Calpine currently owns two parcels that together
comprise 136 acres of land. Of this, 116 acres compose the
southern portion of Tulare Hill and the adjacent wetlands;
20 acres are flat area. Calpine has donated the
Tulare Hill, the wetland portion, and an additional 15 acres on Coyote Ridge to a local conservation organization, the Silicon Valley Land Conservancy.
A PG&E Substation is located approximately ¼ mile northeast of the site, and five PG&E transmission lines connect into the substation across Tulare Hill, just north of the site. A campus industrial park is planned for development to the south of the site. Development of a power plant in the area is consistent with the existing utility infrastructure. MEC was designed and landscaped to be consistent with the planned campus industrial area to the south of the site.
The plant uses two 200-MW "F" Class gas turbine generators exhausting into two heat recovery steam generator (HRSG) units. Steam generated in the HRSG units power a 235-MW steam turbine generator. Air pollutants in the gas turbine exhaust are controlled using state-of-the-art combustion technology, selective catalytic reduction (SCR), and clean-burning natural gas. Natural gas for the plant is supplied via a new, approximately 1-mile-long pipeline that connects into the existing PG&E gas transmission pipeline located east of U.S. 101.
The primary source of cooling water for the plant is
recycled water supplied by the South Bay Water Recycling Program
(SBWR), which obtains its water from the San Jose/Santa Clara
Water Pollution Control Plant (WPCP). The cooling water is supplied by our SBWR pipeline. Industrial wastewater returns to the WPCP via San Jose's sanitary
sewer system. This use of recycled water from the WPCP as
cooling water to MEC greatly assists the region in water conservation
and reduces the quantity of effluent that WPCP must discharge
to San Francisco Bay, thereby assisting WPCP in meeting its
discharge limits. The cooling water meets California Code
of Regulations Title 22 water quality requirements and is circulated through the cooling system to remove heat from the steam turbine cycle.
In the event the recycled water is not available for cooling,
backup water will be supplied either by the San Jose Municipal
Water System (San Jose MUNI) or Great Oaks Water Company,
from wells located approximately 1 mile south.
Environmental Considerations
Sixteen areas of possible environmental impact from the proposed project were investigated. Detailed descriptions and analyses of these areas are presented in Sections 8.1 through 8.16 of the AFC. Without the implementation of mitigation measures, several of these areas could have environmental effects. These effects are described briefly in this section.
Air Quality
The site is located in a State of California ambient air quality standards nonattainment area for both ozone and particulate matter with a diameter less than 10 microns (PM10). An assessment of the impact to air quality was performed using detailed air dispersion modeling. The air impacts from the project are mitigated by the advanced nature of the combustion turbine emission control technology. Additionally, emission reduction credits (ERCs) were obtained to offset volatile organic compounds (VOCs), NOx (both precursors of ozone), and PM10. These mitigation measures result in the project having no significant adverse impact on air quality. See Section 8.1 of the AFC for a detailed analysis of air quality.
Water Resources
Most of the water for the power generation facility's cooling
towers is recycled water from WPCP, treated to meet Title
22 requirements. The total quantity of water required is about
3 to 4 million gallons per day (mgd), of which approximately
one-fourth is returned to the WPCP. The balance (approximately
2.5 to 4.4 mgd) evaporates off from the cooling process
as water vapor. The quality of the water returned by MEC to
WPCP is regulated by the WPCP under its pretreatment
standards. The pretreatment standards allow the WPCP
to meet the requirements in its National Pollutant Discharge
Elimination System (NPDES) permit for discharge to San Francisco
Bay. Section 8.14 of the AFC provides a detailed description of water
resources.
Visual
The most prominent visual features of the MEC are two HRSG structures and their associated stacks. The cooling tower has a plume abatement system to eliminate the plume.
The combustion turbine exhaust stacks are approximately 145 feet high. The HRSG's are approximately 90 feet high.
See Section 8.11 for a detailed description of the visual effects
of MEC.
Biology
Sensitive Biological resources in the MEC project area include the serpentine grassland and outcrop habitats of Tulare Hill and adjacent hillsides, the waterways of Coyote Creek and Fisher Creek, and significant and/or heritage trees on the site and along Monterey Road. Tulare Hill is primarily serpentine soil. Serpentine soils support native vegetation and provide critical habitat for numerous special-status species, such as the Bay checkerspot butterfly, Opler's longhorn moth, the burrowing owl, the Metcalf Canyon jewel-flower, the Santa Clara Valley dudleya, and various native flowers.
Tulare Hill continues to be a link between the Santa
Teresa Hills and Coyote Ridge habitats for the Bay checkerspot
butterfly. The riparian corridors and aquatic habitats in
Coyote and Fisher creeks are avoided by the implementation of protection
measures and special construction methods. The loss of significant
trees from the site have been mitigated by planting up to 4
trees for every one lost along Fisher Creek and other strategic
areas. Impacts to sensitive biological resources from the
construction and operation of MEC were not significant.
Noise
Ambient noise measurements were taken to determine the L90 (the noise level that is exceeded during 90 percent of the measurement period) nighttime noise level at the nearest residence (i.e., sensitive receptor). Noise modeling was used to determine the contribution to the nighttime ambient levels the plant would make during operations. Appropriate mitigation measures were then developed so that the cumulative noise level does not cause the background level to be increased by more than 5 dBA (barely noticeable increase) at the nearest receptor. Since the cumulative increase in noise level at the nearest receptor will be barely noticeable during the most quiet nighttime hours at the nearest receptor, no adverse impact is experienced due to the normal operation of the facility.
Key Benefits
Environmental
MEC employs advanced, high efficiency combustion turbine technology and SCR to minimize emissions from the facility. NOx emissions, a precursor to smog produced by MEC, is approximately 90 percent less than for existing power plants. In addition to the significant reduction of emissions, MEC's operating efficiency is such that the plant consumes 40 percent less fuel than existing plants of similar size. MEC also obtained offsets to more than compensate (115%) for the emissions. Hence, the MEC project provides a net air quality improvement for the region.
MEC also minimizes fresh water usage. Treated secondary effluent (i.e., recycled water) from the WPCP is used for plant cooling purposes. This allows for the commercial use of a wastewater stream that would otherwise be discharged into San Francisco Bay without providing any useful or beneficial application. The use of recycled water has a significant benefit to the south San Francisco Bay waters. The WPCP is being ordered to reduce discharges into the Bay, and the MEC eliminates several million gallons per day of discharge.
Employment
The project provided for a peak of approximately 700 construction jobs over a 2-year period and will provide 20 skilled, family-wage positions throughout the life of the plant. In addition to the direct employment benefit, MEC required and will use throughout the life of the facility the services of local firms for major maintenance and overhauls, plant supplies, and other support services throughout the life of the facility.
Energy Efficiency
MEC is an efficient, environmentally responsible source of economic and reliable energy to serve the growing energy demands of the Bay Area. The San Jose-Silicon Valley area is growing rapidly, and MEC helps assure reliable, clean, low-cost electricity in the future.
