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 18

Agapito Associates, Inc.

Figure 6b. Barrier 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 10.4 10.7 11.1 11.4 11.8 12.1 12.4 12.7 13.0 13.2 13.5 13.8 14.0
170 13.0 13.5 14.0 14.4 14.9 15.3 15.7 16.1 16.5 16.9 17.2 17.6 17.9
200 15.7 16.3 16.9 17.5 18.0 18.6 19.1 19.6 20.0 20.5 21.0 21.4 21.8
230 16.0 17.4 18.7 20.0 21.2 21.8 22.4 23.0 23.6 24.2 24.7 25.3 25.8
260 17.7 18.4 19.1 20.0 21.4 22.7 24.0 25.4 26.7 27.8 28.5 29.1 29.8
290 20.0 20.8 21.6 22.3 23.0 23.7 24.4 25.4 26.7 28.0 29.4 30.7 32.0
320 22.3 23.2 24.1 24.9 25.7 26.5 27.3 28.0 28.7 29.4 30.1 30.7 32.0
350 24.6 25.6 26.6 27.5 28.4 29.3 30.1 31.0 31.8 32.5 33.3 34.0 34.8
380 27.0 28.0 29.1 30.1 31.1 32.1 33.0 33.9 34.8 35.7 36.5 37.4 38.1
410 29.3 30.5 31.6 32.7 33.8 34.9 35.9 36.9 37.9 38.8 39.7 40.7 41.5
440 31.6 32.9 34.2 35.4 36.5 37.7 38.8 39.9 40.9 42.0 43.0 44.0 44.9
470 33.9 35.3 36.7 38.0 39.2 40.5 41.7 42.8 44.0 45.1 46.2 47.3 48.3
500 36.2 37.7 39.2 40.6 41.9 43.3 44.6 45.8 47.1 48.3 49.4 50.6 51.7
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
10
15
20
25
30
35
40
45
50
55
140 170 200 230 260 290 320 350 380 410 440 470 500REQUIRED BARRIER PILLAR WIDTH, ft 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