20-101386-CO-Response Letter-04-18-2022
April 18, 2022 Job No. 1886-001-016-0015
Mr. Leonard Spadoni
City of Federal Way
33325 8th Avenue S
Federal Way, WA 98003
RE: Permit #20-101386-CO
Woodbridge Building A; 3120 South 344th Street, Federal Way
Dear Mr. Spadoni:
ESM Consulting Engineers, LLC, is submitting the following responses your prior email
comments regarding Conditions of Approval #31 and #35, received April 7, 2022.
In an effort to provide concise and direct responses, we have copied the review comments
below in italics and our responses are in bold.
31. The existing pavement on Weyerhaeuser Way South (south of the site), from the
proposed truck entrance to the SR-18 interchange must be fully reconstructed
(subgrade soils and new pavement) to accommodate the expected truck traffic
load. The applicant shall provide the pavement design for city review and approval
prior to engineering plans submittal. Once the pavement design is approved by
the city, the development shall perform full depth reconstruction of the roadway
segment impacted by the truck traffic. (A SEPA mitigation measure.)
ESM has previously submitted a revised geotechnical report dated January 30,
2020 that includes the new proposed pavement design for city review. While
formal approval for this pavement design has not been received from the City, we
assume the proposed pavement section is acceptable to the City.
The portion of Weyerhaeuser Road South that is receiving full pavement
reconstruction, falls under Redevelopment, per FWRC 19.30.120, because it is
more than 35% impervious, per (1) (c) Redevelopment which involves the repair
or replacement of 5,000 square feet or more of an impervious surface, when such
redevelopment is not part of a routine maintenance activity. Therefore, this is a
non-conforming water quality improvement, being brought into compliance with
current standards which consist of enhanced water quality treatment.
The Building A construction plan set, and Technical Information Report (TIR) have
been revised to show the full pavement reconstruction area (1.7 acres) with
enhanced water quality treatment. The proposed enhanced water quality
Mr. Leonard Spadoni
April 18, 2022
Page 2
treatment device consists of a Modular Wetland vault, which was chosen to
provide the same type of water quality treatment that will be used for the Building
A onsite enhanced water quality treatment. The proposed Modular Wetland vault
will treat a functionally equivalent area of both combined pavement reconstruction
areas that are located north and south of the Weyerhaeuser Way South bridge.
Since the drainage from both sides of the bridge connects within ½ mile
downstream, this is an acceptable feasible option for providing enhanced
treatment. The location of the proposed Modular Wetland vault was chosen such
as fit within existing City right-of-way and provide the adequate drop through the
structure.
35. The Right-of-Way Modification issued on June 22, 2018, includes widening of
Weyerhaeuser Way South. As a part of building permit approval, water quality
treatment shall be provided for new pollution-generating surfaces within the public
right-of-way. Flow control shall also be provided. All stormwater treatment and
flow control requirements shall meet the regulations in place at the time a building
permit application is received.
The proposed pavement reconstruction along the Weyerhaeuser Way South will
be completed with Building A and receive enhanced water quality treatment. The
widening of Weyerhaeuser Way South will be completed with Building B and will
generate new impervious pollution generating surface that will be evaluated for
water quality and flow control with the Building B construction plan set and TIR.
If there are any questions or a need for further clarification, please feel free to contact me
at (253) 838-6113 and we would be happy to discuss them with you.
Sincerely,
ESM CONSULTING ENGINEERS, LLC
LAURA BARTENHAGEN, P.E., LEED® AP
Principal
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