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Y i <br /> Chase Chevrolet - 3 - January 30, 2012 <br /> Site History/Assessments <br /> In May 1986, soil contamination was identified during the removal of USTs. Currently, there are <br /> no monitoring wells on site, having been abandoned in 2004. <br /> Remediation Summary <br /> • Free Product: No free product was documented throughout the life of this case <br /> • Soil Excavation: An estimated 2615 cubic yards of impacted soil were removed and <br /> disposed offsite in 2004 <br /> • In-Situ Soil Remediation: No soil remediation has been conducted. <br /> • Groundwater Remediation: No groundwater remediation has been conducted <br /> General Site Conditions <br /> • Geology and Hydrogeology: The Site is underlain by interbedded and intermixed sand, <br /> silt and clay. The depth to groundwater is approximately 19 feet bgs. The closest <br /> surface water is the McLeod Lake, which is located approximately 250 feet southeast of <br /> r the Site. <br /> • Groundwater Trends: Benzene trends are shown below, source area (MW-21A) <br /> BENZENE Results for MW21A <br /> 200 <br /> �Y7TX80 <br /> 20 <br /> �1 <br /> BENZENE--�Trona <br /> Risk Evaluation <br /> .There are no water supply wells are within 2,000 feet of the Site. Drinking water at and near the <br /> Site is currently supplied by the City of Stockton: <br /> Recommendation <br /> February 2012, source area monitoring well MW-21A has had elevated concentrations of <br /> residual hydrocarbons in groundwater. The large excavation conducted in 2004 removed most <br /> ,of the residual soil contamination. Any remaining contamination is covered by thick asphalt <br /> pavement. The affected shallow groundwater is not used as a source of water supply nor is it <br /> likely to be used as a source of water supply in the foreseeable future. Water users in the <br /> vicinity of the site rely on a public water supply. Based on facts in the record and hydrologic and <br /> geologic conditions at the site, the limited residual petroleum hydrocarbons that remain in soil <br /> and groundwater pose a low risk to human health, safety and the environment. The Fund <br /> recommends that the San Joaquin County LOP review this site for closure. <br /> �^ <br /> Kirk Larson, P.G. Date Nobert Trommer, C.H.G. Date <br /> Engineering Geologist Senior Engineering Geologist <br /> Technical Review Unit . Chief, Technical Review Unit <br /> (916) 341-5663 (916) 341-5684 <br />