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App. II-B-2 <br /> in mining technology has the mine life continued into the third decade. <br /> Mid-Continent introduced longwall mining in 1981 in order to continue operations <br /> under the extreme depth of cover which overlies all the remaining coal reserves. <br /> Until 1987, when the Adit/Rock Tunnel was extended to both the B-bed and the <br /> Middle-bed coal seams, allowing major changes in the underground operations, the <br /> main entry through each portal was the major transportation artery for each mine, <br /> and the mines were not connected. <br /> Machinery, parts and personnel entered each mine through the portal; the coal was <br /> transported from the working area to the surface through the portal. <br /> The steep terrain at all the portal areas also made the portal yards virtually the only <br /> place for storage of coal, materials and supplies, and for trash disposal, and for the <br /> necessary support facilities, such as fans and the hoist. <br /> The Adit/Rock Tunnel has not yet been extended to the workings of Nos. 3, 4 and 5, <br /> although these areas are inactive at the time of permit submittal (1987). If these <br /> workings are re-activated prior to completion of the Adit/Rock Tunnel, the <br /> operations will utilize main entries, portals and haul roads as previously. <br /> 4. Operations - Surface. <br /> The haul roads offer the only surface access to the portals. Prior to extension of the <br /> tunnel to Nos. 1 and 2, the only means to transport coal from the mines has been <br /> down the haul roads. <br /> Coal haulage through the portal required that mountain trucks pick up the coal from <br /> the portal yard and transport it down the haul roads to raw coal storage. Mountain <br /> trucks have made a steady, continuous circuit up and down the roads over the <br /> three decades of operations. <br /> To reach the mines through the portals, employees were bussed up the haul roads <br /> to the portal yards, unloaded, and then carried underground through the main entry <br /> on mantrips. All machinery parts and materials followed the same route. <br /> Because of the elevation and terrain, maintaining access to the portals has been a <br /> primary, but often difficult, operating requirement. Heavy snow and avalanches must <br /> be cleared from the roads regularly throughout the long winter months. The roads <br /> must also be maintained against the natural tendency of the terrain to slough. <br /> 5. Coal Refuse. <br /> 3 <br />