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

Home Browse Search

Spoil peaks are leveled and depressions are filled. The area is graded to the approximate original contour and blended into adjacent areas. All temporary diversions and associated structures are removed, regraded and reclaimed when they are no longer needed. After the rough grading has been completed, it is inspected by the Engineering and Environmental Departments. If the area is approved with respect to grade and contour, it is final graded. Final grading is performed on the contour unless slope or ground conditions make operation of equipment across the slope hazardous to men or machinery. Dozers, graders or similar equipment are used. 1 In accordance with TR-69 recommendations, precaution will be taken when reclaiming an open pit when several of the folkmdng adverse conditions for slope stability might be present i • A slope of the reclaimed pit steeper than 1:4 (V:H); • Shallow (15-25 feet) overburden composed mostly of clays; • Mined coal floor composed of shales, and dipping parallel with the reclaimed slope; and, •i Potential for higher than normal infiltration of surface runoff or presence of ground water within the replaced spoils. Ifi some of the above conditions are present, special procedures will be taken during the pit reclamation. Although these procedures should be site-specific, the following remedial measures could be applied: •i Slopes steeper than 1:5 should have better than normal compaction of the reclaimed spoils material; •! The coal floor shale strata could be scarified at regular intervals to disturb the potential slide surface; •i Slopes with higher potential for surface runoff should be well drained by additional perimeter ditches; and, • Areas of potential infiltration of surface water or areas with a potentially high ground water table should be provided with French drains. The drains should be located to effectively drain the potential accumulation of water at the top of the bedrock. The proposed remedial measures should assure safe slope conditions even during above-normal precipi- tation and/or snowmelt Where areas are being reclaimed to cropland, a dozer pulling a drag or a similarly effective procedure is used to further level the area so that a uniform depth of topsoil can be laid down. to the length of some of the pits at the Trapper Mine, most cuts will remain active longer than 180 r. In many mining areas, the dragline is required to make two passes per cut in order to effectively ver two or more coal seams. The first pass is done to remove overburden material over the first coal n. The dragline then moves across the pit to the spoil ridge created from the overburden removal and s the interburden material to the second seam of coal. Since the dragline is positioned on the spoil of the cut, the interburden material is cast as far as the second and third spoil rows. Depending upon thickness of the interburden material, dozers or similar equipment may aid in the removal of the burden. When excavating with trucks and excavators, backfilling will occur as soon as direct haul to open cuts is possible. The timing of these activities will be governed by geotechnical and other tiderations that insure the safety of personnel and equipment 3-38 zlz?oR q(ZC??`i