Arizona committee issues certificates for projects by Nogales Transmission, UNSE

The Arizona Power Plant and Transmission Line Siting Committee on Sept. 22 issued certificates of environmental compatibility for Nogales Transmission, L.L.C., and for UNS Electric, Inc., (UNSE) for the Nogales Interconnection Project and the UNSE Nogales Tap to Kantor Upgrade Project.

In both certificates, the committee noted that it held public hearings on Sept. 5-6 in Nogales, Ariz., and Sept. 7-8 in Tucson, Ariz., for the purpose of receiving evidence and deliberating on the July 26 joint application of Nogales Transmission and UNSE for certificates of environmental compatibility authorizing construction of the Nogales Interconnection Project and the UNSE Nogales Tap to Kantor Upgrade Project, including an approximately 27.5-mile upgrade of UNSE’s existing 138-kV transmission line from a point near the existing Western Area Power Administration (WAPA) Nogales Tap in Pima County and the existing UNSE Kantor substation in Santa Cruz County, a new approximately three-mile 138-kV double circuit transmission line in Santa Cruz County from a point near the existing UNSE Valencia substation to the proposed Gateway substation and associated facilities, and a new approximately two-mile, 230-kV transmission line and associated facilities in Santa Cruz County to interconnect the proposed Gateway substation to the Mexican National Electric System.

The committee also said that at the conclusion of the hearings, it voted 9-0 to grant:

  • Nogales Transmission, its successors and assigns the certificate for construction of the Gateway to U.S.-Mexico Border 230-kV transmission line
  • UNSE, its successors and assigns the certificate for construction of the Nogales Tap to Kantor Upgrade Project and these components of the Nogales Interconnection Project – the Vail to Valencia 138-kV transmission line and the Gateway to Valencia 138-kV transmission line

Nogales Transmission certificate

In the certificate for Nogales Transmission, the committee noted that the Nogales Interconnection Project consists of these three components, all of which will be located in the City of Nogales in Santa Cruz County:

  • A UNSE 138-kV Gateway substation and a Nogales Transmission 230-kV Gateway substation, which will be the location of high voltage direct current (HVDC) converter equipment, referred to collectively as the Gateway substation
  • A new approximately three-mile double circuit 138-kV transmission line to be built by UNSE – one circuit to extend the existing UNSE Vail to Valencia line from a point near UNSE’s Valencia substation to the proposed Gateway substation – creating the Vail to Valencia 138-kV transmission line – and one circuit to connect the proposed Gateway substation to the existing Valencia substation – creating the Gateway to Valencia 138-kV transmission line
  • A new approximately two-mile single circuit 230-kV transmission line to be built by Nogales Transmission on double-circuit capable structures that will connect the proposed Gateway substation to the U.S.-Mexico border – Gateway to U.S.-Mexico Border 230-kV transmission line – where it will interconnect with the Red Nacional de Transmisión (RNT), the state-owned transmission grid operated by Centro Nacional de Control de Energía (CENACE)

The committee noted that the Nogales Interconnection Project will provide an asynchronous interconnection in the vicinity of Nogales, Ariz., that will enable bidirectional electricity transfer between the Western Electricity Coordinating Council (WECC) and Mexico, facilitating cross-border commercial electricity transactions and enhancing transmission grid reliability in southern Arizona.

The committee also said that the Nogales Interconnection Project will provide bidirectional power flow and voltage support as well as emergency assistance, as needed, for the electric systems both north and south of the international border.

The certificate is granted upon certain conditions, enforceable against Nogales Transmission as they relate to the Gateway to U.S.-Mexico border 230-kV transmission line, including that Nogales Transmission is to:

  • Comply with all existing applicable statutes, ordinances, master plans, and regulations of any governmental entity having jurisdiction
  • 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 the AGFD as necessary on other issues concerning wildlife
  • Design the transmission line for the route approved for the Nogales Interconnection Project (referred to as the CEC Route) to incorporate reasonable measures to minimize impacts to raptors, cranes, and waterfowl
  • Consult with the State Historic Preservation Office with respect to cultural resources
  • Pursue reasonable efforts to work with private landowners on whose property the CEC Route will be located to mitigate the impacts of the location, construction, and operation of the Nogales Interconnection Project on private land and negotiate such ROW agreements in good faith
  • Use non-specular and non-reflective surfaces for the transmission line structures on the CEC Route

The committee added that the CEC Route is about 5.1 miles long and crosses land owned by the City of Nogales, the Arizona Department of Transportation (ADOT), and private owners within the City of Nogales. The CEC Route will originate at the existing Valencia substation located at Section 5, Township 24 South, Range 13 East, and will follow an existing UNSE transmission line corridor west for about 0.4 mile, using the existing conductor and poles for about 1,900 feet on an existing 138-kV UNSE line.

