Questions and Answers

Q: “What is SDG&E’s South Orange County Reliability Enhancement?”

A: The upgrade primarily consists of:

  • Rebuilding the substation in San Juan Capistrano

  • Upgrading the transmission lines from the 138kV and 12kV to 230kV in order to provide for the electric reliability needs of the residents and businesses in South Orange County.

  • Replace select wood, steel and lattice towers with taller new steel fire resistant poles in order to enhance safety and reliability and provide more uniformity of structures in the transmission corridor.

  • Upgrade the Talega Substation in San Clemente

Q: “Why does South Orange County need an electric reliability upgrade project?”

A: While the Orange County population has grown by approximately 50 percent over the last 26 years, electrical use in South Orange County has tripled over that same amount of time.  In the early 1980’s, the typical South Orange County resident had one or two television sets, a stereo and maybe one computer.  Now, most residents have several entertainment centers with flat-screen TV’s, DVD’s DVR’s, along with several computers, video gaming systems, iPads, iPods, iPhones and other electronic gadgets that need electric power.  As we look to the future, we anticipate an even greater need for electric reliability and SDG&E is committed providing that power in a safe and reliable way.

Q: “What is the location of the project?”

A: SDG&E’s South Orange County Reliability Enhancement will upgrade the electrical infrastructure from the substation at Talega in San Clemente, all along the transmission corridor, to the substation in San Juan Capistrano off of Camino Capistrano.  A project map is available online at The vast majority of this upgrade project will be constructed on SDG&E owned land or existing Right of Way.

Q: “Reliability hasn’t seemed to be a problem in the past.  Why does SDG&E say reliability needs to be improved?”

A: While residents in South Orange County experience few outages, the current 138kV transmission system serving the area would be better served by the proposed 230kV system as it would allow for more capacity and switching capability.  At times, these existing transmission lines are running near capacity.  That leaves little room for a sudden increase in load such as on a hot day when air conditioners are running high or if there is a sudden loss of a transmission line.  The Capistrano Substation was built more than 60 years ago.  As with all aging infrastructure, replacement and upgrading is crucial for reliability.  You can only “tune-up” your car so many times; the same with equipment like switches, fuses, transformers, and capacitor banks.  Replacing parts over years will extend the life of the substation, but not forever.  Adding capacity to this substation is also necessary to be able to meet future load needs in South Orange County based on locally approved plans and projections.

Q: How, when and why will the rebuild of the San Juan Capistrano Substation occur?

A: The San Juan Capistrano Substation was first built in 1918 and renovated by SDG&E in the 1950’s.  It has served its purpose admirably for the last six decades, but is in serious need for an upgrade to continue providing safe and reliable power to the community. 

One of the challenges to rebuilding the substation is to keep reliable power in operation throughout the process.  It is akin to rebuilding your house without moving out!

Unlike today, the new substation will be in an enclosed building.  Once the project permits have been approved, SDG&E will demolish sections of the old substation and begin constructing a building to house the new substation.  Once the new building is completed, the substation will be built inside.

SDG&E estimates it will take about six months for the demolition and grading of the property. SDG&E will then construct the building that will house the new 138kV substation.  It will take another 18 months to 2 years to build the new substation inside the new building.  Because the construction of the building will happen first, the noise and dust created by the construction of the new substation will be significantly less.

After the new 138kV substation is complete and in operation, work will continue for the construction of the new 230kV substation. The old 138kV substation will be demolished and the area will be graded. The new building to house the new 230kV substation will be constructed and the new substation will be built inside. This work will take approximately 2 years.

Q:What changes will be made to the SDG&E poles and lines that exist in the transmission corridor between the Talega Substation and San Juan Capistrano Substation?”

A: First, it’s important to understand that not all of the power lines and poles within the transmission corridor are SDG&E’s.  About half of those lines and poles belong to Southern California Edison and transmit power to their service area in Central Orange County and beyond. 

Second, the SDG&E poles and 138kV lines were installed in the 1980’s.  Since then our need for safe and reliable electric power has tripled.  The new 230kV lines add greater electric capacity making power outages less likely.  Additionally, SDG&E will utilize uniform steel poles along the corridor, which currently has a mixture of wood poles, steel poles and steel lattice towers.  Although SDG&E will not renovate the Southern California Edison structures, SDG&E’s new steel poles will be “soldiered” with the existing steel structures in the corridor, to the extent possible.  That means the poles will stand side-by-side in an effort to “clean up” the corridor from a visual perspective.  Approximately 144 structures will be removed and 69 engineered structures will be installed (net reduction of 75 structures).


