ARLINGTON, Va. -- Nearly four months after the deadly explosion at the Upper Big Branch mine in southern West Virginia, there is no end in sight for the mostly secret investigations into the blast.
But a handful of publicly disclosed pieces of evidence have shown the path investigators are following to determine how methane gas could have amassed at such a level to fuel the massive explosion that left 29 dead.
In an interview last week with the Pittsburgh Post-Gazette, Joe Main, the head of the federal Mine Safety and Health Administration, said he believes the completed investigation will make it clear the blast could have been prevented. This view contrasts with recent statements from Massey Energy, the company that owns Upper Big Branch, suggesting the tragedy was the result of a freak accident.
"But until we get all the facts in, it's just not wise for us, and it's just not good investigative practice to talk about things before you've got them figured out," Mr. Main said. "I think the process going forward is just aimed at doing that."
MSHA has opted to interview witnesses in private, Mr. Main said, to protect the integrity of a simultaneous criminal investigation by the Department of Justice and protect the confidentiality of whistleblowers. Had MSHA decided to conduct interviews publicly, the agency would have had the power to subpoena witnesses. Mr. Main would not say how many witnesses have declined to speak to his investigators.
The secrecy has frustrated family members of the victims, who meet with Mr. Main and other MSHA officials regularly for updates on the probe.
"It's usually hogwash," said Clay Mullins, brother of Rex Mullins. "I learn more from reading the newspapers."
"It's frustrating that we can't tell them what they want," Mr. Main said. "The one thing that I do not like to do and will not do is, 'Oh, we found this piece of evidence, that may mean one of 15 things.' Because it's harmful to them."
But during a wide-ranging interview in his office across the Potomac River from Washington, Mr. Main did confirm several threads that his investigators are exploring as they work to pull together the causes of America's worst mine disaster in four decades.
One person directly involved in the investigation has made it clear that investigators are zeroing in on the mine's ventilation -- the system of walls, curtains and fans used to move fresh air through the working areas, providing oxygen and carrying out dangerous dust and gases.
Because methane is chief among the potential culprits in the initial blast, teams are exploring how effectively Massey ventilated the mine. At the same time, the company has mounted an aggressive public relations campaign arguing that MSHA did not approve a ventilation plan that would have assured maximum airflow in the work area.
Two significant issues have emerged: whether MSHA or Massey ever acted on a problem with sudden methane "outbursts" that appeared at the mine six years ago, and whether the mine was adequately ventilated by conventional standards.
A set of internal MSHA memos from 2004 outline a problem with "methane outbursts" -- sudden rushes of explosive methane gas from a series of cracks that appeared in the working area of the mine's longwall section.
Ventilation experts at MSHA's Pittsburgh Safety and Health Technology Center in South Park offered recommendations that included an increase in longwall face airflow to "more effectively dilute the methane released from the outburst closer to the source and safely remove it from the face area," as well as diligent methane checks in the work area and a plan to seal fractures after an outburst occurred.
J. Davitt McAteer, the former MSHA secretary who is overseeing an independent investigation of the explosion on behalf of West Virginia Gov. Joe Manchin, has said remedial steps should have been put and kept in place after the 2004 study.
Yet, a check of MSHA records fails to turn up any set of orders or instructions from the agency to Massey directing specific actions.
Mr. Main, during last week's interview, would not say what, if anything, MSHA did in response to those memos. The memos ultimately came to Mr. Main's attention when someone slipped them under the door to his Arlington office after the Upper Big Branch explosion.
"What I'm trying to say is we're aware of that report that was issued in 2004. What the investigation is trying to determine is what happened after that report was issued all the way up to now," Mr. Main said.
Massey has argued that the explosion might have been unavoidable and has released accounts of a mine recovery team member spotting a crack in the mine floor following the blast. The company also released data showing high levels of methane underground immediately after the blast.
But whether the company adequately addressed the problem of a mine known for high methane output is still a subject of inquiry by the investigating team.
Seven months before Upper Big Branch exploded, MSHA issued two "D" orders -- mandating immediate evacuation of a portion of the mine -- after inspectors discovered air flowing the wrong way across the work face of the longwall section.
"Air flow had reversed in the longwall setup entries and air flow was reversed in neutral air courses. The condition was minewide and the existence of the underlying ventilation conditions were both extensive and obvious," inspectors wrote.
With the airflow reversed -- essentially recirculating polluted air from the mined areas -- the potential for trouble was real enough that inspectors closed the operation until ventilation was restored.
Massey recently released measurement data showing extremely high levels of methane gas a few hours after the explosion -- which, the company said, implies a sudden burst of gas that would have overwhelmed the safety apparatus.
"To put it in perspective, a methane release of this size would completely fill a 2,000 [square-foot] house with an explosive atmosphere in under 40 seconds, and could fill the volume of a typical mine entry to explosive levels in under 25 seconds," Massey Upper Big Branch investigation team member Christopher Schemel said in a statement.
"While the UBB investigation is still ongoing and it is far too early to determine the exact cause of the April 5 accident, the methane gas data is a very important piece of evidence."
MSHA called that conclusion into question, saying the explosion likely caused a sudden spike in methane levels by pulling the gas in from other parts of the mine.
Still, Mr. Main said the idea of methane suddenly pouring into the longwall area through a crack in the floor is possible.
"There's cracks in the floor that appear commonly through mines, cracks in the floor that, if you know methane, basically the stresses are in place that's as common a phenomenon as you'd find.
"The best I can say is that's one of the possibilities in the investigation."
Massey released the methane data -- which MSHA had given the company weeks earlier -- on July 22, the same day Massey CEO Don Blankenship appeared at the National Press Club in Washington. Mr. Blankenship made only oblique mention of the methane burst in his remarks but in general terms said such unpredictable occurrences are central to mine disasters.
The company later took umbrage at news media reports that suggested Mr. Blankenship was calling mine disasters acts of God, but he unquestionably has a different view than Mr. Main, the former safety chief for the United Mine Workers.
"I think we know enough about mining to predict different outcomes," he said, "and I think whenever the investigation is completed on this we will be looking back no different than we have at events in the past to say this is a preventable event."
Mr. Main noted that Upper Big Branch had more "D" orders in 2009 than any other mine in the country. He also confirmed -- as previously reported by the Post-Gazette -- that MSHA is examining the practice of disabling methane monitors in order to continue mine production. An electrician has told investigators that he was forced to "bridge out" a malfunctioning monitor on a continuous mining machine to keep the machine in operation.
"We would hope that it is not" a widespread practice, Mr. Main said.
"There is without question, with regard to the UBB investigation a lot of attention being paid to that very issue and we would hope that by the time the investigation concludes we'll have a better handle about what was going on there."