
WL-Mill-01,02,03,04. Mill Creek Profile
WL-Pond-17thSt. 17th and A Streets SE
WL-Pond-21stSt. 21st and D Streets SE
WL-Pond-RiverN. Riverwalk Dr. SE and U St. SE
WL-Pond-LakeS1, -LakeS2, -LakeEP & -Mill
Detailed 6-year CIP Time Frame
Annual inspections of City-approved facilities constructed under
the terms of permit
Adopt 2012 Ecology Manual or equivalent manual
Measure effectiveness of public outreach
NP
D
E
S
P
e
r
m
i
t
R
e
i
s
s
u
a
n
c
e
Establish specific sustainability goals and standards
Continue system inventory
Conduct new economic life-cycle analyses
Implement economic life-model using Cartegraph data
Implement additional M&O activities
Develop easement review and acquisition program
Remaining 20-year CIP Summary
Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4
IMPLEMENTATION PLAN ACTIVITIES TIMELINE
City of Auburn Comprehensive Storm Drainage Plan
Additional Activities (Section 8.5)
NPDES Compliance (Section 8.3)
Monitoring (Section 8.2)
CIP (Section 8.1)
Data feed
Activity (may start before 2016)
K E Y
Risk assessment/asset vulnerability analysis
Complete one inspection of each catch basin
Review & update operations, maintenance & inspections standards
8. 23rd St. SE Drainage Improvements
Phase 1 Phase 2
Pipe 809-C113_809-C112
Pipe 909-C122_909-C121
Pipe 810-C701_809-C18
Pipe 810-C15_810-C241
Pipe 810-C698_810-C16
Complete field screening for 40% of storm drainage system
Complete field screening for 12% of storm drainage system annually
Revise ACC to reflect IDDE changes
Compile and submit a summary of LID review and revision process
Post SWMP documents to website annually
Review, revise & adopt local development codes, standards, &
the policies to require LID
Phase 1 Phase 2
Timing dependent on project to
be implemented in 2015
10. Vegetative Waste Sorting Facility
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Chapter 1
Introduction
This Comprehensive Storm Drainage Plan (Drainage Plan) for the City of Auburn, Washington, updates
the previous plan that was completed in December 2009 and amended in 2011. An update to the 2009
Drainage Plan is necessary for several reasons:
• The Washington State Growth Management Act (GMA) requires planning documents to be
reassessed and updated periodically.
• New and updated regulatory and permitting requirements, such as those associated with the
National Pollutant Discharge Elimination System (NPDES), need to be addressed.
• Continued growth and development, especially in areas annexed from King County, requires new
and revised evaluations of the storm drainage system to maintain an understanding of existing and
potential problems throughout the utility service area.
• The system inventory has been updated and is needed to account for utility assets and to improve
the accuracy of the analyses used to develop capital improvement projects.
• The Capital Improvement Program (CIP) proposed in the 2009 Drainage Plan needs to be
reevaluated to account for completed projects, changes in system conditions, and new
development, as well as to incorporate new financial information.
• Additional capital improvement projects need to be developed for problems identified since the
2009 Drainage Plan.
This comprehensive plan contains time frames that are the intended framework for future funding
decisions and within which future actions and decisions are intended to occur. However, these time
frames are estimates, and depending on factors involved in the processing of applications and project
work, and availability of funding, the timing may change from the included time frames. The framework
does not represent actual commitments by the City of Auburn, which may depend on funding resources
available.
Purpose and Objectives 1.1
The purpose of this Drainage Plan is to guide the City’s Storm Drainage Utility with respect to future
activities and improvements. The Drainage Plan’s objectives are to:
• Evaluate environmental, social, and regulatory drivers to update the level-of-service (LOS) goals for
capital facility infrastructure development, operation, maintenance, and other key elements of utility
management
• Incorporate updates to the stormwater drainage system inventory into the hydraulic models used for
analyzing the system
• Perform hydraulic modeling analysis to evaluate system capacity focusing on known problems and
areas where data are available for model development and calibration
• Identify monitoring needs for evaluating the performance of system assets, as well as for calibrating
hydraulic models in future modeling efforts
• Develop a CIP that meets required customer service levels, effectively managing risks, and
minimizing the City’s costs of drainage asset ownership
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• Document maintenance and operations (M&O) activities and develop recommendations for
improving the M&O program
• Prioritize capital improvement projects to accommodate both 6- and 20-year funding frameworks
• Incorporate information and activities from concurrent NPDES compliance planning
• Identify additional staffing needed based on NPDES requirements and future M&O activities
• Develop programmatic recommendations to address utility needs
Approach and Document Organization 1.2
Asset management principles were used throughout the development of this Drainage Plan. An asset
management approach is designed to deliver defined service levels at an acceptable risk with the lowest
life-cycle cost. Given this approach, identified problems were analyzed with respect to LOS goals, and
recommendations were developed for achieving those goals.
This Drainage Plan is organized in a way that focuses on the actions the utility will take while
implementing the plan. In most cases, supporting documentation and background information is
included in appendices rather than chapters of the Drainage Plan. The Drainage Plan is organized into
the following chapters:
Chapter 1 Introduction: describes the reasons for developing an updated Drainage Plan, and also
states the purpose and objectives of the Drainage Plan
Chapter 2 Background: provides background information regarding the Storm Drainage Utility and
regulatory drivers for developing LOS goals
Chapter 3 Utility Policies and Level-of-Service Goals: specifies the LOS goals used to develop capital
improvements and future M&O activities
Chapter 4 Drainage System: describes the existing conditions of the City’s drainage system
Chapter 5 Evaluation of the Storm Drainage Utility: describes methodologies used to evaluate existing
problems and develop capital improvement projects
Chapter 6 Maintenance and Operations: documents existing Storm Drainage Utility M&O activities
Chapter 7 Capital Improvements: describes recommended capital improvement projects including
cost estimates and conceptual figures
Chapter 8 Implementation Plan: prioritizes capital improvement projects and lays out a future work
plan
Chapter 9 Finance: identifies the total cost of providing stormwater drainage services and provides a
program for the utility to remain viable during execution of the CIP
Chapter 10 Limitations
Chapter 11 References
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Chapter 2
Background
This chapter provides a brief description of the Storm Drainage Utility; organizational structure; and
funding mechanisms; as well as an overview of the federal, state, and local regulations that can affect
stormwater management in the city.
Storm Drainage Utility 2.1
Recurring local flooding, continued development, and degradation of water resources led the City of
Auburn to form a public utility in 1986 to provide ongoing management of a storm drainage system 1.
Chapter 35.67 of the Revised Code of Washington (RCW) provides for the creation and funding of a
public sewerage system and associated drainage systems. Establishment of a Storm Drainage Utility is
found in Chapter 13.48 of the Auburn City Code (ACC). The general purpose of the Storm Drainage Utility
is to avoid public nuisances and promote public health, safety, and welfare by reducing the likelihood of:
• Inundation of public and private property by stormwater
• Uncontrolled volume increase, rate, or contaminated load of runoff
• Degradation of existing water resources such as creeks, streams, rivers, ponds, lakes, groundwater,
and other water bodies
• Degradation of water used for contact recreation, aquatic habitat, and aesthetic quality
• Jeopardy to the community’s compliance with federal flood insurance programs
The City’s current storm drainage system consists of 210 miles of pipe, 40 miles of ditches, more than
11,000 catch basins and manholes, 293 storage and water quality facilities, and 7 stormwater pump
stations designed to convey rainwater from various collection points for eventual discharge to nearby
receiving waters. A detailed description of the drainage system is provided in Chapter 4.
Sections 2.1.1 and 2.1.2 below describe the organizational structure of the Storm Drainage Utility and
funding mechanisms, respectively.
2.1.1 Organizational Structure
The City’s Storm Drainage Utility is organized under the larger umbrella of the Community Development
and Public Works Department. This department covers six basic areas of responsibility:
• Water Utility Program
• Sanitary Sewer Utility Program
• Storm Drainage Utility Program
• Transportation Program
• Maintenance and Operations Program
• Community Development Services
1 A public utility for stormwater management was established by City of Auburn Ordinance 4193 on December 15, 1986.
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Under these programs the Community Development and Public Works Department carries out long-term
planning, budget management, interaction, and regulation of development; management of capital
improvements; and maintenance and operation for the associated City facilities. Given these program
responsibilities, the Community Development and Public Works Department is divided into three
divisions: Engineering Services, Maintenance and Operation (M&O) Services, and Community
Development Services (see Figure 2-1). Planning and construction of storm drainage facilities is provided
by Engineering Services. Maintenance of storm drainage facilities is provided by a dedicated stormwater
division within M&O.
Figure 2-1. Community Development and Public Works Department Staff Organizational Chart
2.1.2 Funding Mechanisms
The following section provides adapted text from ACC, Title 13: Water, Sewers and Public Utilities,
Chapter 13.48, Storm Drainage Utility, §13.48.060, Authority to establish rates. Per the ACC, the City
has established rate classifications, service charges, and various fees and charges to pay for the
following costs:
• The development, adoption, and implementation of a comprehensive Storm Drainage Utility master
plan
• The debt service and related financing expenses of the construction and reconstruction of storm
drainage and water quality facilities required for the management of stormwater and surface waters
that benefit the service area but do not presently exist
Director of Community
Development and Public Works
Planning Services
Manager
Development Engineer
Building Official
Utilities Engineering
Manager
Transportation
Manager
General Engineering
Assistant City Engineer
Administration
Engineering Services
Assistant Director of Engineering/
City Engineer
Maintenance & Operations Services
Assistant Director of Public Works
Operations
Community Development Services
Assistant Director of Community
Development
Street/Vegetation
Manager
Water Distribution &
Operations
Manager
Sewer/Storm
Manager
Fleet/Central Stores
Manager
Administration
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• The operation, repair, maintenance, improvement, replacement, and reconstruction of storm
drainage facilities that benefit the present service area (e.g., capital improvement projects to
increase system capacity in accordance with LOS goals)
• The purchase of a fee or lesser interest, including easements, in land that may be necessary for the
storm drainage system in the service area including, but not limited to, land necessary for the
installation and construction of storm drainage facilities and all other facilities that are reasonably
required for proper and adequate management of stormwater for the benefit of the service area
• The costs of monitoring, inspection, enforcement, and administration of the utility including, but not
limited to, water quality surveillance, private system maintenance inspection, construction
inspection, and other activities that are reasonably required for the proper and adequate
implementation of the City’s stormwater and surface water policies
2.1.2.1 Rates
The currently established rates for the storm drainage service are provided in Table 2-1 below, which
lists rates for 2015 and 2016. Base rates are the monthly charge for service from the Storm Drainage
Utility to recover costs incurred by the utility such as administrative, billing, and collection. Equivalent
service units (ESU) are used as a means for estimating the development or impervious surfaces
estimated to contribute an amount of runoff to the City’s storm drainage system, which is approximately
equal to that which is created by the average single-family residential parcel. “Impervious,” as defined by
the City (see ACC Chapter 13.41), is a hard surface area that prevents the entry of water into the soil
mantle. Common impervious surfaces include, but are not limited to, rooftops, walkways, patios,
concrete, or asphalt paving. Open, uncovered, retention/detention facilities shall not be considered as
impervious surfaces for the purpose of ESU calculations. One ESU is equal to 2,600 square feet of
impervious surface area or any portion thereof. Table 2-1 provides the current monthly charges, base
rates, and ESU monthly rates for classifications used by the utility.
Table 2-1. 2015 and 2016 Utility Rates for Storm Drainage Service
Single-family parcel types Effective as of January 1, 2015 Effective as of January 1, 2016
Monthly charge Monthly charge
Single-family residential parcelsa $19.25 $19.73
Two-family residential parcelsb 19.25 19.73
Non-single-family parcels Base rate per month, $ ESUs per month Base rate per month, $ ESUs per month
Non-single-family (NSF)c $11.97 $15.32 $12.27 $15.71
NSF with detentiond 11.97 12.31 12.27 12.62
NSF with retentione 11.97 7.61 12.27 7.80
NSF with water quality treatmentf 11.97 9.21 12.27 9.44
NSF with detention and water quality treatment 11.97 6.95 12.27 7.13
NSF with retention and water quality treatment 11.97 4.35 12.27 4.46
a. Any parcel of land having on it a single detached dwelling unit that is designed for occupancy by one family or a similar group of people.
b. A building designed exclusively for occupancy by two families living independently of each other, and containing two dwelling units.
c. Any parcel of developed land other than single-family or two-family (duplex) residential.
d. Detention is the temporary storage of stormwater and surface water runoff with provisions for the controlled offsite surface release of the
stored water.
e. Retention means the storage of stormwater and surface water runoff with no provisions for offsite surface release of the stored water
other than by evaporation and infiltration.
f. Water quality treatment means an engineered and approved facility to remove contaminants in the existing flow regime of stormwater
generated from a developed parcel pursuant to applicable design standards in place at the time of approval.
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Storm Drainage Utility rates are billed on a monthly basis. Storm drainage charges start from the day a
water meter servicing the property is installed by the City. In cases where the property does not receive
water service from the City, storm drainage charges start from the day that the storm drainage permit is
finalized by the City. Payments received for utility bills are applied to expenses in the following order of
priority: late charges, additional fees, stormwater, garbage, sewer, and water. Payment for stormwater
drainage service charges is due and payable to the Finance Department office 15 days after the billing
date appearing on the bill. Utility charges are constituted as a lien, and thus can be applied to a lien
upon the property from which such charges are due, superior to all other liens and encumbrances
whatsoever, except for general taxes and local special assessments.
2.1.2.2 Fees
The City has permit fees and connection fees. Permit fees are applied to cover the planning, checking,
inspection, record drawings, and processing of permit information for new connections to the public
storm drainage system. A repair permit fee is applied to cover inspection and processing of permit
information for repairs conducted to private storm drainage systems.
Connection fees are charges in lieu of assessments. Such fees can be applied to properties that have
not previously paid for storm drainage systems abutting their property, but intend to connect to it. The
City determines the charge in lieu of assessment amount based on the property’s proportional share of
the calculated cost for the storm drainage system. Properties connected to storm drainage systems
constructed prior to 1987 are not required to pay a charge in lieu of assessment, unless required to do
so under an existing agreement. The City rarely charges connection fees for stormwater, but rather a
system development charge (SDC) at the time a new customer joins into the system (see the following
section).
2.1.2.3 System Development Charge
A utility SDC is a charge imposed on new customers, or existing customers revising use of their property,
in recognition of the previous investment of the City and its customers in the utility systems. The purpose
of an SDC is to recover a fair share of the costs of providing existing utility system infrastructure to serve
new customers or revised uses of existing customers and provide for future improvements to serve new
customers. As with Storm Drainage Utility rates, SDCs are based on the relative amount of impervious
surface added to the system. In 2014, SDCs were estimated to be $1,162 per ESU (see Section 2.1.2.1
for a definition of ESU).
Development Code and Design Standards Updates 2.2
In compliance with the requirements of the 2007–12 NPDES Permit (as discussed in Section 2.3.2), the
City conducted substantive updates to its development regulations and design standards contained
within the ACC, including the City’s Zoning Code, Subdivision Code, and Engineering Design Standards.
The City also revised related stormwater standards, policies, and practices, and adopted a stormwater
manual as required by the Permit. Specifically, the City adopted the Auburn Surface Water Management
Manual (SWMM), which is a modified version of the City of Tacoma’s 2008 Surface Water Management
Manual (approved by the Washington State Department of Ecology [Ecology] as an equivalent manual).
In August 2012, Ecology issued an updated NPDES Permit to comply with requirements of the federal
Clean Water Act (CWA). The new NPDES Permit became effective on August 1, 2013, and is effective
through July 31, 2018. In January 2015, a modified version of the NPDES Permit was issued to
incorporate outcomes from the permit appeals process, which were not significant for the City. To comply
with updated requirements of the reissued NPDES Permit, the City will be required to pursue further
updates to the ACC and stormwater standards.
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Updates to City codes, standards, and policies are anticipated to:
• Incorporate low-impact development (LID) principles, making LID the preferred way of managing
stormwater runoff from future development and redevelopment
• Reflect updated stormwater facility requirements for new development and redevelopment
• Accommodate new and more frequent inspections of permanent stormwater infrastructure,
including public and private stormwater facilities
• Incorporate required changes to other City stormwater program elements, including illicit discharge
detection and elimination (IDDE), public outreach and education, and monitoring
Development regulations related to stormwater and drainage design standards will also be reviewed for
potential revision consistent with current policies and LOS goals.
See the following section for an overview of the City Stormwater Management Program (SWMP) and
Chapter 8 for specific steps needed to maintain compliance with updated NPDES Permit requirements.
Regulatory Considerations 2.3
Numerous federal, state, and local regulations can affect stormwater management in the city. Table 2-2
summarizes a number of the applicable regulations.
Table 2-2. Federal, State, and City Regulations and Programs Relevant to the Auburn Storm Drainage Utility
Title Regulation
or program Application to the City
Federal
Clean Water Act (CWA): §402 NPDES
Permit Regulation The NPDES Permit includes a number of requirements that affect stormwater
management in the city. See Section 2.3.2 below.
CWA: §303(d) total maximum daily load
(TMDL) listing Regulation TMDLs could lead to more stringent stormwater quality controls in future NPDES Permits.
CWA: §404 permit requirements Regulation
Some stormwater capital improvement projects can affect wetlands or other “waters of
the U.S.” §404 permitting and mitigation can increase capital improvement project costs
and schedules.
Endangered Species Act (ESA) Regulation
Stormwater capital improvement projects that involve federal permitting or funding could
require consultation with federal agencies under §7 of the ESA. ESA consultation could
increase project timelines and costs.
National Flood Insurance Program Program The Drainage Plan could affect the City’s rating under the Community Rating System,
which affects flood insurance rates.
Governmental Accounting Standards
Board (GASB) Statement 34 Program Requires accurate inventory of City’s stormwater infrastructure. See Section 2.3.3 below.
State
State Environmental Policy Act (SEPA) Regulation Each capital improvement project would require SEPA review prior to implementation,
unless that project qualifies as exempt.
Water quality standards Regulation
The NPDES Permit does not authorize discharges that would violate State water quality
standards. The State may establish TMDLs for water bodies that violate the standards. As
noted above, the TMDLs can become NPDES Permit requirements.
§401 water quality certification Regulation
Individual projects that require §404 or other federal permits would also require a 401
certification from Ecology. A 401 certification could include site-specific mitigation
measures, which could affect capital improvement project design and cost estimates.
Puget Sound Water Quality Management
Plan Program Drainage Plan recommendations should be consistent with the Puget Sound Water
Quality Management Plan.
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Table 2-2. Federal, State, and City Regulations and Programs Relevant to the Auburn Storm Drainage Utility
Title Regulation
or program Application to the City
Puget Sound Partnership Program
In 2007, the Washington State Legislature created a State agency for the purpose of
developing and overseeing the implementation of a 2014/2015 “Action Agenda” to
clean up, restore, and protect Puget Sound by 2020. The Partnership’s “Action Agenda”
identified three priorities, one of which is to prevent pollution from urban stormwater
runoff.
GMA and City Comprehensive Plan Regulation This Drainage Plan is required by the GMA. GMA is discussed in Section 2.3.1 below.
State Hydraulic Code Regulation
Capital improvement projects that involve work in waters of the state would require a
Hydraulic Project Approval (HPA) permit. HPA permitting and mitigation measures could
affect capital improvement project costs.
Archaeological and cultural coordination Regulation
If any capital improvement projects are planned for areas with known or suspected
archaeological sites, the City will need to coordinate with the Department of Archaeology
and Historic Preservation, local Indian tribes, and King County Historic Preservation.
City
Environmental review Regulation
Each capital improvement project would be subject to environmental review prior to
permitting and construction as prescribed in ACC 16.06. This chapter of the ACC was
adopted under the authority of SEPA.
Critical areas ordinance Regulation
The Drainage Plan should avoid capital improvement projects in critical areas (e.g.,
wetlands, groundwater protection zones, or wildlife habitat). If a capital improvement
project must be sited in a critical area, the cost estimate should include costs for
mitigation and permitting as prescribed in ACC 16.10.
Development regulations Regulation The City’s development regulations must be consistent with NPDES Permit requirements.
Shoreline Master Program Regulation
Future projects should be located and designed to be consistent with the City shoreline
regulations (ACC 16.08). Projects within designated shorelines could require permits and
mitigation, which could affect project costs and schedules.
Most of the regulations listed in Table 2-2 primarily affect the implementation of specific measures
recommended in the Drainage Plan. For example, capital improvement projects that could affect
wetlands would need to comply with City critical areas regulations and possibly federal CWA Section 404
regulations. However, three of the regulations listed in Table 2-2—the GMA, Ecology’s Phase II NPDES
Stormwater Permit, and federal GASB Statement 34—directly affect the LOS for this Drainage Plan.
These regulations are discussed in greater detail in Sections 2.3.1 through 2.3.3 below.
2.3.1 Growth Management Act
The Washington State Legislature enacted the GMA in 1990 in response to rapid population growth and
concerns with suburban sprawl, environmental protection, quality of life, and related issues. The GMA is
codified primarily in RCW Chapter 36.70A.
The GMA provides a framework for regional coordination, and counties planning under the GMA are
required to adopt countywide planning policies to guide plan adoption within the county and to establish
urban growth areas. Local comprehensive plans must include the following elements: land use, housing,
capital facilities, utilities, transportation, economic development, parks and recreation, and, for counties,
a rural element. This Drainage Plan serves as the capital facilities element for City-owned storm drainage
assets.
RCW 36.70A.070 requires capital facilities elements to include:
• An inventory of existing capital facilities owned by public entities, showing the locations and
capacities of the capital facilities.
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• A forecast of the future needs for such capital facilities.
• The proposed locations and capacities of expanded or new capital facilities.
• At least a 6-year plan that will finance such capital facilities within projected funding capacities and
clearly identifies sources of public money for such purposes.
• A requirement to reassess the land use element if probable funding falls short of meeting existing
needs and to ensure that the land use element, capital facilities plan element, and financing plan
within the capital facilities plan element are coordinated and consistent. Parks and recreation
facilities shall be included in the capital facilities plan element.
To facilitate meeting the above requirements, Washington Administrative Code (WAC) Section 365-196-
415 recommends:
• An inventory of existing capital facilities showing locations and capacities, including the extent to
which existing facilities have available capacity for future growth. The inventory should be
periodically reviewed and updated.
• A forecast of capital facilities (including general location and capacity) needed during the planning
period, based on the LOS or planning assumptions selected and consistent with the growth,
densities, and distribution of growth anticipated in the land use element.
• The creation of at least a 6-year capital facilities plan for financing capital facilities needed within
that time frame. Projected funding capacities based on revenues available under existing laws and
ordinances, are to be evaluated, followed by the identification of sources of public or private funds
for which there is reasonable assurance of availability. The 6-year plan should be updated at least
biennially so that financial planning remains sufficiently ahead of the present for concurrency to be
evaluated.
• A provision should be made to reassess the land use element and other elements of the plan if the
probable funding for capital facilities is insufficient to meet development needs. If the reassessment
identifies a lack of public facilities, a variety of strategies may be implemented including reducing
LOS and increasing revenue.
2.3.2 Phase II Municipal Stormwater Permit
The NPDES permit program is a requirement of the federal CWA, which is intended to protect and restore
waters for “fishable, swimmable” uses. The federal Environmental Protection Agency (EPA) has
delegated permit authority to state environmental agencies, and these agencies can set permit
conditions in accordance with and in addition to the minimum federal requirements. In Washington,
Ecology is the NPDES-delegated Permit authority.
Phase I of the stormwater NPDES regulation applies to cities and counties that operate municipal
separate storm sewer systems (MS4s) and had populations of 100,000 people or more according to the
1990 census. Phase II of the stormwater NPDES regulation applies to municipalities that operate MS4s
and have populations of fewer than 100,000 people. Auburn is a Phase II permittee.
Ecology issued the initial Western Washington Phase II Municipal Stormwater Permit (NPDES Permit) in
February 2007, a subsequent updated NPDES Permit in August 2012, and a further modified version in
January 2015 (Appendix A). The Permit requires the City to submit a SWMP Plan by March 31 of each
year, in which the City identifies activities to be completed in compliance with the Permit requirements.
The Permit also requires submittal of an annual report that looks back on SWMP activities for the prior
year.
Implementation of updated NPDES Permit conditions is staggered throughout the 5-year Permit term
from August 1, 2013, through July 31, 2018. The NPDES Permit will again be revised and reissued at the
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end of this period. The NPDES Permit and associated requirements are described in detail in the City’s
current SWMP Plan available on the City’s website.
The NPDES Permit allows municipalities to discharge stormwater runoff from their municipal drainage
systems into the state’s water bodies (e.g., streams, rivers, lakes, and wetlands) as long as
municipalities implement programs to protect water quality by reducing the discharge of “nonpoint
source” pollutants to the “maximum extent practicable” (MEP) through application of Permit-specified
“best management practices” (BMPs). The stormwater management activities specified in the NPDES
Permit are collectively referred to as the SWMP and grouped under the following program components:
• SWMP administration
• Public education and outreach
• Public involvement and participation
• IDDE
• Control of runoff from new development, redevelopment, and construction sites
• Municipal operations and maintenance
• Monitoring and assessment
The NPDES Permit also requires compliance with established total maximum daily loads (TMDLs)2. The
current NPDES Permit requires the City to monitor discharges to the White River, in association with the
Puyallup River watershed fecal coliform TMDL. Ecology has identified several other water bodies in the
vicinity of Auburn that do not appear to meet the water quality standards, and additional TMDL
requirements are possible in future Permits.
2.3.3 Governmental Accounting Standards Board
Financial reporting by public utilities must adhere to requirements set by the GASB, the agency
responsible for developing standards of state and local governmental accounting and financial reporting.
Most prominent is GASB Statement 34, “Basic Financial Statements—and Management’s Discussion
and Analysis—for State and Local Governments,” which was issued in June 1999. The main objective of
Statement 34’s requirements is to have financial reports that are more comprehensive and are easier to
understand by the public. Statement 34 consists of several components, which can be seen in full in
paragraphs 3–166 of the GASB publications. In summary, Statement 34 requires that the basic financial
statements and required supplementary information (RSI) for general purpose governments should
consist of the following:
• Management’s discussion and analysis. In sum, this requirement states that prior to the basic
financial statements, a discussion providing an analytical overview of the government’s financial
activities is necessary.
• Basic financial statements, which should include:
− Government-wide financial statements that include information on net assets (e.g., storm
drainage infrastructure) and a statement of activities.
2 A TMDL is a calculated maximum pollutant loading a water body can receive while still meeting water quality standards. Once
a TMDL is established, the State determines how much each source must reduce its discharges of the pollutant in order to
bring the water body back into compliance with the water quality standards. The federal CWA requires that TMDLs be
established for all water bodies that do not meet water quality standards, and that TMDL requirements be included in the
NPDES permits for dischargers into the affected water bodies.
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− Fund financial statements that focus on information about the government’s major
governmental and enterprise funds (e.g., the City’s Storm Drainage Utility), including its blended
component units.
− Notes to the financial statements that will enable users to understand the basic financial
statements.
• Required supplementary information. Budgetary comparison schedules should be presented as RSI
along with other types of data as required by previous GASB pronouncements.
Consequently, the City needs an accurate inventory of its stormwater infrastructure in order to comply
with the GASB 34 requirements.
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Chapter 3
Utility Policies and Level-of-Service
Goals
This chapter describes a set of guiding policies for the City’s Storm Drainage Utility and LOS goals for
complying with these policies. Level of service is generally defined as a community’s specific goals or
objectives for capital facility infrastructure development, operation, maintenance, and other key
elements of utility management. These goals provide a framework for the utility to assess its staffing
levels, prioritize its resources, justify its rate structure, and document its successes. LOS goals should
relate directly to Utility policies and include clear criteria to use in evaluating how well LOS goals are
being met.
The City has developed policies and LOS goals for the following elements of Storm Drainage Utility
operation:
• Business practices
• Protection of public safety and property
• Reliability of the storm drainage infrastructure
• Protection of the environment
• Financial performance of the utility
• Customer satisfaction
The remainder of this Chapter introduces the concept of LOS goals in storm drainage utilities and
presents the Storm Drainage Utility policies and specific LOS goals for the City.
Level-of-Service Goals within Storm Drainage Utilities 3.1
LOS goals defined by a storm drainage utility can relate to quality, quantity, reliability, responsiveness,
safety, environmental acceptability, and cost of delivering service. To serve as effective management
tools, LOS goals should be measurable. For example, a measurable “public health and safety” LOS goal
for drainage would be to ensure that flooding beyond a certain depth does not recur on critical traffic
routes more often than a target frequency (e.g., flooding that affects private property limited to an
average of once per 50 years). An example of an “environmental protection” LOS goal would be
compliance with all required elements of the City’s Phase II NPDES Stormwater Permit. In the latter
example, the NPDES Permit has embedded specific metrics for evaluating compliance (e.g.,
implementation of 95 percent of Permit-required stormwater facility inspections). In this instance, the
NPDES Permit is mandating that the City implement measurable LOS criteria.
By documenting LOS, a storm drainage utility provides a transparent set of metrics to elected officials
and the community, and can begin to communicate with stakeholders about rate implications associated
with increasing or decreasing service. Higher LOS standards result in greater costs to taxpayers,
ratepayers, and new development; lower LOS standards may result in lower rates but unacceptable
public safety, environmental stewardship, or regulatory compliance. LOS goals may be flexible;
communities should be willing to periodically revisit LOS goals to make sure that they are still
appropriate.
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Storm Drainage Utility Policies and Levels of Service 3.2
The Storm Drainage Utility policies and LOS goals are provided in Table 3-1 and are organized by
category.
Table 3-1. Storm Drainage Utility Policies and LOS Goals
Item Policy description 2015 Drainage Plan LOS goal
Policy category: business practices
1
The City desires to employ recognized best business
practices that result in the efficient and cost-effective
operation of the utility.
The City shall identify the key business functions within the utility (e.g., billing,
permitting, asset management, and planning) and develop supporting best
business practices for each. The utility will conduct a performance audit every 6
years in conjunction with its capital projects planning cycle to evaluate how well
best business practices are being implemented and how effective they are.
2
The City shall seek to employ the best practices for
asset management by systematically basing choices on
an understanding of asset performance, risks, and
costs in the long term.
The City shall begin implementing the following best practices for all stormwater
facilities during the next planning period and report progress annually:
• Have knowledge about assets and costs (i.e., detailed inventories and
condition assessments)
• Maintain desired levels of service confirmed by customers
• Take a life-cycle approach to asset management planning
Implement the planned solutions to provide reliable, cost-effective service
Policy category: protection of public safety and property
3
The City shall seek to manage stormwater runoff within
the public right-of-way (ROW) to allow access to and
functionality of critical services such as hospitals, fire
and police stations, Emergency Operations Center,
maintenance and operations, and City Hall.
Public drainage infrastructure will be designed and maintained so that the
annual chance of occurrence of surface water flooding that disrupts the function
of critical facilities (i.e., with floodwaters reaching the building structure,
damaging the structure, and permitting no ingress/egress) will be no greater
than 1% (i.e., an average recurrence interval of 100 years).
4
The City shall seek to manage stormwater runoff within
the public ROW to preserve mobility on major
transportation routes (i.e., arterial roads) and
residential roads.
Public drainage infrastructure will be designed and maintained so that the
annual chance of occurrence of flooding disruption that inundates city roadways
to an impassable level will be no greater than 4% (i.e., an average recurrence
interval of 25 years).
5
The City shall seek to manage stormwater runoff from
the public ROW to protect real property structures (e.g.,
residences and businesses).
Public drainage infrastructure will be designed and maintained so that the
annual chance of occurrence of flooding (surface water from ROW runoff entering
premises and damaging building structures) will be no greater than 2 percent
(i.e., an average recurrence interval of 50 years).
6
The City shall seek to prevent erosion and landslides
related to construction, operation, and maintenance of
the publicly owned drainage system.
Public drainage infrastructure will be constructed, operated, and maintained so
that there is no resulting erosion or landslides.
7
The City shall seek to maintain storm drainage
infrastructure to ensure proper function of drainage
facilities. The City shall seek to seasonally maintain
storm drain inlets, conveyance, and outfalls to preserve
design conveyance capacity.
The City will continue to refine its maintenance practices and reallocate staff as
needed to address seasonal concerns, with an emphasis on maintaining
facilities that have a high “consequence of failure.” An example would be
focusing extra M&O staff on catch basin inlet cleaning during autumn when
leaves are falling. All activities will be documented within the City’s Cartegraph
computerized maintenance management system (CMMS).
Policy category: reliability of the storm drainage infrastructure
8
The City shall seek to maintain an asset criticality
database to be used in prioritizing asset maintenance
and R&R.
The existing criticality database (developed for the 2008 Drainage Plan) will be
refined to include more asset information, such as pipe material, diameter, age,
consequence of failure, etc. The criticality database will be validated using the
results of previous and ongoing M&O inspections. Activities will be documented
within the City’s Cartegraph CMMS.
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Table 3-1. Storm Drainage Utility Policies and LOS Goals
Item Policy description 2015 Drainage Plan LOS goal
9 The City shall seek to perform condition assessments of
critical assets.
The City will develop and implement a condition assessment schedule for all
critical assets as identified through criticality analyses of stormwater
infrastructure assets. Criticality is based on the risk and consequences of failure.
Criticality data will be stored in a criticality database, and all condition
assessment activities will be documented in the City’s Cartegraph CMMS.
10 The City shall seek to repair or replace system assets
before they exceed their economic lives.
The number of high-criticality pipe segments beyond their economic lives will be
determined. After the criticality database inventory is complete, the City’s goal
will be to limit the number of pipe segments beyond their economic lives,
including setting specific numeric goals for replacement of those segments.
11
The City shall seek to conduct maintenance activities in
accordance with a schedule developed to comply with
Ecology requirements and asset criticality.
No deferred maintenance on all critical or Ecology-required assets. The City will
prioritize its inspection activities based on the combined “risk of failure” and
“consequence of failure” computed by the criticality database and meet current
NPDES inspection schedule (e.g., inspecting catch basins). The experience of
M&O staff should be incorporated into the criticality database (see item
8above). All inspection activities will be documented in the CMMS.
12
The City shall seek to maintain storm drainage
infrastructure to ensure proper function of drainage
facilities in accordance with Ecology requirements.
The City will develop a ditch maintenance program. The City will secure proper
permits as well as coordinate with other agencies for work in the associated
ROW. The ditch maintenance program will consist of inspecting and maintaining
all ditches within the permit cycle and then on an as-needed basis.
13
The City shall seek to manage stormwater runoff from
the public ROW with City-owned facilities located in the
public ROW or on City-owned property. The City shall
maintain or seek access to City-owned facilities for
necessary maintenance and operation.
The City’s Storm Drainage Utility will be responsible for maintenance and
operation of the City’s drainage system. The City shall seek to have access to all
City-owned drainage infrastructure. The City shall seek to obtain easements or
relocate infrastructure as necessary to maintain access.
Policy category: protection of the environment
14
The City shall seek to comply with all federal and state
regulations applied to stormwater management
activities.
Meet all requirements of the Western Washington Phase II Municipal Stormwater
Permit with no enforcement actions of the CWA for violations as a result of City
stormwater operations.
15
The City shall seek to provide pump redundancy and
backup power generators or dual power feeds at City-
owned and -operated drainage pump stations.
All pump stations will be designed with two or more pumps to ensure proper
function during maintenance. Backup and/or dual-feed power supplies will be
installed as needed.
16
The City shall seek to comply with all federal, state, and
local regulations in operation and maintenance of the
City’s storm drainage infrastructure.
Meet all specific targets. Examples include complying with NPDES Phase II
inspection cycle, performing all necessary ESA consultations, etc.
17
The City shall protect and preserve existing native
vegetation and drainage courses while maintaining
their conveyance capacity.
The City will maintain existing habitat along drainage ways so there is no net loss
of native vegetation (in terms of area) or natural drainage systems (in terms of
stream length). This does not apply to constructed or maintained facilities.
18
The City shall seek to comply with all federal, state, and
local regulations to reduce runoff volumes and
pollutant loads associated with new development and
redevelopment.
The City will comply with the elements of the Western Washington Phase II
Municipal Stormwater Permit and will adopt or implement the Ecology manual or
equivalent for new development and redevelopment.
19
The City shall place emphasis on onsite approaches
such as LID as the first consideration for runoff and
pollutant load reduction for new development and
redevelopment.
The City will identify feasibility criteria and provide guidance for the
implementation of LID drainage management measures for new development
and redevelopment (including City-owned properties).
20 The City shall seek to evaluate Storm Drainage Utility
activities to emphasize sustainability.
City staff will identify specific areas to measure sustainability by examining how
Storm Drainage Utility operations affect energy resources, natural resources,
and the community. City staff will benchmark practices and log changes over the
next planning period.
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Table 3-1. Storm Drainage Utility Policies and LOS Goals
Item Policy description 2015 Drainage Plan LOS goal
21
The City shall continue to participate in regional storm
drainage, water resources, and water quality planning
efforts.
The City will continue to actively participate in developing and implementing
regional water quality planning and flood hazard reduction efforts within the
Green River, Mill Creek, and White River drainage basins. The City will participate
in the state’s water quality monitoring program.
22
The City shall comply with all federal, state, and local
regulations in the inspection of the City’s publicly
owned storm drainage infrastructure and privately
owned LID facilities.
For all new LID systems constructed after 2016, the City will develop authority
and an inspection frequency for stormwater facilities developed in compliance
with the NPDES Phase II Stormwater Permit. The City will develop an inspection
assessment database to monitor and schedule facility maintenance for all
publicly owned storm drainage infrastructure and privately owned LID facilities.
This database will provide maintenance information for the criticality database
in the City’s Cartegraph CMMS.
Policy category: Storm Drainage Utility financial performance
23
The City shall continue to fund and provide storm
drainage services through the existing Storm Drainage
Utility..
The City’s Storm Drainage Utility should be responsible for implementation,
maintenance, and operation of the City’s drainage system, with a goal of 100%
of the cost of drainage service delivery recovered via Storm Drainage Utility fees.
Seek opportunities to provide public drainage benefits through grant funding
and/or development partnerships where applicable.
24
The City shall assess appropriate rates and SDCs to
fund the ongoing maintenance, operation, and capital
expenditures of the utility, in accordance with the
Drainage Plan.
Periodic cost-of-service studies shall be completed to reassess the monthly
service fees and SDCs. Updates to coincide with all 6-year CIP updates.
25 The City shall seek to track the cost of claims as a
metric.
City staff will summarize the annual costs of claims for the recent past to
establish a baseline measurement of existing practices. If the current costs are
deemed excessive, City staff will evaluate methods to reduce the risk of claims
and measure its progress at reducing the overall cost of claims.
26
The City shall seek to track elements of capital
improvement project implementation: (1) individual
schedule, (2) project budget accuracy, and (3) overall
performance in implementing CIP.
City staff will summarize current methods for capital improvement project
implementation to create a baseline (e.g., schedule and costs) against which
future improvements can be evaluated.
Policy category: customer satisfaction
27
The City shall seek to evaluate and strive to maintain
customer satisfaction with Storm Drainage Utility
service delivery.
To effectively measure the public perception of utility performance, City staff will
conduct the following: (1) summarize annual customer complaint reports, (2)
communicate proactively with community and stakeholders regarding drainage
infrastructure improvements, and (3) comply with Western Washington Phase II
Municipal Stormwater Permit requirements for public education and outreach.
28
The City shall seek to build, operate, and maintain
storm drainage infrastructure within an overarching
goal of protecting employee safety.
City staff will track health and safety incidents to create a baseline against which
to evaluate future improvements.
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Chapter 4
Drainage System
Chapter 3 lays out clear LOS goals for the Storm Drainage Utility. The next step toward developing a
future work plan is to collect and organize information describing the current conditions of the storm
drainage system. This information provides the basis for investigations (Chapter 5) designed to evaluate
the Storm Drainage Utility performance relative to the LOS goals. This chapter provides an overview of
the City’s drainage system including both natural (Section 4.1) and constructed (Section 4.2) drainage
elements.
Figures presented in this chapter consist of several maps of the Storm Drainage Utility service, drainage,
and surrounding areas. These figures are presented at the end of the chapter.
Natural Drainage 4.1
The City of Auburn encompasses approximately 30 square miles; the central portion of the city lies along
the bottom of a valley, while the outer edges of the city extend into the surrounding hills (see Figure 4-1).
In general, stormwater runoff from the city flows to one of three major receiving waters: Green River,
White River, and Mill Creek. Other notable water features in the Auburn area include the following:
• Big Soos Creek, which drains southeast into the Green River
• Soosette Creek (also known as Little Soos Creek), which drains south into Big Soos Creek
• Mullen Slough, which drains along the northwest side of Mill Creek toward the Green River
• Bowman Creek, which drains north into the White River
• Olson Creek, which drains west into the Green River
• Lake Tapps, which is located just south of the city
• White Lake, which is located southeast of R Street SE and State Route (SR) 18
• Coal Creek Springs, which drains north to the White River
The city contains nearly 30 miles of rivers and streams and more than 1,000 acres of floodplain area
associated with these water features. There are over 1,500 acres of wetlands, including forested/shrub
and freshwater emergent wetlands.
The following sections provide additional information on each of the three major receiving waters.
4.1.1 Green River
The Green River flows over 93 miles beginning on the west slope of the Cascade Mountains and ending
in the Duwamish Waterway, meandering through the northeast portion of Auburn along the east valley
wall. Throughout the last century, the Green River was altered for the purpose of flood control, including
the construction of levees and bank revetments, and the diversion of the White River in the early 1900s.
In 1962, the Howard A. Hanson Dam was built on the Green River to control flooding in the valley.
From 1960 to 2007, the City of Auburn participated in Green River flood management activities as part
of the Green River Flood Control District. In 2007, the Green River Flood Control District was phased out
as flood control and management efforts for the Green River are now included in the King County Flood
Control District (KCFCD), which was established in 2007. These efforts are reflected in the 2006 King
County Flood Hazard Management Plan. The KCFCD goals and objectives include maintaining and
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repairing levees and revetments and acquiring at-risk floodplain properties. Auburn elected officials and
staff serve on advisory committees for the KCFCD such as the Green River System Wide Improvement
Framework (Green River SWIF). The goal of the Green River SWIF is to recommend and prioritize a set of
capital projects and programs for flood protection for the Lower Green River.
4.1.2 White River
The White River originates on the slopes of Mount Rainier and flows generally northward and westward
into the Puget Sound lowlands. Near Auburn, the White River flows north and then west through the
southern portions of the city before it curves southward toward the Puyallup River. The White River is a
very dynamic, sediment-laden river, which has led to changing channel morphology.
Prior to 1900, the White River flowed into the Green-Duwamish River; however, floodwaters from the
White River drained to both the Green-Duwamish River and the Puyallup River. A flood in 1906 caused
the White River to shift and flow into the old Stuck River channel, which leads to the Puyallup River. In
1907, a diversion wall located within Game Farm Park was constructed to permanently direct the White
River flow into the Puyallup River (USACE, October 2009).
The shifting of floodwaters from the White River caused inter-jurisdictional conflicts between King and
Pierce counties. After attempts by the two counties to control flooding along the White River met with
limited success, the U.S. Army Corps of Engineers (USACE) was engaged for help. In 1948, the USACE
finished construction of the Mud Mountain Dam to control floods on the White River.
At the time Mud Mountain Dam was finished, White River channel capacity in the area of Auburn was
estimated to be 20,000 cfs. Since then, vegetation encroachment and sediment accumulation have
reduced channel capacity (USACE, October 2009). Reduced channel capacity causes higher river levels
during large storm events, which can impact the City’s gravity drainage outfalls along the White River.
4.1.3 Mill Creek
Mill Creek flows out of the hills on the west side of the valley near SR 18, and then turns northward along
the western portion of the city, running adjacent to SR 167. It crosses under SR 167 several times as it
flows through the valley floor. Approximately 1 mile north of the city boundary, Mill Creek discharges into
the Green River.
Historically, Mill Creek served as vital habitat for migrating salmon and provided ideal conditions for
rearing and storm refuge. However, increasing development has altered the natural flow pattern of Mill
Creek, including the installation of diversions and culverts, channel straightening, degradation of water
quality, and aggradation from increased stormwater inflows with high sediment loads. In many areas the
stream is straight and shallow, and exhibits a lack of quality riparian habitat for Endangered Species Act
(ESA)-listed species such as Chinook salmon and bull trout (USACE, April 2009). Aggradation along Mill
Creek has also contributed to flooding and drainage problems in the city. The City’s drainage outfalls to
Mill Creek can become submerged, thereby reducing the hydraulic capacity of the system.
The USACE and the City have initiated a restoration project, called the Mill Creek 5K Reach Restoration
Project, for the reach of Mill Creek on the west side of SR 167 extending from Main Street to north of the
15th Street NW culvert. The project includes constructing a new creek channel and replacing the culvert
at 15th Street NW. In addition to improving fish passage and flow conveyance through the culvert, the
project will reduce flood elevations along Mill Creek.
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4.1.4 Drainage Areas
The city’s drainage can be described by dividing the city into six general sub-areas3 and their discharge
location (Figure 4-2):
• Lea Hill lies northeast of the Green River. Most of the Lea Hill area drains west into the Green River.
However, the eastern edge drains south and east out of the city into Soosette Creek and Big Soos
Creek.
• West Hill lies west of Mill Creek. The West Hill area drains into several small tributaries to Mill Creek.
The northern portion of West Hill drains to the northeast into steep ravines that discharge to Mullen
Slough and other wetland areas on the valley floor.
• The Southern portion of the city drains to the White River. The area west of Bowman Creek consists
largely of the Lakeland Hills developments, which drain to the White River to the west and north,
Bowman Creek to the east, and a small portion that drains south toward Lake Tapps. The area east
of Bowman Creek consists of rural residential development; this area drains to Bowman Creek on
the southwest and the White River on the northeast side.
• The Southeast portion of the city lies along a narrow plateau between the Green and White rivers.
Runoff from this area drains to the Green River along the north side and the White River along the
south side.
• The North Central portion of the city lies along the valley floor and is located north of 27th Street SE.
This is part of the central and most developed area of the city. The topography in this area is so flat
that roadways and storm drainage infrastructure largely determine the receiving water to which
runoff is diverted. Runoff from this area is generally split between Mill Creek and the Green River.
• The South Central portion of the city also lies along the valley floor and is located south of 27th
Street SE. This area is also part of the most developed area of the city. The topography in this area is
so flat that roadways and storm drainage infrastructure largely determine the receiving water to
which runoff is directed. This area, plus the Boeing property drains to the White River.
The above-described areas can be divided into smaller drainage subbasins. For the 2002 Comprehensive
Drainage Plan (Tetra Tech, 2002) subbasins were delineated such that the entire Storm Drainage Utility
was covered, resulting in a total of 61 drainage subbasins covering approximately 34 square miles. Each
subbasin is identified by a series of one, two, or three letters (Figure 4-2).
4.1.5 Climate and Precipitation
Auburn’s climate is typical of that in the Puget Sound lowlands of Western Washington, where the
summers are cool and comparatively dry, while the winters are mild, wet, and cloudy (Western Regional
Climate Center [WRCC], 2014a). Mean annual precipitation in the Puget Sound lowlands varies from 32
inches (north Seattle) to approximately 47 inches (near Centralia, Washington).
The precipitation gauge at Auburn City Hall has been recording data since 1995. The mean annual
precipitation recorded at that gauge (with missing data filled in from the nearby King County Lakeland
Hills gauge) from 1995 to 2014 was approximately 38 inches. This is very similar to the mean annual
precipitation recorded at the two nearest long-term gauges:
3 For the purposes of this Drainage Plan, sub-areas are generally defined areas within the city that do not have clearly defined
boundaries such as those of a basin or subbasin, which can be delineated based on topographic information. Sub-areas are
defined for the purpose of general discussion and are not used for specific evaluations or analyses.
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• Seattle-Tacoma Airport, which is part of the National Oceanic and Atmospheric Administration
(NOAA) Cooperative Network (Station 457473), has a mean annual precipitation of approximately 38
inches based on 74 years of recorded data (WRCC, 2014b). The Seattle-Tacoma Airport gauge is
located approximately 8 miles northwest of Auburn.
• Kent, Washington (NOAA Co-op Station 454169) has a mean annual precipitation of approximately
39 inches based on 57 years of recorded data (WRCC, 2014c). The Kent gauge is located
approximately 7 miles north of Auburn.
Precipitation-frequency data for Washington are compiled in Volume 9 of NOAA Atlas 2 (Miller, Frederick
and Tracey, 1973); precipitation-frequency estimates for Auburn, Washington, are listed in Table 4-1.
Table 4-1. Precipitation Frequency Data for Auburn, Washington, from NOAA Atlas 2
Frequency, duration Precipitation (inches)
2-year, 6-hour 0.95
2-year, 24-hour 1.75
100-year, 6-hour 1.90
100-year, 24-hour 3.80
4.1.6 Geology and Groundwater
Topography and geology in the Auburn region has been influenced largely by millions of years of
advancing and retreating glaciers, most recently with the Vashon glaciation occurring approximately
12,000–18,000 years ago (Booth, 1991). Following the retreat of the glacier, interglacial processes
such as landslides, mudflows, erosion, and alluvial deposition have continued to shape the region. In
general, the upland hills around the city’s periphery comprise glacial and interglacial deposits, while the
valley is filled with more recent deposits overlying glacial and older interglacial deposits.
Major geologic units of the White and Green River Valley include undifferentiated glacial and interglacial
deposits, Vashon recessional deltaic deposits, undifferentiated alluvium, Osceola mudflow, and White
River alluvium. The undifferentiated glacial and interglacial deposits form the lowest layer in the valley
consist of materials deposited during the glacial periods. As the glacier retreated, meltwater flowed into
a water-filled embayment then occupying the present White and Green River Valley area. This meltwater
deposited sand and gravel known as the Vashon recessional deltaic deposits. After the end of the glacial
period, the Green River deposited undifferentiated alluvium in the valley as a result of erosion of upland
glacial deposits. Approximately 5,700 years ago, a massive volcanic mudflow from Mount Rainier, known
as the Osceola mudflow, flowed down into the valley (Troost and Booth, 2008). White River alluvium is
the geologic unit nearest the surface and consists of alluvial deposits from the White and Green rivers.
Bedrock is found approximately 1,280 feet beneath the valley floor. Surficial geologic mapping of the
Auburn region is shown in Figure 4-3.
In general, groundwater flow systems in the Auburn area are characterized by upland recharge flowing
toward the valley. The two major aquifers in the White and Green River Valley are the modern alluvium
aquifer and a deep deltaic valley aquifer; the latter is used for Auburn’s water supply. The modern
alluvium aquifer is the shallowest aquifer in the Auburn-Kent Valley, often lying 10 to 15 feet below the
ground surface. Groundwater in the deep deltaic valley generally flows in a pattern parallel to the
direction of the Green River in the north and the White River in the south.
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4.1.7 Soils and Runoff Potential
Surface soils are classified by the Natural Resources Conservation Service (NRCS) into four hydrologic
soil groups based on the soil’s runoff potential: A, B, C, and D. Group A soils generally have the lowest
runoff potential while Group D soils have the highest. Hydrologic soil groups are defined by NRCS (1986)
as follows:
• Group A is sand, loamy sand, or sandy loam types of soils. It has low runoff potential and high
infiltration rates, even when thoroughly wetted. It consists chiefly of deep, well to excessively drained
sands or gravels and has a high rate of water transmission.
• Group B is silt loam or loam. It has a moderate infiltration rate when thoroughly wetted and consists
chiefly of moderately deep to deep, moderately well to well drained soils with moderately fine to
moderately coarse textures.
• Group C is sandy clay loam. It has low infiltration rates when thoroughly wetted and consists chiefly
of soils with a layer that impedes downward movement of water and soils with moderately fine to
fine structure.
• Group D is clay loam, silty clay loam, sandy clay, silty clay, or clay. It has very low infiltration rates
when thoroughly wetted and consists chiefly of clay soils with a high swelling potential, soils with a
permanent high water table, soils with a claypan or clay layer at or near the surface, and shallow
soils over nearly impervious material.
For Auburn and the surrounding areas, the valley floor is mostly Group D soils, which typically have very
low infiltration rates and high runoff potential. The West Hill, Lea Hill, and Lakeland Hills areas are
predominantly Group C soils, which have low infiltration rates and moderate to high runoff potential. The
Southeast area, Bowman Creek area, and valley area located generally between SR 18 and the White
River have Group A soils, which are characterized by high infiltration rates and low runoff potential. See
the NRCS maps (http://www.nrcs.usda.gov/) for mapped soils within the city.
4.1.8 Land Use and Development
Land use and the intensity of development have considerable effects on the quality and quantity of
stormwater runoff flowing into the drainage system and ultimately discharging to receiving waters. As the
population of the city increases, new areas of the city are developed or existing areas are redeveloped at
a higher density. These changes can result in increased stormwater runoff and greater water quality
impacts to water bodies. However, development regulations and drainage design standards imposed by
the City are intended to mitigate these impacts. The following sections describe expected growth and
how development regulations and design standards are being updated to reduce impacts to stormwater
runoff.
4.1.8.1 Recent Growth
Auburn’s population has steadily increased since the 1950s. Auburn’s population increased by an
average of 8 percent per year from 1960 to 1980, then slowed to approximately 1.7 percent per year
from 1980 to 1994. Auburn’s population growth rate began to increase in 1998, as the City began
annexing new areas, which precipitated several large housing developments. The Washington State
Office of Financial Management indicates that Auburn’s population in 2014 was approximately 74,600
(approximately 65,300 in King County and 9,300 in Pierce County).
4.1.8.2 Future Growth
The City’s goals, objectives, and policies for growth and development are described in detail in the 2015
Comp Plan. These goals, objectives, and policies are applied to different areas of the city through land
use designations (see Figure 4-4). The City also has developed special land use plans for certain areas of
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the city where specific land use goals have been identified. An important example is the city’s downtown
area; one of the goals described in the Comp Plan is to encourage development and redevelopment in
the downtown area to serve as an urban center for the community.
4.1.8.3 Development Regulations and Drainage Design Standards
The City implements state and federal stormwater regulations through the stormwater code, the Auburn
SWMM, and related stormwater management programs and policies. City stormwater regulations
contain specific requirements for managing stormwater quality and quantity in areas subject to new
development and redevelopment. For example, the SWMM provides guidance for implementing LID
measures that are designed both to improve water quality and to control peak flows and durations of
runoff. The City is in the process of updating its local development regulations and drainage standards in
accordance with updated NPDES Permit requirements.
City stormwater regulations and development standards are intended to avoid substantial increases in
stormwater discharges to the existing drainage system through the implementation of onsite stormwater
controls. Ideally, this would keep stormwater conveyance demands at or near existing levels.
4.1.9 Flood Hazard Mapping
The City of Auburn is a participant in the National Flood Insurance Program (NFIP) administered through
the Federal Emergency Management Agency (FEMA) to enable property owners to purchase insurance
protection from the government against losses from flooding. Participation in the NFIP is based on an
agreement between the City and the federal government, stating that if the City adopts and enforces a
floodplain management ordinance to reduce future flood risks to new construction in areas designated
as Special Flood Hazard Areas (SFHA), the federal government will make flood insurance available within
the community as a financial protection against flood losses. The SFHAs and other risk premium zones
applicable to each participating community are depicted on Flood Insurance Rate Maps (FIRMs).
FEMA established flood hazard zones from a Flood Insurance Study (FIS) for King County conducted in
2013, which examined flooding along several major rivers. Although the primary purpose of the FIS was
to establish flood insurance rates, the flood mapping resulting from these studies is also used for
floodplain management and flood hazard mitigation planning. Updates to the flood hazard zones are
continually being made at local levels (King County and Pierce County) and represented in Preliminary
FIRMs or Letters of Map Revision (LOMR). Preliminary FIRMs for all of King County were reissued on
February 1, 2013. The most recent flood hazard mapping for Pierce County is presented in the County’s
“Rivers Flood Hazard Management Plan” adopted in 2013 and also in LOMR files located on the FEMA
Map Service Center Web page (Pierce County, 2013). Table 4-2 lists the Flood Insurance Rate Maps
developed for areas within the City of Auburn.
Table 4-2. FEMA Flood Insurance Rate Maps Applicable to Auburn
53033C1232K 53033C1253K 53033C1264K 5301380213C
53033C1235K 53033C1254K 53033C1266K 5301380375C
53033C1242K 53033C1261K 53033C1267K 5301380220C
53033C1251K 53033C1262K 53033C1268K 5301380351C
53033C1252K 53033C1263K 53033C1269K
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Stormwater Drainage Infrastructure 4.2
As part of the development of the 2009 Drainage Plan, the City embarked on a substantial effort to
update its inventory of drainage system infrastructure owned or operated by the Storm Drainage Utility.
Since that plan, the City has continued to update its inventory through dedicated field staff conducting
surveys. This effort will continue until field surveys have been completed citywide. A comprehensive
system inventory will provide the City with a database of infrastructure assets, which will achieve the
following objectives:
• Help to meet regulatory requirements
• Provide input for hydraulic models to analyze system conveyance capacity
• Serve as a basis for an asset criticality database used to prioritize repair and replacement (R&R)
activities
• Support the City’s M&O activities through the computerized maintenance management system
(CMMS)
Table 4-3 provides a summary of stormwater infrastructure inventory.
Table 4-3. Stormwater Drainage Infrastructure Summary
Infrastructure element GIS data type GIS feature class name Quantitya Unit
Pipes, all sizes Polyline Storm pipes 1,108,000 Linear feet
Pipes, all sizes (excluding force mains) Polyline Storm pipes 11,500 Count
6–10 in. diameter Polyline Storm pipes 2,300 Count
162,300 Linear feet
12–15 in. diameter Polyline Storm pipes 6,400 Count
547,500 Linear feet
16–18 in. diameter Polyline Storm pipes 1,100 Count
129,300 Linear feet
21–24 in. diameter Polyline Storm pipes 700 Count
96,900 Linear feet
27–36 in. diameter Polyline Storm pipes 400 Count
69,500 Linear feet
42–48 in. diameter Polyline Storm pipes 100 Count
32,700 Linear feet
54–72 in. diameter Polyline Storm pipes 10 Count
1,600 Linear feet
Force mains Polyline Storm pipes 23 Count
2,500 Linear feet
Open channels Polyline Storm channels 217,100 Linear feet
Culverts Polyline Storm culverts 38,400 Linear feet
Manholes Point Storm manholes 2,330 Count
Catch basins Point Storm catch basins 8,880 Count
Weirs Point Storm auxiliary equipment 1 Count
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Table 4-3. Stormwater Drainage Infrastructure Summary
Infrastructure element GIS data type GIS feature class name Quantitya Unit
Orifices Point
Storm manholes or storm
catch basin data,
where attribute flow control = yes
203 Count
Outfalls (to water courses, ditches, etc.) Point Storm outfalls 127 Count
Detention ponds Point Detention sites 139 Count
Infiltration ponds Point Detention sites 12 Count
Vaults Point Vault 17 Count
Pump stations Point Storm pumps 7 Count
a. Quantities are based on current inventory and have not yet been finalized.
Most of the storm drainage infrastructure is located in the city’s core, between Mill Creek and the Green
River, where development densities are highest. Figure 4-5 shows an overview of the city’s stormwater
drainage infrastructure.
Critical Facilities 4.3
Section 3.2.2 describes policies and LOS goals for managing the City’s critical facilities and critical
stormwater assets. Two groups of policies and LOS goals in particular focus on criticality. The first
applies to critical facilities, stating that the City will manage stormwater runoff within the public ROW in
the vicinity of critical facilities to allow access and ensure function of these facilities at all times,
especially during large storm events (LOS Goal 3). Eleven critical facilities have been identified and
included in Table 4-4.
The second group of policies relates to the management of the City’s critical stormwater assets (LOS
Goals 8–11). The City is modifying its inspection and maintenance practices to prioritize active
management of facilities with the highest combined risk and consequence of failure (i.e., a criticality-
based maintenance program). Factors that impact criticality include the age of the asset, repair history
of the asset, condition of the asset, and financial consequences of a failure. The consequences of a
system failure impacting a hospital or school are considered more serious than one affecting a residence
or unoccupied property, and are thus assigned as critical assets. The City has identified 11 city facilities
(Table 4-4) and seven stormwater pump stations (Table 4-5) as critical assets. The list of critical
stormwater assets may expand as the City refines its criticality database by adding information (e.g.,
inspection and repair logs, asset age; see LOS Goal 8). The locations of these critical facilities are shown
in Figure 4-6.
Table 4-4. Critical City Facilities
Facility Address
City Hall 25 W Main Street
City Hall Annex 1 E Main Street
Justice Center 340 E Main Street
Maintenance and Operation Facility 1305 C Street SW
Regional Hospital 201 N Division Street
Senior Center 808 9th Street SE
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Table 4-4. Critical City Facilities
Facility Address
Valley Regional Fire Authority (VRFA) Station 31 1101 D Street NE
VRFA Station 32 1951 R Street SE
VRFA Station 33 500 182nd Avenue E
VRFA Station 34 31290 124th Avenue SE
VRFA Station 35 2905 C Street SW
Table 4-5. Critical Stormwater Facilities
Storm drainage facility Year
constructed Address
A Street Pump Station 1973 404 A Street SE
Auburn Way S Pump Station 1994 405 Auburn Way S
Brannan Park Pump Station 2001 1302 30th Street NE
Emerald Park Pump Station 1999 499 42nd Street NE
M Street Pump Station 2014 410 M Street SE
West Main Street Pump Station 2008 1410 W Main Street
White River Pump Station 2012 4640 A Street SE
Water Quality 4.4
This section describes the existing water quality and regulatory conditions that affect surface water
quality in Auburn and describes upcoming processes that are required to maintain compliance with the
City’s NPDES Permit.
4.4.1 Existing Conditions
According to water resource inventories by Ecology, the main water bodies within the City’s
administrative boundaries include the Green River, Mill Creek, White Lake, White River, and Bowman
Creek. The City’s NPDES Permit requires that these water bodies meet water quality standards and
criteria. Municipal storm sewers that discharge runoff from urban areas to surface waters are not
authorized to violate state water quality standards.
Appendix 2 of the NPDES Permit (Appendix A of this plan) describes water bodies that have been
assessed as impaired and have additional requirements based on established TMDLs. A fecal coliform
TMDL for the Puyallup River watershed is included in the current NPDES Permit. As part of the TMDL, the
City is required to conduct wet weather sampling of discharges to the White River at Auburn Riverside
High School. Details of the required activities are included in Appendix 2 to the NPDES Permit.
The Green River has a TMDL for temperature that was approved by EPA in 2011. The TMDL report
indicated that implementation will depend on the support and participation of Auburn; however, the
water quality improvement plan has not been developed yet and the TMDL is not in Appendix 2 of the
NPDES Permit (Ecology, 2011).
The Green River is also being evaluated for a potential TMDL for dissolved oxygen, and Ecology is
currently evaluating Mill Creek, White River and Little Soosette Creek within the city. Mill Creek is being
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examined for potential TMDLs for temperature, fecal coliform, dissolved oxygen, and copper, and the
lower White River currently is under evaluation for TMDLs for pH and temperature. Soos Creek
watershed, which is partially in the city and includes the tributary Little Soosette Creek, has TMDLs under
development for aquatic habitat, dissolved oxygen, temperature, and fecal coliform. One or more new
TMDLs could be included in a future NPDES Permit.
4.4.2 Regulatory Compliance
The City has a well-developed MS4 M&O program that employs and provides training on numerous
processes and procedures to minimize water quality impacts from municipal operations. The City also
actively implements stormwater management BMPs in its municipal activities. BMPs include activities,
prohibitions of practices, maintenance procedures, and structural and/or managerial practices that
prevent or reduce the release of pollutants and other adverse impacts to waters of Washington State.
The current NPDES Permit includes provisions for monitoring and assessment of water quality.
Permittees have the option of paying annual fees to participate in statewide monitoring programs, or
developing individual monitoring programs to meet the requirement. The City notified Ecology in 2013
that it intends to participate in the statewide monitoring programs. Fees totaling $47,710 are due
annually, beginning in August 2014.
The City is in full compliance with its NPDES Permit, with programs, codes, processes, and procedures
that meet all of the NPDES Permit requirements currently in effect. The City’s SWMP Plan contains a
summary of the NPDES Permit requirements and descriptions of the City’s current and planned activities
for NPDES Permit compliance.
However, the City will need to make several changes to comply with updated requirements of the NPDES
Permit that phase in during the permit term. The City is conducting a process to identify and implement
needed updates to codes, standards, and programs by the relevant due dates. As part of the process,
the City developed a Compliance Work Plan to outline and guide compliance activities over the current
permit term. A copy of the Compliance Work Plan is included as Appendix B.
A schedule of relevant due dates to comply with updated NPDES Permit requirements is provided in
Section 8.3.
Existing Drainage Problems 4.5
Members of the City staff working within the Storm Drainage Utility are experienced and familiar with the
condition of the drainage system. Existing drainage problems have been observed by the staff and are
known to cause frequent flooding of roadways. The most apparent problems were identified for analysis
(see Hydraulic Evaluation, Section 5.1). Additionally, a severe storm event occurring in November 2007
caused substantial flooding in several locations that were identified during the development of the 2009
Drainage Plan. Many high-priority capital improvement projects were implemented to address these
problems. Capital improvement projects, which were developed for some lower-priority locations, have
yet to be implemented. For this planning effort, unimplemented capital improvement projects were
revised based on current conditions and available information. Existing drainage problems are described
in Table 4-6 and locations are mapped in Figure 4-7. Capital improvement projects developed to address
these problems are described in Chapter 7.
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Table 4-6. Existing Drainage Problems
No. Priority Location Description Approximate frequency
or last noted occurrence
P1 1 West Main Street dead
end near SR 167
The dead-end portion of Old West Main Street near SR 167 has a history of
observed flooding. The City installed a temporary pump station to dewater
the gravity pipe, flowing on the south side of Old West Main Street, in the
effort to protect local businesses from flooding. Since its installation in
2008, the pump station has eliminated flooding at the observed location.
The pump station, however, does not meet the City’s LOS guidelines
regarding pump redundancy, and may be insufficient to convey the 25-year
flow rate.
The City’s gravity pipe on the north side of Old West Main Street
experiences flooding, at one catch basin, approximately once per year.
Portions of this gravity pipe are full and water has been observed at catch
basin rims during summer months.
The pump station and gravity pipe discharge to a Washington State
Department of Transportation (WSDOT) ditch along the east side of SR
167. WSDOT has recently cleaned this ditch segment, and the impacts of
this maintenance work are still being determined.
Catch basin flooding once
per year and system
surcharging
P2 1 37th and I Streets NW
Recurring flooding in the vicinity of 37th Street NW and I Street NW causes
several nuisance problems including slow or impeded traffic on 37th Street
NW, driveway damage and/or impeded access to the nearby power
substation, and impeded pedestrian and bicycle access to the Interurban
Trail south of 37th Street NW (east of the substation).
A couple times a year, after
heavy rain prolonged wet
periods following storm
events
P3 1 Hillsides throughout the
city
The existing drainage system includes pipes that discharge over hillsides.
While a preliminary inventory and mapping of locations has been
completed, field-locating and detailed inspection is warranted to define
deficiencies.
Periodic
P4A 2
East of I Street NE
between 32nd Street NE
and 35th Street NE
The residential development east of I Street NE between 32nd Street NE
and 35th Street NE discharges flows into a City-owned infiltration area. The
infiltration area commonly experiences prolonged periods of standing
water due to high groundwater from extended high flows in the Green River,
which is adjacent to the infiltration area. The drainage system on I Street
NE currently lacks infrastructure to collect and convey stormwater away
from the infiltration area as well as residential roadways and parking areas.
Ponding occurs within the parking of the developments and presents a
nuisance and potential hazard to local residents.
Once every few years
P4B 3
C Street NE between
30th Street NE and 37th
Street NE
The December 3, 2007, storm (approximately a 50-year storm) produced
extensive flooding along C Street NE northward toward 37th Street NE,
which required sandbagging to protect local businesses. Deposition of
sediment within Mill Creek has raised the water levels within the creek and
diminished the capacity of the gravity system in C Street NE and
downstream in 37th Street NE. In addition to the influence of Mill Creek,
modeling efforts demonstrate that the system’s capacity is limited by low
pipe gradient and shallow inverts and that flooding would continue even
with sediment removal within Mill Creek.
December 2007
P5 1 West Hills
Flooding has been reported along the S 330th Street roadway. Surface
water from the ROW is conveyed through a ditch and set of pipes located on
private properties. The portion on private property had previously been
conveyed in a ditch. In an attempt to reclaim the front yard, a previous
property owner filled the ditch with two parallel pipes.
A City-owned pipe daylights to the backyard of a residential parcel and
discharges runoff onto the northern adjacent property located on S 312th
Street.
Once in last 5 years
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Table 4-6. Existing Drainage Problems
No. Priority Location Description Approximate frequency
or last noted occurrence
P6 2 North Airport area
The inlet and outlet of Airport Pond I do not allow the pond to operate as
designed; the pond fills from its outlet when the storm line in 30th Street
NE surcharges. In the north hangar area immediately east of Airport Pond I,
surcharging flows from the storm line in 30th Street NE backwater to the
airport’s 30-inch-diameter storm drain and causes flooding to the north
and west of the most northerly hangar.
December 2007
P7 2 D Street SE at 25th
Street
The western dead-end portion of 25th Street SE has a history of observed
flooding. An existing dry well has inadequate infiltration. The dry well floods
after heavy rain, several times a year. Floodwater fills the adjacent section
of 25th Street SE to the curb. Numerous dry wells also do not meet
discharge standards.
Floods after heavy
prolonged rain
P8 3 23rd Street SE
A new 12-inch-diameter stormwater gravity drain was installed along K
Street SE, south of 23rd Street SE, in 2014 to address localized flooding.
This piping increased the tributary area to the 8-inch-diameter gravity drain
along 23rd Street SE. Modeling results indicate that the existing 8-inch-
diameter gravity drain along 23rd Street SE does not meet the LOS.
None reported; potential
flooding simulated through
modeling
In addition to the problem locations listed in Table 4-6, the City identified two potential problem areas
described below.
Riverwalk Drive SE and Howard Road. Roadside ditches along the north and east side of Howard Road,
between Riverwalk Drive SE and R Street SE overtop and flood portions of Howard Road and the mobile
home park along the south side of the road. The Muckleshoot Indian Tribe has development plans for
the property between Howard Road and Auburn Way S. As part of the development, storm drainage
infiltration areas will be expanded northward of the existing facilities in the vicinity of the City’s water
treatment facility. Proposed facilities will include an overflow to the City’s storm drainage system, which
flows to the 21st Street Pond. The proposed modifications may address the observed flooding.
2nd and G Streets SE. The 2009 Drainage Plan described a problem at this location as roadway flooding
during large rain events due to manhole surcharging in the intersection. The manhole is located in a
local low point, and water encroaches on private property. In addition, a King County regional sewer line
crosses the storm drainage line at this manhole reducing conveyance capacity at this location. A project
to address this problem was included in the 2009 Drainage Plan, but has not been implemented.
Flooding has not been reported at this location since the development of the 2009 Drainage Plan. With
the implementation of the project Auburn Way S Flooding, Phase 1 in 2012 and planned construction of
Auburn Way S Flooding, Phase 2 in 2015/2016, the tributary area to this reported problem location will
be reduced. The lack of recent reported flooding and the reduced tributary area may indicate a project is
not warranted for this location.
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E
R
R
D
12
8
T
H
A
V
E
E
S 354TH ST
S 344TH ST
SE 364TH ST
SE 290TH ST
10TH ST SE
D
S
T
S
W
SE 280TH ST
2
1
1
T
H
A
V
E
E
NA
T
H
A
N
A
V
E
S
E
HI
C
R
E
S
T
D
R
B PL NW
SE 294TH ST
72ND ST SE
S 285TH ST
6TH ST NW
14
6
T
H
A
V
E
S
E
SE 293RD ST
3RD ST NW
12
6
T
H
A
V
E
S
E
I
S
A
A
C
A
V
E
S
E
S 312TH ST
EL
M
S
T
S
E
CLAY ST
S 370TH ST
52
N
D
P
L
S
7TH ST E
19TH DR NE
SE 307TH PL
51ST
S
T
S
E
10TH AVE N
S 364TH ST
14
0
T
H
A
V
E
S
E
28TH ST SE
15TH ST SE
13
3
R
D
A
V
E
S
E
10
8
T
H
A
V
E
S
E
73RD ST SE
SE 295TH ST
26TH ST NE
S 366TH ST
SE 3
8
0
T
H
P
L
SE 297TH ST
2
1
0
T
H
A
V
E
E
66TH ST SE
24TH ST NE
SE 296TH ST
SE 285TH ST
S 368TH ST
AL
D
E
R
L
N
S
11
7
T
H
A
V
E
S
E
U
S
T
S
E
19TH ST SE
6TH ST SE
11
0
T
H
P
L
S
E
A ST E
15
6
T
H
A
V
E
S
E
21ST ST SE
R PL NE
11
7
T
H
A
V
E
E
33RD ST SE
7TH ST
5TH ST NE
53
R
D
A
V
E
S
HE
A
T
H
E
R
A
V
E
S
E
F
S
T
N
E
11
2
T
H
P
L
S
E
51
S
T
P
L
S
SE 292ND ST
D PL SE
S 320TH ST
SE 272ND PL
8TH ST SW
6TH AVE N
22ND ST E
63
R
D
P
L
S
2ND CT NW
1ST ST NE
R
S
T
N
E
12
9
T
H
P
L
S
E
O
C
T
S
E
S 342ND ST
26TH ST NW
SE 321ST PL
11
4
T
H
P
L
S
E
8TH ST NE
51
S
T
A
V
E
S
9TH ST E
55T
H
P
L
S
SE 288TH ST
SR
1
6
7
SE 272ND ST
51
S
T
A
V
E
S
11
0
T
H
A
V
E
S
E
C S
T
N
W
SE 282ND ST
S 277TH ST
55
T
H
A
V
E
S
SE 296TH ST
53
R
D
A
V
E
S
SE 282ND ST
11
8
T
H
A
V
E
S
E
8TH ST E
SR 1
8
SE 272ND ST
SR
1
6
7
M
S
T
N
W
1ST AVE N
SR
1
6
7
14
2
N
D
A
V
E
E
S 277TH ST
SE 274TH ST
56
T
H
A
V
E
S
SR
1
6
7
23RD ST SE
H
S
T
N
E
SR
1
6
7
8TH ST E
16TH ST E
SR
1
6
7
10
8
T
H
A
V
E
S
E
SR
1
6
7
12TH ST E
M
S
T
N
E
10
4
T
H
A
V
E
S
E
2ND ST E
SE 301ST ST
SR
1
6
7
SR 18
21ST ST E
R
S
T
N
W
32ND ST E
14
4
T
H
A
V
E
S
E
12
4
T
H
A
V
E
S
E
32ND ST E
14
8
T
H
A
V
E
S
E
D
S
T
S
E
24TH ST E
SR 1
8
2ND ST SE
17TH ST SE
SE 368TH PL
20
0
T
H
A
V
E
E
51ST
S
T
S
E
R
S
T
N
W
COMPREHENSIVE STORM DRAINAGE PLAN
1 inch = 4,000 feet
April 2015
LEGEND
Roadway
Watercourse
Water Body
Wetland
Auburn City Boundary
P:
\
A
u
b
u
r
n
\
1
4
5
2
9
5
A
u
b
u
r
n
S
t
o
r
m
w
a
t
e
r
C
o
m
p
P
l
a
n
\
G
I
S
\
M
X
D
\
P
r
e
l
i
m
i
n
a
r
y
D
r
a
f
t
P
l
a
n
\
A
u
b
u
r
n
S
t
o
r
m
_
F
i
g
4
-
1
(
n
a
t
d
r
a
i
n
)
.
m
x
d
0 4,000 8,000
Feet
Figure 4-1Natural Drainage Features of the City of Auburn¯
L a k eT a p p s
Bi g S o o s C r e e k
Mill
Creek
R i v e r
G
r
e
e
n
R
i
ver
M
ill
Creek
CreekMill
G
r
e
e
n
R
i
v
e
r
White
G
r
e
e
n
River
Soosette
Creek
River
Whit
e
Bow m an C
re
e
k
W
h
i
t
e
River
R i v e r
WhiteLake
M
u
l
l
e
n
S
l
o
u
g
h
Green Ri v e r
Lake Meridian
White
Lea Hill
Southern
North Central
West Hill
Southeast
South Central
COMPREHENSIVE STORM DRAINAGE PLAN
1 inch = 4,000 feet
LEGEND
Roadway
Watercourse
Water Body
Wetland
Drainage Subarea
Auburn City Boundary
Major receiving water
Green River
Mill Creek
Mullen Slough
Soosette and Big Soos Creeks
White River
Outfalls
Green River
Mill Creek
White River
Other Stream
Wetland
P:
\
A
u
b
u
r
n
\
1
4
5
2
9
5
A
u
b
u
r
n
S
t
o
r
m
w
a
t
e
r
C
o
m
p
P
l
a
n
\
G
I
S
\
M
X
D
\
P
r
e
l
i
m
i
n
a
r
y
D
r
a
f
t
P
l
a
n
\
A
u
b
u
r
n
S
t
o
r
m
_
F
i
g
4
-
2
(
s
u
b
b
a
s
i
n
s
)
.
m
x
d
0 4,000 8,000
Feet
Figure 4-2Drainage Subareas for the City of Auburn Storm Drainage Utility¯April 2015
L a k eT a p p s
B i g S o o s C r e e k
Mill
Creek
R i v e r
G
r
e
e
n
R
i
ver
Mill
Creek
CreekMill
G
r
e
e
n
R
i
v
e
r
G
r
e
e
n
River
White
G
r
e
e
n
River
Soosette
Creek
River
W
hit
e
Bow man
C
re
e
k
W
h
i
t
e
River
R i v e r
WhiteLake
M
u
l
l
e
n
S
l
o
u
g
h
Green Ri v e r
Lake Meridian
White
S
R
1
6
7
SR 1
8
A
S
T
S
E
C
S
T
S
W
A
U
B
U
R
N
W
A
Y
S
B
S
T
N
W
I
S
T
N
E
AU
B
U
R
N
W
A
Y
N
R
S
T
S
E
13
2
N
D
A
V
E
S
E
WE
S
T
V
A
L
L
E
Y
H
W
Y
N
W
M
S
T
S
E
8TH ST E
E MAIN ST
24TH ST E
12
4
T
H
A
V
E
S
E
EA
S
T
V
A
L
L
E
Y
H
W
Y
S
E
JOVITA BLVD
12
2
N
D
A
V
E
E
C
S
T
N
W
BU
T
T
E
A
V
E
S 384TH ST
11
0
T
H
A
V
E
E
15TH ST SW
SE 288TH ST
2ND ST E
C
S
T
N
E
SE 312TH ST
S 277TH ST
W MAIN ST
15TH ST NW
19
8
T
H
A
V
E
E
53RD ST SE
9TH ST
E
29TH ST SE
GREEN VALLEY RD
1
7
9
T
H
A
V
E
SE 320TH ST
11
4
T
H
A
V
E
E
11
6
T
H
A
V
E
S
E
EDWARDS RD E
LAKE TAPPS PKWY SE
41ST ST SE
WE
S
T
V
A
L
L
E
Y
H
W
Y
S
W
STUCK
R
I
V
E
R
D
R
16TH ST E
K
E
R
S
E
Y
W
A
Y
S
E
14
7
T
H
A
V
E
S
E
4TH ST E
18TH ST E
M
S
T
N
E
12TH ST E
SE 304TH ST
1
9
0
T
H
A
V
E
E
11
2
T
H
A
V
E
E
3RD AVE SE
ELLINGSON RD SW
37TH ST SE
PE
R
I
M
E
T
E
R
R
D
SE 272ND ST
4
6
T
H
P
L
S
8TH ST NE
18
2
N
D
A
V
E
E
37TH ST NW
AC
A
D
E
M
Y
D
R
S
E
SE LAKE HOLM RD
22ND ST NE
L
A
K
E
L
A
N
D
H
I
L
L
S
W
A
Y
S
E
ORA
V
E
T
Z
R
D
S
E
VA
L
E
N
T
I
N
E
A
V
E
S
E
C
U
T
O
F
F
51
S
T
A
V
E
S
SE 282ND ST
14
4
T
H
A
V
E
S
E
17TH ST SE
S 296TH ST
25TH ST SE
12TH ST SE
55
T
H
A
V
E
S
1
8
5
T
H
A
V
E
E
21
4
T
H
A
V
E
E
D
S
T
S
E
1ST AVE SE
TA
C
O
M
A
B
L
V
D
D
S
T
N
W
A
S
T
N
E
4TH ST SE
CE
L
E
R
Y
A
V
E
30TH ST NE
10
8
T
H
A
V
E
EA
S
T
B
L
V
D
(
B
O
E
I
N
G
)
11
2
T
H
A
V
E
S
E
SE 316TH ST
14
8
T
H
A
V
E
S
E
T
A
C
O
M
A
P
O
I
N
T
D
R
E
A
U
B
U
R
N
-
E
N
U
M
C
L
A
W
R
D
55TH ST SE
E
V
E
R
G
R
E
E
N
W
A
Y
S
E
EM
E
R
A
L
D
D
O
W
N
S
D
R
N
W
D
S
T
N
E
M
S
T
N
W
O
S
T
N
E
S
E
3
6
8
T
H
P
L
W
S
T
N
W
1
6
9
T
H
A
V
E
E
S 287TH ST
3RD AVE S
5TH AVE SW
E
S
T
N
E
37TH ST NE
14
2
N
D
A
V
E
E
S 316TH ST
H
A
R
V
E
Y
R
D
S
C
E
N
I
C
D
R
S
E
H
S
T
N
W
M
A
I
N
S
T
S 292ND ST
WE
S
T
B
L
V
D
(
B
O
E
I
N
G
)
44TH ST NW
3RD AVE SW
11
8
T
H
A
V
E
E
10TH ST NE
CL
A
Y
S
T
N
W
4TH AVE SW
14
8
T
H
A
V
E
E
7TH ST SE
13
7
T
H
A
V
E
E
26
T
H
S
T
E
13
6
T
H
A
V
E
E
SE 310TH ST
S 3RD AVE
TH
O
R
T
O
N
A
V
E
S
W
2
0
0
T
H
A
V
E
E
RIVE
R
D
R
BOUNDARY BLVD
LEA HIL
L
R
D
S
E
32ND ST E
11
8
T
H
A
V
E
S
E
58
T
H
A
V
E
S
AL
G
O
N
A
B
L
V
D
N
10
4
T
H
A
V
E
S
E
S 372ND ST
J
S
T
N
E
ROY RD SW
4TH ST NE
PA
C
I
F
I
C
A
V
E
S
11
0
T
H
A
V
E
S
E
14TH ST NE
D
R
I
V
E
W
A
Y
SE 281ST ST
12
6
T
H
A
V
E
E
5TH ST SE
72
N
D
A
V
E
S
56
T
H
P
L
S
25TH ST E
BR
I
D
G
E
T
A
V
E
S
E
57
T
H
A
V
E
S
S 328TH ST
DO
G
W
O
O
D
S
T
S
E
2ND AVE SW
8TH ST SE
S 279TH ST
L
S
T
S
E
T
S
T
S
E
F
S
T
S
E
FR
O
N
T
A
G
E
R
D
C
O
T
T
A
G
E
R
D
E
FO
S
T
E
R
A
V
E
S
E
52
N
D
A
V
E
S
SE 274TH ST
1ST ST E
16
6
T
H
A
V
E
E
1ST AVE N
SE 299TH ST
SE 316TH PL
SE 284TH ST
49TH ST NE
S 362ND ST
NO
R
M
A
N
A
V
E
S
E
I
S
T
N
W
32ND PL NE
54
T
H
A
V
E
S
A
S
T
S
W
57
T
H
P
L
S
U
S
T
N
W
7
8
T
H
A
V
E
S
3RD ST E
D
E
E
R
I
S
L
A
N
D
D
R
E
13
5
T
H
A
V
E
S
E
47TH
S
T
S
E
2
0
4
T
H
A
V
E
E
28TH ST NE
8
6
T
H
A
V
E
S
S 356TH ST
J
S
T
S
E
R S
T
N
W
27TH ST E
15TH ST E
28TH ST E
MI
L
I
T
A
R
Y
R
D
S
13TH ST E
K
S
T
S
E
OL
I
V
E
A
V
E
S
E
10TH ST E
10
8
T
H
A
V
E
E
31ST ST NE
SE 323RD PL
54
T
H
P
L
S
B
S
T
S
E
WY
M
A
N
D
R
26TH ST SE
S 336TH ST
ST
P
A
U
L
B
L
V
D
S 340TH ST
C
S
T
S
E
B S
T
N
E
32ND ST SE
S 300TH ST
1ST AVE S
36TH ST SE
ELM LN
SE 301ST ST
2
0
8
T
H
A
V
E
E
SE 287TH ST
V
S
T
N
W
2ND ST SE
23RD ST SE
4TH AVE S
3RD ST SE
QU
I
N
C
Y
A
V
E
S
E
29TH ST NW
21ST ST NE
1
5
6
T
H
A
V
E
E
HE
M
L
O
C
K
S
T
S
E
1
8
4
T
H
C
T
E
5
6
T
H
A
V
E
S
10
6
T
H
A
V
E
E
SE 298TH PL30TH ST NW
30TH ST SE
S 318TH ST
24TH ST SE
2ND AVE S
14TH ST E
H
S
T
N
E
LU
N
D
R
D
S
W
S 324TH ST
PI
K
E
S
T
N
W
21ST ST E
31ST ST E
42ND ST NW
6TH AVE SW
17TH
S
T
E
11
9
T
H
A
V
E
E
SE 286TH ST
9TH ST SE
55T
H
P
L
S
SE 276TH PL
65
T
H
A
V
E
S
SE 295TH PL
G
S
T
N
E
27TH ST SE5TH AVE N
SK
I
N
N
E
R
R
D
1
0
2
N
D
A
V
E
S
E
12
8
T
H
A
V
E
E
S 354TH ST
S 344TH ST
SE 364TH ST
SE 290TH ST
10TH ST SE
D
S
T
S
W
SE 280TH ST
2
1
1
T
H
A
V
E
E
NA
T
H
A
N
A
V
E
S
E
V
S
T
S
E
HI
C
R
E
S
T
D
R
B PL NW
SE 294TH ST
S 285TH ST
6TH ST NW
14
6
T
H
A
V
E
S
E
SE 293RD ST
PE
A
R
L
A
V
E
S
E
3RD ST NW
12
6
T
H
A
V
E
S
E
I
S
A
A
C
A
V
E
S
E
S 312TH ST
EL
M
S
T
S
E
CLAY ST
S 370TH ST
20TH ST E
52
N
D
P
L
S
7TH ST E
19TH DR NE
SE 307TH PL
51ST
S
T
S
E
10TH AVE N
S 364TH ST
14
0
T
H
A
V
E
S
E
28TH ST SE
72ND ST SE
15TH ST SE
13
3
R
D
A
V
E
S
E
10
8
T
H
A
V
E
S
E
73RD ST SE
SE 295TH ST
26TH ST NE
S 366TH ST
SE 297TH ST
2
1
0
T
H
A
V
E
E
66TH ST SE
24TH ST NE
SE 296TH ST
SE 285TH ST
S 368TH ST
AL
D
E
R
L
N
S
11
7
T
H
A
V
E
S
E
U
S
T
S
E
19TH ST SE
6TH ST SE
11
0
T
H
P
L
S
E
A ST E
15
6
T
H
A
V
E
S
E
21ST ST SE
R PL NE
11
7
T
H
A
V
E
E
10
5
T
H
A
V
E
S
E
7TH ST
5TH ST NE
53
R
D
A
V
E
S
HE
A
T
H
E
R
A
V
E
S
E
F
S
T
N
E
11
2
T
H
P
L
S
E
51
S
T
P
L
S
SE 292ND ST
D PL SE
S 320TH ST
SE 272ND PL
8TH ST SW
6TH AVE N
22ND ST E
12
3
R
D
A
V
E
E
63
R
D
P
L
S
TH
O
R
T
O
N
P
L
S
W
2ND CT NW
1ST ST NE
12
9
T
H
P
L
S
E
6TH ST NE
3RD ST NE
O
C
T
S
E
S 342ND ST
10
5
T
H
A
V
E
E
26TH ST NW
SE 321ST PL
11
4
T
H
P
L
S
E
26TH ST NE
55
T
H
A
V
E
S
SE 301ST ST
54
T
H
A
V
E
S
56
T
H
A
V
E
S
51
S
T
A
V
E
S
M
S
T
N
E
14
4
T
H
A
V
E
S
E
SE 292ND ST
32ND ST E
SR 18
24TH ST E
21ST ST E
S 277TH ST
11
0
T
H
A
V
E
S
E
SE 282ND ST
SR
1
6
7
20
0
T
H
A
V
E
E
SE 272ND ST
SR 18
DRIVEWAY
2ND ST SE
R
S
T
N
W
SE 274TH ST
8TH ST E
10
8
T
H
A
V
E
S
E
32ND ST E
SE 288TH ST
9TH ST E
51
S
T
A
V
E
S
23RD ST SE
16TH ST E
SR
1
6
7
12TH ST E
SR
1
6
7
12
4
T
H
A
V
E
S
E
SR
1
6
7
DRIV
E
W
A
Y
8TH ST NE
SE 272ND ST
14
8
T
H
A
V
E
S
E
SE 282ND ST
SR
1
6
7
V
S
T
S
E
17TH ST E
8TH ST E
SR 1
8
SR
1
6
7
SR
1
6
7
SE 296TH ST
H
S
T
N
E
R
S
T
N
W
13TH ST E
SR
1
6
7
51ST
S
T
S
E
SR
1
6
7
10
4
T
H
A
V
E
S
E
1ST AVE N
SE 284TH ST
D
R
I
V
E
W
A
Y
SR 1
8
D
R
I
V
E
W
A
Y
S 277TH ST
10
8
T
H
A
V
E
E
D
S
T
S
E
SE 304TH S
T
10
6
T
H
A
V
E
E
17TH ST SE
55T
H
P
L
S
COMPREHENSIVE STORM DRAINAGE PLAN
1 inch = 4,000 feet
April 2015
LEGEND
Roadway
Watercourse
Water Body
Wetland
Subbasins
Auburn City Boundary
Surficial Geology
Qa
Qc
Qf
Qga
Qgd
Qgl
Qgo
Qgp
Qgp(s)
Qgp(st)
Qgpc
Qgt
Qls
Qp
Qvl(o)
P:
\
A
u
b
u
r
n
\
1
4
5
2
9
5
A
u
b
u
r
n
S
t
o
r
m
w
a
t
e
r
C
o
m
p
P
l
a
n
\
G
I
S
\
M
X
D
\
P
r
e
l
i
m
i
n
a
r
y
D
r
a
f
t
P
l
a
n
\
A
u
b
u
r
n
S
t
o
r
m
_
F
i
g
4
-
3
(
g
e
o
)
.
