MSHA Lists Communication Alternatives for Underground Coal Mines
Approved electronic systems to track the movements of miners inside underground coal mines are now available, but the fully wireless communications technology also called for by the MINER Act is "not sufficiently developed at this time, nor is it likely to be technologically feasible by June 15, 2009," MSHA said in a Program Policy Letter that offers guidance to mine operators. By that date, the operators must have submitted a plan to use wireless communications technology, the law states; the letter lists acceptable alternatives.
The PPL from Kevin Stricklin, administrator for Coal Mine Safety and Health, and Mark Skiles, director of Technical Support, on "Guidance for Compliance with Post-Accident Two-Way Communications and Electronic Tracking Requirements of the MINER Act" is available on the agency's Web site, along with MSHA's preliminary estimates of costs associated with implementing these MINER Act requirements.
The PPL says an alternative to a fully wireless communications system for post-accident communication can be a system used for day-to-day operations or a stored system used in the event of an accident, including leaky feeder, mesh and medium frequency systems. Any alternative system generally should have an untethered device that miners can use to communicate with the surface; enable two-way voice and/or two-way text messages; provide an audible, visual, and/or vibrating alarm that is activated by an incoming signal; be capable of sending an emergency message to each of the untethered devices; and be installed to prevent interference with blasting circuits and other electrical systems, the letter states. And the system must provide coverage for each working section in a mine, including all intersections; continuous coverage along the escapeways; and a coverage zone both inby and outby strategic areas of the mine, such as belt drives and transfer points, power centers, loading points, refuge alternatives, SCSR caches, and other areas identified by the District Manager.
It says portable devices, such as hand-held radios, "generally should provide sufficient power to facilitate evacuation and rescue following an accident. In many mining situations, at least 4 hours of operation in addition to the normal shift duration (12-hour minimum total duration) based on a 5/5/90 duty cycle generally should be adequate, but mine-specific conditions may warrant more or less capability."
Because approved electronic tracking systems are available, by June 15, 2009, operators must submit a plan that provides for determining the location of persons underground, the letter states.