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1 - <br /> 19 July 2002 <br /> i AGE-NC Project No 95-0173 <br /> Page 7 of 8 <br />' • The highest dissolved petroleum hydrocarbons were detected in the area of well AW-2, with <br /> increasing depth, the dissolved plume apparently grades from higher concentrations to lower <br /> concentrations <br /> • A moderate to substantial increase in concentrations of dissolved TPH-g and BTEX were <br /> quantified in ground water samples collected from wells MW-2,MW-3,MW-6, AW-1A and <br /> AW-2A (Table3) wluch may be interpreted as a"rebound effect"while alternating IAS with <br /> deeper intervals AW-1B and AW-2B <br /> • Previous and current laboratory results of ground water samples suggest that there is a minor <br /> MTBE- and 1,2-DCA-impact to ground water in the areas of wells MW-2, MW-3, MW-4 <br /> and MW-5 (Tables 3 and 4) <br /> • Laboratory results of ground water samples collected from MW-13 (screened 95 to 100 feet <br /> bsg) suggest that the dissolved petroleum hydrocarbon plume extends to at least 100 feet bsg, <br /> and is at least 65 feet thick <br /> Based on SVE remediation data collected between 31 December 2001 and 29 March 2002, AGE <br /> concludes <br /> • The average SVE inlet vapor concentration was approximately 627 ,ug/l, the average SVE <br /> inlet flow rate was approximately 95 cubic feet per minute (Table 6) <br /> • The volume of hydrocarbons extracted by the SVE system was calculated to be <br /> approximately 70 gallons of petroleum hydrocarbons (Appendix F) during the first quarter <br /> monitoring period (Table 7) <br /> • Since initiation of the SVE system, the total volume of petroleum hydrocarbons extracted is <br /> estimated to be approximately 1,225 gallons (Table 7) <br /> I • No general concentration trends were evident in the PID field measurements, however, a <br /> general decline from extracted soil-gas samples was apparent in analytical results over the <br /> First Quarter 2002 monitoring period <br /> 6.0. RECOMMENDATIONS <br /> Based upon first quarter 2002 data collected from the site, AGE recommends <br /> I • Continued quarterly ground water monitoring and sampling of wells MW-1 through MW-13, <br /> AW-lA, AW-1B, AW-2A and AW-2B, ground water sampling results will be used to <br /> monitor progress of the SVE and 1AS remediation system <br /> • Continued operation of the on-site SVE and 1AS remediation system, remediation progress <br /> will be reevaluated on a quarterly basis <br /> IAdvanced GeoEnvironmental,Inc <br />