PERMFILE123352

• Permit No: C1980007
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: Exhibit 60 Subsidence Evaluation for Apache Rocks Mining Area & Box Canyon Lease Tract
• Media Type: D
• Archive: No

EXHIBIT 60
SUBSIDENCE EVALUATION
FOR THE APACHE ROCKS AND
THE BOX CANYON MINING AREAS
1.0 INTRODUCTION
This exhibit describes subsidence processes that have been observed by the author and others
from studies above longwall mining panels in Mountain Coal Company's (MCC) West Elk Mine
and from other similar operations and studies. The subsidence information obtained from the
current West Elk Mine area is used in this application to project subsidence processes, amounts,
and effects to the Apache Rocks and the Box Canyon mining areas. This is an application
document intended to comply with the Colorado Division of Minerals and Geology (CDMG)
regulations for Coal Mining, revised May 2, 1994, under Section 2.05.6, Mitigation of the
Impacts of Mining Operations.
2.0 MINING METHOD
The longwall mining method will be utilized in the Apache Rocks and the Box Canyon mining
• azeas. The panel design will be similar to the current West Elk Mine longwall panels. An
average of 12 feet of coal will be extracted from [he B-Seam in both azeas and an average of I 1
feet will be extracted from the E-Seam in the westem panels of the Apache Rocks mining azea.
In the Apache Rocks mining azea, E-Seam mining will occur in Sections 28, 29, and 30. Top
coal and bottom coal may be lefr in place in both permit areas to improve roof and floor stability.
In the Apache Rocks mining azea the three eastem panels aze designed to be 8,500 to 8,800 feet
long; the three western panels will trend east-west and range from 10,600 to 12,700 feet in
length. As currently planned, the four eastem panels are projected to trend N80°W and be 950
feet wide. E- and B-Seam mining gate road entries and longwall panels will be vertically
superimposed in the westem panels. For the most-part, the E-Seam is planned to be mined
before completing operations in the underlying B-Seam. In the Box Canyon mining area, the six
panels currently planned trend about N80°W, are I,I00 feet wide, and range in length from 7,000
to 8,200 feet. The panel layouts for the Apache Rocks and the Box Canyon mining azeas aze
shown on Map 1. The mine plan is always subject to change based on numerous factors;
however, the subsidence evaluation contained in this exhibit has been performed on the most
recent (1998 Long Range Plan) projection of the longwall panel layout.
All panels are planned to be separated by two rows of chain pillars, one row a rigid pillaz design
and one row a yielding pillar design. Chain pillazs (headgate and tailgate entries) aze currently
• planned to include one row of rigid pillazs approximately 100 feet wide by 130 feet long (130 x
831-032.181 Wright Water Engineers, Inc.