2022-01-27_PERMIT FILE - C1981019 ‎(7)‎

• Permit No: C1981019
• IBM Index Class Name: Permit File
• Doc Date: 1/27/2022
• Doc Name: Addendum Collom and South Taylor Highwall Mining Geotechnical Design
• Section_Exhibit Name: Volume 20 Exhibit 27 Item 7
• Media Type: D
• Archive: No

Mr. Lee Sampson
December 7, 2021
Page 14

Agapito Associates, Inc.

Figure 5a. Web Pillar Design Chart—Collom D1/D2 Seam
Design
Depth of Cover, ft 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 13
190 83 86 90 93 96 100 103 106 110 113 116 120 125
210 88 92 95 99 103 106 110 113 117 120 124 127 130
230 93 97 101 105 109 113 116 120 124 128 131 135 138
250 98 102 107 111 115 119 123 127 131 135 139 142 146
270 103 107 112 116 121 125 129 134 138 142 146 150 154
290 108 112 117 122 126 131 136 140 144 149 153 157 162
310 112 117 122 127 132 137 142 146 151 156 160 165 169
330 117 122 127 133 138 143 148 153 158 162 167 172 177
350 123 127 132 138 143 148 154 159 164 169 174 179 184
370 129 134 139 143 149 154 160 165 170 176 181 186 191
390 136 141 146 151 156 160 165 171 177 182 188 193 199
410 142 148 153 158 163 168 173 178 183 189 194 200 206
430 149 155 160 166 171 176 181 186 191 196 201 207 213
Coal strength, psi 821 Mining width, ft 11.50 No. web pillars 19
Pillar widths in italics have width-to-height ratios of 0.8
Mining Height, ft
6
7
8
9
10
11
12
13
14
15
16
17
18
72
84
96
108
120
132
144
156
168
180
192
204
216
190 210 230 250 270 290 310 330 350 370 390 410 430 REQUIRED WEB PILLAR WIDTH, ftREQUIRED WEB PILLAR WIDTH, in DEPTH OF COVER, ft
7
7.5
8
8.5
9
9.5
10
10.5
11
11.5
12
12.5
13
Mining
Height,
ft