Solano 4 Wind Project EIR July 2019

3.10. Noise

This section describes ambient-noise conditions and provides an analysis of potential short-term construction and decommissioning, as well as long-term operational-source noise impacts associated with the proposed project. Applicable regulations related to noise and vibration provide the regulatory background that guides the assessment of potential environmental effects. Mitigation measures are recommended as necessary to reduce significant noise impacts. Additional data are provided in Appendix H.

3.10.1. Acoustics Terminology and Background

Background information about sound, noise, vibration, and common noise descriptors is included below to provide context and to explain the technical terms referenced throughout this section.

Sound, Noise, and Acoustics

Sound can be described as the mechanical energy of a vibrating object transmitted by pressure waves through a liquid or gaseous medium (e.g., air) to a human ear. Noise is defined as loud, unexpected, annoying, or unwanted sound.

The field of acoustics deals primarily with the propagation and control of sound. The fundamental acoustical model consists of a sound (or noise) source, a receiver, and the propagation path between the two. The loudness of the source and obstructions or atmospheric factors affecting the propagation path to the receiver determines the level and characteristics of the sound perceived by the receiver.

Frequency

Continuous sound can be described by frequency (pitch) and amplitude (loudness). A low-frequency sound is perceived as low in pitch. Frequency is expressed in terms of cycles per second, or hertz (Hz) (e.g., a frequency of 250 cycles per second is referred to as 250 Hz). High frequencies are sometimes more conveniently expressed in kilohertz, or thousands of hertz. The audible frequency range for humans is generally between 20 Hz and 20,000 Hz.

Sound Pressure Levels and Decibels

The amplitude of pressure waves generated by a sound source determines the loudness of that source. Sound pressure amplitude is measured in micro-Pascals (mPa). One mPa is approximately one hundred billionth (0.00000000001) of normal atmospheric pressure. Sound pressure amplitudes for different kinds of noise environments can range from less than 100 to 100,000,000 mPa. Because of this large range of values, sound is rarely expressed in terms of mPa. Instead, a logarithmic scale is used to describe sound pressure level (SPL) in terms of decibels (dB).

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Addition of Decibels

Because decibels are logarithmic units, SPLs cannot be added or subtracted through ordinary arithmetic. Under the decibel scale, a doubling of sound energy corresponds to a 3-dB increase. In other words, when two identical sources are each producing sound of the same loudness at the same time, the resulting sound level at a given distance would be 3 dB higher than if only one of the sound sources was producing sound under the same conditions. For example, if one idling truck generates an SPL of 70 dB, two trucks idling simultaneously would not produce 140 dB; rather, they would combine to produce 73 dB. Under the decibel scale, three sources of equal loudness together produce a sound level approximately 5 dB louder than one source.

A-Weighted Decibels

The decibel scale alone does not adequately characterize how humans perceive noise. The dominant frequencies of a sound have a substantial effect on the human response to that sound. Although the intensity (energy per unit area) of the sound is a purely physical quantity, the loudness or human response is determined by the characteristics of the human ear.

Human hearing is limited in the range of audible frequencies as well as in the way it perceives the SPL in that range. In general, people are most sensitive to the frequency range of 1,000–8,000 Hz and perceive sounds within this range better than sounds of the same amplitude with frequencies outside of this range. To approximate the response of the human ear, sound levels of individual frequency bands are weighted, depending on the human sensitivity to those frequencies. Then, an “A-weighted” sound level (expressed in units of A-weighted decibels) can be computed based on this information.

The A-weighting network approximates the frequency response of the average young ear when listening to most ordinary sounds. When people make judgments of the relative loudness or annoyance of a sound, their judgment correlates well with the A-scale sound levels of those sounds. Thus, noise levels are typically reported in terms of A-weighted decibels. All sound levels discussed in this section are A-weighted decibels. Table 3.10- 1 describes typical A-weighted noise levels for various noise sources.

Human Response to Changes in Noise Levels

As discussed above, the doubling of sound energy results in a 3-dB increase in the sound level. However, given a sound level change measured with precise instrumentation, the subjective human perception of a doubling of loudness will usually be different from what is measured.

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Table 3.10-1 Typical A-Weighted Noise Levels Noise Level Common Outdoor Activities Common Indoor Activities (dB) — 110 — Rock band Jet fly-over at 1,000 feet — 100 — Gas lawn mower at 3 feet — 90 — Food blender at 3 feet, Garbage disposal at Diesel truck at 50 feet at 50 miles per hour — 80 — 3 feet Noisy urban area, daytime, Gas lawn Vacuum cleaner at 10 feet, Normal speech — 70 — mower at 100 feet at 3 feet Commercial area, Heavy traffic at 300 feet — 60 — Large business office, Dishwasher next Quiet urban daytime — 50 — room Theater, large conference room Quiet urban nighttime — 40 — (background) Quiet suburban nighttime — 30 — Library, Bedroom at night Quiet rural nighttime — 20 — — 10 — Broadcast/recording studio Lowest threshold of human hearing — 0 — Lowest threshold of human hearing Source: Caltrans 2013a: Table 2-5

Under controlled conditions in an acoustical laboratory, the trained, healthy human ear is able to discern 1-dB changes in sound levels when exposed to steady, single-frequency (“pure-tone”) signals in the mid-frequency (1,000–8,000 Hz) range. In general, the healthy human ear is most sensitive to sounds between 1,000 and 5,000 Hz and perceives both higher and lower frequency sounds of the same magnitude with less intensity (Caltrans 2013a:2-18). In typical noisy environments, changes in noise of 1–2 dB are generally not perceptible. However, it is widely accepted that people are able to begin to detect sound level increases of 3 dB in typical noisy environments. Further, a 5-dB increase is generally perceived as a distinctly noticeable increase, and a 10-dB increase is generally perceived as a doubling of loudness (Caltrans 2013a:2-10). Therefore, a doubling of sound energy (e.g., doubling the volume of traffic on a highway) that would result in a 3-dB increase in sound would generally be perceived as barely detectable.

Vibration

Vibration is the periodic oscillation of a medium or object with respect to a given reference point. Sources of vibration include natural phenomena (e.g., earthquakes, volcanic eruptions, sea waves, landslides) and those introduced by human activity (e.g., explosions, machinery, traffic, trains, construction equipment). Vibration sources may be continuous (e.g., operating factory machinery) or transient (e.g., explosions). Vibration levels can be depicted in terms of amplitude and frequency, relative to displacement, velocity, or acceleration.

