Mine Safety and Health Administration (MSHA) - Report of ...

PREFACE
This investigation was conducted by the Mine Safety and Health Administration (MSHA) under the
authority of The Federal Mine Safety and Health Act of 1977 (Mine Act). The Mine Act requires
that authorized representatives of the Secretary of Labor make investigations in coal and other mines
for the purpose of obtaining, utilizing, and disseminating information relating to the causes of
accidents. The objective of MSHA’s accident investigations is to determine the root cause(s) of the
accident and to utilize and share this information with the mining community and others for the
purpose of preventing similar occurrences. MSHA’s accident investigations include determinations
of whether violations of the Mine Act or implementing regulations contributed to the accident. In
addition to providing critical, potentially life-saving information, the findings of these investigations
provide a basis for formulating and evaluating MSHA health and safety standards and policies.
In addition to the traditional accident investigation, the Secretary of Labor also appointed an
independent review team. The independent review will consist of a thorough examination of written
mine plans (including the mine’s approved roof control plan), inspection records, and other
documents relevant to the Crandall Canyon Mine and interviews of MSHA employees with personal
knowledge of MSHA’s inspection responsibilities and enforcement procedures at the mine. This
review will provide a comparison of MSHA’s actions at the Crandall Canyon Mine with the
requirements of the Mine Act (as amended by the Mine Improvement and New Emergency Response
Act of 2006), its standards and regulations, and MSHA policies and procedures. The findings of the
independent review will result in the development of recommendations to improve MSHA’s
enforcement program and the agency’s oversight of rescue and recovery programs in the aftermath
of mine accidents. Copies of this review will be made available to the families of the miners
involved in the Crandall Canyon Mine accident, Congress, and the public.
The tragic accidents at the Crandall Canyon Mine in August 2007 occurred when overstressed coal
pillars suddenly failed, violently expelling coal from the pillars into the mine openings. Locally
referred to in Utah as a “bounce,” terminology for this type of event differs regionally, and is also
known as an outburst, bump, or burst. Bounces and bumps are broader terms that can include any
dull, hollow, or thumping sound produced by movement or fracturing of strata as a result of mining
operations. In many cases, vibrations in the strata resulting from such movement can be felt by
miners and detected by seismographic instruments. Bounces resulting from intentional caving,
where strata in active workings remain intact, are common in deep coal mines and do not pose a
threat to miners. However, coal or rock bursts, also known as outbursts 1* , are those bounces
specifically characterized by the sudden and violent failure of overstressed rock or coal resulting in
the instantaneous release of large amounts of accumulated energy with the ejection of material.
When such events occur in active workings, they pose a serious hazard to miners. Federal mine
safety standards, therefore, require that the roof, face, and ribs be controlled to protect persons from
hazards related to bursts through proper ground support and pillar dimensions. Also, coal or rock
outbursts that cause withdrawal of miners or which disrupt regular mining activity for more than one
hour are defined as accidents (even if no miners are injured) and must be immediately reported to
MSHA, as required by relevant portions of 30 CFR 50. Definitions for these and other terms are
provided in Appendix Y. Any references to product manufacturers, distributors, or service providers
are intended for factual documentation and do not imply endorsement by MSHA.
* References identified by superscript numbers are listed in Appendix Z.
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