Laserfiche WebLink
Once the overburden is sufficiently fragmented to allow for efficient <br />removal and loading, overburden removal will commence. The location of <br />the area to be mined is shown on the Mine Plan Map (Map 23). <br />Colowyo utilizes two distinct methods of overburden removal in the mining <br />operation: (1) truck/shovel techniques and (2) dragline technique. By <br />combining the use of both shovel and trucks, and draglines, Colowyo can <br />both efficiently and economically handle the logistics involved in a <br />multiseam, open pit coal mine. <br />The truck/shovel operation was used to open up the initial boxcut, and <br />now is generally utilized in removing overburden over the upper coal <br />seams, Y3, Y2, X, A2, and portions of B and B2. From time to time, based <br />on production requirements, truck/shovel or loader/truck methods may be <br />utilized to assist the dragline operation in the lower seams. <br />The initial mining operations at Colowyo began along the southern face <br />of Streeter Draw. The box cut extended into the upper reaches of the <br />draw. Mining has proceeded south from the initial excavation. Box cut <br />overburden material was placed into the Streeter Fill as shown on the <br />• 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 <br />height of these benches will be influenced by the distance between the <br />coal seams to'be mined (see Mining Range Diagrams (Map 24)), and the <br />equipment mining those benches. <br />Overburden removal by the .truck/shovel method progresses on approximately <br />170-240 foot wide benches with a maximum highwall height of about 60 <br />feet. Electric shovels or front-end loaders load this overburden into <br />50, 170, 190 or 240-ton trucks. The trucks then haul the overburden <br />around the active coal pit and dump this material into the mined-out <br />area. The truck/shovel operation will always precede the dragline <br />operation in the multiple seam pits. <br /> <br />2.05-6 <br />Revision kpryreved- ~ ~ ~ G 7 <br />Revision No. ~I Z <br />