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RPR. 9.2002 10~07RM TWENTYMILE CORL ENVIRONMENTRL N0. (371 P. 9 Concurrent with road construction a power distribution line Will be extended firm the existing substation to the pad-mounted transformer at the shaft site. The power distribution line is approximately 3,600' long with a total of 12 power poles. In order to minimize potential enviroameatal and aesthetic impacts associated with the NGV Mains ventilation shag and fan installation, surface drainage at the shaft site will be handled by an upgradient diversion ditch, perimeter berms, and gravel surfacing under an SAE, the limited road drainage will 6e handled by designed drainage structures, active use areas era graveled to control dust and drainage, other disturbed areas (including topsoil stockpiles) will be stabilized with temporary vegetation, and structures will be painted in neutral earth-tone colors to blend with the natural surroundings. As shown on Map 23, additional entries will be driven to the north from the ventilation shaft silo. These entries will be needed to maximi2e the ef{tcienay of the ventilation system. The entries will be driven in the same meaner as is used in TCC's development work, i.e. coaitinuous miners and shuttle cars. No. 7 North fiscape Shaft (Section 20, TSN, R86VV) A 1,066 foot escape borehole shaft was constructed into #7 entry of North Mains to allow emergency evacuation of personnel from the development sections of the 9 Right and 10 Right gateroads, The construction of the shaft utilized raise drilling techniques. It is anticipated that the escape shaft will be utilized for approximately ten years. The site is shown on Figure 23, General Location of Escape Shag. The drilling of the shafr resulted in minimal surface disturbance. A drill pad approximately 200' x 200' was constructed at the resulting site in 1,450 CY of cut and fill, Available topsoil was salvaged and stockpiled for future reclamation of the site immediately northeast of the drilled pad. Approximately 1 S" of topsoil derived from Cochetopa Loam is available for salvaging (222 CY). Casing and other drilling supplies were stockpiled on the borehole pad. ARer topsoil removal, two mqd pits with dimensions of 10' x 10' x 7.5' were dug adjacent to the drill hole. Drilling fluids and cuttings were discharged into the adjacent pits, allowing settling in one pit with water decanting into the adjacent pit. Drilling muds were used during the course of drilling the surface collar and pilot hole, The surface collar was approximately S.0 feet in diameter, and the pilot hole was 11 Inches in diameter. The collar was comprised of two components; a surface concrete pad and a liner or casing that extends to bedrock. A concrete cantering base is at the bottom of the liner'. The concrete pad was poured around the liner and was approximately 14'x 30' x 2'. Hopvever, the liner extends through the pad, reducing the amount of concrete Headed to construct the pad, Approximately 8.9 CY of concrete was required to construct the pad. After the collar and liner are in place and the pilot hole was completed, raise boring methods were used to complete the hole. The hole was reamed to a final diameter of 4.33' and a 48" diameter steel casing was cemented in place from 50' below the bottom of Tweatymile 3andstona to lire top of the concrete centering pad. The remainder of the easing below the cement hangs is the hole. The hole is approximately 1,100 feet in depth. The 4' diameter casing extrudes 4" to 6" out of the concrete surface pad. A cap to regulate intake air flow was installed. A fence was installed around the drill pad to prevent access by cattle, after completion of the hole. Access wag derived from as existing light-use road rynning up to an old electrical borehole. A series of culverts were placed under the existing mad and their locations shown on Figure 23, t3erretal Location of 8scape Sltaft. The design for the culverts can be found in Exhibit 8D, Escape 8haft/Light-Auiy Road Culvert Design. TCC MR 02-178 2.05-45.2 04/08/02