CHARLESTON, W.Va. -- Federal regulators revealed Tuesday that they believe a faulty computer program led them not to send Massey Energy a "pattern of violations" warning letter late last year for the company's Upper Big Branch Mine, where 29 workers died in a massive underground explosion last week.
U.S. Mine Safety and Health Administration officials said the computer system, in use since 2007, missed eight "unwarrantable failure" enforcement orders, any one of which would have placed Upper Big Branch in line for the MSHA warning letter.
Greg Wagner, deputy assistant labor secretary for MSHA, said the Raleigh County operation was the only one of the more than 2,000 coal mines nationwide impacted by the "computer programming error." Wagner conceded "it's a low probability" that the programming error would have affected only the one coal mine that blew up a few months later.
In the wake of the Upper Big Branch deaths -- the worst U.S. coal mining disaster in 40 years -- national media and safety advocates have questioned why MSHA did not shut down the mine, given indications of growing safety problems there.
Under federal law, MSHA generally does not have broad authority to simply close a troubled coal mine unless it seeks a federal court injunction to stop anything its inspectors believe "constitutes a continuing hazard to the health and safety of miners."
But on its own authority and without going to court, MSHA can issue what the law calls "withdrawal orders" that force all miners to be removed from areas until significant hazards are eliminated.
Citing a mine for a pattern of violations, though, kicks the operation into a much tougher enforcement bracket. Each time an additional serious citation is issued, that part of the mine is closed. Mines can have the pattern of violations designation lifted only if they go an entire quarterly inspection without a serious violation.
Last week, MSHA officials said that during a September 2009 review, Upper Big Branch met nine of 10 agency "screening criteria" for the warning letter.
But, they said, the operation did not have on its record a final order citing the company for "unwarrantable failure" to comply with safety rules. Upper Big Branch had received 16 such orders during the two-year period examined by MSHA, but appeals of all of them were pending, agency officials said.
Wagner said, though, that the computer error "did not have an impact on this tragedy."
Under internal MSHA policy, mines that meet the agency's pattern of violations screening guidelines receive warning letters, rather than actual pattern of violations orders.