PERMFILE108142

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 6/6/2003
• Doc Name: pages 2.05-84 to 2.05-166
• Section_Exhibit Name: 2.05 Operation & Reclamation Part 2
• Media Type: D
• Archive: Yes

West Elk Mine
Maximum Curvature
~ Curvature, i.e., subscript (C„J which is the reciprocal of radius of curvature (and thus expressed
in radians/foot [rad/ft]), is calculated from differential tilt. Maximum positive (convex upwazd)
curvature in the West Elk Mine monitoring network is as much as 50 percent more over chain
pillars than it is above longwall panel boundaries. Maximum positive curvature at the current
West Elk Mine ranges from 14.4 to 18 (Sn,/d2) with a numeric range of 0.000060 to 0.000065
rad/ft above longwall panel boundaries to an average of 24 (Stu/dr) with a turmeric range of
0.000144 to 0.00022 rad/ft above the chain pillars.
I
Maximum negative (concave upward) curvature averaged about the same when measured above
the chain pillars as it did above the panel boundaries. Maximum negative curvature ranges from
about -20 to -25 (Smld2) (-0.000111 to -0.000066 rad/ft) above longwall panel boundazies and has
an average value of -24 (Sm/dZ) (-0.00012 to -0.00025 rad/ft) in the panel centers between the
chain pillazs. Maximum positive and negative curvature in four different areas of the Westem
United States ranges from 9 to 45 (Stu/dr). Maximum curvature ranges are given below for the
eastern and western panels of the Apache Rocks and the Box Canyon mining areas.
Apache Rocks Mining Area -Maximum positive curvature projected for B-Seam mining in the
eastern panels of the Apache Rocks mining area (using an average West Elk Mine value of
24 (Stu/dZ)), ranges from 0.000023 to 0.00025 rad/ft; maximum negative curvature (using a
similar average of -24 [Stu/d2)) ranges from -0.000033 to -0.00069 rad/ft. Maximum positive
curvature projected in the western panels of the Apache Rocks mining area, after E and B-Seam
mining is completed, is projected to range from 0.00026 to 0.00132 rad/ft. Maximum negative
curvature projected in the western panels for E and B-Seam mining ranges from approximately
-0.00026 to -0.00132 rad/ft.
Box Carryon Mining Area -Maximum positive curvature for the two northern panels, Panels 1
and 2, is projected to be 0.000030 to 0.000410 radlft; for Panel 3, 0.000024 to 0.000202 rad/ft;
for Panels 4 through 6, 0.000016 to 0.000239 rad/ft. Similarly, maximum negative curvature is
projected at -0.000022 to -0.000410 rad/ft for Panels 1 and 2; -0.000024 to -0.000202 rad/ft for
Panel 3; -0.000016 to -0.000239 rad/ft for Panels 4 through 6.
Maximum Horizontal Strain
i•
Maximum horizontal tensile strain (E„J measured in the West Elk Mine monitoring network
ranges from 1.12 to 1.4 (S~,/d) (0.0058 to 0.0102). The range of horizontal tensile strain in four
different mine areas of the Westem United States studied by Mr. Dunrud is 0.45 to 3 (Stu/d).
Using an average value of 1.3 (Stu/d) for maximum predicted horizontal tensile strain above the
chain pillars, the gate road entries, and barriers between panels and an average of 2 (Stu/d) for
2 (Stu/d) for maximum predicted horizontal compressive strain, the following strain values are
projected for the Apache Rocks and the Box Canyon mining areas.
2.05-118 Revised Jim. /995 PR06; 1/96 RN03; RevisedJmi. 1998 PR08