An unstable and weak slime-like foundation was the primary factor behind the Dec. 22, 2008, catastrophic failure of a coal-ash pond at Tennessee Valley Authority’s Kingston plant near Knoxville, Tenn., says a root-cause analysis released last week by AECOM Technology Corp. TVA hired the firm after the accident to determine why dikes holding coal-waste slurry failed, flooding 300 acres around the plant and the Emory River with 5.4 million cu yd of coal ash. Photo: TVA Spill cleanup could cost $1 billion. Los Angeles-based AECOM’s analysis determined the dikes’ angle and setbacks, increased loads because of recent high fill 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.