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 B-2
Agapito Associates, Inc.

Figure B-1a. J Pit, G2 Seam Web Pillar Design Chart
534-40 Trapper [534-40 Trapper_Design Charts18JUL2018.pptx]:dc/smvf (7-18-2018)
Design
Depth of Cover (ft) 3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6
50 35 37 39 41 43 45 47 48 50 52 54 56 58
65 39 39 40 41 43 45 47 48 50 52 54 56 58
80 45 46 46 47 48 49 50 51 52 53 54 56 58
95 50 52 53 54 55 56 57 58 58 59 60 61 62
110 56 57 59 60 61 62 63 64 65 66 67 68 69
125 61 63 64 66 67 68 70 71 72 73 74 76 77
140 66 68 70 71 73 74 76 77 79 80 81 83 84
155 73 74 75 77 78 80 82 83 85 86 88 89 91
170 79 81 83 84 86 87 88 90 91 93 94 96 98
185 84 87 89 91 93 95 97 98 100 101 102 104 105
200 89 92 94 97 99 102 104 106 108 110 112 113 115
215 94 97 99 102 105 107 110 112 115 117 120 122 124
230 98 101 104 107 110 113 116 118 121 124 126 129 131
Coal Strength (psi)568 Mining Width (ft)11.50 No. Web Pillars 19
Pillar widths in italics have width-to-height ratios of 0.8
Mining Height (ft)
2
3
4
5
6
7
8
9
10
11
12
24
36
48
60
72
84
96
108
120
132
144
50 70 90 110 130 150 170 190 210 230 REQUIRED WEB PILLAR WIDTH (ft)REQUIRED WEB PILLAR WIDTH (inches)DEPTH OF COVER (ft)
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.8
6.0
Mining
Height
(ft)