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cnviror3., , .hlal Review Committee Staff Report
FRrS ELECTRONICS _ LUA- 14052, ECF
RcPORT OF MAY 8. 2001 Page 6 of 6
Surface Water
Impacts: The subject site is located within 300 feet of the Lake Washington shoreline and is part of the East Lake
Washington Drainage Basin. There are no surface water features or sensitive areas on the property. The 23-acre site
is currently developed as an asphalt parking lot with 100% impervious surface. The site is relatively flat and gently
slopes from east to west with grades of less than 1.5%.
A Preliminary Drainage Report prepared by the DLR Group, dated April 5, 2001. was submitted with the project
application. According to the report, site runoff currently sheet flows across the site to the west where it is collected in
catch basins prior to being discharged to the existing storm facilities in Garden Avenue North.
As proposed, surface runoff from new parking areas, drives, and walkways would be collected by catch basins and
runoff generated from the rooftop of the proposed building would be collected by roof drains. Each would then be
tight -lined to the proposed conveyance system. The conveyance system would discharge to the existing system in
Garden Avenue North. The project would provide storm water runoff control and water quality treatment in accordance
with the 1990 King County Surface Water Drainage Manual as adopted by the City.
Mitigation Measures: No further mitigation is recommended.
Nexus: N/A
4. Earth
Imp: A Geotechntcai Report, prepared by Kleinfelder dated March 23, 2001, was Submitted with the project
application. According to the report, the subject site was marshland until the water level of Lake Washington was
lowered 10 feet in 1916 as a consequence of the construction of the Lake Washington Ship Canal. Subsequently,
upwards of 10 vertical feet of fill was placed over the entire east bank of the Cedar River Delta area, including this site.
Field explorations indicates deep, soft soils, as well as several feet of peat, which will undergo continuous and
significant settlement, underlie the site. Therefore, building construction would require a pile foundation system for
proper building support. Floor slabs should also be structural slabs supported on grade beams because of the deep,
soft soil conditions.
The report concludes that the site contains significant geotechnical issues that would need to be addressed for the
proposed development of the site and includes several recommendations with regard to site preparation and earthwork
activities, as well as seismic and foundation designs. In order to appropriately mitigate potential impacts from the
construction of the site, staff recommends the applicant be required to comply with all recommendations contained
within the Geotechnical Report submitted with the land use application.
Minimal grading is proposed and would be limited to excavation necessary for building foundations. In order to
properly mitigate potential short term erosion impacts from the disturbance of the site, the applicant would be required
to implement an approved Temporary Erosion and Sedimentation Control Plan (TESCP) and utilize Best Management
Practices (BMP) during site preparation and project construction.
Mitigation Measures: The applicant shall comply with all recommendations contained within the Geotechnical Report
dated March 23, 2001, prepared by Kleinfelder, with regard to site preparation, building construction and design. The
satisfaction of this requirement shall be subject to the review and approval of the Development Services Division prior
to the issuance of building permits.
Nexus: SEPA Environmental Regulations and adopting ordinance.
E. COMMENTS OF REVIEWING DEPARTMENTS
The proposal has been circulated to City Departmental / Divisional Reviewers for their review. Where
applicable, these comments have beer, incorporated into the text of this report as Mitigation Measures and/or
Notes to Applicant.
X Copies of all Review Comments are contained in the Official File.
Copies of all Review Comments are attached to this report.
Environmental Determination Appeal Process Appeals of the environmental determination must be
filed in writing on or before 5:00 PM May 25, 2001. Appeals must be filed in writing together with the required
S75.00 application fee with: Hearing Examiner, City of Renton, 1055 South Grady Way, Renton, WA 98055. Appeals
to the Examiner are governed by City of Renton Municipal Code Section 4-8-1 10-B. Additional information regarding
the appeal process may be obtained from the Renton City Clerk's Office, (425) 430-6510.
ercrpt