Saguaro to Marana 115/138 Kilovolt Transmission Line Project

AEPCO is building a new 115-kV transmission line that would connect its existing Marana Substation, located near North Trico and West Marana roads, to its planned Adonis Substation, located near. North Owl Head Ranch Road and West Cochise Canyon Trail.

The planned transmission line will interconnect TEP’s planned Grier Substation to TEP’s existing transmission system and connect AEPCO’s existing Marana and planned Adonis substations to AEPCO’s transmission system. Monopole structures will be installed with a double-circuit configuration between the Adonis and Grier substations. TEP will own and operate one circuit, energized at 138-kV, while AEPCO will own and operate the other circuit, energized at 115-kV.

AEPCO will own and operate the remainder of the Project, a single-circuit 115-kV line proceeding west from TEP’s planned, unnamed substation to the existing Marana Substation.

TEP’s planned Grier Substation, which will be located south of West Marana Road, between North Sanders and North Wentz roads, is expected to be in-service in 2028.

The co-location of TEP and AEPCO assets will minimize environmental impacts and provide efficiencies in the permitting processes required to build the facilities.

Visit the AEPCO project website to view a project map.

Under state law, AEPCO must secure a Certificate of Environmental Compatibility (CEC) before building the transmission line.

AEPCO filed a CEC application in April 2022 with the Arizona Power Plant and Transmission Line Siting Committee, which approved AEPCO's application in a public process that provided neighbors and other stakeholders with opportunities to provide comments. The Arizona Corporation Commission reviewed and approved the CEC in July 2022.

For a complete project timeline, please visit the AEPCO project website.

The Arizona Power Plant & Transmission Line Siting Committee considered and voted to grant Arizona Electric Power Cooperative’s application for a certificate of environmental compatibility (CEC) at a public hearing that began on June 6, 2022. The Arizona Corporation Commission reviewed and approved the CEC in July 2022.

• Saguaro to Marana 115/138-kV Certificate of Environmental Compatibility Application
• Notice of Hearing — May 2022
• ACC Decision No. 78646 (Order Granting CEC) — July 2022