Q: “Why can’t SDG&E underground the transmission lines?”

A: There are engineering, maintenance, environmental and economic challenges to undergrounding transmission lines. 

230kV lines are capable of carrying large amounts of electric current and generate a great deal of heat, which makes undergrounding the transmission lines for an extended length very difficult from an engineering perspective.  The heat in an underground electric system results in a greatly reduced operating limit, or reduced capacity.

When placed underground, maintenance becomes more difficult as line-workers for SDG&E have to test the lines to determine where the line failure occurred, and would potentially need to dig down to the facilities to repair them.  If failure occurs on the cable or connections, the amount of time to repair those elements takes substantially longer than repairs on overhead line elements.  Depending on the extent of the failure, repairs could take weeks instead of days.  These issues add to both the cost of maintenance as well as the speed for system recovery in case of an outage.

Any undergrounding excavation requires additional environmental permits.  Undergrounding power lines can potentially impact species as well as water quality impacts from soil erosion and other environmental challenges.

Finally, the cost of undergrounding power lines is exponentially higher than the cost of standard above ground transmission line connections, especially for 230kV. 

For these reasons, SDG&E’s South Orange County Reliability Enhancement plans to replace one of the existing above-ground electric transmission lines with an improved modern above-ground electric transmission system with the exception of a short stretch in San Juan Capistrano, where the existing transmission line is underground today.

Q: “How long will the project take to complete?”

A: “The permitting process will take about 18 months to 2 years and the construction of the project will take about four to five-years. 

After three years of undergoing technical feasibility studies, the California Independent System Operator (CAISO) agreed that the project is needed and gave permission for SDG&E to file an application with the California Public Utilities Commission (CPUC). 

In the second quarter of 2012, SDG&E will file its application to proceed with the project.  SDG&E will conduct extensive community outreach to obtain public input about the project and conduct all necessary environmental analysis of the project as required under state and federal law.

The draft Environmental Impact Report (EIR) is expected to be available for public review in the 2nd or 3rd quarter of 2013.  The final EIR is expected to be certified in the 3rd or 4th quarter of 2013.  CPUC approval is anticipated in the fourth quarter of 2013.

Once the CPUC approves the project, construction may begin.  The new project will be built and activated before the existing infrastructure is decommissioned so that SDG&E customers will not have an interruption in power due to the project.

The demolition and grading certain sections of the San Juan Capistrano Substation will occur so that the new building can be built.  Within six months or so, SDG&E will begin constructing the new substation inside the new building.

The power poles and lines along the transmission corridor will be phased so that the removal of the old structures and the installation of the new poles and lines will be done in a way that has as little impact on the local community as possible.

The community will be notified prior to any significant construction effort that occurs.

Q: “If reliability is such a concern for SDG&E, why did the company wait this long to propose this project?”

A:  SDG&E was aware of these issues and has been working on this project for a number of years in order to optimize the design, minimize environmental impacts and meet the forecasted load growth.  The timing of this project will correspond with existing load growth in the area, and was approved by the CAISO in May 2011, the appropriate Transmission Planning window.

Q: “If this project would have been completed prior to September 8, 2011, would it have prevented the system-wide blackout?”

A: SDG&E’s system, like other utilities, is designed to withstand the loss of the single largest transmission line and the single largest generating unit.  The initial transmission event on Sept. 8 in Arizona triggered the sequence of events that led to wide-spread outages in the Pacific Southwest region, including San Diego.  Due to the loss of subsequent portions of other control areas, SDG&E’s system was stressed beyond this initial event.  While the South Orange County Reliability Project would not have prevented the widespread outage, if in place, it would have assisted in restoration efforts and will significantly reduce the risk of smaller outages from occurring.

Q: “Is SDG&E meeting NERC, WECC and CAISO standards today?  If so, what is the need to do this project?”

A: Yes, SDG&E is in compliance with all applicable NERC, WECC and CAISO reliability standards.  However, as the load continues to grow in the area the existing system will reach its capacity.  This project will allow SDG&E to reliably serve the Orange County load and maintain compliance with these standards in the future.

