EPBM “MudHoney” has been lowered into the ground in Seattle, Washington, ready to get to work on the 4.3km long tunnel for the Ship Canal Water Quality Project. The Ship Canal Water Quality Project is a $570M program, being constructed by The Lane Construction Corporation, which has a $255M share of the project. When completed, the tunnel will prevent, on average, up to 75M gallons of polluted stormwater and sewage from entering the Lake Washington Ship Canal, Salmon Bay, and Lake Union each year.
Currently 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 new 5.75m diameter (18’10”) tunnel will capture and temporarily hold more than 29.6M gallons of stormwater and sewage during heavy rains. When the storm passes, flows will be released to the treatment plant. The project is expected to be completed by 2025 and is a joint project between the City of Seattle and King County.