2018-01-03_PERMIT FILE - C1981010A (2)

Home Browse Search

The Kimber(K) Pit employs both a truck/loader fleet and draglines as methods of mining. Where the coal structure allows, the truck/loader fleet will remove overburden material from the I, K, and L seams, and the draglines or dozers will uncover the M, Q, and possibly R seams. The truck/loader fleet will generally operate in a strikeline orientation, and the draglines will generally operate in either a strikeline or a dipline orientation, depending on which area of the pit the machines are working. Where the geology precludes effective dragline mining, the truck/loader fleet will uncover all mineable seams, up to and including the R seam. As mining progresses eastward and into L& M pits(and out of K pit), Trapper Mine's traditional stripping techniques(in a down dip orientation)will resume. Initial spoils from the truck/loader fleet were hauled to the Horse Gulch fill or to Flintlock pit for final pit backfill. As soon as conditions allow, the K Pit will be backfilled with K and L Pit spoils to meet the post- mining topography depicted on Map M12, Sheet 3. Operations will generally progress down dip to maximize the stability of the K Pit during mining operations. Backfilling will only occur above active mining operations when it can be placed without endangering men or equipment. The M12 series of maps depicts the planned Post Mining Topography. The K Pit area appears on Sheet 3. The topography depicted meets the definition of approximate original contour, per Statute 34-33-103(3) and Regulation 1.04(13). The proposed topography closely resembles the general surface configuration of the land prior to mining, and blends into and complements the drainage pattern of the surrounding terrain. The variance of post mining elevations and pre-mining elevations are consistent with Trapper's prior, and successful, reclamation efforts. Examples of successful reclamation, as evidenced by Phase 3 bond release, where such variance exists can be found in the northwest and north-central portions of D Pit, and the northeast portion of the E Pit boxcut spoil. Phase 2 bond release examples can be found in the east- central and northeast portions of D Pit. As such, the Horse Gulch fill qualifies as excess spoil, as defined by Regulation 1.04(45a). This fill will be left as a permanent reclamation feature, consistent with the planned post mining land use of Rangeland and Wildlife Habitat. The fill was constructed with overburden, as defined by Regulation 1.04(83). Neither coal mine waste, as defined by Regulation 1.04(22a), nor coal processing waste, as defined by Regulation 1.04(24), were used in the construction of the fill. Topsoil was stripped and salvaged prior to construction, and no organic material was used in its construction. The Horse Gulch area was chosen for excess spoil placement because the area contained neither ephemeral streams, as defined in Regulation 1.04(42), nor intermittent streams, as defined by Regulation 1.04(69). This location allowed construction of a head of hollow fill, as defined by Regulation 1.04(56), which blends with the surrounding topography. Detailed cross sections can be found in Appendix T. The hydrologic balance, as defined by Regulation 1.04(61), is protected with this mine plan. There is no discernible change in the quality or quantity of water inflow to our outflow of the Yampa River Basin. As mining of the K Pit progresses, prestripping in L Pit has begun. This will assist the dragline operation, and provide for the continued backfill of K Pit. When K Pit is backfilled, spoil material removed via T/L will be placed in the L pit spoils. The final cut in any given pit may be open for as long as 18 months until all coal is removed. Final cuts are a logical area to carry inventory. Due to spoil side stripping techniques employed at Trapper, extra room is needed to effectively place the spoils. Taking into consideration that the shortest cycle time in a down-dip dragline operation leaves the pit active for up to 230 days and that the interburden will be cast as far as three previous cuts, it is not possible to regrade the spoils within 180 days after coal removal. For Trapper Mine's contemporaneou"s regrade criteria, grading will progress such that there will be no more than three un-regraded spoil rows, including the active spoil row, at any one time in each pit. A pictorial view of the double pass stripping operation is shown in Figure 3.5-1. This figure presents a simplification of the Trapper stripping operation and shows graphically why three spoil rows are required. 3-39 MAY 21 2013