Transportation, storage and use of hazardous substances would not be required for operation of the new power lines, the reconductored power lines, or as a result of the reconfiguration of loop circuits. Although transformers that contain mineral oil and batteries similar to automobile batteries are commonly used at substations, no new transformers or batteries are proposed as a part of the project.
Other hazardous materials would be used in construction and maintenance of the power lines, including petroleum products, paints, and adhesives, as well as those hazardous materials used in autos and trucks. The use of such materials is common and is regarded as posing less than significant risks to workers or to public health and safety. PG&E proposes to handle all hazardous materials and waste in accordance with Best Management Practices (BMPs) as prescribed by PG&E (PG&E, 1992).
In the long term operation of the power lines and their terminations at the substations, there is a finite risk of electrical arcing and short-circuits due to failure of the equipment, or when a live phase conductor falls to the ground. The design of the power lines and substations, including the placement of the wires, equipment, and fencing at the substation, are intended to prevent public access to high-voltage equipment and to minimize the risk to the public of shock or injury in the event of equipment failure. The high-speed relay control systems that sense a broken line and activate circuit breakers within about one-tenth of a second mitigate the risk of fire and other harm to the public from downed power lines.
Excavation would be required for installation of underground line and poles to support above ground lines. If soil contamination or naturally hazardous soils (e.g., mercury bearing earth) were present within any construction area, such contaminated soils disturbed or excavated during site preparation could pose a health risk to construction workers or the adjacent public. Contaminated and naturally hazardous soils must be handled and disposed of in accordance with local, state, and federal regulations. If soil contamination were present within any construction area, all excavation would proceed according to worker safety requirements of the Federal and California Occupational Safety and Health Administrations (OSHA). If there were any site contamination and naturally hazardous soils that would require action, OSHA rules then would require a site-specific Health and Safety Plan (HASP) to be prepared and implemented by PG&E and its contractors to minimize exposure of construction workers to potential site contamination and to dispose of construction-derived waste soil in accordance with local, state, and federal regulations. These effects would be less than significant.
PG&E’s proposed mitigation measures (shown below in this section) for the new and modified 115 kV power lines are consistent with those employed along the existing 115 kV transmission line, and would be adequate to ensure a minimal risk of fire, accidental explosion or release of hazardous substances. Assuming implementation of the mitigation measures proposed as part of the project, additional mitigation would not be required and project-related hazards would be less than significant.
To the extent that project construction and operation would improve the reliability of the regional and the local electric power system, the proposed Looping Project would benefit local emergency response capabilities. No interference with the emergency response plans or emergency evacuation plans of the County of Santa Clara is evident.
d. The project would construct new 115 kV power lines, and supply electricity to the regional 115 kV power network. By its nature, the project provides certain benefits and poses certain risks to the public. Because the project will alter the electric and magnetic fields (EMF) along the routes of the new 115 kV power lines, concerns about potential health-related consequences of the EMFs are addressed.
Most of the length of the new power lines would be underground, except those portions that would be on PG&E and SCVWD property. PG&E has not estimated the magnetic field strengths to be expected under the power lines or at the boundary of the substations. However, above ground high-voltage power lines, under peak electrical load conditions, have been estimated to generate magnetic field strengths in the range of roughly 100 to 200 milliGauss (mG) or less at the edge of the right-of-way. Magnetic field strengths in the range of roughly 10% to 20% of those values or less can be expected to occur at the substation boundaries, except at locations beneath the distribution lines entering or leaving the substation, where the values could be higher. Placement of power lines underground results in a more intensified field, but one that dissipates more quickly with distance. This effect is due to the fact that the nine separate lines would be placed closer together in comparison to aboveground power lines.
These values represent, in effect, rough estimates of the maximum conditions at the boundaries of the substations and boundaries of the power line right-of-ways on PG&E and SCVWD property. Because the PG&E and SCVWD properties have restricted access, no hazards to the public are present.
