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27 June 2002 AGE-NC Project No 98-0448 IPage 7of8 I • Previous and current analytical results from ground water samples suggest that there is a mmor MTBE, DIPE and TBA-Impact to ground water in the areas of wells MW-1, MW-2, MW-4 and MW-6 (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, Iand is at least 30 feet thick Based on SVE remediation data collected between 01 January and 31 March 2001,AGE concludes I • The volume of hydrocarbons extracted by the SVE system was calculated to be approximately 56 6 pounds, or approximately 9 05 gallons of petroleum hydrocarbons Iextracted (Appendix F) • The average SVE Inlet flow rate was 34 cubic feet per minute(cftn) at an average differential pressure of 0 35 Inches of water(Table 5) • No consistent concentration trends were evident in extracted soil-gas samples, however, a general decline from the PID field measurements was apparent over the First Quarter 2002 ' monitoring period 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, IMW-4A, MW-4B and MW-6, ground water sampling results will be used to monitor progress of the SVE and IAS remediation system I • 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 W • Continued operation of the on-site SVE and IAS remediation system, remediation progress will be re-evaluated on a quarterly basis • Alternating air sparging at regular intervals between MW-4B(screened 45 to 40 feet bsg)and 1AS wells AW-1 through AW-4 (screened 25 to 30 feet bsg) Advanced GeoEnvvonmental,Inc I