UEC Breaks Ground on 31st Substation

March 27, 2017

Umatilla Electric began construction of their 31st substation in late February.

The Hermiston East substation, located at the intersection of Northeast 10th Street and East Elm Ave. in Hermiston, will serve both UEC and Hermiston Energy (HES) customers.

The project is expected to be completed in July of this year and will help to take the burden off Umatilla Electric’s other three substations in the area by reducing the number of members affected by an outage and shortening restoration times.

The 4.75 million dollar project is being completed by Potelco, Inc. out of Sumner, Washington and is designed with room to add a second transformer as Hermiston continues to see growth.

Project Overview

  • Estimated Project Cost: $4,750,000
  • Primary Construction Contractor: Potelco Inc. of Sumner, Wash.
  • Construction Schedule: Began Feb. 27, 2017; Completion scheduled July 2017


The substation is designed for two transformers. The first transformer will be installed during initial construction. The second will be installed in the future to accommodate increased demand.

UEC will use three and HES three of the substation’s six feeders, which are electrical circuits that serve customers at distribution voltage.


As Hermiston and surrounding areas have experienced ongoing population and electrical growth, the area’s three electrical substations (Hermiston Butte Substation, Feedville Substation and Columbia Substation) need added capacity to continue providing adequate service to both existing and future loads.

Adding the Hermiston East substation to the system will help reduce the number of customers affected by an outage and allow for quicker restoration times. This substation will have capacity to be served with power supplied from two separate points of delivery from the Bonneville Power Administration, offering both UEC and HES greater flexibility and service availability.

Transmission Interconnection

The transmission line connecting to this substation is already located East Elm Avenue. Two new transmission poles will have to be added within the existing transmission easement to support this connection into the substation.