By Dennis B. Roddy Pittsburgh Post-Gazette Friday, December 08, 2006
Nearly a year after a methane explosion in a sealed area of the Sago Mine caused the deaths of 12 West Virginia coal miners, state officials have concluded that a lightning strike triggered the blast.
That determination will be included in a report to be issued Monday by the West Virginia office of Miners' Health Safety and Training. It is based on the elimination of other sources of the spark that ignited the methane gas, including a roof fall, but investigators acknowledge that absolute proof linking the blast to lightning might never come.
E. Philip Krider, a University of Arizona lightning expert who worked as a consultant on the report, said investigators are still trying to figure out how lightning -- which struck miles from the mine -- traveled underground.
The explosion Jan. 2 blew out a block wall erected to seal off an abandoned section of the mine, filling the atmosphere with carbon monoxide. One miner died instantly in the explosion, and 11 others slowly asphyxiated. A 13th miner, Randal McCloy Jr., survived.
Dennis O'Dell, director of safety for the United Mine Workers of America, said yesterday that he learned the report would cite lightning during a union-industry training meeting last week in Fayette County, W.Va.
He said Ron Wooten, newly appointed director of MHST, "started talking about the Sago report, and he told us ... that the state was 100 percent sure that it was lightning."
Precisely how the lightning reached several hundred feet underground has eluded teams of engineers who traveled to a hillside a mile and a half from the mine to examine a shattered yellow poplar tree on the farm of Pete Rutherford.
A strike of 101 kiloamperes -- considered extraordinarily large -- hit the tree almost at the moment the methane was touched off, according to state and federal investigators.
But the bolt would have had to zip more than a mile down a road, cross the Buckhannon River, and find its way a mile into the mine to reach the seals.
"We ourselves are still trying to understand better the possibilities of what happened," Dr. Krider said.
One theory holds that the strike on the Rutherford Farm, along with another strike on the other side of the mine property, could have created an electromagnetic field that triggered a spark.
That idea would be based, Dr. Krider said, on "an effect of (electromagnetic) fields in the ground propagating current."
Such a theory was among those explored earlier this year by Monte Hieb, an engineer for the West Virginia mining office.
The mine's owners, International Coal Group, released its own investigation report two months after the accident, declaring that lightning was the source of the explosion. At the same time, J. Davit McAteer, a special investigator appointed by Gov. Joe Manchin III to conduct an independent inquiry, said he remained perplexed as to how lightning could have reached so far underground with no pipes or cables in the vicinity to carry it.
Although rare, lightning strikes have previously been blamed as the source of explosions in mines. The National Institute for Occupational Safety and Health cited seven cases in a 2001 report.
Both the United States Geological Survey and an independent laboratory reported either seismic events and lightning strikes simultaneously at the time of the Sago explosion.
A spokeswoman for the West Virginia mining office would not comment on the report.
Mr. O'Dell said he also anticipated that Monday's report would fault the construction of the Omega Block walls, which, workers have testified, were placed on the mine floor atop dry mortar rather than being cemented to the floor. The walls, however, also likely received a blast force far in excess of the 20 pounds per square inch they were required to withstand.
A federal report into the Sago disaster by the U.S. Mine Safety and Health Administration is not due until early next year. Agency sources have indicated that their findings are likely to mirror West Virginia's.
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