With growing demand for power in the neighborhoods around South Lake Union, utility department Seattle City Light (SCL) is preparing to build a new electrical substation nearby. It won’t be like the city’s other 11 facilities with cold chain-link fences, as it will invite residents to play outside and peer inside from perimeter ramps and translucent walls. SCL decided to implement this project in an unusual way because of the concerns expressed at community outreach events; the local NBBJ architectural office, who is consulting on the design, is also only a block from the site.

Transmission line map. (Seattle City Light)

Two substations currently serve the area, one on Broad Street near Seattle Center and another just southwest of Safeco Field. Increasing density in the area from new residential and commercial buildings, along with future extensions of electrical-based transportation, has led to the need for a finer distribution network. The project is also significant because it will be the first new substation in 32 years. The city purchased three adjacent parcels, with Pontius Avenue between two of them, in 2009. One parcel, 1250 Denny Way, is a former Greyhound bus station and is undergoing cleanup; automotive fluids and leaks from underground diesel tanks were found as deep as 35 feet, requiring extensive earth removal. The operation experienced an accident just today, when a backhoe knocked a power pole onto occupied construction vehicles. No one was injured.

Because much of the site is already being excavated, early design concepts looked at occupying just the Greyhound parcel with equipment going several stories underground and up. However, it was found that option would be prohibitively expensive because of complex transmission line rerouting. A second alternative lowered the height by expanding across Pontius, but the third and preferred alternative is even more spread out in order to limit the facility’s height and impact on the neighborhood.

Part of the construction site, looking south.

At an AIA Seattle Urban Design Forum at NBBJ’s office, lead architects Jon Savo and John Hoffman explained the preferred design. The west side’s diagonal shape was derived from existing pedestrian flows from a #8 bus stop at Minor Avenue and Denny Way and across a parking lot. Neighbors were actually interested in seeing inside the substation, and so with similar ambitions as the Olympic Sculpture Park and plans for the downtown waterfront, each side has ramps that elevate visitors and allow them to peer in through openings or glass; the metallic wall material hasn’t been defined yet. There won’t be too much to see; recent technological advances allow the electrical equipment to be stored in metal boxes that are gas- rather than air-cooled. Blast walls direct an improbable explosion upwards, which negated the idea of a green roof, overhead photovoltaic (PV) array, or walkways over the interior.

NBBJ’s model.

Other arrangements of PVs, perhaps included in the exterior wall itself, wouldn’t be feasible because of planned 200′ buildings just south of the site. However SLC and NBBJ are interested in incorporating educational features in the project, which could include not just plaques and signs but also demonstrative PV arrays and rain gardens, in addition to a small dog park or recreational field. Part of the impetus for such public amenities is the code requirements for vacating Pontius, a public right-of-way.

Night render of southeast corner. (NBBJ)

Other considerations will be art and light that symbolize the facility’s energy. At some level the architects imagine the Denny Substation as a destination, though no parking or land uses like retail are on the table. Many Seattlites have opted to pay higher rates for electricity from renewable sources, so there is certainly interest in power infrastructure.

The project has received its share of criticism, including an apparent favoritism for the well-to-do area neighborhoods while other residents are left with older substations that have no aesthetic considerations. 30 years ago, citizens were not as concerned or consulted on public utility projects. Earlier in the design process SLC analyzed the feasibility of putting the substation under a high-rise to blend with the area’s future trends, but developer’s weren’t too interested.  A recent example of the idea is a substation under a tower at the redeveloped World Trade Center site in New York. Capitol Hill residents are also wary of a distribution alternative that would place tall transmission towers on residential streets, and the lack of public discourse beyond the affected areas.

The Denny Substation is expected to be energized by 2016 and initially cost $164 million, with ongoing improvements in the following years. The project will go before the Seattle Design Commission on November 7 for approval. A slideshow from a design open house earlier this month, with many more details, is available online here (23MB PDF).