Skagit River Hydroelectric Project at Diablo Lake. Photo by Roman Khomlyak,
Seattle City Light LARRY WEIS, General Manager and CEO
Denny Substation Project
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Denny Substation Project Update

Project Status

Seattle City Light is constructing a new electrical substation (Denny Substation) and an underground distribution network (Denny Network) to accomplish a major electrical system upgrade for the city of Seattle.

Construction of the substation began in May 2016 and is expected to be complete in mid-2018. Construction of the network, which is being installed underground in the South Lake Union and Denny Triangle neighborhoods, began in late February 2016. This work is anticipated to be complete in mid-2018. Learn more about the sequence of work, the construction schedule, and what to expect on our interactive construction map.

Denny Substation Construction

Crews have completed excavation work on the electrical vault on John Street and have begun relocating water and sewer lines between Minor Avenue N and Yale Avenue N. This work required a switch from the current westbound closure on John Street to an eastbound closure. Crews have also begun water and sewer line work on Minor Avenue N between Denny Way and John Street. Work hours are 7 a.m. to 7 p.m., Monday through Friday.

Crews continue to drill shafts and pour concrete for foundation piles inside of the substation site. Site excavation will ramp up in July. Please be aware of increased truck traffic in the neighborhood. Typical work hours are 7 a.m. to 5:30 p.m. with occasional work on Saturdays between 9 a.m. and 5 p.m. Note: This schedule is subject to change due to weather or other circumstances.

Denny Network Construction

In July, construction will continue in the Denny Triangle neighborhood on Stewart Street between Minor and 6th Avenue and on Virginia Street between Minor and 7th streets. Work includes installation of underground vaults and duct banks. Crews will also continue potholing to confirm utility locations, retrieving soil samples for analysis, and setting up settlement monitoring stations on local utilities.

Crews will also be working in the South Lake Union neighborhood on Harrison Street between Boren and Fairview avenues to install an underground vault, and between Westlake and Terry avenues to perform potholing work. This work is scheduled for night times the week of July 5 and between 9 a.m. and 3 p.m. the weeks of July 11 and July 18.

Network Construction Traffic Restrictions

From now through September 2016, drivers should expect congestion on Stewart Street between Yale and Westlake avenues and on Virginia Street between Minor and 7th avenues as the project continues with the installation of vaults and duct banks. To stay informed about traffic conditions, subscribe to SDOT's email alerts by following this link:

What to Expect During Construction

  • Lane restrictions and some traffic and pedestrian detours
  • Typical weekday work hours will be from 6 a.m. to 7 p.m.
  • Some weekend, night and early morning work
  • Nighttime work between the hours of 7 p.m. and 6 a.m.
  • Parking and loading restrictions near work zones
  • Typical construction impacts such as dust, noise and truck activity

Monthly Online Construction Meetings

The project team remains committed to providing the public with regular and reliable information about construction. Together with the contractor, the team is hosting monthly online construction updates. The previous updates covered details on current and upcoming work, lessons on vault and duct bank installation, and how the crews are staying safe on the job. Listen to the recording! Please note that you may be prompted to register, but only your first name is required (your email address is not required).

Updated: July 2016

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    700 5th Avenue
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    P.O. Box 34023
    Seattle, WA 98124-4023

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