CPUC grants SCE permit to build 500-kV substation project

The California Public Utilities Commission (CPUC), in a decision dated Feb. 9, and issued on Feb. 16, granted Southern California Edison (SCE) a permit to build the Mesa 500-kV Substation Facility Project, with certain mitigation.

As noted in the order, SCE in March 2015 submitted its application for a permit to construct (PTC). The CPUC said that the project consists of these main components:

  • Construction of the new 500/220/66/16-kV Mesa substation and demolition of the existing 220/66/16-kV substation, increasing the substation’s footprint from about 22 acres to 69 acres
  • Removal, relocation, modification, and/or construction of transmission lines, subtransmission, distribution, and telecommunication structures to accommodate the new 500/220/66/16-kV Mesa substation within existing SCE-owned properties, rights of way (ROWs), and franchise areas located in the cities of Monterey Park, Montebello, Rosemead, South El Monte, and Commerce, as well as in portions of unincorporated Los Angeles County
  • Installation of a temporary 220-kV transmission structure to connect the Eagle Rock-Mesa 220-kV Transmission Line to the Goodrich substation and maintain a second line of service to the City of Pasadena
  • Replacement of an existing 220-kV double-circuit transmission structure supporting the existing Goodrich-Laguna Bell (future Laguna Bell-Mesa Number (No.) 1) and Mesa-Redondo 220-kV Transmission Lines in order to increase the capacity rating of the future Laguna Bell-Mesa No. 1 (220-kV) Transmission Line
  • Relocation of an existing 72-inch Metropolitan Water District of Southern California (MWD) waterline that traverses the substation location
  • Decommission 10 existing groundwater monitoring wells located within the substation site that are administered by the U.S. Environmental Protection Agency
  • Electrical and/or telecommunications equipment upgrades at 27 existing substations
  • Undergrounding of three spans of overhead streetlight conductors within the City of Bell Gardens
  • Minor internal equipment replacement and upgrades within the perimeter of 27 existing substations operated by SCE within the company’s service area

The project will result in five significant and unavoidable impacts in the resource areas of aesthetics, air quality, and noise, the CPUC said. An environmental impact report (EIR) determined that the project would have no impact or a less than significant impact on the resource areas of greenhouse gases; land use and planning; as well as population, housing and recreation. The CPUC also said that the project will result in impacts that can be mitigated to a less than significant in the remaining resources areas of biological; cultural and paleontological; geology, soils and minerals; hazards and hazardous materials; hydrology and water quality; public services and utilities; as well as traffic and transportation.

The EIR screened nine project alternatives and determined that three of the alternatives should be carried forward for full analysis in the EIR because they meet certain requirements. As noted in the final EIR (FEIR), the CPUC added, the “One-Transformer Bank Substation” alternative is considered the most environmentally superior alternate in seven resource areas and is therefore considered environmentally superior to all alternatives and the proposed project.

The “One-Transformer Bank (1600 megavolt amperes (MVA)) Substation” alternative involves building the project as proposed, but using one 1600-MVA 500/220-kV transformer bank with space for a spare transformer bank.

The CPUC also said that the proposed project would enable SCE to:

  • Address anticipated violations of NERC Standard TPL-001-04 (NERC 2015), Western Electricity Coordination Council (WECC) Regional Business Practice TPL-001-WECC-RBP-2 (WECC 2011), and California ISO (Cal-ISO) planning standards that would occur by Dec. 31, 2020, of generators that use “once-through cooling” (OTC)
  • Avoid introduction of new violations of NERC, WECC, and Cal-ISO standards
  • Maintain electrical service by minimizing service interruptions during the project

The CPUC said that having adopted all feasible mitigation measures, recognized all significant, unavoidable impacts, and balanced the benefits of the project against its significant and unavoidable impacts, the commission finds that the project’s benefits outweigh and override its significant unavoidable impacts.

Based on the testimony of SCE, as supported by the Cal-ISO, the CPUC said that it finds that the FEIR alternatives are infeasible because they result in reliability concerns, cause significant delays in scheduling and facilitating OTC retirement, and are likely to be as costly or more costly than the proposed project.

The proposed project will provide an additional point of 500-kV service into SCE’s metropolitan load center, and it is needed to facilitate OTC retirement requirements by Dec. 31, 2020, as well as to address anticipated NERC, WECC, and Cal-ISO violations that could occur upon the retirement of generators using OTC. The CPUC added that the project will allow for greater flexibility in siting future generation projects to meet local reliability needs in the Western Los Angeles Basin, while reducing new generation requirements by providing additional transmission import capability.

The CPUC further noted that the One Transformer Alternative includes a “remedial action scheme,” or RAS, and that upon the loss of two transmission lines, the RAS will open two other transmission lines in the Serrano Corridor, resulting in the loss of four transmission lines that serve the Western L.A. Basin, and will degrade system reliability by making the system less likely to withstand the next contingency. The proposed project with three 1120 MVA transformer banks does not require an RAS, the CPUC said.

SCE estimates that the project can be built in 48 months, with a potential operational date of June 2021. While the OTC retirement compliance requirement date is Dec. 31, 2020 for generating plants in SCE’s service territory, the system reliability concern does not become critical until the following summer peak loading period, June 1, 2021, the CPUC added. Consequently, to timely retire gas-fired generation subject to the OTC policy, the project must be energized before summer 2021. The FEIR alternatives result in unreasonable delay to completion due to the redesign and engineering work involved, the CPUC said.

Among other things, the mitigation measures call for SCE to prepare a monthly environmental compliance report for the CPUC, and if a project change would create or have the potential to create a new significant impact, increase the severity of an impact, or occur outside of the geographic area evaluated in the EIR, then SCE would be required to submit a petition for modification.

SCE is a subsidiary of Edison International (NYSE:EIX).

About Corina Rivera-Linares 3286 Articles
Corina Rivera-Linares was TransmissionHub’s chief editor until August 2021, as well as part of the team that established TransmissionHub in 2011. Before joining TransmissionHub, Corina covered renewable energy and environmental issues, as well as transmission, generation, regulation, legislation and ISO/RTO matters at SNL Financial from 2005 to 2011. She has also covered such topics as health, politics, and education for weekly newspapers and national magazines.