Mount Si, photo by Seattle City Light employee, Todd Andrews
Seattle City Light LARRY WEIS, General Manager and CEO
Denny Substation Project
Pay My Bill   

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 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 on-site excavation, hauling, and utility work, and have begun pouring the foundation for the substation and installing duct bank and vaults. Utility work will continue on Denny Way, John Street and Minor Avenue N, as well as at the substation site. Please be aware of increased truck traffic in the neighborhood.

Denny Way Nighttime Lane Closures and Detours

September 19 – October 13: Both eastbound lanes on Denny Way between Stewart Street and Minor Avenue N will be closed during the following times. Please follow the marked detour route in the project area.

  • Monday – Thursday: 9 p.m. – 6 a.m.
  • Friday – Saturday: 11 p.m. – 10 a.m.
  • Sunday: 11 p.m. – 6 a.m.

October 14 – November 21: Construction crews will be constructing utilities on Denny Way adjacent to the substation site. During this work, Denny Way between Stewart Street and Minor Avenue N will be reduced to one lane in each direction, 24 hours per day, 7 days a week, for 5 weeks. Access to I-5 South from Yale Avenue will be maintained but drivers should expect additional delays. Seattle City Light encourages drivers to avoid the Stewart Street exit from southbound I-5 during this time.
  • Friday, October 14, at 11 p.m. through Monday, October 17, at 5 a.m.: all lanes on Denny Way will be closed so crews can restripe the roadway.
  • Monday, October 17, at 5 a.m. for 4 weeks: Denny Way between Stewart St and Minor Ave N will be reduced to one lane in each direction 24 hours per day, 7 days a week.
  • Over the weekend of November 19 and 20: crews will close all lanes on Denny Way once again in order to restore the roadway to its normal configuration.
  • Monday, November 21: All lanes on Denny Way will reopen.

Denny Way westbound and eastbound lane closures between Minor Avenue N and Stewart Street. Follow marked detour route.

Note: This schedule is subject to change due to weather or other circumstances.

Denny Network Construction

Network construction consists of installing underground electrical duct bank and vaults. We have completed the bulk of the preconstruction activities (potholing to confirm utility locations, soil characterization, and installing vibration equipment) south of Denny Way and are now moving this work to the South Lake Union neighborhood. This work is done in preparation for duct bank and vault installations.

As of September 1, eight electrical vaults and 2,100 feet of duct bank have been installed. See the below map showing where these installations have occurred.

Completed vault and duct banks installation

Network Construction Traffic Restrictions

Drivers should expect congestion on Stewart Street between 8th and Westlake avenues and on Virginia Street between Boren and 7th avenues as the Network project continues. To stay informed about the schedule and 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

Bi-Monthly Online Construction Meetings

The project team remains committed to providing the public with regular and reliable information about construction. One way we do this is by hosting bi-monthly online construction updates. These live reports cover current and upcoming work, as well as information about construction processes. Listen to the most recent recording. Please note that you may be prompted to register, but only your first name is required (your email address is not required).

Updated: September 2016

Twitter Newsfeed
contact us

Get email updates:

If you have a comment or question regarding this project, please use the box below:




Subscribe me

If your email requires a response, you will receive follow-up within 48 hours.

Project Hotline:
(206) 257-2142

Email Address:

Utility Discounts
SAVE 60%
The Utility Discount Program is a great way to lower bills.


  • Contact Seattle City Light

    700 5th Avenue
    Suite 3200
    P.O. Box 34023
    Seattle, WA 98124-4023

    Account & General Questions:

    Contact Us