D.C. Water has awarded its largest contract to date — a $580 million design-build plan for a 5-mile tunnel that will help avoid combined sewer overflow into the Anacostia River.
A joint venture of Salini Impregilo and S.A. Healy will design and construct the tunnel. Work is expected to begin in September with a completion date of 2023. Along with controlling sewer outflow, the tunnel construction is expected to reduce the chance of flooding in the areas it serves, including flood-prone sections of Rhode Island Avenue.
The new tunnel will start just south of RFK Stadium and terminate at the intersection of Rhode Island Avenue and Sixth Street NW. It is expected to be 23 feet in diameter, constructed with precast concrete segments, approximately 50 to 160 feet below the ground surface.
The work is part of the Clean Rivers Project, a $2.6 billion, 20-year civil works project that’s meant to correct a combined sewer system in place since the 1800s that needed drastically more capacity. The new 13-mile tunnel network, when completed, is expected to last for a century or more.