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• 1.0 SLiMMARY <br />The proposed mining geometry for Panel B consists of pillars on <br />70-ft by 140-ft centers, a maximum entry width of 20 ft, an <br />extraction height of up to 16 ft and a maximum overburden depth <br />of 800 ft. This mining geometry results in a factor of safety <br />greater than 1.5 with respect to pillar load carrying capacity <br />and the anticipated load on the pillar. This factor of safety <br />determination uses the Wilson pillar design method for pillar <br />load carrying capacity and tributary area loading for estimated <br />pillar load. <br />A buffer zone is required between the caved area and the area of <br />floor coal mining. The minimum required width of the buffer zone <br />is 140 ft, or two pillar widths. The maximum mining height in <br />the buffer zone area is 12 ft. <br />This pillar stability analysis uses existing physical rock <br />properties data from the Orchard Valley mine site and the <br />historical mining experience at the mine site. <br />• <br />• <br />Cyprus Orchard Velley Mire February 6, 1992 <br />Parel B Pillar Analysis page i <br />