Up for review at the Sept. 29 meeting of the California Public Utilities Commission is a draft order from a commission administrative law judge approving San Diego Gas & Electric for a certificate of public convenience and necessity for the Sycamore-Peñasquitos 230 kV Transmission Line Project.
The draft approval covers Alternative 5 (Pomerado Road to Miramar Area North Combination Underground/Overhead), which is subject to the mitigation measures identified in the Mitigation Monitoring and Reporting Plan. As the lead agency for environmental review, the commission would find and certify that the Environmental Impact Report prepared for this project meets the requirements of the California Environmental Quality Act and that the ability of the proposed project to mitigate thermal overloads and avoid North American Electric Reliability Criteria reliability violations and 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, and transportation and traffic.
The proposed project would install a new 230 kV transmission line that would replace existing, predominantly wood structures between the existing Sycamore Canyon and Peñasquitos Substations.
SDG&E asserted that the project is necessary to meet North American Electric Reliability Criteria (NERC), Western Electric Coordination Council, and California Independent System Operator reliability standards to avoid service interruptions. As SDG&E explained: “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. This imported energy then flows into the Miguel and Sycamore Canyon Substations, respectively. Heavy energy flows into these 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 these downstream facilities.”
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 project involves the following main components:
- Between Sycamore Canyon Substation and Carmel Valley Road (Segment A): installation of approximately 8.31 miles of new 230 kV overhead transmission line (TL) on 37 new double-circuit 230 kV tubular steel poles (TSP) replacing existing wood H-frame structures; and relocation and reconductoring of an existing 138 kV power line with partial undergrounding for approximately 850 feet where the 138 kV power line enters Sycamore Canyon Substation;
- Along a 2.84 mile segment of Carmel Valley Road (Segment B), installation of 230 kV underground TL between two new cable poles, and removal of one double-circuit lattice tower.
- Between Carmel Valley Road and Peñasquitos Junction (Segment C): installation of one new TSP and approximately 2.19 miles of overhead 230 kV conductor on existing double-circuit steel lattice towers; and reconductoring and bundling of two existing 230 kV TLs into one circuit on the same double-circuit steel lattice towers and new TSP. At Peñasquitos Junction—in the Del Mar Mesa Preserve—removal of one steel lattice tower;
- Between Peñasquitos Junction and Peñasquitos Substation (Segment D): installation of one new TSP and approximately 3.34 miles of overhead 230 kV conductor on existing double-circuit steel lattice towers; consolidation of two existing 69 kV power lines onto 17 new TSPs that would replace 15 existing wood H-frame structures and five wood monopoles; replacement of existing wood poles outside of Peñasquitos Substation with two TSPs; and removal of one existing 138 kV steel H-frame structure; and
- Minor modifications to Sycamore Canyon, Peñasquitos, San Luis Rey, Chicarita, and Mission Substations, and reconfiguration of 230 kV power lines at Encina Hub.
The EIR identifies Alternative 5 (Pomerado Road to Miramar Area North Combination Underground/Overhead) as the environmentally superior alternative. By undergrounding approximately 11 miles of overhead transmission line, Alternative 5 eliminates the need for tubular steel cable poles, conductors, marker balls, and retaining walls, preserving open space areas including within Black Mountain Ranch Community Park.
SDG&E testified, and no party contested, that the estimated cost of the proposed project, configured as Alternative 5, is $259,670,632, including $41,882,360 in contingency.