REP23356

• Permit No: C1980007
• IBM Index Class Name: Report
• Doc Date: 1/30/2007
• Doc Name: 2006 Subsidence & Geologic Field Observation
• From: Mountain Coal Company, LLC
• To: DRMS
• Permit Index Doc Type: Subsidence Report
• Media Type: D
• Archive: No

TABLE OF CONTENTS
Paae
1.0 SUMMARY OF MAJOR FINDINGS ..................................................................................1
' 2.0 FIELD RECOGNITION OF SUBSIDENCE AND NON-SUBSIDENCE FEATURES IN
THE WEST ELK MINE AREA .........................................................................................3
2.1 Subsidence Cracks and Compression Features .................................................................3
' 2.2 Construction Cracks ............................................................................................................4
2.3 Desiccation Cracks ..............................................................................................................5
2.4 Gravity-Induced Cracks .......................................................................................................7
3.0 OVERVIEW OF 2006 FIELD STUDIES ...........................................................................8
4.0 TRAVERSES AND OBSERVATIONS IN THE BOX CANYON, WEST FLATIRON,
APACHE ROCKS AND SOUTH OF DIVIDE MINING AREAS ........................................9
' 4.1 TraverseA-A' .................................................................................................................... ...9
4.1.1 Location 1 ....................................................................................................... ...9
4.2 Traverse B-B' .................................................................................................................... .10
4.2.1 Location 2 ....................................................................................................... .10
4.2.2 Location 3 ....................................................................................................... .12
4.2.3 Location 4 ....................................................................................................... .13
4.3 Traverse C-C' ................................................................................................................... .16
' 4.3.1 Location 5 ....................................................................................................... .16
4.3.2 Location 6 ....................................................................................................... .18
4.3 Traverse D-D' ................................................................................................................... .19
' 4.4 Traverse E-E' .................................................................................................................... .19
4.5 Traverse F-F' .................................................................................................................... .20
4.6 Traverse G-G' ................................................................................................................... .20
4.6.1 Location 7 ....................................................................................................... .20
' 4.6.2 Location 8 ....................................................................................................... .21
4.7 Traverse H-H' ................................................................................................................... .23
4.8 Traverse I-I' ....................................................................................................................... .23
' 4.9 Traverse J-J' ..................................................................................................................... .23
4.9.1 Location 9 ....................................................................................................... .24
4.10 Traverse K-K' .................................................................................................................... .26
4.11 Traverse L-L' ..................................................................................................................... .27
' 4.11.1 Location 10 ..................................................................................................... .27
4.11.2 Location 11 ..................................................................................................... .28
4.12 Traverse M-M' ................................................................................................................... .29
' 4.13 Traverse N-N' ................................................................................................................... .30
4.14 Location 12 ....................................................................................................................... .31
4.15 Location 13 ....................................................................................................................... .36
' 5.0 CONCLUSIONS ............................................................................................................ 40
6.0 REFERENCES .............................................................................................................. 43