2008-12-09_PERMIT FILE - C1996083 ‎(2)‎

• Permit No: C1996083
• IBM Index Class Name: Permit File
• Doc Date: 12/9/2008
• Doc Name: In Dove Gulch Area for New Layout, Maleki Technologies, December 2007
• Section_Exhibit Name: Volume IIIA Exhibit 17 Prediction of Surface Deformation Resulting From Longwall Mining
• Media Type: D
• Archive: No

• Based on four uniaxial compressive strength tests, the B Seam has moderate strength,
averaging 2,675 psi, which is very similar to the average values for the B Seam in the
West Elk Mine (Maleki and others 1999) and the Orchard Valley Mine (USBM 1986). A
rather large inherent variability in strength ranges from 2,000 to 5,800 psi. Such a level of
variability is typical for cleated coal seams. Lower strength values are reported to the
west near Terror Creek and within the present workings in the Lower B Seam and are
influenced by changes in the depositional environment of the B Seam, among other
factors (MTI 2004).
Both overburden geology and mechanical properties are similar to those from other
operations in the North Fork valley. Thus, we expect subsidence characteristics similar to
the regional patterns established for the B and D seams.
4.2 Subsidence Parameters
• Subsidence engineering parameters were estimated using the results of
comprehensive measurements by the U.S. Geological Survey (USGS) and mining
companies within the North Fork Valley. During the 1970's, USGS completed
subsidence monitoring over the historic U.S. Steel mine near the BRL No. 2 operations
(figure 1). Both U.S. Steel and the West Elk mines extracted the B Seam, complementing
detailed measurements obtained by BRL over the D Seam (figure 2).
Figure 2 presents the location of subsidence monuments over the D Seam longwall
block in the Bowie No. 2 Mine. The monument grid was gradually expanded by Cragg
Surveying as mining continued to the north in the D1 to D9 panels. In the gateroads of
these longwall panels, BRL used yield abutment pillars while gradually increasing
abutment pillar width from 98 ft in the D3 headgate to 114 ft in the DS headgate and
beyond. Surface topography influenced both the location of monuments and the
frequency of monitoring some monuments. Because of the ease of access, a great number
of monuments were positioned to the west on the top of the hill. Some monuments to the
• east were positioned over areas mined previously in the King and U.S. Steel mines and
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