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i j 04 January 2006 AGE-NC Project No. 97-0301 Page 5 of 6 modify ground water flow direction. • The average ground water elevation at the site on 22 September 2005 was 21.94 feet below MSL. Generally, ground water elevation at the site decreased an average 3.12 feet between the June 2005 and the September 2005 ground water monitoring events. The decrease in ground water elevation is probably due to seasonal fluctuation. • Generally,a steep downward vertical gradient was observed from wells MW-8,MW-9,and MW-12 and between the Second Water Zone, Third Water Zone, and Fourth Water Zone; upward vertical gradients were observed between the First Water Zone and the Second Water Zone in the northern and southern portions of the site(Figure 3). • Analysis of ground water samples collected from MW-1 and MW-7 suggest the dissolved plume is comprised of TPH-g, BTEX, and 1,2-DCA. The core of the First Water Zone dissolved gasoline plume appears to be currently distributed near the location of wells MW-1 and MW-7; and contained within network of wells consisting of MW-2, MW-3, MW-4, MW-6, MW-9, MW-10A,MW-11A,and MW-12A(Figure 5). • Substantial concentrations of dissolved TPH-d and TPH-k have previously been detected in water samples collected from wells MW-1 and MW-7, indicating a limited distribution of TPH-d and TPH-k in the area assessed.For the ninth consecutive quarterly monitoring event, TPH-k,and TPH-mo were not detected from any of the twenty-three water samples analyzed. However, TPH-d was detected this quarter, for the first time in eight sampling events, in samples from wells MW-1 and MW-7 at concentrations of 9,200 µg11 and 29,000 µg11, respectively. • BTEX concentrations in ground water samples MW-1 and MW-7 were above the Maximum . Contaminant Levels(MCL's)in drinking water.Benzene concentrations from wells MW-4, � MW-8A and MW-8B were also above the MCL's. • Low concentrations of MTBE and TAME were detected at wells MW-1 and MW-7, indicating that there is only a minor impact of these components. • 1,2-DCA was not detected this quarter in the sample collected from wells MW-10,MW-11 and MW-12. 1,2-DCA does not appear to extend vertically beyond 40 feet bsg.The core of the First Water Zone dissolved 1,2-DCA plume appears to be currently distributed near the location of wells MW-7 and MW-9A and extending west to MW-1; and contained within network of wells consisting of MW-2, MW-3, MW-4, MW-6, MW-10A, MW-11A, and MW-12A (Figure 6). The First Water Zone dissolved 1,2-DCA plume is not laterally assessed toward the southeast beyond well MW-9A. • 1,2-DCA concentrations in groundwater samples MW-1,MW-7,MW-8A and MW-9A were detected above the MCL's in drinking water. _ Advanced GeoEnvironmenW,Inc.