The U.S. Environmental Protection Agency will develop regulations for coal- ash storage by the end of the year, says EPA administrator Lisa Jackson. The March 9 decision comes 10 weeks after a dike burst at a storage impoundment at a Tennessee Valley Authority plant, spilling about 5.4 million gallons of coal-ash slurry. EPA will ask experts to assess the integrity of 300 units across the country that store ash suspended in liquid. It is working closely with dam safety experts because of structural similarities of coal-ash impoundments and dams.
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.