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i <br />' 06 November 2002 <br /> • AGE-NC Project No 95-0137 <br /> Page 4 of 7 <br /> 3 1 SOIL VAPOR EXTRACTION/IN-SITU AIR SPARGING <br /> The SVE unit was operated continuously during the period between 11 June and 19 September 2002, <br /> except during maintenance The unit operated at an average extraction flow rate of 85 cubic feet per <br /> minute(cfm) An induced vacuum(negative pressure)of approximately 16 to 20 inches ofwater was <br />' measured in the piping between the blower and extraction wells Utilizing a photo ionization meter <br /> (PID),hydrocarbon concentrations were measured between 11 and 71 ppm at the SVE intake during <br /> this period The field measurements are summarized in Table 1 <br />' Air-sparging rates were measured at approximately 4 scfm during each monitoring event A pressure <br /> of approximately 5 psi was maintained for the air sparging flow rate <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 <br /> ' value,measured in well MW-1,was 16 7% Generally,dissolved oxygen concentrations measured <br /> in the wells remained stable at/or sporadically increased above pre-remedial levels Dissolved <br /> . oxygen measurements are presented in Table 3 <br /> 3 2 ANALYTICAL RESULTS OF SOIL-GAS VAPOR SAMPLES <br /> PH- was detected from all influent and effluent SVE air flow samples at concentrations as high <br /> T g P <br /> as 430 µg/1 (19 September 2002)and 190 µg/1 (17 July 2002), respectively <br /> i <br /> Various BTEX compounds were detected at low concentrations in all influent and effluent SVE air <br /> ' flow samples, benzene was detected in the 19 September 2002 influent sample at a concentration <br /> of 0 62 µg/1 MTBE was not detected in any of the samples analyzed <br /> The analytical results of the soil vapor samples are summarized on Table 2 The laboratory reports <br /> (MAI Sample Numbers 0207237-01,02, 0208324-01,02 and 0209323-01,02), Quality Assurance <br /> and Quality Control (QA/QC) reports and chain-of-custody forms are included in Appendix B <br /> 33 MASS OF RECOVERED HYDROCARBONS <br /> ' The hydrocarbon mass (TPH-g) removed during the operating period was calculated using the <br /> equation <br /> M = C•Q•t <br /> iAdvanced GeoEnvironmental,Inc <br /> 1 <br />