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Vibration amplitudes are commonly expressed in peak particle velocity (PPV) or root- mean-square (RMS) vibration velocity. PPV and RMS vibration velocity are normally described in inches per second (in/sec) or in millimeters per second. PPV is defined as the maximum instantaneous positive or negative peak of a vibration signal. PPV is typically used in the monitoring of transient and impact vibration and has been found to correlate well to the stresses experienced by buildings (FTA 2018:7-3, Caltrans 2013a:6).

Although PPV is appropriate for evaluating the potential for building damage, it is not always suitable for evaluating human response. It takes some time for the human body to respond to vibration signals. In a sense, the human body responds to average vibration amplitude. The RMS of a signal is the average of the squared amplitude of the signal, typically calculated over a 1-second period. As with airborne sound, the RMS velocity is often expressed in decibel notation as vibration decibels (VdB), which serves to compress the range of numbers required to describe vibration (FTA 2018:7-4; Caltrans 2013b:7). This is based on a reference value of 1 microinch per second.

The typical background vibration-velocity level in residential areas is approximately 50 VdB. Ground vibration is normally perceptible to humans at approximately 65 VdB. For most people, a vibration-velocity level of 75 VdB is the approximate dividing line between barely perceptible and distinctly perceptible levels (FTA 2018:7-8; Caltrans 2013b:27).

Typical outdoor sources of perceptible ground vibration are construction equipment, steel- wheeled trains, and traffic on rough roads. If a roadway is smooth, the ground vibration is rarely perceptible. The range of interest is from approximately 50 VdB, which is the typical background vibration-velocity level, to 100 VdB, which is the general threshold where minor damage can occur to fragile buildings. Construction activities can generate sufficient ground vibrations to pose a risk to nearby structures. Constant or transient vibrations can weaken structures, crack facades, and disturb occupants (FTA 2018:7-5).

Vibrations generated by construction activity can be transient, random, or continuous. Transient construction vibrations are generated by blasting, impact pile driving, and wrecking balls. Continuous vibrations are generated by vibratory pile drivers, large pumps, and compressors. Random vibration can result from jackhammers, pavement breakers, and heavy construction equipment.

Table 3.10-2 summarizes the general human response to different ground vibration- velocity levels.

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Table 3.10-2 Human Response to Different Levels of Ground Noise and Vibration Vibration-Velocity Level Human Reaction 65 VdB Approximate threshold of perception. Approximate dividing line between barely perceptible and distinctly 75 VdB perceptible. Many people find that transportation-related vibration at this level is unacceptable. 85 VdB Vibration acceptable only if there are an infrequent number of events per day. Notes: VdB = vibration decibels referenced to 1 microinch/second and based on the root mean square velocity amplitude. Source: FTA 2018:7-8

Common Noise Descriptors

Noise in our daily environment fluctuates over time. Various noise descriptors have been developed to describe time-varying noise levels. The following noise descriptors are used throughout this section.

• Equivalent Continuous Sound Level (Leq): Leq represents an average of the sound energy occurring over a specified period. In effect, Leq is the steady-state sound level containing the same acoustical energy as the time-varying sound level that actually occurs during the same period (Caltrans 2013a:2-48). For instance, the 1-hour equivalent sound level, also referred to as the hourly Leq, is the energy average of sound levels occurring during a 1-hour period and is the basis for noise abatement criteria used by the California Department of Transportation (Caltrans) and the Federal Highway Administration (FHWA) (Caltrans 2013a:2-47; FTA 2018:2-19).

• Percentile-Exceeded Sound Level (LX): LX represents the sound level exceeded for a given percentage of a specified period (e.g., L10 is the sound level exceeded 10 percent of the time, and L90 is the sound level exceeded 90 percent of the time) (Caltrans 2013a:2-16).

• Maximum Sound Level (Lmax): Lmax is the highest instantaneous sound level measured during a specified period (Caltrans 2013a:2-48; FTA 2018:2-16).

• Day-Night Level (Ldn): Ldn is the energy average of A-weighted sound levels occurring over a 24-hour period, with a 10-dB “penalty” applied to sound levels occurring during nighttime hours between 10 p.m. and 7 a.m. (Caltrans 2013a:2- 48; FTA 2018:2-22).

• Community Noise Equivalent Level (CNEL): Similar to Ldn, CNEL is the energy average of the A-weighted sound levels occurring over a 24-hour period, with a 10-dBA penalty applied to A-weighted sound levels occurring during the nighttime hours between 10 p.m. and 7 a.m. and a 5-dBA penalty applied to the A-weighted sound levels occurring during evening hours between 7 p.m. and 10 p.m.

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Sound Propagation

When sound propagates over a distance, it changes in level and frequency content. The manner in which a noise level decreases with distance depends on the factors described below.

Geometric Spreading

Sound from a localized source (i.e., a point source) propagates uniformly outward in a spherical pattern. The sound level attenuates (or decreases) at a rate of 6 dB for each doubling of distance from a point source. Roads and highways consist of several localized noise sources on a defined path and hence can be treated as a line source, which approximates the effect of several point sources. Thus, the sound from a line source propagates at a slower rate than the sound from a point source. Noise from a line source propagates outward in a cylindrical pattern, often referred to as cylindrical spreading. Sound levels attenuate at a rate of 3 dB for each doubling of distance from a line source.

Ground Absorption

The propagation path of noise from a source to a receiver is usually very close to the ground. Noise attenuation from ground absorption and reflective-wave canceling provides additional attenuation associated with geometric spreading. Traditionally, this additional attenuation has also been expressed in terms of attenuation per doubling of distance. This approximation is usually sufficiently accurate for distances of less than 200 feet. For acoustically hard sites (i.e., sites with a reflective surface between the source and the receiver, such as a parking lot or body of water), no excess ground attenuation is assumed. For acoustically absorptive or soft sites (i.e., those sites with an absorptive ground surface between the source and the receiver, such as soft dirt, grass, or scattered bushes and trees), additional ground-attenuation value of 1.5 dB per doubling of distance is normally assumed. When added to the attenuation rate associated with cylindrical spreading, the additional ground attenuation results in an overall drop-off rate of 4.5 dB per doubling of distance. This would hold true for point sources, resulting in an overall drop-off rate of up to 7.5 dB per doubling of distance.

