On Friday, March 22 of this year, the rock crushed Elam Jones. Five months later, some say that same silence is deafening.
Like in Crandall Canyon, Jones and his cousin, Dallen McFarlane, were retreat mining when a 10-by-10-foot, 22-inch-thick slab of rock fell from the earthen ceiling.
The process involves excavating a room or chamber and removing the pillars as miners "retreat" so the roof collapses behind the mining area. Pillar removal has to occur in a precise manner to minimize the risk of injury or death to workers.
With Jones' death, it wasn't a pillar that collapsed, but a roof fall.
Veteran miners familiar with the circumstances of Jones' death say the cut sequence was changed because of the ARMPS program, going against what the miners said they know about safe mining.
"There was so much weight, it shifted," one said.
Another miner said the change in the cut sequence resulted in a lack of caves, or the roof falling.
"If you can't get a good cave, that is what causes the rock to override you," said the miner, who also spoke on condition of anonymity.
The agency insists ARMPS program has a good track record and pillar design case histories from Western U.S. mines are well-represented in the database. The agency pointed to a statistical analysis by the National Institute for Occupational Safety and Health that shows Western pillars do not differ significantly from Eastern ones.
The Mine Safety and Health Administration's preference for the retreat mining analysis program was stepped up in the aftermath of Crandall Canyon ,and all retreat mining plans at depths more than 1,500 feet were re-examined in the region.
An investigation revealed that while the ARMPS program was used in the development of the roof control plan at Crandall, a flawed engineering analysis by the mining consultants led to an inadequate mine design with unsafe pillar dimensions.
At the time, complaints and questions surfaced over the analysis program and its suitability for Utah mines.
"There were a lot of questions raised," Brune said. "A lot of soul-searching."
Brune teaches ARMPS to his students, as does Nelson. Nelson said ARMPS, LaModel and other computer programs are useful tools to assess a mine design plan, but they have limitations.
"The difficulty I see with these programs is they give an answer, but it is not the answer. When a computer gives an answer, it is easy for people to say, 'That's it, let's go with that.' In the case of a mining scenario, that is probably not the right approach."
Computer as tool
Nelson said computer programs that prescribe and predict mechanical behavior started with NASA and were extended to measure construction materials.
That works fine for homogeneous material such as steel or concrete, Nelson said, but not so much for rock, which has varying strengths and properties.
"I'm not saying it is not a useful tool, it is, but like all computer programs, they only provide guidelines, a starting place that can be used. Local conditions need to be assessed and evaluated on a continuing basis."
The miners said the Analysis of Retreat Mining Pillar Stability program does not take into account the vast differences in Utah coal and the deep underground mines in the state.
"Why are they putting so much faith in a computer program that goes against years and years of mining experience?" one questioned.
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