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into the adjacent pit. Drilling muds were used during the cowse of drilling the surface collar and pilot hole. The <br />surface collar was approximately 5.0 feet in diameter, and the pilot hole was 11 inches in diameter. <br />The collar was comprised of two components; a surface concrete pad and a liner or casing that extends to bedrock. <br />A concrete centering base is at the bottom of the liner. <br />The concrete pad was poured around the liner and was approximately 14'x 10' x 2'. However, the liner extends <br />through the pad, reducing [he amount of concrete needed to construct the pad. Approximately 8.9 CY of concrete <br />was required to construct [he pad. <br />Afrer the collar and liner are 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' and a 48" diameter steel casing was cemented in place <br />from 50' below the bottom of Twentymile Sandstone to the top of the concrete centering pad. The remainder of the <br />casing below the cement hangs in the hole. The hole is approximately 1,100 feet in depth. The 4' diameter casing <br />extrudes 4" to 6" out of the concrete surface pad. A cap to regulate intake air flow was installed. A fence was <br />installed around the drill pad to prevent access by cattle, aRer completion of the hole. <br />Access was derived from an existing light-use road running up to an old electrical borehole. A series of culverts <br />were placed under the existing road and their locations shown on Figure 23, General Location of Escape Shaft. The <br />design for the culverts can be found in Exhibit 8D, Escape Shaft/Light-Duty Road Culvert Design. TCC <br />constructed an additional 25-foot wide road at a 4% grade to access the site. The 1,300-foot long road is graveled <br />with 0.5' of 6-inch pit run gravel. <br />MR 02-176 2.05-45,3 02/20/02 <br />