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subsurface Investx atxon and 'SCO FacxlxWell Installation Re Ort h'No 6100 Tracy, California Page S Disc Through Continuous soil sainplin soil borings, Delta identified g' detailed soil to transmissive to subsurface intervals m and ost geophysical logging groundwater Several thin sand strata were encountered gg g °f the feet bgs Two lateral] Y to be hydraulically stra#um was encounteredoatiauous sand strata were encountered tered at depths to 45 sand and sand stratum ata approximately 48 to 63 feet bgs, , a 3 to 4-foot-thick sand the site appears a r MrOximately 68 to 80 feet b g and a I S-foot-thick silty p towards the east and southeastgThe bedded Sediment beneath aFPears to be similar to exposed outcrops observed in th approximately 5 degrees, which Eight wells (four well clusters e vicinity expected to be hydraulicall were constructed with screens across the depth rechargeable groundwater � transmissive The only monrtorm p Intervals originating from the water supply I and MW-2 Water present in Wells that contain water in the water supply poly we11, which is approximately SO feet awaell y may be water supply FP1Y well has been measured at Y Depth t° However, PIY well was gravel packed fro PProximatel 40 feet b Well MW-3, located approximatelym the bottom of the well u gs The groundwater acid is screened from'2 to 92 feet best from well ,VI p to 35 feet bgs likely to be hydraulically transmissive W-2' does not contain { ed from 73 to 103 feet b g s across approximately 15 feet of sol, screen Groundwater has not been present In well since monitoring was Initiated in August approximately 7 feet northeast of well VW-17 MW-1 may be fromrection gust 2of M 000 The source of MW-1, Gertain Further off--sit as essment WouldW- the water present m well 2 and the supply well observed in well MW_ be necethe , however, this is not T extends further to the southeast to determine If the Data collected dune groundwater vertical] g this investigation Suggest, y delineated The lateral extent remains Undefined hydrocarbon M the highest concentrations of TPH pact appears to be to 65 feet b G and benzene were detected at depths st of the site bgs TPHG or BTEX compounds were not detecteranging Xn soil, collected below IOS feet bgs g g from 35 benzene g Groundwater in well Mor_ in any soli sample MTBE was detected only In the soils 2 contained onlyF Fuel oxygenates were not detected In other soil samples, mPle from 63 feet bgs in bannHG and collected from well MW-2 g B-33 airlples, or In the groundwater sample Conclusions and Recommendations The vertical extent of hydrocarb on and Offsite on Impact appears to be adequately assessed bath • The inaJonty afhYdrocarbons encountered Burin t between approximately 35 and 65 feet bgs g his Investigation were detected P�ARC0161001REPORTS16100,we]]wsta]]report doe