Slurry wall going up at Ship Canal Water Quality site at 24th and Shilshole

Work is steadily progressing on the project to improve water quality in the Ship Canal, with crews building a slurry wall at the Ballard site.

The Ship Canal Water Quality Project is a multiyear Seattle Public Utilities endeavor to build a 2.7-mile-long tunnel along the canal between Wallingford and Ballard. The tunnel will be designed to collect wastewater during heavy rains and prevent polluted runoff from flowing into the canal.

The slurry wall, in case you’re wondering, will be a thick, reinforced-concrete circular ring structure designed to support the 100-foot-deep and 90-foot-wide vertical shaft excavation. The vertical shaft will eventually bring stormwater and sewage flows into the new storage tunnel,

In the coming months, the Ballard vertical shaft will serve as the launch point for the tunnel boring machine. 

As SPU describes, the slurry wall ring is formed by constructing 18 separate vertical panels, consisting of nine large primary panels and nine smaller closing panels (the primary panels are white and the closing panels are blue in the diagram above). 

The slurry wall construction will take about three months to build, and nearby residents and businesses should expect the following:

• very 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.

Work along the project corridor is also increasing, with construction expected to start in East Ballard (11th Ave NW and NW 45th St near Fred Meyer) in late May or early June. SPU says the first stage of the construction will involve a detour on the Burke-Gilman, temporarily moving the trail to the north side of NW 45th St.

The Fremont project site will begin to see some activity this month as well, with crews closing NW 36th St between Leary Ave NW and 3rd Ave NW to set up their construction site.

Here’s a rundown of what to expect at the Fremont site:

• Tree removal
• Removal of an existing sidewalk on NW 36th St and existing utilities
• Installation of stormwater control and soil monitoring equipment
• Removal of existing asphalt
• Installation of a temporary storm drain bypass

For more information about the project timeline and other areas impacted by construction, visit the SPU project website.

Photo: SPU