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Geotech Response.pdfa s s o c i a t e d earth sciences December 4, 2017 Project No. 140265EO01 Mr. Roy Gursli c/o Cornerstone Architectural Group 6161 NE 175th Street, Suite 101 Kenmore, Washington 98028 Attention: Mr. Steve Barnes Subject: Geotechnical Plan Review and Response to City Comments Edmonds Apartments 8509 244th Avenue SW Edmonds, Washington Dear Mr. Barnes: As requested, we have reviewed geotechnical engineering aspects of project plans that were provided to us, which are listed below. We are familiar with the project as a result of completion of subsurface explorations and issuance of a geotechnical engineering report for the project titled "Subsurface Exploration, Geologic Hazard, and Preliminary Geotechnical Engineering Report," dated February 11, 2016, for the subject project, along with the subsequent design -phase geotechnical consultation. For our use in preparing this letter, we have been provided with the following review comment letters: • Civil Review Comments — Engineering Division, prepared by City of Edmonds staff, dated September 21, 2017. (Civil Comments) • Stormwater Review, prepared by City of Edmonds staff, dated August 15, 2017. (Stormwater Comments) We have been requested to respond to Item 3 in the Civil Comments and Item 11 in the Stormwater Comments. These items, along with our responses, are included in the following paragraphs. CITY COPY RESUB Kirkland Office 1 911 Fifth Avenue I Kirkland, WA 98033 P 1425.827.7701 F 1425.827.5424 7 Everett Office 1 2911 % Hewitt Avenue, Suite 2 1 Everett, WA 98201 P 1425.259.0522 F 1425.827.5424 DEC O 8 201/ Tacoma Office 1 1552 Commerce Street, Suite 102 1 Tacoma, WA 98402 P 1 253.722.2992 F 1253.722 9 3ANG DEPARTMENT www.aesgeo.com CITY OF EDMONDS Civil Comments, Item 3: "Please provide a written response from the geotech that the civil plans are consistent with the geotech report." Plans that were provided for our review included: o Civil Sheets C0.1, C0.2, C1.1, C1.2, C2.1, C3.1, C3.2, C4.1, C5.1, C6.1 through C6.4, and Water/Sewer Sheets 1 through 4, prepared by Terra Forma Design Group, Inc., dated December 4, 2017 (Sheet C6.4, prepared by Associated Earth Sciences, Inc. (AESI), dated November 2017). Based on our review of our February 11, 2016 report and the currently proposed project, it is our opinion that the plans provided to us are generally consistent with the recommendations we provided in the above -referenced report. Stormwater Comments, Item 11: "Sheet C3.1: Detention system specifies a chamber system with an open bottom. The geotech does not recommend infiltration. Additionally, the proximity of the retaining wall immediately to the east will express "infiltrated" groundwater." Based on our review of the provided plans, the open bottom detention system mentioned in the City's comment has been replaced with a closed tank detention system. The bioretention planter also infiltrates and therefore does not meet the geotech's recommendation." We understand that the proposed bioretention planter is intended as a filtration system, with an underdrain that discharges to the detention system, and that no infiltration was assumed in the sizing of the detention system. We appreciate the opportunity to be of continued service. If you have any questions regarding this letter or other geotechnical engineering aspects of the project, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. K1rkIa9#,.Wa ington Q'� �. Syr_• �7q�� J pF WASy/ 9 p?- �� O� Q 23580 FGfsl'C�� N?ni �r1 Kurt D. Merriman, P.E. Senior Principal Engineer 2 KDM/ms-140265E001-5 • ProJects\20140265\KE\WP