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to control dust and drainage, other disturbed areas (including topsoil stockpiles) are stabilized with temporary <br />vegetation, and structures are painted in neutral earth -tone colors to blend with the natural surroundings. <br />As shown on Map 23, additional entries were driven to the north from the ventilation shaft site. These entries are <br />needed to maximize the efficiency of the ventilation system. The entries were driven in the same manner as TLC's <br />development work, i.e. continuous miners and shuttle cars. <br />Buffalo Forge Fan Silencer (MR 03-187) <br />A new silencer will be installed on the Buffalo fan at the NW Mains Ventilation Shaft location. Installation of the <br />silencer will require construction of foundations utilizing concrete piers and concrete grade beams. The foundation <br />will require eight concrete piers (6 -inch radius x 20 feet deep) and then placement of two concrete grade beams (12" x <br />2' x 31') on top of the piers. The concrete grade beams will be reinforced with three #5 rebar, and #4 stirrups spaced <br />at 8 inches on center within 3 feet of the piers, and spaced at 16 inches on center at all other locations.. The <br />installation of the silencer will occur within the existing disturbed area. The silencer is essentially a box containing <br />baffles, which will be approximately 31 feet long, 21 feet wide, and 20 feet high. The location of the vent shaft and <br />silencer is shown on Map 24. <br />No. 7 North Escape Shaft (Section 20. T5N. R86 <br />A 1,066 foot escape borehole shaft was constructed into the No. 7 entry of North Mains to allow emergency <br />evacuation of personnel from the development sections of the 9 -Right and 10 -Right gateroads. The construction of <br />the shaft utilized raise drilling techniques. It is anticipated that the escape shaft will be utilized for approximately ten <br />years. The site is shown on Figure 23, General Location of Escape Shaft. <br />The drilling of the shaft resulted in minimal surface disturbance. A drill pad approximately 200 x 200 feet was <br />constructed at the resulting site in 1,450 CY of cut and fill. Available topsoil was salvaged and stockpiled for future <br />reclamation of the site immediately northeast of the drilled pad. Approximately 18 inches of topsoil derived from <br />Cochetopa Loam is available for salvaging (222 CY). Casing and other drilling supplies were stockpiled on the <br />borehole pad. <br />After topsoil removal, two mud pits 10 x 10 x 7.5 feet were dug adjacent to the drillhole. Drilling fluids and <br />cuttings were discharged into the adjacent pits, allowing settling in one pit, with water decanting into the adjacent <br />pit. Drilling muds were used during the course of drilling the surface collar and pilot hole. <br />The surface collar was approximately 5.0 feet in diameter, and the pilot hole was 11 inches in diameter. The collar <br />was comprised of two components; a surface concrete pad and a liner or casing that extends to bedrock. A concrete <br />centering base is at the bottom of the liner. The concrete pad was poured around the liner and was approximately 14x <br />10 x 2 feet, however, the liner extends through the pad, reducing the amount of concrete needed to construct the pad. <br />Approximately 8.9 CY of concrete was required to construct the pad. <br />After the collar and liner were in place and the pilot hole was completed, raise -boring methods were used to complete <br />the hole. The hole was reamed to a final diameter of 4.33 feet and a 48 -inch diameter steel casing was cemented in <br />place from 50 feet below the bottom of Twentymile Sandstone to the top of the concrete centering pad. The <br />remainder of the casing below the cement hangs in the hole. The hole is approximately 1,100 feet in depth. The 4 - <br />foot diameter casing extrudes 4 to 6 inches out of the concrete surface pad. A cap to regulate intake air flow was <br />installed. A fence was installed around the drill pad to prevent access by cattle, after completion of the hole. Access <br />was derived from an existing light -use road running up to an old electrical borehole. A series of culverts were placed <br />under the existing road as shown on Figure 23, General Location of Escape Shaft. The design for the culverts can be <br />found in Exhibit 8D, Escape Shaft/Light-Duty Road Culvert Design. TCC constructed an additional 25 -foot wide <br />road at a 4 percent grade to access the site. The 1,300 -foot long road is graveled with 0.5 feet of 6 -inch pit -run gravel. <br />MR11-259 2.05-45.3 11/17/11 <br />