HomeMy WebLinkAbout01-25-2017 HEARING EXAMINER AGENDA1,504.7
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1/4/2017Printed Date:
Map Created by City of Auburn eGIS
Imagery Date: May 2015
Information shown is for general reference
purposes only and does not necessarily
represent exact geographic or cartographic
data as mapped. The City of Auburn makes no
warranty as to its accuracy.
Parcels
Street Centerlines
Zoning
C1 Light Commercial District
C2 Central Business District
C3 Heavy Commercial District
C4 Mixed Use Commercial
CN Neighborhood Shopping District
DUC Downtown Urban Center
EP Environmental Park District
I Institutional Use District
Lakeland Hills South PUD
LF Airport Landing Field District
M1 Light Industrial District
M2 Heavy Industrial District
P1 Public Use District
PUD Planned Unit Development
R1 Residential 1 DU/Acre
R5 Residential 5 DU/Acre
R7 Residential 7 DU/Acre
R10 Residential 10 DU/Acre
R20 Residential 20 DU/Acre
Residential Conservency
RMHC Residential Manufactured/Mobile Home Units
RO Residential Office District
RO-H Residential Office District (Hospital)
TV Terrace View
UNC Unclassified Use District
Exhibit 4
Conceptual Storm Drainage Report
To View Exhibit 4, please access the SFTP Site:
Access the City of Auburn Web Transfer Tool (SFTP) by going to
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Log into the SFTP site using the following user name and password:
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Password: P1ckm3up
Click on the PLT14-0006 folder and view sub-folder Exhibit 4 Conceptual Storm
Drainage Report
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know.
Exhibit 8
DRAFT EIS
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Log into the SFTP site using the following user name and password:
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Exhibit 9
FINAL EIS
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Log into the SFTP site using the following user name and password:
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PRE-APPLICATION MEETING SUMMARY
This summary reflects the information provided at the pre-application meeting, and is
intended to assist the applicant with preparing plans for submittal to the City. Further
information provided by the applicant may influence plan reviewers as permit
applications and development plans are submitted for review. Additional information
may be needed to complete the project to applicable City standards. Please note that
this review is based on current codes adopted at the time of the meeting.
These notes will be kept on file for a period of two years.
File: PRE08-0045
Project : Park Ridge (Kersey 3 Div. 3)
Applicant(s): Jeff Mann, Apex Engineering for Duty
Meeting Date: August 27, 2008
Site Address: Off Evergreen Way SE just east of Lakeland Hills
Parcel #: 3221059010, 3221059011, 3221059030, 3221059037
Proposal: Subsequent to the meeting the proposal has been revised
from 243 lots to a total of 256 lots though the approval of a
Development Agreement and Plat.
City Representatives
Karen Scharer, Senior Planner, PB&C, 253-804-3111, kscharer@auburnwa.gov
Elizabeth Chamberlain, Principle Planner, PB&C, 253-931-3092
Ingrid Gaub, Assistant City Engineer, Public Works, 253-804-3113
Monty Bakken, Development Engineer, Public Works, 253-804-5073
Mike Lee, Valley Regional Fire Authority, 253-931-3060, mike.lee@vrfa.org
Also for reference:
Jan Weaver, Building Department, 253-804-5092, jweaver@auburnwa.gov
Joe Welsh, Traffic, Public Works 253 804-5050 jwelsh@auburnwa.gov
Submittal of the Development Agreement Subsequent to the Pre-App Meeting:
The applicant submitted a letter on Oct. 9, 2008 which asserts that they “entered into
formal negotiations with the City for a development agreement” prior to July 1, 2007.
Their main argument was that the City entered into formal negotiations when we held
various meetings with them.
The City agrees that there were formal negotiations before that date, therefore the
applicant was not be required to hold a pre-application public meeting prior to filing of a
Development Agreement application (ACC 14.21.045 B). The applicant filed for a
PRE08-0045
November 3, 2008
Page 2
Development Agreement on Monday, Oct. 13th before the effective date of Ord. # 6187
(Oct. 14th).
The City’s Justification for allowing the applicant to file without a Pre-application Public
Meeting is as follows:
• EIS – 2004/2005
• The applicant funded part of the EIS for Kersey 3. This is considered “Formal
Negotiations”
• EIS “formally” considered two alternatives with smaller lot sizes yielding higher
densities
• EIS “public meetings” were held by City.
• PUD District Repealed on April 11, 2006 - City eliminated the opportunity for
processing as a PUD. (PUD’s are discussed in the EIS).
• Property will be dedicated for Evergreen Way before opening of the street.
• Right of way dedication is one of the “Formal Negotiations” considered allowing
for future development.
• Utilities – An easement will be established for a storm pond prior to recording of
Div. 1 or 2. Establishing the easement is part of the “Formal Negotiations”
allowing for future development.
• Evergreen Way - Applicant was involved with road engineering for road
entrances. Applicant met a number of times with City staff regarding road
design. Meetings are considered as “Formal Negotiations”.
PRE-APP COMMENTS BY CITY STAFF: With the submittal of the application for
Development Agreement (DA), no further “preapplication” meetings or discussions were
held. Comments are based on the pre-application submittal. Most of the comments are
relevant to a future plat and minimum requirements of code and/or the need of
information. Comments do not reflect the subsequent submittal of the development
agreement. Please reference the DA file – MIS08-0017.
PB&C:
Planning:
1. This property referenced is zoned R-1 Single Family Residential District - ACC
18.12. The minimum lot size is 8,000 square feet, however alternative standards for
lot size can be established through a development agreement. This is allowed for
other standards as well.
2. Specifically, the Development Agreement must be reviewed in context of the DA
criteria for approval in ACC 14.21.030 A.:
“The city may consider a development agreement for an exclusively or
primarily residential project in order to provide enhanced flexibility to develop a
site through innovative and alternative development standards. A development
agreement should allow for a greater range of residential development scenarios,
provides for internal transfers of density, and may result in more dwelling units
than may be realized by using the existing standards of the existing zone. In
exchange for this enhanced flexibility, the city will require a development to be of
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REVISED Nov. 3, 2008
PRE08-0045
November 3, 2008
Page 3
significantly higher quality, generate more public benefit and be a more sensitive
proposal than would have been the case with the use of standard zoning or
subdivision procedures.”
It will be the applicant’s responsibility to demonstrate, to the city’s satisfaction,
that a development proposal achieves or is consistent with the following desired
public benefits and expectations in whole or in part:
1. Preservation of Natural Amenities. Preservation of desirable site
characteristics such as open spaces and the protection of sensitive
environmental features including steep slopes, mature trees, rivers, creeks,
wetlands, lakes and scenic views.
2. Pedestrian-Oriented Communities. Use of traffic management and
design techniques to reduce traffic congestion both within and in the vicinity of
the proposed development and to increase the potential use of alternative modes
of travel such as mass transit, pedestrian and bicycle traffic.
3. Land Use Efficiencies. Provide efficient and effective use of land, open
space and public facilities that result in lower development cost and make
housing more affordable.
4. Improved Transitional Areas. Improve the sensitive development of
transitional areas located between different land uses, environmentally sensitive
areas, and along significant corridors within the city.
5. Implementation of the Comprehensive Plan. Provide development that
is consistent with the goals and policies of the comprehensive plan.
6. Enhanced Design Features. Provide building and structural designs
that complement surrounding land uses and their environment. Design standards
should reflect quality site planning, landscaping and building architecture.
7. Creation of Public Amenities. Enhance parks and open spaces
consistent with the comprehensive park plan and nonmotorized plan.”
At this time the proposal offers few additional enhancements beyond required code.
Support for this proposal by City staff will require the applicant to demonstrate further
benefit to the City.
3. Narrow lot frontages do not readily accommodate separate driveways while still
providing sufficient space for street trees, water meters, street lights easily. The City
often finds conflict with specific street trees, sewer lines, and other utilities while also
considering sight distance at driveways. The applicant will need to demonstrate how
these requirements will be for this project.
4. Site cross sections are needed to graphically show site slopes for purposes of
evaluating proposal.
5. Address adequate backyard areas of double fronted lots, Lots 1-8, Lots 38-45 & 245-
252.
6. Clarify the alteration of grades within open space tracts and need for removal of
native vegetation.
7. The plan shows grading proposed however, city will need to critically review grades
to ensure that grading results in functional lots and minimizes or avoids the need for
individual grading permits at time of home construction.
8. Demonstrate the typical house design and final site grades of sloped lots for home
construction; Lots 113 -120, Lots 124-135.
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REVISED Nov. 3, 2008
PRE08-0045
November 3, 2008
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9. Park impact fees will be required for lots. The applicant will need to demonstrate that
the City agreed to a “credit” for 180 units which the applicant believes was
addressed under the Lakeland Special District Overlay. Please document the credit
believed to be granted by the city.
10. The existing plat file PLT00-0006 is vested and has been on hold for an extended
period of time. Typically plat applications are not placed on hold for more than 3-6
months. The City will address the future limits of that file in a separate letter.
Please contact me, Karen Scharer, Senior Planner at 253- 804-3111 if there are
questions regarding these comments.
Building
1. At the time of application for building permit(s), geotechnical report(s) will be required
for building construction.
Please contact Jan Weaver at 253-804-5092 if there are questions regarding these
comments.
PUBLIC WORKS
Sewer
1. The pre-application material contained insufficient detail to make specific
constructive comments related to the proposed sewer system. The applicant should
be aware that significant challenges are anticipated in providing access to the
downstream connection point (to be constructed under a separate FAC permit).
What appears to be a utility tract in the northeast portion of the development must be
sufficiently wide to allow access to sewer manholes and future replacement of sewer
lines.
2. Provisions should be made to allow the property owner to the north to extend the
sewer line from both north-south streets.
Water
1. There are two existing 12" waterlines (one transmission and one distribution line)
near the south end of the applicant's parcel along Evergreen Way SE. The applicant
shall connect to the distribution line for water service.
2. Whenever possible, provisions shall be made for looping all existing and new dead-
end mains associated with the project per Design Standard 7.01.1.2(E). The
applicant shall loop the main to the east at the very north end of the parcel through
the 49th Street SE right-of-way for connection to the future main proposed to extend
north from the proposed Wesley Court SE in the proposed Lakeland Hills Estates
development. The applicant shall also loop the main on Road G and connect to the
stub outs on Evergreen Way SE.
3 All fire hydrant assemblies shall be located within the public right-of-way or easement
in accordance with Standard Detail Water-07 and Design Standard 7.02(A).
4. The applicant's parcel is located within 4 different proposed water pressure zones.
The water system shall be designed to meet the 2001 Water Comprehensive Plan
criteria and standards for system distribution pressures: 35 psi minimum and 80 psi
maximum.
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REVISED Nov. 3, 2008
PRE08-0045
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5. Residential sites shall have water meters placed as close to the city water main as
possible with the distance not to exceed 50 feet, in landscape strips within the public
right-of-way or within a public utility easement per Design Standard 7.01.2.1(C). The
length of the service between the meter and the structure shall not exceed 150 feet
per Design Standard 7.01.2.1(F).
6. The Applicant's parcel is located within the critical area known as Ground Water
Protection Zone 4. The Applicant shall implement best management practices for
water resource protection per ACC 16.10.120(E)2.
Stormwater Facilities
This project will be required to meet all City standards for detention and water quality
treatment. The information provided in the pre-application packet does not contain
enough information for more detailed comments. However site topography and
proposed grading suggests in addition to the public storm drainage system a private
drainage system will be required to drain slopes and individual lots. The applicant will
need to submit a conceptual drainage plan and geotechnical report.
