HomeMy WebLinkAboutAuburn Drainage Plan Final Dec09(v2)
CITY OF AUBURN COMPREHENSIVE
STORMWATER DRAINAGE PLAN
Prepared for
City of Auburn Public Works Department,
Auburn, Washington
December 2009
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Table of Contents COMPREHENSIVE STORMWATER DRAINAGE PLAN
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TABLE OF CONTENTS
LIST OF FIGURES........................................................................................................................................................iv
LIST OF TABLES...........................................................................................................................................................v
LIST OF ABBREVIATIONS...........................................................................................................................................vi
EXECUTIVE SUMMARY...............................................................................................................................................1
ES-1 LOS Goals.......................................................................................................................................................2
ES-2 Evaluation of the Stormwater Utility.....................................................................................................4
ES-3 Implementation Plan............................................................................................................................7
ES-3.1 6-Year and 20-Year CIP..........................................................................................................7
ES-3.2 Monitoring..............................................................................................................................10
ES-3.3 Programmatic Measures for NPDES Compliance.................................................................11
ES-3.4 Recommendations for Additional Studies and Activities........................................................12
1. INTRODUCTION.....................................................................................................................................................1-1
1.1 Purpose and Objectives....................................................................................................................1-1
1.2 Approach and Document Organization.............................................................................................1-2
2. BACKGROUND......................................................................................................................................................2-1
2.1 Stormwater Utility..............................................................................................................................2-1
2.1.1 Organizational Structure.......................................................................................................2-2
2.1.2 Funding Mechanisms............................................................................................................2-3
2.2 Development Code and Design Standards Update..........................................................................2-5
2.3 Regulatory Considerations................................................................................................................2-6
2.3.1 Growth Management Act......................................................................................................2-7
2.3.2 Phase II Municipal Stormwater Permit..................................................................................2-8
2.3.3 Governmental Accounting Standards Board.........................................................................2-9
3. UTILITY POLICIES AND LEVEL OF SERVICE GOALS........................................................................................3-1
3.1 Level of Service Goals within Storm Drainage Utilities.....................................................................3-1
3.2 Levels of Service..............................................................................................................................3-2
3.2.1 Incorporation of Existing Comp Plan Storm Drainage Policies.............................................3-2
3.2.2 Levels of Service..................................................................................................................3-3
4. DRAINAGE SYSTEM..............................................................................................................................................4-1
4.1 Natural Drainage...............................................................................................................................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......................................................................................................4-4
4.1.6 Geology and Groundwater....................................................................................................4-5
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4.1.7 Soils and Runoff Potential....................................................................................................4-5
4.1.8 Land Use and Development.................................................................................................4-6
4.1.9 Flood Hazard Mapping.........................................................................................................4-7
4.2 Stormwater Drainage Infrastructure..................................................................................................4-7
4.3 Critical Facilities................................................................................................................................4-9
4.4 Water Quality..................................................................................................................................4-10
4.4.1 Existing Water Quality Conditions.......................................................................................4-10
4.4.2 Water Quality Regulatory Compliance................................................................................4-11
4.5 Existing Drainage Problems............................................................................................................4-11
4.6 Potential Future Drainage Problems...............................................................................................4-13
5. EVALUATION OF THE STORMWATER UTILITY..................................................................................................5-1
5.1 Hydraulic Investigation......................................................................................................................5-2