m
x
d
0 4,000 8,000
Feet
Figure 4-3Surface Geology inthe Vicinity of theCity of Auburn
Geologic UnitLithologyQaAlluvium
Qc Continental sedimentary deposits or rocks
Qf Artificial fill, including modified land
Qga Advance continental glacial outwash, Fraser-age
Qgd Continental glacial drift, Fraser-age
Qgl Glaciolacustrine deposits, Fraser-age
Qgo Continental glacial outwash, Fraser-age
Qgp Continental glacial drift, pre-Fraser
Qgp(s)Continental glacial drift, pre-Frasier, Salmon Springs Drift
Qgp(st)Continental glacial drift, pre-Fraser, Stuck Drift
Qgpc Continental glacial drift, pre-Fraser, and nonglacial deposits
Qgt Continental glacial till, Fraser-age
Qls Mass-wasting deposits, mostly landslides
Qp Peat deposits
Qvl(o)Lahars
¯
L a k eT a p p s
B i g S o o s C r e e k
Mill
Creek
R i v e r
G
r
e
e
n
R
i
ver
M
ill
Creek
CreekMill
G
r
e
e
n
R
i
v
e
r
G
r
e
e
n
River
White
G
r
e
e
n
River
Soosette
Creek
River
W
hit
e
Bowm an
C
re
e
k
W
h
i
t
e
River
R i v e r
WhiteLake
M
u
l
l
e
n
S
l
o
u
g
h
Green Ri v e r
Lake Meridian
White
S
R
1
6
7
A
S
T
S
E
C
S
T
S
W
A
U
B
U
R
N
W
A
Y
S
B
S
T
N
W
I
S
T
N
E
AU
B
U
R
N
W
A
Y
N
SR 1
8
R
S
T
S
E
13
2
N
D
A
V
E
S
E
WE
S
T
V
A
L
L
E
Y
H
W
Y
N
W
M
S
T
S
E
8TH ST E
E MAIN ST
24TH ST E
12
4
T
H
A
V
E
S
E
JOVIT
A
B
L
V
D
EA
S
T
V
A
L
L
E
Y
H
W
Y
S
E
12
2
N
D
A
V
E
E
BU
T
T
E
A
V
E
S 384TH ST
11
0
T
H
A
V
E
E
15TH ST SW
SE 288TH ST
2ND ST E
C
S
T
N
E
SE 312TH ST
S 277TH ST
W MAIN ST
15TH ST NW
C
S
T
N
W
19
8
T
H
A
V
E
E
53RD ST SE
9TH ST
E
29TH ST SE
GREEN VALLEY RD
1
7
9
T
H
A
V
E
SE 320TH ST
11
4
T
H
A
V
E
E
11
6
T
H
A
V
E
S
E
EDWARDS RD E
LAKE TAPPS PKWY SE
41ST ST SE
WE
S
T
V
A
L
L
E
Y
H
W
Y
S
W
STUCK
R
I
V
E
R
D
R
16TH ST E
K
E
R
S
E
Y
W
A
Y
S
E
14
7
T
H
A
V
E
S
E
4TH ST E
18TH ST E
M
S
T
N
E
12TH ST E
SE 304TH ST
1
9
0
T
H
A
V
E
E
11
2
T
H
A
V
E
E
3RD AVE SE
ELLINGSON RD SW
37TH ST SE
PE
R
I
M
E
T
E
R
R
D
SE 272ND ST
4
6
T
H
P
L
S
8TH ST NE
18
2
N
D
A
V
E
E
37TH ST NW
AC
A
D
E
M
Y
D
R
S
E
SE LAKE HOLM RD
22ND ST NE
L
A
K
E
L
A
N
D
H
I
L
L
S
W
A
Y
S
E
ORA
V
E
T
Z
R
D
S
E
VA
L
E
N
T
I
N
E
A
V
E
S
E
C
U
T
O
F
F
51
S
T
A
V
E
S
SE 282ND ST
14
4
T
H
A
V
E
S
E
17TH ST SE
S 296TH ST
25TH ST SE
12TH ST SE
55
T
H
A
V
E
S
1
8
5
T
H
A
V
E
E
21
4
T
H
A
V
E
E
D
S
T
S
E
1ST AVE SE
TA
C
O
M
A
B
L
V
D
D
S
T
N
W
A
S
T
N
E
4TH ST SE
CE
L
E
R
Y
A
V
E
30TH ST NE
10
8
T
H
A
V
E
EA
S
T
B
L
V
D
(
B
O
E
I
N
G
)
11
2
T
H
A
V
E
S
E
SE 316TH ST
14
8
T
H
A
V
E
S
E
T
A
C
O
M
A
P
O
I
N
T
D
R
E
55TH ST SE
A
U
B
U
R
N
-
E
N
U
M
C
L
A
W
R
D
E
V
E
R
G
R
E
E
N
W
A
Y
S
E
D
S
T
N
E
M
S
T
N
W
O
S
T
N
E
S
E
3
6
8
T
H
P
L
W
S
T
N
W
1
6
9
T
H
A
V
E
E
S 287TH ST
3RD AVE S
5TH AVE SW
E
S
T
N
E
37TH ST NE
14
2
N
D
A
V
E
E
S 316TH ST
H
A
R
V
E
Y
R
D
S
C
E
N
I
C
D
R
S
E
H
S
T
N
W
M
A
I
N
S
T
S 292ND ST
WE
S
T
B
L
V
D
(
B
O
E
I
N
G
)
44TH ST NW
3RD AVE SW
11
8
T
H
A
V
E
E
10TH ST NE
CL
A
Y
S
T
N
W
4TH AVE SW
14
8
T
H
A
V
E
E
7TH ST SE
13
7
T
H
A
V
E
E
26
T
H
S
T
E
13
6
T
H
A
V
E
E
SE 310TH ST
S 3RD AVE
TH
O
R
T
O
N
A
V
E
S
W
2
0
0
T
H
A
V
E
E
17TH S
T
E
RIVE
R
D
R
BOUNDARY BLVD
LEA HIL
L
R
D
S
E
32ND ST E
11
8
T
H
A
V
E
S
E
58
T
H
A
V
E
S
AL
G
O
N
A
B
L
V
D
N
10
4
T
H
A
V
E
S
E
S 372ND ST
J
S
T
N
E
ROY RD SW
4TH ST NE
PA
C
I
F
I
C
A
V
E
S
11
0
T
H
A
V
E
S
E
14TH ST NE
DRIVEWAY
SE 281ST ST
12
6
T
H
A
V
E
E
5TH ST SE
72
N
D
A
V
E
S
56
T
H
P
L
S
25TH ST E
BR
I
D
G
E
T
A
V
E
S
E
57
T
H
A
V
E
S
S 328TH ST
DO
G
W
O
O
D
S
T
S
E
2ND AVE SW
8TH ST SE
S 279TH ST
L
S
T
S
E
T
S
T
S
E
F
S
T
S
E
FR
O
N
T
A
G
E
R
D
C
O
T
T
A
G
E
R
D
E
FO
S
T
E
R
A
V
E
S
E
52
N
D
A
V
E
S
SE 274TH ST
16
6
T
H
A
V
E
E
1ST AVE N
SE 299TH ST
SE 316TH PL
SE 284TH ST
49TH ST NE
S 362ND ST
I
S
T
N
W
32ND PL NE
54
T
H
A
V
E
S
A
S
T
S
W
57
T
H
P
L
S
U
S
T
N
W
7
8
T
H
A
V
E
S
3RD ST E
D
E
E
R
I
S
L
A
N
D
D
R
E
13
5
T
H
A
V
E
S
E
47TH
S
T
S
E
2
0
4
T
H
A
V
E
E
28TH ST NE
8
6
T
H
A
V
E
S
S 356TH ST
J
S
T
S
E
R S
T
N
W
27TH ST E
15TH ST E
28TH ST E
MI
L
I
T
A
R
Y
R
D
S
13TH ST E
K
S
T
S
E
OL
I
V
E
A
V
E
S
E
10TH ST E
10
8
T
H
A
V
E
E
31ST ST NE
SE 323RD PL
54
T
H
P
L
S
B
S
T
S
E
WY
M
A
N
D
R
26TH ST SE
S 336TH ST
ST
P
A
U
L
B
L
V
D
S 340TH ST
C
S
T
S
E
B S
T
N
E
32ND ST SE
S 300TH ST
1ST AVE S
36TH ST SE
ELM LN
SE 301ST ST
2
0
8
T
H
A
V
E
E
SE 287TH ST
V
S
T
N
W
2ND ST SE
23RD ST SE
4TH AVE S
3RD ST SE
QU
I
N
C
Y
A
V
E
S
E
21ST ST NE
1
5
6
T
H
A
V
E
E
14
0
T
H
A
V
E
E
HE
M
L
O
C
K
S
T
S
E
1
8
4
T
H
C
T
E
5
6
T
H
A
V
E
S
10
6
T
H
A
V
E
E
SE 298TH PL
30TH ST SE
S 318TH ST
24TH ST SE
2ND AVE S
14TH ST E
H
S
T
N
E
LU
N
D
R
D
S
W
S 324TH ST
PI
K
E
S
T
N
W
21ST ST E
31ST ST E
42ND ST NW
6TH AVE SW
11
9
T
H
A
V
E
E
SE 286TH ST
9TH ST SE
55T
H
P
L
S
SE 276TH PL
65
T
H
A
V
E
S
SE 295TH PL
G
S
T
N
E
27TH ST SE5TH AVE N
SK
I
N
N
E
R
R
D
12
8
T
H
A
V
E
E
S 354TH ST
S 344TH ST
SE 364TH ST
SE 290TH ST
10TH ST SE
D
S
T
S
W
SE 280TH ST
2
1
1
T
H
A
V
E
E
NA
T
H
A
N
A
V
E
S
E
V
S
T
S
E
1
0
4
T
H
P
L
S
E
HI
C
R
E
S
T
D
R
B PL NW
SE 294TH ST
72ND ST SE
S 285TH ST
6TH ST NW
14
6
T
H
A
V
E
S
E
SE 293RD ST
3RD ST NW
12
6
T
H
A
V
E
S
E
I
S
A
A
C
A
V
E
S
E
S 312TH ST
EL
M
S
T
S
E
CLAY ST
S 370TH ST
20TH ST E
52
N
D
P
L
S
7TH ST E
19TH DR NE
SE 307TH PL
51ST
S
T
S
E
10TH AVE N
S 364TH ST
14
0
T
H
A
V
E
S
E
28TH ST SE
15TH ST SE
13
3
R
D
A
V
E
S
E
10
8
T
H
A
V
E
S
E
73RD ST SE
SE 295TH ST
26TH ST NE
S 366TH ST
SE 297TH ST
2
1
0
T
H
A
V
E
E
66TH ST SE
24TH ST NE
SE 296TH ST
SE 285TH ST
S 368TH ST
AL
D
E
R
L
N
S
11
7
T
H
A
V
E
S
E
U
S
T
S
E
19TH ST SE
6TH ST SE
11
0
T
H
P
L
S
E
A ST E WA
R
D
A
V
E
S
E
15
6
T
H
A
V
E
S
E
21ST ST SE
R PL NE
11
7
T
H
A
V
E
E
10
5
T
H
A
V
E
S
E
7TH ST
5TH ST NE
53
R
D
A
V
E
S
HE
A
T
H
E
R
A
V
E
S
E
F
S
T
N
E
11
2
T
H
P
L
S
E
51
S
T
P
L
S
SE 292ND ST
D PL SE
S 320TH ST
SE 272ND PL
8TH ST SW
6TH AVE N
22ND ST E
12
3
R
D
A
V
E
E
63
R
D
P
L
S
2ND CT NW
1ST ST NE
R
S
T
N
E
12
9
T
H
P
L
S
E
O
C
T
S
E
S 342ND ST
10
5
T
H
A
V
E
E
26TH ST NW
5TH ST E
SE 321ST PL
11
4
T
H
P
L
S
E
1ST AVE N
SE 282ND ST
SE 296TH ST
M
S
T
N
W
12TH ST E
55T
H
P
L
S
2ND ST SE
8TH ST E
SR 1
8
10
4
T
H
A
V
E
S
E
9TH ST E
SE 282ND ST
16TH ST E
R
S
T
N
W
8TH ST E
SE 272ND ST
11
8
T
H
A
V
E
S
E
32ND ST E
14
8
T
H
A
V
E
S
E
SE 272ND ST
SR 18
SE 284TH ST
14
2
N
D
A
V
E
E
V
S
T
S
E
10
6
T
H
A
V
E
E
SR 1
8
54
T
H
A
V
E
S
56
T
H
A
V
E
S
C S
T
N
W
SR
1
6
7
SR
1
6
7
10
5
T
H
A
V
E
E
8TH ST NE
D
S
T
S
E
21ST ST E
20
0
T
H
A
V
E
E
26TH ST NE
R
S
T
N
W
51
S
T
A
V
E
S
DRIVEWAY
SE 274TH ST
SR
1
6
7
51ST
S
T
S
E
D
R
I
V
E
W
A
Y
S 277TH ST
SE 301ST ST
12
4
T
H
A
V
E
S
E
SR
1
6
7
24TH ST E
14
4
T
H
A
V
E
S
E
51
S
T
A
V
E
S
SR
1
6
7
DRIV
E
W
A
Y
13TH ST E
SR
1
6
7
SR
1
6
7
55
T
H
A
V
E
S
H
S
T
N
E
10
8
T
H
A
V
E
E
D
R
I
V
E
W
A
Y
11
0
T
H
A
V
E
S
E
10
8
T
H
A
V
E
E
10
8
T
H
A
V
E
S
E
SR 18
SR
1
6
7
M
S
T
N
E
S 277TH ST
17TH ST SE
32ND ST E
COMPREHENSIVE STORM DRAINAGE PLAN
1 inch = 4,000 feet
April 2015
P:
\
A
u
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1
4
5
2
9
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l
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Figure 4-4Land Use Designationsfor the City of Auburn
LEGEND
Roadway
Watercourse
Hydrography
Subbasins
Auburn City Boundary
Existing Land Use
Rural
Single-Family Residential
Moderate Density Residential
High Density Residential
Office Residential
Neighborhood Commercial
Light Commercial
Heavy Commercial
Downtown
Light Industrial
Heavy Industrial
Public and Quasi-Public
Open Space
Special Plan Area - Adopted
Special Plan Area - Proposed
¯
[Ú
[Ú
[Ú[Ú
[Ú
[Ú[Ú
[Ú
[Ú[Ú
[Ú[Ú[Ú[Ú[Ú
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L a k eT a p p s
B i g S o o s C r e e k
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White
"
West Main PS "
A Street PS
"
Auburn Way South PS
"
Emerald Park PS
"
Brannan Park PS
"
White River PS
"
M Street PS
COMPREHENSIVE STORM DRAINAGE PLAN
1 inch = 4,000 feet
April 2015
LEGEND
[Ú Pump Station
Infiltration Pond or Swale
Detention Pond
Stormwater Vault or Tank
Storm Pipe
Open Channel (Ditch)
Roadway
Watercourse
Water Body
Wetland
Auburn City Boundary
P:
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Figure 4-5Drainage Infrastructure for the City of Auburn Storm Drainage Utility¯
4
L a k eT a p p s
B i g S o o s C r e e k
Mill
Creek
R i v e r
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White
¬«S7
S
R
1
6
7
SR 1
8
A
S
T
S
E
C
S
T
S
W
A
U
B
U
R
N
W
A
Y
S
B
S
T
N
W
I
S
T
N
E
AU
B
U
R
N
W
A
Y
N
R
S
T
S
E
13
2
N
D
A
V
E
S
E
WE
S
T
V
A
L
L
E
Y
H
W
Y
N
W
M
S
T
S
E
8TH ST E
E MAIN ST
24TH ST E
12
4
T
H
A
V
E
S
E
EA
S
T
V
A
L
L
E
Y
H
W
Y
S
E
12
2
N
D
A
V
E
E
BU
T
T
E
A
V
E
11
0
T
H
A
V
E
E
15TH ST SW
SE 288TH ST
2ND ST EJOVITA BLVD
C
S
T
N
E
S 384TH ST
SE 312TH ST
S 277TH ST
W MAIN ST
15TH ST NW
C
S
T
N
W
19
8
T
H
A
V
E
E
53RD ST SE
9TH ST E
29TH ST SE
GREEN VALLEY RD
1
7
9
T
H
A
V
E
SE 320TH ST
11
4
T
H
A
V
E
E
11
6
T
H
A
V
E
S
E
EDWARDS RD E
LAKE TAPPS PKWY SE
41ST ST SE
WE
S
T
V
A
L
L
E
Y
H
W
Y
S
W
STUCK
R
I
V
E
R
D
R
16TH ST E
K
E
R
S
E
Y
W
A
Y
S
E
14
7
T
H
A
V
E
S
E
4TH ST E
18TH ST E
M
S
T
N
E
12TH ST E
SE 304TH ST
1
9
0
T
H
A
V
E
E
11
2
T
H
A
V
E
E
3RD AVE SE
ELLINGSON RD SW
37TH ST SE
PE
R
I
M
E
T
E
R
R
D
SE 272ND ST
4
6
T
H
P
L
S
8TH ST NE
18
2
N
D
A
V
E
E
37TH ST NW
AC
A
D
E
M
Y
D
R
S
E
SE LAKE HOLM RD
22ND ST NE
L
A
K
E
L
A
N
D
H
I
L
L
S
W
A
Y
S
E
ORA
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E
T
Z
R
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L
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N
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A
V
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S
E
C
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F
F
51
S
T
A
V
E
S
SE 282ND ST
14
4
T
H
A
V
E
S
E
17TH ST SE
S 296TH ST
25TH ST SE
12TH ST SE
55
T
H
A
V
E
S
1
8
5
T
H
A
V
E
E
21
4
T
H
A
V
E
E
D
S
T
S
E
1ST AVE SE
TA
C
O
M
A
B
L
V
D
A
U
B
U
R
N
-
E
N
U
M
C
L
A
W
R
D
D
S
T
N
W
A
S
T
N
E
4TH ST SE
TB
D
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L
E
R
Y
A
V
E
30TH ST NE
10
8
T
H
A
V
E
EA
S
T
B
L
V
D
(
B
O
E
I
N
G
)
11
2
T
H
A
V
E
S
E
SE 316TH ST
14
8
T
H
A
V
E
S
E
T
A
C
O
M
A
P
O
I
N
T
D
R
E
55TH ST SE
E
V
E
R
G
R
E
E
N
W
A
Y
S
E
D
S
T
N
E
M
S
T
N
W
O
S
T
N
E
S
E
3
6
8
T
H
P
L
W
S
T
N
W
1
6
9
T
H
A
V
E
E
S 287TH ST
3RD AVE S
5TH AVE SW
E
S
T
N
E
37TH ST NE
14
2
N
D
A
V
E
E
S 316TH ST
H
A
R
V
E
Y
R
D
S
C
E
N
I
C
D
R
S
E
H
S
T
N
W
M
A
I
N
S
T
S 292ND ST
WE
S
T
B
L
V
D
(
B
O
E
I
N
G
)
44TH ST NW
3RD AVE SW
11
8
T
H
A
V
E
E
10TH ST NE
CL
A
Y
S
T
N
W
4TH AVE SW
14
8
T
H
A
V
E
E
7TH ST SE
13
7
T
H
A
V
E
E
26
T
H
S
T
E
13
6
T
H
A
V
E
E
SE 310TH ST
S 3RD AVE
TH
O
R
T
O
N
A
V
E
S
W
2
0
0
T
H
A
V
E
E
17TH
S
T
E
RIVE
R
D
R
BOUNDARY BLVD
LEA HIL
L
R
D
S
E
32ND ST E
11
8
T
H
A
V
E
S
E
58
T
H
A
V
E
S
AL
G
O
N
A
B
L
V
D
N
10
4
T
H
A
V
E
S
E
S 372ND ST
J
S
T
N
E
ROY RD SW
4TH ST NE
PA
C
I
F
I
C
A
V
E
S
11
0
T
H
A
V
E
S
E
14TH ST NE
D
R
I
V
E
W
A
Y
SE 281ST ST
16
0
T
H
A
V
E
S
E
12
6
T
H
A
V
E
E
5TH ST SE
72
N
D
A
V
E
S
56
T
H
P
L
S
25TH ST E
BR
I
D
G
E
T
A
V
E
S
E
57
T
H
A
V
E
S
S 328TH ST
DO
G
W
O
O
D
S
T
S
E
2ND AVE SW
8TH ST SE
S 279TH ST
L
S
T
S
E
T
S
T
S
E
F
S
T
S
E
FR
O
N
T
A
G
E
R
D
C
O
T
T
A
G
E
R
D
E
S 358TH ST
FO
S
T
E
R
A
V
E
S
E
52
N
D
A
V
E
S
SE 274TH ST
16
6
T
H
A
V
E
E
1ST AVE N
SE 299TH ST
SE 316TH PL
SE 284TH ST
49TH ST NE
S 362ND ST
I
S
T
N
W
54
T
H
A
V
E
S
A
S
T
S
W
57
T
H
P
L
S
U
S
T
N
W
32ND ST NE
7
8
T
H
A
V
E
S
3RD ST E
D
E
E
R
I
S
L
A
N
D
D
R
E
13
5
T
H
A
V
E
S
E
47TH
S
T
S
E
2
0
4
T
H
A
V
E
E
28TH ST NE
8
6
T
H
A
V
E
S
S 356TH ST
J
S
T
S
E
R S
T
N
W
27TH ST E
15TH ST E
28TH ST E
MI
L
I
T
A
R
Y
R
D
S
13TH ST E
K
S
T
S
E
OL
I
V
E
A
V
E
S
E
10TH ST E
10
8
T
H
A
V
E
E
SE 323RD PL
B
S
T
S
E
WY
M
A
N
D
R
26TH ST SE
S 336TH ST
ST
P
A
U
L
B
L
V
D
S 340TH ST
C
S
T
S
E
B S
T
N
E
32ND ST SE
S 300TH ST
1ST AVE S
36TH ST SE
ELM LN
SE 301ST ST
2
0
8
T
H
A
V
E
E
SE 287TH ST
V
S
T
N
W
2ND ST SE
23RD ST SE
4TH AVE S
3RD ST SE
QU
I
N
C
Y
A
V
E
S
E
21ST ST NE
1
5
6
T
H
A
V
E
E
14
0
T
H
A
V
E
E
HE
M
L
O
C
K
S
T
S
E
1
8
4
T
H
C
T
E
5
6
T
H
A
V
E
S
SE 298TH PL30TH ST NW
30TH ST SE
S 318TH ST
24TH ST SE
2ND AVE S
14TH ST E
H
S
T
N
E
LU
N
D
R
D
S
W
S 324TH ST
PI
K
E
S
T
N
W
21ST ST E
31ST ST E
42ND ST NW
6TH AVE SW
11
9
T
H
A
V
E
E
SE 286TH ST
9TH ST SE
55T
H
P
L
S
SE 276TH PL
65
T
H
A
V
E
S
SE 295TH PL
G
S
T
N
E
27TH ST SE5TH AVE N
SK
I
N
N
E
R
R
D
12
8
T
H
A
V
E
E
S 354TH ST
S 344TH ST
SE 364TH ST
SE 290TH ST
10TH ST SE
D
S
T
S
W
SE 280TH ST
2
1
1
T
H
A
V
E
E
NA
T
H
A
N
A
V
E
S
E
V
S
T
S
E
1
0
4
T
H
P
L
S
E
HI
C
R
E
S
T
D
R
B PL NW
SE 294TH ST
72ND ST SE
S 285TH ST
6TH ST NW
14
6
T
H
A
V
E
S
E
SE 293RD ST
3RD ST NW
12
6
T
H
A
V
E
S
E
I
S
A
A
C
A
V
E
S
E
S 312TH ST
EL
M
S
T
S
E
CLAY ST
S 370TH ST
20TH ST E
52
N
D
P
L
S
7TH ST E
19TH DR NE
SE 307TH PL
51ST
S
T
S
E
10TH AVE N
S 364TH ST
14
0
T
H
A
V
E
S
E
28TH ST SE
15TH ST SE
13
3
R
D
A
V
E
S
E
10
8
T
H
A
V
E
S
E
73RD ST SE
SE 295TH ST
26TH ST NE
S 366TH ST
SE 297TH ST
2
1
0
T
H
A
V
E
E
66TH ST SE
24TH ST NE
SE 296TH ST
SE 285TH ST
S 368TH ST
AL
D
E
R
L
N
S
11
7
T
H
A
V
E
S
E
U
S
T
S
E
19TH ST SE
6TH ST SE
11
0
T
H
P
L
S
E
A ST E WA
R
D
A
V
E
S
E
15
6
T
H
A
V
E
S
E
21ST ST SE
R PL NE
11
7
T
H
A
V
E
E
10
5
T
H
A
V
E
S
E
7TH ST
5TH ST NE
53
R
D
A
V
E
S
HE
A
T
H
E
R
A
V
E
S
E
F
S
T
N
E
11
2
T
H
P
L
S
E
51
S
T
P
L
S
SE 292ND ST
D PL SE
S 320TH ST
SE 272ND PL
8TH ST SW
6TH AVE N
22ND ST E
12
3
R
D
A
V
E
E
63
R
D
P
L
S
2ND CT NW
1ST ST NE
R
S
T
N
E
12
9
T
H
P
L
S
E
O
C
T
S
E
S 342ND ST
26TH ST NW
SE 321ST PL
11
4
T
H
P
L
S
E
53
R
D
A
V
E
S
M
S
T
N
W
17TH ST E
SE 292ND ST
SR 18
SE 282ND ST
SE 272ND ST
SR
1
6
7
10
8
T
H
A
V
E
S
E
10
4
T
H
A
V
E
S
E
D
R
I
V
E
W
A
Y
TBD
TBD
TB
D
12
4
T
H
A
V
E
S
E
14
8
T
H
A
V
E
S
E
SR
1
6
7
14
4
T
H
A
V
E
S
E
51ST
S
T
S
E
SR
1
6
7
20
0
T
H
A
V
E
E
2ND ST SE
DRIVEWAY
SE 284TH ST
55
T
H
A
V
E
S
TB
D
H
S
T
N
E
C S
T
N
W
SE 301ST ST
V
S
T
S
E
SR 1
8SR 1
8
SE 288TH ST
9TH ST E
56
T
H
A
V
E
S
SR
1
6
7
14
2
N
D
A
V
E
E
26TH ST NE
SE 282ND ST
17TH ST SE
TB
D
SR
1
6
7
51
S
T
A
V
E
S
TBD
S 277TH ST
SE 272ND ST
T
B
D
16TH ST E
TB
D
SE 274TH ST
TB
D
21ST ST E
TBD
24TH ST E
TBD
10
8
T
H
A
V
E
E
TB
D
M
S
T
N
E
8TH ST E
SR
1
6
7
TB
D
R
S
T
N
W
8TH ST E
1ST AVE N
51
S
T
A
V
E
S
S 277TH ST
32ND ST E
SR
1
6
7
TBD
R
S
T
N
W
D
R
I
V
E
W
A
Y
32ND ST E
12TH ST E
SR
1
6
7
D
S
T
S
E
8TH ST NE
SE 296TH ST
13TH ST E
DRIVEWAY
SR 18
55T
H
P
L
S
TBD
OPC8
OPC4
OPC11
OPS1
OPC9
OPC1 OPC3
OPC6OPC7
OPC5OPC2
OPC10
OPS2
OPS3
OPS4
OPS5
OPS6
COMPREHENSIVE STORM DRAINAGE PLAN
1 inch = 4,000 feet
April 2015
P:
\
A
u
b
u
r
n
\
1
4
5
2
9
5
A
u
b
u
r
n
S
t
o
r
m
w
a
t
e
r
C
o
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p
P
l
a
n
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G
I
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P
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l
i
m
i
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a
r
y
D
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P
l
a
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\
A
u
b
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S
t
o
r
m
_
F
i
g
4
-
6
(
c
r
i
t
f
a
c
)
.
m
x
d
0 4,000 8,000
Feet
Figure 4-6City and Storm DrainageCritical Facilities forthe City of Auburn
LEGEND
!(S1 Storm Critical Facility
!(C1 City Critical Facility
Roadway
Watercourse
Water Body
Wetland
Auburn City Boundary
OPC1 OPC3
OPC5
OPC2
A
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SR 18
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3RD ST NE
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5TH ST SW
SR 18
6TH ST SE
8TH ST SE
D
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7TH ST SE
SR 18OPS1OPS2
SEE INSET
INSET
¯
CITY CRITICAL FACILITIES C1 City Hall 25 W Main Street C2 City Hall Annex 1 E Main Street C3 Justice Center 340 E Main Street C4 Maintenance and Operations 1305 C Street SW C5 Regional Hospital 210 N Division Street C6 Senior Center 808 9th Street SE C7 VRFA Station 31 1101 D Street NE C8 VRFA Station 32 1951 R Street SE C9 VRFA Station 33 500 182nd Avenue E C10 VRFA Station 34 31290 124th Avenue SE C11 VRFA Station 35 2905 C Street SW
STORM CRITICAL FACILITIES S1 A Street PS 404 A Street SE S2 Auburn Way S PS 405 Auburn Way S S3 Brannan Park PS 1302 30th Street NE S4 Emerald Park PS 499 42nd Street NE S5 West Main Street PS 1410 W Main Street S6 White River PS 4640 A Street SE S7 M Street PS 410 M Street SE
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23RD ST SE
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21ST ST NE
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10
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S 318TH ST
24TH ST SE
2ND AVE S
14TH ST E
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LU
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S 344TH ST
SE 364TH ST
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10TH ST SE
D
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1
1
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S 285TH ST
6TH ST NW
14
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S
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3RD ST NW
16TH ST SE
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S 370TH ST
20TH ST E
52
N
D
P
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7TH ST E
19TH DR NE
SE 307TH PL
10TH AVE N
SE 314TH ST
S 364TH ST
14
0
T
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A
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S
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72ND ST SE
15TH ST SE
13
3
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10
8
T
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A
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S
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73RD ST SE
SE 295TH ST
26TH ST NE
S 366TH ST
SE 297TH ST
2
1
0
T
H
A
V
E
E
66TH ST SE
24TH ST NE
SE 296TH ST
SE 285TH ST
S 368TH ST
AL
D
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L
N
S
11
7
T
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A
V
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S
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S
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S
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19TH ST SE
6TH ST SE
11
0
T
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P
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A ST E
15
6
T
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A
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S
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21ST ST SE
R PL NE
11
7
T
H
A
V
E
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10
5
T
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A
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E
S
E
7TH ST
5TH ST NE
53
R
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A
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A
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F
S
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N
E
11
2
T
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P
L
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51
S
T
P
L
S
SE 292ND ST
D PL SE
S 320TH ST
SE 272ND PL
8TH ST SW
6TH AVE N
22ND ST E
12
3
R
D
A
V
E
E
TH
O
R
T
O
N
P
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S
W
2ND CT NW
1ST ST NE
12
9
T
H
P
L
S
E
6TH ST NE
3RD ST NE
O
C
T
S
E
S 342ND ST
SE 315TH PL
26TH ST NW
SE 321ST PL
11
4
T
H
P
L
S
E
SR 18
SR
1
6
7
17TH ST E
72
N
D
A
V
E
S
9TH ST E
SE 274TH ST
SE 292ND ST
SE 282ND ST
SE 301ST ST
M
S
T
N
E
24TH ST E
8TH ST E
V
S
T
S
E
20
0
T
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A
V
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M
S
T
S
E
53
R
D
A
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SR
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6
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SR
1
6
7
SR 1
8
32ND ST E
12TH ST E
10
8
T
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A
V
E
S
E
2ND ST SE
SR 18
16TH ST E
32ND ST E
D
S
T
S
E
SR
1
6
7
M
S
T
N
W
H
S
T
N
E
SE 272ND ST
R
S
T
N
W
SE 272ND ST
55T
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P
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SE 282ND ST
51
S
T
A
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SR
1
6
7
14
4
T
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51
S
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A
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26TH ST NE
DRIVEWAY
8TH ST NE
13TH ST E
S 277TH ST
23RD ST SE
55
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A
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A
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SR
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10
8
T
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A
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56
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A
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S
1ST AVE N
R
S
T
N
W
21ST ST E
SR 1
8
D
R
I
V
E
W
A
Y
SE 288TH ST
SR
1
6
7
S 277TH ST
14
8
T
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A
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S
E
SR
1
6
7
SE 304TH S
T
17TH ST SE
P1
P7 P8
P2
P6
P4B P4A
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P3
P5
COMPREHENSIVE STORM DRAINAGE PLAN
1 inch = 4,000 feet
April 2015
LEGEND
!(Drainage Problem Vicinity
!(Hillside Discharge Location
Roadway
Watercourse
Water Body
Wetland
Auburn City Boundary
P:
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Feet
Figure 4-7Drainage Problem Locations forthe Storm Drainage Utility¯
ID Location P1 South of West Main Street east of the SR 167 overpass P2 Intersection of 37th Street NW and I Street NW P3 Hillsides throughout the city P4A East of I Street NE between 32nd Street NE and 35th Street NE P4B C Street NE between 30th Street NE and 37th Street NE P5 West Hills P6 Northern extent of airport property near 30th Street NE P7 Western end of 25th Street SE near D Street SE right-of-way P8 23rd and K Streets SE
5-1
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Chapter 5
Evaluation of the Storm Drainage
Utility
This chapter presents analyses conducted to evaluate the Storm Drainage Utility and identify gaps
between existing service levels and the desired LOS described in Section 3.2.2. The following types of
evaluations were completed to identify Storm Drainage Utility future activities to address the range of
LOS goals:
• Hydraulic: gather system data, update or develop computer models, assess hydraulic performance,
and develop capital improvement projects with respect to LOS and associated system design criteria
• Asset management: develop system requirements specification for integrating the City’s pipe
criticality database, which is the basis of the City’s pipe repair and replacement asset management
model, into the City’s Cartegraph CMMS
• Environmental: determine differences between the 2013–18 permit and previous NPDES Permit,
and evaluate how the differences could affect City regulations, facilities, and activities; conduct an
NPDES program gap analysis; update the existing Compliance Work Plan; and estimate the time and
costs for NPDES Permit compliance
• Maintenance and operations: assess process performance, equipment, and personnel with respect
to LOS for M&O
These evaluations were conducted to develop capital improvements for the 6- and 20-year horizons, as
well as identify future M&O needs. The following sections summarize the hydraulic, asset management,
and environmental evaluations. The M&O evaluations are described in Chapter 6.
Hydraulic Evaluation 5.1
As described in Chapter 4, the City of Auburn owns and operates a large system of stormwater drainage
infrastructure to collect and convey stormwater runoff to nearby receiving waters. For the 2009 Plan,
models were developed to assess the system on a per basin or problem area scale in MIKE URBAN4
software. Subsequent to the 2009 Drainage Plan, the City converted the existing hydraulic models to the
PCSWMM5 software platform and updated the models with new survey data, and construction and
record drawings. Additionally, some models were updated by calibrating to flow monitoring data collected
in 2010 and 2011.
4 MIKE URBAN is a GIS-integrated, modular software program developed by the Danish Hydraulic Institute for modeling water
distribution and collection systems. The stormwater module is internally powered by the SWMM5 engine, which is public domain
software distributed by EPA. Information about MIKE URBAN software can be found at
http://www.dhigroup.com/Software/Urban/MIKEURBAN.aspx.
5 PCSWMM is a GIS-based hydraulic and hydrologic modeling platform developed by Computational Hydraulics International
(CHI). The software fully supports the EPA SWMM5 hydrology and hydraulics engine, thus providing comparable computation
between EPA SWMM and PCSWMM models. Information about PCSWMM software can be found at
http://www.chiwater.com/Software/PCSWMM/index.asp.
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Hydraulic modeling efforts for the 2015 Drainage Plan focused on updating those models covering
locations of existing problems as described in Chapter 4. The model updates were based on recent GIS
data, design drawings, and record drawings. Some model updates also included calibration to flow
monitoring data collected in 2010 and 2011. For problem areas that had not been previously modeled,
new PCSWMM models were developed or WWHM 6 was used to estimate flow for capital improvement
project sizing.
The following sections describe the steps used to update existing models or develop new models.
5.1.1 Updating Existing Models
The hydraulic components of existing models were updated with recent GIS data. The following model
data were verified against the GIS data:
• pipe size
• pipe invert elevations
• pipe material (for estimating pipe roughness)
• node rim elevation
• system connectivity
Where the GIS data did not accurately describe the existing system, technical reports, record drawings,
or construction drawings were used to update the model. Where data were available, models were given
more detail with respect to pump and storage facility information.
For model hydrology, subcatchment delineations within problem areas were reviewed and revised based
on recent GIS data, topographic data, and 2012 aerial photography. Total impervious area was
estimated with the City’s impervious area coverage. Subcatchment slope was estimated as the average
slope based on a digital elevation model. Where available, flow monitoring data were used to calibrate
modeled flow by adjusting effective impervious area and soil conductivity parameters.
5.1.2 Creating New Models
The following is a general description of steps followed to develop new PCSWMM models:
1. Infrastructure data from existing GIS databases were used to build drainage networks in problem
areas. Drainage network models consist of catch basins, manholes, pipes, junctions, ditches, control
structures, vaults, storage ponds, pump stations, and outfalls. GIS data were validated and
augmented as necessary based on record drawings and City-conducted field investigations.
2. The drainage network was developed to a level of detail that is sufficient for analyzing conveyance
on a subbasin-wide or problem-specific scale. In general, pipes 1 foot in diameter or greater were
included; smaller-diameter pipes and pipes that were part of private systems were generally not
included in the model unless they provided an important link within the system.
3. Subbasin areas were divided into smaller drainage area delineations called subcatchments, which in
the model are linked into the drainage network at specific nodes. Hydrologic parameters such as
area, slope, and percent impervious area are developed for each subcatchment. Subcatchment
slope was estimated as the average slope based on a digital elevation model (DEM). Total
impervious area was estimated with the City’s impervious area coverage.
6 WWHM is a western Washington-specific hydrology model developed for the Washington State Department of Ecology. The
software is based on HSPF continuous-simulation hydrology methodologies and uses regional HSPF parameters and long-term
recorded precipitation data. Information about WWHM software can be found at
http://www.ecy.wa.gov/Programs/wq/stormwater/wwhmtraining/index.html.
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4. Models were calibrated using either pump runtime data or flow monitoring data where available.
5. Long-term simulations were performed to determine the 2 percent and 4 percent exceedance
storms (one in 50-year and one in 25-year flows, respectively). These storms were used as design
storms to identify ways to alleviate existing drainage problems through capital improvements, which
meet the LOS (see Chapter 7 for a description of proposed capital improvements).
The following is a general description of steps followed to develop new WWHM models:
1. Subcatchments within subbasins were delineated with existing GIS information including 2012
aerial photography, roadway extents, contours, and drainage network (catch basins, manholes,
pipes, ditches, infalls, and outfalls).
2. Existing GIS information was used to determine hydrologic parameters, per subcatchment, used by
WWHM such as hydrologic soil type, slope, and impervious area. Since subbasins were relatively
small, slope was estimated from City 2-foot contour data, instead of the coarser DEM. Total
impervious area was estimated with the City’s impervious area coverage. 2012 Aerial photography
was used to estimate vegetation.
3. WWHM model results provide annual peak flows, and determines the 2 percent and 4 percent
exceedance storms (one in 50-year and one in 25-year flows, respectively). These flows were used
as design storms to identify ways to alleviate existing drainage problems through capital
improvements, which meet the LOS (see Chapter 7 for a description of proposed capital
improvements).
Appendix C provides a detailed description of the hydrologic and hydraulic (H&H) modeling
methodologies.
Asset Management Evaluation 5.2
All utilities manage their assets in one way or another through maintenance practices, capital
improvement projects, and R&R activities. However, for most storm drainage utilities, the means of
deciding where and how to direct limited resources has often been done in a reactive, ad hoc approach
based on incomplete or incorrect information. In contrast, asset management is a systematic approach
to maintaining assets in good working order to minimize future costs of maintaining and replacing them,
especially to avoid costly deferred maintenance. The best practices for asset management involve
systematically basing choices on an understanding of asset condition and performance, risks, and costs
in the long term. Asset best practices include:
• having knowledge about assets and costs (i.e., detailed inventories)
• maintaining desired LOSs
• taking a life-cycle approach to asset management planning
• implementing the planned solutions to provide reliable, cost-effective service
• establishing funding levels and rates to support ongoing infrastructure rehabilitation or replacement
projects
The first step to effectively managing storm drainage assets is to establish LOS goals for the City’s Storm
Drainage Utility as described in Chapter 3 of this Drainage Plan. The second step is preparing a
comprehensive inventory of the assets. The next steps include performing asset assessments and
economic analyses to estimate life-cycle costs and the risk associated with each of the City’s storm
drainage assets.
Asset management evaluations completed for the 2009 Drainage Plan focused on pipes and pump
stations. A pipe criticality database and an economic life model were developed. The pipe criticality
database contained data (i.e. pipe diameter, age, length, material, depth of bury, condition) describing
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the current conditions of the pipe network. The data in the database were the basis for the economic life
model. The economic life model was used to evaluate the life-cycle costs and risk for the City’s drainage
pipe assets. The model estimated a risk cost associated with each asset by multiplying a probability of
failure in a given year by the cost (including capital, social, and environmental costs) of that asset failing.
Then the risk cost associated with each asset was compared to the life-cycle cost of owning the asset to
estimate the timing for repair or replacement.
The results of the economic model are only as good as the input data describing the pipes. For the 2009
planning effort, the pipe inventory was incomplete and pipe data for many pipes were missing. Since
then, the City has systematically been inventorying the system, and collecting necessary pipe data which
are stored in GIS for future link to Cartegraph. A quarter of the system, however, is still missing pipe
material and/or installation date data, which are needed for the economic life model (Figure 5-1). The
City are in the process of collecting these data.
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Figure 5-1. Drainage Pipe Summary
Unknown
4%
< 12 inches
21%
12–22 inches
65%
24–30 inches
7%
36–51 inches
3%
>= 54 inches
< 1%
Unknown
< 12 inches
12–22 inches
24–30 inches
36–51 inches
>= 54 inches
Pipe Diameter
Unknown
27%
ADS
2%
CMP
7% Concrete
23% Ductile iron
6%
HDPE
1%
Other
< 1%
PVC
34%
Unknown
ADS
CMP
Concrete
Ductile iron
HDPE
Other
PVC
Pipe Material
Unknown
24%
1960s
4%
1970s
4% 1980s
15% 1990s
22%
2000s
25%
2010s
6%
Unknown
1960s
1970s
1980s
1990s
2000s
2010s
Pipe Installation Date
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Evaluations completed for this Drainage Plan consisted of developing a system requirements
specification for implementing the economic life model using the data in the City’s asset management
system, Cartegraph (Brown and Caldwell, 2014). Once the pipe inventory is complete, and the economic
life model is implemented, the model can be rerun and used to inform future R&R priorities. Currently,
the economic life model includes only collection system piping, and there is an opportunity to expand the
model to include the catch basins and manholes, as described in Chapter 8.
Environmental Investigation 5.3
The federal Clean Water Act requires municipalities to help maintain fishable/swimmable waters through
the NPDES Permit Program (see Section 2.3.2 and Appendix A), which requires municipalities to reduce
the discharge of pollutants from their stormwater systems to the MEP by implementing municipal
stormwater management programs. The City has an established municipal SWMP that complies with all
Permit requirements currently in effect. Updates to the City’s codes, programs, and standards are being
developed to comply with the requirements of the updated 2013 NPDES Permit.
The City’s SWMP Plan identifies activities that will be implemented by the City to comply with NDPES
Permit requirements. The SWMP Plan is updated annually to reflect new requirements that phase in
during each year, including one-time and new ongoing activities. An updated SWMP Plan is submitted to
Ecology in March of each year. The City’s current SWMP Plan is accessible on the City website.
To plan for upcoming requirements of the new NPDES permit, the City formed a project team consisting
of staff from the City Attorney’s office, the City Community Development and Public Works, and Brown
and Caldwell.
The project team reviewed Auburn’s City-wide stormwater management programs, codes, standards,
processes, and documentation protocols in order to identify potential actions to comply with the NPDES
Permit conditions over the 5-year Permit period. From these documents, the project team created a
database cataloging responsible City departments/entities, reference documents, and potential
requirements for each updated section of the Permit. Interviews were then conducted with appropriate
staff (e.g., stormwater M&O staff) to discuss the potential implications of Permit changes for existing City
codes, programs, and standards. The information on existing City practices and programs was then
compared to the updated Permit requirements to identify potential compliance needs. Some policy
issues and potential compliance strategies were also identified. The results of this analysis were used as
the foundation for development of a 5-year Compliance Work Plan (see Appendix B). Recommended
future activities from the Compliance Work plan are summarized in Chapter 8.
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Chapter 6
Maintenance and Operations
An evaluation of existing Storm Drainage Utility M&O activities was conducted in support of this Drainage
Plan. This chapter documents existing Storm Drainage Utility M&O activities with the primary purpose of
establishing a baseline understanding of the proactive and responsive maintenance procedures
performed by City Storm Drainage Utility M&O staff. This baseline understanding is used herein to
evaluate utility staffing, data collection and computerized record-keeping needs, and other utility needs
necessary to continue to meet LOS goals.
The information provided in this chapter is a summary of information collected during City Storm
Drainage Utility staff interviews, review of computerized records, and existing utility forms/checklists.
Utility Responsibility and Authority 6.1
This section provides an overview of the Storm Drainage Utility organization and basic information
related to utility staffing, training, and education.
6.1.1 Organizational Structure
The City Storm Drainage Utility is operated as a utility enterprise under the direction of the Director of
Community Development and Public Works. The Department of Community Development and Public
Works is responsible for planning, design, construction, operation, maintenance, quality control, and
management of the storm drainage system. The City has a mayor-council form of government; therefore,
the Director of Community Development and Public Works reports to the Mayor, with input from Council
through Council study sessions and meetings. The Mayor and the City Council provide oversight for the
implementation of policies, planning, and management for the Storm Drainage Utility.
Engineering Services (Engineering) within Community Development and Public Works is the lead group
for comprehensive storm drainage system planning; development of a CIP; and the design, construction,
and inspection of projects related to the storm drainage system. The Assistant Director of
Engineering/City Engineer oversees Engineering and reports directly to the Community Development and
Public Works Director.
Maintenance and Operations Services is the group responsible for the day-to-day maintenance and
operation of the storm drainage system. The Sewer/Storm Drainage Operations Manager reports to the
Assistant Director of Public Works Operations, and oversees nine storm drainage employees including a
field supervisor. Vegetation Maintenance Division is responsible for mowing, tree trimming and weed
control of city properties and facilities.
The overall Community Development and Public Works Department organizational structure is shown in
Figure 2-1.
6.1.2 Staffing Level
The Storm Drainage Utility currently includes eight full-time M&O field staff, two seasonal staff, plus a
field supervisor and an M&O manager, who perform administrative duties. This chapter does not include
an evaluation of utility management, including regulatory compliance, planning, and coordination with
other City departments. Position titles and the primary functions of the M&O staff working within the
Storm Drainage Utility are shown in Table 6-1.
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Table 6-1. Storm Drainage Utility M&O Personnel
Position Primary function(s)
Sewer/Storm Manager Management of sewer and storm M&O staff
Storm field supervisor Supervision of field staff
Maintenance worker II Seven full-time staff dedicated to field inspection and maintenance
Maintenance worker I One full-time staff dedicated to field inspection and maintenance
Seasonal employee Two seasonal staff, for four months of the year, for field inspection and
maintenance
In addition to the M&O field staff identified in Table 6-1, full-time and seasonal staff support the
following Storm Drainage functions:
• Management and administration: A full-time manager performs administrative duties for both the
Sewer and Storm Divisions. Management and administrative tasks include general oversight of the
Sewer and Storm Drainage utilities M&O staff, regulatory compliance, planning, and coordination
with other City departments. Field work is supervised by a full-time field supervisor.
• Vegetation maintenance: The Vegetation Maintenance Division consists of six full-time and three
seasonal staff. These staff primarily (approximately 90 percent of total staff effort) support the
Storm Drainage Utility M&O field staff with pond vegetative control, weed control and herbicide
spraying, right-of-way and ditch mowing, tree trimming and removal, and leaf removal.
• Contracted services: The Storm Drainage Utility utilizes other City departments or external
contractors for some services, as discussed in Section 6.3.
M&O activities routinely performed by Storm Drainage Utility staff are discussed in Section 6.2.
Additional M&O activities, performed by other City divisions or contracted services on behalf of the Storm
Utility are discussed in Section 6.3. The staffing plan presented in Section 6.6 considers M&O activities
performed by Storm Drainage Utility and Vegetation Maintenance staff.
6.1.3 Level of Service
The Storm Drainage Utility operates in accordance with the LOS criteria outlined in Chapter 3, and
internally adopted goals integral to meeting those levels. These goals are generally based on the current
staffing level and tasks deemed most critical to the City and its residents. However, the existing staffing
requirements discussed in Section 6.6 herein include near-term goals, which may not be met by existing
staff.
6.1.4 Training and Education
The City recognizes the value of having a knowledgeable and well-trained staff operating the storm
drainage system, and encourages employees to obtain the highest level of training available. At this
time, the State of Washington does not require certification for stormwater maintenance operators but
the City would support any effort to establish certification for these positions. Seminars, conferences,
and college coursework have become tools to advance knowledge for maintenance staff.
Many M&O staff are specialized in specific job functions, which can promote expertise through
specialization but also has the potential to limit the ability of the utility to absorb absences due to
vacation, sickness, retirement, resignation, and termination. To mitigate this limitation, the City has
broadened the scope of the Storm Drainage Utility’s education system by initiating a cross-training
program.
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Routine Operations Provided by the Storm Drainage Utility 6.2
This section discusses routine operations provided by the Storm Drainage Utility M&O staff shown in
Table 6-1. Each sub-section provides a brief description of the M&O activity, City goals with respect to
proactive maintenance, and the estimated Storm Drainage Utility staff effort to achieve the proactive
maintenance goal.
6.2.1 Catch Basin and Manhole Inspection, Cleaning, and Repair
The storm drainage system includes approximately 8,880 catch basins and 2,330 manholes. Catch
basin and manhole maintenance includes initial inspection and potential follow-up cleaning and/or
repair. Inspection is performed by two person using utility mapping to locate the targeted facilities. M&O
staff use an inspection checklist to identify which facilities require further cleaning or repair. The
checklist includes items such as observation of trash, debris, sediment, or vegetation blocking or within
the catch basin/manhole; structural damage; evidence of contamination or pollution; and the integrity of
catch basin grates, manhole covers, and ladders. Follow-up cleaning and maintenance work orders are
generated based upon the results of initial inspection and typically include a two-person crew. Based
upon recent maintenance history, it is assumed that approximately one in five catch basin/manhole
inspections leads to further cleaning. The City assumes that a total of 250 catch basins and manholes
per year require some level of maintenance/repair.
Catch basin inspection is required as part of the City’s NPDES Phase II Municipal Stormwater Permit,
recently updated in August 2013. Beginning in 2015, the City is required to inspect and maintain all
catch basin facilities every 2 years. To achieve this permit requirement, the City goal is to inspect 60
catch basins per day. Manhole inspection frequency is not mandated by the permit, but the City’s goal is
to complete inspection of all City manholes on a 4-year rotating schedule.
In the future, the City intends to demonstrate (through maintenance records) that catch basins do not
require inspection every 2 years. The City will use Cartegraph software (see Section 6.5) to record and
track results of catch basin inspection, cleaning, and maintenance efforts.
6.2.2 Stormwater Pipeline Cleaning and CCTV
The storm drainage system includes approximately 210 miles of collection system piping. Cleaning and
inspection of the storm drainage system is performed using City-owned vactor/jet truck and closed-
circuit television (CCTV) equipment. Cleaning and CCTV inspection are typically performed in tandem
from structure to structure (i.e., catch basin or manhole) by a two-person crew for each task.
Jetting of stormwater pipelines and subsequent vactor truck suction is the principal means of removing
debris or obstructions from the storm drainage system. A hose with a special end fitting is inserted into a
pipe and high-pressure water (up to 2,500 pounds per square inch) is sent through the hose. The high-
pressure water exits the small hole at the tip of the nozzle, breaking down and/or scouring obstructions.
Debris is then removed via suction by the vactor truck equipment at each manhole.
Following cleaning, CCTV inspection is performed to identify structural defects and potential pipeline
leaks. “Lamping” inspections, where the camera is inserted into the manhole or catch basin but not
advanced through the pipe system, are typically performed as a first step of the CCTV process. Although
the visual range is limited, lamping can identify structures and piping in very good condition. In these
cases, no additional CCTV inspection is completed. Lamping is generally limited to areas of newer pipe or
low-priority facilities.
Routine CCTV inspection of the storm drainage system is an essential component of the M&O program
as it can identify trouble spots before larger failures occur and can provide the City with accurate
information about the condition of the storm drainage system. Since the end of 2007, inspection reports
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and digital video captured by the CCTV crews have been stored within the City’s computer network
(flexidata software). While the ability to edit information in flexidata is limited to licensed machines, the
flexidata reader is available for all City staff. Currently, the City does not have the ability to transfer the
data stored in flexidata, specifically a summary of pipe condition, to the more comprehensive data
stored within Cartegraph, the utility CMMS software. A primary goal of the utility in the near future is to
use the results of CCTV inspection to populate pipe conditions fields within Cartegraph in order to
provide a more accurate planning tool based upon the known condition of storm drainage system
assets.
The City’s goal is to clean and inspect all stormwater collection pipes within the system on a 15-year
cycle. On average, a two-person crew can clean approximately 1,500 feet of pipe per day and inspect
approximately 500 feet of pipe per day.
6.2.3 Stormwater Outfall Inspection, Cleaning, and Maintenance
The storm drainage system includes 65 outfalls, or discharges from localized collection systems to the
Green River, White River or Mill Creek. Outfall maintenance includes initial inspection and potential
follow-up corrective actions. Outfall inspections are performed to identify excessive vegetative growth
that could obstruct flow, outfall erosion protection, structural damage to the pipe itself, and abnormal
discharge from the pipe that might be indicative of contamination (i.e., color/sheen or odor). Follow-up
cleaning and maintenance work orders are generated based upon the results of initial inspection. The
City goal is to inspect each outfall seasonally (four times per year) and to perform maintenance at least
annually, or at a greater frequency depending upon inspection results. On average, inspection and
maintenance activities require 0.75 hour and 1.0 hour, respectively, for a two-person crew.
6.2.4 Drainage Ditch Maintenance and Restoration
The storm drainage system includes approximately 40 miles of drainage ditches. Drainage ditch
maintenance is required to preserve the original line and grade, hydraulic capacity, and purpose of the
ditch. Routine maintenance activities include re-grading and removal of sediment; nuisance vegetation;
and isolated obstructions such as trash, trees, and accumulated debris. Because vegetation is important
for erosion control, the City strives to minimize the removal of beneficial vegetation.
Drainage ditch maintenance efforts are time-consuming for the Storm Drainage Utility. Up to six M&O
staff are required for a single ditch maintenance crew to operate the City-owned excavator, control traffic
(as necessary), and manually re-grade or remove obstructions. The City assigns a six-person ditch
maintenance crew approximately 15 days per year (3 days per week for 1, out of 4, month in the
summer). On average, these crews can complete 200 feet of ditch maintenance per day. The City’s goal
is to maintain all ditches within the system on a 20-year cycle.
6.2.5 Stormwater Pond and Swale Inspection, Maintenance, and Restoration
Inspection of the approximately 168 City stormwater ponds and 75 swales is performed by a two-person
crew using an inspection checklist to identify conditions that require correction. The checklist includes
items such as observation of trash, debris, sediment, and animal or insect infestation that could impact
pond function or future maintenance; structural damage or erosion; evidence of contamination or
pollution; and the integrity/function of emergency overflow spillways. On average, inspection activities
require 1.0 hour for a two-person crew per location. Follow-up maintenance and restoration is scheduled
during the summer months. The City assigns a six-person stormwater pond/swale crew approximately 45
days per year (3 days per week for 3, out of 4, months in the summer).
The City goal is to inspect each pond/swale twice per year. Maintenance and restoration are performed
as necessary. After major storms (greater than 10-year events), it is recommended that some
stormwater ponds be inspected briefly to verify proper function and identify damage, if any. It is
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recommended that the City develop a list of ponds that should be inspected following these major
storms. Some larger City ponds have been maintained by King County staff, as discussed in Section 6.3.
6.2.6 Culvert Inspection and Cleaning
Culvert maintenance includes inspection and cleaning of the approximately 800 culverts within the
storm drainage system. Culverts are typically inspected by a two-person crew, with corrective actions and
cleaning performed during the inspection when possible. On average, inspection and cleaning activities
require 0.75 hour for a two-person crew. Culvert inspection focuses on the assessment of free flow
within the culvert and identifying any structural defects. Any debris that cannot be removed during the
initial inspection or any noted structural concerns result in a work order for corrective action. The City
goal is to inspect (and clean as necessary) each culvert twice per year.
6.2.7 General Facility Maintenance and Other Field Tasks
Storm Drainage Utility M&O staff perform a number of duties that do not readily fall into the categories
previously listed, and often support other City departments. Examples of these additional storm drainage
tasks include:
• General facility maintenance: Maintenance may include detention vault cleaning and sediment
removal, weir cleaning, filter inspection and cleaning, and maintenance of oil/water separators.
• Engineering support: Storm Drainage Utility M&O staff often provide facility inspection services for
Engineering projects and support Engineering through visual observation in the field. M&O staff also
make small repairs such as replacing catch basins or failed culverts, or minor drainage pipe
replacement. See Section 6.7 for recommendations related to documenting M&O repair projects.
It is difficult to quantify in terms of full-time equivalent (FTE) the general inspection and field tasks
performed by Storm Drainage Utility staff. Many of the activities occur outside of a regular maintenance
schedule. FTE assumptions are summarized in Section 6.6.
Routine Operations Provided to the Storm Drainage Utility 6.3
This section discusses routine operations performed by other City staff or by contracted services in
support of the Storm Drainage Utility. Each sub-section provides a brief description of the M&O activity.
FTE efforts for these activities are funded by the Storm Drainage Utility. Because Vegetation
Maintenance staff primarily support the Storm Drainage Utility (approximately 90 percent of total staff
effort), these staff are included in the existing staffing requirements discussed in Section 6.6.
6.3.1 Vegetation Maintenance
Vegetation maintenance is performed by Vegetation Maintenance Division full-time and seasonal staff
that support City Storm Drainage Utility M&O staff. Vegetation maintenance includes mowing, herbicide
application, seeding and re-planting, and removal of nuisance vegetation or vegetation that impairs the
function of storm drainage facilities. In the fall, vegetation maintenance also includes removal of leaves
that can accumulate and block flow to catch basins.
Full-time Storm Drainage Utility staff may also perform limited vegetation maintenance as part of the
routine operations discussed in Section 6.2.
6.3.2 Stormwater Pump Station Maintenance
Maintenance of the seven pump stations within the City storm drainage system is performed by Sewer
Utility staff since they have pump specialists whom perform all pump station maintenance. Sewer Utility
staff perform scheduled weekly and monthly maintenance inspections as described in the City of Auburn
Sewer Comprehensive Plan Update and summarized below:
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Weekly pump station maintenance activities include the following tasks:
• Perform a general visual inspection of grounds and pump station structure or vault
• Check equipment for abnormal vibrations
• Check lubrication of all pumping equipment
• Check and clean, as needed, seal filters
• Check ultrasonic level sensor
• Check pump run times
• Bleed lines of moisture
• Inspect control valves
• Check wet well for debris
• Manually run pump and observe wet well level
Monthly pump station maintenance activities include the following tasks:
• Inspect and test engine-generators
• Inspect pump station mechanical bypass pumping
• Flush sump pit and manually run sump pump
• Clean pump station interior and, at a minimum, wipe down control panels and pumps, and wash
down/disinfect floor
• Inspect fall restraint system
• Spot-check control system and telemetry alarms
6.3.3 Stormwater Pond Maintenance by King County
The City has contracted with King County to provide stormwater pond maintenance of two to five larger
stormwater ponds per year because the County can more efficiently provide this service using County-
owned equipment and property for disposal of sediment materials. The City seeks to phase out the use
of County resources by adding personnel and procuring additional equipment. Maintenance activities
and frequency of maintenance as discussed in Section 6.2.5 applies to those facilities maintained by
King County.
6.3.4 Stormfilter Maintenance
Stormfilters are designed to remove sediment, metals, and other stormwater pollutants from wet
weather runoff via filter cartridges. The City currently has eleven stormfilter cartridge facility locations.
The stormfilter vaults are inspected by city staff quarterly to identify conditions that require additional,
unscheduled maintenance. Such conditions could include excess sediment accumulation, damaged
piping, or vault and access cover damage. The stormfilters and vaults are maintained (cartridges
replaced) annually by a private contractor.
Non-Routine and Emergency Operations 6.4
The intent of the routine inspection and maintenance activities discussed in Sections 6.2 and 6.3 is to
minimize, through proactive management of the stormwater facilities, the potential for conditions that
could lead to emergencies. This section discusses unscheduled activities performed by Storm Drainage
Utility M&O staff, and describes a response plan for emergency conditions.
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6.4.1 Customer Service Requests
Customer service requests, typically related to a local drainage complaint, trigger creation of a work
order to inspect the affected area or stormwater facility and identify potential solutions. In some cases,
relatively simple solutions, such as removal of blockages, can alleviate the issue. However, other cases
require coordination with Engineering or other City departments. On average, City Storm Drainage Utility
staff respond to approximately three customer service/complaint-related work orders per week. The
effort required to resolve these complaints varies considerably.
Good record-keeping can help in complaint resolution by ensuring that all relevant data are gathered and
by serving as a reminder to resolve the complaint and notify the complainant. When a complaint is
received, the following information should be recorded to the extent possible:
• Name and contact information of the person making the complaint
• Brief description of the nature of the complaint
• Time and date the complaint was received
• Storm drainage staff assigned to respond
Following initial response, the complaint record should be updated to include the results of inspections
and corrective actions taken, if any. If the complaint cannot be resolved internally within the Storm
Drainage Utility, the complaint record should be forwarded to Engineering for further investigation.
Notification of any system investigation and/or action should be provided to the customer making the
complaint.
6.4.2 Emergency Response Program
The Storm Drainage Utility, in conjunction with the other utilities divisions, has prepared a Public Works
Emergency Response Manual as a guide on how to handle emergency situations. While the manual is by
no means all-inclusive for every type of disaster, it is a valuable tool for dealing with many of the
emergency situations that municipalities face. Copies of the Emergency Response Manual are available
at the M&O Building, at City Hall Annex with the City Engineer, and with the Valley Regional Fire Authority
(VRFA) Station.
The Emergency Response Manual is one element of the City’s overall Emergency Operations Plan. The
primary objectives of the Emergency Operations Plan are to ensure public safety, restore essential
services as quickly as possible, and provide assistance to other areas as required. There is also a master
response program for the entire City as documented in the City’s Emergency Management Plan (CEMP).
The material in the CEMP provides guidance for mitigation, preparedness, responsibilities, recovery
operations, training, and community education activities. Copies of the Emergency Operations Plan are
located in each City department, the M&O Building, and with the VRFA.
The utility has implemented a standby program whereby one on-call employee is designated to be the
first to receive after-hours emergency calls. Most storm drainage system problems that occur outside of
normal working hours are reported through the City’s 911 emergency response system or a non-
emergency response number. An emergency call-out list is provided to the emergency operator in order
to contact utility staff in case of an emergency. The primary responder to those after-hours calls is the
on-call employee. Storm Drainage Utility M&O staff have been trained to respond to system
emergencies. The contacted staff assesses the situation, contacts additional staff as necessary, and
then responds in accordance with established emergency response procedures.
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Data Collection and Record-Keeping 6.5
Data collection and record-keeping functions for the Storm Drainage Utility are performed using
Cartegraph, a Web-based commercial software package provided by Cartegraph Inc. Cartegraph
integrates GIS data with utility M&O records, providing managers with overview information about system
and operational performance and field crews with information related to the condition and failure history
of specific stormwater facilities. The City currently uses Cartegraph to plan field staff activities (work
orders), record results of both routine and non-routine maintenance, and compare actual maintenance
efforts to City goals. The City recently upgraded its Cartegraph system and plans to transition toward the
use of Cartegraph as an asset management tool, through which the City would optimize staffing and
capital resource planning.
In recent years, the City has made considerable progress in adding asset information to Cartegraph,
specifically GIS data, physical information related to size and material, and installation date. However, to
fully utilize the asset management function of Cartegraph, additional information related to risk, asset
criticality, and condition is also necessary. To assist the City’s transition to an asset management
program, the attributes listed below should be used within Cartegraph to define each of the City
stormwater assets (catch basin, pipe segment, stormwater pond, etc.).
Asset-Specific Attributes. The following asset-specific attributes are related to the asset and remain
relatively unchanged over time:
• Asset ID: The unique asset number that is used by all business systems to identify an asset.
• Location: Where the asset is located (GIS).
• In-service date: The date the asset was placed into service.
• Replacement cost: The cost to replace the asset and the year that the cost data were calculated.
• Useful life: The average life expectancy of the asset.
• Asset criticality: A value assigned to each asset that indicates how essential it is to maintaining a
defined LOS. Typically it is defined as a combined score based on the consequence of failure and
the likelihood of failure.
− Consequence of failure: The social and economic cost if the asset fails
− Likelihood of failure (condition): The estimated time until the asset fails, usually based on
condition
• Asset class: A group of assets that share the same characteristics (e.g., ponds, pipe segments).
Asset class is used to estimate replacement costs and useful life of groups of assets.
• Nameplate information and asset specifications: Important information that is used to uniquely
describe an asset such as the manufacturer name, type of asset, serial number, size, material, etc.
This information is used for asset identification, replacement, and repair.
Maintenance and Operation Attributes. The following M&O attributes are captured as part of the
operations, maintenance, and repair history associated with each asset:
• Asset ID: The unique asset number that is used by all business systems to identify an asset. Work
orders should be associated with one or more assets.
• Issue, cause, action: These codes are used to classify historical M&O activities associated with
corrective actions or unplanned maintenance.
− Issue: What is the problem observed in the field?
− Cause: What is the underlying cause of the problem?
− Action: What was done to address the cause?
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• Target hours and actual hours: Recording the estimated hours and actual hours to complete a work
order can help in determining efficiency, planning workloads, and assessing repair costs.
• Target start/stop date and actual dates: Recording the estimated and actual start and stop dates for
a work order can help in determining efficiency, planning workloads, and assessing repair costs.
• Work order costs: Work order costs include labor, parts, materials, and equipment, and should be
accurately recorded for each work order.
• Work order type: Work order types are used to group and compare different types of work activities.
Typical work order types include:
− Capital improvement: Work associated with a capital improvement project
− Corrective maintenance: Work associated with an unplanned repair
− Preventive maintenance: Work associated with a planned preventive maintenance activity
− Predictive maintenance: Work associated with predictive measures (usually for critical assets)
• Warranty information: Helps to determine assets that are under warranty and the warranty
maintenance requirements.
M&O Staffing Requirements 6.6
This section outlines existing and future staffing requirements for M&O staff.
6.6.1 Existing Staffing Requirements
Existing staffing requirements for M&O activities discussed in this chapter were compiled and evaluated
to determine the M&O staffing level needed to efficiently operate, maintain, repair, and collect and
report the information necessary to properly operate the storm drainage system. Table 6-2 and Table 6-3
evaluate Storm Drainage Utility and Vegetation Maintenance Division staff, respectively. Each table
evaluates the estimated time to conduct storm drainage system M&O tasks in the manner currently
performed. Calculated days for each M&O activity are for a single person performed over an 8-hour
“day.” Therefore, an activity that is performed quarterly and that requires 4 hours and two M&O staff to
complete would result in an annual requirement of 4 days.
Table 6-2. Existing Storm Drainage System Maintenance and Staffing Requirements
Work activity FTE days
required annually Assumptions/City goal
Catch basin and manhole inspection, cleaning, and repair
Catch basin inspection 148 Inspect once every 2 years, total of 8,880 catch basins. Perform 60
inspections per day with one-person crew.
Manhole inspection 13 Inspect once every 4 years, total of 2,330 manholes. Perform 45
inspections per day with one-person crew.
Catch basin cleaning 222 One cleaning is required for every five inspections. Two-person crew, 1
hour each.
Manhole cleaning 29 One cleaning is required for every five inspections. Two-person crew, 1
hour each.
Catch basin/manhole repair 63 250 repairs (25 percent of all inspected) per year. Two-person crew, 1
hour each.
Stormwater pipeline cleaning and CCTV
Pipeline cleaning 99 City goal is 74,000 ft per year (entire system in 15 years). Two-person
crew can clean 1,500 ft of pipe per day.
CCTV 220 City goal is 55,000 ft per year (entire system in 20 years). Two-person
crew can CCTV 500 ft of pipe per day.
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Table 6-2. Existing Storm Drainage System Maintenance and Staffing Requirements
Work activity FTE days
required annually Assumptions/City goal
Stormwater outfall inspection, cleaning, and maintenance
Inspection 49 City goal is four times per year (65 total outfalls). Two-person crew,
0.75 hour each.
Maintenance 16 City goal is one time per year (65 total outfalls). Two-person crew, 1
hour each.
Drainage ditch, stormwater pond, and swale inspection, maintenance, and restoration
Drainage ditch maintenance and
restoration
90 Six-person crew for 15 days (approximately 3 days per week for a
month in the summer).
Stormwater pond and swale inspection 91 City goal is twice per year for each of 243 ponds/swales. Two-person
crew, 0.75 hour each.
Stormwater pond and swale maintenance
and restoration
270 Six-person crew for 45 days (approximately 3 days per week for 3
months in the summer).
Culvert inspection and cleaning
Culvert inspection and cleaning 300 City goal of twice per year for each of 800 culverts. Two-person crew,
0.75 hour each.
Other stormwater M&O activities
General facility maintenance and other
field tasks
26 One day per week. Two-person crew, 2 hours each.
Customer service requests/complaints 39 Three requests per week.a Two-person crew, 1 hour each.
Data entry 130 20 hours per week total (8 people at 0.5 hour per day).
Subtotal 1,804
Total 1,985 Assumes 10% unquantified work
Total number of working days available
per FTE
221 365 minus weekends (104), holidays (12), vacation (15), sick (12),
and training (1).
Number of FTEs required 9.0 1,985 days required divided by 221 days per FTE year.
Current funded FTEs 8.7 8 FTE and 2 seasonal staff
Note: FTE days are defined as 8 hours.
a. Many customer service requests are related to maintenance needs for privately owned drainage systems.
Table 6-3. Existing Vegetation Maintenance and Staffing Requirements
Work activity FTE days
required annually Assumptions/City goal
Pond Vegetation Management
Mowing 744 6-person crew, 40 hours per week for 6 months
Weeding/Spraying 248 4-person crew, 20 hours per week for 6 months
Weed Control/Herbicide Spraying
Weed Control/Herbicide Spraying 37.2 2-person crew, 3 days per week (4.8 hrs per day) for 6 months
ROW and Ditch Mowing
Staff 1 115.5 40 hours per week for 8 months
Staff 2 46.2 2 days per week for 8 months
Tree Trimming and Removal
Tree Trimming and Removal 248 4-person crew, 40 hours per week for 3 months
Leaf Removal
Leaf Removal 186 3-person crew, 40 hours per week for 3 months
Subtotal 1,625
Total 1,706 Assumes 5% unquantified work
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Table 6-3. Existing Vegetation Maintenance and Staffing Requirements
Work activity FTE days
required annually Assumptions/City goal
Total number of working days available
per FTE
221 365 minus weekends (104), holidays (12), vacation (15), sick (12), and
training (1).
Number of FTEs required 7.7 1,706 days required divided by 221 days per FTE year.
Current funded FTEs 6.5 6 FTE and 3 seasonal staff x 90% availability for Storm Drainage Utility M&O
Note: FTE days are defined as 8 hours.
Table 6-2 shows that the Storm Drainage Utility, including two seasonal staff, is slightly under- staffed
with respect to meeting current City proactive goals for M&O activities, with the exception of drainage
ditch maintenance and restoration. Based upon discussions with City staff, they are unable to meet the
goal of performing ditch maintenance of all ditches within the system on a 20-year cycle with the
available M&O staff. In addition, the City would like to maintain all their stormwater ponds and no longer
rely on King County’s assistance with the larger ponds. Additional staffing needs required to more
consistently meet the current LOS goals, additional pond maintenance responsibilities, future regulatory
requirements, and anticipated system growth are discussed in Section 6.6.2. Table 6-3 shows that 1.2
additional FTE is required to meet current vegetation maintenance needs of the Storm Drainage Utility.
6.6.2 Future Staffing Requirements and Equipment Needs
The M&O activities discussed in Section 6.2 and summarized in Table 6-2 are current efforts and do not
include additional activities that will be required as part of the revised NPDES Phase II Municipal
Stormwater Permit. Furthermore, additional staffing is required to more consistently meet LOS goals with
respect to stormwater pond and drainage ditch maintenance. Future staffing requirements are
summarized in the sections below and Table 6-4.
6.6.2.1 Drainage Ditch and Stormwater Pond Maintenance and Restoration
The City intends to increase overall Storm Drainage Utility staffing in order to dedicate more staff to
drainage ditch maintenance and restoration during the summer months (see Table 6-4). In order to meet
the City’s goal to maintain all ditches within the system on a 20-year cycle, existing ditch maintenance
frequency will be increased by approximately 36 days (with a six-person crew), or 1 FTE per year.
As identified in Section 6.3.3, the City desires to phase out current King County maintenance of City
storm ponds. It is estimated that existing pond maintenance frequency will be increased by
approximately 55 days (with a six-person crew), or 1.5 FTE per year, to replace current King County
maintenance activities. A new excavator will also be necessary and is estimated to cost $180,000.
6.6.2.2 Other Stormwater M&O Activities
The City intends to hire one full-time staff member for Cartegraph maintenance tracking and reporting
functions. This staff member would support the City Storm Drainage, Sewer, and Water utilities and
would be a liaison with the City Information Services (IS) division.
Many of the new requirements of the NPDES Permit emphasize implementation of LID practices, such as
minimizing impervious surfaces, native vegetation loss, and stormwater runoff. A majority of new
development and redevelopment projects will be required to construct new types of onsite LID facilities,
which will need to be inspected and maintained to ensure proper function moving forward.
An estimate of FTE effort for LID facility inspection and maintenance based upon review of the new
NPDES Permit requirements was prepared separately from the Storm Drainage Utility planning process.
Through that effort it was estimated that 0.5 FTE of Storm Drainage Utility M&O staff will be required for
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LID inspection and maintenance activities. Additional inspectors from Engineering would also be
dedicated to LID facilities and other requirements of the NPDES Permit.
6.6.2.3 Stormwater Pond Vegetation Maintenance
As new stormwater ponds are constructed, vegetation maintenance including mowing and weeding will
be necessary. Not all facilities can be maintained with equipment and some require additional
maintenance time because work has to be completed by hand. The additional effort required each year
is driven by the number of ponds constructed. As this is a small incremental increase that would not
impact the staffing requirements for this planning period, it is not shown in Table 6-4.Increases in efforts
for pond vegetation maintenance, however, should be considered in future planning efforts. For existing
pond maintenance, an excavator mower attachment is needed for vegetation maintenance and is
estimated to cost $30,000.
Table 6-4. Future Storm Drainage System Maintenance and Staffing Requirements
Work activity FTE days
required annually Assumptions/City goal
Drainage ditch and stormwater pond maintenance and restoration
Drainage ditch maintenance and restoration 216 Six-person crew for 36 days during the summer months.
Stormwater pond restoration 330 Six-person crew for 55 days during the summer months.
Other stormwater M&O activities
Cartegraph tracking and reporting 111 Approximately 0.5 FTE (1 FTE shared with Sewer and Water utilities).
LID inspection and maintenance 104 One day per week. Two-person crew.
Total 761
Total number of working days available
per FTE 221 365 minus weekends (104), holidays (12), vacation (15), sick (12), and
training (1).
Number of FTEs required 3.4 761 days required divided by 221 days per FTE year.
6.6.2.4 Equipment Needs
New and updated Storm Drainage Utility and Vegetation Maintenance equipment needs identified via
consultation with City staff include CCTV inspection equipment for pipe inspection, an excavator for
drainage ditch and stormwater pond maintenance and restoration, and an excavator mower attachment
for pond vegetation maintenance. The Storm Drainage Utility utilizes the Sewer Utility’s reallocated CCTV
inspection equipment and truck. New equipment would allow for increased efficiency and inspection
frequency. CCTV inspection is essential component of the M&O program as it can identify trouble spots
before larger failures occur and can provide planning information based on the condition of the storm
drainage system. A new excavator is needed to meet the City’s goal for ditch maintenance and the City’s
plan to maintain all City ponds. A new excavator mower attachment is needed to maintain vegetation in
storm drainage facilities.
New equipment would increase M&O and Vegetation Maintenance field staff efficiency and may reduce
the need for additional staff. Estimated costs, based on recent vendor quotes, for the equipment are
summarized below.
• CCTV inspection equipment: $250,000
• Excavator: $180,000
• Excavator mower attachment: $30,000
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Potential Improvement Opportunities and Capital Needs 6.7
The Storm Drainage Utility has a positive track record for M&O, as evidenced by the limited need for non-
routine maintenance and few customer service complaints about the city’s drainage system. Routine
facility cleaning, regular inspections, experienced staff, and a well-planned storm drainage system
contribute to that success. However, as shown in Table 6-3, 1.2 FTE within the Vegetation Maintenance
Division are necessary to adequately support storm drainage utility functions. Furthermore, the need to
comply with the new NPDES Permit and the growing backlog for drainage ditch and stormwater
pond/swale maintenance should be addressed by the City by adding to the current Storm Drainage
Utility M&O staff. An additional 3.4 FTE (Table 6-4) are required to achieve current City proactive M&O
goals plus future NPDES permit LID requirements.
Based upon discussions with City staff and analysis of M&O activities discussed in this chapter, the
following improvement opportunities are available to the Storm Drainage Utility. These opportunities are
based on improving existing services, regulatory compliance, and improving work productivity:
• Obtain or upgrade the following utility equipment to improve M&O and Vegetation Maintenance
efficiency:
− CCTV inspection equipment for pipe inspection
− Excavator for drainage ditch and stormwater pond maintenance and restoration
− Excavator mower attachment for pond vegetation maintenance
• Continue to integrate asset management with existing utility management software (Cartegraph and
GIS).
− Continue to add GIS attributes to known Storm Drainage Utility assets.
− Perform and document condition assessments. Use defined criteria (such as leaks/cracks
observed, cleanliness, and other specific measures) and provide staff training to ensure
assessment consistency. Use National Association of Sewer Service Companies (NASSCO)
Pipeline Assessment and Certification Program (PACP) certified inspection programs to allow
integration of inspection results with Cartegraph.
− Over time, use results of condition assessments to move toward risk-based maintenance to best
utilize staff resources. For example, consistently high assessment scores would result in a lower
risk or need for maintenance, allowing M&O staff to be diverted to more essential activities.
− Over time, demonstrate (through maintenance records) that a subset of city catch basins do not
require inspection, cleaning, and maintenance every 2 years per the new NPDES Permit.
• All M&O repair projects (see Section 6.2.7) should be constructed to established City engineering
standards. It is recommended that the City develop a more formal procedure for tracking M&O repair
projects to ensure that as-built and GIS records are updated when repairs are completed.
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Chapter 7
Capital Improvements
This chapter describes recommended capital improvement projects for the City of Auburn Storm
Drainage Utility. Capital improvement projects described in this chapter are compiled into a 6-year CIP
that addresses the most crucial drainage problems and a 20-year CIP that addresses longer-term capital
planning goals (see Chapter 8). This comprehensive plan contains time frames that are the intended
framework for future funding decisions and within which future actions and decisions are intended to
occur. However, these time frames are estimates, and depending on factors involved in the processing
of applications and project work, and availability of funding, the timing may change. The framework does
not represent actual commitments by the City of Auburn, which may depend on available funding
resources.
In general, capital improvement projects are modifications to stormwater drainage infrastructure
designed to improve the condition and function of the drainage system so that it can meet the LOS goals
established for the City’s Storm Drainage Utility (see Chapter 3). Example goals include limiting flooding
across roadway segments to an average of once per 25 years and limiting the number of pipes that have
exceeded their economic lives (prior to repair or replacement). All projects were developed and sized to
be consistent with these LOS goals.
The capital improvement projects presented in this chapter were identified and developed through
focused investigations and by working collaboratively with City staff. This focused and collaborative
approach was based on the practical consideration that the City can implement only two to four capital
improvement projects per year given existing revenue streams and staff availability. The intent is to
produce an economical CIP that addresses the most salient issues in the near term, while still planning
for the long-term ability of the Storm Drainage Utility to meet LOS goals. The following basic steps are
used to develop capital improvement projects:
• The project team worked closely with City staff to identify and characterize existing problems based
on direct staff observations from recent storm events. Such observations are a valuable supplement
to modeling analyses and, in this case, were used in conjunction with modeling activities to assist
with model development.
• Modeling was completed for the historical event that most closely produced a once per 25 year flow
rate (the specific event varied by basin). Results from historical events were used to assess the
extent and severity of the drainage problem. Results from the design event were used to size
infrastructure improvements to mitigate drainage problems.
• Hydraulic modeling was completed using PCSWMM, a software package that uses GIS technology to
import and export data, allowing a seamless transition between the system inventories and
modeling input files. For smaller basins for which a PCSWMM model did not exist or was not created,
Manning’s n equations were used to determine pipe sizing.
• Recommendations were developed for flow and water level monitoring in the vicinity for some of the
proposed projects or other locations where future modeling may be warranted.
• Members of the City’s staff have a thorough understanding of the storm drainage system and
firsthand experience with existing drainage problems. The project team worked with City staff to
identify the most viable mitigation alternative.
• Once the projects were defined, the project team developed concept-level cost estimates.
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An overview of project locations is shown in Figure 7-1. Section 7.1 describes a tiered method for
establishing project priorities. Section 7.2 presents detailed descriptions of new proposed projects.
Section 7.3 describes programmatic drainage projects. Section 7.4 examines the need for repair and
replacement of existing pipes.
Project Prioritization 7.1
Storm Drainage Utility staff prioritized capital improvement projects by grouping them into one of three
tiers. Projects in the top tier, or highest priority, are classified as tier 1; projects with medium priority are
classified as tier 2; and projects with lowest priority relative to the other projects are considered tier 3.
Prioritization was based on a qualitative evaluation of the following issues:
• The magnitude of the LOS gap that would be addressed by a CIP project. For example, a project that
rectifies an annual flooding problem would rank higher than a project in a different area that
eliminates less frequent flooding.
• The reduction in risk and reduction in consequences associated with a CIP project. For example, the
consequence of flooding that occurs near critical facilities (e.g., hospital or fire station) or along
major arterial streets may be larger than flooding along residential streets. A CIP project that
addresses a larger consequence would rank higher.
• The opportunity for coordination with ongoing City of Auburn street improvements, or other utility or
transportation projects. Coordinated projects that reduce the overall cost of a CIP project would rank
higher.
• The capital funding capacity of the Storm Drainage Utility. The overall list of project priorities
attempts to balance the need for action with the funding and implementation capacity of the Storm
Drainage Utility.
• Other considerations included the potential to improve water quality, reductions in maintenance,
and increased reliability of the system.
Priorities for each project are included in each project description in the following sections. Project
priority and budgetary constraints were considered together in developing the year-by-year schedules for
project implementation in the 6- and 20-year CIPs (see Chapter 8).
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LEGEND
!(Project Location
Roadway
Watercourse
Water Body
Wetland
Auburn City Boundary
¯0 5,000 10,0002,500
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
October 2015 Figure 7-1Project LocationsStormwater Drainage UtilityCapital Improvements Program
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ID Project Name 1 West Main Street Pump Station Upgrade 2 37th and I Streets NW Storm Improvements 3 Hillside Drainage Assessment (*see Figure 7-4 for project locations) 4A 30th Street NE Are Flooding, Phase 2 4B 30th Street NE Are Flooding, Phase 3 5A West Hills Drainage Improvements near S 330th St. and 46th Pl. S 5B West Hills Drainage Improvements at S 314th St. and 54th Ave. S 6 North Airport Area Improvements 7 D St. SE Storm Improvements 8 23rd St. SE Drainage Improvements 9 Comprehensive Storm Drainage Plan update* 10 Vegetative Waste Sorting Facility (location to be determined)* 11 Storm Drainage Infrastructure Repair & Replacement* 12 Street Utility Improvements* *Project not mapped; multiple locations or location to be determined
Chapter 7 Comprehensive Storm Drainage Plan
7-4
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Proposed Drainage Projects 7.2
Capital improvement projects described in this section were developed as part of this Drainage Plan and
are described in sufficient detail to allow the City to proceed with budgeting and design. Project
descriptions are organized into summaries containing the following information:
• Project number: CIP numbers were generally assigned by priority.
• Project name: A short, descriptive name was assigned to each project.
• Location: A simple description of the project location, such as the cross streets, is provided.
• Priority and schedule: Project priorities and years of implementation are provided to present
complete project summaries; however, prioritization and scheduling is discussed in more detail in
Chapter 8.
• Problem summary: A brief description of the observed problem is presented along with a summary of
the analysis conducted to characterize the problem and evaluate alternatives for mitigation. A more
complete discussion of the hydraulic analyses performed to evaluate system conveyance capacities
is summarized in Section 5.1 and described in detail in Appendix C.
• Description: A description of the proposed project is provided, including major project elements and
sizes.
• LOS goal(s) addressed: The LOS goal(s) addressed by the project is provided.
• Recommended predesign refinement: In some cases, pre-project data collection and monitoring is
proposed.
• Recommended post-construction monitoring: In some cases, post-project monitoring is proposed.
• Planning-level cost estimate: A list of estimated costs is provided including construction costs,
engineering and administrative costs, taxes, and contingency costs. The estimate was developed
based on the conceptual design, preliminary quantity take-offs, and estimated unit costs. Estimated
unit costs were based on the City of Seattle Unit Cost Report (SPU, 2012), WSDOT Unit Bid Tab for
the Northwest region (2012–2014), King County’s Tabula conveyance system cost estimating
software, vendor quotes, and escalated project costs from recent projects with similar components.
• Project map: A figure showing the conceptual design and location of project elements is provided.
Proposed project summaries and maps are presented on the following pages.
Comprehensive Storm Drainage Plan Chapter 7
7-5
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 1
Project name West Main Street Pump Station Upgrade
Location South of West Main Street east of the SR 167 overpass
Priority 1
Schedule Begin construction 2016
Problem summary
The dead-end portion of Old West Main Street near SR 167 has a history of observed flooding. The City
installed a pump station to dewater the gravity pipe, flowing on the south side of Old West Main Street, in
an effort to protect local businesses from flooding. Since its installation in 2008, the pump station has
eliminated flooding at the observed location. The pump station, however, does not meet the City’s LOS
guidelines regarding pump redundancy, and modeling indicates that the pump station does not have
capacity to convey the 25-year flow rate.
The City’s gravity pipe on the north side of Old West Main Street experiences flooding, at one inlet,
approximately once per year. Portions of this gravity pipe are now inundated because of high water
elevations associated with the water surface elevation in Mill Creek, which is downstream.
The pump station and gravity pipe discharge to a WSDOT ditch along the east side of SR 167. The ditch
flows north to a WSDOT 24-inch-diameter culvert under West Main Street. Approximately 1,150 feet north
of West Main Street, the WSDOT ditch discharges to Mill Creek via a 24-inch-diameter culvert under SR
167.
During a field visit on April 30, 2014, approximately 5 feet of standing water was observed in the WSDOT
system as well as in portions of the City’s gravity system. Sediment and vegetation accumulation in the
WSDOT downstream conveyance (north of West Main Street) prevent the City’s system from draining. Also,
when Mill Creek’s water surface elevation is high, it backflows into the WSDOT ditch and inundates the
adjacent wetland area north of West Main Street. WSDOT has recently completed cleaning of the ditch
segment. The impact of this maintenance work on water elevations in the WSDOT system and in the City’s
gravity system should be evaluated to determine the timing for construction.
Modeling results show that some sections of the gravity portion of the system are capacity-limited (for the
25-year flow rate), primarily along West Main Street near Clay Street.
Description
This project consists of building a new pump station sized to convey the peak 25-year flow rate with
multiple pumps to meet the pump redundancy LOS (Figure 7-2). The new pump station would convey all
flows from the gravity pipe on the north and south sides of Old West Main Street. The pump station wet
well should be low enough to adequately drain the lowest catch basin in the basin.
The force main from the new pump station would be routed to the City ditch on the north side of West Main
Street. The 30-inch-diameter force main will be constructed within or near the alignment of the existing
culvert with trenchless construction technologies (e.g. pipe-bursting). The force main will discharge to a
riprap rock splash pad constructed in the ditch at the current culvert discharge location.
A backflow preventer should be installed on the 24-inch-diameter WSDOT culvert under West Main Street
to prevent backflow from the north side of the overpass to the south. A backflow preventer may need to be
installed at the 12-inch-diameter culvert crossing at West Main Street, near Lund Road SW, to prevent flow
from the north side of West Main Street to the south side. Post-project monitoring should be conducted to
confirm that the pump station discharges are not causing backups in the City’s ditch, warranting a
backflow preventer at this location.
Model calibration was limited to pump station supervisory control and data acquisition (SCADA) data from
October 2013 through April 2014. Although the existing pump station tributary area is approximately 15%
of the total basin area, the observed flow characteristics from the pump station were used to characterize
flow from the entire basin. Because of the limited calibration data, the proposed pump station should
include SCADA/telemetry capabilities to provide additional flow information, and allow for additional
capacity, if necessary.
Key components include:
• Pump station (estimated capacity 25 cubic feet per second [cfs] with multiple pumps) with wet well and
SCADA/telemetry
• Gravity system conveyance to new pump station:
− 150 feet of 12-inch-diameter pipe
− 113 feet of 24-inch-diameter pipe
• 200 feet of 30-inch-diameter force main installed with trenchless construction technologies
• Riprap rock splash pad at existing culvert outfall in ditch
Chapter 7 Comprehensive Storm Drainage Plan
7-6
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 1
• Backflow preventers to prevent stormwater recirculation to WSDOT ditch or the City’s system (if
necessary)
Recommended
predesign
requirement
• Evaluate the impact of the WSDOT maintenance work on water elevations in the WSDOT system and
the City’s gravity system, to determine construction timing and future needs for ditch cleaning.
• Coordinate with WSDOT on installation of the backflow preventer on the WSDOT culvert.
Recommended post-
construction
monitoring
Conduct periodic site inspections during storm events to confirm that the pump station discharges are not
causing backups in the City’s ditch to the 12-inch-diameter culvert crossing West Main Street near Lund
Road SW. If backups do occur, a backflow preventer on the north end of the 12-inch-diameter culvert may
be warranted.
LOS goal(s)
addressed
• Public drainage infrastructure will be designed and maintained so that the annual chance of
occurrence of flooding disruption that inundates the city roadways to an impassable level no more than
once every 25 years. (LOS Goal 4)
• Public drainage infrastructure will be designed and maintained so that the annual chance of
occurrence of flooding (surface water from ROW runoff entering premises and damaging building
structures) will occur no more than once every 50 years. (LOS Goal 5)
• Pump stations will be designed with two or more pumps to ensure proper function during maintenance.
Backup and/or dual-feed power supplies will be installed as needed. (LOS Goal 15)
Cost estimate
Stormwater pump station with SCADA/telemetry: 25 cfs pump station located in Old
West Main Street ......................................................................................................... $750,000
Gravity piping: 150 feet of 12-inch-diameter pipe and 113 feet of 24-inch-diameter
pipe from existing manholes to new pump station .................................................... $85,000
Force main: construct 200 feet of 30-inch-diameter force main below underpass
(from south to north side through existing culvert) using trenchless technology,
abandon 18-inch-diameter culvert, and install riprap rock splash pad at existing
culvert outfall in ditch outfall ......................................................................................
$257,000
Ancillary improvements: decommission existing pump station; install backflow
preventer on WSDOT culvert ....................................................................................... $40,000
Wetland permitting and mitigation (20% of construction subtotal) .......................... $227,000
Subtotal line-item costs ............................................................................................... $1,359,000
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) . $245,000
Construction contingency (30% of all above construction costs) ............................. $481,000
Washington State and King County sales tax (9.5% of all above construction costs) $198,000
Subtotal construction costs ........................................................................................ $2,283,000
Administration, engineering design, and permitting (30% of construction costs) ... $685,000
CIP 1 project cost $2,968,000
Install backflow preventer, if necessary
Install pump station
Install 200 lf 30-inch-diameter force main
within existing culvert alignment using
trechless construction techniques
Decommission existing
pump station
Install 150 lf 12-inch-diameter
drainage pipe
Install riprap rock splash pad
Install 113 lf 24-inch-diameter
drainage pipe
Mi
l
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e
k
Abandon existing gravity pipe
Install backflow preventer
OLD W MAIN ST
wetlands
W MAIN ST
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LEGEND
Pump Station
%,Proposed Facility
Proposed Force Main
Proposed Drainage Pipe
!(Storm Node
Storm Channel
Storm Pipe
Storm Culvert
¯0 400 800200
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-2Project 1: West Main Street Pump Station Upgrade
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Comprehensive Storm Drainage Plan Chapter 7
7-9
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 2
Project name 37th and I Streets NW Storm Improvements
Location Intersection of 37th Street NW and I Street NW; Interurban Trail approximately 300 feet east
Priority 1
Schedule Begin construction 2016
Problem summary
Recurring flooding in the vicinity of 37th Street NW and I Street NW causes several nuisance problems
including slow or impeded traffic on 37th Street NW, driveway damage and/or impeded access to the
nearby power substation, and impeded pedestrian and bicycle access on the Interurban Trail south of 37th
Street NW (east of the substation). Flooding problems occur relatively frequently and can result from large
storm events as well as prolonged wet periods following storm events. Observations and anecdotal
information suggest that floodwaters originate from Mill Creek and/or drainage system backups caused by
high water levels in Mill Creek, particularly at the north side of 29th Street NW. Although high water levels
in Mill Creek at 37th Street could also be a source of flooding and/or reduce the conveyance capacity of
the drainage ditch along 37th Street, it has been observed that there is typically a positive flow gradient
leading from the flooded areas back toward Mill Creek.
There appear to be at least two flow paths between overflows at 29th Street NW and flooding at 37th
Street NW:
1. Backflow along 29th Street NW is diverted into a remnant channel of Mill Creek that flows north
toward the power substation. The remnant channel appears to be blocked by the substation and
does not have a clear path back to the main channel. It appears that, when discharges in the
remnant channel are high, at least a portion of the flow goes northeast and becomes impounded on
the east side of the power substation driveway.
2. Backflow along 29th Street NW can extend as far as the Interurban Trail crossing, causing backflow
through the culverts into the area between the trail embankment and the railroad embankment.
Water can then flow north along the embankments until it ponds on the south side of 37th Street
NW. When the ponding gets high enough, water floods over the Interurban Trail and into the
impounded water on the east side of the power substation driveway. In 2013, a small berm was
constructed between the trail embankment and the railroad embankment to try to prevent water
from flowing north; however, it is not known whether this modification sufficiently addressed the
problem.
The impounded water on the east side of the power substation driveway can lead to flooding when water
surface elevations rise to roughly 51 feet elevation (NAVD88). Specifically, the substation driveway is
overtopped and areas of 37th Street NW are flooded because of backflow through an existing storm drain
catch basin, and perhaps also because of direct flow over the sidewalk and curb.
City maintenance crews completed a small works project in 2012 to try to mitigate the flooding. Two 8-
inch-diameter ductile iron culverts were installed under the power substation driveway near 37th Street
NW at a higher invert elevation than the existing 12-inch-diameter culvert. The intention was to provide
additional conveyance capacity to drain the water that ponds on the east side of the driveway back to Mill
Creek. However, reports from the City suggest that this modification has not been sufficient to eliminate
the flooding problems.
Description
This project will increase the conveyance capacity of the drainage along 37th Street NW by replacing the
existing culverts under the power substation driveway and installing a new culvert under the Interurban
Trail (Figure 7-3). A drainage ditch should be constructed to convey water from the Interurban Trail culvert
to the existing ditch along the south side of 37th Street NW. The trapezoidal ditch should have a bottom
width of 4 feet, 3:1 side slopes, and a depth of 2 feet. In addition, the existing ditch along 37th Street NW
should be cleaned out (remove sediment, vegetation, obstructions, and accumulated debris) to maximize
conveyance capacity and minimize the tail water effects on culvert outlets.
The magnitude and frequency of flows emanating from Mill Creek backflows are difficult to quantify without
a hydraulic study of the Mill Creek main channel, as well as a detailed survey of the drainage flow paths
leading to the flooded areas at 37th Street NW. Therefore, the proposed new culverts were not sized to
pass a specific design discharge. Alternatively, a hydraulic analysis of the ditch and culvert system was
performed to examine the potential for reducing water surface elevations by installing larger culverts.
The project includes two new 3-foot (span) by 2-foot (rise) reinforced concrete box culverts: the first would
be installed under the power substation driveway at an invert elevation of approximately 46.5 feet
(NAVD88), and a second would be installed under the Interurban Trail embedded by approximately 1 foot
because of likely cover limitations. Installation of these culverts would reduce upstream water surface
elevations by roughly 2 feet during high flow conditions that currently result in flooding at approximately 51
Chapter 7 Comprehensive Storm Drainage Plan
7-10
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 2
feet NAVD88.
The proposed culverts are the smallest standard box culvert. If additional data are collected (see predesign
recommended predesign refinements), culvert sizes could be refined, and a larger size could be installed if
warranted.
Recommended
predesign
refinements
• Perform additional site reconnaissance and survey, including a stream walk during high flow conditions
(to estimate high water elevations) and confirm flow paths assumptions
• Conduct a detailed topographic survey of the drainage system including the ditch, road and trail
crossings, and nearby flooded areas; in addition, conduct a ground survey of key structures such as
culvert invert elevations and dimensions
• Conduct a revised hydraulic analysis of the drainage system using new survey data, high water mark
estimates, and confirmed flow paths; refine culvert sizing given needed conveyance capacity, spatial
constraints, and project costs
LOS goal(s)
addressed
Public drainage infrastructure will be designed and maintained so that the annual chance of occurrence of
flooding disruption that inundates the city roadways to an impassable level no more than once every
25 years. (LOS Goal 4)
Cost estimate
Interurban Trail culvert: construct 60 feet of 3-by-2-foot precast concrete box culvert including
inlet and outlet headwalls and riprap rock splash pad at outlet…. ........................................... $40,000
Power substation driveway culvert: construct 60 feet of 3-by-2-foot precast concrete box
culvert including inlet and outlet headwalls and riprap rock splash pad at outlet, and drainage
bypass .........................................................................................................................................
$50,000
Ancillary improvements: construct 50-foot-long ditch to connect Interurban Trail culvert to
roadside ditch; clean 1,000-foot-long existing ditches along south side of 37th Street NW .. $33,000
Wetland permitting and mitigation ............................................................................................. $22,000
Subtotal line-item costs ............................................................................................................... $145,000
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) ................. $26,000
Construction contingency (20% of all above construction costs) ............................................. $34,000
Washington State and King County sales tax (9.5% of all above construction costs) ............. $19,000
Subtotal construction costs ........................................................................................................ $224,000
Administration, engineering design, and permitting (30% of construction costs) ................... $67,000
CIP 2 project cost $291,000
INTERURBAN
TRAIL
POWER
SUBSTATION
M
i
l
l
C
reek
High water levels cause
backflow into the drainage
system, including diverted
flow into the remnant
Mill Creek channel
Water continues
to flow north along
remnant channel
Remnant channel
terminates but does
not have clear path
back to main channel;
some water appears to
flow to the east side of
the power substation
Backflow from Mill
Creek could result
in surcharging at
inlet to Interurban
Trail culverts; berm
constructed in 2013
to prevent water
from flowing north
Flooding over
Interurban Trail
Flooding of 37th
Street NWFlooding over
driveway
Remove Remove sediment, debris, & vegetation
from 1,000 lf of drainage ditch
SR
1
6
7
37TH ST NW
29TH ST NW
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¯
COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-3Project 2: 37th and I Streets NWStorm Improvements
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Replace existing culvert with
30-inch x 24-inch reinforced
concrete box culvert
37TH ST NW INSET A
LEGEND
!(Storm Node
Storm Pipe
Storm Channel
Storm Culvert
Proposed Culvert
Proposed Ditch
0 400 800200
Feet
1 inch = 400 feet
!(
Install new 30-inch x 24-inch
concrete box culvert
Construct new drainage
ditch and connect to
existing roadway ditch
INSET B
BA
Comprehensive Storm Drainage Plan Chapter 7
7-13
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 3 (Phases 1 and 2 described jointly)
Project name Hillside Drainage Assessment
Location Hillsides throughout the city
Priority 1
Schedule Begin assessment 2016 (Phase 1) and 2017 (Phase 2)
Problem summary
The existing drainage system includes pipes that discharge over hillsides. While a preliminary inventory
and mapping of locations has been completed, field-locating and detailed inspection is warranted to
define deficiencies.
Description
This project would entail compiling and reviewing existing documentation (GIS, record drawings,
Cartegraph) on piped stormwater discharges to hillsides throughout the city (Figure 7-4).
Some pipes may be located on private property or may be accessed only through private property. The
project would include reviewing property legal descriptions to determine where easements may be
lacking and working with property owners to obtain temporary access for the CIP work.
Field visits would be conducted for all identified pipes. Field crews would locate, perform a detailed
inspection, and define outfall deficiencies (e.g., poor access, damaged pipe, insufficient slope protection
at the outfall, structural support of pipe). Special equipment (e.g., pipe video cameras) may be necessary
based on site conditions (e.g., heavy vegetation, steep slope).
Last, the field visit and the necessary actions would be documented. Necessary actions could include:
• Obtaining permanent easements for ongoing inspection and maintenance
• Constructing an access road or trail
• Pipe replacement or repair
• Repair or replacement of slope protection
• Engineering services for pipe or slope protection replacement
This project would be completed in a phased approach. Phase I would consist of completing the
assessment for all non-high-density polyethylene (HDPE) pipes, as there is less information about these
pipes and they tend to be older. Phase 2 would consist of completing the assessment for all HDPE pipes.
HPDE pipes tend to be newer, have more information, and are easier to locate as many are aboveground
installations. The cost estimate includes a placeholder for implementing drainage assessment
recommendations. Actual implementation costs will be estimated after the assessment is complete.
LOS goal(s)
addressed
Public drainage infrastructure will be constructed, operated, and maintained so that there is no resulting
erosion or landslides. (LOS Goal 6)
Recommended
predesign
refinements
This project is for an assessment that will help define the predesign requirements.
Cost estimate
Collect and review available documentation on pipes (28 locations) ..................................... $10,000
Coordinate access with private landowners (18 locations) ...................................................... $4,000
Conduct field visit and assess the pipe(s) and outfall, Phase 1: Non-HDPE Pipes
Medium vegetation on a medium slope (12 locations) ..................................................... $21,000
Medium to dense vegetation on a steep slope (2 locations) ............................................. $5,000
Conduct field visit and assess the pipe(s) and outfall, Phase 2: HPDE Pipes
Medium to dense vegetation on a mild slope (4 locations) ............................................... $7,000
Medium to dense vegetation on a medium slope (8 locations) ........................................ $14,000
Medium vegetation on a steep slope (2 locations) ............................................................ $6,000
Document results of assessment .............................................................................................. $14,000
Implement drainage assessment recommendations $88,000
Subtotal line-item costs .............................................................................................................. $169,000
Construction contingency (20% of all above construction costs)............................................. $34,000
Washington State and King County sales tax (9.5% of all above construction costs) ............ $19,000
Subtotal construction costs ....................................................................................................... $222,000
Chapter 7 Comprehensive Storm Drainage Plan
7-14
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 3 (Phases 1 and 2 described jointly)
Administration, engineering design, and permitting (30% of construction costs) .................. $67,000
CIP 3 project cost $289,000
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LakeTapps
Whi
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GreenRiver
Academy
Johansen
Mill Pond
River Rim
West Beverly
Cobble Creek
Olsen Canyon
Forest Ridge
Pacific Ridge
Vista Heights
Kendall Ridge
Leah Hill Road
Jovita Heights Auburn Way S #1
Amberview Apts.
Auburn Way S #2
Scenic Drive #1
East View Vista
High Crest Drive
Rainier Ridge #1
Rainier Ridge #2
Lakeland Hills #2
Scenic Drive #2-5
Lakeland Hills #1
East Hill Estates
Hidden Valley Vista
Lake Tapps Parkway East #1
Lake Tapps Parkway East #2
LEGEND
Auburn City Boundary
!HDPE Pipe
!Other Pipe
¯0 5,000 10,0002,500
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-4Project 3: Hillside Drainage Assessment
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Comprehensive Storm Drainage Plan Chapter 7
7-17
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 4A and 4B (described jointly)
Project name 30th Street NE Area Flooding, Phases 2 and 3
Location East of I Street NE between 32nd Street NE and 35th Street NE, and at C Street NE between 30th Street NE
and 37th Street NE
Priority 2 (4A) and 3 (4B)
Schedule Phase construction with Project 4A (Phase 2) in 2017 and Project 4B (Phase 3) in 2019
Problem
summary
The north-central area of Auburn has a history of surface flooding with street flooding occurring once every few
years.
The residential development east of I Street NE between 32nd Street NE and 35th Street NE discharges flows
into a City-owned infiltration area. The infiltration area commonly experiences prolonged periods of standing
water due to high groundwater from extended high flows in the Green River, which is adjacent to the infiltration
area. The drainage system on I Street NE currently lacks infrastructure to collect and convey stormwater away
from the infiltration area, as well as residential roadways and parking area. Ponding occurs within the parking
areas of the developments and presents a nuisance and potential hazard to local residents.
The December 3, 2007, storm (approximately a 50-year storm) produced extensive flooding along C Street NE
northward toward 37th Street NE, which required sandbagging to protect local businesses. Deposition of
sediment within Mill Creek has raised the water levels within the creek and diminished the capacity of the
gravity system in C Street NE and downstream in 37th Street NE. In addition to the influence of Mill Creek,
modeling efforts demonstrate that the system’s capacity is limited by low pipe gradient and shallow inverts
and that flooding would continue even with sediment removal within Mill Creek.
Although the two problems are not hydraulically connected, the proposed projects are described jointly as they
will connect the problem areas to the 30th Street NE system.
Description
These projects are Phases 2 and 3 of a three-phased capital improvement project (Relieve 30th Street NE
Area Flooding) from the 2009 Comprehensive Stormwater Drainage Plan. The goal of the 2011 capital
improvement project was to increase the capacity of the 30th Street NE system to reduce flooding along 30th
Street NE and to provide capacity to connect other flooding drainage systems (C Street NE and I Street NE).
The implementation of this capital improvement project is occurring in phases, as funding, staff availability,
and priorities allow. The first phase (30th Street NE Area Flooding, Phase 1) is scheduled for construction in
2015/2016. The subsequent phases, referred to as Projects 4A and 4B in this Drainage Plan, are scheduled
for construction in 2017 and 2019, respectively.
