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i <br />� <br />S: ; ;r•a�,�ora ���.^��� so�:. i«c. <br />Thc results of the geophysical survey did not provide definitive evidencc of a UST bcneath the <br />� plara arca. I-lowcver, marked utilitics (cithcr marked with paint on the gro md surface or shown <br />on projcct survcy maps) and several pipcs werc encountered. These pipes are likely associated <br />� with former utility scr��iccs to prc��ious sitc development. No contamination source was apparent <br />in thc arca cvaluatcd using GPR. <br />' <br />8A GtiOLOGY <br />� 1'hc gcologic dcposits prescnt in thc viciniry uf thc site wcrc largcly dcpositcd during thc last <br />glacial advancc, known as thc Vashon Stade of thc Frasicr glaciation. As thc Vashon icc shcct <br />� advanced from the north, drain;:ae from Puget Sound ���as blocked, and glaciolacustrine silt and <br />clay, with some sand seams, �vere deposited in a proglacial lake. As the glacial ice sheet <br />� ;idvanccd furihcr, sand and somc gravcl (ad��ancc out���ash) ���cro dcposited on top of thc <br />gl:�ciolacustrinc sedimcnts as a broad out���ash plain in front of thc glacicr. Thc advancc out���ash <br />� typically is gradational with lhc undcrlying glaciolacustrinc dcposiis at Uic basc (intcrbeddcd <br />sand :md silt) and coarsens up�vard to snnd and then gravclly sand at lhe top. The glacial ice <br />cvcnluall} ovcrrodc lhc arca, compacting thc undcrlying scdimcnts and depositing lodgmcnt till <br />� at lhc b:�sc of thc glacicr. Thc till is a non-so�tcd mixuu'c of day, silt, sand, :md gr.rvcl with <br />scattcrcd cobblcs and bouldcrs. <br />� <br />� <br />').1 Cencral <br />9.11 5U13SUKI�AC1's CONDITIONS <br />� Thc subsurfacc conditions at thc sitc �ticrc cvalu:uc� bascd on conditiuns cncountcrcd in boiines <br />13-7 through Q-1 S. A dcscription of thc soil and ground���atcr conditions disclosed by thc borings <br />� is presentcd bclow. Figures 3, a and 5 present generalized subsurface profilcs running north- <br />south in thc cast half of thc sitc, and cast-���cst in thc north half of thc sitc. "Chc locations of thc <br />� Uorings :md prof ilrs :u'c sh���� n on Pigurc "_'. <br />'J.2 Soil <br />� As sho�vn on the auached subsurface profiles (Pigures 3 through 5), and as described in the <br />�colog�� scction ahovc, thc sitc's subsurf:�cc conditions gcncraliy consist of Uic follo���ing <br />� ��calu,_i� I:ncrti sl:�rting Irnm Ihc �sroun�i surfacc: glacial till, ad�•:mcc out�cash, ��laciolacustrine <br />� .i-i.n.n,�li��<.ei;,,��i�,i 21-1-09G4�1-OOS <br />7 <br />41 <br />