Typically, it can be expected that the highest levels of magnetic field strengths at the boundaries of the substation would occur at the locations of the distribution lines or the locations of overhead 115 kV power lines. Similarly, the highest levels of magnetic field strengths would be expected to occur at the center of the power line right-of-way, under the lowest point of the power line.
In response to public concern about possible health effects of EMFs from electric utility facilities, the CPUC opened an investigation of the hazards. On November 2, 1993, the CPUC issued Decision 93-11-013, which recognized the public concern, but which declined to "adopt any specific numerical standard in association with EMFs until we have a firm scientific basis for adopting any particular value." However, in that decision, the CPUC did direct all publicly owned utilities to take "no cost and low-cost" EMF reduction steps on transmission, substation, and distribution facilities to reduce exposure of the public to magnetic fields.
In accordance with that requirement, the final design of the Stelling/Wolfe/Monte Vista Looping Project would include standard "no cost and low-cost" EMF reduction measures proposed by PG&E that would include: increasing the separation distance between the public and electrical conductors and equipment; reducing the spacing between current-carrying electrical conductors; minimizing the current carried; and, optimizing the phase configuration in the power line.
The possible relationships between exposure to EMFs and potential health-related effects have been investigated by many organizations, including the U.S. National Academy of Sciences, American Medical Association, American Cancer Society, California Department of Health Services, National Institute of Environmental Health Sciences, U.S. Department of Energy, and the CPUC (PG&E, 1997). The U.S. National Academy of Sciences study (NAS, 1996) is the most comprehensive evaluation of the topic; that committee concluded that the current body of evidence does not show that exposure to power-frequency EMFs presents a human hazard.
The most recent study on EMFs was conducted by the National Institute of Environmental Health Sciences. A majority of the researchers in this latest study concluded that classifying low frequency fields as "possibly carcinogenic" is a conservative, public health decision based on limited epidemiological evidence of an increased risk for childhood leukemias with residential exposure.
There is no evidence that the additional EMF contributed by the new power line circuit would create a health hazard or potential health hazard. Therefore, the impact is considered less than significant, and mitigation beyond that proposed by PG&E as part of the project, in accordance with CPUC Decision 93-11-013, is not required.
Accompanying the operation of the power lines are concerns about other phenomena such as corona discharge, electrical interference, and electric shock and currents induced by the power lines. Design standards for power lines use established standards to limit the effect of these phenomena to less than significant levels.
The power lines would be located underground in all areas not on PG&E or SCVWD property. This would prevent any hazard of arcing leading to a fire that would spread to grasses, shrubs and trees outside the perimeters of the sites. There would be no increase in fire hazard on the substation sites or adjacent areas. Standard fire suppression measures will be undertaken during construction activities.
Operation of the overhead power lines carries a finite risk of electric arcing due to objects contacting the energized power line; that arcing, in turn, could lead to a fire. Where there would be new 115 kV power line circuits, the incremental increase in fire risk along that length is very small. The rigorous maintenance of right-of-way landscaping trees, in accordance with CPUC General Order 95 (G.O. 95), would be effective in reducing to acceptable levels the risk of fire due to tree contact with above ground power lines.
Applicant Proposed Mitigation
Fire prevention activities will be performed by mowing dead, herbaceous vegetation in areas where vehicles will be parked, equipment and materials will be stored, and where crews may work.
No campfires or trash burning will be allowed anywhere within the project boundaries.
Smoking will be restricted to vehicle interiors. All cigarette butts will be disposed of in vehicle ashtrays.
All vehicles will be equipped with a minimum five-gallon water container and at least a two-pound fire extinguisher. Hand tools and shovels will also be stocked on all vehicles.
Fire resistant mats or windscreens will be placed on the ground below welding and splicing equipment/operations wherever dry vegetation is present.
All welding and splicing rigs/trailers will be equipped with a minimum 20-pound fire extinguisher and a minimum of five gallons of water in a fire fighting apparatus.
The construction foreman will have a cellular phone on hand to immediately report a fire.
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