4.4 AIR QUALITY

4.4.1 Overview of Proposed Project Related Air Quality Issues

The purpose of the proposed Tehachapi Renewable Transmission Project (TRTP) is to provide the electrical facilities necessary to integrate levels of new wind generation in excess of 700 megawatts (MW) and up to approximately 4,500 MW in the Tehachapi Wind Resource Area (TWRA).

Transmitting the electricity generated by the wind farms would reduce reliance on electricity generated from power plants that operate on coal, natural gas, and/or other types of fuel. Hence, utilizing “wind” electricity would reduce the emission of air pollutants associated with fossil-fueled power plants.

The proposed Project extends through Kern, Los Angeles, and San Bernardino counties. These counties are located within the Mojave Desert Air Basin (MDAB) and South Coast Air Basin (SCAB). In the Project area, air quality is regulated by the following three local air districts: Kern County Air Pollution Control District (KCAPCD), the Antelope Valley Air Quality Management District (AVAQMD) and the South Coast Air Quality Management District (SCAQMD), as shown on Figure 4.4-1.

4.4.1.1 Mojave Desert Air Basin

The MDAB covers more than 20,000 square miles and encompasses the majority of California’s high desert with typical hot, dry summers and cold winters with little precipitation. It is bounded by the San Gabriel and San Bernardino mountains to the south, which serve as the boundary separating the MDAB and the SCAB. The Tehachapi Mountains serve as the northwest boundary separating the MDAB from the San Joaquin Air Basin (SJAB). The majority of the population resides in the southeast area of the MDAB with the remaining population scattered in rural areas. There are approximately 494,000 persons residing within the MDAB (Census, 2003). Because it is a desert environment consisting of flat terrain, during high wind conditions, a substantial amount of fugitive dust (i.e., particulate matter [PM]) is generated. Air quality in the MDAB is also heavily influenced by airborne pollutants transported into the region from areas within the SCAB under the jurisdiction of the SCAQMD.

4.4.1.2 South Coast Air Basin

The SCAB covers an area of 6,745 square miles and consists of Orange County and the non-desert portions of Los Angeles, Riverside, and San Bernardino counties. It is bounded on the west by the Pacific Ocean, the north by the San Gabriel Mountains, the east by the San Bernardino Mountains, and the south by the Santa Ana Mountains. The SCAB has over 15 million people with one of the worst air quality conditions (e.g., high concentrations of ozone [O₃], carbon monoxide [CO], particulate matter less than or equal to 10 microns (PM₁₀), and PM less than or equal to 2.5 microns [PM_2.5]) in the nation because of the topographical features that trap anthropogenic air pollutants that are associated with the dense population. Mobile source emissions are a major contributor to overall pollution within the SCAB. The SCAB experiences a persistent temperature inversion (increasing temperature with increasing altitude) that limits the vertical dispersion of air contaminants, holding them relatively close to the ground until the inversion layer breaks through, allowing the vertical mixing of the layers. Strong, dry north or northeasterly winds, known as Santa Ana winds, occur during the fall and winter months, helping to disperse air contaminants.

4.4.1.3 General Project Description

The TRTP is separated into eight distinct segments, Segments 4 through 11. Segments 4 through 8 and Segment 11 all involve existing transmission corridors. Segment 10 would be a new transmission facility requiring new right-of-way (R-O-W). Transmission facilities consist of transmission towers and transmission lines (T/L). Segment 8 has three sub-segments: 8A, 8B, and 8C, with each having slightly different components, but serving the same purpose (i.e., to transmit electricity). Segment 10 has two alternative routing options. Segment 9 consists of upgrades to existing substations (i.e., Antelope, Vincent, Mesa, Gould, and Mira Loma) along the proposed transmission corridor and the construction of a new substation, Whirlwind. The air basins and air districts associated with each segment are presented in Table 4.4-1.

Because the proposed Project stretches over multiple air basins and air districts, only the general description of the air basins is provided in this section. Detailed data, such as local meteorological data, ambient criteria air pollutants concentrations, and physical equipment descriptions for each segment, are described in greater detail in Sections 4.4.6.1 through 4.4.6.8. Implementation of the proposed T/L and substation construction and/or upgrades would generate air pollutants during construction and operational activities. The majority of the segments would involve the following construction activities:

•  Establishing marshalling yards for staging of equipment and storage of construction materials

•  Development of access roads and spur roads

•  Removal and replacement of existing transmission towers and T/Ls

TABLE 4.4-1
SEGMENTS AND ASSOCIATED AIR BASINS AND AIR DISTRICTS

•  Installation of new transmission towers, lines, and a substation

•  Enhancements to existing substations

This section provides the following information:

•  Method used to quantify construction and operational emissions

•  Existing air quality data, including a general discussion of air quality rules and regulations

•  Air quality impact assessment

Existing air quality data and applicable regulations presented in this section were derived from applicable government websites for the following agencies: United States Environmental Protection Agency (USEPA), United States Forest Service (USFS), California Air Resources Board (CARB), SCAQMD, AVAQMD, KCAPCD, Federal Highway Administration (FHWA), and Federal Aviation Administration (FAA).

4.4.2 Technical Methodology

To determine the significance of potential air quality impacts from the implementation of the proposed Project, the net increase in air pollutants associated with the implementation of the proposed Project were quantified and compared with applicable criteria pollutant significance thresholds for each air district and General Conformity Rule (GCR) DeMinimis levels. According to the construction schedule (Section 3.0, Table 3.9-1), between February 2010 and March 2011, construction of Segments 4 through 9 would occur simultaneously and overlap the entire time. As such, the air quality analysis assessed the significance of air quality impacts for the segments on an individual basis assuming all construction phases within the segment were occurring simultaneously. This scenario is not likely, but portrays a worst-case scenario. The impact analysis presented in Section 4.4.7 (Overall Project Impact Analysis) considers segments located in the same air district where emissions would be additive.

4.4.2.1 Construction Emissions

The construction of the proposed Project would last approximately 55 months, and is expected to extend from approximately April 2009 to November 2013. Construction activities were categorized into the following general activities: roadway construction, site preparation, construction and installation of new transmission towers and lines, upgrading of existing substations, and the construction of the new substation. During these activities, air pollutants would be emitted from the use of construction equipment. In addition, air pollutants would also be emitted from vehicles used to deliver construction equipment and materials, haul waste, and transport workers. Fugitive dust generated during site grading activities was also quantified. Approximately 1,444 acres would be disturbed with the majority of construction activities occurring within existing SCE R-O-W.

Construction equipment exhaust emissions were quantified using the construction data provided in Section 3.0 (Project Description) and Appendix P (Project Description Appendix) and emission factors for off- and on-road mobile sources from SCAQMD’s web site (SCAQMD, 2006a, 2007a). These two sections of the PEA provide a description of the construction process and a detailed list of construction equipment, daily operating hours, duration of each construction phase, and number of workers for each construction phase. Daily and annual construction emissions were quantified for every phase using construction timeline, type of equipment, quantity of equipment, hours of operation, and reasonable assumptions. Assumptions were made for data such as distance traveled by off-road equipment at the Project site and on-road vehicles (i.e., trucks hauling construction materials and workers’ commute distance). Haul trucks were assumed to travel a roundtrip distance of 30 miles in urban and rural areas, while construction worker vehicles were assumed to travel a roundtrip distance of 40 and 80 miles in urban and rural areas, respectively. If the Project site is in a combination of urban and rural areas then the workers’ commute roundtrip distance was assumed to be 60 miles. Other assumptions made are provided in the footnotes of the construction emissions worksheets (see Appendix G).

Although portions of the proposed Project are located within KCAPCD, AVAQMD, and SCAQMD air districts, SCAQMD emission factors for exhaust, tires, and brakes of off- and on-road mobile sources were used because they are the most detailed (i.e., emission factors are provided for various type of construction equipment and for various years). SCAQMD emission factors were used to estimate exhaust emissions from all the construction phases proposed for Segments 4 through 8, and Segment 11. Where an air district did not have adequate data (e.g., emission factors, guidance manual) for the air quality analysis, methods and data from another air district were used, a practice widely accepted by air districts in California. Helicopter emission factors are based on values from the Federal Aviation Administration’s Aircraft Engine Emission Database (FAA, 2001).

As construction schedules are finalized, actual construction emissions are expected to be lower than presented in the following analysis. However, based on the existing schedule data available at this time, it was assumed that all construction phases could occur and overlap on any particular day. This assumption presents a worst-case peak daily construction scenario. To estimate annual emissions and compare it to the applicable significance thresholds and the GCR DeMinimis levels, emissions generated during each construction phase were evenly distributed according to the number of months of construction activities scheduled for that particular year. For example, Segment 4 is expected to start in April 2009 and end in April 2011, which equates to nine months of construction in year 2009, 12 months in year 2010, and three months in year 2011 for a total of 24 months. Therefore, in 2009, it was assumed that approximately 37.5 percent (i.e., 9 months/24 months) of each construction phase was completed in 2009; 50 percent (i.e., 12 months/24 months) was completed in 2010, and 12.5 percent (3 months/24 months) was completed in 2011. This method of estimating annual emissions correlates with the assumption that construction phases overlap throughout the year. Annual emissions are calculated based on the calendar year and not a 12-month rolling total. Detailed construction equipment exhaust emissions calculations are provided in Appendix G.

There are numerous ways to estimate fugitive dust emissions from construction activities; however, the level of precision is dependent on the availability and accuracy of project-specific data such as silt content of excavated soil, soil moisture content, depth of excavation, wind speed, annual precipitation, type of construction equipment used, distance traveled, and how often and how much water or surfactants are used to control dust on unpaved roads and in the excavation areas. Fugitive dust emissions associated with construction of the TRTP were quantified using fugitive dust emission factors available on the CARB webpage, http://www.arb.ca.gov/ei/areasrc/ONEHTM/ONE7-7.HTM. The emission factor, 0.11 ton of PM₁₀per acre-month, was developed to analyze PM₁₀ emissions generated from average construction activities (including operation of vehicles on unpaved roads1) that do not involve substantial earth-moving activities. Substantial earth-moving operations are defined as any earth-moving operation with a daily earth moving or throughput volume of 5,000 cubic yards or more that occurs three times during a 365-day period (SCAQMD Rule 403 [c]21). This emission factor assumes that water is applied during site grading to minimize fugitive dust resulting in an emission reduction efficiency of 50 percent. Based on the Project description, the TRTP would excavate up to approximately 200 cubic yards of soil during installation of foundations for each of the transmission towers. Access roads and spur roads would be constructed in sections at a time and, therefore, they would not require moving a substantial amount of soil on a daily basis. As such, the proposed Project is considered to be an average, typical construction operation. Therefore, to quantify fugitive dust emissions using the above emission factor, it was assumed that 5 acres are disturbed per day for removal and installation of the foundations, and grading new access road and spur roads. The 5 acres assumption was based on the 1,444 acres to be disturbed over 55 months, which breaks down to approximately 26.3 acres per month or 1.2 acres per day. To be conservative, it was assumed that three to four segments would be active, or approximately 5 acres.

To estimate PM_2.5 emissions from combustion and fugitive sources, SCAQMD created a method to estimate PM_2.5 emissions from combustion and mechanical/fugitive emission sources. Mechanical sources are any type of sources other than combustion (e.g., fugitive dust generated from motor vehicles traveling on unpaved roads). The method assumes a direct correlation between PM₁₀ and PM_2.5 data in the 2003 Air Quality Management Plan (AQMP) annual inventories for combustion and mechanical/fugitive sources. Based on this assumption, SCAQMD derived default ratios for mechanical/fugitive processes, combustion sources, and off-road combustion sources. The default ratios assumed a certain percentage of PM₁₀ emissions are PM_2.5 emissions. For mechanical/fugitive dust, the method assumes 21 percent of PM₁₀ emissions are PM_2.5 emissions. For combustion sources, 99 percent of PM₁₀ is PM_2.5 emissions and for off-road combustion sources, 89 percent of PM₁₀ is PM_2.5. PM_2.5 emissions for fugitive dust and off-road combustion sources were estimated using the default ratios. For on-road mobile sources, PM_2.5 emissions were estimated using emission factors provided on the SCAQMD’s web site (SCAQMD, 2007b) and derived from the mobile source emission factor model, EMFAC2007, which was developed by the CARB.

The proposed Project extends over three air districts with certain segments overlapping within two districts. Because each district has its own significance thresholds, construction emissions for overlapping segments (i.e., Segments 4, 6, 9, and 11) were prorated based on the physical extent of the segment located within the individual air districts. The daily and annual emissions were then compared to applicable criteria pollutant thresholds for each district to determine the significance of air quality impacts. A summary of construction emissions is provided for each segment, and the detailed calculation worksheets for each segment are provided in Appendix G.

4.4.2.2 Operation Emissions

Upon completion of the proposed Project, the only change in operation emissions would be generated from the testing of the new emergency generator located at the Whirlwind Substation and maintenance vehicles used to transport personnel during maintenance and repair. The existing generator at Vincent Substation would be replaced with a newer model, resulting in lower emissions and improving existing air quality. Therefore, the Vincent Substation generator is not discussed any further in this analysis. While the emergency generator would only be operated during an unforeseen crisis and not on a regular basis, the generator would have to be tested regularly (e.g., assumed 30 minutes biweekly). Scheduled maintenance activities are assumed to be minimal (e.g., once per year). As such, operation (i.e., long-term) air pollutant emissions generated during generator testing and from maintenance vehicles are expected to be negligible and considered to have less-than-significant air quality impacts.

4.4.3 Air Quality Regulations, Plans, and Standards

Federal and state governments have each established standards for ambient air quality. The USEPA has established primary and secondary National Ambient Air Quality Standards (NAAQS) that specify allowable ambient concentrations for criteria pollutants under the provisions of the Clean Air Act (CAA). Allowable ambient concentrations are set for the following criteria pollutants: O₃, respirable PM₁₀, fine PM_2.5, CO, nitrogen dioxide (NO₂), lead (Pb), and sulfur dioxide (SO₂). Table 4.4-2 summarizes the NAAQS for these pollutants. The 8‑hour O₃ and PM_2.5 standards listed in the table were promulgated in 1997, but were challenged in the courts. In 2002, the courts upheld these two standards. The USEPA made final designations for the 8‑hour O₃ standards on April 15, 2004, and final designations for the new federal PM_2.5 standards in December 2004. Currently, the USEPA and the states are working together to develop air quality plans to achieve compliance with these standards, where needed. Health effects associated with exposure to criteria pollutants are presented toward the end of this section.

The USEPA, under the provisions of the CAA, requires each state with regions that have not attained the NAAQS to prepare a State Implementation Plan (SIP), detailing how these standards are to be met in each local area. The SIP is a legal agreement between each state and the federal government to commit resources to improving air quality. It serves as the template for conducting regional and project-level air quality analysis. The regional analysis is performed by the appropriate Metropolitan Planning Organization (MPO) and the project-level analysis by the project sponsor. The SIP is not a single document, but a compilation of new and previously submitted attainment plans, emissions reduction programs, district rules, state regulations, and federal controls. Areas designated as serious nonattainment are

TABLE 4.4-2
FEDERAL AND STATE AMBIENT AIR QUALITY STANDARDS

¹   California standards for ozone, carbon monoxide (except Lake Tahoe), sulfur dioxide (1‑ and 24‑hour), nitrogen dioxide, suspended particulate matter-PM₁₀, PM_2.5, and visibility reducing particles, are values that are not to be exceeded. All others are not to be equaled or exceeded. California ambient air quality standards are listed in the Table of Standards in Section 70200 of Title 17 of the California Code of Regulations.

²   National standards (other than ozone, particulate matter, and those based on annual averages or annual arithmetic mean) are not to be exceeded more than once a year. The ozone standard is attained when the fourth highest eight-hour concentration in a year, averaged over three years, is equal to or less than the standard. For PM₁₀, the 24‑hour standard is attained when the expected number of days per calendar year with a 24‑hour average concentration above 150 µg/m³ is equal to or less than one. For PM_2.5, the 24‑hour standard is attained when 98 percent of the daily concentrations, averaged over three years, are equal to or less than the standard. Contact USEPA for further clarification and current federal policies.

³   Concentration expressed first in units in which it was promulgated. Equivalent units given in parentheses are based upon a reference temperature of 25 °C and a reference pressure of 760 torr. Most measurements of air quality are to be corrected to a reference temperature of 25°C and a reference pressure of 760 torr; ppm in this table refers to ppm by volume, or micromoles of pollutant per mole of gas.

⁴   Any equivalent procedure that can be shown to the satisfaction of the CARB to give equivalent results at or near the level of the air quality standard may be used.

⁵   National Primary Standards: The levels of air quality necessary, with an adequate margin of safety to protect the public health.

⁶   National Secondary Standards: The levels of air quality necessary to protect the public welfare from any known or anticipated adverse effects of a pollutant.

⁷   Reference method as described by the USEPA. An “equivalent method” of measurement may be used but must have a “consistent relationship to the reference method” and must be approved by the USEPA.

⁸   New federal 8‑hour ozone and fine particulate matter standards were promulgated by USEPA on July 18, 1997. Contact USEPA for further clarification and current federal policies.

⁹   The CARB has identified lead and vinyl chloride as ‘toxic air contaminants’ with no threshold level of exposure for adverse health effects determined. These actions allow for the implementation of control measures at levels below the ambient concentrations specified for these pollutants.

¹⁰  Due to lack of evidence linking health problems to long-term exposure to coarse particle pollution, USEPA revoked the annual PM₁₀ standard in 2006 (effective December 17, 2006).

* - µg/m³ = micrograms per cubic meter; mg/m³ = milligrams per cubic meter; ppm = parts per million

Source: CARB, February 22, 2007; USEPA, 2007.

required to achieve attainment by June 15, 2013. The CARB, which is part of the California Environmental Protection Agency (CalEPA), is the lead agency for developing this SIP. Local air districts and other agencies prepare Air Quality Attainment Plans (AQAPs) or Air Quality Management Plans (AQMPs) and submit them to CARB for review, approval, and incorporation into the applicable SIP.

