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i <br /> 23 April 1999 <br /> AGE-NC Project No. 95-0100 <br /> Page 2 of 7 <br /> On 22 February 1995, two additional borings (borings B3 and B4)were drilled north and south of <br /> the former fuel dispenser island. Low concentrations of volatile aromatics were detected in one <br /> sample from boring B4. Results of the site assessment indicated that impacted.soil is present only <br /> in the area of the former dispenser island. <br /> 2.4. GROUNDWATER DEPTH AND FLOW DIRECTION <br /> The Well.Completion Report for a domestic water well drilled in January of 1992 states that water <br /> was encountered on the site at a.depth of 54 feet. According to the San Joaquin County Flood <br /> Control Map (Fall 1990), the prevailing ground water flow direction is to-the north. Soil borings <br /> established in January 1999 indicated the depth to ground water at approximately 45 feet bsg. <br /> 3.0. REMEDIATION OF HYDROCARBON-IMPACTED SOIL <br /> Data collected from the site during the investigation of the former UST site indicated that <br /> hydrocarbon-impacted soil is present in the vadose zone from approximate depths of 5 to 3 5 feet bsg. <br /> Therefore, only hydrocarbon-impacted soil remediation alternatives were explored during any <br /> .feasibility studies. The results of the soil remediation feasibility studies (soil vapor extraction pilot <br /> test; bio numeration; and excavation limitations) are detailed in the Corrective Action Plan prepared <br /> by AGE, dated 29 November 4995. <br /> AGE installed and operated a thermal oxidation SVE unit at the site. Overall, the SVE has operated <br /> at 80 to 100 standard cubic feet per minute (scfm). Soil gas/vapor samples indicted a decrease of <br /> overall concentrations of TPH-g'and BTEX over a six month operation.. As a result of the declining <br /> concentrations in the soil/vapor extraction, soil samples were collected in January 1999 to confirm <br /> the removal of the hydrocarbons. Additionally one `grab'ground water sample was collected at the <br /> request of the PHS-EHD. The `.grab' ground water samples contained residual BTEX and MTBE. <br /> 3.0. SCOPE OF WORK <br /> Based on the results of the ground water sample, the release of petroleum hydrocarbon compounds <br /> at the site has impacted ground water. AGE proposes to established ground water monitoring wells <br /> to evaluate the lateral extent of MTBE impact to groundwater. The investigation'of the extent of the <br /> MTBE contamination at the site will consist of the following tasks: <br />