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' 25 November 2002 <br /> AGE-NC Project No 98-0448 <br />' Page 7 of 8 <br />' • Previous and current analytical results from ground water samples suggest that there is a <br /> minor MTBE, DIPE and TBA-impact to ground water in the areas of wells MW-1, MW-2, <br /> MW-4 and MW-6 (Table 2) <br />' • Laboratory results of ground water samples collected from MW-4B (screened 45 to 50 feet <br /> bsg)suggest that the dissolved petroleum hydrocarbon plume extends to at least 50 feet bsg, <br />' and is at least 30 feet thick <br /> • Significant decreases in dissolved petroleum hydrocarbons reported in ground water samples <br />' from wells MW-2, MW-4A and MW-413 may be attributed to the air sparging activity at <br /> MW-4B <br /> • Wells MW-1 and MW-6 did not detect any petroleum hydrocarbon constituents of concern, <br />' which may be attributed to a reduction in the size of the dissolved petroleum hydrocarbon <br /> plume <br />' Based on SVE remediation data collected between 11 June and I 1 September 2002,AGE concludes <br /> . • The volume of hydrocarbons extracted by the SVE system was calculated to be <br />' approximately 182 pounds,or approximately29 gallons of petroleum hydrocarbons extracted <br /> (Appendix F) <br />' • The average SVE inlet flow rate was 41 cubic feet per minute(cfm)at an average differential <br /> pressure of 0 55 inches of water (Table 5) <br />' • No general trends were evident from the PID field measurements or the hydrocarbon <br /> concentrations in extracted soil-gas samples over the June,July,August and September 2002 <br /> monitoring periods <br />' 6.4. RECOMMENDATIONS <br /> Based upon the results of this investigation, AGE recommends <br />' • Continued quarterly ground water monitoring and sampling of wells MW-1, MW-2, <br /> MW-4A,MW-4B,MW-6 and MW-8,ground water sampling results will be used to monitor <br /> progress of the SVE and 1AS remediation system <br />' - Monthly depth to ground water measurements collected from all monitoring wells (MW-1 <br /> through MW-8) to monitor for ground water mounding resulting from 1AS <br />' - Continued operation of the on-site SVE and 1AS remediation system, remediation progress <br /> will be re-evaluated on a quarterly basis <br />' Advanced GeoEnvaronmental,Inc <br /> I <br />