Some Snohomish County water customers will lose service for up to 24 hours starting Nov. 19 when Everett shuts down a major pipeline for inspection.

Everett Public Works will take Transmission Line 5 offline from 12 a.m. Thursday, Nov. 19, through 12 a.m. Friday, Nov. 20, according to a city notice. An inspection tool will move through the pipe to measure wall thickness and roundness.

The shutdown will help determine which sections of the line need replacement as part of the broader Chinook Marsh Restoration project, which will relocate the pipeline.

Who is affected

Everett's transmission lines serve more than 657,000 people across Snohomish County, carrying drinking water from the city's filtration plant to reservoirs and wholesale customers.

The city's notice says the shutdown will cut service to "a portion of our customers in the affected area," but does not name specific water districts or neighborhoods.

A map of the affected area is referenced on the city's project page but was not included in the notice text.

The pipeline

Transmission Line 5 is a 51-inch-diameter steel pipe built in 1966 with a capacity of roughly 75 million gallons per day, according to the city's Chinook Marsh project page. Much of the pipeline sits above ground, with buried sections at road crossings and where it crosses Ebey Slough and the Snohomish River.

What happens and when

Preparation work along the pipeline route begins Wednesday, Nov. 18, during the day. Crews return late that evening.

At midnight Thursday, Nov. 19, workers begin depressurizing the line and shutting off service connections. The inspection runs during daytime hours Thursday and is expected to wrap up by 7 p.m.

By midnight Friday, Nov. 20, the city plans to refill the line, reopen service connections and restore normal pressure. All times are approximate and depend on conditions, the city said.

Virtual information sessions

Public Works will hold two virtual sessions for stakeholders affected by the shutdown:

  • Monday, Oct. 26, at 9 a.m.
  • Thursday, Oct. 29, at 1 p.m.

Invitations with a Microsoft Teams link will be sent to impacted water systems.

Chinook Marsh Restoration

The inspection feeds into the Chinook Marsh Restoration project, a Snohomish County effort to restore estuary habitat along the Snohomish River for Chinook salmon listed under the Endangered Species Act. Relocating Transmission Line 5 out of the restoration area will also improve the water system's seismic and flood resilience, the city said.

No construction start date or completion timeline for the relocation has been announced.

How to stay informed

Residents can subscribe to the "Everett Public Works - Transmission Line Maintenance" category on the city's news flash page for updates. Customers who get water directly from a transmission line and want to explore connecting to a distribution system can call Everett's 24-hour dispatch at 425-257-8821.

For those with sight impairments, the city's AlertSense application can deliver spoken messages by phone. Contact Sierra Garcia at 425-257-8991 or [email protected] to set it up.