Gateway West Transmission Line Project

January 6, 2023

Gateway West Transmission Line Project

Due to the existing transmission grid across the West and it increasingly operating at full capacity during peak periods of customer electric use, this project was jointly proposed by Rocky Mountain Power and Idaho Power. The scope was to build and operate approxi- mately 1,000 miles of new high-voltage transmission lines between the Windstar substation near Glenrock, Wyoming and the Hemingway substation near Melba, Idaho. PacificCorp’s project included approximately 150 miles of 230 kilovolt (kV) lines in Wyoming and approximately 850 miles of 500kV lines in Wyoming and Idaho. PacifiCorp owns and operates one of the largest privately held transmission systems in the nation. This new transmission line delivers electricity to meet increasing customer needs in Idaho, Wyoming, Utah and other Western states, providing strength and reliability to the region’s transmission system.

The project is comprised of two major line segments.

• Windstar to Populus, Segment D, stretches approximately 488 miles starting at the Windstar substation near Glenrock, Wyoming, proceeding south to Medicine Bow and then spanning across southern Wyoming to the Populus substation near Downey, Idaho.
• Populus to Hemingway, Segment E, originates at the Populus substation near Downey, Idaho, and includes two 500kV single-circuit transmission lines that run approximately 502 miles across Idaho to the Hemingway substation near Melba, Idaho.

Quanta Services companies executed the following:

• QEPC provided overall project management, procurement and material management, project controls and Safety and Quality Assurance. QEPC’s detail-oriented management approach, dedication to safety excellence and commitment to total quality management allows us to effectively and efficiently manage complex EPC projects. Ultimately over 21.8 million pounds of steel, roughly 7 million feet of conductor, 33 steel H-frames, and three pole dead-ends were successfully procured and deliv- ered ahead of construction.
• Our Environmental team provided real-time infor- mation on changing ground conditions related to protected environmental areas and species restric- tions. On-site environmental specialists provided assessments and input information to our real-time, online project management system, working with our Project Management team to make daily deci- sions regarding schedules and crew locations.
• Summit Line Construction provided construction management, construction and craft labor for the project. Additionally, Summit leveraged additional resources from sister company, PAR Electrical Contractors. Construction crews had to work in a non-linear fashion that were dictated by biological and seasonal restrictions.
• Quanta Subsurface provided foundation design of the lattice tower and 345kV steel pole foundations, inspections, and geotechnical services.

The Gateway West Transmission Line Project utilized a variety of different tower structures. The towers for each segment and area of the project depend on the location, topography and needs.

Throughout the project, our team was sensitive and conscientious of the cultural, archaeological, and paleontological discoveries. The challenges brought to the team by environmental restrictions, non-linear construction, weather, and governmental agency coordination were tackled head on, and very professionally.