Introduction. Section 4.12 Noise. Acoustical Terminology

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1 Introduction Section 4.12 Noise This section describes the affected environment and regulatory setting of the proposed project and evaluates the potential for noise and groundborne vibration impacts to result from project implementation It also describes the need for mitigation measures where applicable. The information in this section is based on the Noise Assessment (JCBA, 2014), which is provided in Appendix M. Acoustical Terminology This section describes the physical characteristics of sound. An understanding of the physical characteristics of sound is useful for evaluating environmental noise from the proposed project. The methods and metrics used to quantify noise exposure, human response, and relative judgment of loudness are also discussed, and noise levels of common noise environments are presented. Noise is generally defined as loud, unpleasant, unexpected, or undesired sound that is typically associated with human activity and interferes with or disrupts normal activities. The effects of noise on people can be grouped into four general categories: Subjective effects (dissatisfaction, annoyance); Interference effects (communication and sleep interference, learning); Physiological effects (startle response); and Physical effects (hearing loss). Although exposure to high noise levels has been demonstrated to cause physical and physiological effects, the principal human responses to typical environmental noise exposure are related to subjective effects and interference with activities. The subjective responses of individuals to similar noise events are diverse and influenced by many factors, including the type of noise, the perceived importance of the noise, its appropriateness to the setting, the duration of the noise, the time of day and the type of activity during which the noise occurs, and individual noise sensitivity. Interference effects of environmental noise refer to those effects that interrupt daily activities and include interference with human communication activities, such as normal conversations, watching television, and telephone conversations, and interference with sleep. Sleep interference effects can include both awakening from sleep and arousal to a lesser state of sleep. Sound is a physical phenomenon consisting of minute vibrations that travel through a medium, such as air, and are sensed by the human ear. Sound is generally characterized by several variables, including frequency and amplitude. Frequency describes the sound s pitch (tone) and is measured in cycles per second (Hertz [Hz]), while amplitude describes the sound s pressure (loudness). Because the range of sound pressures that occurs in the environment is extremely large, it is convenient to express these pressures on a logarithmic scale that compresses the wide range of pressures into a more useful range of numbers. The standard unit of sound measurement is the decibel (db). Hz is a measure of how many

2 times each second the crest of a sound pressure wave passes a fixed point. For example, when a drummer beats a drum, the skin of the drum vibrates a given number of times per second. If the drum vibrates 100 times per second, it generates a sound pressure wave that is oscillating at 100 Hz, and this pressure oscillation is perceived by the ear/brain as a tonal pitch of 100 Hz. Sound frequencies between 20 and 20,000 Hz are within the range of sensitivity of the healthy human ear. Sound levels are expressed by reference to a specified national/international standard. The sound pressure level is used to describe sound pressure (loudness) and is specified at a given distance or specific receptor location. In expressing sound pressure level on a logarithmic scale, sound pressure (db) is referenced to a value of 20 micropascals (µpa). Sound pressure level depends not only on the power of the source but also on the distance from the source to the receiver and the acoustical characteristics of the sound propagation path (absorption, reflection, etc.). Outdoor sound levels decrease logarithmically as the distance from the source increases. This decrease is due to wave divergence, atmospheric absorption, and ground attenuation. Sound radiating from a source in a homogeneous and undisturbed manner travels in spherical waves. As the sound waves travel away from the source, the sound energy is dispersed over a greater area, decreasing the sound pressure of the wave. Spherical spreading of the sound wave from a point source reduces the noise level at a rate of 6 db per doubling of distance. Atmospheric absorption also influences the sound levels received by an observer. The greater the distance traveled, the greater the influence of the atmosphere and the resultant fluctuations. Atmospheric absorption becomes important at distances greater than 1,000 feet. The degree of absorption varies depending on the frequency of the sound as well as the humidity and temperature of the air. For example, atmospheric absorption is lowest (i.e., sound carries farther) at high humidity and high temperatures, and lower frequencies are less readily absorbed (i.e., sound carries farther) than higher frequencies. Over long distances, lower frequencies become dominant as the higher frequencies are more rapidly attenuated. Turbulence, gradients of wind, and other atmospheric phenomena also play a significant role in determining the degree of attenuation. For example, certain conditions, such as temperature inversions, can channel or focus the sound waves, resulting in higher noise levels than would result from simple spherical spreading. Sound from a tuning fork contains a single frequency (a pure tone), but most sounds in the environment do not consist of a single frequency. Instead, they are a broad band of many frequencies differing in sound level. Because of the broad range of audible frequencies, methods have been developed to quantify these values into a single number representative of human hearing. The most common method used to quantify environmental sounds consists of evaluating all frequencies of a sound according to a weighting system that is reflective of human hearing characteristics. Human hearing is less sensitive at low frequencies and extremely high frequencies than at the mid-range frequencies. This process is termed A weighting, and the resulting db level is termed the A-weighted decibel (dba). Because A-weighting is designed to emulate the frequency response characteristics of the human ear and reflect the way people perceive sounds, it is widely used in local noise ordinances and state and federal guidelines, including those of the State of California and Kern County. Unless specifically noted, the use of A-weighting is always assumed with respect to environmental sound and community noise, even if the notation does not include the A. In terms of human perception, a sound level of 0 dba is the threshold of human hearing and is barely audible by a healthy ear under extremely quiet listening conditions. This threshold is the reference level

