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09 May 2003 AGE-NC Project No 96-0232 Page 12 of 16 The results from the ground water monitoring and sampling events performed in December 2002 are as follows Generally, depth to ground water at the site vaned between 10 and 14 feet bsg,ground water ' elevations range between 198 feet (MW-10A) and 2 88 feet (MW-10E) below mean sea level ' First Zone ground water was inferred to be radially inward towards a ground water depression in the area of Flag City Chevron wells MW-1, MW-2, MW-4 and MW-5 at a gradient of 0 003 ft/ft or less (Figure 4) Second Zone ground water was inferred to be ' radially-inward flow towards the area of Flag City Chevron wells MW-6B, MW-8A, MW-9A and MW-10B at a hydraulic gradient of 0 001 ft/ft or less(Figure 5) Secondary and Primary Aquifer Zone ground water inferred a east-southeast ground water flow direction ' (Figures 6 and 7), ground water gradients were approximately 0 001 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 • The average increase in ground water elevation of approximately 168 feet between December 2002 and March 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 l tThe highest on-site concentrations of dissolved MTBE were detected in the sample collected from First Zone extraction well EW-8 at 96 µg/1 (Figure 8) and from Second Zone well MW-8A at 900 µg/1 (Figure 9), lower concentrations of on-site MTBE were detected in water samples from First Zone extraction wells EW-1,EW-4,EW-7,EW-9 and EW-10,and from Second Zone monitoring wells MW-6B and MW-9A, generally, significant MTBE ' increases were reported in wells MW-8A, EW-4 and EW-8 • 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 91 µg/l (Figure 8) • The most intense `Second Zone' off-site MTBE-impacted ground water were detected from the area of well MW-17 at a concentration of 220 µg/l (Figure 9) a 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 200 µg/l (Table 6), significant increasing MTBE concentrations were reported from wells MW-11B and MW-15 between the December 2002 and March 2003 sampling events • Low concentrations of TPH-d have been detected at various wells during previous quarterly monitoring events at Flag City Chevron During March 2003,a low concentration of TPH-d was detected in the ground water sample from well MW-12A,screened within the First Zone Advanced GeaEnvimnmental,Inc I