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r Mr Kenneth R Earnest February 11, 1993 Page 3 Ground Water Level Measurements Depth to ground water was measured in each existing monitoring well (MW-1 through MW-5) on December 14, 1992 (Table 2) Ground water was present at depths ranging from 75 28 to 77 41 feet below the top of the well casing Water level measurements indicate an inferred direction of ground water flow toward the west as illustrated on Figure 3 On December 14, 1992, the ground water gradient was approximately 0 035 foot per foot Ground Water Analytical Results On December 14, 1992, ground water samples were collected from monitoring wells MW-4 and MW-5 Samples were collected as described in Enclosure A Each ground water sample was analyzed for BTEX and TPHg by EPA and Cal-EPA approved methods The ground water sample collected from monitoring well MW-5 was also analyzed for the presence of chlorinated hydrocarbons by EPA and Cal-EPA approved methods Analytical results of sampling conducted on December 14, 1992, are summarized in Table 3 Previous ground water sample analytical results are included in Table 3 for comparison Copies of certified analytical reports are contained in Enclosure E The most recent ground water quality data available for each existing ground water monitoring well were compiled to infer the distribution of dissolved benzene in ground water beneath the site (Figure 4) Data from monitoring wells MW-1, MW-2, and MW-3 are from October 30, 1992, data from monitoring wells MW-4 and MW-5 were collected on December 14, 1992 Each well at the site will be sampled on the same day during the next quarterly sampling event to verify the inferred distribution of dissolved benzene in ground water Fecal coliform was not detected in the ground water sample collected from monitoring well MW-4 A copy of the laboratory report is included in Enclosure E Summary of Analytical Results None of the soil samples submitted for analysis from borings for monitoring wells MW-4 and MW-5 and vapor extraction well VW-3 contained more than 1 milligram per kilogram (mg/kg) of any petroleum constituents Seven of the 43 soil samples collected in December 1992 contained concentrations of TPHg greater than 100 mg/kg Soil samples collected from the boring for vapor extraction well VW-1 between 15 and 45 feet below grade contained TPHg at concentrations ranging from 130 to 5,400 ppm Soil samples collected from the boring for vapor extraction well VW-2 at depths of 30 and 40 feet below grade contained 200 and 410 ppm TPHg, respectively A single sample collected from the soil boring for vapor extraction well VW-4 contained greater than 100 ppm TPHg, this sample was collected at 40 feet below grade and contained 250 ppm TPHg ACTON + MICKELSON van DAM, INC Consulting Scientists, Engineers,and Geologists t