Denny Substation

Seattle, Washington

  • Services Civil Engineering, Structural Engineering
  • Market(s) Civic, Tunnels & Underground Stations


New duct banks


Miles of duct banks


Years since last substation constructed by Seattle City Light


Ft tall faceted enclosure structure clad in metal panels and glass
  • Owner Seattle City Light
  • Architect POWER Engineers
  • Team Seattle, WA
Denny Substation

KPFF provided civil and structural engineering for the new Seattle City Light substation, the first new SCL substation in 30 years. KPFF designed approximately four miles of new SCL distribution duct bank within the congested South Lake Union and Denny Triangle neighborhoods of Seattle.

Substation design included intricate yard and right-of-way utility design, complex structural support structure, layout, grading, design phasing, and permitting processes. Detailed coordination with SPU, SDOT, and Franchise Utility Providers, relative to reconstruction and maintenance of their utility and roadway infrastructure, was imperative as the project added 17 new duct banks in the directly adjacent streets, requiring reconstruction of public water and combined sewer mains, PSE gas mains, communication infrastructure, as well as existing SCL duct bank relocations.

Structural elements included 115kV inductor and 13.8kV switch gear vaults and structures, 115kV/13.8kV transformer pad foundations, a below-grade oil containment vault structure, shoring, and structural support for the perimeter facade.


Denny Substation

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