2016-09-01_REVISION - C1981010 - Laserfiche WebLink

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inclinometers and survey monuments are installed. Initial box cuts are opened with draglines and/or with trucks and excavators. Keyways can be excavated with draglines, excavators or dozers to establish the highwall. Draglines can strip overburden and partings from both highwall and spoil sides of pits. Coal mining takes place after the coal is uncovered and backfilling, re -contouring, and reclamation activities take place after coal removal is completed. Current plans call for mining in four separate pits. These pits are shown on the attached Ground Control Plan Map 1 and are listed below: ACCEPTED/FILED Pit Derringer (or D) Pit Ithaca (or I) -Pit Lancaster (or L) Pit Nighthawk (or N) Pit AUG 26 2016 CMSH-DISTRICT 9 The types of layered strata associated with the geology are shown on Figure 1, Typical Stratigraphic Section. The mineable seams in a pit will vary depending on coal thickness, quality and economic factors. Future mine plans may call for mining in any or all of the areas shown in Ground Control Plan Map 1. Mining Methods: The mine utilizes two surface mining or pit development methods; 1) Strikeline Mining, and 2) Dipline Mining. The mining methods utilized provide for the safe control of all highwalls, pits and spoil banks, are consistent with prudent engineering designs, and ensure safe working conditions. Strikeline Mining with Draglines and/or Truck/Loader: This mining method exposes coal seams by developing successive cuts oriented along the strike (approximately parallel to the contours) of the coal (see Cross -Section 1). Dragline spoil is typically cast upslope/or downslope into the prior open cut with pit floors prepared as necessary to ensure spoil stability is achieved. Coal in the dragline strike cuts is mined by either operating excavating and hauling equipment in successive cuts or slots oriented along the dip of the coal, or by dozing or stacking the coal at the toe of the exposed coal seam near the down dip highwall or spoil bank. Exposed coal seams may also be mined with equipment operating along the strike of the coal. In this case, flattened to mildly cross -sloped (travel ways are established for the haulage equipment. Protective berms are utilized, if necessary, on any elevated roadways or ramps that equipment may travel on. Up -dip spoil slopes adjacent to the pit floor are placed at an approximate slope of 1.33H:1 V with some areas steeper. Highwall angles are 70 degrees with some slopes flatter when benches are considered. Pit floors are prepared as necessary to ensure spoil stability is achieved. Overall highwall slopes are maintained at S60° as shown in S:\GROUND CONTROLVanuary 2016 GCP Revision\Trapper_GCP_Jan20l6_DRAFTI.docx Page 12