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Three Rescue Workers Die at Utah Mine

August 17, 2007 at 6:20 PM EDT

MARGARET WARNER: Rescue workers were clearing an underground passage toward six trapped miners last night when the collapse occurred at 6:39 p.m. local time. Three were killed and six injured.

Around the same time, University of Utah seismologists recorded what’s called a “mountain bump.” The bump, or small quake, registered 1.6 on the Richter scale. About 20 such events have occurred around the mine since the initial collapse 11 days ago.

The rescuers had advanced about 800 feet towards the trapped miners before last night’s collapse. At the time, they were working 2,000 feet below the mountain’s surface. They were still some 1,200 feet away from the area where the six trapped miners are thought to be.

A federal mine official said the pressure of so much earth and rock above the tunnel and its support structure triggered the collapse.

RICHARD STICKLER, Mine Safety and Health Administration: That vertical load creates forces that are horizontal within the pillars. And when that energy gets released, it’s like an explosion. And last night, the right rib exploded off of the coal pillar with tremendous force, removed — it knocked out all of the ground support we had in place.

Pressure on coal pillars

MARGARET WARNER: For the latest on this story, we turn to reporter Brent Hunsaker of KTVX-TV in Salt Lake City. He's been reporting from the mine site since the initial August 6th accident and joins us now.

And, Brent, thank you for joining us. Flesh out for us what the federal mine official meant when he said that the pressure created horizontal force on the pillars.

BRENT HUNSAKER, Reporter, KTVX-TV: Well, think of it like in between my hands here is a balloon. What's happening is all that pressure of the movement of the mountain above is forcing down on the coal pillars. Coal pillars, not like the pillars in your home, but they're huge supports, blocks of coal left unmined inside of the coal mine to support the roof.

So here we go with this balloon. The pressure comes down. Most of the time it just bounces. Sometimes it's severe enough, it's catastrophic, forces it down really hard, and that balloon would pop, right? Well, in the same sense, those coal pillars pop out, and the coal is pushed out at incredible rates of speed. And there's also a concussion wave that can go along with it.

MARGARET WARNER: And so that's what's meant by a mountain bump? It's not really a natural earthquake at all, but it's somehow a side effect of this mining.

BRENT HUNSAKER: And that's what seismologists are telling us, that it is an event that is found only in areas where there's mining, because basically human beings going in, and we're hollowing out a section underneath, at one point, 2,000 feet of shale, of sandstone, and limestone. That's a lot of weight sitting on that void and on those coal pillars.

Looking for a safe way to resume

MARGARET WARNER: OK, so the underground approach to these trapped miners or where they're thought to be has been suspended the officials say until a safe way can be found to do it. Do the experts you're talking to there think there is some other safe way, guaranteed safe way to resume the underground approach, or are they pretty much abandoning it?

BRENT HUNSAKER: There are no guarantees when you're dealing with this much force in nature. They're looking to modify the way that they are putting out the protections on the ribs of the walls of the mine as they go in, along the borders of those coal pillars.

They have been putting in steel supports with timbers, with wire mesh, everything they can to keep that coal from bursting out of those ribs. Obviously, what they thought was adequate last night proved not to be adequate. So at this point, nobody has any concrete ideas of what they can do to absolutely guarantee the safety of those rescuers. It may be that there are no guarantees.

MARGARET WARNER: Now, you've been there, as we said, for the duration of this rescue effort. What's the mood like among the people who've been involved in this, after this setback, grim, determined, what?

BRENT HUNSAKER: I would say grim. And, in fact, on the face of the governor today, underneath his calm exterior, I thought I detected something else brewing inside, as well. Perhaps you might even call it anger, perhaps frustration. And at the very end of his comments, he said, whatever we do as we move forward, we cannot have any more injuries or deaths. We have suffered as Utahans enough.

Drilling boreholes to search

MARGARET WARNER: Now the rescue mission that is still underway involves drilling this borehole from above down to this area where they think the trapped miners may be. What makes them think that's where the miners may be?

BRENT HUNSAKER: Well, this is the fourth borehole that they drilled. Yesterday they told us that they had changed the location of borehole number four because they had heard a mysterious noise. Now, most of the time -- and they have listening devices set up all over the mountaintop called geophones. Most of the time, the geophones can't pick up anything because you've got the drilling action going on from above, from on top of the mountain, and underneath you have the rescue miners working, moving all of that debris, all of the rubble that is between them and the trapped miners.

But when they finished borehole number three, they had a moment of silence. Everything was shut down, and all they did was listen. And while they listened, there was a five-minute period where they heard a consistent noise that happened about every second-and-a-half. They said it wasn't a pattern; it wasn't like an SOS being pounded out on metal somewhere. But it was consistent. It lasted for five minutes.

It intrigued them enough that they said they changed the direction or the location of borehole number four over the area where they think that noise was coming from, and that's what they're drilling right now. We hope that that borehole will break through either late tonight or sometime tomorrow morning.

MARGARET WARNER: So they think it could happen that soon?

BRENT HUNSAKER: Yes, they have quickened the pace on those holes considerably. They started yesterday afternoon. They said roughly two days, so that puts us into perhaps tonight, if they move quickly, probably tomorrow.

MARGARET WARNER: So what is the scenario they envision? If they were to get down there with the borehole and find that there are any miners and they're alive, how do they get them out?

BRENT HUNSAKER: Well, first of all, they've got to sustain them. They've got to ascertain, you know, if there are injuries, you know, what's their situation. They can through that hole pump oxygen. They can put down food; they can put down water, emergency supplies, anything to sustain them.

Now, you've got two options. How do you get them out? You either go back underground and resume the underground rescue operation in that mine, or you bore a much bigger hole and you put down a rescue capsule.

That was done in the rescue, I believe, in Pennsylvania, but here we're talking about a lot more distance between the top of the mountain and where those miners might be. That rescue hole to get that capsule down we're told could take anywhere up to three weeks.

Hope the miners are alive

MARGARET WARNER: And on what are they basing their hopes that, in fact, the miners are alive? Is it strictly the sounds they heard? Do they think they could have survived this long?

BRENT HUNSAKER: The sounds really were the first hint, the first clue that perhaps they're still alive, because, frankly, in the previous three boreholes that they drilled, they have no proof of life. But with those sounds, it gave them renewed hope that perhaps they are down there somewhere, they just have to find them.

And, again, where they're drilling these holes is a matter of best educated guess. They just keep poking holes in the mountaintop hoping that somewhere behind that rubble they'll find those miners alive.

MARGARET WARNER: And did the miners have -- are they believed to have enough oxygen down there? And do they have water?

BRENT HUNSAKER: They have plenty of water. There's groundwater seeping into the mine all the time, and you can drink it. It will sustain you.

As far as air, that's a mixed question. Right now, through two previous boreholes that they drilled, they are pumping at the rate of about 9,000 cubic feet a minute oxygen down into the mine. When they drilled the very first borehole, they found only 7 percent oxygen, not enough to survive on.

When they drilled the second borehole or third borehole, rather, into an area where they thought they might have escaped to if they found bad oxygen, they found 16 percent. You can survive on 16 percent oxygen. Normal is about 21 percent. So there is hope that there is oxygen somewhere down there where they can breathe and survive.

MARGARET WARNER: All right, Brent Hunsaker, Salt Lake City television, thank you so much.