Project 4A would address the flooding adjacent to I Street NE (Figure 7-5). This project would locate a storm
drain line to capture stormwater from the two residential developments currently discharging stormwater to
the City’s infiltration area. In addition, this project would construct a new storm drain within I Street NE
southward to connect into the 42-inch-diameter storm drain (which will be constructed as part of the 30th
Street NE Area Flooding project, Phase I, from the 2009 Plan) near the intersection at I Street NE and 30th
Street NE. The 42-inch-diameter line will have sufficient available capacity to convey the I Street NE flows. Key
components of Project 4A include:
• 1,850 feet of 15-inch-diameter gravity storm drain
• Catch basin and incidental grading to collect stormwater at the upstream end of the system
Project 4B would address flooding along C Street NE (Figure 7-6). Currently stormwater flows along C Street NE
are conveyed north to the 37th Street NE storm conveyance line and discharge to Mill Creek. This project
would reduce flooding in C Street NE by increasing capacity in the line by lowering inverts and upsizing the
pipe diameter of a portion of the system, and by redirecting the high wet weather flows southward to the 42-
inch-diameter storm drain (to be completed in 2016) in 30th Street NE. Flows are redirected with a diversion
to a new pump station and force main connection to 30th Street NE. Key components of Project 4B include:
• Backflow preventer to isolate the C Street NE system from Mill Creek backwater
• Diversion structure in C Street NE for pump station
• Pump station (estimated capacity of 5 to 7 cfs)
• 850 feet of 24-inch-diameter drainage pipe (replace existing pipe with larger and steeper pipe)
• 1,730 feet of 15-inch-diameter force main
Upon completion, City staff should consider lowering the level settings for Brannan Park pumps 4 and 5,
because the hydraulic improvements associated with this project will allow more stormwater to reach the
pump station.
LOS goal(s)
addressed
• Public drainage infrastructure will be designed and maintained so that the annual chance of occurrence of
flooding disruption that inundates the city roadways to an impassable level no more than once every 25
Chapter 7 Comprehensive Storm Drainage Plan
7-18
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 4A and 4B (described jointly)
years. (LOS Goal 4)
• Public drainage infrastructure will be designed and maintained so that the annual chance of occurrence of
flooding (surface water from ROW runoff entering premises and damaging building structures) will occur no
more than once every 50 years. (LOS Goal 5)
Project 4B
recommended
predesign
refinements
Pump station design capacity and control strategy should consider the potential impacts to the downstream
conveyance systems along 30th Street NE and the airport. Pump station real time control at the airport
stormwater ponds could be included, where the pond outflow is restricted when the pump station is operating.
Cost estimate
Project 4A
Gravity storm drain: install 1,850 feet of 15-inch-diameter pipe (along I Street NE to 30th
Street NE storm drain) ............................................................................................................ $481,000
Subtotal line-item costs .......................................................................................................... $481,000
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) ............ $87,000
Construction contingency (20% of all above construction costs) ........................................ $114,000
Washington State and King County sales tax (9.5% of all above construction costs) ........ $65,000
Subtotal construction costs ................................................................................................... $747,000
Administration, engineering design, and permitting (20% of construction costs) .............. $145,000
CIP 4A (Phase 2) project cost $896,000
Cost estimate
Project 4B
Flow diversion structure ......................................................................................................... $4,000
Install backflow preventer for 24-inch-diameter pipe ........................................................... $10,000
Gravity line: replace 850 feet of pipe with 24-inch-diameter pipe at steeper grade .......... $289,000
Stormwater pump station: 5 to 7 cfs pump station located C Street NE to the south of 37th
Street NE ................................................................................................................................. $300,000
Force main: install 1,730 feet of 15-inch-diameter pipe (connect to 30th Street NE storm
drain) ....................................................................................................................................... $450,000
Subtotal line-item costs .......................................................................................................... $1,053,000
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) ............ $190,000
Construction contingency (20% of all above construction costs) ........................................ $249,000
Washington State and King County sales tax (9.5% of all above construction costs) ........ $142,000
Subtotal construction costs ................................................................................................... $1,634,000
Administration, engineering design, and permitting (30% of construction costs) ............. $490,000
CIP 4B (Phase 3) project cost $2,124,000
Total CIP 4A and 4B project cost $3,020,000
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Install 1,850 lf 15-inch drainage pipe
I
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30TH ST NE
28TH ST NE
31ST ST NE
32ND ST NE
32ND PL NE
L
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LEGEND
Pump Station
!(Storm Node
Storm Pipe
Storm Channel
Storm Culvert
Storm Pond
Proposed Drainage Pipe
¯0 300 600150
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-5Project 4A: 30th Street NE Area Flooding, Phase 2
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AU
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30TH ST NE30TH ST NW
35TH ST NE
LEGEND
!(Storm Node
Storm Pipe
Storm Channel
Storm Culvert
Storm Pond
%,Proposed Facility
Proposed Force Main
Proposed Drainage Pipe
¯0 300 600150
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-6Project 4B: 30th Street NE Area Flooding, Phase 3
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New pump station in C St. NE
New 1,730 lf force main in C S.t NE
Force main connection to
30th St. NE drainage pipe
Replace existing gravity pipe
with larger, steeper pipe
Install backflow preventer
Flow diversion structure
Comprehensive Storm Drainage Plan Chapter 7
7-23
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 5A
Project name West Hills Drainage Improvements at S 330th St. and 46th Pl. S
Location Southwest corner of S 330th Street and 46th Place S
Priority 2
Schedule Begin construction 2016
Problem summary
Flooding has been reported along the S 330th Street roadway. Surface water from upstream of the flooding
location including the City’s ROW is conveyed through a ditch and pipes, located on private property
adjacent to the problem area. The pipes located on private property had previously been conveyed in a
ditch. In an attempt to reclaim the front yard, a previous property owner filled the ditch with two parallel
pipes. The existing system discharges to a ravine outfall south of S 330th Street. Flows from the ravine
eventually discharge to Mill Creek.
Description
This project would re-route flows upstream of the private property including those flows from the City ROW
into a new piped system. The proposed 24-inch-diameter pipe would be aligned in the 46th Place S and S
330th Street ROWs. The project includes three connection structures: a tie-in to the existing system at the
upstream end, a manhole where the pipe alignment turns onto S 330th Street, and a manhole where the
pipe alignment turns toward the outfall. This manhole also connects the adjacent private system to the new
pipe system.
The project results in a single 24-inch-diameter pipe discharging to the existing outfall. The east side of the
existing outfall is a brick retaining wall and will be rebuilt as part of this project. The outfall will also be
reinforced with riprap.
LOS goal(s)
addressed Maintain or seek access to City-owned facilities for necessary maintenance and operation. (LOS Goal 13)
Recommended
predesign
refinements
Flows to the project area were estimated using WWHM12, assuming existing conditions for the current
subbasin contributing area. Prior to detailed design, the basin contributing area should be refined by
accounting for any changes due to new or re-development.
Obtain easement from one property owner.
Cost estimate
Extend existing (12-inch-diameter) culvert 18 feet to new tie-in connection .......................... $4,000
Gravity storm drain: install 220 feet of 24-inch-diameter pipe in ROW under power line ..... $70,000
Gravity storm drain: install 105 feet of 24-inch-diameter pipe in ROW .................................. $34,000
Gravity storm drain: install 22 feet of 24-inch-diameter pipe in easement ............................ $8,000
Gravity storm drain: install 34 feet of 12-inch-diameter pipe in easement from existing catch
basin to new manhole ................................................................................................................ $7,000
Install three connecting structures ............................................................................................ $10,000
Rebuild outfall and reinforce discharge area ............................................................................ $5,000
Obtain easement ........................................................................................................................ $20,000
Subtotal line-item costs .............................................................................................................. $158,000
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) ............... $28,000
Construction contingency (20% of all above construction costs) ............................................ $37,000
Washington State and King County sales tax (9.5% of all above construction costs) ............ $21,000
Subtotal construction costs ....................................................................................................... $244,000
Administration, engineering design, and permitting (30% of construction costs) .................. $73,000
CIP 5A project cost $317,000
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LEGEND
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#Storm Infall
#*Storm Outfall
Storm Channel
Storm Culvert
Parcels
Proposed Easement
%,Proposed Facility
Proposed Drainage Pipe
¯0 100 20050
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-7 Project 5A: West Hills Drainage Improvements S 330th St. and 46th Pl. S
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Install 220 lf
24-inch pipe
Extend existing culvert 18 feet
to new manhole
S 330th St
Connect existing 18-inch pipe
to new manhole
Install 105 lf
24-inch pipe
#*#*
!(
Inset
Connect existing catch basin
to new manhole with
34 lf 12-inch pipe
Rebuild existing outfall
and reinforce with riprap
Obtain easement
Replace existing 18-inch pipe
with 22 lf 24-inch pipe
Comprehensive Storm Drainage Plan Chapter 7
7-27
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 5B (Phases 1 and 2 described jointly)
Project name West Hills Drainage Improvements near S 314th St. and 54th Ave. S
Location S 314th Street and 54th Avenue S
Priority 2
Schedule Begin construction 2018
Problem summary
A City-owned pipe daylights to the back yard of a residential parcel on S 314th St and discharges runoff
onto the northern adjacent property. Although the northern property reports water under the home, there is
no record of nuisance ponding or flooding. The discharging pipe is the outfall for a 25-acre subbasin roughly
spanning S 316th and 314th streets and 52nd and 55th avenues S. The residential area surrounding the
25-acre subbasin (to the west and north) is served by a grass ditch and culvert system that conveys flows to
a culvert crossing at S 312th Street. The discharge continues through a series of open channels and
culverts and eventually drains to Mill Creek.
Description
Phase 1: The project’s first phase is to implement LID BMPs in the ROW to provide infiltration and reduce
flows into the existing and proposed piped system (Figure 7-8. The ROW areas in this neighborhood are
good candidates for roadside bioretention cells over gravel trench based on gentle consistent slope of the
existing grass-lined ditches, existing infall and outfall infrastructure, and lack of street/shoulder parking.
The gravel trench provides storage and detention time for infiltration in areas of low infiltration rates.
Phase 2: Given that LID BMPs do not significantly reduce high flows, the project also includes installing 385
feet of 18-inch-diameter pipe through easements and ROW to connect the existing discharge point to the
downstream system on S 312th Street (Figure 7-8). Pipe conveyance was selected over a ditch to minimize
the risk of flooding impacts to private premises and to ensure future conveyance maintenance. The pipe
alignment includes upgrading the ditch and culvert system on S 312th Street to a piped system. The
existing 12-inch-diameter culvert crossing S 312th Street will be increased to a 24-inch-diameter culvert.
The culvert discharges to an open channel that traverses three private properties. The culvert outfall will be
reinforced with riprap.
LOS goal(s)
addressed
• Public drainage infrastructure will be designed and maintained so that the annual chance of occurrence
of flooding (surface water from ROW runoff entering premises and damaging building structures) will
occur no more than once every 50 years. (LOS Goal 5)
• Maintain or seek access to City-owned facilities for necessary maintenance and operation. (LOS Goal
13)
Recommended
predesign
refinements
Confirm infiltrative capacity of proposed bioretention sites with infiltration tests. Soils in the area are listed
as NRCS hydrologic soil group “C,” which has a low infiltration rate (0.15 to 0.05 inch per hour), but there
may be localized areas with higher infiltration rates.
Confirm that grades and existing culvert and pipe inlets are sufficient for LID BMP drainage design.
Confirm the open channel downstream of S 312th Street culvert crossing has the capacity for the 100-year
flow (based on City open-channel design standards).
The King County culvert crossing 51st Avenue S is the next culvert downstream of the project area. The
infall to this culvert is partially blocked by a living tree root wad. With more surface flow directed to this
infall, the root wad should be removed. This effort will need to be coordinated with King County.
Obtain easements from two property owners.
Cost estimate
Phase 1
Install 7 gravel trench draining bioretention cells with infall and outfall connection to the
existing drainage system ............................................................................................................ $210,000
Subtotal line-item costs ............................................................................................................. $210,000
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) ............... $38,000
Construction contingency (20% of all above construction costs) ............................................ $50,000
Washington State and King County sales tax (9.5% of all above construction costs) ............ $28,000
Subtotal construction costs ....................................................................................................... $326,000
Administration, engineering design, and permitting (25% of construction costs) .................. $82,000
CIP 5B (Phase 1) project cost $408,000
Chapter 7 Comprehensive Storm Drainage Plan
7-28
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 5B (Phases 1 and 2 described jointly)
Cost estimate
Phase 2
Gravity storm drain: install 385 feet of 18-inch-diameter pipe ................................................ $100,000
Upsize existing 12-inch-diameter culvert to 24-inch-diameter (36 feet) and reinforce culvert
outlet with riprap ........................................................................................................................ $15,000
Install five connecting structures .............................................................................................. $16,000
Easement acquisition ................................................................................................................. $20,000
Subtotal line-item costs ............................................................................................................. $151,000
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) ............... $27,000
Construction contingency (20% of all above construction costs) ............................................ $36,000
Washington State and King County sales tax (9.5% of all above construction costs) ............ $20,000
Subtotal construction costs ....................................................................................................... $234,000
Administration, engineering design, and permitting (30% of construction costs) .................. $70,000
CIP 5B (Phase 2) project cost $304,000
Total CIP 5B project cost $712,000
#*
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S 316TH ST
S 312TH ST
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LEGEND
!(Storm Node
Storm Pipe
#Storm Infall
#*Storm Outfall
Storm Channel
Storm Culvert
Parcels
Proposed Easement
Proposed Bioretention
%,Proposed Facility
Proposed Drainage Pipe
¯0 250 500125
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-8Project 5B:West Hill Drainage Improvements S 314th St. and 54th Ave. S
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1 inch = 250 feet
Replace existing 12-inch culvert
with 24-inch culvert
Reinforce outfall with riprap
Install 385 lf of 18-inch pipe from
existing discharge point to
new manhole at S 312th St culvert infall
Obtain easement for
existing and new pipe
Comprehensive Storm Drainage Plan Chapter 7
7-31
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 6
Project name North Airport Area Improvements
Location Northern extent of airport property near 30th Street NE
Priority 2
Schedule Begin construction 2016
Problem summary
Pond I: The current configurations of the inlet and outlet of airport Pond I do not allow the pond to operate as
designed. The inlet is intended to receive primary flows from the airport drainage system, but instead is
configured to take only high flows. The pond does not fill from its inlet because the inlet elevation is higher
than designed. The inlet is made further ineffective by an inverse grade or high point along its alignment.
Rather than accepting primary or low flows through its inlet and releasing detained water through a flow
control riser to the storm system in 30th Street NE, the pond fills from its outlet because of a disconnected
riser when the storm line in 30th Street NE surcharges. This surcharging usually occurs prior to the high
flows entering the pond.
North Hangar Area: In the north hangar area immediately east of Pond I, surcharging flows from the storm line
in 30th Street NE backwater to the airport’s 30-inch-diameter storm drain and causes flooding to the north
and west of the most northerly hangar. Historically, the flooding extends to part of the taxiway and into the
hangar. The grate inlets in 30th Street NE are higher than the ground elevation of the northern airport area,
which allows the airport area to flood before street flooding occurs in 30th Street NE. In addition, given that
onsite runoff is not being diverted to or retained by Pond I, onsite flows contribute to the north hangar area
surcharging.
Description:
Pond I: This project would provide Pond I with more detention volume and allow the pond inlet and outlet to
operate as intended, collecting and detaining surface water generated on airport property with high flows
discharging to the 30th Street NE system. The project would excavate portions of the pond to provide more
storage capacity, replace the existing inlet pipe at a lower invert and consistent positive slope to capture the
primary flow, reconnect the flow control structure to the outlet, and install a backflow preventer at the
outlet.
North Hangar Area: The project for the north hangar area consists of installing a backflow preventer at the
connection to the 30th Street NE system. Pond I upgrades need to be completed first because the north
hangar area is at a lower elevation and receives flow from both the airport drainage and the 30th Street NE
system. Because portions of the airport area have lower elevations than the adjacent 30th Street NE
system, the north hangar area may experience some localized flooding, even with the Pond I upgrades and
installation of backflow preventers, because the 30th Street NE is higher. This project would be constructed
as shown in Figure 7-9.
LOS goal(s)
addressed
• Public drainage infrastructure will be designed and maintained so that the annual chance of occurrence
of flooding disruption that inundates the city roadways to an impassable level no more than once every
25 years. (LOS Goal 4)
• Public drainage infrastructure will be designed and maintained so that the annual chance of occurrence
of flooding (surface water from ROW runoff entering premises and damaging building structures) will
occur no more than once every 50 years. (LOS Goal 5)
Recommended
predesign
refinements
None
Cost estimate
Pond I:
Excavate portions of the pond .............................................................................................. $46,000
Replace and lower pond inlet pipe ...................................................................................... $25,000
Upgrade diversion manhole ................................................................................................. $4,000
Replace flow control manhole at pond outlet ..................................................................... $4,000
Install backflow preventer .................................................................................................... $7,000
North Hangar Area:
Install backflow preventer for 30-inch-diameter pipe .......................................................... $14,000
Subtotal line-item costs ......................................................................................................... $100,000
Chapter 7 Comprehensive Storm Drainage Plan
7-32
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 6
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) ............ $18,000
Construction contingency (30% of all above construction costs)......................................... $35,000
Washington State and King County sales taxes (9.5% of all above construction costs) .... $15,000
Subtotal construction costs $168,000
Administration, engineering design, and permitting (30% of construction costs) $50,000
CIP 6 project cost $218,000
Repair flow control connection
and install backflow preventer
Replace pipe at new slope
Adjust pond inlet invert
Install backflow preventer
Excavate portions of the pond
Pond
I
Pond
H
Pond
G
Pond
F
AU
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A
Y
N
30TH ST NE
C
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26TH ST NE
30TH ST NW
E
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LEGEND
!(Storm Node
Storm Pipe
Storm Channel
Storm Culvert
Storm Pond
%,Proposed Facility
Proposed Drainage Pipe
¯0 300 600150
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-9Project 6: North Airport Area Improvements
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Comprehensive Storm Drainage Plan Chapter 7
7-35
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 7
Project name D St. SE Storm Improvements
Location Western end of 25th Street SE near D Street SE right-of-way
Priority 2
Schedule Begin construction 2018
Problem summary
The western dead-end portion of 25th Street SE has a history of observed flooding. An existing dry well has
inadequate infiltration. The dry well floods after heavy rain, several times a year. Floodwater fills the
adjacent section of 25th Street SE to the curb. There are also numerous dry wells not meeting discharge
standards in this area.
Description
This project consists of installing a new gravity drain to convey the peak 25-year flow rate from the flooding
location to the 21st Street stormwater pond (Figure 7-10). New piping consists of a 24-inch-diameter
gravity drain from the existing dry well location (at the intersection of D Street SE ROW and 25th Street SE)
north along D Street SE to the intersection of 23rd Street SE. New 30-inch-diameter gravity drain would be
installed from 23rd Street SE to the existing junction with the 48-inch-diameter gravity pipe in 21st Street
SE.
The existing dry wells at 23rd Street SE and 22nd Street SE would be removed. Conveyance piping to these
dry wells would be connected to the new 30-inch-diameter gravity drain.
The conveyance piping, along 25th Street SE, to the problematic dry well will be replaced with a new 12-
inch-diameter gravity drain because the existing conveyance is lower than the proposed conveyance piping
along D Street SE.
Additional dry wells at 26th Street SE and 27th Street SE would be removed. Conveyance piping along 26th
Street SE will also be replaced with a 12-inch-diameter gravity drain, because the existing conveyance
flows to the east.
A sixth dry well system, located at 27th Street SE and F Street SE, will be replaced with a gravity drain. A
12-inch-diameter gravity drain will be installed along F Street SE and connect to the existing manhole at the
intersection at 26th Street SE.
Recommended
predesign
requirement
None
LOS goal(s)
addressed
Public drainage infrastructure will be designed and maintained so that the annual chance of occurrence of
flooding disruption that inundates the city roadways to an impassable level no more than once every
25 years. (LOS Goal 4)
Cost estimate
Gravity piping: 990 feet of 30-inch-diameter pipe, 630 feet of 24-inch-diameter pipe,
and 1,610 feet of 12-inch-diameter pipe ................................................................... $906,000
Subtotal line-item costs ............................................................................................... $906,000
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) . $163,000
Construction contingency (20% of all above construction costs) .............................. $214,000
Washington State and King County sales tax (9.5% of all above construction costs) $122,000
Subtotal construction costs......................................................................................... $1,405,000
Administration, engineering design, and permitting (30% of construction costs) .... $422,000
CIP 11 project cost $1,827,000
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drainage pipe
Install 990 lf 30-inch-diameter
drainage pipe
Install 1,230 lf 12-inch-diameter
drainage pipe
Install 630 lf 24-inch-diameter
drainage pipe
F
S
T
S
E
21ST ST SE
D
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S
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26TH ST SE
25TH ST SE
27TH ST SE
22ND ST SE
23RD ST SE
28TH ST SE
24TH ST SE
H
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CEDAR DR SE
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28TH ST SE
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LEGEND
!(Storm Node
!(Storm Node with flow control
!(Dry Well
Storm Pipes
Storm Pond
Proposed Drainage Pipe
¯0 300 600150
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-10Project 7: D St. SE Storm Improvements
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Comprehensive Storm Drainage Plan Chapter 7
7-39
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Project number 8
Project name 23rd St. SE Drainage Improvements
Location 23rd and K streets SE
Priority 3
Schedule Begin construction 2018
Problem summary
A new 12-inch-diameter stormwater gravity drain was installed along K Street SE, south of 23rd Street SE,
in 2014 to address localized flooding. This piping increased the tributary area to the 8-inch-diameter
gravity drain along 23rd Street SE. Modeling results indicate that the existing 8-inch-diameter gravity drain
along 23rd Street SE does not meet the LOS.
Description
This project has a phased approach. Phase 1 consists of installing a new 15-inch-diameter gravity drain
along K Street SE from the intersection of 23rd Street SE to the intersection of 21st Street SE (Figure 7-
11). The new pipe would connect to the existing 24-inch-diameter system along 21st Street SE, which
eventually discharges to the 21st Street Pond. The existing 8-inch-diameter gravity drain pipe conveying
flow west from the intersection of K Street SE and 23rd Street SE would be plugged so that all runoff on K
Street SE would be conveyed north.
Phase 2 consists of installing a new 18-inch-diameter gravity drain along 23rd Street SE from H Street SE
to F Street SE. The new pipe would connect to the existing 24-inch-diameter system along 23rd Street SE.
This system eventually discharges to the 21st Street Pond. After completion of Phase 1 and prior to
implementing Phase 2, the storm system along 23rd Street SE should be monitored during large events to
confirm that water levels in pipe are surcharging. An existing detention system in the tributary area was not
explicitly modeled during project development, and may manage flows such that simulated surcharging
does not occur. If this is the case, then Phase 2 would not be required to meet the City’s LOS.
Recommended
predesign
requirement
Periodic site inspections by the maintenance crews during storm events to observe water levels in pipes
along 23rd Street SE
LOS goal(s)
addressed
Public drainage infrastructure will be designed and maintained so that the annual chance of occurrence of
flooding disruption that inundates the city roadways to an impassable level no more than once every
25 years. (LOS Goal 4)
Cost estimate
Phase 1: Gravity piping: 600 feet of 18-inch-diameter pipe, plug existing 8-inch-
diameter pipe ............................................................................................................... $157,000
Phase 2: Gravity piping: 560 feet of 21-inch-diameter pipe ..................................... $157,000
Subtotal line-item costs ............................................................................................... $314,000
Contractor overhead, profit, and mobilization (18% of subtotal of line-item costs) . $57,000
Construction contingency (20% of all above construction costs).............................. $74,000
Washington State and King County sales tax (9.5% of all above construction costs) $42,000
Subtotal construction costs ........................................................................................ $487,000
Administration, engineering design, and permitting (30% of construction costs).... $146,000
CIP 8 project cost $633,000
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Phase 2:
Install 560 lf 18-inch-diameter
drainage pipe
Phase 1:
Install 600 lf 15-inch-diameter
drainage pipe
Phase 1:
Disconnect drainage pipe
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21ST ST SE
25TH ST SE
23RD ST SE
26TH ST SE
27TH ST SE
H
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24TH ST SE
20TH ST SE
CEDAR DR SE
23RD PL SE
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LEGEND
!(Storm Node
Storm Pipe
Storm Pond
Proposed Drainage Pipe
¯0 300 600150
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COMPREHENSIVE STORM DRAINAGE PLAN
April 2015 Figure 7-11Project 8: 23rd St. SE Drainage Improvements
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Project number 9
Project name Comprehensive Storm Drainage Plan update
Location City-wide
Priority 1
Schedule Begin development 2020
Problem summary The Storm Drainage Utility is responsible for the maintenance, operations and improvements of the storm
drainage system.
Description
The Comprehensive Storm Drainage Plan would include an update to the capital projects in the existing
plan. Projects not completed, but still required to address a problem would be reevaluated and updated
based on recent information, such as drainage system inventory, system changes, flow monitoring,
flooding, and recent unit costs.
It would also include capital projects to address newly identified problems, including projects resulting from
the Hillside Drainage Assessment (project number 3) and the flow monitoring proposed in the
Implementation Plan (Chapter 8).
The plan would include additional activities required to address new regulatory requirements.
The plan would include cost-of-service studies to reassess the monthly service fees and SDCs.
LOS goal(s)
addressed
The Comprehensive Storm Drainage Plan guides the City’s Storm Drainage Utility with respect to future
activities and improvements in order to meet established LOS goals.
Cost estimate Update Comprehensive Storm Drainage Plan ............................................................ $300,000
CIP 9 project cost $300,000
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Project number 10
Project name Vegetative Waste Sorting Facility
Location To be determined
Priority 1
Schedule Purchase property in 2017; develop property 2018
Problem summary
The Storm Drainage Utility is responsible for the maintenance and operations of the storm drainage
system. Pond and drainage ditch maintenance and rehabilitation involves removal of plant material and
sediments, which are considered non-hazardous and are suitable for recycling. During fall and winter,
debris from storm cleanups also yield materials suitable for recycling. The Storm Drainage Utility currently
uses the City-owned Jacobson Tree Farm property for storing and drying of these materials, prior to hauling
off-site for recycling. The property is owned by the Parks Department and is scheduled to be repurposed,
precluding its use for ongoing M&O activities.
Description
This project addresses the need for a new site to sort, dry, and store materials removed from drainage
ditches, swales, and ponds during maintenance and restoration activities necessary to maintain the storm
drainage system. This project includes the purchase of property (preferably located central to maintenance
and restoration sites), initial costs to develop the property (i.e., provide power and water), and purchase
equipment for sorting and drying of materials.
LOS goal(s)
addressed
The City shall seek to maintain storm drainage infrastructure to ensure proper function of drainage
facilities in accordance with Ecology requirements. (LOS Goal 12)
Cost estimate Purchase property........................................................................................................
Develop property and purchase equipment ...............................................................
$750,000
$75,000
CIP 10 project cost $825,000
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Programmatic Drainage Projects 7.3
To ensure an adequate level of utility funding in the future, the City must consider longer-range
programmatic efforts to maintain and/or improve storm drainage service. Table 7-1 lists programmatic
projects that should be included in the Storm Drainage Utility budget. These projects are not linked to
any specific problem or location, but are included for budgetary purposes. By itemizing these activities,
the Storm Drainage Utility can track actual costs to compare with budgeted costs and specifically track
how these expenditures address the LOS goals listed in Chapter 3. The items listed in the table below
are distributed between the 6- and 20-year CIPs in Chapter 8.
Table 7-1. Summary Programmatic Drainage Projects
CIP
number Project or program name and description Priority Total project cost
(2014 dollars)
11
Storm Drainage Infrastructure Repair & Replacement. This item addresses the need to
repair or replace storm drainage infrastructure such as individual pipes, pump station
repair and maintenance, and pond improvements. The long-term priorities for R&R
should be developed by adhering to LOS Goals 8–9 and 11 regarding the
maintenance of a criticality database and the prioritized assessment of critical
infrastructure.
LOS Goal Addressed: Goal 10. “The City shall seek to repair or replace system assets
before they exceed their economic lives.”
1 $11,000,000
12
Street Utility Improvements. The Storm Drainage Utility will seek opportunities to
incorporate drainage improvements into transportation and pavement projects on city
roads. The majority of storm drainage costs related to projects that bring streets to
current design standards are incurred by the City’s Transportation Program.
LOS Goal Addressed: Goal 23. “The City shall continue to fund and provide storm
drainage services through the existing storm drainage utility.” Seeking opportunities to
implement drainage improvements at lower unit costs will help the Storm Drainage
Utility remain within its funding limits.
1 $2,000,000
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Chapter 8
Implementation Plan
This chapter presents the implementation plan, which brings together information from the preceding
chapters to form a work plan of future activities for the Storm Drainage Utility. The information in this
chapter serves as a road map to the Storm Drainage Utility staff. This road map outlines the critical
elements of plan implementation (e.g., CIP implementation, stormwater monitoring, NPDES Permit
compliance, future staffing, and asset management) and links them into a schedule of utility activities.
The implementation plan is divided into six main sections:
• Section 8.1 presents the CIP for both 6-year and 20-year time frames. Section 8.2 describes
recommendations for future monitoring and data collection to support future planning activities.
• Section 8.3 contains a summary of activities for NPDES Permit compliance.
• Section 8.4 presents recommendations for future staffing.
• Section 8.5 describes recommendations for continuing the implementation of best practices for
asset management.
• Section 8.6 makes recommendations for additional activities that help the Storm Drainage Utility
achieve the LOS goals.
The foldout chart (Figure 8-4) at the conclusion of this chapter shows the proposed implementation
timeline. Appendix D provides the SEPA determination for the implementation plan.
6-Year and 20-Year CIP 8.1
The 6-year CIP contains near-term capital improvement projects focused on mitigating the most critical
existing drainage problems that have been observed and are well understood by the City’s staff. These
projects are described in detail in Chapter 7. In addition to site-specific projects, the 6-year CIP contains
ongoing programmatic efforts, such as the Storm Drainage Utility’s participation in the Street Utility
Improvement program. Table 8-1 lists all 11 capital improvement projects described in Chapter 7 and
lays out annual expenditures for the 6-year CIP time frame. Project timing is based on project priorities
weighed with likely budgetary constraints such that costs are distributed somewhat evenly from year to
year (see Table 8-1 and Figure 8-1).
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Table 8-1. Annual Project Cost Summary for 6-Year CIP
Project
number Project name Priority Repair/
Replacement
Upgrade/
Expansion 2016 2017 2018 2019 2020 2021 6-year project
cost, $
1 West Main Street Pump Station Upgrade 1 100% 2,968,000 2,968,000
2 37th and I Streets NW Storm
Improvements 1 100% 291,000 291,000
3 Hillside Drainage Assessment 1 100% 139,000 150,000 289,000
4A 30th Street NE Area Flooding, Phase 2 2 100% 896,000 896,000
4B 30th Street NE Area Flooding, Phase 3 3 100% 2,124,000 2,124,000
5A West Hills Drainage Improvements at S
330th St. and 46th Pl. S 2 100% 317,000 317,000
5B West Hills Drainage Improvements near S
314th St. and 54th Ave. S 3 100% 408,000 304,000 712,000
6 North Airport Area Improvements 2 100% 218,000 218,000
7 D St. SE Storm Improvements 2 100% 1,827,000 1,827,000
8 23rd St. SE Drainage Improvements 3 100% 316,500 316,500 633,000
9 Comprehensive Storm Drainage Plan
update 1 35% 65% 300,000 300,000
10 Vegetative Waste Sorting Facility 1 100% 750,000 75,000 825,000
11 Storm Drainage Infrastructure Repair and
Replacement Programa 1 100% 100,000 1,000,000 100,000 1,000,000 100,000 1,000,000 3,300,000
12 Street Utility Improvementsa 1 100% 100,000 100,000 100,000 100,000 100,000 100,000 600,000
Total 6-year CIP cost for priority 1 projects 3,598,000 2,000,000 275,000 1,100,000 500,000 1,100,000 8,573,000
Total 6-year CIP cost for priority 2 projects 535,000 896,000 1,827,000 0 0 0 3,258,000
Total 6-year CIP cost for priority 3 projects 0 0 724,500 2,124,000 304,000 316,500 3,469,000
Total 6-year CIP cost $4,133,000 $2,896,000 $2,826,500 $3,224,000 $804,000 $1,416,500 $15,300,000
a. Additional project costs included in 20-year CIP.
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Figure 8-1. Annual Costs for 6-year CIP
Long-term stormwater conveyance demands should remain near current levels because, unlike
wastewater planning where population growth brings additional flow demands, most new development
and redevelopment projects will be subject to the City’s development standards for onsite stormwater
control. Local stormwater detention and integrated LID stormwater features should control stormwater
flows to maintain approximately existing levels.
After existing drainage problems are addressed, the City will begin to shift its priorities away from
responding to known drainage problems toward managing existing storm drainage assets to ensure that
LOS goals are continuously met. These long-range capital improvements will focus on programmatic
activities, such as R&R, where the R&R schedule is based on asset conditions and prioritizes assets that
are nearing the end of their economic life. Table 8-2 summarizes the program expenditures and
forecasts total CIP costs for the years 2022 to 2035.
$0
$500,000
$1,000,000
$1,500,000
$2,000,000
$2,500,000
$3,000,000
$3,500,000
$4,000,000
$4,500,000
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Table 8-2. Cost Summary for 20-Year CIP
Project
number Program name Priority Project costs for 2022–35
(2014 dollars)
11 Storm Drainage Infrastructure Repair and Replacement Program 1 7,700,000
12 Street Utility Improvements 1 1,400,000
Total 2022–35 CIP cost for priority 1 projects 9,633,800
Total 2022–35 CIP cost for priority 2 projects 0
Total 2022–35 CIP cost for priority 3 projects 0
Total CIP cost (2022–35) $9,100,000
Total 20-year CIP cost (2016–35) $13,000,000
In addition to the identified projects and programs, the City identified two potential problem areas that
may warrant a project in the future (see Section 4.5). Projects were not developed for this these areas
for the following reasons: (1) existing data were inadequate to understand the potential problem, or (2)
stormwater routing to the area may be changing (because of implementation of an upstream City or
private project), which could affect the need, sizing, and timing of a project. These potential problem
areas require additional data to obtain a better understanding needed to develop a capital improvement
project, if warranted. Section 8.2 provides recommendations for activities that will assist with
understanding and addressing the potential problems.
Monitoring 8.2
Evaluating the adequacy of the storm drainage system and analyzing potential capital improvements
require extensive data. This includes not only infrastructure data such as pipe sizes, invert elevations,
and outfall locations, but also stormwater data such as runoff volumes, flow rates, and flooding
elevations. The City should continue to collect these types of data and store them in a consistent and
organized manner. The following sections describe specific recommendations for additional monitoring
data collection for identified potential problems, as well as summarizing ongoing monitoring efforts.
8.2.1 Precipitation
Precipitation is the source of stormwater runoff. Precipitation intensity and duration data are needed to
characterize rainfall-runoff processes and adequately design for drainage of stormwater runoff. The City
has been collecting precipitation data at City Hall since 1995, and is currently using a Texas Electronics
Model TE525 gauge to record precipitation data with network connectivity allowing for data downloading
by City staff. The City also has a manual rain gauge where data are collected weekly. These data are
used to back up and validate the TE525 gauge data. The City should continue to monitor precipitation at
City Hall using this equipment or updated equipment.
8.2.2 Flow
Flow data are used to gain a better understanding of the H&H conditions within a drainage basin.
Accurate measurement of flow provides both peak discharge estimates for sizing conveyance capacity
within the drainage network and runoff volumes for use in evaluating storm drainage facilities and
improvement projects. Two potential problem locations require newly collected flow data to perform
model development and calibration, which will support the analysis of problem area (see Section 4.5 for
discussion on potential problem areas). Table 8-3 lists each of the recommended flow monitoring sites,
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purpose, type of measurement, recommended start year, and approximate duration of monitoring. Figure
8-2 shows the proposed monitoring locations.
Table 8-3. Proposed Flow Monitoring Sites
Site numbera Location Purpose Measurement Start year Approx.
durationb
Potential problem area: Riverwalk Drive and Howard Road (directing tributary area to17th and 21st Street ponds)
P1012-
C690_C689
Intersection of
Auburn Way S and
Riverwalk Dr. SE
Quantify flow from upstream areas tributary to
flow control device in CB1012-C688
Depth and
velocity 2016 1 to 2 wet seasons
CB1012-C688
Intersection of
Auburn Way S and
Riverwalk Dr. SE
Estimate flows to high flow ditch on Riverwalk Dr.
SE Depth 2016 1 to 2 wet seasons
C1111-
C1469_C1470
Intersection of
Howard Rd. and
Riverwalk Dr. SE
Quantify flows to support modeling flows that
may be connected to the City’s system at
CB1011-C1474
Depth and
velocity 2016 1 to 2 wet seasons
P1011-
C1452_C1453
Howard Rd. between
21st St. SE and
Riverwalk Dr. SE
Quantify flows to support modeling flows that
may be connected to the City’s system at
CB1011-C1474
Depth and
velocity 2016 1 to 2 wet seasons
P1011-
C1086_C1137
Howard Rd. between
21st St. SE and
Riverwalk Dr. SE
Quantify flows to support modeling flows that
may be connected to the City’s system at
CB1011-C1474
Depth and
velocity 2016 1 to 2 wet seasons
P1010-C3_C29 Howard Rd. near
Auburn Way S
Provide data for H&H model calibration
(subbasin C)
Depth and
velocity 2016 1 to 2 wet seasons
P1010-
B220_B221
21st and K Streets
SE
Provide data for H&H model calibration
(subbasin C) post-CIP (AWS Phase 2)c
Depth and
velocity 2016 1 to 2 wet seasons
Potential problem area: 2nd and G streets SE
P909-
C122_C121
Auburn Way S, near
9th St. SE
Quantify flows upstream of flow split (at MH 909-
C12) between subbasins B and C, and provide
data for H&H model calibration
Depth and
velocity
Post-AWS
Phase 2c,d
1 to 2 wet seasons
P809-
C113_C112
F St. SE, north of SR
18
Quantify flows upstream of sewer crossing, and
provide data for H&H model calibration
Depth and
velocity
Post-AWS
Phase 2c,d
1 to 2 wet seasons
P810-
C701_809-C18
G St. SE and E Main
St.
Provide data for H&H model calibration (subbasin
C)
Depth and
velocity
Post-AWS
Phase 2c,d
1 to 2 wet seasons
P810-C698_C16 M St. SE, south of E
Main St.
Provide data for H&H model calibration since M
St. Grade Separation and Well 1 Transmission
Projects implementation
Depth and
velocity
Post-AWS
Phase 2c,d
1 to 2 wet seasons
P810-C15_C241 E Main St. and N St.
SE Estimate backwater effects on drainage system Depth and
velocity
Post-AWS
Phase 2c,d 1 to 2 wet seasons
a. P = pipe, C = culvert, CB = catch basin, MH = manhole.
b. Data to support CIP need at least one wet season of good data—approximately October through April; if sufficiently large storms occur
during the first season, then year 2 data may not be necessary. Monitoring period and duration within a potential problem area should
be the same.
c. Auburn Way S Flooding, Phase 2 (AWS Phase 2) is planned for construction in 2015.
d. Detailed survey of the flow split at MH 909-C12 should be completed prior to flow monitoring, to understand system hydraulics at this
location.
!A
!A
!A
!A
!A!A!A
!A!A
!A
!A
!A
!A
!A !A!A
!A
XW
!R
!R
!R
!R
!R
!R
CB1012-C688
P1010-C3_C29
WL-Pond-Mill
P810-C15_C241
P810-C698_C16
WL-Pond-LakeE
WL-Pond-RiverN
P909-C122_C121
P809-C113_C112
WL-Pond-LakeS2
WL-Pond-LakeS1
P1010-B220_B221
P1012-C690_C689
P810-C701_809-C18
C1111-C1469_C1470
P1011-C1452_C1453P1011-C1086_C1137
RG-01
WL-Mill-03
WL-Mill-04
WL-Mill-02
WL-Mill-01
WL-Pond-17thSt
WL-Pond-21stSt
LEGEND
!A Proposed Monitoring Site
!R Existing Monitoring Site
XW City Rain Gauge
Storm Pipe
Watercourse
Water Body
Wetland
Auburn City Boundary
¯0 4,000 8,0002,000
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
October 2015 Figure 8-2Proposed MonitoringLocations
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8.2.3 Stream and Pond Water Level
Water level data can also be useful for evaluating the performance of stormwater ponds and assessing
the risk of overtopping. Monitoring also will enable the City to identify changes in performance that may
indicate excessive sedimentation and the need for active maintenance. Additionally, continued water
level monitoring will help the City evaluate changes in Mill Creek water elevations that may occur
because of restoration and culvert replacement activities along Mill Creek.
The City should continue its water level monitoring program at selected sites to collect data for the
purposes described above. Because water level monitoring is less expensive than flow monitoring, a
broader ongoing water level monitoring program is more practical. Water level monitoring equipment
should be compatible with telemetric data systems such that each site can be integrated into the City’s
telemetry system, wherever continuous power and data lines are available. Table 8-4 lists each of the
recommended water level monitoring sites, purpose of the monitoring, recommended start year, and
approximate duration of monitoring.
Table 8-4. Proposed Water Level Monitoring Sites
Site number Location Purpose Start year Approx.
duration
WL-Mill-01 Mill Creek at 37th St. NW Evaluate stages in Mill Creek and assess backwater
effects on drainage system Ongoing since 2011 10 yearsa
WL-Mill-02 Mill Creek at 29th St. NW Evaluate stages in Mill Creek and assess backwater
effects on drainage system Ongoing since 2011 10 yearsa
WL-Mill-03 Mill Creek at 15th St. NW Evaluate stages in Mill Creek and assess backwater
effects on drainage system Ongoing since 2011 10 yearsa
WL-Mill-04 Mill Creek at West Main St. Evaluate stages in Mill Creek and assess backwater
effects on drainage system Ongoing since 2011 10 yearsa
WL-Pond-17thSt 17th and A streets SE Monitor pond performance (water levels and infiltration
rates) Ongoing since 2010 Indefiniteb
WL-Pond-21stSt 21st and D streets SE Monitor pond performance (water levels and infiltration
rates) Ongoing since 2011 Indefiniteb
WL-Pond-RiverN Riverwalk Dr. SE and U St. SE
Monitor pond performance (water levels and infiltration
rates) and evaluate capacity in support of analysis for
potential problem area at Riverwalk and Howard Road
2015 Indefiniteb
WL-Pond-LakeS1 Lakeland South Pond 1 Monitor water level to evaluate hazard risk (dam safety) 2015 Indefiniteb
WL-Pond-LakeS2 Lakeland South Pond 2 Monitor water level to evaluate hazard risk (dam safety) 2015 Indefiniteb
WL-Pond-LakeEP Lakeland East Pond Monitor water level to evaluate hazard risk (dam safety) 2015 Indefiniteb
WL-Pond-Mill Mill Pond (Oravetz Rd. SE) Monitor water level to evaluate hazard risk (dam safety) 2015 Indefiniteb
a. Based on need to examine backwater effects on system; if new capital improvements are identified for Mill Creek, additional years may be
needed.
b. To be continually reevaluated; if data indicate that stormwater pond is performing adequately or has low risk of failure, then monitoring
could cease.
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8.2.4 Water Quality
The current NPDES Permit, which is effective through 2018, includes provisions for monitoring and
assessment of water quality. Permittees have the option of paying annual fees to participate in statewide
monitoring programs, or developing individual monitoring programs to meet the requirement. The City
notified Ecology in 2013 that it intends to participate in the statewide monitoring programs. By opting to
participate in statewide monitoring programs, the City has agreed to pay program fees to Ecology. Fees
totaling $47,710 are due annually, beginning in August 2014. Refer to Section S8 of the current NPDES
Permit (Appendix A) for additional information.
Programmatic Measures for NPDES Compliance 8.3
The City of Auburn is covered by the Western Washington Phase II Municipal Stormwater Permit (NPDES
Permit). The Permit regulates stormwater discharges from the City’s MS4 (see Section 2.3.2). The
current version of the Permit will remain in effect through July 2018, when a new version is due to be
issued.
The City is actively engaged in stormwater management activities to comply with the Permit, including
the following:
• SWMP administration
• Public education and outreach
• Public involvement and participation
• IDDE
• Control of runoff from new development, redevelopment, and construction sites
• Municipal operations and maintenance
• Monitoring and assessment
The City maintains and annually updates its SWMP Plan, which documents new and ongoing stormwater
management activities planned for the upcoming year. The current SWMP Plan is available on the City’s
website.
Updates to City codes, programs, and standards are required by the end of 2016 to comply with the
current NPDES Permit. The City is engaging in a process to evaluate, plan, and implement necessary
updates to City regulations and programs. The process will engage staff across City departments, the
public, and elected officials to evaluate and determine updates. As part of the process, the City
developed a Compliance Work Plan to outline and guide compliance activities over the current NPDES
Permit term. A copy of the Compliance Work Plan is included as Appendix B. The compliance schedule
for key requirements under the current NPDES Permit is shown in Figure 8-3.
One of the key NPDES Permit requirements is adoption of an updated stormwater manual. To meet this
requirement, the City may opt to update the Auburn SWMM to maintain equivalency with the 2012
Ecology Stormwater Management Manual for Western Washington. Alternatively, the City could adopt the
Ecology manual or an approved equivalent stormwater manual developed by an NPDES Phase I
jurisdiction (e.g., City of Tacoma). Potential updates to the SWMM represent a major effort for City staff,
and would need to be planned for accordingly.
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Figure 8-3. NPDES Compliance Schedule
Future Staffing and Equipment Needs 8.4
During this planning effort, current Engineering and M&O staffing were reviewed in light of future
activities that will need to be performed to maintain compliance with the NPDES Permit. M&O staffing
and equipment were also reviewed in light of existing maintenance goals and future, additional M&O
responsibilities. The following sections summarize the additional staffing, staffing responsibilities, and
equipment needs for the Storm Drainage Utility.
8.4.1 Engineering Services
This section discusses additional Engineering staffing responsibilities necessary to address
requirements of the revised NPDES Permit and other identified storm drainage system deficiencies.
Many of the new requirements of the NPDES Permit emphasize implementation of LID practices, such as
minimizing impervious surfaces, native vegetation loss, and stormwater runoff. A majority of new
development and redevelopment projects will be required to construct new types of onsite LID facilities,
which will need to be inspected and maintained to ensure proper function.
Under an NPDES Compliance planning effort, an estimate of the additional efforts required by the City to
address NPDES Permit requirements was prepared (Appendix B). The need and timing of additional
Engineering staff is summarized as follows:
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• In 2016, existing staff will need to accomplish the following NPDES compliance activities:
− Update public guidance material and checklists to align with new City/NPDES Permit
requirements
− Develop procedures for public LID facility maintenance and oversight of private facilities
− Update or adopt the Stormwater Manual to meet requirements
− Develop City planning methods and update ACC to meet new Permit requirements for
stormwater, including new runoff control requirements thresholds, BMP performance standards,
and LID requirements
− Update the City Comprehensive Plan related to implementation of LID principles that could
affect elements beyond stormwater management implementation such as LOSs, setbacks,
zoning densities, etc.
• By 2017, it is estimated that additional staff (1.15 FTEs) will be needed for NPDES compliance
activities:
− Inspect new LID facilities regularly, and purchase and maintain associated field instruments
required to perform inspections (1 FTE). Depending on the level of future development,
additional staff beyond 1 FTE may be required.
− Define and organize LID asset classification, coordinate/update maintenance tracking methods,
and track and record maintenance of stormwater assets (0.1 FTE).
− 0.05 FTE to update public education and outreach materials to include additional target
audiences, evaluate program effectiveness, and conduct regional coordination (0.05 FTE).
Additional staffing needs described above and their associated costs, assuming an FTE annual
salary and benefits are $93,000, are summarized in Table 8-5.
Table 8-5. Future Engineering Services Staffing Needs
Additional Engineering Services activity Staff needs (in
2017) Cost
LID facility inspector to inspect new LID facilities regularly, and purchase
and maintain associated field instruments required to perform
inspections. Depending on the level of future development, additional
staff beyond 1 FTE may be required.
1 FTE $93,000
Define and organize LID asset classification, coordinate/update
maintenance tracking methods, and track and record maintenance of
stormwater assets.
0.1 FTE $9,300
Update public education and outreach materials to include additional
target audiences, evaluate program effectiveness, and conduct regional
coordination.
0.05 FTE $4,650
2017 total cost $106,950
8.4.2 M&O Services
The M&O staffing required to efficiently manage, operate, and maintain the storm drainage system was
evaluated in Chapter 6. The analysis indicates that the Storm Drainage Utility is appropriately staffed
internally with respect to meeting proactive City goals for current M&O activities. However, an additional
1.2 FTE within the City Vegetation Maintenance Division is required to provide current vegetation
maintenance in support of the Stormwater Drainage Utility. Additional staff and equipment will be
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needed to meet NPDES Permit requirements and other anticipated future work (see Section 6.6.2).
Future M&O and Vegetation Maintenance staffing requirements are described in Section 6.6.2 and
summarized in Table 8-6.
Table 8-6. Future Maintenance and Operations Staffing Needs
Additional M&O activity FTE days
required annually Assumptions/City goal
Drainage ditch and stormwater pond maintenance and restoration
Drainage ditch maintenance and restoration 216 Six-person crew for 36 days during the summer months.
Stormwater pond restoration 330 Six-person crew for 55 days during the summer months.
Other stormwater M&O activities
Cartegraph tracking and reporting 111 Approximately 0.5 FTE (1 FTE shared with Sewer and Water utilities).
LID inspection and maintenance 104 One day per week. Two-person crew.
Total 761
Total number of working days available
per FTE 221 365 minus weekends (104), holidays (12), vacation (15), sick (12), and
training (1).
Number of additional FTEs required 3.4 761 days required divided by 221 days per FTE year.
Based upon discussions with City staff and analysis of M&O activities discussed in Chapter 6, the Storm
Drainage Utility should obtain or upgrade the following utility equipment to improve M&O efficiency:
• CCTV inspection equipment for pipe inspection
• Excavator for drainage ditch and stormwater pond maintenance and restoration
• Excavator mower attachment for pond vegetation maintenance
Continue Implementation of Best Practices for Asset Management 8.5
The 6-year CIP focuses mainly on existing flooding problems where recent storm events have revealed
deficiencies in the drainage system. The capital improvement projects are designed to mitigate flooding
in these areas and are expected to provide immediate benefits. As current problems are addressed in
the near term, the focus of the CIP can begin to shift from a reactive program to a more proactive
program, where repair or replacement of storm drainage assets can be prioritized according to the
optimal timing for interventions. Ultimately, this process will allow the City to meet customer service
levels, effectively manage risks, and minimize the City’s costs of ownership.
The following sections present recommendations for future and ongoing asset management activities for
the Storm Drainage Utility. Section 8.5 is divided into the following five sub-sections:
• Section 8.5.1 discusses the continued development of the system inventory.
• Section 8.5.2 provides a discussion about ways to optimize the M&O program through criticality-
based strategies and use of the CMMS.
• Section 8.5.3 discusses economic life model improvements
• Section 8.5.4 provides a discussion about ways to optimize the M&O and R&R programs with the
economic life model.
• Section 8.5.5 summarizes additional M&O activities identified during the M&O evaluations
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8.5.1 Continue System Inventory
A comprehensive system inventory is needed for many reasons, including:
• Understanding existing problems
• Developing strategies to address existing problems
• Conducting analysis to support detailed design of capital improvement projects
• Prioritizing maintenance activities
• Budgeting and developing a schedule for R&R
A system inventory includes documenting at a minimum the location, size, length, material, depth,
condition, and maintenance history of all drainage assets. The magnitude of the system inventory effort
is quite large and the City has made great strides in updating its inventory through dedicated survey
staff. Staff have been working throughout the city, quarter section by quarter section. Even though
significant progress has been made, of the 137 quarter sections covering the City’s storm drainage
system, only 32 (about 25 percent) have been inventoried. An additional 11 (8 percent) are in progress.
Therefore, it is recommended that the data inventory task be continued as part of future activities, and
that the inventory be continually updated to reflect additional data collected during maintenance
activities (i.e., condition assessment and frequency of maintenance activities) and drainage system
changes through capital improvement projects.
8.5.2 Implement Economic Life Model Using Cartegraph Data
An economic life model containing data for the City’s stormwater drainage pipes was developed as part
of the 2009 Drainage Plan. The model predicts a probability and a cost of failure for each pipe segment.
The model calculates the risk cost of an asset by multiplying the probability of the asset failing by the
cost of that asset failing. By comparing the risk cost of each segment to the minimum annualized cost of
ownership for an intervention, the optimal economic timing for either rehabilitation or replacing each
segment is calculated. A detailed description of the economic life analysis is provided in the 2009
Drainage Plan.
Evaluations completed for this Drainage Plan consisted of developing a software requirement
specification (SRS) describing the requirements and calculations required to implement the economic
life model for the City’s stormwater collection system using Cartegraph CMMS as a primary data source
(Brown and Caldwell, 2014). Following the SRS, the City should implement the economic life model as
well as the mode improvements described in Section 8.5.3. With continual updates of the internal data
into Cartegraph (as described in Section 8.5.1), the model will continue to improve and become more
useful for guiding maintenance and R&R activities, as described in Section 8.5.4.
8.5.3 Economic Life Model Improvements
The results from the economic life model are only as accurate as the inputs. Therefore, after
implementing the model, improving the accuracy of the information on which the model is built is the
focus for future efforts. The data input improvements can be organized into the following three groups of
information:
• Need for additional infrastructure information: The economic life model is based on data describing
the current conditions of stormwater infrastructure. The completeness and accuracy of these input
data (see Section 8.5.1) are crucial to the usefulness of the economic life-cycle analysis results.
• Cost assumptions: Continually verifying and customizing cost information for spot repairs costs (as a
function of depth of bury and pipe location), as well as social and environmental costs (i.e., impact of
a pipe failure on traffic) will ensure that the model calculates accurate intervention timings and that
cost projections represent an accurate spending program for the Storm Drainage Utility.
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• Failure assumptions: The probability of failure used in the economic life model presumes that the
City’s segments will fail in a manner described by a specific type of statistical distribution. Such a
statistical distribution can be customizable to meet a variety of conditions that influence failure (i.e.
asset age, pipe material); however, verifying the parameters used to describe the distribution will
require information on actual failure rates. With this information, the probability function can be
customized specifically to the Storm Drainage Utility and will better predict optimal intervention
timing.
In addition to updates to the pipe model, the model could be expanded to include catch basins and
manholes. Including catch basins and manholes in the economic life model will allow M&O staff to
identify those facilities with the highest potential cost of failure and that represent the greatest risk to
the City, and to better identify which catch basins and manholes are nearing the end of their useful life,
allowing M&O staff to better focus their maintenance activities. The information provided by the model
(through maintenance records) may help to confirm to Ecology that less frequent catch basin
inspections, cleaning and maintenance are sufficient, as compared to the biennial inspections required
by the NPDES Permit.
Generally, the approach and calculations used by the model apply equally to catch basins and manholes.
However, additional work, as described in the SRS, must be performed to determine the values for some
model parameters.
8.5.4 Maintenance and R&R Prioritization
Once the data inventory is complete, and the economic life model is implemented, the City can use the
model to estimate and evaluate the risk cost associated with each of its drainage pipe segments, catch
basins, and manholes. The model can be used to evaluate the condition of this infrastructure and
identify predictive maintenance and R&R needs.
Maintenance activities can be prioritized to focus on the assets for which the City is carrying the majority
of its risk. The risk provides justification for focused conditional assessment activities (e.g., CCTV
inspections) as part of a risk-based maintenance strategy. In general, risk-based maintenance strategies
recommend predictive maintenance and risk mitigation practices for high-risk assets; preventive and
routine maintenance for medium-risk assets; and routine maintenance, less-frequent, or even a “run-to-
failure” approach for low risk assets.
R&R budget and long-term rate forecasting can be developed, and a business case validation can be
made for each segment intervention. The model results can be sorted in multiple ways to develop
specific R&R needs such as a prioritized intervention list. The model’s benefit/cost ratio can be used to
identify interventions that would result in the greatest savings for the lowest price. As multiple segments
become due for intervention, the benefit/cost ratio can be used as a means to prioritize where finite
R&R funds are spent. As the benefit/cost ratio tends to favor segments that are the most likely to fail
(i.e., old segments with poor condition scores) and relatively inexpensive to intervene (e.g., short, small-
diameter segments), using cost of failure for segments due for intervention would provide an alternative
project priority list. Model results will identify intervention timing for all segments, but high-cost of failure
segments (e.g., larger pipes that are expensive to replace) could potentially show lower on an R&R
priority list using only benefit/cost.
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8.5.5 M&O Activities
In addition to the identified staffing and equipment needs described in Section 8.4, the following M&O
opportunities are available to improve existing activities:
• M&O staff are integral to the continual update to the system inventory described in Section 8.5.1. As
they perform maintenance activities they should continue to update infrastructure attributes stored
in Cartegraph.
• The City should continue the implementation of the NASSCO PACP MACP certified inspection
programs to allow integration of inspection and condition assessment results with Cartegraph. The
City should provide staff training to ensure assessment consistency including documentation using
defined criteria such as leaks/cracks observed, cleanliness, and other specific measures.
• All M&O repair projects should be constructed to established City engineering standards to ensure
best practices are being used. It is also recommended that the City develop a more formal
procedure for tracking M&O repair projects to ensure that as-built and Cartegraph records are
updated when projects are completed.
Recommendations for Additional Activities 8.6
The following sections present recommendations for additional activities for the Storm Drainage Utility.
Section 8.6 is divided into the following three sub-sections:
• Section 8.6.1 prescribes an easement review and acquisition program.
• Section 8.6.2 presents a recommendation that a risk assessment be conducted to evaluate the
vulnerability of Storm Drainage Utility assets.
• Section 8.6.3 presents recommendations for developing and incorporating sustainability goals with
utility activities.
8.6.1 Develop Easement Review and Acquisition Program
As the City implements this Drainage Plan, it needs to develop a process to ensure that it can meet the
LOS goal related to having access to City-owned facilities for M&O activities. While developing this plan, a
number of drainage issues were evaluated in the West Hill area, which was annexed from King County in
2008. The City’s drainage network in this area consists mostly of ditches and culverts. Some of these
are located outside of the right-of-way and cross private property without easements. As the data
inventory for the annexation areas is completed, the City will likely identify more potential easement
gaps. The City should develop a program to identify where easements are needed, and work with the
property owners to obtain easements.
8.6.2 Risk Assessment/Asset Vulnerability Analysis
Asset life-cycle analyses described in Section 8.5 examine risk to individual assets, which focus on small-
scale modes of failure (e.g., pipe breakage). However, Storm Drainage Utility assets are also vulnerable
to failure caused by wide-scale events such as natural disasters. A utility must also consider these risks
and take action to mitigate those risks where feasible. Such actions could be in the form of capital
improvements or utility programs.
The City should conduct a vulnerability analysis on the entire storm drainage system to examine the
potential for natural disasters such as flood, erosion, earthquake, or volcanic activity to cause system
failures. The associated probabilities of failure should be weighed with the consequences of failure to
determine if action is necessary and to identify appropriate mitigation measures. The proposed
mitigation measures should be documented in a plan and should be weighed alongside other capital
commitments for prioritization.
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8.6.3 Incorporate Sustainability
As the City implements this Drainage Plan, a need to prioritize projects and activities in a repeatable,
defensible manner will emerge. This process will need to have a standard method for evaluating all of
the LOS goals listed in Chapter 3, including goals related to sustainability.
Under the “protection of the environment” policy category in Table 3-1, the City has a policy to evaluate
Storm Drainage Utility activities to emphasize sustainability. The goal associated with this policy is to
identify specific areas to measure sustainability by examining how Storm Drainage Utility operations
affect energy resources, natural resources, and the community. The examples provided include items
such as weighing energy consumption impacts and costs during capital project development, selecting
biodegradable and locally produced cleaning and maintenance products, protecting or restoring native
soils and vegetation, structuring maintenance and other activities to minimize vehicle miles traveled,
and improving communication with stakeholders and the public. However, quantifying these goals and
effectively using information in decision making can be challenging.
Traditionally, public works projects are evaluated on initial capital investments and the annual costs of
M&O. A project’s environmental and community benefits and costs are typically discussed, but in many
instances the “hard” costs of capital and M&O are the overriding decision criteria. By more rigorously
including environmental and community benefits and costs in the decision process through sustainability
analyses, projects and utility operations can be evaluated in a manner that truly considers the full cost of
ownership. The following actions are recommended to develop and incorporate sustainability goals
within the Storm Drainage Utility.
Define Sustainability. Sustainability means different things to different people and organizations. The
United Nations World Commission on Environment and Development defined sustainable development
as “development that meets the needs of the present without compromising the ability of future
generations to meet their own needs.” Sustainable Seattle defines sustainability as the long-term health
and vitality of a region, including the cultural, economic, environmental, and social aspects as one whole.
Sustainability is often described as the careful and efficient use of natural, cultural, and financial
resources in ways that improve the quality of life for communities without depleting the environment. To
develop specific and actionable goals around sustainability, it is important for the Storm Drainage Utility
to develop its own definition of the concept.
Develop Sustainability Goals. The challenge for the decision maker is to take a general definition and
create discernible criteria that can be described and compared in a supportable way and used to make
defensible decisions. The City should strive to provide specific metrics around the specific sustainability
goals it would like to accomplish (e.g., for a goal of minimizing vehicle miles traveled, a specific metric
would be to reduce vehicle travel by 20 percent; or for a goal to protect native vegetation, a specific
metric would be retain and protect 40–60 percent of open space on new development sites).
Establish a Method of Evaluation. Once LOS metrics are defined, projects and activities can be
evaluated, compared, and prioritized. The City should develop or adopt a consistent and repeatable
method for evaluating projects and activities. A recommended approach would be to develop an
evaluation process that builds upon the concept of life-cycle costing by also including consideration and
quantification, in economic terms, of environmental and community impacts to determine the full cost of
a specific alternative. Such a quantitative approach considers environmental and community risks and
costs, which provides economic support for a decision at the management and policy level.
Other evaluation options could include a sustainability checklist, measuring a project or operations
capacity to meet individual sustainability goals, or tools such as the Institute for Sustainable
Infrastructure Envision rating system, which is a planning and design framework for measuring and
incorporating sustainability into infrastructure projects, or SalmonSafe, which assesses and certifies
projects for water quality protection. These types of tools look beyond monetized costs and benefits to
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provide both quantitative and qualitative assessments of the environmental and community impacts of
infrastructure projects. Other sustainability tools and project certification or evaluation processes are
also available, or the City could develop its own evaluation process specific to its sustainability goals and
the Storm Drainage Utility’s projects and operations.
The above-described actions provide a mechanism for incorporating sustainability into Storm Drainage
Utility projects and activities. Investigations are conducted to evaluate projects and activities with
respect to LOS criteria and metrics. Gaps are identified and alternatives are developed for reducing or
eliminating those gaps. Alternatives can be evaluated, compared, and ranked through a life-cycle
present value benefit/cost analysis, considering not only budgetary impacts but also risks,
environmental considerations, and societal costs and benefits. By applying a repeatable, defensible
process that includes environmental and community factors, the City can prioritize projects and activities
based on both full costs of ownership and a project’s ability to meet or exceed LOS sustainability
requirements.
2016 2017 2018 2019 2020 2021 2022 2035
1. West Main Street Pump Station Upgrade
2. 37th and I Streets NW Storm Improvements
3. Hillside Drainage Assessment
4A. 30th Street NE Area Flooding, Phase 2
4B. 30th Street NE Area Flooding, Phase 3
5A. West Hills Drainage Improvements at S 330th St. & 46th Pl. S
5B. West Hills Drainage Improvements near S 314th St. & 54th Ave. S
6. North Airport Area Improvements
7. D St. SE Storm Improvements
9. Comprehensive Storm Drainage Plan update
11. Storm Drainage Infrastructure Repair & Replacement
12. Street Utility Improvements
Q1Q2Q3Q4
Pipe 1011-C1086_1011-C1137
Pipe 1011-C1452_1011-C1453
Culvert 1111-C1469_1111-C1470
Catch basin 1012-C688
Pipe 1012-C690_1012-C689
Pipe 1010-C3_1010-C29
Pipe 1010-B220_1010-B221
WL-Mill-01,02,03,04. Mill Creek Profile
WL-Pond-17thSt. 17th and A Streets SE
WL-Pond-21stSt. 21st and D Streets SE
WL-Pond-RiverN. Riverwalk Dr. SE and U St. SE
WL-Pond-LakeS1, -LakeS2, -LakeEP & -Mill
Detailed 6-year CIP Time Frame
Annual inspections of City-approved facilities constructed under
the terms of permit
Adopt 2012 Ecology Manual or equivalent manual
Measure effectiveness of public outreach
NP
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S
P
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r
m
i
t
R
e
i
s
s
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Establish specific sustainability goals and standards
Continue system inventory
Conduct new economic life-cycle analyses
Implement economic life-model using Cartegraph data
Implement additional M&O activities
Develop easement review and acquisition program
Remaining 20-year CIP Summary
Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4
IMPLEMENTATION PLAN ACTIVITIES TIMELINE
City of Auburn Comprehensive Storm Drainage Plan
Additional Activities (Section 8.5)
NPDES Compliance (Section 8.3)
Monitoring (Section 8.2)
CIP (Section 8.1)
Data feed
Activity (may start before 2016)
K E Y
Risk assessment/asset vulnerability analysis
Complete one inspection of each catch basin
Review & update operations, maintenance & inspections standards
8. 23rd St. SE Drainage Improvements
Phase 1 Phase 2
Pipe 809-C113_809-C112
Pipe 909-C122_909-C121
Pipe 810-C701_809-C18
Pipe 810-C15_810-C241
Pipe 810-C698_810-C16
Complete field screening for 40% of storm drainage system
Complete field screening for 12% of storm drainage system annually
Revise ACC to reflect IDDE changes
Compile and submit a summary of LID review and revision process
Post SWMP documents to website annually
Review, revise & adopt local development codes, standards, &
the policies to require LID
Phase 1 Phase 2
Timing dependent on project to
be implemented in 2015
10. Vegetative Waste Sorting Facility
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Chapter 9
Finance
The objective of the financial plan is to identify the total cost of providing storm drainage service and to
provide a financial program that allows the Storm Drainage Utility to remain financially viable during
execution of the identified CIP. This viability analysis considers the historical financial condition of the
Storm Drainage Utility, the sufficiency of Storm Drainage U tility revenues to meet current and future
financial and policy obligations, and the financial impact of executing the CIP. Furthermore, the financial
plan provides a review of the Storm Drainage Utility’s rate structure with respect to rate adequacy and
customer affordability.
Past Financial Performance 9.1
This section includes a historical (2008–13) summary of financial performance as reported by the City of
Auburn on the statement of revenues, expenses, and changes in net position and the statement of net
position, specific to the Storm Drainage Utility.
9.1.1 Statement of Revenues, Expenses, and Changes in Net Position
Table 9-1 shows a consolidated statement of revenues, expenses, and changes in net position for the
period 2008–13.
Operating income (including depreciation expense) was positive in 2010, 2011, and 2013. Operating
income grew from an operating loss of $29,000 in 2008 to an operating income of $863,000 in 2013.
Furthermore, from 2008 to 2013 operating revenues grew by over $3 million, which represents a 59
percent increase. This increase outpaced operating expenses by 18 percent. Depreciation is a non-cash
expenditure, so even though operating income has been negative in some years, operating cash flow
was positive every year.
A few key financial ratios are discussed below. Unless otherwise noted, the stated benchmarks are
based on industry standards.
• M&O coverage ratio (operating revenues divided by operating expenses):
− Benchmark: A ratio of 1.0 or higher is a desirable result, indicative of sufficient revenues to
meet cash operating expenses as well as to cover depreciation expense.
− Results: From 2008 through 2013, the ratio has ranged from 0.9 to 1.1, which is a positive
result overall.
• Operating ratio (total operating expenses excluding depreciation divided by total operating
revenues):
− Benchmark: A ratio greater than 90 percent indicates that there is little room for new debt
service and capital replacement without additional rate increases. A ratio greater than 100
percent indicates that cash operating expenses exceed operating revenues and is indicative of
an unsustainable financial condition.
− Results: From 2008 through 2013, the ratio has ranged from 71 percent to 86 percent, which is
a positive result in every year.
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• Debt service coverage ratio (operating and interest revenues less M&O expenses excluding
depreciation, divided by annual debt service):
− Benchmark: Revenue bonds typically have a legal minimum coverage requirement of 1.25.
− Results: From 2008 through 2013, the coverage ratio has ranged from 3.2 to 10.8, each year
well above the benchmark. The Storm Drainage Utility has used revenue bond debt only in this
historical period; state loans have not been used.
Table 9-1. Statement of Revenues, Expenses and Changes in Fund Net Position
9.1.2 Statement of Net Position
Table 9-2 shows the consolidated statement of net position for the period 2008–13.
Table 9-2. Statement of Net Position
Table 9-1. Statement of Revenues, Expenses and Changes in Fund Net Position
200820092010201120122013
OPERATING REVENUES:
Charges for services 5,159,389$ 6,000,761$ 6,441,726$ 6,938,375$ 7,479,580$ 8,184,303$
Other Operating Revenue 997 102 272 - - -
Total Operating Revenues 5,160,386 6,000,863 6,441,998 6,938,375 7,479,580 8,184,303
OPERATING EXPENSES:
Operations and Maintenance 1,551,406 2,186,976 1,727,711 1,923,604 3,123,618 2,113,050
Administration 1,979,083 2,298,330 2,428,345 2,746,980 2,641,157 2,919,570
Depreciation/Amortization 1,241,980 1,087,555 1,088,529 1,278,402 1,456,342 1,529,701
Other Operating Expenses 417,130 535,284 585,743 646,871 704,221 759,178
Total Operating Expenses 5,189,599 6,108,145 5,830,328 6,595,857 7,925,338 7,321,499
OPERATING INCOME(LOSS)(29,213) (107,282) 611,670 342,518 (445,758) 862,804
NON OPERATING REVENUE (EXPENSES)
Interest Revenue 295,975 60,479 47,875 20,865 18,299 20,944
Other Non-Operating Revenue 77,300 1,047,703 172,791 511,617 803,570 356,010
Interest Expense (37,224) (25,120) (271,964) (133,448) (99,496) (351,913)
Other Non-Operating Expenses - (1,141,807) (892,089) (22,716) (895) (53,055)
Total Non-Operating Revenue (expenses)336,051 (58,745) (943,387) 376,318 721,478 (28,014)
INCOME(LOSS) BEFORE CONTRIBUTIONS AND
TRANSFERS 306,838 (166,027) (331,717) 718,836 275,720 834,790
CAPITAL CONTRIBUTIONS 920,944 750,141 1,727,140 6,193,834 1,966,564 1,033,128
TRANSFERS IN - - - - -
TRANSFERS OUT (159,100) (138,000) (59,580) (96,800) (50,000) (124,000)
Changes in Net Position 1,068,682 446,114 1,335,843 6,815,870 2,192,284 1,743,918
Net Position, January 1, as Previously Reported 38,105,695 39,174,377 39,620,491 40,956,334 47,772,204 49,964,488
Change in Accounting Principle (21,471)
Net Position, January 1, as Restated - - - - - 49,943,017
Net Position, December 31 39,174,377 39,620,491 40,956,334 47,772,204 49,964,488 51,686,935
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Table 9-2. Statement of Net Position
200820092010201120122013
ASSETS
Current Assets
Cash and Cash Equivalents 6,328,751$ 3,902,561$ 2,783,583$ 6,693,599$ 7,954,723$ 8,894,035$
Investments 1,052,500 1,017,813 2,510,325 - - 997,290
Restricted Cash
Bond Payments 442,329 95,746 348,279 357,864 473,264 829,406
Customer Deposits - - - - - -
Other 479,991 425,608 4,451,444 2,128,832 1,413,688 5,726,428
Customer Accounts 720,823 733,644 795,710 855,486 923,999 931,782
Other Receivables 4,521 4,521 4,627 - - 955
Due From Other Governmental Units - 1,019,200 90,608 444,779 705,853 222,677
Inventories 8,764 11,831 7,880 7,299 5,533 7,566
Total Current Assets 9,037,679 7,210,924 10,992,456 10,487,859 11,477,060 17,610,139
Non Current Assets
Long Term Contracts and Notes - - - - - -
Capital Assets
Land 5,686,254 5,686,254 5,686,254 5,686,254 5,686,254 5,686,254
Buildings and Equipment 201,255 297,853 201,254 201,254 201,254 219,214
Improvements Other Than Buildings 38,271,397 38,697,313 44,739,930 50,815,888 55,581,417 56,162,320
Construction in Progress 808,357 4,027,852 755,866 3,403,168 1,083,761 2,922,064
Less: Accumulated Depreciation (12,887,006) (13,974,561) (15,057,455) (16,335,857) (17,792,199) (19,321,900)
Total Capital Assets ( Net of A/D)32,080,257 34,734,711 36,325,849 43,770,707 44,760,487 45,667,952
Total Non-Current Assets 32,080,257 34,734,711 36,325,849 43,770,707 44,760,487 45,667,952
Total Assets 41,117,936 41,945,635 47,318,305 54,258,566 56,237,547 63,278,091
LIABILITIES
Current Liabilities
Current Payables 218,480 931,383 333,818 522,001 393,826 657,995
Current Deposits - - - - - -
Loans Payable-Current - - - - - -
Employee Leave Benefits-Current 92,777 143,232 122,244 136,131 149,928 168,396
Revenue Bonds Payable-Current 398,500 71,500 75,400 79,300 198,705 405,186
General Obligation Bonds Payable-Current - - - - -
Accrued Interest 43,829 24,246 272,879 278,564 274,559 424,221
Deposits - - - - - -
Total Current Liabilities 753,586 1,170,361 804,341 1,015,996 1,017,018 1,655,798
Non Current Liabilities
Unearned Revenue 597,204 597,204 597,204 597,204 597,204 597,204
Employee Leave Benefits 11,443 47,338 63,911 61,793 52,017 50,214
Loans Payable - - - - - -
Revenue Bonds Payable 581,326 510,241 4,896,515 4,811,369 4,606,820 9,287,940
General Obligation Bonds Payable - - - - - -
Total Non Current Liabilities 1,189,973 1,154,783 5,557,630 5,470,366 5,256,041 9,935,358
Total Liabilities 1,943,559 2,325,144 6,361,971 6,486,362 6,273,059 11,591,156
NET ASSETS
Invested In Capital Assets, Net of Related Debt 31,100,432 34,152,970 34,942,276 40,145,011 40,504,264 35,974,826
Restricted for:
Debt Service 179,991 221,354 800,751 810,336 925,485 1,605,820
Capital Projects - - - - - 4,537,224
Rate Stabilization - 300,000 410,629 411,386 412,165 412,791
Unrestricted 7,893,954 4,946,167 4,802,678 6,405,471 8,122,574 9,156,274
Total Net Position 39,174,377$ 39,620,491$ 40,956,334$ 47,772,204$ 49,964,488$ 51,686,935$
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This statement shows that the City’s net storm drainage assets, which measures the cost of assets (net
of depreciation) remaining after liabilities are paid, increased from $39.2 million to $51.7 million over
the 2008–13 time period; this represents a 32 percent increase. This includes an overall increase in the
current assets from $9 million in 2008 to $17.6 million in 2013, which represents a 95 percent
increase. Cash and cash equivalents have increased by $2.6 million over this same period.
Non-current assets, which represent assets required for use or consumption beyond 1 year, have seen a
42 percent increase, from $32.1 million in 2008 to $45.7 million in 2013. A more detailed look at the
change in capital assets over this period reveals that improvements other than buildings have increased
by nearly $18 million, which represents a 47 percent increase. Construction in progress has increased
by $2.1 million during this same time period.
A few key financial ratios are discussed below. Unless otherwise noted, the stated benchmarks are
based on industry standards.
Liquidity
• Current ratio (unrestricted current assets divided by current liabilities):
− Benchmark: A ratio of 2.0 or higher is considered good in terms of healthy liquidity. The current
ratio is a measure of short-term financial strength and answers the question: Are current assets
able to cover expected current liabilities in the coming year?
− Results: From 2008 through 2013, the current ratio has ranged from 4.2 to 9.8, well above the
recommended benchmark in each year.
Efficiency
• Accounts receivable collection period (customer receivables on balance sheet x 365 days then
divided by annual sales):
− Benchmark: Generally, less than 30 days is considered very good.
− Results: Decreased from 51 days in 2008 to 42 days in 2013. This is a positive trend.
Capital Structure
• Debt to net capital assets ratio (total outstanding debt divided by capital assets net of accumulated
depreciation):
− Benchmark: For utilities, having a capital structure of at least 40 percent equity and less than
60 percent debt is considered a healthy capital structure, with adequate future borrowing
capacity and a manageable debt service burden. The City’s capital structure policy is even more
conservative: 50 percent debt and 50 percent equity.
− Results: Increased from 3 percent debt in 2008 to 21 percent debt in 2013. The ratio increased
from 11 percent in 2012 to 21 percent in 2013 resulting from the 2013 CIP Revenue Bond.
Despite this increase, this ratio is still well within both the industry and City benchmarks for
maximum outstanding debt.
9.1.3 Outstanding Debt Principal
Table 9-3 outlines the City’s outstanding debt principal as of the end of 2013.
The Storm Drainage Utility has three outstanding revenue bonds. The total outstanding principal on
these bonds is $9.2 million.
Table 9-3. Outstanding Debt
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Available Capital Funding Resources 9.2
Feasible long-term capital funding strategies should be defined to ensure that adequate resources are
available to fund the CIP identified in this Plan. In addition to the Storm Drainage Utility’s resources such
as accumulated cash reserves, capital revenues, bond proceeds, and SDCs, capital needs can also be
met from outside sources such as grants, low-interest loans, and other debt financing. The following is a
summary of internal Storm Drainage Utility resources, government programs and resources, and public
debt financing.
9.2.1 Internal Utility Resources
Storm Drainage Utility resources appropriate for funding capital needs include accumulated cash in the
capital “account,” bond proceeds, and capital revenues, such as SDCs. Capital-related revenues are
discussed below.
9.2.1.1 Utility Funds and Cash Reserves
User charges (rates) paid by the Storm Drainage Utility’s customers are the primary funding source for all
Storm Drainage Utility activities. The rates cover total annual costs associated with operating and
maintaining the system. Rates can pay for capital improvement projects in two ways: either paying for
debt service or directly paying for capital projects. Although funding the capital costs directly through
rates does not result in the additional interest expense associated with issuing debt, this approach can
cause large and/or volatile rate increases.
9.2.1.2 System Development Charges
An SDC, as provided for by RCW 35.92.025, refers to a one-time charge imposed on new customers as a
condition of connection to the Storm Drainage Utility system. The purpose of the SDC is twofold: (1) to
promote equity between new and existing customers, and (2) to provide a source of revenue to fund
capital projects. Equity is served by providing a vehicle for new customers to share the cost of
infrastructure investment. SDC revenues provide a source of cash flow used to support Storm Drainage
Utility capital needs; revenue can be used only to fund Storm Drainage Utility capital projects or to pay
debt service incurred to finance those projects.
In the absence of an SDC, growth-related capital costs would be borne in large part by existing
customers. In addition, the net investment in the Storm Drainage Utility already collected from existing
customers, whether through rates, charges, and/or assessments, would be diluted by the addition of
new customers, effectively subsidizing new customers with prior customers’ payments. To establish
equity, an SDC should recover a proportionate share of the existing and future infrastructure costs from
a new customer. From a financial perspective, a new customer should become financially equivalent to
an existing customer by paying the SDC.
Table 9-4 summarizes the City’s current SDC schedule.
Table 9-4. Current System Development Charge Schedule
Table 9-3. Outstanding Debt
Debt Description Principal
Outstanding Maturity Year
2005 Refinance Revenue Bond 265,200$ 2016
2010 CIP Revenue Bonds 4,255,888$ 2030
2013 CIP Revenue Bonds 4,653,600$ 2032
Total 9,174,688$
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9.2.1.3 Local Facilities Charge
While an SDC is the manner by which new customers pay their share of general facilities costs, local
facilities funding is used to pay the cost of local facilities that connect each property to the system
infrastructure. Local facilities funding is often overlooked in a rate forecast because it is funded up front
either by connecting customers or developers, or through an assessment to properties—but never from
rates. Although these funding mechanisms do not provide a capital revenue source toward funding CIP
costs, a discussion of these charges is included in this chapter because of their impact on new
customers.
Several mechanisms can be considered toward funding local facilities. One of the following scenarios
typically occurs:
• The Storm Drainage Utility charges a connection fee based on the cost of the local facilities (under
the same authority as the SDC)
• A developer funds extension of the system to its development and turns those facilities over to the
Storm Drainage Utility (contributed capital)
• A local assessment is set up called a utility local improvement district (ULID), which collects tax
revenue from benefited properties
A local facilities charge (LFC) is a variation of the SDC authorized through RCW 35.92.025. It is a city-
imposed charge to recover the cost related to service extension to local properties. Often called a front-
footage charge and imposed on the basis of footage of main “fronting” a particular property, it is usually
implemented as a reimbursement mechanism to a city for the cost of a local facility that directly serves a
property. It is a form of connection charge and, as such, can accumulate up to 10 years of interest. It
typically applies in instances where no developer-installed facilities are needed through developer
extension because of the prior existence of available mains already serving the developing property.
The developer extension is a requirement that a developer install onsite and sometimes offsite
improvements as a condition of extending service. These are in addition to the SDC required and must
be built to city standards. The city is authorized to enter into developer extension agreements under RCW
35.91.020. Part of the agreement between the city and the developer for the developer to extend
service might include a latecomer agreement, resulting in a latecomer charge to new connections to the
developer extension.
Latecomer charges are a variation of developer extensions whereby a new customer connecting to a
developer-installed improvement makes a payment to the city based on their share of the developers
cost (RCW 35.91.020). The city passes this on to the developer that installed the facilities. This is part of
the developer extension process, and defines the allocation of costs and records latecomer obligations
on the title of affected properties. No interest is allowed, and the reimbursement agreement is in effect
for a period of 20 years, unless a longer duration is approved by the city.
ULID is another mechanism for funding infrastructure that assesses benefited properties based on the
special benefit received by the construction of specific facilities (RCW 35.43.042). Most often used for
local facilities, some ULIDs also recover related general facilities costs. Substantial legal and procedural
requirements can make this process relatively expensive, and there are mechanisms by which a ULID
can be rejected by a majority of property ownership within the assessment district boundary. These
Table 9-4. Current System Development Charge Schedule
Type SDC
Single Family Residences & Duplexes (on Individual Parcels)$1,162 per Parcel
Other Parcels $1,162 per Equivalent Service Unit
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instruments are not often used to finance storm drainage facilities because it has proved difficult to
demonstrate required special benefit to properties to be assessed.
9.2.2 Government Programs and Resources
This section outlines government programs and resources potentially available for financing.
9.2.2.1 Grants and Low-Cost Loans Overview
Historically, federal and state grant programs were available to local utilities for capital funding
assistance. However, these assistance programs have been mostly eliminated, substantially reduced in
scope and amount, or replaced by loan programs. Remaining miscellaneous grant programs are
generally lightly funded and heavily subscribed. Nonetheless, even the benefit of low-interest loans
makes the effort of applying worthwhile. Grants and low-cost loans for Washington State utilities are
available from various Washington State departments. Several grant and loan programs for which the
City might be eligible are described in greater detail below.
9.2.2.2 Department of Commerce
A September 2014 document from the Washington State Department of Commerce summarizes various
loan and grant programs available for storm drainage projects (“Summary of Some Grant and Loan
Programs for Drinking Water and Wastewater Projects,” found at
http://www.commerce.wa.gov/Documents/9-2-14_multi-program_funding_program_summary.pdf.
A few of those programs are described below.
Community Economic Revitalization Board (CERB). CERB, a division of the Washington State
Department of Commerce, offers primarily low-cost loans; grants are made available only to the extent
that a loan is not reasonably possible. The CERB targets public facility funding for economically
disadvantaged communities, specifically for job creation and retention. Priority criteria include
unemployment rates, number of jobs created and/or retained, wage rates, projected private investment,
and estimated state and local revenues generated by the project. According to its website, “CERB funds
a variety of projects that create jobs including (but not limited to) domestic and industrial water, storm
and sewer water projects, telecommunications and port facilities.” Eligible applicants include cities,
towns, port districts, special purpose districts, federally recognized Indian tribes, and municipal
corporations.
Funding details for the 2013–15 Program are as follows per the Washington Commerce Department
website: “$9 million was appropriated to CERB for the 2013–15 Biennium. By state law, CERB must
award 75 percent of this funding to projects in rural counties. The Board has also allocated $2,182,500
to be available for construction and planning grants on a first-come, first-served basis.”
Program Funding Limitations
Committed Private Sector Partner
Construction
• $2 million per project load award limit
• Up to $300,000 or 50% of total award, whichever is less, may be grant funds.
• 20% cash match required (minimum, percent of total project cost)
Prospective Development
Construction
Available to rural communities only.
• $2 million per project load award limit
• Up to $300,000 or 50% of total award, whichever is less, may be grant funds.
• 20% cash match required (minimum, percent of total project cost)
Planning/Economic Feasibility
Studies
• $50,000 grant per project award limit
• 25% cash match required (minimum, percent of total project cost)
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Further details are available at:
• http://www.commerce.wa.gov/commissions/CommunityEconomicRevitalizationBoard/
• http://www.commerce.wa.gov/Documents/2013-15_Policies.pdf
• http://www.commerce.wa.gov/commissions/CommunityEconomicRevitalizationBoard/Pages/CERB-
Traditional-Programs.aspx
Public Works Board (PWB) Financial Assistance. The PWB’s goal is to provide community access to
financial and technical resources that help sustain local infrastructure. Cities, towns, counties, and
special-purpose districts are eligible to receive financial assistance for qualifying projects. When funding
is available, the following tools are accessible:
• Construction Loan Program (http://www.pwb.wa.gov/financial-
assistance/Construction/Pages/default.aspx):
− Funding cycle: Per the PWB website, the governor’s proposed 2015–17 budget offers $69.7
million for 19 projects.
− Program description: Low-interest loans for local governments to finance public infrastructure
construction and rehabilitation. Eligible projects must improve public health and safety, respond
to environmental issues, promote economic development, or upgrade system performance.
− Terms: For non-distressed communities, a term of 5 years or less has an interest rate of 1.28
percent and a term from 6 to 20 years has an interest rate of 2.55 percent.
• Pre-Construction Loan Program (http://www.pwb.wa.gov/financial-assistance/Pre-
Construction/Pages/default.aspx):
− Funding cycle: No funding has been allocated to the pre-construction loan program for the
2013–15 biennium.
− Program description: Local governments may apply for low-interest loans to finance pre-
construction activities to prepare a project for construction.
− Terms: Terms are limited to a 5-year repayment period (the loan term may be converted to 20
years once the project has secured construction funding) with a 1 percent interest rate.
• Emergency Loan Program (http://www.pwb.wa.gov/financial-assistance/Emergency-
Loan/Pages/default.aspx):
− Funding cycle: No funding has been allocated to the Emergency Loan Program for the 2013–15
biennium.
− Program description: The Emergency Loan Program provides funding to address public-works
emergencies, thereby helping to provide immediate restoration of critical public-works services
and facilities.
− Terms: Funds are limited to $500,000 per jurisdiction per biennium, and come with a 20-year
term (or the life of the project), and a 3 percent interest rate. No local match is required.
• Energy and Water Efficiency (EWE) Loan Program (http://www.pwb.wa.gov/financial-
assistance/Energy-Water/Pages/default.aspx):
− Funding cycle: No funding has been allocated to the EWE Loan Program for the 2013–15
biennium.
− Program description: The EWE Loan Program is designed to encourage energy, water, and
efficiency upgrades to existing infrastructure by providing low-cost loans.
− Terms: The maximum loan amount is $1 million. The interest rate is dependent upon the term of
the loan. Loans less than 5 years receive a 0.50 percent interest rate. Loans between 5 and 10
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years receive a 1 percent interest rate. Loans between 11 and 20 years receive a 1.50 percent
interest rate.
• Further general resources are available at:
− http://www.pwb.wa.gov/financial-assistance/Pages/default.aspx
− http://www.pwb.wa.gov/Documents/FINAL-MASTER-GUIDELINES.pdf
− http://www.commerce.wa.gov/Documents/9-2-14_multi-
program_funding_program_summary.pdf
9.2.2.3 Department of Ecology: Integrated Water Quality Funding Program
This year, Ecology received 227 applications requesting more than $352 million in financial assistance.
Ecology is proposing grant and loan funding for 165 projects totaling approximately $229 million.
• State Water Pollution Control Revolving Fund and Centennial Clean Water Program
− Design projects associated with publicly owned wastewater and stormwater facilities. The
integrated program also funds planning and implementation of nonpoint source pollution control
activities. Terms for State fiscal year 2016 include either 2.4 percent interest for 6–20-year
term or 1.2 percent for 5-year term loans. Forgivable loan principal terms are available for
distressed communities.
− Further general resources are available at:
http://www.ecy.wa.gov/programs/wq/funding/cycles/FY2016/index.html
• Stormwater Financial Assistance Program (SFAP)
− Stormwater grant assistance is available for projects not required by permit. The SFAP is
available for both cities and counties. The maximum grant award per jurisdiction is $250,000.
− Further general resources are available at:
• http://www.ecy.wa.gov/programs/wq/funding/FundPrgms/OthPrgms/StWa12a/FY12aStW
a.html
• http://www.ecy.wa.gov/programs/wq/funding/Training/FY2016/SFY16ApplicantStormwate
rSession.pdf
9.2.3 Public Debt Financing
This section describes potentially available public debt financing tools.
9.2.3.1 General Obligation Bonds
General obligation (GO) bonds are bonds secured by the full faith and credit of the issuing agency,
committing all available tax and revenue resources to debt repayment. With this high level of
commitment, GO bonds have relatively low interest rates and few financial restrictions. However, the
authority to issue GO bonds is restricted in terms of the amount and use of the funds, as defined by
Washington constitution and statute. Specifically, the amount of debt that can be issued is linked to
assessed valuation.
RCW 39.36.020 states:
(ii) Counties, cities, and towns are limited to an indebtedness amount not exceeding one
and one-half percent of the value of the taxable property in such counties, cities, or
towns without the assent of three-fifths of the voters therein voting at an election held for
that purpose.
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(b) In cases requiring such assent counties, cities, towns, and public hospital districts are
limited to a total indebtedness of two and one-half percent of the value of the taxable
property therein.
While bonding capacity can limit availability of GO bonds for utility purposes, these can sometimes play a
valuable role in project financing. A rate savings may be realized through two avenues: the lower interest
rate and related bond costs, and the extension of repayment obligation to all tax-paying properties (not
just developed properties) through the authorization of an ad valorem property tax levy.
9.2.3.2 Revenue Bonds
Revenue bonds are commonly used to fund utility capital improvements. The debt is secured by the
revenues of the issuing utility and the debt obligation does not extend to the city’s other revenue
sources. With this limited commitment, revenue bonds typically bear higher interest rates than GO bonds
and also require security conditions related to the maintenance of dedicated reserves (a bond reserve)
and financial performance (added bond debt service coverage). The City agrees to satisfy these
requirements by ordinance as a condition of bond sale.
Revenue bonds can be issued in Washington without a public vote. There is no bonding limit, except
perhaps the practical limit of the utility’s ability to generate sufficient revenue to repay the debt and
provide coverage. In some cases, poor credit might make issuing bonds problematic.
9.2.4 Capital Resource Funding Summary
An ideal funding strategy would include the use of grants and low-cost loans when debt issuance is
required. However, these resources are very limited and competitive in nature and do not provide a
reliable source of funding for planning purposes. It is recommended that the City pursue these funding
avenues but assume bond financing to meet needs above the Storm Drainage Utility’s available cash
resources. GO bonds may be useful for special circumstances, but because bonding capacity limits are
most often reserved for other City (non-Storm Drainage Utility) purposes, revenue bonds are a more
secure financing mechanism for Storm Drainage Utility needs. The capital financing strategy developed
to fund the updated CIP follows the funding priority below:
1. Available grant funds and/or developer contributions
2. Interest earnings on allocated fund balances
3. Other miscellaneous capital resources
4. Annual revenue collections from SDCs
5. Annual transfers of rate-funded capital or excess cash (above minimum balance targets) from
operating accounts
6. Accumulated capital cash reserves
7. Revenue bond financing
Financial Plan 9.3
The Storm Drainage Utility is an enterprise fund that is responsible for funding all of its related costs. It is
not dependent upon general tax revenues or General Fund resources. The primary source of funding for
the Storm Drainage Utility is collections from service charges. The City controls the LOS charges by
ordinance and, subject to statutory authority, can adjust user charges as needed to meet financial
objectives.
The financial plan can provide a qualified assurance of financial feasibility only if it considers the “total
system” costs of providing service—both operating and capital. To meet these objectives, the following
elements are completed:
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• Capital funding plan: The capital funding plan identifies the total CIP obligations for the capital
planning period 2014–35, although the Storm Drainage Utility’s capital plan in this Drainage Plan
begins in 2016. The plan defines a strategy for funding the CIP including an analysis of available
resources from rate revenues, existing reserves, SDCs, debt financing, and any special resources
that may be readily available (e.g., grants, developer contributions, etc.). The capital funding plan
impacts the financial plan through use of debt financing (resulting in annual debt service) and the
assumed rate revenue resources available for capital funding. The capital funding plan is discussed
in Section 9.3.3.
• Financial forecast: This forecast identifies annual non-capital costs associated with the operation,
maintenance, and administration of the system. Included in the financial plan is a reserve analysis
that forecasts cash flow and fund balance activity along with testing for satisfaction of actual or
recommended minimum fund balance policies. The financial plan ultimately evaluates the
sufficiency of Storm Drainage Utility revenues in meeting all obligations, including operating
expenses, debt service, and reserve contributions, as well as any debt service coverage
requirements associated with long-term debt. The financial forecast analysis is discussed in Section
9.4.
9.3.1 Utility Fund Structure
The City tracks the Storm Drainage Utility’s revenues and expenditures in a single fund: Fund 432.
Conceptually, Storm Drainage Utility expenditures can be divided into three main types of costs:
operating, capital, and debt service. For modeling purposes, it was assumed that the single fund for the
Storm Drainage Utility is split among three “accounts”: operating, capital, and debt reserves). Municipal
utilities commonly maintain separate operating, capital, and debt reserves. The initial allocation of the
beginning fund balance is discussed in Section 9.4.
• Operations: Serves as an operating account where operating revenues are deposited and operating
expenses are paid.
• Capital projects: Serves as a capital account where capital revenues are deposited and capital
expenditures are paid. Examples of capital revenues include SDCs, grant proceeds, debt proceeds,
and contributions from rates.
• Restricted bond reserve: Serves as a restricted account set up to comply with revenue bond
covenants.
Splitting a single fund into three separate “accounts” allows the City to apply the City’s and industry
standard reserve targets to each account. Minimum balance thresholds for these accounts are
discussed in Section 9.3.2 below.
9.3.2 Financial Policies
A brief summary of adopted or recommended financial policies for the Storm Drainage Utility is provided
below. Adopted policies are drawn from the “Process/Policies” section within the City’s Adopted 2015–
16 budget.
9.3.2.1 Reserve Policies
Utility reserves serve multiple functions: they can be used to address variability and timing of
expenditures and receipts; occasional disruptions in activities, costs, or revenues; utility debt obligations;
and many other functions. The collective use of individual reserves helps to limit the City’s exposure to
revenue shortfalls, meet long-term capital obligations, and reduce the potential for bond coverage
defaults.
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• Operating reserve: An operating reserve is designed to provide a liquidity cushion; it protects the
utility from the risk of short-term variation in the timing of revenue collection or payment of
expenses. Like other types of reserves, operating reserves also serve another purpose: they help to
smooth rate increases over time. Target funding levels for an operating reserve are generally
expressed as a certain number of days of M&O expenses, with the minimum requirement varying
with the expected revenue volatility. Industry practice for utility operating reserves ranges from 30
days (8 percent) to 120 days (33 percent) of M&O expenses, with the lower end more appropriate
for utilities with stable revenue streams and the higher end of the range more appropriate for
utilities with significant seasonal or consumption-based fluctuations.
The City’s adopted policy states that the Storm Drainage Utility’s target operating reserves should be
approximately 60 days (page 36, “Process/Policies”). This is the target assumed in the financial
forecast. Based on the City’s 2015 budgeted expenditures (excluding depreciation), a 60-day target
equates to $1.2 million.
• Capital contingency reserve: A capital contingency reserve is cash set aside in case of an emergency
should a piece of equipment or a portion of the Storm Drainage Utility’s infrastructure fail
unexpectedly. The reserve could also be used for other unanticipated capital needs, including capital
project cost overruns. Various approaches are used in the industry to set an appropriate level for this
reserve, such as (1) choosing a percentage of a utility system’s total fixed assets, or (2) determining
the cost of replacing highly critical assets or facilities. Following common industry practice, this
analysis assumes a minimum capital fund balance equal to 1 percent of the original cost of plant in
service.
• Bond reserve: Bond covenants often establish reserve requirements as a means of protecting an
agency against the risk of nonpayment. This bond reserve can be funded with cash on hand, but is
more often funded at the time of borrowing as part of the bond principal. A reserve amount equal to
annual debt service is targeted.
9.3.2.2 System Reinvestment Policies
The purpose of system reinvestment funding is to provide for the ongoing rate funding for the
replacement of system facilities. Each year, the Storm Drainage Utility assets lose value, and as they lose
value they are moving toward eventual replacement. That accumulating loss in value and future liability
is typically measured for reporting purposes through annual depreciation expense. This is based on the
original cost of the asset divided by its anticipated useful life. While this expense reflects the
consumption of the existing asset and its original investment, the replacement of that asset will likely
cost much more, after factoring in inflation and construction conditions. Therefore, the added annual
replacement liability is often even greater than the annual depreciation expense. It is prudent to
establish a system reinvestment policy that attempts to recover at least a portion of the annual
depreciation expense from rate funding. Providing a certain amount of rate-funded capital reinvestment
is an approach to ensure that the system does not become too heavily dependent on debt.
The City’s adopted policy is to phase in system reinvestment funding over 10 years in 10 percent
increments beginning in 2012. To keep rates at their currently adopted levels through 2017, the system
reinvestment strategy for the financial plan begins in 2015 at 40 percent and increases by 10 percent
per year until 100 percent of the target is funded.
9.3.2.3 Debt Policies
Revenue bond covenants typically establish a minimum debt service coverage as a way to protect
bondholders against the risk of nonpayment. City policy and the City’s current bond covenants both
require bonded debt service coverage of 1.25.
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The City also has another debt-related policy, which is to maintain a capital structure that does not
exceed 50 percent debt. This is more conservative than the typical industry standard of 60 percent debt
and 40 percent equity. The City’s capital structure from the 2013 financial statement was well below the
threshold at 21 percent debt and 79 percent equity. This forecast projects that the debt level will be 13
percent by 2021, remaining well within the industry-standard limit of 60 percent debt and 40 percent
equity.