5.1.1 Review of Existing Model......................................................................................................5-2
5.1.2 Modeling Methodology..........................................................................................................5-3
5.2 Asset Life-Cycle Investigation...........................................................................................................5-4
5.2.1 Economic Life Analysis of Drainage Pipes...........................................................................5-5
5.2.2 Pump Station Condition Assessment....................................................................................5-6
5.3 Environmental Investigation..............................................................................................................5-7
5.4 Maintenance and Operations Investigation.......................................................................................5-8
6. CAPITAL IMPROVEMENTS...................................................................................................................................6-1
6.1 Project Prioritization..........................................................................................................................6-5
6.2 Ongoing Drainage Projects...............................................................................................................6-5
6.3 Proposed Drainage Projects.............................................................................................................6-7
6.4 Programmatic and Long-Term Drainage Planning Projects............................................................6-35
6.5 Repair and Replacement................................................................................................................6-36
6.5.1 Economic Life-Cycle Analysis Results................................................................................6-36
6.5.2 Pipes Identified for Intervention..........................................................................................6-37
6.5.3 Pipes Identified for Conditional Assessment.......................................................................6-38
6.5.4 Recommended Improvements for Economic Life-Cycle Analyses.....................................6-38
7. IMPLEMENTATION PLAN......................................................................................................................................7-1
7.1 6-Year and 20-Year CIP...................................................................................................................7-1
7.2 Monitoring.........................................................................................................................................7-4
7.2.1 Precipitation Monitoring........................................................................................................7-4
7.2.2 Flow Monitoring....................................................................................................................7-5
7.2.3 Water Level Monitoring.........................................................................................................7-5
7.2.4 Water Quality Monitoring......................................................................................................7-6
7.2.5 Monitoring Costs...................................................................................................................7-7
7.3 Programmatic Measures for NPDES Compliance............................................................................7-7
7.4 Recommendations for Additional Studies and Activities...................................................................7-8
7.4.1 Continue System Inventory...................................................................................................7-9
7.4.2 Update Criticality Database..................................................................................................7-9
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7.4.3 Risk Assessment: Asset Vulnerability Analysis..................................................................7-11
7.4.4 Evaluate Maintenance and Operations Program................................................................7-11
7.4.5 Incorporate Sustainability...................................................................................................7-11
7.4.6 Assist with Mill Creek Restoration Studies..........................................................................7-13
7.4.7 Downtown Stormwater Control Study.................................................................................7-13
8. FINANCIAL PLAN...................................................................................................................................................8-1
8.1 Past Financial Performance..............................................................................................................8-1
8.1.1 Comparative Financial Statements.......................................................................................8-1
8.2 Financial Plan...................................................................................................................................8-4
8.2.1 Utility Fund Structure............................................................................................................8-4
8.2.2 Financial Policies..................................................................................................................8-5
8.2.3 Capital Funding Plan............................................................................................................8-7
8.3 Available CIP Funding Assistance and Financing Resources..........................................................8-9
8.3.1 Utility Resources...................................................................................................................8-9
8.3.2 Outside Resources.............................................................................................................8-11
8.4 Financial Forecast...........................................................................................................................8-14
8.4.2 Financial Forecast..............................................................................................................8-14
8.4.3 City Funds and Reserve Balances......................................................................................8-16
8.5 Rate Structures...............................................................................................................................8-16
