Southern Nevada’s Nellis Air Force Base is trimming construction costs of a new child development center by nearly 4% by using a unique aerated plastic-riser foundation system. Graphic: Courtesy USAF Cobblestone Construction, Las Vegas, broke ground on the $7.2-million design-build project in August 2010 and later discovered that the six-acre site along the northwest edge of the base was contaminated with radon. The 26,000-sq-ft block building consequently required a gas ventilation system, which typically comprises a vapor barrier consisting of a membrane of washed rocks and liquid as well as perforated pipe and fans. Wright Engineers, Las Vegas, proposed a
The 2016 Summer Olympics boating and swimming events have put an international spotlight on what has been a long-running problem in Rio de Janeiro—untreated sewage and trash are clogging up major bays and waterways.