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20180620135843.pdfN G l\' NELSON GEoTEcHNIc¡rL Ä.ssocI^A.TEs, IHc. GËOTãCHNICAL TNçINXENS & GNOIOCISTS Ëngincedng-ûeciogy B ra*ch 5526 lndustry l"anx, H2 6ast Tfenatcheë, VYÁ, 98802 ts09i 6ó5-?696 ' rÄX {509) 665"?692 Main ùlïiee t?31I * l35rr Ave Nr, A:500 Woodinvillc, WÀ S8072 (4:5) 486-1ı69 , fi¡.X (425) 48t-?5¡0 June 14,2018 Mr. James Weis 50 Mill Plain Road Danbury, CT 0681 I jweis@techair.com Geotechnical Plan Review Letter Weis Residence Development 16630 - 74th Place West Edmonds, Washington NGA Job No. 9887818 Dear Mr. \ü'eis: This letter presents the results of our recent geotechnical engineering review of the plans for the Weis Residence project located at 16630 - 74th Place West in Edmonds, Washington. We previously prepared a geotechnical evaluation for the project dated April 24,2017 . As a part of this evaluation, we provided geotechnical recommendations for the proposed development. For our use in preparing this plan review and comment response letter, we have been provided with the following document: o Plan Sheets Cl and C2 titled ooWeis SFR," dated October 6,201i. PLAN REVIEW We have reviewed the geotechnical aspects of the provided plans and found the plans to be in general compliance with our recommendations as presented in our previous geotechnical report prepared for this project. We were informed that previous plans for the residence included rockery retaining walls and dispersing stormwater onto the steep slope below. All rockeries along the downslope side of the residence and stormwater dispersion have been removed from the current plans. Stormwater drainage from the residence is to be tightlined through a 6-inch HDPE pipe down to the very lower western portion of the property and into an existing stormwater system. The HDPE pipe is to be collared and anchored to the slope at 20 foot intervals. In our opinion, the proposed stormwater HDPE pipe sVstSffiS¡¡JB ülîY 0OPY ruN 2t} ?rji8 %hfieffiãft''ÉE* Geotechnical Plan Review Letter Weis Residence Development Edmonds, Washington NGA File No. 9887818 June 14,2018 Page2 feasible and should perform adequately. We recommend that all stormwater associated with the proposed development be directed to flow into this system. In addition to the recommendations provided in our previous report, we recommend that the lower western and western l5 feet of the northern and southern residence foundations be embedded a minimum of four feet into the native glacial soils encountered within the site, to provide additional protection against any shallow failures on the steep slope below. All other foundations can utilize standard foundation depths. It appears that some filling may take place within the sloping area below and to the northwest of the proposed access driveway. We recommend that any fill placed within this area be placed as structural fill as discussed in our previous report. Any fill placed on sloping ground should be placed on graded level benches as discussed in our previous report and adequately compacted and vegetated. The slope fill should have a maximum finished gradient of 2H: 1V. No water should be allowed to flow over the slope. It also appears that a proposed retaining wall is to be constructed within the upper southeastern corner of the property. This retaining wall may be as high as 8- to lO-feet and situated in very close proximity to the eastern and southern property lines. Due to the close proximity of the proposed wall to the property lines and neighboring roadway, it may be difficult to maintain temporary excavation slope gradients as described in our previous report to allow construction of the wall. If safe excavation slopes cannot be maintained, soldier pile wall shoring systems may need to be incorporated into the overall site design. We are available to provide recommendations for any proposed shoring systems as needed once grading plans are finalized. All other recommendations provided in our previous report should be strictly followed during the design ofthe project and during the construction phase. CLOSURE 'We recommend that NGA be retained to provide monitoring and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork activities comply with contract plans and specifications. o-o-o ,VEISO'V G EOTECH N ICAI ASSO CI ATES, I N C. Geotechnical Plan Review Letter Weis Residence Development Edmonds, Washington NGA File No. 9887818 June 14,2018 Page 3 We appreciate the opportunity to provide service to you on this project. Please contact us if you have any questions regarding this letter or require further information. Sincerely, ,vEtso/v GEoTEcHNtcAt Asso ct ATES, I N c. Lee S. Bellah, LG Project Geologist Khaled M. Shawish, PE Principal LSB:KMS:dy 2883 LEE S. BELLAH NEISOÍV GEOTECHNICAI ASSO CIATES, INC.