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lit i 31 January 2005 AGE-NC Project No 96-0232 Page 6 of 9 gradients were calculated to be 0 004 ft/ft or less Due to the low ground water gradient at the site, small variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify the inferred ground water flow direction(Figures 4 through 7) • The most intense on-site Flag City Chevron MTBE concentrations were detected from Second Zone well MW-8A at 290 µg/l (Figure 9), lower concentrations of on-site MTBE were detected from First Zone wells MW-2,MW-4 and from Second Zone monitoring well MW-9A, a significant MTBE increase was reported at well MW-2 (Figures 8 and 9) • The most intense off-site MTBE concentrations were detected north of the site from First Zone wells MW-19 A and MW-20A at concentrations as high as 900 µg/l, low to moderate MTBE concentrations were detected in First Zone wells west of the site at Three B's Truck Plaza from wells MW-1, MW-2, MW-4, MW-5, MW-8A, MW-10A and at Rocky's Restaurant from wells MW-7 and MW-16(Figure 8) Between the June 2004 and December 2004 quarterly monitoring events, a significant MTBE decrease was reported at well MW-19A, from 4800 µg/1 to 1,300 µg/1 to 900 µg/l (Figure 8) • Low to moderate off-site MTBE concentrations (as high as 110 µg/1) were detected in M Second Zone wells west-southwest of the site at Rocky's Restaurant from wells MW-11A, MW-14, MW-17, west-northwest of the site from at Three B's Truck Plaza from wells MW-8B,MW-9A,MW-10, MW-11B, and north of the site at McDonald's Restaurant from well MW-20B (Figure 9) • Low to moderate offsite MTBE concentrations (as high as 150 µg/1) were detected in Rocky's Upper Zone wells west of the site at Rocky Restaurant from wells MW-11B and MW-18 (Figure 10, Table 4) • Low concentrations of TPH-d have been detected at various wells during previous quarterly monitoring events at Flag City Chevron During December 2004, a low concentration of TPH-d was detected in the water samples collected from well MW-12A 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 4.0. CONCLUSIONS Based on the initial site conceptual model, AGE previously interpreted the results of all work completed to indicate that historically,a Flag City Chevron unauthorized release of MTBE occurred in the areas of the fuel dispensers, UST pit and/or storm drain, which then migrated westward Advanced CeoEnvironmentat,Inc