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Y ' 02 March 2005 AGE-NC Project No 97-0333 Page 6of10 34 ' QUARTERLY GROUND WATER MONITORING RESULTS Ground water elevation, flow direction, and gradient were determined from field data collected on 30 December 2004, the contaminant impact to ground water was quantified by laboratory analysis ! of ground water samples i3 4 1 Ground Water Elevation and Gradient ' Depths to ground water were measured between 20 90 feet(MW-8A)and 22 48 feet(MW-6)below the tops of the well casings, ground water elevations were calculated to be between 10 38 feet (MW-1'1B-F)and 1199 feet(MW-8A) above mean sea level(MSL, see Table 4) Based on current and previous monitoring data collected from wells MW-1 through MW-13, ground water elevation at the site generally increased'an average 5 09 feet between the October and December 2004 ground water monitoring events Ground'water elevation data collected from multi-level wells MW-11, MW-12, and MW-13 on • 130 December 2004 is depicted on cross section F-F' (Figure 3) The vertical gradients between adjacent screen intervals are depicted on cross section F-F',the vertical gradient was calculated by determining the difference between adjacent screen interval ground water elevations (dh) and dividing by the difference of the screen interval midpoints(dl) Generally,a pronounced downward gradient,was observed between the First Zone and the upper Second Zone at all three well locations, ` near neutral,gradients were observed at all other locations The 30 December 2004 ground water elevation data collected from the Rainwater Car Wash site was plotted for the informal First Zone, Second Zone, Third Zone, and Primary Aquifer Zone hydrogeologic flow units, and is depicted on Figures 4 through 7 ' 3 4 1 1 First Zone Aquifer Ground water elevation data collected in the First Zone Aquifer(15 to 47 feet below surface grade ' [bsg]) inferred an inward ground water flow,toward a ground water depression in the area of wells EW-1, MW-6, and MW-7A(Figure 4) under a hydraulic gradient of approximately 0 005 foot/foot (ft/ft) On the southeast-half of the site, ground water was inferred to be flowing toward the northwest under a gradient of approximately 0 02 ft/ft Advanced CeoEnvironmental,Inc