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<br />Because longwall mining usually extracts the entire seam height in a solid block of coal, coal reserve <br />extraction is extremely high. Extraction rates approaching 100 percent can be achieved with longwall <br />mining within individual longwall panels. Maximizing the resource recovery is an impoRant factor in <br />' mine planning. <br />' The productivity of longwall faces in the United States has dramatically improved in recent years due <br />to improved cutters, face conveyors and roof supports and application of electronic technology. While <br />1000 tons per shift was considered a good figure only a few years ago, the current productivity figures <br />' in the western mines have reached as much as 3000 to 8000 tons per shift. The Deserado Mine coal <br />deposit is suitable for this high recovery, high production technology. Based on experience of the <br />' longwall system used in the Deserado mine, Western Fuels has assumed a production rate per longwall <br />face of 3,500 tons per shift. <br />' Longwall mining has a better safety record than continuous mining. The danger from roof falls has <br />been reduced because the roof supports, which are set in a straight line with skin to skin contact, form <br />' a continuous canopy of steel which protects the miners. <br />Because longwall mining has advantages (higher recovery, higher productivity, and better safety record) <br />' over room-and-pillar mining with continuous miners, Western Fuels has designed the mine plan to <br />maximize the use of longwall mining within the constraints of the property boundaries, resource <br />characteristics and viable equipment specifications. Western Fuels considers longwall equipment capable <br />of a maximum seam height of thirteen feet and a minimum seam height of four feet to be optimal for <br />the Deserado Mine. Coal recovery from areas not suited for longwall mining (areas within the property <br />' not susceptible to practical longwall panel layout) will be accomplished with room-and-pillaz mining <br />using continuous miners if economically and technically feasible. Continuous miners will also be used <br />' to drive entries and to develop longwall panels. Figure 4-3 shows a typical longwall retreat panel in <br />the Deserado Mine. <br />' The longwall panels are from 2500 feet to 8500 feet long and 600 to 800 feet wide. The 800 feet <br />panels will be developed beginning with the sixth longwall panel (LW6). <br />' 4.2.4 Mitigation of C ~bsid n F.ff t Rio Blanco County Road 65, a waterline and a transmission <br />line (both lines serving the mine) cross over the mining area where subsidence is expected. <br />t The county road will be monitored and maintained to repair any cracks that could create a safety hazazd <br />or delay traffic whenever coal is extracted underneath the road. <br />23 <br /> <br />