The California Public Utilities Commission (CPUC), in a decision dated Oct. 13 and issued on Oct. 19, granted San Diego Gas & Electric (SDG&E) a certificate of public convenience and necessity for the Sycamore–Peñasquitos 230-kV Transmission Line Project, configured with “Alternative 5 (Pomerado Road to Miramar Area North Combination Underground/Overhead),” and subject to certain mitigation measures.
The CPUC said that it finds that the environmental impact report (EIR) prepared for the project meets the requirements of the California Environmental Quality Act (CEQA) and that the ability of the proposed project to mitigate thermal overloads and avoid NERC reliability violations, as well as to facilitate the delivery of renewable energy to San Diego, are overriding considerations that outweigh its significant and unavoidable impacts on aesthetics, air quality, noise, transportation and traffic.
As noted in the order, the project would install a new 230-kV transmission line that would replace existing, predominantly wood structures between the existing Sycamore Canyon and Peñasquitos substations.
The project involves these main components:
- Between the Sycamore Canyon substation and Carmel Valley Road (Segment A): installing about 8.31 miles of new 230-kV overhead transmission line on 37 new double-circuit 230-kV tubular steel poles replacing existing wood H-frame structures; and relocating and reconductoring an existing 138-kV power line with partial undergrounding for about 850 feet where the 138-kV power line enters the Sycamore Canyon substation
- Along a 2.84-mile segment of Carmel Valley Road (Segment B): installing 230-kV underground transmission line between two new cable poles, and removing one double-circuit lattice tower
- Between Carmel Valley Road and the Peñasquitos Junction (Segment C): installing one new tubular steel pole and about 2.19 miles of overhead 230-kV conductor on existing double-circuit steel lattice towers; and reconductoring and bundling two existing 230-kV transmission lines into one circuit on the same double-circuit steel lattice towers and new tubular steel poles. At the Peñasquitos Junction – in the Del Mar Mesa Preserve – removing one steel lattice tower
- Between the Peñasquitos Junction and Peñasquitos substation (Segment D): installing one new tubular steel pole and about 3.34 miles of overhead 230-kV conductor on existing double-circuit steel lattice towers; consolidating two existing 69-kV power lines onto 17 new tubular steel poles that would replace 15 existing wood H-frame structures and five wood monopoles; replacing existing wood poles outside of the Peñasquitos substation with two tubular steel poles; and removing one existing 138-kV steel H-frame structure
- Minor modifications to the Sycamore Canyon, Peñasquitos, San Luis Rey, Chicarita, and Mission substations, and reconfiguring 230-kV power lines at the Encina Hub
According to SDG&E, the project is needed to meet NERC, Western Electric Coordination Council and California ISO reliability standards to avoid service interruptions. The company noted that during periods of high customer demand and high energy imports, as well as during periods of high renewable energy generation in the Imperial Valley, most of the energy imported in San Diego flows across the 500-kV Southwest Powerlink and Sunrise Powerlink transmission lines. That imported energy, the company added, then flows into the Miguel and Sycamore Canyon substations, respectively. Heavy energy flows into those gateway substations can result in congestion and NERC reliability criteria violations on the 230-kV, 138-kV, and 69-kV transmission and power lines downstream, requiring dispatch of less efficient generation, increasing energy cost for ratepayers and eventually requiring upgrades to those downstream facilities, the company said.
The project will allow energy to flow directly from the Sycamore Canyon substation almost directly to the approximate San Diego load center, instead of forcing the energy to flow there directly through the existing 69-kV and 138-kV networks, thus, mitigating thermal overloads and avoiding NERC reliability violations, and facilitating the delivery of renewable energy to San Diego, the CPUC added.
The project would have significant and unavoidable impacts on aesthetics over its long-term presence due to visual contrast arising from the removal of vegetation, the construction of access roads and retaining walls, the presence of transmission structures, lighting, and Federal Aviation Administration (FAA) required marker balls, and long-term glare from specular conductor and steel poles.
The project would also have significant and unavoidable impacts on recreation during construction due to the temporary closure of public recreation areas, the CPUC added.
Noting that the EIR identifies Alternative 5 as the environmentally superior alternative, the CPUC said that by undergrounding about 11 miles of overhead transmission line, that alternative eliminates the need for tubular steel cable poles, conductors, marker balls, and retaining walls, preserving open space areas, including within the Black Mountain Ranch Community Park.
Discussing electric and magnetic field (EMF) impacts, for instance, the CPUC noted that since there is no agreement among scientists that exposure to EMF creates any potential health risk, and since the CEQA does not define or adopt any standards to address the potential health risk impacts of possible exposure to EMFs, the CPUC does not consider magnetic fields in the context of CEQA and the determination of environmental impacts.
However, recognizing that public concern remains, the CPUC said that it requires that all requests for a permit to build include a description of the measures taken or proposed by the utility to reduce the potential for exposure to EMFs generated by the proposed project.
SDG&E’s magnetic field management plan (MFMP) provides that the company will adopt the no-cost measures of locating power lines closer to center of the utility corridor to the extent possible, increasing structure height of new structures in Segment A, and phasing circuits to reduce magnetic fields.
“We find that this design complies with the commission’s EMF decisions, and order SDG&E to apply it to the approved Sycamore–Peñasquitos 230 kV Transmission Line Project, configured as Alternative 5,” the CPUC added.
Among other things, the CPUC said that according to SDG&E, the estimated cost of the project, configured as Alternative 5, is about $259.7m, including about $41.9m in contingency. The CPUC added that it concludes that that is a reasonable and prudent maximum cost for the facility.
SDG&E is a Sempra Energy (NYSE:SRE) utility.