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Right Trees Make Eastside Electricity Transmission Corridor Safer

Seattle City Light worked with the City of Bellevue to successfully manage large trees gowing beneath transmission lines over a portion of Wilburton Park.


Photo of Seattle City Light crews planting trees.

Seattle City Light crews plant new trees and shrubs at Wilburton Park.

Big trees and parks go together like, well, trees and parks. Power lines and big trees? Not so much.

That was the challenge faced by Seattle City Light employees this fall, as they worked to manage tall trees under a major transmission line in Bellevue.

The area in question is the Eastside Line transmission right of way over a portion of Wilburton Park, the largest upland park in the middle of Bellevue. It is home to playfields, trails and a botanical garden. It is also a vital part of a historic neighborhood.

Most of the problem trees were in a sensitive wetland directly beneath the lines. About 300 of them were taller than 15 feet, the maximum height allowed under an agreement between City Light and Bellevue. Federal regulations also require all trees underneath the transmission lines be managed to prevent outages.

Photo of Wilburton Park before the tree removals and plantings.

This is what the area beneath the transmission lines at Wilburton Park looked like before the vegetation management work.

To deal with the delicate community and environmental issues, City Light’s Vegetation Management unit and the City of Bellevue worked out a plan to remove the danger trees, and replant and restore the area with low-growing native vegetation.

Bellevue allowed City Light to remove the trees in the wetland and to chemically treat the stumps to prevent re-sprouting. As a replacement, City Light agreed to plant 900 low-growing native shrubs and plants that will mature at a height less than 15 feet. All 300 trees were removed the first week of September.

An impressive 500 pounds of erosion control seed and 50 bales of straw were used. The new vegetation was planted on Nov. 6 and 7. All restoration planting was accomplished by members of Vegetation Management’s rights-of-way crews.

Photo of Wilburton Park after the tree removals.

Here’s what the area looked like after the big trees were removed.

Since 1991, City Light has mitigated and restored miles and acres of transmission line easements with more than 50,000 native plants and shrubs. The work has improved system reliability, reduced outages and restored wildlife habitat.

Photo of Seattle City Light crews planting trees and shrubs at Wilburton Park.

Seattle City Light crews plant trees and shrubs at Wilburton Park.

The Wilburton project was completed by rights of way crew members Steve Lewis, Kathy Smith, Bob Hayes, Chuck Campy, Tom Marion, and David Trantham; Plant Ecologist Marie Swanson; Senior Gardener Dale West; Vegetation Management Manager Brent Schmidt; and Asplundh Tree Service.