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1 ' 11 August 2003 AGE-NC Project No 96-0232 ' Page 12 of 15 • First Zone ground water was inferred to be radially inward towards a ground water ' depression in the area.of Flag City Chevron wells MWA,MW-2 and MW-4 at a gradient of 0 002 ft/ft or less Second Zone ground water was inferred a have radially-inward ground ' water flow,towards a ground water depression the area of Flag City Chevron wells MW-6B and MW-9A at a hydraulic gradient of 0 002 ft/ft or less Secondary and Primary Aquifer Zone ground water was inferred to form a southwest-trending trough trending towards a ' significant ground water depression in the area of Three B's Truck Plaza well MW-9E, hydraulic gradients are 0 02 ft/ft or less Due to the low ground water gradient at the site, small variations in ground water measurements or changes ofrecharge/discharge of the local ' ground water could greatly modify the inferred ground water flow direction(Figures 4, 5, 6 and 7) • The average decrease in ground water elevation of approximately 2 11 feet between March ' 2003 and June 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 I • The highest on-site concentrations of dissolved MTBE were detected in the sample collected from First Zone extraction wells EW-4 and. EW-5 at 26 µg/1 (Figure 8) and from Second Zone well MW-8A at 290 µg/1 (Figure 9), lower concentrations of on-site MTBE were detected in water samples from First Zone extraction wells EW-1, EW-7,EW-8,EW-9 and EW-10,and from Second Zone monitoring wells MW-6B and MW-9A,generally,significant MTBE decreases were reported in wells MW-8A, MW-9A, EW-4 and EW-8 a The most intense `First Zone'off-site MTBE-impacted ground water were detected from the in the area of well MW-16 and Three B's Truck Plaza wells MW-4 and MW-8A at concentrations as high as 150 µg/l (Figure 8) a The most intense `Second Zone' off-site MTBE-impacted ground water were detected from the area of well MW-17 at a concentration of 140 µg/1 (Figure 9) • The most intense `Rocky's Upper Zone' off-site MTBE impacted ground water were ' detected from the area of wells MW-11B,MW-15 and MW-18 at concentrations as high as 140 µg/1 (Table 6), significantly Higher concentrations of MTBE were reported from wells MW-15 and MW-18 during the March and Julie 2003 sampling events a Low concentrations of TPH-d have been detected at various wells during previous quarterly monitoring events at Flag City Chevron During June 2003, low concentrations of TPH-d were detected in water samples collected from wells MW-2 and MW-12A, screened within the First Zone aquifer AGE had previously asked McCampbell Analytical 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 Advuneed GeoEnvironmental,Inc