Crews at the U.S. Energy Dept.’s Hanford nuclear-waste cleanup complex in eastern Washington are reactivating a 45-year-old site crane to remove close to 200 waste tanks, each three to 22 ft long, that are contaminated with plutonium. DOE contractor CH2M Hill Plateau Remediation Co. opted to restore the crane as the safest approach to extract the so-called “pencil tanks,” thinly shaped to prevent uncontrolled plutonium releases during the site’s Cold War-era atomic weapons production. Photo: Courtesy of CH2M Hill Plateau Remediation Co. Revamped crane will lift thin plutonium-tainted tanks to a yard where workers will decontaminate them safely. The 5-ton
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.