In 1976, the California Legislature adopted the Lewis Air Quality Management Act, which created Air Quality Management Districts (AQMDs) and Air Pollution Control Districts (APCDs). Though separate from federal actions, the creation of AQMDs/APCDs became an integral part of conformity, which is described below. CARB oversees activities of the APCDs and regional AQMDs. The AQMDs and APCDs promulgate the strategies stated in the SIPs for achieving cleaner air quality on a region-by-region basis and provide technical assistance to the MPO and project sponsor for regional and project-level air quality analyses. Pursuant to the General Conformity Rule (40 CFR Part 51, Subpart W), a federal agency must perform a General Conformity Analysis for any Federal Action. The federal agency must then make a General Conformity Determination for any federal action in nonattainment or maintenance areas where the total of direct and indirect emissions of the applicable criteria pollutants or their precursors exceeds threshold levels. The proposed TRTP is considered a Federal Action since it requires federal approval and is, therefore, subject to a General Conformity Analysis.

The proposed Project is within the MDAB and the SCAB. The Project area in the MDAB is currently designated as a moderate nonattainment area for the 8-hour NAAQS for O₃ and PM₁₀. The Project area in the SCAB is currently designated as a severe non-attainment area for the 8-hour NAAQS for O₃; a serious nonattainment area for CO and PM₁₀; and a nonattainment area for PM_2.5. CARB submitted SCAQMD’s request for a redesignation of the CO attainment status of the SCAB from nonattainment to attainment to the USEPA in 2005. As of February 14, 2007, the USEPA has reviewed the request. It was then circulated and comments were solicited through March 16, 2007. After reviewing, and addressing all the comments, USEPA will decide whether to grant or deny the CO redesignation request. Currently it is unknown when USEPA will make this determination. The Project area in the two air basins is in attainment with the NAAQS for the other applicable criteria pollutants. The DeMinimis emission thresholds that trigger a General Conformity Determination for nonattainment and maintenance pollutants are specifically identified in the General Conformity Rule. The applicable thresholds for the proposed TRTP area are as follows:

•  MDAB

•  VOC - 50 tons per year

•  NO_X - 100 tons per year

•  PM₁₀ - 100 tons per year

•  SCAB

•  VOC - 25 tons per year

•  NO_X - 25 tons per year

•  CO - 100 tons per year

•  PM₁₀ - 70 tons per year

CARB oversees activities of local air quality management agencies, and is responsible for incorporating AQAPs and AQMPs from local air districts into the SIP for USEPA approval. CARB also maintains air quality monitoring stations throughout the state in conjunction with local air districts. Data collected at these stations are used by CARB to classify air basins as being in attainment or nonattainment with respect to each pollutant and to monitor progress in attaining air quality standards.

CARB has promulgated ambient air quality standards (AAQS) for O₃, PM₁₀, PM_2.5, CO, NO₂, SO₂, and Pb that are known as the California Ambient Air Quality Standards (CAAQS) and are typically more stringent than the USEPA’s standards, as shown in Table 4.4-2. Counties and metropolitan areas are classified as being in attainment or nonattainment with respect to federal and state AAQS. An area’s classification of attainment or nonattainment is determined by comparing actual monitored air pollutant concentrations with state and federal standards. More than 200 air monitoring stations are located in California and are part of the State and Local Air Monitoring Network. These stations are operated by CARB, APCDs or AQMDs, private contractors, and the National Park Service. Areas that do not have sufficient data for a determination are given an “unclassified” designation and are not considered to be nonattainment. The locations of air monitoring stations nearest to the proposed project are illustrated in Figure 4.4-2.

The California CAA requires that each area exceeding the state ambient air quality standards for O₃, CO, SO₂, and NO₂ must develop a plan aimed at achieving those standards (California Health and Safety Code 40911 et seq.). The California Health and Safety Code, Section 40914, requires air districts to design a plan that achieves an annual reduction in district-wide emissions of five percent or more, averaged every consecutive three-year period. To satisfy this requirement, the AQMDs and APCDs have to develop and implement air pollution reduction measures, which are described in their AQAPs/AQMPs and outline strategies for achieving the state ambient air quality standards for any criteria pollutants for which the region is classified as nonattainment.

4.4.3.1 Ozone

O₃ is a colorless gas that has a pungent odor and causes eye and lung irritation, reduces visibility, and damages crops. O₃ is a primary constituent of smog and is formed in the atmosphere in the presence of sunlight by a series of chemical reactions involving oxides of nitrogen (NO_X) and reactive organic gases (ROG). (Volatile organic compounds [VOC] and ROG describe the same category of pollutants and will be used interchangeably throughout this section). Because these reactions occur on a regional scale, O₃ is considered a regional air pollutant. Industrial fuel combustion and motor vehicles are primary sources of NO_X and ROG.

4.4.3.2 Particulate Matter

PM is generally composed of particles floating in the air, such as dust, soot, aerosols, fumes, and mists. Of particular concern is inhalable, respirable PM (i.e., PM₁₀). A subgroup of these particulates is fine particulates (i.e., PM_2.5), which have very different characteristics and potential health effects than coarse particulates (particles with aerodynamic diameter between 2.5 to 10 micrometers). Coarse particulates are generated by sources such as windblown dust, agricultural fields, and dust from vehicular traffic on unpaved roads. PM_2.5 is typically emitted from combustion activities such as industrial and manufacturing process equipment, vehicle exhaust, and residential wood-burning stoves and fireplaces. PM_2.5 is also formed in the atmosphere when gases such as SO₂, NO_X, and VOC emitted by combustion activities are transformed by chemical reactions in the air. Inhalation of PM₁₀ and PM_2.5 affects breathing and the respiratory system, and in particular, can damage lung tissue and contribute to cancer and premature death. There are separate standards for PM_2.5 because these fine particles can penetrate deep into the respiratory tract and cause their own unique adverse health effects.

4.4.3.3 Carbon Monoxide

CO is an odorless, colorless gas that can impair the transport of oxygen in the bloodstream, aggravate cardiovascular disease and cause fatigue, headache, confusion, and dizziness. CO forms through incomplete combustion of fuels in vehicles, wood stoves, industrial operations, and fireplaces. Vehicular exhaust is a major source of CO. CO tends to dissipate rapidly into the atmosphere and consequently is generally a concern at the local level, particularly at major road intersections.

4.4.3.4 Nitrogen Dioxide

NO₂ is a brownish, highly reactive gas that can irritate the lungs, cause pneumonia, and lower the resistance to respiratory infections. NO_X, which includes NO₂, is a key precursor to O₃ and acid rain. NO_X forms when fuel is burned at high temperatures and primarily from transportation sources and stationary fuel combustion sources such as electric utility and industrial boilers.

4.4.3.5 Sulfur Dioxide

SO₂ is a colorless acidic gas with a strong odor. High concentrations of SO₂ affect breathing and may aggravate existing respiratory and cardiovascular disease. SO₂ is also a primary contributor to acid deposition, which causes acidification of lakes and streams and can damage trees, crops, building materials, and statues. In addition, sulfur compounds in the air can contribute to visibility impairment. The major source category for SO₂ is fossil fuel-burning equipment.

4.4.3.6 Toxic Air Contaminants

Toxic Air Contaminants (TACs) have the potential to cause health effects such as increased risk of contracting cancer. TACs are considered separately from the criteria pollutants in the regulatory process. Ambient air quality standards (AAQS) have not been set for TACs because ambient TAC concentrations vary from area to area and are dependent on the type of emission sources within the region. Therefore, TACs are typically regulated on a source-by-source basis (e.g., type and amount of TACs emitted, proximity to nearest sensitive receptors [hospitals, school, daycare, residences]). Motor vehicles also emit TACs, and the amount is dependent on travel speed, type of fuel (e.g., diesel, gasoline), and engine size.

Table 4.4-3 presents the attainment status for KCAPCD, AVAQMD, and SCAQMD.

4.4.3.7 Naturally Occurring Asbestos

This discussion is limited to naturally-occurring asbestos (NOA) and the Memorandum Addressing Naturally Occurring Asbestos in CEQA Documents (Governor’s Office of Planning and Research, 2000). The purpose of the discussion is to establish the impact of NOA entrainment during construction.

Asbestos is a naturally occurring mineral distinguished from other minerals by the fact that its crystals form into long, thin fibers. The main source of NOA is ultramafic (i.e., silica poor) rocks that include serpentine. The fibers, when airborne, may enter the lungs and alveoli and remain there. When the fibers reach the alveoli, white blood cells attack them to try to remove them from the body. However, the fibers are not easily destroyed and eventually scarring of the lung tissue ensues. This scarring is called asbestosis and it leads to greatly diminished breathing capacity. Another result of asbestos exposure is lung cancer and mesothelioma. Both of these diseases are serious and frequently fatal. For these reasons, use of asbestos is limited and highly regulated. Identification of NOA in an area where soil may

TABLE 4.4-3
ATTAINMENT STATUS FOR KCAPCD, AVAQMD, AND SCAQMD

Source: USEPA, 2007.

be disturbed (e.g., construction or demolition activities) is important. The California Department of Conservation, Division of Mines and Geology (since renamed California Geological Society) has published a map of the state locating all areas where ultramafic rocks are present. This map indicates there are no ultramafic rocks in the vicinity of the Project location. Hence, the possibility of NOA becoming dustborne during construction is minimal. The need for minimization of NOA is limited to the control measures implemented for fugitive dust.

4.4.3.8 Air Quality Management Plan (AQMP) Conformance

The proposed Project is located in the MDAB under the jurisdiction of the KCAPCD and AVAQMD and in the SCAB under the jurisdiction of the SCAQMD. Conformity with the air quality management plans for each local air basin/district is discussed below.

4.4.3.9 Mojave Desert Air Basin

Based on the current nonattainment status for the areas overseen by KCAPCD and AVAQMD, AQMPs and AQAPs were developed by both air districts. The KCAPCD developed a 1993 O₃ Attainment Plan (state and federal attainment) and submits implementation progress reports to CARB on an annual basis. The AVAQMD has developed a 2004 O₃ Attainment Plan (state and federal attainment) and has prepared a list of measures to reduce PM emissions to meet state planning requirements.

4.4.3.9.1 Ozone. The AVAQMD 2004 O₃ Attainment Plan (AVAQMD, 2004) does not propose any new control measures beyond those identified in the former SCAQMD 1997 AQMP (SCAQMD, 1996), which included the Antelope Valley prior to its split into a separate jurisdiction in 1997. Of the control measures presented in the 1997 AQMP, the only measure that appears relevant to the proposed Project is the Federal Implementation Plan-11 (FIP-11), which proposes a strategy to regulate emissions from non-road internal combustion engines greater than or equal to 50 horsepower (hp). Therefore, the proposed Project would be consistent with the O₃ AQMP for the Antelope Valley.

KCAPCD’s California Clean Air Act O₃ AQAP was approved by CARB on February 18, 1993. Reduced ambient O₃ levels have occurred with implementation of retrofit controls for VOCs and NO_X on East Kern’s stationary sources. The nonattainment status of the O₃ CAAQS in Kern County is also influenced by pollutants transported from upwind air basins. In 1995, KCAPCD utilized California Health & Safety Code Section 40925(b) to modify its AQAP (i.e., delete control measures inappropriate for an area overwhelmingly impacted by transport). KCAPCD’s 1994 Federal Clean Air Act Amendments O₃ Attainment Demonstration projected attainment with NAAQS by 1999; Mojave monitoring data show the federal O₃ NAAQS of 0.12 parts per million (ppm) has been attained. Consequently, KCAPCD has been redesignated to attainment for the federal 1-hour O₃ NAAQS. However, attainment with O₃ CAAQS and the new O₃ 8-hour NAAQS of 0.08 ppm has not occurred. Due to O₃ CAAQS exceedances being caused by transported pollutants, Section 40925(c) (comprehensive plan revision) does not apply to KCAPCD, but does apply to upwind districts.

4.4.3.9.2 PM₁₀ As noted earlier, the AVAQMD prepared a list of measures to reduce PM emissions in 2005 (AVAQMD, 2005). Of the new control measures listed, the only applicable measures are fugitive dust control measures that would be integrated into AVAQMD Rule 403 - Fugitive Dust. SCE would be required to comply with all AVAQMD rules and regulations; therefore, the proposed Project would comply with the AVAQMD state PM attainment control measures.

The KCAPCD prepared a list of measures to reduce PM emissions. Of the control measures listed, the only applicable measures are fugitive dust control measures that would be integrated into Rule 402- Fugitive Dust Emissions. SCE would be required to comply with all KCAPCD rules and regulations; therefore, the proposed Project would comply with the KCAPCD state PM attainment control measures.

4.4.3.10 South Coast Air Basin

The SCAB is designated as a nonattainment area for both federal and state O₃ and PM₁₀ standards. O₃ is classified under the state’s 1-hour standard as extreme nonattainment. Under federal and state standards, PM₁₀ is designated as serious nonattainment. Federal CO standards are designated as nonattainment. The SCAB is also designated as nonattainment of the federal and state PM_2.5 standard. NO₂ and SO₂, the remaining federal and state criteria pollutants, are considered to be in attainment by the state and unclassified/attainment by federal standards.

SCAQMD is the lead agency for attaining timely compliance with federal standards within the SCAB. SCAQMD is responsible for developing those portions of the SIPs and AQMP that deal with certain stationary and area source controls and, in cooperation with the transportation planning agencies, the development of transportation control measures. CARB is responsible for submitting the SIP to the USEPA. SCAQMD is in the process of preparing the 2007 AQMP to remedy the current nonattainment status of PM₁₀, PM_2.5, and O₃. Various strategies are being discussed to reduce overall pollutants, which include reduction of SO_X, NO_X, and VOC emissions to attain the PM_2.5 standard, and requesting for a voluntary “bump-up” for the non-attainment classification of O₃ to reduce hardship to the region. Because the 2007 AQMP is still in the development process (as of the publication of this PEA, a revised draft 2007 AQMP has been published, but not finalized), the 2003 AQMP is considered to be the most current for the region and is used for the discussion below.

4.4.3.10.1 Ozone. The SCAQMD Governing Board adopted the 2003 AQMP on August 1, 2003 (SCAQMD, 2003). The 2003 AQMP updates the attainment demonstration for the federal 1-hour O₃ standard. (The initial attainment demonstration for the 8-hour O₃ standard is not yet due to the USEPA). The 2003 AQMP is consistent with and builds upon the approaches taken in the 1997 AQMP and the 1999 Amendments to the O₃ SIP for the SCAB for the attainment of the federal O₃ air quality standard. However, this revision points to the urgent need for additional emission reductions (beyond those incorporated in the 1997/99 Plan) from all sources, specifically those under the jurisdiction of CARB and the USEPA, which account for approximately 80 percent of the ozone precursor emissions in the air basin.

The AQMP identifies increasing the use of renewable power generation technologies as a potential long-term strategy. The TRTP is consistent with this strategy. Additionally, the proposed Project would result in negligible increase of operational emissions that are associated with maintenance activities. Therefore, the proposed Project would not conflict with the O₃ attainment plan.

4.4.3.10.2 PM₁₀. The SCAQMD Governing Board adopted the 2003 AQMP on August 1, 2003. The 2003 AQMP updates the attainment demonstration for the federal PM₁₀ standards. The 2003 AQMP is consistent with and builds upon the approaches taken in the 1997 AQMP. Two new best control measures (BCMs) listed in the 2003 AQMP could be applicable to the construction of the proposed Project: 1) BCM-07 Further PM₁₀ Reductions from Fugitive Dust Sources (which may be reflected in the recent revision to District Rule 403); and 2) Future Study Strategy (FSS)-06 Further Emission Reductions from In-Use Off-Road Equipment and Vehicles. SCE would be required to comply with the most recent version of the fugitive dust control Rule 403. However, the other AQMP control measure has not yet undergone rulemaking. The incorporation of Applicant Proposed Measures (APMs) and requiring the use of offroad equipment with newer, lower emission engines would reduce PM₁₀ emissions. Therefore, the proposed Project would not conflict with the PM₁₀ attainment plan.

4.4.3.10.3 Carbon Monoxide. CO attainment strategy in the 1994 AQMP has been proposed by the 1997 and 2003 AQMPs. The CO attainment strategy is primarily focused on emission reductions from onroad mobile sources (SCAQMD, 2003). While the entire non-desert portion of the SCAB is designated as a federal CO nonattainment area, the Project area does not actually experience any exceedances of the federal CO standards. In 2005, SCAQMD requested a redesignation from USEPA to reclassify the SCAB region as attainment with the CO NAAQS. As of February 14, 2007, USEPA has proposed to grant the SCAQMD’s request. However, due to procedural requirements, USEPA can not approve this request until after all public comments have been received and addressed, which technically ends on March 16, 2007. After all comments have been addressed, USEPA will make final determination of whether to redesignate the SCAB region as attainment

4.4.3.10.4 PM_2.5. The SCAQMD has not yet prepared its AQMP for PM_2.5. The PM_2.5 plan was not technically due until April 15, 2008, however, SCAQMD is debating whether it should be included in the Draft 2007 AQMP. The Draft 2007 AQMP is available for review as of the publication of this document, is currently being revised. It is uncertain whether it will include strategies to reduce PM_2.5 emissions.

4.4.3.11 Summary

The proposed Project would have to comply with all rules and regulations applicable at the time of the Project’s construction and operation. Additionally, applicable requirements identified in SCAQMD’s Rule 403, Fugitive Dust, would be implemented during construction of the proposed Project. The implementation of the requirements identified in Rule 403 would meet the intent of all relevant AQMP control measures required for the SCAB and MDAB.

4.4.3.12 Regulatory Framework

The majority of air pollutants associated with the implementation of the proposed Project would be generated during construction activities with a negligible amount emitted from operational activities. The only new sources of air pollutants generated from the operation of the proposed project are an emergency generator at the Whirlwind Substation and maintenance vehicles used by workers to traverse the transmission routes to ensure all equipment is operating properly. Prior to operating the generator, SCE would have to submit the necessary air permit application to AVAQMD and comply with their operating conditions. Therefore, there are very few direct air quality regulations that specifically regulate the proposed Project’s operational emission sources. However, the regulations that do apply, such as fugitive dust regulations, tend to be general and allow multiple means of achieving compliance. A description of the federal, state, and regional regulations that apply to the project is provided below.

4.4.3.12.1 Federal. The USEPA has issued a number of NAAQS. Pollutants regulated under these standards include O₃, NO₂, CO, PM₁₀, PM_2.5, and SO_X. The SCAQMD and CARB are the responsible agencies for providing attainment plans and for demonstrating attainment of these standards. The USEPA reviews and approves these plans and regulations that are designed to achieve attainment and maintain attainment status with the NAAQS. USEPA has a number of other regulations under the authority of the federal CAA (such as New Source Review, Prevention of Significant Deterioration [PSD], Title V permitting program, etc.); however, none of these regulations apply because the proposed Project would have no major operating stationary emission sources. Therefore, a PSD air quality impact analysis of the proposed Project’s impacts to the nearest mandatory Class I areas is not required.