Atmospheric Effects

Receivers located downwind from a source can be exposed to increased noise levels relative to calm conditions, whereas locations upwind can have lowered noise levels, as wind can carry sound. Sound levels can be increased over large distances (e.g., more than 500 feet) from the source because of atmospheric temperature inversion (i.e., increasing temperature with elevation). Other factors such as air temperature, humidity, and turbulence can also affect sound attenuation.

Shielding by Natural or Human-Made Features

A large object or barrier in the path between a noise source and a receiver attenuate noise levels at the receiver. The amount of attenuation provided by shielding depends on

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the size of the object and the frequency content of the noise source. Natural terrain features (e.g., hills and dense woods) and human-made features (e.g., buildings and walls) can substantially reduce noise levels. A barrier that breaks the line of sight between a source and a receiver will typically result in at least 5 dB of noise reduction (Caltrans 2013a:2-41; FTA 2018:5-6, 6-25). Barriers higher than the line of sight provide increased noise reduction (FTA 2018:2-12). Vegetation between the source and receiver is rarely effective in reducing noise because it does not create a solid barrier unless there are multiple rows of vegetation (FTA 2018:2-11).

3.10.2. Regulatory Setting

Federal

U.S. Environmental Protection Agency Office of Noise Abatement and Control

The U.S. Environmental Protection Agency (EPA) Office of Noise Abatement and Control was originally established to coordinate Federal noise control activities. In 1981, EPA administrators determined that subjective issues such as noise would be better addressed at more local levels of government. Consequently, in 1982 responsibilities for regulating noise control policies were transferred to state and local governments. However, documents and research completed by the EPA Office of Noise Abatement and Control continue to provide value in the analysis of noise effects.

Federal Transit Administration

To address the human response to ground vibration, the Federal Transit Administration (FTA) has set forth guidelines for maximum-acceptable vibration criteria for different types of land uses. These guidelines are listed in Table 3.10-3.

State

California General Plan Guidelines

Though not adopted by law, the State of California General Plan Guidelines 2003, published by the Governor’s Office of Planning and Research (OPR 2003), provide guidance for the compatibility of projects within areas of specific noise exposure. Acceptable and unacceptable community noise exposure limits for various land use categories have been determined to help guide new land use decisions in California communities. In many local jurisdictions, these guidelines are used to derive local noise standards and guidance. Citing EPA materials and the State Sound Transmissions Control Standards, the state’s general plan guidelines recommend interior and exterior noise standards of 45 and 60 dB CNEL for residential units, respectively (OPR 2003: 253–254).

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Table 3.10-3 Groundborne Vibration Impact Criteria for General Assessment Groundborne Vibration Impact Levels (VdB re 1 microinch/second) Land Use Category Frequent Occasional Infrequent Events1 Events2 Events3 Category 1: Buildings where vibration would interfere with 65 4 65 4 65 4 interior operations. Category 2: Residences and buildings where people 72 75 80 normally sleep. Category 3: Institutional land uses with primarily daytime 75 78 83 uses. Notes: VdB = vibration decibels referenced to 1 microinch/second and based on the root mean square velocity amplitude. 1 “Frequent Events” is defined as more than 70 vibration events of the same source per day. 2 “Occasional Events” is defined as between 30 and 70 vibration events of the same source per day. 3 “Infrequent Events” is defined as fewer than 30 vibration events of the same source per day. 4 This criterion is based on levels that are acceptable for most moderately sensitive equipment such as optical microscopes. Vibration-sensitive manufacturing or research would require detailed evaluation to define acceptable vibration levels. Source: FTA 2018

California Department of Transportation

The Transportation and Construction Vibration Manual (Caltrans 2013a) provides general guidance on vibration issues associated with construction and operation of projects in relation to human perception and structural damage. Table 3.10-4 presents recommendations for levels of vibration that could result in damage to structures exposed to continuous vibration.

Table 3.10-4 Caltrans Recommendations Regarding Levels of Vibration Exposure PPV (in/sec) Effect on Buildings 0.4–0.6 Architectural damage and possible minor structural damage 0.2 Risk of architectural damage to normal dwelling houses 0.1 Virtually no risk of architectural damage to normal buildings Recommended upper limit of vibration to which ruins and ancient monuments should 0.08 be subjected 0.006–0.019 Vibration unlikely to cause damage of any type Notes: in/sec = inches per second; PPV = peak particle velocity Source: Caltrans 2013

Local

As discussed in Section 1.2, construction of facilities for the production of electrical energy by a local agency like SMUD is exempt from County zoning and building ordinances (Government Code ARTICLE 5. Regulation of Local Agencies by Counties and Cities

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[53090 - 53097.5]). The following discussion is provided to promote informed decisionmaking.

Solano County General Plan

The noise goal in the Solano County General Plan (General Plan) Health and Safety Element, HS.G-3, is to protect people living, working, and visiting Solano County from the harmful impacts of excessive noise. The Public Health and Safety Element (Solano County 2015) contains noise level standards.

Table HS-3 in the General Plan, presented here as Table 3.10-5, shows the acceptable noise levels for various land use categories.

Table 3.10-5 Land Use Noise Compatibility Guidelines Community Noise Exposure (Ldn or CNEL, dBA) Normally Conditionally Normally Clearly Land Use Category Acceptable1 Acceptable2 Unacceptable3 Unacceptable4 Residential—Low Density Single Family, <65 55–70 70–75 75+ Duplex, Mobile Home Residential— Multifamily <65 60–70 70–75 75+ Transient Lodging—Motel, Hotel 60–70 70–80 80+ Schools, Libraries, Churches, Hospitals, <70 60–70 70–80 80+ Nursing Homes Auditoriums, Concert Halls, Amphitheaters <70 65+ Sports Arena, Outdoor Spectator Sports <75 70+ Playgrounds, Neighborhood Parks <70 67.5–75 72.5+ Golf Courses, Riding Stables, Water <70 70–80 80+ Recreation, Cemeteries Office Building, Business Commercial, and <70 67.5–77.5 75+ Professional Industrial, Manufacturing, Utilities, <75 70–80 75+ Agriculture Notes: CNEL = community noise equivalent level; dBA = A-weighted decibel; Ldn = day-night average noise level 1 Specified land use is satisfactory, based upon the assumption that any buildings involved are of normal conventional construction, without any special noise insulation requirements. 2 New construction or development should be undertaken only after a detailed analysis of the noise reduction requirements is made and needed noise insulation features included in the design. Conventional construction, but with closed windows and fresh air supply systems or air conditioning will normally suffice. 3 New construction or development should generally be discouraged. If new construction or development does proceed, a detailed analysis of the noise reduction requirements must be made and needed noise insulation features included in the design. Outdoor areas must be shielded. 4 New construction or development should generally not be undertaken. 5 These standards are not applicable for development within the airport compatibility review area. Development in the airport compatibility review areas are subject to standards in the applicable airport land use plan. Sources: OPR 2003; Solano County 2015.

