The Environmental Protection Agency has asked a federal appeals court to give the agency 18 months to address what it termed a “flaw” in a 2009 stormwater regulation. The rule sets a limit on sediment discharges from construction sites. In April 2010, the Small Business Administration asked EPA to reconsider parts of that regulation. According to EPA, the SBA cited “potential deficiencies” with data used to arrive at the sediment limit. The National Association of Home Builders (NAHB) also challenged the sediment limits. NAHB says the cost of complying with the standard would have risen up to $10 billion a
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.