1. Conceptual Drainage Plan: This Division is requesting that a conceptual drainage
plan be provided to the City for review and approval. The plan shall include
preliminary on-site drainage facilities, and demonstrate that required setbacks,
required side slopes and aesthetic requirements (if an open drainage pond is
proposed) consistent with City standards can be accommodated on-site.
2. Drainage Analysis: This Division is requesting that additional information be
provided regarding the proposed method of on-site quality and quantity control. The
analysis shall include engineering level of water quality and quantity calculations
necessary to demonstrate that stormwater facilities consistent with City standards
can be accommodated on-site.
3. Downstream Analysis: Due to known conveyance limitations of the downstream
drainage system, a downstream analysis is required to adequately evaluate the
storm drainage impacts associated with this. The downstream analysis must
consider the existing conveyance system(s) for a minimum flow path distance of
one-quarter mile and beyond that, as needed, to reach a point where the project site
area constitutes less than 15% of the tributary area.
4. Landscaping Plan: This Division is requesting that additional information be provided
detailing the proposed landscaping of the storm drainage facility. A landscaping plan
with applicable cross-sections is required to demonstrate that aesthetic requirements
are consistent with City standards can be accommodated on-site.
5. Geotechnical Analysis: This Division is requesting that a geotechnical analysis
including soil log information, subsurface flow rates, and slope stabilization
recommendations be provided to the City for review and approval.
6. Hydrologic Wetlands Impacts: Additional information is needed to assess the
potential impacts of the proposed excavation and modification to the ground surface
proximate to the site wetlands through modification, reduction or elimination of
hydrologic support. An analysis of the potential hydrologic changes is necessary to
reduce and avoid wetland impacts. The analysis shall address a method for
maintaining existing hydrologic support of the wetlands, if necessary. The analysis
shall include a pre-developed analysis of the existing hydrologic rates and volumes
tributary to the wetlands, and post-developed rates and volumes from tributary areas
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REVISED Nov. 3, 2008
PRE08-0045
November 3, 2008
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required to replicate pre-developed conditions. A wetlands biologist shall be
consulted to verify the appropriate hydrologic support necessary to maintain existing
wetland function and value.
7. The storm drainage conveyance system required to manage upstream bypass
surface flows shall be routed through the project site and shall not be combined with
the proposed on-site storm drainage system. This system must be within public
right-of-way or tract. Maintenance access shall be provided to all structures
associated with this bypass system.
Transportation/Traffic
General
1. Additional detail should be provided for proposed traffic circle at intersection of
roads B and C/F (including emergency vehicle turning templates).
2. Sight distance triangles per city standards will be required as part of the preliminary
plat documents, especially at the intersection of "Road B" and Evergreen Way SE
related to the potential building locations within the plat.
3. Typical street cross sections per city standards should be provided on plat for all
streets and access lots (including proposed street classification).
4. Applicant will need to provide comprehensive utility layouts for preliminary plat
review.
5. The preliminary plat will need to address concerns with the proposed narrow lots
related to driveway separations, utility service line separations, street lighting, site
distance and street tree requirements to insure that the City's standards can be
met.
6. Portions of the proposed streets exceed the city's maximum vertical grade limit and
will require a deviation from standards. In a preliminary plat process, staff will make
a recommendation of deviations to the City Council but final decisions on deviations
will not be made until preliminary plat approval.
7. Portions of the proposed streets do not meet the city's minimum horizontal curve
radius and will require a deviation from standards. In a preliminary plat process,
staff will make a recommendation of deviations to the City Council but final
decisions on deviations will not be made until preliminary plat approval.
8. Access Tracts will need to meet City standards for pavement width, sidewalks and
turnaround requirements.
9. This proposed plat is dependant on improvements being completed by Kersey 3,
Divisions 1 and 2, and, if not completed by others, this proposed plat may be
required to complete these improvements.
B."Road B"
1. Traffic calming measures should be indicated for this street to mitigate possible
future through traffic and grade related speed issues.
2. Temporary turnaround must be provided at the end of "Road B."
C."Road D"
1. "Road D" will be subject to review and approval by the fire authority.
2. Applicant should consider proposing "Road D" as a privately owned and maintained
emergency access lane.
D."Road E"
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REVISED Nov. 3, 2008
PRE08-0045
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REVISED Nov. 3, 2008
1. "Road E" connection to Evergreen Way SE can be eliminated and converted to
cul-de-sac.
2. A temporary emergency access from "Road E" to Evergreen Way SE would likely
be required prior to opening of the full access at "Road F" through the proposed plat
of Forest Glen.
E. "Road F"
1. "Road F" design should be properly coordinated with street extension proposed by
neighboring plat, Forest Glen, for both horizontal and vertical locations.
2. Traffic calming measures should be indicated for this street to mitigate possible
future through traffic and grade related speed issues.
F. "Road G"
1. Median will be necessary at the connection to evergreen Way or an emergency
access from "Road G" to Evergreen Way will be required.
Contact Joe Welsh at 253 804-5050 for more information.
VALLEY REGIONAL FIRE AUTHORITY
1. Fire Flow: Fire flow for single family dwellings 3,600 sq ft or less is 1,000 gpm for
two hours; however the City of Auburn comp plan may require a fire flow of 1,500
gpm for two hours.
2. Fire Department Apparatus Access: Fire apparatus access roads shall have an
unobstructed width of not less than 20 feet (6,096 mm), except for approved security
gates in accordance with section 503.6, and an unobstructed vertical clearance of
not less than 13 feet 6 inches (4,115 mm).
3. The required turning radius of a fire apparatus access road shall have a 23 foot
minimum inside turning radius and a 45 foot minimum outside turning radius.
4. Dead end fire apparatus access roads in excess of 150 feet (45,720 mm) in length
shall be provided with an approved area for turning around fire apparatus. The
turnaround shall be a 65' diameter turnaround, 120' hammerhead, or a 60' "Y"
hammerhead, or as approved by the fire code official. The proposed turn around
and access will require marking as a fire lane per City of Auburn standards.
5. Fire Hydrants: Provide fire hydrant coverage to within three hundred feet (300') of
any portion planned structures.
6. Rapid Access: If gates are to be installed on access roadways, provide the needed
rapid access devices for FD use (padlocks, switches, etc.).
Contact Mike Lee with the Valley Regional Fire Authority at 253-931-3060 for any questions
regarding these comments.
Exhibit 13
Wetland Stream Report
To View Exhibit 13, please access the SFTP Site:
Access the City of Auburn Web Transfer Tool (SFTP) by going to
https://sftp.auburnwa.gov
Log into the SFTP site using the following user name and password:
Username: plandev
Password: P1ckm3up
Click on the PLT14-0006 folder and view sub-folder Exhibit 13 Wetland Stream Report
To download a single file, simply click on the file name and your web browser will prompt
you to Open, Save or Cancel: NOTE: Internet Explorer does not support multiple file
downloads. If you are using Internet Explorer, you’ll have to download each file
individually.
If you have any issues accessing the SFTP site or downloading the files please let us
know.
Exhibit 14
Geotechnical Report
To View Exhibit 14, please access the SFTP Site:
Access the City of Auburn Web Transfer Tool (SFTP) by going to
https://sftp.auburnwa.gov
Log into the SFTP site using the following user name and password:
Username: plandev
Password: P1ckm3up
Click on the PLT14-0006 folder and view sub-folder Exhibit 14 Geotechnical Report
To download a single file, simply click on the file name and your web browser will prompt
you to Open, Save or Cancel: NOTE: Internet Explorer does not support multiple file
downloads. If you are using Internet Explorer, you’ll have to download each file
individually.
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know.
Wetland & Aquatic Sciences
Wildlife Ecology
Landscape Architecture
2111 N. Northgate Way, Ste 219 Seattle, WA 98133 206-525-8122 raedeke.com
Associates, Inc.
Raedeke
TECHNICAL MEMORANDUM
April 19, 2016
To:
Mr. Blake Haddock, JDH Investment Group Corporation
From Richard W. Lundquist, M.S.
Vice President / Wildlife Biologist
Raedeke Associates, Inc.
RE: Diamond Valley Estates Preliminary Plat –
Response to Feb. 3, 2016 City of Auburn Comments
(RAI Project No. 2001-021-102a)
The purpose of this memorandum is to respond to comments from the City of Auburn on
the Preliminary Plat of Diamond Valley Estates, dated February 3, 2016, regarding
impacts and potential mitigations on downstream stream channels. Specifically, this is in
response to Comment 2 from the City’s Development Review Engineering Division,
Community Development and Public Works Department. The response is based on our
experience and knowledge of site conditions, particularly wetlands and streams, the
proposed development plans, and our review of the April 7, 2016 draft geotechnical
report prepared by GeoEngineers, Inc. (2016), and the December 8, 2014 stormwater
report prepared by Apex Engineering, PLLC (2014).
Development Review Engineering Division – Comment 2:
It appears that the total volume of flows created under developed conditions will be much
greater than under existing conditions. An analysis of the downstream channel is needed
and mitigation may be necessary if the stream is adversely impacted by the longer
duration storms flow rates that will occur as a result of project releases.
Response:
GeoEngineers, Inc. (2016) has analyzed downstream conditions and capacity of the
channels of Streams A and B on-site and Tributary 0043 downstream of the site. Based
on the estimated flow capacity of the stream channels, and the fact that on-site
stormwater facilities are designed such that peak discharge flows will not increase over
existing peak flows, they concluded that the channels have sufficient capacity to manage
the expected flows. Further, the stormwater management facilities on site, including
proposed dispersion facilities that will discharge to wetland buffers and on-site wetlands,
should provide additional buffering capacity for stormwater runoff reaching the stream
Mr. Blake Haddock
April 19, 2016
Page 2
channels (GeoEngineers, Inc. 2016). In addition, the stormwater management system for
the project is designed to meet required detention and flow control criteria to prevent
increases in water levels within the wetlands after development (Apex Engineering,
PLLC 2014).
Based on this analysis GeoEngineers, Inc. (2016) concluded that active fluvial processes
within Streams A, B, and Tributary 0043 would not change as a result of the proposed
development, and that because peak stream flows are not expected to change compared to
pre-development peak flows, mitigation for channel capacity or potential erosion is not
necessary.
However, GeoEngineers, Inc. (2016) indicated that if conditions were to change due to
unforeseen circumstances, some additional channel erosion could occur within Streams A
and B below Wetlands 2 and B, where the stream gradient steepens; over time,
headcutting could progress upstream and could impact the lower portions of the wetlands.
In the future, if such headcutting on Streams A and B were to occur, mitigation measures
could be implemented. These measures could include bed and bank armoring with rip
rap, step pool stream construction, or other methods (GeoEngineers, Inc. 2016).
Thus, based on the GeoEngineers, Inc. (2016) analysis of the expected flows and stream
channel conditions, as well as the stormwater analysis provided by Apex Engineering,
PLLC (2014), additional erosion is not expected to occur within the stream channels.
Nevertheless, it is recommend that stream channel conditions be observed during the
course of wetland mitigation implementation and long-term monitoring to determine
whether conditions have changed from pre-developed conditions or new erosion is
occurring.
If so, site-specific mitigation measures would be identified to protect the channel and
prevent further erosion, as appropriate, in consultation with the project geotechnical
engineer, civil engineer, and the City of Auburn, depending on the location and observed
conditions. Such measures could include “soft” armoring with additional plantings or
large woody debris, or “hard” armoring as suggested by GeoEngineers, Inc. (2016). If
headcutting is observed in the stream reaches where the gradient increases, it is not clear
whether “soft” armoring would be effective in preventing further erosion. If one of the
“hard” armoring measures identified by GeoEngineers, Inc. (2016) is deemed necessary,
this would likely require additional permits from the U.S. Army Corps of Engineers,
WDFW, and City of Auburn.
