V. EMF Issues
The Commission first established EMF policies in D.93-11-013. In our recent review of EMF issues, the Commission stated in D.06-01-042 that, "at this time we are unable to determine whether there is a significant scientifically verifiable relationship between EMF exposure and negative health consequences." We affirmed in D.06-01-042 that the Commission's EMF policy is one of prudent avoidance, with application of low-cost/no-cost mitigation measures to reduce EMF exposure for new and upgraded utility transmission and substation projects. The Commission has adopted a benchmark of 4% of total project cost for low-cost EMF mitigation measures, with flexibility to allow expenditures above the 4% benchmark if justified by a project's unique circumstances. In D.06-01-042, the Commission stated that, as a guideline, low-cost EMF mitigation measures should reduce EMF levels by at least 15% at edge of the utility right of way.
The Final EIR/EIS provides information regarding EMF associated with DPV2. It does not consider magnetic fields18 in the context of CEQA or NEPA and the determination of environmental impacts because there is no agreement among scientists that EMF creates a potential health risk and because there are no defined or adopted CEQA or NEPA standards for defining health risk from EMF.
A. EMF Along Routes Under Consideration
Along the edge of the right of way for the existing DPV1 line, magnetic fields currently range from 8.3 milliGauss (mG) in Riverside County near Thousand Palms to 72.9 mG in Copper Bottom Pass in the Dome Rock Mountains in Arizona. With the addition of DPV2 along the Devers-Harquahala segment, field levels are expected to be reduced between 0.8 and 37.9 mG on the side of the right of way where the existing DPV1 line is located. On the side of the right of way where the new line would be installed, magnetic field levels would increase up to 30.0 mG.
Alternative route segments evaluated for the Devers-Harquahala line are all 500 kV and, if the alternative is adjacent to an existing 500 kV circuit, they would involve field levels similar to those for the proposed Devers-Harquahala route. For alternatives that would require a 500 kV line in a new corridor, magnetic field levels would range between 11.2 and 46.5 mG at the edge of the right of way.
For the 230 kV transmission lines proposed to be upgraded west of the Devers substation, existing magnetic fields at the edge of the right of way range from 4.1 mG in Grand Terrance to 38.5 mG in the Loma Linda area. If the 230 kV upgrades were constructed, field levels would be reduced at the edge of the right of way between 1.0 and 18.1 mG below the existing levels.
The Devers-Valley No. 2 500 kV alternative would be constructed adjacent to the existing Devers-Valley No. 1 500 kV line. Baseline magnetic fields range between 14 and 63 mG at the edge of the right of way. With installation of the second transmission line, magnetic fields would increase between 22 and 28 mG on the side where the new line would be installed and fields would decrease between 16 and 19 mG on the side where the existing line is located.
B. EMF Management Plan for DPV2
SCE states that it has incorporated low-cost and no-cost measures to reduce magnetic fields along the proposed DPV2 route. For the 500 kV Harquahala-Devers line, SCE proposes to optimally phase the DPV2 line with DPV1, as a no-cost EMF mitigation measure. With optimal phasing, adding the DPV2 line to the DPV1 corridor will increase magnetic fields on the side of the right of way adjacent to the new line and decrease magnetic fields on the other side of the right of way as described above. However, the proposed optimal phasing would reduce the fields compared to what they would be if DPV2 were constructed without this EMF reduction measure.
For the 230 kV upgrades proposed west of the Devers substation, SCE proposes to optimally phase the 230 kV lines, as a no-cost EMF mitigation measure, and to optimally phase adjacent 55 kV lines between San Bernardino substation and San Bernardino Junction as a low-cost measure estimated to cost $270,000. As described above, these no-cost and low-cost measures would reduce the magnetic fields on both sides of the 230 kV right of way.
The ALJ requested that SCE develop information regarding the feasibility of low-cost mitigation of magnetic fields associated with the 500 kV Devers-Harquahala line and the 500 kV Devers-Valley No. 2 alternative to the 230 kV West of Devers upgrades. In particular, SCE was asked to determine how much taller the 500 kV towers would need to be in order to reduce magnetic fields by 15% at the edge of the right of way closer to the new transmission line, which is the side where DPV2 would increase the magnetic fields. The request was limited to those locations where there are residences within 200 feet of that edge of the right of way.
