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15 November 2002 14.01 AGE-NC Project No. 95-0173 Page 7 of 8 • Moderate decreases in concentrations of dissolved TPH-g and BTEX were quantified in ground water samples collected from wells MW-1,MW-2,MW-3,MW-4,AW-1A,AW-1B and AW-2A (Table3) while a moderate increase was reported from AW-2B. • 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, MW-3, MW-4 and MW-5 (Tables 3 and 4). Based on SVE remediation data collected between 11 June and 26 September 2002,AGE concludes: • The average SVE inlet vapor concentration was approximately 548 µg/1; the average SVE `r inlet flow rate was approximately 98 cubic feet per minute (Table 6). • The volume of hydrocarbons extracted by the SVE system was calculated to be approximately 68 gallons of petroleum hydrocarbons (Appendix F) during the June, July, August and September monitoring periods (Table 7). • Since initiation of the SVE system,the total volume of petroleum hydrocarbons extracted is estimated to be approximately 1,348 gallons (Table 7). • No general concentration trends were evident in the PID field measurements; however, increasing extracted soil-gas sample analytical results were evident over the July,August and September monitoring periods. 6.4. RECOMMENDATIONS rr Based upon third quarter 2002 data collected from the site, AGE recommends: L, • Continued quarterly groundwater monitoring and sampling of wells MW-1 through MW-12, AWAA, AW-1B, AW-2A and AW-2B; ground water sampling results will be used to monitor progress of the SVE and IAS remediation system. • Continued operation of the on-site SVE and 1AS remediation system; remediation progress will be reevaluated on a quarterly basis. To address deeper petroleum hydrocarbon-impacted ground water at the site,AGE proposes that at least one additional remediation alternative be evaluated due to the modest clean-up effectiveness being encountered utilizing IAS.The well-defined,laterally continuous,sandy nature of Hydrologic Unit 2 (38 feet to 65 feet bsg) is suitable for a ground water extraction system screened solely through Hydrologic Unit 2; implementation of a ground water pump-and-treat technology would augment the IAS clean-up efforts in Hydrologic Unit 1. LW Advanced GeoEnvironmentai,Inc.