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19 July 2000 AGE-NC Project No 96-0232 Page 18 of 29 7 2 2 Relative Ground Water Elevation and Gradient Ground water elevation at the site decreased approximately one foot between the April 2000 and the May 2000 ground water monitoring events Ground water elevation and gradient is presented in Section 6 2 Depth to ground water, ground water elevation, and well screen intervals are summarized in Table 5 The ground water elevation data collected on 25 and 26 May 2000 from the Flag City Chevron site is depicted in Figure 7 7 2 3 Laboratory Results of Ground Water Samples During the May 2000 sampling event, TPH-g was detected in the sample collected from MW-12A (First Zone) at a concentration of 120µg/l TPH-d was detected at concentrations as high as 480 4g/1 in samples from MWA2A and as high as 230 µg11 in the sample collected from MWA 3B (Second Zone) Toluene was detected at a concentration of 25 µg/1 in the sample collected from MW-12A Benzene was detected at a concentration of 16 µglI in the sample collected from MW-13A • MTBE was detected in ground water samples collected from the wells at concentrations as high as 5,500µg11 from MW-1 (First Zone), MTBE was detected in the Rocky's Restaurant domestic water well sample (RDW-1) at a concentration of 16 µg11 TAME was detected at a concentrations of 15µg11 in the sample from MW-13A TBA was detected at a concentration of 5 2 µg/1 in the sample collected from MW-l0E Ethanol was detected in samples collected from monitoring wells at concentrations as high as 250,000 µg/l Ethanol was detected in water samples collected from the Rocky's Restaurant domestic water well (RDW-1), Three B's Truck Plaza domestic drinking water well (DW-1) at concentrations of 550 µg/1 and 1,600 µg/l, respectively As noted in the 19 June 2000 - Problem Assessment Repor t, the high concentrations of ethanol are believed to be a contaminant introduced by coated bentonite pellets during construction of MW-8 through MW-13 and the ethanol should disperse through time Analytical results of the ground water samples are summarized in Tables 3 and 4 The laboratory reports and chain-of-custody forms are presented in Appendix G Dissolved TPH-g data collected on 25, 26 May 2000 from the Flag City Chevron site is contoured in Figure 12 (First Zone) Dissolved TPH-d data collected on 25, 26 May 2000 from the Flag City Chevron site is contoured in Figures 13 and 14 (First Zone and Second Zone) Dissolved MTBE data collected on 25, 26 May 2000 from the Flag City Chevron site is contoured in Figure 15 (First Zone) and Figure 16 (Second Zone and Rocky's Upper Zone) Advanced CeoEn%ironmental,Inc