3 against which the amplitude of other sounds is compared. Normal speech has a sound level of 60 dba. Sound levels above about 120 dba begin to be felt inside the human ear as discomfort, progressing to pain at still higher levels. Humans are much better at discerning relative sound levels than absolute sound levels. The minimum change in the sound level of individual events that an average human ear can detect is about 1 to 3 dba. A 3 to 5 dba change is readily perceived. An increase (or decrease) in sound level of about 10 dba is usually perceived by the average person as a doubling (or halving) of the sound s loudness. Because of the logarithmic nature of the decibel, sound levels cannot be added or subtracted directly. However, some simple rules are useful in dealing with sound levels. First, if a sound s acoustical energy is doubled, the sound level increases by 3 dba, regardless of the initial sound level (e.g., 60 dba + 60 dba = 63 dba; 80 dba + 80 dba = 83 dba). However, an increase of 10 dba is required to double the perceived loudness of a sound, and a doubling or halving of the acoustical energy (a 3 dba difference) is at the lower limit of readily perceived change. Although dba may adequately indicate the level of environmental noise at any instant in time, community noise levels vary continuously. Most ambient environmental noise includes a mixture of noise from nearby and distant sources that creates an ebb and flow of sound, including some identifiable sources plus a relatively steady background noise in which no particular source is identifiable. A single descriptor, termed the equivalent sound level (L eq ), is used to describe sound that is constant or changing in level. L eq is the energy-mean dba during a measured time interval. It is the equivalent sound level produced by a given constant source equal to the acoustic energy contained in the fluctuating sound level measured during the interval. In addition to the energy-average level, it is often desirable to know the acoustic range of the noise source being measured. This is accomplished through the maximum instantaneous (L max ) and minimum instantaneous (L min ) noise level indicators that represent the rootmean-square maximum and minimum noise levels measured during the monitoring interval. The L min value obtained for a particular monitoring location is often called the acoustic floor for that location. To describe the time-varying character of environmental noise, the statistical or percentile noise descriptors L 10, L 50, and L 90 may be used, which represent the noise levels equaled or exceeded during 10 percent, 50 percent, and 90 percent of the measured time interval, respectively. Sound levels associated with L 10 typically describe transient or short-term events, L 50 represents the median sound level during the measurement interval, and L 90 levels are typically used to describe background noise conditions. The Day-Night Average Sound Level (L dn, or DNL) represents the average sound level for a 24-hour day and is calculated by adding a 10 dba penalty to sound levels during the night period (10:00 p.m. to 7:00 a.m.). The L dn is the descriptor of choice and used by nearly all federal, State, and local agencies throughout the U.S. to define acceptable land use compatibility with respect to noise. Within California, the Community Noise Equivalent Level (CNEL) is sometimes used. CNEL is very similar to L dn, except that an additional 5 dba penalty is applied to the evening hours (7:00 p.m. to 10:00 p.m.). Because of the time-of-day penalties associated with the L dn and CNEL descriptors, the L dn or CNEL dba value for a continuously operating sound source during a 24-hour period will be numerically greater than the dba value of the 24-hour L eq. Thus, for a continuously operating noise source producing a constant noise level operating for periods of 24 hours or more, the L dn will be 6 dba higher than the 24-hour L eq value. For convenience, a summary of common noise metrics is provided in Table To provide a frame of reference, common sound levels are presented in Figure

