South Mountain Transmission Project
This project will support anticipated growth and development along Loop 202 in the Laveen area and strengthen SRP’s overall transmission system reliability.
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On Jan. 15, 2025, the Arizona Corporation Commission (ACC) voted unanimously to approve a Certificate of Environmental Compatibility for the South Mountain Transmission Project (SMT). The project will support anticipated growth and development along Loop 202 in the Laveen area and strengthen SRP’s overall transmission system reliability.
About the project
The SMT Project requires a new 500/230/69- kilovolt (kV) substation in Laveen, two new overhead double-circuit 230 kV transmission lines, ranging from 2-3 miles depending on the selected route, and less than 1 mile of two new overhead 500 kV transmission lines.
Why is this project needed?
The City of Phoenix is planning for future development in Laveen along the South Mountain Freeway, which may include a mix of land uses and development options, such as an industrial and tech park, hotel and resort, retail, hospitals, residential developments and new businesses.
Additional electric transmission will be required to power this planned development, which is in SRP’s service territory.
Certificate of Environmental Compatibility (CEC) Application
On Thursday, September 26, 2024, SRP filed with the Arizona Corporation Commission. A link to the CEC application is here. There will be a public hearing
associated with the CEC.
On Thursday, November 14th, the Arizona Power Plant and Transmission Line Siting Committee voted unanimously to approve the Certificate of Environmental Compatibility (CEC) for the South Mountain Transmission Project (SMT).
The routes filed in the CEC application are included below:
Project maps
SRP’s Approved Preferred and Contingent Route Map
Notice of Hearing Map
The map below shows the proposed route options from Figure 1 in the application. To develop and describe the route options, SRP created two Routing Areas: A South Routing Area and a North Routing Area. The South Routing Area shows the route options from the New Substation, which is on SRP-owned property, to a point where the routes intersect with the Laveen Area Conveyance Channel (LACC). The North Routing Area shows the route options from the same points on the LACC to proposed interconnection points on the Anderson–Orme 230-kilovolt (kV) transmission line.
SRP is currently working with ADOT to study the feasibility of a route or route segments on the east side of Loop 202. If, ultimately, the studies deem the east side of Loop 202 incompatible with transmission infrastructure, then Route S4 and Segments H-I-K would not be feasible. Accordingly, SRP’s CEC application identifies S5 Segment H-J-K as a contingent preferred segment in the event the route or route segments on the east side of Loop 202 are not feasible.
SRP’s Proposed Preferred Route Option
The map below is SRP’s proposed preferred route option with nodes (segments). The routes identified throughout the public process were further analyzed to select preferred routes for the Application. During the public and siting process, routing criteria was discussed, and agencies, stakeholders and the public weighed in on opportunities for siting transmission lines and constraints associated with the line routes. This input was used to help develop criteria to determine the preferred routes. The Project requires two transmission routes in each routing area. Ultimately, based on stakeholder and public input along with the routing criteria and analysis, SRP selected Preferred Routes as follows:
South Routing Area
Preferred Routes:
S2
S3 to Segment H-I-K
North Routing Area
Preferred Routes:
N2
N3
Contingent Preferred Segments:
S5 to Segment H-J-K
From the time of filing this Application to the time of the Arizona Power Plant and Transmission Line Siting Committee Hearing, SRP will continue to meet with agencies, stakeholders and the public and, based on these discussions, may include additional details and refined routing preferences in the Arizona Power Plant and Transmission Line Siting Committee Hearing.
New route option added to map
As we continue working with the landowners, stakeholders and members of the public, we are working on analyzing all possible route alternatives. Additional routes are being considered and would like to ensure we obtain feedback on all routing options in our upcoming open houses.
Proposed route map for September 2024 Open Houses (new routes proposed)
The map below identifies new proposed route alternatives for the 230 kV lines as well as other project components after incorporating public input during open houses and other stakeholder meetings.
Original proposed route map from May and June 2024 Open Houses
The map below identifies the route alternatives for the 230 kV lines, the location of the 500 kV transmission and new planned substation.
Transmission line structure types
Below are typical SRP transmission structure types. The structure types that will be used on this project are the 500kV 140’-160’ and 230/69kV 120’-160’ type structures.
News archive
The latest project news and announcements will be added here when available.
Contact us
If you have questions about the project, please call (602) 236-2872 or email 2872line@srpnet.com.
