Frequently Asked Questions

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San Diego Gas and Electric (SDG&E) has identified that the Proposed Project is needed to meet state environmental and energy policy goals, and to ensure the bulk power system is in compliance with applicable North American Electric Reliability Corporation (NERC), Western Electric Coordinating Council (WECC) and California Independent System Operator (CAISO) transmission planning criteria.

According to SDG&E, closure of the San Onofre Nuclear Generation Station (SONGS) constrains SDG&E’s ability to reliably and efficiently provide energy to customers in the area. SDG&E’s bulk electric transmission system serving the San Diego metropolitan area currently has three major gateways for energy that is imported to serve customer load. These include the Miguel 500/230-kV Substation, the Sycamore Canyon 230-kV Substation, and Path 44, which is composed of three 230-kV lines from the SONGS Switchyard to the San Luis Rey Substation and two 230-kV lines from the SONGS Switchyard to the Talega Substation. While the Proposed Project would not replace SONGS, it would increase reliability of the transmission system between the Sycamore and Peñasquitos Substations.

The locations for existing poles that will be removed and preliminary locations of new poles that will be installed are shown in the detailed route maps provided as Appendix 3-B of SDG&E’s Proponent’s Environmental Assessment, which begins on page 29 of the PEA Appendices (available here). Note that the locations of new installed poles may change as SDG&E refines their project design. The Draft EIR will evaluate any and all alternatives, including possible relocations of any poles that are proposed to be installed by SDG&E. The locations of SDG&E’s proposed new poles and any alternative pole locations will be identified in the Draft EIR.

SDG&E has identified transmission line spans where marker balls are currently anticipated based on proposed structure heights and the distance between the power line and an airport. The potential locations requiring marker balls are currently being reviewed by the CPUC through coordination with the Federal Aviation Administration (FAA) and Marine Corps Air Station (MCAS) Miramar. FAA regulations require notification and evaluation of air navigation hazards for any structures taller than 200 feet or within 20,000 feet of an airport. The FAA will determine the locations of marker balls and lighting based on their evaluation of air navigation hazards. MCAS Miramar may have additional requirements for marker balls. The Draft EIR will include detailed project maps indicating locations where marker balls are anticipated pending final approval by the FAA and MCAS Miramar.

There are currently two 138-kV transmission lines within the Segment A corridor of the Proposed Project, one 138-kV and two 230-kV transmission lines in the Segment C corridor, and one 230-KV and two 69-kV transmission lines in the Segment D corridor. There are no existing transmission lines in the Segment B corridor along Carmel Valley Road. The Proposed Project would add a new double circuit 230-kV transmission line in the corridors. Approximately 1,400 megawatts of power would flow along the new transmission line.

The Proposed Project includes the installation of a double circuit 230-kV transmission line. For three-phase systems, such as the Proposed Project, each tower supports six conductors (wires). Thus, the Proposed Project would add six conductors along the entire alignment (Segments A through D; Segment B would be located underground).

The existing H-frame wooden poles only hold one single circuit transmission line. Because the Proposed Project would add an additional double circuit transmission line, the wooden poles would not be sufficient. The new steel poles would hold both circuits.

The Draft EIR should be available in late Spring 2015. However, the Draft EIR may be released later in the year if the CPUC does not receive all of the data needed by stated deadlines to fully analyze the environmental impacts of SDG&E’s proposal.

At this time, it is unknown whether undergrounding the entire, or segments of, the Proposed Project would be feasible. Feasibility of any viable alternatives, including undergrounding, will be addressed in the Alternatives Screening Report. The report will analyze: (1) how well each alternative, including undergrounding, meets most or all project objectives; (2) the technical, economic, legal, regulatory and environmental feasibility factors; and (3) the potential to avoid or lessen any of the significant impacts of the Proposed Project. The report will be released with the Draft EIR.

The Draft EIR will analyze visual impacts of the Proposed Project, including views from homes. The report will include visual simulations from Key Observation Points, or KOPs. KOPs are points on a traveled route, at an existing or potential use area, where the view of an activity (the Proposed Project) would be most obvious and representative to a key viewing group (e.g., community or neighborhood viewers). While not every home located near the Proposed Project can be a KOP, the KOPs will be placed strategically so that views from a variety of neighborhoods will be simulated.

Impacts to property value are not required to be evaluated under CEQA and therefore will not be included in the Draft EIR. However, factors that may affect property value, such as visual impacts, will be analyzed and presented in the Draft EIR.

The magnetic field levels along the ROW from existing transmission lines and the Proposed Project were modeled by SDG&E. The values calculated in an EMF model represent the magnetic field for a 2017 peak summer use and represent one snapshot in time. The current flowing over transmission lines continuously vary, both over the course of a day, as well as over the decades the transmission line will be in service. Since the amount of electricity usage in the community varies over the course of the day, depending upon the use of appliances, lighting, and other sources, the current flowing on the transmission line and the associated magnetic field vary. The periods during the day when the highest power use occurs are referred to as “daily peaks.” The model uses a daily peak during a peak summer day to estimate EMF levels resulting from the project. Values calculated from an EMF model will be presented in the Draft EIR. The EMF model allows for evaluation of the effectiveness of various magnetic field reduction measures. As stated in CPUC Decision D.93-11-013, the CPUC requires that utilities use “low-cost or no-cost” mitigation measures for facilities requiring certification under General Order 131-D.4. SDG&E would implement low- and no-cost measures to reduce magnetic field levels for the Proposed Project using the 4 percent CPUC benchmark and SDG&E’s EMF Design Guidelines for Electrical Facilities filed with the CPUC in compliance with CPUC Decisions D.93-11-013 and D.06-01-042. SDG&E has described these measures in the Field Management Plan, which was submitted as Appendix H of its application for a CPCN (available here). If the Proposed Project or an alternative is approved, the CPUC would monitor implementation of the measures included in SDG&E’s Final Field Management Plan.

It is not currently known whether corona noise will increase as a result of the Proposed Project. The effects of audible corona noise will be evaluated in the Draft EIR. There are not currently any devices that are known to mitigate for corona noise. Audible corona noise is a function of conductor design and configuration. Changing the Proposed Project’s design and configuration would likely trigger other environmental impacts (e.g., taller towers would impact visual resources). Corona noise is also affected by the condition of the conductor and insulators. Proper handling of conductors during construction to avoid damage, and repair of damaged conductors, insulators, or other hardware can help minimize corona noise. The Draft EIR will address possible techniques to mitigate for corona noise. CEQA requires that all reasonably foreseeable projects must be evaluated to analyze cumulative impacts of the Proposed Project. If any reasonably foreseeable transmission line projects near the Proposed Project are identified, the Draft EIR will analyze the cumulative corona noise impact from both projects.

The Proposed Project will not increase radio interference.

Temporary trail closures may occur where trails are located in close proximity to construction areas to provide a safety buffer between recreational users and construction areas. Temporary trail detours will be provided where feasible. Signs will be posted to direct trail users to temporary detours.

The staging yards that would be used during the Proposed Project have not yet been finalized by SDG&E as several of the staging yards in the PEA have been deemed infeasible. Proposed staging yards (with site control verification) will be included in the Draft EIR.

There will not be any additional mailers for the Proposed Project at this time. However, the public will be notified when the Draft EIR is released for review and comment and where and when public workshops will be held for the Draft EIR.