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1 w04 January 2006 . AGE-NC Project No. 97-0301 ' Page 3 of 6 TPH-d, TPH-k, and TPH-mo, respectively) by EPA Method 8015M; and • Benzene,toluene, ethylbenzene,and xylenes (BTEX), methyl tertiary-butyl ether(MTBE), 1,2-Dichloroethane(1,2-DCA),ethylene dibromide(EBD),di-isopropyl ether(DIPE),ethyl tert-butyl ether(ETBE),tert-amyl methyl ether(TAME),and tertiary butanol(TBA)by EPA Method 8260B. 3.0. FINDINGS Ground water elevation, flow direction, and gradient were determined from field data collected on 22 September 2005.The contaminant impact to ground water was quantified by the ground water samples collected on 23 September 2005. 3.1. GROUND WATER ELEVATION AND GRADIENT The depth to ground water measurements at wells MW-1,MW-4 and MW-6 through MW-12 varied between 33.52 feet (MW-9B) and 3 5.3 8 feet(MW-8C)below the tops of the well casings; ground water elevations were calculated to be between 21.38 feet(MW-8A) and 22.61 feet (MW-I IDf below mean sea level(MSL). 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. ' Ground water elevation data collected on 22 September 2005 from wells MW-8 (A-C), MW-9 • (A-D), and MW-12 (A-D) is depicted on cross section D-D' (Figure 3). By determining the difference between groundwater elevations(dh)and dividing by the difference of the screen interval ' midpoints (A), the vertical gradient between adjacent screen intervals was calculated. Generally, moderately steep to steep downward vertical gradients were observed between the Second, Third, ' and Fourth Water Zones; while 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). The ground water elevations at wells MW-1,MW-4 and MW-6 through MW=12 were calculated by subtracting the measured depth to ground water from the surveyed casing elevation. The September 2005 ground water elevation data collected from wells MW-1, MW-4, MW-6 and MW-7 were plotted for the First Water Zone (Figure 4) as defined in AGE's CPT Site .Investigation - Third Quarter 2001 (dated 25 October 2001). Generally,the net ground water flow direction was toward the north-northeast at an approximate hydraulic gradient of 0.003 foot/foot(ft/ft). The local ground ' water flow direction at the former UST location was generally northeast, in accordance with the . former flow directions. Advanced GeoEnvironmental,Inc. 1 '