A mine operator failed to recognize and anticipate the potential for pillar burst conditions and did not develop and implement a method to mine safely, which led to the deaths of two miners May 12, federal officials said.
In addition, mine management took insufficient action to investigate a rib burst accident that occurred three days earlier, and it failed to address hazardous conditions that caused the rib burst, said officials at the Mine Safety and Health Administration (MSHA), which released the findings of its investigation into the incident at the Brody Mine No. 1 that killed Eric Legg, a 48-year-old continuous mining machine operator, and Gary Hensley, a 46-year-old roof bolting machine operator. Brody Mining LLC, a subsidiary of Patriot Coal Corp., operates the underground coal mine in Boon County, West Virginia.
Legg and Hensley died when a large pillar of coal burst while retreat mining was underway. Retreat mining is an underground mining technique that involves extracting coal while leaving behind pillars for support, then returning to mine the pillars in a precise sequence that causes the roof to collapse as mining “retreats” back toward the mine’s entrance. The pillar burst caused a large amount of coal from the mine ribs, or walls, to suddenly and violently eject into the mine entry, filling the entry to within 30 inches of the mine roof.
A pillar burst occurred in the same section of the mine on May 9 — approximately 100 feet away —the company never reported to MSHA.
As a result of its investigation, MSHA issued three citations to the mine operator for failure to:
• Support or otherwise control the mine ribs in order to protect miners from exposure to the hazardous conditions associated with a coal burst
• Recognize a “precursor” burst that occurred on May 9
• Take adequate corrective actions to protect miners from hazardous rib conditions
• Develop and implement a plan, or method, of mining designed to eliminate the hazardous conditions associated with a coal burst
• Immediately report the accident that occurred on May 9
• Preserve the accident site where the May 9 burst occurred
Bursts, also known as bumps or outbursts, are the sudden and violent failure of overstressed rock or coal, resulting in the instantaneous ejection of material into mine openings. When such events occur in active workings, they pose a serious hazard to miners.
Violent coal bursts are relatively rare events. Prior to the fatal rib pillar burst accident at Brody Mine, no previous history of bumps or coal pillar bursts ended up reported to MSHA at that mine or occurred at any other active operation mining in the Eagle Seam, one of deepest and most extensively mined coal seams in southern West Virginia.
Immediately following the Brody Mine accident, MSHA launched a review of retreat mining under deep cover to determine if they needed to do any additional actions. The agency is currently assessing what other precautions need to happen to mitigate the burst risk, particularly at deep cover mines with depths exceeding 1,000 feet.
The mine operator discontinued retreat mining activities at the mine and has discontinued all mining in the eastern side of the mine where the fatal accident occurred.