Environmental assessment released for Alexandria sewer tunnel26 June 2019
USA – Alexandria, Virginia, announced its preferred alignment for a deep tunnel sewer, excavated by TBM, on June 19, releasing an environmental assessment for comment through July 19.
The tunnel is part of RiverRenew, an initiative to reduce CSOs. The proposed sewer will be 2 miles (3.2km) long with a 19ft (5.8m) outside diameter (12ft inner), approximately 100ft (30m) below ground in primarily Potomac clay.
According to the environmental assessment tunnelling would take two and a half years. Price estimates are USD 370M to USD 555M, based on a conceptual level of design.