Waited 41 hours as their limited air supply was used up, one breath after another. By the time rescuers found them, all but one had asphyxiated. A horrific realization became clear. If only rescuers had known the miners were alive all along, and where they were, maybe a quicker approach could have been mounted to reach them before it was too late.
Congress reacted to the disaster at Sago, and two other fatal mining accidents, with the Mine Improvement and New Emergency Response (MINER) Act, the most sweeping safety reform package in 30 years.
One of its many provisions required all underground mines to include two-way wireless communications and tracking systems in their formal emergency response plans by the middle of 2009. Updated requirements set a June 15, 2011, deadline to install approved systems.
To accelerate research to accomplish this goal, Congress allocated $23 million to the National Institute of Safety & Health, or NIOSH. The institute awarded 21 contracts to private companies to pursue promising technology on multiple fronts, from big-picture projects that design integrated communications and tracking systems for mines of all sizes to highly focused studies on the individual components that make those systems work. The innovations include lightweight hand-held radios for miners, helmet tags, radio repeaters, wireless transceivers and much more.
The results have been gratifying for Dave Chirdon, the federal Mine Safety and Health Administration's new technology program manager. The handiwork of this effort goes through MSHA's approval and certification center he runs before it can be commercially produced for use in mines.
"For me, it's unprecedented, the work that has been done producing this new generation of communication and tracking equipment," said Chirdon, a 27-year veteran of the approval process. "We are optimistic that some of the new technologies will work and we'll have a lot better ability to know where miners are underground at any given time."
Projects under way • About 20 plans have been approved (three dozen more are being evaluated), including Accolade, an acronym for a wireless mesh communications and tracking system developed through NIOSH's research contract process by a Virginia-based division of L-3 Communications. In April, PacifiCorp installed the Accolade system in its massive Deer Creek coal mine outside Huntington.
At a price of close to $2 million, L-3 Communications equipped the Emery County mine with a series of "nodes," small metal boxes that contain computer microprocessing chips and antennas. Spaced about 3,000 feet apart in all open directions of the mine, the nodes relay voice and text data on a 900 Megahertz-frequency wave from two separate spots on the surface.
"We looked at the whole spectrum of frequencies" before settling on 900 MHz, said L-3 Communications vice president Victor Young. "We call it 'the sweet spot.' The coal actually channels the signal. So even if there's not a direct line of sight between nodes, we get good crosscut coverage."
That's important. Like the grid system of Salt Lake Valley streets, mines are filled with intersections. Three or more parallel tunnels access most mining sections. These tunnels often extend for miles, intersected every 100 feet or so by "crosscuts" that serve as storage areas or have doors allowing movement between the parallel tunnels.
Crosscuts are often places where miners seek refuge if cut off from the surface by an explosion, fire or a roof fall. So it's imperative for a communication system to be able to branch right or left off main lines. And if any nodes are knocked out by a disastrous event, the system must be able to reroute the communications signal to flow among the nodes that remain intact, increasing prospects of maintaining contact between the surface and underground.
"There are a lot of overlaps designed into the system," Young said, noting that radio handsets distributed to each miner (in Deer Creek's case, about 350) all serve as nodes, as well as tracking devices.
Making a difference • Plenty of Deer Creek miners understand how this type of information could have saved the life of Gordon Conover, one of the 27 victims of a December 1984 fire that engulfed the Wilberg mine in Emery County. Trapped behind the fire, the wiry 24-year-old wandered through smoke-filled tunnels for nearly four hours, looking for an escape route, before he succumbed to carbon monoxide poisoning after reaching a spot where would-be rescuers had been earlier. The new technology surely would have enabled those rescuers to hook up with Conover long before he reached that deadly moment.
Although MSHA has approved L-3's system for use, it apparently falls short of the original congressional intent to develop a truly wireless system that does not require any transmission infrastructure such as the nodes between the surface and miners underground.
"I don't believe we have enough information to go on to be 100 percent convinced the systems will be available if a devastating incident were to occur," MSHA's Chirdon said. "We have increased the potential for a system to survive, but I don't know that we can guarantee it. At this point, we can't figure out how to duplicate a catastrophic event to test these systems."
L-3's Young said the Accolade system complies with the mandate, significantly reducing underground infrastructure needs while showing an ability to re-route signal flows around blockages.
"I like to use the cell phone analogy. We call those things wireless. We do the same thing underground," he said. "Our nodes are like the towers that cell providers use, finding the next nearest node to get a signal out of a mine. We are as wireless as your cell phone."
MSHA accepted that rationale in approving the wireless mesh networks. But it also is continuing studies of "through the earth" technology that will not require any intermediary infrastructure between miners and the surface.
An alternate approach • Another corporate giant, Lockheed Martin, secured a NIOSH grant to develop this technology. Its approach uses low-frequency magnetic waves "that can pass through many thousands of feet of ground where radio waves are squashed out at the very beginning," said Dave LeVan, an engineer behind the company's MagneLink Magnetic Communication System.
Those waves would be transmitted between antennas on the surface and computerized receptors, in explosion-proof enclosures, placed strategically around a mine.
Chirdon's certification center is still reviewing Lockheed Martin's technology for final MSHA approval, but LeVan and system program manager Warren Gross said initial testing in a Pennsylvania mine provided enough positive results that the company could start developing actual systems as soon as early next year.
Considerable work remains before the congressional mandate can be considered satisfied, Chirdon said.
MSHA will spend years comparing the performances of different systems to see what works well and what doesn't in the dusty, noisy, wet, dark environment of an underground mine. "We'll have to develop minimum performance standards, based on the best capabilities," he said. "We also have to help mine inspectors learn how the systems are installed and [how] to know when they are functioning as specified."
Even so, MSHA boss Joe Main hailed the progress achieved so far. "After many years of development, the type of communication and tracking systems Congress sought in the passage of the MINER Act is closer to becoming a reality."
The MINER Act
Required all underground coal operators to submit emergency response plans that included specific systems for two-way communications and electronic tracking of miners.
The law did not contain an installation date requirement. That has since been set for June 15, 2011
As of today, 23 percent of all mines have installed fully compliant systems.
About 20 different proposals have been approved out of nearly 200 ideas submitted.
Source: U.S. Mine Safety and Health Administration