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FEB.20.2002 5~44PM <br />TWENTYMILE CORL ENVIRONMENTRL <br />N <br /> <br />The collar was comprised of two components; a surface concrete pad and a liner or casing Wet extends to bedrock, <br />A concrete ceraering base is at the bottom of the liner. <br />The concrete pad was pouted around the later and Was approximately 14'x 10' x 2'. However, the liner extends <br />througb the pad, reducing the amount of concrete needed to constmct the pad. Approximately 8.9 CY of concrete <br />was required to construct the pad. <br />After the collar and Baer 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 s}.33' and a 48" diameter steel casing was comented in place <br />from 50' below the bottom of Tweatymile Sandstone to the top of the concrete cantering pad. The remainder of the <br />casing below the cement hangs in the hole. The hole is approximately 1,100 feet in depth. Tha 4' diameter casing <br />extrudes 4" W 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, 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 culverts <br />were placed under the existing road and their locations shown on Figure 23, Creneral Location of Escape Shaft. The <br />design for the culverts cau be found in Exhibit SD, Escape Shaft/Light-Duty Road Culvert Design. TCC <br />constructed an additional 25-hoot wide road at a 4% grade !o access the site. The 1,300•Poot long road is graveled <br />with 0.5' of 6•inch pit run gravel. <br />02-176 2.05-45.3 02/20/02 <br />