California regulators approve SCE request to modify Tehachapi project

California regulators on Oct. 31 unanimously granted Southern California Edison (SCE) permission to install marker balls to a portion of the Tehachapi Renewable Transmission Project (TRTP) that will pass close to the Chino Airport, to install aviation lights on some transmission towers and reduce the height of some transmission structures near the airport (Docket No. A07-06-031).

The California Public Utilities Commission (CPUC) approved a proposed decision issued Oct. 14 by Administrative Law Judge (ALJ) Jean Vieth that the utility be allowed to change the project’s design to implement mitigation measures recommended by the Federal Aviation Administration (FAA), a CPUC spokesperson told TransmissionHub Nov. 4.

Specifically, in a request for modification filed Oct. 17, 2011, SCE sought permission to install marker balls on some wire spans and aviation lights on some transmission towers, and to reduce the height of several structures near the Chino Airport.

“The FAA recommended those design changes to increase aviation safety by making hazardous structures (wire spans and transmission towers) more visible to pilots,” ALJ Vieth said in her Oct. 14 proposed decision, which the CPUC approved as part of its Oct. 31 consent agenda.

In its review of SCE’s 2011 request, the CPUC determined additional environmental review was required and ordered the preparation of a supplemental environmental impact report (SEIR). Under the California Environmental Quality Act (CEQA), a supplement review must be given the same kind of notice and public review as the final EIR. The draft SEIR was prepared, released for public comment on April 11, 2013, and a final SEIR was released Oct. 3.

In the SEIR, the CPUC found that the additional structures “would contribute to the long-term loss and degradation of scenic highway viewsheds and the national scenic trail viewshed … and visual impacts would be significant and unavoidable.” However, the final SEIR noted that the marker balls and lights “increase public safety by making hazardous structures (transmission structures and wire spans) more visible to pilots,” according to the proposed decision.

The final SEIR concluded that the additional safety markers would not result in new impacts, nor would they substantially increase the severity of impacts identified in the final EIR, in the areas of air quality, biological resources, noise, or traffic and transportation.

Fewer net markers due to undergrounding

The commission’s July 11 ruling that a 3.5-mile section of the 500-kV project be placed underground through the city of Chino Hills, Calif., resulted in a reduction of the number of overhead spans and associated marker balls within the city and in the project as a whole. In her finding of facts regarding the SEIR, Vieth noted that undergrounding Segment 8A would result in a reduction in the number of marker balls from 78 to 37, a reduction of 41 market balls. No aviation lighting is proposed within the City of Chino Hills, Vieth noted in the finding of facts.

Another petition for modification proposed by SCE remains pending.

On Sept. 9, SCE filed a petition for modification of the commission’s July 11 decision approving the placement of the 3.5-mile Segment 8A underground. In that ruling, the CPUC directed the utility to study the possibility of changing the basic insulation level (BIL) rating for the line rather than approving voltage control equipment, as SCE had requested. In its September petition for modification, the utility said that portion of the order would be problematic, as the highest rated cross-linked polyethylene (XLPE) cable available that can be used in the 500-kV application is rated at 550-kV.

SCE further noted that undergrounding the transmission line will cause an increase in the transmission line charging current that could, in some cases, cause the voltage on the system to exceed its 550-kV rating. Therefore, it said, voltage control was necessary to control voltage and prevent damage.

In addition, the utility stated that studying the possibility of changing the basic insulation level (BIL) rating for the line, as directed by the CPUC in its July order would significantly delay the in-service date of the TRTP, perhaps as late as 2019.

When completed, the project will be able to deliver up to 4,500 MW of largely renewable energy to Southern California, enough electricity to power three million homes, the utility said.

SCE has called the project “a critically important, high-voltage transmission line, the timely completion of which is essential for California’s progress toward its aggressive renewable energy goals.”

California’s renewable portfolio standard calls for 33% renewable energy by 2020.

SCE is a subsidiary of Edison International (NYSE:EIX).