Lane Completes Ship Canal Water Quality Project Tunnel in Seattle
Lane, the U.S. subsidiary of the Webuild Group, has completed the Ship Canal Water Quality Project in Seattle. The project features a large underground storage tunnel to reduce significantly polluted stormwater and untreated sewage that enters the Lake Washington Ship Canal, Salmon Bay and Lake Union.
Commissioned by Seattle Public Utilities through a partnership between the City of Seattle and King County, the $255-million project represents a critical investment in protecting regional waterways and safeguarding public health.
In several historic Seattle neighborhoods—including Ballard, Fremont, Wallingford, and Queen Anne—stormwater and sewage share a single pipe system. While efficient during dry weather, heavy rainfall can overwhelm capacity, leading to combined sewer overflows (CSOs) of stormwater and wastewater into local water bodies. The new tunnel, measuring 2.7 miles (4.3 km) in length and 18 ft, 10 in. (5.7 m) in internal diameter, addresses this challenge by capturing and temporarily storing more than 29.6 million gallons (112 million liters) of excess flow during storm events. Once storm conditions subside, the stored water is conveyed to a treatment facility for proper processing.
The tunnel delivers vital environmental and community benefits by preventing up to 75 million gallons (284 million liters) of polluted stormwater and sewage from entering local waterways annually, improving water quality for aquatic ecosystems and wildlife habitats, and enhancing urban resilience against increasingly frequent and severe storm events.
Tunnel excavation was carried out using a 20-ft diameter tunnel-boring Machine (TBM) named “MudHoney” that ensured precise and efficient operation beneath the urban landscape.
The completion of the Ship Canal Water Quality Project underscores the extensive underground tunneling expertise of Webuild and Lane in the United States, backed by a track record of more than 100 miles (160 km) of tunnels and over 200 projects executed across major metropolitan centers including New York, Chicago, San Francisco, Las Vegas, Washington, D.C., Cleveland, Portland, and Dallas. Current U.S. tunneling projects include the Ohio River Tunnel in Pennsylvania and the Palisades Tunnel in New Jersey.
