CH2M Hill Plateau Remediation Co. Workers remove the east end of a highly contaminated tank in the 209-E Critical Mass Laboratory to provide access to two storage tanks as part of the facility's demolition. CH2M Hill Plateau Remediation Co. Crews spent two months developing mockups, even fabricating non-contaminated replica tanks, to insure safe demolition of 11 large tanks formerly used in weapons production experiments. With radioactive contamination saturating the 209-East Critical Mass Laboratory at the U.S. Dept. of Energy’s Hanford Nuclear Waste Site in southeast Washington, contractor CH2M Hill Plateau Remediation Co. needed new techniques to demolish the nearly 9,000-sq-ft
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.