The USEPA has on- and off-road engine emission reduction programs that indirectly affect the Project’s emissions through the phasing in of cleaner on- and off-road equipment engines.

The U.S. Department of Agriculture (USDA) Forest Service regulates the portion of the Project’s route that goes through the Angeles National Forest (ANF) and has prepared a Land Management Plan (LMP) for the ANF (USDA Forest Service, 2005a). The ANF’s strategies do not include any air quality strategies that would be significantly impacted by the construction or operation of the proposed Project. The ANF air quality strategies are limited to the following:

•  AIR 1: Minimize Smoke and Dust

•  AIR 2: Forest Air Quality Emissions

ANF strategy AIR 1 is very general and is directed to “control and reduce fugitive dust to protect human health, improve safety and moderate or eliminate environmental impacts.” The only action item of this of this strategy is to “incorporate visibility requirements into project plans.” ANF air quality strategy AIR 2 relates to providing an air quality inventory for prescribed burns and wildfires and, therefore, does not directly relate to the proposed Project’s construction and operational emissions.

Per Section 176(c) of the Clean Air Act Amendments of 1990, the Forest Service must make a determination of whether the proposed Project and Project alternatives conform to the SIP. However, if the total direct and indirect emissions from the proposed Project are below the GCR DeMinimisemission levels, then the proposed Project would be considered to be exempt from performing a comprehensive Air Quality Conformity Analysis and Determination, and would be considered conforming to the SIP. Otherwise, it has to be shown that the proposed Project would not conflict with the goals and objectives of the SIP.

4.4.3.12.2 State. CARB has issued a number of CAAQS. These standards include pollutants not covered under the NAAQS and also require more stringent standards than provided under the NAAQS. Pollutants regulated under these standards include O₃, NO₂, CO, PM₁₀, PM_2.5, SO₂, Pb, sulfates, hydrogen sulfide, vinyl chloride, and visibility reducing particles.

CARB, like the USEPA, also has on- and off-road engine emission reduction programs that indirectly affect the Project’s emissions through the phasing in of cleaner on- and off-road equipment engines. Additionally, CARB has a Portable Equipment Registration Program that allows owners or operators of portable engines and associated equipment to register their units under a statewide portable program to operate their equipment, which must meet specified program emission requirements throughout California without having to obtain individual permits from local air districts.

Greenhouse Gas. In addition to the CAAQS, the State of California implemented Executive Order S-03-05, issued by Governor Schwarzenegger, to reduce greenhouse gas (GHG) emissions (e.g., carbon dioxide [CO₂], methane), over various timeframes. This process led to the passage of Assembly Bill 32 (AB32), the Global Warming Solutions Act of 2006, which requires CO₂ emissions to be reduced from various sectors such as transportation (i.e., motor vehicles), natural gas usage and electricity generation. Senate Bill 1368 (SB1368) is a companion bill of AB32, which requires the California Public Utilities Commission (CPUC) and California Energy Commission (CEC) to establish a GHG emission performance standard for baseload generation from investor-owned utilities and local public owned utilities. The standards cannot exceed the GHG emission rate from a combined-cycle natural gas fired plant. This legislation also requires that all electricity provided to California, including imported electricity, must be generated from plants that meet the standards set by the CPUC and CEC.

As mandated in the Public Resources Code Section 25324, the CEC adopted a Strategic Transmission Investment Plan to identify the need for specific transmission projects to increase the physical capacity of the California electric transmission system; to achieve the Renewables Portfolio Standard; and to meet the GHG policy goals. One of the GHG policy goals is to reduce global warming effects by creating a CO₂ emissions performance standard for electricity generation.

4.4.3.12.3 Local. The proposed Project is routed through three separate local air district jurisdictions: KCAPCD, AVAQMD, and SCAQMD. The local jurisdictions are responsible for planning, implementing and enforcing federal, and state AAQS within their respective jurisdictions. The regulations of these agencies are primarily focused on stationary sources, indirect sources, and Best Construction Management Practices (BCMPs) or Best Available Control Measures (BACMs) to minimize air pollutants within their jurisdiction. However, portable engines used during construction that are larger than 50 hp and that are not registered under the CARB Portable Equipment Registration Program would need to obtain air operating permits from KCAPCD, AVAQMD, and SCAQMD. Similarly, stationary equipment, such as emergency generators, would also be required to comply with the applicable air district regulations (e.g., AVAQMD Rule 1110.2, Emissions from Stationary Nonroad & Portable Internal Combustion Engines).

All three agencies have visible emissions, nuisance, and fugitive dust regulations which are applicable to the proposed Project during construction activities. The specific regulations for each district are as follows:

•  KCAPCD Rule 401 - Visible Emissions

•  KCAPCD Rule 402 - Fugitive Dust

•  AVAQMD Rule 401 - Visible Emissions

•  AVAQMD Rule 402 - Nuisance

•  AVAQMD Rule 403 - Fugitive Dust

•  SCAQMD Rule 401 - Visible Emissions

•  SCAQMD Rule 402 - Nuisance

•  SCAQMD Rule 403 - Fugitive Dust

The intent of these rules is to limit the amount of visible emissions including fugitive dust generated from emission sources. Rule 401, Visible Emissions, is typically associated with opacity of exhaust plumes from stationary exhaust stacks. Rule 402, Nuisance, and 403, Fugitive Dust, are to ensure that pollutants emitted from any type of emission sources do not cause a public nuisance These rules are provided in Appendix G. To suppress fugitive dust from traveling offsite at construction activities, recommended control measures are provided in KCAPCD’s Rule 402, AVAQMD Rule 403, and SCAQMD Rule 403 to reduce overall fugitive dust emissions from man-made activities. Based on the description of the construction activities during the implementation of the proposed Project, the amount of soil to be excavated and the acreage of the disturbed areas would not classify the proposed Project as a “medium or large operations.” However, to minimize fugitive dust emissions, feasible fugitive dust control measures as stated in the applicable rules would be implemented to reduce potential impacts to sensitive receptors located nearby.

Most of the proposed construction through the MDAB is located in remote, rural areas and would not be expected to affect sensitive receptors. The construction activities through the SCAB and certain portion of MDAB are located in rural and urbanized areas with residences and commercial facilities located nearby. As such, SCE would take corrective actions including implementing the most stringent control measures specified in the fugitive dust rules so as to not create a nuisance to the sensitive receptors.

4.4.4 Significance Criteria

The Environmental Checklist Form provided in Appendix G of the State California Environmental Quality Act (CEQA) Guidelines contains a series of questions for determining whether a proposed project will have a “potentially significant impact” on air quality. According to these criteria, a project is determined to have a “potentially significant impact” on air quality if it would:

•  Conflict with or obstruct implementation of the applicable air quality plan?

•  Violate any air quality standard or contribute substantially to an existing or projected air quality violation?

•  Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is nonattainment under an applicable federal or state ambient air quality standard (including releasing emission which exceed quantitative thresholds for ozone precursors)?

•  Expose sensitive receptors to substantial pollutant concentrations?

•  Create objectionable odors affecting a substantial number of people?

According to the state CEQA guidelines, a “potentially significant impact” finding is appropriate if there is substantial evidence that an effect may be significant. Furthermore, CEQA Guidelines, §15382, define “significant effect on the environment” as a substantial adverse change in the physical conditions that exist in the area affected by the proposed project.

4.4.4.1 Regional Thresholds

In addition to the CEQA significance criteria, the local air quality districts in the proposed Project area have established significance thresholds to assist the Lead Agencies in determining whether a project may have a significant air quality impact. As such, if the proposed Project’s emissions are expected to meet or exceed the significance thresholds established by the local AQMD or APCD the Project is considered to have significant air quality impact. If a project is considered to have significant air quality impact then feasible mitigation measures would have to be implemented to reduce project emissions to a level considered less than significant or to the greatest extent feasible. KCAPCD, AVAQMD, and SCAQMD have established regional thresholds of significance for construction and/or operational activities as shown below in Table 4.4-4.

TABLE 4.4-4
REGIONAL AIR QUALITY THRESHOLDS¹

¹   Sources: AVAQMD 2002; KCAPCD 2000, SCAQMD 2006.

²   Daily significance thresholds are only applicable to projects with duration of less than 12 months (i.e., are not applicable to TRTP).

4.4.4.2 SCAQMD Ambient Air Quality Significance Criteria

In addition to the regional significance thresholds provided in Table 4.4-4, SCAQMD also created ambient air concentrations thresholds (see Table 4.4-5) that are also used to determine the significance of air quality impacts.

TABLE 4.4-5
SCAQMD AMBIENT AIR CONCENTRATION SIGNIFICANCE THRESHOLDS¹

¹   Source: SCAQMD CEQA Handbook (SCAQMD, 1993).

²   Ambient air quality thresholds for criteria pollutants based on SCAQMD Rule 1303, Table A-2 unless otherwise stated.

³   Ambient air quality threshold based on SCAQMD Rule 403.

Key: ppm = parts per million; µg/m³ = micrograms per cubic meter; ≥ greater than or equal to.

Note that O₃ is not included in Table 4.4-4 or 4.4-5 since O₃ is not directly emitted from stationary or mobile sources. O₃ is formed as a result of chemical reactions in the atmosphere between NO_X and VOCs; therefore, it is not directly regulated. Furthermore, SCAQMD created construction and operational localized significance thresholds look-up tables to determine localized air quality impacts. This is a voluntary method to provide additional information to the project developer and/or Lead Agency to determine whether additional mitigation measures should be implemented to minimize local air quality impacts. The look-up tables can only be used for projects less than 5 acres in dimensions and requires knowledge of the distance from the project site to the nearest offsite receptor (e.g., residences, hospital, daycare). If the project site is larger than 5 acres, then air quality dispersion modeling is required to assess local air quality impacts (i.e., determine whether the project would create significant air quality impacts on a local level).

4.4.4.3 Federal General Conformity Significance Criteria

In addition to the regional significance criteria, the GCR applicability emission levels shown in Table 4.4-6 would apply to those areas in nonattainment or maintenance for CO, NO₂, SO₂, PM₁₀, and O₃. DeMinimis emission levels were created for these criteria pollutants,

TABLE 4.4-6
GENERAL CONFORMITY APPLICABILITY EMISSION LEVELS

which include pre-cursor pollutants such as VOC and NO_X that contribute to the formation of O₃. If the total direct and indirect emissions from the proposed Project are below the GCR DeMinimisemission levels, then the proposed project would be considered to be exempt from performing a comprehensive Air Quality Conformity Analysis and Determination, and would be considered conforming to the SIP. Otherwise, it has to be shown that the proposed Project would not conflict with the goals and objectives of the SIP.

4.4.5 Applicant Proposed Measures

Table 4.4-7 presents SCE’s air quality-related APMs to minimize air quality impacts associated with construction of the TRTP. The impact analysis assumes that the applicable APMs would be implemented as defined in the table to reduce air quality impacts.

TABLE 4.4-7
APPLICANT PROPOSED MEASURES

4.4.6 Proposed Project and Alternatives

4.4.6.1 Segment 4

4.4.6.1.1 Environmental Setting. Segment 4 extends from approximately 15 miles south of the City of Tehachapi, in eastern Kern County, to the western edge of the City of Lancaster in northeastern Los Angeles County. Approximately 35 percent of this segment is located in the MDAB within the jurisdiction of KCAPCD. The KCAPCD has jurisdiction over the eastern half of Kern County. This region includes the incorporated cities of Mojave, Tehachapi, and California City. The remaining 65 percent of Segment 4 is located in the northern portion of Los Angeles County within the jurisdiction of the AVAQMD. AVAQMD has jurisdiction over the northern, desert portion Los Angeles County. This region includes the incorporated cities of Lancaster and Palmdale, Air Force Plant 42, and the southern portion of Edwards Air Force Base. The allocation (i.e., percentage) of the segment for each county and air district is based on physical distances (i.e., approximately 6.9 miles within Kern County and 12.8 miles within Los Angeles County).

Meteorological (i.e., short-term) and climatological (i.e., long-term) conditions influence ambient air quality. Segment 4 of the proposed Project is located in the south-central portion of the SCAB. Air pollution from the SCAB is carried over the San Gabriel and San Bernardino mountains, heavily impacting the area just to the north. The area downwind of the pass through the Tehachapi Mountains gets air pollution from the San Joaquin Air Basin (SJAB).

The majority of Segment 4 occupies rural, uninhabited environments. Segment 4 is located at an elevation range of about 1,000 feet to 2,000 feet. This area is separated from the southern California coastal and central California Valley regions by mountains. The proposed Project area is bordered in the north and northwest by the Tehachapi Mountains; the San Gabriel Mountains to the west, south, and southwest; and the Mojave Desert immediately to the east. During the summer months, the proposed Project area is generally influenced by a Pacific Subtropical High cell that sits off the coast, inhibiting cloud formation and encouraging daytime solar heating. The MDAB is classified as a dry-hot desert climate, with portions classified as dry-very hot desert.

Temperatures for the area are markedly higher in the summer months. Using the 32-year (1974 to 2006) monthly climate summary from the nearest meteorological station, the Western Regional Climate Center #044749 at Lancaster, located near the southern end of Segment 4, the average maximum temperature was 95.3 degrees Fahrenheit (°F) in August, with an average minimum temperature of 29.1°F in December. Seasonal temperature differences are due to the lack of marine influence.

During the winter months, a semi-permanent, subtropical high-pressure system over the eastern Pacific Ocean moves south, allowing frontal systems that normally are blocked and forced to the north of the area to pass through the region. This results in majority of the area’s annual precipitation, which totals about 7.73 inches. Average maximum rainfall occurs in February (1.89 inches), with minimum rainfall in June (0.05 inches)(Western Regional Climate Center, #044749).

The relative humidity is fairly low, averaging 30 to 60 percent in the early morning hours and 10 to 20 percent in the late afternoon. During the hottest part of the day, the relative humidity averages below 10 percent. These conditions promote intense heat during the day and marked cooling at night.

On occasion during fall and winter months, a high-pressure system develops over Nevada and Utah and pushes air south and southwestward over the San Gabriel and San Bernardino mountains. The resulting winds are known as Santa Ana winds. Santa Ana winds can be very strong, with wind speeds through mountain passes sometimes exceeding 100 kilometers (km) per hour (62 miles per hour [mph]), and are usually warm and dry. They tend to clear the Air Basin of accumulated air pollutants, but can also cause dust storms and high particulate levels.

Air Quality Standards and Existing Concentrations. Ambient air quality standards and federal, state, and local regulations are discussed in Section 4.4.3 and, therefore, are not discussed in detail in this section. The nearest air monitoring station to Segment 4 is located in the City of Lancaster at 43301 Division Street. Table 4.4-8 summarizes the measured criteria pollutant concentrations over the past three years at this station.

Ozone. As shown in Table 4.4-8, O₃ concentrations have exceeded federal and state AAQS over the past three years. These violations, along with other violations throughout eastern Kern County and northern Los Angeles County, resulted in the region being classified as nonattainment for the state’s 1‑hour, and federal and state’s 8‑hour O₃ standards.

Particulate Matter. Measured concentrations at the monitoring stations have not exceeded federal 24‑hour PM₁₀ standards over the past three years. However, exceedances of the state PM₁₀ standards have occurred over the past three years. These measured concentrations have contributed to the region being classified as nonattainment for the state PM₁₀ standards.

Carbon Monoxide. CO concentrations recorded at the nearby monitoring station are well below federal and state 1‑hour and 8‑hour standards; therefore, this portion of eastern Kern County is in attainment, while all of Los Angeles County is considered to be in nonattainment of the CO standards.

Nitrogen Dioxide. The data in Table 4.4-8 show that measured concentrations of NO₂ have consistently remained well below the federal and state standards. With similar trends throughout the region (and state), the area is well within federal and state NO₂ standards.

Sulfur Dioxide. SO₂ is not measured at the Lancaster station. However, the Project area is designated as unclassified for federal and attainment for state standards.

4.4.6.1.2 Impact Analysis. The air quality impacts of this segment are discussed below with regards to the applicable significance thresholds (i.e., KCAPCD and AVAQMD), the GCR DeMinimis levels, and the significance criterion as described in Section 4.4.4.

Would the proposed Project conflict with or obstruct implementation of the applicable air quality plan?

Air quality plans are strategies designed to reduce long-term operational emissions and comply with the federal and State ambient air quality standards. The operation of Segment 4 would generate emissions considered to be negligible. Operation emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. As previously mentioned,

TABLE 4.4-8
SUMMARY OF AMBIENT AIR DATA AT MONITORING STATIONS IN LANCASTER, 2004-2006

¹   Station: LAN (Lancaster).

²   Exceeds the federal standard.

³    Exceeds the state standard.

⁴    Federal/state values. The federal and state values differ due to differences in sampling methods and criteria.

⁵    The federal annual PM₁₀ standards was revoked as of December 17, 2006.

-- = Data not collected at the monitoring station

µg/m³ = micrograms per cubic meter; ppm = parts per million; conc. = concentration

Source. CARB, 2006.

operation phase emissions are expected to be negligible and below significance thresholds, and would not conflict with or obstruct the applicable air quality plan. Therefore, impacts from operation of Segment 4 would be less than significant.

Would the proposed Project violate any air quality standards or contribute substantially to an existing or projected air quality violation?

To determine whether implementation of Segment 4 would violate any air quality standards or contribute substantially to an existing or projected air quality violation, a worst-case scenario approach was taken to ensure that all potential air quality impacts were assessed. As such, emissions occurring during peak construction activities were quantified and used to determine air quality impacts. Segment 4 construction emissions are presented in Table 4.4-9.

TABLE 4.4-9
SEGMENT 4 CONSTRUCTION EMISSION/AIR DISTRICT REGIONAL EMISSION THRESHOLD COMPARISON

¹   Daily significance thresholds are only applicable to single phased projects with duration of less than 12 months, therefore, not applicable to this segment.

Construction and Operation Impacts. Construction of Segment 4 would result in short-term impacts to ambient air quality. Construction activities are projected to last 24 months and start in April 2009 and end in April 2011. This segment requires the following construction tasks:

•  Surveying

•  Setting up marshalling yards

•  Roads and landing work

•  Removal of existing foundations, conductors, towers, and overhead ground wire (OHGW)

•  Installing new foundations, conductors, OHGW for approximately 165 new lattice steel towers (LSTs)

•  Restoration of impacted areas

Annual construction emissions were estimated and compared to the AVAQMD annual thresholds to determine significance of air quality impacts (see Table 4.4-9). KCAPCD does not have significance thresholds for construction activities, therefore, data is only provided for informational purposes.