Table HS-4 in the General Plan, presented here as Table 3.10-6, defines acceptable outdoor and interior noise levels for land uses affected by traffic and railroad noise.

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Table 3.10-6 Noise Standards for New Uses Affected by Traffic and Railroad Noise 1 Sensitive Outdoor Sensitive Interior New Land Use Are a (dBA Ldn) Area (dBA Ldn) Notes All Residential 65 45 2 Transient Lodging 65 45 2, 3 Hospitals and Nursing Homes 65 45 2, 3, 4 Theaters and Auditoriums – 35 3 Churches, Meeting Halls, Schools, Libraries, etc. 65 40 3 Office Buildings 65 45 3 Commercial Buildings – 50 3 Playgrounds, Parks, etc. 70 – Industry 65 50 3 Notes: dBA = A-weighted decibels; Ldn = day-night average noise level 1 Interior-noise-level standards are applied within noise -sensitive areas of the various land uses, with windows and doors in the closed positions. 2 If these uses are affected by nighttime railroad passages, the potential for sleep disturbance shall be addressed 3 Where there are no sensitive exterior spaces proposed for these uses, only the interior-noise- level standard shall apply. 4 Hospitals are often noise-generating uses. The exterior-noise-level standards for hospitals are applicable only at clearly identified areas designated for outdoor relaxation by either hospital staff or patients. Source: Solano County 2015.

Table HS-5 in the General Plan, presented here as Table 3.10-7, defines noise performance standards for nontransportation noise.

Table 3.10-7 Nontransportation Noise Standards—Average (dBA Leq)/Maximum (dBA 1 Lmax) Outdoor Area Interior2 Receiving Land Use Daytime Nighttime Day and Night Notes All Residential 55/70 55/65 35/55 Transient Lodging 55/75 – 35/55 3 Hospitals and Nursing Homes 55/75 – 35/55 4,5 Theaters and Auditoriums – – 30/50 5 Churches, Meeting Halls, Schools, Libraries, etc. 55/75 – 35/60 5 Office Buildings 55/75 – 45/65 5 Commercial Buildings 55/75 – 45/65 5 Playgrounds, Parks, etc. 55/75 – – 5 Industry 55/80 – 50/70 5 Notes: Leq = equivalent or energy-averaged sound level; Lmax = highest root-mean-square sound level measured over a given period of time 1 The standards shall be reduced by 5 dBA for sounds consisting primarily of speech or music, and for recurring impulsive sounds. If the existing ambient noise level exceeds the standards, then the noise level standards shall be increased at 5-dBA increments to encompass the ambient. 2 Interior-noise-level standards are applied within noise-sensitive areas of the various land uses, with windows and doors in the closed positions. 3 Outdoor activity areas of transient lodging facilities are not commonly used during nighttime hours. 4 Hospitals are often noise-generating uses. The exterior-noise-level standards for hospitals are applicable only at clearly identified areas designated for outdoor relaxation by either hospital staff or patients. 5 The outdoor activity areas of these uses (if any), are not typically utilized during nighttime hours. Source: Solano County 2015.

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Solano County Code

Article III, “Land use Regulations,” Section 28.70.10, “General Development Standards Applicable to All Uses in Every Zoning District,” of the Solano County Code requires all uses of land and structures be conducted in a manner, and provide adequate controls and operational management, to prevent noise levels exceeding 65 dBA Ldn at any property line. Section 28.80, “Commercial Wind Energy Facilities,” states that noise emitted from any wind turbine generator (WTG) shall not exceed 50 dBA CNEL at any property line abutting a residential zone or 60 dBA CNEL at any other property line (Solano County 2018).

Solano County Wind Turbine Siting Plan and Environmental Impact Report

The WTG operation levels studied for the adjacent High Winds Power Project indicated 80 percent, 86 percent, and 88 percent operation for daytime, evening, and nighttime periods, respectively. These percentages would be used to help calculate hourly equivalent sound level (Leq), from which day-night average sound level (Ldn) and community noise equivalent level (CNEL) can be derived and assumed to apply under conditions when WTGs are operating.

In addition to the A-weighted sound levels, the Solano County Wind Turbine Siting Plan and Environmental Impact Report (Siting Plan) (Solano County 1987) and the National Wind Coordinating Committee (NWCC) Permitting of Wind Energy Facilities Handbook (NWCC 2002) address low-frequency noise. Both suggest increasing WTG setback distance from dwelling units, residential building sites, or residentially zoned land to a mile if low-frequency (20–100 Hz) noise is prominent. However, because the WTGs associated with this project feature upwind rotor arrangement, the likelihood of low- frequency noise is remote. “Upwind” refers to the rotor disc positioned upstream from the WTG support tower. In this configuration, rotor blades do not interact with tower-induced wakes that can cause low frequency blade passage tones.

Draft Final Solano County Noise Ordinance County Code, Chapter 28.1

Section 28.1-30, “Interior Noise Standards,” includes the interior noise standards for residential dwelling units within residential zones or areas for noise generated by sources outside the dwelling unit. These standards are presented in Table 3.10-8.

Table 3.10-8 Interior Noise Standards Allowable Interior Noise Level Land Use Time Interval (dBA) 7 p.m.–7 a.m. 45 Residential 7 a.m.–7 p.m. 55 Note: dBA = A-weighted decibels Source: Solano County 2018:Table 28.1.30

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Noise from any source on a property within a residential zone or area shall not cause the noise level measured inside a dwelling unit on a neighboring property to exceed the noise standard specified in Table 3.10-8 for a cumulative period of more than 5 minutes in any hour.

