1315 PACIFIC AVE 2018-01-01 MF Import

observed in fow of the borings,and thc base course was absent in the remaining borings. Slight to strong pctroleum odors werc obscrved in samples obtained from borings D-6 and B-9 at about 7'/s ro 19 fxt bclow existing site grades. The soil uni4c obscrved in the borings are desc�ibed below. Fill. Fill was encountered in each of the borings and typically varies from 6 co 12 feet in thickness. We understand the fill placcd along the alley curtently bisecting the property may extend up to 20 feet below• the ground surface. The fill primarily consists of very loose to medium dense sand with vaziable silt and occaaional gravel. As noted previous!�, boring B-3 aas located in the northeast corna of the site and cncountemd a concrete obstruction al about 10 feet below thc ground surface. Outwaeh Deposits. Outwash deposits undcrlic the fill and gencrally consist of inedium dense to very densc, finc to medium sand with variablr amounts of silt. The outwash varies from 5 to 10 feet in ihickncss. Glaciil Till. Glacial till was encountercd at a depth of 15 to 17 fcct bclow existing grade in a�.i of the borings. The glacial till typically consists of vcry dense silry sand with variable amounts of g2ve1 and cobbles. Thc upper few feet of thc till in boring E3-6 consisted of mcdium dense soils. Groundwafer Condltlons Perchcd groundwater was obscrved in fivc of thc tcn horings during drilling at depths ranging from 12 to 22 fcet below thc existing ground surfacc. Although perchcd walcr was only observcd in fivc borings, moist to wct soils were observed in several other boriugs. Perchcd groundwater is common in glacial till soils wherc water Gom precipitalion percolates through the more pertncable fill and outwash soils and mmes laterally on the very dense, Iess pertneable glacial tiL'. We expect that perched groundwatcr levcls will fluctuale scasonally with prccipitation. CONCLUSIONS AND RECOMMENDATIONS SUMMARY OF KEY GEOTECHNICAL ISSUES I3ascd on thc results of our subsurfacc cxplotation program and gco�cchnical analyses,subsurfacc soil and groundwatcr conditions arc favorablc for construction of thc Potala Villagc Mixed-Usc building. A summary of Ihe primary gcotechnical considerations is pro��ided below. Thc summary is presented for introductory purposcs only and should be used in c�.ijunction with the complctc rccommendations prcscntcd in this rcport. • Subsurfacc soils encounlercd at the site consist of Ihrec geologic units: fill,ounvash deposits,and glaci�l till. The fill ranges from 6 l0 12 fcet in thickncss in our borings; however, wc anticipatc GII up to 20 fcet thick abo��c thc scwcr located in thc alley. • 1'crched groundwatcr was obscrvcd in fivc of shc�cn borings during drilling. • 7'he site is designatcd as scismic Site Class C per the 20061I3C. • Cantilcver soldicr pilc H�allc will pro��ide an economical rctention sqslcm for the pmposed cxcavations at thc sitc. + Dcsign of thc foundation and requirc� exca��ation aill necd to address conditions of thc existing (ni idation of'Ihc Snohomisl:Hcalth Uistrict building. flkA'�� 1;n1-un�-nn Pnge3 G[oEMG�MHIIE� hn,r 6.1IulA' �