1315 PACIFIC AVE 2018-01-01 MF Import

C�scadi�Subduction Zone Intr�plate Eart6quakes. Cascadia Subduction Zone inVaplate earthquakes occur within the subducting Juan de Fuca Platc at depths of 30 to 40 miles within westem Washington. Intraplatc carthquakes arc cxpccted to have durations ranging up to 45 seconds and magnitudes rangins up to 7.5. Thc Olympia 1949(magnitude 7.1), the Scattic 1965 tmagnitude 6.5),and the Nisqually 2001 (magnitude 6.R)are considcred to bc intraplate earthquakes. Selamle DesJyn We rccommend the following 2006 Intemational Building Codc (IDC) parameters for Site Class, shott period spcctnl responsc acceleration(SS), I-second period spwtral response acceleration (S�), and Scismic Coet'ticicnts F�and F�.. 200819C P�rr�Ma Fboo�mMqb V�Mw Slte Class C Short Penod Spectrel Response Acceleration,SslPercenl g) _ 179�__ b5econd Penod Speclral Response Accekralion,S,(percent g) _ _ 42 �_ __ Seismic CoeBicient,F,, ��0 Seismic CoeRcienl,F� ��39 Llquefactlon Liqucfaction refcrs to thc condition whcre vibra�ion or shaking of the ground, usually from catthquake forces, results in thc devclopmcnt of exccss pore pressurcs in satura�ed soils with subsequent loss of strcngth in thc dcposit of soil so affcctcd. In gcncral,soils that are susccptiblc to liquefaction includc vcry loose to mcdium dense,cican to silty sands that are bclow the watcr table. Our analysis indicates that thc soils that underlic thc proposed building area have a low risk of liquefying bccause of the densiry of thesc soils and thc dcpth to groundwatcr. Grnund Ruptcre Gcologic maps indicate that the south Whidbcy Island Pault is locatcd roughly 7 miles southwest of the site. Because ot thc thickncss of thc Quatcmary scdiments below lhe site, which am commonly morc than 1,000 fcet thick,Ihc potcntial for surfacc fault rupturc is considcrcd remotc. EXCAVATION SUPPORT General Sile dc��clopmcnt will rcquirc rcmo��il of cxisting buildings, pavcments, buried utilities, and other slructures prescnt at thc sitc. Wc cstimatc crcavations on thc ordcr of 12 fcet will bc ncccssary to obtain thc proposed finished Iloor elevalion for thc parking Ic��cl. Additional excavation will also be requircd to rcmovic exis�ing GII and/or contaminatcd soils as dcscribed in our May 30, 200R environmental report. Thcse soils arc estimated In extcnd approximatcly 15 to 16 fect dcep. Soil conditions cncountercd within the planned cxca��ation deplhs consi�i of a surficial laycr of fill (up to 7 to 20 fect thick) overlying glacially consolidated soils (outwash and glacial till). Pcrched groundwater was encountered during drilling at depths ranging from 12 to 1 R Ccct and moist to wet soils wcre observed in scveral samples. Temporary shoring will bc rcquircd to rctain thc adjaccro stmcts and accomplish the excavation at thc property boundaries. Conecntional cantilcver soldier pile walls can be considered for supporting the cxca��alion. I3ecause the ahoring will retain primarily very loose to loose fill,conventional soil nail walls r�ic.�'o nuaon�-nn Pa�¢eS GEOENGIMEE�� Junr R.:00,5' 1