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2. Impact of the Mining Operation on Ground Water <br /> The impact of the proposed mine on ground water will be very localized, with <br /> no significant impact expected on a regional basis. This is due primarily to the <br /> small quantity of ground water in the area. <br /> Water encountered within the mine will be utilized underground for dust <br /> suppression. As a result, only those inflows that temporarily exceed storage <br /> capacities and mine use requirements would potentially be discharged to the <br /> surface and lost from the ground water system. Pumping from approved <br /> minewater discharge locations ceased upon sealing of the "D" seam northern <br /> longwall district in 1996. Although dewatering could be accomplished by <br /> installation of a submersible pump at Site SDH-2, such dewatering is not <br /> currently anticipated. If minewater discharge were to occur, there would be no <br /> loss to the hydrologic system, since groundwater in the area is tributary to the <br /> 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 /> 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 <br /> probable that fracturing from the mine to the surface will occur as a result of <br /> subsidence and cause the flow of surface water to the mine. <br /> Subsequent to completion of mining, the ground water will slowly reestablish <br /> its pre-mining water levels. Due to the caving of the roof materials into the <br /> mine, an area of increased permeability will exist within the mine that will act <br /> as a "sump area" until equilibrium is established. However, due to the small <br /> quantity of water in the aquifers being discharged to the White River and its <br /> tributaries, the lack of ground water usage in the area, and the poor quality of <br /> ground water, potential impacts to flow in the White River will be very minor. <br /> It could be possible 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, <br /> 26 <br />