WASHINGTON – The method of mining used at the Utah mine that collapsed Monday, trapping six miners, has a history of being disproportionately deadly, according to federal safety studies.
The Crandall Canyon mine collapse happened while miners were engaged in a method called "retreat mining," in which pillars of coal are used to hold up an area of the mine's roof. When that area is completely mined, the company pulls the pillar and grabs the useful coal, causing an intentional collapse.
It is "the most dangerous type of mining there is," said Tony Oppegard, a former top federal and state of Kentucky mine safety official who is now a private attorney in Lexington, Ky., representing miners.
According to the American Society of Safety Engineers, retreat mining requires very precise planning and sequencing to ensure roof stability while the pillars supporting the roof are removed.
The reason the practice is used is that it pays off: The last bit of coal taken from pillars is pure profit, Oppegard said. Plus, if someone violates rules during pillar removal and there is a collapse, the evidence of rule violations are gone, he said.
Retreat pillar mining is one of the biggest causes of mine roof collapse deaths, according to studies done by the National Institutes of Occupational Safety and Health.
Three of the nine roof fatalities in 2001 were from retreat mining, according to a 2003 NIOSH paper. Between 1992 and 2001, 100 miners died in roof collapses, 27 of them during retreat mining the study found.
Yet that type of mining only provides 10 percent of underground coal production, the report said, concluding "mathematically a coal miner on a pillar recovery section was more than three times as likely to be fatally injured" in a roof collapse than colleagues in other parts of a mine.
"Pillar recovery continues to be one of the most hazardous activities in underground mining," the report said. A NIOSH study six years earlier found the same thing.
Dennis O'Dell, occupational safety and health chief for the United Mine Workers of America, used to do retreat mining when he was younger.
"The only support you had basically were five breaker posts; five posts would be between you and the roof falling in," O'Dell said. "It's a pretty spooky way of mining."
But Bruce Hill, president of UtahAmerican Energy, Inc. which operates and co-owns the mine, called it a safe practice.
"It's been done for the last 70 years and been very successful for those years," Hill said. "It's something that the government approves and signs off on. Coal operators have been able to prove it's safe all along."
It's up to individual mines and "the coal community" to determine whether to use retreat mining and often times unions and management don't seem to mind, said Luke Popovich, spokesman for the National Mining Association, which represents mine companies in Washington.
"It's thought to be very valuable, useful," Popovich said.
NIOSH said that during retreat mining nearly half of those fatal accidents happened during the removal of the final pillar, which miners call the "suicide pillar," said J. Davitt McAteer, former head of the U.S. Mine Safety and Health Administration and now vice president of Wheeling Jesuit University in West Virginia.
McAteer wrote a 2001 report for the state of West Virginia calling for tighter restrictions on the retreat mining process, saying one miner told him "We are always pushing the edge of safety; we are right up against it."
Some states are debating about even allowing the practice, he said. The state of Kentucky recently adopted new rules on retreat mining ordering companies to tell state officials before the practice is used, Oppegard said.
The deaths of four miners within 13 months in 2004 and 2005 prompted the Kentucky Office of Mine Safety and Licensing to do an independent study of the practice. The resulting report recommended better training in geological conditions, roof control and retreat mining plans.
Last month, federal regulators cited the operator of the southern West Virginia coal mine, Brooks Run Mining Co., for safety violations that resulted in the deaths of two workers in a roof fall. MSHA reported that the company ignored its roof control plan and inadequately trained workers on safe retreat mining practices.