Project updates

  • PSE is focusing on engineering design and fieldwork for the project.
  • Fieldwork is ongoing to inform the project’s engineering and design.

Project overview

Electric reliability on Bainbridge Island needs to be improved – two-thirds of the island is served by two substations that don’t have backup transmission. The Winslow and Murden Cove substations are each served by single radial transmission lines, referred to as "taps". If the transmission line serving the substation goes out, then the substation and all customers served by that substation lose power.

As part of PSE's solution to improve reliability on the island, we’re planning to build the new Murden Cove – Winslow "missing link" 115 kV transmission line between the Winslow and Murden Cove substations to create a transmission loop. This means each substation will be connected to two transmission lines. If one line goes out, the other line can still feed the substation and provide power to customers.

This new transmission line is a critical component of PSE’s plan to improve electric service reliability, reducing the frequency and duration of power outages for customers on Bainbridge Island. More homes and businesses depend on PSE for reliable power than ever before and PSE’s investment in transmission infrastructure will make Bainbridge Island's electric grid more resilient and reduce the impact of any single outage by focusing on redundancy.

The Murden Cove-Winslow “Missing Link” 115 kV transmission line is just one piece of PSE’s solutions package for Bainbridge Island and, while each project has independent functions and benefits, we are working to accomplish all of the components cohesively. For instance, other Bainbridge Island projects require substation upgrade work, as does the WIN-MUR transmission line. To maintain reliable power for the island, substation upgrades can only be done at certain times of the year, and we must follow a particular order of operations to accommodate all project work. This can be seen in the "substation upgrade" section.

Murden Cove - Winslow 115 kV line (missing link) project timeline and milestones

Updated: April 2022
Note: This timeline depicts PSE’s preferred timing of project phases and is dependent on outside agency’s decisions. Some project phases may take longer than expected and are dependent on other projects completion.

Where are we now?

PSE launched the Murden Cove – Winslow “Missing Link” 115 kV Transmission Line Project in late 2019 while engaging the community on the hybrid solutions package to improve Bainbridge Island’s electric system. Following the formation of a Community Sounding Board and multiple public engagement events and comment periods, a transmission line route was selected and announced to the community in fall 2021.

Currently, PSE is continuing on-going fieldwork and engineering, real estate planning, and permitting for the project. We will inform adjacent property owners of upcoming work directly as we progress. We expect the new transmission line to be in service in 2026. The project timeline is subject to change and will be kept up to date as the project continues.

The selected route

After over two years of public engagement, PSE selected route option – "Route A" – as the best route option based on siting criteria and balancing the values the community shared to connect Murden Cove and Winslow substations. The selected route option finds balance with a variety of sitting considerations including the feasibility to construct, future maintenance needs, and community values.

Map of PSE’s selected route for the Murden Cove – Winslow 115 kV Transmission Line.

Safety is always the foundation of everything PSE does. In comparison to other route options, Route A:

  • Is the shortest route (3.4 miles)
  • Affects the fewest parcels, including residential parcels
  • Follows public road rights-of-way for the entire length, limiting both environmental and community impacts
  • Contains land uses and zoning that represent less population density
  • Has a comparatively lower area of tree canopy
  • Has existing overhead distribution lines along its entire length, which allows for more opportunities to colocate the transmission line with existing distribution

The selected route provides the best opportunity to minimize impacts on the following community values:

  • Trees, wetlands, and habitats
  • Private property and residential neighborhoods
  • Schools

PSE weighed the community’s feedback alongside a variety of considerations, including a thorough review of existing restrictions and regulations, wetland delineations, coordination with the City of Bainbridge Island, and technical reviews by engineers, vegetation management, and other technical staff.

This simulation is taken from Sportsman Club Road near the entrance of Woodward Middle Schools looking south toward New Brooklyn Road. North Town Woods is located to the left of the image. The new transmission will follow the existing distribution line alignment.

Existing 115kV lines on Bainbridge Island; not representations of future lines
Representation of future 115kV lines on Bainbridge Island

PSE listened to community input on the importance of the trees located across the street from the Sportsman’s Club. Our technical review determined that it was possible to avoid these trees by locating the transmission line in front of the Sportsman’s Club. In this scenario, PSE would relocate the existing distribution line with the transmission line on the west side of Sportsman Club Road. This siting allows for the select removal of less significant trees.

