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20 February 2003 <br /> AGE-NC Project No 97-0290 <br /> Page 5 of 6 <br /> M = C•Q•t <br /> where M = cumulative mass recovered(kg) , <br /> C — soil-vapor concentration (kg/Iri ) <br /> Q = extraction flow rate (rOhr) <br /> It = operational period, in hours <br /> The calculated mass of hydrocarbons removed was based on laboratory analysis of soil-vapor <br /> I samples The mass of extracted hydrocarbons was calculated using average hydrocarbon <br /> concentrations of influent soil-vapor sample collected on 26 September 2002 (end of third quarter <br /> 2002) and 28 October 2002 and the average air flow rates at these two dates A calculated total of <br /> I 144 5kilograms, 318 5 lbs of approximately 50 9 gallons gasoline (TPH-g) were removed between <br /> September and October 2002 Operational paiameters are presented on Table 4 The volume/mass <br /> calculations are attached in Appendix D <br /> IDue to contaminant breakthrough (high TPH-g concentration) detected in the effluent sample <br /> collected on 28 October 2002, the SVE and IAS systems have been de-activated <br /> I• <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> Based on the data collected from the s,�e, AGE fids <br /> • Ground water was encountered m the monitoring wells at approximately 46 feet bsg and was <br /> inferred to have a southern flow direction during the January 2003 monitoring event <br /> I0 The highest concentrations of dissolved petroleum hydrocarbons were detected in samples <br /> collected ti om wells MW-2 and MW-4, pets oleum hydi ocarbons were not detected in wells <br /> MW-5 and MW-8 this quarter <br /> I0 Concentrations of TPH-g and benzene in wells MW-2 and i\4W-4 have exhibited declining <br /> trends over the past two years, as depicted in Appendix E <br /> • During fourth quartei 2002, an estimated 144 5kilogi ams, 318 5 lbs, 50 9 gallons gasoline <br /> (TPH-g) were removed from the subsurface of the site <br /> • Replacement of the SVE carbon vessels and continued opeiation of the [AS with SVE should <br /> Iresult in a reduction of the hydrocarbon impact to soil and giound watei <br />' 50 RECOMMENDATIONS <br /> Based on the findings of the environmental activities recounted in this report, AGE recommends <br /> I <br /> Advanced Geol;nvxromnental,Inc <br /> I <br />