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07 May 2009 <br /> AGE-NC Project No. 97-0343 <br /> Page 5 of 7 <br /> 3.4.1. Remaining Adsorbed TPH-g <br /> The mass of TPH-g remaining in soil was determined on the basis of averaged TPH-g concentrations <br /> in soil samples collected from site assessment activities and utilizing Figures 4, 5 and 8. AGE's <br /> calculations estimate approximately 169 pounds or 27 gallons of gasoline remain in soil at the site. <br /> This represents a 93%reduction in total TPH-g mass in soil utilizing the mass calculation of TPH-g <br /> in soil calculated prior to remediation (2,388 lbs of gasoline; presented in AGE-prepared Interim <br /> Corrective Action Plan dated 20 January 2005).Adsorbed TPH-g mass and volume calculations are <br /> presented in Appendix D. <br /> 3.4.2. Remaining Adsorbed TPH-d <br /> The mass of TPH-d remaining in soil was determined on the basis of averaged TPH-d concentrations <br /> in soil samples collected from site assessment activities and utilizing Figures 4 through 8.Two zones <br /> of TPH-d-impacted soil (the outer zone [concentrations below 3,000 mg/kg] and the inner zone <br /> [concentrations above 3,000 mg/kg])were utilizing in determining the remaining TPH-d mass at the <br /> site.AGE's calculations estimate approximately 1,090 pounds or 156 gallons of diesel remain in soil <br /> at the site. <br /> This represents a 47%reduction in total TPH-d mass in soil utilizing the mass calculation of TPH-d <br /> in soil calculated prior to remediation (2,049 lbs of diesel; presented in AGE-prepared Interim <br /> Corrective Action Plan dated 20 January 2005).Adsorbed TPH-d mass and volume calculations are <br /> presented in Appendix D. I <br /> 3.5. ENVIRONMENTAL SCREENING LEVELS EVALUATION <br /> In order to evaluate the potential for vapor intrusion at the site, analytical results from soil samples <br /> collected from confirmation borings P 1 and P2(including shallow soil samples collected at five feet <br /> bsg)were compared to the SanFrancisco Bay Region Water Quality Control Board's Environmental <br /> Screening Levels(for commercial or industrial area,where ground water is a potential drinking water <br /> resource) for TPH-g, TPH-d and BTEX. <br /> All soil samples analyzed from boring P2 passed ESL standards for all constituents analyzed, <br /> including depths of 5 feet and 10 feet bsg. Confirmation soil boring P2 is located in close proximity <br /> to, approximately 8 feet,one of the site buildings. All soil samples analyzed from boring P 1 passed <br /> ESL standards for all constituents analyzed, including the depth of 5 feet bsg, except for the <br /> following: <br /> Advanced GeuEnviron mental,Inc. <br />