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New sewer construction prompts overnight work in the Magnolia Bridge/Smith Cove area



A sewer utility project will prompt traffic revisions near the Smith Cove/Terminal 91 area of South Magnolia beginning on Monday, July 7. Ramp closures may extend up to two weeks.

The project is part of King County’s commitment to protect Puget Sound by controlling overflows of stormwater and sewage during heavy rains. Work involves constructing a 3,000-foot long gravity sewer pipeline under the Magnolia Bridge to connect the new pipe to the County’s existing sewer line on Port of Seattle property north of the bridge. This work will require trenching through the on- and off-ramps, which will be closed one at a time.

Construction will be performed overnight from 7 p.m. to 7 a.m. during lower traffic periods. During this time, access to the Elliott Bay Marina, Palisade and Maggie Bluffs restaurants via the Magnolia Bridge will be maintained. Travel to and from 15th Avenue West and the Magnolia community will also be maintained.

Prepare for detours around the Magnolia Bridge ramps for several nights, allow extra time for commuting and follow signage instructions. There will be flaggers and signs to direct motorists, pedestrians, and bicyclists around closure. Metro Transit routes 19, 23, and 33 will maintain regular service.

A 1.5-million-gallon underground tank will store excess flows of stormwater and sewage when heavy rains fill pipes, reducing untreated overflows to Puget Sound. This facility will store peak combined sewer flows so that discharges of untreated wastewater and stormwater are limited to no more than one per year on a long-term average.

For ramp closure updates, call the 24/7 Construction Hotline at 206-205-0968. For more information and detour route maps, visit the project website at

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