ARCHIVED REPORTS_XR0009619 - Laserfiche WebLink

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• s• Thrifty Oil Co. Station #172 Page3 Influent and effluent vapor samples were collected on Apnl 10, May 27, and June 12, 2003 In addition, vapor samples were collected on May 27, 2003 from selected well heads The well head, influent, and effluent vapor samples were analyzed for TPH-g by EPA method 8015, and BTEX/MTBE by EPA method 8021B Copies of the influent, effluent, and wellhead vapor sample laboratory analytical results are presented in Appendix D A historical summary of hydrocarbons removed by vapor extraction is presented in Table 3, vapor sample analytical results for the individual wells sampling are presented in Table 5 The Field Status Reports are included in Appendix C Groundwater Treatment System The groundwater treatment system was started in conjunction with the vapor treatment system on April 26, 2001, and the flow meter started at zero Presently, the remediation system is connected to groundwater wells MW-10 and MW-11 Two down-well pneumatic pumps (one in each well) draw water into a 150-gallon polyvinyl tank, which then transfers the water through two (2) one thousand-pound canisters with activated carbon During this reporting period, the groundwater extraction system was restarted on April 9, 2003 after installation of a continuous LEL morutonng device that is interlocked with the control circuit of the groundwater pumping system, meeting the City of Stockton, Department of Municipal Utilities (CSDMU) new permit requirements The system was shut down on May 20, 2003 for quarterly water sampling and restarted on May 21, 2003 The groundwater system was shut down again for carbon change out on May 22, 2003, and was restarted on June 20, 2003 A total of 4,342 gallons of water have been treated and discharged during the reporting period, and 97,456 gallons had been treated and discharged since the commencement of groundwater treatment Historical groundwater system operations are reported in Table 4 and 4b, and the quarterly analytical results are presented in Appendix E Summary and Recommendations The soil vapor and groundwater extraction systems were started on April 26, 2001 A total of 71,133 pounds of hydrocarbons have been destroyed by the vapor extraction system, and approximately 36 pounds of hydrocarbons have been removed through groundwater treatment The groundwater extraction system was non-operational from April 1 through April 9, and May 20 through June 20, 2003, because of system maintenance and new permit requirements from the CSDMU, the quarterly water-sampling event, and carbon change out Due to the declining concentrations in pumping well MW-10, Thrifty will optimize the groundwater extraction operations by limiting extraction to well MW-11 only