Pyramid Peak at Skagit Hydroelectric Project, Photo by Jim Hunter
Seattle City Light JIM BAGGS, Interim General Manager and CEO
Denny Substation Project
Pay My Bill   

Construction [Denny Network]

Construction Update

City Light's contractor, Shimmick Construction Company, Inc., began construction of the network on February 29, 2016. The network map (below) displays a preliminary construction schedule and the general sequence of work, which will be completed in stages. Each stage will begin with the installation of vaults, followed by the installation of a duct bank system that will connect the vaults. Street restoration will conclude each stage. Follow along on the interactive construction map.

Stage 1

Shimmick has completed the installation of four large vaults in this stage—one on Minor Avenue and three on Stewart Street between Minor and 7th avenues—and underground duct banks between Minor and 6th avenues. Final roadway restoration between Boren and 9th avenues is complete. In order to minimize commute impacts and stay coordinated with the Denny Substation Project, restoration of the remainder of Stewart Street will resume in the second quarter of 2017.

Stage 2

On Virginia Street, three vaults have been completed, and underground duct banks have been installed between Minor and 8th avenues. Construction in this stage is expected to be complete by the end of the first quarter of 2017, with final street restoration scheduled for the third quarter of 2017.

Stages 3

Potholing, soil characterization, and other preconstruction activities are substantially complete in this area. Vault and duct bank installation began in the third quarter of 2016 and will continue through 2017.

Stages 4

This stage started in summer of 2016 with potholing and vault installation on Harrison Street. Construction in this area will resume in the fourth quarter of 2016. Vault and duct bank installation, followed by street restoration, will continue through late 2017.

Stages 5

This stage started in summer 2016 with potholing and other preconstruction activities throughout the area. In the third quarter of 2016, construction began on Minor Avenue North between John and Harrison streets. Vault and duct bank installation, followed by street restoration, will continue throughout the Cascade Neighborhood through mid-2018.

Stages 6

This stage started with installation of duct bank on Republican Street between Boren and Fairview avenues. In early 2017, potholing, followed by vault and duct bank installation, will resume. This work is expected to be complete in mid-2018.

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

Distribution Network

The Denny Network is being built underground in South Lake Union and the Denny Triangle. Construction will occur b¬¬lock by block and mostly in the public right-of-way. Typical impacts include daytime and nighttime work, parking restrictions, transit and pedestrian detours, dust, and noise. There will be lane restrictions and street detours, but streets will typically remain open to traffic during construction.

Below are examples of what typical construction activity will look like in the project area.

demolition example photo

Potholing to confirm utility locations

excavation example photo


installation example photo

Shoring (trench reinforcement)

restoration example photo

Duct Bank Installation

demolition example photo

Vault Installation

excavation example photo

Back Filling Vault

installation example photo

Temporary Street Restoration

installation example photo

Final street restoration

Network construction will take approximately 24 months to complete and will consist of the following steps:
  • Locating underground utilities
  • Excavating and removing concrete and asphalt
  • Installing duct banks and electrical vaults
  • Backfilling excavation
  • Installing permanent concrete and asphalt pavement
  • Repairing and installing sidewalks, curb ramps and curb bulbs
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