Thank you for the opportunity to prepare this information. If you have any questions or
need additional information, I am available at 206-525-8122 or via email at
rwlundquist@raedeke.com.
Mr. Blake Haddock
April 19, 2016
Page 3
LIMITATIONS
We have prepared this report for the exclusive use of JDH Investment Group Corporation
and their consultants. No other person or agency may rely upon the information,
analysis, or conclusions contained herein without permission from JDH Investment
Group Corporation.
The determination of ecological system classifications, functions, values, and boundaries
is an inexact science, and different individuals and agencies may reach different
conclusions. We cannot guarantee the outcome of such determinations. Therefore, the
conclusions of this report should be reviewed by the appropriate regulatory agencies.
We warrant that the work performed conforms to standards generally accepted in our
field, and prepared substantially in accordance with then-current technical guidelines and
criteria. The conclusions of this report represent the results of our analysis of the
information provided by the project proponent and their consultants, together with
information gathered in the course of the study. No other warranty, expressed or implied,
is made.
LITERATURE CITED
Apex Engineering, PLLC. 2014. Preliminary plat conceptual stormwater site plan for
Diamond Valley Estates. December 8, 2014 report to Mr. Blake Haddock, La
Quinta, California.
Auburn, City of. 2016. Review of preliminary plat of Diamond Valley Estates, File o.
PLT14-0006, related file SEPA File No. SEP00-0040 (FEIS) Dev. Agreement
Application File No. MIS08-0017. February 3, 2016 letter to Mr. Blake Haddock,
JDH Investment Group Corporation and Mr. James “Tres” Kirkebo, Apex
Engineering, Inc., Tacoma, Washington.
GeoEngineers, Inc. 2016. Geotechnical engineering services and geomorphology
services, Diamond Valley Estates Development, Auburn, Washington. File No.
21166-001-00. April 7, 2016 draft report to JDH Investment Group, LLC, La
Quinta, California, and Apex Engineering, Inc., Tacoma, Washington.
Diamond Valley Estates Deviation Request
The project site is constrained by the horizontal alignment and vertical profile of Evergreen Way SE as
well as site topography, road connection to the adjacent Gillette Plat, and onsite wetlands. As currently
designed, the project does not meet minimum density. Increasing the density to meet the minimum
would result in significantly more grading and several other deviations.
Deviation Request #1: Allow four horizontal curves that are less than the minimum radius of 333 feet
for a local residential street. Per the City of Auburn Design Standards, Table 10-1, the minimum
horizontal curve radius for a local residential street is 333 feet.
At the first location, Road F is a cul-de-sac street 485 feet in length that has two reverse curves each
with a radius of 200 feet and a tangent length between them of 108 feet. At the second location, on
Road B between Evergreen Way SE and Road C/F, there are two reverse curves each with a radius of 296
feet and a tangent length between them of 105 feet.
A. The functional intent of the design element.
The requested deviation still allows vehicles to safely negotiate the curves without leaving the
driving lane.
B. Safety factors associated with the design element.
The requested deviation provides the minimum tangent length requirement of 100 feet between
reverse curves. In addition, sight distance requirements are not violated. Road F is a cul-de-sac
road and actual vehicle speeds are anticipated to be low. For Road B, the design speed is 30mph
(per Table 10-1). For a horizontal curve radius of 296 feet, the corresponding design speed is 28
mph, which is not a significant reduction in design speed.
C. Operational concerns associated with the design element.
The requested deviation does not increase operational concerns. Two way traffic with parking
on one side of the street is still provided. No changes to the street components are being
proposed.
D. Maintenance concerns associated with the design element.
The requested deviation does not increase maintenance concerns. There is a slight decrease in
road maintenance since there is less length of street.
E. Liability concerns associated with the design element.
The requested deviation should not increase liability since other road elements meet the
standard requirements.
F. The capacity and/or efficiency of the design element.
The requested deviation does not affect capacity and/or efficiency of the roadway. Two way
traffic with parking on one side of the street is still provided. No changes to the street
components are being proposed.
G. The design life, historical performance, and durability of the design element.
The requested deviation is not anticipated to effect design life and durability of the roadway.
With respect to historical performance, horizontal curves with a radius of less than 333 feet have
been previously used in the vicinity of this project.
H. The aesthetic and visual impacts of the design element.
The requested deviation does not affect aesthetic and visual components of the roadway.
I. The cost effectiveness and availability of any replacement components or materials.
The requested deviation is for horizontal curve radius. No replacement components are required
and cost effectiveness is slightly improved since there is less road length to be maintained.
J. Consistency with the spirit and purpose of the corresponding City design standard.
The requested deviation still allows vehicles to maneuver on the roadways and the minimum
tangent length between reverse curves is still being met.
K. Demonstration that the environment will not be adversely affected.
The requested deviation results in less road length than for the standard minimum radius of 333
feet. Thus there is no increase in adverse effects to the environment.
L. Supported by published industry standards.
In the road layout in the vicinity of the project, there are instances of local roads with horizontal
curve radius of less than 333 feet. In addition, the adjacent Gillette Plat has an approved
preliminary plat with a horizontal curve radius of 100 feet.
Deviation Request #2: Allow the use of walls on more than three sides in the storm ponds and not
require 25% of the pond perimeter to be a vegetated soil slope not steeper than 3:1. These items are
shown in the November 2009 City of Auburn Surface Water Management Manual, Volume III, chapter 2,
page 352.
A. The functional intent of the design element.
The requested deviation will still provide the required detention storage but with a smaller pond
footprint.
B. Safety factors associated with the design element.
The design of the pond walls will still incorporate the appropriate safety factors.
C. Operational concerns associated with the design element.
The requested deviation does not affect the hydraulic operation of the storm ponds.
D. Maintenance concerns associated with the design element.
The use of pond walls will decrease maintenance since sloped ground will not be used.
Maintenance access to the bottom of the ponds is still being provided.
E. Liability concerns associated with the design element.
The use of pond walls is not anticipated to increase liability concerns with the functioning of the
ponds.
F. The capacity and/or efficiency of the design element.
The requested deviation does not decrease the capacity and efficiency of the storm ponds.
G. The design life, historical performance, and durability of the design element.
Properly designed, constructed, and maintained pond walls would last as long as the pond itself.
H. The aesthetic and visual impacts of the design element.
The ponds are located below the lots and public roads and are not readily visible from the street,
thus aesthetic and visual impacts are not significant.
I. The cost effectiveness and availability of any replacement components or materials.
Properly designed, constructed, and maintained pond walls would last as long as the pond itself.
Maintenance of the pond would be reduced since the amount of graded slope would be reduced.
J. Consistency with the spirit and purpose of the corresponding City design standard.
The requested deviation does not affect the storage and access requirements for the ponds and
the pond configuration still meets the design standards.
K. Demonstration that the environment will not be adversely affected.
The use of pond walls results in the pond area taking up less space than without walls. Thus the
environment is not adversely affected. The effect on the environment is reduced since the pond
footprint is reduced.
L. Supported by published industry standards.
Walls have been incorporated into previously designed, approved, and constructed storm ponds.
Deviation Request #3: Allow a modified street section for a portion of Road B and Road C northerly of
the intersection of Road F.
The intent of the modified street section design is to allow ingress/egress of emergency vehicles and
non-emergency vehicles without interference from each other.
A. The functional intent of the design element.
The requested deviation still allows passage of vehicles.
B. Safety factors associated with the design element.
The requested deviation is intended to provide for ingress/egress of emergency vehicles without
interfering with ingress/egress for non-emergency vehicles. Standard road elements (curb
gutter, paved travelled way, etc. are still provided.
C. Operational concerns associated with the design element.
The requested deviation does not restrict vehicular operation through the modified street
section.
D. Maintenance concerns associated with the design element.
The requested deviation utilizes standard road elements. No unusual maintenance issues are
anticipated.
E. Liability concerns associated with the design element.
The requested deviation should not increase liability since standard road elements are still being
used.
F. The capacity and/or efficiency of the design element.
The requested deviation does not reduce the capacity and effectiveness of the roadway.
G. The design life, historical performance, and durability of the design element.
The requested deviation is not anticipated to effect design life or durability of the roadway.
Although this specific road section modification is not known to be used elsewhere negative
performance is not anticipated to occur.
H. The aesthetic and visual impacts of the design element.
The requested deviation does not create unusual aesthetic and/or visual impacts since no
unusual road elements are being used.
I. The cost effectiveness and availability of any replacement components or materials.
The requested deviation utilizes standard road components. No unusual components or
materials are proposed that would burden the City of Auburn with extra costs.
J. Consistency with the spirit and purpose of the corresponding City design standard.
The requested deviation still provides the typical road components of a street cross-section. The
wider width from curb to curb allows additional ingress/egress movements for emergency
vehicles.
K. Demonstration that the environment will not be adversely affected.
The requested deviation does not adversely affect the environment since critical areas are not
impacted.
L. Supported by published industry standards.
Although the modified cross sections are not known to be standard to the general area, a wider
than standard paved width of one direction travel exceeds industry standards for lane width.
April 27, 2016
Jeff Dixon
City of Auburn
25 West Main Street
Auburn, WA 98001
Reference: Comment Responses for Preliminary Plat of Diamond Valley Estates
City of Auburn Application PLT14-0006
Apex Project No. 30153.03
Dear Mr. Dixon:
We have received your letter of February 3, 2016 with review comments for the above referenced
project. Below are your comments followed by our responses in italic.
Development Review Engineering Division - Community Development & Public Works Department
1. The storm water modeling per WWHM does not address the Wetland
Fluctuation Model. Please provide the modeling results and if the results
show that it fails, provide the results to your wetland consultant for
evaluation and determination how to proceed.
Chapter 5 of the December 8, 2014 storm report describes the
stormwater effects to the existing wetlands. The evaluation utilized
Guide Sheet 2B of the Auburn Storm Manual. WWHM was used to
calculate pre-developed and developed flow rates on a daily and
monthly basis. These flow rates were used to calculate depth of flow at
several cross-sections in the wetland areas. The maximum change in
depth was calculated to be 1.32 inches with a maximum depth of 4.08
inches. Guide Sheet 2B also describes six criteria for threshold
evaluation. For this project the thresholds are not exceeded. The
calculations and modeling results begin on page 167 of the storm report.
2. It appears that the total volume of flows created under developed conditions
will be much greater than under existing conditions. An analysis of the
downstream stream channel is needed and mitigation may be necessary if the
stream is adversely impacted by the longer duration storms flow rates that will
occur as a result of project releases.
A downstream analysis of the stream channel was performed and described
in detail in the geotechnical report (page 26 of the report dated April 21,
2601 South 35th Street, Suite 200
Tacoma, WA 98409
(253) 473-4494 Phone
(253) 473-0599 Fax
Page 2 April 27, 2016
2601 South 35th Street, Suite 200, Tacoma, WA 98409 (253) 473-4494 Phone (253) 473-0599 Fax
2016). In addition, Raedeke and Associates (wetland consultant) has prepared
a response letter discussing the downstream condition from a wetland
consideration.
