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• 04 January 2002 <br /> AGE-NC Project No 95-0137 <br /> Page 4 of 6 <br /> (MAI Sample Numbers 67145, 67149, 70868, 70869, 72766,72767,74507,74508, 77934, 77935, <br /> 80937, 80938, 83119, 83120, 86511 and 86512) Quality Assurance and Quality Control (QA/QC) <br /> reports and chain-of-custody forms are included in Appendix B Extracted organic vapor <br /> concepti ations measured with the OVM were low compared to the analytical results from the soil- <br /> vapor samples The highest concentration of organic vapor measured with the OVM was 99 ppm <br /> 3 2 MASS OF RECOVERED HYDROCARBONS <br /> ' The hydrocarbon mass (TPH-g) removed during the operating period was calculated using the <br /> equation M = C•Q•t <br /> 1 where M = cumulative mass recovered(kg) <br /> C =soil-vapor concentration(kghn ) <br /> Q= extraction flow rate (m3/hr) <br /> t= operational period, in hours <br /> The operational time was divided into seven time periods The estimated mass of hydrocarbons <br /> removed was based on laboratory analysis of soil-vapor samples The mass of extracted hydrocarbons <br /> was calculated foi each time period using average hydi ocarbon concentrations of influent soil-vapor <br /> sample data and average air flow rates The opei ational results are summarized on Table 2 A total <br /> of 189 5 gallons of 537 4 kg of hydrocarbons as gasoline removed and destroyed by the SVE <br /> network between 04-09-01 and 12-13-01 The volume and mass calculations are attached in <br /> Appendix C <br />' 3 3 IN-SITU AIR SPARGING <br /> Elevated concentrations of dissolved oxygen were periodically detected in monitoring wells used as <br /> observation wells within and outside the IAS network on the site The highest dissolved oxygen value <br /> measured in well MW-1 was at 12 1 % and in well MW-2 was at 20 8% Generally, dissolved oxygen <br />' concentrations measured in the wells remained stable at/or sporadically increased above pre-remedial <br /> levels Sparging rates were measured at approximately 6 sctm. during each monitoring event A <br /> pressure of approximately 10 psi was maintained for the air spai ging flow rate Dissolved oxygen <br /> measurements are presented in Table 4 <br /> 1 3 4 GROUND WATER GRADIENT AND FLOW DIRECTION <br /> The elevation of ground water in each well was calculated by subtracting the depth to ground water <br />' from the surveyed well casing elevations (Table 2) <br /> Advanced GeoEnvironmental,Inc <br />