Section 28.1-40, “Exterior Noise Standards,” limits the maximum permissible sound levels by receiving land use. The exterior noise standards for residential and agricultural zones or areas are presented in Table 3.10-9 and summarized further below.

Table 3.10-9 Noise Levels Permissible by Receiving Land Uses Noise Level (dBA) Zone 7 a.m.–7 p.m. 7 p.m.–7 a.m. Agricultural 55 50 Residential 55 50 Source: Solano County 2018:Table 28.1.40

1. If the measured ambient noise level at the time of a complaint investigation exceeds the identified permissible noise level for that zone, the allowable noise standard shall be the ambient noise level.

2. Except as provided in subsection (b) of Section 28.1-30, noise from any source shall not cause the noise level measured on a property in an agricultural or residential zone or area to exceed the exterior noise levels specified in Table 28.1-40 or in subsection (2), whichever is greater, for a period of more than 5 minutes in any hour.

In addition to the standards established in Sections 28.1-30 and 28.1-40, noise created by specific activities shall be subject to the following additional regulations in Section 28.1- 50, “Specific Noise Regulations”:

(a) Construction or Demolition

1) Construction and demolition activities within a residential district or within a radius of 500 feet are allowed only during the times specified in Table 28.1-50 (Note: Table 3.10-10 of this EIR).

2) Except as set forth in subsection (5) of this section, the noise created by construction activity shall not cause:

a. The noise level to exceed the noise standards specified in Table 28.1–40 of this chapter (Note: Table 3.10-9 of this EIR), for the land use where the measurement is taken, plus 20 dBA, for a period of more than 2 minutes; or

b. A maximum noise at the receiving property line of more than 90 dBA at any time.

3) Any construction that exceeds noise levels established in Sections 28.1-30 or 28.1-40 shall occur between the hours of 9 a.m. and 4 p.m., Monday through Friday.

4) Construction or demolition activity during the times otherwise prohibited by this section may be allowed as described in this subsection if it is found to be in the public interest.

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a. A request for such allowance shall be in writing and shall set forth in detail facts showing that the public interest will be served by the grant of such allowance.

b. If the allowance is being requested in connection with construction or demolition activities to be undertaken in connection with a land division, use permit, or other discretionary entitlement, the request shall be submitted as part of the application for such entitlement and shall be acted upon by the official or decision-making body taking action on such application, after considering the recommendation of the noise control officer.

c. If the allowance is being requested in connection with a building permit, demolition permit, or grading permit and is not in connection with a discretionary entitlement, the request shall be considered and acted on by the noise control officer before the construction or demolition permit has been issued.

Table 3.10-10 Time Limits for Noise Associated with Commercial Construction Activities Day of Week Time Frame Monday–Friday 7 a.m.–6 p.m. Saturday 8 a.m.–5 p.m. Sunday Not allowed Federal Holidays Not allowed Source: Solano County 2018:Table 28.1-50

3.10.3. Environmental Setting

Existing Noise- and Vibration-Sensitive Land Uses

Noise-sensitive land uses are generally considered to include those uses where noise exposure could result in health-related risks to individuals, as well as places where quiet is an essential element of their intended purpose. Residential dwellings are of primary concern because of the potential for increased and prolonged exposure of individuals to both interior and exterior noise levels, and because of the potential for nighttime noise to result in sleep disruption. Additional land uses such as schools, transient lodging, historic sites, cemeteries, parks, recreational areas, and places of worship are also generally considered sensitive to increases in noise levels. These land use types are also considered vibration-sensitive land uses, as are commercial and industrial buildings, where vibration would interfere with operations within the building, including levels that may be well below those associated with human annoyance.

The nearest noise-sensitive receptors are single-family rural residences located along Montezuma Hills Road (Solano 4 East project subarea) and Talbert Lane (Solano 4 West project subarea) adjacent to the project site, approximately 3,100 feet and 1,400 feet from the project site boundary, respectively. The historically significant Hastings Adobe structure is located within the project boundary, but approximately 1,100 feet from the nearest proposed project construction area of the Solano 4 West subarea. Exhibit 3.10-1 shows the layout of the nearest surrounding receptors relative to the project site.

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Existing Noise Sources and Ambient Levels

To characterize the existing ambient noise environment at the project site, long-term ambient noise level measurements were conducted at three locations at the project site between March 13, 2019, and March 19, 2019. The locations of the noise monitoring sites are shown in Exhibit 3.10-1. To characterize existing WTG noise in the project area, multiple short-term noise measurements were conducted around existing WTGs and at two distances to assess attenuation factors. The locations of the WTG reference noise monitoring sites are shown in Exhibit 3.10-2. Larson Davis Laboratories precision integrating sound level meters Models 820 and 831 were used for the ambient noise level measurement surveys. The meters were calibrated before use with Larson Davis Laboratories Model CAL200 acoustical calibrators to ensure measurement accuracy. The measurement equipment meets all pertinent specifications of the American National Standards Institute. The results of the long-term ambient noise measurement survey are summarized in Table 3.10-11 and results of the short-term WTG reference noise measurements are summarized in Table 3.10-12.

Table 3.10-11 Summary of Existing Ambient Noise Measurements A-Weighted Sound Level (dB) Start Daytime Nighttime 1 Location Date Time Duration Ldn Leq Lmax L50 L90 Leq Lmax L50 L90 LT-1 13-Mar-2019 17:10 24 Hours 61.3 62.4 77.8 45.3 43.0 48.4 60.4 45.1 44.0 LT-2 18-Mar-2019 17:40 24 Hours 62.2 57.6 73.9 51.1 46.2 55.4 64.1 50.5 47.8 LT-3 18-Mar-2019 18:25 24 Hours 49.8 49.0 62.6 38.7 35.1 40.8 49.5 39.2 37.8 ST-12 14-Mar-2019 13:40 0:05 – 53.6 73.8 53.6 53.0 – – – – ST-23 14-Mar-2019 13:47 0:05 – 54.3 82.9 54.2 53.6 – – – – ST-32 14-Mar-2019 13:54 0:05 – 50.4 81.4 50.0 49.1 – – – – ST-43 14-Mar-2019 14:00 0:05 – 48.9 85.6 48.7 47.6 – – – – ST-52 14-Mar-2019 14:08 0:05 – 52.6 78.2 52.6 52.0 – – – – ST-63 14-Mar-2019 14:14 0:06 – 51.9 84.4 51.3 50.3 – – – – ST-72 14-Mar-2019 14:22 0:10 – 52.3 83.9 52.5 49.4 – – – – ST-83 14-Mar-2019 14:33 0:12 – 50.6 82.9 50.7 48.5 – – – – ST-94 14-Mar-2019 14:48 0:10 – 50.1 85.8 49.8 48.7 – – – –

