They will probably look for scorch marks and melted plastic, examine equipment for signs of a short-circuit, establish whether the methane detectors were working and take air samples to check for highly combustible coal dust.
They will also take notice of where the bodies lay, track the victims’ footprints and perhaps look for farewell notes in the miners’ lunch pails.
Sometime in the next few days, once the toxic gases in the Sago Mine have cleared, federal and state investigators will go in and begin gathering forensic clues in an effort to establish exactly what touched off the deadly explosion and how the victims spent their final hours.
At the same time, investigators on the outside will pore through safety records and interview just about everyone connected with the mine — inspectors, managers and coal miners alike.
The blast Jan. 2 killed one miner and spread carbon monoxide that slowly asphyxiated 11 other men 260 feet below ground as they waited in the farthest reaches of the mine to be rescued. Establishing how the tragedy unfolded will be something akin to the way highway patrol officers try to reconstruct a car accident.
“It’s the same approach, in that every bit of evidence is very crucial,” said Richard Begley, a former mine boss, now an engineering professor at Marshall University.
Investigators already have some clues, including a sort of timeline written by one of the trapped miners, and a place to start: Rescue workers discovered that all of the seals on a closed-off section of the mine had been blown toward the surface, indicating that was where the explosion took place.
“With an explosion you want to know where and how it was initiated,” said Terry Farley, a member of the state investigative team. “We want to know how the fuel came to be, the buildup of gases, how that came about. That’s not uncommon in a sealed area.”
To pinpoint the cause, the investigation team — which typically includes engineers, mine safety supervisors and mine ventilation experts — will most likely look for charring and other burn patterns, said Chris Hamilton, a former mine foreman and mine rescue instructor who is now the senior vice president of the West Virginia Coal Association. And they will want to ask miners who escaped to describe conditions in the mine just before the explosion, he said.
Little evidence of fire
Tests conducted during the rescue detected high levels of carbon monoxide, and rescue workers found little evidence of fire. That suggests the explosion was probably caused by methane alone, and not, say, coal dust stirred up by the miners, Begley said.
Past investigations by the federal Mine Safety and Health Administration looked at whether methane detectors were working, and studied barometric pressure readings around the time of the accident, said Ellen Smith, editor of the newsletter Mine Safety and Health News. Such changes in pressure can release the odorless, colorless gas from the earth.
Another possible fuel source is coal dust, which can build up in the air if the walls are not coated properly. Also, loose coal that spills off the mine’s conveyor belt can work its way into the rollers and catch fire from the heat and friction.
“Coal dust will blow out supports, buckle steel supports,” said Tony Szwilski, a professor of environmental engineering and science at Marshall University. “Coal dust is the most powerful explosion.”
MSHA had cited the Sago Mine for the accumulation of such “combustible materials,” but International Coal Group chief executive Ben Hatfield said Wednesday he has heard nothing to suggest those violations had anything to do with the blast.
Whatever the fuel, there had to be a spark. Early reports from the mine suggested lightning — there were thunderstorms in the area as the men entered the mine — might have triggered the blast. One possibility is that the metal housing of a natural gas well nearby was hit by lightning and conducted an electrical charge into the ground.
But that is just one possible source of ignition.
“Methane can be ignited from electrical fault sparking, even falling rock, a rock that hits another rock or hits a rail and creates a spark,” Szwilski said.
Some ignition sources leave a trail, but nailing down the cause can also come down to a process of elimination, he said, especially if it is something like a rock falling.
The autopsies and toxicology reports could help investigators establish how long the miners were alive. Investigators will also probably try to reconstruct what the miners did as the tragedy unfolded, said Max Houck, a former FBI scientist who is director of West Virginia University’s Forensic Science Initiative.
“They’re going to be leaving behind traces, clues if you will,” Houck said.
Clues include footprints
One such clue: footprints inside the mine, which the mine’s owners have said indicate the trapped men tried to escape before hunkering down to wait for a rescue.
As detectives might at a murder scene, investigators can also study the positions of the bodies for information. Some officials have speculated that one reason the sole survivor, Randal McCloy Jr., made it out alive is that he might have been in a spot where the air was less poisonous.
McCloy is perhaps the person investigators most want to interview. He remains in critical condition. But if he recovers without significant brain damage, he might be able to tell investigators what happened during the more than 40-hour ordeal.
For now, the only firsthand account comes from a note left by miner Jim Bennett. His daughter said Bennett kept a log of what was happening, noting the time in a series of entries, with the last entry written about 10 hours after the explosion. She said that with each entry, it was clear his condition was getting worse.
That such a piece of evidence even exists is a boon for investigators.
“I’ve been here for 20 years,” Farley said. “I have been involved in fatal accidents for 12 or 13 years. I have never been involved in a situation where we had notes. I’ve never been in a situation where we had 12 people killed in one event, either.”