Can transmission lines be undergrounded?

Yes, PSE can build transmission lines underground. 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