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y <br /> • <br /> HYDROCARBON DISTRIBUTION IN SOIL <br /> TPHg and BTEX were not detected in soil from any of the borings MTBE was detected (by <br /> EPA Method 8260B) in borings MW-1 through MW-3, GP-3 and GP-5 at concentrations <br /> ranging from 0 00596 to 2 13 ppm TBA was also detected in boring MW-2 at 0 140 ppm <br /> The soil chemical analytical data are summarized in Table 2 and presented on Figure 2 <br /> Laboratory analytical data are presented in Appendix E <br /> HYDROCARBON DISTRIBUTION IN GROUNDWATER <br /> The groundwater samples collected from wells MW-1 through MW-3 contained TPHg <br /> concentrations ranging from 75 3 to 183 ppb and MTBE (by EPA Method 8260A) ranging <br /> from 104 to 6,990 ppb Benzene was detected in wells MW-1 and MW-2 at concentrations <br /> of 1 51 and 0 663 ppb, respectively Benzene was not detected in well MW-3 <br /> Groundwater chemical analytical data are summarized in the summary table in Blaine's report <br /> (Appendix C) and Table 3 and presented on Figure 3 Laboratory analytical data are also <br /> presented in Blaine's report (Appendix C) <br /> CONCLUSIONS <br /> The soil samples from borings GP-3 through GP-6, drilled in the dispenser island area, did not <br /> contain petroleum hydrocarbons Low concentrations of MTBE were detected in GP-3 and <br /> GP-5 at depths of 5 and 4 5 fbg, respectively No MTBE was detected in deeper soil samples <br /> from these borings, therefore, the impact is vertically defined in soil in the dispenser island <br /> area These data suggest the dispenser island area is not the source area for petroleum <br /> hydrocarbons and MTBE detected in groundwater beneath the site <br /> Soil boring MW-2 was drilled adjacent to the product piping, which runs between the USTs <br /> and the dispenser islands Low levels of MTBE detected in soil in this boring do not suggest <br /> this area is a source area for petroleum hydrocarbons and MTBE detected in groundwater <br /> beneath the site <br /> Based on monitoring data collected December 7, 1999, groundwater flow is to the southwest <br /> at an approximate hydraulic gradient of 0 002 (Figure 3) <br /> Petroleum hydrocarbon and MTBE concentrations in groundwater from downgradient well <br /> MW-3 and soil borings SB-3 and SB-4, from a previous investigation (Table 4), indicate that <br /> 955 5 <br />