An ash dike ruptured at a solid waste containment area in Roane County, Tennessee, releasing 1.1 billion US gallons (4,200,000 m3) of coal fly ash slurry.

Roane County is a county of the U.S. state of Tennessee. As of the 2020 census, the population was 53,404. Its county seat is Kingston. Roane County is included in the Knoxville, TN Metropolitan Statistical Area.

The Kingston Fossil Plant coal fly ash slurry spill was an environmental and industrial disaster that occurred on Monday December 22, 2008, when a dike ruptured at a coal ash pond at the Tennessee Valley Authority's Kingston Fossil Plant in Roane County, Tennessee, releasing 1.1 billion US gallons (4.2 million cubic metres) of coal fly ash slurry. The coal-fired power plant, located across the Clinch River from the city of Kingston, used a series of ponds to store and dewater the fly ash, a byproduct of coal combustion. The spill released a slurry of fly ash and water, which traveled across the Emory River and its Swan Pond embayment, onto the opposite shore, covering up to 300 acres (1.2 km2) of the surrounding land. The spill damaged multiple homes and flowed into nearby waterways including the Emory River and Clinch River, both tributaries of the Tennessee River. It was the largest industrial spill in United States history.The initial spill, which resulted in millions of dollars worth of property damages and rendered many properties uninhabitable, cost TVA more than $1 billion to clean up, and was declared complete in 2015. TVA was found liable for the spill in August 2012 by the U.S. District Court for the Eastern District of Tennessee. The initial spill resulted in no injuries or deaths, but several of the employees of an engineering firm hired by TVA to clean up the spill developed illnesses, including brain cancer, lung cancer, and leukemia, as a result of exposure to the toxic coal ash, and by the ten year anniversary of the spill, more than 30 had died. In November 2018, a federal jury ruled that the contractor did not properly inform the workers about the dangers of exposure to coal ash and had failed to provide them with necessary personal protective equipment.