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30 January 2004 AGE-NC Project No 96-0232 Page 12 of 15 water measurements or changes of recharge/discharge of the local ground water could greatly modify the inferred ground water flow direction • The average increase in ground water elevation of approximately 1 08 feet between September 2003 and December 2003 may be due to seasonal fluctuation Hydrographs depicting recorded ground water elevations at wells MW-2, MW-6A and MW-6B vs time are provided in Appendix T • The highest on-site concentrations of dissolved MTBE were detected in the sample collected from Second Zone well MW-8A at 400 µg/1 (Figure 9), lower concentrations of on-site MTBE were detected in water samples collected from First Zone wells EW-2,EW-4,EW-5, EW-7 through EW-10, and from Second Zone monitoring well MW-9A, generally, low to moderate MTBE increases were reported at wells MW-9A, EW-4 and EW-7 • The most intense First Zone off-site MTBE-impacted ground water were detected from the in the area of well Flag City Chevron well MW-16 and Three B's Truck Plaza wells MW-4 and MW-8A at concentrations as high as 99 µg/1 (Figure 8) • The most intense Second Zone off-site MTBE-impacted ground water were detected from the area of Flag City Chevron well MW-17 and Three B's Truck Plaza wells MW-9A and MW-1013 at concentrations of 45 µg/1 and less (Figure 9) • The most intense Rocky's Upper Zone off-site MTBE impacted ground water were detected from the area of Flag City Chevron wells MW-l l B and MW-18 at concentrations as high as 130 µg/1 (Figure 10, Table 6) Between the September and December 2003 quarterly monitoring events,a significant MTBE increase was reported at well MW-11B,from 78 µg/1 to 1309 µg/1 • Low concentrations of TPH-d have been detected at various wells during previous quarterly monitoring events at Flag City Chevron During December 2003, a low concentration of TPH-d was detected in the water sample collected from well MW-12A, screened within the First Zone aquifer AGE had previously asked McCampbell Analytical Laboratory to review the TPH-d sample chromatograms from MW-12A, the laboratory concluded that the low TPH-d detections from MW-12A did not have typical diesel characteristics, and that the detected chromatogram peaks were probably the result of biological interference 5.0. CONCLUSIONS AGE interpreted the results of all work completed to indicate that a Flag City Chevron release of petroleum hydrocarbons and associated MTBE occurred in the areas of the fuel dispensers,UST pit and/or storm drain, which then migrated through and along the First Zone and upper Second Zone Advanced GeoEnvironmental,Inc