8.5.1 Existing Retail Rates...........................................................................................................8-16
8.5.2 Projected Retail Rates........................................................................................................8-17
8.6 Affordability.....................................................................................................................................8-17
8.7 Conclusion......................................................................................................................................8-18
9. LIMITATIONS.........................................................................................................................................................9-1
Report Limitations.................................................................................................................................................9-1
REFERENCES.....................................................................................................................................................REF-1
APPENDIX A: WESTERN WASHINGTON PHASE II MUNICIPAL STORMWATER PERMIT
APPENDIX B: GREEN RIVER PUMP OPERATIONS PROCEDURES PLAN
APPENDIX C: 2009 STORMWATER MANAGEMENT PLAN
APPENDIX D: SYSTEM INVENTORY AND MODELING
APPENDIX E: FLOW MONITORING PLAN
APPENDIX F: ECONOMIC LIFE ANALYSIS
APPENDIX G: PUMP STATION CONDITION ASSESSMENT
APPENDIX H: PHASE II NPDES STORMWATER PERMIT COMPLIANCE WORK PLAN
APPENDIX I: REVIEW OF OPERATION AND MAINTENANCE
APPENDIX J: PLANNING-LEVEL COST ASSUMPTIONS
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LIST OF FIGURES
Figure ES-1. Sub-basin drainage areas prioritized for evaluation and inventory......................................................5
Figure ES-2. Timeline for NPDES Permit compliance............................................................................................12
Figure 2-1. Public Works Department staff organizational chart...........................................................................2-3
Figure 4-1. Natural drainage features of the city of Auburn.................................................................................4-15
Figure 4-2. Drainage sub-basins for the Auburn stormwater utility......................................................................4-17
Figure 4-3. Surface geology in the vicinity of the Auburn stormwater utility........................................................4-19
Figure 4-4. Hydrologic soil groups for soils in the vicinity of the Auburn stormwater utility..................................4-21
Figure 4-5. Land use designations for the city of Auburn (Comp Plan, 2008).....................................................4-23
Figure 4-6. Sub-basin priorities for system inventory..........................................................................................4-25
Figure 4-7. Drainage infrastructure for the Auburn stormwater utility..................................................................4-27
Figure 4-8. City and storm drainage critical facilities for the city of Auburn.........................................................4-29
Figure 4-9. Observed drainage problem locations for the Auburn stormwater utility...........................................4-31
Figure 4-10. City of Auburn downtown area and urban center............................................................................4-33
Figure 5-1. Example of annualized cost of ownership with minimum highlighted in red (age 23).........................5-6
Figure 6-1. Project locations, stormwater utility Capital Improvement Program....................................................6-3
Figure 6-2. Proposed capital improvements at Auburn Way S pump station, Phase 1 (CIP Project 11A)..........6-11
Figure 6-3. Proposed bypass piping at 2nd and G Streets (CIP Project 12).......................................................6-17
Figure 6-4. Proposed capital improvements to relieve flooding at 30th Street NE (CIP Project 13A and B).......6-21
Figure 6-5. Proposed capital improvements at West Main Street (CIP Project 14).............................................6-25
Figure 6-6. Proposed capital improvements at 296th Street pond in West Hill area (CIP Project 15A and B)....6-29
Figure 6-7. Proposed capital improvements at Bry’s Cove Pond in West Hill area (CIP Project 16A and B)......6-33
Figure 6-8. Future annual spending for repair and replacement given calculated optimal timing........................6-37
Figure 6-9. Relative criticality of stormwater drainage pipes identified for condition assessment.......................6-24
Figure 7-1. Annual costs for 6-year CIP................................................................................................................7-3
Figure 7-2. Timeline for NPDES Permit compliance.............................................................................................7-8
Figure 7-3. Distribution of pipe ages based on the City's current criticality database..........................................7-10
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LIST OF TABLES
Table ES-1-1. LOS Goals.........................................................................................................................................2
Table ES-1-2. Project Cost Summary for 6-Year and 20-Year CIP..........................................................................9
Table ES-1-3. Proposed Flow Monitoring Sites......................................................................................................10
Table 2-1. 2009 and 2010 Utility Rates for Storm Drainage Service.....................................................................2-4
Table 2-2. Federal, State, and City Regulations and Programs Relevant to the Auburn Stormwater Utility.........2-6
Table 3-1. LOS Goals............................................................................................................................................3-4
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 the Auburn..............................................................4-7
Table 4-3. Stormwater Drainage Infrastructure Summary.....................................................................................4-9
Table 4-4 Critical Facilities..................................................................................................................................4-10
Table 4-5. List of Known High-Priority Drainage Problems.................................................................................4-12
Table 5-1. City of Auburn Stormwater Drainage Pump Station Inventory.............................................................5-6
