The DC Water Board of Directors approved the Authority’s largest contract to date for the design and construction of the Northeast Boundary Tunnel.

The DC Water Board of Directors approved the Authority's largest contract to date for the design and construction of the Northeast Boundary Tunnel (NEBT). The 5-mi. NEBT is the largest and final segment of the massive tunnel system that will bring relief from combined sewer overflows (CSOs) to the Anacostia River. This work is part of the larger Clean Rivers Project, a $2.6 billion program to improve the water quality of the Anacostia and Potomac rivers and Rock Creek by increasing the capacity of the sewer system.

A joint venture of Salini Impregilo and S.A. Healy was selected based on the highest technical score and lowest price proposal, therefore providing the best value. The $580 million bid is for design-build, a contract type adopted by DC Water in recent years. Design-build allows for more contractor innovation and greater coordination with the contract owner.

“With this decision, the board of directors is making a tremendous investment in the future of the District of Columbia and the Anacostia River,” said Matthew Brown, DC Water Board chairman. “The scourge of combined sewer overflows has long contributed to the pollution in our waterways, and we are delivering on our promise to be part of the solution not the problem.”

Work on the project is expected to begin in September 2017 with completion in 2023, two years ahead of the schedule stipulated in the consent decree DC Water signed in 2005 with the U.S. Environmental Protection Agency and the Department of Justice. Once the NEBT is connected to the other tunnels already constructed, combined sewer overflows to the Anacostia River will be reduced by 98 percent. In addition to controlling combined sewer overflows, the construction of the NEBT will reduce the chance of flooding in the areas it serves from approximately 50 percent to 7 percent in any given year.

“This is the last piece of the puzzle for the Anacostia River tunnel system,” said George S. Hawkins, DC Water CEO and general manager. “When the NEBT is complete, we will have 13 miles of new capacity, providing relief to flood-plagued neighborhoods in the city's center and improving the water quality in the rebounding Anacostia River. I applaud the Clean Rivers team for their diligent work to keep this project on schedule and on budget, while ensuring it meets the highest standards for deep tunneling.”

The NEBT will start just south of RFK Stadium and terminate at the intersection of Rhode Island Avenue and 6th Street, NW. The proposed soft ground tunnel will be 23 ft. in diameter, constructed with precast concrete segments, approximately 50 to 160 ft. below the ground surface.

The NEBT is aligned to intersect with existing chronic flood areas along Rhode Island Avenue. Diversion facilities will be constructed to capture flows from the existing sewer system and divert them into the tunnel. Ultimately, all flow captured by the system will be conveyed to DC Water's Blue Plains Advanced Wastewater Treatment Plant. In addition to the tunnel and diversion facilities, the NEBT also will include the construction of ventilation control facilities, stormwater inlets and green infrastructure.

For more information, visit dcwater.com/NEBT.

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