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17 March 1997 AGE-NC Project No. 95-0100 Page 2 of 7 the former fuel dispenser island by GAS. Low concentrations of volatile aromatics were detected in one sample from boring B4. Results of the site assessment indicated that impacted soil is present only in the area of the former dispenser island. 2.4. GROUND WATER DEPTH AND FLOW DIRECTION The Well Completion Report for a domestic water well drilled in January of 1992 states that water was encountered on the site at a depth of 54 feet. According to the San Joaquin County Flood Control Map (Fall 1990), the prevailing ground water flow direction is to the north.'No site specific ground water investigation has been performed. 3.0. REMEDIATION OF HYDROCARBON-IMPACTED SOIL Data collected from the site during the investigation of the former UST site indicated that hydrocarbon-impacted soil is present in the vadose zone from approximate depths of 5 to 35 feet bsg. No ground water investigation was required or performed at the Franklyn Cole site. Therefore, only hydrocarbon-impacted soil remediation alternatives were explored during any feasibility studies and only considered in this RWAP. The results of the soil remediation feasibility studies (soil vapor extraction pilot test; bio numeration; and excavation limitations) are detailed in the Corrective Action Plan prepared by AGE, dated 29 November 1995. AGE recommended the installation of a thermal oxidation SVE unit at the site. Based on the high carbon dioxide concentrations encountered during the pilot test, low levels of free oxygen in the soil, and the consumption of supplemental fuel, an IC engine is not a cost-efficient:option. Overall, the SVE test performed at the site produced acceptable results. Based upon the lithology at the site(gravels), a unit capable of 100 to 200 sefm should be suitable for extraction. A theoretical radius of influence greater than 25 feet was calculated from the data collected. It does not appear that additional extraction wells within the impacted soil plume will be required' " at the site. The SVE well network should consist of extraction wells VE-1 and VE-2. Each vapor well is screened with separate casing intervals; which shall be individually routed into the SVE network to allow for extraction from differing lithologies at the site. , A 6 to 12-month'soil remediation period can be expected. The SVE unit has a typical destruction rate of greater than 95%of hydrocarbon vapors,throughout the entire cleanup duration. AGE anticipates that an 85 to 90 % removal all hydrocarbon vapors will be achieved from the soil will at the site, utilizing existing SVE wells.