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N��% California Re*gtonal Water Quality Control Board <br /> LCentral Valley Region <br /> Peter M.Rooney Sacramento Main Office 1',d J.Schnabel <br /> Secretaryfor Internet Address: http://www.swreb.ca.gov/-rwgcb5/home.html Chair <br /> Environmental 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Protection Phone(916)255-3000•FAX(916)255-3015 <br /> TO: Gordon L. Boggs FROM: Mark R. List <br /> UST Program Manager Engineering Geologist <br /> DATE: 05 October 1998 SIGNATURE: <br /> SUBJECT: FILE REVIEW FOR CLOSURE CONCURRENCE, RENTAL EQUIPMENT <br /> COMPANY, INC., 182111825 EAST CHARTER WAY, STOCKTON, SAN JOAQUIN <br /> COUNTY <br /> At the request of the San Joaquin County Environmental Health Division (SJCEHD), a file review was <br /> completed to determine if Regional Board staff agree with the SJCEHD determination of no further <br /> action required (NFAR), at this site. This information was obtained during my review of the Regional <br /> Board casefile, and during discussions with Mr. Michael J. Infurna of SJCEHD. <br /> Background: <br /> On 19 October 1990, one 5,000-gallon diesel fuel tank was removed from the site. Soil samples <br /> collected from the UST excavation revealed elevated concentrations of TPHd, ethylbenzene and xylenes. <br /> The contamination was detected in the sample collected from the south end of the UST at 13 feet below <br /> ground surface (bgs). The contaminant concentrations in soil are as follows: <br /> Contaminant: Concentration: <br /> TPHdiesel 8080 ppm (mg/Kg) <br /> ethylbenzene 9.6 ppm <br /> xylenes 84 ppm <br /> In August 1998, one Geoprobe boring was advanced through the center of the former UST excavation to <br /> 65 feet bgs. Soil samples were collected at five foot intervals between 5 and 50 feet bgs, and one grab <br /> groundwater sample was collected from the boring. The analytical results of the soil samples did not <br /> detect TPHd, BTEX or MTBE above the laboratory reporting limits. The groundwater sample analysis <br /> detected 69 gg/L(ppb) of TPHd. No BTEX or oxygenates were detected in the groundwater sample. <br /> Summary: <br /> TPHd, ethylbenzene and xylenes are present in soil at 13 feet bgs., near the south end of the former UST <br /> excavation. TPHd remains in groundwater below the site at 69 gg/L. Benzene and the oxygenates are not <br /> present in soil or groundwater at the site. The contamination remaining does not pose a significant threat <br /> to water quality. Concurrence with the SJCEHD determination of NFAR appears appropriate. <br /> California Environmental Protection Agency <br /> ea Recycled Paper <br />