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

Subsidence Evaluation for the
Exhibit 60E Southern Panels, Apache Rocks West, & Sunset Trail Mining Areas Page 18

831-032.923 Wright Water Engineers, Inc.
December 2021
Horizontal compressive strain ranges from -0.004 to -0.018 (-0.4 to -1.8 percent) where
the extraction thickness equals 9 feet, and -0.007 to -0.028 (-0.7 to -2.8 percent) where
it equals 14 feet (Table 2).
The E-seam panels E1 to E5 and B-seam panels B26 to B29 occur on top of one another, but are
not stacked based on the current panel layout. However, to be conservative, the strain of the two
seams is assumed to be additive.
• For E-seam and B-seam panels, projected horizontal tensile strain ranges from 0.009
to 0.044 (0.9 to 4.4 percent) where the planned coal extraction thickness is 9 feet, and
from 0.014 to 0.069 (1.4 to 6.9 percent) where the extraction thickness equals 14 feet.
Horizontal compressive strain ranges from -0.009 to -0.047 (-0.9 to -4.7 percent) where
the extraction thickness equals 9 feet, and -0.014 to -0.073 (-1.4 to -7.3 percent) where
it equals 14 feet (Table 2).
Apache Rocks West Mining Area:
Maximum tensile and compressive horizontal strains are calculated, using the values obtained from
the area of the West Elk Mine, and as projected in Figure 5 (Table 3). These values are believed
to be conservative, based on Dunrud's annual observations in the Apache Rocks West mining area.
• Panels E10 to E12: For these panels, projected horizontal tensile strain ranges from
0.007 to 0.028 (0.7 to 2.8 percent) where the planned coal extraction thickness is 10
feet, and from 0.009 to 0.039 (0.9 to 3.9 percent) where the extraction thickness equals
14 feet.
Horizontal compressive strain ranges from -0.007 to -0.030 (-0.7 to -3.0 percent) where
the extraction thickness equals 10 feet, and -0.009 to -0.042 (-0.9 to -4.2 percent) where
it equals 14 feet (Table 3).
• Panels B12 to B13-A: For these panels, projected horizontal tensile strain ranges from
0.007 to 0.018 (0.7 to 1.8 percent) where the planned coal extraction thickness is 12
feet.
Horizontal compressive strain ranges from -0.007 to -0.019 (-0.7 to -1.9 percent) where
the extraction thickness equals 12 feet.
The E-seam panels E10 to E12 and B-seam panels B12 to 13A occur on top of one another, but
are not stacked based on the current panel layout. However, to be conservative, the strain of the
two seams is assumed to be additive.
• For E-seam and B-seam panels, projected horizontal tensile strain ranges from 0.013
to 0.046 (1.3 to 4.6 percent) where the planned coal extraction thickness is 10 feet, and
from 0.016 to 0.057 (1.6 to 5.7 percent) where the extraction thickness equals 14 feet.