Denny Way Seattle Substation

– Construction on the Denny Substation was completed in 2018. The uniquely designed substation, named after its host street, Denny Way, in Seattle has unique amenities that provide a vantage point for viewing the city, education and art spaces, and accessible areas for pedestrians and their pooches.

– 33 trees at Denny Way and Minor Avenue have grown substantially since planting in 2018, adding canopy, shade, and comfort to the walking paths around the electric substation that services Seattle’s Cascade and South Lake Union neighborhoods.

The trees were planted with 624 2X Silva Cells, which support their long-term health, contributing to the green spaces around the substation that are open to the community.

Growth in housing and business development in Seattle over the past decade have resulted in space being at a premium and estimates for energy demand at an all-time high. When planning began on a new electricity substation, the decision was made to make it more than just a low-budget perfunctory facility. In addition to the electricity it provides to the South Lake Union and Cascade neighborhoods, the thoughtfully designed 4-acre Denny Substation hosts an off-leash dog park, a beautifully landscaped open space, an exhibit hall, a small theater, and an educational corner. Written about in Wired, Fast Company, and Slate, the substation, operated by Seattle City Light and designed by architects NBBJ, fulfills two vital public infrastructure needs: supplying energy and providing enticing accessible outdoor space for the community. An elevated walkway, unique building facade, and public artworks such as the Transforest sculpture conspire to serve the community in unusual ways and create something not often associated with a substation: an aesthetically pleasing city landmark.

The station is shaped like a trapezoid and allows for views of the interior from a pedestrian ramp.

The sloping translucent glass and stainless-steel panels of the substation are complemented by 33 street trees. These trees on Denny Way and Minor Avenue were planted in 624 2X Silva Cells, giving each tree 464 ft3 of soil volume. Landscape architects Hough Beck & Baird (HBB) wanted to ensure the trees along the paths and walking trails surrounding the station would flourish.

HBB has worked on several civic and public projects in Washington with DeepRoot since as early as 2013. This includes the Sound Transit, East Link in Bellevue and the Multi-way downtown Bothell project.

Silva Cells protect tree roots from the weight of concrete sidewalks and the heavy volume of cars and buses, while maintaining proper soil volume compaction for urban trees. Silva Cells were the bioretention choice for HBB.

The substation officially opened to the public in July 2019. Few could have foreseen the desire and need for open space during the ensuing COVID-19 pandemic lockdown. What fortuitous timing it was to have this open for all members of the community, two- and four-legged.

In addition to space is the benefit to the climate that trees offer during unprecedented heatwaves. The summer of 2021 was dire for the Pacific Northwest and Canada. The 2- to 20-degree drop in temperature trees can provide was vital during these months and will be in the future. The American lindens (tilia Americanas) surrounding the substation, flourishing thanks to Silva Cells, will help create a cooler microclimate during any future heatwaves.

American Linden beginning to carve a canopy above ground thanks to their substantial growth after just two years.

American Linden providing shade along Denny Way outside of the Denny Substation. Below ground are 2X Silva Cells creating more root growing space, fueling tree growth.

Summer of 2021, 3″ ABH

Soon to come is a bus stop just near some of the trees planted in Silva Cells.

Installation Summary:

Number of Silva Cells: 624 2X
Amount of soil volume per tree: 464ft3 per tree
Number of trees and type: 33 The American lindens (tilia Americanas)
Project architect: NBBJ
Project designer: Hough Beck & Baird Inc. (HBB)
Project contractor: Walsh Construction Company
Project sub-contractor: SS Landscaping Services Inc.
Installation date of Silva Cells: Fall 2018
Project time line: 2016–2018


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