2022-09-29_PERMIT FILE - C1980007 ‎(5)‎

• Permit No: C1980007
• IBM Index Class Name: Permit File
• Doc Date: 9/29/2022
• Doc Name: SUBSIDENCE EVALUATION
• Section_Exhibit Name: Exhibit 60E Subsidence Evaluation for the South of Divide and Dry Fork Mining Areas
• Media Type: D
• Archive: No

APPENDIX A

Height of collapse-chimney equation (Whittaker and Reddish,1989)

𝑧=4
(k −1)(П)(𝑑2 )(2(𝑤)(ℎ2 )cot(∅)+ℎ(𝑤2 ))

k = bulking factor
z = height of collapse-chimney
d = diameter of collapse-chimney
w = width of mined roadway
h = height of mined roadway
Ф = angle of repose of caved rock

Variables for an 18 feet wide roadway:

k = 1.33
z = variable solved for
d = 7.8m
w = 5.5m
h = 3.35m
Ф = 35°

Variables for a 34 feet diagonal intersection:

k = 1.33
z = variable solved for
d = 10.3m
w = 7.3m
h = 3.35m
Ф = 35°