REP52801

• Permit No: C1980007
• IBM Index Class Name: Report
• Doc Date: 9/30/2004
• Doc Name: Subsidence & Geologic Field Observ Apache Rocks & Box Canyon 7/2004
• From: Wright Water Engineers Inc
• To: DMG
• 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-SUBSIDENGE FEATURES IN
THE WEST ELK MINING AREA .....................................................................................4
2.1 Subsidence Cracks and Compression Features ......................................................... ........4
2.2 Construction Cracks .................................................................................................... ........ 5
2.3 Desiccation Cracks ..................................................................................................... ........ 6
2.4 Pseudo Subsidence Cracks (Gravity-Induced Tension Cracks) ................................. ........6
3.0 OVERVIEW OF FIELD SUBSIDENCE STUDIES DURING JULY 12 -15, 2004 ...... .......7
4.0 OBSERVATIONS AND EVALUATIONS ALONG FIELD TRAVERSES AND AT
INDIVIDUAL LOCATIONS FROM JULY 12 THROUGH JULY 15 ..................................8
4.1 Subsidence Observations and Evaluations on July 12, 2004 ....... ...................................... 8
4.1.1 Traverse A-A' ................................................................. ......................................8
4.1.2 Traverse B-B' ................................................................. ......................................8
4.1.3 Traverse C-C' ................................................................ ....................................11
4.1.4 Traverse D-D' ................................................................ ....................................12
4.1.5 Traverse E-E' ................................................................. ....................................14
4.1.6 Traverse F-F' ................................................................. ....................................15
4.2 Subsidence Observations and Evaluations for July 13, 2004 ....... ....................................19
4.2.7 Traverse G-G' ................................................................ .................................... 19
4.2.2 Traverse H-H' ................................................................ ....................................19
4.2.3 Traverse I-I' ................................................................... ....................................20
4.2.4. Traverse J-J' .................................................................. .................................... 24
4.2.5 Traverse K-K' ................................................................. ....................................25
4.2.6 Traverse L-L' ................................................................. .................................... 26
4.3 Subsidence Observation and Evaluations for July 14, 2004 ......... ....................................27
4.3.1 Traverse M-M' ............................................................... .................................... 27
4.3.2 Traverse N-N' ................................................................ .................................... 31
4.3.3 Traverse O-O' ................................................................ .................................... 32
4.3.4 Traverse P-P' ................................................................. ....................................33
4.3.5 Traverse O-Q' ................................................................ ....................................35
4.3.6 Traverse R-R' ................................................................ .................................... 36
4.3.7 Location 76 .................................................................... ....................................37