Crandall Canyon Accident Investigation
Summary and Conclusions
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.