Table 6-1. Summary of Ongoinga Capital Improvement Projects..........................................................................6-6
Table 6-2. Summary of Ongoing and Long-Term Programs to Address Drainage Infrastructure........................6-35
Table 7-1. Annual Project Cost Summary for 6-Year CIP.....................................................................................7-2
Table 7-2. Cost Summary for 20-Year CIP............................................................................................................7-4
Table 7-3. Proposed Flow Monitoring Sites...........................................................................................................7-5
Table 7-4. Proposed Water Level Monitoring Sites...............................................................................................7-6
Table 8-1. Statement of Revenues, Expenses, and Changes in Fund Net...........................................................8-2
Table 8-2. Statement of Net Assets......................................................................................................................8-3
Table 8-3. 2009–2014 Stormwater CIP.................................................................................................................8-7
Table 8-4. 2009-2019 Capital Financing Plan.......................................................................................................8-9
Table 8-5. Current System Development Charge Schedulea ..............................................................................8-10
Table 8-6. Financial Forecast..............................................................................................................................8-15
Table 8-7. Cash Balance Summary.....................................................................................................................8-16
Table 8-8. Existing Retail Stormwater Rates.......................................................................................................8-17
Table 8-9. Affordability Test................................................................................................................................8-18
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COMPREHENSIVE STORMWATER DRAINAGE PLAN
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LIST OF ABBREVIATIONS
ac-ft acre-feet
ACC Auburn City Code
AKART all known, available, and reasonable methods of prevention, control, and treatment
BCE business case evaluation
BMP best management practice
CCTV closed circuit television
CERB Community Economic Revitalization Board
cfs cubic feet per second
CIP Capital Improvement Program
CMMS computerized maintenance management system
Comp Plan Comprehensive Plan for the City of Auburn (Land Use Plan)
CTED Department of Community, Trade, and Economic Development
CWA Clean Water Act
DUC designated urban center
Ecology Washington State Department of Ecology
EPA Environmental Protection Agency
ERP Ecosystem Restoration Project
ESA Endangered Species Act
ESU equivalent service unit
GASB Governmental Accounting Standards Board
GIS geographic information system
GMA Growth Management Act
GO general obligation
HPA hydraulic project approval
IDDE illicit discharge detection and elimination
LFC local facilities charge
LID low impact development
LOS level of service
M&O maintenance and operations
MEP maximum extent practicable
MHI median household income
MS4 municipal separate storm sewer system
NGVD29 National Geodetic Vertical Datum 1929
NAVD88 North American Vertical Datum 1988
NOAA National Oceanic and Atmospheric Administration
NPDES National Pollutant Discharge Elimination System
NSF non-single-family
PLC programmable logic controller
PWTF Public Works Trust Fund
R&R repair and replacement
RCW Revised Code of Washington
ROW right-of-way
RSI required supplementary information
SAMP Special Area Management Plan
SCADA supervisory control and data acquisition
SDC system development charge
COMPREHENSIVE STORMWATER DRAINAGE PLAN
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SEPA State Environmental Policy Act
SMP Shoreline Master Program
SOS Save Our Streets
sq ft square feet
SR State Route
SWMP Stormwater Management Program
TMDL total maximum daily load
UGA urban growth area
ULID Utility Local Improvement District
USACE U.S. Army Corps of Engineers
WRIA Water Resource Inventory Areas
ES-1
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P:\135347 Auburn Drainage Phase II\009 Storm Drainage Comprehensive Plan\Final\Auburn Drainage Plan Final Dec09(v2).doc
CITY OF AUBURN COMPREHENSIVE
STORMWATER DRAINAGE PLAN
EXECUTIVE SUMMARY
This Comprehensive Stormwater Drainage Plan (Drainage Plan) for the city of Auburn (City)
updates the previous plan, which was completed in August 2002. An update to the 2002 Drainage
Plan was necessary for several reasons including new regulatory requirements, continued growth and
development, the need for a comprehensive system inventory and an update of the list of projects
for the Capital Improvement Program (CIP). This comprehensive plan contains time frames which
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.
The purpose of this new Drainage Plan is to guide the City’s Stormwater Drainage utility with
respect to future activities and improvements for the stormwater drainage system. An asset
management approach was used to develop a work plan for the stormwater utility, consisting of the
following basic steps:
Review background information about the stormwater utility including the organizational
structure, funding mechanisms, and regulatory drivers (Chapter 2).
Examine City policies affecting the stormwater utility and develop specific level of service (LOS)
goals around those policies. LOS goals are policy- and community-based objectives for capital
facility infrastructure development, operation, maintenance, and other utility activities (Chapter 3).
Study and characterize the current and expected future conditions of the drainage system
(Chapter 4), including both natural and constructed drainage elements. The constructed drainage
system requires a detailed system inventory for use in analyses and asset management.
Evaluate the stormwater utility with respect to established LOS goals to identify gaps between
those goals and current or expected future service levels (Chapter 5). General types of evaluations
include hydraulic analyses of the drainage system, asset life-cycle analyses, environmental
assessments and investigations, review of maintenance and operations (M&O) practices, and
organizational investigations.
