Idaho Power on Nov. 8 filed with the Idaho Public Utilities Commission an application seeking an order that would grant the company a certificate of public convenience and necessity (CPCN) to build a new 138-kV transmission line and related facilities to provide redundant service from the Wood River substation, near Hailey, into the Ketchum substation.
More specifically, the company said that it requests a CPCN for the particular line route and facilities identified as “Underground Transmssion-TP1,” to include a 138-kV overhead transmission line from the Wood River substation, north along Highway 75, to an underground transmission transition point near Elkhorn Road (TP1), and then underground to the Ketchum substation.
The company said that it requests that the commission find it to be in the public convenience and necessity that Idaho Power build the new line as a redundant source of energy into the Wood River Valley north of East Fork Road, including the communities of Sun Valley, Ketchum and areas of Blaine County, with a transition from overhead to underground transmission near Elkhorn Road.
The North Valley is currently supplied by a single-source radial line that has experienced sustained outage line events, which Idaho Power forecasts to increase in frequency, the company said. Furthermore, the existing radial transmission line, built in 1962, is aged and must be rebuilt, the company said, adding that the proposed facilities follow the same path and would replace existing distribution lines, which minimizes the aesthetic impact.
Idaho Power said that it has engaged the affected communities in the North Valley regarding a second 138-kV transmission line on a consistent basis since about 1995, and has planned a second transmission line to the North Valley since 1973. Today, beyond the continuing need to serve growing load, there are two reasons that now require the construction of the second 138-kV line, the company said: the increased reliability provided by a redundant source of energy; and the need to rebuild the existing and aging 138-kV radial transmission line without long-term disruption of service to the North Valley.
In addition, the Wood River Valley has seen moderate increases in load, which is expected to continue to grow into the future, the company said.
The North Valley contains the resort communities of Ketchum and Sun Valley, as well as the Sun Valley ski resort, the company said, adding that it serves more than 9,000 customers in the North Valley, and that the peak demand reached 63 MW during winter 2007.
The North Valley is served by two substations, one located in Ketchum and the other in the Elkhorn Valley within Sun Valley city limits, the company said. Those substations are supplied by a single, 12.4-mile, 138-kV transmission line from the Wood River substation in Hailey, the company said, adding that the line is built with wooden poles that were built in 1962.
Idaho Power said that it is currently engaged in acquiring the appropriate and required permits, including the submission in 2015 for a right of way (ROW) encroachment application to the cities of Ketchum and Sun Valley, as well as a conditional use permit, with a revised application in 2016 to Blaine County. All requests are pending, with a hearing set for the conditional use permit application with Blaine County on Nov. 10, the company said.
Idaho Power said that it would like to begin construction in 2019, and have the second line in service by 2020.
Among other things, the company said that while a previous CPCN to build a new 138-kV transmission line was canceled in 1995 based primarily upon public opposition, including the difficulty of finding an acceptable route, aesthetic impacts, perceived health and safety concerns, and the excessive cost of undergrounding the line, the need for a second source of energy has not dissipated with time.
Idaho Power’s parent company is IDACORP (NYSE:IDA).