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With the coal reserves defined end equipment chosen, it becomes the engineer's task to apply his • technical expertise to the design of a facilities site plan, mining plan, ground control plan, haulage road system, surface water control plan, sediment control plan, power distribution system, postmine contour configuration, and a variety of inter-related projects. The processing and support facilities are generally located at a site near the center of the reserves in order to balance haulage distances. Factors such as topographic relief, strength of foundation materials, adequacy of drainage and accessibility are normally considered in the engineering design. The design of a mining plan is governed by several factors, including economic considerations, drainage patterns, relief, slope, and geologic structures. Normal pit progression would begin at a "cropline" (outcropping) or shallow area and progress toward the deeper coal. The advantage of this technique is a lower production cost in early years. However, the cost of production becomes progressively higher as the pits advance. At Seneca II-W, the, topography and geologic structure dictate pit orientation and progression. In the main II-W area, more uniform overburden depths favor pits oriented perpendicular to the cropline while rapidly increasing overburden depths in the II-W South area favor pits oriented parallel to the cropline. The best techniques for orientation of pits with respect to drainage patterns are to lay out a sequence of pits where the natural drainage is away from or parallel to the pits. The techniques used at Seneca II-W to deal with the relatively high relief, slopes, and geologic structure will discussed in the following section. A haulage road system is designed with roads of appropriate width and grade to accommodate the intended traffic. In mountainous terrain the construction of switchbacks is sometimes necessary to maintain the flatest possible grade and minimize the area of disturbance. Safety berms will be utilized where • required by steep side slopes. Surface water control plans normally utilize ditches for overland diversion of surface water as well as pit sumps for collecting and handling surface and ground water that enter the pit. Sediment ponds are designed for controlling runoff from disturbed areas. All diversions end sediment ponds ere designed in accordance with the regulations governing such structures and conform to currently accepted engineering practice. Power distribution at area surface mines such as Seneca II-W, which utilizes high voltage electrical equipment, must be well planned far optimum accessibility. Power for stripping equipment is normally fed from the highwall or undisturbed side of the operation for ease of access and to alleviate congestion in the pit and on the spoil side. A very important task requiring utilization of the best available engineering techniques is the design of a stable postmine land surface. Determination of such Tactors as spoil swell, stream gradients, postmine land use, spoil character, and foundation materials will affect the design of a land surface representing the approximate original contour. The currently accepted technique is to design a surface with slopes that do not exceed the average premining slope and with a general configuration that approximates the premining surface. Area surface mining is the most efficient method of recovery of a coal resource, especially in areas such as Seneca II-W where the coal is of such a quality that it can be burned "raw", that is, without processing. The Watlge Coal seam will be mined to approximately 100 feet in depth (limitation of the stripping equipment) with a resource recovery rate approaching 95 percent. Table 12-2 illustrates the • actual and anticipated acres mined and actual and proposed annual production of coal from September 1, 1 990 through the currently proposed life-of-operations. It is highly unlikely that the areas proposed 3 Revised 9/98