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 12

Agapito Associates, Inc.

Figure 4b. Barrier Pillar Design Chart—Collom C3/C5 Seam
Design
Depth of Cover, ft 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11
130 10.4 10.9 11.3 11.7 12.0 12.4 12.7 13.1 13.4 13.7 14.0 14.4 14.7
160 13.4 14.0 14.6 15.1 15.6 16.1 16.6 17.1 17.5 17.9 18.3 18.7 19.1
190 16.5 17.2 17.9 18.6 19.3 19.9 20.5 21.1 21.7 22.2 22.8 23.3 23.8
220 19.5 20.4 21.3 22.1 22.9 23.7 24.5 25.2 25.9 26.6 27.2 27.9 28.5
250 20.0 22.0 24.0 25.7 26.6 27.5 28.4 29.3 30.1 30.9 31.7 32.5 33.2
280 21.5 22.5 24.0 26.0 28.0 30.0 32.0 33.4 34.4 35.3 36.2 37.1 38.0
310 24.1 25.2 26.3 27.3 28.4 30.0 32.0 34.0 36.0 38.0 40.0 41.8 42.8
340 26.7 27.9 29.2 30.4 31.5 32.6 33.6 34.7 36.0 38.0 40.0 42.0 44.0
370 29.3 30.7 32.1 33.4 34.6 35.8 37.0 38.2 39.3 40.3 41.4 42.4 44.0
400 31.9 33.4 34.9 36.4 37.8 39.1 40.4 41.7 42.9 44.1 45.2 46.4 47.5
430 34.5 36.2 37.8 39.4 40.9 42.4 43.8 45.2 46.5 47.8 49.1 50.3 51.5
460 37.1 39.0 40.7 42.4 44.1 45.6 47.2 48.7 50.1 51.5 52.9 54.3 55.6
490 39.7 41.7 43.6 45.4 47.2 48.9 50.6 52.2 53.7 55.3 56.8 58.2 59.6
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
60
130 160 190 220 250 280 310 340 370 400 430 460 490REQUIRED BARRIER PILLAR WIDTH, ft DEPTH OF COVER, ft
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
10.5
11
Mining
Height,
ft