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Wallula Gap

Assigned Site Specialist
John Barnes

Assigned CFE
Yuriy Korol

Appliant: OneEnergy Development LLC
Facility: 60-megawatt (MW) solar photovoltaic (PV) project with an optional battery energy storage system (BESS)

Project Milestones

Project Background

On February 23, 2024, EFSEC received from Wallula Gap Solar, LLC an application to construct and operate Wallula Gap Solar, a 60-megawatt (MW) solar photovoltaic (PV) project with an optional battery energy storage system (BESS) located in Benton County, Washington.

The Facility is proposed to be located approximately 4 miles northwest of the unincorporated community of Plymouth on parcels located north of SR-14, approximately 5 miles west of its intersection with Interstate 82. The Facility would be located across a portion (approximately 437 acres) of three parcels. The parcels are owned by Farmland Reserve, Inc. (Landowner), and are known herein as the “Facility Parcels” (approximately 1,220 acres).

The Facility would consist of PV modules mounted on single-axis trackers supported on stationary piles. Each row of solar panels would be strung together in a north-south orientation and the panels would tilt on a single axis (facing east in the morning and tilting toward the west, following the sun, through the course of each day to maximize energy output).

The optional BESS would not exceed the nominal 60-MW capacity of the Facility. As currently designed, the optional BESS would be connected to the DC side of the transformer. The battery would store power generated by the Facility and dispatch it to the electrical grid at a later time. The Facility is currently proposed to utilize lithium-ion battery energy technology. However, pending commercial interest, the Facility could be designed to utilize other battery technology.

The Facility would interconnect through a line tap to Benton Public Utility District’s (PUD) 115-kV line near the Prior #2 substation. The generation would then be connected to the Bonneville Power Administration’s (BPA) facilities at the Plymouth tap (aka Paterson Tap), where Benton PUD and BPA facilities connect at BPA’s McNary substation.

The Applicant intends for the Facility to have a Commercial Operations Date (COD) as early as Q4 2026. To meet this schedule, it is expected that construction would begin in Q4 2025

Wallula Gap Informational Meeting and Land Use Hearing

The Informational Meeting and Land Use Hearing took place on April 23rd, 2024. You can view the recordings here: 
Informational Meeting
Land Use Hearing

Counsel for the Environment


Document Titlesort descending Document Date
CFE Appoints Yuriy Korol 03/13/2024

Project Comments

Tribal Comments

Document Titlesort descending Document Date
Lummi Nation Comment 04/23/2024
Spokane Tribe Deferral 03/13/2024

Public Comments

Document Titlesort descending Document Date
001 04/12/2024
002 04/12/2024
003 05/08/2024

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