Laserfiche WebLink
potential impacts to flow in the White River will be minimal. <br /> The possibility exists for water to discharge from the portals once the mine <br /> workings have become completely flooded. The portals are up dip in the mine <br /> and drainage will tend to move down the dip of the mine and coal seam, thereby <br /> increasing the time to flood the workings. The permittee has proposed backfilling <br /> of the portals and construction of bulkheads upon closure of the mine, <br /> minimizing the possibility for discharge of water. <br /> A large coal refuse disposal area exists in the northern section of the mine permit <br /> area. Drill hole data indicate that there is no ground water within 44 feet of the <br /> ground surface in the disposal area, and recharge to ground water in the <br /> Mesaverde Group is minimal. Infiltration of water through the refuse pile will be <br /> minimized by covering the compacted refuse with 30 to 48 inches of the best <br /> available non-toxic material. Impacts to the ground water system are not <br /> expected to be significant due to the relatively impermeable nature of the refuse <br /> and the low water table. <br /> The development and reclamation of the cuts and fills in the portal areas should <br /> have no impact on the bedrock aquifer system. Recharge of the aquifers does not <br /> occur in these areas due to surface water control systems, so possible degradation <br /> of the ground water by infiltrating waters is unlikely. The fill material itself is <br /> generally of suitable quality as a topsoil substitute except for SAR values which <br /> are up to twice as high as defined in the Wyoming Guidelines for suitability. As <br /> water flows through the fill, total dissolved solids may increase due to soluble <br /> salts; however, this occurs naturally within the existing ground water region. The <br /> fill does not contain materials that create a toxic leachate. Water that infiltrates <br /> the fill may reach Scullion Gulch. However, due to the small area of disturbance <br /> relative to the entire drainage basin for Scullion Gulch, this will be a very minor <br /> contribution of flow in the creek. <br /> The permittee obtains part of the required water supply from the White River <br /> Lagoon, as discussed earlier. Approximately 552 ac. ft. per year(601 gpm is <br /> pumped from the lagoon to a head tank in the D-Portal area. This is less than one <br /> percent of the low flow of the White River. Therefore, impacts are not <br /> significant. <br /> Recharge of the ground water is not expected to be impacted significantly by the <br /> proposed mining operation. The majority of the recharge area for the Mesaverde <br /> aquifers is outside of the mine plan area. It is possible that surface fracturing <br /> resulting from subsidence could increase recharge to the Upper Williams Fork. <br /> However, these cracks, if they occur, are expected to exist for only a short period <br /> of time before naturally sealing. <br /> Recharge of the White River alluvium by bedrock aquifers is not considered to <br /> be significant because of the low transmissivities of the aquifers. The permittee <br /> xxxi <br />