REP42036

• Permit No: C1980007
• IBM Index Class Name: Report
• Doc Date: 9/4/1997
• Doc Name: 1997 Mid-Year Subsidence Report
• From: Mountain Coal Company
• To: DMG
• Permit Index Doc Type: Subsidence Report
• Media Type: D
• Archive: No

Mountain Coal Company
West EIk Mine
Post OKce Box 591
Somerset, Calorodo 81434
Telephone [phone]
September 4, 1997
Mr. Michael Boulay
Colorado Division of Minerals & Geology
1313 Sherman Street, Room 215
Denver, CO 80203

RECEIVED
SEP 0 5 1997
Division o! Minerals & Geology
RE: Mid-Year Subsidence Report; West Elk Mine; Permit No. C-80-007
Deaz Mr. Boulay:
Mountain Coal Company (MCC) performed the mid-year subsidence survey during
July 1997. 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 E. Schaaf and
Associates, Inc., using a Trimble 4000 Series Global Positioning System (GPS).
The results of the survey (see attached tables) show that very little movement has
occurred since the previous survey in October 1996. 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 yeazs. MCC intends to provide a revision
application to the Division eliminating monitoring of the grid shown on Map 29.
MCC has been surveying the Jumbo Mountain azea 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 area, because mining methods and geology are similar to the
area that is covered by the subsidence monitoring grid.
During the period October 1996 to August 1997, MCC finished longwall mining the
8NW longwall panel in January 1997 and began the 9NW longwall panel. The 9NW
panel was completed in mid-August and MCC is currently in the process of moving
the longwall to the 1NE panel, the next panel to be mined. Development mining was
completed in the 9NW panel and the 1NE and 2NE panel during this period.
Development mining also occurred in the B-South Mains, Box Canyon Mains and the