The Idaho Public Utilities Commission on June 27 said that it will conduct a public hearing on July 26 in Ketchum, Idaho, regarding Idaho Power’s proposed 138-kV transmission line and related facilities.
According to the commission’s notice, Idaho Power last November filed an application for a certificate of public convenience and necessity to make system improvements and to secure adequate and reliable service to customers in the Wood River Valley.
Specifically, the commission said, Idaho Power proposes to build a new – second – 138-kV transmission line and related facilities “to provide redundant service from the Wood River substation near Hailey into the Ketchum substation.”
As TransmissionHub reported, in a November 2016 order, the commission noted that the company would like to begin construction of the line in 2019, and have it in service by 2020.
The commission also noted in that order that according to the company, the North Valley is served by a substation in Ketchum and a substation in Elkhorn Valley within the Sun Valley city limits. The two substations are supplied by a single 12.4-mile, 138-kV transmission line from the Wood River substation in Hailey that was built with wooden poles in 1962.
Idaho Power in 1974 obtained a certificate to build a second transmission line to the North Valley as well as related facilities. In 1995, the company participated in public meetings about the proposed construction of a second transmission line, the commission said, adding that there was considerable public opposition to the proposal, based on, for instance, the route that the line would take. At the company’s request, the commission cancelled that certificate. The commission also said Idaho Power initiated a Community Advisory Committee (CAC) in 2007 to develop the Wood River Valley Electrical Plan, and in 2011, the CAC recommended that Idaho Power build the second 138-kV line.
Among other things, the commission said that Idaho Power asserts that the existing 138-kV radial transmission line is aging and needs reconstruction, and that reconstruction of that line would result in “extreme disruption of service … [unless the company builds] either a redundant transmission line or a temporary line that would be removed after construction.”
According to Idaho Power, the proposed redundant 138-kV line would increase reliability and avoid long-term disruption of service to the North Valley, the commission said.
In May 5 direct testimony, Michael Morrison, a staff engineer with the commission, said that the company has not provided compelling evidence that the benefits of a fully redundant line justify the $30m cost proposed for the project. Nevertheless, a second line will be necessary to facilitate repair of the existing transmission line, Morrison said.
Among other things, he said that much of the cost of the company’s preferred route would be incurred providing aesthetic benefits to the City of Ketchum, and that he does not believe that it would be appropriate for the incremental costs of providing those benefits to be passed on to the general body of Idaho Power ratepayers. He said that he recommends that the commission direct the company to install a temporary overhead transmission line as necessary to facilitate repair of the existing transmission line.
“In the event that the commission determines that a second line is needed, then I recommend that an overhead transmission route through the City of Ketchum be considered the base case,” Morrison said. “The City of Ketchum and other affected cities/counties should be prepared to provide the incremental difference in cost required to place those facilities underground.”
In June 23 rebuttal testimony, David Angell, the transmission and distribution planning manager with Idaho Power, said that the company designs its system to meet certain reliability and service quality standards that are consistent with other utilities as well as national standards. When those criteria for upgrades or additions are met, all of which are met by the current situation in the North Valley, redundant service is provided to reduce the risk, cost, and potential damage to the public from interruption of service or long-term outage, Angell said.
The North Valley area has grown to such a size, is relatively remote with difficult-to-access facilities, and has a substantial seasonal resort economy that the risk of harm from a potential long-term outage and the potential catastrophic effects of a long-term outage during extreme winter conditions when North Valley electric load peaks is too great to be served by a single, radial feed – no matter how reliable that single transmission line may have been in the past, Angell said.
The redundant transmission source is the most cost-effective means of providing the required reliability improvements and mitigation of potentially damaging outages in the North Valley, Angell said, adding that the company has evaluated several other sources of alternative or additional generation for the North Valley area.
According to the commission’s June 27 notice, a technical hearing is scheduled to convene on Aug. 8, and continue through Aug. 9, at the Commission Hearing Room in Boise, Idaho.
Idaho Power’s parent company is IDACORP (NYSE:IDA).