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Chapter V <br /> In addition, Mid-Continent wishes to see the winter recreational potential of the Coal <br /> Basin developed, and would use the roads in connection with that use. See <br /> Postmining Land Use at the beginning of this Chapter V, and the discussion of <br /> Postmining Land Use, Chapter VII. <br /> c. Adit/Rock Tunnel Area. <br /> The adit/rock tunnel area will be reclaimed during the second season after mining <br /> ceases with procedures virtually the same as employed at the portal areas. <br /> The adit/rock tunnel will be sealed in accordance with the plan approved by Minor <br /> Revision on July 11, 1985. The plan was submitted to comply with stipulation No. 4. <br /> The plan calls for concrete seals to be constructed above and below the Cozette, <br /> Rollins and Middle sandstones, as well as the tunnel portals. <br /> In order to assure proper sealing, the concrete seals will be keyed 24 inches into the <br /> bedrock around the perimeter to prevent leakage around the seals. <br /> The maximum water head pressure occurs against seal No. 1. <br /> Calculations were made on the assumption that the full length of tunnel, behind the <br /> bulkhead, will fill with water. Calculations for seal strength were based on the <br /> assumption that the concrete and steel bulkhead would fail in shear in a horizontal <br /> plane. <br /> A 36" concrete wall can support a total force of 4,200,000 lb. before failure. The <br /> maximum head is 143 feet, creating a force of 1,500,000 lb. The factor of safety is 3. <br /> Calculations and design specification are included in App. II-B-3. <br /> The structures and buildings will be removed, and the foundations will be broken up <br /> and used for sealing the portals (in accordance with MSHA regulations Sec. <br /> 75.1711-2 ) and the approved rock tunnel sealing plan. <br /> The concrete foundations, placed against the portal face-up cut, will serve as a <br /> foundation for backfilling. <br /> During construction of the Rock Tunnel, the North Fork of Dutch Creek was <br /> channelized, using a 10' diameter culvert. Since this is considered to be a <br /> temporary fill, with an estimated life span of up to 40 years (1980-2020), the fill <br /> materials (B and C horizon) around the culvert will be excavated and placed on <br /> either the face-up area or the permanent rock fill disposal area. The culvert will be <br /> removed and the channel stabilized. <br /> 24 <br /> �I <br />