But Tony Oppegard, a former senior adviser at MSHA and Kentucky mining regulator, said the "retreat mining" being done at Crandall poses serious risks, and given the conditions in the area raises questions about the thoroughness of the MSHA review.
The questions about the agency's performance come on the heels of MSHA administrator Richard Stickler's acknowledgement in June that there were "deeply disturbing" problems in its enforcement programs leading up to the 2006 disasters at the Sago, Aracoma and Darby mines that killed 19 miners.
"These three reviews show an unacceptable lack of accountability and oversight that will not be tolerated," Stickler said in a memo to MSHA employees. "The internal reviews identified several significant deficiencies in MSHA's accountability and performance that must be corrected."
Stickler created an Office of Accountability to oversee management and enforcement programs in the agency. The position has yet to be filled.
The Crandall Canyon mine was nearing the end of its life and mine owners were trying to extract the last deposits by cutting out the coal pillars that were holding up the massive amount of rock above the main tunnels.
Huge sections on each side of the main tunnels had already been mined with longwall machines. Once that coal was gone, the sections collapsed, leaving behind piles of rubble called "gob." That essentially meant that the thick coal pillars that protected the tunnels were the only support for the mountain that rises as much as 2,200 feet above.
"Everyone understands that in the West you have tremendous pressure on those coal pillars from the overburden and they are subject to bursting or bursting of the ribs," Oppegard said. "In either case, that can be deadly for coal miners."
In the Crandall Canyon mine, miners have for the past several months been cutting those pillars away, removing the last of the coal and allowing the roof to fall in.
In March, the mine experienced a major "bump" - a shift in the mountain that can cause the roofs or pillars to fail, the floor to heave up, or coal to explode from the tunnel walls.
The event severely damaged the northernmost main tunnels for hundreds of feet, according to a memo by Agapito Associates Inc., a mining engineering consulting company hired by the mine's operators. The operators then decided to abandon mining in those areas, but Agapito determined the southernmost main tunnels could be mined if larger pillars were used to support the roof.
"Our mining plan, when it was recommended by Agapito, was approved by the federal Mine Safety and Health Administration," and those who question it are "incorrect," Murray said.
Oppegard said that when the mine operators offered that plan, it was then up to MSHA to examine it and make a sound decision based on the risks.
MSHA coal administrator Kevin Stricklin told The Charleston Gazette last week that operators were "trying to pick up all the coal they could" when the company proposed removing pillars from the main tunnels.
He said a roof control inspection that started on May 22 was part of MSHA's review of the company's proposal. Inspectors found some problems, Stricklin said, but they were corrected and the plan was approved.
Allyn Davis, manager for MSHA's District 9, approved the pillar mining plan along the southernmost main tunnels on June 15. Stricklin told The Gazette that MSHA would not have approved an unsafe plan.
After the 1984 Wilberg mine fire that killed 27 people, John Barton, then MSHA's district director in Denver, came under fire - largely from union officials - for approving Emery Mining Co.'s plan for longwalling parts of the mine. The Crandall mine is nonunion.
Larry Grayson, a professor of mining engineering at Penn State University, said that it's too early to say if MSHA's handling of the mine plan was adequate, but that, in a mine with a recent history of bumps, "MSHA approval, in my opinion, is not enough."
He said a risk analysis must look at questions, such as whether miners could escape if a bump were to occur, how they could be reached if they were trapped, and whether there are enough provisions to sustain them if the mine is damaged.
Robert Ferriter, now director of the mine safety program at the Colorado School of Mines and a 27-year MSHA veteran, said the mining being done at Crandall was extremely dangerous.
"I'm surprised that they would try to take that last section," Ferriter said. "I would've thought that would have triggered someone from MSHA to say, 'Wait a minute, let's take a look at this.' "
The decision to approve the mine plan will be looked at during MSHA's accident review.
"It's absolutely something that would be addressed in the course of the investigation and the ensuing internal review," said Amy Louviere, an MSHA spokeswoman.
Oppegard said it should be up to an independent entity to look at MSHA's handling of the permit to ensure it is objective.