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 17

Agapito Associates, Inc.

Figure 6a. Web Pillar Design Chart—Collom E2 Seam
Design
Depth of Cover, ft 4 4.33 4.67 5 5.33 5.67 6 6.33 6.67 7 7.33 7.67 8
140 47 49 51 54 56 58 59 61 65 68 71 74 77
170 53 55 58 60 62 64 67 69 71 73 75 77 79
200 58 61 63 66 68 71 73 76 78 81 83 85 87
230 63 66 69 72 74 77 80 83 85 88 90 93 95
260 67 71 74 77 80 83 86 89 92 95 97 100 103
290 74 76 79 82 86 89 92 95 98 101 104 107 110
320 80 83 86 89 92 95 98 101 105 108 111 114 118
350 86 89 93 96 99 102 105 108 111 114 118 121 125
380 92 96 99 103 106 110 113 116 119 122 125 128 132
410 98 102 106 110 114 117 121 124 128 131 134 137 140
440 104 108 112 117 121 125 129 132 136 140 143 147 150
470 109 114 119 123 128 132 136 140 144 148 152 156 160
500 115 120 125 130 135 140 144 148 153 157 161 165 169
Coal strength, psi 900 Mining width, ft 11.50 No. web pillars 19
Pillar widths in italics have width-to-height ratios of 0.8
Mining Height, ft
3
4
5
6
7
8
9
10
11
12
13
14
15
36
48
60
72
84
96
108
120
132
144
156
168
180
140 170 200 230 260 290 320 350 380 410 440 470 500 REQUIRED WEB PILLAR WIDTH, ftREQUIRED WEB PILLAR WIDTH, in DEPTH OF COVER, ft
4
4.33
4.67
5
5.33
5.67
6
6.33
6.67
7
7.33
7.67
8
Mining
Height,
ft