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• All runoff from the disturbed area at the mine site will be routed through the two <br />sediment ponds. Effects of mining on this water will involve changes in the <br />magnitude and duration of runoff and changes in water quality. <br />The effects on water quantity are expected to be minimal. An increase in <br />imperviousness due to the construction or roads and buildings can be expected to <br />cause an increase in tunoff amounts. The rate of runoff will increase over natural <br />conditions because of the increased efficiency of conveyance channels. However, <br />these effects are moderated by the detention of runoff in the pond and subsequent <br />evaporation of pond water. In general, only slight changes in the hydrologic balance <br />of surface water are expected due to the underground mining operations proposed <br />at the King Coal Mine. <br />Changes th water quality can be expected to occur as a result of mining. An <br />increase in erosion rates aze expected from the disturbance of soils and vegetation, <br />however, these are compensated by deposition of sediment in the sediment pond. <br />An increase in total dissolved solids (TDS) may occur from well water pumped and <br />used for dust suppression and other operational use. Evaporation of water standing <br />in the pond may also cause an increase in TDS, although. the increase above <br />background concentrations (1500-2000 mg/1) is not expected to be large. <br />• The Division has detemtined that probable hydrologic effects on surface water <br />identified above will not preclude use of the water below the point of discharge from <br />the mine. This conclusion is based on the small and infrequent flows relative to the <br />lazge amount of dilution available in receiving waters. The quality of surface water <br />is limited on site and the treatment systems should act to mitigate any adverse effects <br />on surface water. <br />Ground Water Effects <br />There are two potentially impacted ground water systems within and adjacent to the <br />King Coal operation: the Menefee Formation and the Hay Gulch alluvial system. <br />The probable hydrologic consequences of mining to the Menefee Formation are <br />negligible. The Menefee is essentially dry at the King Coal Mine. This has been <br />historically documented during past operations. Additionally, a drilling program <br />initiated in 1980 for the proposed Shalako Mine (about 1 mile northeast of the King <br />Coal Mine in Hay Gulch) confirmed that the coal and overburden are essentially free <br />of water. Perched aquifers, which may be located above the mined seam, will be <br />dewatered during the course of mining operations . The perched aquifers above the <br />mine are probably limited both in number and in areal extent. There is no <br />documented use of any of these aquifers, nor is there any evidence to suggest that <br />• these aquifers supply base flow to any local steams or springs. Therefore, impacts <br />to perched aquifers, and the Menefee Formation as a whole, will be minimal. <br />17 <br />