Action Taken to Strengthen Underground Coal Mine Seals
What MSHA says is only its fourth emergency temporary standard was published in May 22's Federal Register to require stronger seals in underground coal mines. This rule's publication beat by seven months the deadline set by the MINER Act and responded to the causes of two 2006 fatal explosions in West Virginia and Kentucky mines.
"Based on MSHA's accident investigation reports of the Sago and Darby mine explosions, MSHA's in-mine seal evaluations and review of technical literature, and the National Institute for Occupational Safety and Health's reports on explosion testing and modeling, we have concluded that immediate action is necessary to provide additional protections for our nation's underground coal miners," said Richard E. Stickler, assistant secretary of labor for mine safety and health.
The standard sets requirements to strengthen the design, construction, maintenance, and repair of seals, and it also contains requirements for sampling and controlling atmospheres behind seals. For new seals, it sets a three-tiered approach:
- Seals may be constructed at 50 psi, but the atmosphere behind them must be monitored and maintained inert;
- if the atmosphere is not monitored and maintained inert, the seals must be constructed at 120 psi -- six times stronger than MSHA's requirement at the time of the Sago blast in early 2006; and
- where higher explosion pressures are possible within sealed areas that are not monitored or maintained inert, the seals must be greater than 120 psi.
MSHA said mine operators must submit design and installation applications for MSHA's approval, and the seals' design plans must be certified by a professional engineer. MSHA has posted preliminary designs for 50 psi and 120 psi seals at www.msha.gov.
Reflecting MSHA concluded that lighting triggered the Sago blast via cables that were connected to a sealed area; the standard requires that insulated cables be removed from future areas to be sealed and bars welding, cutting, and soldering with an arc or flame within 150 feet of a seal. MSHA will hold four public hearings on the standard: July 10 in Morgantown, W.Va.; July 12 in Lexington, Ky.; July 17 in Denver; and July 19 in Birmingham, Ala.