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 9

Agapito Associates, Inc.

Figure 3b. Barrier Pillar Design Chart—Collom B2/B3 Seam
Design
Depth of Cover, ft 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9
110 10.0 10.8 11.5 12.2 12.8 13.4 13.9 14.4 14.9 15.4 15.9 16.4 16.8
130 12.0 13.1 14.0 14.8 15.6 16.3 17.1 17.7 18.4 19.0 19.6 20.2 20.7
150 12.0 14.0 16.0 17.5 18.5 19.3 20.2 21.0 21.8 22.6 23.3 24.0 24.7
170 13.8 14.9 16.0 18.0 20.0 22.0 23.4 24.3 25.3 26.2 27.1 27.9 28.7
190 15.6 16.8 18.0 19.1 20.1 22.0 24.0 26.0 28.0 29.8 30.8 31.8 32.8
210 17.4 18.8 20.1 21.4 22.5 23.6 24.7 26.0 28.0 30.0 32.0 34.0 36.0
230 19.3 20.8 22.3 23.6 24.9 26.2 27.4 28.5 29.6 30.7 32.0 34.0 36.0
250 21.1 22.8 24.4 25.9 27.4 28.7 30.1 31.3 32.5 33.7 34.9 36.0 37.0
270 22.9 24.8 26.6 28.2 29.8 31.3 32.7 34.1 35.5 36.8 38.0 39.3 40.4
290 24.7 26.8 28.7 30.5 32.2 33.9 35.4 37.0 38.4 39.8 41.2 42.6 43.9
310 26.6 28.8 30.9 32.8 34.7 36.4 38.1 39.8 41.4 42.9 44.4 45.9 47.3
330 28.4 30.8 33.0 35.1 37.1 39.0 40.8 42.6 44.3 46.0 47.6 49.2 50.7
350 30.2 32.8 35.1 37.4 39.5 41.6 43.5 45.4 47.3 49.0 50.8 52.5 54.1
Coal strength, psi 495 Mining width, ft 11.50 No. web pillars 19
Pillar widths in italics have width-to-height ratios of 0.8
Mining Height, ft
0
10
20
30
40
50
60
110 130 150 170 190 210 230 250 270 290 310 330 350REQUIRED BARRIER PILLAR WIDTH, ft DEPTH OF COVER, ft
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
Mining
Height,
ft