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-33- The Hawk's Nest Mine may impact the quality of ground water in the permit and adjacent areas. Sediment ponds and benches composed of mine refuse material have been constructed in and on the alluvium of the North Fork of the Gunnison. These structures may affect the quality of ground water in the alluvium. The total dissolved solids (TDS) of surface water contained in sediment ponds will be higher than surface water from undisturbed areas. Since the sediment ponds are unlined and above the level of the river, a portion of the water stored in these ponds will enter the alluvial ground water system by infiltration through the bottom of the ponds. The amount of water entering the alluvial ground water system will depend on the retention time of the water in the sediment ponds. Surface waters which infiltrate coal stockpiles and the surface facilities benches may impact the quality of alluvial yround water. The water which infiltrates these structures will pick up soluble salts as it percolates down to the alluvial water table. These soluble salts will increase the TDS levels in the alluvial ground water. Given the data presently available, the impacts of mining on alluvial ground water quality cannot be quantifiably assessed. However, it is assumed that effects will be localized. Degraded water in the vicinity of the surface facilities would be rapidly diluted due to the volume of water and iransmissivity of the alluvial aquifer. The potential for cumulative effects of all mining in the region on water quality of the North Fork alluvial aquifer is discussed later in this document. The effects of the mining operation on alluvial water quality will be monitored below the load-out sediment pond (see Stipulation IVo. 5 in Section IV "Hydrologic Balance: Ground Water" of this document. The impacts to alluvial yround water quality will be minimal upon reclamation of the mine site. The quality of ground water in the Rollins sandstone will not be affected oy the mining operaton since: 1) there is no hydrologic connection between this aquifer and the mine workings, and 2) there are no surface facilities or stockpiles constructed over the recharge area of this aquifer. The quality of ground water in perched lenticular aquifers below the "E" seam and below the surface facilities may be affected. However, the degradation of the water quality in these aquifers will not impact the use of ground water in the permit and adjacent areas. The quality of water within the mine will be degraded during and after mining. The degraded mine water will not impact ground water in adjacent aquifers or impact surface water after mine closure, since: 1) the coal seams are not aquifers, 2) the mining is downdip and away from the outcrops of the coal, and 3) the mine upon closure will be adequately sealed to prevent diversion of surface waters into the mine and gravity discharge from the mine.