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1 t <br /> 1 <br /> OS September 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 /> 31 March 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 17 34 feet (MW-10A/MW-11A) and 19 23 feet <br /> (MW-7B/MW-7C and MW-71)) below the tops of the well casings, ground water elevations were <br /> calculated to be between 13 59 feet (MW-12F) and 14 55 feet (MW-10A) above mean sea level <br /> ' (MSL, see Table 4) Based on current and previous monitoring data collected from wells MW-1 <br /> through MW-13,ground water elevation at the site generally increased an average 3 23 feet between <br /> the December 2004 and the March 2005 ground water monitoring events <br /> ' Ground water elevation data collected from multi-level wells MW-11, MW-12, and MW-13 on <br /> . 31 March 2005 1s 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 31 March 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 /> Ground water flow direction on the south-half of the site was inferred to be oriented toward the <br /> ground water depression under a gradient of approximately 0 003 ft/ft, north of the site near well <br /> MW-12,ground water was inferred to be oriented towards the ground water depression at a gradient <br /> of approximately 0 001 ft/ft <br /> 1 Advanced GeoEnvnronmental,Inc <br />