Atlanta greenlights quarry tunnel project
25 June 2015The Atlanta City Council approved a USD 270M project to build a 5-mile- (8km-) long tunnel connecting the Chattahoochee River to and flooding a former rock quarry, creating a 30-day raw water storage vessel, local media reported.
The project will include new pump stations to draw water through the tunnel, which would be approximately 10ft (3m) in diameter and 200ft (61m) below ground, connecting to the Hemphill Water Treatment Plant and the quarry.
Work also includes replacing aging water transmission lines that are still in service. Cast iron mains of diameters 30", 36", and 48" were installed in 1893, 1908, and 1924 respectively. "Although these were renewed with a cement liner in the 1950s, they have far exceeded their design life. A fourth line, 72" steel main, was built in 1975 and metallurgical weaknesses restrict its operation to warm weather months," according to the City of Atlanta's Department of Watershed Management.
The council authorized a construction manager at Risk contract with PC/Russell on June 1.
