2010-02-05_REVISION - C1996083 ‎(8)‎

• Permit No: C1996083
• IBM Index Class Name: REVISION
• Doc Date: 2/5/2010
• Doc Name: Adequacy Response No. 1
• From: J.E. Stover & Associates
• To: DRMS
• Type & Sequence: TR65
• Email Name: JJD
• Media Type: D
• Archive: No

•
Safety Factor
3.5
3
2.5
2
1.5
1
0.75
0.5
0
Safety Factor
3.5 •
3
2.5
2
1.5
1
0.75
0.5
0
Figure 3. Pillar factor-of-safety for the mains area, (top) Niosh recommended coal strength of
900 psi and development loading, (bottom) worst case scenario using minimum coal strength of
600-psi and considering load transfer from the longwall area.
•
Maleki Technologies, Inc. Page 10
Factor of Safety Distribution on the B Seam, Development
In Situ Coal Strength = 900 psi
Factor of Safety Distribution on the B Seam, Retreat
In Situ Coal Strength = 600 psi