Coal-ash waste poses risk across the nation

The billion-gallon wave of toxic coal-ash sludge that burst from a power-plant retention pond and buried 300 acres of rural Tennessee hints at a far larger problem: hundreds of similar threats nationwide.

More than 1,300 coal-ash waste sites are dotted across the United States, about half of them actively used, federal data show. Some are landfills. The rest are “surface impoundments” (storage lagoons), which, like the one in Tennessee, mix ash with water.

Coal ash has some beneficial uses. It can be mixed with concrete to make roads, for example. But storing coal ash in a retention pond – common at coal-fired power plants nationwide – can be a threat to the environment and humans as well: The ash contains many toxic metals, including arsenic, lead, and chromium.