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' 26 September 2002 <br /> • 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 />' • Moderate decreases in concentrations of dissolved TPH-g and BTEX were quantified in <br /> ground water samples collected from wells MW-1, MW-2, MW-3, MW-4, AW-1A and <br /> AW-2A(Table3) while moderate increases were reported from wells 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 /> Iand MW-5 (Tables 3 and 4) <br /> I Based on SVE remediation data collected between 11 March 2002 and II June 2002, AGE <br /> concludes <br /> • The average SVE inlet vapor concentration was approximately 428 µg/l, the average SVE <br /> Iinlet flow rate was approximately 98 cubic feet per minute (Table 6) <br /> • The volume of hydrocarbons extracted by the SVE system was calculated to be <br /> approximately 55 gallons of petroleum hydrocarbons(Appendix F)during the March,April, <br /> May and June monitoring periods (Table 7) <br /> I • Since initiation of the SVE system,the total volume of petroleum hydrocarbons extracted is <br /> estimated to be approximately 1,280 gallons (Table 7) <br /> • No general concentration trends were evident in the PID field measurements or from the <br /> Iextracted soil-gas sample analytical results over the March,April,May and June monitoring <br /> periods <br /> 6.0. RECOMMENDATIONS <br /> Based upon second quarter 2002 data collected from the site, AGE recommends <br /> • Continued quarterly ground water monitoring and sampling ofwells MW-1 through MW-12, <br /> AW-1 A, AW-1B, AW-2A and AW-2B, ground vater sampling results w1d. be used M <br /> monitor progress of the SVE and IAS remediation system <br /> • Continued operation of the on-site SVE and IAS remediation system, remediation progress <br /> will be reevaluated on a quarterly basis <br /> To address deeper petroleum hydrocarbon-impacted ground water at the site,AGE proposes that at <br /> least one additional remediation alternative be evaluated due to the modest to below average <br /> clean-Advanced GeoEnvironmental,Inc <br />