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located above the mined seam, will be dewatered during the course of mining <br />operations. The perched aquifers above the mine are probably limited both in <br />number and in areal extent. There is no documented use of any of these <br />aquifers, nor is there any evidence to suggest that these aquifers supply base <br />flow to any local streams or springs. Therefore, impacts to perched aquifers, <br />and the Menefee formation as a whole, will be minimal. <br />The second ground water system identified near the permit area is the <br />Hay Gulch alluvial aquifer. This aquifer system may he potentially affected <br />by surface runoff from the mine bench or discharge from the sediment pond <br />infiltrating into the alluvial body. This infiltration could cause localized <br />increases in total dissolved solids within the alluvium. The probability of <br />this occurring is minimal. The sediment control system at the King Coal Mine <br />has been designed to minimize impacts to the prevailing hydrologic balance at <br />and near the permit area. All surface runoff from the mine area will flow, <br />via a series of conveyance culverts and ditches, to the sediment ponds, which <br />are located on either side of the combination haul/access road adjacent to the <br />alluvial valley. The sediment ponds, which are adequately sized to contain <br />the runoff from a 10-year, 24-hour storm, will not discharge until a storm <br />event of this magnitude has been exceeded. National King Coal has committed <br />to an extensive water quality sampling plan, should the ponds discharge due to <br />mine portal discharges. The sampling plan should be an effective method of <br />determining the extent, if any, of impacts which are occurring to the alluvial <br />aquifer system. <br />It is thought that, due to the great quantity of water transported within the <br />alluvial aquifer, the effects of surface drainage to the AVF will be <br />immediately mitigated. <br />B. Cumulative Hydrologic Impact Assessment <br />The Division has made an assessment of the probable cumulative hydrologic <br />impacts of anticipated and permitted mining operations within the ground water <br />and surface water study areas. The purpose of the assessment is to determine <br />the cumulative impacts to the hydrologic system from all existing and <br />anticipated coal mining operations within the ground and surface water study <br />areas. <br />The surface water study area is defined as the Hay Gulch drainage basin from <br />Hesperus, Colorado, to its confluence with the La Plata River, near Kline, <br />Colorado. The ground water study area is defined as the Menefee Formation and <br />Hay Gulch alluvial aquifer in the immediate vicinity of the existing and <br />anticipated mining activities. <br />The coal mining operations which are considered in this cumulative assessment <br />include the La Plata No. 1 Mine (permit issuance pending, inactive); King Coal <br />Mine (permit issued, active); and the Blue Flame Coal Mine (permit issuance <br />pending, inactive). <br />-14- <br />