Bonneville Power Administration

McNary – John Day 500kV Transmission Line, WA – OR

Wilson constructed the McNary – John Day No. 1 500kV lattice steel transmission line, relocated the Rock Creek – John Day 500kV lattice steel single-circuit transmission line, and reconstructed the River Crossing Corridor for Bonneville Power Administration.

The 79-mile transmission line consisted of 369 steel lattice towers and footings, triple bundle 1590 ACSR Deschutes conductor, and 72 count ADSS fiber optic cables. The transmission line started in Washington across the Columbia River from Umatilla, Oregon. The line then proceeded west approximately 70 miles along the Columbia River. The crossing of the Columbia River included the installation of a 315 foot tall, 250,000 pound lattice tower to maintain appropriate clearance over the water.

The project included access road construction, avoidance and protection of environmental resources, and timing restrictions. Due to steep mountain terrain for 30 miles of the transmission line, helicopters were used extensively.