One year after dikes failed at the Tennessee Valley Authority’s Kingston coal-fired powerplant near Knoxville, Tenn., and sent coal ash spilling over 300 nearby acres and into the Emory River, contractors have removed two-thirds of the river waste and are halfway through the $1-billion cleanup. But the agency and regulatory officials are struggling with how to prevent a repeat of the Dec. 22, 2008, catastrophe. Photo: Sevenson Environmental Services Ash waste that spilled into the Emory River is most critical portion of TVA remediation project. Tom Kilgore, TVA’s CEO, told a congressional subcommittee this month that he expects cleanup 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.