Ship Canal Water Quality project update

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Dear neighbors,

We’ve talked a lot about the slurry wall construction happening in Ballard to support the excavation of the vertical shaft. As soon as September, we’ll start shaft construction in Fremont and Queen Anne followed by Wallingford. These neighborhood shafts are less than half the diameter of the Ballard shaft (roughly 37-47 ft) and will be supported by “secant pile” walls. (The shaft in East Ballard is about 11-ft wide and will be constructed with a different support method.)

Photo showing an example of secant pile wall construction on a previous SPU project.

This photo shows secant pile wall construction taking place on a previous Seattle Public Utilities project in Seward Park. 

A secant pile wall is another type of construction system used to support underground excavations. It is made up of overlapping vertical concrete piles, which together hold back surrounding soil to allow for excavation and underground construction. To create a pile, a hole is bored into the ground using a drilling machine and is filled with concrete. During this phase of construction in each of these neighborhoods, you should anticipate:

  • More heavy equipment on site like the drilling machine, crane and rebar cages.
  • Noise and vibration from the drilling machine. If you live or work within a few blocks of a site, you may be able to feel the vibration in your building. This is expected. We are monitoring vibration levels on site to ensure they are within allowable levels.
  • Trucks in and out of the site to haul away excavated material and deliver concrete.


Slurry wall construction continues through early September. During this time, you should anticipate:

  • Heavy truck traffic on Shilshole Ave NW and 24th Ave NW; please pay attention to flaggers.
  • Parking restrictions along the east side of 24th Ave NW so construction trucks can exit the work site.
  • Noise and vibrations related to excavation and concrete pours.
  • Longer than normal working hours; crews will be working nights and weekends. We are monitoring noise levels.

East Ballard

Photo showing crews preparing equipment for jet grouting.

Crews prepare equipment for soil stabilization.

Soil stabilization work continues in East Ballard for the next several weeks.

Impacts include:

  • NW 45th St is closed to traffic; vehicles must detour onto NW 46th St.
  • 11th Ave NW will allow two-way traffic via one lane controlled by flaggers during work hours.
  • Burke-Gilman Trail users are detoured to the north side of NW 45th St; flaggers to help direct traffic. Please follow all detour guidance on site. Bicyclists must cross train tracks at 90-degree angles.
  • Heavy noise and vibrations. If you live or work within a few blocks of a site, you may be able to feel the vibration in your building. This is expected. We are monitoring vibration levels on site to ensure they are within allowable levels.

See anticipated traffic impacts through 2022 on our website.


Over the next two weeks, crews will relocate existing utilities and construct the guide walls for shaft secant pile construction (see full description at the beginning of this message). Secant pile construction is expected to begin at the end of the month and should last through October.

Over the next few weeks, you should anticipate:

  • NW 36th St between Leary Way NW and 3rd Ave NW to be closed (through remainder of the project).
  • Pedestrians detoured to the north side of Leary Way NW.
  • A pump and bypass system running 24/7 to re-route an existing drainage line around the secant pile construction. This system is powered by a generator and will be in place through the end of the year.
  • Crews will perform one day of overnight work in Leary Way NW to decommission a water main. Please pay attention to signage on site. This work is done at night because it requires water to be shut off. Some residents and businesses will experience temporary water shut offs during this time. If your water service will be impacted, you will receive a door hanger from our crews five days in advance. Learn how to prepare for a water shut off (translations available)
  • More equipment staged on site (such as a crane) and concrete trucks moving in and out.
  • Noise and vibrations typical of a construction site.


Crews are re-mobilizing to our Wallingford site. For the first several weeks of construction, crews will:

  • Install stormwater control and remove contaminated soils.
  • Remove the existing chain link fence, gate, posts, and stairs.
  • Remove existing asphalt, concrete, and some trees.
  • Remove existing utilities.

You should anticipate:

  • The eastern sidewalk on Interlake Ave N to be closed near the work site.
  • Impacts to the northbound traffic lane on Interlake Ave N. Please pay attention to signage on site.
  • Increased truck traffic through the area.
  • Typical noises/vibrations related to construction.

Queen Anne

Over the next few weeks, crews will remove existing asphalt, gravel, and utilities and set up the Ship Canal Trail detour as early as Aug. 17. Secant pile wall construction is expected to start in September.

For the next few weeks, you should anticipate:

  • The West Ewing Mini Park parking lot to be closed. This closure is anticipated to last through mid-2023.
  • A localized Ship Canal Trail detour mid-August through summer 2022. See our previous update for a map.
  • Noise and vibrations typical of a construction site.
  • Equipment being staged in the area.

Contact us

Please email with questions or comments or call (206) 701-0233. You can also find information online at


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