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Puget Sound Energy transmission line and substation projects

Pierce County 230 kV transmission line and Alderton substation expansion

Spring 2013 project updates
  • We have identified our preliminary preferred route for the transmission line. Click here to view a close-up version of the map.
  • We are conducting soil exploration to advance engineering and begin preliminary environmental analysis for the preferred route.
  • A public meeting to update the community on the project is expected to take place in summer 2013. We continue to keep the community advisory committee informed as the project progresses and respond to questions and concerns from individual property owners.
  • We expect to begin construction on the 230 kV transmission line and Alderton 230 kV substation expansion in 2015.
Project overview

Due to current and projected customer energy use in Pierce County, the existing regional electric grid is approaching capacity, making it difficult to move power throughout the county. To help solve this problem, Puget Sound Energy plans to construct approximately eight miles of new 230 kilovolt transmission line from the White River transmission substation, located at 2120 Lakeland Hills Way in Bonney Lake, to the Alderton switching station, located at 14450 Old Military Road in Puyallup. Adding the new 230 kV line will allow PSE to respond to the county’s current and future need for power while increasing overall reliability to our customers served by 17 local distribution substations in the central Pierce County area.


Download full-size map
Project road map

We also plan to upgrade our existing Alderton switching station, which is currently designed to accommodate 115 kV transmission lines, enabling it to accommodate the increased capacity of the new 230 kV line. The upgrade will require us to expand the station’s footprint within our existing property.

This project is related to our Central Pierce-Alderton 115 kV transmission reliability project , which involves the construction of three new 115 kV transmission lines in the Bonney Lake, Orting, and central Pierce County areas. These projects work together to strengthen the overall electric grid and increase electric reliability for our customers in Sumner, Bonney Lake, Orting and central Pierce County.

Contact us:

For more information about this project, e-mail info info@PSEPierce230kV.com or call our project manager, Janet Olsen, at 425-462-3912.

What is a transmission line?

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

What is a substation?

Substations are critical links in the electricity distribution system, containing utility circuit protection, voltage regulation, and equipment that steps down higher voltage to lower voltage. Before reaching homes and businesses, power is routed through our transmission system to a substation where it is changed to a lower voltage that can be utilized by customers.

What is a switching station?

A switching station is a transmission substation where the utility can switch or reroute power flow from one line or path to another to allow the power to be isolated to clear a fault (e.g., a fallen tree in the wires) or to take the power line out of service for maintenance. It also may act as a point of interconnection between two different transmission operators (e.g., Bonneville Power Administration and PSE). Unlike a substation with a transformer serving neighborhood circuitry, switching stations do not step power up or down; they integrate power from one or more transmission sources on the regional and local grid to serve neighborhood substations.

Committed to keeping you informed

PSE will continue to provide updates to the community. We will notify residents and businesses near the project area when construction will occur. We aim to complete the work with as little disruption as possible.

Download information

Download these PDF files for more detail on PSE's Pierce County 230 kV transmission line and Alderton substation expansion.

January 2013 Update to the Community

Community update newsletter, January 2013
Preferred route aerial map
Preferred route road map


January 14, 2013 State Street neighborhood meeting

Conceptual alignment aerial map
Route alternatives aerial map
State Street tree replacement plan
Third party sound survey
Meeting invite, January 2013


August 15, 2012 State Street neighborhood meeting

Follow-up notice, August 2012
Project fact sheet, updated August 2012
Conceptual alignment map
State Street alternatives
Meeting invite, August 2012


July 22, 2011 stakeholder meeting

Advisory group meeting summary, July 22, 2011


June 2011 community update
Report to the community, June 2011


May 5, 2011 public meeting

Public meeting invitation, April 2011
Fact sheet, March 2011
Why do we need to build the line?
White River transmission station load graph
Conceptual alignments aerial map
Conceptual alignments road map
Conceptual routes and PSE's critical constraints
Advisory group comments and concerns
Conceptual design: Along a roadway
Conceptual design: Cross-country corridor
Substation aerials
Project aerial map
Project road map


April 13, 2011 stakeholder meeting

Advisory group meeting presentation, April 13, 2011
Advisory group meeting summary, April 13, 2011


March 30, 2011 stakeholder meeting

Advisory group meeting presentation, March 30, 2011
Advisory group meeting summary, March 30, 2011