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I , TABLE 1 ' POTENTIAL OFFSITE SOURCE AREAS 541 West Grant Line Road Tracy, California ' Maximum Concentrations Depth to i ' Groundwater,Flow � r! Direction and No. Name and Address Potential Contaminant Sources Shallow Sod Type Gradient Soil(ppm) Groundwater(ppb) Remediation/Status Concerns { Groundwater elevation contour maps for Unknown number of steel USTs 1996-1997 show localized flow to north- installed 7 600 TPH- as- 19 000 Contaminated soil overexcavated beneath I1JSTs,sump, installed in 1964 then removed and g g western horst,and southern pump island t depths ranging no near former USTs replaced with fiberglass USTs m TPH-diesel-2,100 MTB TPH-diesel-4,700 from 6 5 to 10 5 feet bgs in August 1994 400 cuyds of Use and location of former 1960's steel 1984 6-7 5 feet b s Total O&G-5,200 MTBE-3,100 ]fromUSTs unknown g excavated contaminated soil was removed site whichFormer Chevron Station In 1994 removed three former NW with some flow MTBE-0 0014 � benzene-1,500Groundwater grab samples at CPT-1 1 0-25 ft silty clay benzene-24 eth lbenzene-1 100 included up to 200 cuyds of oil&greaseip acted soil 575 W Grant Line Road 10,000 gal fiberglass USTs to N&NE 0 006 y through CPT-15 in 2001 were taken well @ ApproxmiakeIy 300 cuyds of lesser contaated soil ethylbenzene-180 toluene-59 below the u g containing gasoline, one 1,000 gal to 0 02 peer groundwater surface placed at northeast corner of station and allowed to aerate fiberglass waste oil UST,one oil- toluene-5 xylenes-1,900 r where floating or dissolved product xylenes-560 lead-18 for 6 months then used as backfill onsite I�'lie site is part of would be found ' water separator,and two hydraulic lead-17 1 2-DCA-4 ongoing Joint Groundwater Monitoring Piogram with hoists in service bay former Mobil and Scotties Stations Lateral and vertical extent of contamination has not been characterized ' I Facility is old and oil-water separator 1 may not have been properly mamtamed • 2 Former Self-Serve Car Wash One oil-water separator No data available No data available No data available Na data available Oil-water separator removed during Grant Line Road Observed to be leaking during removal 575 W Grant Line Road widening in 1988 Waste oil and other unknown contaminants may have unpacted soil } and groundwater I Chevron Fuel Pipeline 6-inch diameter fuel pipeline carried The pipeline is old and carnes smular ' 3 West Grant Line Road gasoline, diesel,and jet fuel since No data available No data available No data available No data available No data available 1965 fuels occurring in the groundwater Pipeline still active I Contaminated soil and groundwater detect'd during TPH-gas-2,500 TPH-gas- 1,500 construction of new car wash and lubncati n facility built ' Possible oil-water separator from TPH-diesel-NT TPH-diesel-ND in 1996 Subsurface investigation found g,solme Tracy Express Wash&Lube former car wash built in 1980 Total O&G-NT Total O&G-NT contamination extending across the entire 51te and east onto 7-9 ft b s MTBE-5 4 MTBE-21 Site(541 W Grant Line Road)at boring P�_7 Entire site was contaminated by Chevron 4 (Former Car Wash) 0-8 ft silty clay g LUSTS and offsite(eastern)extent of ' 2480 W Grant Line Road Former Chevron Station detemmmed N @0 002 benzene-10 I benzene-99 Total of approximately 600 cuyds of conta ated soil to be source of contamination ethylbenzene-57 ethylbenzene-68 removed from basement excavation Rem diated by plume never investigated or remediated toluene-6 3 toluene-63 spreading,rototilling,and aerating then usi g as backfill xylenes-300 xylenes-430 onsite Contaminated groundwater dewatered from f excavation was carbon treated and discharged to sewer i 1 I 1 • i1 Polential Source areas xis } TREADWELL&ROLLO,INC 1 of 3 5121103