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Ni l <br /> A S S O C I A 7 E S I N C <br /> 4.0 RESULTS <br /> 4_1 Soil <br /> 1 Petroleum hydrocarbons were detected in boring SB9A Elevated concentrations of petroleum <br /> hydrocarbons were detected in boring SB9A between 25 feet and 27 feet bgs and attenuate <br /> rapidly with depth Soil samples collected from boring SB9A at 30 feet bgs contained very low <br /> 1 concentrations of TPHg and BTEX and the sample collected at 35 feet bgs contained only trace <br /> concentrations of benzene Oxygenate fuel additives were not detected in the soil samples <br /> 1 collected from boring S139A at 27 feet and 30 feet bgs, but these samples had elevated detection <br /> limits due to dilution factors Soil samples collected from borings SB10 and SB11 contained no <br /> detectable concentrations of TPHg, BTEX, or oxygenate fuel additives Analytical results of soil <br /> 1 samples are summarized in Table 1 <br /> 1 These data indicate that residual impacted soil from the former unleaded gasoline tanks exists in <br /> shallow soils and within the capillary fringe The vertical extent of impacted soil has been <br /> limited to less than 45 feet bgs, based on the analytical results from boring SB8 which was <br /> advanced through the location of the former UST pit in March 1998 and boring SB9A which was <br /> advanced through the center of the petroleum hydrocarbon plume in March 1999 The horizontal <br /> extent of TPHg and benzene residual impacted soil from the unleaded gasoline tanks has been <br /> ' defined to north, east, southeast, and west of the former UST pit as shown on Figures 3 and 4, <br /> respectively <br /> 1 4.2 Groundwater <br /> 1 Detectable concentrations of petroleum hydrocarbon analytes were present in the grab <br /> groundwater samples collected from borings SB10 and SB11 TPHg concentrations in <br /> 1 groundwater samples from borings SB10 and SBI 1 were 1,010 parts per billion (ppb) and 212 <br /> ppb, respectively The groundwater samples contained no detectable concentrations of BTEX <br /> The groundwater sample from boring SB 10 contained MTBE at 2 21 ppb No other oxygenate <br /> 1 fuel additives were detected in the groundwater sample from boring SB 10 The groundwater <br /> sample from boring SB 11 contained no detectable concentrations of oxygenate fuel additives <br /> 1 Groundwater analytical results are summarized in Table 2 <br /> The horizontal extent of impacted groundwater at the site has been defined to the west The <br /> 1 extent of impacted groundwater to the north, south, and east has not been fully defined Based <br /> on the analytical results from samples collected from well MW6 and borings SB7, SB 11, and <br /> SB l 0 the extent of impacted groundwater does not extend much further south and east <br /> w 1625961reportslphu1 doc 5 <br /> 1 <br />