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7.0 SUMMARY AND DISCUSSION <br /> 7.1 Summary <br /> * The site UST, product dispenser, and product piping have been removed. Motor vehicle <br /> fuels are no longer stored or dispensed at the site. <br /> * An SVE system, extracting from wells VEW-1 and VEW-2, operated between July 1994 <br /> and the first quarter 1997. The SVE system appears to have been effective in reducing <br /> residual petroleum hydrocarbon concentrations in the unsaturated soil beneath the former <br /> UST. <br /> * Groundwater levels in the monitoring wells have risen from approximately 68 feet bgs to <br /> approximately 44 feet bgs since monitoring was initiated in 1989. It is our understanding, <br /> based on conversations with San Joaquin County PHS/EHD, that first encountered <br /> groundwater in the general area of the site was recorded as low as 110 feet bgs in 1979. <br /> w * Silt and clay predominate from 0 to 100 feet bgs at the site. Sand intervals logged <br /> between approximately 15 and 35 feet bgs and 45 to 65 feet bgs in the vicinity of the <br /> former UST do not appear to be laterally continuous. A sand layer appears to be laterally <br /> continuous between approximately 85 and 90 feet bgs across the northern portion of the <br /> site. Sand and gravelly sand were encountered in each CPT boring at depths between 95 <br /> and 105 feet bgs. This sand is laterally continuous, and is approximately 10 to greater <br /> than 40 feet thick. This sand stratum is impacted with petroleum hydrocarbons. <br /> * The vertical extent of groundwater impact appears to be adequately delineated in the <br /> source area, but remains undefined downgradient in the vicinity of boring CPT-8. <br /> * MTBE is not a COC at the Apache Plastics site. Dissolved concentrations of MTBE', <br /> above the current MCL have been detected upgradient at the Sunland site. <br /> • The lateral extent of petroleum hydrocarbon impact to soil and groundwater onsite -z <br /> appears to be adequately assessed. <br /> * Additional data is required to adequately assess the extent to which the hydrocarbon - <br /> release at the former Sunland facility has impacted soil and groundwater beneath the �� <br /> Apache site. <br /> * Onsite sensitive receptors have not been identified. <br /> p;\,pache Plastics\ReportMpache sCMAoc Page 14 Stratus <br />