Whitesburg KY

Plan would halt sealing of abandoned mine sections


The search for a better way to protect the nation’s underground coal miners from deadly methane gas explosions is leading some in an unexpected direction: the past.

Before the 1990s, mines typically left abandoned sections open and relied on complex ventilation systems to remove methane that constantly seeps out of coal. For the past decade or so, however, a variety of factors have pushed coal mining toward sealing abandoned areas with concrete block walls.

But a pair of deadly 2006 explosions have given the industry reason to rethink the notion that sealing abandoned areas is the best option. The Sago Mine blast that killed 12 men in January 2006 and the Kentucky Darby explosion that killed five more the following May occurred behind seals.

“Until the last few years, I believe that the mining community believed that the seals that were in place were sufficient to contain an explosion,” said Jeff Kohler, associate director for Mine Safety and Health Research at the National Institute for Occupational Safety and Health.

“It was only in recent years that evidence began to accumulate that that may not be the case. Now everybody’s looking for alternatives.”

The Sago explosion destroyed 10 seals built to withstand 20 pounds of pressure per square inch, the federal standard at the time. Investigators later pegged the actual explosion at 93 psi or higher. A U.S. Army Corps of Engineers report estimates a small part of a seal may have been hit by 629 psi.

MSHA estimates that 372 of the nation’s 670 underground coal mines seal abandoned areas. Those mines employ more than 70 percent of the nation’s 42,700 underground miners.

Coal mines moved toward using seals because ventilating abandoned areas is considered difficult – and dangerous. Socalled gob areas can be prone to roof falls and flooding, which can mess up air flow. They’re also dangerous to the miners who must inspect abandoned areas regularly and travel – often by foot – to the farthest reaches to test for methane regularly.

Still, the West Virginia Office of Miners’ Health, Safety and Training is giving serious consideration to ventilating abandoned areas in the state’s active coal mines instead of having them blocked off. Officials say the idea is worth exploring in the search for ways to make the state’s 135 producing underground mines safer. The agency also plans to test ways of dampening explosive forces before they slam into seals.

There’s some history guiding that notion, says state mining engineer Monte Hieb. Records predating the widespread acceptance of seals suggest that miners might have been better protected back then.

“We’ve had far greater problems with accidents, injuries, fatalities, with explosions with mine seals,” he said.

The question really hasn’t been studied, though that was suggested by the Mine Safety


Technology and Training Commission after Sago, chairman Larry Grayson said. The panel was appointed by the National Mining Association, a Washington, D.C.-based industry group, but included representatives from coal companies, the United Mine Workers union and mine-rescue teams, as well as health and safety experts.

The panel called for a study to determine proper seal strength coupled with risk assessments at individual mines to better decide between seals and ventilation, said Grayson, a professor of mining engineering at Penn State University.

But experts say simply reverting to the days before seals is unlikely.

Crumbling roofs, accumulating water and other problems make it risky to send miners into abandoned areas to check gas levels, he said. And those same factors can change air flow in a mine, forcing revisions in the ventilation system.

“It is not a decision to be made lightly. There’s no question that there’s a trade off in risk,” said Kohler. “You had better ventilate them correctly … in a complex and large mine, ventilating gobs is not a trivial matter.”

Kohler notes that seals originally were seen as the solution to people having to enter abandoned areas.

“That contrasts to explosions that we’ve had in the last few years, where it’s become clear where seals need to be changed.”

Grayson says elevated risk is the chief concern in the sealing vs. ventilating debate.

“Could it be done better? Probably. Would it be more expensive? Maybe. Would it be cheaper? Maybe,” he said. “But the main concern is the elevation of risk.”

Regulators still give mine operators the option of ventilating abandoned sections rather than sealing them, but they’re required to monitor conditions, maintain the atmosphere and regularly send people to check gas levels, among other things.

The federal Mine Safety and Health Administration issued emergency rules last spring that said seals, at a minimum, must be able to withstand an explosive force of 50 pounds per square inch. To meet that standard, mine operators would have to ensure sealed off areas remained nonexplosive. Mines could avoid such monitoring if they build seals to withstand forces of up to 120 psi.

The agency estimates that requiring stronger seals is expected to cost the industry about $40 million a year.

Neither the National Mining Association nor MSHA have taken a position in the debate over seals vs. ventilation, but mine operators have been considering it for about 18 months, said West Virginia Coal Association Vice President Chris Hamilton.

“I’m not certain we’ll see more or less areas sealed, but I am certain that those decisions will be made at the local level,” he said.

Yet, if historic problems about ventilation can be managed, it would be a viable option to seals for most mines, Hieb said. “Some areas, sealing is still the only feasible option.”

Leave a Reply