Image Courtesy Environmental Defense Fund and Google Maps Methane leaks from natural-gas lines, such as these shown on a map of New York City's Staten Island (right), add to greenhouse gases. A cooperative effort between the Environmental Defense Fund and Google Earth Outreach aims to help utilities find them. Related Links: Environmental Defense Fund natural gas leak project EPA overview on greenhouse gases Rapid and accurate detection of methane leaks is being offered to natural-gas utility companies following a successful pilot project led by the Environmental Defense Fund, in partnership with Google Earth Outreach.The program uses Google Street View cars
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.