Sioux Falls, S.D.-headquartered NorthWestern Energy has announced a proposal to build and operate the Mountain States Transmission Intertie (MSTI), a 500 kV electric transmission line between southwestern Montana and southeastern Idaho. According to the company, the transmission line would meet customer demand for additional transmission capacity and relieve constraints on the existing high-voltage transmission system in the region.
The proposed MSTI project would extend approximately 350 miles to 390 miles from a new substation to be built either near Townsend or Garrison, Mont., to the existing Borah or Midpoint substations located in southern Idaho, NorthWestern Energy says. The line's support structures would be constructed of lattice steel or tubular steel self-supporting towers with an average height between 110 feet and 130 feet. The span between towers would average 1,500 feet, with a right-of-way width of approximately 220 feet.
‘We are preparing an application for a certificate under the Montana Major Facility Siting Act (MFSA), and we will then proceed with environmental review under the National Environmental Policy Act and the Montana Environmental Policy,’ says Rick Walsh, NorthWestern Energy's manager of environmental permitting. ‘The Montana Department of Environmental Quality will oversee the MFSA application and will be the state lead agency for the subsequent Environmental Impact Statement.’
Under the current plan, the transmission line would be placed into service in 2013.