3. Benching of the graded slopes above developed facilities, i.e., roads, ponds, and
homes is required for protection of the proposed facilities. Estimated spacing
suggested is at 15 to 20 foot vertical spacing. Please consult with your
geotechnical consultant as to their recommended spacing. Your present
grading design appears inadequate in respect to benching along the significant
2:1 slopes proposed within the project. It is requested that further discussion
and direction be provided by the geotechnical consultant in their report on
vertical spacing and recommended locations of benching along the slopes.
Specific areas of concern are graded areas above future housing and roadways,
and ponds.
Terracing (benching) of graded slopes is discussed on page 44 of the April 21,
2016 geotechnical report.
4. Sheet 22 shows fill slopes that are not keyed in. Special attention should be made in
the design of fill slopes to prevent failure. Provide design recommendation from the
geotechnical consultant on the keying in of fill slopes on this project.
Fill slopes are to be keyed in as described on page 44 of the April 21, 2016
geotechnical report. This condition is anticipated to be a plat requirement and shown
on the FAC/GRA plans.
Utilities Division - Community Development & Public Works Department
Storm
1. Both ponds exceed requirements to secure a Dam Construction Permit from the Dam
Safety Office of the Washington State Department of Ecology. Evidence of permit
compliance is required prior to approval of the FAC plans for the project. (Authority
Chapter 173-175 WAC).
Comment noted. Dam safety review will be initiated as part of FAC/GRA plan
preparation.
2. Retaining wall located within storm ponds shall be concrete meeting the requirements
of Vol Ill 2.3.1.2 of the 2009 City of Auburn Surface Water Management Manual
(SWMM).
Comment noted.
3. The geotechnical report provided is a response to the City's previous comments, but
does not include a comprehensive geotechnical evaluation of the entire site. The
geotechnical report titled "Geologic, Hydrogeologic, and Geotechnical Engineering
Services, Proposed Kersey Ill Subdivision, Auburn. Washington" dated March 5, 2004 is
considered out of date, particularly in the steep hillside areas. The report should be re-
issued with revisions to bring it up to date, in accordance with current codes, and
Page 3 April 27, 2016
2601 South 35th Street, Suite 200, Tacoma, WA 98409 (253) 473-4494 Phone (253) 473-0599 Fax
include a comprehensive subsurface evaluation of the entire site (full depth boring from
top to toe of slopes). The topography, particularly of the steep areas, should be
surveyed (e.g., LIDAR or
conventional methods), with special emphasis on geologic hillside exposures. Hillside
areas should be evaluated for areas of seepage, evidence of erosion, and the condition of
tree trunks (e.g., bowed conifer tree trunks).
During our February 23 meeting, it was acknowledged that the recent geotechnical
evaluations prepared by GeoEngineers was to supplement the March 2004
geotechnical report. The April 21, 2016 report contains detailed descriptions,
discussion, calculations, and responses that are specific to the Diamond Valley Estate
project. For reference, the March 2004 report was uploaded to the Auburn FTP site on
March 18, 2016 in the “PLT 14-0006 Diamond Valley Estates” folder.
4. A target slope stability for static and seismic safety factor of 1.00 is not acceptable as
it burdens the City with the long term liability of potential slope failure. Given the
perpetual public ownership of the walls and slopes, the notion that "it is highly
unlikely that the design earthquake would occur at the same time as the 100-year-
high water surface elevation within the pond" is not acceptable.
The slope stability discussion begins on page 19 of the April 21, 2016 geotechnical
report and has been expanded with additional discussion. Factor of safety has been
increased by wall bury depths below the bottom of the pond and geotextile
reinforced earth.
5. As noted in the building permit comments, the buffers and setbacks from steep slopes
(both at the top and toe of slopes) needs to be defined and shown on the drawings.
These setbacks should consider not only the proposed lots within Diamond Valley
Estates, but also setbacks from existing lots in the surrounding Lakeland Divisions 8 and
9 and the Pierce County lots to the south.
Proposed grading into the wetland buffers are very minimal, minor encroachment
areas are to be replanted. Proposed grading is intended to conform at the property
line or to existing ground within the project boundary. Within the lots, structure
setbacks from the property lines will be maintained. For the condition when the top of
slope and/or toe of slope is greater than the structure setbacks, the setback from
either top of slope or toe of slope within the lot is intended to be at least 5’. For these
situations, smaller houses are intended to be used to increase the distance to the
top/toe of slope.
6. Provide additional explanation of the slope stability modeling performed, the results of
which are shown in Appendix D.
Additional discussion of the slope stability modeling has been included in the April 21,
2016 geotechnical report. (See page 19 of the report).
7. The recommendations included in the report: Geotechnical Engineering and
Geomorphology Services for Diamond Valley Estates Development prepared by
GeoEngineers dated November 16, 2015, including Appendix D, shall be included as plat
requirements for approval as noted below.
Page 4 April 27, 2016
2601 South 35th Street, Suite 200, Tacoma, WA 98409 (253) 473-4494 Phone (253) 473-0599 Fax
Comment noted.
General
8. To reduce the length of unimpeded high slope (in some cases exceeding 80 feet), and to
collect and reduce the probable impacts of sheet flow on the slope face, additional
benches shall be installed into the cut and fill slopes associated with Ponds 1 & 2, Road F
and Lot 7 & 8 slopes.
Comment noted. For plat requirements as stated in #7 above. Additional benches to
be added per Geotech recommendations.
9. Provide the proposed re-vegetative and planting proposed for these slopes.
Comment noted for plat requirements as stated in # 7 above.
10. Dispersion Trenches: Disturbance of native vegetation in and around the dispersion
trenches shall be minimized.
Comment noted for plat requirements as stated in #7 above.
11. Site clearing, grading, stabilization, pond, and roadwork shall occur during summer
construction season. Prior to issuance of clearing or grading permits, a grading plan for
grading and clearing necessary for both the construction of infrastructure such as roads
and utilities and for lot grading shall be prepared, submitted and approved by the City of
Auburn. The purpose of the plan is to accomplish the maximum amount of grading at
one time to limit or avoid the need for subsequent grading and disturbance, including
grading of individual lots during home construction. The plan shall identify the surveyed
boundary of the crest slopes for the site's 40% or greater slopes. This plan shall show
quantities and locations of excavations, and embankments, the design of temporary
storm drainage detention system, and methods of preventing drainage, erosion and
sedimentation from impacting adjacent properties, natural and public storm drainage
systems and other nearby sensitive areas. All the measures shall be implemented prior to
beginning phased on-site filling, grading or construction activities. The applicant's grading
plans shall be prepared in conjunction with and reviewed by a geotechnical engineer
licensed in the State of Washington. The geotechnical engineer shall develop and
submit, for the City's review, specific recommendations to mitigate grading activities with
particular attention to developing a plan to minimize the extent and time soils are
exposed on site and address grading and related activities during wet weather periods
(the period of greatest concern is October 1 through March 31). The plans shall show the
type and the extent of geologic hazard area or any other critical areas as required in
chapters 16 and 18 of the International Building Code (IBC). (Policy EN- 69, EN-70, ACP)
and/or the City's Critical Areas Ordinance.
Comment noted for plat requirements as stated in #7 above.
12. A re-evaluation of the site conditions by a geotechnical engineer licensed in the State of
Washington, specifically the geotechnical engineer of record for the initial rough-grading
geotechnical analysis, is required following rough grading and excavation to refine
Page 5 April 27, 2016
2601 South 35th Street, Suite 200, Tacoma, WA 98409 (253) 473-4494 Phone (253) 473-0599 Fax
drainage design. Upon completion of rough grading and excavation, the applicant shall
have a geotechnical engineer re-analyze the site and determine if new or additional
mitigation measures are necessary. A revised geotechnical report shall be submitted to
the City of Auburn for review and approval by the City Engineer. Recommendations for
areas where subsurface water or heaving sands are known or discovered shall be given
particular attention by the geotechnical engineer and coordinated with the project
engineer responsible for the storm drainage system design.
Comment noted for plat requirements as stated in #7 above.
13. Additional analysis to assess the magnitude of the temporary and permanent dewatering
is required prior to issuance of a grading permit. All permanent dewatering shall be
designed to ensure long term, low cost, minimal maintenance. Provide detailed
description of required maintenance, frequency and access prior to permit issuance,
including accessibility for long-term maintenance.
Comment noted for plat requirements as stated in #7 above.
14. Pond 1
Uphill Cut Slope: Temporary dewatering of the hillside above Pond 1 shall occur prior to
its construction. Permanent drainage dewatering system shall be installed below the
base of the retaining wall at the toe of the cut for the pond.
Downhill Fill Berm: A full liner of the entire pond and slopes is required. A partial liner
would allow seepage from the unlined area to bypass the lined part. A permanent
drainage dewatering system shall be installed below the outboard fill slope. The
outboard fill slope shall be a minimum 2 1/2 H: 1 V (2:1 is too steep).
Temporary and permanent dewatering to be designed during the FAC/GRA plan
preparation process. A pond liner is to be incorporated into the final pond design.
Outboard fill slope to be increased to 2.5:1 where possible by use of walls but not
encroaching into the wetland buffers.
15. Pond 2
Uphill Cut Slope: Temporary dewatering of the hillside above Pond 2 shall occur prior to
its construction. Permanent drainage dewatering system shall be installed below the
base of the retaining wall at the toe of the cut for the pond.
Downhill Fill Berm: A full liner of the entire pond and slopes is required. A partial liner
would allow seepage from the unlined area to bypass the lined part. A permanent
drainage dewatering system shall be installed below the outboard fill slope. The
outboard fill slope shall be a minimum 2 ½ H: 1 V (2:1 is too steep).
Temporary and permanent dewatering to be designed during the FAC/GRA plan
preparation process. A pond liner is to be incorporated into the final pond design.
Outboard fill slope to be increased to 2.5:1 where possible by use of walls but not
encroaching into the wetland buffers.
16. Road F
Page 6 April 27, 2016
2601 South 35th Street, Suite 200, Tacoma, WA 98409 (253) 473-4494 Phone (253) 473-0599 Fax
Uphill Cut Slope: To increase the static factor of safety above 1.00 and eliminate
potential for groundwater surfacing at grade, install a permanent drainage dewatering
trench system.
Downhill Existing Slopes: To increase the static factor of safety above the calculated 1.03,
install a permanent drainage dewatering system at the toe of the slope.
Factor of safety has been increased to be at least 1.10. See the slope stability
discussion on page 19 of the April 21, 2016 geotechnical report. Dewatering to be
designed during the FAC/GRA plan preparation process.
17. Lots 7 & 8
To address a low static factor of safety and eliminate potential for groundwater surfacing
at grade, install a permanent drainage dewatering trench system.
Comment noted. Dewatering to be designed during the FAC/GRA plan preparation
process.
Water
18. No comments on the geotechnical report. Previous water comments still apply:
Comment noted.
19. The number of proposed Pressure Reducing Stations (PRV) is not acceptable. 1 or 2
would be acceptable. Any parcel with pressure over 80 psi would be required to have
an individual PRV after the meter. This information is required to be recorded with the
plat.
Per comments from Susan Fenhaus, the number of PRVs has been reduced (see
sheets 14 and 15).
Planning Services Division - Community Development & Public Works Department
1. On page 13, (Comment 19) the geotechnical report references a revised "critical areas
slope exhibit', but the figure is not contained within the Report.
Critical Area Slope Exhibit added to the April 21, 2016 geotechnical report.
2. The geotechnical report references that a variance application for alteration of Class IV
landslide Hazard areas will be filed for Road F, Tract I and lots 74 through 77 (now re-
numbered as Lots 71 through 73) and Lots 7 and 8. Please be aware that the variance
application would need to be field so that the variance application could be considered
by the Hearing Examiner along with the preliminary plat. The inclusion of responses to
variance criteria contained in the geotechnical report does not substitute for filing this
variance application.