Based on a comparison of daily emissions shown in Table 4.4-9 with significance thresholds presented in Table 4.4-4, daily construction emissions would exceed the AVAQMD’s daily significance thresholds for NO_X and VOC, but would not exceed the PM_10, CO, and SO_X thresholds. However, it should be noted that the daily significance thresholds are only used for multi-phased projects with phases shorter than one year (AVAQMD, 2002). This proposed Project is multi-phased with construction of Segment 4 lasting approximately 24 months, therefore, daily significance thresholds do not apply to this segment. Hence, the annual thresholds are used to determine significance of air quality impacts from this segment. As shown above, peak construction emissions in year 2010 do not exceed the AVAQMD’s annual thresholds, therefore, are considered to have a less than significant impact. Although the annual significance thresholds are not exceeded, the APMs identified in Section 4.4.5 would reduce overall air quality impacts. As previously stated, emissions that would result from the operation of the electrical transmission system are considered to be negligible. Hence, the construction and operation of Segment 4 would not violate any air quality standard nor contribute substantially to an existing or projected air quality violation. Thus, impacts would be less than significant.

Would the proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the project region is classified as non-attainment under an applicable federal or state AAQS (including releasing emissions which exceed quantitative thresholds for ozone precursors)?

The MDAB is designated as non-attainment for 8-hour O₃, PM₁₀, and PM_2.5. To determine whether the construction and operation of Segment 4 would result in a cumulatively considerable net increase of any non-attainment criteria pollutant, the peak year construction emissions are compared to the DeMinimis thresholds and discussed below.

Federal General Conformity Rule. If the Project were to cause annual emissions that exceed the GCR DeMinimis thresholds, SCE would be required to prepare a comprehensive Air Quality Conformity Analysis and Determination. Based on the current proposed Project schedule, the maximum annual construction emissions for Segment 4 would occur in 2010. The estimated annual emissions for 2010 (peak construction year) in the MDAB (i.e., areas within the KCAPCD and AVAQMD jurisdictions), compared to the respective GCR DeMinimisthresholds are provided in Table 4.4-10.

TABLE 4.4-10
SEGMENT 4 EMISSIONS/GENERAL CONFORMITY EMISSIONS THRESHOLD COMPARISON

As shown in Table 4.4-10, the proposed Project’s estimated construction emissions are less than the GCR DeMinimis thresholds for the MDAB region, and no mitigation measures would be required. Therefore, construction and operation of Segment 4 of the TRTP would not result in a cumulatively considerable net increase of any criteria pollutant for which the project region is classified as non-attainment under an applicable federal or state AAQS. As such, the construction of Segment 4 is considered to be conforming with the SIP and AQMP. The detailed annual emissions calculations and associated assumptions used in the calculations are provided in Appendix G. Thus, impacts would be expected to be less than significant.

Would the proposed Project expose sensitive receptors to substantial pollutant concentrations?

Most of the proposed construction through the MDAB is in remote and rural areas which should not affect sensitive receptors. A review of aerial photography for the area surrounding Segment 4 shows that this area has a very low residential population with no other sensitive receptors nearby (i.e., schools, hospitals, residences) located near the R-O-W. After the construction of Segment 4, operational emissions associated with maintenance activities would be expected to be generated from the operation of maintenance vehicles driven to the site, parked for a short duration, then driven off, and therefore are considered negligible. The emissions generated from the construction of the electrical transmission system along Segment 4 would not expose nearby sensitive receptors to substantial pollutant concentrations. Operational emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles and/or helicopters used by workers to visit the substations and patrol the T/L routes. Thus, impacts from construction and operation of Segment 4 would be less than significant.

Would the proposed Project create objectionable odors that would affect a substantial amount of people?

The use of diesel construction equipment during various construction phases may generate odors that are considered to be a nuisance. Diesel equipment emits a distinctive odor that may be considered offensive to certain individuals. These odors would be temporary and would not affect a substantial number of people. The operation of the new substation, Whirlwind, would be expected to emit minimal odor (i.e., diesel emergency generator); however, the substation equipment would be enclosed within the fenced property and away from all sensitive receptors, therefore, any odor emitted would most likely only be detected by workers servicing the equipment. Therefore, the construction and operation of Segment 4 facilities would not create objectionable odors affecting a substantial number of people. Thus, odor impacts from construction and operation of Segment 4 would be less than significant.

Summary of Air Quality Impacts. As described in the previous subsections, the indirect and direct emissions associated with implementation of Segment 4 are not expected to exceed the AVAQMD annual significance thresholds and, therefore, would not conflict with or obstruct implementation of the applicable air quality plan, violate any air quality standard or contribute to an existing or projected air quality violation, result in a cumulatively considerable net increase of any nonattainment criteria pollutant, expose sensitive receptors to a substantial amount of pollutants, or create objectionable odors. Hence, the construction of Segment 4 is considered to be consistent with the SIP.

4.4.6.1.3 Mitigation Measures. The comparison of construction emissions generated during the implementation of the proposed Segment 4 with the applicable pollutant thresholds show that air quality impacts are considered to be less than significant. The aforementioned APMs have been incorporated into the Project design, therefore, potentially significant impacts have been avoided or reduced to a less-than-significant level, and no mitigation is required.

4.4.6.1.4 Impact Significance After Mitigation Measure Application. The potential impacts to air quality associated with construction and operation of Segment 4 are considered to be less than significant.

4.4.6.2 Segment 5

4.4.6.2.1 Environmental Setting. Segment 5 extends from the Antelope Substation, located in the western portion of the City of Lancaster, to the Vincent Substation. Segment 5 is located in north central Los Angeles County within the MDAB. This portion of Los Angeles County is within AVAQMD jurisdiction.

Meteorological (short-term) and climatological (long-term) conditions influence ambient air quality. Segment 5 of the proposed Project is located in the southern portion of the MDAB. Air quality in the MDAB is influenced by air pollution transported from the SCAB and San Joaquin Air Basin (SJAB). Air pollution from the SCAB moves through the San Gabriel and San Bernardino mountains, heavily impacting the southern region of the MDAB. The northern portion of the MDAB is affected by air pollution transported from the SJAB through the Tehachapi Mountains. The southern edge of the MDAB that borders the SCAB is the most heavily polluted portion of the entire basin. This is contributed to by the transport of pollutants from the SCAB and also because most of the air basin’s population is concentrated along this border.

Segment 5 traverses the western edges of both the City of Lancaster and the City of Palmdale. Segment 5 is located at an elevation range of about 1,000 feet to 2,000 feet. This area is separated from the southern California coastal and central California Valley regions by mountains. The proposed Project area is bordered to the north by the Tehachapi Mountains, the San Gabriel Mountains to the south and west, and the Mojave Desert immediately to the east. During the summer months the proposed Project area is generally influenced by a Pacific Subtropical High cell that sits off the coast, inhibiting cloud formation and encouraging daytime solar heating. The MDAB is classified as a dry-hot desert climate, with portions classified as dry-very hot desert.

Temperatures for the area are markedly higher in the summer months. Using the 75-year (1931 to 2006) monthly climate summary from the nearest meteorological station, the Western Regional Climate Center #046624 at Palmdale, located near the central portion of Segment 5, the average maximum temperature was 97.5°F in July, with an average minimum temperature of 32.4°F in January. Seasonal temperature differences are due to the lack of marine influence.

During the winter months, a semi-permanent, subtropical high-pressure system over the eastern Pacific Ocean moves south, allowing frontal systems that normally are blocked and forced to the north of the area to pass through the region. This results in majority of the area’s annual precipitation, which totals about 7.9 inches. Average maximum rainfall occurs in February (1.65 inches), with minimum rainfall in June (0.04 inch)(Western Regional Climate Center, #046624).

The relative humidity is fairly low, averaging 30 to 60 percent in the early morning hours and 10 to 20 percent in the late afternoon. During the hottest part of the day, the relative humidity averages below 10 percent. These conditions promote intense heat during the day and marked cooling at night.

On occasion during the fall and winter months, a high-pressure system develops over Nevada and Utah and pushes air south and southwestward over the San Gabriel and San Bernardino mountains. The resulting winds are known as Santa Ana winds. Santa Ana winds can be very strong, with wind speeds through mountain passes sometimes exceeding 100 km per hour (62 mph), and are usually warm and dry. They tend to clear the air basin of accumulated air pollutants, but can also cause dust storms and high particulate levels.

Air Quality Standards and Existing Concentrations. Ambient air quality standards and federal, state, and local regulations are discussed in Section 4.4.3 and, therefore, are not repeated here. The nearest air monitoring station to Segment 5 is located in the City of Lancaster. Data for this station is presented in Table 4.4-8 and discussed in Section 4.4.6.1.

4.4.6.2.2 Impact Analysis. The air quality impacts of Segment 5 are discussed below with regard to the applicable significance thresholds established by AVAQMD, the GCR DeMinimis levels, and the significance criterion presented in Section 4.4.4.

Would the proposed Project conflict with or obstruct implementation of the applicable air quality plan?

Air quality plans are strategies designed to reduce long-term operational emissions and comply with the federal and State ambient air quality standards. The operation of Segment 5 would generate emissions considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. As previously mentioned, operation emissions are expected to be negligible and well below significance thresholds, and would not conflict with or obstruct the applicable air quality plan. Therefore, impacts from operation of Segment 5 would be less than significant.

Would the proposed Project violate any air quality standards or contribute substantially to an existing or projected air quality violation?

To determine whether implementation of Segment 5 would violate any air quality standards or contribute substantially to an existing or projected air quality violation, a worst-case scenario approach was taken to ensure that all potential air quality impacts were assessed. As such, emissions occurring during peak construction activities were quantified and used to determine air quality impacts.

Construction and Operation Impacts. Construction of Segment 5 would result in short-term impacts to ambient air quality. Construction activities are projected to last 21 months and start in July 2009 and end in April 2011. This segment requires the following construction tasks:

•  Surveying

•  Setting up marshalling yards

•  Roads and landing work

•  Removal of existing foundations, conductors, towers, and overhead ground wire (OHGW)

•  Installing new foundations, conductors, OHGW for approximately 67 new LSTs

•  Restoration of impacted areas

Annual construction emissions were estimated and compared to the AVAQMD annual thresholds to determine significance of air quality impacts (see Table 4.4-11). Detailed calculations are provided in Appendix G.

A comparison of daily emissions is shown in Table 4.4-11 with significance thresholds presented in Table 4.4-4. Daily construction emissions would exceed the AVAQMD’s daily significance thresholds for NO_X and VOC, but would not exceed the PM_10, CO, and SO_X thresholds. However, it is noted that the daily thresholds are only used for multi-phased projects with phases shorter than one year (AVAQMD, 2002). This proposed Project is multi-phased with construction of Segment 5 lasting approximately 21 months; therefore, daily significance thresholds do not apply to this segment. Hence, the annual thresholds are used to determine significance of air quality impacts from this segment. As shown below, peak construction emissions in year 2010 do not exceed the AVAQMD’s annual thresholds; therefore, construction of Segment 5 would result in a less than significant impact. Although the annual significance thresholds are not exceeded, the APMs identified in Section 4.4.5 would be implemented to reduce air quality impacts.

TABLE 4.4-11
SEGMENT 5 CONSTRUCTION EMISSION/AIR DISTRICT REGIONAL EMISSION THRESHOLD COMPARISON

¹   Daily significance thresholds are only applicable to single phased projects with duration of less than 12 months and, therefore, are not applicable to this segment.

Operational emissions that would result from the electrical transmission system are considered to be negligible. Hence, the construction and operation of Segment 5 would not violate any air quality standard nor contribute substantially to an existing or projected air quality violation. Thus, impacts would be less than significant.

Would the proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the project region is classified as nonattainment under an applicable federal or state AAQS (including releasing emissions which exceed quantitative thresholds for ozone precursors)?

The MDAB is designated as non-attainment for 8-hour O₃, PM₁₀, and PM_2.5. To determine whether the construction and operation of Segment 5 would result in a cumulatively considerable net increase of any non-attainment criteria pollutant, the peak year construction emissions are compared to the DeMinimis thresholds.

Federal General Conformity Rule. If the Project were to cause annual emissions that exceed the GCR DeMinimis thresholds, SCE would be required to prepare a comprehensive Air Quality Conformity Analysis and Determination. Based on the current proposed Project schedule, the maximum annual construction emissions for Segment 5 would occur in 2010. The estimated annual emissions for 2010 (peak construction year) in the MDAB (i.e., areas within the AVAQMD jurisdiction), compared to the respective GCR DeMinimisthresholds are provided in Table 4.4-12.

TABLE 4.4-12
PROPOSED PROJECT EMISSIONS/GENERAL CONFORMITY EMISSIONS THRESHOLD COMPARISON

As shown in Table 4.4-12, the proposed Project’s estimated construction emissions are less than the GCR DeMinimis thresholds for the MDAB region, and no mitigation measures would be required. The implementation of Segment 5 of the TRTP would not result in a cumulatively considerable net increase of any criteria pollutant for which the project region is classified as nonattainment under an applicable federal or state AAQS. As such, the construction of Segment 5 is considered to be conforming with the SIP and AQMP. The detailed annual emissions calculations and associated assumptions used in the calculations are provided in Appendix G.

Would the proposed Project expose sensitive receptors to substantial pollutant concentrations?

Most of the proposed construction through the MDAB is in remote and rural areas which should not affect sensitive receptors. The cities of Lancaster and Palmdale have ongoing developments (e.g., Anaverde, Ritter Ranch, and Quail Valley) that may lead to substantial growth near Segment 5. However, existing conditions include a few residences nearby the proposed T/L R-O-W with no other sensitive receptors nearby (i.e., schools, hospitals, residences). Due to the lack of sensitive receptors near the construction sites, and the construction emissions being less than the annual significance thresholds, the impacts to sensitive receptors located in the MDAB are considered to be less than significant. The emissions generated from the construction of the electrical transmission system along Segment 5 would not expose nearby sensitive receptors to substantial pollutant concentrations. Operational emissions would not expose nearby sensitive receptors to substantial pollutant concentrations because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. Thus, impacts from construction and operation of Segment 5 would be considered to be less than significant.

Would the proposed Project create objectionable odors that would affect a substantial amount of people?

The use of diesel construction equipment during various construction phases may generate odors that are considered to be a nuisance. Diesel equipment emits a distinctive odor that may be considered offensive to certain individuals. These odors would be temporary and would not affect a substantial number of people. Therefore, the odor impacts from the construction and operation of Segment 5 would be less than significant and would not create objectionable odors that would affect a substantial amount of people. Thus, impacts from construction and operation of Segment 5 would be considered to be less than significant.

Summary of Air Quality Impacts. The indirect and direct emissions associated with implementation of Segment 5 would not exceed the AVAQMD annual significance thresholds; therefore, implementation of Segment 5 would not conflict with or obstruct implementation of the applicable air quality plan, violate any air quality standard or contribute to an existing or projected air quality violation, result in a cumulatively considerable net increase of any nonattainment criteria pollutant, expose sensitive receptors to a substantial amount of pollutants, or create objectionable odors. Hence, the construction of Segment 5 is considered to be consistent with the SIP.

4.4.6.2.3 Mitigation Measures. The comparison of construction emissions generated during the implementation of proposed Segment 5 with the applicable pollutant thresholds show that air quality impacts would be less than significant. As such, mitigation measures are not required to be implemented.

4.4.6.2.4 Impact Significance after Mitigation Measure Application. The construction of Segment 5 would not be expected to create significant air quality impacts because annual construction emissions presented are well below AVAQMD’s significance thresholds. The potential impacts to air quality associated with construction and operation of Segment 5 are considered to be less than significant.

4.4.6.3 Segment 6

4.4.6.3.1 Environmental Setting. Segment 6 of SCE’s TRTP extends southeasterly from the Vincent Substation through the southern most boundary of ANF, near the incorporated City of Duarte in Los Angeles County. Approximately 30 percent of this segment is located in the MDAB within the jurisdiction of the AVAQMD. The remaining 70 percent of Segment 6 is located in the SCAB within the jurisdiction of the SCAQMD. The allocation (i.e., percentage) of the segment for each county and air district is based on physical distances (i.e., approximately 8.2 miles within MDAB and 18.7 miles within SCAB).

Segment 6 is located in the north-central portion of the SCAB. The basin forms a low plain, bounded on the west by the Pacific Ocean, and surrounded on the other sides by mountains, which channel and confine air flow. The air basin both transports to and receives air pollutants from the coastal portions of Ventura and Santa Barbara counties in the South Central Coast Air Basin. The air basin also receives air pollutants from oil and gas development operations on the outer continental shelf in Santa Monica Bay and San Pedro Channel.

Nearly the entire length of Segment 6 occupies land in the ANF, which is located in the San Gabriel Mountain Range. The elevation for this segment ranges from 550 feet to 5,000 feet. The San Gabriel Mountains surround Segment 6 to the north, south, east, and west. This area has a Mediterranean climate, which ischaracterized by warm, dry summers and mild winters and is dominated by a semi‑permanent, high‑pressure cell located over the Pacific Ocean.

Temperatures for the area are markedly higher during the summer months. Using the 79-year (1927 to 2006) monthly climate summary from the nearest meteorological station (Western Regional Climate Center #046719 at Pasadena, located approximately 8 miles west of the Project area), the average maximum temperature was 89.5°F in August, with an average minimum temperature of 43.1°F in January. Seasonal temperature differences are due to the lack of marine influence.

During the winter months, a semi-permanent, subtropical high-pressure system over the eastern Pacific Ocean moves south, allowing frontal systems that normally are blocked and forced to the north of the area to pass through the region. This results in majority of the area’s annual precipitation, which totals about 20.34 inches. Average maximum rainfall occurs in February (4.66 inches), with minimum rainfall in July (0.02 inches)(Western Regional Climate Center, #046719).

The relative humidity is fairly low, averaging 30 to 60 percent in the early morning hours and 10 to 20 percent in the late afternoon. During the hottest part of the day, the relative humidity averages below 10 percent. These conditions promote intense heat during the day and marked cooling at night.

On occasion during fall and winter months, a high-pressure system develops over Nevada and Utah and pushes air south and southwestward over the San Gabriel and San Bernardino mountains. The resulting winds are known as Santa Ana winds. Santa Ana winds can be very strong, with wind speeds through mountain passes sometimes exceeding 100 km per hour (62 mph), and are usually warm and dry. They tend to clear the air basin of accumulated air pollutants, but can also cause dust storms and high particulate levels.

