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I26 September 2002 AGE-NC Project No 98-0448 Page 7 of 8 I • Previous and current analytical results from ground water samples suggest that there is a minor MTBE, DIPE and TBA-impact to ground water in the areas of wells MW-1, MW-2, MW-4, MW-6 and MW-8 (Table 2) • Laboratory results of ground water samples collected from MW-4B (screened 45 to 50 feet bsg) suggest that the dissolved petroleum hydrocarbon plume extends to at least 50 feet bsg, and Is at least 30 feet thick Based on SVE remediation data collected between 11 March and 11 June 2002, AGE concludes I • The volume of hydrocarbons extracted by the SVE system was calculated to be approximately 69 pounds,or approximately 11 gallons of petroleum hydrocarbons extracted ' (Appendix F) • The average SVE inlet flow rate was 36 cubic feet per minute(cfm)at an average differential pressure of 0 42 inches of water (Table 5) • A decreasing trend ofhydrocarbon concentrations were evident in extracted soil-gas samples, I however, a general trend was not evident from the PID field measurements over the March, April, May and June 2002 monitoring periods ' 6.0. RECOMMENDATIONS IBased upon the results of this investigation, AGE recommends • Continued quarterly ground water monitoring and sampling of wells MW-1, MW-2, MW-4A, MW-4B and MW-6, ground water sampling results will be used to monitor progress of the SVE and IAS remediation system r ' • Monthly depth to ground water measurements collected from all monitoring wells (MW-1 through MW-6) to monitor for ground water mounding resulting from IAS • Continued operation of the on-site SVE and IAS remediation system, remediation progress will be re-evaluated on a quarterly basis • Alternate air sparging at regular intervals between MW-4B (screened 45 to 40 feet bsg) and IAS wells AW-1 through AW-4 (screened 25 to 30 feet bsg) 4 Advanced GeoEnvironmental,Inc I