Blue Ridge Low Level Outlet
In 2002, the Tennessee Valley Authority awarded Atkinson a $14.8 million design-build contract for work on the Blue Ridge Dam in north Georgia. Originally constructed in 1925, this hydroelectric dam—standing 167 feet high and spanning 1,000 feet—was designed to generate electricity and reduce flood damage on the Toccoa River.
In an effort to provide the Blue Ridge Reservoir with an alternative means for regulating water elevations, Atkinson built a low-level inlet/outlet structure in the dam, which included the design and construction of a 975-foot-by-12-foot-diameter tunnel, 105-foot sheet pile cofferdam, flow control devices, and hydraulic energy dissipation systems.
During the excavation process, the team used traditional drill and blast techniques. The dam’s intake structure included the installation of a 16-foot-diameter by 50-foot steel intake liner and trashracks in the reservoir—in addition to a nine-foot-diameter by 1,000-foot steel pipe to accommodate flows of 1,800 cubic feet per second at an opening head of 130 feet. The finished steel pipe was encased in cellular concrete.
Atkinson built the intake using marine equipment. Following the completion of the intake structure, tunneling crews connected the tunnel to the intake structure.