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1 - ' 16 June 2004 AGE-NC Project No 95-0173 ' Page 8 of 9 ' • Ground water elevation data collected on 08 November 2003 does not suggest that ground water mounding may have occurred due to the on-going LAS activities • The elevated concentrations of petroleum hydrocarbons detected in samples collected from ' wells AW-1B (screened 50 to 60 feet bsg), AW-2A (screened 40 to 45 feet bsg), AW-2B (screened 60 to 70 feet bsg)and MW-4(screened 30 to 50 feet bsg)indicate that these wells are within the remaining dissolved petroleum hydrocarbon "core area" of the plume ' (Figures 4) • The continued decrease in hydrocarbon concentrations observed at well AW-1B may be ' attributed to the September, October and November 2003 IAS activities performed at AW-1B, the rapid,upward movement of hydrocarbons was substantiated with the observed `spike' in the September, October and November 2003 influent air flow samples ' • Generally, an overall apparent trend of decreasing dissolved petroleum concentrations is evident in samples collected from wells MW-I, MW-2, MW-3, MW-4, MW-6, AW-1 (A and B)and AW-2 (A and B), the trend of decreasing concentrations may be attributed to the air sparge activities being performed at wells AW-IB and AW-2B (Table 3) • A moderate increase in dissolved hydrocarbons was observed from well AW-1A, the ' increase in hydrocarbon concentrations may also be attributed to IAS activities being conducted from AW-1B with upward movement of dissolved petroleum hydrocarbons at deeper depths • Previous and current laboratory results of ground water samples suggest that there is a minor MTBE- and 1,2-DCA-impact to ground water in the areas of wells MW-2 through MW-5, MW-11 and AW-2A (Tables 3 and 4) Based on SVE remediation data collected between 09 September 2003 and 30 December 2003,AGE concludes • The average SVE inlet vapor concentration was approximately 2,240 p,g/l,the average SVE inlet flow rate was approximately 86 cubic feet per minute (Table 6) • The volume of hydrocarbons extracted by the SVE system was calculated to be approximately 201 gallons of petroleum hydrocarbons(Appendix F) during the September, October, November and December 2003 monitoring periods (Table 7) • Since initiation of the SVE system, the total volume of petroleum hydrocarbons extracted is estimated to be approximately 1,899 gallons (Table 7) • A spike in the PID field measurements and influent SVE air samples was evident during the • fourth quarter 2003 monitoring periods and coincided with the reconfiguration of the SVE well network from VW-1 through VW-7 to VW-1 through VW-4 SVE Wells VW-5 through IAdvanced GeoEnvironmental,Inc I