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12 December 2005 <br /> {. AGE-NC Project No 97-0333 <br /> ' Page 6 of 11 <br /> ' 3 4 QUARTERLY GROUND WATER MONITORING RESULTS <br /> Ground water elevation, flow direction; and gradient were determined from field data collected on <br /> 05 July 2005, the contaminant impact to ground water was quantified by laboratory analysis of <br /> ' ground water samples <br /> 3 4 1 Ground Water Elevation and Gradient <br /> ' Depths to ground water were measured between 18 56 feet(MW-5)and 23 61 feet(MW-7D)below <br /> the tops of the well casings, ground water elevations were calculated to be between 9 22 feet <br /> (MW-11F) and 13 34feet (MW-10A) above mean sea level (MSL, see Table 4) Based on current <br /> and previous monitoring data collected from wells MW-1 through MW-13, ground water elevation <br /> at the site generally decreased an average 3 33 feet between the March 2005 and the July 2005 <br /> ground water monitoring events <br /> Ground water elevation data collected from multi-level wells MW-11, MW-12, and MW-13 on <br /> ' 05 July 2005 is depicted on cross section F-F'(Figure 3) The vertical gradients between adjacent <br /> screen intervals are depicted on cross section F-F', the vertical gradient was calculated by <br /> determining the difference between adjacent screen interval ground water elevations (dh) and <br /> dividing by the difference of the screen interval midpoints(dl) Generally,a pronounced downward <br /> gradient was observed between the First Zone and the upper Second Zone at all three well locations, <br /> near neutral gradients were observed at all other locations <br /> ' The 05 July 2005 ground water elevation data collected from the Rainwater Car Wash site was <br /> plotted for the informal First Zone, Second Zone, Third Zone, and Primary Aquifer Zone <br /> ' hydrogeologic flow units, and is depicted on Figures 4 through 7 <br /> 3 4 1 1 First Zone <br /> Ground water elevation data collected in the First Zone (15 to 47 feet below surface grade [bsg]) <br /> ' inferred an inward ground water flow,toward a ground water depression in the area of wells EW-1, <br /> MW-6, and MW-7A (Figure 4) under a hydraulic gradient of approximately 0 012 foot/foot (ft/ft) <br /> from the east and west Ground water flow direction on the south-half of the site was inferred to be, <br /> oriented toward the ground water depression under a gradient of approximately 0 008 ft/ft, north of <br /> the site near well MW-12, ground water was inferred to be oriented towards the ground water <br /> ' depression at a gradient of approximately 0 003 ft/ft <br /> • <br /> Advanced GeoEnvironmental,Inc <br />