Nearly a year after President Obama signed an executive order calling on the federal government to reduce greenhouse-gas emissions 28% by 2020, agencies have outlined plans for achieving those green goals. The White House Council on Environmental Quality and the Office of Management and Budget reported on Sept. 9 that 56 federal agencies had submitted sustainability performance plans that will serve as frameworks for future sustainability efforts. Although many of the plans focus on practices such as reducing waste, some of the agencies’ strategies give significant weight to green design and construction goals. For example, the General Services Administration’s plan
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.