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E 1 r r 15 September 2000 AGE-NC Project No 95-0103 Page 4 of 5 a , The SVE unit operated at an extraction flow rate of 185 scfm An induced vacuum (negative ' pressure)'of 32anches of water was measured in the piping between the blower and extraction wells, i TPH-g and BTEX compounds were detected in the one sample collected during the quarter The r laboratory report(MAI Lab ID No 45579),QA/QC reports and chain-of-custody forms are included in Appendix D i - 4.0. DISCUSSION/CONCLUSIONS ' Based on the analytical results from this Investigation, the following conclusions are presented I , ' The relative ground water elevation at the site decreased 127 feet over the last quarter The map of ground water contours indicates a divergent ground water flow direction toward the south Monitoring wells MW-1,MW-2,MW-3 and MW-4 had ground water approximately four to six feet above the top of the screened interval,potentially reducing the effectiveness of these ground water monitoring wells to characterize the dissolved-phase hydrocarbon plume in the shallowest ground water 1 • TPH-g was detected this quarter in MW-1, MW-3, MW-4, MW-5, VE-1 and VE-6 In ' general,the TPH-g concentrations have remained fairly stable when compared to the results from the April 2000 sampling event, with concentrations decreasing slightly in MW-5 and ' VE-6 and Increasing slightly in MW-1, MW-3, and VE-1 A significant decrease of TPH-g ' concentrations did occur in sample MW-4, with concentrations dropping from 17,000 µg11 ` in April 2000 to 3,900 µg/l during this quarter BTE&X compounds show similar trends in these wells • Fuel oxygenates, including MTBE, DIPE or TBA,were detected in samples MW-1,MW-3, MW-4, MW-6, VE-1 and VE-6 The highest oxygenate concentration detected was 91 µg/1 of TBA in sample MW-1 5 An overall reduction of the di ssolved-phase hydrocarbon plume concentrations on the site has ' occurred since ground water monitoring began in 1994 However,the dissolved hydrocarbon ; concentrations,specifically benzene have fluctuated over the past four quarters The detection of petroleum hydrocarbons in monitoring wells MW-4 and MW-5 indicate that the ' hydrocarbon plume has not been delineated to the west, south and southeast r' Advanced GeoEnvironmcntal,Inc j ` 1 i