Develop alternatives to reduce or eliminate identified gaps in service. Such alternatives consist of
both capital improvement projects and non-structural, programmatic activities.
Recommendations for capital improvements are based on detailed hydraulic modeling and
criticality-based economic life-cycle analyses (Chapter 6).
Establish the implementation plan, which is the future work plan for the utility (Chapter 7).
Capital improvement projects from Chapter 6 are prioritized and placed into 6- year and 20-year
CIP time frames. Non-capital works recommendations such as flow monitoring, regulatory
Executive Summary COMPREHENSIVE STORMWATER DRAINAGE PLAN
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compliance, M&O improvements, and additional asset management activities are also included in
the implementation plan.
Provide a financial plan to support the costs associated with proposed improvements.
The following sections summarize the development of the Drainage Plan and outline the
recommendations contained in the implementation plan.
ES-1 LOS Goals
LOS goals provide a framework for the 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 to use in evaluating how well those goals are being met. Descriptions of LOS goals for the
stormwater utility were developed for this Drainage Plan; LOS goals are based on existing City
policies as presented in the 2008 Comprehensive Plan for the City of Auburn (Comp Plan). LOS
goals and associated City polices are listed in Table ES-1.
Table ES-1. LOS Goals
Item Policy description 2009 Drainage Plan LOS goal
Policy category: protection of public safety and property
1 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. See policy
EN-57.
Surface water flooding will disrupt the function of critical facilities (i.e., with
floodwaters reaching the building structure, damaging the structure, and
permitting no ingress/egress) with an annual chance of occurrence of no greater
than 1 percent (i.e., an average recurrence interval of 100 years).
2 The City shall seek to manage stormwater runoff within
the city-owned public ROW to preserve mobility on
major transportation routes (i.e., arterial roads) and
residential roads. See policy EN-57.
Flooding disruption that inundates the city roadways to an impassable level with
an annual chance of occurrence of no greater than 4 percent (i.e., an average
recurrence interval of 25 years).
3 The City shall seek to manage stormwater runoff from
the public ROW to protect real property structures
(e.g., residences and businesses). See policy EN-57.
Flooding (surface water from ROW runoff entering premises and damaging
building structures) with an annual chance of occurrence of no greater than 2
percent (i.e., an average recurrence interval of 50 years).
4 The City shall seek to prevent erosion and landslides
related to construction, operation, and maintenance of
the publicly owned drainage system. See polices CF-
48 and EN-3.
No erosion or landslides resulting from public drainage infrastructure
construction, operation, or maintenance. No direct stormwater discharge will be
permitted on steep slopes.
5 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. See policies CF-40 and
EN-17.
The City will 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. Activities will
be documented within the City's CartêGraph computerized maintenance
management system (CMMS).
Policy category: reliability of the storm drainage infrastructure
6 The City shall seek to maintain an asset criticality
database to be used in prioritizing asset maintenance
and repair and replacement (R&R). See policies CF-40
and EN-17.
The existing criticality database (developed for this 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 CartêGraph CMMS.
Executive Summary COMPREHENSIVE STORMWATER DRAINAGE PLAN
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Table ES-1. LOS Goals
Item Policy description 2009 Drainage Plan LOS goal
7 The City shall seek to perform condition assessments
of critical assets. See policies CF-40 and EN-17.
The City will develop and implement a condition assessment schedule for 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 condition assessment activities
will be documented in the CMMS.
8 The City shall seek to repair or replace system assets
before they exceed their economic lives. See policies
CF-40 and EN-17.
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.
9 The City shall seek to conduct maintenance activities
in accordance with a schedule developed to comply
with Washington State Department of Ecology
(Ecology) requirements and asset criticality. See
policies CF-40, EN-12 and EN-17.
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 outfalls). The experience of M&O
staff should be incorporated into the criticality database (see item 6 above).
Inspection activities will be documented in the CMMS.
Policy category: protection of the environment
10 The City shall seek to provide pump redundancy and
backup power generators or dual power feeds at City-
owned and -operated drainage pump stations. See
policy EN-17.
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.
