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district in 1996. With the approval of TR -68, the Deserado Mine is approved for <br />dewatering within the workings of the "B" seam. Excess water entering the mine <br />workings is pumped to the surface where it is allowed to settle out or discharge <br />through a series of sediment ponds and artificial wetlands know as the "B" seam <br />dewatering pond system. To the date of this findings document, no water has <br />discharged from the "B" seam dewatering pond system. Water pumped to the <br />surface is allowed to percolate through the soil of the ponds and artificial <br />wetlands remaining in the same hydrologic system. Groundwater in the area is <br />tributary to the White River. <br />Since January, 1997, prep plant thickener water has been disposed underground <br />within down -dip, sealed sections of the "D" seam mine. No discernible effects <br />on surface water or ground water quality are anticipated, although water levels <br />will be reestablished sooner than would otherwise have been the case. <br />Subsidence effects include fracturing of the material overlying the coal for a <br />vertical distance of 30 to 40 feet due to caving of the roof material and surface <br />subsidence and possible development of tension cracks on the surface due to <br />differential settling. Observed ground water inflows during mining have been <br />approximately 50 gpm. In fractured areas, increased flows of 100 to 300 gpm <br />may be encountered for a short period of time. These flows will diminish as <br />equilibrium is reestablished. Due to the low transmissivities of the aquifers, if <br />caving should create a hydraulic connection from the mine to an aquifer within <br />30 to 40 feet of the coal, the additional inflow will be minimal. It is not probable <br />that fracturing from the mine to the surface will occur as a result of subsidence <br />and cause the flow of surface water to the mine. <br />Subsequent to completion of mining, the ground water will slowly reestablish its <br />pre- mining water levels. Due to the caving of the roof materials into the mine, an <br />area of increased permeability will exist within the mine that will act as a "sump <br />area" until equilibrium is established. However, due to the small quantity of <br />water in the aquifers being discharged to the White River and its tributaries, the <br />lack of ground water usage in the area, and the poor quality of ground water, <br />potential impacts to flow in the White River will be minimal. <br />The possibility exists for water to discharge from the portals once the mine <br />workings have become completely flooded. The portals are updip in the mine <br />and drainage will tend to move down the dip of the mine and coal seam, thereby <br />increasing the time to flood the workings. The permittee has proposed backfilling <br />of the portals and construction of bulkheads upon closure of the mine, <br />minimizing the possibility for discharge of water. <br />A large coal refuse disposal area exists in the northern section of the mine permit <br />area. Drill hole data indicate that there is no ground water within 44 feet of the <br />ground surface in the disposal area, and recharge to ground water in the <br />Mesaverde Group is minimal. Infiltration of water through the refuse pile will be <br />31 <br />