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CHAPTERTWO Alternatives <br />separated by gravity with heavy media circuits. The coal is lighter and "floats," and is then <br />transferred to the clean coal stockpile. The rock (coal mine waste) is heavier and sinks, and is <br />then taken to the waste disposal area. The plant would be a closed system. All water would be <br />treated in a thickener and returned to the plant. No water would be discharged. The thickener is <br />a concrete structure where water is cleaned and returned to the wash plant. The tank would be <br />approximately 70 feet in diameter and 10 feet high. The coal preparation plant structure would <br />be approximately 55 feet by 140 feet by 80 feet high. A refuse bin may be utilized to hold surges <br />in refuse production from the coal preparation plant and would load refuse haul trucks. The <br />refuse bin would be constructed of structural steel approximately 20 feet long by 20 feet wide by <br />60 feet high. <br />From the coal preparation plant, clean coal would be taken to the clean coal stockpile for transfer <br />onto the unit train loadout. Coal refuse would be taken to a waste disposal area (gob pile). Coal <br />mine waste is generated by the coal wash plant and by roof falls in the underground mine; it is <br />composed of sandstone and shale, with small amounts of coal. This material has been tested and <br />is not classified as hazardous material. The coal mine waste material would be hauled by <br />conveyor and truck to the disposal area. Coal mine waste would be placed and compacted to <br />90 percent of the maximum dry density to prevent spontaneous combustion and to provide the <br />strength required for stability of the gob pile. Dry densities would be determined in accordance <br />with American Association of State Highway and Transportation Officials (AASHTO) <br />Specification T99-74. The gob pile is designed to prevent off-site migration of the coal mine <br />waste. The placing and spreading of the coal mine waste would be started at the lowest point of <br />the foundation. The coal mine waste would be keyed into the natural ground. Materials would <br />be spread in approximately horizontal lifts no more than 24 inches thick and such lifts made <br />uniformly over long stretches. Each lift would be moistened or dried to uniform moisture <br />content suitable for maximum compaction. Compaction would be carried to the edge of the fills <br />so that the final slopes would be firm. Slopes would be no steeper than 2.SH:1V with 15-foot- <br />wide terraces on 50-foot vertical intervals. Runoff from the gob pile would be captured and <br />routed to the sedimentation ponds. <br />As discussed previously, clean coal from the stockpile would be transferred to the unit train <br />loadout. The unit train loadout would be comprised of a reclaim tunnel, conveyor belt(s), and <br />loadout tower. The reclaim tunnel would be located under the clean coal storage pile. It would <br />be constructed of reinforced concrete or steel multi-plate. The typical inside dimensions of a <br />reclaim tunnel are 13 feet high by 12 feet wide. Vibratory feeders in the reclaim tunnel transfer <br />clean coal onto the conveyor belt(s) at a rate of 6,000 tons per hour. Coal would be conveyed <br />directly to the loadout structure. The coal would then be batch weighed and loaded into rail cars <br />at this location. The dimensions of the loadout structure would be approximately 30 feet long by <br />40 feet wide by 120 feet high. <br />2-50 <br />