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<br />-za- <br />It is likely that the proposed channel realignment will result in a more <br />desirable hydrologic situation than exists presently. The creation of a <br />stable, non-meandering channel coupled with the isolation of coal waste from <br />the ground water table will result in the reduced potential for degradation of <br />water quality. <br />WFC proposes to relocate the active refuse disposal site from the floodplain <br />of the Middle Fork of the Purgatoire River to a small watershed across the <br />valley for the existing New Elk mine. This refuse site has been designed with <br />a sediment pond to control all disturbed drainage. The pond has been designed <br />to allow for an average detention time of 24 hours for storm or snowmelt <br />waters. This detention time should decrease the level of suspended solids in <br />the effluent to equal to or below the baseline level of the receiving stream. <br />The dewatering devices on the pond are designed so that the pond has limited <br />volume to store water. Therefore, the quantity of water available to the <br />surface water system will not be significantly impacted. <br />Infiltration of surface water through the refuse pile is expected to be <br />minimal due to the compaction of the refuse mater~.al. Any water leaching <br />through the pile will have elevated levels of dissolved solids and sodium. <br />Much of this water will be retained in the sediment pond until evaporation <br />occurs. Impacts of these impounded waters during storm event discharge will <br />be minimized by mixing with the storm waters. <br />After final reclamation of the refuse pile, the sediment pond will be <br />removed. At this time, suspended solids should return to baseline levels but <br />leachate water will drain directly into the surface water system carrying <br />elevated levels of sodium and dissolved solids. As infiltration through the <br />refuse pile is expected to be minimal, the long term impacts due to leaching <br />should be insignificant. <br />After the cessation of mining operations, mine water from the New Elk Mine <br />would no longer be discharged, and the abandoned workings would fill with <br />water, a process taking up to 80 years. The piezometric surface would <br />partially recover. Because the underground workings lie 400 to 800 feet below <br />the surface, the piezometric surface of the coal aquifer would not be expected <br />to rise to a level where it would intersect the ground surface and, thus, <br />discharge. A permanent depression in the piezometric surface would exist in <br />the vicinity of the flooded mine workings. Given the assumption that the <br />Allen seam is hydrologically similar to the Maxwell seam, the depression may <br />extend to a distance of 2 to 3 miles from the edge of the mine workings. <br />When pumping of water from the workings is discontinued, the water that <br />accumulates is expected to be of lower quality than that currently pumped due <br />to increased residence time (Exhibit 6, Table 5 of the application). The <br />quality of the stagnant mine water should be similar to the quality measured <br />below the New Elk waste piles (Exhibit 6, Table 13). Total dissolved solids <br />are expected to equal or exceed 2600 mg/1. This mine water would spread as a <br />plume of degraded quality ground water down gradient from the mine. Based on <br />the structural contours of the coal seam, water passing through the flooded <br />workings would move in a northeasterly direction. It may spread to <br />approximately 2 to 3 miles from the edge of the mine workings. It is <br />anticipated that soluble materials would be readily flushed from the mine <br />