PERMFILE133766 - Laserfiche WebLink

Home Browse Search

Postmine slopes were then superimposed on the diagrams. For the sake of continuity, it was • estimated that all spoil would be graded towards the open pit at 5h:1v slopes. All highwall slopes would be reduced to 5h:1v. This produced a final topography that could not only be revegetated, but would also allow drainage to flow through the pit area without impounding water. !t was also assumed that in all cases there would be-four standing spoils behind the open pit. This is a very conservative estimate because, in most cases, reclamation grading is current to within two spoil piles. A digitizer was used to balance the cut and fill volumes of material needed to create the above- described topography. A swell factor of 17 percent was utilized for the bonding estimate. The adjacent spoil would be dozed into the open pit and the three other spoils would be graded into the adjacent v's created by the spoil (see appropriate worksheets in Attachment 25-11• Highwalls will be reduced and sloped towards the open pit. This would be accomplished by drilling and shooting the highwall and then dozing/ripping the blasted material into the open ph. See appropriate worksheet in Attachment 25-1 for a complete listing of volumes to be dozed into the open pit. A Caterpillar computer program called EMF was used to determine dozer production. This program • utilizes iniormation given in the Caterpillar Handbook. All tables and charts have been computerized to simulate production for track type equipment. See various worksheets for production and costs. The premining and postmining topography maps were compared for material movement. Although a specific postmine topography map is not available fora 2004 mine closure, drainage patterns will generally remain the same as the planned final topography. Due to the fact that the topographic highs and lows will generally be located in the same area after mining as they were prior to mining, it is not anticipated that wheel type earthmovers will be needed to backfill the final pit. No box cut spoil grading is included in this estimate. The timing and location of the box pit spoil is such that all box pit spoil will be reclaimed by the end of 2004, and therefore, was not included as a liability in the "worst case" year. Ramp grading estimates are included with spoil grading. It was assumed that ramps will be graded at the same time as two spoils are pushed into the pit and, therefore, additional cost is not estimated Tor this project. • 3 Revised 11/00