Comment noted. A variance Application will be completed and submitted in the next
Page 7 April 27, 2016
2601 South 35th Street, Suite 200, Tacoma, WA 98409 (253) 473-4494 Phone (253) 473-0599 Fax
week.
Thank you for your consideration of this response.
Sincerely,
Geoffrey P. Sherwin, PE
Principal
I:\30153.03\Docs-Reports\Documents\30153.03_Comment Response Letter_04-27-16.doc
July 6, 2016
Jeff Dixon
City of Auburn
25 West Main Street
Auburn, WA 98001
Reference: Comment Responses for Preliminary Plat of Diamond Valley Estates
City of Auburn Application PLT14-0006
Apex Project No. 30153.03
Dear Mr. Dixon:
We have received your letter of February 27, 2015 with review comments for the above referenced project.
Below are your comments followed by our responses in italic.
Survey Division - Community Development & Public Works Department
(Prior comments have been addressed)
For any questions on the survey comments please contact Bob Burton, Survey Supervisor, at
bburton@auburnwa.gov or at 253-804-5066 .
N/A. The City has determined that survey division comments have been addressed.
Development Review Engineering Division - Community Development & Public Works Department
(Awaiting submittal of requested geotechnical report to complete reviews)
For any questions on the development review engineering comments please contact Monty Bakken,
Development Review Engineer, at mbakken@auburnwa. gov or 253-804-5070 .
Geotechnical report submitted on April 27, 2016.
Valley Regional Fire Authority
1. FIRE APPARATUS ACCESS ROADS:
Fire apparatus access shall comply with International Fire Code (IFC) Section 503, Appendix D and
City of Auburn Design Standards, Chapter 10. If fire lanes are required they must comply with Auburn
City Code 10.36.175, 'Fire Lanes'.
Provide two separate and approved fire apparatus access roads for the residential lots accessed by
proposed Road G (See IFC Section D107 and D104.3, below) .
2601 South 35th Street, Suite 200
Tacoma, WA 98409
(253) 473-4494 Phone
(253) 473-0599 Fax
Page 2 July 6, 2016
Provide documentation for review that insures that proposed Roads B and F will have future links to
public roads. The cul-de-sacs are not even labeled "temporary”.
The two temporary cel-de-sacs have been labeled as temporary on Sheet 2. The Forest Glen
Plat (PLT06-0008) shows the construction of Road F and coincides with the alignment shown
on the Diamond Valley Estates plat. There are no known applications for development of the
parcel to the north of Road B. Development of this parcel would be required to connect to
Road B (contingent on review and approval by the City of Auburn.)
A note has been added to Sheet 2 indicating the installation of an informational sign. The
exact wording, size, location, etc. is to be determined during preparation of FAC plans. We
expect the sign installation to be a condition of preliminary plat approval.
SECTION D 107
ONE- OR TWO-FAMILY RESIDENTIAL DEVELOPMENTS
D107. 1 One- or two-family dwelling residential developments.
Developments of one- or two-family dwellings where the number of dwelling units
exceeds 30 shall be provided with two separate and approved fire apparatus access
roads, and shall meet the requirements of Section 0104.3.
Exceptions:
Where there are more than 30 dwelling units on a single public or private fire
apparatus access road and all dwelling units are equipped throughout with an
approved automatic sprinkler system in accordance with Section 903.3.1.1,
903.3.1.2 or 903.3.1.3 of the International Fire Code, access from two
directions shall not be required.
The number of dwelling units on a single fire apparatus access road shall not
be increased unless fire apparatus access roads will connect with future
development, as determined by the fire code official.
All proposed roads less than twenty six feet (26} must be post "No Parking".
Proposed roads twenty six feet (26} or greater in width, but less
than thirty two feet (32} in width, must be posted parking on one side of the
street only to provide minimum fire apparatus access. Cul-de-sacs must be
posted no parking around its entire perimeter to provide fire apparatus
turnaround.
0104.3 Remoteness
Where two fire apparatus access roads are required, they shall be placed a distance apart
equal to not less than one half of the length of the maximum overall diagonal dimension
of the lot or area to be served, measured in a straight line between accesses.
For any questions on the Fire Agency comments please contact Mike Lee, Assistant Fire Marshall,
Valley Regional Fire Agency, at mike.lee@vrfa.org or at 253-288-5872.
Page 3 July 6, 2016
Road B and Road C north of the intersection of Road F has been widened to provide additional
width for vehicular ingress/egress. The width, alignment, and striping were agreed during
several conversations with James Webb in August and September 2014.
Building Division - Community Development & Public Works Department
1. In its August 1, 2014 letter, the city commented please be aware of building code requirements that
apply to slopes, rockery and retaining walls in relation to the future placement of structures in
accordance with the 2012 International Building and 2012 Residential Code, current standards
R403.1.7.1, 'Building clearances from ascending slopes'.
In general, buildings below slopes shall be set a sufficient distance from the slope to provide
protection from slope drainage, erosion and shallow failures. Except as provided in Section
R403.1.7.4 and Figure R403.1.7.1, the following criteria will be assumed to provide this protection.
Where the existing slope is steeper than one unit vertical in one unit horizontal (100-percent slope),
the toe of the slope shall be assumed to be at the intersection of a
horizontal plane drawn from the top of the foundation and a plane drawn tangent to the slope at an
angle of 45 degrees (0.79 rad) to the horizontal. Where a retaining wall is constructed at
the toe of the slope, the height of the slope shall be measured from the top of the wall to the top of
the slope. Retaining walls can be used for to supplement to slope design.
Please recognize the limitation of rockery retaining walls could be subject to redesign or may need to
be replaced with a retaining wall to support the building loads or surcharge imposed. If rockeries are
shown on future grading plans, these plans could be subject to conditions that require changing to
retaining wall construction a separate permit. For building permit activity of site specific lots, could
require that the building contractor to be aware that rock retaining walls cannot be used to support
loads from the building foundations or surcharge. Rockery walls that do not have a structural
surcharge and are less than 4 feet in height will not require a permit.
Retaining walls
Any retaining wall over four feet in height must have a permit and engineering calculation to support
the design and placement on the property. Retaining walls that are not over 4 feet (1219 mm) in
height measured from the bottom of the footing to the top of the wall, unless supporting a
surcharge or impounding Class I, II or lllA liquids. Keystone walls must provide engineering
calculation along with the manufacturers installation guidelines. Any structure imposing a surcharge
onto a rockery walls or retaining wall will require a permit. Please note rockery walls are not
designed to retain any buildings or structural loading. Please refer to the 2012 International Building
for design. Rockery walls that do not have a structural surcharge and are less than 4 feet in height
will not require a permit.
The response by Apex Engineering indicates: "comments noted" but this information should be
correlated with the Conceptual Grading Plan, Sheet 21 of and 22 of 26, Apex Engineering Inc.
December 8, 2014 to show that with proposed grading sufficient building envelopes will be available
within the lot areas.
For any questions on the Building Division comments please contact Michael Grohs, Plans Examiner, at
mqrohs@auburnwa.gov or at 253-931-3013
Page 4 July 6, 2016
The grading provides flat pads with the depths shown. House plans have not been selected at this
time and would be selected (or designed) to fit the pad. The Client understands that walls would be
required to create larger pads and that additional permitting and calculations are required for walls
over 4 feet in height.
Utilities Division - Community Development & Public Works Department General
General
1. Informational Comment: Please be aware that water and sewer system payback agreements apply for
all parcels of plat.
Comment noted.
Water
2. The number of proposed Pressure Reducing Stations (PRV) is not acceptable. 1 or 2 would be
acceptable for the proposed plat. And based on the location of the public PRVs any parcel with
pressure over 80 psi would be required to have an individual PRV after the meter. It is anticipated
that identification of the lots that are subject to the individual PRVs will be a preliminary plat condition
and will be required to be identified on the final plat that is recorded.
For any questions on the utility comments please contact Susan Fenhaus, Water Engineer, at
sfenhaus@auburnwa .gov or 253-804-5061.
Per comments from Susan Fenhaus, the number of PRVs has been reduced (see Sheets 14 and
15).
Sewer
3. It is understood that the proposed Tract I is to be owned and maintained by the City. If that is not the
case or the proposal changes in the future, then a 30' wide easement, centered on the pipe, will be
required for the sewer line within this Tract I.
Comment noted. We anticipate this wording (or similar) to be a condition of preliminary plat
approval. (see also Planning Division comment #2 at the end of this letter.)
Storm
(No comment. Previous comments have been addressed in the narrative and plan submittals.)
N/A. No comments from this review.
Transportation Division - Community Development & Publi c Works Department
The following comments are based on the review of Diamond Valley Estates Preliminary Plat
(drawings) Sheets 1 through 26, Apex Engineering PLLC, December 8, 2014.
Sheet 2:
Page 5 July 6, 2016
1. In accordance with previous discussions, the cul-de-sac where temporary should be shown as cul-
de-sacs that can be addressed through temporary easements with provisions similar to the
following :
"WHEN IT BECOMES NECESSARY , AS PART OF A SUBDIVISION, TO INSTALL A TEMPORARY
CUL-DE-SAC PER CITY OF AUBURN DESIGN STANDARDS, THE PORTION OF THE TEMPORARY
CUL-DE-SAC ENCROACHING ON THE ADJACENT PRIVATE PROPERTY SHALL BE PLACED IN A
TEMPORARY EASEMENT DEDICATED TO THE CITY OF AUBURN . THE TEMPORARY
EASEMENT SHOWN ON LOTS 111- 114, 82 IS HEREBY RESERVED, GRANTED AND CONVEYED
TO THE CITY OF AUBURN FOR TEMPORARY PUBLIC ROADWAY PURPOSE, UPON THE
RECORDING OF THIS PLAT. THE CITY OF AUBURN IS HEREBY RESPONSIBLE FOR THE
MAINTENANCE OF THE TEMPORARY PUBLIC ROADWAY FACILITIES WITHIN SAID EASEMENT.
UPON THE CONSTRUCTION OF AN EXTENSION OF THE STREET, AND WHEN DETERMINED BY
THE CITY OF AUBURN THAT THE TEMPORARY CUL-DE- SAC IS NO LONGER REQUIRED, IT
SHALL BE THE RESPONSIBILITY OF THE DEVELOPER THAT IS EXTENDING THE PUBLIC STREET
IMPROVEMENTS , TO REMOVE THE TEMPORARY CUL-DE-SAC AT THEIR EXPENSE . IN
CONJUNCTION WITH TEMPORARY CUL-DE-SAC REMOVAL, THE DEVELOPER SHALL ALSO
FINISH CONSTRUCTION OF THE PUBLIC STREET WITH N THE TEMPORARY CUL-DE-SAC
A REA IN ACCORDANCE WITH THE CITY OF AUBURN DESIGN STANDARDS APPLICABLE TO THE
STREET CLASSIFICATION AS WELL AS ANY PRIVATE IMPROVEMENTS AND PROPERTY
RESTORATION THAT MAY BE NECESSARY ON ADJACENT LOTS AFFECTED BY THE REMOVAL
OF THE TEMPORARY CUL-DE-SAC . THE TEMPORARY EASEMENT SHALL AUTOMATICALLY
TERMINATE UPON REMOVAL OF THE TEMPORARY CUL-DE-SAC IMPROVEMENTS, AS
APPROVED BY THE CITY OF AUBURN. LOT XX IS HEREBY DESIGNATED “UNBUILDABLE" UNTIL
SUCH TIME AS SAID TEMPORARY CUL-DE-SAC EASEMENT ON LOT XX IS TERMINATED. "
Comment noted. We anticipate this wording to be a condition of preliminary plat
approval.
