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24 August 2005 <br /> AGE-NC Project No. 97-0301 <br /> ' Page 5 of 6 <br /> • The average ground water elevation at the site on 13 June 2005 was 18.82 feet below MSL. <br /> Generally,'ground water elevation at the site increased an average 0.42 feet between the <br /> March 2005 and the June 2005 ground water monitoring events. The increase in ground <br /> water elevation is probably due to seasonal fluctuation. <br /> t • Generali a stee downward vertical adient was observed from wells MW-8,MW-9,and <br /> Y, P �' <br /> MW-12 and between the Second Water Zone, Third Water Zone, and Fourth Water Zone; <br /> near neutral to upward vertical gradients were observed between the First Water Zone and <br /> the Second Water Zone in the southern portion of the site (Figure 3). <br /> ' Analysis of ground water samples collected from MW-1 and MW-7 suggest the dissolved <br /> plume is comprised of TPH-g, BTEX, and 1,2-DCA. The core of the First Water Zone <br /> dissolved gasoline plume appears to be currently distributed near the location of wells <br /> u� MW-7 and MW-1- and contained within network of wells consisting of MW-2, MW-3, <br /> MW-4, MW-6, -9, MW-l0'A\, MW-1lA, and MW-12A (Figure 5). <br /> • Substantial concentrations of c"1'issolved TPH-d and TPH-k have previously been detected in <br /> t water samples collected from wells MW-1 and MW-7, indicating a limited distribution of <br /> TPH-d and TPH-k in the area assessed. However, for the eighth consecutive quarterly <br /> ' monitoring event,TPH-d,TPH-k,and TPH-mo were not detected from any of the twenty-six <br /> water samples analyzed. <br /> • BTEX concentrations in ground water samples MW-1 and MW-7 were above the Maximum <br /> ' Contaminant Levels(MCL's)in drinking water.Benzene concentrations from wells MW-8A <br /> and MW-9A were also above the MCL's. W, <br /> ' Very low concentrations of MTB?9d TAME were detected at wells MW-1 and MW-7, <br /> indicating that there is only a minor impact of these components. <br /> ' 1,2-DCA was detected for the second consecutive time since sampling began in wells <br /> MW-10A, MW-10B and MW,;lOC. 1,2-DCA was not detected this quarter in the sample <br /> collected from well MW-12C. 1,2-DCA-impacted groundwater extends to 95-100 feet bsg <br /> t in the area of well MW-10"However, dissolved 1,2-DCA does not appear to extend <br /> vertically beyond 100 feet bsg. The core of the First Water Zone dissolved 1,2-DCA plume <br /> + appears to be currently distributed near the location of wells MW-7 and MW-9A and <br /> 1 extending west to MW-1 and east to well MW-I OA;and contained within network of wells <br /> consisting of MW-2,MW-3,MW-4,MW-6,MW-11A,and MW-12A(Figure 6).The First <br /> Water Zone dissolved 1,2-DCA plume is not laterally assessed toward the southeast beyond <br /> twell MW-9A and toward the northeast beyond well MW-10A. <br /> • 1,2-DCA concentrations in ground water samples MW-1, MW-7, MW-9A, MW-10A, <br /> tMW-1 OB and MW-IOC were detected above the MCL's in drinking water. <br /> Advanced GeaEnvironmental,Inc. <br /> I <br />