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DISCUSSION SOIL AND GROUNDWATER INVESTIGATION Field and laboratory analytical results of soil and groundwater samples collected during this investigation from borings/wells in the vicinity of the former underground gasoline storage tank appear to confirm the soil vapor survey results. Total Petroleum Hydrocarbons as gasoline (TPH) Laboratory analyses of soil samples collected during this investigation detected TPH in concentrations ranging to 840 ppm. The highest TPH levels in soil were found at OW-2, approximately 10 feet to the north-northeast of the former tank location. TPH levels in OW-2 were highest in soils within 2 feet of the encountered water table (sample collected about 8 feet below ground surface) , and dropped off rapidly above and below this depth (to 190 ppm at 6.5 feet below the ground surface and 25 ppm at 10 feet below the ground surface) . Much lower TPH concentrations (3 ppm) were detected in soil samples collected approximately 80 feet to the northeast (downgradient) of the former tank location (OW-5) , at a depth approximately 9 feet below ground surface. No soil samples collected from OW-1, OW-3, OW-4 or OW-6 showed any detectable presence of gasoline petroleum hydrocarbons (detection limit was 1 ppm) . Figure 8 shows the estimated horizontal TPH isoconcentration lines for soils in the vicinity of the former underground tank, based on results from this investigation. This figure shows that, with the possible exception of a very small volume of soil immediately adjacent to the former tank location, TPH concentrations below 1000 ppm are expected for all onsite soil. Laboratory results of groundwater samples collected during this investigation from observation wells at the site indicated that elevated TPH levels ranged to 14 ppm. The highest TPH levels in groundwater were found 3286a/BAV 24