Notes: dB = decibels; Ldn = day-night noise level 1 See Exhibit 3.10-1 for locations of long-term ambient noise level measurements; see Exhibit 3.10-2 for locations of short-term ambient WTG noise level measurements; LT = long-term measurement; ST = short-term measurement. 2 Measurement located 50 feet from base of tower either downwind and upwind wing side of turbine. 3 Measurement located 100 feet from base of tower either downwind and upwind wing side of turbine. 4 Measurement located between two existing turbines in operation at 345 feet from each turbine. Source: Data collected by AECOM in 2019

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Exhibit 3.10-1 Locations of Long-Term Noise Measurements

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Exhibit 3.10-2 Locations of Short-Term Wind Turbine Generator Reference Noise Measurements

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The predominant noise source in the area of LT-1 is vehicle traffic on Montezuma Hills Road. The predominant noise sources in the area of LT-2 are wind-generated noise and other natural sources (e.g., wind, birds, animals) and farm and ranch activities at the nearby house. At LT-3, the predominant noise sources are existing wind-generated noise and other natural sources (e.g., wind, birds, animals). As shown in Table 3.10-11, the ambient operational noise levels for single WTG operation at 50 feet and 100 feet ranged between 50 dBA and 54 dBA and the ambient operational noise levels for two WTGs measured 50 dBA at 345 feet, the midpoint between the two turbines.

3.10.4. Environmental Impacts and Mitigation Measures

Methods and Assumptions

To assess potential short-term (construction- and decommissioning-related) noise and vibration impacts, sensitive receptors and their relative exposure were identified. Project- generated construction source noise and vibration levels were determined based on methodologies, reference emission levels, and usage factors from FTA’s Transit Noise and Vibration Impact Assessment methodology (FTA 2018) and FHWA’s Roadway Construction Noise Model User’s Guide (FHWA 2006). Reference levels are noise and vibration emissions for specific equipment or activity types that are well documented and the usage thereof is common practice in the field of acoustics.

To evaluate relative significance, noise and vibration impacts were determined based on comparisons to applicable regulations and guidance provided by federal and state agencies.

Based on current decommissioning practices, as a reasonable worst case, it is assumed that construction source noise and vibration levels during future decommissioning of the project would be similar to those generated during project construction. Thus, the impact analysis and mitigation that follows apply to project construction as well as decommissioning of the project.

Thresholds of Significance

Based on Appendix G of the State CEQA Guidelines, the project would result in a potentially significant impact on noise if it would cause:

• generation of a substantial temporary or permanent increase in ambient noise levels in the vicinity of the project in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies,

• generation of excessive groundborne vibration or groundborne noise levels, exceeding either of the following:

o Caltrans’s recommended level of 0.08 in/sec PPV with respect to the prevention of structural damage for historical buildings; or

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o FTA’s maximum acceptable level of 80 VdB with respect to human response for residential uses (i.e., annoyance) at nearby existing vibration- sensitive land uses; or

• for a project within the vicinity of a private airstrip or an airport land use plan or, where such a plan has not been adopted, within 2 miles of a public airport or public- use airport, exposure of people residing or working in the project area to excessive noise levels.

Issues Not Discussed Further

The “Impact Analysis” section will not further analyze the proposed project against thresholds of significance for which no significant impacts have been identified. Therefore, the following issues will not be discussed further in the impact analysis.

As explained in Chapter 2, “Project Description,” project operation is expected to generate approximately six vehicular trips per day (one round trip per day) attributed to on-site employee and infrequent monitoring and maintenance trips. This would not result in a substantial increase in noise during operation of the project, because the increase in traffic would be a small fraction of existing and future traffic volumes.

Pickup trucks and flatbeds, forklifts, and loaders may be used for maintenance and repair throughout the lifetime of the project as they are for existing needs. The project is not expected to result in any discernable noise because the daily operation of the project and the associated stationary equipment is not likely to generate a substantial amount of noise. Project maintenance and repair would be similar to existing conditions. Therefore, project operations would not increase the ambient noise level. This issue will not be discussed further.

The closest airport to the project site is Rio Vista Municipal Airport, which is located approximately 5 miles to the northeast. Therefore, the project would not expose residents or workers to excessive noise levels from airport noise. This issue will not be discussed further.

Impact Analysis

Impact 3.10-1: Generation of a Substantial Temporary Increase in Ambient Noise Levels in the Vicinity of the Project in Excess of Standards Established in the Local General Plan or Noise Ordinance, or Applicable Standards of Other Agencies due to Short-term construction noise impacts. Proposed construction areas are located mostly far from existing noise-sensitive receptors, the only closest receptor (LT-2) being approximately 275 feet from where construction activities (underground cabling) would occur. Most noise-generating construction activity would be performed during daytime hours, when people are less sensitive to noise. This impact would be less than significant.

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Construction Activity

Construction of project components would result in temporary, short-term construction activities and haul truck trips to haul wind turbine parts and needed construction materials, equipment, and waste materials to and from the project area. Short-term construction noise levels near the project site would fluctuate depending on the type, number, and duration of usage for the varying equipment. The effects of construction noise largely depend on the type of construction activities being performed, noise levels generated by those activities, distances to noise-sensitive receptors, the relative locations of noise attenuating features such as vegetation and existing structures, and existing ambient noise levels.

As discussed in Section 2.5.10, “Construction Methods and Schedule,” construction of the project is estimated to begin in spring 2020, with completion targeted for winter of 2022. Construction activities at the project site would include initial site preparation work, grading and improving on-site and public access roads, turbine foundation, erection, trenching, and underground cable installation. Construction equipment may include, but would not be limited to scrapers, dozers, dump trucks, watering trucks, graders, compactors, loaders, excavators, forklifts, and cranes. Noise levels for individual equipment range from 55 to 89 dBA at 50 feet, as indicated in Table 3.10-12.

