Congress has cleared legislation authorizing the U.S. Environmental Protection Agency to dole out up to $500 million over five years for diesel retrofits. The House passed the Diesel Emissions Reduction Act (DERA) on Dec. 21, sending it to the White House. The bill is seen as a boon for clean air, contractors and suppliers. In its first five years, DERA returned about $20 in benefits for each $1 spent, according to the Diesel Technology Forum.
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.