Two years ago, residents of a small town in (the U.S. state of) Tennessee woke to a disaster in their backyard. A retaining wall from a nearby power plant dump site ruptured and sent more than four billion liters of coal ash slurry into the Emory River. The toxic brew washed out roads, uprooted trees and lifted homes from their foundations.  As VOA’s Rosanne Skirble reports, the event prompted the U.S. Environmental Protection Agency to consider federal controls on coal ash, the toxic byproduct in the generation of electricity.