The Massachusetts Water Resources Authority on June 25 awarded a $4.9-million contract to the Boston office of Stantec for engineering services on the 45-year old, 60-mgd West Roxbury Wastewater Tunnel. The 12-in thick cast-in-place concrete lining in the 12,500-ft long, 84-in dia. rock tunnel, which serves about 125,000 homes and businesses, is eroded due to hydrogen sulfide corrosion. J.F. White, Framingham, Mass., will inspect the tunnel, which has two portals and a 220-ft deep shaft, this fall to help determine the extent of the problem and the relining solution. "The 12-in liner is structural and as of a decade ago
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.