2014-06-19_PERMIT FILE - C1981019A

• Permit No: C1981019A
• IBM Index Class Name: Permit File
• Doc Date: 6/19/2014
• Doc Name: Geotechnical Stability Report For Highwall Mining At the Colowyo Coal Mine
• Section_Exhibit Name: Exhibit 23, Item 1
• Media Type: D
• Archive: Yes

July 23, 2013
Page 43
Design Depth
Mining Height (ft)
of Cover (ft)
8
9
10
11
12
13
14
15
16
17
18
19
20
60
6.5
7.2
8.0
8.9
9.7
10.4
11.2
12.0
12.9
13.7
14.4
15.2
16.0
80
6.5
7.2
8.0
8.9
9.7
10.4
11.2
12.0
12.9
13.7
14.4
15.2
16.0
100
7.9
8.4
8.9
9.4
9.9
10.4
11.2
12.0
12.9
13.7
14.4
15.2
16.0
120
9.5
10.1
10.7
11.3
11.8
12.4
12.9
13.4
13.9
14.4
14.9
15.3
16.0
140
11.0j
11.8
12.5
13.1
13.8
14.4
15.0
15.6
16.2
16.8
17.3
17.9
18.4
160
13.1
13.8
14.3
15.0
15.8
16.5
17.2
17.9
18.5
19.2
19.8
20.4
21.0
180
15.2
16.0
16.8
17.4
18.1
18.7
19.3
20.1
20.8
21.6
22.3
23.0
23.6
200
17.4
18.3
19.2
20.0
20.7
21.5
22.1
22.8
23.4
24.0
24.7
25.5
26.3
220
19.5
20.6
21.6
22.5
23.4
24.3
25.1
25.8
26.6
27.3
27.9
28.6
29.2
240
21.7
22.9
24.1
25.1
26.1
27.1
28.0
28.9
29.7
30.5
31.3
32.1
32.8
260
23.9
25.2
26.5
27.7
28.9
29.9
31.0
32.0
32.9
33.8
34.7
35.6
36.4
280
26.1
27.6
29.0
30.3
31.6
32.8
33.9
35.1
36.11
37.2
38.2
39.1
40.1
300
28.2
29.9
31.41
32.9
34.3
7_56,__36_9T
38.1
39.31
40.5
41.6
42.7
43.7
coal 5trengtn (psi) wu Mining Widtn (tt) 11.5U
'Pillar widths in italics have width -to- height ratios of 0.8
45
CI17
35
x
30
J
J
a
25
20
5
9 15
M
5
50
100 150 200 250 300 350
DEPTH OF COVER (ft)
No. Web Pillars 19
Mining
Height
(ft)
-� -8
9
- 10
11
12
13
14
15
16
--*--17
--- 18
19
20
Figure 30b. Barrier Pillar Design Chart -South Taylor Pit, E and D2 /E Seams
Agapito Associates, Inc.
l
I
i1
I
I
i
i
i
100 150 200 250 300 350
DEPTH OF COVER (ft)
No. Web Pillars 19
Mining
Height
(ft)
-� -8
9
- 10
11
12
13
14
15
16
--*--17
--- 18
19
20
Figure 30b. Barrier Pillar Design Chart -South Taylor Pit, E and D2 /E Seams
Agapito Associates, Inc.