2013-03-07_REVISION - C1981035 (2)

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Cliffhouse. Therefore, if the workings fill with water, and subsidence fractures convey that water to the Cliffhouse Sandstone, then impacts could possibly occur to the water quality in the Cliffhouse Sandstone aquifer down -dip from the workings, if mine water is lower quality than ambient ground water. Significant flow from the workings to the Cliffhouse through subsidence fractures is unlikely, however, because head in the overlying (higher elevation) Cliffhouse would be greater than the head exerted by the mine water. The State Engineer's records show two wells have been completed in the Cliffhouse Sandstone approximately one mile downgradient from the King I Mine workings (the L. Paulek and G. Paulek wells). Menefee Formation Like the Cliffhouse Sandstone, mining impacts to the Menefee Formation are improbable because it is unlikely the workings of the King I and 11 Mines will fill with water. Ground water points of compliance are not warranted for the Hay Gulch alluvium, the Menefee Formation, the Cliffhouse Sandstone, or the Point Lookout Sandstone because, as explained above, the King I and 11 Mines lack the potential to negatively impact these units. Surface Water Effects With the exception of two small area exemptions, all runoff from the disturbed area at the mine site will be routed through sediment ponds. Effects of mining on this water will involve changes in the magnitude and duration of runoff and changes in water quality. The effects on water quantity are expected to be minimal. A decrease in permeability due to the construction or roads and buildings can be expected to cause an increase in runoff amounts. The rate of runoff will increase over natural conditions because of the increased efficiency of conveyance channels. However, these effects are moderated by the detention of runoff in the pond and subsequent evaporation of pond water. In general, only slight changes in the hydrologic balance of surface water are expected due to the underground mining operations proposed at the King I and 11 Mines. Changes in water quality can be expected to occur as a result of mining. Increases in erosion rates are expected from the disturbance of soils and vegetation; however, these are compensated by deposition of sediment in the sediment ponds. An increase in total dissolved solids (TDS) may occur from well water pumped and used for dust suppression and other operational use. Evaporation of water standing in the ponds may also cause an increase in TDS, although the increase above background concentrations (1500 -2000 mg/1) is not expected to be large. The Division has determined that probable hydrologic effects on surface water identified above will not preclude use of the water below the point of discharge from the mine. This conclusion is based on the small and infrequent flows relative to the In