Yes, the “missing link” transmission line is a critical a critical piece of the puzzle to improve reliability on Bainbridge Island. Looking at past data and assuming the new transmission line had been in place, there could have been 60% less 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, 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 asked PSE to find solutions that improve reliability, meet this community’s growing energy needs, and align with the community’s values. It’s PSE's 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 Murden Cove and Winslow 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 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 115kV transmission line using wood poles. A new roadside 115kV transmission line could look similar, though other vertical configurations or pole types are possible and may be desirable.

We will develop and share representative photo simulations of our proposed project once we have progressed into the design and permitting phases.

Trees and vegetation are an important part of the rural character of Bainbridge Island and valued by the community, including PSE. PSE is currently engaging with the community to understand the values of the community and discuss route option trade-offs to inform a preferred route. Because project development is in the early stages and we don’t have a preferred route or know the exact vegetation impacts, we’re committed to working with landowners, the City and other stakeholders to minimize vegetation impacts and to fully mitigate for these impacts.

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

Yes, PSE can build transmission lines underground if the location is feasible. However, 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 these 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 transmission undergrounding fact sheet.

PSE also held a joint information session on electromagnetic fields and underground transmission lines on September 17, 2020. See our Info Session 2 presentation slides and Info Session 2 summary to learn more about electromagnetic fields and undergrounding.

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. We understand that local residents may still wish to learn more. In 2020, PSE hosted an information session on EMF and undergrounding you may find useful. The presentation and summary notes are available on our website.

For more details about EMF studies, exposure limits and PSE’s approach to EMF, visit pse.com/pages/electromagnetic-fields.

PSE will use feedback throughout the routing process to better understand community values and inform the preferred route selection – because routing a transmission line requires PSE to decision on tradeoffs between different elements. Safety and reliability will always remain PSE’s core priorities when routing a transmission line. The Community Sounding Board will review the preferred route developed by PSE at their next meeting and share their feedback. PSE will work to incorporate feedback where feasible and make a decision on the preferred route, to be announced later in 2021.

Building a new transmission line on an island poses unique challenges and there are no route segments that completely avoid community impacts. PSE is committed to engaging the community to better understand and address these challenges. Thank you for sharing your feedback!

The next opportunity to interact with the project is the sixth CSB meeting, tentatively planned for summer 2021. All CSB meetings are open to the public to observe, and there will be a brief opportunity for public comment at each meeting. CSB meetings are held virtually while social distancing recommendations are still in place. The meeting access link and agenda will be posted on this website one week prior to the event. Subscribe to our e-newsletter to receive important project updates about upcoming CSB meetings and community workshops.

You can also share your feedback anytime — email us at info@psebainbridge.com or leave a message at 1-888-878-8632.