The Western Area Power Administration (WAPA) and Tucson Electric Power (TEP) have signed a joint participation agreement to rebuild 64 miles of the Parker-Davis Project transmission system in Arizona.
The agreement calls for TEP to upgrade an existing 115-kilovolt (kV) WAPA line with a double-circuit 230-kV transmission line. When complete, TEP would own and operate one 230-kV circuit and WAPA would own and operate the other circuit.
The Vail-Tortolita project also calls for existing wood pole structures from the 1950s to be replaced with steel monopoles. Ownership of the transmission structures would be split between TEP and WAPA.
WAPA said it would operate its circuit at 115 kV to match the existing system, so upgrades will not be required at substations. “At this time, 115-kV is sufficient for serving WAPA’s customers,” WAPA spokesman Eric Barendsen said via email. Should there be a need in the future for the 230-kV line, “we have a head start on any upgrades that will be needed in the future to accommodate growth,” he said.
The Vail-Tortolita project would run between TEP’s Vail Substation southeast of Tucson and its Tortolita Substation north of Marana in Pinal County to strengthen reliability and serve growing energy needs in the Tucson area.
TEP is funding the project, while WAPA has responsibility for project management and construction. The project is anticipated to begin in 2023 and be completed by 2026.
The Arizona Corporation Commission in January 2021 approved TEP’s application to amend a Certificate of Environmental Compatibility for the project.
“This partnership will deliver the benefits of more reliable and resilient power service for TEP and WAPA customers alike,” Tracey LeBeau, WAPA administrator and CEO, said in a statement. “This project could serve as a model for how future large-scale, public-private partnerships can help upgrade our nation’s energy infrastructure.”
The Vail-to-Tortolita Project was originally part of the larger Southline Transmission Project. TEP purchased development rights for the project’s western portion from Southline in 2021.
The other elements of the Southline Transmission Project, in which WAPA is a participant, include rebuilding the existing transmission line between the Nogales and Apache substations in southeastern Arizona and constructing new transmission lines between southern New Mexico and Arizona.