11 The City shall seek to comply with all federal, state,
and local regulations in operation and maintenance of
the City’s storm drainage infrastructure. See policy EN-
12.
Meet all relevant regulatory requirements. Examples include complying with
NPDES Phase II inspection cycle, performing all necessary ESA consultations,
etc.
12 The City shall protect and preserve existing native
vegetation and drainage courses while maintaining
their conveyance capacity. See policy CF-45.
No net loss of native vegetation (in terms of area) or natural drainage systems (in
terms of stream length) to maintain existing habitat along drainage ways. This
does not apply to constructed or maintained facilities.
13 The City shall seek to reduce runoff volumes and
pollutant loads associated with new development. See
policy EN-15.
The City will comply with the elements of the NPDES Phase II Stormwater
Permit and implement an Ecology-equivalent stormwater manual for new
development. Identify appropriate areas and provide guidance for the
implementation of low impact development (LID) drainage management
measures by new development and redevelopment (including City-owned
properties).
14 The City shall seek to evaluate drainage utility activities
to emphasize sustainability. See policy CF-40.
City staff will identify specific areas to measure sustainability by examining how
storm drainage utility operations affect energy resources and natural resources.
City staff will benchmark practices and log changes over the next planning
period.
15 The City shall continue to participate in regional storm
drainage, water resources, and water quality planning
efforts. See policies CF-48 and EN-12.
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.
Policy category: storm drainage utility financial performance
16 The City shall continue to fund and provide storm
drainage services through the existing storm drainage
utility. See policy CF-40.
The City's storm drainage utility should be responsible for implementation,
maintenance, and operation of the City's drainage system. Goal of 100% of cost
of drainage service delivery recovered via storm drainage utility fees. Seek
opportunities to provide public drainage benefits through grants funding and/or
development partnerships where applicable.
17 The City shall assess appropriate rates and system
development charges (SDCs) to fund the ongoing
maintenance, operation, and capital expenditures of
the utility, in accordance with the Drainage Plan. See
policy CF-41.
Periodic cost of service studies shall be completed to reassess the monthly
service fees and SDCs. Updates to coincide with 6-year CIP updates.
Executive Summary COMPREHENSIVE STORMWATER DRAINAGE PLAN
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Table ES-1. LOS Goals
Item Policy description 2009 Drainage Plan LOS goal
18 The City shall seek to track the cost of claims as a
metric. See policy CF-41.
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 define methods to reduce the risk of claims and
measure its progress at reducing the overall cost of claims.
19 The City shall seek to track elements of CIP
implementation: (1) individual schedule, (2) project
budget accuracy, and (3) overall performance in
implementing CIP. See policies CF-40 and CF-48.
City staff will summarize current methods for CIP implementation to create a
baseline (e.g., schedule and costs) against which future improvements can be
evaluated.
Policy category: customer satisfaction
20 The City shall seek to evaluate and strive to maintain
customer satisfaction with drainage utility service
delivery. See policy CF-40.
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 Stormwater NPDES Phase II
Permit requirements for public education and outreach.
21 The City shall seek to build, operate, and maintain
drainage utility infrastructure within an overarching goal
of protecting employee safety. See policy CF-40.
City staff will track health and safety incidents to create a baseline against which
to evaluate future improvements.
ES-2 Evaluation of the Stormwater Utility
A series of investigations were conducted to evaluate the stormwater utility and identify gaps
between existing service levels and the desired LOS goals. Such investigations typically fall into one
of five basic types of investigations: hydraulic, economic (i.e., asset life-cycle), environmental, or
maintenance and operations. The following paragraphs summarize the evaluations conducted as part
of the development of this Drainage Plan:
Hydraulic. The City’s existing XP-SWMM1 hydraulic model was reviewed and compared with
infrastructure data contained in the City’s geographic information system (GIS). Data gaps and
inconsistencies between the two data sources led the City to embark on an effort to develop an
improved and more-detailed drainage system inventory, which would serve as the basis for a new
hydraulic model. MIKE URBAN2 software was selected for this purpose because it would be
consistent with the City’s sanitary sewer model and uses common GIS data formats. A complete
update of the City’s drainage system inventory will require a substantial effort; thereby
necessitating a phased approach. The system was divided and prioritized for evaluation by
drainage sub-basin (Figure ES-1). This Drainage Plan focuses on high- and medium-priority sub-
basins. Low-priority sub-basins and sub-basins without a designated priority were deferred to
future efforts (see recommendations future activities in the implementation plan).
