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' 15 September 2005 AGE-NC Project No 96-0229 ' Page 3 of 6 Ethylene dibromide (EDB), 1,2-dichloroethane (1,2-DCA), tert-butyl alcohol (TBA), di- Isopropyl ether(DIPE), ethyl tert-butyl ether(ETBE),tert-amyl methyl ether(TAME), and methyl tert-buyl ether (MTBE) by EPA Method 8260B r 3.0. FINDINGS IGround water monitoring field data was utilized to determineg round water flow direction and gradient, petroleum hydrocarbon-impact to ground water was quantified by laboratory analysis of samples 3 1 GROUND WATER ELEVATION AND GRADIENT The depth to ground water measurements on 21 June 2005 ranged between 29 46 feet(MW-5) and 31 98 feet(MW-10A)below the tops of well casings Generally,the average groundwater depth at the site was equal to 31 19 feet, ground water levels generally increased an average of 0 84 feet • between the April 2005 and the June 2005 ground water monitoring events Ground water elevations were calculated by subtracting the measured depth to ground water from I the surveyed casing elevations The ground water elevations averaged 18 21 feet below mean sea level (MSL)at the site,with a range of between 16 99 feet(MW-5)and 18 97 feet(MW-19C)below MSL Ground water elevation data collected from wells MW-1, MW-2, MW-3, MW-13 (A-D), MW-14 (A-D), and MW-16 (A-E) on 21 June 2005 is depicted on cross section B-B' (Figure 3) By determining the difference between ground water elevations (dh) and dividing by the difference of the screen interval midpoints (dl), the vertical gradient between adjacent screen intervals was calculated Generally,nearly flat vertical gradients and mostly slightly downward vertical gradients were observed between the Second Water Zane,Second Confining Unit and Third Water Zone screen intervals of all the above wells(Figure 3),however,slight upward vertical gradients were generally observed in the upper zone of the First Confining Unit Ground water elevations were plotted on scaled site plans for the informal First Water Zone (between 15 and 45 feet, Figure 4) and Second Water Zone (between 70 and 95 feet, Figure 5) 3 1 1 First Water Zone Ground water elevation data collected in the First Water Zone(15 to 45 feet bsg)at the site inferred Advanced GeoEnvironmental,Inc 1