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07 May 2009 AGE-NC Project No. 97-0343 Page 6 of 7 • TPH-d at a depth of 10 feet bsg exceeded the ESL standard for leaching only; • TPH-d and TPH-g at a depth of 20 feet bsg exceeded the ESL standards for direct exposure, gross contamination and leaching, and leaching, respectively; • TPH-d and TPH-g at a depth of 25 feet bsg exceeded the ESL standards for direct exposure, gross contamination and leaching, and leaching, respectively; and • TPH-d and TPH-g at a depth of 30 feet bsg exceeded the ESL standards for leaching. A comparison of confirmation soil samples to ESLs is presented in Table 3. Soil leaching is not evaluated with ESLs program based on the ground water samples collected. While direct exposure and gross contamination are not evaluated for deep soil (10 feet)as these depths are not anticipated to be accessed from the surface and no current building basement exists on the site. ESLs Surfer reports for soil samples P1-5, P2-5, PI-10, PI-15, PI-20, P 1-25, and PI-30 for the constituents TPH (middle distillates and gasoline) are provided in Appendix E. 4.0. CONCLUSIONS Based upon soil data collected during advancement of soil borings, AGE concludes: • SVE was highly effective in the removal of adsorbed TPH-g, with an estimated 93% reduction in total TPH-g mass in soil utilizing the mass calculation of TPH-g in soil calculated prior to remediation (Appendix D). • SVE was highly effective in the removal of volatile BTEX compounds as evidenced by the non-detection of BTEX compounds in the samples analyzed from confirmation borings P1 and P2 (Tables 1 and 2). • SVE was moderately effective in the removal of adsorbed TPH-d, with an estimated 47% reduction in total TPH-d mass in soil utilizing the mass calculation of TPH-d in soil calculated prior to remediation(Appendix D).A small mass of high concentrations of TPH-d remains in the former UST area between the depths of 20 feet and 25 feet bsg (Figures 4, 6 and 7;Tables 1 and 2). This mass is separated from the ground water table by approximately 25 feet of non-detect soil or soil with very low concentrations of TPH (Figure 4). • TPH remaining in soil is likely non-volatile, and cannot be removed utilizing SVE. • Soil vapor intrusion does not appear to be a concern at the site due to the following: 1) soil samples collected between 5 feet and 15 feet bsg do not exceed the ESLs for direct exposure (e.g., protection of human health) as shown in Appendix E; 2) the remaining TPH mass is largely diesel; and 3)the remaining TPH mass is likely non-volatile. Advanced Geo£nvironmental,Inc.