Portland's Complex Distribution and Substation Project

To ensure both downtown Portland, Oregon, and the city’s South Waterfront District have an adequate supply of reliable power, Portland General Electric knew it needed a new substation. In 2007, PGE began planning to replace an 80-year-old substation and nearly 1.5 miles of aging 15-kV submarine distribution cables.

But PGE faced a challenge. New 115-kV XLPE cables would carry power from PGE’s Harrison substation, east of the Willamette River, and over the new Tilikum Crossing Bridge to the new Marquam substation, close to downtown on the river’s west side. However, to bring power from the bridge to the substation, project engineers at Black & Veatch first had to run the XLPE cables 1050 ft under 12 lanes of the busy Interstate 5 freeway, while dodging underground obstacles and negotiating varying soil types.

The Marquam substation also presented PGE and Black & Veatch with its own set of unique challenges. The designated location is a small urban lot, sandwiched between I-405 and I-5 and surrounded by numerous parkways, local roads and residential buildings.

From the outset, PGE confronted several critical issues:

  • What cable system would best meet the project goals?
  • How would the cables come across the Willamette River?
  • How would the team overcome construction challenges on a small and complex site?
  • How would the substation tie to the distribution system?

Following are images of the $83-million Marquam project, featured in-depth in the April 2018 issue of T&D World. For the full article, see "Engineering Complexity in Substation Design."

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