Southern California Edison has begun rebuilding the historic Mesa Substation located along Potrero Grande Drive in south Monterey Park.
The new, bigger and more powerful substation would be located at the existing Mesa Substation site but would result in a tripling in size of the 69.4-acre footprint expanded from the current 21.6-acre footprint. Estimated cost of the project is $608 million.
According to a project description by the California Public Utilities Commission, the project includes removal, relocation, modifications and construction of a transmission, sub-transmission power lines within SCE-owned properties, in Monterey Park as well as the neighboring cities of Montebello, Monterey Park and areas of unincorporated L.A. County.
According to an Edison factsheet, SCE is rebuilding the Mesa Substation Project “to ensure that the electric grid will continue to serve the needs of its customers in the region.”
Upgrading the existing Mesa Substation and connecting existing transmission lines to the substation will address future reliability concerns related to the projected retirement of older coastal power plants and the previous retirement of the San Onofre Nuclear Generating Station (SONGS), without requiring new transmission lines or substations
Construction of the new 500/220/66/16-kV substation and demolition of the existing 220/66/16-kV substation would occur in phases.
Phase 1 now underway would consist of grading and initial site development on the western portion of the project site. Phase 2 would consist of construction of the first half of the new Mesa Substation. During Phase 1 and 2, the existing substation on the eastern portion of the site would remain operational in order to maintain electrical service to customers during construction.
Phase 3 would consist of demolition of the existing substation and construction of the second half of the new substation on the eastern portion of the site. Construction of the Mesa Substation Project began in early 2017 and would take approximately 4.5 years to complete.
Detailed information can be found in the project Environmental Report that is available at the Monterey Park Bruggemeyer Library.