2023-07-14_PERMIT FILE - C1981010 ‎(16)‎

• Permit No: C1981010
• IBM Index Class Name: Permit File
• Doc Date: 7/14/2023
• Doc Name: Summary of Geotechnical Design andf Operational Cnsiderations for Highwall Mining-I,J,N, and L Pits
• Section_Exhibit Name: Appendix X
• Media Type: D
• Archive: No

January 2, 2020 Page A-2
Agapito Associates, Inc.

Figure A-1a. I Pit, F Seam Web Pillar Design Chart
Design
Depth of Cover (ft) 3 3.3 3.6 3.9 4.2 4.5 4.8 5.1 5.4 5.7 6 6.3 6.6
50 31 32 35 38 41 44 47 49 52 55 58 61 64
65 37 39 40 41 43 44 47 49 52 55 58 61 64
80 43 45 47 48 49 51 52 53 55 56 58 61 64
95 49 51 53 54 56 58 59 61 62 63 65 66 68
110 54 56 58 60 62 64 66 68 69 71 73 74 76
125 59 61 64 66 69 71 73 75 77 79 80 82 84
140 65 67 69 72 74 77 79 81 84 86 88 90 92
155 71 74 76 79 81 83 85 88 90 93 95 98 100
170 76 79 83 86 89 91 93 95 97 100 102 105 107
185 80 84 88 92 95 99 102 104 107 109 111 113 115
200 84 89 93 97 101 105 109 112 116 119 122 124 126
215 89 93 98 102 107 111 115 119 123 127 130 134 137
230 93 98 103 107 112 117 121 125 129 134 138 142 145
Coal Strength (psi)540 Mining Width (ft)11.50 No. Web Pillars 19
Pillar widths in italics have width-to-height ratios of 0.8
Mining Height (ft)
534-40 Trapper [534-40 Trapper_Design Charts18JUL2018.pptx]:dc/smvf (7-18-2018)
2
3
4
5
6
7
8
9
10
11
12
13
24
36
48
60
72
84
96
108
120
132
144
156
50 70 90 110 130 150 170 190 210 230 REQUIRED WEB PILLAR WIDTH (ft)REQUIRED WEB PILLAR WIDTH (inches) DEPTH OF COVER (ft)
3.0
3.3
3.6
3.9
4.2
4.5
4.8
5.1
5.4
5.7
6.0
6.3
6.6
Mining
Height
(ft)