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Ship Canal Water Quality Project
Owner: Seattle Public Utilities
Location: King County, WA
Project Cost: $570 million/ Lane's share is $255 million
Project Type: Tunneling | Procurement Type: Bid-Build
State: Washington | Status: Ongoing
Sewage and stormwater from many older parts of the City of Seattle including the Ballard, Fremont, Wallingford, and Queen Anne neighborhoods, is collected and conveyed in one set of pipes.
In dry weather conditions, all sewage flows to a local wastewater treatment plant. During wet weather conditions, polluted runoff can exceed the pipes’ capacity and send a mixture of stormwater (90%) and sewage (10%) to outfalls that flow into the nearest water body. These combined sewer overflows, or CSOs, contain contaminants that can affect public and environmental health.
The 2.7-mile, 18’10” internal diameter tunnel, known as the Ship Canal Water Quality Project – Storage Tunnel project, will keep more than 75 million gallons of polluted stormwater and sewage out of the Lake Washington Ship Canal, Salmon Bay, and Lake Union on average each year.
- 2.7-mile, 18-ft and 10-inch internal-diameter tunnel
Benefits/Positive Aspects to Community:
- Prevents, on average, up to 75 million gallons of polluted stormwater and sewage from entering Lake Washington Ship Canal, Salmon Bay, and Lake Union each year.