Seattle’s Ship Canal Water Quality Project has been completed.
The core of the project, delivered by Webuild US subsidiary Lane, is a 4.25km-long storage tunnel designed to reduce combined sewer overflows into the Lake Washington Ship Canal, Salmon Bay and Lake Union.
The 5.7m-diameter tunnel can store more than 112 million litres of excess flow during storms. The water is then conveyed to a treatment facility for processing.
The storage tunnel drive was completed in 2023 when the Herrenknecht EPBM named Mudhoney broke through into a flooded shaft in Wallingford.
The conveyance tunnels – one with 2.4m internal diameter, and the other 2.1m – were completed by two remote-controlled Herrenknecht TBM.
The US$255m project was commissioned by Seattle Public Utilities through a partnership between the City of Seattle and King County.
