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<br />-26- <br />However, given the present rate of mine inflows, the extensive area to be <br />undermined, and the steeply dipping strata within the area, there is only <br />a low potential for the North Thompson Creek No. 1 and No: 3 Hines to <br />discharge acidic or toxic waters to surface streams. <br />Ground water quality in overlying and underlying aquifers may become <br />degraded upon closure of the mine through vertical communication of. <br />strata caused by faults and fractures. The overlying and underlying <br />aquifers are currently not put to beneficial use and the potential for <br />their future utilization is limited by the difficulty in developing water <br />wells 1n these strata. Owing to these factors, the mines will not <br />materially damage the ground water of any water user through vertical <br />migration of degraded mine waters. <br />The coal processing wastes from the wash plant are combustible and <br />acid-forming and potentially toxic. Owtng,to the nature of these coal <br />processing wastes, the applicant is presently constructiny the coal <br />refuse pile to minimize exposure of wastes to air, surFace water, and <br />ground water. The exposure to these wastes is being limited through <br />1) compacting the waste in two-foot lifts, 2) conrnitting to cover the <br />refuse pile with four feet of non-toxic cover, 3) providing permanent <br />surface diversion of surface runoff from undisturbed areas around the <br />pile, 4) collecting and treating all surface drainage flowing over the <br />pile during construction and reclamation, and 5) benching and sloping the <br />pile such that erosion and infiltration of the final pile 1s minimized. <br />The refuse pile is being Constructed on top of thin alluvium of the old <br />stream channel which will supply drainage of ground water beneath the <br />pile. The pile 15 being constructed over the relatively impermeable <br />Mancos Shale Formation and not over any aquifer. Therefore, the impacts <br />of the refuse pile on the quality of ground water should be minimized and <br />should not cause material damage to any ground water currently in use. <br />Waste water from the coal wash plant is currently recycled back into the <br />coal washing facility after fines have been settled out in upper and <br />lower settling ponds. This water recycling system tends to increase the <br />total dissolved solids in the water through exposure of the water to <br />fines and through evaporation. The ponds used in this water recycling <br />system are unlined and are located on or are hydrologically adjacent to <br />the North Thompson Creek alluvium. Thus, these ponds pose a potential <br />for the degradation of the alluvial water quality directly and, <br />indirectly, the surface water quality of North Thompson Creek. <br />Alluvial monitoring well D-lA below the refuse pile has a water chemistry , <br />markedly different from that in North Thompson Creek. The high levels of <br />both total dissolved solids, between 3498 and 3982 mg/l, and sulfates, <br />between 1900 and 2700 mg/l, Indicate the refuse pile sediment pond and <br />unlined settling ponds may in part impacting the quality of alluvial <br />