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Mr Randall K Stephenson October 24, 1994 Page 3 Soil samples were selected for chemical analysts on the basis of field observations and the location of the soil sample in relation to the most likely sources of petroleum hydrocarbon constituents Twenty-two soil samples were submitted for analysis of concentrations of BTEX and TPHg Soil sample analytical results for soil samples collected from the soil borings for monitoring wells MW-1, MW-2, and MW-3 are summarized in Table 2 Copies of cemfled analytical reports for each soil sample submitted to the laboratory during this phase of work are container) in Enclosure F Ground Water Analytical Results After newly installed monitoring wells MW-1, MW-2, and MW-3 were developed and purged on July 8, 1994, ground water samples were collected from each monitoring well 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 Analytical results of sampling conducted on July 8, 1994, are summarized in Table 3 Copies of certified analytical reports for ground water samples are contained in Enclosure G Dissolved benzene concentrations detected in water samples collected from monitoring wells on July 8, 1994, ranged from 2 9 micrograms per liter (µg/1) in the sample collected from monitoring well MW-1 to 540 tig/l in the sample collected from MW-3 The sample collected from monitoring well MW-2 was reported to contain a concentration of 6 8 µg/l of benzene Figure 4 illustrates the inferred distribution of dissolved benzene in ground water samples collected on July 8, 1994 Summary of Results Soil samples analyzed from the bonngs for monitoring wells MW-1 and MW-2 did not contain detectable concentrations of petroleum hydrocarbon constituents A soil sample collected from 65 feet below grade (possibly within the zone of water table fluctuation) from the boring for monitoring well MW-3 was reported to contain the highest concentration of TPHg (230 milligrams per kilogram [mg/kg]) Petroleum hydrocarbon constituents were detected in the ground water samples collected from the newly constructed monitoring wells (MW-1, MW-2, and MW-3) on July 8, 1994 Benzene was detected in ground water samples collected from monitoring wells MWA, MW-2, and MW-3 at 2 9, 6 8, and 540 lAgll, respectively The inferred direction of ground water flow on July 8, 1994, was toward the east-southeast with an inferred hydraulic gradient of less than 0 01 ft/ft ACTON - M3CKELSON • hp[l25 M3 van DAM, INC Consulting Scientists, Engineers,and Geologists