US contractor Lane Construction is to join forces with Salini Impregilo of Italy to built a $580m "super sewer" in Washington, DC.
The Northeast Boundary Tunnel (NEBT) will be a large, deep drainage tunnel that will increases the capacity of the District’s wastewater system, thereby reducing the frequency, magnitude and duration of sewer flooding and improving the water quality of the Anacostia River.
The contract was awarded by the District of Columbia Water and Sewer Authority, with Lane taking 70% and Salini the remaining 30% of the work.
The NEBT will be the biggest component of the authority’s Clean Rivers Project and will run from south of Robert Kennedy Stadium to the intersection of Rhode Island Avenue and 6th Street, a distance of about 8.2km.
In times of flooding, the tunnel will convey excess water to the Blue Plains Advanced Wastewater Treatment Plant.
Once it is connected to the other Clean Rivers Project tunnels, the NEBT will help reduce combined sewer overflows to the Anacostia River by 98% and reduce the annual chance of flooding in the areas it serves from 50% to 7%.
Work is expected to begin in September 2017 and be completed in 2023.
Image courtesy of Salini Impregilo