Table 3.10-12 Noise Emission Levels from Construction Equipment Equipment Type Typical Noise Level (Lmax) @ 50 feet Dump Truck 76 Concrete Mixer 85 Concrete Saw 82 Crane 85 Dozer 85 Grader 85 Excavator 85 Front End Loader 80 Lift 75 Paver 89 Roller 85 Scraper 89 Pickup Trucks 55 Notes: Lmax = maximum noise level Assumes all equipment is fitted with a properly maintained and operational noise control device, per manufacturer specifications. Noise levels listed are manufacturer-specified noise levels for each piece of heavy construction equipment. Source: FTA 2018

The most noise intensive phase of construction would likely be during road construction and installation of underground cable because of the proximity of these activities to two receptors (LT-1 and LT-2). Daytime construction-noise evaluation assumed that four of

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the highest noise-generating pieces of equipment could operate simultaneously in close proximity to each other and nearest location to receptors of the project construction activity. Based on the reference noise levels listed in Table 3.10-12 and accounting for typical usage factors of individual pieces of equipment, on-site construction-related activities could generate a combined hourly average noise level of approximately 86 dBA Leq and a maximum noise level as high as 91 Lmax at 50 feet from project areas.

Noise-sensitive receptors that could be adversely affected by construction noise are shown in Table 3.10-13. See Exhibit 3.10-1 for locations of all nearby sensitive land uses. The distance to and daytime noise exposure levels at each receptor location were estimated for the closest possible construction activities and are summarized in Table 3.10-13.

Table 3.10-13 Levels of Noise Exposure at Noise-Sensitive Receptors during Typical Daytime Construction Activity Daytime Construction Noise Exposure Level 2 at Sensitive Receptor Leq (dBA) Sensitive 1 Highest Leq Receptor Turbine Tower Underground (Exterior/Interior Road Work Foundation Erection Cabling [dBA])3 LT-1 30 55 35 35 32 LT-2 41 66 38 38 63 LT-3 22 47 47 47 44 Hastings Abode 26 51 50 50 47 Notes: dBA = A-weighted decibels; Leq = equivalent or energy-averaged sound level; LT = long-term noise measurement 1 See Exhibit 3.10-1 for locations of sensitive land uses relative to the project site. 2 Assumes all equipment is fitted with a properly maintained and operational noise control device, per manufacturer specifications. Noise levels listed are manufacture-specified noise levels for each piece of heavy construction equipment. 3 Assumes windows closed with an exterior to interior noise reduction of 25 dBA. Source: Data modeled by AECOM in 2019.

As shown in Table 3.10-13, daytime construction-generated exterior noise levels could exceed 66 dBA and 63 dBA Leq at the nearest sensitive receptor (LT-2) during road construction and underground cabling, respectively. All other receptors would not be exposed to project construction noise levels greater than 55 dBA Leq. Table 3.10-13 also shows that interior noise levels due to project construction would not exceed 45 dBA at noise sensitive receptors.

There would be some nighttime construction related noise generated by the project. These nighttime activities do not involve intensive sustained noise levels due to project construction equipment. Nighttime activities would include the relocation of project cranes to WTG sites and transport of oversized project components. These would be very short- term events and noise sources would include, but not be limited to, engine noise, track interaction with road surfaces, and support vehicle noise. This project activity would not

Page 3.10-22 Solano 4 Wind Project EIR July 2019 result in an impact due to the large distances from receptors to relative access roads that would be used for crane mobilization.

Construction Traffic

Over the entire construction period, approximately 8,025 heavy truck trips would be needed for delivery of the turbine parts and related material to the project site. Dump trucks, concrete trucks, water trucks, cranes, and other construction and trade vehicles would also travel to the site. Construction worker trips would generate a total of 7,500 trips over the construction period. In total, the project would generate 15,525 trips over the course of construction with a peak construction traffic volume of approximately 250 trips per day. This would result in 25 to 30 trips per hour.

Although the large trucks carrying turbine parts would be required to travel via specific routes (as described above), other construction traffic would travel to the project site via the most efficient paths. In general, construction traffic would travel to the generation area using State Route (SR) 12 and SR 113. Local access to the project site would be via Shiloh Road, Collinsville Road, Birds Landing Road, and Montezuma Hills Road.

Generally, a doubling of a noise source (such as twice as much traffic) is required to result in an increase of 3 dB, which is perceived as barely noticeable by people (Caltrans 2013a). Existing traffic volumes along the routes used by project-related construction traffic are more than 25–30 trips per hour (peak project-related trips). Therefore, project- related construction traffic would not double the existing traffic along the affected roadways and would not result in significant traffic noise increase. This impact would be less than significant.

Turbine Activity

Operation of wind turbines generates aerodynamic and mechanical noise. Aerodynamic noise is generated by the moving blades passing through the air, which may produce a buzzing, whooshing, pulsing, or sizzling sound, depending on the type of wind turbine and operating speed. Most of the noise generated during operation radiates perpendicular to the rotation of the blades; however, because the turbines rotate to face the wind, the noise may be radiated in various directions. Two or more operating turbines may combine to create an oscillating or thumping effect. Mechanical noise may be generated by the turbine’s gears, which can produce noticeable and irritating noise, depending on the degree of turbine insulation (Alberts 2006).

The effects of wind turbine noise on nearby receptors can be related to wind speed; high wind speeds generate noise that can mask turbine noise. Public perception of the acoustic impact of wind turbines is, in part, a subjective determination. Typically, the effects of noise from turbines on nearby receptors include subjective effects, including annoyance, nuisance, and dissatisfaction, along with interference with speech, sleep, and learning. (UMass 2006)

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The proposed project would replace existing turbines with new and technologically improved WTGs and introduce up to 22 new WTGs between the Solano East and Solano West project subareas. Wind turbine noise levels are based on the reference noise level measurements conducted in the field, as shown in Table 3.10-11. Measured noise levels from existing wind turbine operation ranged from 49 dBA to 54 dBA, depending on the orientation of the noise meter and the noise producing rotor hub. Conservatively assuming the highest measured WTG noise level in the field (54 dBA Leq) and an attenuation rate of -3 dBA per doubling of distance, Table 3.10-14 shows the resulting combined noise level at each receptor accounting for the various distances to the nearest cluster of wind turbines.

