Arizona regulators approve, with modification, 138-kV project proposed by TEP

The Arizona Corporation Commission, in a Nov. 27 order, approved – with modification – a certificate of environmental compatibility (CEC) issued by the Arizona Power Plant and Transmission Line Siting Committee for Tucson Electric Power’s (TEP) proposed Sonoran Substation to Wilmot Energy Center 138-kV Transmission Line Project.

The commission said that it “has balanced all relevant matters in the broad public interest, including the need for an adequate, economical and reliable supply of electric power with the desire to minimize the effect thereof on the environment and ecology of this state, and finds that the CEC for the … application for siting approval is in the public interest as modified by this order.”

The commission also said that it finds that it is in the public interest to modify the CEC to change “Condition No. 1 of the CEC” to read:

  • “This authorization to construct the project shall expire ten (10) years from the date this certificate is approved by the Arizona Corporation Commission, with or without modification. Construction of the project shall be complete, such that the project is [in service] within this ten-year timeframe. However, prior to the expiration of the time period, TEP may request that the commission extend the time limitation.”

The commission said that it further finds that it is in the public interest to modify the CEC by deleting “Condition No. 24,” which stated, “Once all right of way has been acquired, the applicable corridor will be null and void.”

As noted in the Oct. 2 certificate, the project is being developed to interconnect a 100-MW solar and 30-MW battery storage facility – the Wilmot Energy Center (WEC) – to TEP’s system. The project will consist of two portions:

  • A northern portion, which will connect three existing 138-kV transmission lines into and out of the planned Sonoran substation. The lines will be supported by three double-circuit, 138-kV transmission structures within a common corridor
  • A southern portion, which will connect the planned Sonoran substation to the planned Cisne switchyard via a single 138-kV transmission line

While structures for the line will be designed as double-circuit-capable structures, TEP’s application for a certificate requested approval for construction of one 138-kV circuit for that portion of the project. The certificate also noted that the Cisne switchyard is a point of interconnection for the planned WEC to the TEP 138-kV transmission system.

Noting that the company proposed two alternative routes for the northern and southern portions of the project, the certificate said that as a result of the committee’s deliberations, it approved “Northern 2 Preferred and Southern 1 Preferred as well as the Cisne switchyard.”

Northern 2 Preferred is about 1.42 miles long, while Southern 1 Preferred is about 1.86 miles long. The certificate further noted that the project will have a 1,000-foot corridor for the northern portion of the project, which is the portion of the project north of the proposed Sonoran substation. The project will have a 500-foot corridor for the portion of the project leaving the Sonoran substation to the south until the line crosses south Swan Road.

The certificate added that once the line crosses south Swan Road, a corridor of 250-foot extending to the west from the centerline of south Swan Road will be used up to the point the line enters WEC land. From the northern property line of WEC land to the Cisne switchyard, the corridor will be 500 foot, the certificate said.

Among other things, the certificate noted that conditions for approval include that TEP is to comply with the Arizona Game and Fish Department guidelines for handling protected animal species, should any be encountered during construction and operation of the project, and is to consult with that department as necessary on other issues concerning wildlife.

About Corina Rivera-Linares 3286 Articles
Corina Rivera-Linares was TransmissionHub’s chief editor until August 2021, as well as part of the team that established TransmissionHub in 2011. Before joining TransmissionHub, Corina covered renewable energy and environmental issues, as well as transmission, generation, regulation, legislation and ISO/RTO matters at SNL Financial from 2005 to 2011. She has also covered such topics as health, politics, and education for weekly newspapers and national magazines.