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September 16, 1991 <br /> ARCO Service Station No. 2076, Lodi, California <br /> Soil Sampling <br /> The sand or gravel backfill material that was originally placed around the tanks to fill the <br /> tank cavity will be removed from the tank cavity and stockpiled onsite. After the tanks are <br /> removed, additional material will be excavated until native soil is exposed on the bottom <br /> and sides of the tank cavity. Two native soil samples will be collected within 2 feet of the <br /> bottom of each former tank (approximately 12 feet below grade) for laboratory analyses to <br /> evaluate whether contents of the tanks have laked into the surrounding native soil. <br /> Additional soil samples from the sidewalk of the excavation will be collected if product <br /> discoloration or odor are detected by our staff geologist. Soil samples will also be collected <br /> , within 2 feet of bottom of the former product lines at 20 foot intervals. Soil samples will <br /> be submitted to a State-licensed laboratory and analyzed for appropriate compounds <br /> according to the SJCPHS-EHD guidelines. <br /> ARCO plans to install the new tanks in a sepa late tank cavity located northeast of the <br /> station building, as depicted on Plate 2. The new tank cavity will be excavated to <br /> approximately 12 feet below grade. Appropriate soil samples will be collected according to <br /> the SJCPHS-EHD guidelines from the bottom of the cavity to evaluate if hvdrocarbons are <br /> present in the soil. <br /> . 1 <br /> Tank and Product-Line Installation <br /> Before the new tanks are installed, two vertical 12-inch-diameter polyvinyl casings will be <br /> installed between each new tank extending from approximately 2 feet into the native soil <br /> to the ground surface. The casing will allow soil borings to be drilled between the new <br /> tanks to continue further investigation of soil conditions beneath the new tanks, if warranted. <br /> Results of laboratory analyses of soil samples collected from the former tank cavity, <br /> proposed tank cavity, and product-line trenchesill be forwarded to the SJCPHS-EHD. If <br /> laboratory analyses indicate hydrocarbons remainin the soil, at concentrations warranting <br /> remediation, we will evaluate and recommend remedial alternatives. At this time <br /> remediation by soil vapor extraction appears feasible. <br /> New tanks and product lines will not be installed until authorization is obtained from the <br /> SJCPHS-EHD. We may also request authorization to install subgrade components that will <br /> later be used in the VES. The new tanks and product lines will be surrounded by clean pea <br /> gravel backfill which will be compacted to construction standards. <br /> 30008-3W 111 <br />