3505 SHORE AVE 2016-01-01 MF Import

Gaotechnical Enhineuing Letter 3505 Shoro Avenue Deck Additiun Everett,Washington May?6,1A10 NGA File No. 827110 Page 6 The site slope is consideied stable with fespect to deep-seated failures. There is a potential for sbnllow sloughing snd erosion events to occur on the stecper poRions of thc slope. In our opwon, tt�e planned setbeck of over 50 fcet from the top of the steep slope to the deck foundetions should be adequate and provide a reasonable usable flme for the structure. This setback from the stap slope should reduce potential impact of the development on the steep slope, and to also icduce the rislc of undermining the residence should any slope failuros take plece. The dxk foundations could be designed es conventional shallov� foundations. 'fhese foolings should oxtend through any lovse surficinl soil or undoc:�mented fill and be founded on the undalying medium dense or bener mtive soils or structuesl fitl extending to these soils. Medium dense soils should typically bc encountered approximately two ro four fcet below the ezisting surface. NCiA ahou�d be� Oo awlu�te fo�ndnton beuing wil at the time of comauaioo. 1'he soils enwuntaed on this site are considered moistwe-sensitive and will distucb easily when wet. To lessen the potrntial impacts of construction oa the slope and to reduce wst avemms and delays, we recommend t6at conswction take place during the dria summer months if possibla If conshuction takes place during the rainy months additional expeoses and deleys s6ould be expected. Thes�exua ezpenses could include additional erosion conuol and tempo�ary drainege measunrs to protxt the slope,placement of e blanket of rock spalls to protect exposed subgredes,and the uad for importing all-weather materials for swctural fill. Under no circumstanccs, should wata be allowed to tlow over or concentrate on the site slopes, both during conswction and after conswction l�as been completed. We �ecommeod that stormwater iunoff from the roof drains,paved areas,and yard dcains be tightlined to a suitable discharge point. The steep slopes should be protected from erosion. We rocommend that vegetation on and near the stap slope be maintaincd and that eny disturbed areas be replented to mesteblish vegetation es soon es possibla Sronnwater tunoff should not be allowed to concrntcate and flow over the slope. Specific recommendations for erosion control are presented in tl�e Erosion Control aod Slope Protection Measures subsection of this letter. NELSON GEOTECHNICAL ASSOClA TES, lNC. � `�� � � �.=