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 15

Agapito Associates, Inc.

Figure 5b. Barrier Pillar Design Chart—Collom D1/D2 Seam
Design
Depth of Cover, ft 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 13
190 20.5 21.2 21.9 22.5 23.1 23.7 24.3 24.9 25.4 25.9 26.5 27.0 27.5
210 23.1 23.9 24.6 25.4 26.1 26.8 27.4 28.1 28.7 29.3 29.9 30.5 31.1
230 25.7 26.6 27.4 28.2 29.0 29.8 30.6 31.3 32.1 32.8 33.5 34.1 34.8
250 28.0 29.2 30.2 31.1 32.0 32.9 33.8 34.6 35.4 36.2 37.0 37.7 38.5
270 28.0 30.0 32.0 34.0 35.0 36.0 36.9 37.9 38.8 39.6 40.5 41.3 42.2
290 28.0 30.0 32.0 34.0 36.0 38.0 40.0 41.1 42.1 43.1 44.0 45.0 45.9
310 30.0 31.1 32.1 34.0 36.0 38.0 40.0 42.0 44.0 46.0 47.6 48.6 49.6
330 32.3 33.4 34.5 35.5 36.6 38.0 40.0 42.0 44.0 46.0 48.0 50.0 52.0
350 34.5 35.7 36.8 38.0 39.1 40.2 41.2 42.2 44.0 46.0 48.0 50.0 52.0
370 36.7 38.0 39.2 40.4 41.6 42.8 43.9 45.0 46.1 47.1 48.2 50.0 52.0
390 38.9 40.3 41.6 42.9 44.2 45.4 46.6 47.8 48.9 50.1 51.2 52.2 53.3
410 41.1 42.5 44.0 45.4 46.7 48.0 49.3 50.6 51.8 53.0 54.2 55.3 56.4
430 43.3 44.8 46.4 47.8 49.3 50.7 52.0 53.3 54.6 55.9 57.2 58.4 59.6
Coal strength, psi 821 Mining width, ft 11.50 No. web pillars 19
Pillar widths in italics have width-to-height ratios of 0.8
Mining Height, ft
20
25
30
35
40
45
50
55
60
190 210 230 250 270 290 310 330 350 370 390 410 430REQUIRED BARRIER PILLAR WIDTH, ft DEPTH OF COVER, ft
7
7.5
8
8.5
9
9.5
10
10.5
11
11.5
12
12.5
13
Mining
Height,
ft