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I03 October 2003 <br /> AGE-NC Project No 97-0290 <br /> Page 5 of 6 <br /> ` The influent soil-vapor sample collected on 11 September contained detectable <br /> concentrations of TPH-g(2,100µg/1)and the BTEX compounds benzene(5 9 pg/1),toluene <br /> (9 5 gg/I), ethylbenzene (2 2 µg/1) and total xylenes (44 gg/1) <br /> I No additional Yt target analytes were detected The analytical results are summarized on Table 2 The <br /> g Yt <br /> laboratory reports (MAI Laboratory Report Numbers 0303176, 0304257, 0305204, 0306492, <br /> 0307437, 0308233, and 0309220) Quality Assurance and Quality Control (QA/QC) reports and <br /> chain-of-custody forms are included in Appendix C <br /> 3 4 SOIL VAPOR EXTRACTION <br /> IThe carbon-based SVE system operated between 11 March and 11 September 2003, during the <br /> quarters The hydrocarbon mass(TPH-g)removed during the operating period was calculated using <br />' the following equation M =C•Q•t where <br /> M =cumulative mass recovered (kg) <br /> C = soil-vapor concentration(kg/m') <br /> Q =extraction flow rate (m3/hr) <br /> t=operational period, in hours <br /> The calculated mass of hydrocarbons removed was based on laboratory analysis of soil-vapor <br /> samples The mass of extracted hydrocarbons was calculated using average hydrocarbon <br /> concentrations of influent soil-vapor sample collected between 11 March and 11 September 2002 <br /> and the average air flow rates at the dates A calculated total of 1,552 lbs of gasoline (TPH-g) and <br /> 2 879 lbs of benzene were removed between March and September Operational parameters are <br /> presented on Table 5 The volume/mass calculations are attached in 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 48 feet bsg and was <br /> inferred to have a southern to southeastern flow direction during the August 2003 monitoring <br />' event <br /> The ground water elevation has decreased over two feet dunng the quarters,which increased <br /> the vadose soil to the SVE system and decreased the amount of free-water within the <br />' monitoring wells screen, thus may have produced a more concentrated water sample from <br /> . the water table This explains the increased concentration in the on-site well MW-2 <br />' Advanced GeoEnvironmental,Inc <br /> 1 <br />