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29 December 2003 <br /> AGE-NC Project No 95-0103 <br /> Page 4 of 5 <br /> • The BTEX compound benzene was detected in twelve of the soil samples analyzed, at a <br /> maximum concentration of 11 mg/kg in sample CB7-24 (20 feet bsg vertical depth), the <br /> benzene concentrations ranged from 001 mg/kg to 11 mg/kg Various other BTEX <br /> compounds were detected in ten of soil samples analyzed <br /> • The greatest concentrations of BTEX compounds were detected generally in soil samples <br /> collected at a vertical depth of 20 feet bsg The maximum concentration of the other BTEX <br /> compounds was detected in sample CB7-24 (20') at 110 mg/kg of xylene <br /> • MTBE and other fuel additives were not detected in the analyzed soil samples analyzed <br /> Laboratory results of soil samples analyzed for petroleum hydrocarbons area summarized in Tables 1 <br /> and 2 The laboratory reports (CTEL Laboratory ID 214-0311167, 0311168 and 0312010), quality <br /> assurance and quality control (QA/QC)reports and chains-of-custody are included in Appendix C <br /> 3 3 VOLUME MASS CALCULATION <br /> A volume-mass calculation of the remaining petroleum hydrocarbon-impacted soil under the building <br /> M yields an approximate volume of 18,000 ft'or 660 cubic yards Volume-mass calculations indicate <br /> that an estimated 60 gallons of adsorbed TPH-g remain in soil in the area delineated in Figure 2,an <br /> averaged concentration of 125 mg/kg TPH-g was used to calculate the total mass of remaining <br /> hydrocarbons in soil beneath the building The volume-mass calculations, based on the recently- <br /> acquired data, are presented in Appendix D <br /> 4.0. DISCUSSION/CONCLUSIONS <br /> Based on the results of this investigation, supplemented by quarterly ground water monitoring data, <br /> AGE concludes <br /> • Ground water was encountered at 17 feet bsg, hydrocarbons odor was detected in saturated <br /> sand encountered at the top of the ground water table <br /> • The highest concentrations of TPH-g were detected in soil samples collected between the <br /> vertical depths of 17 feet and 20 feet bsg The maximum hydrocarbon concentrations in soil <br /> were detected beneath that portion of the building nearest the former 8,000-gallon USTs <br /> located at the eastern edge of the site <br /> • The highest concentration of benzene was detected in sample CB7-24, collected from the <br /> vertical depth of 20 feet bsg south of the former 8,000-gallon easternmost USTs Benzene <br /> concentrations were not detected above the saturated zone <br /> • MTBE and other fuel additives were not detected in the soil samples <br /> Advanced GeoEnvironmental,Inc <br />