Purpose and Need
Tri-State is proposing to rebuild and upgrade the existing Montrose-Nucla-Cahone transmission line from 115 kV to 230 kV. The upgraded transmission line will replace a 57-year old line, support growth of Tri-State’s Member Systems and improve the overall performance of the region’s electrical grid.The transmission line would be upgraded to 230 kV using primarily wooden H-frame structures and some self-supporting steel structures.The H-frame structures would be approximately 25 feet taller and 10 feet wider than the existing structures and would require an additional 50 feet of right-of-way for a total of 150 feet.The rebuild would consist of the following components:
- A 230-kV transmission line from the existing Montrose Substation west of Montrose, Colorado to a new Nucla 230-kV Substation .
- A 230-kV transmission line from the new Nucla 230-kV Substation to the existing Cahone Substation near Dove Creek, Colorado.
- Double circuit structures between the new Nucla 230-kV Substation and the existing Nucla 115-kV Substation at the Nucla Power Plant. The double circuit would consist of a 115 kV line back to the Nucla Power Plant and the new 230-kV Nucla to Cahone transmission line.
- A new substation near the existing Nucla Substation and power plant, near Nucla, Colorado. The new substation would be called the Maverick 230-kV Substation.
- Construction of the project will be completed in two segments. Construction of the Nucla Substation and Nucla to Cahone segment would begin in 2017, followed by the Nucla to Montrose segment in 2018.
- PUC Approved: Colorado Public Utilities Commission has validated the purpose and need and issued Tri-State a Certificate of Public Convenience and Necessity for the project.
- Safety & Reliability: The existing line was built in 1958 and is becoming more difficult to maintain. The age of the poles makes them more susceptible to cracking, rotting, insect infestation and woodpecker damage. A new line would reduce safety risks associated with maintenance of the existing line and address reliability issues.
- Improved Service and Reduced Costs: The line will strengthen the ‘transmission backbone’ that provides electricity to individuals, farms and businesses in the region. It will also minimize maintenance costs, reduce outages and allow our members to provide the reliable power that the region is dependent on for future economic development.
- Future Load Growth: The existing line is not capable of handling the future load increases in southwest Colorado.
The line will be designed to minimize environmental impacts.
- Tri-State has completed a thorough analysis and believes the line can be constructed, operated and maintained in a manner that will not impact wildlife or the environment.
- Tri-State has standard design measures that we will implement for this project to minimize impacts to land use, water quality, air quality, wildlife, cultural resources, and vegetation resources. Tri-State has made application for an amending authorization with the USFS and the BLM and is participating in the NEPA process being directed the BLM.
- Tri-State is keenly aware of the presence of critical habitat for Gunnison Sage Grouse along a small portion of the line and is working with the BLM and Colorado Parks & Wildlife through the Environmental Assessment/NEPA process to identify mitigation efforts to protect the species.
- Tri-State plans to use single steel pole structures (as opposed to wood pole H-frame structures) in the Gunnison Sage Grouse critical habitat to reduce perch and nesting surfaces for the grouse’s avian predators.
- Tri-State is considering reasonable routing alternatives to the project to minimize impacts to the Gunnison Sage Grouse. An analysis of undergrounding the project through the critical habitat or re-routing completely around critical habitat was completed and the results have been provided to the BLM for objective review as part of the Environmental Assessment/NEPA process.
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Tri-State Generation and Transmission Association, Inc. is a wholesale electric power supplier owned by the 44 electric cooperatives that it serves. Tri-State generates and transmits electricity to its member systems.
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