9.3.3 Capital Funding Plan
The CIP developed for this Drainage Plan contains 14 different projects valued at $25 million ($34
million in inflated dollars) over the 2016–35 planning period (excluding the 2014 estimated and 2015
budgeted capital figures). Costs are stated in 2014 dollars and are escalated to the year of planned
spending at an annual inflation rate of 3.5 percent per year.
Table 9-5 summarizes the expected annual capital expenditures, using 2014 estimated and 2015
budgeted capital expenditures.
Table 9-5. Drainage CIP
A capital funding plan is developed to identify the total resources available to pay for the CIP and
determine if new debt financing is required. After allocating the estimated beginning 2015 fund balance
first to the debt reserve and secondly to the operating reserve, more than $8.6 million was available for
capital.
The SDC is projected to generate an average annual revenue stream of roughly $800,000. This is based
on an assumed ESU growth rate of 1 percent per year. The growth percentage is drawn from a 2012
analysis provided by the City’s storm drainage engineer, who projected ESUs through 2018. An account
growth of 1.8 percent is used in the rate revenue projection in the financial forecast. Using an ESU
growth rate that is lower than customer account growth is a reasonable and conservative assumption
after evaluating historical SDC revenues.
The SDC revenue projection assumes the current SDC of $1,162 plus an annual Construction Cost Index
adjustment starting in 2016.
Table 9-6 summarizes the capital funding plan.
Table 9-6. Capital Financing Plan
Table 9-5. Drainage CIP
Year 2014 $Inflated $
20149,154,705$ 9,154,705$
20154,964,848$ 5,138,618$
20164,133,000$ 4,427,373$
20172,896,000$ 3,210,847$
20182,773,500$ 3,182,655$
20193,247,100$ 3,856,536$
2020828,300$ 1,018,192$
20211,442,100$ 1,834,754$
8 Year Total 29,439,553$ 31,823,680$
2022-20359,633,800$ 16,197,872$
Grand Total 39,073,353$ 48,021,552$
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Financial Forecast 9.4
The financial forecast, or revenue requirement analysis, forecasts the amount of annual rate revenue
needed throughout the 2014–21 planning horizon. The analysis incorporates operating revenues, M&O
expenses, debt service payments, rate-funded capital needs, and any other identified revenues or
expenses related to Storm Drainage Utility operations, and determines the sufficiency of the current level
of rates. Revenue needs are also impacted by debt covenants (typically applicable to revenue bonds)
and specific fiscal policies and financial goals of the Storm Drainage Utility. For this analysis, two
revenue sufficiency “tests” have been developed to reflect the financial goals and constraints of the
Storm Drainage Utility: (1) cash needs must be met, and (2) debt coverage requirements must be
realized. In order to operate successfully with respect to these goals, both tests of revenue sufficiency
described below must be met.
9.4.1 Cash Test
The cash flow test identifies all known cash requirements for the Storm Drainage Utility in each year of
the planning period. Capital needs are identified and a capital funding strategy is established. This may
include the use of debt, cash reserves, outside assistance, and rate funding. Cash requirements to be
funded from rates are determined. Typically, these include M&O expenses, debt service payments,
system reinvestment funding or directly funded capital outlays, and any additions to specified reserve
balances. The total annual cash needs of the Storm Drainage Utility are then compared to total operating
revenues (under current rates) to forecast annual revenue surpluses or shortfalls.
9.4.2 Coverage Test
The coverage test is based on a commitment made by the City when issuing revenue bonds. For
purposes of this analysis, revenue bond debt is assumed for any needed debt issuance. As a security
condition of issuance, the City is required per covenant to agree that the revenue bond debt would have
a higher priority for payment (a senior lien) compared to most other Storm Drainage Utility expenditures;
the only outlays with a higher lien are M&O expenses. Debt service coverage is expressed as a multiplier
of the annual revenue bond debt service payment. For example, a 1.0 coverage factor would imply that
no additional cushion is required. A 1.25 coverage factor means revenues must be sufficient to pay M&O
expenses, annual revenue bond debt service payments, plus an additional 25 percent of annual revenue
bond debt service payments. The excess cash flow derived from the added coverage, if any, can be used
Table 9-6. Capital Financing Plan
Year Capital
Expenditures
Capital
Expenditures
Inflated
Revenue Bond
Financing Cash Funding Total Financial
Resources
20149,154,705$ $ 9,154,705 $ - 9,154,705$ $ 9,154,705
20154,964,848 5,138,618 - 5,138,618 5,138,618
20164,133,000 4,427,373 - 4,427,373 4,427,373
20172,896,000 3,210,847 - 3,210,847 3,210,847
20182,773,500 3,182,655 492,824 2,689,831 3,182,655
20193,247,100 3,856,536 1,858,962 1,997,574 3,856,536
2020828,300 1,018,192 - 1,018,192 1,018,192
20211,442,100 1,834,754 - 1,834,754 1,834,754
8-Year Total 29,439,553$ 31,823,680$ 2,351,786$ 29,471,893$ 31,823,680$
2022-20359,633,800$ 16,197,872$ -$ 16,197,872$ 16,197,872$
Grand Total 39,073,353$ 48,021,552$ 2,351,786$ 45,669,766$ 48,021,552$
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for any Storm Drainage Utility purpose, including funding capital projects. The existing coverage
requirement policy on the City’s outstanding revenue bonds is 1.25 times bond debt. In determining the
annual revenue requirement, both the cash and coverage sufficiency tests must be met—the test with
the greatest deficiency drives the level of needed rate increase in any given year.
The financial forecast projects the amount of operating and capital expenditures to determine the
annual amount of revenue required. The objective of the financial forecast is to evaluate the sufficiency
of the current level of rates in meeting the total revenue requirements of the system. In addition to
annual operating costs, the revenue of the Storm Drainage Utility must also meet debt covenant
requirements and minimum reserve level targets.
9.4.3 Financial Forecast Assumptions
The financial forecast is developed from the City’s adopted 2015–16 biennial budget documents along
with other key factors and assumptions to develop a complete portrayal of the Storm Drainage Utility’s
annual financial obligations. The forecast covers the 2014–21 planning period. The following is a list of
the key revenue and expense factors and assumptions used to develop the forecast:
9.4.3.1 Revenue and Fund Balance
The following revenue and fund balance assumptions are used to develop the forecast:
• Customer growth: Based on a review of 5 years of historical data, annual customer account growth
has been 1.8 percent per year.
• Adopted rate increases: The City adopted annual rate increases through 2017 of roughly 2.5
percent, which are incorporated into the revenue figures in the forecast. The analysis shows that
through 2017, no additional rate increases are needed above the adopted levels.
• Miscellaneous revenues are conservatively assumed to stay at their currently budgeted levels.
Miscellaneous revenues include late penalties, applications, etc. The Build America Bonds (BAB)
subsidy for the 2010 Revenue Bond is expected to gradually decline in proportion to the annual
decline in interest expense.
• Fund balances are based on the budgeted beginning balance in 2015. Depending on resource
availability, the balance was allocated to the “accounts” using the following methodology:
− Debt reserve: amount equal to highest annual debt service on existing debt
− Operating reserve: amount equal to the operating reserve target of 60 days
− Capital reserve: remaining funds
The estimated beginning fund balance in 2015 was approximately $10.6 million, which is enough to
fully fund the debt reserve, provide 60 days in the operating reserve, and provide over $8.6 million in
the capital reserve.
• Interest earnings initially assume a rate of 0.09 percent applied to the beginning of year cash
balances based on existing Local Government Investment Pool rates, phasing toward 0.25 percent
over the long term.
9.4.3.2 Expenditures
The following expenditure assumptions are used to develop the forecast:
• General operating expenses are escalated from the budgeted figures at 2.5 percent per year, labor
costs at 2.5 percent per year, and benefits at 5.5 percent per year.
• State taxes are calculated based on prevailing tax rates.
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• Existing debt service schedules were provided by the City and include three existing revenue bond
issues. These obligations represent nearly $795,000 in annual debt service principal and interest
payments in 2015.
• This Drainage Plan identifies additional staffing levels and equipment purchases needed above the
2015 and 2016 budgeted levels. The additional staff is needed for vegetation maintenance, NPDES
compliance activities, which include LID facility inspection, maintenance tracking, and public
education and outreach.
− Full-time engineering staff with salaries plus benefits totaling $107,000 starting in 2017 and
continuing throughout the study period.
− Full-time system maintenance staff with salaries and benefits totaling $320,000 starting in
2017 and continuing throughout the study period. This includes a 50 percent share of the asset
management specialist to be shared with the Sewer Utility.
− Full-time vegetation maintenance staff with salaries and benefits totaling $112,000 starting in
2017 and continuing throughout the study period.
− One-time equipment purchases in 2017 consisting of CCTV inspection equipment for
$250,000,an excavator for $180,000, and an excavator mower attachment for $30,000.
• Future debt service has been added as outlined in the capital funding plan. The forecast assumes a
revenue bond interest rate of 4.30 percent based on prevailing rates, as well as an issuance cost of
1 percent with a 20-year term. City policy dictates a minimum debt service coverage requirement of
1.25.
The City should review the proposed rates and rate assumptions annually to ensure that the rate
projections developed remain adequate. Any significant changes should be incorporated into the
financial plan and future rates should be adjusted as needed.
Table 9-7 summarizes the annual revenue requirement for the 2014–21 planning horizon based on the
forecast of revenues, expenditures, fund balances, fiscal policies, and capital funding.
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Table 9-7. Financial Forecast
The last row of Table 9-7 shows the projected debt service coverage for bonded debt. Bonded debt
service coverage—which legally cannot drop below 1.25—is projected to stay at or above 3.17 throughout
the life of the forecast.
In 2012, the City Council adopted annual rate increases of 2.5 percent in 2015, 2016, and 2017. This
analysis shows that the adopted rates will generate sufficient revenue to meet operating expenses and
the Storm Drainage Utility policy goals as discussed herein for the 2015–17 period. Based on the
assumptions in the forecast, no incremental rate increases (above adopted amounts) are needed
through 2017.
Based on the financial forecast, no rate increase is needed in 2018. Rate increases averaging about 2.6
percent per year are needed in 2019 and beyond to cover projected M&O expenses, debt service
payments, system reinvestment funding, and other stated financial policy objectives. While no rate
increase is projected in 2018, it may be prudent to adopt a smaller set of increases over 4 years (2018–
21) rather than adopt a higher set of increases over 3 years (2019–21).
9.4.4 City Funds and Reserve Balances
Table 9-8 shows a summary of the projected ending City operating, capital, and debt reserve balances
through 2021. The operating reserve ends at 60 days of operating expenditures; the capital reserve
ends at over $4 million, which is above the minimum target of about $1 million; and the debt reserve
ends at nearly $1 million, which is enough to cover 1 year of annual debt service.
Table 9-7. Financial Forecast
Revenue Requirements 20142015201620172018201920202021
Assuming Existing Rates:
Revenue
Rate Revenues 8,727,224$ 9,106,422$ 9,502,096$ 9,914,962$ 10,093,431$ 10,275,113$ 10,460,065$ 10,648,346$
Non-Rate Revenues 2,133,878 960,113 176,479 173,808 171,731 169,614 167,462 164,803
Total Revenue 10,861,102$ 10,066,535$ 9,678,575$ 10,088,770$ 10,265,162$ 10,444,727$ 10,627,527$ 10,813,149$
Expenses
Cash Operating Expenses 7,000,356$ 7,323,914$ 7,249,903$ 8,342,836$ 8,151,980$ 8,399,583$ 8,656,021$ 8,921,664$
Existing Debt Service 796,781 795,239 777,111 774,579 776,275 776,413 774,467 774,396
New Debt Service - - - - 40,716 194,299 194,299 194,299
Rate-Funded System Reinvestment - 550,558 734,017 940,032 1,120,686 1,268,271 1,479,931 1,646,473
Additions to Operating Reserve - - - - 120,221 40,702 38,266 47,555
Total Expenses 7,797,136$ 8,669,711$ 8,761,031$ 10,057,448$ 10,209,877$ 10,679,269$ 11,142,985$ 11,584,387$
Cash Surplus / (Deficiency) Before Rate Increases 3,063,965$ 1,396,824$ 917,544$ 31,322$ 55,285$ (234,542)$ (515,458)$ (771,238)$
Annual Rate Adjustment 0.00%0.00%0.00%0.00%2.49%2.82%2.40%
Cumulative Annual Rate Adjustment 0.00%0.00%0.00%0.00%2.49%5.39%7.92%
After Rate Increases:
Rate Revenues 8,727,224$ 9,106,422$ 9,502,096$ 9,914,962$ 10,093,431$ 10,531,443$ 11,023,407$ 11,491,230$
Cash Surplus / (Deficiency) After Rate Increases 3,064,000 1,396,800 917,500 31,300 175,500 40,700 38,300 47,600
Debt Service Coverage - Revenue Bonds 5.694.343.993.253.543.173.403.61
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Table 9-8. Cash Balance Summary
Existing Rate Structure and Projected Schedule 9.5
The City’s existing rate structure is composed of a single-family rate class and six non-single-family rate
classes. The rate schedule for the single-family customer class consists of a base monthly charge. The
rate schedule for non-single-family customers consists of a base monthly charge and an additional
charge per ESU based on the characteristics of a customer’s parcel.
Low-income, single-family residential customers are provided a 50 percent discount to the rates
presented. To qualify for a low-income discount, a customer must be 62 years old or older and meet low-
income guidelines as defined by the U.S. Department of Housing and Urban Development (ACC 13.24
and 13.24.030).
A recent detailed review of the City’s rate structure has been completed in the 2014 Retail Rate Study
and recommends incorporating cost-of-service adjustments among various rate classes.
Table 9-9 presents the City’s existing rate schedule for each customer class under the adopted rates
through 2017. No rate increases above adopted levels are necessary through 2017. The table then
incorporates necessary rate increases starting in 2018 and continuing through 2021.
Table 9-9. Projected Rate Schedule
Table 9-8. Cash Balance Summary
Ending Reserves 20142015201620172018201920202021
Operating 1,150,743$ 1,203,931$ 1,188,509$ 1,219,831$ 1,340,051$ 1,380,753$ 1,419,020$ 1,466,575$
Capital 8,362,881 6,169,948 4,170,692 2,689,831 1,997,574 2,125,099 3,482,614 4,233,887
Debt 796,781 795,239 776,414 776,414 817,130 970,712 970,712 970,712
Total 10,310,405$ 8,169,117$ 6,135,614$ 4,686,075$ 4,154,755$ 4,476,564$ 5,872,347$ 6,671,174$
Table 9-9. Projected Rate Schedule
Monthly Rate Schedule AdoptedAdoptedAdoptedAdopted ProjectedProjectedProjectedProjected
20142015201620172018201920202021
Annual:0.00%0.00%0.00%0.00%2.49%2.82%2.40%
Cumulative:0.00%0.00%0.00%0.00%2.49%5.39%7.92%
Single Family $18.78$19.25$19.73$20.22$20.22$20.72$21.31$21.82
Non-Single Family
Base Charge $11.68$11.97$12.27$12.58$12.58$12.89$13.26$13.58
ESU Charges
Non-Single-Family $14.95$15.32$15.71$16.10$16.10$16.50$16.97$17.37
NSF w/Detention $12.01$12.31$12.62$12.93$12.93$13.25$13.63$13.95
NSF w/Retention $7.42$7.61$7.80$8.00$8.00$8.20$8.43$8.63
NSF w/Water Quality Treatment $8.98$9.21$9.44$9.67$9.67$9.91$10.19$10.44
NSF w/Detention and Water Quality Treatment $6.78$6.95$7.13$7.31$7.31$7.49$7.70$7.89
NSF w/Retention and Water Quality Treatment $4.25$4.35$4.46$4.57 $4.57$4.68$4.82$4.93
Low Income Discount: 50%
Rate Increases Applied "Across the Board"
Rate increases shown in 2015, 2016, and 2017 reflect already-adopted annual increases of 2.5%
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Affordability 9.6
The Washington State Department of Health and the PWB have historically used an affordability index to
prioritize low-cost loan awards. The typical threshold looks at whether a system’s rates exceed 1.5 to 2.0
percent of the median household income for the demographic area. As a result, if monthly bills are less
than 1.5 percent of the median household income for the demographic area, they are generally
considered affordable.
According to City staff, the median household income for the City of Auburn in 2012 was $49,996. This
figure was inflated to $51,810 at 2014 levels assuming annual Consumer Price Index adjustments.
Table 9-10 presents the City’s estimated single-family rate with the projected rate increases for the
forecast period. The affordability mark (monthly bill * 12 ÷ median income) averages 0.4 percent
throughout the study period. As shown in the following table, the City’s rates remain well within the
affordability range throughout the planning horizon.
Table 9-10 below presents the results of the affordability test.
Table 9-10. Affordability Test
Conclusion 9.7
The financial analysis indicates that the adopted rates in 2015, 2016, and 2017 are sufficient to meet
the Storm Drainage Utility financial obligations as presented in this forecast. No additional rate increases
are proposed for 2015–17. Based on the forecast, no rate increase is required in 2018. Rate increases
for 2019–21 average about 2.6 percent per year, for a cumulative increase of 7.9 percent.
This evaluation also finds that the rates with projected rate increases would remain well within the
defined threshold of affordability.
Table 9-10. Affordability Test
Year Inflation Median HH
Income
Projected
Monthly Bill
% of Median HH
Income
20142.50%$51,810$18.780.43%
2015 2.50%$53,106$19.250.43%
2016 2.50%$54,433$19.730.43%
2017 2.50%$55,794$20.220.43%
2018 2.50%$57,189$20.220.42%
2019 2.50%$58,619$20.720.42%
2020 2.50%$60,084$21.310.43%
2021 2.50%$61,586$21.820.43%
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Chapter 10
Limitations
This document was prepared solely for City of Auburn in accordance with professional standards at the
time the services were performed and in accordance with the contract between City of Auburn and
Brown and Caldwell dated December 6, 2013. This document is governed by the specific scope of work
authorized by City of Auburn; it is not intended to be relied upon by any other party except for regulatory
authorities contemplated by the scope of work. We have relied on information or instructions provided by
City of Auburn and other parties and, unless otherwise expressly indicated, have made no independent
investigation as to the validity, completeness, or accuracy of such information.
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Chapter 11
References
Auburn City Code (ACC). 2009. http://www.codepublishing.com/wa/auburn/.
Booth. 1991. Glacier physics of the Puget lobe, southwest Cordilleran ice sheet: Geographie Physique et Quaternaire, v.
45, pp. 301–316.
Brown and Caldwell. 2014. Draft Cartegraph Economic Life Model System Requirements Specification.
City of Auburn Comprehensive Plan (Comp Plan). Amended 2011. City of Auburn.
http://www.auburnwa.gov/business/Planning___Development/Comprehensive_Plan.asp.
City of Auburn 2015 Stormwater Management Program Plan. March 2015. City of Auburn.
King County. 2010. Tabula conveyance system cost estimating software. Version 3.1.2.
Miller, J.F., Frederick, R.H., and Tracey, R.J. 1973. Precipitation-frequency Atlas of the Western United States: NOAA Atlas
2 Volume IX-Washington. United States Department of Commerce, National Oceanic and Atmospheric
Administration, National Weather Service. Silver Spring, Maryland.
Natural Resources Conservation Center (NRCS). June 1986. Urban Hydrology for Small Watershed, Technical Release 55
(TR-55). United States Department of Agriculture, Natural Resources Conservation Service, Conservation Engineering
Division.
Pierce County. February 2013. Pierce County Rivers Flood Hazard Management Plan, Adopted February 19, 2013,
Ordinance 2012-53s. Pierce County Public Works & Utilities Surface Water Management.
SPU, 2012. City of Seattle Unit Cost Report (for APWA Standard Bid Items).
Tetra Tech, Inc. September 2002. City of Auburn 2002 Comprehensive Drainage Plan. Prepared for the City of Auburn by
Tetra Tech/KCM, Inc., 1917 First Ave., Seattle, WA 98101.
Troost, K.G. and Booth, D.B, 2008. Geology of Seattle and the Seattle area, Washington. The Geological Society of
America, Reviews in Engineering Geology XX, 2008.
U.S. Army Corps of Engineers (USACE). April 2009. Project Management Plan for Wetland 5K Reach Mill Creek
Restoration, Green Duwamish Ecosystem Restoration Program. U.S. Army Corps of Engineers, Seattle District,
U.S. Army Corps of Engineers (USACE). October 2009. Mud Mountain Dam: White and Puyallup Rivers Channel Capacity
Study. U.S. Army Corps of Engineers, Seattle District, Hydraulic Engineering Section.
Washington State Department of Ecology. June 2011. Green River Temperature Total Maximum Daily Load Water Quality
Improvement Report June 2011, Publication No. 11-10-046.
Western Regional Climate Center (WRCC). 2014a. “Climate of Washington.”
http://www.wrcc.dri.edu/narratives/WASHINGTON.htm
Western Regional Climate Center (WRCC). 2014b. “Period of Record Monthly Climate Summary for Seattle Tcoma Wscmo
Ap, Washington.” http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?waseat
Western Regional Climate Center (WRCC). 2014c. “Period of Record Monthly Climate Summary for Kent, Washington.”
http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?wakent
WSDOT, 2012–2014. Unit Bid Tab for the Northwest region.
Comprehensive Storm Drainage Plan
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Appendix A: Western Washington Phase II Municipal
Stormwater Permit
Issuance Date:
Effective Date:
Expiration Date:
Modification Date:
August 1, 2012
August 1, 2013
July31,2018
January 16, 2014
Western Washington Phase II Municipal
Stormwater Permit
National Pollutant Discharge Elimination System and
State Waste Discharge General Permit
for discharges from Small Municipal Separate Storm Sewers
in Western Washington
State of Washington
Department of Ecology
Olympia, Washington 98504-7600
In compliance with the provisions of
The State of Washington Water Pollution Control Law
Chapter 90.48 Revised Code of Washington
and
The Federal Water Pollution Control Act
(The Clean Water Act)
Title 33 United States Code, Section 1251 et seq.
Until this permit expires, is modified, or revoked, Permittees that have properly obtained
coverage under this permit are authorized to discharge to waters of the state in accordance with
the special and general conditions which follow.
~ther R. Bartlett
Wa er Quality Program Manager
Department of Ecology
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 2 of 74
THIS PAGE INTENTIONALLY LEFT BLANK
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 3 of 74
TABLE OF CONTENTS
SPECIAL AND GENERAL CONDITIONS
SPECIAL CONDITIONS ............................................................................................................... 5
S1. PERMIT COVERAGE AREA AND PERMITTEES ........................................... 5
S2. AUTHORIZED DISCHARGES ......................................................................... 10
S3. RESPONSIBILITIES OF PERMITTEES ........................................................... 11
S4. COMPLIANCE WITH STANDARDS............................................................... 12
S5. STORMWATER MANAGEMENT PROGRAM FOR CITIES, TOWNS, AND
COUNTIES ......................................................................................................... 15
S5.C.1 Public Education and Outreach .................................................................................... 17
S5.C.2 Public Involvement and Participation .......................................................................... 19
S5.C.3 Illicit Discharge Detection and Elimination ................................................................. 19
S5.C.4 Controlling Runoff from New Development, Redevelopment and Construction Sites 25
S5.C.5 Municipal Operations and Maintenance ...................................................................... 35
S6. STORMWATER MANAGEMENT PROGRAM FOR SECONDARY
PERMITTEES ..................................................................................................... 39
S7. COMPLIANCE WITH TOTAL MAXIMUM DAILY LOAD
REQUIREMENTS .............................................................................................. 48
S8. MONITORING AND ASSESSMENT ............................................................... 48
S9. REPORTING REQUIREMENTS ....................................................................... 56
GENERAL CONDITIONS .......................................................................................................... 59
G1. DISCHARGE VIOLATIONS ............................................................................. 59
G2. PROPER OPERATION AND MAINTENANCE .............................................. 59
G3. NOTIFICATION OF DISCHARGE, INCLUDING SPILLS ............................. 59
G4. BYPASS PROHIBITED ..................................................................................... 59
G5. RIGHT OF ENTRY ............................................................................................ 60
G6. DUTY TO MITIGATE ....................................................................................... 60
G7. PROPERTY RIGHTS ......................................................................................... 60
G8. COMPLIANCE WITH OTHER LAWS AND STATUTES .............................. 60
G9. MONITORING ................................................................................................... 60
G10. REMOVED SUBSTANCES ............................................................................... 62
G11. SEVERABILITY ................................................................................................ 62
G12. REVOCATION OF COVERAGE ...................................................................... 62
G13. TRANSFER OF COVERAGE ............................................................................ 63
G14. GENERAL PERMIT MODIFICATION AND REVOCATION ........................ 63
G15. REPORTING A CAUSE FOR MODIFICATION OR REVOCATION ............ 63
G16. APPEALS ............................................................................................................ 63
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 4 of 74
G17. PENALTIES ........................................................................................................ 64
G18. DUTY TO REAPPLY ......................................................................................... 64
G19. CERTIFICATION AND SIGNATURE ............................................................. 64
G20. NON-COMPLIANCE NOTIFICATION ............................................................ 65
G21. UPSETS ............................................................................................................... 65
DEFINITIONS AND ACRONYMS ............................................................................................ 67
APPENDICES
APPENDIX 1. MINIMUM TECHNICAL REQUIREMENTS
APPENDIX 2. TOTAL MAXIMUM DAILY LOAD REQUIREMENTS
APPENDIX 3. ANNUAL REPORT FOR CITIES, TOWNS AND COUNTIES
APPENDIX 4. ANNUAL REPORT FOR SECONDARY PERMITTEES
APPENDIX 5. NOTICE OF INTENT
APPENDIX 6. STREET WASTE DISPOSAL
APPENDIX 7. DETERMINING CONSTRUCTION SITE DAMAGE TRANSPORT
POTENTIAL
APPENDIX 8. ANNUAL REPORT FOR NEW PERMITTEES
APPENDIX 9. STORMWATER DISCHARGE MONITORING
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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SPECIAL CONDITIONS
S1. PERMIT COVERAGE AREA AND PERMITTEES
A. Geographic Area of Permit Coverage
This Permit is applicable to owners or operators of regulated small municipal separate
storm sewer systems (MS4s) located west of the eastern boundaries of the following
counties: Whatcom, Skagit, Snohomish, King, Pierce, Lewis and Skamania.
1. For all cities required to obtain coverage under this permit, the geographic area of
coverage is the entire incorporated area of the city.
2. For all counties required to have coverage under this Permit, the geographic area
of coverage is the urbanized areas and urban growth areas associated with
permitted cities under the jurisdictional control of the county. The geographic area
of coverage also includes any urban growth area contiguous to permitted
urbanized areas under the jurisdictional control of the county.
3. For Whatcom County, the geographic area of coverage also includes the
unincorporated Birch Bay urban growth area.
4. For Secondary Permittees required to obtain coverage under this permit, the
minimum geographic area of coverage is all areas identified under S1.A.1 and
S1.A.2. At the time of permit coverage, the Washington State Department of
Ecology (Ecology) may establish a geographic area of coverage specific to an
individual Secondary Permittee.
5. All regulated small MS4s owned or operated by the Permittees named in
S1.D.2.a(i) and (ii),and S1.D.2.b and located in another city or county area
requiring coverage under this permit or the Phase I Municipal Stormwater Permit
or the Eastern Washington Phase II Municipal Stormwater Permit are also
covered under this permit.
B. Regulated Small Municipal Separate Storm Sewer Systems (MS4s)
All operators of regulated small MS4s are required to apply for and obtain coverage
under this Permit or be permitted under a separate individual permit, unless waived or
exempted in accordance with condition S1.C.
1. A regulated small MS4:
a. Is a “Small MS4” as defined in the Definitions and Acronyms section at the
end of this Permit; and
b. Is located within, or partially located within, an urbanized area as defined by
the latest decennial census conducted by the U.S. Bureau of Census, or
S1.B.2 S1.B.5
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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designated by Ecology pursuant to 40 CFR 123.35(b) or 40 CFR 122.26(f);
and
c. Discharges stormwater from the MS4 to a surface water of Washington State;
and
d. Is not eligible for a waiver or exemption under S1.C. below.
2. All other operators of MS4s, including special purpose districts, which meet the
criteria for a regulated small MS4 shall obtain coverage under this Permit. Other
operators of small MS4s may include, but are not limited to: flood control, or
diking and drainage districts, schools including universities, and correctional
facilities that own or operate a small MS4 serving non-agricultural land uses.
3. Any other operators of small MS4s may be required by Ecology to obtain
coverage under this permit or an alternative NPDES permit if Ecology determines
the small MS4 is a significant source of pollution to surface waters of the state.
Notification of Ecology’s determination that permit coverage is required will be
through the issuance of an Administrative Order issued in accordance with RCW
90.48.
4. The owner or operator of a regulated small MS4 may obtain coverage under this
Permit as a Permittee, Co-Permittee, or Secondary Permittee as defined in S1.D.1.
below.
5. Pursuant to 40 CFR 122.26(f), any person or organization may petition Ecology to
require that additional small MS4s obtain coverage under this Permit. The process
for petitioning Ecology is:
a. The person or organization shall submit a complete petition in writing to
Ecology. A complete petition shall address each of the relevant factors for
petitions outlined on Ecology’s website.
b. In making its determination on the petition, Ecology may request additional
information from either the petitioner or the entity that is the subject of the
petition.
c. Ecology will make a final determination on a complete petition within 180
days of receipt of the petition and inform both the petitioner and the MS4 of
the decision, in writing.
d. If Ecology’s final determination is that the candidate MS4 will be regulated,
Ecology will issue an order to the operator of the MS4 requiring them to
obtain coverage under this Permit. The order will specify:
i. The geographic area of permit coverage for the MS4;
S1.C.1 S1.C.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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ii. Any modified dates or deadlines for developing and implementing this
Permit, as appropriate to the MS4, and for submitting their first annual
report; and
iii. A deadline for the operator of the MS4 to submit a complete Notice of
Intent (see Appendix 5) to Ecology.
C. Owners and operators of an otherwise regulated small MS4 are not required to obtain
coverage under this Permit if:
1. The small MS4 is operated by:
a. A federal entity, including any department, agency or instrumentality of the
executive, legislative, and judicial branches of the Federal government of the
United States.
b. Federally recognized Indian Tribes located within Indian Country, including
all trust or restricted lands within the 1873 Survey Area of the Puyallup Tribe
of Indians; or
c. The Washington State Department of Transportation.
or:
2. The portions of the small MS4 located within the census defined urban area(s)
serve a total population of less than 1000 people and a, b, and c, below all apply:
a. The small MS4 is not contributing substantially to the pollutant loadings of a
physically interconnected MS4 that is regulated by the NPDES stormwater
program.
b. The discharge of pollutants from the small MS4 has not been identified as a
cause of impairment of any water body to which the MS4 discharges.
c. In areas where an EPA approved TMDL has been completed, stormwater
controls on the MS4 have not been identified as being necessary.
In determining the total population served, both resident and commuter
populations shall be included. For example:
• For publicly operated school complexes including universities and
colleges the total population served would include the sum of the
average annual student enrollment plus staff.
• For flood control, diking, and drainage districts the total population
served would include residential population and any non-residents
regularly employed in the areas served by the small MS4.
S1.D.1 S1.D.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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D. Obtaining coverage under this Permit
All operators of regulated small MS4s are required to apply for and obtain coverage
in accordance with this section, unless waived or exempted in accordance with
section S1.C.
1. Unless otherwise noted, the term “Permittee” shall include a city, town, or county
Permittee, New Permittee, Co-Permittee, Secondary Permittee, and New
Secondary Permittee as defined below:
a. “Permittee” is a city, town, or county owning or operating a regulated small
MS4 applying and receiving a permit as a single entity.
b. “New Permittee” is a city, town, or county that is subject to the Western
Washington Phase II Municipal Stormwater General Permit and was not
subject to the permit prior to August 1, 2013.
c. “Co-Permittee” is any owner or operator of a regulated small MS4 that is
applying in a cooperative agreement with at least one other applicant for
coverage under this Permit. Co-Permittees own or operate a regulated small
MS4 located within or in proximity to another regulated small MS4.
d. A “Secondary Permittee” is an operator of a regulated small MS4 that is not a
city, town or county. Secondary Permittees include special purpose districts
and other MS4s that meet the criteria for a regulated small MS4 in S1.B.
above.
e. “New Secondary Permittee” is a Secondary Permittee that is covered under a
municipal stormwater general permit and was not covered by the permit prior
to August 1, 2013.
2. Operators of regulated small MS4s have submitted or shall submit to Ecology
either a Notice of Intent (NOI) for Coverage under National Pollutant Discharge
Elimination System (NPDES) Municipal Stormwater General Permit provided in
Appendix 5 or a Duty to Reapply - NOI.
a. The following Permittees and Secondary Permittees submitted a Duty to
Reapply - NOI to Ecology prior to August 19, 2011:
i. Cities and towns: Aberdeen, Algona, Anacortes, Arlington, Auburn,
Bainbridge Island, Battle Ground, Bellevue, Bellingham, Black
Diamond, Bonney Lake, Bothell, Bremerton, Brier, Buckley, Burien,
Burlington, Camas, Centralia, Clyde Hill, Covington, Des Moines,
DuPont, Duvall, Edgewood, Edmonds, Enumclaw, Everett, Federal
Way, Ferndale, Fife, Fircrest, Gig Harbor, Granite Falls, Issaquah,
Kelso, Kenmore, Kent, Kirkland, Lacey, Lake Forest Park, Lake
Stevens, Lakewood, Longview, Lynnwood, Maple Valley, Marysville,
S1.D.2 S1.D.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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Medina, Mercer Island, Mill Creek, Milton, Monroe, Mountlake
Terrace, Mount Vernon, Mukilteo, Newcastle, Normandy Park, Oak
Harbor, Olympia, Orting, Pacific, Port Orchard, Port Angeles,
Poulsbo, Puyallup, Redmond, Renton, Sammamish, SeaTac, Sedro-
Woolley, Shoreline, Snohomish, Steilacoom, Sumner, Tukwila,
Tumwater, University Place, Vancouver, Washougal, and
Woodinville.
ii. Counties: Cowlitz, Kitsap, Thurston, Skagit, and Whatcom.
iii. Secondary Permittees: Bainbridge Island School District #303,
Bellingham School District, Bellingham Technical College, Cascadia
College, Central Kitsap School District, Centralia College, Clark
College, Consolidated Diking Improvement District #1 of Cowlitz
County, Edmonds Community College, Evergreen College, Highline
Community College, Kelso School District, Kent School District,
Longview School District, Lower Columbia College, Port of
Anacortes, Port of Bellingham, Port of Olympia, Port of Skagit
County, Port of Vancouver, Skagit County Drainage District #19,
Skagit Valley College, University of Washington Bothell, Washington
State University Vancouver, Washington State General Administration
(Capitol Campus), Washington Department of Corrections, Western
Washington University, and Whatcom Community College.
b. Operators of regulated small MS4s have submitted or shall submit to Ecology
a Notice of Intent (NOI) for Coverage under National Pollutant Discharge
Elimination System (NPDES) Municipal Stormwater General Permit provided
in Appendix 5 before the effective date of this permit, with the following
exceptions:
i. Operators of regulated small MS4s located in the Cities of Lynden and
Snoqualmie shall submit a NOI or application to Ecology no later than
30 days after the effective date of this permit.
ii. Operators of regulated small MS4s listed in S1.D.2.a do not need to
submit a new application to be covered under this permit.
c. For operators of regulated small MS4s listed in S1.D.2.a, coverage under this
permit is automatic and begins on the effective date of this permit, unless the
operator chooses to opt out of this General Permit. Any operator of a regulated
small MS4 that is opting out of this permit shall submit an application for an
individual MS4 permit in accordance with 40 CFR 122.33(b)(2)(ii) no later
than the effective date of this permit.
d. Operators of regulated small MS4s which want to be covered under this
permit as Co-Permittees shall each submit a NOI to Ecology.
S1.D.3 S2.A.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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e. Operators of regulated small MS4s which are relying on another entity to
satisfy all of their permit obligations shall submit a NOI to Ecology.
f. Operators of small MS4s designated by Ecology pursuant to S1.B.3 of this
permit shall submit a NOI to Ecology within 120 days of receiving
notification from Ecology that permit coverage is required.
3. Application Requirements
a. For NOIs submitted after the issuance date of this Permit, the applicant shall
include a certification that the public notification requirements of WAC 173-
226-130(5) have been satisfied. Ecology will notify applicants in writing of
their status concerning coverage under this Permit within 90 days of
Ecology’s receipt of a complete NOI.
b. Each Permittee applying as a Co-Permittee shall submit a NOI provided in
Appendix 5. The NOI shall clearly identify the areas of the MS4 for which the
Co-Permittee is responsible.
c. Permittees relying on another entity or entities to satisfy one or more of their
permit obligations shall notify Ecology in writing. The notification shall
include a summary of the permit obligations that will be carried out by
another entity. The summary shall identify the other entity or entities and shall
be signed by the other entity or entities. During the term of the permit,
Permittees may terminate or amend shared responsibility arrangements by
notifying Ecology, provided this does not alter implementation deadlines.
d. Secondary Permittees required to obtain coverage under this Permit, and the
Phase I Municipal Stormwater Permit or the Eastern Washington Phase II
Municipal Stormwater Permit may obtain coverage by submitting a single
NOI.
S2. AUTHORIZED DISCHARGES
A. This Permit authorizes the discharge of stormwater to surface waters and to ground
waters of the state from MS4s owned or operated by each Permittee covered under
this permit, in the geographic area covered pursuant to S1.A. These discharges are
subject to the following limitations:
1. Discharges to ground waters of the state through facilities regulated under the
Underground Injection Control (UIC) program, chapter 173-218 WAC, are not
authorized under this Permit.
2. Discharges to ground waters not subject to regulation under the federal Clean
Water Act are authorized in this permit only under state authorities, chapter 90.48
RCW, the Water Pollution Control Act.
S2.B.1 S3.A.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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B. This Permit authorizes discharges of non-stormwater flows to surface waters and to
ground waters of the state from MS4s owned or operated by each Permittee covered
under this permit, in the geographic area covered pursuant to S1.A, only under one or
more of the following conditions:
1. The discharge is authorized by a separate NPDES or State Waste Discharge
permit.
2. The discharge is from emergency fire fighting activities.
3. The discharge is from another illicit or non-stormwater discharge that is managed
by the Permittee as provided in Special Condition S5.C.3 or S6.C.3.
These discharges are also subject to the limitations in S2.A.1 and S.2.A.2 above.
C. This Permit does not relieve entities that cause illicit discharges, including spills of oil
or hazardous substances, from responsibilities and liabilities under state and federal
laws and regulations pertaining to those discharges.
D. Discharges from MS4s constructed after the effective date of this permit shall receive
all applicable state and local permits and use authorizations, including compliance
with chapter 43.21C RCW (the State Environmental Policy Act).
E. This Permit does not authorize discharges of stormwater to waters within Indian
Country or to waters subject to water quality standards of Indian Tribes, including
portions of the Puyallup River and other waters on trust or restricted lands within the
1873 Survey Area of the Puyallup Tribe of Indians Reservation, except where
authority has been specifically delegated to Ecology by the U.S. Environmental
Protection Agency. The exclusion of such discharges from this Permit does not waive
any rights the State may have with respect to the regulation of the discharges.
S3. RESPONSIBILITIES OF PERMITTEES
A. Each Permittee covered under this Permit is responsible for compliance with the
terms of this Permit for the regulated small MS4s that they own or operate.
Compliance with (1) or (2) below is required as applicable to each Permittee, whether
the Permittee has applied for coverage as a Permittee, Co-Permittee, or Secondary
Permittee.
1. All city, town and county Permittees are required to comply with all conditions of
this Permit, including any appendices referenced therein, except for Special
Condition S6 Stormwater Management Program for Secondary Permittees.
2. All Secondary Permittees are required to comply with all conditions of this
Permit, including any appendices referenced therein, except for section S5
Stormwater Management Program for Cities, Towns, and Counties and S8.B,
S8.C, and S8.D Monitoring.
S3.B.1 S4.F.1
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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B. Permittees may rely on another entity to satisfy one or more of the requirements of
this Permit. Permittees that are relying on another entity to satisfy one or more of
their permit obligations remain responsible for permit compliance if the other entity
fails to implement permit conditions. Permittees may rely on another entity provided
all the requirements of 40 CFR 122.35(a) are satisfied, including but not limited to:
1. The other entity, in fact, implements the Permit requirements.
2. The other entity agrees to take on responsibility for implementation of the Permit
requirement(s) as indicated on the NOI.
S4. COMPLIANCE WITH STANDARDS
A. In accordance with RCW 90.48.520, the discharge of toxicants to waters of the state
of Washington which would violate any water quality standard, including toxicant
standards, sediment criteria, and dilution zone criteria is prohibited. The required
response to such discharges is defined in section S4.F, below.
B. This Permit does not authorize a discharge which would be a violation of Washington
State Surface Water Quality Standards (chapter 173-201A WAC), Ground Water
Quality Standards (chapter 173-200 WAC), Sediment Management Standards
(chapter 173-204 WAC), or human health-based criteria in the national Toxics Rule
(Federal Register, Vol. 57, NO. 246, Dec. 22, 1992, pages 60848-60923). The
required response to such discharges is defined in section S4.F, below.
C. The Permittee shall reduce the discharge of pollutants to the maximum extent
practicable (MEP).
D. The Permittee shall use all known, available, and reasonable methods of prevention,
control and treatment (AKART) to prevent and control pollution of waters of the state
of Washington.
E. In order to meet the goals of the Clean Water Act, and comply with S4.A, S4.B, S4.C,
and S4.D each Permittee shall comply with all of the applicable requirements of this
Permit as identified in S3. Responsibilities of Permittees.
F. A Permittee remains in compliance with S4 despite any discharges prohibited by
S4.A or S4.B, when the Permittee undertakes the following response toward long-
term water quality improvement:
1. A Permittee shall notify Ecology in writing within 30 days of becoming aware,
based on credible site-specific information that a discharge from the MS4 owned
or operated by the Permittee is causing or contributing to a known or likely
violation of Water Quality Standards in the receiving water. Written notification
provided under this subsection shall, at a minimum, identify the source of the site-
specific information, describe the nature and extent of the known or likely
violation in the receiving water, and explain the reasons why the MS4 discharge is
S4.F.1 S4.F.3
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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believed to be causing or contributing to the problem. For ongoing or continuing
violations, a single written notification to Ecology will fulfill this requirement.
2. In the event that Ecology determines, based on a notification provided under
S4.F.1 or through any other means, that a discharge from an MS4 owned or
operated by the Permittee is causing or contributing to a violation of Water
Quality Standards in a receiving water, Ecology will notify the Permittee in
writing that an adaptive management response outlined in S4.F.3 below is
required, unless:
a. Ecology also determines that the violation of Water Quality Standards is
already being addressed by a Total Maximum Daily Load (TMDL) or other
enforceable water quality cleanup plan; or
b. Ecology concludes the MS4 contribution to the violation will be eliminated
through implementation of other permit requirements.
3. Adaptive Management Response
a. Within 60 days of receiving a notification under S4.F.2, or by an alternative
date established by Ecology, the Permittee shall review its Stormwater
Management Program (SWMP) and submit a report to Ecology. The report
shall include:
i. A description of the operational and/or structural BMPs that are
currently being implemented to prevent or reduce any pollutants that
are causing or contributing to the violation of Water Quality
Standards, including a qualitative assessment of the effectiveness of
each best management practice (BMP).
ii. A description of potential additional operational and/or structural
BMPs that will or may be implemented in order to apply AKART on a
site-specific basis to prevent or reduce any pollutants that are causing
or contributing to the violation of Water Quality Standards.
iii. A description of the potential monitoring or other assessment and
evaluation efforts that will or may be implemented to monitor, assess,
or evaluate the effectiveness of the additional BMPs.
iv. A schedule for implementing the additional BMPs including, as
appropriate: funding, training, purchasing, construction, monitoring,
and other assessment and evaluation components of implementation.
b. Ecology will, in writing, acknowledge receipt of the report within a
reasonable time and notify the Permittee when it expects to complete its
review of the report. Ecology will either approve the additional BMPs and
implementation schedule or require the Permittee to modify the report as
S4.G.1 S4.G.3
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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needed to meet AKART on a site-specific basis. If modifications are required,
Ecology will specify a reasonable time frame in which the Permittee shall
submit and Ecology will review the revised report.
c. The Permittee shall implement the additional BMPs, pursuant to the schedule
approved by Ecology, beginning immediately upon receipt of written
notification of approval.
d. The Permittee shall include with each subsequent annual report a summary of
the status of implementation and the results of any monitoring, assessment or
evaluation efforts conducted during the reporting period. If, based on the
information provided under this subsection, Ecology determines that
modification of the BMPs or implementation schedule is necessary to meet
AKART on a site-specific basis, the Permittee shall make such modifications
as Ecology directs. In the event there are ongoing violations of water quality
standards despite the implementation of the BMP approach of this section, the
Permittee may be subject to compliance schedules to eliminate the violation
under WAC 173-201A-510(4) and WAC 173-226-180 or other enforcement
orders as Ecology deems appropriate during the term of this permit.
e. A TMDL or other enforceable water quality cleanup plan that has been
approved and is being implemented to address the MS4’s contribution to the
Water Quality Standards violation supersedes and terminates the S4.F.3
implementation plan.
f. Provided the Permittee is implementing the approved adaptive management
response under this section, the Permittee remains in compliance with
Condition S4, despite any on-going violations of Water Quality Standards
identified under S4.A or B above.
g. The adaptive management process provided under Section S.4.F is not
intended to create a shield for the Permittee from any liability it may face
under 42 U.S.C. 9601 et seq. or chapter 70.105D RCW.
G. Ecology may modify or revoke and reissue this General Permit in accordance with
G14 General Permit Modification and Revocation, if Ecology becomes aware of
additional control measures, management practices or other actions beyond what is
required in this Permit that are necessary to:
1. Reduce the discharge of pollutants to the MEP,
2. Comply with the state AKART requirements, or
3. Control the discharge of toxicants to waters of the State of Washington.
S5.A.1 S5.A.3
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S5. STORMWATER MANAGEMENT PROGRAM FOR CITIES, TOWNS, AND
COUNTIES
A. Each Permittee shall develop and implement a Stormwater Management Program
(SWMP). A SWMP is a set of actions and activities comprising the components listed
in S5 and any additional actions necessary, to meet the requirements of applicable
TMDLs pursuant to S7 Compliance with TMDL Requirements, and S8 Monitoring
and Assessment. This section applies to all cities, towns, and counties covered under
this Permit, including cities, towns, and counties that are Co-Permittees. Where the
term “Permittee” is used in this section the requirements apply to all cities, towns, and
counties covered under this Permit.
New Permittees subject to this permit as described in S1.D.1.b shall fully meet the
requirements in S5 as modified in footnotes below, or as specified in an alternate
schedule as a condition of coverage by Ecology. Permittees obtaining coverage after
the issuance date of this permit shall fully meet the requirements in S5 as specified in
an alternate schedule as a condition of coverage by Ecology.
1. At a minimum the Permittee’s SWMP shall be implemented throughout the
geographic area subject to this Permit as described in S1.A.1
2. Each Permittee shall prepare written documentation of the SWMP, called the
SWMP Plan. The SWMP Plan shall be organized according to the program
components in S5.C or a format approved by Ecology, and shall be updated at
least annually for submittal with the Permittee’s annual reports to Ecology (see S9
Reporting and Record Keeping). The SWMP Plan shall be written to inform the
public of the planned SWMP activities for the upcoming calendar year, and shall
include a description of:
a. Planned activities for each of the program components included in S5.C.
b. Any additional planned actions to meet the requirements of applicable
TMDLs pursuant to S7 Compliance with Total Maximum Daily Load
Requirements.
c. Any additional planned actions to meet the requirements of S8 Monitoring.
3. The SWMP shall include an ongoing program for gathering, tracking,
maintaining, and using information to evaluate SWMP development,
implementation and permit compliance and to set priorities.
1 New Permittees shall fully develop and implement the SWMP in accordance with the schedules contained in this
section no later than February 2, 2018.
S5.A.4 S5.A.5
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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a. Each Permittee shall track the cost or estimated cost of development and
implementation of each component of the SWMP.2 This information shall be
provided to Ecology upon request.
b. Each Permittee shall track the number of inspections, official enforcement
actions and types of public education activities as required by the respective
program component. This information shall be included in the annual report.
4. Permittees shall continue implementation of existing stormwater management
programs until they begin implementation of the updated stormwater management
program in accordance with the terms of this permit, including implementation
schedules.
5. Coordination among Permittees
a. Coordination among entities covered under municipal stormwater NPDES
permits may be necessary to comply with certain conditions of the SWMP.
The SWMP should include, when needed, coordination mechanisms among
entities covered under a municipal stormwater NPDES permit to encourage
coordinated stormwater-related policies, programs and projects within
adjoining or shared areas, including:
i. Coordination mechanisms clarifying roles and responsibilities for the
control of pollutants between physically interconnected MS4s covered
by a municipal stormwater permit.
ii. Coordinating stormwater management activities for shared water
bodies among Permittees to avoid conflicting plans, policies and
regulations.
b. The SWMP shall include coordination mechanisms among departments within
each jurisdiction to eliminate barriers to compliance with the terms of this
permit. Permittees shall include a written description of internal coordination
mechanisms in the Annual Report due no later than March 31, 2015.
B. The SWMP shall be designed to reduce the discharge of pollutants from regulated
small MS4s to the MEP, meet state AKART requirements, and protect water quality.
C. The SWMP shall include the components listed below. To the extent allowable under
state or federal law, all components are mandatory for city, town or county Permittees
covered under this permit.
2 New Permittees shall begin implementing the requirements of S5.A.3.a no later than August 1, 2015.
S5.C.1 S5.C.1
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1. Public Education and Outreach
The SWMP shall include an education and outreach program designed to reduce
or eliminate behaviors and practices that cause or contribute to adverse
stormwater impacts and encourage the public to participate in stewardship
activities. The education program may be developed and implemented locally or
regionally.
The minimum performance measures are:
a. Each Permittee shall provide an education and outreach program for the area
served by the MS4. The program shall be designed to educate target audiences
about the stormwater problem and provide specific actions they can follow to
minimize the problem.3
i. To build general awareness, Permittees shall select from the following
target audiences and subject areas:
(a) General public (including school age children), and businesses
(including home-based and mobile businesses)
• General impacts of stormwater on surface waters.
• Impacts from impervious surfaces.
• Impacts of illicit discharges and how to report them.
• Low impact development (LID) principles and LID BMPs.
• Opportunities to become involved in stewardship
activities.
(b) Engineers, contractors, developers and land use planners
• Technical standards for stormwater site and erosion
control plans.
• LID principles and LID BMPs.
• Stormwater treatment and flow control BMPs/facilities.
ii. To effect behavior change, Permittees shall select from the following
target audiences and BMPs:
3 New Permittees shall begin implementing the requirements of S5.C.1 no later than August 1, 2015.
S5.C.2 S5.C.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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(a) General public (which may include school age children),
businesses (including home-based and mobile businesses)
• Use and storage of automotive chemicals, hazardous
cleaning supplies, carwash soaps and other hazardous
materials.
• Equipment maintenance.
• Prevention of illicit discharges.
(b) Residents, landscapers and property managers/owners
• Yard care techniques protective of water quality.
• Use and storage of pesticides and fertilizers and other
household chemicals.
• Carpet cleaning and auto repair and maintenance.
• Vehicle, equipment and home/building maintenance.
• Pet waste management and disposal.
• LID principles and LID BMPs.
• Stormwater facility maintenance.
• Dumpster and trash compactor maintenance.
b. Each Permittee shall create stewardship opportunities and/or partner with
existing organizations to encourage residents to participate in activities such
as stream teams, storm drain marking, volunteer monitoring, riparian plantings
and education activities.
c. Each Permittee shall measure the understanding and adoption of the targeted
behaviors for at least one target audience in at least one subject area. No later
than February 2, 2016, Permittees shall use the resulting measurements to
direct education and outreach resources most effectively, as well as to
evaluate changes in adoption of the targeted behaviors.4 Permittees may meet
this requirement individually or as a member of a regional group.
4 By no later than August 1, 2017, new Permittees shall begin using the results of measurements to direct education
and outreach resources more effectively, as well as to evaluate changes in adopted behaviors.
S5.C.2 S5.C.3
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 19 of 74
2. Public Involvement and Participation
Permittees shall provide ongoing opportunities for public involvement and
participation through advisory councils, public hearings, watershed committees,
participation in developing rate-structures or other similar activities. Each
Permittee shall comply with applicable state and local public notice requirements
when developing elements of the SWMP.
The minimum performance measures are:
a. Permittees shall create opportunities for the public to participate in the
decision-making processes involving the development, implementation and
update of the Permittee’s SWMP.5
b. Each Permittee shall post on their website their SWMP Plan and the annual
report required under S9.A no later than May 31 each year. All other
submittals shall be available to the public upon request. To comply with the
posting requirement, a Permittee that does not maintain a website may submit
the updated SWMP in electronic format to Ecology for posting on Ecology’s
website.
3. Illicit Discharge Detection and Elimination
The SWMP shall include an ongoing program designed to prevent, detect,
characterize, trace and eliminate illicit connections and illicit discharges into the
MS4.
The minimum performance measures are:
a. Mapping of the MS4 shall continue on an ongoing basis.6 MS4 maps shall be
periodically updated. Update maps if necessary to meet the requirements of
this section no later than February 2, 2018. At a minimum, maps shall include
the following information:
i. Known MS4 outfalls and known MS4 discharge points.
ii. Receiving waters, other than ground water.
iii. Stormwater treatment and flow control BMPs/facilities owned or
operated by the Permittee.
5 New Permittees shall develop and begin to implement requirements of S5.C.2.a no later than August 1, 2014.
6 New Permittees shall meet the requirements to map the MS4 according to S5.C.3.a no later than February 2, 2018,
except where otherwise noted in this section.
S5.C.3 S5.C.3
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 20 of 74
iv. Tributary conveyances to all known outfalls and discharge points with
a 24 inch nominal diameter or larger, or an equivalent cross-sectional
area for non-pipe systems. The following attributes shall be mapped:
• Tributary conveyance type, material, and size where known.
• Associated drainage areas.
• Land use.
v. All connections to the MS4 authorized or allowed by the Permittee
after February 16, 2007.7
vi. Connections between the MS4 owned or operated by the Permittee and
other municipalities or public entities.
vii. Geographic areas served by the Permittee’s MS4 that do not discharge
stormwater to surface waters.
viii. To the extent consistent with national security laws and directives,
each Permittee shall make available to Ecology upon request, MS4
map(s) depicting the information required in S5.C.3.a.i through vi
above. The preferred format for mapping will be an electronic format
with fully described mapping standards. An example description is
available on Ecology website.
ix. Upon request, and to the extent appropriate, Permittees shall provide
mapping information to federally-recognized Indian Tribes,
municipalities, and other Permittees. This permit does not preclude
Permittees from recovering reasonable costs associated with fulfilling
mapping information requests by federally-recognized Indian Tribes,
municipalities, and other Permittees.
b. Each Permittee shall implement an ordinance or other regulatory mechanism
to effectively prohibit non-stormwater, illicit discharges into the Permittee’s
MS4 to the maximum extent allowable under state and federal law.8
i. Allowable Discharges: The regulatory mechanism does not need to
prohibit the following categories of non-stormwater discharges:
• Diverted stream flows
• Rising ground waters
7 New Permittees shall meet the requirements of S5.C.3.a.v. after August 1, 2013 for all connections to the MS4
authorized after August 1, 2013.
8 New Permittees shall meet the requirements of S5.C.3.b no later than February 2, 2016.
S5.C.3 S5.C.3
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Modified January 16, 2015
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• Uncontaminated ground water infiltration (as defined at 40
CFR 35.2005(b)(20))
• Uncontaminated pumped ground water
• Foundation drains
• Air conditioning condensation
• Irrigation water from agricultural sources that is commingled
with urban stormwater
• Springs
• Uncontaminated water from crawl space pumps
• Footing drains
• Flows from riparian habitats and wetlands
• Non-stormwater discharges authorized by another NPDES or
state waste discharge permit
• Discharges from emergency fire fighting activities in
accordance with S2 Authorized Discharges
ii. Conditionally Allowable Discharges: The regulatory mechanism may
allow the following categories of non-stormwater discharges only if
the stated conditions are met:
• Discharges from potable water sources, including but not
limited to water line flushing, hyperchlorinated water line
flushing, fire hydrant system flushing, and pipeline hydrostatic
test water. Planned discharges shall be dechlorinated to a total
residual chlorine concentration of 0.1 ppm or less, pH-adjusted,
if necessary, and volumetrically and velocity controlled to
prevent re-suspension of sediments in the MS4.
• Discharges from lawn watering and other irrigation runoff.
These discharges shall be minimized through, at a minimum,
public education activities (see section S5.C.1) and water
conservation efforts.
• Dechlorinated swimming pool, spa and hot tub discharges. The
discharges shall be dechlorinated to a total residual chlorine
concentration of 0.1 ppm or less, pH-adjusted and
reoxygenized if necessary, volumetrically and velocity
controlled to prevent re-suspension of sediments in the MS4.
S5.C.3 S5.C.3
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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Discharges shall be thermally controlled to prevent an increase
in temperature of the receiving water. Swimming pool cleaning
wastewater and filter backwash shall not be discharged to the
MS4.
• Street and sidewalk wash water, water used to control dust, and
routine external building washdown that does not use
detergents. The Permittee shall reduce these discharges
through, at a minimum, public education activities (see section
S5.C.1) and/or water conservation efforts. To avoid washing
pollutants into the MS4, Permittees shall minimize the amount
of street wash and dust control water used.
• Other non-stormwater discharges. The discharges shall be in
compliance with the requirements of a pollution prevention
plan reviewed by the Permittee, which addresses control of
such discharges.
iii. The Permittee shall further address any category of discharges in (i) or
(ii) above if the discharges are identified as significant sources of
pollutants to waters of the State.
iv. The ordinance or other regulatory mechanism shall include escalating
enforcement procedures and actions.
v. The Permittee shall implement a compliance strategy that includes
informal compliance actions such as public education and technical
assistance as well as the enforcement provisions of the ordinance or
other regulatory mechanism. To implement an effective compliance
strategy, the Permittee’s ordinance or other regulatory mechanism may
need to include the following tools:
• The application of operational and/or structural source control
BMPs for pollutant generating sources associated with existing
land uses and activities where necessary to prevent illicit
discharges. The source control BMPs referenced in this subsection
are in Volume IV of the Stormwater Management Manual for
Western Washington, or an equivalent manual approved by
Ecology under the 2013 Phase I Permit.
• The maintenance of stormwater facilities which discharge into the
Permittee’s MS4 in accordance with maintenance standards
established under S5.C.4 and/or S5.C.5 where necessary to prevent
illicit discharges.
S5.C.3 S5.C.3
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Modified January 16, 2015
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vi. The Permittee’s ordinance or other regulatory mechanism in effect as
of the effective date of this permit shall be revised if necessary to meet
the requirements of this section no later than February 2, 2018.
c. Each Permittee shall implement an ongoing program designed to detect and
identify non-stormwater discharges and illicit connections into the Permittee’s
MS4.9 The program shall include the following components:
i. Procedures for conducting investigations of the Permittee’s MS4,
including field screening and methods for identifying potential
sources.
The Permittee shall implement a field screening methodology
appropriate to the characteristics of the MS4 and water quality
concerns. Screening for illicit connections may be conducted using:
Illicit Discharge Detection and Elimination: A Guidance Manual for
Program Development and Technical Assessments, Center for
Watershed Protection, October 2004, or another methodology of
comparable or improved effectiveness. The Permittee shall document
the field screening methodology in the relevant Annual Report.
All Permittees, except for the City of Aberdeen, shall complete field
screening for at least 40% of the MS4 no later than December 31,
2017,10 and on average 12% each year thereafter. The City of
Aberdeen shall complete field screening for at least 40% of the system
no later than June 30, 2018 and on average 12% each year thereafter.
ii. A publicly listed and publicized hotline or other telephone number for
public reporting of spills and other illicit discharges.11
iii. An ongoing training program for all municipal field staff, who, as part
of their normal job responsibilities, might come into contact with or
otherwise observe an illicit discharge and/or illicit connection to the
MS4, on the identification of an illicit discharge and/or connection,
and on the proper procedures for reporting and responding to the illicit
discharge and/or connection. Follow-up training shall be provided as
needed to address changes in procedures, techniques, requirements, or
9 New Permittees shall fully implement the requirements of S5.C.3.c no later than February 2, 2018, except where
otherwise noted in this section.
10 New Permittees shall complete S5.C.3.c.i requirements for field screening covering at least 12% of the MS4
within the Permittee’s coverage area no later than December 31, 2017, and on average 12% each year thereafter.
11 New Permittees shall implement the requirements of S5.C.3.c.ii no later than August 1, 2015.
S5.C.3 S5.C.3
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Modified January 16, 2015
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staffing. Permittees shall document and maintain records of the
trainings provided and the staff trained.12
iv. Permittees shall inform public employees, businesses, and the general
public of hazards associated with illicit discharges and improper
disposal of waste.13
d. Each Permittee shall implement an ongoing program designed to address
illicit discharges, including spills and illicit connections, into the Permittee’s
MS4.14 The program shall include:
i. Procedures for characterizing the nature of, and potential public or
environmental threat posed by, any illicit discharges found by or
reported to the Permittee. Procedures shall address the evaluation of
whether the discharge must be immediately contained and steps to be
taken for containment of the discharge.
ii. Procedures for tracing the source of an illicit discharge; including
visual inspections, and when necessary, opening manholes, using
mobile cameras, collecting and analyzing water samples, and/or other
detailed inspection procedures.
iii. Procedures for eliminating the discharge; including notification of
appropriate authorities; notification of the property owner; technical
assistance; follow-up inspections; and use of the compliance strategy
developed pursuant to S5.C.3.b.v, including escalating enforcement
and legal actions if the discharge is not eliminated.
iv. Compliance with the provisions in (i), (ii), and (iii), above, shall be
achieved by meeting the following timelines:
• Immediately respond to all illicit discharges, including spills,
which are determined to constitute a threat to human health,
welfare, or the environment, consistent with General Condition
G3.
• Investigate (or refer to the appropriate agency with the authority to
act) within 7 days, on average, any complaints, reports or
monitoring information that indicates a potential illicit discharge.
12 New Permittees shall develop and begin implementing the ongoing training program described in S5.C.3.c.iii no
later than February 2, 2016.
13 New Permittees shall inform public employees, businesses, and the general public of hazards associated with
illicit discharges no later than February 2, 2017.
14 New Permittees shall fully develop and implement the requirements of S5.C.3.d no later than February 2, 2018.
S5.C.4 S5.C.4
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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• Initiate an investigation within 21 days of any report or discovery
of a suspected illicit connection to determine the source of the
connection, the nature and volume of discharge through the
connection, and the party responsible for the connection.
• Upon confirmation of an illicit connection, use the compliance
strategy in a documented effort to eliminate the illicit connection
within 6 months. All known illicit connections to the MS4 shall be
eliminated.
e. Permittees shall train staff who are responsible for identification,
investigation, termination, cleanup, and reporting of illicit discharges,
including spills, and illicit connections, to conduct these activities. Follow-up
training shall be provided as needed to address changes in procedures,
techniques, requirements or staffing. Permittees shall document and maintain
records of the training provided and the staff trained.15
f. Recordkeeping: Permittees shall track and maintain records of the activities
conducted to meet the requirements of this section.
4. Controlling Runoff from New Development, Redevelopment and
Construction Sites
Each Permittee shall implement and enforce a program to reduce pollutants
in stormwater runoff to a regulated small MS4 from new development,
redevelopment and construction site activities. The program shall apply to
private and public development, including roads.16
The minimum performance measures are:
a. Implement an ordinance or other enforceable mechanism that addresses runoff
from new development, redevelopment, and construction site projects. Except
for Permittees in Lewis and Cowlitz Counties and the City of Aberdeen, the
ordinance or other enforceable mechanism to implement (i) through (iii),
below, shall be adopted and effective no later than December 31, 2016. The
local program adopted to meet the requirements of S5.C.4.a(i) through (iii),
below shall apply to all applications 17 submitted on or after January 1, 2017
and shall apply to applications submitted prior to January 1, 2017, which have
15 New Permittees shall meet the requirements of S5.C.3.e no later than February 2, 2016.
16 New Permittees shall meet the requirements of S5.C.4 no later than December 31, 2017, except where otherwise
specified in this section.
17 In this context, “application” means, at a minimum a complete project description, site plan, and, if applicable,
SEPA checklist. Permittees may establish additional elements of a completed application.
S5.C.4 S5.C.4
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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not started construction 18 by January 1, 2022 19.
For Permittees in Lewis and Cowlitz Counties the ordinance or other
enforceable mechanism to implement (i) through (iii), below, shall be
adopted and effective no later than June 30, 2017. The local program adopted to
meet the requirements of S5.C.4.a(i) through (iii), below shall apply to all
applications submitted on or after July 1, 2017 and shall apply to applications
submitted prior to July 1, 2017, which have not started construction by June 30,
2022.
For the City of Aberdeen the ordinance or other enforceable mechanism to
implement (i) through (iii), below, shall be adopted and effective no later than
June 30, 2018. The local program adopted to meet the requirements of
S5.C.4.a(i) through (iii), below shall apply to all applications submitted on or
after July 1, 2018 and shall apply to applications submitted prior to July 1,
2018, which have not started construction by June 30, 2023.
The ordinance or other enforceable mechanism shall include, at a minimum:
i. The Minimum Requirements, thresholds, and definitions in Appendix
1 or a program approved by Ecology under the 2013 NPDES Phase I
Municipal Stormwater Permit, for new development, redevelopment,
and construction sites. Adjustment and variance criteria equivalent to
those in Appendix 1 shall be included. More stringent requirements
may be used, and/or certain requirements may be tailored to local
circumstances through the use of Ecology-approved basin plans or
other similar water quality and quantity planning efforts. Such local
requirements and thresholds shall provide equal protection of receiving
waters and equal levels of pollutant control to those provided in
Appendix 1.
ii. The local requirements shall include the following requirements,
limitations, and criteria that, when used to implement the minimum
requirements in Appendix 1 (or program approved by Ecology under
the 2013 Phase I Permit) will protect water quality, reduce the
18 In this context “started construction” means the site work associated with, and directly related to the approved
project has begun. For example: grading the project site to final grade or utility installation. Simply clearing the
project site does not constitute the start of construction. Permittees may establish additional requirements related to
the start of construction.
19 New Permittees shall meet the requirements of S5.C.4.a no later than December 31, 2017. The local program shall
apply to all applications submitted on or after January 1, 2018 and shall apply to applications submitted prior to
January 1, 2018, which have not started construction by January 1, 2023.
S5.C.4 S5.C.4
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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discharge of pollutants to the MEP, and satisfy the State requirement
under chapter 90.48 RCW to apply AKART prior to discharge:
(a) Site planning requirements
(b) BMP selection criteria
(c) BMP design criteria
(d) BMP infeasibility criteria
(e) LID competing needs criteria
(f) BMP limitations
Permittees shall document how the criteria and requirements will
protect water quality, reduce the discharge of pollutants to the MEP,
and satisfy State AKART requirements.
Permittees who choose to use the requirements, limitations, and
criteria above in the Stormwater Management Manual for Western
Washington, or a program approved by Ecology under the 2013 Phase
I Permit, may cite this choice as their sole documentation to meet this
requirement.
iii. The legal authority, through the approval process for new development
and redevelopment, to inspect and enforce maintenance standards for
private stormwater facilities approved under the provisions of this
section that discharge to the Permittee’s MS4.
b. The program shall include a permitting process with site plan review,
inspection and enforcement capability to meet the standards listed in (i)
through (iv) below, for both private and public projects, using qualified
personnel (as defined in Definitions and Acronyms). At a minimum, this
program shall be applied to all sites that meet the minimum thresholds
adopted pursuant to S5.C.4.a.i, above.
i. Review of all stormwater site plans for proposed development
activities.
ii. Inspect, prior to clearing and construction, all permitted development
sites that have a high potential for sediment transport as determined
through plan review based on definitions and requirements in
Appendix 7 Determining Construction Site Sediment Damage
Potential. As an alternative to evaluating each site according to
Appendix 7, Permittees may choose to inspect all construction sites
that meet the minimum thresholds adopted pursuant to S5.C.4.a.i,
above.
S5.C.4 S5.C.4
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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iii. Inspect all permitted development sites during construction to verify
proper installation and maintenance of required erosion and sediment
controls. Enforce as necessary based on the inspection.
iv. Inspect all permitted development sites upon completion of
construction and prior to final approval or occupancy to ensure proper
installation of permanent stormwater facilities. Verify that a
maintenance plan is completed and responsibility for maintenance is
assigned for stormwater treatment and flow control BMPs/facilities.
Enforce as necessary based on the inspection.
v. Compliance with the inspection requirements in (ii), (iii) and (iv)
above, shall be determined by the presence and records of an
established inspection program designed to inspect all sites.
Compliance during this permit term shall be determined by achieving
at least 80% of scheduled inspections.
vi. An enforcement strategy shall be implemented to respond to issues of
non-compliance.
c. The program shall include provisions to verify adequate long-term operation
and maintenance (O&M) of stormwater treatment and flow control
BMPs/facilities that are permitted and constructed pursuant to (b) above.
Except for Permittees located in Lewis or Cowlitz Counties and the City of
Aberdeen, these provisions shall be in place no later than December 31, 2016.
20 For Permittees in Lewis and Cowlitz Counties, the provisions shall be in
place no later than June 30, 2017. For the City of Aberdeen, the provisions
shall be in place no later than June 30, 2018. The provisions shall include:
i. Implementation of an ordinance or other enforceable mechanism that
clearly identifies the party responsible for maintenance, requires
inspection of facilities in accordance with the requirements in (ii)
through (iv) below, and establishes enforcement procedures.
ii. Each Permittee shall establish maintenance standards that are as
protective or more protective of facility function than those specified
in Chapter 4 of Volume V of the Stormwater Management Manual for
Western Washington. For facilities which do not have maintenance
standards, the Permittee shall develop a maintenance standard.
The purpose of the maintenance standard is to determine if
maintenance is required. The maintenance standard is not a measure of
the facility’s required condition at all times between inspections.
20 New Permittees shall meet the requirements of S5.C.4.c no later than December 31, 2017.
S5.C.4 S5.C.4
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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Exceeding the maintenance standard between the period of inspections
is not a permit violation.
iii. Annual inspections of all stormwater treatment and flow control
BMPs/facilities that discharge to the MS4 and were permitted by the
Permittee according to S5.C.4.b, including those permitted in
accordance with requirements adopted pursuant to the 2007-2012
Ecology municipal stormwater permits, unless there are maintenance
records to justify a different frequency.
Permittees may reduce the inspection frequency based on maintenance
records of double the length of time of the proposed inspection
frequency. In the absence of maintenance records, the Permittee may
substitute written statements to document a specific less frequent
inspection schedule. Written statements shall be based on actual
inspection and maintenance experience and shall be certified in
accordance with G19 Certification and Signature.
iv. Inspections of all permanent stormwater treatment and flow control
BMPs/facilities and catch basins in new residential developments
every six months until 90% of the lots are constructed (or when
construction is stopped and the site is fully stabilized) to identify
maintenance needs and enforce compliance with maintenance
standards as needed.
v. Compliance with the inspection requirements in (iii) and (iv) above
shall be determined by the presence and records of an established
inspection program designed to inspect all sites. Compliance during
this permit term shall be determined by achieving at least 80% of
scheduled inspections.
vi. Unless there are circumstances beyond the Permittee’s control, when
an inspection identifies an exceedance of the maintenance standard,
maintenance shall be performed:
• Within 1 year for typical maintenance of facilities, except
catch basins.
• Within 6 months for catch basins.
• Within 2 years for maintenance that requires capital
construction of less than $25,000.
Circumstances beyond the Permittee’s control include denial or
delay of access by property owners, denial or delay of necessary
permit approvals, and unexpected reallocations of maintenance staff
to perform emergency work. For each exceedance of the required
S5.C.4 S5.C.4
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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timeframe, the Permittee shall document the circumstances and how
they were beyond their control.
vii. The program shall include a procedure for keeping records of
inspections and enforcement actions by staff, including inspection
reports, warning letters, notices of violations, and other enforcement
records. Records of maintenance inspections and maintenance
activities shall be maintained.
d. The program shall make available as applicable copies of the "Notice of Intent
for Construction Activity" and copies of the "Notice of Intent for Industrial
Activity" to representatives of proposed new development and redevelopment.
Permittees shall continue to enforce local ordinances controlling runoff from
sites that are also covered by stormwater permits issued by Ecology.21
e. Each Permittee shall ensure that all staff whose primary job duties are
implementing the program to control stormwater runoff from new
development, redevelopment, and construction sites, including permitting,
plan review, construction site inspections, and enforcement, are trained to
conduct these activities. Follow-up training shall be provided as needed to
address changes in procedures, techniques or staffing. Permittees shall
document and maintain records of the training provided and the staff trained.22
f. Low impact development code-related requirements.
i. No later than December 31, 2016,23 Permittees shall review, revise and
make effective their local development-related codes, rules, standards,
or other enforceable documents to incorporate and require LID
principles and LID BMPs. For Permittees in Lewis and Cowlitz
Counties, the deadline for this requirement is no later than June 30,
2017; for the City of Aberdeen, the deadline for this requirement is no
later than June 30, 2018.
The intent of the revisions shall be to make LID the preferred and
commonly-used approach to site development. The revisions shall be
designed to minimize impervious surfaces, native vegetation loss, and
stormwater runoff in all types of development situations. Permittees
shall conduct a similar review and revision process, and consider the
range of issues, outlined in the following document: Integrating LID
21 New Permittees shall meet the requirements of S5.C.4.d beginning no later than August 1, 2013.
22 New Permittees shall meet the requirements of S5.C.4.e no later than December 31, 2017.
23 New Permittees shall meet the requirements of S5.C.4.f.i no later than December 31, 2017.
S5.C.4 S5.C.4
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
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into Local Codes: A Guidebook for Local Governments (Puget Sound
Partnership, 2012).
ii. Except for Permittees in Lewis and Cowlitz Counties and the City of
Aberdeen, each Permittee shall submit a summary of the results of the
review and revision process in (i) above with the annual report due no
later than March 31, 2017 24. Permittees in Lewis and Cowlitz Counties
shall submit the summary with the annual report due no later than
March 31, 2018. The City of Aberdeen shall submit the summary with
the Fifth Year annual report. This summary shall include, at a
minimum, a list of the participants (job title, brief job description, and
department represented), the codes, rules, standards, and other
enforceable documents reviewed, and the revisions made to those
documents which incorporate and require LID principles and LID
BMPs. The summary shall include existing requirements for LID
principles and LID BMPs in development-related codes. The summary
shall be organized as follows:
(a) Measures to minimize impervious surfaces;
(b) Measures to minimize loss of native vegetation; and
(c) Other measures to minimize stormwater runoff.
g. Watershed-scale stormwater planning
The objective of watershed-scale stormwater planning is to identify a
stormwater management strategy or strategies that would result in hydrologic
and water quality conditions that fully support “existing uses,” and
“designated uses,” as those terms are defined in WAC 173-201A-020,
throughout the stream system.
Each City or County Permittee 25 that has all or part of its coverage area in a
watershed selected by a Phase I county for watershed-scale stormwater
planning under condition S5.C.5.c of the Phase I Municipal Stormwater
Permit must fully participate in the watershed-scale stormwater planning
process as described in S5.C.4.g, below. Permittees may choose to participate
in a coordinated scope of work and schedule with one or more of the
Permittees within the selected watershed, or conduct their scope of work
independently.
24 New Permittees shall meet the S5.C.4.f.ii reporting requirement in the annual report covering calendar year 2017
and due no later than March 31, 2018.
25 This section applies to the Phase II Permittees within King County’s selected watershed: the cities of Redmond
and Woodinville. Bothell has minimal acreage in the Snohomish County watershed and is not required to
participate.
S5.C.4 S5.C.4
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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i. No later than August 13, 2015, each Permittee within a selected
watershed must submit to Ecology documentation of its approach to
coordinate with other Permittees within the watershed, including:
(a) A list of the municipal stormwater Permittees with whom the
Permittee will undertake watershed-scale planning under a
common scope of work; and a description of the coordination
and dispute resolution procedures agreed to by all of the
Permittees operating under the common scope of work; and
(b) A description of planned coordination and dispute resolution
procedures for providing and receiving feedback from
Permittees operating under different scopes of work within the
same watershed, including procedures to:
1) Review, provide comment, and revise methods and
assumptions to meet S5.C.4.g.ii (a) through (d);
2) Review, provide comment, and revise present- and future-
condition B-IBI scores, pollutant concentrations, temperature
and hydrologic metrics used for calibrating the model;
3) Share the results of the modeling performed by the Permittee
with all other Permittees in the watershed;
4) Adjust the Permittee’s proposed changes to development-
related codes, rules, standards, plans, and potential future
structural stormwater control projects in response to feedback
so that the planning objectives, as described in S5.C.4.g
above, are projected to be met throughout the watershed.
(c) It is not a permit violation if other entities, over whose actions
the Permittee has limited or no control, refuse to participate in
the coordination plan described in S5.C.4.g.i.
ii. No later than November 4, 2015 the Permittee must submit a scope of
work and a schedule to Ecology for the complete watershed-scale
stormwater planning process. The scope of work and schedule are
subject to Ecology’s review and approval. If Ecology takes longer than
90 days to provide a written response, the required deadline for
submitting a final watershed-scale stormwater plan to Ecology will be
automatically extended by the number of days Ecology exceeds 90
days, but no later than July 30, 2018.
The scope of work and schedule must apply to the geographic extent
of the jurisdictions of the Permittees listed under S5.C.4.g.i (a) above
and, at a minimum, describe:
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(a) An assessment of existing hydrologic, biologic, and water
quality conditions within the selected watershed, and an
assessment of the current status of the aquatic community. This
assessment can be based on existing data where such data are
available. Where such data are not available, or are not
sufficient, the scope of work and schedule must include the
collection of such data.
The existing conditions assessment must, at a minimum, include
the following:
1) Water quality conditions as established through sampling
during base flows and storm flows for, at a minimum, the
following chemical parameters: dissolved copper, dissolved
zinc, temperature, and fecal coliform. Permittees must
identify or collect data from locations upgradient and
downgradient of stream sections influenced by MS4
discharges.
2) Continuous flow monitoring of the stream to provide the data
necessary to calibrate a continuous runoff model to the
selected watershed. Permittees must identify or collect flow
monitoring data from locations upgradient and downgradient
of stream sections influenced by MS4 discharges.
3) Macroinvertebrate data for the purpose of estimating current
Benthic Index of Biotic Integrity (B-IBI) scores and
comparing them with the scores predicted by the existing
values of the hydrologic metrics in S5.C.4.g.ii (d).
4) The status of the aquatic community, including the presence
and distribution of salmonid uses, using data from existing
sources.
(b) Efforts to compile and/or generate maps of the selected
watershed to identify the existing distribution and totals of
general soil types, vegetative land cover, impervious land
covers, and regulated and other MS4s. Maps must be sufficient
to allow construction of a rainfall/runoff model representation of
the watershed. Maps must also identify areas within the
watershed appropriate for special attention in regard to
hydrologic and water quality impacts. For example: headwater
wetlands and critical aquifer recharge areas.
(c) How the Permittee will use the existing conditions assessment
from S5.C.4.g.ii (a) and the maps described in S5.C.4.g.ii (b) to
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calibrate a continuous runoff model to reflect the existing
hydrologic, water quality, and biologic (as represented by B-IBI
score) conditions.
(d) How the Permittee will use the model calibrated in S5.C.4.g.ii
(c) to estimate hydrologic changes from the historic condition;
and to predict the future hydrologic, biologic, and water quality
conditions at full build-out under existing or proposed
comprehensive land use management plan(s) for the watershed.
Future biologic conditions must be estimated by using a
correlation of hydrologic metrics with B-IBI scores for Puget
Sound Lowland Streams 26, or other similar correlation if
approved by Ecology. Future water quality conditions must be
described through estimation of concentrations of, at a
minimum, dissolved copper, dissolved zinc, temperature, and
fecal coliform.
(e) How, if the estimation in S5.C.4.g.ii (d) predicts water quality
standards will not be met, the Permittee will use the calibrated
watershed model to evaluate stormwater management strategies
to meet the standards. The same hydrologic metrics and
correlated B-IBI scores, and water quality parameters used in
S5.C.4.g.ii (d) must be used to evaluate the effectiveness of
strategies.
1) Stormwater management strategies to be evaluated for all
jurisdictions in the watershed must include:
• Changes to development-related codes, rules, standards,
and plans.
• Potential future structural stormwater control projects.
2) Stormwater management strategies evaluated may also
include:
• Basin-specific stormwater control requirements for new
development and redevelopment as allowed by Section 7
of Appendix 1.
• Strategies to encourage redevelopment and infill, and an
assessment of options for efficient, effective runoff
26 DeGasperi, C.L., Berge, H. B., Whiting, K. R., Burkey, J. J., Cassin, J. L. and Fuerstenberg, R. R. (2009), Linking
Hydrologic Alteration to Biological Impairment in Urbanizing Streams of the Puget Lowland, Washington, USA.
JAWRA Journal of the American Water Resources Association, 45: 512-533. Doi: 10.1111/j.1752-
1688.2009.00306.x
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controls for redevelopment projects, such as regional
facilities, in lieu of individual site requirements.
(f) How the permittee will create an implementation plan and
schedule that includes: potential future actions to implement the
identified stormwater management strategies, responsible
parties, estimated costs, and potential funding mechanisms.
(g) A public review and comment process that, at a minimum,
focuses on the draft watershed-scale stormwater plan. The public
review must allow for public comment from all governmental
entities with jurisdiction within the watershed.
iii. The watershed-scale stormwater planning process, as documented in
the scope of work and schedule, may include an evaluation of
strategies to preserve or improve other factors that influence
maintenance of the existing and designated uses of the stream.
Examples include: channel restoration, in-stream culvert replacement,
quality of the riparian zone, gravel disturbance regime, and presence
and distribution of large woody debris.
iv. Each Permittee (or group of Permittees operating under a single scope
of work, as described above) must submit a final watershed-scale
stormwater plan to Ecology no later April 4, 2018. The plan must
summarize results of the modeling and planning process, describe
results of the evaluation of strategies under S5.C.4.g.ii (e), and include
the implementation plan and schedule developed pursuant to
S5.C.4.g.ii (f).
5. Municipal Operations and Maintenance
Each Permittee shall implement an operations and maintenance (O&M) program
that includes a training component and has the ultimate goal of preventing or
reducing pollutant runoff from municipal operations.27
The minimum performance measures are:
a. Each Permittee shall implement maintenance standards that are as protective,
or more protective, of facility function than those specified in Chapter 4 of
Volume V of the Stormwater Management Manual for Western Washington.
For facilities which do not have maintenance standards, the Permittee shall
develop a maintenance standard. Except for Permittees located in Lewis and
27 New Permittees shall develop and implement the requirements of S5.C.5 no later than December 31, 2017 except
where otherwise noted in this section.
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Cowlitz Counties and the City of Aberdeen, no later than December 31, 2016,
Permittees shall update their maintenance standards as necessary to meet the
requirements of this section.28 For Permittees in Lewis and Cowlitz Counties,
this requirement shall apply no later than June 30, 2017; for the City of
Aberdeen this requirement shall apply no later than June 30, 2018.
i. The purpose of the maintenance standard is to determine if
maintenance is required. The maintenance standard is not a measure of
the facility’s required condition at all times between inspections.
Exceeding the maintenance standard between inspections and/or
maintenance is not a permit violation.
ii. Unless there are circumstances beyond the Permittee’s control, when
an inspection identifies an exceedance of the maintenance standard,
maintenance shall be performed:
• Within 1 year for typical maintenance of facilities, except catch
basins.
• Within 6 months for catch basins.
• Within 2 years for maintenance that requires capital
construction of less than $25,000.
Circumstances beyond the Permittee’s control include denial or
delay of access by property owners, denial or delay of necessary
permit approvals, and unexpected reallocations of maintenance staff
to perform emergency work. For each exceedance of the required
timeframe, the Permittee shall document the circumstances and how
they were beyond their control.
b. Annual inspection of all municipally owned or operated permanent
stormwater treatment and flow control BMPs/facilities, and taking appropriate
maintenance actions in accordance with the adopted maintenance standards.29
Permittees may reduce the inspection frequency based on maintenance records
of double the length of time of the proposed inspection frequency. In the
absence of maintenance records, the Permittee may substitute written
statements to document a specific less frequent inspection schedule. Written
28 New Permittees shall adopt the updated maintenance standards in Chapter 4 of Volume V of the Stormwater
Management Manual for Western Washington or an Ecology-approved program under the 2013 Phase I Permit no
later than December 31, 2017.
29 New Permittees shall begin annual inspections of municipally owned or operated stormwater treatment and flow
control facilities/BMPs no later than December 31, 2017.
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statements shall be based on actual inspection and maintenance experience
and shall be certified in accordance with G19 Certification and Signature.
c. Spot checks of potentially damaged permanent stormwater treatment and flow
control BMPs/facilities after major storm events (24 hour storm event with a
10 year or greater recurrence interval). If spot checks indicate widespread
damage/maintenance needs, inspect all stormwater treatment and flow control
BMPs/facilities that may be affected. Conduct repairs or take appropriate
maintenance action in accordance with maintenance standards established
above, based on the results of the inspections.
d. Except for the City of Aberdeen, inspection of all catch basins and inlets
owned or operated by the Permittee at least once no later than August 1, 2017
and every two years thereafter. 30 For the City of Aberdeen, the deadline for
this requirement shall be no later than June 30, 2018. Clean catch basins if the
inspection indicates cleaning is needed to comply with maintenance standards
established in the Stormwater Management Manual for Western Washington.
Decant water shall be disposed of in accordance with Appendix 6 Street Waste
Disposal.
The following alternatives to the standard approach of inspecting all catch
basins once no later than August 1, 2017 and every two years thereafter
(except no later than June 30, 2018 and every two years thereafter for the City
of Aberdeen) may be applied to all or portions of the system:
i. The catch basin inspection schedule of every two years may be
changed as appropriate to meet the maintenance standards based on
maintenance records of double the length of time of the proposed
inspection frequency. In the absence of maintenance records for catch
basins, the Permittee may substitute written statements to document a
specific, less frequent inspection schedule. Written statements shall be
based on actual inspection and maintenance experiences and shall be
certified in accordance with G19 Certification and Signature.
ii. Inspections at least once by August 1, 2017 and every two years
thereafter may be conducted on a “circuit basis” whereby 25% of catch
basins and inlets within each circuit are inspected to identify
maintenance needs. Include an inspection of the catch basin
immediately upstream of any system outfall or discharge point, if
applicable. Clean all catch basins within a given circuit for which the
30 New Permittees shall inspect and, if needed, clean all catch basins and inlets owned or operated by the Permittee
in accordance with the requirements of S5.C.5.d once during the permit term, to be completed no later than February
2, 2018.
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inspection indicates cleaning is needed to comply with maintenance
standards established under S5.C.5.a, above.
iii. The Permittee may clean all pipes, ditches, catch basins, and inlets
within a circuit once during the permit term. Circuits selected for this
alternative must drain to a single point.
e. Compliance with the inspection requirements in b, c, and d above shall be
determined by the presence of an established inspection program designed to
inspect all sites and achieving at least 95% of inspections.
f. Implement practices, policies and procedures to reduce stormwater impacts
associated with runoff from all lands owned or maintained by the Permittee,
and road maintenance activities under the functional control of the Permittee.
Lands owned or maintained by the Permittee include, but are not limited to,
streets, parking lots, roads, highways, buildings, parks, open space, road right-
of-ways, maintenance yards, and stormwater treatment and flow control
BMPs/facilities. The following activities shall be addressed:
• Pipe cleaning
• Cleaning of culverts that convey stormwater in ditch systems
• Ditch maintenance
• Street cleaning
• Road repair and resurfacing, including pavement grinding
• Snow and ice control
• Utility installation
• Pavement striping maintenance
• Maintaining roadside areas, including vegetation management
• Dust control
• Application of fertilizers, pesticides, and herbicides according to the
instructions for their use, including reducing nutrients and pesticides
using alternatives that minimize environmental impacts
• Sediment and erosion control
• Landscape maintenance and vegetation disposal
• Trash and pet waste management
• Building exterior cleaning and maintenance
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g. Implement an ongoing training program for employees of the Permittee whose
primary construction, operations or maintenance job functions may impact
stormwater quality. The training program shall address the importance of
protecting water quality, operation and maintenance standards, inspection
procedures, selecting appropriate BMPs, ways to perform their job activities
to prevent or minimize impacts to water quality, and procedures for reporting
water quality concerns. Follow-up training shall be provided as needed to
address changes in procedures, techniques, requirements, or staffing.
Permittees shall document and maintain records of training provided and the
staff trained.
h. Implement a Stormwater Pollution Prevention Plan (SWPPP) for all heavy
equipment maintenance or storage yards, and material storage facilities owned
or operated by the Permittee in areas subject to this Permit that are not
required to have coverage under the General NPDES Permit for Stormwater
Discharges Associated with Industrial Activities or another NPDES permit
that authorizes stormwater discharges associated with the activity. A schedule
for implementation of structural BMPs shall be included in the SWPPP.
Generic SWPPPs that can be applied at multiple sites may be used to comply
with this requirement. The SWPPP shall include periodic visual observation
of discharges from the facility to evaluate the effectiveness of the BMP.
i. Maintain records of inspections and maintenance or repair activities
conducted by the Permittee.
S6. STORMWATER MANAGEMENT PROGRAM FOR SECONDARY PERMITTEES
A. This section applies to all Secondary Permittees and all New Secondary Permittees,
whether coverage under this Permit is obtained individually or as a Co-Permittee with
a city, town, county or another Secondary Permittee.
New Secondary Permittees subject to this Permit shall fully meet the requirements of
this section as modified in footnotes in S6.D below, or as established as a condition of
coverage by Ecology.
1. To the extent allowable under state, federal or local law, all components are
mandatory for each Secondary Permittee covered under this Permit, whether
covered as an individual Permittee or as a Co-Permittee.
2. Each Secondary Permittee shall develop and implement a stormwater
management program (SWMP). A SWMP is a set of actions and activities
comprising the components listed in S6 and any additional actions necessary to
meet the requirements of applicable TMDLs pursuant to S7 Compliance with
TMDL Requirements, and S8 Monitoring and Assessment. The SWMP shall be
designed to reduce the discharge of pollutants from regulated small MS4s to the
MEP and protect water quality.
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3. Unless an alternate implementation schedule is established by Ecology as a
condition of permit coverage, the SWMP shall be developed and implemented in
accordance with the schedules contained in this section and shall be fully
developed and implemented no later than four and one-half years from the initial
permit coverage date. Secondary Permittees that are already implementing some
or all of the required SWMP components shall continue implementation of those
components.
4. Secondary Permittees may implement parts of their SWMP in accordance with
the schedule for cities, towns, and counties in S5, provided they have signed a
memorandum of understanding or other agreement to jointly implement the
activity or activities with one or more jurisdictions listed in S1.D.2.a or S1.D.2.b,
and submitted a copy of the agreement to Ecology.
5. Each Secondary Permittee shall prepare written documentation of the SWMP,
called the SWMP Plan. The SWMP Plan shall include a description of program
activities for the upcoming calendar year.
B. Coordination
Secondary Permittees shall coordinate stormwater-related policies, programs and
projects within a watershed and interconnected MS4s. Where relevant and
appropriate, the SWMP shall coordinate among departments of the Secondary
Permittee to ensure compliance with the terms of this Permit.
C. Legal Authority
To the extent allowable under state law and federal law, each Secondary Permittee
shall be able to demonstrate that they can operate pursuant to legal authority which
authorizes or enables the Secondary Permittee to control discharges to and from
MS4s owned or operated by the Secondary Permittee.
This legal authority may be a combination of statutes, ordinances, permits, contracts,
orders, interagency agreements, or similar instruments.
D. Stormwater Management Program for Secondary Permittees
The SWMP for Secondary Permittees shall include the following components:
1. Public Education and Outreach
Each Secondary Permittee shall implement the following stormwater education
strategies:
a. Storm drain inlets owned or operated by the Secondary Permittee that are
located in maintenance yards, in parking lots, along sidewalks, and at
S6.D.2 S6.D.2
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pedestrian access points shall be clearly labeled with a message similar to
“Dump no waste – Drains to water body”.31
As identified during visual inspection and regular maintenance of storm drain
inlets per the requirements of S6.D.3.d and S6.D.6.a.i below, or as otherwise
reported to the Secondary Permittee, any inlet having a label that is no longer
clearly visible and/or easily readable shall be re-labeled within 90 days.
b. Each year beginning no later than three years from the initial date of permit
coverage, public ports, colleges, and universities shall distribute educational
information to tenants and residents on the impact of stormwater discharges
on receiving waters, and steps that can be taken to reduce pollutants in
stormwater runoff. Distribution may be by hard copy or electronic means.
Appropriate topics may include:
i. How stormwater runoff affects local water bodies.
ii. Proper use and application of pesticides and fertilizers.
iii. Benefits of using well-adapted vegetation.
iv. Alternative equipment washing practices, including cars and trucks,
that minimize pollutants in stormwater.
v. Benefits of proper vehicle maintenance and alternative transportation
choices; proper handling and disposal of vehicle wastes, including the
location of hazardous waste collection facilities in the area.
vi. Hazards associated with illicit connections and illicit discharges.
vii. Benefits of litter control of pet waste.
2. Public Involvement and Participation
Each year, no later than May 31, each Secondary Permittee shall:
a. Make the annual report available on the Permittee’s website.
b. Make available on the Permittee’s website the latest updated version of the
SWMP Plan.
c. A Secondary Permittee that does not maintain a website may submit the
updated SWMP Plan and annual report in electronic format to Ecology for
posting on Ecology’s website.
31 New Secondary Permittees shall label all inlets as described in S6.D.1.a no later than four years from the initial
date of permit coverage.
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3. Illicit Discharge Detection and Elimination
Each Secondary Permittee shall:
a. From the initial date of permit coverage, comply with all relevant ordinances,
rules, and regulations of the local jurisdiction(s) in which the Secondary
Permittee is located that govern non-stormwater discharges.
b. Implement appropriate policies prohibiting illicit discharges,32 and an
enforcement plan to ensure compliance with illicit discharge policies.33 These
policies shall address, at a minimum: illicit connections, non-stormwater
discharges, including spills of hazardous materials, and improper disposal of
pet waste and litter.
i. Allowable discharges: The policies do not need to prohibit the
following categories of non-stormwater discharges:
• Diverted stream flows
• Rising ground waters
• Uncontaminated ground water infiltration (as defined at 40
CFR 35.2005(b)(20))
• Uncontaminated pumped ground water
• Foundation drains.
• Air conditioning condensation
• Irrigation water from agricultural sources that is commingled
with urban stormwater
• Springs
• Uncontaminated water from crawl space pumps
• Footing drains
• Flows from riparian habitats and wetlands
32 New Secondary Permittees shall develop and implement appropriate policies prohibiting illicit discharges, and
identify possible enforcement mechanisms as described in S6.D.3.b no later than one year from the initial date of
permit coverage.
33 New Secondary Permittees shall develop and implement an enforcement plan as described in S6.D.3.b no later
than 18 months from the initial date of permit coverage.
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• Discharges from emergency fire fighting activities in
accordance with S2 Authorized Discharges
• Non-stormwater discharges authorized by another NPDES or
state waste discharge permit
ii. Conditionally allowable discharges: The policies may allow the
following categories of non-stormwater discharges only if the stated
conditions are met and such discharges are allowed by local codes:
• Discharges from potable water sources, including but not
limited to water line flushing, hyperchlorinated water line
flushing, fire hydrant system flushing, and pipeline hydrostatic
test water. Planned discharges shall be dechlorinated to a total
residual chlorine concentration of 0.1 ppm or less, pH-adjusted
if necessary, and volumetrically and velocity controlled to
prevent resuspension of sediments in the MS4.
• Discharges from lawn watering and other irrigation runoff.
These discharges shall be minimized through, at a minimum,
public education activities and water conservation efforts
conducted by the Secondary Permittee and/or the local
jurisdiction.
• Dechlorinated swimming pool, spa and hot tub discharges. The
discharges shall be dechlorinated to a total residual chlorine
concentration of 0.1 ppm or less, pH-adjusted and
reoxygenated if necessary, and volumetrically and velocity
controlled to prevent resuspension of sediments in the MS4.
Discharges shall be thermally controlled to prevent an increase
in temperature of the receiving water. Swimming pool cleaning
wastewater and filter backwash shall not be discharged to the
MS4.
• Street and sidewalk wash water, water used to control dust, and
routine external building washdown that does not use
detergents. The Secondary Permittee shall reduce these
discharges through, at a minimum, public education activities
and/or water conservation efforts conducted by the Secondary
Permittee and/or the local jurisdiction. To avoid washing
pollutants into the MS4, the Secondary Permittee shall
minimize the amount of street wash and dust control water
used.
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• Other non-stormwater discharges shall be in compliance with
the requirements of a pollution prevention plan reviewed by the
Permittee which addresses control of such discharges.
iii. The Secondary Permittee shall address any category of discharges in
(i) or (ii) above if the discharge is identified as a significant source of
pollutants to waters of the State.
c. Maintain a storm sewer system map showing the locations of all known MS4
outfalls and discharge points, labeling the receiving waters (other than ground
water) and delineating the areas contributing runoff to each outfall and
discharge point. Make the map (or completed portions of the map) available
on request to Ecology and to the extent appropriate, to other Permittees. The
preferred format for mapping is an electronic format with fully described
mapping standards. An example description is provided on Ecology’s
website.34
d. Conduct field inspections and visually inspect for illicit discharges at all
known MS4 outfalls and discharge points. Visually inspect at least one third
(on average) of all known outfalls and discharge points each year beginning
no later than two years from the initial date of permit coverage. Implement
procedures to identify and remove any illicit discharges. Keep records of
inspections and follow-up activities.
e. Implement a spill response plan that includes coordination with a qualified
spill responder.35
f. No later than two years from initial date of permit coverage, provide staff
training or coordinate with existing training efforts to educate staff on proper
BMPs for preventing illicit discharges, including spills. Train all Secondary
Permittee staff who, as part of their normal job responsibilities, have a role in
preventing such illicit discharges.
4. Construction Site Stormwater Runoff Control
From the initial date of permit coverage, each Secondary Permittee shall:
a. Comply with all relevant ordinances, rules, and regulations of the local
jurisdiction(s) in which the Secondary Permittee is located that govern
construction phase stormwater pollution prevention measures.
34 New Secondary Permittees shall meet the requirements of S6.D.3.c no later than four and one-half years from the
initial date of permit coverage.
35 New Secondary Permittees shall develop and implement a spill response plan as described in S6.D.3.e no later
than four and one-half years from the initial date of permit coverage.
