ACC approves, with modifications, certificate issued by siting committee for Southline project

The Arizona Corporation Commission (ACC), in a Feb. 24 decision, concluded that the certificate of environmental compatibility (CEC) issued by the Arizona Power Plant and Transmission Line Siting Committee for Southline Transmission, L.L.C.’s Southline Transmission Project is approved, with modifications.

As noted in the committee’s December 2016 certificate, the project includes the construction and operation of an approximately 370-mile electric transmission line and associated facilities in southern New Mexico and Arizona. The project includes two sections: a new approximately 249-mile, double-circuit, 345-kV transmission line and associated facilities beginning in Doña Ana County, N.M., and traveling west into Cochise County, Ariz., (the “new build section”); and the upgrade of about 121 miles of two existing Western Area Power Administration (WAPA) 115-kV line segments to double-circuit 230-kV line segments located in Cochise, Pima, and Pinal counties, and the City of Tucson in Arizona, as well as short segments of new transmission lines and associated facilities needed to interconnect the upgraded WAPA lines to existing substations (the “upgrade section”).

The committee added that of the 370 miles, about 72 miles of the Arizona portion of the project was before the committee in the company’s application. The Arizona portion of the project includes about 67 miles of the new build section – including less than one mile of associated facilities – and the entire upgrade section – including the 121 miles of WAPA-owned facilities, and about five miles of associated non-WAPA-owned facilities to connect the upgraded WAPA lines to existing substations, the committee said.

The route for which Southline sought committee approval is about 72 miles and crosses land owned by the U.S. Bureau of Land Management (BLM), the Department of Defense (DoD), the Arizona State Land Department (ASLD), and private landowners (“CEC Route”).

The CEC Route consists of about 67 miles of the new build section (the “CEC New Build Route”) and about five miles of the upgrade section (the “CEC Upgrade Route”), the committee added. Furthermore, five existing substations associated with the CEC Route will be expanded internally or with adjacent new Southline facilities to accommodate interconnections to the upgraded WAPA facilities: the Arizona Electric Power Cooperative (AEPCO) Apache substation; the AEPCO Pantano substation; the Tucson Electric Power (TEP) Vail substation; the TEP DeMoss Petrie substation; and the TEP Tortolita substation – collectively, the CEC substations.

The CEC New Build Route consists of about 66 miles of new double-circuit, 345-kV transmission line in a new 200-foot-wide right of way (ROW), terminating at a new substation to be owned by Southline, near the existing AEPCO Apache substation; and less than one mile of 115-kV or 230-kV transmission line and associated facilities in a new 200-foot-wide ROW needed to connect the new Southline Apache substation to the AEPCO Apache substation, the committee added.

The CEC New Build Route enters Arizona at the New Mexico border about five miles north of Interstate-10 and about nine miles south of the Graham/Greenlee County line. Beginning at the state line, the CEC New Build Route parallels an existing El Paso Natural Gas pipeline for about 43 miles in a westerly direction, crossing two 69-kV power lines, and Interstate-10 about five miles west of the community of San Simon.

The CEC New Build Route continues westerly south of Interstate-10 for about eight miles, the committee added, noting that two miles south of the community of Bowie, the CEC New Build Route turns northwest for about three miles before heading west again for about 13 miles.

Six miles northeast of the City of Willcox, the CEC New Build Route then turns south to parallel an existing AEPCO 230-kV transmission line for about 23 miles along the eastern edge of Willcox Playa. The commission also said that the CEC New Build Route then crosses an El Paso Natural Gas pipeline about five miles east of the City of Willcox and crosses State Route 186 and Kansas Settlement Road about six miles southeast of the City of Willcox, paralleling 3.5 miles of an existing El Paso Natural Gas pipeline at the southern end of Willcox Playa.

The CEC New Build Route then heads south, then west, for less than one mile and interconnects the new Southline Apache substation. The commission added that the CEC New Build Route then crosses west over US Highway 191 and then heads northwest and terminates at the existing AEPCO Apache substation, located west of US Highway 191 about four miles south of the community of Cochise and nine miles south of Interstate-10.

