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• EXHIBIT 33 <br />MINE WATER CONTROL PLAN <br />Ground water intercepted during mining will be handled to facilitate <br />operations, control water quality and efficiently discharge excess water to <br />receiving streams. A plan for dewatering the underground mine has been <br />developed for engineering and environmental facility designs. <br />SOURCES OF INFLOW <br />Coal is extracted from the Wadge Seam, which constitutes the base of the <br />overburden aquifer. The overburden is saturated and under artesian pressure <br />in the Twentymile Park Basin. Ground water will enter the mine from gravity <br />drainage of the overburden to the roof, face and outer ribs, primarily via <br />joints and fractures. In addition, major points/occurrences of inflow will be <br />fault crossings, particularly faults which provide hydraulic connection with <br />overlying and underlying aquifers. The overlying Twentymile Sandstone is <br />separated from the Wadge overburden by approximately 700 feet of impermeable <br />• shale. The underlying aquifers, particularly the Trout Creek Sandstone, have <br />sufficient artesian pressure to cause water to flow upward into the mine from <br />the floor. The Trout Creek Sandstone underlies the Wadge Seam and is in <br />hydraulic connection with the overburden aquifer where fault zones exist. <br />When mining intercepts such fault zones, discharge rates at the fault <br />crossings will be high at first, but will decline and stabilize as drawdown <br />reaches steady-state. At the fault crossings, water will enter the mine from <br />the roof, ribs and floor of the mine at the fault crossings for the duration <br />of the mining operation. <br />WATER INFLOW ESTIMATES <br />A two-dimensional, finite-difference ground water model has been used to <br />determine inflow to the underground mine from the overburden aquifer. <br />Calibration of the GRWATER modeling program (McWhorter and Sunada, 1977) is <br />discussed separately. The GRWATER model requires the time in days when mining <br />begins and ends in each grid, and calculates vertical, lateral and constant <br />inflow to each grid in an iterative analysis based on Darcy's Law. The <br />• results of model runs over 32 years of mining are shown on Table A, GRWATER <br />Model Output. Because the model is two-dimensional, the output does not <br />Ex. 33-1 <br />Revised 7/7/86 <br />