_GENERAL DOCUMENTS - C1981017 (283)

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-35- The mining activities will not have an adverse effect on the quantity of surface water within or outside the permit area. Mid-Continent has a water right to withdraw water from Coal Creek up to 7.48 cfs. This is the only withdrawal of water from within the permit area. Through Pumping water from the mines, the flow in Coal Creek is increased on the average by 3.75 cfs, thus the net effect of withdrawal is to deplete 3.73 cfs, which is approximately one percent of the average low flow in the Crystal River. Most of the water will be withdrawn from the Coal Creek drainage during the summer months for dust suppression. Since the flow in the summer months is greater than average, the Crystal River will be depleted by less than one percent during the summer. Therefore, the proposed operation will not significantly affect the quantity of surface Water in the hydrologic regime outside the permit area. Probable Hydrologic Consequences - Ground Water The impacts incurred by ground water resources as a result of the proposed mining operations are expected to be insignificant. However, several slight changes in the hydrologic system are expected. First, the coal seams and immediately adjacent strata will be dewatered in the vicinity of the mining operations. Second, the water quality of alluvial ground water located adjacent to the several mine-waste piles may become slightly degraded. * Third, slight mixing of ground waters from previously unconnected aquifers may occur as a result of the proposed rock tunnel . None of these potential impacts are expected to cause material damage to ground waters in the Coal Basin area. Each is discussed in greater detail below. As a part of normal operating procedures, the applicant must handle water that develops in the mine workings. This water is handled in one of the following ways: I . it will be used during the mining process, 2. it will be allowed to migrate downdip either in the coal or the underlying sandstone units, or 3. it will be pumped from the mine at a rate of 40 to 300 gpm. Based on mine pump records (see Table III-E-2 of the permit application) , the amount of water pumped from the workings increases during the spring and significantly decreases during the late fall and winter. This mine dewatering process should lower water levels in the two coal seams being mined and the Rollins and Middle sandstones. Based on the erected low transmissivities_ it is -unlik lv that the drawdowns would extend more than a mile from the edge Of therja@—*erk4ngs. Since the mine is located near an outcrop area, it is unlikely that these strata are fully saturated anyway. The low pumping rates required to dewater the mine workings is evidence of this. Also, the fact that the pumoing rates dramatically increase during the spring season indicates variable degrees of aquifer saturation throughout a given year.