REP14254

• Permit No: C1980007
• IBM Index Class Name: Report
• Doc Date: 10/31/1996
• Doc Name: MID YEAR SUBSIDENCE REPORT WEST ELK MINE PN C-80-007
• From: MOUNTAIN COAL CO
• To: DMG
• Permit Index Doc Type: SUBSIDENCE REPORT
• Media Type: D
• Archive: No

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Mountain Coal Company
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RECEIVED "
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October 29, 1996
Mr. Michael Boulay
Colorado Division of Minerals & Geology
1313 Sherman Street, Room 215
Denier, CO 80203
Olwsl9r~ er Nm4ral~ g GaologY
RE: Mid-Year Subsidence Report; West Elk Mine; Permit No. C-80-007
Deaz Mr. Boulay:
Mountain Coal Company (MCC) performed the mid-yeaz subsidence survey during July 1996.
The information provided follows the format approved by the Division as a result of Minor
Revision No. 96. Please find attached two tables of the subsidence survey data for the subsidence
grid shown on Map 29 in MCC's permit.
The survey was conducted by Registered Land Surveyors of Wdmore and Company using radial
and level loop survey methods. The instrument used was an HP 3820A Total Station.
The results of the survey (see attached tables) show that very little movement has occurred since
the previous survey in October and November 1995. Maximum total subsidence continues to be
within the range of predicted subsidence of 2.25 feet for F-seam, 7.97 feet for B seam and 10.22
feet total for F and B seams (Exhibit 60, Volume 13).
As MCC's current mining is primarily west of the monument grid, the grid has shown very little
movement in the past few years. MCC intends to provide a revision to the Division eliminating
the monitoring of the grid shown on Map 29. MCC has been surveying the Jumbo Mountain area
using aerial photogrammetric methods (as approved per PROS) and will report this data in the
revision application as verification of the accuracy of the photogrammetric methods. Exhibit 60,
Volume 13 predicts subsidence based on only B-seam longwall mining, which can be applied to
the Jumbo Mountain azea because mining methods and geology are similar to the azea that is
covered by the subsidence grid.
During the period November 1995 to July 1996, MCC finished mining the 7th longwall panel and
moved to the Jumbo Mountain lease area. Longwell mining in the 7th panel was completed in
February. Development mining in the Jumbo Mountain 8th Panel was completed in early
February and longwall mining began in this panel in early March. In July, longwall mining in the
panel approached 31 crosscut in the 8th headgate. Development mining of the 9th panel