By Ashley Karen
A JV of CBNA and Halmar received the Potomac River Tunnel design-build contract from DC Water.
The contract is worth US$819m (€778m), is the most considerable ever granted by the authority, and contains the construction of an 8.9km tunnel to control combined sewer overflows (CSOs) to the Potomac River in the US capital.
It is part of the great Clean Rivers Project, a US$2.99bn (€2.84bn) schedule to enhance the water quality of the Anacostia and Potomac rivers and Rock Creek by improving the sewer system capacity.
The Anacostia River and Potomac River tunnel systems contain over 29km of tunnels.
The 5.5m-diameter Potomac River Tunnel will operate under the Georgetown waterfront and link by gravity to the current Anacostia River Tunnel.
Construction will need two tunnel boring machines; one will be launched from West Potomac Park to mine south through mostly soft ground; the other will head north to excavate through rock.
Work on the project is anticipated to start next year, with completion in early 2030. When operational, the project will decrease the volume of CSOs to the Potomac River by 93% and the number of CSOs from about 74 to four in an average year of rainfall.
David L Gadis, DC Water CEO and general manager, stated: “The Clean Rivers Project is a game-changer for the District.”
He added: “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.”
