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r 31 October 2003 AGE-NC Project No 95-0173 Page 7 of 8 • Ground water at the site was approximately between 10 feet and 30 feet above the screen intervals (drowned) of wells AW-1A, AWAB, AW-2A and AW-2B and may not yield samples fully representative of shallowest ground water conditions, ground water was between 65 and 115 feet above the screen intervals of multi-level well MW-13 (A-C),which was designed to collect ground water representative of deep ground water conditions The ground water elevation appeared to be within or near the screen intervals of all other wells at the site and should be representative of shallowest ground water conditions • Ground water elevation data collected on 24 June 2003 does not suggest that ground water mounding may have occurred • The elevated concentrations of petroleum hydrocarbons detected in samples collected from wells AW-1 A(screened 39 to 44 feet bsg) ,AW-2A(screened 40 to 45 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) • Generally, an apparent trend of decreasing petroleum concentrations is evident in samples collected from wells MW-2, MW-3, MW-4, MW-6 and AW-2B, the trend of decreasing concentrations may be attributed to air sparge activities being performed at wells AW-1 through AW-7 • 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 20 Manch 2003 and 23 .lune 2003, AGE concludes • The average SVE inlet vapor concentration was approximately 144 µg/1, the average SVE inlet flow rate was approximately 105 cubic feet per minute (Table 6) • The volume of hydrocarbons extracted by the SVE system was calculated to be approximately 16 gallons of petroleum hydrocarbons(Appendix F)during the March,April, May and June 2003 monitoring periods (Table 7) • Since initiation of the SVE system,the total volume of petroleum hydrocarbons extracted is estimated to be approximately 1,607 gallons (Table 7) • No general concentration trends were evident in the PID field measurements, however, laboratory analytical results from the I" and 2n° quarter 2003 monitoring periods have continued to be lower compared to the 3rd and 4h quarter 2002 monitoring periods • Due to a malfunction in the SVE electric control panel, the SVE unit was non-operational for repairs and maintenance between 20 March and 01 April 2003 Advanced GeoEnvironrnental,Inc