The committee added that the CEC Route will then continue, using double-circuit 138-kV construction, south and then west, crossing Interstate 19 (I-19) and the Mariposa Wash. The CEC Route will then continue southwest along a property line and on the north side of the Mariposa Wash to Mariposa Road, then cross Mariposa Road and continue along the south side of the Mariposa Wash for 0.6 mile.

The CEC Route will then head north for 0.75 mile to the proposed Gateway substation, located at Section 12, Township 24 South, Range 13 East, the committee added, noting that at the western end, both circuits will be connected to the Gateway substation. At the eastern end, the existing Vail to Valencia line will be severed and connected to one circuit of that new line, thereby converting the existing Vail to Valencia transmission line to the new Vail to Gateway transmission line. The second circuit, the committee added, will connect with the existing portion of the UNSE 138-kV transmission line at an existing pole 1,900 feet west of the existing Valencia substation, and travel east along the north side of W. White Park Drive to the Valencia substation.

That circuit will constitute the new Gateway to Valencia transmission line, the committee said, adding that the Gateway to U.S.-Mexico Border 230-kV transmission line portion of the CEC Route will originate at the Gateway substation and follow the same path out of the Gateway substation as the 138-kV line for 0.6 mile. The CEC Route will continue southwest on the north side of the Mariposa Wash and then continue south to the international border, where the 230-kV line will connect to a line to be built in Mexico, the committee said.

The approved ROW width for the CEC Route is 150 feet, the committee said, noting that the right of way (ROW) will be located within a 1,000-foot corridor, except for areas in which the corridor includes Coronado National Forest (CNF) land, in which case the corridor will extend up to and abut CNF land.

UNSE certificate

In the certificate for UNSE, the committee said that the Nogales Tap to Kantor Upgrade Project, which will be located in the City of Tucson, Pima County, and Santa Cruz County, consists of an upgrade of a 27.5-mile segment between a point near the WAPA Nogales Tap switchyard in Pima County and UNSE’s Kantor substation in Santa Cruz County, which will include replacement of the existing conductor and the existing steel monopoles, and relocating poles within new and amended ROW.

The route approved for the Nogales Tap to Kantor Upgrade Project (referred to as the Nogales Tap to Kantor CEC Route) is about 27.5 miles long and crosses land owned by the Arizona State Land Department (ASLD), and private owners within the City of Tucson, Pima County, and Santa Cruz County.

The committee added that the Nogales Tap to Kantor CEC Route will originate in Pima County 320 feet south of the Nogales Tap on the west side of Wilmot Road at existing pole no. VLKA-5-2, and cross Wilmot Road to the east where it will continue south for 9.5 miles along existing and amended ROW.

The Nogales Tap to Kantor CEC Route will continue south to a point where the existing transmission line corridor turns southwest and continues diagonally for 18 miles to the Kantor substation, located in Santa Cruz County at Section 8, Township 20 South, Range 13 East.

The committee also said that the approved ROW width for the Nogales Tap to Kantor CEC Route is 100 feet, and that the ROW will be located within a 1,000-foot corridor.

The committee said that the certificate is granted upon certain conditions, enforceable against UNSE as they relate to the Nogales Tap to Kantor Upgrade Project, as well as these components of the Nogales Interconnection Project: the Vail to Valencia 138-kV line and the Gateway to Valencia 138-kV line.

The conditions include that UNSE is to:

  • Obtain all approvals and permits required by any government entity having jurisdiction
  • Comply with the notice and salvage requirements of the Arizona Native Plant Law and, to the extent feasible, minimize the destruction of native plants during the CEC Route construction (for purposes of the UNSE certificate, the committee said that the Nogales Interconnection CEC Route and Nogales Tap to Kantor CEC Route are referred to collectively as the CEC Route)
  • Build, operate, and maintain all facilities, improvements, and structures in the Nogales Interconnection CEC Route in conformity with all terms, conditions, and stipulations set forth in a presidential permit if such permit is issued to Nogales Transmission for the Nogales Interconnection Project
  • Participate in good faith in state and regional transmission study forums to coordinate transmission expansion plans related to the CEC Route and to resolve transmission constraints in a timely manner

Among other things, the committee said, “The Nogales Interconnection Project and Nogales Tap to Kantor Upgrade Project are in the public interest because the Nogales Interconnection Project and Nogales Tap to Kantor Upgrade Project’s contribution to meeting the need for an adequate, economical, and reliable supply of electric power outweighs the minimized impact of the Nogales Interconnection Project and Nogales Tap to Kantor Upgrade Project on the environment and ecology of the state.”

About Corina Rivera-Linares 3235 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.