Courtesy of InfoSense SL-RAT sends sound waves through pipes to find blockages. The Charlotte-Mecklenburg County, N.C., Utilities Division (CMUD) uses CCTV cameras to inspect its underground sanitary sewer pipes for blockages and interferences, but a new device that sends acoustical waves through sewer pipes is giving the utility a more accurate view.“Often, the [CCTV] images were so dark and murky or the system would get hung up, and we couldn’t get a clear picture,” says John Fishburne, senior engineer in CMUD’s field operations division. “We wound up cleaning pipes that, in many cases, didn’t need it.”In 2005, CMUD commissioned Ivan
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.