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EI CA. Mr. Dave Deaner February 16, 1998 Page 3 County, 1992). The nearest body of water is the Mokelumne River located approximately 2,200 feet east of the subject property-(U.S.G.S. Thornton Quadrangle, 1978). A water well located along the eastem boundary of the subject property is used for irrigation purposes only. The residence receives it's domestic water from the San Joaquin Municipal Water District. Drinking Water Well Search ENSR contacted the California Department of Water Resources (DWR) to conduct a water well search within a 2,000-foot radius of the subject property. Well logs of the water well located on the subject property were not identified by the search. According to the property owner this well is used for irrigation purposes only. Two water wells were identified within the search distance and are described below: • Well No. 119249 is a irrigation well located approximately 1,800 feet southwest of the subject property. This well was completed in 1978 to a depth of 128 feet bgs. According to the welll log, a 14-inch diameter steel casing, with no perforations, was installed from 0 to 85 feet. No other casing information is provided on the well log. The subsurface lithology consists of alternating layers of clay and sand to 120 feet bgs and sand and gravel from 120 to 128 feet bgs. • ` Well No. 194932 is a domestic water well located approximately 2,000 feet west of'the subject property. This well was completed in April 5, 1987 to a depth of 115 feet bgs. The casing is 8-inch diameter and is screened from 115 feet to 90 feet bgs. The subsurface lithology consists of alternating layers of clay and sand to 115 feet bgs. Lopez Water Well Sampling On January 28, 1998, water samples were collected from the domestic water well (used for irrigation only), located at the subject property. Water samples were collected from a faucet located at the well head, after allowing the water to nun for approximately 10 minutes to ensure samples represent actual water supply conditions. The collected water samples were analyzed for the presence of TPH-g, BTEX and MTBE by EPA methods 8020 modified and DHS Luft. The laboratory results did not detect the presence of TPH-g, BTEX or MTBE at or above the reporting limit. A copy of the Laboratory report and chain of custody documentation is presented in Attachment 6. Request for Site Closure ENSR, on behalf of Ms. Pamela Lopez, is requesting case closure for the subject property. Justification for site closure is based on source removal, site characterization, and no significant risk to human health or the environment. Residual soil contamination at the site does not appear to significantly impact the shallow ground water, based on the results of ground water monitoring activities conducted from between February 1996 through July 1997. The reduction in mass, mobility, and concentration of residual petroleum hydrocarbons in soil will continue at this site as a result of natural attenuation. 8716002.CLS