2008-09-19_GENERAL DOCUMENTS - C1981018

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Water for the Deserado Mine is supplied by the White River. Combined water use and evaporative loss at full production is projected to consume 552 acre-feet per year at a withdrawal rate of .763 cubic feet per second, which translates to less than .02 percent of the White River's average annual flow of 672 cubic feet per second. During low flow conditions of the White River, the withdrawal rate will be 0.31 percent of the available flow. Therefore, the adverse impacts on the flow in the White River as a result of the withdrawal should be minimal. The construction of surface facilities in the permit area will cause temporary increases in the amount of suspended solids in the surface water system. Concentration of elemental constituents such as iron and manganese will also increase. Mitigation of sediment load will be accomplished primarily by sedimentation ponds. Although sediment increases will occur in the early phases of construction, the long-term sediment yield may decrease below the already high natural occurrence of sediment concentrations due to the installation of control measures. Effects on the surface water system from the refuse disposal area should be minimal. Analysis of the waste material does not indicate the presence of toxic or acid-forming characteristics. The waste disposal will be covered with 30 inches of non-toxic, non-combustible material, thereby reducing the infiltration of water into the pile and further reducing the potential for water quality degradation. The size of the non-reclaimed disturbed area at the refuse disposal area will be a maximum of 120 acres at any one time. All runoff from the disturbed area will be routed to properly sized sediment ponds. Subsidence from underground mine workings could potentially impact both Red Wash and Scullion Gulch. The effect on Red Wash is of greatest importance as it drains approximately 122 square miles at the location where undermining will occur. Although predictions indicate that maximum vertical subsidence could approach six feet, large crevasses or collapse of the surface should not occur due to the fact that there is approximately 600 to 1200 feet of overburden material above the coal seam in that area. Furthermore, the swelling of shale and overburden from the caved roof should effectively fill the open mine cavity. An ongoing monitoring program was implemented to detect subsidence on the first longwall panel and first room-and-pillar section to be mined during the initial years of production. The permittee originally predicted that tension cracks from subsidence may develop in formations directly underlying Red Wash and that these cracks may extend upwards for tens of feet. These cracks were predicted to be of limited extent; therefore, a minimal amount of surface water was predicted to be siphoned into the cracks. The permittee predicted that the sediment Deserado Mine 22 September 19, 2008