Existing 115kV lines on Bainbridge Island; not representations of future lines
Representation of future 115kV lines on Bainbridge Island

This simulation is taken at a mapped Category II wetland location at High School Road and Fletcher Bay Road. The anticipated vegetation removals would include the trees shown in the foreground.

Existing 115kV lines on Bainbridge Island; not representations of future lines
Representation of future 115kV lines on Bainbridge Island

This simulation is taken from Fletcher Bay Road, just north of the Winslow Substation looking to the north. Fletcher Bay Road is where most of the tree removals for this project are anticipated. PSE also anticipates the need to trim trees that extend over the roadway opposite the transmission line.

Existing 115kV lines on Bainbridge Island; not representations of future lines
Representation of future 115kV lines on Bainbridge Island

Community engagement

PSE committed to engaging with the community on our work to improve the electric system on the island. After more than two years of technical analysis and community engagement, PSE selected a route for the Murden Cove – Winslow "missing link" 115 kV transmission line. This was an important step towards improving reliability for two-thirds of the island currently at risk of outage due to lack of transmission system redundancy.

PSE worked diligently to understand from a technical and impact perspective which route option best meets the route criteria and project need. Feedback from the Community Sounding Board (CSB) and the community - which we had been gathering since the project launch in 2019 - was considered in the route selection.

  • We heard a wide range of input from hundreds of island residents on their values related to route siting. The feedback was varied, and it helped PSE better understand community values and perspectives to inform route selection.
  • We appreciate the hundreds of islanders and the dedicated CSB members who took the time and made the effort to join us in the sitting conversation and share their feedback to inform our selection of the preferred route option.

PSE held an online Community Announcement on November 30, 2021 to share the selected route option with the Bainbridge Island Community.

Diagram showing the engagement process for the Murden Cove – Winslow Transmission Line Project. The linked PDF further details the engagement process
High-level overview of PSE’s transmission line routing community engagement process.

Prior to selecting a route option for the Missing Link, the Bainbridge Island City Council shared a letter with community values and interests that PSE should keep in mind when selecting a preferred route. The City Council delivered their letter of recommendations via email to PSE on October 8. The letter from City Council is available below.

On November 1, PSE responded to the City Council’s letter. PSE’s response letter and its appendices are available below.

In response to community interest shared during feedback periods for the Murden Cove - Winslow “missing link” 115 kV transmission line project, PSE held two information sessions. One focused on underground transmission lines and the other on electromagnetic fields (EMF).

The first information session on underground transmission lines was held on August 16, 2021. Information provided at the session included the benefits, challenges, and processes involved with underground transmission lines. Attendees were able to submit questions to a panel that included an independent underground transmission line expert and representatives from PSE.

The second information session on EMF was held on September 29, 2021. Information provided at the session include a discussion of what EMF is, where frequencies are found, and how it relates to health. Attendees were able to submit questions to a panel that includes an independent, board-certified health physicist and representatives from PSE.

PSE hosted two workshops where Bainbridge Island community members could provide feedback to inform the routing process. The first workshop was held virtually on Jan. 21, 2021. PSE introduced the route segments and invited initial community feedback on these segments. Following the first workshop, PSE held a feedback period between January 22 and February 12 to continue collecting community input on route segments. During this time, PSE heard feedback from a variety of community members. Feedback was collected through responses to an online interactive Segment Explorer tool, emails, voice messages, online comment forms, and mailed letters. A summary of themes PSE heard during the first feedback period is available in our community workshop materials below.

The second workshop— held virtually on May 3— introduced the route options and provided an opportunity for public feedback on the potential routes. Between May 4 and June 2, PSE continued collecting feedback on route options through an online interactive Route Explorer tool, email, voice message, and online comment form.

PSE convened the CSB to help inform the routing process for the new Murden Cove - Winslow “missing link” 115 kV transmission line between the Murden Cove and Winslow substations. The 18-member CSB individually provided input and feedback on routing criteria, route segments, route options and other project related topics identified by PSE during the transmission line routing process. Members were selected from a pool of applicants and represented a variety of geographic, organizational, and individual interests on Bainbridge Island from inside and outside the project study area.

