T&D World Magazine

NorthWestern Energy Announces Plans to Upgrade Transmission Line Serving Big Sky, Montana

The rapidly growing demand for electricity in and around Big Sky, Montana along with future planned development has prompted NorthWestern Energy to begin the process to upgrade one of the existing transmission lines serving the area. The company is seeking the necessary permits to rebuild the existing 69-kV transmission line between the Jack Rabbit Substation west of Bozeman and a new substation near Meadow Village in Big Sky. The approximately 35-mile 161-kV transmission line would eventually replace the existing line along the existing corridor that roughly follows US Highway 191.

“Gallatin County in general, and the Big Sky area in particular, has experienced significant growth in recent years and with additional planned development in both the residential market and resort industry, we only expect that growth to continue,” said Dave Gates, Vice President – Wholesale Operations. “The new transmission line and associated substation equipment is necessary to ensure that the area has adequate capacity for future growth while improving reliability for existing customers, especially during periods of high electric demand,” Gates added.

The new line will consist of a combination of single-pole, wooden structures placed approximately 300 ft apart. In some areas two-pole wooden "H-frame" structures may be used to allow further spacing between structures. The standard right-of-way width for a single pole 161-kV transmission line is 50 ft. The standard right-of-way width for a two-pole “H-frame” line is 80 ft. The height of the new structures will vary from 60 ft above ground to 90 ft, depending on terrain and structure type.

While the engineering design and permitting requirements will determine the actual cost and construction duration, the construction on the estimated $20-30 million project would begin sometime after the permitting process is completed in mid-2009 and may take up to three years to complete.

The company plans to build the new line under a statutory exclusion from the Montana Major Facility Siting Act. Under Section 75-20-104(8)(a)(ii), MCA, the line would be excluded from Siting Act coverage if NWE obtains right-of-way agreements or options for a right-of-way from more than 75 percent of the landowners who collectively own more than 75 percent of the property along which the new line is to be located. If NorthWestern is unable to obtain the statutory exclusion, the Siting Act's full public and agency review provisions will apply to the new line. The Montana Department of Environmental Quality (DEQ), which administers the Siting Act, will then determine the line location.

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