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• collecting and pumping surface and ground water that enter the pit. Sediment ponds are designed for <br />controlling runoff from disturbed areas. All diversions and sediment ponds are designed in accordance <br />with the regulations governing such structures and conform to currently accepted engineering practice. <br />Power distribution at area surface mines such as Yoast, which utilizes high voltage electrical <br />• <br /> <br />equipment, must be well planned for optimum accessibility. Power for stripping equipment is normally <br />fed from the highwall or undisturbed side of the operation for ease of access and to alleviate <br />congestion in the pit and on the spoil side. Avery important task requiring utilization of the best <br />available engineering techniques is the design of a stable postmine land surface. Determination of <br />such factors as spoil swell, stream gradients, postmine land use, spoil character, and foundation <br />materials will affect the design of a land surface representing the approximate original contour. The <br />currently accepted technique is to design a surface with slopes that do not exceed the average <br />premining slope and with a general configuration that approximates the premining surface. <br />Area surface mining is the most efficient method of recovery of a coal resource, especially in areas <br />such as Yoast where the coal is of such a quality that it can be burned "raw", that is, without <br />processing. The Wadge Coal seam and a small amount of the Wolf Creek coal seam will be mined to <br />approximately 100 feet in depth (limitation of the stripping equipment) with a resource recovery rate <br />approaching 91 percent. Table 12-2 illustrates the anticipated acres mined and annual production of <br />coal from October 1996 through the currently proposed life-ot-operations. It is highly unlikely that the <br />areas proposed to be mined will be redisturbed at some future date to recover deeper seams. The <br />closest coal seam below the Wadge seam is the Wolf Creek seam with an interburden thickness of <br />approximately 150 feet. There is no equipment suited to the terrain at Yoast that could economically <br />remove interburden to such depths. <br />Operation Description -General <br />The mining plan for Yoast was developed in conjunction with the Seneca Il and II-W miningplans and <br />is based on standard mining practices, feasibility studies, and balancing production between mines. <br />As shown on Exhibit 12-1 and Figure 12-1, the mining reserves at the Yoast Mine lie in irregular <br />shaped areas along ridge tops. The area will be mined from cropline to approximately the 100 foot <br />recovery line. <br />$ - Revised 2/99 <br />