PERMFILE130419

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 4/8/2005
• Section_Exhibit Name: Exhibit 60C Subsidence Evaluation 2004 Geological Hazard Field Observations for the WFLA
• Media Type: D
• Archive: Yes

Exhibit 60C
Subsidence Evaluation and 2004 Geologic Hazard Field Observations
West Flatiron Lease Area
• 7.1.2 Maximum Tilt
Longwall Panel 18A:
Maximum tilt (Mm) above the longwal] pane] centerline is projected to range from 0.011 to
0.048 (0.1 to 4.8 percent).
lAngwall Panels 18 and 19:
Maximum tilt (Mm) above the longwal] panel centers is projected to range from 0.005 to
0.039 (0.5 to 3.9 percent).
Longwall Panels 20 and 21:
Maximum tilt (Mm) above the longwal] panel centers is estimated to range from 0.005 to
0.027 (0.50 to 2.7 percent).
• 7.1.3 Maximum Horizontal Strain
The horizontal stain values, listed below for longwal] panels 18A through 21, fit within the range
of horizontal tensile strains determined in four different mining areas of the Western United
States studied by the author (0.45 to 3 (S,,,/d). The curves projected for tensile and compressive
strain for the West Flatiron Lease area are based on the West Elk Monitoring Network and the
National Coal Board of the United Kingdom (Figure 1).
Longwall Panel 18A:
Maximum tensile (positive) horizontal strain is projected to range from 0.006 to 0.024 (0.6 to
2.4 percent).
Maximum compressive (negative) horizontal strain is estimated to vary from -0.006 [o -0.038
(-0.6 to -3.8 percent).
u
831-032.650 Wright Water Engineers, Inc. Page 14
November 2004