The topographical features in the region around the Project area restrict air movement through and out of the basin (especially in the northern portion). The San Gabriel and San Bernardino mountains hinder wind access into the valley from the northeast, north, east; the San Jacinto Mountains are to the southeast of the basin; the Santa Ana Mountains hinder winds from the south causing weak air flow throughout the basin.

Air Quality Standards and Existing Concentrations. Ambient air quality standards and federal, state, and local regulations are discussed in Section 4.4.3, and therefore, are not repeated in this section. The Azusa air monitoring station is located near the southern end of Segment 6. Table 4.4-13 summarizes the measured criteria pollutant concentrations over the past three years at this station.

Ozone. As shown in Table 4.4-13, O₃ concentrations have exceeded federal and state AAQS between 2003 and 2006. These violations, along with other violations throughout the Los Angeles County region, resulted in the region being classified as nonattainment for the state’s 1‑hour, and federal and state’s 8‑hour O₃ standards.

Particulate Matter. Measured concentrations at the monitoring stations have not exceeded federal 24‑hour PM₁₀ standards over the past three years. However, exceedances of the state PM₁₀ standards have occurred over the past three years. These measured concentrations have contributed to the region being classified as nonattainment for the state PM₁₀ standards.

Carbon Monoxide. CO concentrations recorded at the nearby monitoring station are well below federal and state 1‑hour and 8‑hour standards. However, this portion of Los Angeles County is considered to be nonattainment.

Nitrogen Dioxide. Data in Table 4.4-13 show that measured concentrations of NO₂ have consistently remained well below the federal and state standards. With similar trends throughout the region (and state), the area is well within federal and state NO₂ standards.

Sulfur Dioxide. Sulfur dioxide is not measured at the Azusa station. However, the Project area is designated as unclassified for federal and attainment for state standards.

4.4.6.3.2 Impact Analysis. The air quality impacts for Segment 6 are discussed below with regards to the applicable significance thresholds (i.e., AVAQMD and SCAQMD), the GCR DeMinimis levels, and the significance criterion as described in Section 4.4.4.

TABLE 4.4-13
SUMMARY OF AMBIENT AIR DATA AT MONITORING STATION IN AZUSA NEAR SEGMENT 6, 2004‑2006

¹    Station: AZU (Azusa).

²   Exceeds the federal standard.

³   Exceeds the state standard.

⁴   Federal/state values. The federal and state values differ due to differences in sampling methods and criteria.

⁵   The federal annual PM₁₀ standards were revoked as of December 17, 2006.

-- = Data not collected at the monitoring station; µg/m³ = micrograms per cubic meter; ppm = parts per million; conc. = concentration.

Source: CARB, 2006c.

Would the proposed Project conflict with or obstruct implementation of the applicable air quality plan?

Air quality plans are strategies designed to reduce long-term operational emissions and comply with the federal and State ambient air quality standards. Operational emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. As previously mentioned, operation emissions are expected to be negligible and below significance thresholds, and would not conflict with or obstruct the applicable air quality plan. Therefore, impacts from operation of Segment 6 would be less than significant.

Would the proposed Project violate any air quality standards or contribute substantially to an existing or projected air quality violation?

To determine whether implementation of Segment 6 would violate any air quality standards or contribute substantially to an existing or projected air quality violation, a worst-case scenario approach was taken to ensure that all potential air quality impacts are assessed. As such, emissions occurring during peak construction activities were quantified and used to determine air quality impacts. Segment 6 construction emissions are presented in
Table 4.4-14.

Construction and Operation Emissions. Construction of Segment 6 of the proposed Project would result in short-term impacts to ambient air quality. Construction activities are projected to last 36 months and start in April 2009 and end in April 2012. This segment requires the following construction tasks:

•  Construction inspection

•  Surveying

•  Setting up marshalling yards

•  Roads and landing work

•  Installing guard poles

•  Removal of existing foundations, conductors, towers, and OHGW

•  Install new foundations, conductors, OHGW for approximately 140 new transmission structures

•  Restoration of impacted areas

TABLE 4.4-14
SEGMENT 6 CONSTRUCTION EMISSION/AIR DISTRICT REGIONAL EMISSION THRESHOLD COMPARISON

¹   Daily significance thresholds are only applicable to single phased projects with duration of less than 12 months; therefore, they are not applicable to this segment.

The annual and daily emissions were compared to applicable AVAQMD and SCAQMD significance thresholds, respectively (see Table 4.4-14) to determine significance of air quality impacts.

A comparison of daily emissions shown in Table 4.4-14 with significance thresholds presented in Table 4.4-4, daily construction emissions would exceed the AVAQMD’s daily significance thresholds for NO_X and VOC, but would not exceed the PM_10, CO, and SO₂ thresholds. However, it should be noted that the daily thresholds are only used for multi-phased projects with phases shorter than one year (AVAQMD, 2002). This proposed project is multi-phased with construction of Segment 6 lasting approximately 36 months; therefore, daily significance thresholds do not apply to this segment. Hence, the annual thresholds are used to determine significance of air quality impacts from this segment. As shown above, peak construction emissions for the entire duration (i.e., 2009 - 2012) does not exceed the AVAQMD’s annual thresholds, therefore, is considered to have less than significant impact in MDAB. Although the annual significance thresholds are not exceeded, the APMs identified in Section 4.4.5 would help reduce the overall air quality impact associated with Segment 6.

The comparison of the peak daily construction emissions with the SCAQMD significance thresholds show that all pollutants are below the thresholds with the exception of NO_X. The reason for the exceedance of the NO_X significance threshold is because of the emissions associated with the operation of a helicopter sky crane. The use of helicopters during construction for this segment is considered to be substantial when compared with other TRTP segments. The reason for this is because a large portion of Segment 6 is located within the ANF and is inaccessible by large off- and on-road construction equipment. Helicopters would be used to deliver construction material and workers to these inaccessible areas. Therefore, the exceedance of NO_X, VOC, and CO significance thresholds requires all feasible APMs be implemented to reduce air impacts to the lowest extent possible. Implementation of the APMs proposed in Section 4.4.5 would not reduce air quality impacts to a level considered less than significant; therefore, impacts would remain significant and unavoidable for the portion of Segment 6 in the ANF. Although operational emissions associated with Segment 6 would be minimal, NO_X emissions associated with construction activities are well above the SCAQMD threshold. Therefore, the construction of Segment 6 could potentially result in a violation of the O₃ air quality standard.

The comparison of the peak daily construction emissions with the SCAQMD significance thresholds show that all pollutants are well below the thresholds with the exception of NO_X emissions. The exceedance of the NO_X significance thresholds requires all feasible mitigation measures be implemented to reduce it to an acceptable level (i.e., less than significant or to the lowest extent possible). Implementation of the measures proposed in Section 4.4.5 may reduce air quality impacts to a level considered less than significant. However, due to the uncertainty regarding the effectiveness of these measures, the NO_X emissions associated with construction of Segment 6 in the SCAQMD would be considered significant. Operational emissions are considered to be negligible and less than significant. Considering that construction emissions associated with Segment 6 would be for a short duration and construction emissions associated with projects listed in the SIP are typically included in the emission inventory provided in the SIP. The project is currently not listed in the SIP, but will be in the next update. As such, the implementation of Segment 6 would not be expected to violate any air quality standard nor contribute substantially to an existing or projected air quality violation. Thus, impacts would be expected to be less than significant.

Would the proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the Project region is classified as nonattainment under an applicable federal or state AAQS (including releasing emissions which exceed quantitative thresholds for ozone precursors)?

The MDAB and SCAB are designated as non-attainment for 8-hour O₃, PM₁₀, and PM_2.5. To determine whether the construction and operation of Segment 6 would result in a cumulatively considerable net increase of any non-attainment criteria pollutant, the peak year construction emissions are compared to the DeMinimis thresholds.

Federal General Conformity Rule. If the Project were to cause annual emissions that exceed the GCR DeMinimis thresholds, SCE would be required to prepare a comprehensive Air Quality Conformity Analysis and Determination. Based on the current proposed Project schedule, the maximum annual construction emissions for Segment 6 would occur in 2010. The estimated annual emissions for year 2010 (peak construction year) for the entire Segment 6 within both air basins, MDAB and SCAB, are compared to the respective GCR DeMinimisthresholds in Table 4.4-15.

TABLE 4.4-15
SEGMENT 6 EMISSION/GENERAL
CONFORMITY EMISSION THRESHOLD COMPARISON

¹   2010 Annual emissions presented in the table are the total emissions generated in year 2010 during construction of Segment 6.

As shown in Table 4.4-15, the proposed Project’s estimated construction emissions are less than the GCR DeMinimis thresholds for the MDAB and SCAB regions. Although the estimated peak annual construction emissions are below the DeMinimis thresholds, daily significance thresholds are exceeded. Therefore, the construction of Segment 6 would result in a cumulatively considerable net increase of NO_X that would contribute to the O₃ nonattainment status for the project region. The detailed annual emissions calculations and associated assumptions used in the calculations are provided in Appendix G. Thus, impacts would be expected to be less than significant.

Would the proposed Project expose sensitive receptors to substantial pollutant concentrations?

The portion of Segment 6 in the MDAB is in remote and rural areas with minimal residences and no other sensitive receptors located near the T/L R-O-W. The portion of the Project area within the SCAB is in remote areas of the ANF and would not affect sensitive receptors. Based on this information, construction emissions would not impact any sensitive receptors near the Project site and, therefore, are determined to be less than significant. The emissions generated from the construction and operation of the electrical transmission system along Segment 6 would not expose nearby sensitive receptors to substantial pollutant concentrations. Operational emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles and light-duty helicopters used by workers to visit the substations and patrol the T/L routes. Thus, impacts from construction and operation of Segment 6 would be less than significant.

Would the proposed Project create objectionable odors that would affect a substantial amount of people?

The use of diesel construction equipment during various construction phases may generate odor that are considered to be a nuisance. Diesel equipment emits a distinctive odor that may be considered offensive to certain individuals. These odors would be temporary and would not affect a substantial number of people. Therefore, the odor impacts from the proposed Project’s construction and operation would be less than significant and would not affect a substantial amount of people. Thus, impacts from construction and operation of Segment 4 would be less than significant.

Summary of Air Quality Impacts. The emissions associated with implementation of Segment 6 are not expected to exceed the AVAQMD annual significance thresholds. However, peak daily construction emissions exceed the SCAQMD significance threshold for NO_X emissions. To reduce daily NO_X emissions, APMs are provided to reduce NO_X emissions to the extent possible. The implementation of APMs would not reduce NO_X emissions to below the significance threshold; therefore, peak daily construction activities within the SCAB are considered to have significant and unavoidable air quality impacts.

Construction activities occur only for a short duration with short-term emissions and all feasible mitigation measures would be implemented to reduce air quality impacts associated with NO_X emissions. Therefore, the short-term exceedance of NO_X emissions is not expected to impact the attainment status of NO₂ within the MDAB and SCAB. In addition, construction emissions generated during the peak year of construction do not exceed the GCR DeMinimis levels; therefore, the construction of Segment 6 is considered to not conflict with or obstruct implementation of the applicable air quality plan, violate any air quality standard or contribute to an existing or projected air quality violation, result in a cumulatively considerable net increase of any nonattainment criteria pollutant, expose sensitive receptors to a substantial amount of pollutants, or create objectionable odors. Hence, the construction of Segment 6 is considered to be consistent with the SIP.

4.4.6.3.3 Mitigation Measures. Peak daily construction emissions (NO_X) would have short-term significant and unavoidable air quality impacts in the SCAB region. No feasible mitigation measures have been identified that would reduce this air quality impact to less-than-significant levels.

4.4.6.3.4 Impact Significance after Mitigation Measure Application. The construction of Segment 6 is expected to create significant air quality impacts because daily construction emissions of NO_X exceed SCAQMD significance thresholds. The short-term construction impact is considered to be significant and unavoidable. The long-term operation impact would be less than significant.

4.4.6.4 Segment 7

4.4.6.4.1 Environmental Setting. Segment 7 of SCE’s TRTP extends from the incorporated City of Duarte in central eastern Los Angeles County through the cities of Irwindale, El Monte, South El Monte, and Montebello to the Mesa Substation located in the City of Monterey Park. The entire area of Segment 7 is located in the SCAB within the jurisdiction of the SCAQMD.

The elevation for Segment 7 ranges from 100 feet to 3,000 feet. The San Gabriel Mountains lie to the north of this segment. This area has a Mediterranean climate, which ischaracterized by warm, dry summers and mild winters and is dominated by a semi‑permanent, high‑pressure cell located over the Pacific Ocean (Western Regional Climate Center).

Temperatures for the area are markedly higher during the summer months. Using the 27-year (1979 to 2006) monthly climate summary from the nearest meteorological station, the Western Regional Climate Center #045790 at Montebello, located approximately 1 mile west of the southwest end of segment 7, the average maximum temperature was 89.7°F in August, with an average minimum temperature of 47.2°F in December.

During the winter months, a semi-permanent, subtropical high-pressure system over the eastern Pacific Ocean moves south, allowing frontal systems that normally are blocked and forced to the north of the area to pass through the region. This results in majority of the area’s annual precipitation, which totals about 15.45 inches. Average maximum rainfall occurs in February (3.91 inches), with minimum rainfall in July (0.01 inch)(Western Regional Climate Center, #045790).

The relative humidity is fairly low, averaging 30 to 60 percent in the early morning hours and 10 to 20 percent in the late afternoon. During the hottest part of the day, the relative humidity averages below 10 percent. These conditions promote intense heat during the day and marked cooling at night.

On occasion during the fall and winter months, a high-pressure system develops over Nevada and Utah and pushes air south and southwestward over the San Gabriel and San Bernardino mountains. The resulting winds are known as Santa Ana winds. Santa Ana winds can be very strong, with wind speeds through mountain passes sometimes exceeding 100 km per hour (62 mph), and are usually warm and dry. They tend to clear the SCAB of accumulated air pollutants, but can also cause dust storms and high particulate levels.

The topographical features in the region around the project area restrict air movement through and out of the basin (especially in the northern portion). The San Gabriel and San Bernardino mountains hinder wind access into the basin from the north, northeast, and east; the San Jacinto Mountains are to the southeast of the basin; the Santa Ana Mountains hinder winds from the south causing weak air flow throughout the basin.

Air Quality Standards and Existing Concentrations. Ambient air quality standards and federal, state, and local regulations are discussed in Section 4.4.3. The nearest air monitoring station to Segment 7 is the Azusa station (see Table 4.4-13) as discussed for Segment 6.

4.4.6.4.2 Impact Analysis. The air quality impacts for Segment 7 are discussed below with regards to the SCAQMD applicable significance thresholds the GCR DeMinimis levels, and the significance criterion as described in Section 4.4.4.

Would the proposed Project conflict with or obstruct implementation of the applicable air quality plan?

Air quality plans are strategies designed to reduce long-term operational emissions and comply with the federal and State ambient air quality standards. The operation of Segment 7 would generate emissions considered to be negligible, as the primary source of operation emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. As previously mentioned, operational phase emissions would be expected to be negligible and below the significance thresholds, and would not conflict with or obstruct the applicable air quality plan. Therefore, the operation of Segment 7 of the TRTP would not conflict with or obstruct implementation of the applicable air quality plan. Therefore, impacts from operation of Segment 7 would be less than significant.

Would the proposed Project violate any air quality standards or contribute substantially to an existing or projected air quality violation?

To determine whether implementation of the proposed Project would violate any air quality standards or contribute substantially to an existing or projected air quality violation, a worst-case scenario approach was taken to ensure that all potential air quality impacts are assessed. As such, emissions occurring during peak construction activities were quantified and used to determine air quality impacts.

Construction and Operation Impacts. Construction of Segment 7 would result in short-term impacts to ambient air quality. Construction activities are projected to last 31 months and start in April 2009 and end in November 2011. This segment requires the following construction tasks:

•  Construction inspection

•  Surveying

•  Setting up marshalling yards

•  Roads and landing work

•  Installing guard poles

•  Removal of existing foundations, conductors, towers, and OHGW

•  Installing new foundations, conductors, OHGW for approximately 81 new transmission structures

•  Restoration of impacted areas

The peak daily construction emissions were compared to the SCAQMD significance thresholds to determine the potential significance of air quality impacts associated with construction activities (see Table 4.4-16).

The comparison of the peak daily construction emissions with the SCAQMD significance thresholds show that all pollutants are below the thresholds with the exception of NO_Xemissions. The exceedance of the NO_X significance thresholds requires that all feasible measures be implemented to reduce it to an acceptable level (i.e., less than significant or to the greatest extent possible). Implementation of APMs proposed in Section 4.4.5 would reduce air quality impacts, but due to the uncertainty of the effectiveness of the measures,

TABLE 4.4-16
SEGMENT 7 CONSTRUCTION EMISSIONS/AIR DISTRICT REGIONAL THRESHOLD COMPARISON

this impact remains significant. Construction emissions are considered to have short term effects and are typically included in the emission inventory provided in the SIP, when the proposed Project is included in the SIP. This Project should be included in the latest SIP update. The implementation of Segment 7 could contribute to the violation of the O₃ air quality standard. In summary, air quality impacts resulting from construction of Segment 7 would be considered significant, however these impacts would be short-term in nature.

Operational emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. Thus, impacts from operation of Segment 4 would be less than significant.

Would the proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the project region is classified as nonattainment under an applicable federal or state AAQS (including releasing emissions which exceed quantitative thresholds for ozone precursors)?

The SCAB is designated as non-attainment for 8-hour O₃, PM₁₀, and PM_2.5. To determine whether the construction and operation of Segment 7 would result in a cumulatively considerable net increase of any non-attainment criteria pollutant, the peak year construction emissions are compared to the GCR DeMinimis thresholds.

Federal General Conformity Rule. If the Project were to cause annual emissions that exceed the GCR DeMinimis thresholds, SCE would be required to prepare a comprehensive Air Quality Conformity Analysis and Determination. Based on the current proposed Project schedule, the maximum annual construction emissions for Segment 7 would occur in 2009. The estimated annual emissions for year 2009 (peak construction year) for Segment 7 within the SCAB are compared to the respective GCR DeMinimisthresholds in Table 4.4-17.

