At least 30,000 tons of coal ash poured through a broken Duke Energy stormwater pipe and into the Dan River earlier this month. The spill is the third largest of its kind in US history.
But that spill was much smaller than an accident in Tennessee six years ago.
It was the middle of the night, three days before Christmas in 2008 when part of a retention wall at a Tennessee Valley Authority coal ash pond ruptured. A dike failed and millions of gallons of potentially toxic waste were unleashed.