The U.S. Army Corps of Engineers gave final approval July 27 to Central Maine Power, a subsidiary of the Spanish-owned company Iberdrola USA, to begin work on a $1.4-billion electricity transmission network, one of the largest construction projects in Maine’s history. The project includes five, 345-kV substations linked by 450 miles of new or rebuilt transmission line. The line’s southern end will tie into the New England grid near the New Hampshire border and its northern end will link with Canadian transmission lines in Orrington, Maine. The utility has contracted with Maine contractors Cianbro Corp., Pittsfield, and RJ Grondin &
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.