A main tunnel 8.9 km long and located 30 meters deep. A project which is part of DC Water’s Clean Rivers Project (2.99 billion USD), a vast program to improve water quality in the region.
DC Water has selected the CBNA-Halmar Clean Rivers consortium, a joint venture made up of CBNA (American subsidiary of Bouygues Construction) and Halmar International for the design-construction contract for the Potomac River Tunnel. This is a major environmental project aimed at preventing wastewater infrastructure overflows and improving the water quality of the Potomac River in Washington, D.C. This project amounts to US$819 million (US$758 million). euros).*
The objective of this project is to collect and store combined sewer discharges and runoff from the city of Washington DC before transporting them to the Advanced Wastewater Treatment Plant. operated by DC Water, in Blue Plains. The project will increase the capacity of the sewer network through deep storage tunnels and significantly reduce overflows, particularly during intense rainy periods, in order to control their impact on the Potomac River, the fourth largest river on the East Coast. the United States.
The main tunnel, 8.9 km long, 5.5 meters wide and approximately 30 meters deep, will cross variable geological horizons (clay, alluvium, hard rock) in addition to passing close to emblematic monuments of Washington DC It will require the use of two tunnel boring machines made specifically for these ground conditions. The ancillary works include 9 wells and drains, the connecting branches to the main tunnel and the connections to the existing sanitation network.
“We are proud of the trust placed by our client DC Water for the completion of this project. Bouygues Construction is mobilizing all of its expertise and confirming its commitment to major projects that contribute to improving water management in the United States. »
Bertrand Burtschell, general director of Bouygues Travaux Publics.
“We are honored to participate in the construction of this complex tunnel system that is essential to protecting such an important natural resource as the Potomac River. We look forward to working for DC Water on this ambitious project and seeing the benefits for years to come.” »
Chris Larsen, Chairman and CEO of Halmar International.
Work is scheduled to start at the end of 2023 for a construction period of just under 6 years. It should mobilize 400 employees during peak periods, with a strong commitment to local employment and the participation of SMEs in the local economic fabric.
The “CBNA Halmar Clean Rivers” joint venture will rely on its engineering partners Cowi and Hatch to carry out the design of the work, and is committed to carrying out this project with a sustainable approach.
Bouygues Travaux Publics is already building a tunnel in Pawtucket (State of Rhode Island, USA) to store runoff water, as part of a program to improve the water quality of Narragansett Bay.
* Total amount for the CBNA-Halmar Clean Rivers group: 819 MUSD (758 M€), including 749 MUSD (693 M€) already taken on order by the group and 70 MUSD (65 M€) of sums to be allow (“allowances”). The share taken by Bouygues Construction is 523 MUSD (482 M€).