Critics contend that the new emissions targets in a proposed Environmental Protection Agency rule for sulfur dioxides and nitrogen oxides carried downwind from powerplants in 31 eastern states and the District of Columbia could be difficult to achieve, but environmental advocates say the new proposal will result in cleaner air. EPA says the proposed rule, which EPA Administrator Lisa Jackson signed on July 6, would cut SO2 emissions by 2014 by 70% from 2005 levels and trim NOx emissions by 52%. Gina McCarthy, EPA’s assistant administrator for air and radiation, says the proposal is a “large and important step in
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.