Several hazardous substances would be used in the operation of the proposed FMC Substation. One 115/12 kV, 30-MVA transformer could contain up to 6,500 gallons of mineral oil, which is used as an insulating medium and coolant. The mineral oil would not contain Polychlorinated Biphenyls (PCBs). To prevent the release of mineral oil in the event of damage to the transformer, PG&E proposes that the transformer would be mounted on a sealed pad with drainage directed to a SPCC collection system and pond that could hold 150% of the volume of oil from one transformer. A weir system with a manually operated gate valve would retain any oil in the SPCC pond for collection and disposal at an approved site. Environmental Protection Agency regulations require that the equipment and spill containment area be inspected at least monthly. During heavy storm periods, more frequent monitoring of the transformers and the SPCC pond would be conducted to prevent overflows of the pond. The operator would check the pond for evidence of an oil sheen, and any oil would be cleaned up before the valve would be manually opened by the operator to release rainwater that had accumulated in the pond.

Batteries would be used for emergency back-up power at the substation. Similar to automobile batteries, these batteries would contain sulfuric acid in the electrolyte. The substation’s three batteries would have 20 cells each for a total of 60 cells, and would provide an output of 125 volts (in comparison, an automobile battery has 6 cells and provides an output of 12 volts). Release to the environment of material from the batteries in the event of a spill would be prevented by housing them in a building proposed to be constructed with a concrete floor and without drains.

Nitrogen gas (N₂) and Sulfur Hexafluoride gas (SF₆), both inert and non-toxic gases, would be used at the substation. N₂ would be used to slightly pressurize oil-filled equipment, while SF₆ would be used as an insulator and arc suppresser in circuit breakers. SF₆ would not be released under normal conditions; PG&E usually recycles the SF₆ gas in the breakers during maintenance. When SF₆ is exposed to electric arcs, a small quantity of solid residue forms that is highly toxic and must be removed to prevent exposure hazards to PG&E personnel working with the circuit breakers. Vacuuming with a heavy duty shop vacuum and/or cleaning of the equipment surfaces with dry, lint-free rags and proper disposal of the material is adequate to control potential hazards from this residue.

The only potential hazard to the public involved in the use of either the N₂ or SF₆ is a physical hazard involving the high pressure of the gases in the storage cylinders. The likelihood of a cylinder explosion is low; distance between the cylinders and any public access makes the risk of injury remote.

In the long term operation of the substation, and in the operation of the power and distribution lines, there is a finite risk of electrical arcing and short-circuits due to failure of the equipment. The design of the substation, including the placement of the wires, equipment, and the fencing around the substation, as well as the design of the power and distribution lines, is 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.

Shallow soil contamination by fuels, metals, volatile organic compounds, and phenol at the site has been documented (Parsons, 1997). If present within the expansion areas, contaminated soils disturbed or excavated during site preparation could pose a health risk to construction workers or the adjacent public. Additionally, contaminated waste soils must be handled and disposed of in accordance with local, state, and federal regulations. Risk-based analysis of on-site contamination indicates that on-site soil contamination is below target levels that would identify further investigation. However, the California Department of Toxic Substances Control (DTSC, the lead agency) has not categorically accepted risk-based assessment, and the case has not been closed. Consequently, the potential exists for site remediation to be required by the regulatory agency (DTSC). Installation of the proposed transformers at the site could potentially impede further investigation or clean-up actions. However, as the placement of the transformers requires a large, continuous concrete pad foundation, the soil would be effectively sealed below the substation. Construction of the foundation would require excavation, which would proceed according to worker safety requirements of the Federal and California Occupational Safety and Health Administrations (OSHA). If DTSC determines that site contamination requires 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.

PG&E’s proposed mitigation measures are consistent with those employed at other substations and power lines, and would be adequate to ensure a minimal risk of accidental explosion or release of hazardous substances. Assuming implementation of the mitigation measures proposed as part of the plan, additional mitigation is not required and the hazard would be less than significant.

To the extent that the construction and operation of the project would improve the reliability of the local electric power system, the proposed substation would benefit local emergency response capabilities. However, no interference with the City of San Jose’s emergency response plan or emergency evacuation plan is evident.

The project will take high-voltage electricity from the PG&E 115 kV power line, step-down the voltage to 12 kV, and distribute the electricity to local customers. By its nature, the project provides certain benefits and poses certain risks to the public. In addition to the issues discussed elsewhere in this section of the Initial Study, because the project will alter the electric and magnetic fields (EMF) in the vicinity of the site, concerns about potential health-related consequences of the EMF are addressed.

