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1. INTRODUCTION <br /> At the request of Exxon Company, U S.A , EA has proposed a work plan to remediate petroleum <br /> hydrocarbons in the soil and groundwater at former Exxon Retail Site (RS) 7-3942 This <br /> document has been prepared in support of an application for a waste discharge permit to carry <br /> out the work involved The work plan (EA October 1990) has been approved by the San Joaquin <br /> County Public Health Department and the Regional Water Quality Control Board, Central Valley <br /> Region, and will be implemented in two phases. The two phases include the following items <br /> (some of which are now in progress): <br />' Phase One: Immediate Investigation and Interim Remediation <br /> 1 The groundwater monitoring wells on and off the site will be used to define <br /> the full horizontal extent of the dissolved petroleum hydrocarbon plume <br /> 2. A groundwater extraction and treatment system (GETS) will be implement- <br /> ed groundwater will be extracted from five recovery wells in order to begin <br /> immediate containment of the plume, the extracted groundwater will be <br />' treated on the site with a system that will include an air stripper, catalytic <br /> oxidation of the stripped petroleum hydrocarbon vapors, and an activated <br /> carbon polish of the water. <br /> 3 A vapor extraction and treatment system (VETS) will be constructed vapor <br />' will be extracted from nine wells, and the extracted vapors will be treated by <br /> catalytic oxidation (the VETS will be plumbed to the GETS so that petrole- <br /> um hydrocarbon vapors from the two systems can be oxidized together). <br /> 4. The operational areas of influence of the VETS and the GETS will be active- <br /> ly monitored vapor monitoring wells will be installed to monitor the VETS, <br /> and concentrations of petroleum hydrocarbons in the water and drawdown of <br /> the water table will be monitored in the onsite and offsite wells 11 <br />' S. The quality of the groundwater has been defined, and permits are being <br /> applied for to dispose of treated groundwater to the storm sewer and injec- <br /> tion wells (A portion of the water will be reinjected to the aquifer in three <br /> onsite wells to create a hydraulic mound or bamer.) <br /> tPhase Two: Long-Term Program <br /> 1 On the basis of the operational areas of influence of the vapor and the <br /> groundwater extraction wells and the definition of the petroleum hydrocar- <br /> bon plumes in the soil and groundwater, additional vapor and groundwater <br />' C6Vw*W/394ZrJu19lla 1 <br />