Sheet 4:
2. The ROW shown for the temporary cul-de-sacs at the ends of Road F and Road B are larger than
needed to accommodate the required 65 feet of pavement.
Comment noted. The Client understands that the temporary cul-de-sacs are larger than
needed. However, with the previous discussions of emergency vehicle access and
turnarounds, the Client believes that the larger area would be of benefit for the roads where
they are located. The temporary cul-de-sacs will be replaced with a continuous road section
when adjacent developments connect to those roads.
A notation has been added on Sheet 2 regarding a sign at the back of the temporary cul-de-
sac indicating a future extension.
3. The road grade of Road B at the intersection with Evergreen Way SE is missing.
Grade text added.
4. Both ends of the section of Road B classified as a "Residential Collector" are subject to the City's
functional intersection boundary requirements.
Page 6 July 6, 2016
Comment noted. The driveway for Lot 1 is to be on Road G and is shared with Lot 2. The
driveway for lot 37 is to be on Road G on the east side of the lot.
5. All the ROW radii need to be labeled .
Radii information added.
6. The modified cross sections for Roads B and C to the north of the intersection with Road F need to
extend such that no more than 25 lots are located along beyond the end of the modified cross
section.
Limits of modified section moved to the 25 lot limit.
7. Include the detailed drawings showing the transition areas from the modified cross sections to
the standard cross sections along Road B and Road C north of the intersection with Road F and
Road B just north of Evergreen WY SE.
Transition area details added.
Sheet 5:
8. The intersection depicted in Detail D should incorporate a splitter island at the end of the Road C
median. Based on the school access analysis, the intersection needs to accommodate school buses.
The intersection also needs to accommodate delivery vehicles and moving trucks. Turning templates
for the anticipated design vehicle are required to support the proposed design. The design details are
also needed for the proposed island, for example, is barrier curb proposed, or will it be mountable?
etc.
Splitter island added and noted. A separate exhibit showing turning templates is included in
the resubmittal. The curb at the traffic island is noted to be mountable. Required signing and
locations to be determined during preparation of FAC plans.
Sheet 6:
9. The use of stop control on Road B at the intersection with Road G is not warranted. The sight triangles
should be modified assuming the intersection is uncontrolled.
Although the likelihood of a significant number of vehicles crossing the intersection without
turning onto Road B is small, the road grades of 4.8% and 8% along Road B are greater than
the usual 2% to 3%. In addition, the intersection sight distance for an uncontrolled
intersection is smaller than for a stop controlled intersection (115 ft versus 280 ft/240 ft for a
25mph design speed). It is suggested that this intersection not be stop controlled, however,
the sight distance triangles would be prepared for the stop condition. In the future, if the
intersection is to be stop controlled, the appropriate sight distance will have been provided.
Sheet 7:
10. All sight distance exhibits need to include the road grades on both the major and minor street
approaches for the sight triangle. The adjustment factor for the grade of the side street approach
should be the same for both the left and right turn sight triangles.
Page 7 July 6, 2016
The grades used in the sight distance calculations have been added to each sight distance
exhibit. The grades shown are from the road profile at the end of the sight distance limit. The
adjustment factor for grade is taken from Table 10-2B and varies depending on the positive or
negative grade of the approaching vehicle. At this intersection, the approach grades are -10%
to -6.62% with corresponding adjustment factors of 1.2 and 1.1.
Sheet 8:
11. The adjustment for the grade of the minor street approach should be the same for left and eight
turning vehicles.
The adjustment factor for grade is taken from Table 10-2B and varies depending on the
positive or negative grade of the approaching vehicle. At this intersection, the approach
grades are -10% and -6.62% with corresponding adjustment factors of 1.2 and 1.1.
Sheet 9:
12. The adjustment for the grade of the minor street approach should be the same for left and eight
turning vehicles .The Median Island on Evergreen at the intersection with Road E needs to be
modified to accommodate turning vehicles.
The adjustment factor for grade is taken from Table 10-2B and varies depending on the
positive or negative grade of the approaching vehicle. At this intersection, the approach
grades are -10% and -6.62% with corresponding adjustment factors of 1.2 and 1.1. A note has
been added to the sheet indicating the median island is to be modified.
Sheet 10:
13. What control type is proposed to be used at this intersection? The use of a traffic island implies that
all approaches to the intersection will be yield controlled. The Sight distance triangles should be
modified accordingly. Road B to the west of the intersection is a residential collector so a design speed
of 35 mph should be used. The side street grade for both LT and RT should be consistent, the RT does
not account for the side street grade.
Although this intersection would be yield controlled, accommodating the stop condition would
provide the appropriate sight distance if this intersection became stop controlled in the future.
The portion of Road B that is a collector is adjacent to Evergreen Way SE (per the section on
Sheet 4) and the remainder of Road B is a local residential street. For a design speed of
35mph, the sight distance required would be 397ft and could be achieved without impacting
the lot configuration. If a design speed of 35mph is to be used at this intersection, we would
expect this to be a condition of preliminary plat approval.
The adjustment factor for grade is taken from Table 10-2B and varies depending on the
positive or negative grade of the approaching vehicle. At this intersection, the approach
grades are -8% (approaching the intersection) and +8% (leaving the intersection) with
corresponding adjustment factors of 1.1 and 0.9.
Sheets 11, 12 and 13:
14. See comments for sheet 10.
Page 8 July 6, 2016
The adjustment factor for grade is taken from Table 10-2B and varies depending on the
positive or negative grade of the approaching vehicle. The slopes shown on these sheets were
used to calculate the adjustment factor.
15. Note that the City requires a level landing on all intersection approaches of no more than 5%. This
does not appear to be the case in some locations based on the sight distance calculations.
The sight distance profiles are taken along the line of sight, not along the road centerlines,
which result in the skewed pavement depicted in the sight distance profile. The road profiles
(taken along the centerline) shows that the landings are less than 5%.
16. Deviation requests are required for the modified cross-sections and any other items which are not
consistent with City standards.
Comment noted. The modified cross-sections deviation will be included in the requested
deviations for the project.
For any questions on the transportation comments please contact James Webb, City Traffic Engineer,
at jwebb@auburnwa.gov or 253-804-5040.
Planning Services Division - Community Development & Public Works Department
1. In the August 1, 2014 letter, the city said Auburn City Zoning Code Section; 18.02.065 provides the
method of calculating the zoning density and requires a computation of "net site area" as a starting
basis. While Sheet 1 of 19 provides a figure of 70.25 acres for "net site area". Please show how this
figure was calculated using the criteria in code.
And the City said Sheet 1 of 19 shows a minimum density calculation of "70.25 acres x 4 dwelling units
per acre of the R5 zoning = 281 dwelling units". However, the project is not
achieving this minimum density based on the 202 lots proposed . Please ensure that the "net site
area" has been calculated in accordance with city code standards. If this standard continues to not be
met by the proposal , then a 'modification of standards and specifications' application may need to be
filed with the city to be processed concurrently with the preliminary plat application in accordance
with Chapter 17.18. "Net site area" is defined as:
"18.02.065 Methods of calculating density.
The permitted number of dwelling units or lots shall be determined as follows:
A. Net Site Area. The area of a site used to calculate the allowed number of dwelling
units or lots shall exclude those areas designated for public rights-of-way, except for the
designation of additional right-of-way along arterials, private streets, vehicle access
easements, and on-site public or homeowners' association-maintained recreation space if
required.
Further, the net site area shall be subject to the following adjustments and limitations for
critical areas:
1. Net site areas shall exclude streams, wetlands, fish and wildlife habitat areas, and
high landslide hazards; and
Page 9 July 6, 2016
2. Net site area shall include any required critical area buffer, seismic hazards, and flood
hazard areas when calculating base density, unless critical areas identified in subsection (A)(1)
of this section are present; provided, that net site area shall not include required critical area
buffers when calculating minimum density. The allowed number of
dwelling units or lots for a site shall be computed by multiplying the net site area of the lot
as calculated in this section by the applicable residential base density number found in the
development standards for each zone."
It does not appear stream, streams, wetlands, fish and wildlife habitat areas, and high landslide
hazards and their buffers were excluded from the net site area calculation.
The response says that there is a request is being made to waive the minimum density. A formal
request in accordance with ACCC Chapter 17.18 (MODIFICATIONS OF STANDARDS AND
SPECIFICATIONS) will be needed.
Comment noted. Accompanying this resubmittal is a request to waive the minimum density
requirement for the project.
2. City previously asked for information on the proposed ownership of the plat's tracts. Tract I is
proposed to consist of wetlands, stream and public storm drainage faculties and be publicly
dedicated. It may not be appropriate to have the City Storm utility own and maintain the critical area
features within this Tract, unless there is a mechanism to distinguish between management of the
different functional areas. Separate tracts are preferential.
Comment noted. The storm ponds (and associated access) can be separated into tracts.
3. The City previously had a number of comments on the report: Geotechnical Engineering Services,
Diamond Valley Estates Development, Auburn WA, GeoEngineers, April 18, 2014 that are expected to
be addressed by the revised report.
The revised geotechnical report was submitted on April 27, 2016.
Thank you for your consideration of this response.
Sincerely,
Geoffrey P. Sherwin, PE
Principal
July 7, 2016
Jeff Dixon
City of Auburn
25 West Main Street
Auburn, WA 98001
Reference: Comment Responses for Preliminary Plat of Diamond Valley Estates
City of Auburn Application PLT14-0006
Apex Project No. 30153.03
Dear Mr. Dixon:
We have received your email of new review comments for the above referenced project. Below are your
comments followed by our responses in italic.
New comments based on April 27, 2016 submittal:
New Dev Rev. Engineer. based on April 27, 2016 submittal:
1. Please incorporate in the Geotechnical Engineering and Geomorphology Services Report dated
April 21, 2016, Page 38, under Sedimentation and Erosion Control:
Note 4 has been added to the grading plan (Sheet 21) for erosion control measures. We
expect erosion control wording to be a condition of preliminary plat approval.
2. Add reference to the WSDOE Surface Water Management Manual (SWMMWW) for Western
Washington 2012 (amended 2014) and the 2009 City of Auburn Surface Water Management
Manual (SWMM).
Note added to Sheet 14 and 15.
3. In the Raedeke Associates, Inc. April 19, 2016 Technical Memorandum, Development Review
Engineering Division - Comment 2:
The total volume of developed flows created under the developed condition is significantly greater
than under pre-developed conditions. The peaking flow rates are being maintained but the total
volume of flow is greater (Apex can provide you with those volumes in cubic feet of runoff. There
may be impacts to the wetlands and downstream channel due to the increased volume of flows
released from the two proposed ponds.
We request that pre-developed photos and report be provided for the existing condition of the
wetlands and stream channel along with a mitigation plan on the monitoring and process to address
potential impacts created by the development.
2601 South 35th Street, Suite 200
Tacoma, WA 98409
(253) 473-4494 Phone
(253) 473-0599 Fax
Page 2 July 7, 2016
Pre-development photos and report of the existing condition of the wetlands and stream
channel along with a proposed mitigation and monitoring plan can be prepared prior to
the start of construction. We expect this to be a condition of preliminary plat approval.