Q: “It takes an average of 18-24 months to build a substation.  Why will it take SDG&E five full years to construct this substation?”

A: SDG&E needs to keep the current 138/12kV substation operational the entire time it is being rebuilt.  Once the new 138/12kV substation is operational, the old facility will be torn down and a new 230kV substation will be erected in its place.

Q: “What will be done for the residents near the Capistrano Substation?  To have to endure five long years of construction is preposterous.”

A: SDG&E will make every effort to keep dust and noise levels down.  The heaviest and loudest equipment will be used in stages for grading and below grade work of each of the substation facilities that will be built. 

Q: “Will SDG&E be condemning any homes near the Capistrano Substation?”

A: No, SDG&E’s goal with this project is to minimize environmental and residential impacts, which is why we are using the existing ROW and existing Capistrano Substation to complete this project.

Q: “What will SDG&E do to minimize the appearance of the 45-foot tall substation?”

A: SDG&E plans to partner with the community and surrounding residents to improve the aesthetics and to ensure the finished project will be acceptable to those affected.

Q: How tall will the transmission structures be?

A:  The transmission line design has not been finalized at this point in time, but the structures will generally be the same height as the steel structures currently in the corridor (SDG&E and Edison).  The typical structure height will be somewhere between 140’ – 180’.

Q:  What color will the transmission structures be?

A:  The structures will be galvanized with a dulled finish.  The dulling process takes away the shiny appearance generally seen on galvanized structures.

Q: “How much will this project cost and who will pay for it?”

A: The total cost for the project will be approximately$450 to $500 million.  The upgrade will have significant economic benefits to the local economies of both San Clemente and San Juan Capistrano with SDG&E employees and contract workers using the restaurants, hotels, gas stations and other businesses and services throughout the life of the five-year project.  

Because a significant portion of the project involves the installation of transmission lines greater than 200kV, 45% of the project is paid for equally by electric ratepayers throughout California.  SDG&E ratepayers are just 10% of that total number.

The remaining 55% of the project is paid for by SDG&E’s 1.4 million ratepayers.  It should be noted that this project has been planned for many years and this electric reliability project is part of SDG&E’s standard utility upgrade budget.

In the simplest of terms, the project will impact in SDG&E’s rates by about 1% or one penny on every dollar.

Q: “With higher voltage transmission lines, will the Electric Magnetic Field (EMF) increase for those residents in communities along the eight-mile route?”

A: Public concern and uncertain science have led policy-makers to consider “precautionary measures” to limit exposure when that precaution can be attained for little or no cost.  This is the thinking behind the California Public Utility Commission’s (CPUC) EMF policy of “no and low-cost field reduction measures on new powerline construction in California.  Recently the CPUC reviewed the EMF research and reaffirmed that these measures are still appropriate.

The CPUC requires utilities to consider "no-cost" and "low-cost" magnetic field management techniques on all new transmission projects as a precautionary measure to reduce public exposure to magnetic fields.  SDG&E will implement magnetic field reduction techniques on this project, as appropriate, in accordance with SDG&E's EMF Design Guidelines for Electrical Facilities (Guidelines), as filed with the CPUC in compliance with Decision 93-11-013 and updated in compliance with Decision 06-01-042.

SDG&E will take the following measures for this Project: 

  • Identify and implement appropriate “no-cost” measures, i.e., those that will not increase overall project costs but will reduce the magnetic field levels.

  • Identify and implement appropriate “low-cost” measures, i.e., those measures costing in the range of 4% of the total budgeted project cost.  

To qualify, "low-cost" measures must reduce the magnetic field levels by at least 15% at the edge of Right-of-Way (ROW). 

Q: “By converting the smaller 138/12kV air-insulated substation to a much larger 230/138/12kV indoor-insulated substation, what added environmental risks are those nearby residents going to be exposed to?  What about SF6?  Some claim those levels will increase?”

A: Sulfur Hexafluoride (SF6) is an inert gas used industry wide for high voltage circuit breaker technology.  The gas is currently used at Capistrano Substation and must be used for either an indoor substation or an outdoor substation.

However, to allow for a smaller overall footprint for the 230/138/12kV equipment to fit on the existing substation site, more SF6 is required than at a comparable outdoor substation at other sites.