Southern California Edison Company (SCE) proposes to build the Devers- Mirage 115 Kilovolt System Split Project (Proposed Project) to maintain electric system reliability, enhance operational flexibility, and serve projected electrical demand in the cities of Palm Springs, Rancho Mirage, Cathedral City, Palm Desert, Indian Wells and unincorporated areas of Riverside County, including the community of Thousand Palms (Project Area). Construction is scheduled to begin in the second quarter of 2009 following the receipt of all project approvals and to be completed by mid-2010.

The Proposed Project includes the following primary components, which are described in more detail on the project fact sheet in the "Project Description" section:

• Construct a new 115 kilovolt subtransmission line from the Mirage Substation south to Interstate 10, adjacent to the east side of Tri-Palms Estates and within SCE’s existing right-of-way and public streets.
• Replace an existing single-circuit with a double-circuit 115 kilovolt subtransmission line in Palm Springs from Farrell Substation, located at Gene Autry Trail and Vista Chino Drive, to the Garnet Substation, located near the intersection of Indian Avenue and Garnet Avenue within SCE’s existing right-of-way and public streets.
• Loop the existing Devers-Coachella Valley 220 kilovolt transmission line from an existing right-of-way for approximately 0.8-miles on double-circuit lattice towers to Mirage Substation (install eight lattice steel towers and remove four lattice steel towers).
• Install one new tubular steel pole near Mirage Substation.
• Install an additional 280 megavolt ampere-220/115 kilovolt transformer at Mirage Substation.
• Install additional equipment and relays at certain substations located within the Project Area.

Why is this project needed?

The Electrical Needs Area is currently served by an electrical system of interconnected substations and 115 kV subtransmission lines called the “Devers 115 kV Subtransmission System.” However, this electrical system is becoming overloaded beyond its ability to carry enough electricity to meet SCE’s customer requirements, especially during peak electrical demand periods. The Proposed Project would relieve overload conditions on existing 115 kV lines and reconfigure the existing Devers 115 kV Subtransmission System into two separate subtransmission systems (Devers 115 kV Subtransmission System and the Mirage 115 kV Subtransmission System). Splitting this system into two separate systems would enable SCE to continue to provide safe and reliable service to SCE’s customers.

The Proposed Devers-Coachella Valley 220 kV Loop-in at Mirage Substation would help mitigate possible 220 kV system voltage problems after the two separate subtransmission systems are created as part of the Proposed Project.