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It's MORNING EDITION, from NPR News. I'm Steve Inskeep.
RENEE MONTAGNE, host:
And I'm Renee Montagne.
Nine months after that deadly coal mine explosion in West Virginia, federal investigators have revealed their working theory about the cause. It directs blame toward a series of maintenance and equipment failures at the Upper Big Branch mine.
Last night, the Mine Safety and Health Administration briefed the families of the 29 coal miners who died. The briefing was closed to reporters but NPR's Howard Berkes spoke with several people who attended and joined us from Beckley, West Virginia.
Howard, good morning.
HOWARD BERKES: Good morning.
MONTAGNE: What did investigators say about this deadly accident how it started?
BERKES: Well, let me take you through this step by step. And remember, first, that this is a very gassy mine. Methane gas is common in this area and in this mine, and it seeped into the area where a massive long wall mining machine was cutting coal. The cutting tool, which is called a shearer, had several problems. Some of its carbide-tipped teeth were worn down to their steel nubbins, and when those teeth hit hard rocks, sandstone in the coal seam, they sent sparks flying.
Now problem number two, a water spraying system that's supposed to help control sparks wasn't working. Now investigators point out that the water sprayers also help control coal dust, which is explosive. The sparks ignited the methane in what is described as a small fireball. But without the sprayers to control or extinguish that ignition and with coal dust to fuel it, it exploded. Investigators reported excessive coal dust spread throughout the mine and that fed the blast, sending it coursing more than two miles underground.
MONTAGNE: It sounds like a lot of things went wrong in this Massey Energy mine. Did investigators explain that?
BERKES: You know, I talked to several people who were in the meeting, as you pointed out, and they all quote federal mine safety officials saying essentially the same thing, that this mine was non-compliant with federal safety laws in multiple ways and if the mine had been operating the way it was supposed to, this explosion would not have happened. One official pointed out that these small methane ignitions occur almost weekly around the country but without explosions.
Now, some people did ask about federal oversight were regulators doing enough? And the officials said regulators cited the mine repeatedly, they closed unsafe areas at times but Massey Energy would fix the problem so they could start cutting coal again and the violations would return.
MONTAGNE: And Howard, we're calling this a working theory. Does that mean that there is some uncertainty about what went wrong?
BERKES: I'm told that investigators were careful not to say that this is their final and firm conclusion. They're still working through evidence and it'll be 60 to 90 days, they said, before they'll have a final report. They also pointed out that there's a federal criminal investigation that's still underway. And by the way, the investigators themselves will talk publicly about their tentative findings in a news conference later this morning.
MONTAGNE: And any response so far from the owner of the Upper Big Branch mine, Massey Energy?
BERKES: Massey is set to conduct its own briefing for the families Friday morning in Charleston, West Virginia. And the company has had its own theory -based essentially on a natural and massive infusion of methane or natural gas that overwhelmed all the safety systems. Last night, one of the government's experts refuted that theory by presenting evidence he said contradicts it. We'll get Massey's response to that and the rest of the government's tentative conclusions I'm sure on Friday.
MONTAGNE: Howard, thanks very much.
BERKES: You're welcome, Renee.
MONTAGNE: NPR's Howard Berkes reporting from Beckley, West Virginia.
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