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b. Ensure that all construction projects under the functional control of the
Secondary Permittee which require a construction stormwater permit obtain
coverage under the NPDES General Permit for Stormwater Discharges
Associated with Construction Activities or an individual NPDES permit prior
to discharging construction related stormwater.
c. Coordinate with the local jurisdiction regarding projects owned or operated by
other entities which discharge into the Secondary Permittee’s MS4, to assist
the local jurisdiction with achieving compliance with all relevant ordinances,
rules, and regulations of the local jurisdiction(s).
d. Provide training or coordinate with existing training efforts to educate relevant
staff in erosion and sediment control BMPs and requirements, or hire trained
contractors to perform the work.
e. Coordinate as requested with Ecology or the local jurisdiction to provide
access for inspection of construction sites or other land disturbances which are
under the functional control of the Secondary Permittee during land disturbing
activities and/or construction period.
5. Post-Construction Stormwater Management for New Development and
Redevelopment
From the initial date of permit coverage, each Secondary Permittee shall:
a. Comply with all relevant ordinances, rules and regulations of the local
jurisdiction(s) in which the Secondary Permittee is located that govern post-
construction stormwater pollution prevention measures.
b. Coordinate with the local jurisdiction regarding projects owned or operated by
other entities which discharge into the Secondary Permittee’s MS4, to assist
the local jurisdiction with achieving compliance with all relevant ordinances,
rules and regulations of the local jurisdiction(s).
6. Pollution Prevention and Good Housekeeping for Municipal Operations
Each Secondary Permittee shall:
a. Implement a municipal operation and maintenance (O&M) plan to minimize
stormwater pollution from activities conducted by the Secondary Permittee.
The O&M Plan shall include appropriate pollution prevention and good
housekeeping procedures for all of the following operations, activities, and/or
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types of facilities that are present within the Secondary Permittee’s boundaries
and under the functional control of the Secondary Permittee.36
i. Stormwater collection and conveyance systems, including catch
basins, stormwater pipes, open channels, culverts, and stormwater
treatment and flow control BMPs/facilities. The O&M Plan shall
address, at a minimum: scheduled inspections and maintenance
activities, including cleaning and proper disposal of waste removed
from the system. Secondary Permittees shall properly maintain
stormwater collection and conveyance systems owned or operated by
the Secondary Permittee and regularly inspect and maintain all
stormwater facilities to ensure facility function.
Secondary Permittees shall establish maintenance standards that are as
protective or more protective of facility function than those specified
in Chapter 4 Volume V of the Stormwater Management Manual for
Western Washington. Secondary Permittees shall review their
maintenance standards to ensure they are consistent with the
requirements of this section.
Secondary Permittees shall conduct spot checks of potentially
damaged permanent stormwater treatment and flow control
BMPs/facilities following major storm events (24 hour storm event
with a 10 year or greater recurrence interval).
ii. Roads, highways, and parking lots. The O&M Plan shall address,
but is not limited to: deicing, anti-icing, and snow removal practices;
snow disposal areas; material (e.g., salt, sand, or other chemical)
storage areas; all-season BMPs to reduce road and parking lot debris
and other pollutants from entering the MS4.
iii. Vehicle fleets. The O&M Plan shall address, but is not limited to:
storage, washing, and maintenance of Secondary Permittee vehicle
fleets; and fueling facilities. Secondary Permittees shall conduct all
vehicle and equipment washing and maintenance in a self-contained
covered building or in designated wash and/or maintenance areas.
iv. External building maintenance. The O&M Plan shall address,
building exterior cleaning and maintenance including cleaning,
washing, painting; and maintenance and management of dumpsters;
and other maintenance activities.
36 New Secondary Permittees shall develop and implement the operation and maintenance plan described in
S6.D.6.a no later than three years from initial date of permit coverage.
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v. Parks and open space. The O&M Plan shall address, but is not
limited to: proper application of fertilizer, pesticides, and herbicides;
sediment and erosion control; BMPs for landscape maintenance and
vegetation disposal; and trash and pet waste management.
vi. Material storage facilities and heavy equipment maintenance or
storage yards. Secondary Permittees shall develop and implement a
Stormwater Pollution Prevention Plan to protect water quality at each
of these facilities owned or operated by the Secondary Permittee and
not covered under the General NPDES Permit for Stormwater
Discharges Associated with Industrial Activities or under another
NPDES permit that authorizes stormwater discharges associated with
the activity.
vii. Other facilities that would reasonably be expected to discharge
contaminated runoff. The O&M Plan shall address proper
stormwater pollution prevention practices for each facility.
b. From the initial date of permit coverage, Secondary Permittees shall also have
permit coverage for all facilities operated by the Secondary Permittee that are
required to be covered under the General NPDES Permit for Stormwater
Discharges Associated with Industrial Activities or another NPDES permit
that authorizes discharges associated with the activity.
c. The O&M Plan shall include sufficient documentation and records as
necessary to demonstrate compliance with the O&M Plan requirements in
S6.D.6.a.(i) through (vii) above.
d. No later than three years from the initial date of permit coverage, Secondary
Permittees shall implement a program designed to train all employees whose
primary construction, operations, or maintenance job functions may impact
stormwater quality. The training shall address:
i. The importance of protecting water quality.
ii. The requirements of this Permit.
iii. Operation and maintenance requirements.
iv. Inspection procedures.
v. Ways to perform their job activities to prevent or minimize impacts to
water quality.
vi. Procedures for reporting water quality concerns, including potential
illicit discharges (including spills).
S6.D.6 S6.D.6
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 48 of 74
S7. COMPLIANCE WITH TOTAL MAXIMUM DAILY LOAD REQUIREMENTS
The following requirements apply if an applicable TMDL is approved for stormwater
discharges from MS4s owned or operated by the Permittee. Applicable TMDLs are TMDLs
which have been approved by EPA on or before the issuance date of this Permit or prior to
the date that Ecology issues coverage under this permit, whichever is later.
A. For applicable TMDLs listed in Appendix 2, affected Permittees shall comply with
the specific requirements identified in Appendix 2. Each Permittee shall keep records
of all actions required by this Permit that are relevant to applicable TMDLs within
their jurisdiction. The status of the TMDL implementation shall be included as part of
the annual report submitted to Ecology. Each annual report shall include a summary
of relevant SWMP and Appendix 2 activities conducted in the TMDL area to address
the applicable TMDL parameter(s).
B. For applicable TMDLs not listed in Appendix 2, compliance with this Permit shall
constitute compliance with those TMDLs.
C. For TMDLs that are approved by EPA after this Permit is issued, Ecology may
establish TMDL related permit requirements through future permit modification if
Ecology determines implementation of actions, monitoring or reporting necessary to
demonstrate reasonable further progress toward achieving TMDL waste load
allocations, and other targets, are not occurring and shall be implemented during the
term of this Permit or when this Permit is reissued. Permittees are encouraged to
participate in development of TMDLs within their jurisdiction and to begin
implementation.
S8. MONITORING AND ASSESSMENT
A. All Permittees including Secondary Permittees shall provide, in each annual report, a
description of any stormwater monitoring or stormwater-related studies conducted by
the Permittee during the reporting period. If other stormwater monitoring or
stormwater-related studies were conducted on behalf of the Permittee during the
reporting period, or if stormwater-related investigations conducted by other entities
were reported to the Permittee during the reporting period, a brief description of the
type of information gathered or received shall be included in the annual report.
Permittees are not required to provide descriptions of any monitoring, studies, or
analyses conducted as part of the Regional Stormwater Monitoring Program (RSMP)
in annual reports. If a Permittee conducts independent monitoring in accordance with
requirements in S8.B or S8.C below, annual reporting of such monitoring must follow
the requirements specified in those sections.
B. Status and trends monitoring. By December 1, 2013, each city and county Permittee
listed in S1.D.2.a(i) and S1.D.2.a(ii) located in Clallam, Island, King, Kitsap, Pierce,
Skagit, Snohomish, Thurston, or Whatcom County shall notify Ecology in writing
which of the following two options for status and trends monitoring the Permittee
S8.B.1 S8.B.1
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 49 of 74
chooses to carry out during this permit cycle. Either option will fully satisfy the
Permittee’s obligations under this section (S8.B). Each Permittee shall select a single
option for the duration of this permit term.
1. Status and Trends Monitoring Option #1: Each Permittee that chooses this
option shall pay into a collective fund to implement RSMP small streams and
marine nearshore status and trends monitoring in Puget Sound. The payments into
the collective fund are due to Ecology annually beginning August 15, 2014. The
payment amounts are (Permittees are listed alphabetically, by county):
Permittee
Annual
payment
amount
Permittee
Annual
payment
amount
Clallam Co. N/A Pierce Co. N/A
Port Angeles $4,732 Bonney Lake $4,075
Island Co. N/A Buckley $1,129
Oak Harbor $5,719 DuPont $1,936
King Co. N/A Edgewood $2,350
Algona $678 Fife $2,005
Auburn $16,914 Fircrest $1,549
Bellevue $30,009 Gig Harbor $1,836
Black Diamond $1,023 Lakewood $14,367
Bothell $8,163 Milton $1,597
Burien $11,238 Orting $1,525
Clyde Hill $695 Puyallup $9,498
Covington $4,307 Steilacoom $1,538
Des Moines $7,152 Sumner $2,217
Duvall $1,463 University Place $7,704
Enumclaw $2,806 Skagit Co. $1,257
Federal Way $21,673 Burlington $2,194
Issaquah $6,632 Anacortes $4,102
Kenmore $5,042 Mount Vernon $7,574
Kent $27,441 Sedro Woolley $2,452
Kirkland $12,116 Snohomish Co. N/A
Lake Forest Park $3,135 Arlington $4,219
Maple Valley $5,648 Brier $1,585
S8.B.2 S8.B.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 50 of 74
Medina $728 Edmonds $9,987
Mercer Island $5,589 Everett $25,419
Newcastle $2,431 Granite Falls $824
Normandy Park $1,597 Lake Stevens $6,512
Pacific $1,540 Lynnwood $8,829
Redmond $13,143 Marysville $14,172
Renton $21,055 Mill Creek $4,566
Sammamish $10,028 Monroe $4,073
SeaTac $6,322 Mountlake Terrace $5,118
Shoreline $13,327 Mukilteo $4,920
Tukwila $4,444 Snohomish $2,276
Woodinville $2,771 Thurston Co. $12,841
Kitsap Co. $17,133 Lacey $9,799
Bainbridge Island $5,709 Olympia $11,110
Bremerton $8,837 Tumwater $4,095
Port Orchard $2,664 Whatcom Co. $3,714
Poulsbo $2,187 Bellingham $18,936
Ferndale $2,737
Or
2. Status and Trends Monitoring Option #2: Each Permittee that chooses this
option shall conduct status and trends monitoring as follows:
a. Beginning no later than October 31, 2014, conduct wadeable stream water
quality, benthos, habitat, and sediment chemistry monitoring according to the
Ecology-approved Quality Assurance Project Plan (QAPP) for RSMP Small
Streams Status and Trends Monitoring.
i. Permittees with population less than 10,000 in the permit coverage
area shall conduct this monitoring at the first two qualified monitoring
locations (as listed sequentially among the potential monitoring
locations defined in the RSMP QAPP) that are located within the
jurisdiction’s boundaries. Counties shall monitor the first location
inside UGA boundaries and the first location outside UGA boundaries.
ii. Permittees with population equal to or greater than 10,000 and fewer
than 50,000 in the permit coverage area shall conduct this monitoring
at the first four qualified monitoring locations (as listed sequentially
among the potential monitoring locations defined in the RSMP QAPP)
S8.B.2 S8.B.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 51 of 74
that are located within the jurisdiction’s boundaries. Counties shall
monitor the first two locations inside UGA boundaries and the first
two locations outside UGA boundaries.
iii. Permittees with population equal to or greater than 50,000 in the
permit coverage area shall conduct this monitoring at the first eight
qualified monitoring locations (as listed sequentially among the
potential monitoring locations defined in the RSMP QAPP) that are
located within the jurisdiction’s boundaries. Counties shall monitor the
first four locations inside UGA boundaries and the first four locations
outside UGA boundaries.
Permittees with population equal to or greater than 50,000 in the
permit coverage area and located entirely inland (i.e., having no Puget
Sound shoreline boundary) shall conduct this monitoring at an
additional four monitoring locations (as listed sequentially among the
potential monitoring locations defined in the RSMP QAPP), for a total
of 12 monitoring locations.
If fewer than the total required number (8 or 12) of monitoring
locations located in the Permittees’ coverage area meet the criteria for
sampling defined in the RSMP QAPP, then the Permittee shall conduct
this monitoring at all of the monitoring locations that meet the criteria.
And
b. Beginning no later than October 1, 2015, Permittees with Puget Sound
shoreline shall conduct sediment chemistry, mussel, and bacteria monitoring
according to the Ecology-approved QAPPs for RSMP Marine Nearshore
Status and Trends Monitoring.
i. Permittees with population less than 10,000 shall conduct this
monitoring at the first two qualified monitoring locations each, for
sediment and for mussels and bacteria (as listed sequentially among
the potential monitoring locations defined in the RSMP QAPPs), that
are located adjacent to the jurisdiction’s Puget Sound shoreline
boundary.
ii. Permittees with population equal to or greater than 10,000 and fewer
than 50,000 in the permit coverage area shall conduct this monitoring
at the first four qualified monitoring locations each, for sediment and
for mussels and bacteria (as listed sequentially among the potential
monitoring locations defined in the RSMP QAPPs), that are located
adjacent to the jurisdiction’s Puget Sound shoreline boundary.
S8.C.1 S8.C.1
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 52 of 74
iii. Permittees with population equal to or greater than 50,000 in the
permit coverage area shall conduct this monitoring at the first six
qualified monitoring locations each, for sediment and for mussels and
bacteria (as listed sequentially among the potential monitoring
locations defined in the RSMP QAPPs), that are located adjacent to the
jurisdiction’s Puget Sound shoreline boundary.
And
c. Data and analyses shall be reported annually in accordance with the Ecology-
approved QAPPs.
C. Stormwater management program effectiveness studies. By December 1, 2013, each
city and county Permittee listed in S1.D.2.a(i) and S1.D.2.a(ii) shall notify Ecology in
writing which of the following two options for effectiveness studies the Permittee
chooses to carry out during this permit cycle. Either option will fully satisfy the
Permittee’s obligations under this section (S8.C). Each Permittee shall select a single
option for the duration of this permit term.
1. Effectiveness Studies Option #1: Each Permittee that chooses this option shall
pay into a collective fund to implement RSMP effectiveness studies. The
payments into the collective fund are due to Ecology annually beginning August
15, 2014. The payment amounts are (Permittees are listed alphabetically, by
county):
Permittee
Annual
payment
amount
Permittee
Annual
payment
amount
Clallam Co. N/A Lewis Co. N/A
Port Angeles $7,885 Centralia $6,334
Clark Co. N/A Pierce Co. N/A
Battle Ground $7,079 Bonney Lake $6,790
Camas $7,002 Buckley $1,882
Vancouver $67,335 DuPont $3,226
Washougal $5,716 Edgewood $3,916
Cowlitz Co. $1,384 Fife $3,340
Kelso $4,793 Fircrest $2,581
Longview $14,687 Gig Harbor $3,059
Grays Harbor Co. N/A Lakewood $23,938
Aberdeen $6,693 Milton $2,661
S8.C.1 S8.C.1
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 53 of 74
Island Co. N/A Orting $2,541
Oak Harbor $9,528 Puyallup $15,826
King Co. N/A Steilacoom $2,563
Algona $1,129 Sumner $3,694
Auburn $28,182 University Place $12,836
Bellevue $50,001 Skagit Co. $2,094
Black Diamond $1,705 Burlington $3,655
Bothell $13,601 Anacortes $6,835
Burien $18,724 Mount Vernon $12,620
Clyde Hill $1,157 Sedro Woolley $4,085
Covington $7,177 Snohomish Co. N/A
Des Moines $11,916 Arlington $7,030
Duvall $2,437 Brier $2,640
Enumclaw $4,675 Edmonds $16,640
Federal Way $36,111 Everett $42,352
Issaquah $11,050 Granite Falls $1,373
Kenmore $8,401 Lake Stevens $10,850
Kent $45,721 Lynnwood $14,711
Kirkland $20,187 Marysville $23,613
Lake Forest Park $5,224 Mill Creek $7,608
Maple Valley $9,410 Monroe $6,786
Medina $1,212 Mountlake Terrace $8,527
Mercer Island $9,313 Mukilteo $8,198
Newcastle $4,050 Snohomish $3,792
Normandy Park $2,661 Thurston Co. $21,395
Pacific $2,565 Lacey $16,326
Redmond $21,899 Olympia $18,511
Renton $35,082 Tumwater $6,823
Sammamish $16,709 Whatcom Co. $6,188
SeaTac $10,533 Bellingham $31,550
Shoreline $22,205 Ferndale $4,561
Tukwila $7,405
S8.C.2 S8.C.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 54 of 74
Woodinville $4,618
Kitsap Co. $28,547
Bainbridge Island $9,512
Bremerton $14,724
Port Orchard $4,439
Poulsbo $3,643
Or
2. Effectiveness Studies Option #2: Each Permittee that chooses this option shall
conduct stormwater discharge monitoring in accordance with Appendix 9 and the
following:
a. By February 2, 2014, each Permittee shall submit to Ecology a draft
stormwater discharge monitoring QAPP for review and approval. If Ecology
does not request changes within 90 days, the draft QAPP is considered
approved. Final QAPPs shall be submitted to Ecology as soon as possible
following finalization.
i. Each Permittee with population fewer than 10,000 in the permit
coverage area shall conduct stormwater discharge monitoring at one
discharge monitoring location.
ii. Each Permittee with population equal to or greater than 10,000 but
fewer than 50,000 in the permit coverage area shall conduct
stormwater discharge monitoring at two discharge monitoring
locations.
iii. Each Permittee with population equal to or greater than 50,000 but
fewer than 100,000 in the permit coverage area shall conduct
stormwater discharge monitoring at three discharge monitoring
locations.
iv. Each Permittee with population 100,000 or more in the permit
coverage area shall conduct stormwater discharge monitoring at four
discharge monitoring locations.
b. Permittees shall document in the QAPP why selected discharge monitoring
locations are of interest for long term stormwater discharge monitoring and
associated stormwater management program effectiveness evaluations.
Permittees are encouraged to monitor at locations chosen and submitted in the
annual reports that were due March 31, 2011.
c. Flow monitoring at discharge monitoring locations shall be implemented
beginning no later than October 1, 2014. Stormwater discharge monitoring
S8.C.2 S8.C.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 55 of 74
shall be fully implemented no later than October 1, 2015. All monitoring shall
be conducted in accordance with an Ecology-approved QAPP.
D. Source identification and diagnostic monitoring. Each city and county Permittee
listed in S1.D.2.a(i) and S1.D.2.a(ii) shall pay into a collective fund to implement the
RSMP Source Identification Information Repository (SIDIR). The payments into the
collective fund are due to Ecology annually beginning August 15, 2014. The payment
amounts are (Permittees are listed alphabetically, by county):
Permittee
Annual
payment
amount
Permittee
Annual
payment
amount
Clallam Co. N/A Lewis Co. N/A
Port Angeles $731 Centralia $587
Clark Co. N/A Pierce Co. N/A
Battle Ground $657 Bonney Lake $630
Camas $649 Buckley $175
Vancouver $6,245 DuPont $299
Washougal $530 Edgewood $363
Cowlitz Co. $128 Fife $310
Kelso $444 Fircrest $239
Longview $1,362 Gig Harbor $284
Grays Harbor Co. N/A Lakewood $2,220
Aberdeen $621 Milton $247
Island Co. N/A Orting $236
Oak Harbor $884 Puyallup $1,468
King Co. N/A Steilacoom $238
Algona $105 Sumner $343
Auburn $2,614 University Place $1,190
Bellevue $4,637 Skagit Co. $194
Black Diamond $158 Burlington $339
Bothell $1,261 Anacortes $634
Burien $1,736 Mount Vernon $1,170
Clyde Hill $107 Sedro Woolley $379
Covington $666 Snohomish Co. N/A
S8.C.2 S8.C.2
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 56 of 74
Des Moines $1,105 Arlington $652
Duvall $226 Brier $245
Enumclaw $434 Edmonds $1,543
Federal Way $3,349 Everett $3,928
Issaquah $1,025 Granite Falls $127
Kenmore $779 Lake Stevens $1,006
Kent $4,240 Lynnwood $1,364
Kirkland $1,872 Marysville $2,190
Lake Forest Park $484 Mill Creek $706
Maple Valley $873 Monroe $629
Medina $112 Mountlake Terrace $791
Mercer Island $864 Mukilteo $760
Newcastle $376 Snohomish $352
Normandy Park $247 Thurston Co. $1,984
Pacific $238 Lacey $1,514
Redmond $2,031 Olympia $1,717
Renton $3,253 Tumwater $633
Sammamish $1,550 Whatcom Co. $574
SeaTac $977 Bellingham $2,926
Shoreline $2,059 Ferndale $423
Tukwila $687
Woodinville $428
Kitsap Co. $2,647
Bainbridge Island $882
Bremerton $1,365
Port Orchard $412
Poulsbo $338
S9. REPORTING REQUIREMENTS
A. No later than March 31 of each year beginning in 2015, each Permittee shall submit
an annual report. The reporting period for the first annual report will be from January
S9.C.1 S9.D.6
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 57 of 74
1, 2014 through December 31, 2014. The reporting period for all subsequent annual
reports will be the previous calendar year unless otherwise specified.
Permittees must submit annual reports electronically using Ecology’s Water Quality
Permitting Portal (WQWebPortal) available on Ecology’s website at:
http://www.ecy.wa.gov/programs/wq/permits/paris/portal.html unless otherwise
directed by Ecology.
Permittees unable to submit electronically through Ecology’s WQWebPortal must
contact Ecology to request a waiver and obtain instructions on how to submit an
annual report in an alternative format.
B. Each Permittee is required to keep all records related to this permit and the SWMP
for at least five years.
C. Each Permittee shall make all records related to this permit and the Permittee’s
SWMP available to the public at reasonable times during business hours. The
Permittee will provide a copy of the most recent annual report to any individual or
entity, upon request.
1. A reasonable charge may be assessed by the Permittee for making photocopies of
records.
2. The Permittee may require reasonable advance notice of intent to review records
related to this Permit.
D. The annual report for cities, towns, and counties
Each annual report shall include the following:
1. A copy of the Permittee’s current SWMP Plan as required by S5.A.2.
2. Submittal of the annual report form as provided by Ecology pursuant to S9.A,
describing the status of implementation of the requirements of this permit during
the reporting period.
3. Attachments to the annual report form including summaries, descriptions, reports,
and other information as required, or as applicable, to meet the requirements of
this permit during the reporting period. Refer to Appendix 3 for annual report
questions.
4. If applicable, notice that the MS4 is relying on another governmental entity to
satisfy any of the obligations under this permit.
5. Certification and signature pursuant to G19.D, and notification of any changes to
authorization pursuant to G19.C.
S9.D.6 S9.E.5
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 58 of 74
6. A notification of any annexations, incorporations or jurisdictional boundary
changes resulting in an increase or decrease in the Permittee’s geographic area of
permit coverage during the reporting period.
E. Annual report for Secondary Permittees
Each annual report shall include the following:
1. Submittal of the annual report form as provided by Ecology pursuant to S9.A,
describing the status of implementation of the requirements of this permit during
the reporting period.
2. Attachments to the annual report form including summaries, descriptions, reports,
and other information as required, or as applicable, to meet the requirements of
this permit during the reporting period. Refer to Appendix 4 for annual report
questions.
3. If applicable, notice that the MS4 is relying on another governmental entity to
satisfy any of the obligations under this permit.
4. Certification and signature pursuant to G19.D, and notification of any changes to
authorization pursuant to G19.C.
5. A notification of any jurisdictional boundary changes resulting in an increase or
decrease in the Secondary Permittee’s geographic area of permit coverage during
the reporting period.
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 59 of 74
GENERAL CONDITIONS
G1. DISCHARGE VIOLATIONS
All discharges and activities authorized by this Permit shall be consistent with the terms
and conditions of this Permit.
G2. PROPER OPERATION AND MAINTENANCE
The Permittee shall at all times properly operate and maintain all facilities and systems of
collection, treatment, and control (and related appurtenances) which are installed or used
by the Permittee for pollution control to achieve compliance with the terms and conditions
of this Permit.
G3. NOTIFICATION OF DISCHARGE, INCLUDING SPILLS
If a Permittee has knowledge of a discharge, including spills, into or from a MS4 which
could constitute a threat to human health, welfare, or the environment, the Permittee shall
A. Take appropriate action to correct or minimize the threat to human health, welfare
and/or the environment.
B. Notify the Ecology regional office and other appropriate spill response authorities
immediately but in no case later than within 24 hours of obtaining that knowledge.
Ecology’s Northwest Regional Office 24-hour number is 425-649-7000 and
Ecology’s Southwest Regional Office the number is 360-407-6300.
C. Immediately report spills or other discharges which might cause bacterial
contamination of marine waters, such as discharges resulting from broken sewer lines
and failing onsite septic systems, to the Ecology regional office and to the
Department of Health, Shellfish Program. The Department of Health's shellfish
number is 360-236-3330 (business hours) or 360-789-8962 (24-hours).
D. Immediately report spills or discharges of oils or hazardous substances to the Ecology
regional office and to the Washington Emergency Management Division at 1-800-
258-5990.
G4. BYPASS PROHIBITED
The intentional bypass of stormwater from all or any portion of a stormwater treatment
BMP whenever the design capacity of the treatment BMP is not exceeded, is prohibited
unless the following conditions are met:
A. Bypass is: (1) unavoidable to prevent loss of life, personal injury, or severe property
damage; or (2) necessary to perform construction or maintenance-related activities
essential to meet the requirements of the Clean Water Act (CWA); and
B. There are no feasible alternatives to bypass, such as the use of auxiliary treatment
facilities, retention of untreated stormwater, or maintenance during normal dry
periods.
G5 G9
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 60 of 74
"Severe property damage" means substantial physical damage to property, damage to
the treatment facilities which would cause them to become inoperable, or substantial
and permanent loss of natural resources which can reasonably be expected to occur in
the absence of a bypass.
G5. RIGHT OF ENTRY
The Permittee shall allow an authorized representative of Ecology, upon the presentation of
credentials and such other documents as may be required by law at reasonable times:
A. To enter upon the Permittee's premises where a discharge is located or where any
records must be kept under the terms and conditions of this Permit;
B. To have access to, and copy at reasonable cost and at reasonable times, any records
that must be kept under the terms of the Permit;
C. To inspect at reasonable times any monitoring equipment or method of monitoring
required in the Permit;
D. To inspect at reasonable times any collection, treatment, pollution management, or
discharge facilities; and
E. To sample at reasonable times any discharge of pollutants.
G6. DUTY TO MITIGATE
The Permittee shall take all reasonable steps to minimize or prevent any discharge in
violation of this Permit which has a reasonable likelihood of adversely affecting human
health or the environment.
G7. PROPERTY RIGHTS
This permit does not convey any property rights of any sort, or any exclusive privilege.
G8. COMPLIANCE WITH OTHER LAWS AND STATUTES
Nothing in the Permit shall be construed as excusing the Permittee from compliance with
any other applicable federal, state, or local statutes, ordinances, or regulations.
G9. MONITORING
A. Representative Sampling:
Samples and measurements taken to meet the requirements of this Permit shall be
representative of the volume and nature of the monitored discharge, including
representative sampling of any unusual discharge or discharge condition, including
bypasses, upsets, and maintenance-related conditions affecting effluent quality.
G9 G9
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
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B. Records Retention:
The Permittee shall retain records of all monitoring information, including all
calibration and maintenance records and all original recordings for continuous
monitoring instrumentation, copies of all reports required by this Permit, and records
of all data used to complete the application for this permit, for a period of at least five
years. This period of retention shall be extended during the course of any unresolved
litigation regarding the discharge of pollutants by the Permittee or when requested by
the Ecology. On request, monitoring data and analysis shall be provided to Ecology.
C. Recording of Results:
For each measurement or sample taken, the Permittee shall record the following
information: (1) the date, exact place and time of sampling; (2) the individual who
performed the sampling or measurement; (3) the dates the analyses were performed;
(4) who performed the analyses; (5) the analytical techniques or methods used; and
(6) the results of all analyses.
D. Test Procedures:
All sampling and analytical methods used to meet the monitoring requirements in this
Permit shall conform to the Guidelines Establishing Test Procedures for the Analysis
of Pollutants contained in 40 CFR Part 136, unless otherwise specified in this permit
or approved in writing by Ecology.
E. Flow Measurement:
Appropriate flow measurement devices and methods consistent with accepted
scientific practices shall be selected and used to ensure the accuracy and reliability of
measurements of the volume of monitored discharges. The devices shall be installed,
calibrated, and maintained to ensure that the accuracy of the measurements is
consistent with the accepted industry standard for that type of device. Frequency of
calibration shall be in conformance with manufacturer's recommendations or at a
minimum frequency of at least one calibration per year. Calibration records should be
maintained for a minimum of three years.
F. Lab Accreditation:
All monitoring data, except for flow, temperature, conductivity, pH, total residual
chlorine, and other exceptions approved by Ecology, shall be prepared by a laboratory
registered or accredited under the provisions of, Accreditation of Environmental
Laboratories, chapter 173-50 WAC. Soils and hazardous waste data are exempted
from this requirement pending accreditation of laboratories for analysis of these
media by Ecology. Quick methods of field detection of pollutants including nutrients,
surfactants, salinity, and other parameters are exempted from this requirement when
G10 G12
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013
Modified January 16, 2015
Page 62 of 74
the purpose of the sampling is identification and removal of a suspected illicit
discharge.
G. Additional Monitoring:
Ecology may establish specific monitoring requirements in addition to those
contained in this permit by administrative order or permit modification.
G10. REMOVED SUBSTANCES
With the exception of decant from street waste vehicles, the Permittee shall not allow
collected screenings, grit, solids, sludges, filter backwash, or other pollutants removed in
the course of treatment or control of stormwater to be resuspended or reintroduced to the
storm sewer system or to waters of the state. Decant from street waste vehicles resulting
from cleaning stormwater facilities may be reintroduced only when other practical means
are not available and only in accordance with the Street Waste Disposal Guidelines in
Appendix 6. Solids generated from maintenance of the MS4 may be reclaimed, recycled, or
reused when allowed by local codes and ordinances. Soils that are identified as
contaminated pursuant to chapter 173-350 WAC shall be disposed at a qualified solid waste
disposal facility (see Appendix 6).
G11. SEVERABILITY
The provisions of this Permit are severable, and if any provision of this Permit, or the
application of any provision of this permit to any circumstance, is held invalid, the
application of such provision to other circumstances, and the remainder of this Permit shall
not be affected thereby.
G12. REVOCATION OF COVERAGE
The director may terminate coverage under this General Permit in accordance with chapter
43.21B RCW and chapter 173-226 WAC. Cases where coverage may be terminated
include, but are not limited to the following:
A. Violation of any term or condition of this general permit;
B. Obtaining coverage under this general permit by misrepresentation or failure to
disclose fully all relevant facts;
C. A change in any condition that requires either a temporary or permanent reduction or
elimination of the permitted discharge;
D. A determination that the permitted activity endangers human health or the
environment, or contributes significantly to water quality standards violations;
E. Failure or refusal of the Permittee to allow entry as required in chapter 90.48.090
RCW;
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F. Nonpayment of permit fees assessed pursuant to chapter 90.48.465 RCW;
Revocation of coverage under this general permit may be initiated by Ecology or
requested by any interested person.
G13. TRANSFER OF COVERAGE
The director may require any discharger authorized by this General Permit to apply for and
obtain an individual permit in accordance with chapter 43.21B RCW and chapter 173-226
WAC.
G14. GENERAL PERMIT MODIFICATION AND REVOCATION
This General Permit may be modified, revoked and reissued, or terminated in accordance
with the provisions of WAC 173-226-230. Grounds for modification, revocation and
reissuance, or termination include, but are not limited to the following:
A. A change occurs in the technology or practices for control or abatement of pollutants
applicable to the category of dischargers covered under this General Permit;
B. Effluent limitation guidelines or standards are promulgated pursuant to the CWA or
chapter 90.48 RCW, for the category of dischargers covered under this General
Permit;
C. A water quality management plan containing requirements applicable to the category
of dischargers covered under this General Permit is approved; or
D. Information is obtained which indicates that cumulative effects on the environment
from dischargers covered under this General Permit are unacceptable.
E. Changes in state law that reference this permit.
G15. REPORTING A CAUSE FOR MODIFICATION OR REVOCATION
A Permittee who knows or has reason to believe that any activity has occurred or will occur
which would constitute cause for modification or revocation and reissuance under
Condition G12, G14, or 40 CFR 122.62 must report such plans, or such information, to
Ecology so that a decision can be made on whether action to modify, or revoke and reissue
this Permit will be required. Ecology may then require submission of a new or amended
application. Submission of such application does not relieve the Permittee of the duty to
comply with this Permit until it is modified or reissued.
G16. APPEALS
A. The terms and conditions of this General Permit, as they apply to the appropriate
class of dischargers, are subject to appeal within thirty days of issuance of this
General Permit, in accordance with chapter 43.21B RCW, and chapter 173-226
WAC.
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B. The terms and conditions of this General Permit, as they apply to an individual
discharger, are appealable in accordance with chapter 43.21B RCW within thirty days
of the effective date of coverage of that discharger. Consideration of an appeal of
General Permit coverage of an individual discharger is limited to the General Permit's
applicability or nonapplicability to that individual discharger.
C. The appeal of General Permit coverage of an individual discharger does not affect
any other dischargers covered under this General Permit. If the terms and conditions
of this General Permit are found to be inapplicable to any individual discharger(s), the
matter shall be remanded to Ecology for consideration of issuance of an individual
permit or permits.
D. Modifications of this Permit are appealable in accordance with chapter 43.21B RCW
and chapter 173-226 WAC.
G17. PENALTIES
40 CFR 122.41(a)(2) and (3), 40 CFR 122.41(j)(5), and 40 CFR 122.41(k)(2) are hereby
incorporated into this Permit by reference.
G18. DUTY TO REAPPLY
The Permittee shall apply for permit renewal at least 180 days prior to the specified
expiration date of this permit.
G19. CERTIFICATION AND SIGNATURE
All formal submittals to Ecology shall be signed and certified.
A. All permit applications shall be signed by either a principal executive officer or
ranking elected official.
B. All formal submittals required by this Permit shall be signed by a person described
above or by a duly authorized representative of that person. A person is a duly
authorized representative only if:
1. The authorization is made in writing by a person described above and submitted
to Ecology, and
2. The authorization specifies either an individual or a position having responsibility
for the overall development and implementation of the stormwater management
program. (A duly authorized representative may thus be either a named individual
or any individual occupying a named position.)
C. Changes to authorization. If an authorization under condition G19.B.2 is no longer
accurate because a different individual or position has responsibility for the overall
development and implementation of the stormwater management program, a new
authorization satisfying the requirements of condition G19.B.2 must be submitted to
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Ecology prior to or together with any reports, information, or applications to be
signed by an authorized representative.
D. Certification. Any person signing a formal submittal under this Permit shall make the
following certification:
“I certify, under penalty of law, that this document and all attachments were prepared
under my direction or supervision in accordance with a system designed to assure that
Qualified Personnel properly gathered and evaluated the information submitted.
Based on my inquiry of the person or persons who manage the system or those
persons directly responsible for gathering information, the information submitted is,
to the best of my knowledge and belief, true, accurate, and complete. I am aware that
there are significant penalties for submitting false information, including the
possibility of fine and imprisonment for willful violations.”
G20. NON-COMPLIANCE NOTIFICATION
In the event a Permittee is unable to comply with any of the terms and conditions of this
Permit, the Permittee must:
A. Notify Ecology of the failure to comply with the permit terms and conditions in
writing within 30 days of becoming aware that the non-compliance has occurred. The
written notification must include all of the following:
1. A description of the non-compliance, including dates.
2. Beginning and end dates of the non-compliance, and if the compliance has not
been corrected, the anticipated date of correction.
3. Steps taken or planned to reduce, eliminate, or prevent reoccurrence of the non-
compliance.
B. Take appropriate action to stop or correct the condition of non-compliance.
G21. UPSETS
Permittees must meet the conditions of 40 CFR 122.41(n) regarding “Upsets.” The
conditions are as follows:
A. Definition. “Upset” means an exceptional incident in which there is unintentional and
temporary noncompliance with technology based permit effluent limitations because
of factors beyond the reasonable control of the Permittee. An upset does not include
noncompliance to the extent caused by operational error, improperly designed
treatment facilities, inadequate treatment facilities, lack of preventive maintenance, or
careless or improper operation.
B. Effect of an upset. An upset constitutes an affirmative defense to an action brought
for noncompliance with such technology based permit effluent limitations if the
requirements of paragraph (C) of this condition are met. Any determination made
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during administrative review of claims that noncompliance was caused by upset, and
before an action for noncompliance, will not constitute final administrative action
subject to judicial review.
C. Conditions necessary for demonstration of upset. A Permittee who wishes to establish
the affirmative defense of upset must demonstrate, through properly signed
contemporaneous operating logs, or other relevant evidence that:
1. An upset occurred and that the Permittee can identify the cause(s) of the upset;
2. The permitted facility was at the time being properly operated; and
3. The Permittee submitted notice of the upset as required in 40 CFR
122.41(l)(6)(ii)(B) (24-hour notice of noncompliance).
4. The Permittee complied with any remedial measures required under 40 CFR
122.41(d) (Duty to Mitigate).
D. Burden of proof. In any enforcement proceeding, the Permittee seeking to establish
the occurrence of an upset has the burden of proof.
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DEFINITIONS AND ACRONYMS
This section includes definitions for terms used in the body of the permit and in all the
appendices except Appendix 1. Terms defined in Appendix 1 are necessary to implement
requirements related to Appendix 1.
40 CFR means Title 40 of the Code of Federal Regulations, which is the codification of the
general and permanent rules published in the Federal Register by the executive departments
and agencies of the federal government.
AKART means all known, available, and reasonable methods of prevention, control and
treatment. See also State Water Pollution Control Act, chapter 90.48.010 RCW and chapter
90.48.520 RCW.
All known, available and reasonable methods of prevention, control and treatment refers to
the State Water Pollution Control Act, chapter 90.48.010 RCW and chapter 90.48.520 RCW.
Applicable TMDL means a TMDL which has been approved by EPA on or before the issuance
date of this Permit, or prior to the date that Ecology issues coverage under this Permit,
whichever is later.
Beneficial Uses means uses of waters of the state, which include but are not limited to use for
domestic, stock watering, industrial, commercial, agricultural, irrigation, mining, fish and
wildlife maintenance and enhancement, recreation, generation of electric power and
preservation of environmental and aesthetic values, and all other uses compatible with the
enjoyment of the public waters of the state.
Best Management Practices are the schedules of activities, prohibitions of practices,
maintenance procedures, and structural and/or managerial practices approved by Ecology
that, when used singly or in combination, prevent or reduce the release of pollutants and
other adverse impacts to waters of Washington State.
BMP means Best Management Practice.
Bypass means the diversion of stormwater from any portion of a stormwater treatment facility.
Census defined urban area means Urbanized Area.
Circuit means a portion of a MS4 discharging to a single point or serving a discrete area
determined by traffic volumes, land use, topography or the configuration of the MS4.
Component or Program Component means an element of the Stormwater Management
Program listed in S5 Stormwater Management Program for Cities, Towns, and Counties or
S6 Stormwater Management Program for Secondary Permittees, S7 Compliance with Total
Maximum Daily Load Requirements, or S8 Monitoring of this permit.
Conveyance system means that portion of the municipal separate storm sewer system designed
or used for conveying stormwater.
Co-Permittee means an owner or operator of an MS4 which is in a cooperative agreement with
at least one other applicant for coverage under this permit. A Co-Permittee is an owner or
operator of a regulated MS4 located within or in proximity to another regulated MS4. A Co-
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Permittee is only responsible for permit conditions relating to discharges from the MS4 the
Co-Permittee owns or operates. See also 40 CFR 122.26(b)(1)
CWA means Clean Water Act (formerly referred to as the Federal Water Pollution Control Act
or Federal Water Pollution Control Act Amendments of 1972) Pub.L. 92-500, as amended
Pub. L. 95-217, Pub. L. 95-576, Pub. L. (6-483 and Pub. L. 97-117, 33 U.S.C. 1251 et seq.).
Director means the Director of the Washington State Department of Ecology, or an authorized
representative.
Discharge Point means the location where a discharge leaves the Permittee’s MS4 through the
Permittee’s MS4 facilities/BMPs designed to infiltrate.
Entity means a governmental body, or a public or private organization.
EPA means the U.S. Environmental Protection Agency.
General Permit means a permit which covers multiple dischargers of a point source category
within a designated geographical area, in lieu of individual permits being issued to each
discharger.
Ground water means water in a saturated zone or stratum beneath the surface of the land or
below a surface water body. Refer to chapter 173-200 WAC.
Hazardous substance means any liquid, solid, gas, or sludge, including any material, substance,
product, commodity, or waste, regardless of quantity, that exhibits any of the physical,
chemical, or biological properties described in WAC 173-303-090 or WAC 173-303-100.
Heavy equipment maintenance or storage yard means an uncovered area where any heavy
equipment, such as mowing equipment, excavators, dump trucks, backhoes, or bulldozers are
washed or maintained, or where at least five pieces of heavy equipment are stored on a long-
term basis.
Highway means a main public road connecting towns and cities.
Hydraulically near means runoff from the site discharges to the sensitive feature without
significant natural attenuation of flows that allows for suspended solids removal. See
Appendix 7 Determining Construction Site Sediment Damage Potential for a more detailed
definition.
Hyperchlorinated means water that contains more than 10 mg/Liter chlorine.
Illicit connection means any infrastructure connection to the MS4 that is not intended, permitted
or used for collecting and conveying stormwater or non-stormwater discharges allowed as
specified in this permit (S5.C.3 and S6.D.3). Examples include sanitary sewer connections,
floor drains, channels, pipelines, conduits, inlets, or outlets that are connected directly to the
MS4.
Illicit discharge means any discharge to a MS4 that is not composed entirely of stormwater or of
non-stormwater discharges allowed as specified in this permit (S5.C.3 and S6.D.3).
Impervious surface means a non-vegetated surface area that either prevents or retards the entry
of water into the soil mantle as under natural conditions prior to development. A non-
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vegetated surface area which causes water to run off the surface in greater quantities or at an
increased rate of flow from the flow present under natural conditions prior to development.
Common impervious surfaces include, but are not limited to, roof tops, walkways, patios,
driveways, parking lots or stormwater areas, concrete or asphalt paving, gravel roads, packed
earthen materials, and oiled, macadam or other surfaces which similarly impede the natural
infiltration of stormwater.
Land disturbing activity means any activity that results in a change in the existing soil cover
(both vegetative and non-vegetative) and/or the existing soil topography. Land disturbing
activities include, but are not limited to clearing, grading, filling and excavation. Compaction
that is associated with stabilization of structures and road construction shall also be
considered land disturbing activity. Vegetation maintenance practices, including landscape
maintenance and gardening, are not considered land disturbing activity. Stormwater facility
maintenance is not considered land disturbing activity if conducted according to established
standards and procedures.
LID means Low Impact Development.
LID BMP means low impact development best management practices.
LID Principles means land use management strategies that emphasize conservation, use of on-
site natural features, and site planning to minimize impervious surfaces, native vegetation
loss, and stormwater runoff.
Low Impact Development means a stormwater and land use management strategy that strives to
mimic pre-disturbance hydrologic processes of infiltration, filtration, storage, evaporation
and transpiration by emphasizing conservation, use of on-site natural features, site planning,
and distributed stormwater management practices that are integrated into a project design.
Low impact development best management practices means distributed stormwater
management practices, integrated into a project design, that emphasize pre-disturbance
hydrologic processes of infiltration, filtration, storage, evaporation and transpiration. LID
BMPs include, but are not limited to, bioretention,rain gardens, permeable pavements, roof
downspout controls, dispersion, soil quality and depth, vegetated roofs, minimum excavation
foundations, and water re-use.
Material Storage Facilities means an uncovered area where bulk materials (liquid, solid,
granular, etc.) are stored in piles, barrels, tanks, bins, crates, or other means.
Maximum Extent Practicable refers to paragraph 402(p)(3)(B)(iii) of the federal Clean Water
Act which reads as follows: Permits for discharges from municipal storm sewers shall require
controls to reduce the discharge of pollutants to the maximum extent practicable, including
management practices, control techniques, and system, design, and engineering methods, and
other such provisions as the Administrator or the State determines appropriate for the control
of such pollutants.
MEP means Maximum Extent Practicable.
MS4 means municipal separate storm sewer system.
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Municipal Separate Storm Sewer System means a conveyance, or system of conveyances
(including roads with drainage systems, municipal streets, catch basins, curbs, gutters,
ditches, manmade channels, or storm drains):
(i) Owned or operated by a state, city, town, borough, county, parish, district, association,
or other public body (created by or pursuant to state law) having jurisdiction over
disposal of wastes, stormwater, or other wastes, including special districts under State
law such as a sewer district, flood control district or drainage district, or similar entity,
or an Indian tribe or an authorized Indian tribal organization, or a designated and
approved management agency under section 208 of the CWA that discharges to waters
of Washington State.
(ii) Designed or used for collecting or conveying stormwater.
(iii) Which is not a combined sewer;
(iv) Which is not part of a Publicly Owned Treatment Works (POTW) as defined at 40 CFR
122.2.; and
(v) Which is defined as “large” or “medium” or “small” or otherwise designated by
Ecology pursuant to 40 CFR 122.26.
National Pollutant Discharge Elimination System means the national program for issuing,
modifying, revoking, and reissuing, terminating, monitoring and enforcing permits, and
imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of
the Federal Clean Water Act, for the discharge of pollutants to surface waters of the state
from point sources. These permits are referred to as NPDES permits and, in Washington
State, are administered by the Washington State Department of Ecology.
Native vegetation means vegetation comprised of plant species, other than noxious weeds, that
are indigenous to the coastal region of the Pacific Northwest and which reasonably could
have been expected to naturally occur on the site. Examples include trees such as Douglas
Fir, western hemlock, western red cedar, alder, big-leaf maple; shrubs such as willow,
elderberry, salmonberry, and salal; and herbaceous plants such as sword fern, foam flower,
and fireweed.
New development means land disturbing activities, including Class IV General Forest Practices
that are conversions from timber land to other uses; structural development, including
construction or installation of a building or other structure; creation of hard surfaces; and
subdivision, short subdivision and binding site plans, as defined and applied in chapter 58.17
RCW. Projects meeting the definition of redevelopment shall not be considered new
development. Refer to Appendix 1 for a definition of hard surfaces.
New Permittee means a city, town, or county that is subject to the Western Washington
Municipal Stormwater General Permit and was not subject to the permit prior to August 1,
2013.
New Secondary Permittee means a Secondary Permittee that is covered under a municipal
stormwater general permit and was not covered by the permit prior to August 1, 2013.
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NOI means Notice of Intent.
Notice of Intent means the application for, or a request for coverage under a General Permit
pursuant to WAC 173-226-200.
Notice of Intent for Construction Activity means the application form for coverage under the
Construction Stormwater General Permit.
Notice of Intent for Industrial Activity means the application form for coverage under the
General Permit for Stormwater Discharges Associated with Industrial Activities.
NPDES means National Pollutant Discharge Elimination System.
Outfall means a point source as defined by 40 CFR 122.2 at the point where a discharge leaves
the Permittee’s MS4 and enters a surface receiving waterbody or surface receiving waters.
Outfall does not include pipes, tunnels, or other conveyances which connect segments of the
same stream or other surface waters and are used to convey primarily surface waters (i.e.,
culverts).
Permittee unless otherwise noted, the term “Permittee” includes city, town, or county Permittee,
Co-Permittee, New Permittee, Secondary Permittee, and New Secondary Permittee.
Physically Interconnected means that one MS4 is connected to another storm sewer system in
such a way that it allows for direct discharges to the second system. For example, the roads
with drainage systems and municipal streets of one entity are physically connected directly to
a storm sewer system belonging to another entity.
Project site means that portion of a property, properties, or right-of-ways subject to land
disturbing activities, new hard surfaces, or replaced hard surfaces. Refer to Appendix 1 for a
definition of hard surfaces.
QAPP means Quality Assurance Project Plan.
Qualified Personnel means someone who has had professional training in the aspects of
stormwater management for which they are responsible and are under the functional control
of the Permittee. Qualified Personnel may be staff members, contractors, or volunteers.
Quality Assurance Project Plan means a document that describes the objectives of an
environmental study and the procedures to be followed to achieve those objectives.
RCW means the Revised Code of Washington State.
Receiving waterbody or receiving waters means naturally and/or reconstructed naturally
occurring surface water bodies, such as creeks, streams, rivers, lakes, wetlands, estuaries, and
marine waters, or ground water, to which a MS4 discharges.
Redevelopment means, on a site that is already substantially developed (i.e., has 35% or more of
existing hard surface coverage), the creation or addition of hard surfaces; the expansion of a
building footprint or addition or replacement of a structure; structural development including
construction, installation or expansion of a building or other structure; replacement of hard
surface that is not part of a routine maintenance activity; and land disturbing activities. Refer
to Appendix 1 for a definition of hard surfaces.
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Regional Stormwater Monitoring Program means, for all of western Washington, a
stormwater-focused monitoring and assessment program consisting of these components:
status and trends monitoring in small streams and marine nearshore areas, stormwater
management program effectiveness studies, and a source identification information
repository (SIDIR). The priorities and scope for the RSMP are set by a formal stakeholder
group. For this permit term, RSMP status and trends monitoring will be conducted in the
Puget Sound basin only.
Regulated Small Municipal Separate Storm Sewer System means a Municipal Separate
Storm Sewer System which is automatically designated for inclusion in the Phase II
stormwater permitting program by its location within an Urbanized Area, or by designation
by Ecology and is not eligible for a waiver or exemption under S1.C.
RSMP means Regional Stormwater Monitoring Program.
Runoff is water that travels across the land surface and discharges to water bodies either directly
or through a collection and conveyance system. See also “Stormwater.”
Secondary Permittee is an operator of a regulated small MS4 which is not a city, town or
county. Secondary Permittees include special purpose districts and other public entities that
meet the criteria in S1.B.
Sediment/Erosion-Sensitive Feature means an area subject to significant degradation due to the
effect of construction runoff, or areas requiring special protection to prevent erosion. See
Appendix 7 Determining Construction Site Sediment Transport Potential for a more detailed
definition.
Shared water bodies means water bodies, including downstream segments, lakes and estuaries
that receive discharges from more than one Permittee.
SIDIR means Source Identification Information Repository.
Significant contributor means a discharge that contributes a loading of pollutants considered to
be sufficient to cause or exacerbate the deterioration of receiving water quality or instream
habitat conditions.
Small Municipal Separate Storm Sewer System means an MS4 that is not defined as “large”
or “medium” pursuant to 40 CFR 122.26(b)(4) & (7) or designated under 40 CFR 122.26
(a)(1)(v).
Source control BMP means a structure or operation that is intended to prevent pollutants from
coming into contact with stormwater through physical separation of areas or careful
management of activities that are sources of pollutants. The SWMMWW separates source
control BMPs into two types. Structural Source Control BMPs are physical, structural, or
mechanical devices, or facilities that are intended to prevent pollutants from entering
stormwater. Operational BMPs are non-structural practices that prevent or reduce pollutants
from entering stormwater. See Volume IV of the SWMMWW for details.
Stormwater means runoff during and following precipitation and snowmelt events, including
surface runoff, drainage or interflow.
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Stormwater Associated with Industrial and Construction Activity means the discharge from
any conveyance which is used for collecting and conveying stormwater, which is directly
related to manufacturing, processing or raw materials storage areas at an industrial plant, or
associated with clearing, grading and/or excavation, and is required to have an NPDES
permit in accordance with 40 CFR 122.26.
Stormwater Management Program means a set of actions and activities designed to reduce the
discharge of pollutants from the MS4 to the MEP and to protect water quality, and
comprising the components listed in S5 (for cities, towns, and counties) or S6 (for Secondary
Permittees) of this Permit and any additional actions necessary to meet the requirements of
applicable TMDLs pursuant to S7 Compliance with TMDL Requirements, and S8 Monitoring
and Assessment.
Stormwater Treatment and Flow Control BMPs/Facilities means detention facilities,
treatment BMPs/facilities, bioretention, vegetated roofs, and permeable pavements that help
meet Appendix 1 Minimum Requirements #6 (treatment), #7 (flow control), or both.
SWMMWW or Stormwater Management Manual for Western Washington means
Stormwater Management Manual for Western Washington (as amended in 2014)
SWMP means Stormwater Management Program.
TMDL means Total Maximum Daily Load.
Total Maximum Daily Load means a water cleanup plan. A TMDL is a calculation of the
maximum amount of a pollutant that a water body can receive and still meet water quality
standards, and an allocation of that amount to the pollutant’s sources. A TMDL is the sum of
the allowable loads of a single pollutant from all contributing point and nonpoint sources.
The calculation must include a margin of safety to ensure that the water body can be used for
the purposes the state has designated. The calculation must also account for seasonable
variation in water quality. Water quality standards are set by states, territories, and tribes.
They identify the uses for each water body, for example, drinking water supply, contact
recreation (swimming), and aquatic life support (fishing), and the scientific criteria to support
that use. The Clean Water Act, section 303, establishes the water quality standards and
TMDL programs.
Tributary conveyance means pipes, ditches, catch basins, and inlets owned or operated by the
Permittee and designed or used for collecting and conveying stormwater.
UGA means Urban Growth Area.
Urban Growth Area means those areas designated by a county pursuant to RCW 36.70A.110.
Urbanized Area is a federally-designated land area comprising one or more places and the
adjacent densely settled surrounding area that together have a residential population of at
least 50,000 and an overall population density of at least 1,000 people per square mile.
Urbanized Areas are designated by the U.S. Census Bureau based on the most recent
decennial census.
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Vehicle Maintenance or Storage Facility means an uncovered area where any vehicles are
regularly washed or maintained, or where at least 10 vehicles are stored.
Water Quality Standards means Surface Water Quality Standards, chapter 173-201A WAC,
Ground Water Quality Standards, chapter 173-200 WAC, and Sediment Management
Standards, chapter 173-204 WAC.
Waters of the State includes those waters as defined as "waters of the United States" in 40 CFR
Subpart 122.2 within the geographic boundaries of Washington State and "waters of the
state" as defined in chapter 90.48 RCW which includes lakes, rivers, ponds, streams, inland
waters, underground waters, salt waters and all other surface waters and water courses within
the jurisdiction of the State of Washington.
Waters of the United States refers to the definition in 40 CFR 122.2.
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APPENDIX 1 – Minimum Technical Requirements for
New Development and Redevelopment
Section 1. Exemptions
Unless otherwise indicated in this Section 1, the practices described in this section are exempt
from the Minimum Requirements, even if such practices meet the definition of new development
or redevelopment.
Forest practices:
Forest practices regulated under Title 222 WAC, except for Class IV General forest practices
that are conversions from timberland to other uses, are exempt from the provisions of the
minimum requirements.
Commercial agriculture:
Commercial agriculture practices involving working the land for production are generally
exempt. However, the conversion from timberland to agriculture, and the construction of
impervious surfaces are not exempt.
Oil and Gas Field Activities or Operations:
Construction of drilling sites, waste management pits, and access roads, as well as construction
of transportation and treatment infrastructure such as pipelines natural gas treatment plants,
natural gas pipeline compressor stations, and crude oil pumping stations are exempt. Operators
are encouraged to implement and maintain Best Management Practices to minimize erosion and
control sediment during and after construction activities to help ensure protection of surface
water quality during storm events.
Pavement Maintenance:
The following pavement maintenance practices are exempt: pothole and square cut patching,
overlaying existing asphalt or concrete pavement with asphalt or concrete without expanding the
area of coverage, shoulder grading, reshaping/regrading drainage systems, crack sealing,
resurfacing with in-kind material without expanding the road prism, pavement preservation
activities that do not expand the road prism, and vegetation maintenance.
The following pavement maintenance practices are not categorically exempt. The extent to
which this Appendix applies is explained for each circumstance.
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• Removing and replacing a paved surface to base course or lower, or repairing the
pavement base: If impervious surfaces are not expanded, Minimum Requirements #1 - #5
apply.
• Extending the pavement edge without increasing the size of the road prism, or paving
graveled shoulders: These are considered new impervious surfaces and are subject to the
minimum requirements that are triggered when the thresholds identified for new or
redevelopment projects are met.
• Resurfacing by upgrading from dirt to gravel, asphalt, or concrete; upgrading from gravel
to asphalt, or concrete; or upgrading from a bituminous surface treatment (“chip seal”) to
asphalt or concrete: These are considered new impervious surfaces and are subject to the
minimum requirements that are triggered when the thresholds identified for new or
redevelopment projects are met.
Underground utility projects:
Underground utility projects that replace the ground surface with in-kind material or materials
with similar runoff characteristics are only subject to Minimum Requirement #2, Construction
Stormwater Pollution Prevention.
Section 2. Definitions Related to Minimum Requirements
Arterial – A road or street primarily for through traffic. The term generally includes roads or
streets considered collectors. It does not include local access roads which are generally limited to
providing access to abutting property. See also RCW 35.78.010, RCW 36.86.070, and RCW
47.05.021.
Bioretention – Engineered facilities that treat stormwater by passing it through a specified soil
profile, and either retain or detain the treated stormwater for flow attenuation. Refer to the
Stormwater Management Manual for Western Washington (SWMMWW), Chapter 7 of Volume V
for Bioretention BMP types and design specifications.
Certified Erosion and Sediment Control Lead (CESCL) – means an individual who has current
certification through an approved erosion and sediment control training program that meets the
minimum training standards established by the Washington Department of Ecology (Ecology)
(see BMP C160 in the Stormwater Management Manual for Western Washington (SWMMWW)).
A CESCL is knowledgeable in the principles and practices of erosion and sediment control. The
CESCL must have the skills to assess site conditions and construction activities that could impact
the quality of stormwater and, the effectiveness of erosion and sediment control measures used to
control the quality of stormwater discharges. Certification is obtained through an Ecology
approved erosion and sediment control course. Course listings are provided online at Ecology’s
website.
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Commercial Agriculture – means those activities conducted on lands defined in RCW
84.34.020(2) and activities involved in the production of crops or livestock for commercial trade.
An activity ceases to be considered commercial agriculture when the area on which it is
conducted is proposed for conversion to a nonagricultural use or has lain idle for more than five
years, unless the idle land is registered in a federal or state soils conservation program, or unless
the activity is maintenance of irrigation ditches, laterals, canals, or drainage ditches related to an
existing and ongoing agricultural activity.
Converted vegetation (areas) – The surfaces on a project site where native vegetation, pasture,
scrub/shrub, or unmaintained non-native vegetation (e.g., Himalayan blackberry, scotch broom)
are converted to lawn or landscaped areas, or where native vegetation is converted to pasture.
Discharge Point – the location where a discharge leaves the Permittee’s MS4 through the
Permittee’s MS4 facilities/BMPs designed to infiltrate.
Effective Impervious surface – Those impervious surfaces that are connected via sheet flow or
discrete conveyance to a drainage system. Impervious surfaces are considered ineffective if: 1)
the runoff is dispersed through at least one hundred feet of native vegetation in accordance with
BMP T5.30 – “Full Dispersion” as described in Chapter 5 of Volume V of the Stormwater
Management Manual for Western Washington (SWMMWW); 2) residential roof runoff is
infiltrated in accordance with Downspout Full Infiltration Systems in BMP T5.10A in Volume
III of the SWMMWW; or 3) approved continuous runoff modeling methods indicate that the
entire runoff file is infiltrated.
Erodible or leachable materials – Wastes, chemicals, or other substances that measurably alter
the physical or chemical characteristics of runoff when exposed to rainfall. Examples include
erodible soils that are stockpiled, uncovered process wastes, manure, fertilizers, oily substances,
ashes, kiln dust, and garbage dumpster leakage.
Hard Surface – An impervious surface, a permeable pavement, or a vegetated roof.
Highway – A main public road connecting towns and cities
Impervious surface – A non-vegetated surface area that either prevents or retards the entry of
water into the soil mantle as under natural conditions prior to development. A non-vegetated
surface area which causes water to run off the surface in greater quantities or at an increased rate
of flow from the flow present under natural conditions prior to development. Common
impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways,
parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials,
and oiled, macadam or other surfaces which similarly impede the natural infiltration of
stormwater. Open, uncovered retention/detention facilities shall not be considered as impervious
surfaces for purposes of determining whether the thresholds for application of minimum
requirements are exceeded. Open, uncovered retention/detention facilities shall be considered
impervious surfaces for purposes of runoff modeling.
Land disturbing activity – Any activity that results in a change in the existing soil cover (both
vegetative and non-vegetative) and/or the existing soil topography. Land disturbing activities
include, but are not limited to clearing, grading, filling, and excavation. Compaction that is
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associated with stabilization of structures and road construction shall also be considered a land
disturbing activity. Vegetation maintenance practices, including landscape maintenance and
gardening, are not considered land-disturbing activity. Stormwater facility maintenance is not
considered land disturbing activity if conducted according to established standards and
procedures.
Low Impact Development (LID) – A stormwater and land use management strategy that strives
to mimic pre-disturbance hydrologic processes of infiltration, filtration, storage, evaporation and
transpiration by emphasizing conservation, use of on-site natural features, site planning, and
distributed stormwater management practices that are integrated into a project design.
LID Best Management Practices – Distributed stormwater management practices, integrated
into a project design, that emphasize pre-disturbance hydrologic processes of infiltration,
filtration, storage, evaporation and transpiration. LID BMPs include, but are not limited to,
bioretention,rain gardens, permeable pavements, roof downspout controls, dispersion, soil
quality and depth, minimal excavation foundations, vegetated roofs, and water re-use.
LID Principles – Land use management strategies that emphasize conservation, use of on-site
natural features, and site planning to minimize impervious surfaces, native vegetation loss, and
stormwater runoff.
Maintenance – Repair and maintenance includes activities conducted on currently serviceable
structures, facilities, and equipment that involves no expansion or use beyond that previously
existing and results in no significant adverse hydrologic impact. It includes those usual activities
taken to prevent a decline, lapse, or cessation in the use of structures and systems. Those usual
activities may include replacement of dysfunctional facilities, including cases where
environmental permits require replacing an existing structure with a different type structure, as
long as the functioning characteristics of the original structure are not changed. One example is
the replacement of a collapsed, fish blocking, round culvert with a new box culvert under the
same span, or width, of roadway. In regard to stormwater facilities, maintenance includes
assessment to ensure ongoing proper operation, removal of built up pollutants (i.e.
sediments), replacement of failed or failing treatment media, and other actions taken to correct
defects as identified in the maintenance standards of Chapter 4, Volume V of the Stormwater
Management Manual for Western Washington (SWMMWW). See also Pavement Maintenance
exemptions in Section 1 of this Appendix.
Native vegetation – Vegetation comprised of plant species, other than noxious weeds, that are
indigenous to the coastal region of the Pacific Northwest and which reasonably could have been
expected to naturally occur on the site. Examples include trees such as Douglas Fir, western
hemlock, western red cedar, alder, big-leaf maple, and vine maple; shrubs such as willow,
elderberry, salmonberry, and salal; and herbaceous plants such as sword fern, foam flower, and
fireweed.
New development – Land disturbing activities, including Class IV -general forest practices that
are conversions from timber land to other uses; structural development, including construction or
installation of a building or other structure; creation of hard surfaces; and subdivision, short
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subdivision and binding site plans, as defined and applied in Chapter 58.17 RCW. Projects
meeting the definition of redevelopment shall not be considered new development.
Outfall – a point source as defined by 40 CFR 122.2 at the point where a discharge leaves the
permittee’s MS4 and enters a surface receiving waterbody or surface receiving waters. Outfall
does not include pipes, tunnels, or other conveyances which connect segments of the same
stream or other surface waters and are used to convey primarily surface waters (i.e., culverts).
On-site Stormwater Management BMPs: As used in this appendix, a synonym for Low Impact
Development BMPs.
Permeable pavement – Pervious concrete, porous asphalt, permeable pavers or other forms of
pervious or porous paving material intended to allow passage of water through the pavement
section. It often includes an aggregate base that provides structural support and acts as a
stormwater reservoir.
Pervious Surface – Any surface material that allows stormwater to infiltrate into the ground.
Examples include lawn, landscape, pasture, native vegetation areas, and permeable pavements.
Pollution-generating hard surface (PGHS) – Those hard surfaces considered to be a significant
source of pollutants in stormwater runoff. See the listing of surfaces under pollution-generating
impervious surface.
Pollution-generating impervious surface (PGIS) – Those impervious surfaces considered to be
a significant source of pollutants in stormwater runoff. Such surfaces include those which are
subject to: vehicular use; industrial activities (as further defined in the glossary of the
Stormwater Management Manual for Western Washington (SWMMWW)); storage of erodible or
leachable materials, wastes, or chemicals, and which receive direct rainfall or the run-on or
blow-in of rainfall; metal roofs unless they are coated with an inert, non-leachable material (e.g.,
baked-on enamel coating); or roofs that are subject to venting significant amounts of dusts, mists,
or fumes from manufacturing, commercial, or other indoor activities.
Pollution-generating pervious surfaces (PGPS) – Any non-impervious surface subject to
vehicular use, industrial activities (as further defined in the glossary of the Stormwater
Management Manual for Western Washington (SWMMWW); or storage of erodible or leachable
materials, wastes, or chemicals, and that receive direct rainfall or run-on or blow-in of rainfall,
use of pesticides and fertilizers, or loss of soil. Typical PGPS include permeable pavement
subject to vehicular use, lawns, and landscaped areas including: golf courses, parks, cemeteries,
and sports fields (natural and artificial turf).
Pre-developed condition – The native vegetation and soils that existed at a site prior to the
influence of Euro-American settlement. The pre-developed condition shall be assumed to be a
forested land cover unless reasonable, historic information is provided that indicates the site was
prairie prior to settlement.
Project site – That portion of a property, properties, or right of way subject to land disturbing
activities, new hard surfaces, or replaced hard surfaces.
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Rain Garden – A non-engineered shallow landscaped depression, with compost-amended native
soils and adapted plants. The depression is designed to pond and temporarily store stormwater
runoff from adjacent areas, and to allow stormwater to pass through the amended soil profile.
Receiving waterbody or Receiving waters – naturally and/or reconstructed naturally occurring
surface water bodies, such as creeks, streams, rivers, lakes, wetlands, estuaries, and marine
waters, or groundwater, to which a MS4 discharges.
Redevelopment – On a site that is already substantially developed (i.e., has 35% or more of
existing hard surface coverage), the creation or addition of hard surfaces; the expansion of a
building footprint or addition or replacement of a structure; structural development including
construction, installation or expansion of a building or other structure; replacement of hard
surface that is not part of a routine maintenance activity; and land disturbing activities.
Replaced hard surface – For structures, the removal and replacement of hard surfaces down to
the foundation. For other hard surfaces, the removal down to bare soil or base course and
replacement.
Replaced impervious surface – For structures, the removal and replacement of impervious
surfaces down to the foundation. For other impervious surfaces, the removal down to bare soil
or base course and replacement.
Site – The area defined by the legal boundaries of a parcel or parcels of land that is (are) subject
to new development or redevelopment. For road projects, the length of the project site and the
right-of-way boundaries define the site.
Source control BMP – A structure or operation that is intended to prevent pollutants from
coming into contact with stormwater through physical separation of areas or careful management
of activities that are sources of pollutants. The Stormwater Management Manual for Western
Washington (SWMMWW) separates source control BMPs into two types. Structural Source
Control BMPs are physical, structural, or mechanical devices, or facilities that are intended to
prevent pollutants from entering stormwater. Operational BMPs are non-structural practices that
prevent or reduce pollutants from entering stormwater. See Volume IV of the SWMMWW for
details.
Threshold Discharge Area – An on-site area draining to a single natural discharge location or
multiple natural discharge locations that combine within one-quarter mile downstream (as
determined by the shortest flowpath). The examples in Figure 2.1 below illustrate this definition.
The purpose of this definition is to clarify how the thresholds of this appendix are applied to
project sites with multiple discharge points.
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Vehicular Use – Regular use of an impervious or pervious surface by motor vehicles. The
following are subject to regular vehicular use: roads, un-vegetated road shoulders, bike lanes
within the traveled lane of a roadway, driveways, parking lots, unrestricted access fire lanes,
vehicular equipment storage yards, and airport runways.
The following are not considered subject to regular vehicular use: paved bicycle pathways
separated from and not subject to drainage from roads for motor vehicles, restricted access fire
lanes, and infrequently used maintenance access roads.
Wetland – Those areas that are inundated or saturated by surface or ground water at a frequency
and duration sufficient to support, and that under normal circumstances do support, a prevalence
of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include
swamps, marshes, bogs, and similar areas. Wetlands do not include those artificial wetlands
intentionally created from non-wetland sites, including, but not limited to, irrigation and drainage
ditches, grass-lined swales, canals, detention facilities, wastewater treatment facilities, farm
ponds, and landscape amenities, or those wetlands created after July 1, 1990, that were
unintentionally created as a result of the construction of a road, street, or highway. Wetlands may
include those artificial wetlands intentionally created from non-wetland areas to mitigate the
conversion of wetlands.
Figure 2.1 Threshold Discharge Areas
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Section 3. Applicability of the Minimum Requirements
3.1 Thresholds
Not all of the Minimum Requirements apply to every development or redevelopment
project. The applicability varies depending on the project type and size. This section
identifies thresholds that determine the applicability of the Minimum Requirements to
projects. Use the flow charts in Figures 3.1, 3.2, and 3.3 to determine which of the
Minimum Requirements apply. The Minimum Requirements themselves are presented in
Section 4 of this Appendix.
Use the thresholds in sections 3.2 and 3.3 at the time of application for a subdivision,
plat, short plat, building permit, or other construction permit. The plat or short plat
approval shall identify all stormwater BMPs that are required for each lot. For projects
involving only land disturbing activities, (e.g., clearing or grading), the thresholds apply
at the time of application for the permit allowing or authorizing that activity. Note the
exemption in Section 1 for forest practices other than Class IV General.
Will the project discharge
stormwater either directly or
indirectly into an MS4 owned or
operated by the Permittee?
Permittee is not required
to apply the Minimum
Requirements to the
project.
Continue with Figure 3.2 and 3.3
No
Yes
Figure 3.1 Flow Chart for Determining Whether
the Permittee Must Regulate the Project
Is the Project exempt according to
Section 1 of this Appendix?
No
Yes
START
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Yes
Yes Yes
No
No
Yes No
Yes
No
Does the project convert
¾ acres or more of
vegetation to lawn or
landscaped areas, or
convert 2.5 acres or more
of native vegetation to
pasture?
See Redevelopment
Minimum
Requirements and
Flow Chart
(Figure 3.3)
Minimum
Requirement #2
applies.
Does the project
result in 5,000
square feet, or
greater, of new plus
replaced hard
surface area?
All Minimum
Requirements apply
to the new and
replaced hard surfaces
and converted
vegetation areas.
Does the project
result in 2,000 square
feet, or greater, of
new plus replaced
hard surface area?
Minimum Requirements
#1 through #5 apply to
the new and replaced
hard surfaces and the
land disturbed.
Does the project have
land disturbing
activities of 7,000
square feet or greater?
Start Here
No
Does the site have
35% or more of
existing impervious
coverage?
Figure 3.2 Flow Chart for Determining Requirements for New Development
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All Minimum Requirements apply to the new and
replaced hard surfaces and converted vegetation areas.
Yes
No
Next Question
Yes
Next
Question
No
Yes
No
Minimum Requirements #1 through #5 apply to
the new and replaced hard surfaces and the land
disturbed.
Minimum Requirements #2 applies.
Does the project add 5,000 square feet or more of new hard surfaces?
OR
Convert ¾ acres or more of vegetation to lawn or landscaped areas?
OR
Convert 2.5 acres or more of native vegetation to pasture?
All Minimum Requirements apply to the
new hard surfaces and the converted
vegetation areas.
Is this a road
related project?
Does the project add 5,000 square feet or more of new hard surfaces?
Yes
Yes
Yes
No
No
No
Do new hard surfaces add 50% or
more to the existing hard surfaces
within the project limits?
No additional
requirements
No additional
requirements
Figure 3.3 Flow Chart for Determining Requirements for Redevelopment
Does the project result in 2,000 square feet, or more, of new plus replaced hard surface area?
OR
Does the land disturbing activity total 7,000 square feet or greater?
Is the total of new plus replaced hard surfaces
5,000 square feet or more, AND does the value
of the proposed improvements – including
interior improvements – exceed 50% of the
assessed value (or replacement value) of the
existing site improvements?
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3.2 New Development
All new development shall be required to comply with Minimum Requirement #2.
The following new development shall comply with Minimum Requirements #1 through
#5 for the new and replaced hard surfaces and the land disturbed:
• Results in 2,000 square feet, or greater, of new plus replaced hard surface area, or
• Has land disturbing activity of 7,000 square feet or greater.
The following new development shall comply with Minimum Requirements #1 through
#9 for the new and replaced hard surfaces and the converted vegetation areas:
• Results in 5,000 square feet, or greater, of new plus replaced hard surface area, or
• Converts ¾ acres, or more, of vegetation to lawn or landscaped areas, or
• Converts 2.5 acres, or more, of native vegetation to pasture.
3.3 Redevelopment
All redevelopment shall be required to comply with Minimum Requirement #2.
The following redevelopment shall comply with Minimum Requirements #1 through #5
for the new and replaced hard surfaces and the land disturbed:
• Results in 2,000 square feet, or more, of new plus replaced hard surface area, or
• Has land disturbing activity of 7,000 square feet or greater.
The following redevelopment shall comply with Minimum Requirements #1 through #9
for the new hard surfaces and converted vegetation areas:
• Adds 5,000 square feet or more of new hard surfaces or,
• Converts ¾ acres, or more, of vegetation to lawn or landscaped areas, or
• Converts 2.5 acres, or more, of native vegetation to pasture.
The local government may allow the Minimum Requirements to be met for an equivalent
(flow and pollution characteristics) area within the same site. For public road projects, the
equivalent area does not have to be within the project limits, but must drain to the same
receiving water.
3.4 Additional Requirements for Re-development Project Sites
For road-related projects, runoff from the replaced and new hard surfaces (including
pavement, shoulders, curbs, and sidewalks) and the converted vegetation areas shall meet
all the Minimum Requirements if the new hard surfaces total 5,000 square feet or more
and total 50% or more of the existing hard surfaces within the project limits. The project
limits shall be defined by the length of the project and the width of the right-of-way.
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Other types of redevelopment projects shall comply with Minimum Requirements #1
through #9 for the new and replaced hard surfaces and the converted vegetation areas if
the total of new plus replaced hard surfaces is 5,000 square feet or more, and the
valuation of proposed improvements – including interior improvements – exceeds 50% of
the assessed value of the existing site improvements.
The Permittee may exempt or institute a stop-loss provision for redevelopment projects
from compliance with Minimum Requirement #5 On-site Stormwater Management,
Minimum Requirement #6 Runoff Treatment, Minimum Requirement #7 Flow Control
and/or Minimum Requirement #8 Wetlands Protection as applied to the replaced hard
surfaces if the Permittee has adopted a plan and a schedule that fulfills those requirements
in regional facilities.
The Permittee may grant a variance/exception to the application of the flow control
requirements to replaced impervious surfaces if such application imposes a severe
economic hardship. See Section 6 of this Appendix.
3.5 Modification of the Minimum Requirements
Basin Planning is encouraged and may be used to tailor Minimum Requirement #5
On-site Stormwater Management, Minimum Requirement #6 Runoff Treatment,
Minimum Requirement #7 Flow Control, and/or Minimum Requirement #8 Wetlands
Protection. Basin planning may also be used to demonstrate an equivalent level of
treatment, flow control, and/or wetland protection through the construction and use of
regional stormwater facilities. See Section 7 of this Appendix for details on Basin
Planning and how Permittees may use basin planning to modify the Minimum
Requirements in Section 4.
Section 4. Minimum Requirements
This Section describes the Minimum Requirements for stormwater management at new
development and redevelopment sites. Section 3 of this Appendix should be consulted to
determine which of the minimum requirements below apply to any given project. Figures
3.2 and 3.3 should be consulted to determine whether the minimum requirements apply to
new surfaces, replaced surfaces, or new and replaced surfaces.
4.1 Minimum Requirement #1: Preparation of Stormwater Site Plans
The permittee shall require a Stormwater Site Plan from all projects meeting the
thresholds in Section 3.1 of this Appendix. Stormwater Site Plans shall use site-
appropriate development principles, as required and encouraged by local development
codes, to retain native vegetation and minimize impervious surfaces to the extent feasible.
Stormwater Site Plans shall be prepared in accordance with Chapter 3 of Volume 1 of the
Stormwater Management Manual for Western Washington (SWMMWW).
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4.2 Minimum Requirement #2: Construction Stormwater Pollution Prevention Plan
(SWPPP)
Permittees may choose to allow compliance with this Minimum Requirement to be
achieved for an individual site if the site is covered under Ecology’s General NPDES
Permit for Stormwater Discharges Associated with Construction Activities and fully
implementing the requirements of that permit.
Thresholds
All new development and redevelopment projects are responsible for preventing erosion
and discharge of sediment and other pollutants into receiving waters.
Permittees must require a Construction Stormwater Pollution Prevention Plan (SWPPP)
for all projects which result in 2,000 sq. ft. or more of new plus replaced hard surface
area, or which disturb 7,000 sq. ft. or more of land.
Projects below those thresholds are not required to prepare a Construction SWPPP, but
must consider all of the Elements listed below for Construction SWPPPs and develop
controls for all elements that pertain to the project site. The Permittee may develop an
abbreviated SWPPP format to meet the SWPPP requirement under this permit for project
sites that will disturb less than 1 acre.
General Requirements
The SWPPP shall include a narrative and drawings. All BMPs shall be clearly referenced
in the narrative and marked on the drawings. The SWPPP narrative shall include
documentation to explain and justify the pollution prevention decisions made for the
project. Each of the thirteen elements listed below must be considered and included in the
SWPPP unless site conditions render the element unnecessary and the exemption from
that element is clearly justified in the narrative of the SWPPP.
Clearing and grading activities for developments shall be permitted only if conducted
pursuant to an approved site development plan (e.g., subdivision approval) that establishes
permitted areas of clearing, grading, cutting, and filling. These permitted clearing and
grading areas and any other areas required to preserve critical or sensitive areas, buffers,
native growth protection easements, or tree retention areas as may be required by local
jurisdictions, shall be delineated on the site plans and the development site.
The SWPPP shall be implemented beginning with initial land disturbance and until final
stabilization. Sediment and Erosion control BMPs shall be consistent with the BMPs
contained in chapter 4 of Volume II of the Stormwater Management Manual for Western
Washington (SWMMWW).
Seasonal Work Limitations - From October 1 through April 30, clearing, grading, and
other soil disturbing activities may only be authorized by the Permittee if silt-laden runoff
will be prevented from leaving the site through a combination of the following:
1. Site conditions including existing vegetative coverage, slope, soil type and
proximity to receiving waters; and
2. Limitations on activities and the extent of disturbed areas; and
3. Proposed erosion and sediment control measures.
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Based on the information provided and/or local weather conditions, the Permittee may
expand or restrict the seasonal limitation on site disturbance. The following activities are
exempt from the seasonal clearing and grading limitations:
1. Routine maintenance and necessary repair of erosion and sediment control BMPs,
2. Routine maintenance of public facilities or existing utility structures that do not
expose the soil or result in the removal of the vegetative cover to soil, and
3. Activities where there is one hundred percent infiltration of surface water runoff
within the site in approved and installed erosion and sediment control facilities.
Construction Stormwater Pollution Prevention Plan (SWPPP) Elements
1. Preserve Vegetation/Mark Clearing Limits:
a. Before beginning land disturbing activities, including clearing and grading,
clearly mark all clearing limits, sensitive areas and their buffers, and trees that are
to be preserved within the construction area.
b. Retain the duff layer, native top soil, and natural vegetation in an undisturbed
state to the maximum degree practicable.
2. Establish Construction Access:
a. Limit construction vehicle access and exit to one route, if possible.
b. Stabilize access points with a pad of quarry spalls, crushed rock, or other
equivalent BMPs, to minimize tracking of sediment onto public roads.
c. Locate wheel wash or tire baths on-site, if the stabilized constructions entrance is
not effective in preventing tracking sediment onto roads.
d. If sediment is tracked off site, clean the affected roadways thoroughly at the end
of each day, or more frequently as necessary (for example, during wet weather).
Remove sediment from roads by shoveling, sweeping, or pick up and transport the
sediment to a controlled sediment disposal area.
e. Conduct street washing only after sediment is removed in accordance with 2.d,
above.
f. Control street wash wastewater by pumping back on-site, or otherwise prevent it
from discharging into systems tributary to waters of the State.
3. Control Flow Rates:
a. Protect properties and waterways downstream of development sites from erosion
and the associated discharge of turbid waters due to increases in the velocity and
peak volumetric flow rate of stormwater runoff from the project site.
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b. Where necessary to comply with 3.a, above, construct stormwater retention or
detention facilities as one of the first steps in grading. Assure that detention
facilities function properly before constructing site improvements (e.g.,
impervious surfaces).
c. If permanent infiltration ponds are used for flow control during construction,
protect these facilities from siltation during the construction phase.
4. Install Sediment Controls:
a. Design, install, and maintain effective erosion controls and sediment controls to
minimize the discharge of pollutants.
b. Construct sediment control BMPs (sediment ponds, traps, filters, etc.) as one of
the first steps in grading. These BMPs shall be functional before other land
disturbing activities take place.
c. Minimize sediment discharges from the site. The design, installation and
maintenance of erosion and sediment controls must address factors such as the
amount, frequency, intensity and duration of precipitation, the nature of resulting
stormwater runoff, and soil characteristics, including the range of soil particle
sizes expected to be present on the site.
d. Direct stormwater runoff from disturbed areas through a sediment pond or other
appropriate sediment removal BMP, before the runoff leaves a construction site or
before discharge to an infiltration facility. Runoff from fully stabilized areas may
be discharged without a sediment removal BMP, but must meet the flow control
performance standard in 3.a, above.
e. Locate BMPs intended to trap sediment on-site in a manner to avoid interference
with the movement of juvenile salmonids attempting to enter off-channel areas or
drainages.
f. Where feasible, design outlet structures that withdraw impounded stormwater
from the surface to avoid discharging sediment that is still suspended lower in the
water column.
5. Stabilize Soils:
a. Stabilize exposed and unworked soils by application of effective BMPs that
prevent erosion. Applicable BMPs include, but are not limited to: temporary and
permanent seeding, sodding, mulching, plastic covering, erosion control fabrics
and matting, soil application of polyacrylamide (PAM), the early application of
gravel base early on areas to be paved, and dust control.
b. Control stormwater volume and velocity within the site to minimize soil erosion.
c. Control stormwater discharges, including both peak flow rates and total
stormwater volume, to minimize erosion at outlets and to minimize downstream
channel and stream bank erosion.
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d. Soils must not remain exposed and unworked for more than the time periods set
forth below to prevent erosion:
• During the dry season (May 1 – September 30): 7 days
• During the wet season (October 1 – April 30): 2 days
e. Stabilize soils at the end of the shift before a holiday or weekend if needed based
on the weather forecast.
f. Stabilize soil stockpiles from erosion, protect with sediment trapping measures,
and where possible, locate away from storm drain inlets, waterways and drainage
channels.
g. Minimize the amount of soil exposed during construction activity.
h. Minimize the disturbance of steep slopes.
i. Minimize soil compaction and, unless infeasible, preserve topsoil.
6. Protect Slopes:
a. Design and construct cut-and-fill slopes in a manner to minimize erosion.
Applicable practices include, but are not limited to, reducing continuous length of
slope with terracing and diversions, reducing slope steepness, and roughening
slope surfaces (for example, track walking).
b. Divert off-site stormwater (run-on) or ground water away from slopes and
disturbed areas with interceptor dikes, pipes and/or swales. Off-site stormwater
should be managed separately from stormwater generated on the site.
c. At the top of slopes, collect drainage in pipe slope drains or protected channels to
prevent erosion.
• Temporary pipe slope drains must handle the peak volumetric flow rate
calculated using a 10-minute time step from a Type 1A, 10-year, 24-hour
frequency storm for the developed condition. Alternatively, the 10-year 1-
hour flow rate predicted by an approved continuous runoff model, increased
by a factor of 1.6, may be used. The hydrologic analysis must use the existing
land cover condition for predicting flow rates from tributary areas outside the
project limits. For tributary areas on the project site, the analysis must use the
temporary or permanent project land cover condition, whichever will produce
the highest flow rates. If using the Western Washington Hydrology Model to
predict flows, bare soil areas should be modeled as “landscaped area.”
d. Place excavated material on the uphill side of trenches, consistent with safety and
space considerations.
e. Place check dams at regular intervals within constructed channels that are cut
down a slope.
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7. Protect Drain Inlets:
a. Protect storm drain inlets made operable during construction so that stormwater
runoff does not enter the conveyance system without first being filtered or treated
to remove sediment.
b. Clean or remove and replace inlet protection devices when sediment has filled
one-third of the available storage (unless a different standard is specified by the
product manufacturer).
8. Stabilize Channels and Outlets:
a. Design, construct, and stabilize all on-site conveyance channels to prevent erosion
from the following expected peak flows:
• Channels must handle the peak volumetric flow rate calculated using a 10-
minute time step from a Type 1A, 10-year, 24-hour frequency storm for the
developed condition. Alternatively, the 10-year, 1-hour flow rate indicated by
an approved continuous runoff model, increased by a factor of 1.6, may be
used. The hydrologic analysis must use the existing land cover condition for
predicting flow rates from tributary areas outside the project limits. For
tributary areas on the project site, the analysis shall use the temporary or
permanent project land cover condition, whichever will produce the highest
flow rates. If using the Western Washington Hydrology Model to predict
flows, bare soil areas should be modeled as “landscaped area.”
b. Provide stabilization, including armoring material, adequate to prevent erosion of
outlets, adjacent stream banks, slopes, and downstream reaches at the outlets of
all conveyance systems.
9. Control Pollutants:
a. Design, install, implement and maintain effective pollution prevention measures
to minimize the discharge of pollutants.
b. Handle and dispose all pollutants, including waste materials and demolition debris
that occur on-site in a manner that does not cause contamination of stormwater.
c. Provide cover, containment, and protection from vandalism for all chemicals,
liquid products, petroleum products, and other materials that have the potential to
pose a threat to human health or the environment. On-site fueling tanks must
include secondary containment. Secondary containment means placing tanks or
containers within an impervious structure capable of containing 110% of the
volume contained in the largest tank within the containment structure. Double-
walled tanks do not require additional secondary containment.
d. Conduct maintenance, fueling and repair of heavy equipment and vehicles using
spill prevention and control measures. Clean contaminated surfaces immediately
following any spill incident.
e. Discharge wheel wash or tire bath wastewater to a separate on-site treatment
system that prevents discharge to surface water, such as closed-loop recirculation
or upland application, or to the sanitary sewer, with local sewer district approval.
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f. Apply fertilizers and pesticides in a manner and at application rates that will not
result in loss of chemical to stormwater runoff. Follow manufacturers’ label
requirements for application rates and procedures.
g. Use BMPs to prevent contamination of stormwater runoff by pH modifying
sources. The sources for this contamination include, but are not limited to: bulk
cement, cement kiln dust, fly ash, new concrete washing and curing waters, waste
streams generated from concrete grinding and sawing, exposed aggregate
processes, dewatering concrete vaults, concrete pumping and mixer washout
waters.
h. Adjust the pH of stormwater if necessary to prevent violations of water quality
standards.
i. Assure that washout of concrete trucks is performed off-site or in designated
concrete washout areas only. Do not wash out concrete trucks onto the ground, or
into storm drains, open ditches, streets, or streams. Do not dump excess concrete
on-site, except in designated concrete washout areas. Concrete spillage or
concrete discharge to surface waters of the State is prohibited.
j. Obtain written approval from Ecology before using chemical treatment other than
CO2 or dry ice to adjust pH.
10. Control De-Watering:
a. Discharge foundation, vault, and trench de-watering water, which have similar
characteristics to stormwater runoff at the site, into a controlled conveyance
system before discharge to a sediment trap or sediment pond.
b. Discharge clean, non-turbid de-watering water, such as well-point ground water,
to systems tributary to, or directly into surface waters of the State, as specified in
8, above, provided the de-watering flow does not cause erosion or flooding of
receiving waters. Do not route clean dewatering water through stormwater
sediment ponds. Note that “surface waters of the State” may exist on a
construction site as well as off site; for example, a creek running through a site.
c. Handle highly turbid or otherwise contaminated dewatering water separately from
stormwater.
d. Other treatment or disposal options may include:
(i) Infiltration
(ii) Transport off-site in vehicle, such as a vacuum flush truck, for legal
disposal in a manner that does not pollute state waters.
(iii) Ecology-approved on-site chemical treatment or other suitable treatment
technologies.
(iv) Sanitary or combined sewer discharge with local sewer district approval, if
there is no other option.
(v) Use of a sedimentation bag that discharges to a ditch or swale for small
volumes of localized dewatering.
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11. Maintain BMPs:
a. Maintain and repair all temporary and permanent erosion and sediment control
BMPs as needed to assure continued performance of their intended function in
accordance with BMP specifications.
b. Remove all temporary erosion and sediment control BMPs within 30 days after
achieving final site stabilization or after the temporary BMPs are no longer
needed.
12. Manage the Project:
a. Phase development projects to the maximum degree practicable and take into
account seasonal work limitations.
b. Inspection and monitoring – Inspect, maintain, and repair all BMPs as needed to
assure continued performance of their intended function.
c. Maintaining an updated construction SWPPP – Maintain, update, and implement
the SWPPP.
d. Projects that disturb one or more acres must have site inspections conducted by a
Certified Erosion and Sediment Control Lead (CESCL). Project sites disturbing
less than one acre may have a CESCL or a person without CESCL certification
conduct inspections. By the initiation of construction, the SWPPP must identify
the CESCL or inspector, who must be present on-site or on-call at all times.
13. Protect Low Impact Development BMPs
a. Protect all Bioretention and Rain Garden BMPs from sedimentation through
installation and maintenance of erosion and sediment control BMPs on portions of
the site that drain into the Bioretention and/or Rain Garden BMPs. Restore the
BMPs to their fully functioning condition if they accumulate sediment during
construction. Restoring the BMP must include removal of sediment and any
sediment-laden Bioretention/rain garden soils, and replacing the removed soils
with soils meeting the design specification.
b. Prevent compacting Bioretention and Rain Garden BMPs by excluding
construction equipment and foot traffic. Protect completed lawn and landscaped
areas from compaction due to construction equipment.
c. Control erosion and avoid introducing sediment from surrounding land uses onto
permeable pavements. Do not allow muddy construction equipment on the base
material or pavement. Do not allow sediment-laden runoff onto permeable
pavements or base materials.
d. Pavements fouled with sediments or no longer passing an initial infiltration test
must be cleaned using procedures from the local stormwater manual or the
manufacturer’s procedures.
e. Keep all heavy equipment off existing soils under LID BMPs that have been
excavated to final grade to retain the infiltration rate of the soils.
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4.3 Minimum Requirement #3: Source Control of Pollution
All known, available and reasonable source control BMPs must be required for all
projects approved by the Permittee. Source control BMPs must be selected, designed, and
maintained in accordance with Volume IV of the Stormwater Management Manual for
Western Washington or an approved equivalent manual approved by Ecology.
4.4 Minimum Requirement #4: Preservation of Natural Drainage Systems and Outfalls
Natural drainage patterns shall be maintained, and discharges from the project site shall
occur at the natural location, to the maximum extent practicable. The manner by which
runoff is discharged from the project site must not cause a significant adverse impact to
downstream receiving waters and down gradient properties. All outfalls require energy
dissipation.
4.5 Minimum Requirement #5: On-site Stormwater Management
Applicability
Except as provided below, the Permittee must require On-site Stormwater Management
BMPs in accordance with the following project thresholds, standards, and lists to
infiltrate, disperse, and retain stormwater runoff on-site to the extent feasible without
causing flooding or erosion impacts.
Projects qualifying as flow control exempt in accordance with Section 4.7 of this
Appendix do not have to achieve the LID performance standard, nor consider
bioretention, rain gardens, permeable pavement, and full dispersion if using List #1 or
List #2. However, those projects must implement BMP T5.13; BMPs T5.10A, B, or C;
and BMP T5.11or T5.12, if feasible.
Project Thresholds
1. Projects triggering only Minimum Requirements #1 through #5 shall either:
a. Use On-site Stormwater Management BMPs from List #1 for all surfaces
within each type of surface in List #1; or
b. Demonstrate compliance with the LID Performance Standard. Projects
selecting this option cannot use Rain Gardens. They may choose to use
Bioretention BMPs as described in the SWMMWW 1.
2. Projects triggering Minimum Requirements #1 through #9 must meet the
requirements in Table 4.1
1 All references to the Stormwater Management Manual for Western Washington are to the 2014 amended version.
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Table 4.1: On-site Stormwater Management Requirements for Projects Triggering
Minimum Requirements #1 - #9
Project Type and Location Requirement
New development on any parcel inside the
UGA, or new development outside the
UGA on a parcel less than 5 acres
Low Impact Development Performance
Standard and BMP T5.13; or List #2
(applicant option).
New development outside the UGA on a
parcel of 5 acres or larger
Low Impact Development Performance
Standard and BMP T5.13.
Redevelopment on any parcel inside the
UGA, or redevelopment outside the UGA
on a parcel less than 5 acres
Low Impact Development Performance
Standard and BMP T5.13; or List #2
(applicant option).
Redevelopment outside the UGA on a
parcel of 5 acres or larger
Low Impact Development Performance
Standard and BMP T5.13.
NOTE: This table refers to the Urban Growth Area (UGA) as designated under the
Growth Management Act (GMA) (chapter 36.70A RCW) of the State of Washington. If
the Permittee is located in a county that is not subject to planning under the GMA, the
city limits shall be used instead.
Low Impact Development Performance Standard
Stormwater discharges shall match developed discharge durations to pre-developed
durations for the range of pre-developed discharge rates from 8% of the 2-year peak flow
to 50% of the 2-year peak flow. Refer to the Standard Flow Control Requirement section
in Minimum Requirement #7 for information about the assignment of the pre-developed
condition. Project sites that must also meet minimum requirement #7 shall match flow
durations between 8% of the 2-year flow through the full 50-year flow.
List #1: On-site Stormwater Management BMPs for Projects Triggering Minimum
Requirements #1 through #5
For each surface, consider the BMP’s in the order listed for that type of surface. Use the
first BMP that is considered feasible. No other On-site Stormwater Management BMP is
necessary for that surface. Feasibility shall be determined by evaluation against:
1. Design criteria, limitations, and infeasibility criteria identified for each BMP in
the SWMMWW; and
2. Competing Needs Criteria listed in Chapter 5 of Volume V of the SWMMWW.
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Lawn and landscaped areas:
• Post-Construction Soil Quality and Depth in accordance with BMP T5.13 in
Chapter 5 of Volume V of the SWMMWW
Roofs:
1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the
SWMMWW, or Downspout Full Infiltration Systems in accordance with BMP
T5.10A in Section 3.1.1 of Volume III of the SWMMWW.
2. Rain Gardens in accordance with BMP T5.14A in Chapter 5 of Volume V, or
Bioretention in accordance with Chapter 7 of Volume V of the SWMMWW. The
rain garden or bioretention facility must have a minimum horizontal projected
surface area below the overflow which is at least 5% of the area draining to it.
3. Downspout Dispersion Systems in accordance with BMP T5.10B in Section 3.1.2
of Volume III of the SWMMWW.
4. Perforated Stub-out Connections in accordance with BMP T5.10C in Section
3.1.3 of Volume III of the SWMMWW.
Other Hard Surfaces:
1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the
SWMMWW.
2. Permeable pavement 2 in accordance with BMP T5.15 in Chapter 5 of Volume V
of the SWMMWW, or Rain Gardens in accordance with BMP T5.14A in Chapter 5
of Volume V, or Bioretention in accordance with Chapter 7 of Volume V of the
SWMMWW. The rain garden or bioretention facility must have a minimum
horizontal projected surface area below the overflow which is at least 5% of the
area draining to it.
3. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow
Dispersion in accordance with BMP T5.11 in Chapter 5 of Volume V of the
SWMMWW.
List #2: On-site Stormwater Management BMPs for Projects Triggering Minimum
Requirements #1 through #9
For each surface, consider the BMPs in the order listed for that type of surface. Use the
first BMP that is considered feasible. No other On-site Stormwater Management BMP is
necessary for that surface. Feasibility shall be determined by evaluation against:
1. Design criteria, limitations, and infeasibility criteria identified for each BMP in
the SWMMWW; and
2. Competing Needs Criteria listed in Chapter 5 of Volume V of the SWMMWW.
2 This is not a requirement to pave these surfaces. Where pavement is proposed, it must be permeable to the extent
feasible unless full dispersion is employed.
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Lawn and landscaped areas:
• Post-Construction Soil Quality and Depth in accordance with BMP T5.13 in
Chapter 5 of Volume V of the SWMMWW
Roofs:
1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the
SWMMWW, or Downspout Full Infiltration Systems in accordance with BMP
T5.10A in Section 3.1.1 of Volume III of the SWMMWW
2. Bioretention (See Chapter 7 of Volume V of the SWMMWW) facilities that have a
minimum horizontally projected surface area below the overflow which is at least
5% of the of the total surface area draining to it
3. Downspout Dispersion Systems in accordance with BMP T5.10B in Section 3.1.2
of Volume III of the SWMMWW
4. Perforated Stub-out Connections in accordance with BMP T5.10C in Section
3.1.3 of Volume III of the SWMMWW.
Other Hard Surfaces:
1. Full Dispersion in accordance with BMP T5.30 in Chapter 5 of Volume V of the
SWMMWW
2. Permeable pavement2 in accordance with BMP T5.15 in Chapter 5 of Volume V
of the SWMMWW
3. Bioretention (See Chapter 7, Volume V of the SWMMWW) facilities that have a
minimum horizontally projected surface area below the overflow which is at least
5% of the total surface area draining to it.
4. Sheet Flow Dispersion in accordance with BMP T5.12, or Concentrated Flow
Dispersion in accordance with BMP T5.11 in Chapter 5 of Volume V of the
SWMMWW
4.6 Minimum Requirement #6: Runoff Treatment
Project Thresholds
When assessing a project against the following thresholds, only consider those hard
and pervious surfaces that are subject to this minimum requirement as determined in
Section 3 of this Appendix.
The following require construction of stormwater treatment facilities:
• Projects in which the total of pollution-generating hard surface (PGHS) is 5,000
square feet or more in a threshold discharge area of the project, or
• Projects in which the total of pollution-generating pervious surfaces (PGPS) – not
including permeable pavements - is three-quarters (3/4) of an acre or more in a
threshold discharge area, and from which there will be a surface discharge in a
natural or man-made conveyance system from the site.
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Treatment-Type Thresholds
1. Oil Control:
Treatment to achieve Oil Control applies to projects that have “high-use sites.”
