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Once the overburden is sufficiently fragmented to allow for efficient removal and loadine, <br />overburden removal will commence. The location of the area to be mined is shown on the <br />Mine Plan N[ap (Map 23). [n June of 2004, Colowyo did extract 2600 tons of unleased <br />federal coal in SW1/4 of Sec.4, T3N, R93W, 6th PM. The area impacted is illustrated on the <br />Mine Plan, Map 23 with the extension of the West Pit Mining Limit boundary. <br />Colowyo utilizes two distinct methods of overburden removal in the mining operation: (I) <br />truck/shovel techniques and (2) dragline technique. By combining the use of both shovel and <br />trucks, and draglines, Colowyo can both efficiently and economically handle the logistics <br />involved in a multiseam, open pit coal mine. <br />The truck/shovel operation was used to open up the initial boxcut, and now is generally <br />utilized in removing overburden over the upper coal seams, Y3, Y2, X, A2, and portions of B <br />and B2. From time to time, based on production requirements, truck shovel or loader/truck <br />methods may be utilized to assist the dragline operation in the lower seams. <br />The initial mining operations at Colowyo began along the southern face of Streeter Draw. <br />The box cut extended into the upper reaches of the draw. Mining has proceeded south from <br />the initial excavation. Box cut overburden material was placed into the Streeter Fill as shown <br />on the Existing Structures -South Map (Map 22) and as discussed in Section 2.06.2. <br />The overburden material is removed in a series of lifts or benches; the height of these <br />benches will be influenced by the distance between the coal seams to be mined (see Mining <br />Range Diagrams (Map 24)), and the equipment mining those benches. <br />Overburden removal by the, truck/shovel method progresses on approximately 170-240 foot <br />wide benches with a maximum highwall height of about 60 feet. Electric shovels or front-end <br />loaders load this overburden into 50, 170, 190 or 240-ton trucks. The trucks then haul the <br />overburden around the active coal pit and dump this material into the mined-out area. The <br />truck/shovel operation will always precede the dragline operation in the multiple seam pits. <br />r ~ <br />~J <br />2.05-6 Revision Date: 7/08/04 <br />Revision No.: MR-65 <br />