New planning division comments based on April 27, 2016 submittal:
A. Based on Sheet 21 of 26, Grading Plan, please demonstrate that Lots 24 and 29 have a suitable
and developable lot envelope for future house construction, that will not require subsequent lot
grading at time of building permit. The access to Tract 29 appears to be located with the
engineered slope proposed with plat grading. Please ensure that private access grade can meet
city engineering design standards for driveway slope.
The grading for lot 24 and lot 29 has been modified to show development feasibility.
B. Based on Sheet 21 of 26, Grading Plan, please demonstrate that Lots 73 through 79, inclusive,
have a suitable and developable lot envelope for future house construction, that does not
require subsequent lot grading or alteration of engineered slopes. The preliminary plat should
identify slopes that should not be further disturbed or altered and that should be protected
from disturbance or alteration in final platting.
See separate exhibit for lots 73 to 79. Note 5 has been added to the grading plan (Sheet
21) indicating protection of slopes.
C. Based on Sheet 21 of 26, Grading plan, please demonstrate that Lots 38 and 54 at the
intersection of Road E and Evergreen Way SE, can observe city standards for functional
separation of the driveway location from intersection of Evergreen Way SE and not interfere
with ADA access ramps at the intersection.
The driveway for lot 38 and lot 54 is intended to be on Road E and not on Evergreen Way
SE. For lot 38, the Functional Intersection Boundary distance needed is 79.5 feet. The
driveway for lot 38 is shown to be graded at the eastside of the lot at a distance of
approximately 130 feet from the return at Evergreen Way SE.
For lot 54, the driveway is proposed to be a shared driveway (with lot 53). The driveway is
thus placed as far from the intersection as reasonable. Sharing the driveway consolidates
the ingress/egress to these lots instead of the driveways being separated with parked
vehicles between them. In addition, Road F is a cul-de-sac that is sloped down and away
from Evergreen Way SE and vehicles approaching the intersection along Road F are
already slowing down because of travelling up to the intersection.
These lots are not intended to be eliminated from the plat. Minimum density is not being
achieved with the lots shown and any additional lot reduction would further reduce the
project density.
D. Will Lots 38 and 54 or any lots with the plat utilize shared driveways? If so please indicate on
prel plat. The use of shared driveways was presented as part of the entire proposal some time
ago but does not appear to be indicated. In fact the use of shared driveways is contradicted by
information shown on Landscape Plan, Sheet L1, where the detail shows individual driveways.
Page 3 July 7, 2016
A detail of shared driveways should be provided on the plans. Shared driveways appear to be
the only way to accommodate any on-street parking within the plat.
Selected lots will utilize shared driveways (lots 53/54, 170/171, 172/173, 174/175,
176/177, 178/179, and 181/182). A typical shared driveway will be shown on
sheet L-1. Shared driveway detail added to the preliminary plat plans.
Thank you for your consideration of this response.
Sincerely,
Geoffrey P. Sherwin, PE
Principal
AMC Chapter 17.18 Modification of Standards and Specifications
On sheet 1 of the Preliminary Plat plan set the Applicant provides a method of calculating
density per AMC 18.02.065. Originally the Applicant was showing a net developable
acreage of 70.25 which equates to a minimum density of 281 lots within the R5 Zoning
Classification.
The net developable acreage for this project has been revised to accurately exclude areas
within the project site that not considered as developable acreage per the 18.02.065. The
revised net developable acreage for this project is 59.54 acres. As such this development
has a minimum lot yield of 238 single family lots.
The Applicant is proposing 200 single family lots (3.35 dwelling units per acre), 38 lots
short of the minimum density. The primary justification for this shortage is significant
topographical constraints.
The Applicant proposes a wider lot than required by code to give more spacing between
driveways and allow for more topographical relief between lots thereby reducing the need
for retaining walls between the lots.
Accordingly the Applicant is not proposing to meet minimum density but feels that the
project site, and its associated development constraints, justify this modification to
standards and specifications.
In summary the Applicant respectfully requests that the Hearing Examiner support the
above described request to waive minimum density as it applies to this residential
development for the reasons stated above.
Sincerely,
James E. Kirkebo III
Agent for Applicant
November 8, 2016
To: James Webb, PE, Traffic Engineer, City of Auburn Public Works Department
From: Victor Salemann, PE, Jeff Hee, PE, and Isabel Diaz, PE, PTOE, TSI
Subject: Diamond Valley Estates Road B at Road F/C Mini-Roundabout Design Report
Auburn, WA
File No.: MIS08-0017, SEP0-0040
Dear Mr. Webb,
This technical memorandum documents the design criteria for future construction of a mini-roundabout
at the intersection of future Road B and future Road C/F at the Diamond Valley Estates residential
development in Auburn, WA. This document updates the October 17, 2016 memorandum of the same
name, based on comments from Auburn staff.
Development Overview
Diamond Valley Estates is a residential subdivision located off Evergreen Way SE between Kersey Way SE
and Lakeland Hills Way SE. A vicinity map is provided as Figure 1, for reference. The site which includes
202 residential single-family lots is located on land parcel no. 322105-9011.
Figure 1: Vicinity Map
A site plan highlighting the proposed mini-roundabout location is included as Figure 2. Development
accesses to Evergreen Way SE are proposed off Roads B and C/F. Future connections to neighboring
development may be off Road F, to the east of the site, and off Road B, to the north of the site.
A traffic impact analysis report was prepared for Diamond Valley Estates (then known as Parkridge) in
2008. Final traffic impact analysis documentation was in 2014.
SITE
James Webb
Diamond Valley Estates
Road B and Road F/C Mini-Roundabout Design Report
November 8, 2016
Page 2 of 8
Figure 2: Site Plan
Traffic Volumes
Diamond Valley Estates includes 202 single-family lots and generates 202 PM peak hour trips. The
northwest leg of the mini-roundabout serves 52 lots, the northeast leg serves 48 lots with future access
to the north of the site, the southeast leg serves 20 lots with future access to the east of the site, and
the southwest leg provides access to Evergreen Way SE.
Future intersection traffic volumes are illustrated in Figure 3, which assumes some cross-traffic through
Road B and Road F from neighboring development. The volumes are consistent with FHWA
recommendations for a mini-roundabout.
Figure 3: Weekday Daily and PM Peak Hour Intersection Volumes
Mini-Roundabout
Location Road B
James Webb
Diamond Valley Estates
Road B and Road F/C Mini-Roundabout Design Report
November 8, 2016
Page 3 of 8
Mini-Roundabout Design Criteria
The mini-roundabout is proposed to assign right-of-way, reduce speeds through the intersection, and
address sight distance constraints that do not allow the intersection to operate as an uncontrolled
intersection.
A mini-roundabout is proposed at Road B and Road C/F to control this intersection and support the
characteristics described above. The following analyses describe how the proposed mini-roundabout
meets the design criteria from the Federal Highways Administration (FHWA) technical summary Mini-
Roundabouts (FHWA-SA-10-007).
Horizontal Design
Figure 4 provides a concept design of the proposed mini-roundabout and includes general dimensions.
Figure 4: Mini-Roundabout Concept Design
Horizontal design elements related to the proposed mini-roundabout are discussed below:
Size – FHWA states that a mini-roundabout should be made as large as possible within the
intersection constraints; however, the inscribed diameter should not exceed 90-feet. The
proposed mini-roundabout has an inscribed diameter of 75-feet and 19.5-foot lane widths. The
inscribed diameter satisfies the FHWA criteria.
Design Vehicle – “Passenger Car” and “Bus” design vehicle-turn templates, per AASHTO, were
applied to locate and size the central island. The proposed mini-roundabout will accommodate
passenger cars and buses in the circulatory roadway. Figure 5 includes AutoTurn exhibits
showing the mini-roundabout supports a “bus”. The design vehicle (“bus”) does not need to
traverse any of the curbs in the mini-roundabout. Since the mini-roundabout supports a “bus”, it
will also support a “passenger car”.
James Webb
Diamond Valley Estates
Road B and Road F/C Mini-Roundabout Design Report
November 8, 2016
Page 4 of 8
Left-Turn Movements
Through Movements
Right-Turn Movements
Figure 5: Design Vehicle Turn Templates; AASHTO SU-BUS-36 Design Vehicle
James Webb
Diamond Valley Estates
Road B and Road F/C Mini-Roundabout Design Report
November 8, 2016
Page 5 of 8
Design Speed – The proposed mini-roundabout has an approach design speed of 25-mph. The
roundabout and splitter islands will also reduce speed on the downgrades.
Central Island – The central island will be fully mountable and designed with mountable curbs,
like a truck apron.
Placement of Entrance Line – The entrance lines are located to provide the largest circulating
path for the design vehicle with an enlarged central island. The circulating path is set-up so that
the design vehicles will not need to traverse the center island or splitting islands.
Splitter Islands – Figure 6 includes the FHWA illustrates FHWA’s guidelines for splitter islands.
FHWA states that it is desirable to provide 15-feet of additional splitter island length beyond the
crosswalk and that splitter islands when raised (non-traversable) or mountable are
recommended with a minimum area of 50 square feet. The splitter islands on each approach
satisfy the FHWA criteria and the splitter island features and crosswalks do not impede the
future driveway locations:
o The southwest leg of the mini-roundabout includes a mountable splitter island and
marked crosswalk. Beyond the crosswalk, the splitter island will transition to the road
centerline via a painted (full traversable) section.
o The northeast leg of the mini-roundabout includes a mountable splitter island and
marked crosswalk. An additional 15-feet of mountable curb is provided beyond the
crosswalk which transitions to a striped road centerline.
o The northwest leg of the mini-roundabout includes a mountable splitter island and
marked crosswalk. Approaching the crosswalk from the northwest, the road includes a
raised (non-traversable) center median with median breaks intermittently for U-turn
vehicle maneuvers. At the U-turn sections on-street parking will be prohibited.
o The southeast leg of the mini-roundabout includes a mountable splitter island to the
north of the crosswalk and a painted (flush) taper area south of the crosswalk to support
the adjacent driveways. The road approach will be designed as a low speed approach, of
25-mph or less. A marked crosswalk is proposed and the splitter island will transition to
the road centerline via a 15-foot long painted section. The painted taper-section
extends past the shared driveway nearest the mini-roundabout. A painted section
across one driveway is not unreasonable and does not physically impede vehicle
movement to/from the driveway.
Figure 6: Splitter Island Dimensions
James Webb
Diamond Valley Estates
Road B and Road F/C Mini-Roundabout Design Report
November 8, 2016
Page 6 of 8
Pedestrian Design Treatments
Pedestrian crossing volumes are minimal, and are projected to satisfy the FHWA requirements. At the
northwest and northeast road approaches the splitter islands will be designed to support a small
pedestrian refuge area in the center of the splitter island for two-stage pedestrian crossing. The
proposed mini-roundabout will be designed to support pedestrians and ADA guidelines.
Bicycle Design Treatments
Bicycle volumes are minimal, and are projected to satisfy the FHWA requirements. The proposed mini-
roundabout will be designed to support bicyclists.
Sight Distance and Visibility
Sight distance guidelines from the Roundabout Guide1 were used to review sight distance at the
roundabout. Figure 7 illustrates the sight distance measures with the proposed mini-roundabout.
1 Rodegerdts, L. A., et al. Roundabouts: An Informational Guide, 2nd Edition. National Cooperative Highway
Research Program Project 03-65A. Transportation Research Board, National Academy of Sciences, Washington,
D.C., Work in progress, estimated publication 2010.