TABLE 4.4-17
SEGMENT 7 PEAK ANNUAL CONSTRUCTION EMISSIONS/GENERAL CONFORMITY EMISSIONS LEVELS

As shown in Table 4.4-17, the proposed Project’s estimated construction emissions for Segment 7 are less than the GCR DeMinimis thresholds for the SCAB region. Although the peak annual construction emissions are below the DeMinimis thresholds, daily significance thresholds are exceeded. Therefore, the construction of Segment 7 would result in a cumulatively considerable net increase of NO_X that would contribute to the O₃ nonattainment status for the project region. Thus, impacts as a result of construction of Segment 7 have the potential to be significant, though by their nature would be temporary. The detailed annual emissions calculations and associated assumptions used in the calculations are provided in Appendix G. Operational impacts would be expected to be less than significant.

Would the proposed Project expose sensitive receptors to substantial pollutant concentrations?

Most of the proposed construction of Segment 7 through the SCAB is along the San Gabriel River bed, which also serves as a buffer zone for the substantial residential population along Segment 7. The closest residences are within a development along Greenbank Avenue in the City of Duarte, which is approximately 60 meters (197 feet) away. The distances to the nearest sensitive receptors are based on measurements using the aerial photographs in Appendix P (Figure P.1-73 [Sheet 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38] ). Based on the distance and the SCAQMD localized significance threshold values data provided in Table 4.4-18, which presents the amount of air pollutants that may potentially create localized significance air quality impacts, there may be a potential for adverse air quality impacts (e.g., NO_X and PM₁₀) at nearby sensitive receptor locations. The emissions presented in Table 4.4-16 were not calculated to allow a direct comparison with the localized significance thresholds, and therefore localized air quality impacts were not assessed in this analysis. APMs presented in Section 4.4.5 would be implemented to reduce air quality impacts. With implementation of the proposed APMs, potential impacts to

TABLE 4.4-18
SEGMENT 7 SCAQMD LOCALIZED SIGNIFICANCE THRESHOLD VALUES (LBS/DAY)¹

¹   SCAQMD 2007b.

sensitive receptors would be expected to be less than significant during typical construction activities. Construction and operational emissions would not expose sensitive receptors to substantial pollutant concentrations. Operational emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. Thus, impacts from construction and operation of Segment 7 would be less than significant.

Would the proposed Project create objectionable odors that would affect a substantial amount of people?

The use of diesel construction equipment during various construction phases may generate odor that are considered to be a nuisance. Diesel equipment emits a distinctive odor that may be considered offensive to certain individuals. These odors would be temporary and would not affect a substantial number of people. Therefore, the odor impacts from construction and operation of Segment 7 would be less than significant.

Summary of Air Quality Impacts. The peak daily construction emissions for Segment 7 exceed the SCAQMD significance threshold (refer to Table 4.4-16) for NO_X emissions. To reduce daily NO_X emissions, measures specified in Section 4.4.5 are provided to reduce NO_X emissions to the extent possible. The implementation of the measures would not reduce NO_X emissions to below the significance threshold, therefore, peak daily construction activities within the SCAB are considered to have significant and unavoidable air quality impacts.

It should be noted that construction activities would only occur over a short duration with short-term emissions; feasible measures would be implemented to reduce air quality impacts associated with NO_X emissions. Therefore, the short-term exceedance of NO_X emissions would not be expected to impact the maintenance status of NO₂ within the SCAB. In addition, construction emissions generated during a peak year does not exceed the GCR DeMinimis levels, therefore, the construction of Segment 7 is considered to not conflict with or obstruct implementation of the applicable air quality plan, violate any air quality standard or contribute to an existing or projected air quality violation, result in a cumulatively considerable net increase of any nonattainment criteria pollutant, expose sensitive receptors to a substantial amount of pollutants, or create objectionable odors. Hence, the construction of Segment 7 is considered to be consistent with the SIP.

4.4.6.4.3 Mitigation Measures. Peak daily construction emissions (NO_X) would result in significant and unavoidable air quality impacts in the SCAB region. APMs would be implemented to reduce construction emissions to the extent possible.

4.4.6.4.4 Impact Significance after Mitigation Measure Application. The construction of Segment 7 would be expected to create significant short-term air quality impacts because daily emissions for NO_X exceed the applicable SCAQMD criteria. Operation emissions for Segment 7 would be less than significant.

4.4.6.5 Segment 8

4.4.6.5.1 Environmental Setting. Segment 8 of the TRTP extends from the Mesa Substation in the City of Monterey Park in Los Angeles County, through the cities of Montebello, Pico Rivera, Industry, and Whittier, along unincorporated county lands, through the cities of Chino Hills, Chino, and Ontario to the Mira Loma Substation in San Bernardino County. There are three proposed sub-segments, 8A, 8B, and 8C, between the Chino Substation and the Mira Loma Substation. Each of these sub-segments follows a very similar path, and they are separated by less than 1 mile. Segment 8 is located entirely in the SCAB within the jurisdiction of the SCAQMD.

Nearly the entire western half of Segment 8 runs along unincorporated lands of Los Angeles County. The eastern half of Segment 8 exits unincorporated Los Angeles County and enters the City of Chino Hills in southwestern San Bernardino County where Segment 8 runs eastward through the City of Chino and the City of Ontario. The elevation for this segment ranges from 100 feet to 1,500 feet. This area is surrounded by mountains on three sides, the San Gabriel Mountains to the north, the San Bernardino Mountains to the east, and the Santa Ana Mountains to the south. This area has a Mediterranean climate, which ischaracterized by warm, dry summers and mild winters and is dominated by a semi‑permanent, high‑pressure cell located over the Pacific Ocean (Western Regional Climate Center).

Temperatures for the area are markedly higher during the summer months. Using the 58-year (1948 to 2006) monthly climate summary from the nearest meteorological station, the Western Regional Climate Center #049847 at Yorba Linda, located approximately 4 miles south of Segment 8, the average maximum temperature was 89.0°F in August, with an average minimum temperature of 42.2°F in December.

During the winter months, a semi-permanent, subtropical high-pressure system over the eastern Pacific Ocean moves south, allowing frontal systems that normally are blocked and forced to the north of the area to pass through the region. This results in majority of the area’s annual precipitation, which totals about 13.89 inches. Average maximum rainfall occurs in January (3.36 inches), with minimum rainfall in July (0.01 inch)(Western Regional Climate Center, #049847).

The relative humidity is fairly low, averaging 30 to 60 percent in the early morning hours and 10 to 20 percent in the late afternoon. During the hottest part of the day, the relative humidity averages below 10 percent. These conditions promote intense heat during the day and marked cooling at night.

On occasion during fall and winter months, a high-pressure system develops over Nevada and Utah and pushes air south and southwestward over the San Gabriel and San Bernardino Mountains. The resulting winds known as Santa Ana winds. Santa Ana winds can be very strong, with wind speeds through mountain passes sometimes exceeding 60 miles per hour, and are usually warm and dry. They tend to clear the SCAB of accumulated air pollutants, but can also cause dust storms and high particulate levels.

The topographical features in the region around the Segment 8 Project area restrict air movement through and out of the basin (especially in the northern portion). The San Gabriel and San Bernardino Mountains hinder wind access into the basin from the north, northeast, and east; the San Jacinto Mountains are to the southeast of the basin; the Santa Ana Mountains hinder winds from the south causing weak air flow throughout the basin.

Air Quality Standards and Existing Concentrations. Ambient air quality standards and federal, state, and local regulations are discussed in Section 4.4.3. Ambient air monitoring data is collected at two locations near Segment 8 of the proposed project: the Pomona air monitoring station, and the Pico Rivera station in Los Angeles County. Table 4.4-19 summarizes the measured criteria pollutant concentrations over the past three years at these stations.

Ozone. As shown in Table 4.4-19, O₃ concentrations have exceeded federal and state AAQS over the past three years. These violations, along with other violations throughout the SCAQMD region, resulted in the region being classified as nonattainment for the state’s 1‑hour, and federal and state’s 8‑hour O₃ standards.

Particulate Matter. Measured concentrations at the monitoring stations have not exceeded federal 24‑hour PM₁₀ standards over the past three years. However, exceedances of the state PM₁₀ standards have occurred over the past three years. These measured

TABLE 4.4-19
SUMMARY OF AMBIENT AIR DATA AT MONITORING STATIONS NEAR SEGMENT 8, 2004‑2006

Source. CARB, 2006c.

¹   Stations: POM (Pomona); PCR (Pico Rivera).

²   Exceeds the federal standard.

³   Exceeds the state standard.

⁴   Federal/state values. The federal and state values differ due to differences in sampling methods and criteria.

⁵   The federal annual PM₁₀ standard was revoked as of December 17, 2006.

-- Data not collected at the monitoring station.

µg/m³ = micrograms per cubic meter; ppm = parts per million; conc. = concentration.

concentrations have contributed to the region being classified as non-attainment for the state PM₁₀ standards.

Carbon Monoxide. CO concentrations recorded at the two nearby monitoring stations are well below federal and state 1‑hour and 8‑hour standards. However, the portions of Los Angeles and San Bernardino counties associated with Segment 8 are considered to be in non-attainment.

Nitrogen Dioxide. Data in Table 4.4-19 show that measured concentrations of NO₂ have consistently remained well below the federal and state standards. With similar trends throughout the region (and state), the area is well within federal and state NO₂ standards.

Sulfur Dioxide. SO₂ is not measured at the Pomona or Pico Rivera stations. However, the Project area is designated as unclassified for federal and attainment for state standards.

4.4.6.5.2 Impact Analysis. The air quality impacts of Segment 8 are discussed below with regards to the SCAQMD applicable significance thresholds, the GCR DeMinimis levels, and the significance criterion as described in Section 4.4.4.

Would the proposed Project conflict with or obstruct implementation of the applicable air quality plan?

Air quality plans are strategies designed to reduce long-term operational emissions and comply with the federal and State ambient air quality standards. Operation emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. As previously mentioned, operation phase emissions are expected to be negligible and below significance thresholds, and would not conflict with or obstruct the applicable air quality plan. Therefore, impacts from operation of Segment 8 would be less than significant.

Would the proposed Project violate any air quality standards or contribute substantially to an existing or projected air quality violation?

To determine whether implementation of Segment 8 would violate any air quality standards or contribute substantially to an existing or projected air quality violation, a worst-case scenario approach was taken to ensure that all potential air quality impacts were assessed. As such, emissions occurring during peak construction activities were quantified and used to determine air quality impacts. Segment 8 construction emissions are presented in
Table 4.4-20.

TABLE 4.4-20
SEGMENT 8 CONSTRUCTION EMISSIONS/AIR DISTRICT REGIONAL THRESHOLD COMPARISON

Construction and Operation Impacts. Construction of Segment 8 of the proposed Project would result in short-term impacts to ambient air quality. Construction activities are projected to last 36 months starting in April 2009 and ending in April 2012. This segment requires the following construction tasks:

•  Construction inspection

•  Surveying

•  Setting up marshalling yards

•  Roads and landing work

•  Installing guard poles

•  Removal of existing foundations, conductors, towers, and OHGW

•  Installing new foundations, conductors, OHGW for approximately 226 new 550 kV and 220 kV towers, which is a combination of LSTs and TSPs, as well as 14 66 kV structures

•  Installing underground infrastructures (e.g., duct banks and vaults)

•  Restoration of impacted areas

The peak daily construction emissions were compared to the SCAQMD significance thresholds to determine significance of air quality impacts associated with construction activities (see Table 4.4-20).

The comparison of the peak daily construction emissions with the SCAQMD significance thresholds show that all pollutants except NO_X and VOC are below the thresholds. The exceedance of the NO_X and VOC significance thresholds requires all feasible measures be implemented to reduce it to an acceptable level (i.e., less than significant or to the greatest extent possible). Implementation of the APMs in Section 4.4.5 would reduce air quality impacts, but impacts would remain significant. Operational emissions are expected to be negligible and well below the significant thresholds. However, the construction of Segment 8 could potentially contribute to violation of the O₃ air quality standard. Thus, construction-related air quality impacts are considered to be significant.

Would the proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the project region is classified as nonattainment under an applicable federal or state AAQS (including releasing emissions which exceed quantitative thresholds for ozone precursors)?

The SCAB is designated as non-attainment for 8-hour O₃, PM₁₀, and PM_2.5. To determine whether the construction and operation of Segment 8 would result in a cumulatively considerable net increase of any non-attainment criteria pollutant, the peak year construction emissions are compared to the DeMinimis thresholds.

Federal General Conformity Rule. If the Project were to cause annual emissions that exceed the GCR DeMinimis thresholds, SCE would be required to prepare a comprehensive Air Quality Conformity Analysis and Determination. Based on the current proposed Project schedule, the maximum annual construction emissions for Segment 8 would occur in 2009. The estimated annual emissions for year 2009 (peak construction year) for the entire Segment 8 within the SCAB, are compared to the respective GCR DeMinimisthresholds and presented in Table 4.4-21.

TABLE 4.4-21
SEGMENT 8 EMISSIONS/GENERAL CONFORMITY EMISSIONS THRESHOLD COMPARISON

As shown in Table 4.4-21, the estimated peak annual construction emissions for Segment 8 are less than the GCR DeMinimis thresholds for the SCAB regions. Although the peak annual construction emissions are below the DeMinimis thresholds, daily significance thresholds are exceeded. Therefore, the construction of Segment 8 would result in a cumulatively considerable net increase of NO_X and VOC that could contribute to the O₃ nonattainment status for the Project region. The detailed annual emissions calculations and associated assumptions used in the calculations are provided in Appendix G. Thus, impacts would have the potential to be significant.

Would the proposed Project expose sensitive receptors to substantial pollutant concentrations?

A large portion of the proposed construction route for Segment 8 is located on uninhabited land through the SCAB. There are residential developments near the proposed construction route in the La Habra Heights and Chino Hills areas. The closest residence is approximately 165 feet away. The distances to the nearest sensitive receptors are based on measurements using aerial photographs in Appendix P (Figure P.1-73 [Sheet 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38] ). Based on the distance and SCAQMD local significance threshold data provided in Table 4.4-22, which presents the amount of air pollutants that may potentially create localized significant air quality impacts, there is a potential for adverse air quality impacts at nearby sensitive receptor locations. The emissions presented in Table 4.4-20 were not calculated to allow a direct comparison with the localized significance thresholds, and therefore localized air quality impacts were not assessed in this analysis. APMs presented in Section 4.4.5 would be implemented to reduce air quality impacts. With implementation of the APMs, impacts to sensitive receptors would be expected to be less than significant.

TABLE 4.4-22
SCAQMD LOCALIZED SIGNIFICANCE THRESHOLD VALUES (LBS/DAY)

Would the proposed Project create objectionable odors that would affect a substantial amount of people?

The use of diesel construction equipment during various construction phases may generate odor that are considered to be a nuisance. Diesel equipment emits a distinctive odor that may be considered offensive to certain individuals. These odors would be temporary and would not affect a substantial number of people. Therefore, the odor impacts from the proposed project’s construction and operation would be less than significant and no mitigation measures would be required.

Summary of Air Quality Impacts. As described in the previous section, the peak daily construction emissions exceed the SCAQMD significance threshold for NO_X and VOC emissions. To reduce daily NO_X and VOC emissions, the APMs specified in Section 4.4.5 would be implemented to reduce emissions to the extent possible. The implementation of the APMs would not reduce NO_X and VOC emissions to below the significance threshold; therefore, peak daily construction activities within the SCAB would have short-term significant and unavoidable air quality impacts.

Construction activities are only for a short duration with short-term emissions and all feasible mitigation measures would be implemented to reduce air quality impacts associated with NO_X emissions. Therefore, the short-term exceedance of NO_X and VOC significance criteria would not be expected to impact the maintenance status of NO₂ within the SCAB. In addition, construction emissions generated during a peak year does not exceed the GCR DeMinimis levels, therefore, the construction of Segment 8 is considered not to conflict with or obstruct implementation of the applicable air quality plan, violate any air quality standard or contribute to an existing or projected air quality violation, result in a cumulatively considerable net increase of any nonattainment criteria pollutant, expose sensitive receptors to a substantial amount of pollutants, or create objectionable odors. Hence, the construction of Segment 8 is considered to be consistent with the SIP.

4.4.6.5.3 Mitigation Measures. Peak daily construction emissions were shown to have significant and unavoidable air quality impacts in the SCAB region. APMs would be implemented to reduce construction emissions to the extent possible.

4.4.6.5.4 Impact Significance after Mitigation Measure Application. The construction of Segment 8 would be expected to create significant air quality impacts because annual construction emissions presented above are above SCAQMD significance thresholds for NO_X and VOC. As such, the impact would remain significant.

4.4.6.6 Segment 9

4.4.6.6.1 Environmental Setting. Segment 9 of the proposed Project is comprised of expansions and upgrades to existing SCE substations and construction of a new substation, Whirlwind. The substations associated with Segment 9 and their locations with respect to air basins and districts are presented in Table 4.4-23.

Air quality settings for the locations of the substations are as discussed in the proposed T/L segment discussions, as follows:

•  Whirlwind (refer to Segment 4)

TABLE 4.4-23
SEGMENT 9 SUBSTATIONS AND ASSOCIATED AIR BASIN
AND AIR DISTRICTS

•  Antelope (refer to Segments 4 and 5)

•  Vincent (refer to Segment 5)

•  Gould (refer to Segment 11)

•  Mesa (refer to Segments 7 and 11)

•  Mira Loma (refer to Segment 8)

4.4.6.6.2 Impact Analysis. The air quality impacts for Segment 9 substation facilities are discussed below with regards to the applicable KCAPCD, AVAQMD, and SCAQMD significance thresholds, the GCR DeMinimis levels, and the significance criterion as described in Section 4.4.4.

Would the proposed Project conflict with or obstruct implementation of the applicable air quality plan?

Air quality plans are strategies designed to reduce long-term operational emissions and comply with the federal and State ambient air quality standards. The operation of Segment 9 of the TRTP would generate emissions considered to be negligible. Operational emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations. As previously mentioned, operation emissions would be expected to be negligible and below the significance thresholds, and would not conflict with or obstruct the applicable air quality plan. Therefore, impacts from operation of Segment 9 would be less than significant.

Would the proposed Project violate any air quality standards or contribute substantially to an existing or projected air quality violation?

To determine whether implementation of the proposed Project would violate any air quality standards or contribute substantially to an existing or projected air quality violation, a worst-case scenario approach was taken to ensure that all potential air quality impacts are assessed. As such, emissions occurring during peak construction activities were quantified and used to determine air quality impacts. Construction emissions are presented in Table 4.4-24.

