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Puget Sound Energy transmission line project

Cottage Brook-Stillwater-Novelty transmission line


Spring 2015 project updates

  • Phase 1 of the project was completed in 2014.
  • During Phase 2 of the project we will replace the transmission line from the Stillwater substation to a location west of of W Snoqualmie Valley Rd NE. We submitted applications for permits in late 2014 and construction is expected to take place as early as summer 2015.
  • Prior to Phase 3 of construction we will relocate a portion of existing overhead distribution line to underground along the SPU Tolt Pipeline Corridor near Mink Rd NE. Customers currently served by the Cottage-13 circuit experience many tree-related outages. By relocating the line to underground we expect to improve reliability. This work is expected to take place as early as summer 2015.
  • Phase 3 of construction (from the end of Phase 2 to the Cottage Brook substation) is anticipated to take place in 2016.

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Project overview

The existing electric system serving customers in parts of Duvall and unincorporated King County is almost 100 years old and approaching its capacity limit, putting the homes and businesses that rely on it at risk of outages. The lines were not built to meet the needs of a 21st century community, and can become overloaded during periods of high energy use, such as on very cold or very hot days. In addition to the limitations of the small capacity conductor, the current height and configuration of the poles increase the possibility of damage and outages due to trees and tree branches.

By rebuilding the existing power lines with higher-capacity wire, PSE will improve the dependability of the electric system that serves you and your neighbors and ensure that PSE is able to meet the future energy needs of the community. Specifically, Puget Sound Energy is planning to rebuild eight miles of existing power lines between the Cottage Brook substation in Woodinville, the Stillwater substation in Duvall and the Novelty Hill substation in Redmond. 

In addition, we'll also be transferring a particularly vulnerable part of the overhead distribution line (Cot-13 distribution circuit) near the Cottage Brook substation from overhead to underground along the Seattle Public Utilities Tolt Pipeline Corridor near Mink Rd NE. Placing this distribution line underground will lower the risk of outages. 

What is a transmission line?

Transmission lines are key elements in the electrical distribution system. These lines safely transport high voltage electricity from power generation sources like dams and wind generating facilities to substations in local communities. Transmission normally takes place at voltages of 55 kV and higher.