Doubling electrical capacity to support a slope-side Rocky Mountain town.

Home to the “biggest skiing in America,” Big Sky, Montana’s, demand for electricity exceeded the old line’s capacity. So NorthWestern Energy selected our team to design a new 37-mile 161kV transmission line through rugged United States Forest Service land. Between the incredible level of flexibility required to construct the project and its steep, rocky canyon route, it was a complex job. 

Awaiting issuance of a Special Use Permit by the USFS, we evaluated multiple foundation and pole options for their ability to minimize environmental and aesthetic impacts on this line. Due to an injunction we weren’t allowed to do subsurface investigation of the soil to determine which foundation options were ideal, so we brought a geotechnical engineer on site during construction. Soil stratum was identified during excavation, and we modified the steel monopole foundations based on actual excavation spoils.

Access to the transmission route was limited by steep talus slopes, preserved USFS land, the Gallatin River and a busy highway. The use of heavy-lift helicopters was coordinated on almost every aspect of construction so we could build in the tight corridor and rugged terrain. 

Now connected to the grid, the Jackrabbit to Big Sky transmission line will keep this remote resort destination operating during peak demand for the into the future.