Several hazardous substances would be used in the operation of the Northern Geysers Area Reinforcement Project. 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 and substation modifications, 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 worker or public health or safety. PG&E proposes to handle all hazardous materials and waste in accordance with Best Management Practices (BMP), 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 sensing and 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.
A small amount of excavation would be required for the proposed access roads in the Geysers and for poles at the Fulton Substation project. If soil contamination or naturally hazardous soils (e.g., mercury bearing earth) werepresent 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 waste 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 for the new and modified 115 kV power lines are consistent with those employed along the existing 230 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 the hazard would be less than significant.
Most of the length of the new power lines is on the right-of-way of the existing 230 kV transmission line, an operating high-voltage electric power transmission facility. PG&E has not estimated the magnetic field strengths to be expected under the power lines or at the boundary of the substations. However, similar 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. Also, 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 power or distribution lines entering or leaving the substation, where the values could be higher. These values represent, in effect, rough estimates of the maximum conditions at the boundaries of the substation and boundaries of the power line right-of-ways.
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.
Compared to present maximum contributions from the existing 230 kV power lines, the project would add a contribution that would be similar to the existing magnetic field strength present under the existing lines.
Average annual electrical load conditions for the power lines would be less than the maximum load, and the contribution of the project to the magnetic field strength at the edge of the right-of-way would be about correspondingly decreased.
Ultimately, new power lines and distribution circuits would connect the Eagle Rock and Fulton Substations to the existing electric transmission and distribution system. While not part of the proposed project, they would contribute to EMFs at locations near the Eagle Rock and Fulton sites. These contributions would occur generally within the existing power lines rights-of-way. Members of the public that would be exposed to these fields include anyone walking within those right-of-ways. As the Geysers site has restricted access to workers in the KGRA, no hazards to the public are present. The Fulton site is fenced and there are no roads or sidewalks near any of the proposed facilities.
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 Northern Geysers Area Reinforcement Project would include "no cost and low-cost" EMF reduction measures that likely 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 recent 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.
Based on the results of the U.S. National Academy of Science study, there is no evidence that the EMF from the proposed 115 kV power lines presents a health hazard to those individuals who live and/or work in the vicinity of either substation or along the 115 kV power line routes. Further, there is no evidence that the additional EMF contributed by the new power line circuit would create a health hazard or potential health hazard. The impact is 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.
Also, 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.
Operation of the proposed modified Fulton and Eagle Rock substations would not greatly alter the number of people working on or using those sites, since both are operated remotely. Those who do work periodically at those substations would be PG&E employees or contractors, acting in accordance with occupational health and safety requirements. As a result of these two factors, that part of the project would result in a small increase in the total exposure of people to any existing sources of potential health hazards.
Operation of the proposed power lines would not change the number of people working within or using the power line route right-of-ways. No individuals would live or work within the right-of-ways, which are used for various agricultural uses. As a result, operation of the power lines would result in very small increases in the total exposure of people to any existing sources of potential health hazards.
The cleared and graded areas within the existing substations would be maintained and kept free of shrubs or trees that might colonize the site; 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.
Operation of the 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 the new 115 kV power line circuit replaces an existing 230 kV transmission line circuit, the incremental increase in fire risk along that length is very small. The project includes detailed measures to mitigate the fire risk along the routes of the two power lines, so even where there is no existing power line, the incremental increase in fire risk also 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 power lines. As a part of the project, PG&E has proposed a further mitigation measure to warn construction and maintenance workers to not discard lighted matches or other burning materials in order to avoid starting fires.
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