Main indicated that, while eight methane sensors have been collected from the UBB and sent to labs, many more tests remain before investigators can say the sensors weren't tampered with. Some of the sensors were damaged, Main noted, while others were older models not capable of being downloaded.
"We don't know what it means yet," he said of the data that's been retrieved already.
The methane monitors — dubbed "sniffers" in coal country — are devices designed to shut down mining equipment automatically when methane accumulates at dangerous levels. The UBB was known to be a gassy mine, and a number of former Massey miners — working in the UBB and elsewhere — have charged that company managers would sometimes ask workers to dismantle the sniffers for the sake of keeping the equipment running and harvesting more coal.
NPR reported last month that a UBB electrician in February was ordered to "bridge out" a sniffer because it was repeatedly shutting down a continuous mining machine.
Twenty-nine miners were killed April 5 when the UBB exploded in Montcoal, W.Va. MSHA officials Wednesday made it clear that they have yet to determine the cause of the accident — "We are still collecting evidence," Main said — but mine-safety experts say the sheer size of the blast suggests large amounts of methane, combined with combustible coal dust, were likely present.
In the months prior to the blast, the UBB had received hundreds of MSHA safety violations, with dozens indicating problems related to coal dust and the mine's ventilation system.
In response, Democrats in both the House and Senate are pushing legislation to bolster the work-safety protections of the nation's miners. The legislation would hike fines for safety violations, empower MSHA officials to close dangerous mines more easily and strengthen miner's whistleblower protections.
MSHA officials on Wednesday also indicated:
• While investigators have found cracks in the tunnel, they've seen nothing to support Massey's claim that a huge crack inundated the mine with methane just prior to the blast. "We have not seen any massive crack," said Kevin Sticklin, head of MSHA's coal safety division.
• Responding to complaints from miners' families, MSHA removed two Massey officials from inside the UBB immediately following the April 5 blast. MSHA officials didn't speculate about what the two were up to, but said they simply weren't trained for mine rescue.
• The agency has eight mapping teams, four electrical teams, three photography teams and an evidence collection team roaming the mine. Still, two sections affected by the blast have not yet been examined. "We're not going to speculate on what may or may not have caused this until we have all the facts," Main said.
• Investigators have interviewed 166 people related to the disaster, most of them rank-and-file Massey workers and their family members. Officials hope to begin interviews with upper-level Massey managers in the coming weeks.
• The transcripts of those interviews will be made public before the agency holds public hearings on the disaster, though the timeline surrounding the public hearings remains unknown.
• MSHA has provided technical assistance to lawmakers pushing for mine safety reforms in the wake of the UBB blast. But "it's going to be up to Congress to decide what's in the final legislation," Main said.
Finally, MSHA officials are confident, not only that they'll find the cause of the UBB disaster, but also that they'll find it was avoidable.
"Explosions at these coal mines are preventable," Main said. "I believe we're going to look back and say that this was a preventable occurrence."