1 XP-SWMM is a program developed by XP Software for hydrodynamic modeling of stormwater and wastewater
collection systems. XP-SWMM uses the SWMM5 engine, which is public domain modeling software distributed by the
EPA. Information about XP-SWMM software can be found at http://www.xpsoftware.com/products/xpswmm/.
2 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.
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COMPREHENSIVE STORMWATER DRAINAGE PLAN
1 inch = 5,280 feet
December 2009
P:\135347 Auburn Drainage Phase II\GIS\MXD\Drainage Plan Figures\AurburnStorm_FigES-1(priorities).mxd
FIGURE ES-1
SUB-BASIN DRAINAGE AREAS
PRIORITIZED FOR EVALUATION
AND INVENTORY
0.500.5
Miles
[N
L E G E N D
Roadway
Auburn City Boundary
Evaluation/Inventory Priority
High
Medium
Low
Future Efforts
NOTES:
Sub-basin delineations are based on the 2002 Drainage Plan and are used for reference.
Gray areas appearing as gaps between sub-basins are areas adjacent to rivers that drain directly to those rivers.
back of Figure ES-1.
Executive Summary COMPREHENSIVE STORMWATER DRAINAGE PLAN
ES-7
Use of contents on this sheet is subject to the limitations specified at the end of this document.
Economic. Asset life-cycle investigations also require detailed system information. An economic
life analysis of the utility’s drainage pipes was conducted using available data in system inventory.
Those data within the system inventory that are used for such an analysis (e.g., pipe material, pipe
age, and proximity to critical facilities) form what is referred to as a criticality database. The
economic life analysis examined the probability of failure and the costs associated with a failure
to determine the optimal timing for intervention and to prioritize maintenance activities.
Environmental. Environmental investigations centered on regulatory compliance for the
National Pollutant Discharge Elimination System (NPDES) Permit. A legal requirements analysis
was conducted and stormwater management programs, codes, standards, processes, and
documentation protocols were assessed, including interviews with appropriate staff. The results
were used to identify gaps and develop potential actions to comply with the NPDES Permit
conditions over the 5-year Permit period. Some policy issues and potential compliance strategies
were also identified. A compliance work plan was developed, as well as Stormwater Management
Plans (SWMPs) for 2008 and 2009.
Maintenance and operations. A preliminary evaluation of M&O activities was conducted for
this Drainage Plan. Current ditch and drainage line maintenance activities were examined and the
City’s CartêGraph computerized maintenance management system (CMMS) software was
reviewed. Recommendations were made for ways to optimize M&O activities including a list of
key elements for the development of a structured M&O program.
ES-3 Implementation Plan
The implementation plan brings together information from the system evaluation to form a work
plan of future activities for the stormwater utility. The implementation plan consists of 6-year and
20-year CIP, 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. Most of the capital improvement projects are designed
to mitigate flooding in these areas and are expected to provide substantial and immediate benefits.
The 6-year CIP also contains ongoing drainage projects developed prior to, or during the
completion of this Drainage Plan and ongoing programmatic efforts, such as the drainage utility’s
participation in the Save Our Streets (SOS) 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 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.
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
Executive Summary COMPREHENSIVE STORMWATER DRAINAGE PLAN
ES-8
Use of contents on this sheet is subject to the limitations specified at the end of this document.
programmatic activities, such as developing a repair and replacement schedule that examines asset
inspection and maintenance results to identify assets that are nearing the end of their economic life.
The 20-year CIP adds projects identified through asset life-cycle investigations, or projects that
address long-term regional issues (e.g., the impact of Mill Creek aggradation on storm drainage
discharge capacity).
Table ES-2 lists all 19 capital improvement projects included in this Drainage Plan and lays out
annual expenditures for the 6-year and 20-year CIP time frames.