2010-06-04_PERMIT FILE - C1982056A (9)

Home Browse Search

The installation of the silencer and duct work will occur within the existing disturbed area. The overall length of the silencer and duct work is approximately 34 feet, the location of the structure is shown on Figure 16 E(1). Additional Suunort for UP Fan Silencer (MR 02 -179 An additional H -beam support structure is needed to maintain the stability of the silencer. The structure will be placed between the fan concrete pad and the eastern silencer support structure. The support structure will be approximately 14' high and tied in at the top with a 12' H -beam. Cross - bracing rods will be used to tie the two H- beam supports together. The transition section of the silencer will be supported by the new structure. The support structure will be bolted onto a concrete footer approximately 3.5' x 4' x 12'. NW Mains Ventilation Shaft and Thickener Underflow Project (TR 01 -39) As mine development has proceeded to the north, the distance from existing mine ventilation fan installations has increased to the point where an additional ventilation shaft and fan installation are necessary to maintain effective ventilation of active mining areas. The new ventilation shaft and surface fan installation, will be located approximately 900 feet north of Fish Creek in Section 17, T5N, R86W on a low rise above the Fish Creek drainage, as shown on Maps 23 and 23B. Development, construction, and installation of the ventilation shaft and fan installation involves the following sequential activities, as briefly described in the following sections: • Completion of environmental and engineering investigations • Temporary drainage and sediment control measures • Recovery and stockpiling of available topsoil • Installation of drainage and sediment control structures • Construction of an access road and site preparation for shaft pad • Drilling of shaft pilot hole, grout holes (if required), and utility boreholes • Construction and extension of power distribution line • Construction of shaft collar structure, temporary drilling equipment pad, and fan foundations • Shaft boring and casing operations • Erection of fan enclosure and control buildings and installation of fence(s) • Installation and connection of fan, drive, and control equipment and systems • Driving of additional entries in the Northwest Mains • Final clean -up and dressing of roads and site pads Site - specific investigations required for design and permitting of the new ventilation shaft included a cultural resource survey of potential disturbance areas, soil and foundation characterization as the basis for shaft pad and access road design, and completion of a wetland/AVF survey for the shaft access road and power line crossing of Fish Creek. The cultural resource survey was conducted by Metcalf Archaeological Consultants, the engineering soils characterization by Northwest Colorado Consultants, and the wetland/AVF survey by Habitat Management, as described in Section 2.04. The proposed shaft pad area is approximately 280 feet square (1.8 acres) and the associated access road corridor is approximately 3,800 feet long with a finished top width of 22 feet (road corridor 30 feet wide). See Exhibit 25 S, NW Mains Ventilation Shaft Access Road Design, for details on the road. Approximately 2,000 feet of the access road crosses upland areas, with the remaining 1,800 feet crossing lowland areas where road construction will involve removal of any large vegetation and placement of geotextile and road fill over the in -place soils. Given an average topsoil depth of approximately 6 inches in the upland area and a total disturbance area of approximately 1.4 acres, approximately 1,111 CY of topsoil was salvaged from the road corridor, and 1,452 CY from the pad. The topsoil from these areas was placed in stockpiles adjacent to the shaft pad and road for future reclamation use. The topsoil salvage volumes are indicated on Table 49A. Seeding with the topsoil stockpile stabilization seed mixture was used to stabilize the stockpiled topsoil. TR09 -66 2.05 -45 02/17/09