Materials

Yes, the Murden Cove - Winslow “missing link” 115 kV transmission line is critical to improving reliability on Bainbridge Island. Looking at past data and assuming the new transmission line had been in place, PSE estimates that Bainbridge could have experienced 60% fewer substation outages between 2018 and 2020. Between 2013 and 2020, our experts estimate the “missing link” transmission line could have reduced customer minutes of interruption for Bainbridge Island by nearly 40% per year on average.

The new transmission line will connect Murden Cove and Winslow substations which currently are each served by single radial transmission lines, referred to as "taps". If the transmission line serving the substation goes out, then the substation and all customers served by that substation lose power. Connecting the substations with the “missing link” would create a transmission loop. If one line goes out, the other can still feed the substation and provide power to customers. Combined with the other components of the Bainbridge Island reliability solutions package, it will improve reliability of the electric service on the island.

 

Bainbridge Island customers experience more frequent and longer outages than the average PSE customer, and nearly half of those outage minutes are due to issues with the transmission system and lack of redundancy. Challenges to reliability include:

  • Trees: The combination of high winds, winter storms and tall trees mean trees are the #1 cause of outages on the island. Bainbridge transmission lines are heavily exposed to trees, and 64%of outages are caused by trees.
  • Radial transmission lines: Nearly two-thirds of Bainbridge customers are at risk of a prolonged outage. This is because their area is served by a substation – either Winslow or Murden Cove substation – that’s fed by a single transmission line with no back-up. 
  • Customers served by the Winslow substation have the worst reliability on the island, followed by customers served by the Murden Cove substation.
  • Nearly 70 percent of transmission customer minutes of service interruptions were from the Winslow Tap transmission line that feeds the Winslow substation.
  • Geography: The geography of an island also poses unique challenges for electric reliability, mainly the lack of neighboring infrastructure to serve as backup.

Electric reliability on Bainbridge Island needs to be improved. PSE’s customers have been vocal in asking us to find solutions that improve reliability, meet this community’s growing energy needs and align with the community’s values. It’s our goal to understand community values and interests around the new transmission line, so we’re engaging the community to gather input and feedback. To help reach that goal we’re asking for the community’s feedback on the route segments under consideration.

PSE is investing in transmission infrastructure that will make Bainbridge Island's electric grid more resilient and reduce the impact of any single transmission outage by focusing on redundancy. We'll build the "missing link" transmission line between the Winslow and Murden Cove substations to create a transmission "loop." This means each substation will be connected to two transmission lines so that if one line goes out, the other line can still feed the substation and provide power to customers. This will significantly reduce the frequency and duration of power outages for Bainbridge Island customers. 

The team currently anticipates that the line will be primarily composed of round wood transmission poles that are typically 60 to 75 feet above ground. These poles will be similar to other 115kv lines already on the island.

The photo on the right below shows an existing transmission pole that includes a distribution line on the same pole. Transmission lines bring power to the substations from the generation source and distribution lines distribute the power from the substations to homes and businesses.

These are examples of construction for a typical vertical configuration 115 kV transmission line using wood poles. A new roadside 115 kV transmission line could look similar but could be subject to change.

Existing 115kV lines on Bainbridge Island; not representations of future lines
Existing 115kV lines on Bainbridge Island; not representations of future lines

PSE plans to collocate the transmission line over existing aerial distribution lines because the vegetation around the distribution lines is already being maintained unless there are specific locations where this is not feasible or there are better design alternatives to help limit impacts to vegetation. Visual surveys also helped us to identify Route A as having a lower density of tree canopy than other routes. Additional work will be undertaken during design to first avoid and then to minimize potential impacts.

PSE’s goal is to remove as few trees as possible while building and maintaining a safe and reliable transmission line to serve the community.

PSE is a willing steward in the community and we understand trees are a vital component of Bainbridge Island’s character. In addition to trying to avoid and limit vegetation removal to the extent practicable, PSE is committed to replacing and mitigating for the trees we remove for this project. While we don’t know the exact vegetation impacts at this stage, we are committed to working with landowners, the City and others to replace trees removed for the new Murden Cove – Winslow “missing link” 115 kV transmission line.

