Energy McNary UEC Substation

Project Highlights

• Completed the construction of four new substation bays to support system expansion and increased capacity.
• A 230/115 kV 300 MVA transformer and multiple high-voltage breakers were installed, and existing transmission infrastructure was rerouted.
• Detailed outage coordination was essential due to overlapping utility systems and high local energy demands.

Project Description

The McNary UEC Substation project, led by MacKay Sposito for the Bonneville Power Administration in Umatilla, Oregon, focused on the significant expansion and modification of existing infrastructure. The scope included constructing four new substation bays, installing a 230/115kV 300 MVA transformer, seven high-voltage power circuit breakers, and extensive indoor and outdoor substation control equipment. An engineered retaining wall and a new access road were also built to support the yard expansion.

Transmission lines were rerouted using tubular steel and direct embed poles to facilitate system modifications. Given the critical nature of nearby data centers and large-scale irrigation systems, meticulous outage planning and real-time coordination were vital. MacKay Sposito’s team provided construction management and inspection services, ensuring quality, safety, contractor compliance, and smooth stakeholder collaboration through advanced communication software and robust project controls.