The Tennessee Valley Authority will seek engineering and construction proposals next month to convert to dry storage all of its wet-storage impoundments for combustion by-products. The project, which will take until 2020 to complete and could cost up to $2 billion, follows the 2008 failure of a coal-ash pond at the utility’s Kingston, Tenn., powerplant that spilled 5.4 million gallons of waste material over 300 acres and into the Emory River. Cleanup could cost $1.2 billion. Photo: TVA Tennessee ash spill pushes TVA to rethink waste storage at all powerplants. Robert Deacy, TVA senior vice president for clean strategies and
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.