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are no longer needed they will be grouted from the bottom of the casing to within three feet of the surface. <br />The remaining four feet of casing will be cut off and discazded and then the azea graded, topsoiled and <br />seeded as per the approved plan. The holes will be located within the existing vent shaft pad disturbance <br />azea. <br />Concurrent with road construction a power distribution line will be extended from the existing substation <br />to the pad-mounted transformer at the shaft site. The power distribution line is approximately 3,600' long <br />with a total of 12 power poles. <br />In order to minimize potential environmental and aesthetic impacts associated with the NW Mains <br />ventilation shaft and fan installation, surface drainage at the shaft site will be handled by an upgradient <br />diversion ditch, perimeter berms, and gravel surfacing under an SAE, the limited road drainage will be <br />handled by designed drainage structures, active use areas are graveled to control dust and drainage, other <br />disturbed azeas (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 Escane Shaft (Section 20, TSN, R86W1 <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 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' <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 10' x 7.5' were dug adjacent to the drill <br />hole. Drilling fluids and cuttings were discharged 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 />collar and pilot hole. The surface collar 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 collar 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 />MR 03-182 2.05.45.3 02/25/03 <br />