James Webb
Diamond Valley Estates
Road B and Road F/C Mini-Roundabout Design Report
November 8, 2016
Page 7 of 8
Figure 7: Entering, Circulating and Right-Turn Corner Mini-Roundabout Sight Distance
Vertical Design
The proposed mini-roundabout will be designed to be outward draining. The proposed mini-
roundabout is on a 4.25% grade.
Pavement Markings and Signs
Proposed pavement markings and signage will consistent with the FHWA, MUTCD2 and Roundabout
Guide guidelines. Pavement marking arrows will be added to the circulating roadway in front of each
entry to direct drivers of the counter-clockwise circulation. Yield signs will be provided at each approach
along with advance warning signage for a circular intersection. Figure 8 includes examples of pavement
markings and signage from the FHWA guide.
Figure 8: Pavement Marking and Signage Examples (FHWA)
2 Federal Highway Administration (FHWA). Manual on Uniform Traffic Control Devices. FHWA, Washington, D.C.,
2009
James Webb
Diamond Valley Estates
Road B and Road F/C Mini-Roundabout Design Report
November 8, 2016
Page 8 of 8
Lighting
The City’s street light guidelines are sufficient to provide adequate lighting for vehicles, pedestrians and
bicyclists at a mini-roundabout.
Other Design Details and Applications
The proposed mini-roundabout is designed to manage driveway access to adjacent properties. All
driveway approaches are located outside of the marked crosswalks, and are at minimum 30 feet or
further from the circulating roadway.
Driveways on the northwest leg of the intersection are right-in/right-out since the roadway has a center
median and intermittent U-turn sections.
As stated previously, the painted splitter island taper on the southeast-leg of the mini-roundabout (Road
F) extends past the shared driveway on the north side of the road. The painted splitter island does not
impede movements in/out the driveway.
We trust that this report will provide you with sufficient information to address your final comments
regarding this intersection.
November 3, 2016
To: James Webb, City of Auburn
From: Jeff Hee, TSI
Subject:Diamond Valley Estates Mini-Roundabout
Response to Comments received November 2, 2016
This memorandum serves as a cover page to the update design report and conceptual plan. Staff
comments are listed followed by our responses:
October 17, 2016 Diamond Valley Estates Road B at Road F/C Mini-Roundabout Design Report:
Staff Review Comment: TSI Response:
1. Page 2, Figure 3: These volumes do not seem to
account for traffic generated by the adjacent
developments.
1. The figure was expanded and updated to more
reasonably account for traffic for adjacent
developments.
2. Page 2, Figure 3: Is this much traffic really going
to be internal to the neighborhood?
2. See response #1
3. Page 2, Figure 3: These are existing volumes.
No discussion of horizon year for analysis and
why assuming no growth is OK
3. Horizon year growth within Diamond Valley
Estates is negligible, the proposal is for 202
total single-family lots. The mini-roundabout
volumes are based on where the lots are in the
development, and there are 120 total lots
accessible within Diamond Valley Estates to the
northwest, northeast and southwest of the
mini-roundabout.
Some cross-traffic was assumed in the previous
analysis. The volumes at the mini-roundabout
were increased some based on this comment
to address more cross-traffic. 200 trips are
assumed to the north of Diamond Valley
Estates and 100 trips are assumed to the east
of Diamond Valley Estates.
4. Page 3, paragraph 1: These are not the reasons
why a RAB is being installed at this intersection
4. The mini-roundabout is proposed to assign
right-of-way, reduce speeds through the
intersection, and address sight distance
constraints that do not allow the intersection
to operate as an uncontrolled intersection
5. Page 3, last bullet: Exhibits should be included
as an attachment.
5. “Bus” turn templates are provided as an
additional figure in the report. The “AutoTurn”
shows a bus can traverse through the mini-
roundabout without traveling over any curb
areas. Since the mini-roundabout can support a
James Webb, City of Auburn
Diamond Valley Estates Mini-Roundabout Response to Comments #1
November 8, 2016
Page 2 of 3
bus, a “car” is also supported by the proposed
design; a separate car turn template is not
provided.
6. Page 4 last bullet: Why can the minimum not
be achieved on this approach?
6. The area-section of the splitter island to the
north of the crosswalk at the southeast leg of
the min-roundabout is sufficient for a raised
section, the design was revised. The taper
section will be maintained as a painted section
to facilitate driveway movements. The taper
section does extend past one shared driveway;
this section is flat; and will not physically
impede driveway movements.
7. Page 4, last paragraph: ADA should be
discussed here, not in the bike section.
7. The last statement in the bike section was
relocated to the ADA section of the document.
8. Page 4, last paragraph: How was this
determined and what does minimal mean?
8. The site is no within an urban area, so the
pedestrian volumes are not likely to be
significant.
9. Page 5, Figure 6: What is the purpose of the
gore striping on this corner? Should the
curbline be moved or a concrete apron be
provided?
9. The gore striping was removed and the north
corner of the mini-roundabout was revised, the
curb section is maintained to support larger
vehicles (i.e. “bus”).
10. Page 5, Figure 6: Why is this only shown on two
of the four intersection corners?
10. The missing figure was added back into the
report.
11. Page 6, 3rd paragraph: City guidelines do not
include any special considerations for
roundabouts. Does following the standards
provide acceptable lighting for the
roundabout?
11. For a mini-roundabout the city’s street light
standards are appropriate. If a larger-more
standard roundabout was proposed, the
lighting requirements would be different.
12. Page 6, 4th paragraph: Add driveway locations
to figures.
12. Driveway locations are provided in the updated
graphics and concept design.
October 17, 2016 Diamond Valley Estates Road B at Road F/C Mini-Roundabout Concept Plan:
Staff Review Comment: TSI Response:
1. Diameter notation: 35.52. 1. An island diameter of 36-feet is dimensions on
the mini-roundabout plan.
2. Southeast leg of mini-roundabout: Why no
physical splitter island on this approach?
2. This splitter island was modified to include
raised curb to the north of the crosswalk. The
section south of the crosswalk is painted to
facilitate movements from a driveway.
3. North corner mini-roundabout: Why does this
corner have a gore area? Should the curbline
be revised or replace with a concrete apron?
3. The gore strip was removed. The curbline
remains with the intent to support larger
vehicles.
4. Full intersection: Driveway location for
adjacent lot need to be shown.
4. Driveway at the mini-roundabout are shown in
the updated concept figure.
James Webb, City of Auburn
Diamond Valley Estates Mini-Roundabout Response to Comments #1
November 8, 2016
Page 3 of 3
5. Intersection corners: R=? TYP 5. The corner radii are shown on the concept
plan; typical radii are 44’.
I trust these responses will be sufficient for the City. Please contact TSI should you have any questions
or need further clarification.
NOTICE of APPLICATION
PARK RIDGE DEVELOPMENT AGREEMENT
APPLICATION NUMBER & NAME: MIS08-0017 / PARK RIDGE
APPLICANT: Todd Ward APPLICATION FILED: Oct. 13, 2008
C/O Betty Frye COMPLETE APPLICATION: Nov. 10, 2008
PO BOX 652 NOTICE OF APPLICATION: Nov. 24, 2008
Fall City, WA 98024
Contact: Jeff Mann, Apex Engineering INC.
2601 S. 35th ST, #200, Tacoma, WA 98409
Phone: 253-473-4494
PROJECT LOCATION: Park Ridge is located on both north and south sides of the future
extension of Evergreen Way SE and just east of Lakeland Hills (Quincy Ave. SE). Park
Ridge is west of the Preliminary Plat of Kersey III Div. 2. and southwest of Kersey Way SE.
at 49th St. SW (if extended).
Parcels: 3221059010, 3221059011, 3221059030 & 3221059037
DESCRIPTION OF PROPOSAL: Approval of the proposed Park Ridge Development
Agreement (DA). Future subdivision of approximately 81 acres; creating 256 lots for mostly
detached single family homes and approximately 40 townhomes using development
standards through a proposed DA with the City of Auburn. Primary access to the property
will be provided by Evergreen Way SE. Wetlands and slopes will be included into open
space areas. Trails and sidewalks are proposed for pedestrian use. Public water, sewer,
stormwater control, and roads will serve the plat. Traffic calming circles will be installed at
key intersections to slow traffic and provide for safer streets.
AUBURN PROJECT CONTACT: Karen Scharer, Senior Planner
E-mail: kscharer@auburnwa.gov & Phone: 253-931-3090
STUDIES SUBMITTED WITH APPLICATION: Final Environmental Impact Statement
(FEIS) for Kersey III Preliminary Plat w/DEIS and Appendices (SEP00-0040); Draft
Development Agreement; Conceptual Development Plans with grading, utilities,
landscaping; Signage Plan; Architectural Design Guidelines; and other documents.
OTHER PERMITS AND PLANS WHICH MAY BE REQUIRED: Subdivision/Plat, Building
Permits, Grading Permit, WA St. Forest Practice Permit
Park Ridge Notice of Application
November 24, 2008
Page 2
E:\Multimedia\Planning\Tina\EX 24 MIS08-0017 Park Ridge DA Notice of Application .doc
STATEMENT OF CONSISTENCY AND LIST OF APPLICABLE DEVELOPMENT
REGULATIONS: If adopted, the development agreement and the development
standards in the agreement govern during the term of the agreement, or for all or that part
of the build-out period specified in the agreement (RCW 36.70B.180). Auburn City Code
regulating Development Agreements is found within ACC 14.21. This project is subject to
and shall be consistent with the City of Auburn Zoning Code, Critical Areas Code, Auburn
Construction Standards, Road Standards, Storm Water Utility Code, Excavation Code and
Grading Code, unless specified differently with the DA. Mitigation measures may be
required based on the FEIS or other subsequent environmental review.
COMMENT PERIOD: There is a 15-day comment period ending December 9, 2008.
Written comments may be submitted to the City of Auburn, Attn: Karen Scharer at the
address below. You may review the application and any documents at City Hall, address
listed below. If you wish to receive future notices, cop ies of reports, and the decision on
this application together with any appeal rights, please notify the City by providing your
name, mailing address and please reference application MIS08-0017.
PUBLIC HEARING: A public hearing is required for this proposal. A separate notice will
be issued when the hearing date has been scheduled.
City of Auburn
Community Development and Public Works
25 West Main
Auburn, Washington 98001
PPUUBBLLIICC MMEEEETTIINNGG IINNVVIITTAATTIIOONN
You are invited to a public meeting hosted by the applicant of the:
PARK RIDGE DEVELOPMENT PROJECT
When: Thursday, November 20, 2008 @ 6:30-8pm
Where: Ilalko Elementary School Gymnasium
301 Oravetz Place SE, Auburn, WA 98092
PROJECT DESCRIPTION: The proposal includes a subdivision on approximately 81 acres with
256 lots for detached single family homes using development standards through approval of a
Development Agreement with the City of Auburn. Primary access to the property will be provided
by Evergreen Way SE. Wetlands and slopes will be incorporated into open space areas. A network
of trails and sidewalks will enhance the property to encourage pedestrian use. Public water, sewer,
stormwater control, and roads will serve the plat. Traffic calming circles will be installed at key
intersections to slow traffic and provide for safer streets.
MEETING PURPOSE: The intent of this meeting is to facilitate an early informal discussion
between the project developer and neighbors regarding the proposal. This meeting is in addition to
future hearings that will be conducted by the City of Auburn.
Park Ridge Project Location
If you have questions please contact Jeffrey Mann at 253-473-4494. If you are unable to attend
and wish to send written comments please send to:
Apex Engineering PLLC
2601 S 35th St, Ste 200
Tacoma, WA, 98409