Table 3.10-14 Combined Wind Turbine Noise at Sensitive Receptors LT-1 LT-2 LT-3 Adobe House Distance Leq Distance Leq Distance Leq Distance Leq 3,900 38.1 1,300 42.9 1,400 42.5 1,000 44.0 4,100 37.9 1,500 42.2 2,000 41.0 3,400 38.7 4,200 37.8 1,700 41.7 4,000 38.0 1,850 41.3 4,700 37.3 2,100 40.8 3,300 38.8 3,300 38.8 Combined Combined Combined Combined 41 45 45 45 Noise Level Noise Level Noise Level Noise Level Notes: Leq = equivalent or energy-averaged sound level; LT = long-term measurement Source: Data compiled by AECOM in 2019

As shown in Table 3.10-14, combined noise levels of new and upgraded WTGs at the relative nearest receptor would result in cumulative noise levels of up to 45 dBA Leq. Interior noise levels at sensitive receptor locations would be less than 30 dBA due to the operation of proposed new and upgraded turbines. The combined noise levels represent the most conservative approach to determining project operational noise impacts at sensitive receptors in the project area. The resulting combined noise levels indicate project operation would not expose people to a substantial increase in noise levels. This impact would be less than significant.

Overall Conclusion

Construction of project roads and underground cabling would take place over a relatively short time (4 months and 3 months, respectively), for a total of 7 months; and construction would move in a linear motion from one section of the road or underground cabling to another as installations are completed, further minimizing the timeframe during which substantial noise would be generated near any one sensitive receptor. Moreover, noise generated by construction activity would be limited to daytime hours between 7 a.m. and 6 p.m., Monday through Friday, and between 8 a.m. and 5 p.m. on Saturday. As described in Section 2.5.10, “Construction Methods and Schedule,” construction would primarily take place during the day, with only crane mobilization and transportation of heavy components occurring during the nighttime hours. Operation of the project wind turbines

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would not exposed to receptors to noise levels above 45 dBA at exterior or interior uses. This impact would be less than significant.

Mitigation Measures No mitigation is required.

Impact 3.10-2: Temporary and Short-Term Exposure of Sensitive Receptors to, or Temporary and Short-Term Generation of, Excessive Groundborne Vibration. Construction activities, including but not limited to the use of large dozers, would not expose existing nearby sensitive residential or historical receptors and structures to levels of ground vibration that could result in structural damage and/or disturbance to people occupying nearby buildings because of the project’s distance from the closest sensitive receptor (275 feet). This impact would be less than significant.

As shown in Table 3.10-15, below, construction activities generate varying degrees of ground vibration, depending on the specific construction equipment used and activities involved. Ground vibration generated by construction equipment spreads through the ground and diminishes in magnitude with increases in distance. Construction-related ground vibration is normally associated with impact equipment such as pile drivers, jackhammers, and the operation of some heavy-duty construction equipment, such as dozers and trucks. Blasting activities also generate relatively high levels of ground vibration and vibration noise. The effects of ground vibration may be imperceptible at the lowest levels, result in low rumbling sounds and detectable vibrations at moderate levels, and high levels of vibration can cause sleep disturbance in places where people normally sleep or annoyance to people in buildings that are primarily used for daytime functions.

Table 3.10-15 Representative Ground Vibration and Noise Levels for Construction Equipment 1 2 Equipment PPV at 25 feet (in/sec) Approximate Lv (VdB) at 25 feet Large Bulldozer 0.089 87 Caisson Drilling 0.089 87 Loaded Trucks 0.076 86 Rock Breaker 0.059 83 Jackhammer 0.035 79 Small Bulldozer 0.003 58

Notes: in/sec = inches per second; LV = the root mean square velocity expressed in vibration decibels (VdB), assuming a crest factor of 4; PPV = peak particle velocity. 1 Typical PPV and VdB shown. Source: FTA 2018

As shown in Table 3.10-15, the operation of large bulldozers are the typical construction activities that generate the greatest ground vibration. As described in Section 2.5.10, “Construction Methods and Schedule,” construction activity associated with decommissioning of outdated WTGs and new construction of access roads, underground

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cable lines, and WTGs would be conducted at both of the project subarea sites as part of installation of the WTGs.

According to FTA, large bulldozers typically generate vibration levels of 0.089 in/sec PPV and 87 VdB at 25 feet (FTA 2018). Construction activities would be located approximately 275 feet from the nearest existing sensitive residential receptor (LT-1) and 1,100 feet from the nearest existing sensitive historical structure (Hastings Abode). Based on FTA’s recommended procedure for applying a propagation adjustment to these reference levels, vibration levels from project construction was modeled at the nearest existing sensitive receptors. It was assumed that construction activity could take place nearest to vibration- sensitive receptors. Table 3.10-16 summarizes the levels of ground vibration that could occur at the surrounding sensitive receptors because of pile driving on the project site.

Table 3.10-16 Summary of Modeled Vibration Levels at Sensitive Receptors

Distance (feet) to PPV (in/sec) at Approximate LV (VdB) Sensitive Receptor Sensitive Receptor Sensitive Receptor1,2 at Sensitive Receptor3 LT-1 775 0.001 42 LT-2 275 0.002 56 LT-3 1,400 0.0002 35 Hastings Abode 1,100 0.0003 38 Notes: in/sec = inches per second; LT = long-term measurement; PPV = peak particle velocity; VdB = vibration decibels See Appendix H for detailed noise modeling input data and output results. 1 Caltrans’s recommended level of 0.2 in/sec PPV with respect to the structural damage used as the threshold for residential receptors. 2 Caltrans’s recommended level of 0.1 in/sec PPV with respect to the structural damage used as the threshold for nonresidential receptors. 3 FTA’s maximum acceptable level of 80 VdB with respect to human response used as the threshold. Source: Data modeled by AECOM in 2017

As shown in Table 3.10-16, for all nearby residential and historical (Hastings Abode) sensitive receptors, modeled vibration levels would not exceed Caltrans’s recommended standard of 0.08 in/sec PPV nor 0.2 in/sec PPV with respect to the prevention of structural damage for historical structures and residential dwellings or exceed FTA’s maximum acceptable level of 80 VdB with respect to human response.

Thus, the use of vibration inducing construction equipment during project construction activities at the project site would not result in the exposure of existing nearby sensitive receptors to excessive ground vibration and vibration noise levels. This impact would be less than significant.

Mitigation Measures No mitigation is required.

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