Vail to Tortolita 230 Kilovolt Transmission Line

Under an agreement with WAPA, TEP will upgrade infrastructure along a 64-mile stretch between TEP’s Vail Substation located southeast of Tucson and its Tortolita Substation located north of Marana in Pinal County.

TEP purchased development rights from the Southline Project, a proposed transmission line designed to transmit electricity across southern New Mexico and southern Arizona. The agreement calls for TEP to upgrade an existing 115-kilovolt (kV) Western Area Power Administration (WAPA) line with a double-circuit 230 kV transmission line. When complete, TEP will own and operate one 230 kV circuit and WAPA will own and operate the other. Ownership of the transmission structures will be split between TEP and WAPA.

The project will interconnect with TEP’s energy grid at three locations. By constructing an additional circuit in conjunction with the upgrade of existing lines, TEP obtains transmission capacity parallel and adjacent to its existing 138kV system without the environmental, visual and cost impacts associated with building a separate line. The project calls for installing new steel monopoles to replace H-frame wood pole structures that are more than 50 years old.

TEP’s ownership of a 230kV circuit will reduce the need for required upgrades within TEP’s existing 138kV system.

Rebuilding of the WAPA-owned line was authorized under a National Environmental Policy Act permitting process that culminated in a Record of Decision issued by the Bureau of Land Management in April 2016. A link to the decision is available here.

Construction is expected to begin in September 2024. The line is expected to be in service by 2027.