The District of Columbia Water and Sewer Authority’s board of directors approved an $819 million design-build contract earlier this month for the construction of the Potomac River Tunnelthe largest ever granted by the authority, according to a press release.
The 5.5-mile-long tunnel aims to control sewer overflows in the Potomac River and is part of the $2.99 billion Clean Rivers Project, an initiative to improve water quality in the area.
The joint venture between Miami-based CBNA and Nanuet, New York-based Halmar International will build the 18-foot-diameter tunnel, which will pass under the Georgetown waterfront in Washington, DC, and connect to the tunnel of the existing Anacostia River. According to the statement, the CBNA and Halmar team expects to start work on the project in 2024, with completion in early 2030.
Construction will require two TBMs: one will blast south through mostly soft terrain and the other will head north to drill through rock. Once operational, the Potomac River Tunnel will reduce combined sewer overflows in the Potomac River by 93% in an average rainfall year, according to DC Water.
This will be a major achievement for the global Clean Rivers project, said David Gadis, CEO and General Manager of DC Water.
“The Clean Rivers project is a game changer for the district,” Gadis said. “We’ve already seen the impact the Anacostia River Tunnel System is having on the health of that river, and we expect similar results for the Potomac as a result of this project.”
The Clean Rivers Project is DC Water’s ongoing program to reduce combined sewer overflows in the District’s waterways, namely the Anacostia River, Potomac River, and Rock Creek. The project is a massive infrastructure and support program designed to capture and clean wastewater during rains before it reaches these rivers.
