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disturbed areas (including topsoil stockpiles) will be stabilized with temporary vegetation, and structures <br />• will be painted in neutral earth-tone colors to blend with the natural surroundings. <br />As shown on Map 23, additional entries will be driven to the north from the ventilation shaft site. These <br />entries will be needed to maximize the efficiency of the ventilation system. The entries will be driven in <br />the same manner as is used in TCC's development work, i.e. continuous miners and shuttle cars. <br />No. 7 North Escape Shaft (Section 20, TSN, R86V1~ <br />A 1,066 foot escape borehole shaft was constructed into #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 <br />construction of the shaft utilized raise drilling techniques. It is anticipated that the escape shaft will be <br />utilized for approximately ten yeazs. 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' <br />was constructed at the resulting site in 1,450 CY of cut and fill. Available topsoil was salvaged and <br />stockpiled for future reclamation of the site immediately northeast of the drilled pad. Approximately 18" <br />of topsoil derived from Cochetopa Loam is available for salvaging (222 CY). Casing and other drilling <br />supplies were stockpiled on the borehole pad. <br />After topsoil removal, two mud pits with dimensions of 10' x ]0' x 7.5' were dug adjacent to the drill <br />hole. Drilling fluids and cuttings were dischazged into the adjacent pits, allowing settling in one pit with <br />water decanting into the adjacent pit. Drilling muds were used during the course of drilling the surface <br />collaz and pilot hole. The surface collaz was approximately 5.0 feet in diameter, and the pilot hole was 11 <br />• inches in diameter. <br />The collaz was comprised of two components; a surface concrete pad and a liner or casing that extends to <br />bedrock. A concrete centering base is at the bottom of the liner. <br />The concrete pad was poured azound the liner and was approximately 14'x 10' x 2'. However, the liner <br />extends through the pad, reducing the amount of concrete needed to construct the pad. Approximately 8.9 <br />CY of concrete was required to construct the pad. <br />After the collaz and liner are in place and the pilot hole was completed, raise boring methods were used to <br />complete the hole. The hole was reamed to a final diameter of 4.33' and a 48" diameter steel casing was <br />cemented in .place from 50' below the bottom of Twentymile Sandstone to the top of the concrete <br />centering pad. The remainder of the casing below the cement hangs in the hole. The hole is <br />approximately 1,100 feet in depth. The 4' diameter casing extrudes 4" to 6" out of the concrete surface <br />pad. A cap to regulate intake air flow was installed. A fence was installed azound the drill pad to prevent <br />access by cattle, after completion of the hole. <br />Access was derived from an existing light-use road running up to an old electrical borehole. A series of <br />culverts were placed under the existing road and their locations shown on Figure 23, General Location of <br />Escape Shaft. The design for the culverts can be found in Exhibit 8D, Escape Shaft/Light-Duty Road <br />Culvert Design. TCC constructed an additiona125-foot wide road at a 4% grade to access the site. The <br />1,300-foot long road is graveled with 0.5' of 6-inch pit run gravel. <br />• <br />MR 02-179 2.05-45.3 08/06/02 <br />