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Ground water at Site #1 is under confined conditions, and the potentiometric surface occurs at a depth of approximately 6 feet bgs The measured flow gradient varies due to tidal water level fluctuations in the nearby Deep Water Channel However, the overall flow direction over time has been generally consistent toward the south- southwest (away from the Channel)1 Hydrocarbons in Soil and Ground Water, The lateral and vertical extent of total petroleum hydrocarbons (TPH) and benzene, toluene, ethylbenzene, and xylenes (BTEX) in soil is limited to a localized area in the vicinity of the former tank, in a zone between approximately 6 and 11 feet bgs (Figure 3-2) This zone of affected sods is above the clay- sand contact but below the ground water potentiometric surface The extent of TPH and BTEX in ground water is also limited The maximum concentrations of TPH as gasoline and benzene detected in ground water are illustrated in Figure 3-3 The highest concentrations of these compounds detected were in ground water samples collected at soil gas probe location M and monitoring wells MW-4 and MW-5 The highest concentrations of TPH as gasoline and benzene detected in ground water in MW-4 and MW-5 were from samples collected in April 1991 However, the results of quarterly ground water samples collected from monitoring wells MW-4 and MW-5 since April 1991 have shown a steady decline in the concentrations of TPH as gasoline and benzene in ground water Table 3-1 presents a summary of the quarterly ground water sample results for Site #1 The concentrations ' of TPH as gasoline and benzene detected in MW-5 have decreased significantly over time, and the most recent samples collected from MW-4 in December 1992 and March 1993 were non-detect Based on ' the ground water data, the estimated non-detect line (<1 mg/l (parts per million)) for TPH as gasoline in ground water is shown on Figure 3-3 Lead, Analyses were also performed for total and organic lead in soil and water samples Samples collected during the removal of the tank ' by EHJ Construction showed total lead in soil results to be very low The unfiltered ground water sample showed a lead concentration of 6 mg/1 Subsequent samples were analyzed for organic lead These later sample results (for both soil and water) were below detection limits The analytical findings suggest that the tank contained unleaded ' gasoline, and the total lead values reported are representative of background levels in area soils 1 Based upon data collected during quarterly ground water monitoring events conducted between April 1991 and April 1993 3-2