The Environmental Protection Agency's revision of its March 2011 proposed rule on boiler maximum achievable control technology (MACT), announced on Dec. 2, would offer industry more flexibility in meeting emission targets, the agency says. EPA plans to finalize the rule, which would apply to the 1% of boilers that emit the most pollutants, in spring 2012. The Council of Industrial Boiler Owners says the revision would ease compliance for sources.
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.