2009-04-29_PERMIT FILE - C1982056A (8)

Home Browse Search

nominal 3-4 yard hoisting bucket. The shaft cuttings were placed by awheel-loader in a 14-foot deep, lined temporary mine development waste pit excavated within the shaft pad, adjacent to the shaft excavation, as shown on Maps EX16E-M1 and M2. The cuttings pit is lined with a nomina130-mil PVC flexible membrane liner having a permeability of ~10-12 cm/sec. The PVC liner is covered with approximately 6-8 inches of pit-run material to protect the liner. The shaft concrete lining was placed in nomina120- to 30-foot lifts in cycle with the drilling and mucking operation, using acurb-ring and slip-form assembly. During excavation, the shaft work area was ventilated using ventilation ducting and a permissible surface fan. Once the blind sink excavation reached the coal seam, the work stage was removed and disassembled. The cuttings volume generated by shaft sinking operations is approximately 15,126 cubic yards (22,690 cubic yards when swelled by 50 percent, based on 20-foot diameter and 1,300-foot depth). If drainage of water from the excavated material resulted in any significant accumulation of water in the cuttings pit, the water was pumped to a water tanker to maintain essentially dry conditions in the pit. Upon completion of the shaft excavation and concrete liner installation, any minor water accumulation in the cuttings pit were allowed to dry-out, and the collection pit and cutting materials were then be covered with previously placed materials from the shaft collar excavation, graded, and revegetated with a temporary cover. A sign(s) was posted designating the temporary mine development waste pit. The cuttings and shaft collar excavation materials will be utilized to re-fill the shaft during eventual reclamation of the facility. The cement liner serves to isolate the Twentymile Sandstone from the Wadge Overburden. As noted above, apre- grout program is not required in a conventional blind sink. A probe-hole is typically carried down the hole as the shaft is excavated. Water is grouted off from within the excavated shaft as it is encountered. This further assures that, after final closure, the water in this unit is confined and will not seep down on the inside of the shaft. Following completion of shaft excavation and cement lining operations, and removal of equipment from the site, an emergency escape hoist will be installed in the shaft. Hoist installation will involve completion of the following activities, as illustrated by the design information provided in Exhibit 49N, 6MN Emergency Escape Hoist Design Drawings: • Erection of apre-fabricated steel hoist-frame and bull-wheel, approximately 10 x 22 x 25 feet high over the existing 6MN Ventilation Shaft, tying into the existing concrete shaft collar • Fabrication of a steel frame and expanded metal shaft landing and access stairs, tying into the hoist-frame • Fabrication of a similar shaft landing at the bottom of the shaft • Installation in the shaft of guide-ropes for the hoist cage • Excavation for the hoist-house foundation • Forming and pouring of the 20 x 30 foot reinforced concrete hoist-house foundation • Installation of the hoist motor, winch, and associated control equipment on the hoist-house foundation • Erection of the pre-fabricated steel hoist house • Stringing of hoist cable and placement and connection of the 3 x 5 x 8 foot high pre-fabricated hoist cage • Electrical connections (from existing power distribution line) and testing of hoist • Installation of appropriate equipment guards and fencing Underground Utilities Project Components -Concurrent with road construction, a 69-KV power distribution line was extended from the existing substation at the Northwest Mains fan location to apad-mounted transformer at the 6 North Mains shaft site. The power distribution line is approximately 3,130 feet long with a total of approximately 14 powerpoles and is located adjacent to the proposed access road and within the 50-foot road corridor from road centerline. In conjunction with the 6-North Mains shaft project and extension of the power distribution line, TCC also proposes to construct on the shaft pad a high voltage substation with three power borehole drops, a compressed air station with borehole drop, a rockdust tank station with borehole drop, a bulk material borehole drop and a water borehole drop for the continued development and mining of the Northern and Western Mine Districts. The boreholes were drilled to a nominal 13-inch diameter. Water for drilling operations was either trucked-in by tanker or drawn from Fish Creek using a portable pump (under TCC's Boettler Ditch water right -144 cfs). The cuttings TR09-66 2.05 - 45.6d 02/17/09