MSHA Finalizes Mine Seals Rule

MSHA issued a final rule today that takes effect immediately and sets requirements for stronger seals inside underground coal mines. The agency made some changes in the Emergency Temporary Standard it has had in place since March 22, 2007, and it designed this final rule to dictate strength, design, construction, maintenance, repair of seals, recordkeeping, and monitoring and control of atmospheres behind seals to reduce the risk of seal failures and cut the risk of explosions in abandoned areas.

For example, the rule adds a recordkeeping section to 30 CFR Part 75 that says gas sampling records must be kept one year, while the training certification for people sampling the atmosphere and for people who construct and repair seals must be kept for two years.

The emergency standard followed the Sago Mine explosion on Jan. 2, 2006, in West Virginia and the May 20, 2006, explosion at the Darby Mine No. 1 in Kentucky -- events that killed a total of 17 miners. Failures of seals constructed to a 20 psi standard were involved in both. The emergency standard also followed a Feb. 8, 2007, NIOSH report, "Explosion Pressure Design Criteria for New Seals in U.S. Coal Mines," which recommended requiring stronger seals.

MSHA said this new final rule "assures that miners can rely on seals to protect them from the hazardous and sometimes explosive environments within sealed areas." The rule requires that seals constructed in underground coal mines after Oct. 20, 2008, be designed and constructed to withstand at least 50 psi overpressure when the atmosphere in the sealed area is monitored and maintained inert and to withstand overpressures of at least 120 psi if the atmosphere in the sealed area is not monitored, is not maintained inert, and (i) the atmosphere in the sealed area is likely to contain homogeneous mixtures of methane between 4.5 percent and 17.0 percent and oxygen exceeding 17.0 percent throughout the entire area; or (ii) pressure piling could result in overpressures greater than 120 psi in the area to be sealed; or (iii) other conditions are encountered, such as the likelihood of a detonation in the area to be sealed.

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    October 2019

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