TABLE 4.4-24
SEGMENT 9 PROPOSED PROJECT CONSTRUCTION EMISSION/AIR DISTRICT REGIONAL EMISSION THRESHOLD COMPARISON

¹   Emissions are from construction activities at the Whirlwind Substation.

²   Emissions are from construction activities at the Antelope and Vincent substations.

³   Emissions are from construction activities at the Gould, Mesa, and Mira Loma substations.

Construction and Operation Emissions. Construction of Segment 9 of the proposed Project would result in short-term impacts to ambient air quality. Construction activities are projected to last 45 months and start in February 2010 and end in November 2013. Each one of the Segment 9 substations would undergo some or all of the following activities:

•  Grading Element

•  Civil Element

•  Electrical Element

•  Maintenance Element

•  Test Element

The peak annual and daily construction emissions were compared to the applicable KCAPCD, AVAQMD, and SCAQMD significance thresholds, respectively, to determine significance of air quality impacts associated with construction activities. Emissions generated in the MDAB (i.e., within KCAPCD and AVAQMD jurisdictions) and SCAB are presented in Table 4.4-24.

KCAPCD does not have significance thresholds for construction activities, therefore, emissions data is only provided for informational purposes. A comparison of AVAQMD’s annual emissions shown in Table 4.4-24 with applicable significance thresholds shows that annual construction emissions would not exceed the AVAQMD’s significance thresholds for any pollutants, therefore, is considered to have a less than significant impact. Although the annual significance thresholds are not exceeded, the APMs identified in Section 4.4.5 would be implemented to reduce overall air quality impacts.

The comparison of the peak daily construction emissions with the SCAQMD significance thresholds show that all pollutants are below the thresholds with the exception of NO_X and PM₁₀ emissions. The exceedance of the NO_X and PM₁₀significance thresholds requires all measures be implemented to reduce impacts to an acceptable level (i.e., less than significant or to the lowest extent possible). Implementation of the APMs in Section 4.4.5 would be expected to reduce air quality impacts to a level considered less than significant. Therefore, the construction of Segment 9 would not have a significant impact on air quality, and impacts would be short-term. Furthermore, emissions from the operation of Segment 9 substation facilities are considered to be negligible. Hence, the construction and operation of the Segment 9 would not violate any air quality standard nor contribute substantially to an existing or projected air quality violation.

Would the proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the Project region is classified as nonattainment under an applicable federal or state AAQS (including releasing emissions which exceed quantitative thresholds for ozone precursors)?

Federal General Conformity Rule. If the Project were to cause annual emissions that exceed the GCR DeMinimis thresholds,SCE would be required to prepare a comprehensive Air Quality Conformity Analysis and Determination. Based on the current proposed project schedule, the maximum annual construction emissions for Segment 9 would occur in 2011 within the MDAB (i.e., areas within the KCAPCD and AVAQMD jurisdictions) and in 2012 within the SCAB (i.e., areas within the SCAQMD jurisdiction). Annual construction emissions for 2011 and 2012 in the MDAB, in the SCAB, respectively, were compared to the respective GCR DeMinimisthresholds and are provided in Table 4.4-25.

TABLE 4.4-25
SEGMENT 9 PROPOSED PROJECT EMISSIONS/GENERAL CONFORMITY EMISSIONS THRESHOLD COMPARISON

¹   Emissions are from construction activities occurring in year 2011 in KCAPCD and AVAQMD jurisdictions (MDAB region).

²    Maximum construction emissions occurring in the SCAB was in year 2012.

Table 4.4-25 shows that the maximum construction emissions are well below the GCR DeMinimis for the MDAB and the SCAB. Although the SCAQMD daily significance thresholds are exceeded (Table 4.4-24) for NO_X and VOC, implementation of the APMs would be expected to reduce air quality impacts to a level considered less than significant. The detailed annual emissions calculations and associated assumptions used in the calculations are provided in Appendix G. Thus, the implementation of Segment 9 is expected to have less than significant air quality impacts.

Would the proposed Project expose sensitive receptors to substantial pollutant concentrations?

Construction activities to upgrade the existing substations and the new Whirlwind Substation would generate air pollutants that may have localized air quality impacts. To determine whether there would be any adverse air quality impacts to nearby sensitive receptors, the aerial photographs in Appendix P (Figure P.1-73 [Sheet 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38] ) were reviewed. There are three alternative locations for the Whirlwind Substation, but they are all in an agricultural area with the nearest sensitive receptors located at least several hundred meters away. Similarly, the Antelope and Vincent substations are in rural areas with no sensitive receptors nearby. The nearest sensitive receptor to the expanded Vincent Substation property would be approximately 400 feet. The Mira Loma Substation is located in an agricultural area with no sensitive receptors nearby. Approximately 240 feet from the Gould Substation are multiple residences. There are a few commercial properties that are located approximately 100 meters (328 feet) from the Mesa Substation. All proposed upgrades at the Gould and Mira Loma substations would occur within the existing fencelines with emissions that are well below the SCAQMD daily significance thresholds. Therefore, substation construction, expansion, and/or upgrades would not be expected to result in adverse air quality impacts that would impact nearby sensitive receptors or create any localized air quality impacts, and impacts would be considered to be less than significant.

Would the proposed Project create objectionable odors that would affect a substantial amount of people?

The use of diesel construction equipment during various construction phases may generate odor that are considered to be a nuisance. Diesel equipment and asphalt paving emit a distinctive odor that may be considered offensive to certain individuals. These odors would be temporary and would not affect a substantial number of people. Thus, odor impacts from the construction and operation of Segment 9 would be less than significant.

Summary of Air Quality Impacts. As described in the previous section, construction emissions occurring within the MDAB are well below the AVAQMD annual significance thresholds. Peak daily construction emissions would be below all SCAQMD significance thresholds except for the NO_X and PM₁₀ thresholds. To reduce daily NO_X and PM₁₀ emissions, feasible APMs specified in Section 4.4.5 would be implemented to reduce NO_X and PM₁₀ emissions to the extent possible. The implementation of the APMs could reduce NO_X emissions to below the significance threshold. The reduction in daily emissions is dependent on the number of APMs implemented; therefore, it is assumed that SCE would implement all feasible measures to reduce peak daily construction activities within the SCAB to a level considered less than significant.

Construction activities occur only for a short duration with short-term emissions and all feasible mitigation measures would be implemented to reduce air quality impacts associated with NO_X and PM₁₀ emissions. Therefore, the short-term exceedance of NO_X emissions is not expected to impact the maintenance status of NO₂ within the SCAB. PM₁₀ emissions generated on a peak construction day would only be seven percent over the threshold. It should be considered that this would be on a peak construction day and would have greater emissions than a typical construction day. Therefore, with the implementation of APMs, PM₁₀ emissions would be expected to be reduced to a level considered less than significant. In addition, construction emissions generated during a peak year would not exceed the GCR DeMinimis levels, therefore, the construction of Segment 9 is considered not to conflict with or obstruct implementation of the applicable air quality plan, violate any air quality standard or contribute to an existing or projected air quality violation, result in a cumulatively considerable net increase of any nonattainment criteria pollutant, expose sensitive receptors to a substantial amount of pollutants, or create objectionable odors. Hence, the construction of Segment 9 is considered to be consistent with the SIP.

4.4.6.6.3 Mitigation Measures. The aforementioned APMs have been incorporated into the Project design, and potentially significant impacts have been avoided or reduced to a less-than-significant level, and no mitigation is required.

4.4.6.6.4 Impact Significance after Mitigation Measure Application. The construction of Segment 9 is expected to create potentially significant air quality impacts in the SCAB region because peak day construction emissions presented exceed the SCAQMD significance thresholds. However, with the implementation of the APMs, it is expected that air quality impacts would be reduced to a less-than-significant level.

4.4.6.7 Segment 10

4.4.6.7.1 Environmental Setting. Segment 10 of the TRTP extends from approximately 10 miles southeast of the City of Tehachapi, in eastern Kern County, to the southeastern edge of Kern County. This portion of the proposed project is located in MDAB within the KCAPCD jurisdiction. There are two routing alternatives for portions of this segment, Alternatives 10A and 10B. The environmental setting for air quality is the same for proposed Segment 10 and the two alternative routings. Segment 10 (and alternatives) extends through unincorporated Kern County lands, which are rural and currently uninhabited. Meteorological conditions and ambient air quality for Segment 10 are similar to Segment 4, as described in
Section 4.4.6.1.1.

4.4.6.7.2 Impact Analysis. The air quality impacts of this segment are discussed below with regards to the applicable KCAPCD significance thresholds, the GCR DeMinimis levels, and the significance criterion as described in Section 4.4.4.

Would the proposed Project conflict with or obstruct implementation of the applicable air quality plan?

Air quality plans are strategies designed to reduce long-term operational emissions and comply with the federal and State ambient air quality standards. The operation of Segment 10 of the TRTP would generate emissions considered to be negligible. Operation emissions are considered to be negligible because the primary souce of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. As previously mentioned, operation emissions are expected to be negligible and below significance thresholds, and would not conflict with or obstruct the applicable air quality plan. Therefore, the impacts from operation of Segment 10 would be less than significant.

Would the proposed Project violate any air quality standards or contribute substantially to an existing or projected air quality violation?

To determine whether implementation of Segment 10 would violate any air quality standards or contribute substantially to an existing or projected air quality violation, a worst-case scenario approach was taken to ensure that all potential air quality impacts are assessed. As such, emissions occurring during peak construction activities were quantified and used to determine air quality impacts. Segment 10 construction emissions are presented in Table 4.4-26.

TABLE 4.4-26
SEGMENT 10 PROPOSED PROJECT CONSTRUCTION EMISSION/AIR DISTRICT REGIONAL EMISSION THRESHOLD COMPARISON

Construction Emissions. Construction of Segment 10 would result in short-term impacts to ambient air quality. Construction activities are projected to last eight months and start in February 2011 and ends in October 2011. This segment requires the following construction tasks:

•  Surveying

•  Setting up Marshalling Yards

•  Roads and Landing Work

•  Installing guard poles

•  Installing new foundations, conductors, OHGW for approximately 96 new towers, which is a combination of LSTs and TSPs

•  Restoration of impacted areas

KCAPCD does not have significance thresholds for construction activities, therefore, emissions data is only provided for informational purposes. Emissions generated in the MDAB (i.e., within KCAPCD jurisdiction) are presented in Table 4.4-26.

KCAPCD does not have significance thresholds for construction activities, therefore, emissions data is only provided for informational purposes. Without significance thresholds for construction activities, it is assumed that with the implementation of APMs that air quality impacts would be considered to be less than significant. Hence, the construction and operation of Segment 10 would not violate any air quality standard nor contribute substantially to an existing or projected air quality violation. Thus, impacts would be less than significant.

Would the proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the Project region is classified as nonattainment under an applicable federal or state AAQS (including releasing emissions which exceed quantitative thresholds for ozone precursors)?

Federal General Conformity Rule. If the Project were to cause annual emissions that exceed the GCR DeMinimis thresholds, SCE would be required to prepare a comprehensive Air Quality Conformity Analysis and Determination. Based on the current proposed project schedule, the entire Segment 10 would be constructed in year 2011. Construction emissions for year 2011 were compared to the respective GCR DeMinimisthresholds and are presented in Table 4.4-27.

TABLE 4.4-27
SEGMENT 10 EMISSIONS/GENERAL CONFORMITY EMISSIONS THRESHOLD COMPARISON

Table 4.4-27 shows that the estimated construction emissions for Segment 10 are well below the GCR DeMinimis applicability thresholds for the MDAB and, therefore, are considered to be conforming with the SIP and AQMP. The detailed annual emissions calculations and associated assumptions used in the calculations are provided in Appendix G. Thus, impacts would be expected to be less than significant.

Would the proposed Project expose sensitive receptors to substantial pollutant concentrations?

The majority of the areas traversed by Segment 10 are uninhabited, rural, with the remaining areas occupied by agricultural activities. There are no sensitive receptors nearby, therefore, construction activities would not be expected to create localized adverse air quality impacts that would affect any sensitive receptors, and this potential impact is considered to be less than significant.

Would the proposed Project create objectionable odors that would affect a substantial amount of people?

The use of diesel construction equipment during various construction phases may generate odor that are considered to be a nuisance. Diesel equipment emits a distinctive odor that may be considered offensive to certain individuals. These odors would be temporary and would not affect a substantial number of people. Therefore, the odor impacts from construction and operation of Segment 10 would be less than significant and no mitigation measures would be required.

Summary of Air Quality Impacts. As described in the previous section, construction emissions with the implementation of the APMs are expected to have less than significant air quality impacts. In addition, construction emissions generated during year 2011 would not exceed the GCR DeMinimis levels; therefore, the construction of Segment 10 is considered to not conflict with or obstruct implementation of the applicable air quality plan, violate any air quality standard or contribute to an existing or projected air quality violation, result in a cumulatively considerable net increase of any nonattainment criteria pollutant, expose sensitive receptors to a substantial amount of pollutants, or create objectionable odors. Hence, the construction of Segment 10 is considered to be consistent with the SIP.

4.4.6.7.3 Mitigation Measures. The aforementioned APMs have been incorporated into the Project design, and potentially significant impacts have been avoided or reduced to a less-than-significant level, and no mitigation is required.

4.4.6.7.4 Impact Significance after Mitigation Measure Application. The construction of Segment 10 would not be expected to create significant air quality impacts in the MDAB. The potential impacts to air quality associated with construction and operation of Segment 10 are considered to be less than significant.

4.4.6.8 Segment 11

4.4.6.8.1 Environmental Setting. Segment 11 of SCE’s TRTP extends from the Vincent Substation in northeastern Los Angeles County through the ANF to the Gould Substation, into La Canada Flintridge, then onward Pasadena, Rosemead, and San Gabriel to the Mesa Substation to the incorporated City of Monterey Park in central Los Angeles County. This portion of the proposed Project is located in the SCAB. Segment 11 is located within the jurisdiction of AVAQMD and SCAQMD. Approximately 21 percent of Segment 11 is located in the AVAQMD and 79 percent of Segment 11 is located in the SCAQMD. Descriptions for the AVAQMD and SCAQMD jurisdictions are provided in Segments 4 - 9 (i.e., Sections 4.4.6.1 - 4.4.6.6).

The northern half of Segment 11 occupies land in the ANF, which is located in the San Gabriel Mountain Range. The elevation of this segment ranges from 500 feet to 5,000 feet. The San Gabriel Mountains surround the northern half of Segment 11 to the north, south, east and west. The southern half of the segment has the San Gabriel Mountains to the north, the San Bernardino Mountains to the east, the Santa Ana Mountains to the south, and the Pacific Ocean to the west.

Temperatures for the area are markedly higher during the summer months. Using the 79-year (1927 to 2006) monthly climate summary from the nearest meteorological station, the Western Regional Climate Center #046719 at Pasadena, located approximately 6 miles north of the southern end of the proposed project segment, the average maximum temperature was 89.5°F in August, with an average minimum temperature of 43.1°F in January. Seasonal temperature differences are due to the lack of marine influence.

During the winter months, a semi-permanent, subtropical high-pressure system over the eastern Pacific Ocean moves south, allowing frontal systems that normally are blocked and forced to the north of the area to pass through the region. This results in majority of the area’s annual precipitation, which totals about 20.34 inches. Average maximum rainfall occurs in February (4.66 inches), with minimum rainfall in July (0.02 inches)(Western Regional Climate Center, #046719).

The relative humidity is fairly low, averaging 30 to 60 percent in the early morning hours and 10 to 20 percent in the late afternoon. During the hottest part of the day, the relative humidity averages below 10 percent. These conditions promote intense heat during the day and marked cooling at night.

Air Quality Standards and Existing Concentrations. Applicable ambient air quality standards and federal, state, and local regulations are discussed in Section 4.4.3. The Pasadena air monitoring station is located near the central portion of Segment 11. Table 4.4‑28 summarizes the measured criteria pollutant concentrations over the past three years at this station.

Ozone. As shown in Table 4.4-28, ozone concentrations have exceeded federal and state AAQS over the past three years. These violations, along with other violations throughout the Los Angeles region, resulted in the region being classified as nonattainment for the state’s 1‑hour, and federal and state’s 8‑hour O₃ standards.

Particulate Matter. Measured concentrations at the monitoring stations have not exceeded federal 24‑hour PM_2.5 standards over the past three years. However, exceedances of the state PM_2.5 standards have occurred over the past three years. These measured concentrations have contributed to the region being classified as nonattainment for the state PM_2.5 standards.

Carbon Monoxide. CO concentrations recorded at the nearby monitoring station are well below federal and state 1‑hour and 8‑hour standards. However, all of Los Angeles County is considered to be in nonattainment of state and federal standards.

Nitrogen Dioxide. Data in Table 4.4-28 show that measured concentrations of NO₂ have consistently remained below the federal and state standards. With similar trends throughout the region (and state), the area is within federal and state NO₂ standards.

Sulfur Dioxide. Sulfur dioxide is not measured at the Pasadena station. However, the Project area is designated as unclassified for federal and attainment for state standards.

4.4.6.8.2 Impact Analysis. The air quality impacts for Segment 11 of the proposed Project are discussed below. The analysis describes the impacts of the proposed project related to air quality and, for each criterion, determines whether implementation of the proposed project would result in significant impacts.

Would the proposed Project conflict with or obstruct implementation of the applicable air quality plan?

Air quality plans are strategies designed to reduce long-term operational emissions and comply with the federal and State ambient air quality standards. The operation of Segment 11 of the TRTP would generate emissions considered to be negligible. Operation emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. As

TABLE 4.4-28
SEGMENT 11 SUMMARY OF AMBIENT AIR DATA AT MONITORING STATION IN PASADENA, 2004-2006

Source. CARB, 2006c.

¹   Station: PAS (Pasadena).

²   Exceeds the federal standard.

³   Exceeds the state standard.

⁴   Federal/state values. The federal and state values differ due to differences in sampling methods and criteria.

⁵   The federal annual PM₁₀ standards were revoked as of December 17, 2006.

-- Data not collected at the monitoring station; µg/m³ = micrograms per cubic meter; ppm = parts per million; conc. = concentration.

previously mentioned, operation phase emissions are expected to be negligible and below significance thresholds, and would not conflict with or obstruct the applicable air quality plan. Therefore, impacts from operation of Segment 11 would not conflict with or obstruct the applicable air quality plan. Therefore, impacts from operation of Segment 11 would be less than significant.

Would the proposed Project violate any air quality standards or contribute substantially to an existing or projected air quality violation?