The project is located on the right-of-way of a PG&E 115 kV power line, an operating high-voltage electric power transmission facility. The power line, under peak electrical load conditions, is estimated to generate a magnetic field strength of not more than 150 milliGauss (mG) at the edge of the right-of-way (PG&E, 1997). This value represents, in effect, a maximum baseline condition for the substation site, along the boundaries of the power line right-of-way; directly under the power line, the value would be higher.

PG&E calculated the magnetic field strength that would be created by the operation of the substation at the proposed substation property boundaries. Based on ultimate build-out of the substation with three 30-MVA transformer banks, twelve 12 kV distribution feeders (four from each of the three banks), it was determined that the strength of the magnetic field at the property boundary would range from 0.6 mG to 10.2 mG (PG&E, 1997). The calculations include magnetic field strength contributions from the 115 kV power line, but exclude contributions from the existing 20-MVA transformer bank or the stand-by generator. Although connections to the existing power line are necessary, the existing power line is not a part of the proposed project, while the new circuit is a part of the proposed project.

Under the maximum electrical load conditions, the contribution of the project to the magnetic field strength at the property boundaries would range from 0.6 mG to 10.2 mG, as follows: along the west (railroad property) boundary, 0.6 mG to 0.7 mG; along the northern boundary, 1.1 mG to 6.0 mG; along Stockton Avenue, 1.0 mG to 10.2 mG; and along the southern (I-880) boundary, 0.8 mG to 10.2 mG. Typically, the higher levels of magnetic field strengths at the boundaries of the substation correspond to the locations of the undergrounded 12 kV distribution lines or the locations of overhead 115 kV power lines. Magnetic field strengths at the residences across Stockton Avenue would be substantially less than the values in the street right-of-way.

Compared to present maximum contributions from the existing substation and 115 kV power line and an undetermined contribution from the 12 kV distribution lines along Stockton Avenue, the project would add a contribution that would be similar to, but larger than, the existing magnetic field strength present at the substation.

Average annual electrical load conditions for the substation would be less than the maximum load, and the contribution of the project to the magnetic field strength at the property boundaries would be about correspondingly decreased. Further, typical magnetic field strengths at the edge of power line rights-of-way would be 10 mG to 90 mG (PG&E, 1997).

Ultimately, up to twelve underground 12 kV distribution circuits would connect the FMC Substation to the existing electric distribution system. While not part of the proposed project, they would contribute to EMF at the site. The undergrounded feeds to the 12 kV distribution lines would all exit the substation site on the Stockton Avenue frontage.

These contributions would occur within the existing rights-of-way of the streets and power lines and not on surrounding residential or commercial properties. Members of the public that would be exposed to these fields include anyone walking within the rights-of-way or along the Stockton Avenue frontage of the project site.

In response to public concern about possible health effects of EMF 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 EMF 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 proposed design of the FMC Substation includes the following "no cost and low-cost" EMF reduction measures:

1. For structures adjacent to the school and residential areas, raise the 115 kV power line’s poles (and conductors) by 5 feet to reduce EMF at ground level;

2. Arrange the phasing of the 115 kV power line and the 12 kV distribution lines so that they create the minimum magnetic field at the edge of the substation right-of-way;

3. Use metal-clad switchgear at the substation to reduce magnetic field contributions from the 12 kV bus; and,

4. Use compact equipment spacing at the substation, which reduces the site area used and allows equipment to be shifted away from the residential and commercial areas across Stockton Avenue. Providing more distance between the equipment and the property lines would reduce magnetic field strength at the property line.

The possible relationships between exposure to EMF 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 EMF presents a human hazard.

Based on the results of the U.S. National Academy of Science study, there is no evidence that the existing EMF from the substation or the 115 kV power line (and the 12 kV distribution lines) presents a health hazard to those individuals who live and/or work in the vicinity of the site. Further, there is no evidence that the additional EMF contributed by the proposed FMC Substation or 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 as part of the project is not required.

Operation of the proposed FMC Substation would decrease the number of people working on or using the site, so the project would not increase the total exposure of people to any existing sources of potential health hazards.

The site is substantially cleared of vegetation, and would be mostly paved with the construction of the substation. The cleared area within the substation 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 the landscaping trees on the perimeter of the site. There would be no increase in fire hazard on the site or adjacent areas.

Operation of the power line carries a finite risk of electric arcing due to objects contacting the energized power line; that arcing, in turn, could lead to a fire. Given that there are existing power lines over most of the length of the new power line, the incremental increase in fire risk is likely very small. Rigorous maintenance of right-of-way landscaping trees, in accordance with the schedule proposed (PG&E, Response to Deficiency Report, Table 2, FMC Project Area Tree Survey, and Table 3, Alignment Option "A" Tree Survey, 1998), would be effective in reducing the risk of fire due to tree contact with power lines.