High-use sites are those that typically generate high concentrations of oil due to
high traffic turnover or the frequent transfer of oil. High-use sites include:
a. An area of a commercial or industrial site subject to an expected average
daily traffic (ADT) count equal to or greater than 100 vehicles per 1,000
square feet of gross building area;
b. An area of a commercial or industrial site subject to petroleum storage and
transfer in excess of 1,500 gallons per year, not including routinely delivered
heating oil;
c. An area of a commercial or industrial site subject to parking, storage or
maintenance of 25 or more vehicles that are over 10 tons gross weight
(trucks, buses, trains, heavy equipment, etc.);
d. A road intersection with a measured ADT count of 25,000 vehicles or more
on the main roadway and 15,000 vehicles or more on any intersecting
roadway, excluding projects proposing primarily pedestrian or bicycle use
improvements.
2. Phosphorus Treatment:
The requirement to provide phosphorous control is determined by the local
government with jurisdiction (e.g., through a lake management plan), or the
Department of Ecology (e.g., through a waste load allocation). The local
government may have developed a management plan and implementing
ordinances or regulations for control of phosphorus from new/redevelopment for
the receiving water(s) of the stormwater drainage. The local government can use
the following sources of information for pursuing plans and implementing
ordinances and/or regulations:
a. Those waterbodies reported under section 305(b) of the Clean Water Act, and
designated as not supporting beneficial uses due to phosphorous;
b. Those listed in Washington State's Nonpoint Source Assessment required
under section 319(a) of the Clean Water Act due to nutrients.
3. Enhanced Treatment:
Except where specified below under “4. Basic Treatment”, Enhanced treatment
for reduction in dissolved metals is required for the following project sites that: 1)
discharge directly to fresh waters or conveyance systems tributary to fresh waters
designated for aquatic life use or that have an existing aquatic life use; or 2) use
infiltration strictly for flow control – not treatment – and the discharge is within ¼
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mile of a fresh water designated for aquatic life use or that has an existing aquatic
life use:
Industrial project sites,
Commercial project sites,
Multi-family project sites, and
High AADT roads as follows:
Within Urban Growth Management Areas:
• Fully controlled and partially controlled limited access highways with
Annual Average Daily Traffic (AADT) counts of 15,000 or more
• All other roads with an AADT of 7,500 or greater
Outside of Urban Growth Management Areas:
• Roads with an AADT of 15,000 or greater unless discharging to a 4th
Strahler order stream or larger;
• Roads with an AADT of 30,000 or greater if discharging to a 4th Strahler
order stream or larger (as determined using 1:24,000 scale maps to
delineate stream order).
Any areas of the above-listed project sites that are identified as subject to Basic
Treatment requirements (below), are not also subject to Enhanced Treatment
requirements. For developments with a mix of land use types, the Enhanced
Treatment requirement shall apply when the runoff from the areas subject to the
Enhanced Treatment requirement comprise 50% or more of the total runoff within
a threshold discharge area.
4. Basic Treatment:
Basic Treatment is required in the following circumstances:
• Project sites that discharge to the ground, UNLESS:
1) The soil suitability criteria for infiltration treatment are met (See
Chapter 3, Volume III of the SWMMWW), and alternative pretreatment
is provided (see Chapter 6, Volume V of the SWMMWW); or
2) The project site uses infiltration strictly for flow control – not treatment
- and the discharge is within ¼-mile of a phosphorus sensitive lake
(use a Phosphorus Treatment facility), or
3) The project site is industrial, commercial, multi-family residential, or a
high AADT road (consistent with the Enhanced Treatment-type
thresholds listed above) and is within ¼ mile of a fresh water
designated for aquatic life use or that has an existing aquatic life
use.(use an Enhanced Treatment facility).
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• Residential projects not otherwise needing phosphorus control as
designated by USEPA, the Department of Ecology, or by the Permittee;
• Project sites discharging directly (or indirectly through a municipal
separate storm sewer system) to Basic Treatment Receiving Waters
(Appendix I-C of the SWMMWW);
• Project sites that drain to fresh water that is not designated for aquatic life
use, and does not have an existing aquatic life use; and project sites that
drain to waters not tributary to waters designated for aquatic life use or
that have an existing aquatic life use;
• Landscaped areas of industrial, commercial, and multi-family project sites,
and parking lots of industrial and commercial project sites that do not
involve pollution-generating sources (e.g., industrial activities, customer
parking, storage of erodible or leachable material, wastes or chemicals)
other than parking of employees’ private vehicles. For developments with
a mix of land use types, the Basic Treatment requirement shall apply when
the runoff from the areas subject to the Basic Treatment requirement
comprise 50% or more of the total runoff within a threshold discharge
area.
Treatment Facility Sizing
Size stormwater treatment facilities for the entire area that drains to them, even if some of
those areas are not pollution-generating, or were not included in the project site threshold
decisions (Section 3 of this appendix) or the treatment threshold decisions of this
minimum requirement.
Water Quality Design Storm Volume: The volume of runoff predicted from a 24-hour
storm with a 6-month return frequency (a.k.a., 6-month, 24-hour storm). Wetpool
facilities are sized based upon the volume of runoff predicted through use of the Natural
Resource Conservation Service curve number equations in Chapter 2 of Volume III of the
SWMMWW), for the 6-month, 24-hour storm. Alternatively, when using an approved
continuous runoff model, the water quality design storm volume shall be equal to the
simulated daily volume that represents the upper limit of the range of daily volumes that
accounts for 91% of the entire runoff volume over a multi-decade period of record.
Water Quality Design Flow Rate
1. Preceding Detention Facilities or when Detention Facilities are not required:
The flow rate at or below which 91% of the runoff volume, as estimated by an
approved continuous runoff model, will be treated. Design criteria for treatment
facilities are assigned to achieve the applicable performance goal (e.g., 80% TSS
removal) at the water quality design flow rate. At a minimum, 91% of the total
runoff volume, as estimated by an approved continuous runoff model, must pass
through the treatment facility(ies) at or below the approved hydraulic loading rate
for the facility(ies).
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2. Downstream of Detention Facilities:
The water quality design flow rate must be the full 2-year release rate from the
detention facility.
Treatment Facility Selection, Design, and Maintenance
Stormwater treatment facilities shall be:
• Selected in accordance with the process identified in Chapter 4 of Volume I, and
Chapter 2 of Volume V of the SWMMWW,
• Designed in accordance with the design criteria in Volume V of the SWMMWW,
and
• Maintained in accordance with the maintenance schedule in Volume V of the
SWMMWW.
Additional Requirements
The discharge of untreated stormwater from pollution-generating hard surfaces to ground
water must not be authorized by the Permittee, except for the discharge achieved by
infiltration or dispersion of runoff through use of On-site Stormwater Management
BMPs in accordance with Chapter 5, Volume V and Chapter 7, Volume V of the
SWMMWW; or by infiltration through soils meeting the soil suitability criteria in Chapter
3 of Volume III of the SWMMWW.
4.7 Minimum Requirement #7: Flow Control
Applicability
Except as provided below, the Permittee must require all projects provide flow control to
reduce the impacts of stormwater runoff from hard surfaces and land cover conversions.
The requirement below applies to projects that discharge stormwater directly, or
indirectly through a conveyance system, into a fresh water body.
Flow control is not required for projects that discharge directly to, or indirectly through
an MS4 to a water listed in Appendix I-E of the SWMMWW subject to the following
restrictions:
• Direct discharge to the exempt receiving water does not result in the diversion of
drainage from any perennial stream classified as Types 1, 2, 3, or 4 in the State of
Washington Interim Water Typing System, or Types “S”, “F”, or “Np” in the
Permanent Water Typing System, or from any category I, II, or III wetland; and
• Flow splitting devices or drainage BMP’s are applied to route natural runoff volumes
from the project site to any downstream Type 5 stream or category IV wetland:
o Design of flow splitting devices or drainage BMP’s will be based on
continuous hydrologic modeling analysis. The design will assure that flows
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delivered to Type 5 stream reaches will approximate, but in no case exceed,
durations ranging from 50% of the 2-year to the 50-year peak flow.
o Flow splitting devices or drainage BMP’s that deliver flow to category IV
wetlands will also be designed using continuous hydrologic modeling to
preserve pre-project wetland hydrologic conditions unless specifically waived
or exempted by regulatory agencies with permitting jurisdiction; and
• The project site must be drained by a conveyance system that is comprised entirely of
manmade conveyance elements (e.g., pipes, ditches, outfall protection) and extends to
the ordinary high water line of the exempt receiving water; and
• The conveyance system between the project site and the exempt receiving water shall
have sufficient hydraulic capacity to convey discharges from future build-out
conditions (under current zoning) of the site, and the existing condition from non-
project areas from which runoff is or will be collected; and
• Any erodible elements of the manmade conveyance system must be adequately
stabilized to prevent erosion under the conditions noted above.
If the discharge is to a stream that leads to a wetland, or to a wetland that has an outflow
to a stream, both this minimum requirement (Minimum Requirement #7) and Minimum
Requirement #8 apply.
Permittees may petition Ecology to exempt projects in additional areas. A petition must
justify the proposed exemption based upon a hydrologic analysis that demonstrates that
the potential stormwater runoff from the exempted area will not significantly increase the
erosion forces on the stream channel nor have near-field impacts.
Thresholds
When assessing a project against the following thresholds, consider only those
impervious, hard, and pervious surfaces that are subject to this minimum requirement as
determined in Section 3 of this Appendix.
The following circumstances require achievement of the standard flow control
requirement for western Washington:
• Projects in which the total of effective impervious surfaces is 10,000 square feet or
more in a threshold discharge area, or
• Projects that convert ¾ acres or more of vegetation to lawn or landscape, or convert
2.5 acres or more of native vegetation to pasture in a threshold discharge area, and
from which there is a surface discharge in a natural or man-made conveyance system
from the site, or
• Projects that through a combination of hard surfaces and converted vegetation areas
cause a 0.10 cubic feet per second (cfs) increase or greater in the 100-year flow
frequency from a threshold discharge area as estimated using the Western
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Washington Hydrology Model or other approved model and one-hour time steps (or a
0.15 cfs increase or greater using 15-minute time steps).3
Standard Flow Control Requirement
Stormwater discharges shall match developed discharge durations to pre-developed
durations for the range of pre-developed discharge rates from 50% of the 2-year peak
flow up to the full 50-year peak flow. The pre-developed condition to be matched shall be
a forested land cover unless:
• Reasonable, historic information is available that indicates the site was prairie prior to
settlement (modeled as “pasture” in the Western Washington Hydrology Model); or
• The drainage area of the immediate stream and all subsequent downstream basins
have had at least 40% total impervious area since 1985. In this case, the pre-
developed condition to be matched shall be the existing land cover condition. The
map in Appendix I-G of the SWMMWW depicts those areas which meet this
criterion. Where basin-specific studies determine a stream channel to be unstable,
even though the above criterion is met, the pre-developed condition assumption shall
be the “historic” land cover condition, or a land cover condition commensurate with
achieving a target flow regime identified by an approved basin study.
This standard requirement is waived for sites that will reliably infiltrate all the runoff
from hard surfaces and converted vegetation areas.
Western Washington Alternative Requirement
An alternative requirement may be established through application of watershed-scale
hydrological modeling and supporting field observations. Possible reasons for an
alternative flow control requirement include:
• Establishment of a stream–specific threshold of significant bedload movement other
than the assumed 50% of the 2-year peak flow;
• Zoning and Land Clearing Ordinance restrictions that, in combination with an
alternative flow control standard, maintain or reduce the naturally occurring erosive
forces on the stream channel; or
• A duration control standard is not necessary for protection, maintenance, or
restoration of designated and existing beneficial uses or Clean Water Act compliance.
See Section 7 Basin/Watershed Planning of this Appendix for details on how alternative
flow control requirements may be established.
3 The 0.10 cfs (one-hour time steps) or 0.15 cfs (15-minute time steps) increase should be a comparison of the post-
project runoff to the existing condition runoff. For the purpose of applying this threshold, the existing condition is
either the pre-project land cover, or the land cover that existed at the site as of a date when the local jurisdiction first
adopted flow control requirements into code or rules.
Western Washington Phase II Municipal Stormwater Permit
______________________________________________________________________________
August 1, 2013, Modified January 16, 2015 Appendix 1- Minimum Technical Requirements
Page 30 of 32
Additional Requirement
Flow Control BMPs shall be selected, designed, and maintained in accordance with
Volume III of the SWMMWW or an approved equivalent.
4.8 Minimum Requirement #8: Wetlands Protection
Applicability
The requirements below apply only to projects whose stormwater discharges into a
wetland, either directly or indirectly through a conveyance system.
Thresholds
The thresholds identified in Minimum Requirement #6 – Runoff Treatment, and
Minimum Requirement #7 – Flow Control shall also be applied to determine the
applicability of this requirement to discharges to wetlands.
Standard Requirement
Projects shall comply with Guide Sheets #1 through #3 in Appendix I-D of the
SWMMWW. The hydrologic analysis shall use the existing land cover condition to
determine the existing hydrologic conditions unless directed otherwise by a regulatory
agency with jurisdiction.
Additional Requirements
Stormwater treatment and flow control facilities shall not be built within a natural
vegetated buffer, except for:
• Necessary conveyance systems as approved by the Permittee; or
• As allowed in wetlands approved for hydrologic modification and/or treatment in
accordance with Guide Sheet 2 in Appendix I-D of the SWMMWW.
An adopted and implemented basin plan prepared in accordance with the provisions of
Section 7 of this Appendix may be used to develop requirements for wetlands that are
tailored to a specific basin.
4.9 Minimum Requirement #9: Operation and Maintenance
Permittees must require an operation and maintenance manual that is consistent with the
provisions in Volume V of the SWMMWW for proposed stormwater facilities and BMPs.
The party (or parties) responsible for maintenance and operation shall be identified in the
operation and maintenance manual. For private facilities approved by the Permittee, a
copy of the operation and maintenance manual shall be retained on-site or within
reasonable access to the site, and shall be transferred with the property to the new owner.
For public facilities, a copy of the operation and maintenance manual shall be retained in
the appropriate department. A log of maintenance activity that indicates what actions
were taken shall be kept and be available for inspection by the local government.
Western Washington Phase II Municipal Stormwater Permit
______________________________________________________________________________
August 1, 2013, Modified January 16, 2015 Appendix 1- Minimum Technical Requirements
Page 31 of 32
Section 5. Adjustments
Adjustments to the Minimum Requirements may be granted by the Permittee provided that a
written finding of fact is prepared, that addresses the following:
• The adjustment provides substantially equivalent environmental protection.
• Based on sound Engineering practices, the objectives of safety, function,
environmental protection and facility maintenance, are met.
Section 6. Exceptions/Variances
Exceptions/variances (exceptions) to the Minimum Requirements may be granted by the
Permittee following legal public notice of an application for an exception or variance, legal
public notice of the Permittee’s decision on the application, and written findings of fact that
documents the Permittees determination to grant an exception. Permittees shall keep records,
including the written findings of fact, of all local exceptions to the Minimum Requirements.
Project-specific design exceptions based on site-specific conditions do not require prior approval
of Ecology. The Permittee must seek prior approval by Ecology for any jurisdiction-wide
exception.
The Permittee may grant an exception to the minimum requirements if such application imposes
a severe and unexpected economic hardship. To determine whether the application imposes a
severe and unexpected economic hardship on the project applicant, the Permittee must consider
and document with written findings of fact the following:
• The current (pre-project) use of the site, and
• How the application of the minimum requirement(s) restricts the proposed use of
the site compared to the restrictions that existed prior to the adoption of the
minimum requirements; and
• The possible remaining uses of the site if the exception were not granted; and
• The uses of the site that would have been allowed prior to the adoption of the
minimum requirements; and
• A comparison of the estimated amount and percentage of value loss as a result of
the minimum requirements versus the estimated amount and percentage of value
loss as a result of requirements that existed prior to adoption of the minimum
requirements; and
• The feasibility for the owner to alter the project to apply the minimum
requirements.
In addition any exception must meet the following criteria:
• The exception will not increase risk to the public health and welfare, nor be
injurious to other properties in the vicinity and/or downstream, and to the quality
of waters of the state; and
• The exception is the least possible exception that could be granted to comply with
the intent of the Minimum Requirements.
Western Washington Phase II Municipal Stormwater Permit
______________________________________________________________________________
August 1, 2013, Modified January 16, 2015 Appendix 1- Minimum Technical Requirements
Page 32 of 32
Section 7. Basin/Watershed Planning
Basin/Watershed planning may be used by the Permittee to tailor Minimum Requirement #5
On-site Stormwater Management, Minimum Requirement #6 Runoff Treatment, Minimum
Requirement #7 Flow Control, and/or Minimum Requirement #8 Wetlands Protection. Basin
planning may also be used to demonstrate an equivalent level of treatment, flow control, and/or
wetland protection through the construction and use of regional stormwater facilities.
Basin planning provides a mechanism by which the minimum requirements and implementing
BMP’s can be evaluated and refined based on an analysis of a basin or watershed. Basin plans
may be used to develop control strategies to address impacts from future development and to
correct specific problems whose sources are known or suspected. Basin plans can be effective at
addressing both long-term cumulative impacts of pollutant loads and short-term acute impacts of
pollutant concentrations, as well as hydrologic impacts to streams, wetlands, and ground water
resources.
Basin planning will require the use of continuous runoff computer models and field work to
verify and support the models. Permittees who are considering the use of basin/watershed plans
to modify or tailor one or more of the minimum requirements are encouraged to contact Ecology
early in the planning stage.
Some examples of how Basin Planning can alter the minimum requirements are given in
Appendix I-A from the SWMMWW.
In order for a basin plan to serve as a means of modifying the minimum requirements the
following conditions must be met:
• The plan must be formally adopted by all jurisdictions with responsibilities under
the plan; and
• All ordinances or regulations called for by the plan must be in effect; and
• The basin plan must be reviewed and approved by Ecology.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 1
APPENDIX 2 – Total Maximum Daily Load (TMDL)
Requirements
Additional permit requirements are based on applicable TMDLs in accordance with Special
Condition S7 Compliance with Total Maximum Daily Load Requirements.
1. WRIA 1 - Nooksack River Watershed Bacteria Page 2
4. WRIA 5 – Stillaguamish River Page 3
5. WRIA 7 – Snohomish River Tributaries Page 5
6. WRIA 8 – North Creek Page 7
7. WRIA 8 - Swamp Creek Page 9
8. WRIA 8 - Bear-Evans Creek Page 11
9. WRIA 8 – Cottage Lake Page 12
10. WRIA 8 – Issaquah Creek Basin Page 12
11. WRIA 8 – Little Bear Creek Page 13
12. WRIA 10 – Puyallup River Page 15
11. WRIA 10 Clarks Creek (Fecal Coliform) Page 17
13. WRIA 10 - South Prairie Creek Page 18
14. WRIA 11 – Nisqually River Page 19
15. WRIA 13 – Henderson Inlet Watershed Page 20
16. WRIA 15 – Sinclair-Dyes Inlet Page 23
18. WRIA 22 – Grays Harbor/Chehalis River Page 26
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 2
Name of TMDL Nooksack River Watershed Bacteria TMDL
Document(s) for
TMDL
Nooksack River Watershed Bacteria Total Maximum Daily Load, June
2000. Ecology Publication No. 00-10-036
Nooksack River Watershed Bacteria Total Maximum Daily Load
Detailed
Implementation Plan, January 2002. Ecology Publication No. 01-10-060
http://www.ecy.wa.gov/programs/wq/tmdl/TMDLsbyWria/TMDLbyWria.html
Location of
Original 303(d)
Listings
WA-01-1010, WA-01-1012, WA-01-1014, WA-01-1015, WA-01-1016,
WA-01-1110, WA-01-1111, WA-01-1115, WA-01-1116, WA-01-1117,
WA-01-1118, WA-01-1119, WA-01-1120, WA-01-1125, AR42TO,
BX84LO, UZ70KA, LLPL
Area Where
TMDL
Requirements
Apply
TMDL coverage includes areas served by an MS4 draining to the
Nooksack River and its tributaries, Fishtrap Creek, Bertrand Creek,
Double Ditch drain, Duffner Ditch, Bender road ditch, between Nugents
Corner and Marine Drive.
Parameter(s) Fecal Coliform.
EPA Approval
Date
August 8, 2000
MS4 Permittee: Phase II Permit: City of Ferndale WAR04-5552
Phase II Permit: City of Lynden
Actions Required
City of Ferndale
Continue bacteria sampling under Ecology-approved Stormwater Quality Monitoring for Fecal
Coliform bacteria QAPP dated 6/19/2009.
• Once the City of Ferndale reduces fecal coliform bacteria below state water quality
standards in the current outfall sampling area, the City of Ferndale should designate a
new representative area for continued fecal coliform sampling at MS4 outfalls.
• With each annual report, the City of Ferndale shall submit an up to date Stormwater
Capital Improvement plan to address existing deficiencies in the stormwater treatment
and conveyance system.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 3
City of Lynden
The City of Lynden shall designate a high priority area discharging to its MS4 system for fecal
coliform sampling at a representative outfall location, and submit a Stormwater Capital
Improvement Plan with each annual report.
• City of Lynden shall designate a high priority sampling location from an MS4 outfall.
• City of Lynden shall submit a fecal coliform Quality Assurance Project Plan (QAPP) to
Ecology for review and approval by December 1, 2013. Monitoring shall be ongoing
from March 2014 to the end of the permit term.
• With each annual report, City of Lynden shall submit the monitoring results and an up to
date Stormwater Capital Improvement Plan to address existing deficiencies in the
stormwater treatment and conveyance system.
Name of TMDL Stillaguamish River
EPA Approved
Document(s) for
TMDL
Stillaguamish River Watershed Fecal Coliform, Dissolved Oxygen, pH,
Arsenic, and Mercury Total Maximum Daily Load (Water Cleanup Plan) -
Submittal Report, May 2005, Ecology Publication No. 05-10-044.
http://www.ecy.wa.gov/biblio/0510044.html
Stillaguamish River Watershed Fecal Coliform, Dissolved Oxygen, pH,
Arsenic, and Mercury Total Maximum Daily Load (Water Cleanup Plan) -
Water Quality Implementation Plan, June 2007, Ecology Publication No.
07-10-033. http://www.ecy.wa.gov/biblio/0710033.html
Location of
Original 303(d)
Listings
QJ28UC, HD76OJ, JU33JU, GH05SX, IJ55EP, VJ74AO, 390KRD,
OT80TY, QE93BW, ZO73WL, WO38NV, SN06ZT, LU17DC
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the Permittees’ municipal
stormwater permit and draining to fresh or marine waters within Water
Resource Inventory Area (WRIA) 5
Parameter Fecal Coliform, Dissolved Oxygen
EPA Approval
Date
June 21, 2005
MS4 Permittee Phase I Permit: Snohomish County
Phase II Permit: Arlington
Actions Required
Business Inspections: Each Permittee shall inspect commercial animal handling areas and
commercial composting facilities to ensure implementation of source control BMPs for bacteria.
Commercial animal handling areas are associated with Standard Industrial Code (SIC) 074 and
075 and include veterinary and pet care/boarding services, animal slaughtering, and support
activities for animal production. Facilities where the degradation and transformation of organic
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 4
solid waste takes place under controlled conditions designed to promote aerobic decomposition
are considered composting facilities (definition in accordance with Chapter 173-350 WAC). All
qualifying facilities shall be inspected by August 1, 2016 Permittees shall implement an ongoing
inspection program to re-inspect facilities with bacteria source control problems a minimum of
every three years.
Public Education and Outreach: Each Permittee shall conduct public education and outreach
activities to increase awareness of bacterial pollution problems and promote proper pet waste
management behavior.
Operations & Maintenance: Each Permittee shall install and maintain animal waste collection
and/or education stations at municipal parks and other Permittee owned and operated lands
reasonably expected to have substantial domestic animal (dog and horse) use and the potential
for pollution of stormwater.
IDDE Field Screening: Each Permittee shall conduct illicit discharge detection and elimination
(IDDE) field screening for bacteria sources in MS4 subbasins which discharge to surface waters
in the area where these TMDL requirements apply. Phase II cities shall screen 100% of these
MS4 subbasins by the expiration date of the permit. Snohomish County shall screen 50% of rural
MS4 basins in the TMDL area by the expiration date of the permit unless the option to combine
this requirement with the surface water monitoring requirement is selected below. Permittees
shall implement the schedules and activities identified in S5.C.8 of the Phase I permit or S5.C.3
of the Western Washington Phase II permit in response to any illicit discharges found.
Surface Water Monitoring: Each Permittee shall select surface water monitoring location(s) as
appropriate for characterization and long term trends evaluation of fecal coliform. Each
Permittee shall submit a draft QAPP to Ecology for review and approval, no later than February
2, 2015. If Ecology does not request changes within 60 days, the draft QAPP is considered
approved. At a minimum, the monitoring program shall:
• Begin by August 1, 2015.
• Collect 12 samples in at least one location per calendar year.
• Submit available data to the Environmental Information Management (EIM) database by
May 31 of each year.
• Provide a data summaries and narrative evaluation of the data in each annual report’s
TMDL summary.
• Be documented in a QAPP which follows Guidelines for Preparing Quality Assurance
Project Plans for Environmental Studies, July 2004, Ecology Publication No. 04-03-030
Permittees shall follow Ecology-approved QAPPs unless changes are approved by Ecology.
Permittees subject to multiple TMDL monitoring requirements may conduct an integrated
monitoring program in accordance with an Ecology-approved QAPP. Snohomish County may
combine the targeted IDDE field screening requirement, above, with the surface water
monitoring requirement as documented in the County’s microbial water quality assessment
(MWQA), or similar, program per an Ecology-approved QAPP.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 5
Name of TMDL Snohomish River Tributaries
EPA Approved
Document(s) for
TMDL
Water Quality Assessment of Tributaries to the Snohomish River and
Nonpoint Source Pollution TMDL, September 1997, Ecology Publication
No. 97-334. www.ecy.wa.gov/biblio/97334.html
Snohomish River Tributaries Fecal Coliform Total Maximum Daily Load
Submittal Report, June 2001, Ecology publication No. 00-10-087.
www.ecy.wa.gov/biblio/0010087.html
Lower Snohomish River Tributaries Fecal Coliform Bacterial Total
Maximum Daily Load: Detailed Implementation Plan, June 2003,
Ecology Publication No. 03-10-031.
www.ecy.wa.gov//biblio/0310031.html
Location of
Original 303(d)
Listings
WA-07-1012, WA-07-015, WA-07-1052, WA-07-1163WA-07-1163,
WA-07-1030 and WA-07-040
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the Permittees’
municipal stormwater permit and draining to the WASWIS segment
number, and all upstream tributaries within the jurisdiction of the
Permittee and within the geographic area covered by this permit
contributing to waterbodies: Allen Creek, YT94RF: Quilceda Creek,
TH58TS: French Creek, XZ24XU: Woods Creek, FZ74HO: Pilchuck
River, NF79WA: Marshland Watershed, XW79FQ.
Parameter Fecal Coliform
EPA Approval
Date
August 9, 2001
MS4 Permittee Phase I Permit: Snohomish County
Phase II Permit: Granite Falls, Lake Stevens, Monroe, Snohomish,
Marysville, Arlington, Everett
Actions Required
Business Inspections: Each Permittee shall inspect commercial animal handling areas and
commercial composting facilities to ensure implementation of source control BMPs for bacteria.
Commercial animal handling areas are associated with Standard Industrial Code (SIC) 074 and
075 and include veterinary and pet care/boarding services, animal slaughtering, and support
activities for animal production. Facilities where the degradation and transformation of organic
solid waste takes place under controlled conditions designed to promote aerobic decomposition
are considered composting facilities (definition in accordance with Chapter 173-350 WAC). All
qualifying facilities shall be inspected by August 1, 2016. Permittees shall implement an ongoing
inspection program to re-inspect facilities with bacteria source control problems a minimum of
every three years.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 6
Public Education and Outreach: Each Permittee shall conduct public education and outreach
activities to increase awareness of bacterial pollution problems and promote proper pet waste
management behavior.
Operations & Maintenance: Each Permittee shall install and maintain animal waste collection
and/or education stations at municipal parks and other Permittee owned and operated lands
reasonably expected to have substantial domestic animal (dog and horse) use and the potential
for pollution of stormwater.
IDDE: Permittees conducting IDDE-related field screening under S5.C.8 of the Phase I permit
or S5.C.3 of the Western Washington Phase II permit shall screen for bacteria sources in any
screened MS4 subbasins which discharge to surface waters in the TMDL area.
Targeted Source Identification & Elimination: By February 2, 2014, each Permittee shall
review the fecal coliform data collected per approved QAPPs under the 2007 Permit. The
purpose of this review is to identify a minimum of one high priority area (such as a tributary or a
stream segment) that will be the focus of source identification and elimination efforts during this
permit cycle. Each Permittee shall prepare written documentation of this review and the
identified high priority area; documentation shall be submitted with the Annual Report for 2014.
Permittees shall begin to implement source identification and elimination efforts in the MS4
subbasins discharging to the identified high priority area no later than August 1, 2014. Permittees
are encouraged to address potential bacteria pollution sources not associated with the MS4.
Stormwater quality sampling for bacteria sources is required as part of this focused source
identification and elimination effort. Permittees shall implement the schedules and activities
identified in S5.C.8 of the Phase I permit or S5.C.3 of the Western Washington Phase II permit
in response to any illicit discharges found. Each annual report’s TMDL summary shall include
qualitative and quantitative information about the source identification and elimination activities,
including procedures followed and sampling results, implemented in the selected high priority
area(s).
Surface Water Monitoring: Each Permittee shall review the fecal coliform data collected per
approved QAPPs under the 2007 Permit and select surface water monitoring location(s) as
appropriate for continued characterization and long term trends evaluation of fecal coliform.
Each Permittee shall submit a draft revised QAPP to Ecology for review and approval, no later
than February 2, 2015. If Ecology does not request changes within 60 days, the draft QAPP is
considered approved. At a minimum, the monitoring program shall:
• Begin by August 1, 2015.
• Collect 12 samples in at least one location per calendar year.
• Submit available data to the Environmental Information Management (EIM) database by
May 31 of each year.
• Provide data summaries and narrative evaluation of the data in each annual report’s
TMDL summary.
• Be documented in a QAPP which follows Guidelines for Preparing Quality Assurance
Project Plans for Environmental Studies, July 2004, Ecology Publication No. 04-03-030.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 7
Permittees shall follow Ecology-approved QAPPs unless changes are approved by Ecology.
Permittees subject to multiple TMDL monitoring requirements may conduct an integrated
monitoring program in accordance with an Ecology-approved QAPP. Snohomish County may
combine the high priority area source identification and elimination requirement with the surface
water monitoring requirement as documented in the County’s microbial water quality assessment
(MWQA), or similar, program per an Ecology-approved QAPP.
Name of TMDL North Creek
EPA Approved
Document(s) for
TMDL
North Creek Watershed: Total Maximum Daily Load Evaluation for Fecal
Coliform Bacteria, June 2001, Ecology Publication No. 01-03-020.
http://www.ecy.wa.gov/biblio/0103020.html
North Creek Fecal Coliform Total Maximum Daily Load Submittal Report,
June 2002, Ecology publication No. 02-10-020.
http://www.ecy.wa.gov/biblio/0210020.html
North Creek Fecal Coliform Bacteria Total Maximum Daily Load: Detailed
Implementation Plan, October 2003, Ecology Publication No. 03-10-047.
http://www.ecy.wa.gov/biblio/0310047.html
Location of
Original 303(d)
Listings
WA-08-1065
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the Permittees’ municipal
stormwater permit and draining to the portion of the WASWIS segment
SM74QQ starting at the confluence with the Sammamish River and
including all upstream tributaries contributing to the North Creek segment
of WASWIS SM74QQ.
Parameter Fecal Coliform
EPA Approval
Date
August 2, 2002
MS4 Permittee Phase I Permit: Snohomish County
Phase II Permit: Everett, Bothell, Mill Creek
Actions Required
Business Inspections: Each Permittee shall inspect commercial animal handling areas and
commercial composting facilities to ensure implementation of source control BMPs for bacteria.
Commercial animal handling areas are associated with Standard Industrial Code (SIC) 074 and
075 and include veterinary and pet care/boarding services, animal slaughtering, and support
activities for animal production. Facilities where the degradation and transformation of organic
solid waste takes place under controlled conditions designed to promote aerobic decomposition
are considered composting facilities (definition in accordance with Chapter 173-350 WAC). All
qualifying facilities shall be inspected by August 1, 2016. Permittees shall implement an ongoing
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 8
inspection program to re-inspect facilities with bacteria source control problems a minimum of
every three years.
Public Education and Outreach: Each Permittee shall conduct public education and outreach
activities to increase awareness of bacterial pollution problems and promote proper pet waste
management behavior.
Operations & Maintenance: Each Permittee shall install and maintain animal waste collection
and/or education stations at municipal parks and other Permittee owned and operated lands
reasonably expected to have substantial domestic animal (dog and horse) use and the potential
for pollution of stormwater.
IDDE: Permittees conducting IDDE-related field screening under S5.C.8 of the Phase I permit or
S5.C.3 of the Western Washington Phase II permit shall screen for bacteria sources in any
screened MS4 subbasins which discharge to surface waters in the TMDL area.
Targeted Source Identification & Elimination: By February 2, 2014, each Permittee shall
review the fecal coliform data collected per approved QAPPs under the 2007 Permit. The
purpose of this review is to identify a minimum of one high priority area (such as a tributary or a
stream segment) that will be the focus of source identification and elimination efforts during this
permit cycle. Each Permittee shall prepare written documentation of this review and the
identified high priority area; documentation shall be submitted with the Annual Report for 2014.
Permittees shall begin to implement source identification and elimination efforts in the MS4
subbasins discharging to the identified high priority area no later than August 1, 2014. Permittees
are encouraged to address potential bacteria pollution sources not associated with the MS4.
Stormwater quality sampling for bacteria sources is required as part of this focused source
identification and elimination effort. Permittees shall implement the schedules and activities
identified in S5.C.8 of the Phase I permit or S5.C.3 of the Western Washington Phase II permit
in response to any illicit discharges found. Each annual report’s TMDL summary shall include
qualitative and quantitative information about the source identification and elimination activities,
including procedures followed and sampling results, implemented in the selected high priority
area(s).
Surface Water Monitoring: Each Permittee shall review the fecal coliform data collected per
approved QAPPs under the 2007 Permit and select surface water monitoring location(s) as
appropriate for continued characterization and long term trends evaluation of fecal coliform.
Each Permittee shall submit a draft revised QAPP to Ecology for review and approval, no later
than February 2, 2015. If Ecology does not request changes within 60 days, the draft QAPP is
considered approved. At a minimum, the monitoring program shall:
• Begin by August 1, 2015.
• Collect 12 samples in at least one location per calendar year.
• Submit available data to the Environmental Information Management (EIM) database by
May 31 of each year.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 9
• Provide data summaries and narrative evaluation of the data in each annual report’s
TMDL summary.
• Be documented in a QAPP which follows Guidelines for Preparing Quality Assurance
Project Plans for Environmental Studies, July 2004, Ecology Publication No. 04-03-030.
Permittees shall follow Ecology-approved QAPPs unless changes are approved by Ecology.
Permittees subject to multiple TMDL monitoring requirements may conduct an integrated
monitoring program in accordance with an Ecology-approved QAPP. Snohomish County may
combine the high priority area source identification and elimination requirement with the surface
water monitoring requirement as documented in the County’s microbial water quality assessment
(MWQA), or similar, program per an Ecology-approved QAPP.
Name of TMDL Swamp Creek
EPA Approved
Document(s) for
TMDL
Swamp Creek Fecal Coliform Bacteria Total Maximum Daily Load: Water
Quality Improvement Report and Implementation Plan, June 2006, Ecology
Publication No. 06-10-021. http://www.ecy.wa.gov/biblio/0610021.html
Location of
Original 303(d)
Listings
WA-08-1060
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the Permittees municipal
stormwater permit and draining to the portion of the WASWIS segment
SM74QQ starting at the confluence with the Sammamish River and
including all upstream tributaries contributing to the Swamp Creek segment
of WASWIS GJ57UL.
Parameter Fecal Coliform
EPA Approval
Date
August 16, 2006
MS4 Permittee Phase I Permit: Snohomish County
Phase II Permit: Everett, Bothell, Lynnwood, Brier, Mountlake Terrace,
Kenmore
Actions Required
Business Inspections: Each Permittee shall inspect commercial animal handling areas and
commercial composting facilities to ensure implementation of source control BMPs for bacteria.
Commercial animal handling areas are associated with Standard Industrial Code (SIC) 074 and
075 and include veterinary and pet care/boarding services, animal slaughtering, and support
activities for animal production. Facilities where the degradation and transformation of organic
solid waste takes place under controlled conditions designed to promote aerobic decomposition
are considered composting facilities (definition in accordance with Chapter 173-350 WAC). All
qualifying facilities shall be inspected by August 1, 2016. Permittees shall implement an ongoing
inspection program to re-inspect facilities with bacteria source control problems a minimum of
every three years.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 10
Public Education and Outreach: Each Permittee shall conduct public education and outreach
activities to increase awareness of bacterial pollution problems and promote proper pet waste
management behavior.
Operations & Maintenance: Each Permittee shall install and maintain animal waste collection
and/or education stations at municipal parks and other Permittee owned and operated lands
reasonably expected to have substantial domestic animal (dog and horse) use and the potential
for pollution of stormwater.
IDDE: Permittees conducting IDDE-related field screening under S5.C.8 of the Phase I permit or
S5.C.3 of the Western Washington Phase II permit shall screen for bacteria sources in any
screened MS4 subbasins which discharge to surface waters in the TMDL area.
Targeted Source Identification & Elimination: By February 2, 2014, each Permittee shall
review the fecal coliform data collected per approved QAPPs under the 2007 Permit. The
purpose of this review is to identify a minimum of one high priority area (such as a tributary or a
stream segment) that will be the focus of source identification and elimination efforts during this
permit cycle. Each Permittee shall prepare written documentation of this review and the
identified high priority area; documentation shall be submitted with the Annual Report for 2014.
Permittees shall begin to implement source identification and elimination efforts in the MS4
subbasins discharging to the identified high priority area no later than August 1, 2014. Permittees
are encouraged to address potential bacteria pollution sources not associated with the MS4.
Stormwater quality sampling for bacteria sources is required as part of this focused source
identification and elimination effort. Permittees shall implement the schedules and activities
identified in S5.C.8 of the Phase I permit or S5.C.3 of the Western Washington Phase II permit
in response to any illicit discharges found. Each annual report’s TMDL summary shall include
qualitative and quantitative information about the source identification and elimination activities,
including procedures followed and sampling results, implemented in the selected high priority
area(s).
Surface Water Monitoring: Each Permittee shall review the fecal coliform data collected per
approved QAPPs under the 2007 Permit and select surface water monitoring location(s) as
appropriate for continued characterization and long term trends evaluation of fecal coliform.
Each Permittee shall submit a draft revised QAPP to Ecology for review and approval, no later
than February 2, 2015. If Ecology does not request changes within 60 days, the draft QAPP is
considered approved. At a minimum, the monitoring program shall:
• Begin by August 1, 2015.
• Collect 12 samples in at least one location per calendar year.
• Submit available data to the Environmental Information Management (EIM) database by
May 31 of each year.
• Provide data summaries and narrative evaluation of the data in each annual report’s
TMDL summary.
• Be documented in a QAPP which follows Guidelines for Preparing Quality Assurance
Project Plans for Environmental Studies, July 2004, Ecology Publication No. 04-03-030.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 11
Permittees shall follow Ecology-approved QAPPs unless changes are approved by Ecology.
Permittees subject to multiple TMDL monitoring requirements may conduct an integrated
monitoring program in accordance with an Ecology-approved QAPP. Snohomish County may
combine the high priority area source identification and elimination requirement with the surface
water monitoring requirement as documented in the County’s microbial water quality assessment
(MWQA), or similar, program per an Ecology-approved QAPP.
Name of TMDL Bear-Evans Watershed
Document(s) for
TMDL Bear-Evans Watershed Fecal Coliform Bacteria Total Maximum Daily
Load, Water Quality Improvement Report, June 2008, Ecology Publication
No. 08-10-026.
https://fortress.wa.gov/ecy/publications/summarypages/0810026.html
Bear-Evans Watershed Temperature, Dissolved Oxygen and Fecal Coliform
Bacteria Total Maximum Daily Load, Water Quality Implementation Plan,
March 2011, Ecology Publication No. 11-10-024.
http://www.ecy.wa.gov/biblio/1110024.html
Location of
Original 303(d)
Listings
Bear Creek (EW54VY, BA64JJ, WR69YU))
Cottage Lake Creek (NO74J5)
Unnamed Tributary to Bear Creek (EU47RU)
Evans Creek (MI67EG)
Area Where
TMDL
Requirements
Apply
Bear Creek and Evans Creek watersheds (includes Cottage Lake watershed)
Parameter Fecal Coliform
EPA Approval
Date
August 11, 2008
MS4 Permittee Phase I: King County
Phase II: No actions identified for Phase II Permittees
Actions Required
King County
• Install and maintain animal waste education and/or collection stations at municipal parks
and other Permittee owned and operated lands reasonably expected to have substantial
domestic animal (dog and horse) use and the potential for pollution of stormwater.
• Designate areas discharging via the MS4 to the TMDL area as high priority areas for
illicit discharge detection and elimination. Complete IDDE field screening for bacteria
sources in 50 percent of MS4 subbasins, including rural MS4 subbasins, by February 2,
2017, and implement the schedules and activities identified in S5.C.8 of the Phase I
permit for response to any illicit discharges found.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 12
Name of TMDL Cottage Lake
EPA Approved
Document(s) for
TMDL
Cottage Lake, Total Phosphorus, Total Maximum Daily Load Analysis,
Submittal Report, June 2004, Ecology Publication No. 03-10-085.
http://www.ecy.wa.gov/biblio/0310085.html
Cottage Lake, Total Phosphorus, Total Maximum Daily Load, Water
Quality Implementation Plan, March 2007, Ecology Publication No. 06-10-
066. http://www.ecy.wa.gov/biblio/0610066.html
Location of
Original 303(d)
Listings
WA-08-9070 & 49ITVC
Area Where
TMDL
Requirements
Apply
Cottage Lake and tributaries to Cottage Lake
Parameter Total Phosphorus
EPA Approval
Date
September 2004
MS4 Permittee Phase I: King County
Action Required
King County shall apply phosphorus control treatment requirements to new and redevelopment
projects, as applicable, throughout the Cottage Lake watershed, including all tributaries to
Cottage Lake. King County’s Department of Development and Environmental Services (DDES)
shall not rely on the quarter mile/15 percent distance downstream clause in King County’s
Surface Water Design Manual.
Name of TMDL Issaquah Creek Basin Water Cleanup Plan for Fecal Coliform Bacteria
Document(s) for
TMDL
Issaquah Creek Basin Water Cleanup Plan for Fecal Coliform Bacteria:
Total Maximum Daily Load Submittal Report, June 2004. Ecology
Publication No. 04-10-055.
http://www.ecy.wa.gov/pubs/0410055.pdf
Location of
Original 303(d)
Listings
Issaquah Creek, TF310B (WA-08-1110)
North Fork Issaquah Creek, CZ80NC (WA-08-1110)
Tibbetts Creek, MB51QQ, EA48LQ (WA-08-1115)
Area Where
TMDL
Requirements
Apply
These requirements apply to areas served by MS4s within the TMDL
coverage area.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 13
Parameter(s) Fecal Coliform Bacteria
EPA Approval
Date
October 1, 2004
MS4 Permittee: Phase I Permit: King County
Phase II Permit: City of Issaquah, WAR04-5518
Actions Required
City of Issaquah
• Designate areas discharging via the MS4 to Tributary 0170 and to the Lewis Lane Outfall
as the highest priority areas for illicit discharge detection and elimination routine field
screening efforts. Complete field screening for bacteria sources by December 31, 2014
and implement the schedules and activities identified in S5.C.3 of the Western
Washington Phase II permit for response to any illicit discharges found.
• Install and maintain pet waste education and collection stations at municipal parks and
other Permittee owned and operated lands adjacent to streams. Focus on locations where
people commonly walk their dogs.
King County
• Install and maintain animal waste education and/or collection stations at municipal parks
and other Permittee owned and operated lands reasonably expected to have substantial
domestic animal (dog and horse) use and the potential for pollution of stormwater.
• Designate areas discharging via MS4 to the TMDL area as high priority areas for illicit
discharge detection and elimination. Complete IDDE field screening for bacteria sources
in 50 percent of the MS4 subbasins, including rural MS4 subbasins, by August 1, 2018,
and implement the schedules and activities identified in S5.C.8 of the Phase I permit for
response to any illicit discharges found.
Name of TMDL Little Bear Creek Fecal Coliform Water Quality Improvement Project
Document(s) for
TMDL
Little Bear Creek Fecal Coliform Total Maximum Daily Load (Water
Cleanup Plan), May 2005, Ecology Publication No. 05-10-034.
http://www.ecy.wa.gov/biblio/0510034.html
Location of
Original 303(d)
Listings
Little Bear Creek, UT96KR (WA-08-1085).
Area Where
TMDL
Requirements
Apply
These requirements apply to areas served by MS4s within the TMDL
coverage area.
Parameter(s) Fecal coliform bacteria
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 14
EPA Approval
Date
July 1, 2005
MS4 Permittee: Phase I Permit: Snohomish County
Phase II Permit: City of Woodinville, WAR04-5545
Actions Required
City of Woodinville
• By December 31, 2014, complete field screening of Little Bear Creek to identify
potential illicit discharges or connections. Conduct bacteria sampling from any flowing
outfall, in accordance with protocols in Illicit Discharge Detection and Elimination: A
Guidance Manual for Program Development and Technical Assessments, Center for
Watershed Protection, October 2004, or another methodology of comparable or improved
effectiveness. Implement related schedules and activities identified in S5.C.3 of the
Western Washington Phase II permit for response to any illicit discharges found.
• Confirm that pet waste collection stations are installed and maintained in all public
lands/parks adjacent to Little Bear Creek.
Snohomish County
• Prioritize and conduct bacteria source identification and elimination in high priority MS4
subbasins that discharge to surface waters in the area where these TMDL requirements
apply. In order to prioritize bacteria source identification and elimination activities based
on surface water quality data, Snohomish County shall incorporate the Little Bear Creek
watershed into the County’s microbial water quality assessment (MWQA), or similar,
monitoring program in accordance with the schedule for QAPP development and
approval required for the Snohomish River Tributaries TMDL.
• Inspect commercial animal handling areas and commercial composting facilities to
ensure implementation of source control BMPs for bacteria. Commercial animal
handling areas are associated with Standard Industrial Code (SIC) 074 and 075 and
include veterinary and pet care/boarding services, animal slaughtering, and support
activities for animal production. Facilities where the degradation and transformation of
organic solid waste takes place under controlled conditions designed to promote aerobic
decomposition are considered composting facilities (definition in accordance with
Chapter 173-350 WAC). All qualifying facilities must be inspected by August 1, 2016.
Permittees shall implement an ongoing inspection program to re-inspect facilities with
bacteria source control problems every three years.
• Conduct public education and outreach activities to increase awareness of bacterial
pollution problems and promote proper pet waste management behavior.
• Install and maintain animal waste collection and/or education stations at municipal parks
and other Permittee owned and operated lands reasonably expected to have substantial
domestic animal (dog and horse) use and the potential for pollution of stormwater.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 15
Name of TMDL Puyallup Watershed Water Quality Improvement Project
Document(s) for
TMDL Puyallup River Watershed Fecal Coliform Total Maximum Daily Load – Water
Quality Improvement Report and Implementation Plan, June 2011, Ecology
Publication No. 11-10-040. http://www.ecy.wa.gov/biblio/1110040.html
Location of
Original 303(d)
Listings
Puyallup River 16712, 7498, White River 16711, 16708, 16709, Clear
Creek 7501, Swan Creek 7514, Boise Creek 16706
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the Permittees’ municipal
stormwater permit and discharging to water bodies listed within the specific
requirement in this TMDL section.
Parameter Fecal Coliform
EPA Approval
Date
September 2011
MS4 Permittee Phase I Permit: King County, Pierce County
Phase II Permit: Auburn, Edgewood, Enumclaw, Puyallup, Sumner
Actions Required
City of Auburn
• Beginning no later than October 1, 2013, conduct twice monthly wet weather sampling of
stormwater discharges to the White River at Auburn Riverside High School to determine if
specific discharges from Auburn’s MS4 exceed the water quality criteria for fecal coliform
bacteria.
o Data shall be collected for one wet season.
o Data shall be collected in accordance with an Ecology-approved QAPP.
o Data collected since EPA TMDL approval can be used to meet this requirement.
• For any of the outfalls monitored, above showing discharges that exceed water quality
criteria for primary contact recreation: designate those areas discharging via the MS4 of
concern as high priority areas for illicit discharge detection and elimination efforts and
implement the schedules and activities identified in S5.C.3 of the Western Washington Phase
II permit for response to any illicit discharges found beginning no later than August 1, 2014.
• Install and maintain pet waste education and collection stations at municipal parks and other
Permittee owned and operated lands adjacent to streams. Focus on locations where people
commonly walk their dogs.
City of Edgewood
• Designate areas discharging via the MS4 to Jovita Creek as the highest priority areas for
illicit discharge detection and elimination routine field screening and implement the
schedules and activities identified in S5.C.3 of the Western Washington Phase II permit.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 16
City of Enumclaw
• Designate areas discharging via the MS4 to Boise Creek from creek mile 1.7 to 1.0 as the
highest priority areas for illicit discharge detection and elimination routine field screening.
Implement the schedules and activities identified in S5.C.3 of the Western Washington Phase
II permit, and implement a pet waste education program in this area according to S5.C.1 of
the permit.
King County
• Designate areas discharging via the MS4 to Boise Creek as high priority areas for illicit
discharge detection and elimination. Complete IDDE field screening for bacteria sources in
100 percent of the MS4 subbasins, including rural subbasins, by February 2, 2016 and
implement the schedules and activities identified in S5.C.8 of the Phase I permit for response
to any illicit discharges found. Field screening must include activities for both the dry season
(May through September) and the wet season (October through April).
• Inventory commercial animal handling areas (associated with Standard Industrial Code 074
and 075) in areas discharging via the MS4 to Boise Creek and conduct inspections of these
areas as part of the Source Control program required in S5.C.7 of the Phase I permit. All
qualifying facilities must be inspected by August 1, 2016. The Permittee shall implement an
ongoing inspection program to re-inspect facilities or areas with bacteria source control
problems every three years.
• Designate areas discharging via the MS4 to Jovita Creek as high priority areas for illicit
discharge detection and elimination field screening, and implement the schedules and
activities identified in S5.C.8 of the Phase I permit.
Pierce County
• Designate areas discharging via MS4 to Swan Creek as high priority areas for illicit
discharge detection and elimination efforts. Complete field screening by December 31, 2014
and implement the schedules and activities identified in S5.C.8 of the Phase I permit.
• Designate areas discharging via MS4 to Salmon Creek as high priority areas for illicit
discharge detection and elimination field screening and implement the schedules and
activities identified in S5.C.8 of the Phase I permit.
• Designate areas discharging via the MS4 to Alderton Creek as high priority areas for illicit
discharge detection and elimination field screening and implement the schedules and
activities identified in S5.C.8 of the Phase I permit.
• Designate areas discharging via the MS4 to upper Deer Creek as high priority areas for illicit
discharge detection and elimination field screening and implement the schedules and
activities identified in S5.C.8 of the Phase I permit.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 17
City of Puyallup
• Designate areas discharging via the MS4 to Deer Creek as high priority areas for illicit
discharge detection and elimination field screening and implement the schedules and
activities identified in S5.C.3 of the Western Washington Phase II permit. Focus
investigation on field screening during dry weather (May through September).
City of Sumner
• Designate areas discharging via the MS4 to Salmon Creek as the highest priority areas for
illicit discharge detection and elimination routine field screening and implement the
schedules and activities identified in S5.C.3 of the Western Washington Phase II permit.
Name of TMDL Clarks Creek Fecal Coliform TMDL
Document(s) for
TMDL Clarks Creek Watershed Fecal Coliform Bacteria Total Maximum Daily
Load (Water Quality Improvement Report), May 2008, Ecology Publication
No. 07-10-110. http://www.ecy.wa.gov/biblio/0710110.html
Clarks Creek Watershed Fecal Coliform Bacteria Total Maximum Daily
Load (Water Quality Implementation Plan), December 2009, Ecology
Publication No. 09-10-081. http://www.ecy.wa.gov/biblio/0910081.html
Location of
Original 303(d)
Listings
Clarks Creek 7497, 7501, Meeker Creek 7508, 7507
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the Permittees’ municipal
stormwater permit and discharging to water bodies listed within the specific
requirement in this TMDL section.
Parameter Fecal Coliform
EPA Approval
Date
June 4, 2008
MS4 Permittee Phase II Permit: Puyallup
Actions Required
City of Puyallup
• Designate areas discharging via the MS4 to Meeker Creek as high priority areas for illicit
discharge detection and elimination field screening and implement the schedules and
activities identified in S5.C.3 of the Western Washington Phase II permit.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 18
Name of TMDL South Prairie Creek Water Quality Improvement Project
Document(s) for
TMDL South Prairie Creek Bacteria and Temperature Total Maximum Daily Load
(Water Cleanup Plan): Submittal Report, June 2003, Ecology Publication
No. 03-10-055. http://www.ecy.wa.gov/biblio/0310055.html
South Prairie Creek Bacteria and Temperature Total Maximum Daily Load
(Water Cleanup Plan): Detailed Implementation Plan, July 2006, Ecology
Publication No. 06-10-018. http://www.ecy.wa.gov/biblio/0610018.html
Location of
Original 303(d)
Listings
South Prairie Creek VC19MO (WA-10-1085), Wilkeson Creek NX07HW
(WA-10-1087)
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the Permittees’ municipal
stormwater permit and discharging to water bodies listed within the specific
requirement in this TMDL section.
Parameter Fecal Coliform
EPA Approval
Date
August 6, 2003
MS4 Permittee Phase I Permit: Pierce County
Phase II Permit: Buckley
Actions Required
Pierce County
• Designate areas discharging via the MS4 to Tributary 1 upstream of SR162 as high priority
areas for illicit discharge detection and elimination efforts. Complete field screening by
December 31, 2013 and implement the schedules and activities identified in S5.C.8 of the
Phase I permit for response to any illicit discharges found. Investigation must include
activities for both the dry season (May through September) and the wet season (October
through April).
• Designate areas discharging to Pierce County MS4 outfalls and conveyances upstream of
SR165 along Spiketon Road, Mundy Loss Road, and Spiketon Ditch Road as high priority
areas for illicit discharge detection and elimination efforts. Complete field screening by
December 31, 2013 and implement the schedules and activities identified in S5.C.8 of the
Phase I permit for response to any illicit discharges found. Investigation must include
activities for both the dry season (May through September) and the wet season (October
through April).
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 19
City of Buckley
• Designate areas discharging via the MS4 to Spiketon Creek as the highest priority areas for
illicit discharge detection and elimination routine field screening and implement the
schedules and activities identified in S5.C.3 of the Western Washington Phase II permit.
Name of TMDL Nisqually River Basin Water Quality Improvement Project
Document(s) for
TMDL Nisqually Watershed Bacteria and Dissolved Oxygen Total Maximum Daily
Load (Water Cleanup Plan): Submittal Report, June 2005, Ecology
Publication No. 05-10-040. http://www.ecy.wa.gov/biblio/0510040.html
Nisqually River Basin Fecal Coliform Bacteria and Dissolved Oxygen Total
Maximum Daily Load: Water Quality Implementation Plan (WQIP), June
2007, Ecology Publication No. 07-10-016.
http://www.ecy.wa.gov/biblio/0710016.html
Location of
Original 303(d)
Listings
Nisqually Reach 390KRD (WA-PS-0290), Nisqually River OE72JI (WA-
11-1010), McAllister Creek LD26OX (WA-11-2000), Ohop Creek
MW64EV (WA-11-1024), Red Salmon Creek NoID (WA-PS-0290)
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the Permittees’ municipal
stormwater permit and discharging to water bodies listed within the specific
requirement in this TMDL section.
Parameter Fecal Coliform, Dissolved Oxygen
EPA Approval
Date
August 5, 2005
MS4 Permittee Phase I Permit: Pierce County
Phase II Permit: Thurston County
Actions Required
Pierce County
• Designate areas discharging via the MS4 to Ohop Creek and Lynch Creek as high priority
areas for illicit discharge detection and elimination efforts. Complete field screening by
December 31, 2014 and implement the schedules and activities identified in S5.C.8 of the
Phase I permit for response to any illicit discharges found.
Thurston County
• Annually implement the following best management practices for reducing fecal coliform
bacteria in areas discharging to the Nisqually Reach via the MS4 in accordance with S5.C.1
and S5.C.5 of the Western Washington Phase II Permit:
a. Reach households in targeted watershed through mailings, door hangers
etc. to increase awareness of the sources of bacteria pollution.
b. Adequately maintain vegetation around stormwater facilities, ditches, and
ponds.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 20
Name of TMDL Henderson Inlet Watershed Fecal Coliform Bacteria Water Quality
Improvement Project
Document(s) for
TMDL Henderson Inlet Watershed Fecal Coliform Bacteria, Dissolved Oxygen,
pH, and Temperature Total Maximum Daily Load Study, March 2006,
Ecology Publication No. 06-03-012.
http://www.ecy.wa.gov/biblio/0603012.html
Henderson Inlet Watershed Fecal Coliform Bacteria, Dissolved Oxygen,
and pH Total Maximum Daily Load: Water Quality Improvement Report
Implementation Strategy, October 2006, Ecology Publication No. 06-10-
058. http://www.ecy.wa.gov/biblio/0610058.html
Henderson Inlet Watershed Fecal Coliform Bacteria Total Maximum Daily
Load: Water Quality Implementation Plan, July 2008, Ecology Publication
No. 08-10-040. http://www.ecy.wa.gov/biblio/0810040.html
Location of
Original 303(d)
Listings
Henderson Inlet 390KRD (WA-13-0010), Dobbs Creek UNK000 (WA-13-
1400), Sleepy Creek UNK000 (WA-13-1700), Woodard Creek MJ83ZH
(WA-13-1600), Woodland Creek JH31LN (WA-13-1500)
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the permittees municipal
stormwater permit and discharging to water bodies listed within the specific
requirement in this TMDL section.
Parameter Fecal Coliform, Dissolved Oxygen, pH, Temperature
EPA Approval
Date
January 8, 2007
MS4 Permittee Phase II Permit: Lacey, Olympia, Thurston County
Actions Required
Thurston County
1. Annually implement the following best management practices in areas discharging to the
Henderson Inlet via the MS4 in accordance with S5.C.4 of the Western Washington Phase II
Permit:
a. Require phosphorus control for new and redevelopment projects that discharge via the
MS4 to Woodard Creek and meet the project thresholds in Appendix 1, Minimum
Requirement #6: Runoff Treatment of the Western Washington Phase II permit.
2. Annually implement the following best management practices for reducing fecal coliform in
areas discharging to the Henderson Inlet via the MS4 in accordance with S5.C.3 of the
Western Washington Phase II Permit:
a. Designate areas discharging via the MS4 to Woodland Creek from river mile 1.6 to 0.2
and Jorgenson Creek upstream of Pleasant Glade Road as high priority areas for illicit
discharge detection and elimination field screening. Implement the schedules and
activities identified in S5.C.3 of the Western Washington Phase II permit. Investigation
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 21
shall include stormwater ponds and on-site septic systems as potential fecal coliform
sources, and sampling of wet-weather discharges (November through April).
3. Annually implement the following best management practices for reducing fecal coliform in
areas discharging to the Henderson Inlet via the MS4 in accordance with S5.C.1 of the
Western Washington Phase II Permit.
a. Continue supporting the Watershed Septic System Operations and Maintenance Program.
Develop a targeted educational plan delivering:
i. Technical assistance to landowners through at least one presentation or workshop
annually.
ii. Technical assistance to landowners through one publication or targeted letter
annually.
iii. A resource webpage on the city’s website.
b. Continue offering public education and outreach efforts for fecal coliform reduction such
as brochures, signage and pet waste stations to homeowner associations.
City of Lacey
1. Annually implement the following best management practices in areas discharging to the
Henderson Inlet via the MS4 in accordance with S5.C. 1 of the Western Washington Phase II
Permit:
a. Continue the Private Stormwater Facilities Maintenance Program, providing
commercial and residential stormwater facility/BMP owners educational resources for
facility function and maintenance requirements.
b. Offer bacteria pollution reduction brochures, signage and pet waste stations to
homeowners associations.
c. Maintain pet waste bag dispenser units in City parks.
d. Install educational signage at City facilities/property.
e. Develop a targeted educational plan for septic system owners that includes; goals, target
audiences, messages, format, distribution and evaluation methods by December 31,
2016. Permittees may meet requirement individually or through regional efforts.
2. Continue developing and implementing a fecal coliform bacteria wet weather sampling
program for the College Regional Stormwater Facility by December 31, 2013 in accordance
with the illicit discharge detection and elimination efforts and activities identified in S5.C.3
of the Western Washington Phase II permit.
a. Submit a plan to Ecology for approval by November 1, 2013. The sampling program
shall establish a regularly scheduled sampling schedule (at least two times per year, as
feasible and consistent with the city’s Wet Weather Discharge Plan) during the wet
season (November through April), specific sampling locations, sampling protocols,
parameters, analytical methods and timelines for implementation.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 22
b. If sampling results indicate potential illicit discharges, conduct an investigation in
accordance with S5.C.3 of the Western Washington Phase II permit.
c. Submit a summary of sampling and investigations with each annual report.
3. Develop and implement a coordinated plan with the City of Olympia to monitor and reduce
fecal coliform bacteria discharges from the Fones/Taylor wetland treatment facilities by
December 31, 2014 in accordance with S5.C.3 of the Western Washington Phase II permit.
a. Submit a program plan to Ecology that includes a timeline for implementation,
sampling frequencies and identifies, at the minimum, who will be responsible for
sampling, investigations and enforcement by December 31, 2013.
b. If sampling results indicate potential illicit discharges, conduct an investigation in
accordance with S5.C.3 of the Western Washington Phase II permit.
c. Submit a summary of the coordinated efforts with sampling, investigation and
enforcement actions taken with the annual reports.
4. Annually implement the following best management practices in areas discharging to the
Henderson Inlet via the MS4 in accordance with S5.C.5 of the Western Washington Phase II
Permit:
• Continue re-vegetation and nuisance vegetation management along Woodland Creek
and its tributaries.
City of Olympia
1. Annually implement the following BMPs in areas discharging to the Henderson Inlet via the
MS4 in accordance with S5.C.4 of the Western Washington Phase II permit:
• Require phosphorus control for new and redevelopment projects that discharge via
MS4 to Woodard Creek and meet the project thresholds in Appendix 1, Minimum
Requirement #6: Runoff Treatment of the Western Washington Phase II permit.
2. Develop and implement a coordinated plan with the City of Lacey to monitor and reduce
fecal coliform bacteria discharges from the Fones/Taylor wetland treatment facilities by
December 31, 2014 in accordance with S5.C.3 Illicit Discharge Detection and Elimination of
the Western Washington Phase II permit.
a. Submit a program plan to Ecology that includes a timeline for implementation,
sampling frequencies and identifies, at the minimum, who will be responsible for
sampling, investigations and enforcement by December 31, 2013.
b. If sampling results indicate potential illicit discharges, conduct an investigation in
accordance with S5.C.3 of the Western Washington Phase II permit.
c. Submit a summary of the coordinated efforts with sampling, investigation and
enforcement actions taken with each annual report.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 23
Name of TMDL Sinclair and Dyes Inlets Fecal Coliform Bacteria Total Maximum Daily
Load
Document(s) for
TMDL
Sinclair and Dyes Inlets Fecal Coliform Bacteria Total Maximum Daily
Load (TMDL) Water Quality Implementation Plan, In Draft, Ecology
Publication No. 11-10-051.
Fecal Coliform Model Verification Sampling Plan (Winter 2004), February
19, 2004. http://www.ecy.wa.gov/programs/wq/tmdl/sinclair-
dyes_inlets/w2004_fc_sap_final_ecy.pdf
Fecal Coliform Total Maximum Daily Load Study Plan for Sinclair and
Dyes Inlet, October 4, 2002.
http://www.ecy.wa.gov/programs/wq/tmdl/sinclair-
dyes_inlets/fc_tmdl_studyplan_final_draft_print.pdf
Location of
Original 303(d)
Listings
Dyes Inlet & Port Washington Narrows (WA-15-0020)
Gorst Creek (WA-15-4000)
Blackjack Creek (WA-15-4200)
Annapolis Creek (WA-15-4400)
Beaver Creek (WA-15-4900)
Clear Creek (WA-15-5000)
Barker Creek (WA-15-5100)
Sinclair Inlet (WA-15-0040)
Area Where
TMDL
Requirements
Apply
These requirements apply to areas served by MS4s listed below within the
TMDL coverage area.
Parameter(s) Fecal coliform bacteria
EPA Approval
Date
July 5, 2012
MS4 Permittee: Phase II Permit: City of Bainbridge Island, WAR04-5503; City of
Bremerton, WAR04-5507; City of Port Orchard, WAR04-5536; Kitsap
County, WAR04-5546
Actions Required
City of Bainbridge Island
• If a minimum of 10 monthly ambient water quality samples collected under a previous
monitoring program approved by Ecology in nearshore areas below Lynwood Center
between 2011 and 2013 indicate that this area does NOT meet water quality standards, then
by December 1, 2014, the City shall designate those areas discharging via MS4 either
directly or to creeks that discharge to shoreline areas along Rich Passage as the highest
priority areas for illicit discharge detection and elimination field screening. The City shall
implement the schedules and activities identified in S5.C.3 of the Western Washington Phase
II permit for response to any illicit discharges found.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 24
• By December 31, 2016, review and, if necessary, increase the frequency of inspection and
cleanout of catch basins (under S5.C.4 and 5 of the Western Washington Phase II permit) to
maintain catch basin sediment levels below 60 percent full. Focus on MS4 areas that drain to
nearshore areas along Rich Passage below Lynwood Center and the northern shoreline of
Fletcher Bay near DOH site 457.
• Use appropriate investigative tools to ensure that contaminated stormwater is not
contributing to the fecal coliform bacteria exceedances at DOH site 457, offshore Fletcher
Bay.
• Install and maintain pet waste education and collection stations at Permittee owned and
operated lands adjacent to stream and marine shorelines. Focus on locations where people
commonly walk their dogs.
City of Bremerton
• Designate areas discharging via MS4 to Phinney and Ostrich Bay Creeks, to the eastern
shoreline of Oyster Bay near DOH site 487, and to shorelines along Port Washington
Narrows as the highest priority areas for illicit discharge detection and elimination routine
field screening and, beginning no later than August 1, 2014 implement the schedules and
activities identified in S5.C.3 of the Western Washington Phase II permit for response to any
illicit discharges found.
• By December 31, 2016, review and, if necessary, increase the frequency of inspection and
cleanout of catch basins (under S5.C.4 and 5 of the Western Washington Phase II permit) to
maintain catch basin sediment levels below 60 percent full. Focus on MS4 areas that drain to
Phinney and Ostrich Bay Creeks, to the eastern shoreline of Oyster Bay near DOH site 487
and to shorelines along Port Washington Narrows.
• Install and maintain pet waste education and collection stations at municipal parks and other
Permittee owned and operated lands adjacent to stream and marine shorelines. Focus on
locations where people commonly walk their dogs.
City of Port Orchard
• Designate areas discharging via MS4 to Blackjack, Annapolis, and Karcher Creeks and to
shorelines along Sinclair Inlet as the highest priority areas for illicit discharge detection and
elimination routine field screening and, beginning August 1, 2014, implement the associated
schedules and activities identified in S5.C.3 of the Western Washington Phase II permit for
response to any illicit discharges found.
• By December 31, 2016, review and, if necessary, increase the frequency of inspection and
cleanout of catch basins (under S5.C.4 and 5 of the Western Washington Phase II permit to
maintain catch basin sediment levels below 60% full. Focus on MS4 areas that drain to
Blackjack, Annapolis, and Karcher Creeks and to shorelines along Sinclair Inlet.
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 25
• Install and maintain pet waste education and collection stations at municipal parks and other
Permittee owned and operated lands adjacent to stream and marine shorelines. Focus on
locations where people commonly walk their dogs.
Kitsap County
• Designate areas discharging via MS4 to Barker, Clear, Strawberry, Ostrich Bay, and Phinney
creeks and shorelines at the head of Dyes Inlet as the highest priority areas for illicit
discharge detection and elimination routine field screening (including agricultural land use
inventories in rural areas) and, beginning no later than August 1, 2014, implement the
associated schedules and activities identified in S5.C.3 of the Western Washington Phase II
permit for response to any illicit discharges found. onduct illicit discharge detection and
elimination efforts in MS4 areas that discharge to Beaver, Pahrmann, Sacco, and upper
Blackjack creeks and to the western shoreline of Chico Bay near DOH site 471 as resources
allow.
• By December 31, 2016, review and, if necessary, increase the frequency of inspection and
cleanout of catch basins (in accordance with S5.C.4 and 5 of the Western Washington Phase
II permit) to maintain catch basin sediment levels below 60% full. Focus on areas within the
Sinclair and Dyes Inlet watershed with closed conveyance systems and catch basins.
• Install and maintain pet waste education and collection stations at municipal parks and other
Permittee owned and operated lands adjacent to stream and marine shorelines. Focus on
locations where people commonly walk their dogs.
Name of TMDL Grays Harbor/Chehalis Watershed Fecal Coliform Bacteria Total
Maximum Daily Load
Document(s) for
TMDL Grays Harbor/Chehalis Watershed Fecal Coliform Bacteria Total
Maximum Daily Load Submittal Report, December 2001, Ecology
Publication No. 01-10-025. http://www.ecy.wa.gov/biblio/0110025.html
Quality Assurance Project Plan: Grays Harbor Fecal Coliform Bacteria
Monitoring to Characterize Water Quality in Urban Stormwater Drains,
October 2010, Ecology Publication No. 10-10-066.
http://www.ecy.wa.gov/biblio/1010066.html
Location of
Original 303(d)
Listings
Outer Grays Harbor 390KRD (WA-22-0020), Inner Grays Harbor 390KRD
(WA-22-030), Inner Grays Harbor DS29ZH (WA-22-0030), Chehalis River
PB33WC (WA-22-4040)
Area Where
TMDL
Requirements
Apply
Requirements apply in all areas regulated under the Permittees’ municipal
stormwater permit and discharging to water bodies listed within the specific
requirement in this TMDL section.
Parameter Fecal Coliform
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 26
EPA Approval
Date
December 2002
MS4 Permittee Phase II Permit: Aberdeen
Actions Required
City of Aberdeen
1. Implement the schedules and activities identified in S5.C.1 of the Western Washington
Phase II Permit. No later than February 28, 2015, develop a Public Education and
Outreach and Involvement plan. The plan shall target the reduction of fecal coliform
pollution by increasing public awareness, effecting behavior changes and shall include:
goals, target audiences, messages, format, distribution, and evaluation methods.
a. The plan shall include at least the following elements and be fully implemented
prior to the expiration date of the permit:
i. Target the residents of the three high priority water bodies identified under
the 2007-2012 permit.
ii. Reach households in targeted watersheds through mailings, door hangers
or similar outreach tools.
iii. Reach 4-6th grade students.
b. Design and implement a program which notifies residents, in a timely manner,
when bacteria pollution that poses a public health concern (such as a wastewater
overflow) reaches the MS4.
c. Conduct two public education surveys gauging resident’s knowledge of the
sources of bacteria and preventing bacteria pollution. One survey should measure
resident’s knowledge of bacteria pollution before outreach and the other should
measure knowledge and likelihood of action after outreach.
d. Design and implement a stream team program where two citizen stream teams are
formed to participate in stewardship activities.
e. Install and maintain pet waste bag dispenser units and explanatory signs in public
areas with dog usage.
f. By December 31, 2014, develop an inventory of sources that have potential for
bacteria runoff such as manure-composting facilities, stables, kennels.
i. Develop a targeted manure management educational plan for such facility
owners delivering at least one presentation or letter annually and
developing a resource webpage on the city’s website.
2. Designate areas discharging to the MS4 urban drains identified in the TMDL as the
highest priority areas for illicit discharge detection and elimination routine field screening
efforts and implement the schedules and activities identified in S5.C.3 of the Western
Western Washington Phase II Municipal Stormwater Permit
Appendix 2 - Total Maximum Daily Load (TMDL) Requirements
Western Washington Phase II Municipal Stormwater Permit – August 1, 2013,
Modified January 16, 2015
Page 27
Washington Phase II permit. Field screening and source tracing methodology (see
S5.C.3.c) must be consistent with the Quality Assurance Project Plan: Grays Harbor
Fecal Coliform Bacteria Monitoring to Characterize Water Quality in Urban Stormwater
Drains, October 2010.
a. Implement a regulatory mechanism to control pet waste.
b. Designate areas discharging via MS4 to the following discharge points: 501-
ABDN, 510-MST, and 514-MST as high priority areas for illicit discharge
detection and elimination efforts.
i. Complete field screening by December 31, 2014 and implement the schedules
and priority area for illicit discharge detection and elimination field screening
identified in S5.C.3 of the Western Washington Phase II permit. Investigation
must include activities for both the dry season (May through October) and the
wet season (November through April).
ii. Beginning no later than October 31, 2014, conduct twice monthly wet weather
sampling of the discharge points 501-ABDN, 510-MST, and 514-MST to
determine if specific discharges from Aberdeen’s MS4 exceed the water
quality criteria for fecal coliform bacteria.
• Data shall be collected for two wet season.
• Data shall be collected in accordance with an Ecology-approved QAPP.
• Samples must be analyzed using an Ecology accredited lab.
• If sampling results indicate potential illicit discharges, conduct an
investigation in accordance with S5.C.3 Illicit Discharge Detection and
Elimination of the Western Washington Phase II permit.
• Data shall be submitted to Ecology in an approved format with the annual
reports.
Western Washington Municipal Stormwater Permit
August 1, 2013 Modified January 16, 2015 Appendix 3 – Annual Report for Cities, Towns and
Counties Page 1
Appendix 3 - Annual Report Questions for Cities, Towns
and Counties
Permittees are required to submit the following information in an online annual report
form, or an alternative format provided by Ecology if requested, pursuant to Special
Condition S9.A.
1. Attach updated annual Stormwater Management Program Plan (SWMP Plan). (S5.A.2)
2. Attach a copy of any annexations, incorporations or boundary changes resulting in an
increase or decrease in the Permittee’s geographic area of permit coverage during the
reporting period per S9.D.5.
3. Implemented an ongoing program to gather, track, and maintain information per S5.A.3,
including costs or estimated costs of implementing the SWMP.
4. Coordinated among departments within the jurisdiction to eliminate barriers to permit
compliance. (S5.A.5.b)
4b. Attach a written description of internal coordination mechanisms. (Required to be
submitted no later than March 31, 2015, S5.A.5.b)
5. Attach description of public education and outreach efforts conducted per S5.C.1.a.i and
ii.
6. Created stewardship opportunities (or partnered with others) to encourage resident
participation in activities such as those described in S5.C.1.b.
7. Used results of measuring the understanding and adoption of targeted behaviors among at
least one audience in at least one subject area to direct education and outreach resources
and evaluate changes in adoption of targeted behaviors. (Required no later than February
2, 2016, S5.C.1.b)
7b. Attach description of how this requirement was met.
8. Describe in Comments field the opportunities created for the public to participate in the
decision making processes involving the development, implementation and updates of the
Permittee’s SWMP. (S5.C.2.a)
9. Posted the updated SWMP Plan and latest annual report on your website no later than
May 31. (S5.C.2.b)
Western Washington Municipal Stormwater Permit
August 1, 2013 Modified January 16, 2015 Appendix 3 – Annual Report for Cities, Towns and
Counties Page 2
9b. List the website address in Comments field.
10. Maintained a map of the MS4 including the requirements listed in S5.C.3.a.i.-vi.
11. Implemented a compliance strategy, including informal compliance actions as well as
enforcement provisions of the regulatory mechanism described in S5.C.3.b. (S5.C.3.b.v)
12. Updated, if necessary, the regulatory mechanism to effectively prohibit illicit discharges
into the MS4 per S5.C.3.b.vi. (Required no later than February 2, 2018)
12b. If Yes, cite the code reference in Comments field
13. Implemented procedures for conducting illicit discharge investigations in accordance
with S5.C.3.c.i.
13b. Cite methodology in Comments field
14. Percentage of MS4 coverage area screened in reporting year per S5.C.3.c.i. (Required to
screen 40% of MS4 no later than December 31, 2017 (except no later than June 30, 2018
for the City of Aberdeen) and 12% on average each year thereafter. (S5.C.3)
15. List the hotline telephone number for public reporting of spills and other illicit discharges
in the Comments field. (S5.C.3.c.ii)
15b. Number of hotline calls received.
16. Implemented an ongoing illicit discharge training program for all municipal field staff per
S5.C.3.c.iii.
17. Informed public employees, businesses, and the general public of hazards associated with
illicit discharges and improper disposal of waste.
17b. Describe actions in Comments field. (S5.C.3.c.iv)
18. Implemented an ongoing program to characterize, trace, and eliminate illicit discharges
into the MS4 per S5.C.3.d.
19. Number of illicit discharges, including illicit connections, eliminated during the reporting
year. (S5.C.3.d.iv)
Western Washington Municipal Stormwater Permit
August 1, 2013 Modified January 16, 2015 Appendix 3 – Annual Report for Cities, Towns and
Counties Page 3
20. Attach a summary of actions taken to characterize, trace and eliminate each illicit
discharge found by or reported to the permittee. For each illicit discharge, include a
description of actions according to required timeline per S5.C.3.d.iv
21. Municipal illicit discharge detection staff are trained to conduct illicit discharge detection
and elimination activities as described in S5.C.3.e.
22. Implemented an ordinance or other enforceable mechanism to address runoff from new
development, redevelopment and construction sites per the requirements of S5.C.4.a.
23. Revised ordinance or other enforceable mechanism to effectively address runoff from
new development, redevelopment and construction sites per the requirements of
S5.C.4.a.i-iii. (Required no later than December 31, 2016, except no later than June 30,
2017 for Permittees in Lewis and Cowlitz counties, and no later than June 30, 2018 for
the City of Aberdeen)
23b. Cite code reference in Comments field.
24. Number of exceptions granted to the minimum requirements in Appendix 1. (S5.C.4.a.i.,
and Section 6 of Appendix 1)
25. Number of variances granted to the minimum requirements in Appendix 1. (S5.C.4.a.i.,
and Section 6 of Appendix 1)
26. Reviewed Stormwater Site Plans for all proposed development activities that meet the
thresholds adopted pursuant to S5.C.4.a.i. (S5.C.4.b.i)
26b. Number of site plans reviewed during the reporting period.
27. Inspected, prior to clearing and construction, permitted development sites that have a
high potential for sediment transport as determined through plan review based on
definitions and requirements in Appendix 7 Determining Construction Site Sediment
Damage Potential, or alternatively, inspected all construction sites meeting the minimum
thresholds adopted pursuant to S5.C.4.a.i. (S5.C.4.b.ii)
27b. Number of construction sites inspected per S5.C.4.b.ii.
28. Inspected permitted development sites during construction to verify proper installation
and maintenance of required erosion and sediment controls. (S5.C.4.b.iii)
28b. Number of construction sites inspected per S5.C.4.b.iii.
Western Washington Municipal Stormwater Permit
August 1, 2013 Modified January 16, 2015 Appendix 3 – Annual Report for Cities, Towns and
Counties Page 4
29. Number of enforcement actions taken during the reporting period (based on construction
phase inspections at new development and redevelopment projects). (S5.C.4.b.ii, iii and
v)
30. Inspected all permitted development sites that meet the thresholds in S5.C.4.a.i upon
completion of construction and prior to final approval or occupancy to ensure proper
installation of permanent stormwater facilities. (S5.C.4.b.iv)
31. Achieved at least 80% of scheduled construction-related inspections. (S5.C.4.b.ii-iv)
32. Verified a maintenance plan is completed and responsibility for maintenance is assigned
for projects. (S5.C.4.b.iv)
33. Implemented provisions to verify adequate long-term operation and maintenance (O&M)
of stormwater treatment and flow control BMPs/facilities that are permitted and
constructed pursuant to S5.C.4. a and b. (S5.C.4.c)
34. Updated provisions to verify long-term operation and maintenance of stormwater
treatment and flow control BMPs/facilities that are permitted pursuant to S5.C.4.a and b.
(Required no later than December 31, 2016, except no later than June 30, 2017 for
Permittees in Lewis and Cowlitz counties, and no later than June 30 2018 for the City of
Aberdeen, S5.C.4.c.i and ii
35. Annually inspected stormwater treatment and flow control BMPs/facilities per
S5.C.4.c.iii.
35b. If using reduced inspection frequency for the first time during this permit cycle, attach
documentation per S5.C.4.c.iii
36. Inspected new residential stormwater treatment and flow control BMPs/facilities and
catch basins every 6 months per S5.C.4.c.iv to identify maintenance needs and enforce
compliance with maintenance standards.
37. Achieved at least 80% of scheduled inspections to verify adequate long-term O&M.
(S5.C4.c.v)
38. Verified that maintenance was performed per the schedule in S5.C.4.c.vi when an
inspection identified an exceedance of the maintenance standard.
38b. Attach documentation of any maintenance delays. (S5.C.4.c.vi)
39. Provided copies of the Notice of Intent for Construction Activity and Notice of Intent for
Industrial Activity to representatives of proposed new development and redevelopment.
(S5.C.4.e)
Western Washington Municipal Stormwater Permit
August 1, 2013 Modified January 16, 2015 Appendix 3 – Annual Report for Cities, Towns and
Counties Page 5
40. All staff responsible for implementing the program to control stormwater runoff from
new development, redevelopment, and construction sites, including permitting, plan
review, construction site inspections, and enforcement are trained to conduct these
activities. (S5.C.4.f)
41. Reviewed, revised and made effective the low impact development-related enforceable
documents per S5.C.4.f.i. (Required by December 31, 2016, except by June 30, 2017 for
Permittees in Lewis and Cowlitz counties, and by June 30, 2018 for the City of
Aberdeen)
41b. Attach a summary of the LID review and revision process that includes the requirements
listed in S5.C.4.f.ii. (Required with annual report due no later than March 31, 2017,
except no later than March 31, 2018 for Permittees in Lewis and Cowlitz counties, and
with the Fifth Year annual report for the City of Aberdeen)
42. Where applicable, participated and cooperated with the watershed-scale stormwater
planning process led by a Phase I county. (S5.C.4.g)
43. Updated and implemented maintenance standards as protective, or more protective, of
facility function as those specified in Chapter 4 of Volume V of the Stormwater
Management Manual for Western Washington (as amended in 2014). (Required no later
than December 31, 2016, except no later than June 30, 2017 for Permittees in Lewis and
Cowlitz counties, and no later than June 30, 2018 for the City of Aberdeen, S5.C.5.a)
44. Applied a maintenance standard that is not specified in the Stormwater Management
Manual for Western Washington.
44b. Please note in the Comments field what kinds of facilities are covered by this alternative
maintenance standard. (S5.C.5.a)
45. Performed timely maintenance per S5.C.5.a.ii.
46. Annually inspected all municipally owned or operated permanent stormwater treatment
and flow control BMPs/facilities. (S5.C.5.b)
46b. Number of known municipally owned or operated stormwater treatment and flow control
BMPs/facilities. (S5.C.5.b)
46c. Number of facilities inspected during the reporting period. (S5.C.5.b)
46d. Number of facilities for which maintenance was performed during the reporting period.
(S5.C.5.b)
47. If using reduced inspection frequency for the first time during this permit cycle, attach
documentation per S5.C.5.b.
Western Washington Municipal Stormwater Permit
August 1, 2013 Modified January 16, 2015 Appendix 3 – Annual Report for Cities, Towns and
Counties Page 6
48. Conducted spot checks and inspections (if necessary) of potentially damaged stormwater
facilities after major storms as per S5.C.5.c.
49. Inspected all municipally owned or operated catch basins and inlets as per S5.C.5.d, or
used an alternative approach. (Required once no later than August 1, 2017 and every two
years thereafter, except once no later than June 30, 2018 and every two years thereafter
for the City of Aberdeen)
49b. Number of known catch basins.
49c. Number of catch basins inspected during the reporting period.
49d. Number of catch basins cleaned during the reporting period.
50. Attach documentation of alternative catch basin cleaning approach, if used. (S5.C.5.d.i
or ii)
51. Implemented practices, policies and procedures to reduce stormwater impacts associated
with runoff from all lands owned or maintained by the Permittee, and road maintenance
activities under the functional control of the Permittee. (S5.C.5.f)
52. Implemented an ongoing training program for Permittee employees whose primary
construction, operations or maintenance job functions may impact stormwater quality.
(S5.C.5.g.)
53. Implemented a Stormwater Pollution Prevention Plan for all heavy equipment
maintenance or storage yards, and material storage facilities owned or operated by the
Permittee in areas subject to this Permit that are not required to have coverage under an
NPDES permit that covers stormwater discharges associated with the activity. (S5.C.5.h)
54. Complied with the Total Maximum Daily Load (TMDL)-specific requirements identified
in Appendix 2. (S7.A)
55. For TMDLs listed in Appendix 2: Attach a summary of relevant SWMP and Appendix 2
activities to address the applicable TMDL parameter(s). (S7.A)
56. Attach a description of any stormwater monitoring or stormwater-related studies as
described in S8.A.
57. Participated in cost-sharing for the regional stormwater monitoring program (RSMP) for
status and trends monitoring. (S8.B.1)
57b. If choosing to conduct monitoring in accordance with S8.B.2., attach a data report in
accordance with the approved QAPP. (Required to begin monitoring no later than
October 31, 2014)
Western Washington Municipal Stormwater Permit
August 1, 2013 Modified January 16, 2015 Appendix 3 – Annual Report for Cities, Towns and
Counties Page 7
58. Participated in cost-sharing for the regional stormwater monitoring program (RSMP) for
effectiveness studies. (S8.D.1) (Required to begin no later than August 15, 2014)
58b. If choosing to conduct discharge monitoring, attach an annual stormwater monitoring
report in accordance with S8.C.2 and Appendix 9. (Required to submit reports beginning
March 31, 2016)
59. Contributed to the RSMP for source identification and diagnostic monitoring information
repository in accordance with S8.D. (Required to begin no later than August 15, 2014)
60. Notified Ecology in accordance with G3 of any discharge into or from the Permittees
MS4 which could constitute a threat to human health, welfare or the environment. (G3)
61. Number of G3 notifications provided to Ecology.
62. Took appropriate action to correct or minimize the threat to human health, welfare,
and/or the environment per G3.A.
63. Notified Ecology within 30 days of becoming aware that a discharge from the Permittee’s
MS4 caused or contributed to a known or likely violation of water quality standards in
the receiving water. (S4.F.1)
64. If requested, submitted an Adaptive Management Response report in accordance with
S4.F.3.a.
65. Attach a summary of the status of implementation of any actions taken pursuant to
S4.F.3 and the status of any monitoring, assessment, or evaluation efforts conducted
during the reporting period. (S4.F.3.d)
66. Notified Ecology of the failure to comply with the permit terms and conditions within 30
days of becoming aware of the non-compliance. (G20)
67. Number of non-compliance notifications (G20) provided in reporting year.
67b. List permit conditions described in non-compliance notification(s) in Comments field.
Western Washington Phase II Municipal Stormwater Permit
APPENDIX 4 – Annual Report Questions for
Secondary Permittees
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 4: Secondary Permittee Annual Report
Questions Page 1
VI. Status Report Covering Calendar Year _____
Secondary Permittees are required to submit annual reports online or in a format provided by
Ecology, pursuant to Special Condition S9.A
1. YES
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 4: Secondary Permittee Annual Report
Questions Page 2
S6.D.3 Illicit Discharge Detection and Elimination
6. YES
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 4: Secondary Permittee Annual Report
Questions Page 3
12. YES
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 4: Secondary Permittee Annual Report
Questions Page 4
S6.D.4 Construction Site Stormwater Control
16. YES
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 4: Secondary Permittee Annual Report
Questions Page 5
S6.D.5 Post-Construction Stormwater Management for New Development and
Redevelopment
21. YES
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 4: Secondary Permittee Annual Report
Questions Page 6
Comments:
27. YES
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 4: Secondary Permittee Annual Report
Questions Page 7
may constitute a threat to human health, welfare, or the environment.
(G3)
Comments:
_____________________________________________________________________________
34. YES
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 5- Notice of Intent for Coverage Page 1 of 5
APPENDIX 5: Notice of Intent (NOI) for Coverage
under a National Pollutant Discharge
Elimination System (NPDES)
Municipal Stormwater General Permit
Introduction
This form must be used by all entities seeking initial coverage under one or more of the following
municipal separate storm sewer permits:
Phase I Municipal Stormwater Permit – “National Pollutant Discharge Elimination System
and State Waste Discharge General Permit for Discharges from Large and Medium Municipal
Separate Storm Sewer Systems”
Western Washington Phase II Municipal Stormwater Permit – “National Pollutant
Discharge Elimination System and State Waste Discharge General Permit for Discharges from
Small Municipal Separate Storm Sewers in Western Washington”
Eastern Washington Phase II Municipal Stormwater Permit – “National Pollutant
Discharge Elimination System and State Waste Discharge General Permit for Discharges from
Small Municipal Separate Storm Sewers in Eastern Washington”
The Department of Ecology (Ecology) will use the information provided to determine if coverage
under one or more of the above municipal stormwater general permits is required and/or appropriate.
Please answer all questions accurately and completely. If a question does not apply, answer NA to that
question. See instructions at the back of the form for more information.
Operators of municipal separate storm sewer systems (MS4s) seeking permit coverage must complete
this application and return it to Ecology. You may print this form and complete it by hand, or
download the form from Ecology’s Web site and fill it out electronically. The form is available at:
www.ecy.wa.gov/biblio/ecy070207.html.
A certified signature is needed to complete the application. Please reference supporting documents in
the text and attach as necessary.
Mail completed NOI to:
Department of Ecology
Water Quality Program
Municipal Stormwater Permits
P.O. Box 47696
Olympia, WA 98504-7696
Ecology will send each applicant an acknowledgment of receipt. If you have questions about this
application, please contact the appropriate Ecology employee listed at
www.ecy.wa.gov/programs/wq/stormwater/municipal/municontacts.html , or call Ecology’s Water
Quality Program at 360-407-6600.
.
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 5 - Notice of Intent for Coverage Page 2 of 5
Part 1 - Owner/Operator Information
A. Applicant Information
Name of city, county, or special district:
Mailing Address:
PO Box (Optional) :
City: State: Zip:
B. Responsible Official or Representative
Name:
Title:
Phone:
Email:
Mailing Address:
PO Box (Optional) :
City: State: Zip:
C. Billing Address, if different
Name:
Mailing Address:
PO Box (Optional) :
City: State: Zip:
D. Primary Contact Person
Name:
Title:
Phone No. Business: Ext. :
Email:
Fax No. (Optional):
Mailing Address:
PO Box (Optional):
City: State: Zip:
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 5 - Notice of Intent for Coverage Page 3 of 5
E. Ownership Status
(check appropriate box)
City or Town
County
Federal
Federally-recognized Indian Tribe
Special Purpose District:(secondary permittee)
Diking/drainage district Port
Flood control district University
Public school district Park district
State agency (give name)
Other (please describe)
Part 2 – Permits under which the applicant is requesting coverage (see instructions)
Phase I Municipal Stormwater Permit
Western Washington Phase II Municipal Stormwater Permit
Eastern Washington Phase II Municipal Stormwater Permit
If you own or operate MS4s that are located in areas covered by more than one permit, please list the
locations of all of the MS4s for which you are requesting permit coverage.
Part 3 – Population served by the MS4
Estimated resident population (public entities that are not cities, towns, or counties also include
commuter populations) served by the MS4 within the geographic area(s) covered by the
permits:
Part 4 – Map(s)
A. Is part of the MS4 located within Indian Country (within a reservation or on land held in
trust for a tribe)? For the Puyallup reservation only, check “yes” if MS4 is located on trust
lands and “no” if any part of the MS4 is located on fee lands. Yes No
B. For special purpose districts only, attach a map or maps delineating the geographic area
served by the MS4. Attach map(s) to this form
Not applicable
Part 5 – Co-Permittee information
Complete this part of the NOI only if you are applying as a Co-Permittee with another entity to
meet the requirements of the permit. Permittees that apply as Co-Permittees are responsible for
meeting permit conditions related to their discharge(s).
If you are applying with another entity or entities as Co-Permittee(s) please include, as an
attachment to this NOI, a summary of the permit obligations that will be carried out jointly among
Co-Permittees. The summary must identify the other Co-Permittee(s) and must be signed by the
other Co-Permittee(s).
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 5 - Notice of Intent for Coverage Page 4 of 5
Attach a summary of joint permit obligations
Summary is signed by all Co-Permittees
Not Applicable
Part 6 - Relying on another entity to satisfy permit requirement(s)
Complete this part of the NOI only if you are relying on another entity to satisfy all of the
requirements of the permit. Permittees that rely on another entity to satisfy all of their permit
obligations remain responsible for permit compliance if the other entity fails to implement the
permit conditions. Permittees may rely on another entity provided:
1. The other entity agrees to take on responsibility for implementation of the permit
requirement(s),
AND
2. The other entity implements the permit requirements.
If you are relying on another entity or entities to satisfy all of the permit obligations, please include
as an attachment to this NOI a summary of the permit obligations that will be carried out by
another entity. The summary must identify the other entity or entities and must be signed by the
other entity or entities.
Attach summary of permit obligations carried out by another entity
Summary is signed by all other entities
Not Applicable
Part 7 – Public Notice
A public notice must be published at least once each week for two consecutive weeks in a single
newspaper of general circulation in the county or city in which the district or entity is located. See
the NOI instructions for the public notice language requirements. Permit coverage will not be
granted sooner than 31 days after the date of the second public notice.
Submit the NOI and public notice to Ecology before the date of the first public notice. A copy of
the NOI and public notice may be faxed to (360) 407-6426.
Name of the newspaper that will publish the public notices:
Provide the exact dates (mm/dd/yy) that the first and second public notices will appear in the
newspaper:
Date of the first notice / /
Date of second notice / /
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 5 - Notice of Intent for Coverage Page 5 of 5
Part 8 - Certification
I certify under penalty of law that this document and all attachments were prepared under my
direction or supervision in accordance with a system designed to assure that qualified personnel
properly gather and evaluate the information submitted. The information submitted is, to the best of
my knowledge and belief, true, accurate, and complete. I am aware that there are significant
penalties for submitting false information, including the possibility of fine and imprisonment for
knowing violations.
Print or type name of responsible official or representative Title
/ /
Signature of responsible official or representative Date
If you need this document in a format for the visually impaired, call the Water Quality Program at
360-407-6600. Persons with hearing loss can call 711 for Washington Relay Service. Persons with a
speech disability can call 877-833-6341.
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013 Appendix 5 - Notice of Intent for Coverage Page 1 of 6
INSTRUCTIONS
These instructions will help you prepare an application, referred to as a Notice of Intent (NOI), for
coverage under a National Pollutant Discharge Elimination System (NPDES) General Permit and State
Waste Discharge Permit for stormwater discharges associated with MS4s in Washington State.
Questions?
If you have questions, please contact the Ecology employee who manages the permit in the county or
counties in which your facility or district is located available at
http://www.ecy.wa.gov/programs/wq/stormwater/municipal/municontacts.html or, call Ecology’s
Water Quality Program office at 360-407-6600, and the receptionist will direct you to a staff member
who can assist you.
Who must apply?
Federal and state law requires all operators of regulated MS4s to apply for and obtain coverage under
this permit or to be permitted under a separate individual permit, unless it qualifies for a waiver or
exemption in accordance with conditions described below (see Who does not need to apply?).
1. A regulated MS4 is a municipal separate storm sewer system that:
• Is located within, or partially within, the unincorporated areas of Clark, King, Pierce or
Snohomish counties; or
• Is located within, or partially within, the cites of Seattle or Tacoma; or
• Is located within the other areas defined in the permits. See list of cities and counties in Part
2 of the line-by-line instructions or Ecology’s maps of permit coverage
www.ecy.wa.gov/programs/wq/stormwater/phase_2/maps.html for more information on
these locations; or
• Is designated by Ecology
AND
• Discharges stormwater from the MS4 to a water of the United States; and
• Is not eligible for an exemption or a waiver.
2. All owners or operators of MS4s that meet the criteria listed above must obtain coverage under
this permit. Owners or operators of MS4s may also include, but are not limited to: public flood
control districts, public diking, and drainage districts, public schools including universities, and
correctional facilities that own or operate an MS4 serving non-agricultural land uses.
3. If Ecology determines the MS4 is a significant source of pollution to surface waters of the state,
Ecology may require any other operators of small MS4s to obtain permit coverage. Ecology
will notify the affected MS4 that permit coverage is required by issuing an administrative order
(see RCW 90.48).
Who does not need to apply?
If either of the following conditions applies, state and federal laws do not require a MS4 to obtain
permit coverage:
If the portions of the MS4 located within the census defined urban area(s) that discharge to surface
waters serve a total population of less than 1000 people** and all the conditions below apply, then
the MS4 qualifies for a waiver and need not apply:
• The MS4 is not contributing substantially to the pollutant loadings of a physically
interconnected MS4 that is regulated by the NPDES stormwater program.
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013 Appendix 5 - Notice of Intent for Coverage Page 2 of 6
• The discharge of pollutants from the MS4 has not been identified as a cause of impairment
of any water body to which the MS4 discharges.
• In areas where an EPA approved Total Maximum Daily Load (TMDL), or water quality
improvement plan for impaired waters, has been completed, stormwater controls on the
MS4 have not been identified as being necessary.
**In determining the total population served, cities and counties include resident populations;
other public entities include resident and commuter populations as follows:
• For publicly operated school complexes including universities and colleges, the total
population served includes the sum of the average annual student enrollment plus staff.
• For flood control, diking, and drainage districts, the total population served includes
residential population and any non-residents regularly employed in the areas served by
the MS4.
Exempt MS4s are those owned or operated by:
• A federal entity, including any department, agency or instrumentality of the executive,
legislative, and judicial branch of the Federal government of the United States; or
• Federally recognized Indian Tribes located within Indian Country, including all trust or
restricted lands within the 1873 Survey Area of the Puyallup Tribe of Indians.
Federal and tribal MS4s are not covered under this permit but may need coverage under a
permit issued by the USEPA.
When to apply
Submit the NOI to the Department of Ecology on or before the date of the first public notice required
in part 7 of this NOI. Ecology must have the permit application during the public comment period
required by this NOI in order to provide the public access to the applications as required by state law
(WAC 173-226-130(5)).
Ecology cannot grant permit coverage until 31 days after the date of the second public notice.
Upon receipt of a complete NOI, Ecology will notify the applicant by mail of confirmation of coverage
under the permit. An NOI is deemed complete only after the 30-day public comment period and all
other requested information has been supplied. Permit coverage will begin on the date specified in
Ecology’s letter of confirmation.
