The District of Columbia Water and Sewer Authority’s board of directors approved a $819 million design-build contract earlier this month for the construction of the Potomac River Tunnel, the largest ever awarded by the authority, according to a press release.
The 5.5-mile-long tunnel aims to control sewer overflows into the Potomac River and forms part of the $2.99 billion Clean Rivers Project, an initiative to improve area water quality.
The joint venture of Miami-based CBNA and Nanuet, New York-based Halmar International will build the 18-foot diameter tunnel, which will run beneath the Georgetown waterfront in Washington, D.C., and connect to the existing Anacostia River Tunnel. The CBNA and Halmar team expect to begin work on the project in 2024, with completion in early 2030, according to the release.
Construction will require two tunnel boring machines: one will mine south through mostly soft ground and the other will head north to bore through rock. Once operational, the Potomac River Tunnel will reduce combined sewer overflows to the Potomac River by 93% in an average year of rainfall, according to DC Water.
That will be a major achievement for the overall Clean Rivers Project, said David Gadis, DC Water CEO and general manager.
“The Clean Rivers Project is a gamechanger for the district,” said Gadis. “We have already seen the impact the completed 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 into 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 rainfalls before it reaches those rivers.