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r.. <br /> percent (SB3). Nitrogen was detected at concentrations ranging from 18 percent (SBI and <br /> ` SB5) to 31 percent (SB6). Carbon dioxide was detected at concentrations ranging from 0.27 <br /> percent (SB3) to 6.2 percent (SB2). Carbon dioxide was not detected in the vapor samples <br /> w from borings SB5 and SB6. Methane was detected only in borings SBI and SB2 at 0.11 <br /> �. percent and 0.19 percent, respectively. Further discussion of these results is presented in <br /> Section 6.2. <br /> Table 3 summarizes soil vapor analytical results. Laboratory reports and chain of custody <br /> documentation for soil vapor samples are included as Appendix III. <br /> 5.0 DISTRIBUTION OF PETROLEUM HYDROCARBONS <br /> �- 5.1 Soil <br /> 5,1.1 Vadose Zone and Capillary Fringe <br /> �. Field observations and PID measurements during the advancement of the soil borings SBI <br /> SB2, SB7, FPB-1 and FPB-2 indicate that petroleum hydrocarbons are present in the vadose <br /> zone in limited areas of the site. This coincides with previous investigation and field <br /> observations, PID measurements and laboratory analytical data from the installation of <br /> monitoring wells MW-2 and MW-3 which indicated petroleum contamination of the vadose <br /> zone. PID measurements collected from the soil vapor line open to between 6 and 8 feet bgs <br /> in borings SB1 and SB2, and field observations from boring SB7 all indicate petroleum <br /> �- hydrocarbon contamination of the vadose zone in these areas. Petroleum hydrocarbons' are <br /> present in the vadose zone in the vicinity of the former gasoline USTs as indicated by results <br /> �. from MW2 and downgradient of the former gasoline USTs as indicated by results from MW3, <br /> SB2, FPB-1, FPB-2 and SB7. <br /> L <br /> Generally field observations, PID measurements and laboratory analytical data collected during <br /> this investigation indicate petroleum hydrocarbon-affected soils are present in the capillary <br /> fringe at depths from approximately 8 to 12 feet bgs. This data coincides with data from the <br /> ` previous investigation and well installation. The highest levels of petroleum hydrocarbons <br /> '.0 noted in soil samples from this portion of the field investigation were in the sample collected <br /> from SB-7 at 10.5 feet bgs. This sample contained TPHg (950 ppm), benzene (4.9 ppm), <br /> toluene (16 ppm), ethylbenzene (33 ppm) and xylenes (130 ppm). <br /> Figures 4 and 6 show the estimated lateral extent of TPHg and benzene concentrations in soil <br /> ( between 6 and 10 feet bgs, the vadose zone and capillary fringe. As indicated on Figure 4, the <br /> J <br /> V wA951221PIumerpt 9 <br /> • <br /> LW <br /> SIY�TN <br />