Where to apply
Mail the signed NOI to: Washington Department of Ecology
Water Quality Program
Municipal Stormwater Permits
P.O. Box 47696
Olympia, WA 98504-7696
Fees
There is no application fee. Ecology will bill the applicant(s) for permit fees after permit coverage
is issued in accordance with Chapter 173-224 WAC. Call the Permit Fee Unit of Ecology at
360-407-6425 for questions relating to permit fees.
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013 Appendix 5 - Notice of Intent for Coverage Page 3 of 6
Line-by-line Instructions
Part 1 – Owner/Operator information
A. Applicant information - Fill out the name and mailing address of the city, county, or public
entity that will receive coverage under the permit.
B. Responsible Official or Representative – Fill out the name, address and contact information for
the principal executive officer or ranking elected official responsible for signing the
application. See Part 8 for more information.
C. Billing information - If a separate department or office handles billing, enter the appropriate
contact information. There is an annual permit fee associated with this permit.
D. Primary Contact person - Enter the name, title, address, phone number, and email for the
person who will be in charge of developing the stormwater management program and meeting
the stormwater permit requirements.
E. Ownership status - Check the appropriate box indicating the ownership status (e.g., city,
county, or special district type).
Part 2 – Permit(s) under which the applicant is requesting coverage
Check the box that corresponds to the permit(s) under which you are applying for coverage. The
geographic locations covered by each permit break down as follows:
• Phase I – covers entities within, or partially within the unincorporated areas of Clark, King, Pierce,
or Snohomish counties; or the cities of Seattle or Tacoma.
• Phase II Western Washington – covers entities in the census-defined urban areas of western
Washington, and associated urban growth areas, some cities with populations over 10,000 or areas
otherwise designated by Ecology.
• Phase II Eastern Washington – covers entities in the census-defined urban areas of eastern
Washington, and associated urban growth areas, and some cities with populations over 10,000 or
areas otherwise designated by Ecology.
Note: Applicants may submit a single NOI to request coverage of all of the MS4s that they own or
operate. For example, a single NOI may be submitted to cover the main campus and any satellite
campuses of a university that may require permit coverage. Applicants requesting coverage for
multiple sites/locations must list the locations for each site/location for which coverage is being
requested. When more than one permit is checked, Ecology will consult with the applicant to
determine whether to assign all the sites to separate permits or to one permit that will provide
coverage.
Part 3 – Population served by the MS4
Provide an estimate of the population served by the MS4 within the geographic area(s) covered by the
permits. Cities, towns, and counties include only the resident population. For special purpose districts
and other public entities that are not cities, towns, or counties, the estimate must include both resident
and commuter populations. For example, a university may have a resident population of students who
live on campus and a commuter population of students and employees who commute to campus. (See
above for information on determining the commuter population in Who does not need to apply?)
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013 Appendix 5 - Notice of Intent for Coverage Page 4 of 6
Part 4 – Map requirements
A. Is part of the MS4 located within Indian Country (within a reservation or on land held in trust
for a tribe)? For the Puyallup reservation only, check “yes” if MS4 is located on trust lands and
“no” if any part of the MS4 is located on fee lands. The portion of the MS4 that is located on
tribal lands will not be covered under these permits.
B. For special purpose districts only, attach a map or maps delineating the geographic area served
by the MS4.
Part 5 – Co-Permittee information
Complete this part of the NOI only if you are applying with another entity as Co-Permittees to meet the
requirements of this permit. Permittees that apply as Co-Permittees are responsible for meeting permit
conditions related to their discharge(s).
If you are applying as a Co-Permittee with another entity or entities, please include as an attachment to
this NOI a summary of the permit obligations that will be carried out jointly among Co-Permittees.
The summary must identify the other Co-Permittee(s) and must be signed by the other Co-Permittee(s).
Part 6 - Relying on another entity to satisfy permit requirement(s)
Complete this part of the NOI only if you are relying on another entity to satisfy all of the requirements
of the permit. Permittees may rely on another entity provided the entity satisfies all of the requirements
it agrees to undertake (see 40 CFR 122.35(a)).
That other entity must agree to take responsibility and implement the permit requirement(s).
Permittees that rely on another entity to satisfy all of their permit obligations remain responsible for
permit compliance with those obligations if the other entity fails to implement the permit conditions.
If you are relying on another entity or entities to satisfy all of the permit obligations, please include as
an attachment to this NOI a summary of the permit obligations that will be carried out by another
entity. The summary must identify the other entity or entities and must be signed by the other entity or
entities.
Part 7 – Public notice
You must publish a public notice in a newspaper of general circulation in the county or city in which
the district or entity is located. The following sample public notice contains the required public notice
elements.
Sample Public Notice
(Name and address of municipality, district or other public entity) is seeking coverage under (select
one of the following):
Phase I Permit – “National Pollutant Discharge Elimination System and State Waste
Discharge General Permit for Discharges from Large and Medium Municipal Separate Storm
Sewer Systems”
Western Washington Phase II Permit – “National Pollutant Discharge Elimination System
and State Waste Discharge General Permit for Discharges from Small Municipal Separate
Storm Sewers in western Washington”
Eastern Washington Phase II Permit – “National Pollutant Discharge Elimination System
and State Waste Discharge General Permit for Discharges from Small Municipal Separate
Storm Sewers in eastern Washington”
The proposed permit will authorize stormwater discharges from the municipal separate storm sewer
system located in (city, town, or county). The permit requires (Name of municipality, district, or other
public entity) to develop and implement a stormwater management program that:
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013 Appendix 5 - Notice of Intent for Coverage Page 5 of 6
1. Reduces the discharge of pollutants to the maximum extent practicable.
2. Protects water quality.
3. Satisfies appropriate requirements of the Clean Water Act.
Any person desiring to present views to the Department of Ecology concerning this application may
notify Ecology in writing within 30 days from the last date of publication of this notice.
Submit comments to:
Washington Department of Ecology
Water Quality Program
Municipal Stormwater Permits
P.O. Box 47696
Olympia, WA 98504-7696
Fax: 360-407-6426
Part 8 - Certification
An authorized person, such as a principal executive officer or ranking elected official, must sign the
certification statement.
OR
A duly authorized representative of the executive officer (or ranking elected official) may sign the
certification as long as:
1. The signator y receives written authorization from the executive officer or ranking elected
official. This document must be submitted to Ecology at the same time as the completed NOI.
2. The authorization specifies an individual or position that has responsibility for the overall
development and implementation of the stormwater management program.
If you need this document in a format for the visually impaired, call the Water Quality Program at
360-407-6600. Persons with hearing loss can call 711 for Washington Relay Service. Persons with a
speech disability can call 877-833-6341.
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 6 – Street Waste Disposal Page 1 of 2
APPENDIX 6 – Street Waste Disposal
Street Waste Liquids
General Procedures:
Street waste collection should emphasize retention of solids in preference to
liquids. Street waste solids are the principal objective in street waste collection and are
substantially easier to store and treat than liquids.
Street waste liquids require treatment before their discharge. Street waste liquids
usually contain high amounts of suspended and total solids and adsorbed metals.
Treatment requirements depend on the discharge location.
Discharges to sanitary sewer and storm sewer systems must be approved by the
entity responsible for operation and maintenance of the system. Ecology will not
generally require waste discharge permits for discharge of stormwater decant to
sanitary sewers or to stormwater treatment BMPs constructed and maintained in
accordance with Ecology’s Stormwater Management Manual for Western Washington.
The following order of preference, for disposal of catch basin decant liquid
and water removed from stormwater treatment facilities, is required.
1. Discharge of catch basin decant liquids to a municipal sanitary sewer connected
to a Public Owned Treatment Works (POTW) is the preferred disposal option.
Discharge to a municipal sanitary sewer requires the approval of the sewer authority.
Approvals for discharge to a POTW will likely contain pretreatment, quantity and
location conditions to protect the POTW.
2. Discharge of catch basin decant liquids may be allowed into a Basic or
Enhanced Stormwater Treatment BMP, if option 1 is not available.
Decant liquid collected from cleaning catch basins and stormwater treatment wet vaults
may be discharged back into the storm sewer system under the following conditions:
• The preferred disposal option of discharge to sanitary sewer is not reasonably
available, and
• The discharge is to a Basic or Enhanced Stormwater Treatment Facility. If
pretreatment does not remove visible sheen from oils, the treatment facility must be
able to prevent the discharge of oils causing a visible sheen, and
• The discharge is as near to the treatment facility as is practical, to minimize
contamination or recontamination of the collection system, and
• The storm sewer system owner/operator has granted approval and has determined
that the stormwater treatment facility will accommodate the increased loading.
Pretreatment conditions to protect the stormwater treatment BMP may be issued as
part of the approval process. Following local pretreatment conditions is a
requirement of this permit.
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 6 – Street Waste Disposal Page
2 of 2
• Flocculants for the pretreatment of catch basin decant liquids must be non-toxic
under the circumstances of use and must be approved in advance by the Department
of Ecology.
The reasonable availability of sanitary sewer discharge will be determined by the
Permittee, by evaluating such factors as distance, time of travel, load restrictions, and
capacity of the stormwater treatment facility.
3. Water removed from stormwater ponds, vaults and oversized catch basins may
be returned to the storm sewer system. Stormwater ponds, vaults and oversized catch
basins contain substantial amounts of liquid, which hampers the collection of solids and
pose problems if the removed waste must be hauled away from the site. Water
removed from these facilities may be discharged back into the pond, vault or catch
basin provided:
• Clear water removed from a stormwater treatment structure may be discharged
directly to a down gradient cell of a treatment pond or into the storm sewer system.
• Turbid water may be discharged back into the structure it was removed from if
− the removed water has been stored in a clean container (eductor truck, Baker
tank or other appropriate container used specifically for handling stormwater or
clean water); and
− there will be no discharge from the treatment structure for at least 24 hours.
• The discharge must be approved by the storm sewer system owner/operator.
Street Waste Solids
Soils generated from maintenance of the MS4 may be reclaimed, recycled or reused
when allowed by local codes and ordinances. Soils that are identified as contaminated
pursuant to Chapter 173-350 WAC shall be disposed at a qualified solid waste disposal
facility.
Western Washington Phase II Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 7- Determining Sediment Damage
Potential Page 1 of 3
APPENDIX 7 – Determining Construction Site
Sediment Damage Potential
The following rating system allows objective evaluation of a particular development site’s
potential to discharge sediment. Permittees may use the rating system below or develop
alternative process designed to identify site-specific features which indicate that the site must be
inspected prior to clearing and construction. Any alternative evaluation process must be
documented and provide for equivalent environmental review.
Step one is to determine if there is a sediment/erosion sensitive feature downstream of the
development site. If there is such a site downstream complete step two, assessment of hydraulic
nearness. If there is a sediment/erosion sensitive feature and it is hydraulically near the site then
go to step three to determine the construction site sediment transport potential.
STEP 1 – Sediment/Erosion Sensitive Feature Identification
Sediment/erosion sensitive features are areas subject to significant degradation due to the effect
of sediment deposition or erosion. Special protection must be provided to protect them.
Sediment/erosion sensitive features include but are not limited to:
i. Salmonid bearing fresh water streams and their tributaries or freshwater streams
that would be Salmonid bearing if not for anthropogenic barriers;
ii. Lakes;
iii. Category I, II, and III wetlands;
iv. Marine near-shore habitat;
v. Sites containing contaminated soils where erosion could cause dispersal of
contaminants; and
vi. Steep slopes (25% or greater) associated with one of the above features.
Identify any sediment/erosion sensitive features, and proceed to step two. If there are none the
assessment is complete.
STEP 2 – Hydraulic Nearness Assessment
Sites are hydraulically near a feature if the pollutant load and peak quantity of runoff from the
site will not be naturally attenuated before entering the feature. The conditions that render a site
hydraulically near to a feature include, but are not limited to, the following:
i. The feature or a buffer to protect the feature is within 200 feet downstream of the
site.
ii. Runoff from the site is tight-lined to the feature or flows to the feature through a
channel or ditch.
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 7- Determining Sediment Damage
Potential Page 2 of 3
A site is not hydraulically near a feature if one of the following takes place to provide attenuation
before runoff from the site enters the feature:
i. Sheet flow through a vegetated area with dense ground cover
ii. Flow through a wetland not included as a sensitive feature
iii. Flow through a significant shallow or adverse slope, not in a conveyance channel,
between the site and the sensitive feature.
Identify any of the sediment/erosion sensitive features from step one that are hydraulically near
the site, and proceed to step three. If none of the sediment/erosion sensitive features are
hydraulically near the site, the assessment is complete.
STEP 3 – Construction Site Sediment Transport Potential
Using the worksheet below, determine the total points for each development site. Assign points
based on the most critical condition that affects 10% or more of the site.
If soil testing has been performed on site, the results should be used to determine the
predominant soil type on the site. Otherwise, soil information should be obtained from the
county soil survey to determine Hydrologic Soil Group (Table of Engineering Index Properties
for step 1.D) and Erosion Potential (Table of Water Features for step 1.E)
When using the county soil survey, the dominant soil type may be in question, particularly when
the site falls on a boundary between two soil types or when one of two soil types may be present
on a site. In this case, the soil type resulting in the most points on the rating system will be
assumed unless site soil tests indicate that another soil type dominates the site.
Use the point score from Step 3 to determine whether the development site has a high potential
for sediment transport off of the site.
Total Score Transport Rating
<100 Low
≥100 High
A high transport rating indicates a higher risk that the site will generate sediment contaminated
runoff.
Western Washington Phase II Municipal Stormwater Permit
August 1, 2013, Modified January 16, 2015 Appendix 7- Determining Sediment Damage
Potential Page 3 of 3
Construction Site Sediment Transport Potential Worksheet
A. Existing slope of site (average, weighted by aerial extent): Points
2% or less ........................................................................................ 0
>2-5% .............................................................................................. 5
>5-10% .......................................................................................... 15
>10-15% ........................................................................................ 30
>15% ............................................................................................. 50
B. Site Area to be cleared and/or graded:
<5,000 sq. ft. ..................................................................................... 0
5,000 sq. ft. – 1 acre ....................................................................... 30
>1 acres ......................................................................................... 50
C. Quantity of cut and/or fill on site:
<500 cubic yards ............................................................................. 0
500 – 5,000 cubic yards .................................................................. 5
>5,000 – 10,000 cubic yards ......................................................... 10
>10,000 – 20,000 cubic yards ....................................................... 25
>20,000 cubic yards ...................................................................... 40
D. Runoff potential of predominant soils (Natural Resources Conservation Service):
Hydrologic soil group A ................................................................. 0
Hydrologic soil group B ................................................................ 10
Hydrologic soil group C ................................................................ 20
Hydrologic soil group D ............................................................... 40
E. Erosion Potential of predominant soils (Unified Classification System):
GW, GP, SW, SP soils .................................................................... 0
Dual classifications (GW-GM, GP-GM, GW-GC,
GP-GC, SW-SM, SW-SC, SP-SM, SP-SC) .......................... 10
GM, GC, SM, SC soils .................................................................. 20
ML, CL, MH, CH soils ................................................................. 40
F. Surface or Groundwater entering site identified and intercepted 1:
Yes ................................................................................................... 0
No ................................................................................................. 25
G. Depth of cut or height of fill >10 feet:
Yes ................................................................................................. 25
No ................................................................................................... 0
H. Clearing and grading will occur in the wet season (October 1 – May 1):
Yes ................................................................................................. 50
No ................................................................................................... 0
TOTAL POINTS ............................................................................................. ________
1 If no surface or groundwater enters site, give 0 points.
Western Washington Phase II Municipal Stormwater Permit
Appendix 8 - Annual Report for New Permittees
August 1, 2013, Modified January 16, 2015
Page 1
APPENDIX 8 – Annual Report Questions for New
Permittees
New Permittees that are Cities, Towns or Counties are required to submit the
following information in an online annual report form, or an alternative format
provided by Ecology if requested, pursuant to Special Condition S9.A.
1. Attach updated annual Stormwater Management Program Plan
(SWMP Plan). (S5.A.2)
2. Attach a notification of any annexations, incorporations or
boundary changes resulting in an increase or decrease in the
Permittee’s geographic area of permit coverage during the
reporting period per S9.D.5.
3. Implemented an ongoing program to gather, track, and maintain
information per S5.A.3, including costs or estimated costs of
developing and implementing the SWMP. (Required to begin no
later than August 1, 2015)
4. Coordinated among departments within the jurisdiction to
eliminate barriers to permit compliance? (S5.A.5.b)
4b. Attach a written description of internal coordination
mechanisms. (Required to be submitted no later than March 31,
2015, S5.A.5.b)
5. Attach description of public education and outreach efforts
conducted per S5.C.1.a. i-ii. (Required to begin no later than
August 1, 2015)
6. Provided stewardship opportunities (or partnered with others) to
encourage resident participation. (Required to begin no later than
August 1, 2015, S5.C.1.b)
7. Used results of measuring the understanding and adoption of
targeted behaviors among at least one audience in at least one
subject area to direct education and outreach resources and
evaluate changes in adoption of targeted behaviors. (Required no
later than August 1, 2017, S5.C.1.c)
Western Washington Phase II Municipal Stormwater Permit
Appendix 8 - Annual Report for New Permittees
August 1, 2013, Modified January 16, 2015
Page 2
7b. Attach description of how this requirement was met.
8. Describe in Comments field the opportunities created for the
public to participate in the decision making processes involving
the development, implementation and updates of the Permittee’s
SWMP. (Required to begin no later than August 1, 2014,
S5.C.2.a)
9. Posted the updated SWMP Plan and latest annual report on your
website no later than May 31. (Required to begin posting no later
than May 31, 2015, S5.C.2.b)
9b. List the website address in Comments field.
10. Developed a map of the MS4 that includes the requirements listed
in S5.C.3.a.i.-vi. (Required no later than August 1, 2017)
11. Mapped all connections to the MS4 authorized or allowed by the
Permittee. (Required to begin no later than August 1, 2013,
S5.C.3.a.v)
12. Adopted and implemented an ordinance or other regulatory
mechanism to effectively prohibit illicit discharges per the
requirements in S5.C.3.b.i.-iv. (Required no later than February
2, 2016)
12b. Cite reference for ordinance or other regulatory mechanism to
meet this requirement in Comments field.
13. Developed and implemented a compliance strategy, including
informal compliance actions as well as enforcement provisions of
the ordinance (S5.C.3.b.v) (Required no later than February 2,
2016)
14. Developed and implemented procedures for conducting illicit
discharge investigations in accordance with S5.C.3.c.i.
(Required no later than February 2, 2018)
14b. Cite methodology used in the Comments sections.
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Appendix 8 - Annual Report for New Permittees
August 1, 2013, Modified January 16, 2015
Page 3
15. Screened on average 12% of MS4 within coverage area each year
in accordance with S5.C.3.c.i. (Required to screen 12% no later
than December 31, 2017; 20% on average each year thereafter,
S5.C.3.c.i)
16. Publicized a hotline telephone number for public reporting of
spills and other illicit discharges. (Required to begin no later than
August 1, 2015, S5.C.3.c.ii)
16b. Number of hotline calls received during the reporting period.
16c. Provide telephone number in the Comments field.
17. Developed and implemented an ongoing illicit discharge training
program for all municipal field staff per S5.C.3.c.iii. (Required to
begin no later than February 2, 2016)
18. Informed public employees, businesses, and the general public of
hazards associated with illicit discharges and improper disposal
of waste? (Required to begin no later than February 2, 2017,
S5.C.3.c.iv)
18b. Describe activities in Comments field.
19. Developed and implemented a program to characterize, trace, and
eliminate illicit discharges into the MS4 found by or reported to
the Permittee. (Required to begin no later than February 2, 2018,
S5.C.3.d.i)
20. Number of illicit discharges, including illicit connections,
eliminated during the reporting year. (Required no later than
February 2, 2018, S5.C.3.d.iii and iv)
21. Attach a summary of actions taken to characterize, trace and
eliminate each illicit discharge found by or reported to the
permittee. For each illicit discharge, include a description of
actions according to required timeline per S5.C.3.d.iv. (Required
no later than February 2, 2018)
22. Trained municipal illicit discharge detection staff to conduct
illicit discharge detection and elimination activities referenced in
S5.C.3.e. (Required no later than February 2, 2016)
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Appendix 8 - Annual Report for New Permittees
August 1, 2013, Modified January 16, 2015
Page 4
23. Developed and implemented a program to reduce pollutants in
stormwater runoff to the MS4 from new public or private
development, redevelopment and construction site activities.
(Required no later than December 31, 2017, S5.C.4)
24. Adopted and implemented an ordinance or other enforceable
mechanism to address runoff from new development,
redevelopment and construction sites per the requirements of
S5.C.4.a. (Required no later than December 31,2017)
24b. Cite the jurisdiction code reference used to meet this requirement
in Comments field.
25. Number of exceptions granted to the minimum requirements in
Appendix 1. (Required no later than December 31, 2017,
S5.C.4.a.i and Section 6 of Appendix 1)
26. Number of variances granted to the minimum requirements in
Appendix 1. (Required no later than December 31, 2017,
S5.C.4.a.i and Section 6 of Appendix 1)
27. Reviewed Stormwater Site Plans for all proposed development
activities that meet the thresholds adopted pursuant to S5.C.4.a.i.
(Required no later than December 31, 2017, S5.C.4.b.i)
27b. Number of site plans reviewed during the reporting period.
28. Inspected, prior to clearing and construction, all permitted
development sites that have a high potential for sediment
transport as determined through plan review based on definitions
and requirements in Appendix 7 Determining Construction Site
Sediment Damage Potential, or alternatively, inspected all
construction sites meeting the minimum thresholds adopted
pursuant to S5.C.4.a.i. (Required no later than December 31,
2017, S5.C.4.b.ii)
28b. Number of construction sites inspected per S5.C.4.b.ii.
29. Inspected all permitted development sites during construction to
verify proper installation and maintenance of required erosion
and sediment controls. (Required no later than December 31,
2017, S5.C.4.b.iii)
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Appendix 8 - Annual Report for New Permittees
August 1, 2013, Modified January 16, 2015
Page 5
29b. Number of construction sites inspected per S5.C.4.b.iii.
30. Number of enforcement actions taken during the reporting period
based on construction phase inspections at new development and
redevelopment projects. (Required no later than December 31,
2017, S5.C.4.b.ii, iii and v)
31. Inspected all permitted development sites that meet the thresholds
in S5.C.4.a.i upon completion of construction and prior to final
approval or occupancy to ensure proper installation of stormwater
facilities. (Required no later than December 31, 2017, S5.C.4.b.iv
and v)
32. Verified a maintenance plan is completed and responsibility for
maintenance is assigned for projects. (Required no later than
December 31, 2017, S5.C.4.b.iv)
33 Achieved at least 80% of scheduled construction-related
inspections. (Required no later than December 31, 2017,
S5.C.4.b.ii-iv)
34. Developed and implemented a program to verify adequate long-
term operation and maintenance (O&M) of stormwater flow
control and treatment BMPs/facilities that are permitted and
constructed pursuant to S5.C.4(b). (Required no later than
December 31, 2017, S5.C.4.c)
35. Adopted and implemented an ordinance or other enforceable
mechanism that clearly identifies the party responsible for
maintenance, requires inspection and establishes enforcement
procedures. (Required no later than December 31, 2017,
S5.C.5.c.i)
36. Established maintenance standards as described in S5.C.4.c.ii.
(Required no later than December 31, 2017)
37. Annually inspected stormwater treatment and flow control
BMPs/facilities per S5.C.4.c.iii.(Required no later than December
31, 2017)
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Appendix 8 - Annual Report for New Permittees
August 1, 2013, Modified January 16, 2015
Page 6
37b. If using reduced inspection frequency for the first time during this
permit term, attach documentation as per S5.C.4.c.iii. (Required
if applicable no later than December 31, 2017)
38. Inspected new stormwater treatment and flow control
BMPs/facilities and catch basins for new developments every 6
months until 90% of the lots are constructed (or until construction
has stopped and the site is fully stabilized) to identify
maintenance needs and enforce compliance with maintenance
standards as needed? (Required no later than December 31, 2017,
S5.C4.c.ii)
39. Achieved at least 80% of scheduled inspections to verify
adequate long-term O&M. (Required no later than December 31,
2017, S5.C4.c.v)
40. Verified that maintenance was performed per the schedule in
S5.C.4.c.vi when an inspection identified an exceedance of the
maintenance standard. (Required no later than December 31,
2017)
40b. Attach documentation of any maintenance delays.(S5.C.4.c.vi)
41. Provided copies of the Notice of Intent for Construction Activity
and Notice of Intent for Industrial Activity to representatives of
proposed new development and redevelopment. (Required no
later than August 1, 2013, S5.C.4.d)
42. Ensured that all staff responsible for implementing the program to
control stormwater runoff from new development,
redevelopment, and construction sites are trained to conduct these
activities, as per S5.C.4.e. (Required to begin no later than
December 31, 2017)
43. Reviewed, revised and made effective the low impact
development-related codes, rules, standards and other enforceable
documents as per S5.C.4.f.i. (Required no later than December
31, 2017)
43b. Attach a summary of the LID review and revision process that
includes the requirements listed in S5.C.4.f.ii. (Required to be
submitted no later than March 31, 2018)
Western Washington Phase II Municipal Stormwater Permit
Appendix 8 - Annual Report for New Permittees
August 1, 2013, Modified January 16, 2015
Page 7
44. Where applicable, participated and cooperated with the
watershed-scale stormwater planning process led by a Phase I
county. (S5.C.4.g)
45. Developed and implemented maintenance standards as protective,
or more protective, of facility function as those specified in
Chapter 4 of Volume V of the Stormwater Management Manual
for Western Washington. (Required no later than December 31,
2017, S5.C.5.a)
46. Applied a maintenance standard that is not specified in the
Stormwater Management Manual for Western Washington.
(Required to report, if applicable, no later than December 31,
2017, S5.C.5.a)
46b. Please note in the Comments field what kinds of facilities are
covered by this alternative maintenance standard.
47. Performed timely maintenance as per S5.C.5.a.ii. (Required no
later than December 31, 2017)
47b. Attach documentation of any maintenance delays. (Required, if
applicable, no later than December 31, 2017, S5.C.5.a.ii)
48. Annually inspected all municipally owned or operated permanent
stormwater treatment and flow control BMPs/facilities. (Required
no later than December 31, 2017, S5.C.5.b)
48a. Number of known municipally owned or operated stormwater
treatment and flow control BMPs/facilities.
48b. Number of facilities inspected during the reporting period.
48c. Number of facilities for which maintenance was performed
during the reporting period.
49. If used a reduced inspection frequency, attach documentation as
per S5.C.5.b (Required, if applicable, no later than December 31,
2017)
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Appendix 8 - Annual Report for New Permittees
August 1, 2013, Modified January 16, 2015
Page 8
50. Conducted spot checks and inspections (if necessary) of
potentially damaged stormwater facilities after major storms.
(Required no later than December 31, 2017, S5.C.5.c)
51. Inspected all municipally owned or operated all catch basins and
inlets owned or operated by the Permittee at least once during the
permit term, or used an alternative approach. (Required no later
than February 2, 2018, S5.C.5.d)
51b. Number of known catch basins.
51c. Number of catch basins inspected.
51d. Number of catch basins cleaned.
52. Attach documentation of alternative catch basin cleaning
approach, if used. (Required, if applicable, no later than
February 2, 2018, S5.C.5.d.i- iii)
53. Developed and implemented practices, policies and procedures to
reduce stormwater impacts associated with runoff from all lands
owned or maintained by the Permittee, and road maintenance
activities under the functional control of the Permittee. (Required
no later than December 31, 2017, S5.C.5.f)
54. Developed and implemented an ongoing training program for
Permittee employees whose primary construction, operations or
maintenance job functions may impact stormwater quality.
(Required no later than December 31, 2017, S5.C.5.g.)
55. Developed and implemented a Stormwater Pollution Prevention
Plan (SWPPP) for all heavy equipment maintenance or storage
yards, and material storage facilities owned or operated by the
Permittee in areas subject to this Permit as described in S5.C.6.h.
(Required no later than December 31, 2017, S5.C.6.h)
56. Complied with the Total Maximum Daily Load (TMDL) specific
requirements identified in Appendix 2, if applicable. (S7.A)
57. If applicable, for TMDLs listed in Appendix 2 attach a summary
of relevant SWMP and Appendix 2 activities to address the
applicable TMDL parameter. (S7.A)
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Appendix 8 - Annual Report for New Permittees
August 1, 2013, Modified January 16, 2015
Page 9
58. Attach a description of any stormwater monitoring or
stormwater-related studies as described in S8.A.
59. Notified Ecology in accordance with G3 of any discharge into or
from the Permittee’s MS4 which could constitute a threat to
human health, welfare or the environment. (G3)
60. Number of G3 notifications provided to Ecology.
61. Took appropriate action to correct or minimize the threat to
human health, welfare, and/or the environment per G3.A.
62. Notified Ecology within 30 days of becoming aware that a
discharge from the Permittee’s MS4 caused or contributed to a
known or likely violation of water quality standards in the
receiving water. (S4.F.1)
63. If requested, submitted an Adaptive Management Response
report in accordance with S4.F.3.a.
64. Attach a summary of the status of implementation of any actions
taken pursuant to S4.F.3 and the status of any monitoring,
assessment, or evaluation efforts conducted during the reporting
period? (S4.F.3.d)
65. Notified Ecology of the failure to comply with the permit terms
and conditions within 30 days of becoming aware of the non-
compliance? (G20)
66. Number of non-compliance notifications (G20) provided in
reporting year.
66b. List permit conditions described in non-compliance
notification(s) in Comments field.
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Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 1 of 14
APPENDIX 9 – Stormwater Discharge Monitoring
This Appendix applies to Permittees with stormwater discharge monitoring requirements
pursuant to Special Condition S8 Monitoring and Assessment, particularly sections S8.B.2, for
Clark County, and S8.C.2, if a Permittee chooses not to participate in the Regional Stormwater
Monitoring Program (RSMP) by paying into a collective fund to implement RSMP effectiveness
studies.
Stormwater discharge monitoring is intended to characterize stormwater runoff quantity and
quality at a limited number of locations in a manner that allows analysis of loadings and changes
in conditions over time and generalization across the Permittee’s jurisdiction.
QAPP Preparation
Permittees shall prepare a Quality Assurance Project Plan (QAPP) in accordance with Quality
Assurance Project Plan Guidance, Special Condition S8.D, Phase I Municipal Stormwater
Permit, December 2010 (Ecology Publication no. 10-10-075
http://www.ecy.wa.gov/pubs/1010075.pdf). The QAPP shall be developed by qualified staff or
contractors with experience in applying Ecology or Environmental Protection Agency (EPA)
QAPP Guidelines.
A stormwater discharge monitoring QAPP shall be submitted to Ecology in accordance with the
deadlines in S8. The QAPP shall describe field collection methods and sample preparation
methods appropriate to each group of analytes, reporting limits, and field conditions.
Permittees are responsible for maintaining an up-to-date approved QAPP for stormwater
discharge monitoring. Significant changes shall be reviewed by Ecology and reflected in a
revised QAPP. Significant changes include, but are not limited to:
• Land disturbing activities over 10 acres in size within the sampled drainage area.
• Relocating a monitoring station.
• Introducing new sampling equipment.
• Unanticipated back water conditions, base flow, or tidal influences.
• Changes in laboratories, analytical methods, or reporting limits.
Discharge Monitoring Location Selection
Stormwater monitoring discharge monitoring locations shall have mapped tributary conveyance
systems and drainage areas, and be suitable for permanent installation and operation of flow-
weighted composite sampling equipment. Additional monitoring location selection guidance and
information about how to estimate a rainfall to runoff relationship is available in Standard
Operating Procedure for Automatic Sampling for Stormwater Monitoring, ECY002 from the
Ecology Quality Assurance Page (http://www.ecy.wa.gov/programs/eap/quality.html; specific
guidance for automatic sampling is available at
http://www.ecy.wa.gov/programs/eap/qa/Agency/ECY_WQ_SOP_AutomatedSampling_v1_0E
CY002.pdf).
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Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 2 of 14
Permittees may identify a discharge monitoring location upstream in the conveyance system (i.e.,
upgradient of the outfall) in order to achieve the desired land use, to accommodate the
installation of sampling equipment, and/or to avoid or minimize back water or tidal interference.
The QAPP shall describe each stormwater discharge monitoring location and associated drainage
basin in detail. The QAPP must describe how each discharge monitoring location was selected,
the size of the drainage basin, and the percentage of area in the drainage basin representing the
following land uses: high density residential, low density residential, commercial, industrial,
agriculture, and transportation right-of-way. Table A9-1 below provides characteristics to
consider for some of these land uses. However, density definitions can vary from jurisdiction to
jurisdiction and may be defined locally in codes and comprehensive plans. Report the residential
density definitions used if they differ from these.
Table A9-1 Land Use Selection Characteristics
Land use category Characteristics
High density residential 4 dwelling units per acre or greater
Medium to high density residential 2 to 4 dwelling units per acre
Low density residential 1 to 2 dwelling units per acre
Commercial Includes multi-family residential
Industrial Not predominated by one facility with a few operators
Flow Monitoring
Discharge monitoring locations must be evaluated for a rainfall to runoff relationship in order to
ensure that the discharge monitoring location will receive enough runoff for sufficient sample
volume. This rainfall to runoff relationship will also assist in programming the automatic
sampling equipment. In order to establish the rainfall to runoff relationship, one year of
continuous flow recording (including base flow and all storm events) is necessary.
Monitoring Frequency
Permittees shall sample each stormwater discharge monitoring location according to the
frequency described below. Documented good faith efforts with good professional practice by
the Permittee which do not result in collecting a successful sample for the full number of
required storms may be considered as contributing toward compliance with this requirement.
For each location, the Permittee shall sample and analyze a minimum of eleven (11) qualifying
storm events per water year. Qualifying storm event sampling must be distributed throughout the
year, approximately reflecting the distribution of rainfall between the wet and dry seasons (with
a goal of 60-80% of the samples collected during the wet season and a goal of 20-40% of the
samples collected in the dry season).
Ecology may approve a reduced sampling frequency if the Permittee provides a statistical
analysis demonstrating that monitoring goals can be met with fewer samples.
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August 1, 2013
Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 3 of 14
Qualifying Storm Event Criteria
The wet season is from October 1 through April 30. A qualifying wet season storm event is
defined as follows:
• Rainfall volume: 0.20” minimum, no fixed maximum
• Rainfall duration: No fixed minimum or maximum
• Antecedent dry period: Less than or equal to 0.05” rain in the previous 24 hours
• Inter-event dry period: 6 hours
The dry season is from May 1 through September 30. A qualifying dry season storm event is
defined as follows:
• Rainfall volume: 0.20” minimum, no fixed maximum
• Rainfall duration: No fixed minimum or maximum
• Antecedent dry period: less than or equal to 0.02” rain in the previous 48 hours
• Inter-event dry period: 6 hours
Types of Sampling
Storm events shall be sampled using flow-weighted composite sampling techniques. Automatic
samplers shall be programmed to begin sampling as early in the runoff event as practical and to
continue sampling past the longest estimated time of concentration for the tributary area. Refer to
Standard Operating Procedure for Automatic Sampling for Stormwater Monitoring, ECY002
(http://www.ecy.wa.gov/programs/eap/quality.html) for guidance on how to conduct flow
weighted composite sampling.
For storm events lasting less than 24 hours, samples shall be collected for at least seventy-five
percent (75%) of the storm event hydrograph. For storm events lasting longer than 24 hours,
samples shall be collected for at least seventy-five percent 75% of the hydrograph of the first 24
hours of the storm.
Each composite sample shall be targeted to contain at least 10 aliquots. Composite samples with
7 to 9 aliquots are acceptable if they meet the other sampling criteria and help achieve a
representative balance of wet season/dry season events and storm sizes.
Continuous flow recording of all storm events (not just sampled storm events) is necessary for at
least one complete water year to establish a baseline rainfall/runoff relationship. Ongoing
continuous flow monitoring is required for each of the sampled storm events as necessary to
properly conduct the flow-weighted composite sampling. Precipitation data shall be collected
from the nearest rain gauge reporting at least hourly rainfall amounts.
Grab samples are necessary for some parameters (see below) and shall be collected early in the
storm event. Refer to Standard Operating Procedure for Grab Sampling for Stormwater
Monitoring, ECY001 (http://www.ecy.wa.gov/programs/eap/quality.html).
Use of in-line sediment traps or similar collection system is preferred for sediment samples; refer
to Standard Operating Procedure for Collection of Stormwater Sediments using In-Line
Sediment Traps, ECY003 (http://www.ecy.wa.gov/programs/eap/quality.html).
Western Washington Phase II Municipal Stormwater Permit
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Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 4 of 14
Sediment samples shall be collected once per water year at each stormwater discharge
monitoring location, or in the vicinity of each stormwater monitoring location, during the month
of May or June.
Sampling of receiving water sediment deposits is an alternative where approved by Ecology.
Parameters
Flow-weighted composite samples shall be analyzed for the following parameters utilizing an
Ecology- or EPA-accredited laboratory and the methods and reporting limits as provided in table
A9-2 at the end of this appendix or otherwise approved by Ecology.
• Conventional parameters: total suspended solids (TSS), turbidity, conductivity, chloride,
biochemical oxygen demand (BOD5), hardness, pH, and methylene blue activating
substances (MBAS).
• Nutrients: total phosphorus, orthophosphate, total kjeldahl nitrogen, and nitrate plus
nitrite
• Metals, total and dissolved: copper, zinc, cadmium, lead, and mercury
• Organics:
o Polycyclic aromatic hydrocarbon (PAH) compounds: acenaphthene,
acenaphthylene, anthracene, benzo(a)anthracene, benzo(a)pyrene,
benzo(b)fluoranthene, benzo(ghi)perylene, benzo(k)fluoranthene, chrysene,
dibenzo(a,h)anthracene, fluoranthene, fluorene, indeno(1,2,3-cd)pyrene,
naphthalene, phenanthrene, and pyrene
o Herbicides: 2,4-D and dichlobenil
o Insecticides: carbaryl and chlorpyrifos
o Phthalates: bis(2-Ethylhexyl)phthalate
If the volume of the stormwater sample collected from a qualifying storm is insufficient to allow
analysis for all of the parameters listed above, the sample shall be analyzed for as many
parameters as possible in the following priority order: (1) metals and hardness; (2) TSS; (3)
organics: PAHs, herbicides, insecticides, phthalates; (4) nutrients; (5) conductivity; (6) BOD5;
and (7) remaining conventional parameters. If insufficient sample exists to run the next highest
priority pollutant, that analysis may be bypassed and analyses run on lower priority pollutants in
accordance with the remaining priority order to the extent possible. Parameters that are below
reporting limits after two years of data may be dropped from the analysis.
Grab samples shall be analyzed for the following parameters utilizing an Ecology- or EPA-
accredited laboratory and the methods and reporting limits listed in Table A9-2 at the end of this
Appendix.
• Fecal coliform bacteria
• Total petroleum hydrocarbons (TPH): NWTPH-Gx and NWTPH-Dx and BTEX
(benzene, toluene, ethyl -benzene, and xylenes).
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Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 5 of 14
Sediment samples shall be analyzed for the following parameters utilizing an Ecology- or EPA-
accredited laboratory and the methods and reporting limits listed in table A9-3 at the end of this
Appendix or otherwise approved by Ecology. If the volume of sediment sample is insufficient to
analyze for all of the parameters listed below, the sample shall be analyzed for as many
parameters as possible in the following priority order:
• Total organic carbon
• Metals: copper, zinc, lead, cadmium, and mercury
• Organics:
o PAH compounds: benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene,
chrysene, 2,6-dimethylnaphthalene, 2-methylnaphthalene, fluoranthene,
naphthalene, benzo(ghi)perylene, phenanthrene, and pyrene
o Petroleum hydrocarbons: NWTPH-Dx
o Pyrethroids: bifenthrin
o PCBs: aroclors
• Total volatile solids
• Total phosphorus
• Percent solids, grain size
A minimum of one sediment sample per year shall be collected. Additional samples shall be
collected if insufficient sample exists from a single sample to run all of the organic pollutants
listed above. A visual, qualitative determination of grain size shall be reported for all samples (in
addition to the quantitative analysis for all samples with sufficient volume). Parameters that are
below reporting limits after two years of data may be dropped from the analysis.
Recordkeeping and Reporting
For each stormwater monitoring location, calculate the following:
• Event Mean Concentrations (EMCs)
• Total annual pollutant load by parameter
• Seasonal pollutant loads by parameter for the wet and dry seasons
The annual pollutant load calculations must be based on a water year and include wet and dry
season loads and total annual load (wet plus dry season load). The loadings shall be expressed as
total pounds and as pounds per acre, and must take into account potential pollutant load from
base flow. Loadings shall be calculated following Standard Operating Procedure for Calculating
Pollutant Loads for Stormwater Discharges, ECY004
(http://www.ecy.wa.gov/programs/eap/quality.html). Pollutant loading information is required
for water quality parameters only.
Annual Monitoring Reports shall be submitted with each Annual Report beginning with the first
Annual Report following the first full water year of monitoring. Annual Monitoring Reports shall
provide all monitoring data collected during the preceding water year (October 1 – September
30). Concentration data shall be provided in the same units that are specified for Reporting
Limits in Tables A9-2 and A9-3. Flow data shall be provided in gallons per minute. Loading data
for each water year shall be provided in total pounds and in pounds per acre. Annual Monitoring
Reports shall consist of a narrative report, an Excel spreadsheet with all data and pollutant
Western Washington Phase II Municipal Stormwater Permit
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Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 6 of 14
loading calculations, and a submittal to Ecology’s Environmental Information Management
(EIM) database. For the Annual Monitoring Report to be considered on time, the EIM data
submission process must be initiated before April 1 of each relevant year, and completed by June
15 of each relevant year.
Annual Monitoring Reports shall include:
• A brief summary of each monitored drainage basin (full details of the monitoring
drainage basin shall be in the QAPP), including any changes within the contributing
drainage area or changes to the monitoring station that could affect hydrology and/or
pollutant loading.
• A description of each flow-weighted composite and grab sampled storm event, including:
o General summary about storm event criteria, including:
Precipitation data (in inches) including antecedent dry period and rainfall
distribution throughout the event.
Flow and hydrograph data including sampled and total runoff time periods
and volumes.
Total number of qualifying storm events captured and analyzed at each
monitoring location.
Distribution of storms collected between wet and dry seasons (permit
goals include 60-80% of storms during the wet season and 20-40% of
storms during the dry season).
Logistical problems associated with any storm event criterion.
o A hyetograph and a hydrograph for each sampled storm event. Include properly
labeled graphs that display the following:
Date of the storm event.
Time of day versus precipitation information.
Time versus flow rate (in gallons per minute).
Time versus aliquot collection.
Display the total duration of the storm event, not just the duration when
samples were collected (remember your pollutant load calculation must
include flow for the entire storm event, not just the water quality sampled
portion).
o A summary of (or in the graph) the total runoff volume in gallons.
o A rainfall/runoff relationship table used to estimate the un-sampled storm events
(when water quality samples were not collected). This is used for future
estimations of annual and seasonal loads.
o Whether or not any chemicals were removed from the list of analysis due to two
years of non-detect data.
o A brief summary with storm event dates where insufficient volumes were
collected. Include the parameters analyzed.
• A description of the sediment sampling event, including:
o Whether or not any chemicals were removed from the list of analysis due to two
years of non-detect data.
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Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 7 of 14
o A summary of sediment sampling (including dates) where insufficient volumes
were collected. Include the parameters analyzed.
• Event Mean Concentrations (EMCs)
• The wet and dry season pollutant loads and annual pollutant load based on water year for
each discharge monitoring location expressed in total pounds, and pounds per acre.
Include the following:
o For storm events where water quality samples were collected, the load in pounds
per day for each parameter for each sampled storm event, include date of storm
events.
o An estimated seasonal pollutant load for each parameter at each discharge
monitoring location. This is calculated using all storm events (when water quality
samples were collected and when samples were not collected).
o A total annual pollutant load (wet season load + dry season load) for each
parameter (include estimated events).
o The rainfall/runoff relationship including your pollutant load estimates for un-
sampled events.
o Note that if any data is unavailable to effectively estimate your rainfall to runoff
relationship due to an incomplete water year, submit this information in the next
year’s stormwater monitoring report.
• Quality Assurance/Quality Control information for each successfully sampled qualifying
storm event at each discharge monitoring location and sediments sampled at each
discharge monitoring location, including:
o A narrative summary of your field and laboratory verification, validation results
and quality control checks performed.
o A narrative analysis of your field and laboratory quality control sample results
and how they compare with your data quality objectives/indicators in your QAPP.
o Corrective actions reported/taken.
• An explanation and discussion of results from each successfully sampled qualifying storm
event at each discharge monitoring location and sediments collected at each discharge
monitoring location, including:
o A statistical analysis of the event mean concentrations for each parameter and a
narrative description of significant findings from this analysis.
o Any conclusions based on data from this study including analyses of previously
collected data from these discharge monitoring locations.
• A description of Stormwater Management Program activities currently taking place or
planned within the monitoring station’s drainage area that may have affected or may
potentially affect future monitoring results.
If the Permittee monitors any pollutant more frequently at the stormwater discharge monitoring
locations, then the results of this monitoring shall be included in the annual monitoring report
reflecting the water year in which the monitoring occurred.
Western Washington Phase II Municipal Stormwater Permit
_____________________________________________________________________________________________
August 1, 2013
Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 8 of 14
After three (3) water years of data, the Annual Monitoring Report shall include:
• Trend analyses,
• An evaluation of the data as it applies to the SWMP, and
• Any stormwater management activities the Permittee has identified that can be adjusted
to respond to this data.
Western Washington Phase II Municipal Stormwater Permit
_____________________________________________________________________________________________
August 1, 2013
Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 9 of 14
Laboratory Methods
The Permittee’s stormwater discharge monitoring program shall use the following analytical
methods or other methods approved by the U.S. Environmental Protection Agency or Ecology
with similar reporting limits, unless alternative methods are approved by Ecology. Any
alternative method proposed by a Permittee must have a similar reporting limit, or must be
justified as adequate for the likely, expected range of concentrations. Permittees are not
guaranteed approval of alternative methods or reporting limits.
In cases where smaller volumes of water are expected to be collected, or to save analytical costs,
Permittees may propose that some of the analyses be optimized for specific parameters or
groups. The Permittee must, in consultation with a qualified chemist, define the exact volumes
and optimization steps and include them in the QAPP.
Table A9-2 Analytical Procedures in Stormwater
Analyte Method in Water Reporting
Limita
Conventional Parameters
Total suspended solids SM 2540Bb or SM 2540D 1.0 mg/L
Turbidity EPA Method 180.1 or SM2130B + 0.2 NTU
Conductivity SM 2510 or EPA Method 120.1 + 1 umhos/cm
Chloride EPA Method 300.0, EPA Method 325.2, or
SM4110B or SM4500 Cl-E 0.2 mg/L
BOD5 SM5210B 2.0 mg/L
Particle size distribution 1 Coulter Counter, Laser diffraction, or
comparable method - see attached method
NA
pH EPA Method 150.2 or SM 4500H+ 0.2 units
Hardness as CaCO3 EPA Method 200.7, SM2340B(ICP), SM2340C
(titration) or SM 3120B 1.0 mg/L
Methylene blue activated
substances (MBAS)
CHEMetrics Colorimetric or SM5540C 0.025 mg/L
Bacteria
Fecal Coliform SM 9221E 2 min., 2E6 max.
Nutrients
Orthophosphate and total
phosphorus
EPA Method 365.3, EPA Method 365.4, SM
4500-P E or SM4500-P F
0.01 mg P/L
Total Kjeldahl nitrogen EPA Method 351.2, EPA Method 351.1, SM
4500 Norg-B, SM 4500 Norg-C, SM 4500
NH3-D, SM 4500 NH3-G, SM 4500 NH3-E or
SM4500 NH3-F
0.5 mg/L
Nitrate-Nitrite EPA Method 353.2 or SM 4500 -NO3- E 0.01 mg/L
1 Particle size distribution is required only for monitoring sites that measure discharge from best management
practices.
Western Washington Phase II Municipal Stormwater Permit
_____________________________________________________________________________________________
August 1, 2013
Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 10 of 14
Metals
Total recoverable zinc EPA Method 200.8 (ICP/MS), EPA Method
200.7 (ICP) or SM 3125 (ICP/MS)
5.0 µg/L
Dissolved zinc EPA Method 200.8 (ICP/MS), or SM 3125
(ICP/MS)
1.0 µg/L
Total recoverable lead EPA Method 200.8 (ICP/MS), or SM 3125
(ICP/MS)
0.1 µg/L
Dissolved lead, copper, and
cadmium EPA Method 200.8 (ICP/MS), or SM 3125
(ICP/MS)
0.1 µg/L
Total recoverable copper EPA Method 200.8 (ICP/MS), or SM 3125
(ICP/MS)
0.5 µg/L
Total recoverable cadmium EPA Method 200.8 (ICP/MS), or SM 3125
(ICP/MS)
0.2 µg/L
Total and dissolved mercury EPA Method 7470 (CVAA), EPA Method
245.7, or EPA Method 1631E
0.1 µg/L
Organics
PAH compounds EPA Method 8310 or 8270 D SIM 0.1 µg/L
Herbicides
(2,4-D, dichlobenil)
EPA Method 8270 D SIM or 8151 A 0.1 µg/L, 1 µg/L
Carbamate insecticides
(carbaryl)
EPA Method 632 0.5 µg/L
Organophosphate insecticides
(chlorpyrifos)
EPA Method 625 or EPA Method 614, 8270 D,
EPA Method 622, EPA Method 1657
0.5 µg/L
Phthalates
(bis(2-ethylhexyl)phthalate)
EPA Method 8270 D 1 µg/L
Petroleum Hydrocarbons
NWTPH-Dx Ecology, 1997, (Publication No. 97-602) 0.25-0.5 mg/L
NWTPH-Gx Ecology, 1997, (Publication No. 97-602) 0.25 mg/L
BTEX EPA Method 8260 or 602 1 µg/L or 5 µg/L
a. The QAPP shall identify Ecology- or EPA-approved methods with appropriate reporting limits. An individual
sample that could not be run at a reporting limit because of matrix interference or other such reasons would
not be called into question for compliance purposes. All results shall be reported. For non-detect values below
the reporting limit, report results at the method detection limit from the lab and the qualifier of “U” for
undetected at that concentration.
b. To ensure accurate results, Ecology recommends modifying these methods to analyze (filter) the entire field
sample. Research results indicate that errors may be introduced by decanting a subsample, although using a
funnel splitter may help. The analyst may also consider analyzing several premixed subsamples from the
same sample container to determine if significant variability occurred due to stratification. Reports shall
indicate whether the entire field sample or a subsample was used.
NA – Not applicable
SM – Standard Methods
Western Washington Phase II Municipal Stormwater Permit
_____________________________________________________________________________________________
August 1, 2013
Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 11 of 14
Table A9-3 Analytical Procedures in Sediments
Analyte Method in Sediment Reporting
Limita
Conventional Parameters
Percent solids SM 2540G NA
Total organic carbon Puget Sound Estuary Protocols (PSEP 1997),
SM 5310B, SM 5310C, SM 5310D or EPA
Method 9060
0.1%
Grain size Sieve and Pipette (ASTM 1997), ASTM F312-
97, ASTMD422 or PSEP 1986/2003
NA
Total phosphorus EPA Method 365.3, EPA Method 365.4, SM
4500 P E or SM 4500 P F
0.01 mg/kg
Total volatile solids EPA Method 160.4 or SM 2540G 0.1%
Metals
Total recoverable zinc EPA Method 200.8 (ICP/MS), EPA Method
6010, EPA Method 6020 or SM 3125
(ICP/MS), or EPA Method 200.7 (ICP)
5.0 mg/kg
Total recoverable lead EPA Method 200.8 (ICP/MS), EPA Method
6010, EPA Method 6020 or SM 3125
(ICP/MS)
0.1 mg/kg
Total recoverable copper EPA Method 200.8 (ICP/MS), EPA Method
6010, EPA Method 6020 or SM 3125
(ICP/MS)
0.1 mg/kg
Total recoverable cadmium EPA Method 200.8 (ICP/MS), EPA Method
6010, EPA Method 6020 or SM 3125
(ICP/MS)
0.1 mg/kg
Total recoverable mercury EPA Method 245.5 or EPA Method 7471B 0.005 mg/kg
Organics
PAH compounds EPA Method 8270 D 70 µg/kg dry
Pyrethroids (bifenthrin) EPA Method 8270 D, EPA Method 1660 1.0 µg/kg dry
PCBs (aroclors) EPA Method 8082 80 µg/kg dry
Petroleum Hydrocarbons
NWTPH-Dx Ecology, 1997 (Publication No. 97-602) or
EPA SW-846 method 8015B
25.0-100.0 mg/kg
a. The QAPP shall identify Ecology- or EPA-approved methods with appropriate reporting limits. An individual
sample that could not be run at a reporting limit because of matrix interference or other such reasons would
not be called into question for compliance purposes. All results shall be reported. For non-detected values
below the reporting limit, report results at the method detection limit from the lab and the qualifier of “U” for
undetected at that concentration.
NA – Not applicable
SM – Standard Methods
Western Washington Phase II Municipal Stormwater Permit
_____________________________________________________________________________________________
August 1, 2013
Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 12 of 14
WET SIEVING AND MASS MEASUREMENT
FOR LASER DIFFRACTION ANALYSIS
WET SIEVING
Sample Collection/Handling
Samples should be collected in HDPE or Teflon containers and held at 4 degrees C during the
collection process. If organic compounds are being collected, the sample containers should be
glass or Teflon.
Preservation/Holding Time
Samples should be stored at 4o C and must be analyzed within 7 days (EPA, 1998). Samples
may not be frozen or dried prior to analysis, as either process may change the particle size
distribution.
Sonication
Do not sonicate samples prior to analysis to preserve particle integrity and representativeness.
Laboratories using laser diffraction will have to be notified not to sonicate these samples at any
time during the analysis. It is recommended that this request also be written on the chain-of-
custody form that the analytical laboratory receives in order to assure that sonication is omitted.
LABORATORY PROCEDURES
Equipment
__ 2 Liters of stormwater sample water (total sample required for analysis (ASTM D 3977))
__ Drying oven (90 degrees C +2 degrees)
__ Analytical balance (0.01 mg accuracy)
__ Desiccator (large enough diameter to accommodate sieve)
__ Standard sieves - larger than 2" diameter may be desirable
__ 500 um (Tyler 32, US Standard 35)
__ 250 um (Tyler 60, US Standard 60)
__ Beakers - plastic (HDPE)
__ Funnel (HDPE - Large enough diameter to accommodate sieve)
__ Wash bottle
__ Pre-measured reagent-grade water
Sample Processing
• Dry 250 um and 500 um mesh sieves in a drying oven to a constant weight at 90 ± 2° C.
• Cool the sieves to room temperature in a desiccator.
• Weigh each sieve to the nearest 0.01 mg.
• Record the initial weight of each dry sieve.
• Measure the volume of sample water and record.
• Pour the sample through a nested sieve stack (the 500 um sieve should be on the top and the
sieve stack should be stabilized in a funnel and the funnel should be resting above/inside a
collection beaker).
• Use some of the pre-measured reagent-grade water in wash bottle to thoroughly rinse all soil
particles from sample container so that all soil particles are rinsed through the sieve.
Western Washington Phase II Municipal Stormwater Permit
_____________________________________________________________________________________________
August 1, 2013
Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 13 of 14
• Thoroughly rinse the soil particles in the sieve using a pre-measured volume of reagent-grade
water.
• The particles that pass through the sieve stack will be analyzed by laser diffraction Particle
Size Distribution (PSD) analysis using the manufacturers recommended protocols (with the
exception of no sonication).
• Particles retained on the sieve (>250 um) will not be analyzed with the laser diffraction PSD.
• Dry each sieve (500 um and 250 um) with the material it retained in a drying oven to a
constant weight at 90 ± 2° C. The drying temperature should be less than 100° C to prevent
boiling and potential loss of sample (PSEP, 1986).
• Cool the samples to room temperature in a desiccator.
• Weigh the cooled sample with each sieve to the nearest 0.01 mg.
• Subtract initial dry weight of each sieve from final dry weight of the sample and sieve
together.
• Record weight of particles/debris separately for each size fraction (> 500 um and 499 - 250
um).
• Document the dominant types of particles/debris found in this each size fraction.
Laser Diffraction (PSD)
PSD results are reported in ml/L for each particle size range. Particle size gradations should
match the Wentworth grade scale (Wentworth, 1922).
Mass Measurement
Equipment
__ Glass filter - 0.45 um (pore size) glass fiber filter disk (Standard Method D 3977) (larger
diameter sized filter is preferable)
__ Drying oven (90 degrees C +2 degrees)
__ Analytical balance (0.01 mg accuracy)
__ Wash bottle
__ Reagent-grade water
Procedure
• Dry glass filter in drying oven at 90 ± 2° C to a constant weight.
• Cool the glass filter to room temperature in a desiccator.
• Weigh the 0.45 um glass filter to the nearest 0.01mg.
• Record the initial weight of the glass filter.
• Slowly pour the laser diffraction sample water (after analysis) through the previously
weighed 0.45 um glass filter and discard the water.
• Use reagent-grade water in wash bottle to rinse particles adhering to the analysis container
onto glass filter
• Dry glass filter with particles in a drying oven at 90 ± 2° C to a constant weight.
• Cool the glass filter and dried particles to room temperature in a desiccator.
• Weigh the glass filter and particles to the nearest 0.01mg.
• Subtract the initial glass filter weight from the final glass filter and particle sample weight.
• Record the final sample weight for particles <250 um in size.
Western Washington Phase II Municipal Stormwater Permit
_____________________________________________________________________________________________
August 1, 2013
Modified January 16, 2015 Appendix 9 – Stormwater Discharge Monitoring Page 14 of 14
Quality Assurance
Dried samples should be cooled in a desiccator and held there until they are weighed. If a
desiccator is not used, the particles will accumulate ambient moisture and the sample weight will
be overestimated. A color-indicating desiccant is recommended so that spent desiccant can be
detected easily. Also, the seal on the desiccator should be checked periodically, and, if necessary,
the ground glass rims should be greased or the "O" rings should be replaced.
Handle sieves with clean gloves to avoid adding oils or other products that could increase the
weight. The weighing room should not have fluctuating temperatures or changing humidity. Any
conditions that could affect results such as doors opening and closing should be minimized as
much as possible.
After the initial weight of the sieve is measured, the sieve should be kept covered and dust free.
Duplicate samples should be analyzed on 10% of the samples for both wet sieving and mass
measurements.
Reporting
Visual observations should be made on all wet sieved fractions and recorded. For example if the
very coarse sand fraction (2,000-1,000 um) is composed primarily of beauty bark, or cigarette
butts, or other organic debris this should be noted. An option might also be for a professional
geologist to record the geological composition of the sediment as well.
REFERENCES
ASTM. 1997. Standard test methods for determining sediment concentration in water samples.
Method D 3977. American Society for Testing and Materials, Philadelphia, PA.
PSEP. 1986. Recommended Protocols for measuring conventional sediment variables in Puget
Sound. Prepared by Tetra Tech, Inc. for U.S. Environmental Protection Agency and Puget
Sound Water Quality Authority. Tetra Tech Inc., Bellevue, WA.
U. S. EPA. 1998. Analysis of total suspended solids by EPA Method 160.2. Region 9, Revision
1. SOP 462. 12 pp
Wentworth, C.K. 1922. A scale of grade and class terms for clastic sediments. Journal of
Geology. 30:377-392
Comprehensive Storm Drainage Plan
B-1
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Appendix B: Phase II NPDES Stormwater Permit
Compliance Work Plan
Phase II NPDES Municipal
Stormwater Permit
Compliance Work Plan
Prepared for the
City of Auburn, Washington
July 2, 2014
701 Pike Street, Suite 1200
Seattle, WA 98101
Phase II NPDES Municipal Stormwater Permit
Compliance Work Plan
Prepared for the
City of Auburn Washington
July 2 , 201 4
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2014 Auburn NPDES Compliance Work Plan.docx
Table of Contents
List of Tables ....................................................................................................................................................... v
List of Abbreviations .......................................................................................................................................... vi
Executive Summary ........................................................................................................................................... 1
1. Introduction ............................................................................................................................................. 1-1
1.1 Overview and Background ........................................................................................................... 1-1
1.2 Schedule for Permit Compliance ................................................................................................. 1-1
1.3 Key Policy Issues........................................................................................................................... 1-2
1.3.1 LID Principles .................................................................................................................. 1-3
1.3.2 LID Infeasibility Criteria and Competing Needs ............................................................ 1-3
1.3.3 Manual Adoption ............................................................................................................ 1-3
1.3.4 Code Revisions ............................................................................................................... 1-3
1.3.5 LID Facility Inspections .................................................................................................. 1-4
1.3.6 Additional City Effort and Costs ..................................................................................... 1-4
1.4 Document Organization ................................................................................................................ 1-4
2. Stormwater Management Program Administration .............................................................................. 2-1
2.1 New Permit Requirements ........................................................................................................... 2-1
2.2 Current Compliance Activities Applicable to New Requirements .............................................. 2-1
2.3 Recommended Actions to Maintain Future Compliance ............................................................ 2-1
3. Public Education and Outreach .............................................................................................................. 3-1
3.1 New Permit Requirements ........................................................................................................... 3-1
3.2 Current Compliance Activities Applicable to New Requirements .............................................. 3-2
3.3 Compliance Policy Issues ............................................................................................................. 3-2
3.4 Recommended Actions to Maintain Future Compliance ............................................................ 3-2
4. Public Involvement .................................................................................................................................. 4-1
4.1 New Permit Requirements ........................................................................................................... 4-1
4.2 Current Compliance Activities Applicable to New Requirements .............................................. 4-1
4.3 Recommended Actions to Maintain Future Compliance ............................................................ 4-1
5. Illicit Discharge Detection and Elimination ............................................................................................ 5-1
5.1 New Permit Requirements ........................................................................................................... 5-1
5.2 Current Compliance Activities Applicable to New Requirements .............................................. 5-1
5.3 Recommended Actions to Maintain Future Compliance ............................................................ 5-1
6. Controlling Runoff from New Development, Redevelopment, and Construction Sites ...................... 6-1
6.1 New Permit Requirements ........................................................................................................... 6-1
6.2 Current Compliance Activities Applicable to New Requirements .............................................. 6-2
6.3 Compliance Policy Issues ............................................................................................................. 6-2
6.4 Recommended Actions to Maintain Future Compliance ............................................................ 6-3
7. Municipal Operations and Maintenance ............................................................................................... 7-1
Table of Contents Auburn NPDES Compliance Work Plan
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2014 Auburn NPDES Compliance Work Plan.docx
7.1 New Permit Requirements ............................................................................................................7-1
7.2 Current Compliance Activities Applicable to New Requirements ...............................................7-1
7.3 Recommended Actions to Maintain Future Compliance ............................................................7-1
8. TMDL Compliance ....................................................................................................................................8-1
8.1 New Permit Requirements ............................................................................................................8-1
8.2 Current Compliance Activities Applicable to New Requirements ...............................................8-1
8.3 Recommended Actions to Maintain Future Compliance ............................................................8-1
9. Monitoring and Assessment ...................................................................................................................9-1
9.1 New Permit Requirements ............................................................................................................9-1
9.2 Current Compliance Activities Applicable to New Requirements ...............................................9-1
9.3 Recommended Actions to Maintain Future Compliance ............................................................9-1
10. Limitations ............................................................................................................................................. 10-1
11. References ............................................................................................................................................ 11-1
Attachment A: Permit Compliance Schedule (Draft) ..................................................................................... A-1
(Courtesy Cities of Covington and SeaTac) ............................................................................................ A-1
Attachment B: Compliance Effort Estimate .................................................................................................. B-1
Attachment C: Gap Analysis Table ..................................................................................................................C-1
Auburn NPDES Compliance Work Plan Table of Contents
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List of Tables
Table 1-1. Summary Compliance Schedule .................................................................................................. 1-2
Table 2-1. Stormwater Management Program Administration .................................................................... 2-2
Table 3-1. Public Education and Outreach .................................................................................................... 3-2
Table 4-1. Public Involvement ........................................................................................................................ 4-1
Table 5-1. Illicit Discharge Detection and Elimination .................................................................................. 5-2
Table 6-1. Controlling Runoff from Development, Redevelopment, and Construction Sites ..................... 6-3
Table 6-2. Recommended City Code and Document Updates (Development-Related) ............................. 6-4
Table 7-1. Municipal Operations and Maintenance ..................................................................................... 7-2
Table 8-1. TMDL Compliance ......................................................................................................................... 8-2
Table 9-1. Monitoring and Assessment ......................................................................................................... 9-1
Table of Contents Auburn NPDES Compliance Work Plan
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List of Abbreviations
ACC Auburn City Code
BMP best management practice
City City of Auburn
CMMS computerized maintenance
management system
Ecology Washington State Department of
Ecology
Ecology Manual 2012 Stormwater Management
Manual for Western Washington
EPA U.S. Environmental Protection
Agency
GMA Growth Management Act
HR Human Resources Department
IDDE Illicit Discharge Detection and
Elimination
IT Information Technology
Department
LID low-impact development
MS4 municipal separate storm sewer
system
NPDES National Pollutant Discharge
Elimination System
O&M operations and maintenance
M&O City of Auburn Maintenance and
Operations Division
Permit NPDES Phase II Municipal
Stormwater Permit
RSMP Regional Stormwater Monitoring
Program
SIDIR Source Identification Information
Repository
SOP standard operating procedure
STORM Stormwater Outreach for Regional
Municipalities
SWMM City of Auburn Surface Water
Management Manual (November
2009)
SWMP Stormwater Management Program
SWPPP Stormwater Pollution Prevention
Plan
TMDL total maximum daily load
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Executive Summary
On August 1, 2012, the Washington State Department of Ecology (Ecology) reissued the National
Pollutant Discharge Elimination System (NPDES) Phase II Municipal Stormwater Permit (Permit) to
comply with requirements of the federal Clean Water Act. The new Permit became effective August 1,
2013, through July 31, 2018. The City of Auburn (City) will be required to pursue updates to the Auburn
City Code (ACC) and to City stormwater standards based on the requirements of this new NPDES Permit.
Maintaining compliance is important for the City for the following reasons:
Requirements of the Permit are intended to result in more “fishable, swimmable waters.”
Ecology has the power to levy fines or impose criminal penalties for noncompliance.
Grant funds may be affected by noncompliance.
Noncompliance with the Permit and the Clean Water Act can expose the City to third-party litigation.
Some of the most significant changes to the Permit include:
Requirements to evaluate City codes, standards, and policies and to incorporate low-impact
development (LID) principles, making LID the preferred way of managing stormwater runoff from
future development and redevelopment
Revised stormwater facility requirements for new development and redevelopment, which are more
intensive and will affect more projects, including single-family dwellings
Requirements for new and more frequent inspections of permanent stormwater infrastructure,
including small LID facilities to be constructed on virtually all private property over time
Requirement to pay for participation in Ecology water quality monitoring programs, or to conduct
equivalent programs independently
The updated Permit requirements may affect the City in a number of ways, including potential impacts
to:
City codes, standards, policies, and requirements, affecting both public and private activities.
Potentially impacted codes include ACC 13.48 and other development-related sections. The degree
of impact in other areas of the ACC (e.g., development regulation, transportation, zoning, etc.) will be
related to the outcome of the City’s LID principles review process. Updates to City standards and
guidance documents will also be required, including the City Surface Water Management Manual
(SWMM) and Engineering Design Standards. The new Permit requirements may also create
potential policy and public-relations issues related to access of private property for City-conducted
inspections and enforcement actions.
Staff effort for ongoing Permit compliance activities, including efforts to conduct the required LID
evaluation process; develop, adopt, and enforce code, standard, and policy updates; and conduct
new and more frequent inspections. Annual effort for City inspectors will increase over time as more
facilities are constructed, each of which must then be inspected in perpetuity.
City expense for potential additional staffing needs, capital improvement projects, and payments for
monitoring program participation. Staffing needs may increase as a result of increased compliance
efforts and field inspection requirements. Additional capital improvement project funding may be
required to incorporate required stormwater facilities into future City capital improvement projects.
Stormwater monitoring program participation includes annual payments of approximately $48,000
from the City to Ecology.
Executive Summary Auburn NPDES Compliance Work Plan
ES-2
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Developers and the general public, which may face additional costs and effort for many
development projects, including individual single-family residential projects.
The City is actively planning and preparing to comply with the updated Permit requirements, including
development of this Compliance Work Plan for compliance activities. The City will continue this Permit
compliance preparation with reviews of codes, policies, and standards, and will begin to implement new
requirements, including making the first annual payment to participate in Ecology’s monitoring
programs.
Over the 5-year term of the Permit, the City will conduct a variety of activities to update City codes,
standards, and policies, and to carry out this Compliance Work Plan consistent with regulatory schedule
deadlines. Activities involving significant resource allocation will include:
Conducting a process to review and incorporate LID principles into City codes, standards, and
policies
Developing and adopting updates to codes and other City documents, including the City
Comprehensive Plan
Developing and adopting updates to the Surface Water Management Manual (SWMM), or adopting
an alternative manual
Communicating new development requirements to the building industry and the public, and
enforcing new requirements
Funding construction of new stormwater facilities associated with City capital improvements and
providing for long-term maintenance of those facilities and other facilities accepted for maintenance
by the City
Developing and implementing updates to the City’s Public Education and Outreach, Illicit Discharge
Detection and Elimination (IDDE), and Operations and Maintenance (O&M) programs
Scheduling and conducting new and more frequent inspections of permanent stormwater
infrastructure, or providing Ecology with justification for less frequent inspections
Making annual payments to participate in the Ecology monitoring program
Compliance with total maximum daily load (TMDL) requirements
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Section 1
Introduction
1.1 Overview and Background
The National Pollutant Discharge Elimination System (NPDES) permit program is a requirement of the
federal Clean Water Act that is intended to protect and restore waters for “fishable, swimmable” uses.
The City of Auburn (City) is one of more than a hundred jurisdictions in Washington that has obtained,
and is currently in compliance with, a municipal stormwater discharge permit for “small” municipalities
(i.e., under 100,000 in population according to the 1990 census). This group of permittees is considered
to have “Phase II Permits,” with larger municipalities regulated by “Phase I Permits.”
These permits allow municipalities to discharge stormwater runoff from municipal drainage systems into
the state’s water bodies (i.e., streams, rivers, lakes, wetlands, etc.) as long as the municipalities have
programs that protect or minimize impacts to water quality as required by the Permit conditions.
Compliance deadlines for implementation of the Permit conditions are phased in over the 5-year Permit
term. The Washington State Department of Ecology (Ecology), as the delegated authority by the U.S.
Environmental Protection Agency (EPA), is to revise and reissue these permits every 5 years.
On August 1, 2012, Ecology reissued the NPDES Phase II Municipal Stormwater Permit (Permit),
effective August 1, 2013, through July 31, 2018. As a Phase II Permittee, the City will be required to
pursue updates to the Auburn City Code (ACC) and stormwater standards based on the requirements of
this new NPDES Permit.
The purpose of this Compliance Work Plan is to identify and make recommendations regarding the key
changes and activities that should take place over the next 5 years for the City to comply with the
updated Permit requirements. This identification includes:
Required compliance schedule deadlines
Recommended updates and activities, organized by applicable Permit section
Interim deadlines and activities for completing groups of similar tasks
Refer to the Phase II Gap Analysis Technical Memorandum, dated February 28, 2014, for details of the
Permit requirements and identification of potential Permit compliance gaps in City codes, standards, and
policies.
1.2 Schedule for Permit Compliance
A number of due dates for City Stormwater Management Program (SWMP) activities are included in the
updated Permit. Key Permit requirement due dates are summarized in Table 1-1.
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Table 1-1. Summary Compliance Schedule
Compliance activity Due date
Continue annual inspections of any onsite stormwater facilities approved by
the City for construction under the terms of the 2007–12 Permit or
subsequent Permits.
Ongoing
Communicate to Ecology whether the City will participate in the collective
fund for Monitoring and Assessment, or conduct stormwater monitoring
activities independently.
December 1, 2013 (completed)
Post SWMP documents to Web site annually. May 31 annually, starting 2014 (completed & ongoing)
Review and update interdepartmental coordination mechanisms, if needed. March 31, 2015 (completed)
Update public outreach and education materials. August 1, 2015
Measure effectiveness of public outreach for at least one target audience and
subject area (may be as part of a regional effort). February 2, 2016
Review and update City operations, maintenance, and inspection standards,
if needed. December 31, 2016
Adopt a new stormwater management manual: either the 2012 Stormwater
Management Manual for Western Washington (Ecology Manual) or an
approved equivalent.
December 31, 2016
Review, revise, and adopt local development codes, standards, and policies
to require low-impact development (LID) principles and LID best
management practices (BMPs), and to reflect deletion of the less than 1-acre
onsite stormwater facilities requirement exemption. The Permit requires a
specific process to be followed in considering revisions. This revision process
may involve revisions to a variety of potentially affected ACC sections.
December 31, 2016
Compile and submit a summary of the LID review and revision process. March 31, 2017
Complete one inspection of each catch basin, including documentation and
reporting.
August 1, 2017, and at least every
2 years thereafter
Complete field screening for 40% of the system by 2018, and 12% annually
thereafter.
December 31, 2017, annually
thereafter
Revise codes to reflect Illicit Discharge Detection and Elimination (IDDE)
changes in the Permit. February 2, 2018
1.3 Key Policy Issues
Over the 5-year Permit term, Auburn will need to address several significant policy issues affecting
multiple departments. The major policy issues associated with the updated Permit generally align with
the following categories:
Low-impact development (LID) principles assessment, policy development, implementation, and
reporting
LID infeasibility criteria and competing needs
Updates to the City Surface Water Management Manual (SWMM) or adoption of alternative manual
Code revisions
LID facility inspections
Additional City effort and costs
Major policy issues are described in the following sections.
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1.3.1 LID Principles
The revised Permit requires that development-related codes, standards, and enforcement be revised to
implement LID principles, including minimizing impervious surfaces, native vegetation loss, and
stormwater runoff. The requirement to minimize impervious areas poses regulatory challenges and may
have significant policy implications for Permittee interests outside of stormwater management.
Examples of potential policy conflicts might include preserving areas of existing vegetation and reducing
impervious surface areas vs. meeting parking requirements or roadway width standards.
The City will need to complete an assessment of LID principles related to various City codes, develop
policies for LID implementation, and report on the process to Ecology. The Puget Sound Partnership’s
Integrating LID into Local Codes: A Guidebook for Local Governments is a reference guidebook intended
by Ecology to be used in this policy development process.
1.3.2 LID Infeasibility Criteria and Competing Needs
The revised Permit allows local programs to identify LID infeasibility and competing needs criteria. These
could include infeasibility criteria for considerations like critical areas (e.g., steep slopes, slide-prone
areas, protected aquifers, and floodplains) or areas otherwise unsuitable for infiltration (e.g., areas with
seasonally high groundwater or low soil permeability). They could also include potentially conflicting
regulations (e.g., Growth Management Act [GMA] requirements), or local requirements (e.g.,
transportation or community planning considerations). It may be that infeasibility and competing needs
criteria can give local jurisdictions more flexibility; however, the criteria may also require additional
updates to the ACC and City policies. This issue may have significant policy implications for Permittee
interests outside of stormwater management.
1.3.3 Manual Adoption
Another key policy decision relates to adoption of a new manual for management of stormwater from
construction and new development and redevelopment sites. The Permit requires each Permittee to
adopt the 2012 Stormwater Management Manual for Western Washington (Ecology Manual) or an
equivalent manual approved by Ecology.
The City has several options related to adoption of a stormwater manual. During the previous Permit
cycle, the City developed the City-specific SWMM, based on the 2008 City of Tacoma manual. In order to
comply with updated Permit requirements, the City can choose one of three options:
Update the Auburn SWMM
Adopt the Ecology Manual
Adopt another Phase I jurisdiction’s equivalent manual (no local jurisdiction manuals are currently
approved as equivalent by Ecology, but achieving equivalency by at least some of the Phase I
Permittees is likely)
1.3.4 Code Revisions
City codes will require an update to comply with the new Permit requirements. The following major
changes will be required:
Updates to Chapter 13.48 (Storm Drainage Utility) and related sections to reflect updated definitions
and requirements for Illicit Discharge Detection and Elimination (IDDE), development activities, and
LID
Other updates to various City codes as identified during the LID Principles assessment process
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1.3.5 LID Facility Inspections
The previous Permit included requirements to conduct annual inspections for all permanent stormwater
best management practices (BMPs)/facilities permitted in accordance with the requirements of this
Permit. The requirements for inspections now include LID and facilities constructed on private
property. With the deletion of the 1-acre threshold exemption, this requirement takes on new
significance. With new development and redevelopment, virtually all properties will have the potential to
have an inspection requirement over time. The scale of required inspections and the requirement to
inspect on private property may pose challenges.
Increased presence of inspectors on private property and increased costs associated with inspections
represent policy issues that City officials may want to consider (e.g., options to fund inspections,
perceptions of increasing City authority, etc.).
1.3.6 Additional City Effort and Costs
The Permit will require additional activities that will grow over the 5-year Permit term. The City must
decide how to staff and fund the required new activities. See Attachment B for a preliminary estimate of
City effort and costs to comply with new Permit requirements.
1.4 Document Organization
The remainder of this Compliance Work Plan is organized similarly to the Permit:
Section 2 addresses compliance with the Permit requirements for administration of the City’s
Stormwater Management Program
Section 3 presents a compliance work plan for Public Education and Outreach
Section 4 presents a compliance work plan for Public Involvement and Participation
Section 5 presents a compliance work plan for Illicit Discharge Detection and Elimination
Section 6 presents a compliance work plan for Controlling Runoff from New Development,
Redevelopment, and Construction Sites
Section 7 presents a compliance work plan for Municipal Operations and Maintenance
Section 8 presents a compliance work plan for TMDL requirements
Section 9 presents a compliance work plan for Monitoring and Assessment
A ttachment A includes a schedule of due dates for new requirements
A ttachment B includes a compliance effort estimate developed to help the City identify staffing and
funding needs related to new Permit requirements
A ttachment C includes a gap analysis table developed to assess changes in the Permit and
corresponding impacts on City codes, standards, and activities
Each section includes a summary of new Permit requirements, current compliance activities that are
applicable to the new requirements, discussion of policy and compliance strategy issues (if applicable),
and recommended actions to maintain future compliance. For additional details on requirements and
recommended activities, see the Gap Analysis Table in Attachment C.
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Section 2
Stormwater Management Program
Administration
This section summarizes new Permit requirements for SWMP administration, current compliance
activities that are applicable to the new requirements, and recommended actions to maintain future
compliance.
2.1 New Permit Requirements
Sections S5.A, S7.A, and S9.A of the Permit include the following new requirements:
The SWMP shall include coordination mechanisms among departments within each jurisdiction to
eliminate barriers to compliance with the terms of this Permit. Permittees shall include a written
description of internal coordination mechanisms in the Annual Compliance Report, due no later than
March 31, 2015.
Each Annual Compliance Report shall include a summary of relevant SWMP and Appendix 2
activities conducted in the total maximum daily load (TMDL) area to address the applicable TMDL
parameter(s).
Permittees shall submit Annual Compliance Reports electronically using Ecology’s WQWebDMR
available on Ecology’s Web site at
http://www.ecy.wa.gov/programs/wq/permits/paris/webdmr.html unless otherwise directed by
Ecology. The first Annual Compliance Report will be due March 31, 2015, covering activities for
2014.
2.2 Current Compliance Activities Applicable to New Requirements
Current City compliance activities applicable to updated requirements of Sections S5.A, S7.A, and S9.A
include:
The City coordinates and tracks stormwater management activities and compliance across multiple
City departments.
The City completes and submits Annual Compliance Reports by March 31 annually.
2.3 Recommended Actions to Maintain Future Compliance
Auburn is compliant with the Permit requirements that are currently in effect. Additional requirements
will take effect during the next 4 years. Table 2-1 lists activities and time frames for the City to comply
with new Permit conditions related to SWMP administration.
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Table 2-1. Stormwater Management Program Administration
Task ID Task description Lead Support Compliance time frame
SWMP-2
Build on existing annual reporting task in 2014 SWMP; use
updated electronic template to complete and submit
annual reports
Utilities
Engineering None
Annual Compliance Report is due
by March 31 of each year beginning
in 2015
SWMP-3 Include a written description of internal coordination
mechanisms in the 2014 Annual Compliance Report
Utilities
Engineering
HR, M&O, Permit
Center,
Development
Engineering
Due March 31, 2015 (completed)
SWMP-4
Include summary of relevant SWMP and Appendix 2
activities related to applicable TMDLs in Annual Compliance
Report
Utilities
Engineering None Ongoing
Note: Task ID numbering and work items build on tasks currently included in the 2014 SWMP.
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Section 3
Public Education and Outreach
This section summarizes new Permit requirements for Public Education and Outreach, current
compliance activities that are applicable to the new requirements, discussion of policy and compliance
strategy issues, and recommended actions to maintain future compliance.
3.1 New Permit Requirements
Section S5.C.1 of the Permit requires the City to conduct the following activities:
Educate the general public (including school-age children) and businesses (including home-based
and mobile businesses) about several new areas, including:
Impacts of illicit discharges and how to report them
LID principles and LID BMPs
Opportunities to become involved in stewardship activities
Equipment maintenance
Prevention of illicit discharges
Educate engineers, contractors, developers, and land use planners about several new areas,
including:
Technical standards for stormwater construction site and erosion control plans
LID principles and LID BMPs
Stormwater treatment and flow control BMPs/facilities
Educate residents, landscapers, and property managers/owners about several new areas, including:
Use and storage of household chemicals
Vehicle, equipment, and home/building maintenance
Pet waste management disposal
LID principles and LID BMPs
Dumpster and trash compactor maintenance
Create stewardship opportunities and/or partner with existing organizations to encourage residents
to participate in activities such as stream teams, storm drain marking, volunteer monitoring, riparian
plantings, and education activities.
Measure the understanding and adoption of the targeted behaviors for at least one target audience
in at least one subject area. No later than February 2, 2016, Permittees shall use the resulting
measurements to direct education and outreach resources most effectively, as well as to evaluate
changes in adoption of the targeted behaviors. Permittees may meet this requirement individually or
as a member of a regional group.
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3.2 Current Compliance Activities Applicable to New Requirements
Current City compliance activities applicable to updated requirements include:
The City conducts numerous education and outreach activities that address stormwater
management targeted to the general public, residents/homeowners, and some industries.
The City is participating in a regional effort to develop effective ways to track and measure the
effectiveness of its education and outreach efforts.
The City tracks its education and outreach efforts.
The City is providing stewardship opportunities such as planting native plants and removing invasive
species at the Auburn Environmental Park.
3.3 Compliance Policy Issues
Measuring changes in understanding or behavior is a challenging objective. City representatives are
participating in a cooperative effort with several other NPDES municipalities to explore efficient and
effective methods to meet the Permit requirements for its public education and outreach program
evaluation.
3.4 Recommended Actions to Maintain Future Compliance
Auburn has a broad public education and outreach program but will need to update the program to
maintain compliance as the Permit requirements take effect. Table 3-1 lists activities and time frames
for the City to comply with new Permit conditions related to public education and outreach.
Table 3-1. Public Education and Outreach
Task ID Task description Lead Compliance time frame
EDUC-1
Build on collaboration with the Stormwater Outreach for
Regional Municipalities (STORM) group and Puget
Sound Starts Here efforts to identify and implement
programs to measure the understanding and adoption
of targeted behaviors for at least one target audience,
and adjust programming as needed
Utilities Engineering February 2, 2016
EDUC-3
Implement new or modify existing education and
outreach activities relative to new target
audiences/topics identified by the Permit
Utilities Engineering Ongoing
EDUC-6 Provide stewardship opportunities for the public Community Development
and Public Works, Parks Ongoing
Note: Task ID numbering and work items build on tasks currently included in the 2014 SWMP.
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Section 4
Public Involvement
This section summarizes new Permit requirements for Public Involvement, current compliance activities
that are applicable to the new requirements, and recommended actions to maintain future compliance.
4.1 New Permit Requirements
Section S5.C.2 of the Permit requires the City to:
Post on its Web site its SWMP Plan and the Annual Compliance Report required under S9.A no later
than May 31 of each year. All other submittals shall be available to the public upon request.
4.2 Current Compliance Activities Applicable to New Requirements
The City currently has activities and programs relevant to the Public Involvement requirement. These
activities are summarized below:
The City makes the SWMP document and Annual Compliance Report available to the public on the
City Web site.
4.3 Recommended Actions to Maintain Future Compliance
Auburn is on track for compliance with new Public Involvement requirements. Table 4-1 lists activities
and time frames for the City to comply with new Permit conditions related to Public Involvement.
Table 4-1. Public Involvement
Task ID Task description Lead Compliance time frame
PI-2 Define public involvement opportunities for annual SWMP
update and reporting process.
Utilities
Engineering
Continue to post to Web site; note the May
31 deadline for annual posting starting in
2014
Note: Task ID numbering and work items build on tasks currently included in the 2014 SWMP.
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Section 5
Illicit Discharge Detection and
Elimination
This section summarizes new Permit requirements for Illicit Discharge Detection and Elimination, current
compliance activities that are applicable to the new requirements, and recommended actions to
maintain future compliance.
5.1 New Permit Requirements
The Permit (Section S5.C.3) requires the City to:
Require thermal control of discharges from swimming pools, spas, and hot tubs.
Include informal compliance actions as an element of the City’s enforcement strategy.
Revise the City’s IDDE ordinance or regulatory mechanisms if necessary to meet the requirements of
this section no later than February 2, 2018.
Implement a field screening methodology appropriate to the characteristics of the municipal
separate storm sewer system (MS4) and water quality concerns. Screening for illicit connections
may be conducted using Illicit Discharge Detection and Elimination: A Guidance Manual for Program
Development and Technical Assessments, Center for Watershed Protection, October 2004, or
another methodology of comparable or improved effectiveness.
Document the field screening methodology in the relevant Annual Compliance Report.
Complete field screening for at least 40 percent of the MS4 no later than December 31, 2017, and
on average 12 percent each year thereafter.
5.2 Current Compliance Activities Applicable to New Requirements
The City currently has activities and programs relevant to IDDE requirements. These activities are
summarized below:
City codes and standards address illicit discharges.
The City conducts annual dry weather screening for illicit discharges and connections.
5.3 Recommended Actions to Maintain Future Compliance
Auburn has an established IDDE program, but will need to make some updates in order to maintain
compliance as new Permit requirements take effect. Table 5-1 lists activities and time frames for the City
to comply with new Permit conditions related to IDDE.
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Table 5-1. Illicit Discharge Detection and Elimination
Task ID Task description Lead Support Compliance time frame
IDDE-4
Complete updates to IDDE requirements in ACC 13.48
(e.g., updated Permit definitions and allowable
discharges).
Utilities Engineering M&O, City
Attorney February 2, 2018
IDDE-5
Complete updates to City standards and standard
operating procedures (SOPs) reflecting any modified
policies or activities.
Utilities Engineering M&O February 2, 2018
IDDE-6 Update public outreach and/or construction permitting
materials related to IDDE updates, if needed. Utilities Engineering
Permit
Center,
Development
Engineering
February 2, 2018
IDDE-7 Review policies and activities related to IDDE source control
(updated Ecology Manual BMPs) for potential update. Utilities Engineering None February 2, 2018
IDDE-8
Update the City’s screening methodology if desired
(optional). The prior Permit required outfall screening—the
2013 Permit allows greater flexibility, including in-system
screening. Permittees may continue to screen outfalls, or
begin screening in-system instead.
Develop local strategy/definition for 40% screening
coverage. Update SWMP with details of screening
methodology.
Utilities Engineering M&O
Establish early enough to
meet December 31, 2017
compliance targets
IDDE-9
Complete field screening using selected methodology,
including 40% of the City stormwater system by the end of
2017, and 12% of the system annually thereafter.
M&O Utilities
Engineering
December 31, 2017,
annually thereafter
Note: Task ID numbering and work items build on tasks currently included in the 2014 SWMP.
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Section 6
Controlling Runoff from New
Development, Redevelopment, and
Construction Sites
This section summarizes new Permit requirements for Controlling Runoff from New Development,
Redevelopment, and Construction Sites; current compliance activities that are applicable to the new
requirements; discussion of policy and compliance strategy issues; and recommended actions to
maintain future compliance.
6.1 New Permit Requirements
The Permit (Section S5.C.4) requires the City to:
Apply program requirements to construction sites disturbing less than an acre (removed the 1-acre
threshold for construction project exemption from many S5.C.4 requirements).
Update the City’s codes, standards, and programs to reduce pollutants in stormwater from new
development, redevelopment, and construction site activities, consistent with the updated minimum
technical requirements of the Permit, Appendix 1, and the 2012 Ecology Manual, including:
Updated definitions
Modified project thresholds
Updated Minimum Requirements, including incorporation of LID elements
Significantly updated Minimum Requirement 5, with new BMP lists and an LID Performance
Standard for onsite stormwater management
New and updated BMPs and requirements in the 2012 Ecology Manual
Adopt the 2012 Ecology Manual or an equivalent stormwater manual, or update the Auburn SWMM
consistent with the updated minimum technical requirements in Appendix 1 of the Permit.
Establish the legal authority, through the approval process for new development and redevelopment,
to inspect and enforce maintenance standards for private stormwater facilities approved under the
provisions of this section that discharge to the Permittee’s MS4.
Ensure that the program includes provisions to verify adequate long-term operations and
maintenance (O&M) of stormwater treatment and flow control BMPs/facilities that are permitted
and constructed pursuant to the City’s permitting process under the Permit.
Inspect all permanent stormwater treatment and flow control BMPs/facilities and catch basins in
new residential developments every 6 months until 90 percent of the lots are constructed (or when
construction is stopped and the site is fully stabilized) to identify maintenance needs and enforce
compliance with maintenance standards as needed.
Comply with inspection requirements of this section by achieving at least 80 percent of scheduled
inspections.
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Review, revise, and make effective its local development-related codes, rules, standards, or other
enforceable documents to incorporate and require LID principles and LID BMPs.
The intent of the revisions shall be to make LID the preferred and commonly used approach to
site development. The revisions shall be designed to minimize impervious surfaces, native
vegetation loss, and stormwater runoff in all types of development situations. Permittees shall
conduct a similar review and revision process, and consider the range of issues, outlined in the
following document: Integrating LID into Local Codes: A Guidebook for Local Governments
(Puget Sound Partnership, 2012).
Submit a summary of the results of the review and revision process described above with the Annual
Compliance Report due no later than March 31, 2017. This summary shall include, at a minimum, a
list of the participants (job title, brief job description, and department represented); the codes, rules,
standards, and other enforceable documents reviewed; and the revisions made to those documents
that incorporate and require LID principles and LID BMPs. The summary shall include existing
requirements for LID principles and LID BMPs in development-related codes. The summary shall be
organized as follows:
a. Measures to minimize impervious surfaces
b. Measures to minimize loss of native vegetation
c. Other measures to minimize stormwater runoff
Participate in watershed-scale stormwater planning if a watershed is partially or fully located in Auburn
is selected by a Phase I county for watershed-scale stormwater planning under condition S5.C.4.c of
the Phase I Municipal Stormwater General Permit. (The City may be required to provide data,
mapping, and “monitoring locations,” and participate in “development of strategies to prevent future
and address existing impacts”.)
6.2 Current Compliance Activities Applicable to New Requirements
The City currently has activities and programs that meet many of the Permit requirements summarized
above. The current compliance activities associated with the above Permit requirements include:
The City has existing programs, codes, and standards that address many of the Permit requirements
for management of stormwater runoff from development, redevelopment, and construction sites.
The City reviews all stormwater site plans for proposed development. The City currently implements
the Auburn SWMM as an equivalent manual approved by Ecology.
The City has a site planning process for BMP selection and design criteria.
The City inspects all permitted development sites during construction and after construction.
The City clearly identifies the party responsible for O&M and requires long-term O&M of permitted
facilities and BMPs.
The City records inspections and enforcement actions by staff.
6.3 Compliance Policy Issues
Compliance with Permit Condition S5.C.4 will require the City to address the following key issues:
See Section 1.3 for discussion of key policy issues related to controlling runoff from new
development, redevelopment, and construction sites, including:
LID principles assessment, policy development, implementation, and reporting
LID infeasibility criteria and competing needs
Updates to SWMM or adoption of an alternative manual
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Code revisions
LID facility inspections
6.4 Recommended Actions to Maintain Future Compliance
Auburn has a well-developed program to help reduce stormwater runoff from new development,
redevelopment, and construction sites but significant updates will be necessary to maintain compliance
with new Permit requirements. Table 6-1 lists activities and time frames for the City to comply with new
Permit conditions related to control of runoff from new development, redevelopment, and construction
sites.
Table 6-1. Controlling Runoff from Development, Redevelopment, and Construction Sites
Task ID Task description Lead Support Compliance time frame
CTRL-3
Begin process to update City codes related to
controlling runoff from new development,
redevelopment, and construction site
projects (e.g., ACC 13.48 and planning-
related code sections: see Table 6-2 for
potentially affected City codes).
Utilities Engineering,
Building Division City Attorney December 31, 2016
CTRL-4
Begin a process to develop and adopt a
stormwater management manual equivalent
to the 2012 Ecology Manual.
Utilities Engineering
Community Development
and Public Works, City
Attorney
December 31, 2016
CTRL-5
Begin process to review, revise, and make
effective development-related codes, rules,
standards, or other enforceable documents
to incorporate and require LID principles and
LID BMPs. See Table 6-2 for potentially
affected City documents.
Utilities Engineering,
Planning Division
Permit Center,
Development Engineering,
City Attorney
December 31, 2016
CTRL-6 Implement updated codes, manual, and
standards.
Utilities Engineering,
Permit Center,
Development
Engineering, Planning
M&O After adoption, no later
than January 1, 2017
CTRL-7
Consider updates to public outreach and
communications materials for property
owners related to increased potential for
annual stormwater facility inspections on
private property.
Utilities Engineering Permit Center Ongoing
CTRL-8
Update inspection requirements for
residential developments (inspect every 6
months until 90% buildout).
Construction Inspectors None Ongoing
CTRL-9
Complete and document 80% of scheduled
O&M and construction inspections to
demonstrate compliance.
Utilities Engineering,
Construction Inspectors,
Building Inspectors,
M&O
None Ongoing
CTRL-10
Compile and submit a summary of the LID
review and revision process described in
CTRL-5
Utilities Engineering Planning Division March 31, 2017
Note: Task ID numbering and work items include and build on tasks currently included in the 2014 SWMP.
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Table 6-2 is adapted from the Phase II Gap Analysis technical memorandum dated February 28, 2014. It
includes assessments of City codes, standards, and other documents that may require update to comply
with updated Permit requirements related to control of runoff from new development, redevelopment,
and construction sites. In general, the LID principles requirements may affect provisions of
Comprehensive Plan goals and policies, land use and development code provisions, and development
standards.
Table 6-2. Recommended City Code and Document Updates (Development-Related)
City document Sections/descriptions Comments
Auburn City Code (ACC) sections
Title 1 General Provisions Chapter 1.20 Right of Entry for Inspection
Chapter 1.25 Civil Penalties for Violations
These sections were reviewed because of their relationship to
facility inspection and enforcement.
1.20: The language in this section appears to be adequate. The
City may wish to review further in the context of a broader
strategy/approach for conducting inspections of LID facilities
on private property.
1.25: No changes appear necessary.
Title 2 Administration and
Personnel
Chapter 2.25 Planning and Development
Department
Chapter 2.27 Public Works Department
These sections were reviewed because of their potential
relationship to stormwater program implementation.
No changes appear necessary.
Title 8 Health and Safety Chapter 8.20 Vegetation
This section was reviewed because of its potential relationship
to maintenance of vegetation in private stormwater facilities.
The City will likely address O&M requirements for private
stormwater facilities elsewhere; no apparent change is required.
Title 12 Streets, Sidewalks and
Public Works Chapter 12.04 Public Works Construction 12.04.010: Update SWMM reference, once the updated
manual is developed.
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Table 6-2. Recommended City Code and Document Updates (Development-Related)
City document Sections/descriptions Comments
Title 13 Water, Sewer and
Public Utilities
Chapter 13.41 Utility Systems Development
Charge
Chapter 13.48 Storm Drainage Utility
13.41.010: Consider updating definitions and usage of
impervious surfaces and LID.
13.41.050: Consider updating policies regarding and
description of credits available for LID. With LID now generally
required, credits may no longer be appropriate.
Numerous revisions are identified throughout Chapter 13.48.
13.48.010: Permit included updates to definitions of illicit
connection, illicit discharge, hard and impervious surfaces, and
other terms. Consider matching Permit language. Update
SWMM reference.
13.48.100.G: Equivalent service units are currently determined
based on impervious surface area. With the Permit now focused
on “hard surfaces,” consider updating the City’s approach for
consistency. Could impact rate ordinance. Optional and
potentially low priority.
13.48.180.A: Inspection access language appears adequate.
13.48.180.B: Review to confirm that this language is adequate
to enforce O&M of private stormwater facilities.
13.48.180.D: Code identifies 50% buildout; the Permit now
specifies 90%. Update accordingly.
13.48.210.A: Review and consider matching updated language
in Permit related to illicit discharges.
13.48.225: See following:
• MR 2: Add new element “Protect Low Impact
Development BMPs”.
• MR 5: Make significant revisions in accordance with
Permit LID changes.
• MR 6 an 7: Code language is adequate, but changes
in SWMM will be required (e.g., thresholds in terms of
hard surface area, Basic and Enhanced Treatment
requirements).
• MR 8: Wetlands guidance in Ecology Manual changed
significantly (Guide Sheets 1–3, Appendix I-D).
Review further to confirm adequacy of ACC language
13.48.230.B: Update thresholds from impervious to hard
surfaces.
13.48.435: Consider whether modified requirements for single-
family home/small LID facilities are needed.
Title 14 Project Review All
This title was reviewed because of its relationship to the project
review and approval process.
The title generally outlines how projects must be reviewed
consistent with specific requirements found in other sections.
No changes appear necessary.
Title 15 Buildings and
Construction
Chapter 15.07 Construction Administration
Code
Chapter 15.68 Flood Hazard Areas
These sections were reviewed because of their relationship to
development and construction.
15.07.090: No changes appear necessary.
15.68: Permit changes (in particular LID principles) have the
potential to impact or be impacted by flood zone-related code.
The sections appear to be general enough to avoid revision but
their content should be reviewed to ensure that it aligns with the
City’s desired approach to LID.
Section 6 Auburn NPDES Compliance Work Plan
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Table 6-2. Recommended City Code and Document Updates (Development-Related)
City document Sections/descriptions Comments
Title 16 Environment Chapter 16.10 Critical Areas
These sections were reviewed because the Permit changes (in
particular LID principles) have the potential to impact code
related to critical areas.
As part of the process for determining the City’s approach to LID
implementation, consider how LID policies will relate to critical
areas, critical areas mapping, buffers and setbacks, and other
considerations.
Title 17 Land Adjustments
and Divisions All
This title was reviewed because of its relationship to land use
and development.
The title is not impacted by the technical changes to the Permit,
but may be impacted in various sections by the LID principles
requirement, consistent with the LID approach to be determined
by the City. LID principles-related updates could represent a
major work effort.
