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s C\YATC ..1 A S S O C I A T E S I N C . • Kleinfelder, Inc. installed five soil borings (KB 1 through KB5) at the site in January 1988. These borings were installed in the vicinity of the former tank complex, adjacent to the product lines, and adjacent to the former waste oil tank (Pacific Environmental Group, August 1993). • Between June 1988 and February 1992, RESNA Industries, Inc. (RESNA) installed a total of seven monitoring wells (MW-1 through MW-7) and three-vapor extraction wells (VW-1 through VW-3). Monitoring wells MW1, MW-2, MW-3, and MW-6 are located on site and wells MW-4, MW-5, and MW-7 are located northeast, downgradient of the site. The soil vapor extraction wells are located in the vicinity of the former product islands (Pacific Environmental Group, August 1993). • In March 1992, RESNA performed a soil vapor extraction test. The results indicated that with a wellhead flow rate of 43 cubic feet per minute, an effective radius of influence of approximately 25 feet could be achieved (Pacific Environmental Group, August 1993). • On July 19, 1994, monitoring wells MW-8 and MW-9 were installed to depths of 55 feet. The wells were screened from 30 to 55 feet bgs. Static water in both wells was measured at 43 feet bgs (PHS/EHD Investigative Officers Report). These wells are located on the Bank of America property located crossgradient of the former UNOCAL site. + Hydrocabon impacted soil appeared to be limited laterally to the area around the former product islands. Soils in the vicinity of the northern product island were found have TPHg and benzene concentrations up to 17,300 ppm and 28 ppm, respectively. In the area of the southern product island soils contained TPHg and benzene concentrations up to 239 ppm and 11.2 ppm, respectively. The estimated vertical extent of soil contamination is greater than 52 feet bgs and appears to be undefined (Pacific Environmental Group, August 1993). • From January to November 1996, a soil vapor extraction system (SVE) was operated at the site utilizing wells VW-1 through VW-3. The system was reported to have been successful in removing 2,745 pounds of total purgable hydrocarbons (TPPH) and 12 pounds of benzene (MPDS, June 13, 1997). • The SVE was effective from 10 to 37 feet bgs. Soil contamination below the groundwater, which extends from 37 feet bgs was not available for treatment by SVE technology. The remedial effectiveness of SVE can only be determined by confirmation borings. Confirmation borings have not been drilled (PHS/EHD Investigative Officers Report). W A17292.45Xsummaryrptdoc 5