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06 November 2002 <br /> • AGE-NC Project No 97-0290 <br /> IPage 5 of 6 <br />' 34 SOIL VAPOR EXTRACTION <br /> A carbon-based SVE system operated during the quarter The hydrocarbon mass(TPH-g)removed <br />' during the operating period was calculated using the following equation <br /> M = C•Q•t <br />' where M = cumulative mass recovered (kg) <br /> C = soil-vapor concentration (kg/m 3) <br />' Q = extraction flow rate (m3/hr) <br /> t= operational period, in hours <br />' The operational time was divided into three time periods The calculated mass of hydrocarbons <br /> removed was based on laboratory analysis of soil-vapor samples The mass of extracted <br /> hydrocarbons was calculated for each time period using average hydrocarbon concentrations of <br />' influent soil-vapor samples collected and average air flow rates A total of 439 8 kilograms,971 6 lbs <br /> or approximately 155 gallons gasoline (TPH-g) were removed between 11 June and 26 September <br />' • 2002 <br /> Operational parameters are presented on Table 4 The volume/mass calculations are attached in <br />' Appendix D <br /> 4 0. SUMMARY AND CONCLUSIONS <br /> Based on the data collected from the site, AGE finds <br />' 0 Ground water was encountered in the monitoring wells at approximately 49 feet bsg and was <br /> inferred to have a southern flow direction during the September 2002 monitoring event <br />' 0 The highest concentrations of dissolved petroleum hydrocarbons were detected in samples <br /> collected from wells MW-2 and MW-4,petroleum hydrocarbons were not detected in wells <br /> MW-5 and MW-8 this quarter <br />' a Concentrations of benzene have decreased in wells MW-2 and MW-4 over the past quarter, <br /> but are still well above the State of California DHS' maximum contaminant level (MCL)of <br />' 10 µg11 <br /> • A total of 439 8 kilograms, 9716 lbs or approximately 155 gallons gasoline (TPH-g) were <br /> removed between 11 June and 26 September 2002 Continued operation of the SVE should <br />' result in diminishing recovery, signifying a reduction of the hydrocarbon impact to soil <br /> • <br />' Advanced Geo Envi ron mental,Inc <br /> 1 <br />