2010-11-12_PERMIT FILE - C1981010A (8)

Home Browse Search

Flintlock Pit cuts range from approximately 3500 feet to over 5100 feet in length. When production requirements are down, the machine in Flintlock Pit becomes a fill -in machine. As a result, a single cut may be open for as long as 18 months. Dozers may be employed to strip to the upper I and L seams in this pit. The dragline will strip overburden to M seam at a pit width of approximately 150 feet. Once the M seam has been extracted and the interburden is drilled and shot, the dragline will strip the interburden to Q seam from the spoil side. As in all multiple seam pits at Trapper, interburden material that is not needed to build ramps and pads to get up the hill may be spoiled on the second or third spoil row. For this reason, grading closer than three spoil rows from the pit may be subject to additional spoil placement. East Ashmore Pit cuts may range from approximately 900 feet to over 2000 feet in length. This is a single seam pit utilizing production dozing in conjunction with dragline stripping to remove overburden to H seam with a simple side cast method. Typically, this pit will cycle quickly, with a cut remaining active for only a few weeks. However, should a significant drop in production requirements occur, a cut could remain open for up to six months. East Flintlock Pit (a.k.a Z pit) employs both dipline and strikeline cuts. In strikeline cuts, a dragline opened box cuts along the strike with lengths ranging from 1000 to 2100 feet. Three seams, L, M and Q, are uncovered and mined. Box cut spoils are placed downhill of the cuts. These materials will require widths of up to 1000 feet or more to be left available below the crest of the first cut to allow sufficient room to blend the spoils into the landscape. The box cut areas will be left open until the pits have progressed up the hill a sufficient distance so that regrade operations can begin. Draglines will uncover coal seams from the spoil side stripping along the east/west strike. The maximum amount of time that these cuts will be open will be approximately six months. Cast blasting methods will be utilized to aid the dragline in uncovering the top L seam. Occasionally, the L seam overburden is removed utilizing production dozing. After L seam is uncovered, the parting between L and M seam will be shot, the dragline will then walk back to the opposite end of the pit and begin uncovering M seam. Q seam will be uncovered in a similar manner with the dragline stripping the parting between M and Q.seams. The dipline cuts in this pit start with a boxcut immediately east of the limit of the strikeline pits. The orientation was changed to dipline to accommodate the changing structure. The dip of the strata steepens and shifts from a general northward trend to a northeasterly trend. The K, L, M and Q seams are mined in the dipline pits. Production dozing is generally employed to uncover the K and L seams. Dragline stripping is utilized to uncover the M and Q seams. The Kimber (K) Pit employs both a truck/loader fleet and a dragline as methods of mining. The first dragline cut is one pass wide, along the ridge top. This cut generally runs east to west. Where the coal structure allows, the truck/loader fleet will prestrip to the slide plane, roughly the L seam, and the dragline or dozers will uncover the M, Q, and possibly R seams. The truck/loader fleet will generally operate in a strikeline orientation. With the exception of the first ridgeline cut, the dragline will generally operate in a dipline orientation. Where the geology precludes effective dragline mining, the truck/loader fleet will uncover all mineable seams, up to and including the R seam. Initial spoils from the truck/loader fleet will be hauled to the Horse Gulch fill, spoiled north of the K Pit, or spoiled elsewhere on the site to meet the requirements of PMT. As soon as conditions allow, the K Pit will be backfilled with K and L Pit spoils to meet the PMT depicted on 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. 3-39 `R t O(o 5 112 12.010