Big Branch Slurry Impoundment Breakthrough: Why it Happened and Lessons Learned

The Big Branch Slurry Impoundment in Martin County, Kentucky, broke into an underground coal mine in the Coalburg seam on 11 October 2000. Volume estimates of the water and fine coal refuse (slurry) spill range from 250 to 300 million gallons. The impact of the release on the environment was severe. Due primarily to the Herculean efforts of the owner, the spill was cleaned up and there were no fatalities and no injuries. Government officials commissioned studies to identify the cause of the spill and evaluate the practice of coal processing waste disposal in slurry impoundments to reduce the potential for breakthroughs at other sites. What caused the spill? What is the potential risk for an event like this to be repeated at other sites? What lessons can be learned from the Martin County spill by owners, designers, and government agencies to reduce the potential for spills in the future? Results of engineering analyses, performed using data generated from the government-commissioned studies, and opinions are presented as answers to these questions.