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3.0 MODEL OUTPUT <br />Model output was contoured and is shown in Sheets 1-7. Proposed pumping <br />and reclamation modeled water table elevations were subtracted from existing <br />water table model output to show relative drawdown due to pumping and <br />reclamation conditions (Sheets 3,5, & 7). <br />Due to the large number of grid cells, MODFLOW model input and output files <br />are too cumbersome to be printed out and included with this report. These input <br />and output files and the Argus One MODFLOW GUI versions of the models are <br />saved onto a data CD which is included with this report. <br />3.1. EXISTING WATER TABLE <br />The first model run was developed to simulate existing water table elevations. <br />The model output for the existing Water Table simulation following calibration is <br />shown in Sheet -1. <br />3.2. DEWATERING WEST PIT (460 GPM) <br />Sheet 2 shows the ground water levels predicted by the model while dewatering <br />the West Pit. During this simulation the pit produces 460 gpm which is pumped to <br />the infiltration pond; ground water is then pumped from the two wells adjacent to <br />the infiltration pond at a total rate of 200 gpm; the well water is conveyed via <br />irrigation pipe to the Big Thompson Lakes to keep them from drawing down due <br />to pit dewatering. During this simulation the following rates were sufficient to <br />keep the lakes full (i.e. no change from base level water surface elevation): <br />• Lake 1 — 0 gpm; <br />• Lake 2 — O gpm; <br />• Lake 3 — 10 gpm; <br />• Lake 4 — 20 gpm; <br />• Total of 30 gpm. <br />These simulated water table elevations were subtracted from the simulated <br />existing water table elevations to determine the drawdown. The drawdown <br />values are plotted as contours shown in Sheet -3. <br />3.2.1. Water Surface Elevations <br />Table 3 summarizes the changes in water surface elevations in the lakes during <br />each progressive stress scenario. Of particular interest are the water levels in <br />lakes 1 through 4 which are the Big Thompson Ponds. Model scenario 1 is the <br />simulation of only dewatering the west pit at 460 gpm. In this simulation lake 5 <br />drops 1.9 feet and lake 4 drops 0.5 feet. <br />Flying W Pit <br />Groundwater Modeling Report Revised June 28, 2005 <br />9of13 <br />