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March 21, 2014 <br />Page 48 <br />Design Depth <br />Mining Height (ft) <br />of Cover (ft) <br />4 <br />4.25 <br />4.5 <br />4.75 <br />5 <br />5.25 <br />5.5 <br />5.75 <br />6 <br />6.25 <br />6.5 <br />6.75 <br />7 <br />100 <br />45 <br />47 <br />49 <br />50 <br />52 <br />53 <br />55 <br />56 <br />58 <br />60 <br />63 <br />65 <br />68 <br />125 <br />52 <br />53 <br />55 <br />57 <br />59 <br />60 <br />62 <br />64 <br />65 <br />67 <br />69 <br />70 <br />72 <br />150 <br />57 <br />59 <br />61 <br />63 <br />65 <br />67 <br />69 <br />71 <br />73 <br />75 <br />76 <br />78 <br />80 <br />175 <br />63 <br />65 <br />67 <br />69 <br />72 <br />74 <br />76 <br />78 <br />80 <br />82 <br />84 <br />86 <br />88 <br />200 <br />68 <br />70 <br />73 <br />75 <br />78 <br />80 <br />82 <br />85 <br />87 <br />89 <br />91 <br />93 <br />95 <br />225 <br />75 <br />77 <br />79 <br />81 <br />83 <br />86 <br />88 <br />91 <br />93 <br />96 <br />98 <br />100 <br />103 <br />250 <br />82 <br />84 <br />87 <br />89 <br />91 <br />93 <br />95 <br />97 <br />100 <br />102 <br />105j <br />107 <br />110 <br />275 <br />88 <br />91 <br />94 <br />96 <br />99 <br />101 <br />103 <br />106 <br />108 <br />110 <br />112 <br />115 <br />117 <br />300 <br />95 <br />98 <br />101 <br />104 <br />106 <br />109 <br />112 <br />114 <br />117 <br />119 <br />122 <br />124 <br />126 <br />325 <br />101 <br />105 <br />108 <br />111 <br />114 <br />117 <br />120 <br />123 <br />125 <br />128 <br />131 <br />133 <br />136 <br />350 <br />108 <br />111 <br />115 <br />118 <br />121 <br />125 <br />128 <br />131 <br />134 <br />137 <br />140 <br />143 <br />146 <br />375 <br />114 <br />118 <br />121 <br />125 <br />129 <br />132 <br />136 <br />139 <br />142 <br />146 <br />149 <br />152 <br />155 <br />400 <br />120 <br />124 <br />128 <br />132 <br />136 <br />140 <br />144 <br />147 <br />151 <br />154 <br />158 <br />161 <br />165 <br />Coal Strength (psi) 651 Mining Width (ft) 11.50 <br />'Pillar widths in italics have width -to- height ratios of 0.8 <br />:8 <br />N <br />m <br />L <br />c 120 <br />2 <br />0 <br />Q <br />J <br />a. <br />e 60 <br />D <br />1� <br />0 4- <br />50 <br />/tlE <br />i <br />A* <br />l <br />W' <br />j <br />4 <br />15 <br />10 <br />_0 <br />Q <br />J <br />J <br />CL <br />e <br />5 5 <br />W <br />I 4 I I I I E 0 <br />100 150 200 250 300 350 400 450 <br />DEPTH OF COVER (ft) <br />No. Web Pillars 19 <br />Figure 32a. Web Pillar Design Chart —West Pit, D2 Seam <br />Agapito Associates, Inc. <br />Mining <br />Height <br />(ft) <br />-t 4 <br />4.25 <br />- r�— 4.5 <br />4.75 <br />5 <br />5.25 <br />5.5 <br />5.75 <br />6 <br />6.25 <br />—6.5 <br />6.75 <br />7 <br />