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' <br />`;_rn�t�l �'.Ic��l�nr••-a,��l\C. <br />. i�y.VlSl.i�l%, �.:i_�._� •.. <br />� 1;YCCU'1'lVl's SU11�9AK1' <br />This report prescnts our analyscs cmd recommendations for thc r�dministration I3uilding and <br />jGaragc portion of thc Snohomish County Campus. <br />Subsurfacc Condilions. The sitc soil consists o( ei.IC18IIy OVCRiCi(ICiI IIII, ouhvash, and <br />lacustrinc deposits. Rclativcly minimal amounts of fill (typically 3 to 8 feet thick) wcre <br />cncountcrcd �vithin the garage footprinL At thc southwest corncr �f the proposed Administration <br />f3uilding, wc cncountcred 28 fcet o( vcry loosc fill. Advancc ouhvash is thc primary watcr- <br />bc.�ring laycr cncountcrcd in thc boiings, and this unit appcars to bc widcr confining pressurc. <br />Thc adv.mcc outwash laycr is about 5 to 2S fcct thick and about 20 to 35 fcct below gradc within <br />thc garage footprint. Soil and groundwatcr ���ith elevatcd Icvels of petroieum hydrocarbons was <br />cncountcmd at scvcral locations �aithin thc advancc out���ash and thc lo�ecr portion of thc glacial <br />till. <br />I;ffecl on Design and Conslruction. Thc effect of thc subsurface conditions on the design and <br />conswction of thc Administration I3uilding :md Garagc can bc b�ic(ly summarircd as follows: <br />Tcmporary soil nail shoring ���alls cire suitablc for thc garB�C CXC:IV.lU00 1S I011d :1S II1C <br />ground���atcr intlo��� is controlled. <br />Potcntially contaminated soil and ground�eatcr must bc handled and disposed of properl�� <br />— �his nuq� bc a long-tcrm condition for thc ground���atcr. <br />Thc glacially ovciridden soil ���ill support sprcad footing garagc foundations.Thc dcsicn <br />for thc AdminisU�tion I3uilding is not yct undcn�•ay, but thc stnicWrc may rcc�uirc a <br />combin�:tion found:uion system (rclativcly shallo��� sprcad footings and dccp foundations <br />such as cmbcrc;�st pilcs or drillcd sh:dts). <br />Seismic Design. The project is located in a modcrately active seismic zone. In accordance �eith <br />thc 1997 Uniforni Buildin�t Code (UI3C), the site is dassificd as a Soil Type S�. <br />I�ow�dation llesign. "Chc garagc can bc supported on sprcad footing toundations �vith a <br />ma�imum allo���ablc bcaring pressurc of I6 kips per squarc foot (ksn bcaring on undisturbcd <br />��laeinlly o��emdden soil. The proposed tunnel may cncounter fill soils t the footing Icvel; wc <br />rccommcnd compacting thc upper 2•3 inchcs of thc c�isting fill and dcsigning the footings for <br />± ksf :illoaahlc hcaring c.ip;icit�•. <br />z i- i-n"aa-iKx. � u,� p�i�a <br />3 l - I -09 W �-005 <br />