The CEC Upgrade Route consists of about five miles of new non-WAPA-owned 138-kV and 230-kV transmission lines and associated facilities that will interconnect the upgraded WAPA 230-kV Apache-Tucson and Tucson-Saguaro transmission lines to four existing substations owned and operated by other Arizona load-serving utilities.

The existing AEPCO Pantano substation is located about 41 miles west of the Southline Apache substation, eight miles east of the community of Vail, and about two miles south of Interstate-10. The commission added that the approximate one mile of 230-kV transmission line and associated facilities that will interconnect the Pantano substation to the upgraded WAPA facilities is within the approximately 25-acre substation expansion area that is located adjacent and west-northwest of the Pantano substation.

The TEP Vail substation is located about eight miles northwest of the community of Vail and one mile south of Interstate-10. The approximate two miles of 230-kV transmission line and associated facilities that will interconnect the Vail substation to the upgraded WAPA facilities begin in the approximate 28-acre substation expansion area that is located adjacent and south-southwest of the Vail substation, and travels west for 0.1 mile before turning south and continuing for about 1.8 miles to the upgraded WAPA facility.

The commission also noted that the DeMoss Petrie substation is located along Flowing Wells Road in the City of Tucson, north and adjacent to Interstate-10 and east of Grant Road. The less than one mile of 138-kV transmission line and associated facilities that will interconnect the DeMoss Petrie substation will be located within the parcels owned by TEP.

The commission further noted that the TEP Tortolita substation is located in Pinal County about three miles north of the Pima County line and 0.6 mile east of Interstate-10. The approximately 1.5 miles of 230-kV transmission line and associated facilities that will interconnect the Tortolita substation to the upgraded WAPA facilities begin in the northwest corner of the 16-acre Tortolita substation expansion area – which is located primarily within the existing Tortolita substation yard, with an additional approximately one-acre section adjacent and northwest of the Tortolita substation – and heads west for about 600 feet. The line then heads southwest for about 1,300 feet, northwest for about 3,000 feet, southwest again for about 2,400 feet, and then northwest again for about 1,000 feet, the commission said.

The certificate is granted upon certain conditions, the commission said, such as that Southline is to comply with the Arizona Game and Fish Department (AGFD) guidelines for handling protected animal species, should any be encountered during construction, and is to consult with AGFD as necessary on other issues concerning wildlife. Furthermore, Southline is to consult with the State Historic Preservation Office with respect to cultural resources, and if any archaeological, paleontological, or historical site or a significant object that is at least 50 years old is discovered on state, county, or municipal land during the construction of the CEC Route, Southline is to promptly report the discovery to the director of the Arizona State Museum and, in consultation with the director, is to immediately take all reasonable steps to secure and maintain the preservation of the discovery.

In its Feb. 24 decision, the ACC said that it modifies the CEC to add certain conditions, including that Southline must obtain WAPA’s agreement that the portion of the project that crosses the Mountain View Ranch property or its viewshed will conform to such matters as that support structures are to be monopoles, with colors, height, and siting selected, in consultation with landowners, to minimize visual impact to the extent reasonably feasible; lattice supports are not to be used in such section.

The project is in the public interest because it aids the state in meeting the need for an adequate, economical and reliable supply of electric power, the ACC said, adding that the conditions resolve matters concerning the need for the project and its impact on the environment and ecology of the state raised during the course of the proceedings.

Southline is a subsidiary of Hunt Power L.P.

About Corina Rivera-Linares 3059 Articles
Corina Rivera-Linares, chief editor for TransmissionHub, has covered the U.S. power industry for the past 15 years. Before joining TransmissionHub, Corina covered renewable energy and environmental issues, as well as transmission, generation, regulation, legislation and ISO/RTO matters at SNL Financial. She has also covered such topics as health, politics, and education for weekly newspapers and national magazines. She can be reached at clinares@endeavorb2b.com.