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

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In order to comply with new Mine Atmosphere Control (MAC) regulations, under the jurisdiction of the Mine Safety and Health Administration (MSHA), and minimize surface disturbance, TCC proposes to drill and case up to two MAC boreholes from the surface of the cuttings collection pit into the bleeder entries (approximately 1,000 feet). The 40 30-inch diameter borehole(s) would be drilled using a conventional down -hole rotary drill -rig and cuttings will be collected in a portapit. Surface casing will be set and grouted to bedrock, and steel borehole casing with a nominal inside diameter of 24 inches will be set and the annulus between the casing and the borehole will be fully grouted to both stabilize the casing and seal it off from potential groundwater infiltration. At the cuttings pit liner interface, quick -set grout will be injected above and below the liner to seal the liner where it is penetrated by the surface casing. Cover material will be removed from a portion of the cuttings pit, and borehole cuttings will be transferred to this area to dry, and will then be spread and compacted. On completion of the borehole(s), the cover material will be replaced and stabilized by seeding with a temporary cover. The stockpiled cuttings will be used to backfill the MAC borehole(s) during final reclamation. A methane drainage pipeline and/or nitrogen injection pipeline will be installed within the cased MAC borehole, and connected to one or more manifolded pipe systems underground which will connect to sealed gob areas. At the surface, an 8 -foot diameter culvert manhole may be installed around the cased MAC borehole(s) as a well -head, with appropriate grounding and lightning protection to meet MSHA requirements. The fixed pipeline(s) will connect at the surface to a portable skid- mounted methane drainage pump and/or skid - mounted nitrogen generator system consisting of the nitrogen generator, two air compressors, a diesel generator, and a control building. Required power for this installation will be provided by dropline from the existing powerpole, and the area will be fenced for security. Installation details are shown by the design drawings in Exhibit 49Q. 6 -North Mains Ventilation Shaft (TR05 -48, MR06 -208, MR06 -210, MR06 -212, MR07 -218, MR09 -236) An additional intake ventilation shaft is necessary to maintain effective ventilation of active mining areas in the northwest mining district and future west mining district. The new ventilation shaft will be located in Section 17, T5N, R86W on a ridge northwest of the Northwest Mains Ventilation Shaft and fan, as shown on Maps 23 and 23B. 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 pad and access road. The cultural resource survey was conducted by Metcalf Archaeological Consultants, the engineering soils characterization by Northwest Colorado Consultants, and the soils /wetland/AVF survey by Habitat Management, as described in Section 2.04. Development, construction, and installation of the intake ventilation shaft (Exhibit 49A, Figures EX49A -F1 through F4 and Maps EX49A -M1 through M3, and Exhibits 49E and 49N) involve the following sequential activities: • Completion of environmental and engineering investigations • Placement of disturbed area markers • Marking of wetland buffer zone • 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 and casing of seven (7) boreholes for: - 3 power boreholes - 1 water borehole - 1 air compressor borehole - 1 rockdust borehole - 1 bulk- material drop borehole (will also be used as the nitrogen injection borehole) • Construction of shaft collar structure and temporary drilling equipment pad • Conventional blind sink excavation and casing operations • Driving of additional entries to the south of the existing 6 -North Main entries • • Installation of electrical sub - station and extension of power distribution line • Fabrication of Million - Gallon Tank for mine water storage • Installation of Rock -Dust Tank and Compressor • Erection of escape hoist /elevator buildings and equipment and installation of fence(s) • Installation and connection of escape hoist /elevator control equipment and systems TR09 -70 2.05 -45.7 12/31/09