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' 20 August 2003 AGE-NC Project No 95-0173 ' Page 7of8 changes of recharge/discharge of the local ground water could greatly modify ground water ' flow direction • The increase of ground water elevation of approximately 2 59 feet between December 2002 and April 2003 is probably due to seasonal fluctuation • Ground water at the site was approximately between 10 feet and 30 feet above the screen ' intervals (drowned) of wells AW-lA, AW-1B, 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 04 April 2003 suggests that ground water mounding may have occurred in the area of wells MW-3, MW-4 and AW-2 due to a ' combination of air sparging and an increase in SVE influent air flow at the site • The elevated concentrations of petroleum hydrocarbons detected in samples collected from wells AW-1 and MW-4 indicate that these wells are within the dissolved petroleum ' hydrocarbon "core area" of the plume (Figures 4), however, signifiant decreases were reported in the samples collected from wells MW-3 and AW-2 which were probably displaced due to the affect of ground water mounding • 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 ' and AW-2A (Tables 3 and 4) ' Based on SVE remediation data collected between 17 December 2002 and 20 March 2003, AGE concludes ' • The average SVE inlet vapor concentration was approximately 307 µg/1, the average SVE inlet flow rate was approximately 110 cubic feet per minute (Table 6) • The volume of hydrocarbons extracted by the SVE system was calculated to be approximately a3 gallons of petroleum hydrocarbons (Appendix F) during the December, January, February and March monitoring periods (Table 7) • Since initiation of the SVE system, the total volume of petroleum hydrocarbons extracted is estimated to be approximately 1,591 gallons (Table 7) • No general concentration trends were evident in the PID field measurements, however, laboratory analytical results were generally lower compared to the aid and 4' quarter 2002 monitoring periods Advanced GeoEnvironments],Inc