Westwing 230kV Interconnection Project

Mom cooking with child


Voltage - 230kV
Location – Peoria, AZ

Project need
Provide a new 230 kilovolt (230kV) transmission line between proposed customer energy projects and the Westwing Substation.

Project description
We are planning to build the Westwing 230kV Interconnection Project, a new 230-kilovolt (kV) transmission line needed to interconnect separate customer proposed battery electrical storage projects to the existing Westwing Substation.

The proposed customer battery electrical storage facilities will enhance the APS electric system and allow flexibility in the delivery of power to customers throughout the Phoenix metropolitan area. With these proposed facilities comes a need for a new 230kV transmission line to interconnect the customer battery electrical storage facilities to the existing Westwing substation, located west of the Loop 303, south of Happy Valley Road.

We are dedicated to providing safe and reliable electric service to make these facilities a part of our system. We will rebuild and co-locate the new transmission line with an existing 69kV line that runs adjacent to and between the proposed customer battery storage projects, located south of Happy Valley Road and near the El Mirage Road alignment, and the Westwing Substation for a total length of approximately 0.5 mile.

Project Planning
In mid-2020, we hired SWCA, an environmental consulting firm, to assist in evaluating the project site, to assess potential environmental impacts, and to support the public outreach process. Baseline information about land use, visual, biological, cultural and recreational resources for the area has been collected. Early in the project process, we began coordination with project area stakeholders including other utility partners and Maricopa County in order to share project information and to collect input from them.

Project maps
Study Area
Existing Land Use
Future Land Use
Land Ownership

Project features
We work hard to balance the energy needs of our customers while protecting the environment and natural beauty of the area. The rebuilt transmission line structures will consist of double-circuit 230kV steel monopoles with a double-circuit 69kV built lower on the pole. The steel monopoles are anticipated to be up to 150 feet in height, which is generally shorter than nearby existing transmission structures*.

*Exact structure, height, and right-of-way width may vary.

Public Hearing Information
July 1, 2021: A Prefiling Conference was held with the Chairman of the Arizona Power Plant and Transmission Line Siting Committee to discuss the application, public hearing agenda, and ensure proper notifications and filing requirements will be met. Prefiling conference transcripts can be viewed in related documents below.

July 13, 2021: An application for a Certificate of Environmental Compatibility (CEC) was filed at the ACC Docket Control. The docket number for this Project is L-00000D-21-0257-00190. A PDF copy of the CEC application can be viewed in related documents below.

August 23-25, 2021: The Arizona Power Plant and Transmission Line Siting Committee held hearings at the Double Tree by Hilton, Phoenix North located at 10220 N. Metro Pkwy E. Phoenix, AZ 85051. At the conclusion of the hearings, the committee voted 10-0 approving the Recommended Order and Opinion to approve Certificates of Environmental Compatibility (Case 190). Hearing transcripts can be viewed in related documents below.

October 27, 2021: The Recommended Order and Opinion was reviewed and approved at the Open Meeting of the Arizona Corporation Commission. The approved CEC 190 can be viewed in related documents below.

Project Input
Although the public siting process is now complete, comments or questions can be submitted by email to:

Stephen Eich
Senior Siting Consultant

Newsletter #1
Newsletter #2
Newsletter #3 

Related documents
Case 190 CEC-1
Case 190 CEC-2
Hearing Transcripts - Part 1
Hearing Transcripts - Part 2
Hearing Transcripts - Part 3
Notice of Hearing
Prefiling Conference Transcripts

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