In response to the ALJ request and based on information compiled for the environmental review, Energy Division identified 60 residences within 200 feet of the right of way on the side closer to the new 500 kV transmission lines, with 5 residences located along the Devers-Harquahala segment and the remaining 55 residences located along the Devers-Valley segment. SCE reported that achievement of a 15% reduction in the magnetic field at the edge of the right of way near these residences would require a 20-foot increase in the height of about 33 towers, at an estimated incremental cost of $1.4 million. Since tower designs have height limitations, SCE cautions that, if any proposed tower height is already taller than about 170 feet, the additional 20-foot height increase may require a different tower design, with potentially significant cost increases.
SCE recommends that the Commission not require this low-cost EMF mitigation, but instead allow the tower and conductor heights to match the adjacent 500 kV transmission lines. SCE submits that constructing new towers taller than the existing towers would increase visual impacts and would conflict with recommended mitigation measures aimed at reducing the visual contrast of the towers, in particular, requirements that new towers match the heights of existing towers to the extent possible. SCE argues further that taller towers would increase the potential for collisions of birds with the power lines, and would conflict with recommended mitigation measures that would require that new towers and lines not be located significantly above existing towers and lines as a collision-reduction technique. As additional support for its position, SCE reports that, while 20-foot higher towers would reduce the magnetic field level by 15% at the edge of the right of way, magnetic field level changes beyond 50 feet from the edge of the right of way would be insignificant.
C. Discussion
As discussed in Section IV.B, we authorize SCE to construct the Devers-Valley No. 2 500 kV transmission line instead of the 230 kV transmission upgrades west of the Devers substation. With that modification to the DPV2 project, SCE should amend its EMF management plan as needed to apply its no-cost 500 kV EMF management techniques to the Devers-Valley corridor in addition to the Devers-Harquahala corridor.
Consistent with D.06-01-042 and D.93-11-013, we require that SCE undertake low-cost EMF mitigation. SCE should increase tower and conductor heights by 20 feet along those portions of the transmission corridor where there are residences near the side of the right of way closer to the new 500 kV transmission lines. SCE has established that this design modification would reduce magnetic fields by 15% at the edge of the right of way, which is consistent with the Commission's guidance in D.06-01-042 for low-cost EMF mitigation. This design modification should be undertaken wherever there are residential properties within 50 feet of the side of the right of way closer to the new 500 kV transmission lines. As SCE has pointed out, the change in magnetic field strength due to the new transmission lines would decrease significantly beyond 50 feet from the right of way.
We do not believe that the potential conflict of this low-cost EMF mitigation measure with environmental mitigation efforts would be significant. Few of the areas where EMF mitigation will occur are completely flat, and the towers and conductors would be difficult to line up due to even small elevation changes between existing and new towers. With tower heights of 150 feet, a 20-foot height increase for DPV2 towers and conductors is unlikely to be noticeable to most observers.
We require that SCE apply this low-cost EMF mitigation measure where there are existing residential properties and also where development of new residences is underway at the time that SCE undertakes final DPV2 project design. Consistent with guidance in D.06-01-042, we do not require that SCE attempt to determine possible future uses of undeveloped land. If applicable, SCE would not be required to raise tower heights near residential properties that will be acquired and converted from residential use in order to allow construction of DPV2, for example, as contemplated by APM L-7 (see Section IV.C.2 above).
With limitation to areas where residential properties are within 50 feet of the edge of the right of way closer to the new 500 kV transmission lines, the cost of the adopted EMF mitigation measure may be less than SCE's $1.4 million estimate, which encompassed residential properties within 200 feet of the right of way. Even at $1.4 million, the cost will be much less than the Commission's 4% benchmark for low-cost EMF mitigation. As described in Section III.A.5, SCE may seek an increase in the approved maximum cost of DPV2 if the adopted low-cost EMF mitigation measure causes the cost cap to be exceeded.
18 Because electric fields are shielded effectively by materials such as trees and walls, the emphasis in the Commission's consideration of EMF is on exposure to magnetic fields.
