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17 February 2003 • AGE-NC Project No 95-0137 ' Page 4 of 7 t30 FINDINGS From field and laboratory data collected at the SVE remediation system between 19 September and ' 12 December 2002, AGE determined the average TPH-g concentration, the average flow rate and calculated the approximate mass and volume of hydrocarbons removed Ground water elevation, flow direction and gradient were determined from field data collected on 02 January 2003, the contaminant impact to ground water was quantified from the ground water laboratory data 3 1 SOIL,VAPOR EXTRACTION/IN SITU AIR SPARGING The SVE unit was operated continuously during the period between 19 September and 13 December 2002,except during maintenance The unit operated at an average extraction flow rate of 85 and 90 cubic feet per minute(cfin) An induced vacuum(negative pressure)of approximately 16 to 18 inches of water was measured in the piping between the blower and extraction wells Utilizing a photo ionization meter (PID), hydrocarbon concentrations were measured at 19 and 56 ppm at the SVE intake during this period The field measurements are summarized in Table 1 rAir-sparging rates were measured at approximately 4 scfm during each monitoring event A pressure of approximately 5 psi was maintained for the air sparging flow rate rElevated concentrations of dissolved oxygen were periodically detected in monitoring wells used as observation wells within andutside thePS network on the site, the highest dissolved oxygen � value, measured in well MW was % Generally, dissolved oxygen concentrations measured in the wells remained stable at/or sporadically increased above pre-remedial levels Dissolved oxygen measurements are presented in Table 3 32 ANALYTICAL RESULTS OF SOIL VAPOR SAMPLES r�t TPH-g was detected from all influent vapor samples at concentration of 120 lig/l, 77 µg/1 and 130 µg/1 (October, November and December), respectively Various BTEX compounds were ' detected at low concentrations in all influent vapor samples,the highest concentration was detected in the December xylenes at 9 5 lig/1 Benzene was detected in the October and December sample at a concentration up to 0 51 gg/l MTBE was not detected in any of the samples analyzed w- ' d BTEX compounds were detected in the effluent soil les at maximum vapor samples TPH-g an p p p concentrations of 49 pg/lfand xylenes at 0 47 gg/1 (December) The analytical results of the soil ' vapor samples are summarized on Table 2 The laboratory reports(MAI Sample Numbers 0210393- 01, 02, 0211395-01,02 and 0212251-01,02), Quality Assurance and Quality Control (QA/QC) ' reports and chain-of-custody forms are included in Appendix B Advanced GeaEnvirunmental,inc