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i r l ,• SiteHistory Jackpot Food Mart,1434 W Yosemite Ave,Manteca,CA Time Oil Property No 04-167 Based on the excellent results achieved during the vapor extraction pilot test and the low cost of Installing and operating such a system, other remedial methods involving excavation were not considered feasible for soil cleanup Vapor extraction is the least expensive option, it can achieve rapid results, and It will not disrupt the business currently in operation Selection of Remedial Technology Vapor extraction is the proposed remedial technology to achieve cleanup of hydrocarbon-impacted soils beneath the subject site We estimate that 3 existing wells (W-1, W-2, and W-4) will be used for the proposed vapor extraction system In addition, horizontal wells may be installed within the vapor extraction piping trenches to enhance remediation if hydrocarbon-impacted soils are encountered during system installation Although a radius of influence has not yet been calculated for the existing wells, it is estimated that they will be sufficient for cleanup of the impacted soils Should additional wells be required, they will be installed at a later date The proposed system will Initially utilize an internal combustion engine for vapor abatement, however, once vapor concentrations have reduced sufficiently, carbon will be used Approval of FRP The Final Remedial Plan underwent public review and comment in October 1994, and was subsequently approved by the PHS/EHD Quarterly Groundwater Monitoring Report- Fourth Quarter 1994 On October 25, 1994, quarterly groundwater monitoring was conducted Prior to purging, the depth to groundwater in each well was measured by a representative of SECOR to assist in evaluating changes in elevation, flow direction, and gradient Groundwater with an easterly flow was encountered at 15 87 to 17 17 feet below ground surface Since the previous sampling event, depth to groundwater increased across the site by approximately 0 25 feet, and flow changed from northeast to east These variations are consistent with those observed In previous sampling events None of the samples were found to contain detectable concentrations of hydrocarbons A copy of SECOR's"Quarterly Monitoring Report, October - December 1994"was forwarded to the PHS/EHD and CRWQCB on January 25, 1994 Quarterly Groundwater Monitoring Report- First Quarter 1995 On February 9, 1995, samples were collected from each of the monitoring wells at the subject site Prior to purging, the depth to groundwater in each well was measured by a representative of SECOR to assist In evaluating changes in elevation, flow direction, and gradient Groundwater was encountered at 13 88 feet to 15 10 feet below ground surface Since the previous sampling event, groundwater elevation had Increased across the site by approximately two feet and flow direction had changed from east to northeast The change in flow direction is consistent with that observed in previous sampling events and is most likely a result of seasonal variation The rise in groundwater elevation is probably due to heavy rainfall during the winter months . Neither gasoline nor its constituents were detected in any of the samples collected 4