To determine whether implementation of Segment 11 would violate any air quality standards or contribute substantially to an existing or projected air quality violation, a worst-case scenario approach was taken to ensure that all potential air quality impacts are assessed. As such, emissions occurring during peak construction activities were quantified and used to determine air quality impacts. Segment 11 construction emissions are presented in Table 4.4-29.

TABLE 4.4-29
SEGMENT 11 CONSTRUCTION EMISSION/AIR DISTRICT REGIONAL EMISSION THRESHOLD COMPARISON

Construction and Operation Emissions. The daily and annual emissions are compared to thresholds for the AVAQMD and the SCAQMD. Where a segment lies over multiple air districts, the proportion of emissions in each district is determined by the distance of the portion of the segment within each district’s boundaries. Construction of Segment 11 of the proposed project would result in short-term impacts to ambient air quality. Construction activities are projected to last 19 months and start in April 2012 and end in November 2013. This segment requires the following construction tasks:

•  Construction inspection

•  Surveying

•  Setting up marshalling yards

•  Roads and landing work

•  Installing guard poles

•  Removal of existing foundations, conductors, towers, and overhead ground wire (OHGW) north of Gould Substation

•  Installing new foundations, conductors, OHGW for approximately 76 new towers north of Gould Substation (a combination of LSTs and TSPs)

•  String 220 kV T/L in a vacant position on existing towers from Gould Substation to Mesa Substation

•  Restoration of impacted areas

Construction emissions data presented in Table 4.4-29 are segregated into the AVAQMD and SCAQMD jurisdictions based on approximately 21 percent of Segment 11 being located in the AVAQMD and 79 percent of Segment 11 being located in the SCAQMD. The peak annual and daily construction emissions were compared to the AVAQMD and SCAQMD significance thresholds, respectively, to determine the potential significance of air quality impacts associated with construction activities.

A comparison of AVAQMD’s annual emissions shown in Table 4.4-29 with applicable significance thresholds shows that annual construction emissions would not exceed the AVAQMD’s significance thresholds for any pollutants; therefore, impacts would be less than significant. Although the annual significance thresholds are not exceeded, the APMs identified in Section 4.4.5 would be implemented to reduce overall air quality impact.

The comparison of the peak daily construction emissions with the SCAQMD significance thresholds show that all pollutants are below the thresholds with the exception of NO_X, VOC, and CO. The reason for the exceedance of the NO_X, VOC, and CO significance thresholds is because of the emissions associated with the operation of a helicopter sky crane. Helicopter construction is proposed to be heavily used in this segment when compared with other TRTP segments. The reason for this is because a large portion of Segment 11 is located within the ANF and is inaccessible by large off- and on-road construction equipment. Helicopters would be used to deliver construction material and workers to these inaccessible areas. Therefore, the exceedance of NO_X, VOC, and CO significance thresholds requires all feasible APMs be implemented to reduce air impacts to the lowest extent possible. Implementation of the APMs proposed in Section 4.4.5 would not reduce air quality impacts to a level considered less than significant; therefore, short-term impacts would remain significant and unavoidable for the portion of Segment 11 in the ANF. Although operational emissions associated with Segment 11 would be minimal, construction emissions are well above the SCAQMD thresholds. Therefore, the construction of Segment 11 could potentially result in a violation of the O₃ air quality standard. Thus, air quality impacts are considered to be significant.

Would the proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the project region is classified as nonattainment under an applicable federal or state AAQS (including releasing emissions which exceed quantitative thresholds for ozone precursors)?

Federal General Conformity Rule. If the Project were to cause annual emissions that exceed the GCR DeMinimis thresholds, SCE would be required to prepare a comprehensive Air Quality Conformity Analysis and Determination. Based on the current proposed Project schedule, the maximum annual construction emissions for Segment 11 would occur in 2013 within the MDAB (i.e., areas within the AVAQMD jurisdiction) and the SCAB (i.e., areas within the SCAQMD jurisdiction). Annual construction emissions for year 2013 in the MDAB and the SCAB, respectively, were compared to their respective GCR DeMinimisthresholds and are provided in Table 4.4-30.

TABLE 4.4-30
SEGMENT 11 EMISSIONS/GENERAL
CONFORMITY EMISSIONS THRESHOLD COMPARISON

Table 4.4-30 shows that the maximum annual construction emissions would be well below the GCR DeMinimis for the MDAB and the SCAB. Although the peak annual construction emissions for Segment 11 are below the DeMinimis thresholds, daily significance thresholds are exceeded. Therefore, the construction of Segment 11 would result in a cumulatively considerable net increase of NO_X, CO, and VOC that could contribute to the O₃ nonattainment status for the Project region. The detailed annual emissions calculations and associated assumptions used in the calculations are provided in Appendix G. Thus, air quality impacts during construction for Segment 11 are considered to be significant.

Would the proposed Project expose sensitive receptors to substantial pollutant concentrations?

The majority of construction emissions generated during the construction of Segment 11 would occur in the ANF with no sensitive receptors nearby; therefore, localized air quality impacts would be less than significant. The remaining construction activities between the Gould and Mesa substations would be in urbanized areas. The use of construction equipment in these urbanized areas would create air quality impacts, but with the implementation of the APMs provided in Section 4.4.5, localized air quality impacts would be expected to be minimal and are considered to be less than significant.

Operational emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. Thus, impacts from operation of Segment 11 would be less than significant.

Would the proposed Project create objectionable odors that would affect a substantial amount of people?

The use of diesel construction equipment during various construction phases may generate odor that are considered to be a nuisance. Diesel equipment emits a distinctive odor that may be considered offensive to certain individuals. These odors would be temporary and would not affect a substantial number of people. Therefore, the odor impacts from the construction and operation of Segment 11 would be less than significant.

Summary of Air Quality Impacts. As described in the previous section, construction emissions occurring within the MDAB are well below the AVAQMD annual significance thresholds. Peak daily construction emissions would be below all SCAQMD significance thresholds except for the NO_X, VOC, and CO thresholds. As previously mentioned, the exceedance of these thresholds is contributed to the “above normal” use of helicopters to deliver construction materials and workers to inaccessible areas of the ANF. The majority of Segment 11 is located within the ANF where it is inaccessible by off- and on-road construction equipment, therefore, requiring the use of helicopter. Upon completion of construction within the ANF areas, the use of helicopters would be substantially reduced and revert to usage similar for other segments. In urbanized areas, feasible APMs specified in Section 4.4.5 would be implemented. The implementation of the APMs could reduce NO_X, VOC, and CO emissions to below the significance threshold. The reduction in daily emissions is dependent on the number of APMs and mitigation measures implemented, therefore, it is assumed that SCE would implement all feasible measures to reduce peak daily construction activities within the urban portions of the SCAB to a level considered less than significant.

In addition, air quality within the ANF area is under the jurisdiction of the Forest Service. Per Section 176 (c) of the CAA, if the Forest Service determines that the net increase of emissions are below the GCR DeMinimis thresholds then the Project is considered to be in conformance with the SIP.

In conclusion, construction emissions generated during the peak year do not exceed the GCR DeMinimis levels; therefore, the construction of Segment 11 would be considered to not conflict with or obstruct implementation of the applicable air quality plan, violate any air quality standard or contribute to an existing or projected air quality violation, result in a cumulatively considerable net increase of any nonattainment criteria pollutant, expose sensitive receptors to a substantial amount of pollutants, or create objectionable odors. Hence, the construction of Segment 11 is considered to be consistent with the SIP.

4.4.6.8.3 Mitigation Measures. The aforementioned APMs have been incorporated into the Project design, and potentially significant impacts have been avoided or reduced to a less-than-significant level, and no mitigation is required.

4.4.6.8.4 Impact Significance after Mitigation Measure Application. The construction of Segment 11 is expected to create potentially significant air quality impacts in the MDAB and SCAB regions because peak day construction emissions presented exceed the SCAQMD significance thresholds. However, with the implementation of the APMs, air quality impacts should be minimized to a level considered less than significant in urbanized areas.

4.4.7 Overall Project Impact Analysis

To determine the potential significance of air quality impacts associated with the implementation of each proposed TRTP segment, emissions and associated impacts were assessed on a segment-by-segment basis in Sections 4.4.6.1 through 4.4.6.8. To assess the potential significance of air quality impacts within each air basin, daily and annual construction emissions were summed for TRTP segments located in the same air districts and air basin and compared to the applicable air district thresholds.

Would the proposed Project conflict with or obstruct implementation of the applicable air quality plan?

Air quality plans are strategies designed to reduce long-term operational emissions and comply with the federal and State ambient air quality standards. The operation of the TRTP would generate emissions considered to be negligible. Operational emissions are considered to be negligible because the primary source of emissions would be from maintenance vehicles used by workers to visit the substations and patrol the T/L routes. As previously mentioned, operation emissions are expected to be negligible and well below the significance thresholds, and would not create significant air quality impacts. Therefore, the operation of the TRTP would not conflict with or obstruct implementation of the applicable air quality plan.

Would the proposed Project violate any air quality standards or contribute substantially to an existing or projected air quality violation?

To determine whether implementation of the proposed Project would violate any air quality standards or contribute substantially to an existing or projected air quality violation, a worst-case scenario approach was taken to ensure that all potential air quality impacts are assessed. As such, emissions occurring during peak construction activities were quantified and used to determine air quality impacts. Overall Project construction emissions (i.e., considering overlapping emissions, by air basin, for all applicable TRTP segments) are presented in
Table 4.4-31.

As shown in Table 4.4-31, annual construction emissions for the overall TRTP would exceed the AVAQMD’s significance thresholds for NO_X in year 2010 and PM₁₀ in years 2010, 2011, and 2012 and, therefore, would be considered to have significant air quality impacts. Similarly, the comparison of the peak daily construction emissions with the SCAQMD significance thresholds shows that all pollutants exceed the thresholds with the exception of SO_2. The implementation of APMs identified in Section 4.4.5 would reduce overall emissions, but air quality impacts would remain significant and unavoidable during peak year construction in both air basins, although impacts would be short-term. Emissions from the operation of proposed TRTP facilities are considered to be negligible. Hence, the construction of the entire TRTP could potentially contribute to existing violations of O₃ and PM₁₀ air quality standards. Therefore, the construction of the entire TRTP would have a significant impact on air quality.

TABLE 4.4-31
OVERALL TRTP CONSTRUCTION EMISSION/AIR DISTRICT
REGIONAL EMISSION THRESHOLD COMPARISON

¹   Emissions are from construction activities occurring in year 2009 from Segment 4 in KCAPCD jurisdiction (MDAB region).

²   Emissions are from construction activities occurring in year 2010 from Segments 4 and 9 in KCAPCD jurisdiction (MDAB region).

³   Emissions are from construction activities occurring in year 2011 from Segments 4, 9, and 10 in KCAPCD jurisdiction (MDAB region).

⁴   Emissions are from construction activities occurring in year 2009 from Segments 4 and 6 in AVAQMD jurisdiction (MDAB region).

⁵   Emissions are from construction activities occurring in year 2010 from Segments 4, 5, 6, and 9 in AVAQMD jurisdiction (MDAB region).

⁶    Emissions are from construction activities occurring in year 2011 from Segments 4, 5, 6, and 9 in AVAQMD jurisdiction (MDAB region).

⁷   Emissions are from construction activities occurring in year 2012 from Segments 6, 9, and 11 in AVAQMD jurisdiction (MDAB region).

⁸   Emissions are from construction activities occurring in year 2013 from Segments 9 and 11 in AVAQMD jurisdiction (MDAB region).

⁹   Emissions are from construction activities occurring in year 2009 from Segments 6, 7, and 9 in SCAQMD jurisdiction (SCAB region).

¹⁰  Emissions are from construction activities occurring in year 2010 from Segments 6, 7, and 8 in SCAQMD jurisdiction (SCAB region).

¹¹  Emissions are from construction activities occurring in year 2011 from Segments 6, 7, 8, and 9 in SCAQMD jurisdiction (SCAB region).

¹²  Emissions are from construction activities occurring in year 2012 from Segments 6, 8, 9, and 11 in SCAQMD jurisdictions (SCAB region).

¹³  Emissions are from construction activities occurring in year 2013 from Segments 9 and 11 in SCAQMD jurisdictions (SCAB region).

Would the proposed Project result in a cumulatively considerable net increase of any criteria pollutant for which the Project region is classified as nonattainment under an applicable federal or state AAQS (including releasing emissions which exceed quantitative thresholds for ozone precursors)?

Federal General Conformity Rule. If the project were to cause annual emissions that exceed the GCR DeMinimis thresholds, SCE would be required to prepare a comprehensive Air Quality Conformity Analysis and Determination. It should be noted that the GCR DeMinimis thresholds are for the entire air basins and are not for individual air districts. Therefore, to determine conformity requirements for MDAB, construction emissions generated in Kern County (i.e., KCAPCD jurisdiction) are added to emissions generated in northern Los Angeles County (i.e., AVAQMD jurisdiction). Based on the current proposed Project schedule, the maximum annual construction emissions for the proposed Project would occur in 2010 within the MDAB and in the SCAB. Annual construction emissions for year 2010 in the MDAB and the SCAB were compared to their respective GCR DeMinimisthresholds and are provided in Table 4.4-32.

Table 4.4-32 shows that the maximum annual construction emissions generated within the MDAB in year 2010 are well below the GCR DeMinimis thresholds, and are therefore considered to be consistent with the SIP. However, annual emissions generated during the peak construction year within the SCAB exceeds the NO_X thresholds by 9.6 percent and are under the thresholds for all other pollutants. To ensure the proposed Project conforms to the SIP, NO_X emissions would have to be reduced by a minimum of 9.6 percent. It should be noted that construction emissions were estimated based on a worst-case scenario (e.g., all construction activities were assumed to overlap throughout the entire year), which is unlikely. NO_X emissions are directly correlated with the number and type of equipment used

TABLE 4.4-32
PROPOSED PROJECT EMISSIONS/GENERAL CONFORMITY EMISSIONS THRESHOLD COMPARISON

and operating hours. Based on this consideration, NO_X emissions could be reduced through various methods such as reducing the number of equipment operating at any one time, extending the construction time frame, and/or scheduling of equipment to reduce duplicate equipment operating for the same purpose during the construction phase. The detailed annual emissions calculations and associated assumptions used in the calculations are provided in Appendix G. While this impact is potentially significant based on preliminary engineering and the preceding “worst-case scenario” analysis, it is anticipated that final engineering would be expected to reduce the impact to a less-than-significant level.

Would the proposed Project expose sensitive receptors to substantial pollutant concentrations?

Construction activities and associated emissions generated during the various construction phases could potentially affect sensitive receptors located near the construction route. The use of construction equipment in these urbanized areas would create air quality impacts, but with the implementation of the APMs and mitigation measures provided in Section 4.4.5, localized air quality impacts would be expected to be minimal and considered to have less than significant impact. After the construction of the entire TRTP was complete (i.e., in 2013), operational emissions would be generated from the operation of maintenance vehicles driven to the TRTP sites, parked for a short duration, then driven off, and therefore are considered negligible. Hence, the emissions generated from the construction and operation of the proposed TRTP would not be expected to expose nearby sensitive receptors to substantial pollutant concentrations, and impacts would be expected to be less than significant.

Would the proposed Project create objectionable odors that would affect a substantial amount of people?

The use of diesel construction equipment during various construction phases may generate odor that are considered to be a nuisance. Diesel equipment and asphalt paving emit a distinctive odor that may be considered offensive to certain individuals. These odors would be temporary and would not affect a substantial number of people. Therefore, the odor impacts from the proposed project’s construction and operation would be less than significant and no mitigation measures would be required.

4.4.8 References

AVAQMD (Antelope Valley Air Quality Management District). 2002. California Environmental Quality Act (CEQA) and Federal Conformity Guidelines. May.

2004. Revised Draft AVAQMD 2004 Ozone Attainment Plan (State and Federal). March.

2005. List and Implementation Schedule for District Measures to Reduce PM Pursuant to Health & Safety Code Subsection 39614(d). August.

2007. Website: http://www.avaqmd.ca.gov/.

California Department of Conservation, Division of Mines and Geology. 2000. A General Location Guide for Ultramafic Rocks in California - Areas More Likely to Contain Naturally Occurring Asbestos Map.

CARB (California Air Resources Board) 2003. Website: http://www.arb.ca.gov/ei/areasrc/ONEHTM/ONE7-7.HTM.

2006. Website: http://www.arb.ca.gov/adam/cgi-bin/db2www/adamtop4b.d2w/start.

2007. Website: http://www.arb.ca.gov/research/aaqs/aaqs2.pdf.

2007a. KCAPCD Rule 210.1. Website: http://www.arb.ca.gov/DRDB/KER/CURHTML/
R210-1.HTM. Accessed April.

FAA (Federal Aviation Agency). 2001. Federal Aircraft Engine Emissions Database.

Governor’s Office of Planning and Research. 2000. Memorandum Addressing Naturally Occurring Asbestos in CEQA Documents. October.

KCAPCD (Kern County Air Pollution Control District). 2000. Regional Air Quality Thresholds.

2005. CEQA Handbook.

2007. Website: http://www.kernair.org/.

SCAQMD (South Coast Air Quality Management District) 1993. CEQA Air Quality Handbook.

1996. 1997 Final Air Quality Management Plan. November.

2003. 2003 Final Air Quality Management Plan. August.

2006a. Off-road emission factors: http://www.aqmd.gov/ceqa/handbook/offroad/offroad.html. December.

2006b. Regional Air Quality Significance Thresholds: http://www.aqmd.gov/ceqa/handbook/signthres.doc.

2007a. On-road emission factors: http://www.aqmd.gov/ceqa/handbook/onroad/onroad.html. March.

2007b. Website: http://www.aqmd.gov/ceqa/hdbk.html.

SCE (Southern California Edison). 2006. Antelope-Pardee 500-kV Transmission Project. December.

U.S. Census Bureau. 2003. Table 5. SUB-EST2002-05-06-California Incorporated Place Population Estimates, Sorted within County: April 1, 2000 to July 1, 2002. July.

USDA Forest Service. 2005a. Land Management Plan. Part 2 Angeles National Forest Strategy. September.

USEPA (United States Environmental Protection Agency). 2007. Green Book website: http://www.epa.gov/oar/oaqps/greenbk/multipol.html.

Western Regional Climate Center. Climate of California.

(Footnotes)

1  Fugitive dust emissions do not consider workers’ vehicles commuting to work, such as entrained dust generated from construction vehicles traveling on paved roads. Such emissions have been accounted for in the emissions budget of the State Implementation Plan (SIP).