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Once the overburden is sufficiently fragmented to allow for efficient removal and <br />loading, overburden removal will commence. The location of the azea to be mined is <br />shown on the Mine Plan Map (Map 23). In June of 2004, Colowyo did extract 2600 tons <br />of unleased federal coal in SW 1\4 of Sec.4, T3N, R93W, 6~' PM. The area impacted is <br />illustrated on the Mine Plan, Map 23 with the extension of the West Pit Mining Limit <br />boundary. <br />Colowyo utilizes two distinct methods of overburden removal in the mining operation: <br />(1) truck/shovel techniques and (2) dragline technique. By combining the use of both <br />shovel and trucks, and draglines, Colowyo can both efficiently and economically handle <br />the logistics 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 <br />of B and B2. From time to time, based on production requirements, truck/shovel or <br />loader/truck methods maybe 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 <br />from the initial excavation. Box cut overburden material was placed into the Streeter Fill <br />as shown on the Existing Structures -South Map (Map 22) and as discussed in Section <br />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 <br />Mining Range Diagrams (Map 24)), and the equipment mining those benches. <br />Overburden removal by the, truck/shovel method progresses on approximately 170-240 <br />foot wide benches with a maximum highwall height of about 60 feet. Electric shovels or <br />front-end loaders load this overburden into 50, 170, 190 or 240-ton trucks. The trucks <br />then haul the overburden azound the active coal pit and dump this material into the <br />mined-out azea. The truck/shovel operation will always precede the dragline operation in <br />the multiple seam pits. <br />< r a i i zna wt-ns 2.05-6 Revision: MR-65 <br />v.>i i z os-r, o~oaoa.d~,~ Date: 7/8/04 <br />