Title 18 Zoning All
This title was reviewed because of its relationship to land use
and development.
The title is not impacted by the technical changes to the Permit,
but may be impacted in various sections by the LID principles
requirement, consistent with the LID approach to be determined
by the City. LID principles-related updates could represent a
major work effort.
Potential issues to consider include:
• Landscaping requirements and native vegetation
preservation
• Impervious surface limitations/standards
• Roads and parking standards
• Site plan review criteria
City of Auburn documents
Surface Water Management
Manual (SWMM)
The City developed and uses the SWMM as
its primary mechanism for implementing
state stormwater regulations related to new
development and redevelopment
The SWMM was developed as an equivalent to the Ecology
Manual during the previous Permit cycle. Updates to the Permit
and the Ecology Manual will trigger corresponding updates in
the SWMM in order to maintain equivalency. This includes
changes to the Minimum Requirements, BMPs (for construction,
source control, and facilities), and design guidance and
practices documented in the SWMM. Because the SWMM is
based on the Tacoma Manual, updates to the SWMM may be
able to build on corresponding updates to the Tacoma Manual.
Potential updates to the SWMM represent a major effort for City
staff.
Engineering Design Standards
Chapter 1 General Information
1.02 Engineering Handouts
1.03 Deviations from Standards
1.02.1.2 Update the referenced guidance and permitting
handouts and create new handouts as necessary. Also see
related discussion on Permit Application Checklists below.
1.03 Consider whether updates to the deviation from standards
section are needed based on the City’s implementation
approach for LID and the associated identification of
infeasibility criteria for LID.
Chapter 2 Plan Approval Process
2.02 Review and Approval Process
Depending on the City’s approach to implementing LID,
consider including a submittal requirement related to
infiltration testing. This testing may already be adequately
covered by existing requirements.
Auburn NPDES Compliance Work Plan Section 6
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Table 6-2. Recommended City Code and Document Updates (Development-Related)
City document Sections/descriptions Comments
Chapter 4 Report Preparation Requirements
4.02 Report Types
Depending on the City’s approach to implementing LID,
consider expanding on the existing requirement to conduct
infiltration testing and report on the results as part of the
geotechnical report. An alternative approach for smaller
projects needing to implement LID may be desirable (short of a
full geotechnical report, perhaps).
Chapter 5 TESC, Clearing and Grading
5.02 Land Clearing
5.05 Construction Sequence
5.02 Clearing requirements could be affected by City’s
approach to LID and the Permit requirement to minimize native
vegetation loss.
5.05 Consider how LID requirements may affect or need to be
included in construction sequence requirements.
Chapter 6 Storm Drainage This section has been replaced with a reference to the SWMM.
No changes necessary.
Chapter 10 Streets
10.05 Sidewalks
10.06 Bikeways
10.07 Pavement Design
10.08 Landscaping
10.05–10.07 Consider allowing and including specifications
for pervious pavement design if determined to be an acceptable
alternative for sidewalk, bikeway, and/or roadway construction.
10.08 Consider how landscaping elements could be integrated
with or serve a dual purpose for storm drainage.
Updates other than those noted may be needed to align with
potential transportation-related strategies as part of the City’s
broader LID approach.
Chapter 11 Site Design Site design requirements (e.g., zoning, land use) refer to more
specific requirements in the ACC. No updates appear necessary.
Definitions The City may want to consider updating definitions consistent
with relevant Permit definitions.
Engineering Construction
Standards
Special provisions and standard details for
construction.
This document appears unaffected by Permit updates. The City
communicated during workshops the intention to address
stormwater BMPs through the SWMM, and not through standard
specification and details.
Permit Application Checklists and
related guidance documents
Checklists and guidance materials for City
permit applicants: (see City Forms Web site)
These documents were reviewed because of their relationship to
permits and project review.
City forms such as the Residential Permit Submittal Checklist
and Commercial Building Permit Checklist will require update to
align with the new Permit requirements and the City’s approach
to LID.
Section 6 Auburn NPDES Compliance Work Plan
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Table 6-2. Recommended City Code and Document Updates (Development-Related)
City document Sections/descriptions Comments
City Comprehensive Plan
The Plan sets future, long-range goals and
summarizes major City policies and
proposals.
This document was reviewed because of its relationship to
policy determination and implementation. While most of the
plan will be unaffected by Permit changes, updates may be
desirable in the following chapters to better align with the new
Permit language and the City’s determined LID approach (in
particular, potential changes to zoning, land use, or other City
policies that may result from requirements to preserve native
vegetation and trees and to minimize impervious surfaces):
3. Land Use
5. Capital Facilities
7. Transportation (refers out to a separate Transportation
Comprehensive Plan)
9. Environment
Broadly, the Permit requires Permittees to minimize impervious
surfaces and minimize the loss of native vegetation. The City
should consider how those principles can be incorporated into
the goals of the Plan.
More specifically, several items and sections were flagged
during review for additional scrutiny:
• Page 3-28: Note indicating elimination of stormwater
improvements as incentive for redevelopment may
not be consistent with state regulations.
• Page 5-10 (CF-42, 43): Review these two policies
related to stormwater facilities on private property
and regional facilities in light of new focus on LID and
distributed stormwater infrastructure. Other policies
in this section do not appear to require update, but
the City should review to confirm.
• Page 9-2 (EN-2): Check whether this reference to the
Ecology Manual is intentional, or should be replaced
with a reference to the Auburn SWMM.
• Page 9-4 (EN-14): Check whether this reference to
the Ecology Manual is intentional, or should be
replaced with a reference to the Auburn SWMM.
• Page 9-22 (EN-124): Consider updating language in
light of new LID requirements (no longer only
“encouraged”).
• Page 15-4: Update the description of the
Comprehensive Drainage Plan consistent with the
current update in progress.
Coordination with the Comprehensive Storm Drainage Plan
update is recommended.
Auburn NPDES Compliance Work Plan Section 6
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Table 6-2. Recommended City Code and Document Updates (Development-Related)
City document Sections/descriptions Comments
Comprehensive Storm Drainage
Plan
The Plan guides the City’s Stormwater
Drainage utility with respect to future
activities and improvements for the
stormwater drainage system.
This document was reviewed because of its relationship to
policy determination and implementation.
While most of the plan will be unaffected by Permit changes,
updates may be desirable throughout the Plan to better align
with the new Permit language and the City’s determined LID
approach.
The following specific areas were flagged for update:
• Figure ES-2: Update timeline for Permit compliance
• Section 2.2: Describe future updates to City codes
and standards
• Section 2.3.2: Review and revise NPDES Permit
description
• Section 3.2: Review how levels of service will be
affected by new LID focus and implementation
• Sections 4.1.6/4.1.7: Review how these sections
related to geology, soils, and groundwater affect or
are affected by LID requirements and feasibility
criteria
• Section 4.1.8.3: Update section on development
regulations and drainage design standards
• Section 7.3: Update section on NPDES compliance
programs, including Figure 7-2 (matches Figure ES-2)
Coordination with the City Comprehensive Plan update is
recommended (e.g., policies CF-40, EN-12, and EN-17).
The Comprehensive Storm Drainage Plan should indicate
coordination of maintenance activities with a schedule
developed to comply with Ecology requirements and asset
criticality.
Shoreline Master Program
The Program provides policies and
regulations to govern development and other
activities along the City’s shorelines. It
includes guidance related to critical areas,
buffers, and general stormwater/LID
management and goals.
Discussion related to stormwater appears to be general and
unaffected by the detailed changes to the Permit.
To the extent that the City’s LID implementation process
(including policies to preserve native vegetation and minimize
impervious surfaces) affects critical areas and buffer
requirements, updates to those elements could be needed. No
immediate changes were identified.
Downtown Urban Center Design
Standards
The Design Standards outline architectural
guidelines for downtown development. This
includes guidelines for elements like parking
spaces and lots, driveways, and pedestrian
sidewalks.
To the extent that these parking and access elements are
affected by potential land use, zoning, and transportation
changes made during the City’s LID implementation process,
the Design Standards may need to be updated.
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Section 7
Municipal Operations and
Maintenance
This section summarizes new Permit requirements for Municipal Operations and Maintenance, current
compliance activities that are applicable to the new requirements, and recommended actions to
maintain future compliance.
7.1 New Permit Requirements
Section S5.C.5 of the Permit requires the City to:
Update maintenance standards as necessary to meet updated Permit requirements
Inspect all catch basins and inlets owned or operated by the City at least once no later than August
1, 2017, and every 2 years thereafter
Implement practices, policies, and procedures to reduce stormwater impacts associated with runoff
from all lands owned or maintained by the Permittee, and road maintenance activities under the
functional control of the Permittee (added buildings, parks, open spaces, road rights-of-way,
maintenance yards, and stormwater facilities to Permit list of Permittee lands)
7.2 Current Compliance Activities Applicable to New Requirements
The City currently has activities and programs that meet many of the requirements of Section S5.C.5 of
the Permit. Current activities and programs include the following:
The City operates an O&M program intended to minimize pollutant runoff from municipal operations.
The City conducts and records the inspections and cleaning of City-owned and -permitted
stormwater facilities and elements of the collection system (e.g., catch basins, outfalls).
7.3 Recommended Actions to Maintain Future Compliance
Auburn has a well-developed municipal stormwater system O&M program to minimize water quality
impacts from municipal operations. Some updates to programs and activities will be necessary to
maintain compliance with the new Permit requirements. Table 7-1 lists activities and time frames for the
City to comply with new Permit conditions related to municipal operations and maintenance.
Section 7 Auburn NPDES Compliance Work Plan
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Table 7-1. Municipal Operations and Maintenance
Task ID Task description Lead Support Compliance time
frame
MOM-4
Review City maintenance standards (SWPPPs, SOPs, SWMM
BMPs, City inspection schedules/Cartegraph tracking, other)
relative to new requirements in S5.C.5, including new inspection
and cleaning requirements and additional City lands identified.
Update if needed.
SWPPPs appear unlikely to require update.
Utilities Engineering
M&O, Parks,
Building
Maintenance,
IT
December 31, 2016
MOM-5
Continue inspection and cleaning of catch basins currently
conducted. Meet at a minimum one inspection of each catch
basin by August 1, 2017, and at least once every 2 years
thereafter, or justify a longer cycle (see below).
The City is currently inspecting on a 3-year rotating basis.
M&O Utilities
Engineering
August 1, 2017
Every 2 years thereafter
MOM-6
If desired, use maintenance records to justify an alternative catch
basin inspection frequency (e.g., every 3 years). If this approach is
selected, compile and submit maintenance records to Ecology.
Utilities Engineering M&O Optional
Note: Task ID numbering and work items build on tasks currently included in the 2014 SWMP.
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Section 8
TMDL Compliance
This section summarizes new Permit requirements for total maximum daily load (TMDL) compliance,
current compliance activities that are applicable to the new requirements, and recommended actions to
maintain future compliance.
8.1 New Permit Requirements
The Permit contains two sections that address TMDL requirements: Section S7 and Appendix 2. Section
S7 received minor updates, while Appendix 2 was entirely revised from the prior version.
Appendix 2 contains TMDL requirements for specific water bodies and Permittees, including the City of
Auburn. The City has required actions identified for the Puyallup Watershed Water Quality Improvement
Project, which is a fecal coliform TMDL for portions of the Puyallup River Watershed. The City is
specifically required to:
Beginning no later than October 1, 2013, conduct twice monthly wet weather sampling of
stormwater discharges to the White River at Auburn Riverside High School to determine if specific
discharges from Auburn’s MS4 exceed the water quality criteria for fecal coliform bacteria.
o Data shall be collected for one wet season.
o Data shall be collected in accordance with an Ecology-approved QAPP.
o Data collected since EPA TMDL approval can be used to meet this requirement.
For any of the outfalls monitored above showing discharges that exceed water quality criteria for
primary contact recreation: designate those areas discharging via the MS4 of concern as high
priority areas for illicit discharge detection and elimination efforts and implement the schedules and
activities identified in S5.C.3 of the Western Washington Phase II permit for response to any illicit
discharges found beginning no later than August 1, 2014.
Install and maintain pet waste education and collection stations at municipal parks and other
Permittee owned and operated lands adjacent to streams. Focus on locations where people
commonly walk their dogs.
8.2 Current Compliance Activities Applicable to New Requirements
The City has completed required wet weather monitoring of discharges to the White River.
The City maintains pet waste education and collection stations at municipal parks and other public lands
adjacent to the White River and its tributaries.
8.3 Recommended Actions to Maintain Future Compliance
Table 8-1 lists activities and time frames for the City to comply with new Permit conditions related to
TMDL compliance. The City’s 2014 SWMP contains current tasks related to TMDL compliance. The
tasks shown in Table 8-1 build on those current tasks identified in the SWMP.
Section 8 Auburn Phase II Compliance Work Plan
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Table 8-1. TMDL Compliance
Task ID Task description Lead Compliance time frame
TMDL-2
Maintain pet waste education and collection
stations at municipal parks and other public lands
adjacent to the White River and its tributaries.
Parks
Department Ongoing
TMDL-3
If triggered by wet weather monitoring results,
designate areas contributing to water quality
exceedances as high priority areas for illicit
discharge detection and elimination efforts;
implement permit-required responses for any
illicit discharges found.
Utilities
Engineering August 1, 2014
Note: Task ID numbering and work items build on tasks currently included in the 2014 SWMP.
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Section 9
Monitoring and Assessment
This section summarizes new Permit requirements for Monitoring and Assessment, current compliance
activities that are applicable to the new requirements, and recommended actions to maintain future
compliance.
9.1 New Permit Requirements
The Permit (Section S8) was substantially revised from the prior version. Permittees are required to:
Conduct Status and Trends Monitoring and Effectiveness Studies, or pay annually into a collective
fund to implement monitoring through the Regional Stormwater Monitoring Program (RSMP).
Auburn’s annual payment will be $45,096.
Pay into the RSMP to implement the RSMP Source Identification Information Repository (SIDIR).
Auburn’s annual payment will be $2,614.
Provide the following monitoring and/or assessment data in each Annual Compliance Report:
A description of any stormwater monitoring or studies conducted by the City during the reporting
period. If stormwater monitoring was conducted on behalf of the City, or if studies or
investigations conducted by other entities were reported to the City, a brief description of the
type of information gathered or received shall be included in the Annual Compliance Report.
9.2 Current Compliance Activities Applicable to New Requirements
The City committed in 2013 to make annual payments into the Ecology monitoring programs, in lieu of
running an independent monitoring program. Program payments are planned by the City in compliance
with annual due dates.
9.3 Recommended Actions to Maintain Future Compliance
Table 9-1 lists activities and time frames for the City to comply with new Permit conditions related to
monitoring and assessment. The City’s 2014 SWMP contains task MNTR-1, which identifies annual
payments into the Ecology monitoring programs. Because the SWMP already captures relevant new
activities for monitoring, the work plan mirrors the SWMP.
Table 9-1. Monitoring and Assessment
Task ID Task description Lead Compliance time frame
MNTR-1
Pay $47,710 annually into the RSMP collective
fund for implementation of Status and Trends
Monitoring, Effectiveness Studies, and the Source
Identification Information Repository.
Utilities
Engineering
Annual payment due by
August 15, starting in 2014
Note: Task ID numbering and work items build on tasks currently included in the 2014 SWMP.
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Section 10
Limitations
This document was prepared solely for the City of Auburn in accordance with professional standards at
the time the services were performed and in accordance with the contract between the City of Auburn
and Brown and Caldwell dated October 17, 2013. This document is governed by the specific scope of
work authorized by the City of Auburn; it is not intended to be relied upon by any other party except for
regulatory authorities contemplated by the scope of work. We have relied on information or instructions
provided by the City of Auburn and other parties and, unless otherwise expressly indicated, have made
no independent investigation as to the validity, completeness, or accuracy of such information.
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Section 11
References
Western Washington Phase II Municipal Stormwater Permit, Washington State Department of Ecology, effective date
August 1, 2013.
Stormwater Management Manual for Western Washington, Washington State Department of Ecology, August 2012.
Integrating LID Into Local Codes: A Guidebook for Local Governments, AHBL for the Puget Sound Partnership, July
2012.
Illicit Discharge Detection and Elimination: A Guidance Manual for Program Development and Technical
Assessments, Center for Watershed Protection and Robert Pitt (University of Alabama), October 2004.
Auburn NPDES Compliance Work Plan
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Attachment A: Permit Compliance Schedule (Draft)
(Courtesy Cities of Covington and SeaTac)
TASKS
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A1 SWMP Develop & Implement
A2 SWMP Plan Annually Updated
A3 a.Track Costs or Estimated Costs
b.Track Inspections, Enforcements & Public Educ. Activities
A4 Continue Implementation of Exising Programs
A5 a.Include Coord. Mech. wi Other Entities (If Applicable)
b.SWMP Includes Internal Coordination Mechanisms
C1 a.Public Education & Outreach (Local or Regional)
b Create Stewardshp Opportunities
c Measure Understanding & Adoption of Behaviors
C2 a.Public Involvement & Participation (Create opport.)
b.SWMP & Annual Report Website Posting
C3 Illicit Discharge Detection and Elimination
a.Ongoing Stormwater Mapping - periodically update
a.v Map All New Connections Since February 16, 2007
b.IDDE Ordinance Update
c.Illicit Discharge Detection & Elimination Program
c.i Field Screen 40% of MS4 12/31/17- 12% yrs thereafter
c.i Document Field Screen Methodology in Annual Report
c.ii Publically List Phone #'s for Reporting Spills
c.iii Ongoing Training all Muni. Field Staff - Lvl B (Tracked)
c.iv IDDE Education
d
e.Ongoing Training IDDE Staff - Lvl A (Tracked)
C4 Construction Site Runoff Program
a.Update Construction Site Runoff Ordinance
a.i Adopt Appendix 1 or Approved Phase I Program
a.i Adopt Variance Criteria Equiv. to Appendix 1
a.ii Site Plan & BMP Select per Append 1 or Approved Ph I
a.iii Ord./ Reg. Mech. Giving Legal Authority to Inspect
b.Implement Permit Process / Plan Review & Inspect. wi
new thresholds
b.i Review All Stormwater Site Plans
b.ii Pre-Con Site Inspection
b.iii Inspect All Sites for Erosion and Sediment Controls
b.iii Enforce ESC as Necessary
b.iv Final ESC Inspection
b.iv Maintenance Plan for New Facilities (Bond Program)
b.iv Enforce Maintenance Plan (Bond Program)
b.v Minimum 80% Compliance wi Inspect. Requirements
b.vi Enforcement Strategy
c.O&M for Private Stormwater Facilities & BMPs
- Long Term Mnt - Treatment & Flow Control BMPS
c.i Enforce. Mech. Identifying Responsibilities for O&M
c.ii Est. Maint. Standard = to Ch.4 Vol.V of 12' SMMWW
c.iii Annual Inspection of Private Facilities Aprvd after 2/15/10
c.iv
Inspect Bonded Resid. Facilities Every 6 Months until
90% of lots constructed (or when construction stops and
sites are fully stabilized)
c.vi Compliance = records + 80% scheduled inspections Reduced standard frm 95%
c.vi Perform Timely Maintenance
c.vii Track Inspections, Enforcements etc. (All Notices)
d.Make NOI for Const. & Industrial Site Avail. & Enforce
Local Regs on NPDES Const. Sites
e.Train All Applicable Staff on Above Activities (Track)
f.Low Impact Development
f.i.Incorporate LID into Codes, Rules Stnds & Enf. Docs
Making LID Prefered/Commonly Used Approach
f.ii Submit Summary of Results of LID Update Process
g.Watershed Scale Stormwater Planning wi Phase Is Not Applicable - SeaTac Watersheds not selected
C5 O&M Program (for Municipally Owned or Operated)
a.Update Maint. Stnds = to Ch.4 Vol.V of 12' SMMWW
a.ii Perform Timely Maintenance
b.Annually Inspect All Treatment & Flow Cntrl. Facilities
c Spot Check Inspections After Major Storms (10 yr 24 Hour)
d.Catch Basin Insp. & Mnt. - All by 8/17 - then every 2 yrs 2 year schedule
e.Ensure 95% compliance for O&M inspections
f.Establish & Implem. Practices to Reduce Impacts
g.O&M Training Program (Train to Standards)
i SWPPPs for All Heavy Equip. Mnt. & Storage Yards
j Track Maint. & Repair Activities Identified Above
A Monitoring & Assessment - Submit Stormwatwer Studies
B1 Status & Trends Monitoring Notification & Contribution Notification to DOEAnnual Payments Start
C1 Effectiveness Monitoring Notification & Contribution Notification to DOEAnnual Payments Start
D Source Ident. & Diagnostic Monitoring (Info. Repository)Annual Payments Start
A1 Annual Compliance Report
G1
8
CH
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S9
WWESTERN WASHINGTON PHASE II MUNICIPAL STORMWATER PERMIT IMPLEMENTATION SCHEDULE
2013 2014 2015 2016 2017 2018
S5
S8
Apply for permit renewal
LEGEND: Effective & Expiration Dates of Permit Ongoing Requirement Permit Deadline
G1
8
Auburn NPDES Compliance Work Plan
1
Use of contents on this sheet is subject to the limitations specified at the end of this document.
2014 Auburn NPDES Compliance Work Plan.docx
Attachment B: Compliance Effort Estimate
Memorandum
Limitations:
This document was prepared solely for the City of Auburn in accordance with professional standards at the time the services were performed and in
accordance with the associated contract between the City of Auburn and Brown and Caldwell. This document is governed by the specific scope of
work authorized by the City of Auburn; it is not intended to be relied upon by any other party except for regulatory authorities contemplated by the
scope of work. We have relied on information or instructions provided by the City of Auburn and other parties and, unless otherwise expressly
indicated, have made no independent investigation as to the validity, completeness, or accuracy of such information.
701 Pike Street, Suite 1200
Seattle, Washington 98101
T: 206.624.0100
F: 206.749.2200
Prepared for: City of Auburn
Project Title: NPDES Compliance Assistance
Project No.: 145125
Memorandum
Subject: Effort Estimate
Date: July 2, 2014
To: Chris Thorn, Water Quality Program Coordinator
From: Patrick Weber, Project Manager
Copy to: Tim Carlaw, Storm Drainage Engineer
Prepared by: Patrick Weber, P.E.
Kirsten Wood, EIT
Reviewed by: Damon Diessner
Memorandum
1
Effort Estimate Memo FINAL.docx
The Department of Ecology issued an updated National Pollutant Discharge Elimination System (NPDES)
Phase II Municipal Stormwater Permit (Permit) on August 1, 2013. As a Phase II Permittee, the City of
Auburn (City) must update its codes and policies to comply with the new Permit requirements. The City began
this process by completing a gap analysis to identify existing City codes and policies that may be affected by
the Permit.
Based on discussions with City staff, Brown and Caldwell (BC) estimated the additional efforts required by
the City to address potential gaps identified in the gap analysis.
Estimated resources are listed in terms of full-time employees (FTE), limited-term employees (LTE), materials
and equipment, and fees (all changes relative to the 2013 baseline year).
The following additional resource needs have been identified, relative to a 2013 baseline:
• Annual fee to participate in Ecology’s monitoring programs is $47,710 USD
• In 2014, 1.05 FTEs, 0.7 LTE, and equipment, including 1 stormwater inspector
• In 2015, 3.05 FTEs, 1.7 LTEs, and equipment, including 1 stormwater inspector and 2 M&O field staff
• In 2016, 3.3 FTEs, 2.55 LTEs, and equipment, including 1 stormwater inspector and 2 M&O field staff
• In 2017, 5.65 FTEs, 0 LTEs, and equipment, including 2 stormwater inspectors, 2 M&O field staff, and 1
LID facility inspector
• In 2018, 5.9 FTEs, 0 LTEs, and equipment, including 2 stormwater inspectors, 2 M&O field staff, and 1
LID facility inspector
Table 1 includes the estimated additional effort, costs, materials and timing for each Permit compliance
activity. The numbering in the first column corresponds to the attached schedule table, which includes the
estimated additional effort required each year from 2014 to 2018.
Table 1. Estimated Resources Required for Compliance
Schedule table
reference number
Description Duration
1.A City permit review staff to update public guidance materials
and checklists to align with the new City/NPDES Permit
requirements.
One-time effort in 2016 once updates to City requirements are
clarified, early enough to be able to inform the public in advance
of upcoming/new requirements.
[0.1 LTE one-time in 2016]
1.B Additional staff effort to conduct permit application reviews.
Additional staff effort will be driven by more complex,
iterative permitting processes for LID, including site-specific
LID feasibility review and determinations.
Ongoing effort starting in 2017, potentially ramping up with long
term growth and an increase in permit applications.
[0.25 FTE ongoing starting in 2017]
2.A Additional staff inspector(s) focused on stormwater
elements. The position could require additional and
specialized training in stormwater management, water
quality, erosion control and LID installation requirements.
Ongoing effort starting in 2014. Includes training and
coordinating responsibilities among inspector groups for
different project types. Additional inspector added in 2017 as
new LID requirements become active, potentially continuing to
ramp up over time.
[1.0 FTE from 2014 to 2016, increasing to 2.0 FTEs ongoing
starting in 2017]
Effort Estimate Memorandum
2
Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Effort Estimate Memo FINAL.docx
Table 1. Estimated Resources Required for Compliance
Schedule table
reference number
Description Duration
2.B Define, coordinate and update procedures and
responsibilities among inspector groups.
One-time effort should occur in 2014 before or coinciding with
filling additional inspector position to ensure that all required
tasks are covered among the roles.
[0.1 LTE one-time in 2014]
3.A Define and organize LID asset classification, and
coordinate/update maintenance tracking methods.
Additional efforts to track and record maintenance of
stormwater assets.
One-time setup of asset management systems and protocols
should occur in 2016. Ongoing tracking will continue and
potentially ramp up with increase in development with tracked
assets.
[0.25 FTE in 2016 decreasing to 0.1 FTE ongoing starting in
2017]
3.B Develop procedures for public LID facility maintenance and
oversight of private facilities.
One-time effort should occur in 2016 so procedure is defined
before 12/31/2016 deadline.
[0.25 LTE one-time in 2016]
3.C Inspect, clean and maintain catch basins at frequencies as
required by the Permit. New hire(s) will require a vehicle and
field equipment.
Ongoing effort starting in 2015.
[2 FTE ongoing starting in 2015]
3.D Maintain publicly owned LID facilities and other stormwater
assets. Obtain required equipment for facility maintenance.
Ongoing effort starting in 2017, with potential increases over
time due to future growth.
[0.25 FTE in 2017 increasing to 0.5 FTE ongoing starting in
2018]
4.A Update public education and outreach materials to include
additional target audiences, evaluate program effectiveness,
and conduct regional coordination.
Ongoing effort starting in 2014.
[0.05 FTE ongoing starting in 2014]
5.A Update or adopt Stormwater Manual to meet requirements. One-time effort ramping up in 2015 and completed in 2016.
[0.5 LTE in 2015 increasing to 1.0 LTE in 2016]
5.B Develop City planning methods and update Code to meet
new Permit requirements for stormwater, including new
runoff control requirement thresholds, BMP performance
standards and LID requirements.
One-time effort ramping up in 2014 and completed in 2016.
[0.5 LTE in 2014 increasing to 1.0 LTE in 2015 and 2016]
5.C Inspect new LID facilities regularly and purchase and
maintain any associated field instruments required to
perform inspections.
Ongoing effort starting in 2017 and potentially increasing with
future development.
[1.0 FTE ongoing starting in 2017]
6.A Update City Comprehensive Plan related to implementation
of LID principles that could affect elements beyond
stormwater management implementation such as levels of
service, setbacks, zoning densities, etc.
One-time effort ramping up in 2014 and completed in 2016.
[0.1 LTE in 2014 increasing to 0.2 FTE in 2015 and 2016]
7.A Annual fees to participate in Ecology-run statewide
monitoring programs.
Annual fee starting in 2014.
[$47,710 annually starting in 2014]
For more details on each item, see attached spreadsheet
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YDetermine City's approach for SWMP effectiveness studies: either pay into the RSMP, or conduct independent studies. The City's annual payment amount to participate in the state program is listed as $28,182. The deadline to notify Ecology of the City's selected approach was December 1, 2013.August 15, 2014, and annually thereafter.Low/ MediumLow
38
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Comprehensive Storm Drainage Plan
C-1
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Appendix C: Hydrologic and Hydraulic Modeling and
Evaluation
Draft Technical Memorandum
Limitations:
This is a draft memorandum and is not intended to be a final representation of the work done or recommendations made by Brown and Caldwell. It
should not be relied upon; consult the final report.
This document was prepared solely for City of Auburn in accordance with professional standards at the time the services were performed and in
accordance with the contract between City of Auburn and Brown and Caldwell dated December 6, 2013. This document is governed by the specific
scope of work authorized by City of Auburn; it is not intended to be relied upon by any other party except for regulatory authorities contemplated by
the scope of work. We have relied on information or instructions provided by City of Auburn and other parties and, unless otherwise expressly
indicated, have made no independent investigation as to the validity, completeness, or accuracy of such information.
701 Pike Street, Suite 1200
Seattle, WA 98101
Phone: 206-624-0100
Fax: 206-749-2200
Prepared for: City of Auburn
Project Title: Comprehensive Storm Drainage Plan
Project No.: 145295
Draft Technical Memorandum
Subject: Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
Date: July 6, 2015
To: Tim Carlaw, Storm Drainage Engineer
From: Colleen O. Doten
Copy to: Lisa D. Tobin, Utilities Engineering Manager
Prepared by: Margaret Ales
Colleen O. Doten
Reviewed by: Nathan Foged
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
ii
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
Table of Contents
List of Figures ........................................................................................................................................................... iii
List of Tables ............................................................................................................................................................. iii
List of Abbreviations ................................................................................................................................................. iv
Section 1: Introduction ............................................................................................................................................. 1
1.1 Background ........................................................................................................................................................ 1
1.2 Purpose and Objectives ..................................................................................................................................... 1
Section 2: Model Development and Refinement ................................................................................................... 3
2.1 Model Development ........................................................................................................................................... 6
2.1.1 Updating Existing PCSWMM Models ................................................................................................ 6
2.1.2 Creating New WWHM Models ......................................................................................................... 11
2.1.3 Drainage Modeling using HEC-RAS................................................................................................. 11
2.2 Hydraulic Parameters ...................................................................................................................................... 11
2.3 Monitoring Data ............................................................................................................................................... 12
2.4 Climatic Data .................................................................................................................................................... 13
2.4.1 Precipitation ..................................................................................................................................... 13
2.4.2 Evaporation ...................................................................................................................................... 13
2.5 Horizontal and Vertical Datum ........................................................................................................................ 13
Section 3: Model Calibration and Evaluation ....................................................................................................... 15
3.1 BCDF Model Calibration................................................................................................................................... 15
3.1.1 Methodology ..................................................................................................................................... 15
3.1.2 Results .............................................................................................................................................. 17
3.2 P Subbasin Model Calibration ......................................................................................................................... 19
3.2.1 Methodology ..................................................................................................................................... 19
3.2.2 Results .............................................................................................................................................. 20
3.3 Model Evaluations............................................................................................................................................ 21
3.3.1 Level of Service ................................................................................................................................ 21
3.3.2 Flow Frequency Determination ....................................................................................................... 22
3.3.3 Drainage System Evaluation in the TT Subbasin ........................................................................... 23
Section 4: Annexation Area Desktop Evaluation .................................................................................................. 26
4.1 Methodology ..................................................................................................................................................... 26
4.1.1 Assessment Guidelines ................................................................................................................... 26
4.1.2 GIS-Based Methodologies ............................................................................................................... 26
4.2 Results .............................................................................................................................................................. 26
4.3 Summary and Recommendations .................................................................................................................. 31
Section 5: Summary ............................................................................................................................................... 32
References .............................................................................................................................................................. 33
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
iii
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
List of Figures
Figure 2-1. Modeled Subbasins, and Monitoring and Project Locations .............................................................. 5
Figure 3-1. BCDF model meter subbasins ............................................................................................................ 17
Figure 3-2. Existing-conditions profiles along 37th Street NW ditch for discharges
ranging from 1 to 10 cfs .................................................................................................................................. 24
Figure 3-3. Proposed-conditions profiles along 37th Street NW ditch for discharges
ranging from 1 to 10 cfs .................................................................................................................................. 25
Figure 4-1. Subbasin OO Potential Drainage System Gaps Identified during Desktop Evaluation ................... 29
List of Tables
Table 2-1. Subbasin Model Summary ..................................................................................................................... 3
Table 2-2. Model Data Description and Source ..................................................................................................... 6
Table 2-3. PCSWMM Subcatchment Model Attributes .......................................................................................... 8
Table 2-4. Initial Green Ampt Parameters ............................................................................................................ 10
Table 2-5. Curve Number Based on Auburn Land Use and Hydrologic Soil Group ............................................ 10
Table 2-6. SCS Model Parameters ........................................................................................................................ 11
Table 2-7. Manning’s Roughness Coefficients ..................................................................................................... 12
Table 2-8. Flow Monitoring Summary ................................................................................................................... 12
Table 2-9. Auburn Composite Precipitation Record for PCSWMM Models ......................................................... 13
Table 3-1. Final Hydrology Parameters Adjusted during Calibration ................................................................... 16
Table 3-2. BCDF Flow Monitoring Observed Data Model Calibration Summary ................................................. 18
Table 3-3. 17th and 21st Street Pond Level Data Model Calibration Summary ................................................ 19
Table 3-4. W Main Street Pump Station Observed Data Model Calibration Summary ...................................... 20
Table 3-5. Final Hydrology Parameters Adjusted during Calibration ................................................................... 21
Table 3-6. BCDF Subbasin Frequency Analysis Summary ................................................................................... 22
Table 3-7. P Subbasin Model Frequency Analysis Summary ............................................................................... 23
Table 4-1. Potential Annexation Area Storm Drainage Improvements ............................................................... 31
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
iv
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
List of Abbreviations
2009 Drainage Plan 2009 Comprehensive
Stormwater Drainage Plan
2015 Drainage Plan 2015 Comprehensive Storm
Drainage Plan
BC Brown and Caldwell
BMP best management practice
cfs cubic foot/feet per second
CHI Computational Hydraulics International
CIP Capital Improvement Program
City City of Auburn
CMP corrugated metal pipe
CN curve number
CPEP corrugated polyethylene pipe
DEM digital elevation model
DGM Digital Ground Model
DHI Danish Hydraulic Institute
EPA U.S. Environmental Protection Agency
ft foot/feet
ft3 cubic foot/feet
GIS geographic information system
gpm gallon(s) per minute
HDPE high-density polyethylene
HEC-RAS Hydrologic Engineering Center River Analysis
System
H&H hydrologic and hydraulic
hr hour(s)
HSPF Hydrological Simulation Program-Fortran
ID identifier
in. inch(es)
L length
LiDAR light detection and ranging
LOS level of service
MG million gallons
n/a not applicable
NAVD88 North American Vertical Datum of 1988
NGVD29 National Geodetic Vertical Datum of 1929
NOAA National Oceanic and Atmospheric
Administration
NRCS Natural Resources Conservation Service
PVC polyvinyl chloride
RCP reinforced concrete pipe
ROW right-of-way
RPVC reinforced polyvinyl chloride
SCADA supervisory control and data acquisition
SCS Soil Conservation Service
SRTC Sensitivity-based Radio Tuning Calibration
TR Technical Release
USACE U.S. Army Corps of Engineers
USGS U.S. Geological Survey
W width
WWHM Western Washington Hydrology Model
yr year(s)
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
1
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
Section 1: Introduction
As part of the 2015 Comprehensive Storm Drainage Plan (2015 Drainage Plan) update, Brown and Caldwell
(BC) performed hydrologic and hydraulic (H&H) analyses for nine problem locations within the City of Au-
burn’s (City) storm drainage system. These analyses included model development and refinement, model
calibration (where possible), and desktop evaluations of drainage problems in areas recently annexed from
King County.
1.1 Background
The City initiated an extensive drainage system data inventory and H&H modeling effort to support the
development of capital improvement projects for the 2009 Comprehensive Stormwater Drainage Plan (2009
Drainage Plan) (Brown and Caldwell, 2009). As a result, 15 storm drainage system models were created for
areas throughout the city. Each model is identified by the lettered subbasin drainage area(s) covered within
the model extent. For example, the “GHI model” covers three subbasins: G, H, and I.
The City’s data inventory effort has continued since 2009, with dedicated field survey staff collecting drain-
age system data across the city on a quarter-section-by-quarter-section basis. The City updates its geograph-
ic information system (GIS) data on an ongoing basis based on the survey data. The City has also continued
to develop and refine models when needed to support the design of capital improvement projects. During
this process, several of the models were converted from MIKE URBAN1 software to the PCSWMM2 (version
5.0.022) software to improve modeling efficiency. Additionally, some of the models were refined based on
field survey data, system updates, and monitoring data collected in 2010 and 2011. Leading into the 2015
Drainage Plan update, the City’s models were in varying states of development, depending on the status of
the system inventory and locations of capital improvement projects.
1.2 Purpose and Objectives
Based on the problems identified during the early stages of the 2015 Drainage Plan update, existing H&H
models were refined or new models were developed if there was no existing model. After models were
developed, they were calibrated based on available data. The calibrated models were used to perform long-
term simulations, and to perform a flow frequency analysis to identify design storms. The models and the
identified design storms were used to develop capital improvement projects that addressed the identified
problem and met the City’s stormwater level of service (LOS) goals. The purpose of this technical memoran-
dum is to document the modeling efforts performed in support of the 2015 Drainage Plan. The objectives
achieved are the documentation of:
· model update based on current data sources
· model development and refinement steps
1 MIKE URBAN is a GIS-integrated, modular software program developed by the Danish Hydraulic Institute (DHI) for modeling water
distribution and collection systems. The stormwater module is internally powered by the SWMM5 engine, which is public domain
software distributed by the U.S. Environmental Protection Agency (EPA). Information about MIKE URBAN software can be found at
http://www.mikepoweredbydhi.com/products/mike-urban.
2 PCSWMM is a GIS-based H&H modeling platform developed by Computational Hydraulics International (CHI). The software fully
supports the EPA SWMM5 hydrology and hydraulics engine, thus providing comparable computation between EPA SWMM and
PCSWMM models. Information about PCSWMM software can be found at
http://www.chiwater.com/Software/PCSWMM/index.asp.
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
2
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
· model calibration steps and calibration results
· drainage problem evaluation in the annexation areas
The model development and refinement approach and model parameters are described in Section 2.
Calibration efforts, data, and results are discussed in Section 3. A summary of the annexation area desktop
evaluation, which includes modeling and additional evaluations, is provided in Section 4. Section 5 includes
a summary of the H&H modeling and evaluation efforts completed in support of the 2015 Drainage Plan.
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
3
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
Section 2: Model Development and Refinement
The City developed and prioritized a list of nine known drainage problems, along with potential capital
improvement projects to address the known problem, for inclusion in the 2015 Drainage Plan. BC performed
an H&H analysis of the storm drainage system at each of the nine problem locations. The following sections
describe the model development procedures and input parameters used to prepare the models for subse-
quent evaluations.
Of the nine prioritized drainage problems, two are located in portions of the city where there is minimal piped
conveyance (i.e., ditch and culverts) or complex natural drainage networks. Because PCSWMM is not the
best tool for analyzing these systems, other modeling tools (Western Washington Hydrology Model [WWHM]
and Hydrologic Engineering Center River Analysis System [HEC-RAS]) were used to perform H&H analyses.
The seven remaining problems were analyzed using PCSWMM. Table 2-1 lists the storm drainage subbasins
for which models were used to evaluate problems and develop capital improvement projects. The table also
presents unique information for each model including the type of model, infiltration method, design storms
events, calibration status, and associated capital improvement projects.
Table 2-1. Subbasin Model Summary
Modeled
subbasin(s)
Model
status
Hydrology model
(infiltration method)
Hydraulic
model Design events
Calibration
status Project number and namea
BCDF Updated for
2015
Drainage
Plan
PCSWMM
(Green-Ampt)
PCSWMM 25-year: 11/4/2006
Calibrated for
2015 Drainage
Plan
Project 7: D St. SE Storm Improve-
ments
Project 8: 23rd St. SE Drainage
Improvements
GHI Updated for
2015
Drainage
Plan
PCSWMM
(Green-Ampt)
PCSWMM 25-year: 11/4/2006
50-year: 11/5/2006
Calibrated prior
to 2015
Drainage Plan
Projects 4A and 4B: 30th Street NE
Area Flooding, Phases 2 and 3
Project 6: North Airport Area Improve-
ments
OO New for
2015
Drainage
Plan
WWHM12
(Hydrological
Simulation Program--
Fortran [HSPF])
Manning’s n
equations
Storm ranking in
WWHM12
Calibration data
unavailable
Project 5A: West Hills Drainage
Improvements at S 330th St. and 46th
Pl. S
Project 5B: West Hills Drainage
Improvements near S 31th St. and
54th Ave. S
P Updated for
2015
Drainage
Plan
PCSWMM
(Soil Conservation
Service [SCS] curve
number [CN])
PCSWMM 25-year: 1/29/1990
50-year: 11/6/2006
Calibrated for
2015 Drainage
Plan
Project 1: West Main Street Pump
Station Upgrade
TT Updated for
2015
Drainage
Plan
None, used range of
typical flows
HEC-RAS n/a, used range of
typical flows
Uncalibrated due
to complexity of
Mill Creek
Project 2: 37th and I Streets NW Storm
Improvements
a. Projects listed correspond to the nine known drainage problems. Projects 4A, 4B, 5A, and 5B each address a separate problem. Project 3 is not
included as it did not require H&H analysis because it is a project to assess pipes that discharge over hillsides.
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
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DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
Figure 2-1 shows the subbasin boundaries highlighting the subbasins modeled for the 2015 Drainage Plan,
the location of problem areas for which capital improvement projects have been developed, and monitoring
locations where data were collected to calibrate the models.
!(
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12
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15TH ST SW
SE 288TH ST
2ND ST E
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S
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SE 312TH ST
S 277TH ST
JO
V
I
T
A
B
L
V
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W MAIN ST
15TH ST
N
W
S 384TH ST
198TH AVE E
53RD ST SE
9TH ST E
29TH ST SE
SE 320TH ST
11
4
T
H
A
V
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11
6
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A
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EDWARDS RD E
LAKE TAPPS PKWY SE
41ST
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STUCK
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24TH ST E
16TH ST E
K
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7
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4TH ST E
18TH ST E
M
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12TH ST E
SE 304TH ST
1
9
0
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3RD AVE SE
ELLINGSON RD SW
37TH ST SE
PE
R
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SE 272ND ST
4
6
T
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P
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S
8TH ST NE
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OR
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SE 282ND ST
14
4
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S
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17TH ST SE
S 296TH ST
25TH ST SE
12TH ST SE
5
5
T
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A
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S
D
S
T
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E
1ST AVE SE
TAC
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A
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N
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A
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4TH ST SE
CE
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30TH ST NE
10
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11
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SE 316TH ST
14
8
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55TH ST SE
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SE 368
T
H
P
L
W
S
T
N
W
S 287TH ST
5TH AVE SW
E
S
T
N
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69TH ST S
E
11
2
T
H
A
V
E
E
S 316TH ST
H
A
R
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R
D
S
C
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N
I
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A
I
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T
S 292ND ST
WE
S
T
B
L
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(
B
O
E
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)
44TH ST NW
3RD AVE SW
1
8
6
T
H
A
V
E
E
10TH ST NE
CL
A
Y
S
T
N
W
4TH AVE SW
14
8
T
H
A
V
E
E
7TH ST SE
13
7
T
H
A
V
E
E
13
6
T
H
A
V
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E
SE 310TH ST
S 3RD AVE
TH
O
R
T
O
N
A
V
E
S
W
12
7
T
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P
L
S
E
RIVE
R
D
R
BOUNDARY BLVD
LEA HIL
L
R
D
S
E
11
8
T
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A
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S
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58
T
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A
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S
S 3
6
4
T
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P
L
AL
G
O
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A
B
L
V
D
N
10
4
T
H
A
V
E
S
E
S 372ND ST
J
S
T
N
E
4TH ST NE
11
0
T
H
A
V
E
S
E
SE 281ST ST
72
N
D
A
V
E
S
56
T
H
P
L
S
BR
I
D
G
E
T
A
V
E
S
E
57
T
H
A
V
E
S
DO
G
W
O
O
D
S
T
S
E
2ND AVE SW
8TH ST SE
S 279TH ST
12
6
T
H
A
V
E
E
T
S
T
S
E
F
S
T
S
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FR
O
N
T
A
G
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R
D
52
N
D
A
V
E
S
SE 274TH ST
1ST ST E
SE 299TH ST
SE 284TH ST
49TH ST N
E
H
O
W
A
R
D
R
D
SE 296TH WAY
54
T
H
A
V
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S
A
S
T
S
W
U
S
T
N
W
S 331ST ST
7
8
T
H
A
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S
3RD ST E
13
5
T
H
A
V
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S
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47TH
S
T
S
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8
6
T
H
A
V
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S
R S
T
N
W
15TH ST E
MI
L
I
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D
S
13TH ST E
K
S
T
S
E
OL
I
V
E
A
V
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S
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10TH ST E
10
8
T
H
A
V
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E
SE 323RD PL
5
4
T
H
P
L
S
B
S
T
S
E
W
Y
M
A
N
D
R
26TH ST SE
S 336TH ST
S 340TH ST
S 300TH ST
ELM LN
64TH ST SE
SE 301ST ST
SE 287TH
S
T
V
S
T
N
W
3RD ST SE
21ST ST NE
HE
M
L
O
C
K
S
T
S
E
56
T
H
A
V
E
S
24TH ST SE
LU
N
D
R
D
S
W
PI
K
E
S
T
N
W
21ST ST E
42ND ST NW
17T
H
S
T
E
11
9
T
H
A
V
E
E
SE 276TH PL
65
T
H
A
V
E
S
SE 295TH PL
G
S
T
N
E
S
2
9
7
T
H
P
L
O
S
T
S
E
27TH ST SE
1
0
2
N
D
A
V
E
S
E
12
8
T
H
A
V
E
E
S 344TH ST
SE 364TH ST
SE 290TH ST
S 288TH ST
V
S
T
S
E
B PL NW
SE 294TH ST
14
6
T
H
A
V
E
S
E
Z
S
T
S
E
S 305TH ST
S 370TH ST
19TH DR NE
SE 307TH PL
SE 314TH ST
14
0
T
H
A
V
E
S
E
28TH ST SE
10
8
T
H
A
V
E
S
E
73RD ST SE
S 319TH ST
S 366TH ST
SE 297TH ST
K
S
T
N
E
24TH ST NE
SE 296TH ST
SE 285TH ST
S 368TH ST
11
7
T
H
A
V
E
S
E
S 302ND PL
6TH ST SE
11
0
T
H
P
L
S
E
55
T
H
A
V
E
STA
N
L
E
Y
A
V
E
7TH ST
HE
A
T
H
E
R
A
V
E
S
E
11
2
T
H
P
L
S
E
SE 292ND ST
2ND AVE NE
13
0
T
H
A
V
E
S
E
I P
L
N
E
R
S
T
N
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FI
R
S
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S
E
CH
I
C
A
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V
E
T
S
T
N
E
8TH ST E
SR 18
13TH ST E
SR
1
6
7
SR
1
6
7
SE 288TH ST
D
S
T
S
E
M
S
T
N
W
17TH ST SE
SE 304TH S
T
M
S
T
N
E
SE 272ND ST
SE 282ND ST
16TH ST E
S 277TH ST
10
8
T
H
A
V
E
S
E
51
S
T
A
V
E
S
SE 272ND ST
12
4
T
H
A
V
E
S
E
9TH ST E
SR 18
M
S
T
N
E
SE 284TH ST
SR
1
6
7
8TH ST NE
S
R
1
6
7
SR
1
6
7
SR
1
6
7
14
4
T
H
A
V
E
S
E
SR 18
SR
1
6
7
51
S
T
A
V
E
S
SR
1
6
7
SR 1
8
R
S
T
N
W
2ND ST E
LEGEND
#Mill Creek Gauge
#*Flow Monitor
!(Project Location
Roadway
Watercourse
Water Body
Wetland
Auburn City Boundary
¯0 5,000 10,0002,500
Feet
COMPREHENSIVE STORM DRAINAGE PLAN
October 2015 Figure 2-1Modeled Subbasins, and Monitoringand Project Locations
P:
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1 inch = 5,000 feet
ID Project Name 1 West Main Street Pump Station Upgrade 2 37th and I Streets NW Storm Improvements 3 Hillside Drainage Assessment* 4A 30th Street NE Are Flooding, Phase 2 4B 30th Street NE Are Flooding, Phase 3 5A West Hills Drainage Improvements near S 330th St. and 46th Pl. S 5B West Hills Drainage Improvements at S 314th St. and 54th Ave. S 6 North Airport Area Improvements 7 D St. SE Storm Improvements 8 23rd St. SE Drainage Improvements 9 Comprehensive Storm Drainage Plan update* 10 Vegetative Waste Sorting Facility (location to be determined)* 11 Storm Drainage Infrastructure Repair & Replacement* 12 Street Utility Improvements* *Project not mapped; multiple locations or location to be determined
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
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DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
2.1 Model Development
Existing PCSWMM models were updated with recent data. If there was not an existing model in a problem
area, a new model was developed. The steps taken to update existing models or create new models are
described below.
2.1.1 Updating Existing PCSWMM Models
GIS data from December 2013 and June 2014 were used to update the PCSWMM files for the BCDF, GHI,
and P models. Survey data for quarter-sections 1009 and 1109 collected in November 2014, after the initial
data were provided to BC, are included in the BCDF model. The following infrastructure data attributes were
checked against the GIS data:
· pipe size
· pipe invert elevations
· pipe material (for estimating pipe roughness)
· node (i.e., catch basin or manhole) rim elevation
· system connectivity
Where the GIS data did not include recent survey information and did not accurately describe the existing
system (based on the City’s knowledge of the system), technical reports, record drawings, or construction
drawings were used to update the model. Detailed pipe information from a stormwater infrastructure survey
performed by Reid Middleton in 2011 and 2013 were used to update the GHI model (Reid Middleton, 2011
and 2013).
For model hydrology, subcatchment delineations within problem areas were reviewed and revised based on
recent GIS data, topographic data (2-foot contour data), and 2012 aerial photography. Total impervious area
was estimated with the City’s impervious area coverage included in the December 2013 GIS data. Sub-
catchment slope was estimated as the average slope based on a digital elevation model (DEM) or 2-foot
contour data. Table 2-2 summarizes the model data sources.
Table 2-2. Model Data Description and Source
Data type Description and source
Hydrologic model input
Subbasin and subcatch-
ment boundaries
Existing model subbasin boundaries refined based on City GIS topography (2-foot contour data), roads, stormwater
infrastructure data, record drawings, and aerial photography.
Land use Existing City land use GIS data based on adopted land use designations through 2011.
Impervious area City GIS impervious area coverage from December 2013 and Sutherland equationsa used to estimate effective
impervious area (P subbasin).
Hydrologic soil group Hydrologic soil group available from Natural Resources Conservation Service (NRCS) soil data (NRCS, 1986).
Slope Weighted average slope from U.S. Geological Survey (USGS) DEM data sets (PCSWMM models).
City 2-foot contour data (all other models and some flat areas in smaller PCSWMM models).
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
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DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
Table 2-2. Model Data Description and Source
Data type Description and source
Hydraulic model input
Conduits (stream, creek,
and ditch, pipe and culvert)
Primary sources of data were City GIS data, record drawings, construction drawings, or modeling reports. If these
sources were not available, conveyance extent was estimated with City 2-foot contour data and aerial photography,
and Google aerial and street view photographs.
Nodes (manhole, catch
basin, and infall)
Primary sources of data were City GIS data, record drawings, construction drawings, or modeling reports. If these
sources were not available, rim elevations were estimated from City 2-foot contour data and invert elevations were
estimated based on connected pipe and node data, as noted in the model.
Outfall Primary sources of data were City GIS data. If these sources were not available, rim elevations were estimated from
City 2-foot contour data.
Storage facility
(wetland, detention ponds)
City GIS data and 2012 aerial photography, Google street view.
Boundary conditions at
outfalls
Modeled as fixed level based on monitoring data (Mill Creek gauge) or modeled water surface elevations (Green
River Hydraulic Modeling and Mapping, BCDF model).
a. Sutherland equations are empirically based formulas to estimate effective impervious area from a mapped impervious area value based
on observed or assumed surface water connections (Sutherland, 2000).
2.1.1.1 Hydrologic Parameters
Subcatchment parameters define the hydrologic component of the PCSWMM model. Table 2-3 lists the
subcatchment attributes and the values for each PCSWMM model. Where flow monitoring data were availa-
ble, calibration was completed by adjusting hydrologic parameters: estimating effective impervious area,
reducing subcatchment width, and adjusting soil conductivity parameters (see Section 3 for additional
information on calibration procedures).
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
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DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
Table 2-3. PCSWMM Subcatchment Model Attributes
Model
attribute Description Value
Name Subcatchment name assigned to correlate with the name of the subcatchment
outlet node based on City ID (e.g., 909-B1). Process same for all models
Rain gauge Composite precipitation time series. Same for all models (see Table 2-9)
Area Area of the subcatchment in acres. Varies, based on subbasin dimensions
Length Maximum length of overland sheet flow in feet. Estimated in GIS based on the
manually drawn longest flow path.
Varies, based on subcatch-
ment and calibration P
Varies, based on subcatch-
ment BCDF, GHI
Width
Width of the overland flow path for sheet flow in feet. Calculated within
PCSWMM as area/length. For P subbasin, used as a calibration parameter, by
adjusting the length.
Varies, based on subcatch-
ment dimensions and
calibration
P
Varies, based on subcatch-
ment dimensions BCDF, GHI
Slope Average percent slope of the subcatchment. Varies, based on DEM or GIS 2-foot contour data
Imperv Percent of land area that is directly connected impervious area.
Varies, based on dimensions
and calibration GHI, P
Varies based, dimensions BCDF
Auburn Storm Drainage Hydrologic and Hydraulic Modeling and Evaluation
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DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the beginning of this document.
Appendix C - H&H Modeling and Evaluation_v2.docx
Table 2-3. PCSWMM Subcatchment Model Attributes
Model
attribute Description Value
Nimperv Manning’s n for overland flow over the impervious portion of the subcatch-
ment. 0.012
Nperv Manning’s n for overland flow over the pervious portion of the subcatchment.
Short grass (0.15) Same for all models
Dense grass (0.24) Same for all models
Underdeveloped area (0.40) BCDF
Dstore-
Imperv Depth of depression storage on the impervious portion of the subcatchment.
0.7 inch P
0.75 inch BCDF, GHI
Dstore-Perv Depth of depression storage on the pervious portion of the subcatchment.
0.15 inch BCDF, GHI, P
0.3 inch (underdevelopment area) BCDF
ZeroImperv Percent of the impervious area with no depression storage.
0% GHI
5% BCDF, P
Routing
If assigned outlet, runoff from pervious and impervious areas routes to a node
within the storm drain system. If assigned pervious, a percent of the impervi-
ous area (as specified in PctRouted) is routed to pervious areas and infiltration
computations are performed before flow is routed to the outlet. This is
representative of the not directly connected (versus the effective) impervious
areas.)
Outlet GHI
Pervious BCDF
Varies by subcatchment P
PctRouted Percent of runoff from impervious areas routed to pervious areas before flow is
routed to the outlet. Adjusted during calibration.
100% GHI, P
Varies, based on calibration BCDF
Groundwater Groundwater routing to aquifer. Not modeled because not observed in flow monitoring
data
CurveNo SCS CN calculated as an area-weighted average using land use and
hydrologic soil group within each subcatchment (see Table 2-6). Relevant to SCS CN model (P subbasin) only
DryTime Time in days for a fully saturated soil to completely dry for SCS CN infiltration
method (Table 2-6). Relevant to SCS CN model (P subbasin) only
Suction
Head
Soil capillary suction head in inches for Green-Ampt infiltration method (see
Table 2-4).
Varies by subcatchment BCDF
6.57 GHI
Conductivity Soil saturated hydraulic conductivity in inches/hour for Green-Ampt
infiltration method. Adjusted during calibration (BCDF model) (see Table 2-4).
Varies by subcatchment and
based on calibration BCDF
0.26 GHI
Initial Deficit Initial soil moisture deficit in fraction of whole for Green-Ampt infiltration
method. Calculated as soil porosity minus field capacity (see Table 2-4).
Varies by subcatchment BCDF
0.3 GHI
2.1.1.2 Infiltration Methods and Parameters
PCSWMM allows for one of three infiltration methodologies: Green-Ampt, Horton, or Soil Conservation
Service (SCS). Where flow monitoring data were available (BCDF and GHI models) infiltration is based on
Green-Ampt with infiltration parameters being adjusted during calibration. The P subbasin model uses the
SCS method for infiltration.
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Green-Ampt. For the Green-Ampt infiltration method, the suction head, conductivity, and initial deficit
parameters were derived from the Natural Resources Conservation Service (NRCS) hydrologic soil group
(Table 2-4). For the GHI subbasin model, soils are predominantly D and the Green-Ampt parameters are
consistent for all subcatchments within the model. For the BCDF subbasin model, soils consist of hydrologic
soil groups A, B and D, and the Green-Ampt parameters are an area-weighted average and vary by
subcatchment.
Table 2-4. Initial Green Ampt Parameters
Hydrologic
soil group
Average
conductivity
(in./hr)
Suction head
(in./hr)
Initial deficit
A 2.6 2.89 0.32
B 0.23 5.10 0.22
C 0.10 8.66 0.15
D 0.025 10.47 0.12
Note: Values are based on soil texture class, as related to hydrologic soil group, and
are average (EPA, 2010, Table A.2)
SCS. For the SCS method, curve number (CN), saturated hydraulic conductivity, and drying time parameters
were assigned to each subcatchment based on the predominant land use type as shown on soil maps
developed by King County and Pierce County. Where there were multiple soil types or land use within a
subcatchment, an area-weighted average CN was calculated based on the land use assumptions presented
in Table 2-5.
Table 2-5. Curve Number Based on Auburn Land Use and Hydrologic Soil Group
Auburn land use SCS land use
CN by hydrologic soil group
A B C D
Open space Open spaces, lawns, parks, golf course, cemeteries, etc.;
good condition: grass cover on 75% or more of the area
39 61 74 80
Public and quasi-public Open spaces, lawns, parks, golf course, cemeteries, etc.; fair
condition: grass cover on 50%–75% of the area
49 69 79 84
Heavy commercial, heavy industrial,
downtown
Commercial and business areas (85% impervious) 89 92 94 95
Light commercial, light industrial,
neighborhood commercial
Industrial districts (72% impervious) 81 88 91 93
Office residential Residential 1/8 acre or less lot (65% impervious) 77 85 90 92
High-density residential, moderate-
density residential
Residential 1/4 acre lot (38% impervious) 61 75 83 87
Single-family residential Residential 1/2 acre lot (25% impervious) 54 70 80 86
Rural residential Residential 1 acre lot (20% impervious) 51 68 79 84
Street Streets and roads; paved with curbs and storm sewers 98 98 98 98
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Saturated hydraulic conductivity and drying time were assigned based on the NRCS hydrologic soil group
definitions. For the saturated hydraulic conductivity, a value in the middle of the range was used. Values
near the higher end were assigned for the drying time to simulate conditions representative of winter
months, when drainage problems are more likely to occur. Table 2-6 shows the hydraulic conductivity and
drying time by hydrologic soil group.
Table 2-6. SCS Model Parameters
Hydrologic
soil group
Saturated hydraulic
conductivity (in./hr)
Drying
time (days)
A 1 8
B 0.22 10
C 0.1 12
D 0.025 14
2.1.2 Creating New WWHM Models
The following is a general description of steps followed to develop new WWHM models for the OO subbasin:
1. Subcatchments within subbasins were delineated with existing GIS data including 2012 aerial photog-
raphy, roadway extents, 2-foot contour data, and drainage network (catch basins, manholes, pipes,
ditches, infalls, and outfalls).
2. Existing GIS data were used to determine hydrologic parameters for WWHM: hydrologic soil group, slope,
land cover (i.e., lawn, impervious area). Subbasin slope was estimated from the 2-foot contour data. To-
tal impervious area was estimated with the City’s impervious area coverage. 2012 aerial photography
was used to estimate vegetation. Table 2-2 summarizes the data types.
3. WWHM uses the Hydrological Simulation Program--Fortran (HSPF) hydrology model. HSPF calculates all
individual components of the hydrologic cycle including surface runoff, interflow, groundwater, soil mois-
ture, and evapotranspiration. HSPF simulates infiltration as a function of soil moisture using a set of re-
gionally calibrated parameters included within WWHM.
2.1.3 Drainage Modeling using HEC-RAS
The ditch-and-culvert drainage system along the south side of 37th Street NW was modeled using the HEC-
RAS3 hydraulic modeling software. Basic geometric data inputs for the HEC-RAS model (i.e., cross-sections
and ditch lengths) were developed using digital elevation data from a 2003 King County light detection and
ranging (LiDAR) survey (King County, 2003). These inputs were modified based on City field observations,
including estimated culvert sizes, invert elevations, and roadway embankment heights.
2.2 Hydraulic Parameters
Table 2-7 lists the Manning’s roughness coefficients (n) used for conveyance analysis in the PCSWMM
models, and in the flow calculations for pipe sizing related to the WWHM analysis.
3 HEC-RAS stands for Hydrologic Engineering Center River Analysis System. This program, which was developed by the U.S. Army
Corps of Engineers to perform one-dimensional hydraulic computations, can be used to calculate hydraulic profiles in open channels
(USACE, 2010).
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Table 2-7. Manning’s Roughness Coefficients
Conveyance material Model value
Corrugated polyethylene pipe (CPEP) or ADS (manufacturer of CPEP) 0.012
Force main 0.012
Polyvinyl chloride (PVC), reinforced polyvinyl chloride (RPVC), and high-density polyethylene (HDPE) 0.0125
Ductile steel and ductile iron 0.013
Culvert 0.013
Concrete/reinforced concrete pipe (RCP) 0.013
Material unknown 0.013
Corrugated metal pipe (CMP) 0.024
Ditch 0.05
2.3 Monitoring Data
Depth, velocity, and water level monitoring data and pump station supervisory control and data acquisition
(SCADA) data were collected subsequent to the 2009 Drainage Plan and used to estimate boundary condi-
tions and calibrate the BCDF, GHI, and P subbasin models. Table 2-8 lists the monitoring locations, model
and purpose for which it was used, and period of record.
Table 2-8. Flow Monitoring Summary
Type Meter ID Location Manhole
ID Modeling purpose Modeled
subbasin Period of record used in model
Depth, velocity AUB_B4 8th St. NE and
Henry Rd. 710-B4 Calibration BCDF 12/17/2010–3/19/2011
Depth, velocity AUB_B86 201 12th St.
SE 909-B86 Calibration BCDF 12/17/2010–3/19/2011
Depth, velocity AUB_B99 16th St. SE
and B St. SE 909-B99 Calibration BCDF 12/17/2010–3/19/2011
Depth, velocity AUB_C18 G St. SE 809-C18 Calibration BCDF 12/17/2010–3/19/2011
Water level n/a 17th St. Pond n/a Calibration BCDF 11/3/2010–12/31/2010
Water level n/a 21st St. Pond n/a Calibration BCDF 11/3/2010–12/31/2010
Water level WL-Mill-01 Mill Creek at
37th St. NW n/a Calibration TT 11/1/2011–12/31/2011
Water level WL-Mill-02 Mill Creek at
29th St. NW n/a Calibration TT 11/1/2011–12/31/2011
Water level WL-Mill-03 Mill Creek at
15th St. NW n/a Calibration TT 11/1/2011–12/31/2011
Water level WL-Mill-04 Mill Creek at W
Main St. n/a
Outfall boundary condition,
average winter month level
Calibration
P
TT
5/23/2011–3/12/2014
11/1/2011–12/31/2011
Flow ST-18 Old West Main
St. & SR 167 807-P156 Calibration City of Auburn
SCADA system 12/28/2012–5/12/2014
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2.4 Climatic Data
Precipitation time series data are required to simulate the hydrologic modeling processes in PCSWMM and
WWHM. Evaporation data are also required for WWHM and some applications of PCSWMM. The following
sections describe the development of these data for use in the models.
2.4.1 Precipitation
The PCSWMM models use a volume-based 15-minute time series rainfall record developed by BC for the City
with a period of record from October 1, 1948, to November 1, 2014. The data set is a composite from three
rain gauges: City of Auburn, Sea-Tac International Airport, and King County Lakeland Hills (located in Auburn
city limits). The City of Auburn gauge data are used when possible. The City’s gauge has been collecting
rainfall data since 1995. However, based on previous modeling efforts and review of the City’s gauge data, it
was deemed that data from the Sea-Tac International Airport gauge prior to 2010 should be used. The King
County Lakeland Hills data are used when the Sea-Tac gauge data are known not to reflect the rainfall in
Auburn (e.g., during a large event in 2007) and when Auburn gauge data are not available. Table 2-9 lists
the sources of data for the precipitation time series used in PCSWMM modeling efforts.
The WWHM software contains an embedded precipitation file based on the Sea-Tac gauge from October 1,
1948, to October 1, 2012. These rainfall data were used for the WWHM analysis.
Table 2-9. Auburn Composite Precipitation Record for PCSWMM Models
Rain gauge Period of record Notes
Sea-Tac International Airport 10/1/1948–11/30/2007 Data obtained from WWHM
King County Lakeland Hills 12/1/2007–12/6/2007 Sea-Tac rainfall not representative at Auburn
Sea-Tac International Airport 12/7/2007–12/31/2009 Data obtained from WWHM
City of Auburn 15-min rainfall 1/1/2010–12/31/2010 -
City of Auburn aggregated 5-min 1/1/2011–11/14/2012 -
King County Lakeland Hills 11/14/2012–12/4/2012 Auburn gauge inoperable during this period
City of Auburn aggregated 5-min 12/5/2012–11/1/2014 -
2.4.2 Evaporation
Evaporation estimates are used by PCSWMM models that use the SCS CN infiltration method. These models
used monthly evaporation values measured in inches per day, which were provided by the City during
previous planning efforts. WWHM requires potential evapotranspiration estimates. These values are includ-
ed with WWHM.
2.5 Horizontal and Vertical Datum
The horizontal and vertical datums of the models are consistent with the City’s GIS datums as follows:
· horizontal: NAD_1983_StatePlane_Washington_North_FIPS_4601_Feet (GCS_North_American_1983)
· vertical: North American Vertical Datum of 1988 (NAVD88)
Where necessary, elevations from other sources, such as as-built drawings and reports that are based on
National Geodetic Vertical Datum of 1929 (NGVD29), were converted to NAVD88. A value of 3.53 feet was
added to the NGVD29 elevation to convert to NAVD88. This conversion value was estimated using the
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VERTCON tool provided by the National Oceanic and Atmospheric Administration (NOAA) at the following
website: http://www.ngs.noaa.gov/TOOLS/Vertcon/vertcon.html. The conversion was estimated for latitude
35 degrees, 12 minutes, and 59.69 seconds north, and longitude 111 degrees, 40 minutes, and 2.06
seconds west.
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Section 3: Model Calibration and Evaluation
BC performed calibration on the BCDF and P subbasin models. The BCDF model was calibrated with flow
monitoring data and pond level data, while the P subbasin was calibrated with pump station SCADA data.
The calibration for these models is described below.
The GHI model was calibrated with flow monitoring data prior to the 2009 Drainage Plan and the 2015
Drainage Plan update. Therefore, no calibration was conducted for the GHI model as part of the 2015
Drainage Plan update. There were no observed data for the OO subbasin model. The TT subbasin model was
not calibrated because of the complexity of the natural Mill Creek system that impacts the problem area.
3.1 BCDF Model Calibration
The BCDF model was calibrated based on flow monitoring data (from end of December 2010 through mid-
March 2011) from four locations and pond level data (November and December 2010) from two infiltration
ponds. Peak storm events were identified using data from the four flow meters.
The largest six peak flows at each meter occurred during the same storm events. Five of the peak storm
events were used in model calibration for comparing observed and simulated flows. The sixth event occurred
on January 13, 2011, and the peak flows for this event did not correspond to the precipitation record.
According to historical weather data, this event included snowmelt, which is not currently simulated with the
model; therefore, calibration was completed with the five remaining events. A summary of the storm events
is included in Table 3-2. Model calibration goals were to have modeled peak flows, event volumes, and
maximum depths within 15 percent of the observed data.
Peak storm events were also identified for the period when pond level data were available. Seven peak
events were identified, based on the maximum pond level. A summary of the storm events is included in
Table 3-3. Model calibration goals were to have modeled maximum depths within 15 percent of the ob-
served data.
3.1.1 Methodology
The model was calibrated using the PCSWMM Sensitivity-based Radio Tuning Calibration (SRTC) tool to vary
two hydrologic parameters: percent routed and soil hydraulic conductivity. The percent routed parameter is
the percent of impervious area that is not directly connected to the drainage system, but is first routed to the
subcatchment pervious area. The percent routed was varied, from the original GIS-estimated impervious
area, by a fixed amount for all subcatchments upstream of a meter. Subcatchments upstream of a meter (or
calibration subbasins) are shown on Figure 3-1. The percent routed was adjusted so the simulated peak flow
matched the flow monitoring data.
Hydraulic conductivity was adjusted (increased from the soil-based values) to match the recession (i.e., tail
end) of the storm hydrograph, which affected the simulated storm event volumes. For some calibration
subbasins, the values were increased by a fixed percentage. In other calibration subbasins, the percent
change was varied by soil type, based on a visual comparison of the simulated and observed event hydro-
graphs.
If simulated and observed values were within 15 percent, then the calibration was considered reasonable.
Furthermore, visual assessment of the event peak flow, volume, and depth was made to qualify the calibra-
tion results.
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For unmonitored areas, the lowest percent routed from the calibrated subbasins was applied to all sub-
catchments. Applying the lowest percent routed value to unmonitored areas is conservative, as the model
produces more runoff for lower values. Hydraulic conductivity was not adjusted for unmonitored areas.
These unmonitored areas should be considered uncalibrated. The final calibration parameters are summa-
rized in Table 3-1.
Table 3-1. Final Hydrology Parameters Adjusted during Calibration
Parameter
Calibration subbasin Areas outside
monitored
areas AUB_B4 AUB_B86 AUB_B99 AUB_C18 17th and 21st
St. ponds
Percent impervious
routed to pervious 71 70.8 62 56 70.35 56
Hydraulic conductivity
(in./hr) 0.32 0.14
0.06–0.48 (increased
soil-based values for
each subcatchment by
150%)
0.24
D soils increased
from 0.025 to 0.236;
other soil types
increased by 118%
Unadjusted
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Figure 3-1. BCDF model meter subbasins
3.1.2 Results
The calibration results are summarized in Table 3-2. The calibration improved the model’s ability to estimate
flow in the City’s storm drainage system. The models are considered sufficient tools for capital improvement
project development in the areas where problems have been identified, and to increase confidence in
project sizing to meet the City’s LOS. In general, goals were met for some events at some locations, but were
not met for all events at all meters. Calibration results for each meter are summarized below.
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AUB_B4. Calibration at this meter did not meet the goals for depth (for all events) and volume and peak flow
for some events. This meter has a large tributary area and calibration could not be improved with the
available information. For the 2015 Drainage Plan update, there were no problem areas in this calibration
subbasin, and the calibration was considered adequate. If future problems or projects area are identified,
additional calibration events may be warranted.
AUB_B86. Peak flows were under- and over simulated with simulated peaks flows meeting the calibration
criteria for five events. In general, peak volumes were over-simulated, while depths were under-simulated.
AUB_B99. In general, simulated depths matched observed depths. Peak flow were under-simulated while
volumes were over- and under-simulated for some events.
AUB_C18. In general, simulated depths matched observed depths. Peak flow and volumes were over- and
under-simulated for some events.
Table 3-2. BCDF Flow Monitoring Observed Data Model Calibration Summary
Event Start date Duration
(hr)
Total
rainfall
(in.)
Peak 15-
min
rainfall
(in./hr)
Peak 15-minute flow (cfs) Volume (ft3) Maximum depth (ft)
Calibrated Observed Difference
(%) Calibrated Observed Difference
(%) Calibrated Observed Difference
(%)
AUB_B4
1 2/12/2011 15:00 12 0.55 0.72 33.1 24.5 35 221,200 168,500 31 1.1 2.2 -49
2 2/27/2011 18:00 13.8 0.63 0.24 14.0 15.2 -8 223,500 206,100 8 0.7 1.6 -54
3 3/9/2011 09:00 24 1.16 0.28 17.2 17.0 1 446,300 343,600 30 0.8 1.8 -57
4 3/13/2011 15:00 9 0.37 0.28 14.7 14.6 0 137,800 126,600 9 0.7 1.7 -56
5 3/15/2011 12:45 7 0.24 0.32 11.9 14.7 -19 83,760 64,330 30 0.7 1.7 -60
AUB_B86
1 2/12/2011 15:00 12 0.55 0.72 3.2 2.2 43 18,170 14,970 21 3.7 4.3 -15
2 2/27/2011 18:00 13.8 0.63 0.24 1.5 1.6 -5 20,310 13,600 49 0.7 0.9 -22
3 3/9/2011 09:00 24 1.16 0.28 1.9 1.8 6 37,820 36,590 3 0.8 2.1 -60
4 3/13/2011 15:00 9 0.37 0.28 1.6 1.8 -10 11,970 11,370 5 0.7 1.0 -24
5 3/15/2011 12:45 7 0.24 0.32 1.4 1.6 -10 7,533 7,747 -3 0.7 1.0 -33
AUB_B99
1 2/12/2011 15:00 12 0.55 0.72 3.0 3.2 -5 25,670 21,150 21 1.5 1.8 -15
2 2/27/2011 18:00 13.8 0.63 0.24 1.8 2.1 -16 28,840 28,430 1 0.9 0.8 13
3 3/9/2011 09:00 24 1.16 0.28 2.1 2.5 -18 63,350 66,420 -5 1.0 1.0 6
4 3/13/2011 15:00 9 0.37 0.28 1.8 2.4 -25 17,100 21,420 -20 1.0 0.9 8
5 3/15/2011 12:45 7 0.24 0.32 1.7 2.4 -28 9,895 14,620 -32 0.9 0.9 1
AUB_C18
1 2/12/2011 15:00 12 0.55 0.72 14.9 13.3 13 96,730 66,090 46 2.1 2.2 -5
2 2/27/2011 18:00 13.8 0.63 0.24 7.2 7.3 0 98,880 79,470 24 1.3 1.4 -4
3 3/9/2011 09:00 24 1.16 0.28 9.3 9.8 -5 192,200 198,400 -3 1.5 1.5 -1
4 3/13/2011 15:00 9 0.37 0.28 7.9 7.6 4 59,840 59,460 1 1.4 1.4 -4
5 3/15/2011 12:45 7 0.24 0.32 6.9 8.6 -20 37,260 42,420 -12 1.2 1.5 -19
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The calibration results for the pond depths are summarized in Table 3-3. In general, goals were not met for
all events at both ponds. However, they were met for the longest, largest event, December 11, 2010, and
therefore, the calibration was deemed acceptable.
Table 3-3. 17th and 21st Street Pond Level Data Model Calibration Summary
Event Start date Duration
(hr)
Total
rainfall
(in.)
Peak 15-
min
rainfall
(in./hr)
Maximum depth (ft)
Calibrated Observed Difference
(%)
17th Street Pond
1 11/6/2010 01:40 49.3 0.89 0.16 1.02 0.99 -3
2 11/17/2010 11:35 26.2 0.41 0.24 n/a n/a n/a
3 11/30/2010 03:00 31 0.42 0.12 n/a n/a n/a
4 12/7/2010 20:45 77.4 1.28 0.36 0.95 1.30 38
5 12/11/2010 09:15 133.5 3.16 0.28 2.80 2.70 -4
6 12/24/2010 14:25 54.3 0.81 0.12 0.95 1.23 29
7 12/27/2010 11:45 28.8 0.27 0.08 0.45 0.39 -12
21st Street Pond
1 11/6/2010 01:40 49.3 0.89 0.16 3.00 2.05 -32
2 11/17/2010 11:35 26.2 0.41 0.24 1.38 1.19 -14
3 11/30/2010 03:00 31 0.42 0.12 1.97 1.45 -26
4 12/7/2010 20:45 77.4 1.28 0.36 3.07 3.15 3
5 12/11/2010 09:15 133.5 3.16 0.28 5.06 4.94 -2
6 12/24/2010 14:25 54.3 0.81 0.12 2.68 2.87 7
7 12/27/2010 11:45 28.8 0.27 0.08 1.44 1.60 11
n/a = not applicable as observed pond level data indicated no water in the pond during this event.
3.2 P Subbasin Model Calibration
The P subbasin model was calibrated with anecdotal flooding information and pump run times exported from
the SCADA data of the single pump at the West Main Street Pump Station. The anecdotal flooding infor-
mation includes reports of ponding on private property (because of private conveyance), flooding in the
vicinity of the existing pump station prior to its construction, and surcharging in the storm conveyance south
of West Main Street.
3.2.1 Methodology
Model calibration goals were set as a maximum 15 percent difference between simulated event volumes
and observed volumes. A comparison of peak flows was not a calibration goal as the observed pump station
peaks were limited by the pump capacity, which is not a useful measure of simulated peak flows.
The calibration effort focused on adjusting model parameters to match modeled and observed volumes at
the pump station, and corroborating observed flooding. A time series representing the observed volume was
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developed using pump run times from the SCADA data and assuming a pump capacity of 1,200 gallons per
minute (gpm).
Initial comparisons of observed and simulated volumes indicated the presence of base flow in the system. A
0.5-cubic-foot per second (cfs) flow was added to the node immediately upstream of the pump station to
represent this base flow contribution from the subbasin. In addition, initial comparisons of model results to
anecdotal flooding locations indicated more simulated flooding than observed. The simulated peak flows
were adjusted to match the observed flooding by reducing impervious area for the entire subbasin, and
adjusting the parameters for subcatchments with detention facilities. The P basin contains several large,
privately owned and maintained detention facilities that were not explicitly modeled because the details of
their design, construction, and operation/maintenance are unknown. Model parameters for the subcatch-
ments with detention facilities were adjusted in an effort to provide some simulated peak attenuation
attributed to the detention facilities. These adjustments included reducing basin width and routing some of
the runoff from impervious areas to pervious areas, instead of directly to the outlet. The parameter adjust-
ments made during calibration are described below:
1. Reduce impervious Reduce impervious Reduce impervious Reduce impervious aaaarea for all subcatchments. rea for all subcatchments. rea for all subcatchments. rea for all subcatchments. The model was calibrated to observed data by adjusting
the effective impervious area, which was estimated using the Sutherland equations and GIS-derived total
impervious area.
2. Reduce subcatchment width to account for detention facilities. Reduce subcatchment width to account for detention facilities. Reduce subcatchment width to account for detention facilities. Reduce subcatchment width to account for detention facilities. The model subcatchment width was
reduced by estimating the ratio between width and length as 0.0417. The ratio was derived from model
trial runs to produce sufficient peak flow attenuation to reduce simulated flooding in locations with no
reported flooding.
3. RoutRoutRoutRouteeee runoff from impervious areas to pervious areas to runoff from impervious areas to pervious areas to runoff from impervious areas to pervious areas to runoff from impervious areas to pervious areas to account for detention facilities. account for detention facilities. account for detention facilities. account for detention facilities. For subcatch-
ments with detention, 100 percent of runoff from the impervious surfaces was routed to pervious sur-
faces prior to being routed to the subcatchment outlet.
Parameter adjustments made during calibration to the area tributary to the pump station, which is about 15
percent of the P subbasin, were applied basin-wide. While land uses are similar for both the area tributary to
the pump station and other portions of the basin, these areas not tributary to the pump station should be
considered uncalibrated.
3.2.2 Results
The calibration results are summarized in Table 3-4. All events met the calibration goal, which indicates that
the calibrated model is effective at matching observations, and is a suitable tool for capital project develop-
ment. However, the calibrated model constitutes about 15 percent of the P subbasin, and the remaining
modeled area is considered uncalibrated. The uncertainty associated with the simulated flows for the
uncalibrated portion of the P subbasin should be accounted for when developing capital projects.
Table 3-4. W Main Street Pump Station Observed Data Model Calibration Summary
Event Start date Duration
(hr)
Total
rainfall (in.)
Peak 15-min
rainfall (in./hr)
Volume (ft3)
Calibrated Observed Difference
(%)
1 11/18/2013 00:10 24 1.12 0.2 111,400 103,700 7
2 12/1/2013 03:00 24 0.54 0.2 88,730 82,400 8
3 12/22/2013 00:05 24 0.44 0.08 86,610 81,300 7
4 1/2/2014 15:00 24 0.39 0.16 82,250 77,310 6
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Table 3-4. W Main Street Pump Station Observed Data Model Calibration Summary
Event Start date Duration
(hr)
Total
rainfall (in.)
Peak 15-min
rainfall (in./hr)
Volume (ft3)
Calibrated Observed Difference
(%)
5 1/11/2014 00:00 24 0.95 0.4 101,800 116,400 -13
6 1/29/2014 03:00 24 1.37 0.24 120,700 121,400 -1
7 2/23/2014 21:00 24 0.53 0.12 96,700 100,300 -4
9 3/2/2014 12:05 24 0.88 0.2 99,730 106,100 -6
10 3/16/2014 00:05 24 1.20 0.2 107,700 114,600 -6
11 3/29/2014 15:00 24 0.85 0.36 114,200 112,100 2
Table 3-5 summarizes the parameters adjusted to calibrate the P subbasin model.
Table 3-5. Final Hydrology Parameters Adjusted during Calibration
Parameter Subcatchments without
detention facility
Subcatchments with
detention facility
Percent impervious reduction -55% - 55%
Subbasin width W = area/L where length estimated as longest
flow path W = area/L, where W:L = 1:24
Subarea routing to outlet 100% of impervious area routed to
pervious areas
3.3 Model Evaluations
The models were used to determine appropriate flows or events for developing capital improvement projects
to address the identified problems.
3.3.1 Level of Service
The City’s stormwater LOS goals were used to evaluate modeled existing conditions and capital improvement
project scenarios:
1. The City seeks to manage stormwater runoff within the public right-of-way (ROW) to allow access to and
functionality of critical services such as hospitals, fire and police stations, Emergency Operations Center,
maintenance and operations, and city hall. The LOS to allow access to and functionality of critical ser-
vices translates to limiting surface water flooding that will disrupt the function of critical facilities (i.e.,
with floodwaters reaching the building structure, damaging the structure, and permitting no in-
gress/egress) with an annual chance of occurrence of no greater than 1 percent (i.e., an average recur-
rence interval of 100 years).
2. The City seeks to manage stormwater runoff within the public ROW to preserve mobility on major trans-
portation routes (i.e., arterial roads) and residential roads. The LOS for preserving mobility on major
transportation routes means limiting flooding disruption that inundates city roadways to an impassable
level with an annual chance of occurrence of no greater than 4 percent (i.e., an average recurrence in-
terval of 25 years).
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3. The City seeks to manage stormwater runoff from the public ROW to protect real property structures
(e.g., residences and businesses). The LOS for protecting real property structures means limiting flooding
(surface water from ROW runoff entering premises and damaging building structures) to an annual
chance of occurrence of no greater than 2 percent (i.e., an average recurrence interval of 50 years).
3.3.2 Flow Frequency Determination
For the newly calibrated PCSWMM models, a frequency analysis was completed for each model by perform-
ing a long-term simulation (from 1948 to 2014) to determine the 2 percent and 4 percent exceedance
storms (one-in-50-year and one-in-25-year flows, respectively). These storms were used as design storms to
identify ways to alleviate existing drainage problems through capital improvements that meet the LOS.
For the long-term simulations, the hydraulic networks of the models were modified so that there were no
restrictions to flow and there was free discharge at outfalls. As a result, all runoff could be conveyed without
substantial system storage and attenuation.
The event peak flows from the simulations were selected in PCSWMM with two event-based criteria: mini-
mum inter-event time (time between peak storms) of 12 hours and a flow threshold (varies by subbasin). The
peak flows were ranked, and the flow frequencies were established with the Cunnane plotting position
estimators. The events associated with the 25- and 50-year peak flows were used to size storm drainage
conveyance in order to meet the relevant LOS. The results of the flow frequency analysis for the BCDF and P
subbasin models are provided in Table 3-6 and Table 3-7, respectively.
Table 3-6. BCDF Subbasin Frequency Analysis Summary
Peak flow rank Event start date/time Peak event flow (cfs) Return period (yr)
1 10/20/2003 03:50 109.9 110.5
2 11/4/2006 14:45 104.9 41.5
3 11/4/1998 18:55 103.5 25.5
4 1/9/1990 04:10 100.5 18.4
5 11/18/2003 09:55 91.6 14.4
6 11/24/1990 05:00 91.1 11.8
7 10/5/1981 22:50 84.3 10.0
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Table 3-7. P Subbasin Model Frequency Analysis Summary
Event volume
rank
Peak flow
rank
Event start
date/time
Peak event flow
(cfs)
Event total volume
(MG)
Return period
(yr)
1 1 10/20/2003 09:20 21.8 8.1 110.1
4 2 11/5/2006 23:45 18.3 6.8 41.3
42 3 11/4/2006 15:15 17.9 2.0 25.4
16 4 1/9/1990 04:25 17.5 3.9 18.4
10 5 10/5/1981 23:10 16.61 5.4 14.4
13 6 11/24/1990 04:25 16.49 4.4 11.8
14 7 11/18/2003 10:15 14.88 4.3 10.0
For the WWHM models, the 25-year peak flows were estimated within the model using a Bulletin 17B flood
frequency method (U.S. Department of the Interior Geological Survey, 1982). These flows were used with
Manning’s equation of flow to size new and replaced pipe for capital improvement projects in the OO sub-
basin.
3.3.3 Drainage System Evaluation in the TT Subbasin
Frequent flooding has occurred in the vicinity of 37th Street NW and I Street NW, including shallow roadway
flooding, overtopping of the driveway leading to a power substation, and flooding over the Interurban Trail
south of 37th Street NW. Field observations and anecdotal information suggest that at least a portion of the
water originates from overbank flooding along Mill Creek near the 29th Street NW bridge. City maintenance
crews installed two 8-inch-diameter culverts (in addition to an existing 12-inch-diameter culvert) under the
power substation driveway in 2012 to try to reduce flooding, but the City indicates that they have been
ineffective.
The complexity of the drainage flow paths in the TT subbasin makes it difficult to quantify discharge frequen-
cy for drainage system features within the Mill Creek floodplain. For example, stormwater draining to the
ditches along the Interurban Trail and the 37th Street NW road originate not only from upland runoff, but
also from Mill Creek overflows near 29th Street NW. Discharges affected by Mill Creek overflows are particu-
larly uncertain because calibration efforts of the existing HEC-RAS model of Mill Creek resulted in simulated
water levels that did not match observed water level data. Therefore, hydraulic analyses were not performed
for evaluating the existing drainage system capacity in the TT subbasin. Alternatively, ranges of discharges
were estimated based on simulated existing system capacity and relative changes due to system improve-
ments.
The HEC-RAS model described in Section 2.1.3 was used to evaluate the capacity of the drainage ditch along
37th Street NW and potential improvements. Two scenarios were developed as described below:
· Existing conditions: no culvert under the interurban trail, one 12-inch-diameter reinforced concrete pipe
(RCP) culvert plus two 8-inch-diameter ductile iron pipes under the power substation driveway, and a 4-
foot minimum ditch bottom width
· Proposed conditions: one 1-foot (rise) by 3-foot (span) concrete box culvert under the Interurban Trail,
one 2-foot (rise) by 3-foot (span) concrete box culvert under the power substation driveway, and a 4-foot
minimum ditch bottom width
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Steady-state simulations were run for the two scenarios using discharges ranging from 1 to 10 cfs, where 10
cfs roughly reflects the existing capacity of the ditch system. For the simulated flows, the model indicates
that the proposed culvert replacements will decrease water surface elevations along the 37th Street NW
ditch system and no driveway or trail overtopping occurs (Figures 3-2 and 3-3).
Figure 3-2. Existing-conditions profiles along 37th Street NW ditch for discharges ranging from 1 to 10 cfs
Su
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Figure 3-3. Proposed-conditions profiles along 37th Street NW ditch for discharges ranging from 1 to 10 cfs
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Section 4: Annexation Area Desktop Evaluation
BC performed a review of the stormwater infrastructure in the City of Auburn’s West Hills OO drainage
subbasin to identify system easement and infrastructure gaps, and to develop capital improvement projects
to address two reported drainage issues. The OO subbasin is 1 of 18 drainage subbasins added to the City
of Auburn’s storm drainage system with the annexation of the West Hills and Lea Hill areas from King County
in 2008. The evaluation was completed in the 00 subbasin, and not other annexed subbasins, because the
system inventory had been completed and there were two identified drainage problems. The review was
based on information collected from site visits to the known problem areas, a desktop analysis using GIS,
and anecdotal information from City staff.
4.1 Methodology
Guidelines were developed so that the assessment could be performed consistently across the subbasin,
and could be applied across other subbasins in the future. The assessment was completed primarily in GIS
to identify potential gaps in the storm drainage system in the OO subbasin.
4.1.1 Assessment Guidelines
Guidelines were developed that reflect the Storm Drainage Utility service and planning expectations and are
intended to complement the LOSs identified in the 2015 Drainage Plan:
1. The City will seek to obtain easements for City-owned infrastructure (pipe, culvert, catch basin, or
manhole) located on private property.
2. When addressing an identified drainage problem, the City will seek to contain roadway runoff to the ROW
to the extent feasible.
3. When addressing an identified drainage problem or reviewing development plans, the City will field-
investigate potential infrastructure gaps and evaluate the need for additional drainage facilities.
4.1.2 GIS-Based Methodologies
Using the guidelines, potential easements and infrastructure gaps in the OO subbasin were identified using
City GIS data, 2012 aerial photography, and Google Earth software imagery. For potential easement gaps, a
spatial analysis was completed in GIS to identify City-owned infrastructure on private property.
To identify potential infrastructure gaps, subbasins were delineated to drainage outfalls. Then major drain-
age pathways were traced upstream based on topography (2-foot contour data), storm drainage infrastruc-
ture, road network, and aerial photos. Ten major pathways were identified. As pathways were traced, gaps
were identified. Paved roadways and drainage features (i.e., interior outfalls) not directly contributing to the
main drainage pathway were also reviewed. Paved roadways were observed from Google Earth and interior
outfalls are outfalls that discharge flows between subbasins and not out of the OO subbasin.
4.2 Results
The assessment revealed three types of gaps:
· easement gaps for public infrastructure on private property
· infrastructure gaps along major drainage pathways
· infrastructure gaps along minor drainage pathways
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The gaps and their occurrence in the OO subbasin are described below. Figure 4-1 shows the locations of
the identified gaps within the OO subbasin, as well as the subbasin delineation and subbasin outfalls, and
locations with known problems for which capital improvement projects are planned.
Easements. Of the 11 potential easement gaps identified, 2 are planned to be procured as part of two
proposed 6-year capital improvement projects in the 2015 Drainage Plan, Projects 5A and 5B (Figure 4-1).
Major Drainage Pathways. Gaps along major drainage pathways were identified downstream of two interior
outfalls. One is the drainage gap downstream of outfall 705-OO383. Based on topographic data, the channel
appears to be located on private property. However, the channel location is not mapped in GIS, and is not
observable from aerial photographs or Google Earth and should be field-confirmed. There are no reported
problems with the infall, outfall, or extent of the assumed channel. Another identified gap in a major drain-
age pathway is the area downstream of outfall 505-OO800. This outfall is the downstream end of a daylight-
ed pipe that discharges directly to the surface onto the property to the north. This infrastructure gap is being
addressed with Project 5B in the 2015 Drainage Plan.
Minor Drainage Pathways. Gaps in the minor drainage pathways include runoff from paved roadways or
where conveyance infrastructure ends and appears to discharge to adjacent parcels. No problems are
reported in areas with identify gaps in minor drainage pathways.
!(
!(
#*
#
#
#
#
#*
#
#
#
#
#*
#
#
#
CreekMill
5A
5B
505-OO591
505-OO612
505-OO585
704-OO979
605-OO800
806-NNN64
805-OO343
704-OO968
705-OO383
805-OO396
804-OO459
705-OO1036
806-PPP106
705-OO1084
SR 1
8
51
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PEASLEY CANYON RD S
55
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SR
1
6
7
W
S
T
N
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S 316TH ST
S 300TH PL
58
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S 328TH ST
52
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S 331ST
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S 300TH ST
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S 312TH ST
S 305TH ST
S 303RD PL
S 319TH ST
S 314T
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S
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S 302ND PL
53
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S 320TH ST
U
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S 322ND PL
52
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15TH ST NW
S 329TH PL
12TH CT NW
S 324TH PL
52
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S 321ST ST
64
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S 325TH ST
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S 324TH ST
53R
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COMPREHENSIVE STORM DRAINAGE PLAN
1 inch = 900 feet
April 2015
LEGEND
!(Storm Node
Storm Pipe
Storm Culvert
Storm Channel
#Subbasin Outfall
#*Interior Outfall
Storm Detention Site
!(Project Location and ID
Potential Easement
Potential Major Pathway Gap
Potential Minor Pathway Gap
Auburn City Boundary
Basin OO Boundary
Subcatchment boundary
P:
\
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Figure 4-1Subbasin OOPotential Drainage System GapsIdentified during Desktop Evaluation±
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4.3 Summary and Recommendations
This desktop evaluation is a high-level review of GIS data and aerial photography to identify potential gaps in
the storm drainage system recently annexed to the City of Auburn from King County. The evaluation was
completed for the OO subbasin where the storm drainage system was recently inventoried and there are two
reported drainage problems. Identified gaps are intended to assist planning efforts associated with devel-
opment review and investigative efforts should flooding problems arise. The evaluation was also used during
the development of two capital improvement projects:
· Project 5A, West Hills Drainage Improvements at S 330th Street and 46th Place S
· Project 5B, West Hills Drainage Improvements near S 314th Street and 54th Avenue S
The approach can be applied to other recently annexed areas when the storm drainage system inventory has
been completed or if a drainage problem is reported. If drainage problems are reported in other annexation
area subbasins, they could be addressed with one of the general improvements listed in Table 4-1.
Also, as the data inventory for the recently annexed areas is completed, the City may identify more easement
gaps. The City may want to develop a program to identify where easements are needed, and work with the
property owners to obtain easements.
Table 4-1. Potential Annexation Area Storm Drainage Improvements
Drainage improvement Benefit Implementation considerations
Pervious pavement Proactive for flow reduction
Most cost-effective for new
projects rather than rehabilitation
or as new BMP on existing roads
Low infiltrative soils will require an underdrain.
Not appropriate for roads with heavy vegetative debris or moss
growth.
ROW bioretention cells Proactive for flow reduction
Low infiltrative soils will require an underdrain.
Higher maintenance requirements.
Pipe and ditch extensions Connect problem area to the
existing system to provide flow
conveyance
Consider impact on downstream system and outfall.
Culvert inspection and
maintenance
Maintenance may be able to
improve the conveyance capacity
and address the issue
Inspection may reveal need for culvert replacement.
May result in additional downstream flows.
Culvert replacement Damaged or undersized culvert
could be replaced to reduce
flooding
May need to increase culvert size based on subbasin land use.
May result in changes to connecting infrastructure.
Ditchline grading Ditch conveyance capacity could
be restored
May result in additional downstream flow. Consider impact on
downstream system and outfall.
Asphalt berms or curb and
gutter
Berms could be used to direct flow
to the storm drainage system
May result in additional downstream flow. Consider impact on
downstream system and outfall.
Inlet placement or replace-
ment
Capturing flow at additional
locations or replacing a damaged
inlet could reduce flooding
May result in additional downstream flow. Consider impact on
downstream system and outfall.
Move pipe alignment from
private property to ROW
Provides City with access to its
infrastructure
If pipe is upsized when moved, conveyance capacity may be
increased and may result in additional downstream flow. Consider
impact on downstream system and outfall.
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Appendix C - H&H Modeling and Evaluation_v2.docx
Section 5: Summary
BC performed H&H modeling for nine known drainage problems within the City of Auburn’s stormwater
system. The preparatory work included updating existing PCSWMM models and building new models in
WWHM and HEC-RAS for smaller-scale analyses. Models were updated or developed with use of several data
sources including City GIS data; technical reports; record and construction drawings of stormwater infra-
structure; and regional agency climatology, soil, and topographic data.
BC performed calibration on subbasin models with observed data, the BCDF and P subbasin models. The
models were used to perform long-term model simulations to estimate peak flow events to perform flow
frequency analyses and establish design event flows for each modeled subbasin. The models were used to
develop planning-level capital improvement projects to address identified drainage problems that meet the
City’s LOS goals for storm drainage capacity.
After the City has completed the system inventory, a more comprehensive modeling effort can be completed
to evaluate City facilities with regard to the LOS.
BC also performed a review of the stormwater infrastructure in the annexation area West Hills OO drainage
subbasin to identify potential easement and infrastructure gaps and to develop capital improvement pro-
jects to address two reported drainage issues. The review was based on information collected from site visits
to the known problem areas, a desktop analysis using GIS, and anecdotal information from City staff. The
evaluation methods can be applied to other recently annexed areas after the storm drainage system inven-
tory has been completed or if a drainage problem has been reported.
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References
Brown and Caldwell, December 2009, Amended December 2011. City of Auburn Comprehensive Stormwater Drainage Plan.
Prepared for the City of Auburn by Brown and Caldwell.
EPA. 2010. Storm Water Management Model User’s Manual, Version 5.0. EPA/600/R-05/040. July 2010.
King County, 2003, LiDAR Digital Ground Model (DGM) Elevation and Hillshade: King County, King County, Washington.
Natural Resources Conservation Center (NRCS). June 1986. Urban Hydrology for Small Watershed, Technical Release 55 (TR-
55). United States Department of Agriculture, Natural Resources Conservation Service, Conservation Engineering Divi-
sion.
Reid Middleton. April 2011. Auburn Airport Storm Drainage System Inventory, Airport Drainage System Plan – Drawing Set.
Prepared for the City of Auburn by Reid Middleton, 728 134th Street SW, Suite 200, Everett, WA 98204.
Reid Middleton. December 2013. Auburn Airport Storm Drainage System Inventory, Storm Drainage System Problems and
Solutions Technical Memorandum. Prepared for the City of by Reid Middleton, 728 134th Street SW, Suite 200, Everett,
WA 98204.
Sutherland, R.C. 2000. Methods for estimating the effective impervious area of urban watersheds. Technical Note #58 from
Watershed Protection Techniques 2(1) 282–284.
United States Army Corps of Engineers (USACE). January 2010. Hydrologic Engineering Center (HEC), River Analysis System
(RAS), Version 1.4. United States Army Corps of Engineers, Hydrologic Engineering Center. Davis, California.
U.S. Department of the Interior Geological Survey. 1982. Guidelines for Determining Flood Flow Frequency, Bulletin #17B of
the Hydrology Subcommittee.
Comprehensive Storm Drainage Plan
D-1
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
Auburn Drainage Plan Public Rvw Draft.docx
Appendix D: SEPA Compliance