CHARLESTON, W.Va. (AP) - Methane gas explosions could generate
nearly 13 times more destructive force than the current federal
standard for seals in underground coal mines, government scientists
The National Institute for Occupational Safety and Health draft
report said the maximum pressure in a mine explosion could reach
640 pounds per square inch, far higher than previously thought.
Government regulators have been grappling with questions about
seals since 12 miners died in a January 2006 explosion at the Sago
Mine. A lightning strike sparked methane gas that had accumulated
in a mined-out, sealed-off section of the mine, officials say.
The Sago blast shattered alternative seals made of lighter
material than traditional concrete block. West Virginia
investigators have concluded the explosion may have produced as
much as 95 pounds per square inch of pressure.
The accident helped prompt the federal Mine Safety and Health
Administration to increase the standard for seals from 20 pounds
per square inch to 50 in July. However, almost 14,000 underground
seals across the country were built to the old standard.
The new standard may have to be significantly revised if NIOSH
"If we want to design a seal for a worst case condition, we
should design the seal for 640" pounds per square inch, said
Jeffrey Kohler, associate director for Mine Safety and Health
Research at NIOSH.
Luke Popovich, a spokesman for the National Mining Association,
said that would far exceed any existing standard in the world.
"What they're proposing is fairly breathtaking in terms of
current standards and use, and not just in the U.S.," he said.
The report also suggests that 50 pounds per square inch would be
sufficient if mines actively monitor and adjust the atmosphere
behind seals. Currently, mines must check methane levels behind
seals weekly, but NIOSH is suggesting continuous monitoring, Kohler
(Copyright 2007 by The Associated Press. All Rights Reserved.)