CITY OF RICHLAND NOTICE OF SEPA DETERMINATION Date Notice Issued: March 24, 2026, per WAC 197-11-340(2) File #: PLN-T1-2026-00423 Proponent: City of Richland Energy Services Department, 2700 Duportail Street, Richland, WA 99354 Proposal: Expansion of an existing substation. The proposed expansion is in conjunction with the Bonneville Power Administration (BPA) Tri-Cities Reinforcement Project. The Thayer Substation is a 115kV – 12.47 kV substation housing three power transformers, three metalclad switchgears, equipment foundations, control house, and new ties to the 115 kV transmission line and will be enclosed by an eight (8) foot tall non-conductive fence for safety and security. The expansion will replace one transformer/metalclad bank. Location of Proposal(s): The project is located at 806 Thayer Dr, Richland WA. Portion of the NE 1/4 of the SE 1/4 of S10, T09N, R28E, WM, Parcel # 110981020600003 Determination: The City has reviewed the project for environmental impacts and has issued a determination of non-significance using the process outlined in WAC 197-11-340(2). This may be the only opportunity to comment on the environmental impacts of the proposal. Public Comments Due: April 08, 2026 Contact: Mike Stevens, Planning Manager 625 Swift Boulevard, MS-35 Richland, WA 99352 mstevens@richlandwa.gov Date Published: Sunday, March 29, 2026 IPL0326320 Mar 29 2026