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Crandall Canyon Accident Investigation
Summary and Conclusions
On August 6, 2007, six miners were killed in a catastrophic coal outburst when roof-supporting pillars failed and violently ejected coal over a half-mile area. Ten days later, two mine employees and an MSHA inspector perished in a coal outburst during rescue efforts.
- The August 6 catastrophic accident was the result of an inadequate mine design.
- Flawed engineering analysis by Agapito Associates Inc. (AAI), resulted in an inadequate mine design, with unsafe pillar dimensions, which contributed to the accident.
- AAI's inadequate engineering management review also contributed to the accident.
- The mine operator, Genwal Resources Inc. (GRI), submitted a mining plan based on the AAI analysis.
- GRI failed to revise its mining plan following coal bursts in March and as late as August 3, but rather continued to mine coal in areas with unsafe conditions.
- GRI's unauthorized mining practices increased geological stress levels in the vicinity of working coal miners.
- MSHA found no evidence that a naturally occurring earthquake caused the collapse on August 6.
- The August 16 coal outburst accident.
- Any hope of accessing the trapped miners required rescue personnel to remove coal debris that blocked them from the miners.
- The mine operator withheld information about a recent coal burst which deprived MSHA of a complete picture of underground conditions.
- The unexpected conditions in the mine caused a robust roof control system to fail during the attempt.
Genwal Resources Inc. Actions
- GRI misled MSHA about the extent of the March 10 coal burst and failed to immediately inform MSHA about the March 7 and August 3 bursts.
- GRI submitted an inadequate roof control plan based on faulty AAI engineering analyses to MSHA.
- GRI failed to adequately revise its roof control plan to provide better support after the March 7, March 10, and August 3 bursts and continued to expose miners to unsafe conditions.
- GRI violated the approved roof control plan when coal was mined in a prohibited area.
Agapito Associates Inc. Actions
- AAI failed to recommend safe mining methods and pillar/barrier dimensions
Fines
- MSHA levies $1,636,664 in fines against GRI
- MSHA levies $220,000 against AAI
Changes to MSHA Policies and Procedures
Completed:
- Letter to Mine Operators with Requirements for Roof Control Plan Submittals-June 3, 2008
- Memoranda to District Managers
- Approval of Complex and/or Non-typical Roof Control Plans and Amendments-June 5, 2008
- Corrective Measures for Inspection and Investigation Activities Related to Roof Control Plans and Related Miner Training - June 3, 2008
- Documentation of Roof Control Plan Reviews-June 6, 2008
- Procedure Instruction Letter
- Technical Support Assistance in Reviewing Roof Control Plans-Effective May 25, 2008
- Memorandum of Understanding (MOU) with the Bureau of Land Management - April 8, 2008
- All Retreat Mining Plans with depths over 1,500 feet in District 9 reexamined - August 2007
- 17 ground control inspections by Technical Support of mines with bump-prone conditions - August 2007 - February 2008
- Developed and posted a list of Best Practices addressing "Ground Control for Deep Cover Coal Mines." - February 2008
Program Information Bulletin
o Precautions for the Use of the Analysis of Retreat Mining Pillar Stability (ARMPS) Computer Program - April 7, 2008
Pending Actions:
- Future Program Information Bulletins
- Guidelines for Use of Numerical Modeling, Type of Information to be Provided in Roof Control Plan Submittals
- Guidelines for Use of LaModel Computer Modeling Program
- Periodic Mine Emergency Response Development (MERD) Exercise and Training
- Legal positions regarding 103 (j) and (k); authority of Primary Communicator and Family Liaison
- Separate assigned persons as Person in Charge, Primary Communicator and Family Liaison
- ERP reviews and updates for non-English speaking families
- Review of MSHA emergency response equipment and deployment procedures
- Wireless communications and tracking guidance.
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