PERMFILE131380

• Permit No: C1981041A
• IBM Index Class Name: Permit File
• Doc Date: 6/16/2003
• Doc Name: TOC to Appendix 20-3
• Section_Exhibit Name: Tab 20 Subsidence Survey Monitoring & Control Plan
• Media Type: D
• Archive: Yes

_g_
• TABLE 2. Factors of safety for panel G pillars for a
range of depths.
- 2nd East Physical Properties (~ = 45.50; ~ = 785 psi)
Advance Retreat
__ Pillar Size Pillar Size (s)
Depth (ft) (f t)
ft 40 x 100 16 x 100 12 x 100
- 200 5.41 2.12 1.57
300 4.67' 1.82 1.35
_ 400 4.30 1.67 1.23
500* 4.07* 1.58* 1.16
700 3.81 1.47 1.08
900 ~ 3.66 1.40 1.03
i.
1000
~~
3.61
1.38
1.01
• 0
AL! Coal Physical
~ Properties (~ = 47.2
; ~o = 783 psi)
200 5.70 2.24 1.66
300 4.97 1.94 1.44
' 400 4.59 1.79 1.32
500* 4.37* 1.70* 1.25
700 4.11 1.59 1.17
900 3.96 1.52 1.12
1000 3.91 1.50 1.10
,.
*Most probable minimum values.
r-
Tributary area = 60 X 120 ft.
._
Physical properties for 0 to 1000 psi confinement.
r-