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Once the overburden is sufficiently fragmented to allow for efficient removal and loading, overburden removal will commence. The location of the area to be mined is shown on the Mine Plan Map 23. Colowyo utilizes two distinct methods of overburden removal in the mining operation: (1) truck/shovel techniques and (2) dragline technique. By combining the use of both shovel and trucks, and draglines, Colowyo can both efficiently and economically handle. the logistics involved in a multiseam, open pit coal mine. The truck/shovel operation was used to open up the initial boxcut, and now is generally utilized in removing overburden over the upper coal seams, Y3, Y2, X, A2, and portions of B and 82. From time to time, based on production requirements, truck/shovel or loader/truck methods may be utilized to assist the dragline operation in the lower seams. The initial mining operatioris at Colowyo began along the southern face of Streeter Draw. The box cut extended into the upper reaches of the draw. Mining has proceeded south from the initial excavation. Box cut overburden material was placed into the Streeter Fill as shown on the Existing Structures -South Map 228 and the 2001 Annual Report Map, and as discussed in Section 2.06.2. The overburden material is removed in a series of lifts or benches; the height of these benches will be influenced by the distance between the coal seams to be mined (see Mining Range Diagrams Map 24), and the equipment mining those benches. Overburden removal by the, truck/shovel method progresses on approximately 170-240 foot wide benches with a maximum highwall height of about 60 feet. Electric shovels or front-end loaders load this overburden into 50, 170, 190 or 240-ton trucks. The trucks then haul the overburden around the active coal pit and dump this material into the mined-out area. The truck/shovel operation will always precede the dragline operation in the multiple seam pits. 2.05-6 June 18, 2002 MR-57 CF 4.1.1.3.