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November 19, 2014

$174M substation designed to be a good neighbor in SLU

Images courtesy of NBBJ [enlarge]
Glass panels will emit a soft glow at night.

Sloping walls reduce the size of the building at street level.

Seattle City Light will hold an open house Thursday to get comments on the design of the Denny substation.

The event is from 5-7 p.m. at Cascade People's Center, at 309 Pontius Ave. N.

The $174 million electrical substation will be built on a 3.2-acre site near Denny Way and Stewart Street in South Lake Union.

The project also includes another $62.2 million for transmission lines and $60 million for a system to distribute power to South Lake Union.

The substation's proposed design shows a structure with sloped walls, metal cladding and glass panels that emit a soft glow at night.

Sloping the enclosure walls inward reduces the size of the building at street level, and leaves more room for pedestrians.

The design shows an “elevated interpretative pedestrian walkway” wrapping the Denny Way edge and continuing north along the alley on the east side of the building.

The substation's footprint would be 120,000 square feet. Public spaces could include a 2,900-square-foot learning center and a 3,800-square-foot community space run by the Seattle Office of Arts & Culture, but details about them still need to be worked out.

Utilities would be inside the substation, mostly hidden away from public view. Three 20- to 22-foot-tall transformers would be installed at grade in the interior yard, but wouldn’t be visible from the street. No overhead wires would come in or out of the substation.

(Editor’s note: The article has been corrected to say that there would be no utility towers at the substation.)

Power Engineers is the project manager and in charge of electrical design. NBBJ is the architect and KPFF is the structural and civil engineer.

Construction is slated to begin in early 2016 and the substation would be finished by the end of 2017.

The substation would distribute electrical power to South Lake Union and also transmit power to other City Light substations.

Work on the transmission lines could take until 2020.

Michael Clark, City Light's project manager for the Denny substation, said substations typically are open air and behind attractive security walls. But the Denny substation site is in a densely developed area so the design needs to be more hospitable to the neighborhood.

He said this project isn't being modeled after another, though substations in Vancouver, B.C., and New York City have also had utilities tucked inside a building.

The Denny substation site will also have a park, interpretive signs and a quarter-mile exercise loop.

“All these urban design elements are new for the electrical utility industry,” Clark said. “We're inviting people to connect with (the building).”

One challenge is how to make a piece of critical infrastructure inviting without attracting nuisance behavior.

“The typical design is to keep the public away,” Clark said.

Being a good neighbor, he said, means threading the needle between security and openness.