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2.05 APPLICATION FOR PERMIT FOR SURFACE OR UNDERGROUND MINING ACTIVITIES - MINIMVM REQUIREMENTS FOR OPERATION AND RECLAMATION PLANS. • A11 development entries are roof-bolted in accordance with the approved roof control plan. 600 to 800 feet of overburden • Protective pillars in these buffer zones are designed to provide safety factors in excess of 1. using the Wilson pillar design method. (See Pillar Stability Calculations in Volume 2) • Panel designs for specific development geometries and mining heights vary within these buffer zones and are optimized for MER, however the minimum safety factor criteria for all panels developed within these buffer zones remains constant at 1.5. • Secondary extraction or retreat mining is limited to the recovery of floor coal within previously developed entries. • All development entries are roof-bolted in accordance with the approved roof control plan. The remaining permanent protective pillars have a safety factor adequate for permanent support, but a smaller safety factor than the pillars directly under the Renewable Resource Lands (refer to Pillar Stability • Calculations, Volume 2). Because of this, pillar yielding will occur at the distance greatest from the Renewable Resource Lands should unexpected and excessive loading occur. The Operator and its assigns indemnifies the United States against any liability for damage to life or property arising from the undermining of Stevens Gulch Road as the result of Technical Revision 17 and 19 to the mining permit application. Mine Layout and Design Both the East and West mine extracted coal from the "D" Seam. In the "D" Seam, the mine is layed out in a series of main, submain and panel entries. The orientation and distance of the workings were designed for maximum economic recovery and mining efficiency with respect to the in-situ features such as faults and the strike and dip of the coal seam. Overall design also maximized the efficiency of the mine ventilation system. Specific pillar and section dimensions were engineered to provide adequate ground support and pillar recovery efficiency. Room and pillar panels were developed off the main and submain entries with barrier pillars left for protection. Pillars and barrier pillars were recovered to the extent safety to the miners and machinery allowed. Where conditions precluded total extraction, pillars were only partially removed, which temporarily delayed the planned roof • falls associated with pillar recovery. Permit Renewal Rn-ov Cy/e/ca) - 2 - 01/03 rnR-,e6