Tunnelbuilder Promoting the world's tunnelling industry to a huge qualified audience

View the Spanish Tunnelbuilder website View the Italian Tunnelbuilder website

Archive Search

United States

United States, Washington D.C - us/109

Combined sewer overflow

DC Water (District of Columbia Water and Sewer Authority) has issued notice to proceed to the CBNA-Halmar Clean Rivers Joint Venture comprising CBNA (a US based subsidiary of Bouygues Construction) and Halmar International for the design-build contract for the Potomac River Tunnel. The tunnel is a project part of DC Water’s USD 2.99bn (EUR 2.76 bn) Clean rivers project designed to control combined sewer overflows and to improve water quality in the Potomac River in Washington D.C. The contract value is USD 819 million (EUR 757.13 million).  The main tunnel, which is 5.5 miles (8.9 km) long and approximately 100 feet (30 m) deep with internal diameter of 18 feet (5.5 m), will cross variable geological conditions (clay, alluvium, hard rock) and will pass close to Washington D.C's iconic monuments. It will require the use of two TBMs customized specifically for these soil conditions. Ancillary structures comprise of 9 shafts, adits connecting to the main tunnel, and near surface structures which link the new infrastructure to the existing sewage system. Visit https://www.bouygues.com/ and https://www.dcwater.com/. 49/23.