Wednesday, August 22, 2007

Utah Coal Mine Troubles

The strange saga of Robert Murray and the coal mining disaster in Utah continues. It got my undivided attention when I heard the claims that the disaster was caused by an earthquake. The seismic activity in most of the Rocky Mountains is relatively quiet but a manmade disaster can be big enough to show up on seismographs. Somebody seemed to be pushing the argument for what happened backwards. Nine people died and the families deserve the facts, and not the usual spin that seems prevalent in the current Bush era.

The Salt Lake Tribune has been covering the disaster closely and here's an article by Robert Gehrke that raises a number of questions:
Robert Murray insists that his company did not change the mining plan at Crandall Canyon after purchasing a joint interest in the mine last August.

But documents obtained by The Salt Lake Tribune clearly contradict Murray's assertion, and show that Murray's company sought and received approval from federal regulators to make a significant, and, experts say, risky change to the mining strategy.

Records of the Mine Safety and Health Administration (MSHA) show that, after Murray acquired a 50 percent ownership in the mine on Aug. 9, 2006, his company repeatedly petitioned the agency to allow coal to be extracted from the north and south barriers - thick walls of coal that run on both sides of the main tunnels and help hold up the mine.

That stands in stark contrast to statements Murray made Monday asserting that his company's mine plan, and that of the previous owner, were one and the same.

(snip)

Documents on file with the Utah Division of Oil Gas and Mining show Andalex [the previous owner] had previously decided not to mine those barriers, determining it posed a risk to worker safety.

The article doesn't let the Bush Administration off the hook either. The MSHA took only seven business days to approve Murray's plan; given the serious safety issues involved and previous concerns, that seems rather quick. I'm also puzzled by the term, 'bump.' I don't know if that's a term used by miners or a euphemism used by owners. If my car tire suddenly goes flat, that's not a bump, it's a blowout.

In an era of high energy prices and high demands, we are going to see people push safety issues to the limit. We are going to see it in our country and we're going to see it elsewhere. I know enough about industry to know how safety can easily be chipped away so that people are put in increasing danger until somebody blows a whistle or disaster strikes. Business owners may not like regulation but there's usually a sad history behind the regulations and when it comes to safety, there are no excuses.

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3 Comments:

Blogger BT (lkrndu ''at'' tiscali ''dot'' it) said...

This comment has been removed by the author.

11:28 AM  
Blogger BT (lkrndu ''at'' tiscali ''dot'' it) said...

Well....one might ask one's friends and/or colleagues with background in the earth sciences! Since this writer is beholden neither to the gummint servers in SLC nor to the commercial mining interests in Huntington UT, he's willing to stick his long, brittle neck out and say with conviction that the only earthquake(s) here were the ones that resulted from large collapses of mine openings at Crandall.

The first trapped the unfortunate six. Subsequent 'bumps' in the slang of the miners collapsed the roof and blew out coal pillars, killing the three rescue crew later on.

Murray is a heroic and/or tragic type all too familiar to this writer in his geologic past. Dime a dozen. A 'pusher' is in fact the crew-level slang that applies, in fact as a semi-formal operating title. Get in there, get the coal out. Don't get stuck on the details.

The facts have emerged into the media slowly in this case, partly, this writer suspects, simply because the snore factor is high. The mechanism of mining, the risk factors and so on, don't make very exciting copy, while finger-pointing is higher on the anchor-chat food chain. Murray is a Central Casting perfect type to serve as angel and/or goat in front of the cameras.

So the truth will out, that is in official senses or in terms of record. Meanwhile what took place is not especially mysterious.

The mining method involves tunnelling in along a thick coal seam. Coal, as a 'rock' is relatively weak and plastic, subject to deforming or squishing under the weight it supports. So long as the seam is intact, it can support enormous weight, even weight greater than the failure strength of the coal, or so to speak, if one visualizes coal as if it were a construction material. Think taffy between layers of lead. Up to a certain point the stiffness of the taffy can support the overlying lead just fine, but beyond that, adding more lead above, the taffy will ooze or squeeze. Or it will, if nothing contains it laterally.

So in the mountain, the coal, intact, is contained or confined laterally. Enter the miners, and the mine cavities, the openings -- shafts (vertical opemings), tunnels and drifts (openings of horizontal extent).

Smart miners know that it will be safe to mine so long as some fraction of the coal seam is left in place to support the roof. Whether that is ten percent, fifty percent, or ninety percent depends on both the quality or strength of the coal, and on the depth of material, called overburden, overlying the coal. The Crandall Canyon mine is deep, with over a thousand feet of overburden pressing down on the coal.

The mine produces a cathedral in which the columns that support the roof are those remnants of coal. Economics motivates removing as much of the coal as possible, and miners exercise judgment -- or, run a calculated risk -- in reducing the sizes of those remnat coal pillars to some minimum. Time is a factor, too, and there is some wiggle room after coal is removed, in which pillars of minimal size and support capacity can hold up, before they do begin to fail and the mined-out zone collapses.

Crandall had been mined already, in the area where the deadly collapse took place. So there was an increased risk, working over an area that was already weakened. When the rescuers tried to tunnel back into the collapse debris, they were on at least the third pass, and undertaking an extremely dangerous mission.

The terms 'judgment' and 'risk' and so on are key, also. This writer hopes this reflection on the mining process, and on the geologic setting for this kind of coal mining, clarifies some of the background to what has taken place in Utah, both in the accident itself and in the consequent actions of the mine owners, crews, and government regulators.

11:31 AM  
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4:32 AM  

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