For this transmission line, PSE will collocate transmission lines over existing distribution lines unless there are specific locations where this is not feasible or there are better design alternatives. Detailed engineering design will determine if there are places where we cannot collocate with existing distribution. To determine more detailed route siting such as side of the road, PSE will analyze collocation opportunities, vegetation management needs, and pole engineering among other considerations.

Wetlands could not be avoided with any of the route options. However, because the preferred route runs along existing roadway with existing distribution lines, we are able to avoid and minimize wetland impacts.

The primary impact in wetlands is expected to be removal of vegetation along the roadside edge. We anticipate collocating the new transmission line with our existing distribution system along the majority of the route, which should lessen impacts to the environment, including wetlands.

PSE looked at environmental and economic inequalities – such as impacts to air or water quality, access to green space, or increased in costs of housing or transportation – using environmental justice and equity databases maintained by the U.S. Environmental Protection Agency (EPA) and Washington Department of Health (DOH). We used these sources to review whether transmission line construction and operation would contribute to environmental and economic inequities.

In looking at the Bainbridge data in these databases, as well as the types of impacts contributing to environmental justice inequities, we determined that new transmission lines, like the Murden Cove – Winslow “missing link” 115 kV transmission line, do not contribute adversely to conditions contributing to environmental inequities as analyzed in environmental justice and equity databases.

We have also reviewed and considered questions relating to equity on Bainbridge Island generated in the “missing link” outreach process. We know that inclusion and education are key components of equity and environmental justice efforts. To that end:

  • The project team is reviewing third party equity impact assessment guides as a way to expand understanding and identify potential community engagement gaps.
  • The project team is coordinating additional community meetings in an effort to continue to ensure that all voices are heard in the siting process.
  • The community engagement team will continue their efforts to inform and educate individual customers and community organizations on the island and ask their assistance in sharing information with the people they serve.

PSE is on a journey to be a more inclusive organization, and that includes gaining the perspectives of historically underserved customers and communities to inform our decisions and investments. PSE has been, and continues to be, committed to hearing feedback from the community to inform our route siting process.

On an engineering basis, PSE can build transmission lines underground, but there are a variety of constraints (e.g., location of other utilities underground) may limit whether undergrounding is practicable or feasible. Additionally— and as importantly— it is up to the community to decide whether to invest in it. State regulations require PSE to first consider building overhead transmission lines because of their combination of reliability and affordability, both of which are important to our customers.

When a new line is constructed overhead, project costs are distributed evenly between PSE’s 1.1 million customers. Undergrounding is an option, but under state regulations underground transmission lines are considered a “local option” and the local community must pay the cost difference between overhead and underground lines. Most communities decide not to invest in undergrounding transmission lines because they have other investment priorities.

For more information, see our undergrounding transmission lines fact sheet.

PSE has also held two information sessions on underground transmission lines, one on September 17, 2020 with the Community Sounding Board, and another on August 16, 2021. The presentation slides and meeting notes are available below.

Electric and magnetic fields, or EMF, are found wherever there is electricity – in household wiring, electrical appliances, computers or power lines.

At PSE, safety is always our top priority. We rely on the findings of reputable, national and international scientific and public health organizations and agencies that have reviewed the research on EMF. Over the past 45 years, there have been many scientific studies conducted to determine if EMF has any effect on human health. To date, extensive reviews and research conducted by leading public health agencies – such as the World Health Organization (WHO) and the U.S. National Cancer Institute (NCI) (one of the U.S. National Institutes of Health) – have not established that power frequency EMF cause any adverse effects in humans or animals.

We are committed to keeping our customers informed. PSE has also held two information sessions on EMF, one on September 17, 2020 with the Community Sounding Board, and another on September 29, 2021. The presentation slides and meeting notes are available below.

We understand that local residents may still wish to learn more. For more details about EMF studies, exposure limits and PSE’s approach to EMF, visit pse.com/pages/electromagnetic-fields.

There will be additional opportunities for community members to provide feedback on the project to the City when permit applications are submitted and reviewed. We will keep those along the route and the broader community informed as the project progresses.  

You can always contact the team by calling us at 1-888-878-8632, emailing us at info@psebainbridge.com, by using the comment form on this website. Follow our e-newsletter for periodic updates on the work PSE is doing on the island.