Wednesday, August 22, 2007

"Evil Mountain"

As hope wanes, the Salt Lake Tribune reports:
The operator of the Crandall Canyon coal mine says no one will be going back into the tunnels where six men have been trapped since Aug. 6.

That means the bodies of the miners may never be recovered.

"I told (the Mine Safety and Health Administration) it is an evil mountain, it is alive, and I will never go back there," Robert Murray said today.

Two weeks and two days. Too long.
" is alive..."

So it must seem to some -- almost as if an active malice was frustrating every attempt to reach the missing men.

And yet, everyone knows that the rock mechanics of mining -- especially at great depth -- are not entirely predictable. Even with modern geological knowledge, what miners find underground always remains to some extent, an unknown quantity.

That's why even in routine mining, miners and mine managers have to be on the constant alert for signs of developing problems. They make regular safety examinations, write down their findings, scrutinize and correct problems. If signs show that a roof control plan is not working as intended, they update it. At least, that's how it goes under prudent safety practices and existing requirements.

In a non-routine situation, unpredictability is worse. Supports can go down like a line of dominoes -- and either quickly or gradually -- as rock stress shifts with every succeeding collapse.

Jerry Tien, a mining engineering professor at the University of Missouri-Rolla:
"That area, geotechnically, it's pretty challenging, we all know that. But the people who are mining there are also pretty experienced," Tien said. "You make a professional judgment and things turn out to not be what you think."

Once the full investigation begins, a key question will be the plan.
Robert Murray insists that his company did not change the mining plan at Crandall Canyon after purchasing a joint interest in the mine last August.

But documents obtained by The Salt Lake Tribune clearly contradict Murray's assertion, and show that Murray's company sought and received approval from federal regulators to make a significant, and, experts say, risky change to the mining strategy.

Records of the Mine Safety and Health Administration (MSHA) show that, after Murray acquired a 50 percent ownership in the mine on Aug. 9, 2006, his company repeatedly petitioned the agency to allow coal to be extracted from the north and south barriers....

Work in the north barrier progressed until March, when the mine suffered a major "bump" - a jolt in the mine caused by the pressure of the mountain bearing down, often causing the roof to fall in, floors to heave or coal to explode from the support pillars.

That incident still doesn't show up in MSHA's publicly available database.
The March bump damaged tunnels over a span of more than 700 feet, and prompted mine operators to abandon their retreat mining in the northern barrier. Instead, they asked MSHA for permission to mine the south barrier...

MSHA approved the plan relatively quickly.
...Murray's company...asked MSHA to approve a change to the mine plan on Nov. 11, 2006. MSHA officials spent just seven business days reviewing the request before approving the mining in the north barrier.

I'm not prepared to cast blame at this point. There are too many aspects that need evaluation: besides MSHA's judgement at the time, changes in mining conditions that came later, actions after those changes, and whether the mine was complying with the plan.
Also worth looking into: after the three major accidents in 2006 (Sago, Aracoma Alma, and Darby) MSHA investigated its own operations and reported that the offices responsible for the those mines were short of specialists in fields like mine ventilation and electrical systems. The agency had moved many specialists into regular inspectors jobs, and the remaining specialists sometimes cut certain corners in an effort to keep up with the work load of plans requiring approval. This may not have been a factor at Crandall Canyon, of course; it's just one of many questions to be asked.

I also want to say one thing about the inspector who was killed. He last visited the mine in May and found no roof problems, the Tribune reported. I hope no one is jumping to the conclusion that he should have found violations, in light of the accident that folowed 4 months later.

From a roof control point of view, 4 months ago is a very long time. By the date of the accident, the active mining area would have moved a long way -- likely thousands of feet, I would imagine. Conditions may have changed radically. Practices may have changed also. Mine personnel are responsible for scrutinizing the mine systematically for potential hazards several times a day because the workplace changes constantly and in ways that are not always predictable. A "clean" roof inspection at a given time says nothing about how it will be 4 months in the future.


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