You might think Bill Dunn Sr., who heads up one of the nation’s largest prison builders, is trying to undo a part of the family business by starting a jobs program for ex-cons. Yet Dunn, 86, whose firm has been successful at building around 50 jails in the last 10 years, is troubled deeply by the prison system’s burden on society. “We felt that maybe we had an obligation to help people who needed a chance,” says the chairman emeritus of Kansas City, Mo.-based JE Dunn Construction. Building prisons, he says, costs $50,000 to $100,000 per cell. —Bill Dunn Sr.
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.