4 Table : Common Noise Metrics Unit of Measure Description db Decibel Decibels, which are units for measuring the volume of sound, are measured on a logarithmic scale, representing points on a sharply rising curve. For example, 10 db sounds are 10 times more intense than 1 db sounds, and 20 db sounds are 100 times more intense. A 10 db increase in sound level is perceived by the human ear as a doubling of the loudness of the sound. dba A-Weighted Decibel A sound pressure level that has been weighted to quantitatively reduce the effect of high- and low-frequency noise. It was designed to approximate the response of the human ear to sound. L eq L max L min L 1, L 10, L 50, L 90 Equivalent Noise Level Maximum Noise Level Minimum Noise Level Percentile Noise Exceedance Levels The average acoustic energy content of noise for a stated period of time. The L eq of a time-varying signal and that of a steady signal are the same if they deliver the same acoustic energy over a given time. The L eq may also be referred to as the average sound level. L max represents the maximum instantaneous noise level experienced during a given period of time. It reflects peak operating conditions and addresses the annoying aspects of intermittent noise. L min represents the minimum instantaneous noise level experienced during a given period of time. It reflects baseline operating conditions and is commonly referenced as the noise floor. The A-weighted noise levels that are equaled or exceeded by a fluctuating sound level 1%, 10%, 50%, and 90% of a stated time period. L dn CNEL Day-Night Average Noise Community Noise Equivalent Level A metric representing the 24-hour average sound level that includes the addition of a 10 dba penalty to sound levels during the nighttime hours of 10 p.m. to 7 a.m. A metric representing the 24-hour average sound level that includes the addition of a 5 dba penalty to sound levels during evening hours (7 p.m. to 10 p.m.) and a 10 dba penalty to sound levels during nighttime hours (10 p.m. to 7 a.m.)

5 Figure Sound Levels and Human Response

6 Fundamentals of Vibration As described in the Federal Transit Administration s (FTA) Transit Noise and Vibration Impact Assessment (FTA, 2006), ground-borne vibration can be a serious concern for nearby neighbors of a transit system route or maintenance facility, causing buildings to shake and rumbling sounds to be heard. In contrast to airborne noise, ground-borne vibration is not a common environmental problem. It is unusual for vibration from sources such as buses and trucks to be perceptible, even in locations close to major roads. Some common sources of ground-borne vibration are trains, buses on rough roads, and construction activities such as blasting, pile-driving, and operation of heavy earth-moving equipment. There are several different methods that are used to quantify vibration. The peak particle velocity (PPV) is defined as the maximum instantaneous peak of the vibration signal. The PPV is most frequently used to describe vibration impacts to buildings. The root mean square (RMS) amplitude is most frequently used to describe the effect of vibration on the human body. The RMS amplitude is defined as the average of the squared amplitude of the signal. Decibel notation (VdB) is commonly used to measure RMS. The relationship of PPV to RMS velocity is expressed in terms of the crest factor, defined as the ratio of the PPV amplitude to the RMS amplitude. Peak particle velocity is typically a factor of 1.7 to 6 times greater than RMS vibration velocity (FTA, 2006). The decibel notation acts to compress the range of numbers required to describe vibration. Typically, ground-borne vibration generated by man-made activities attenuates rapidly with distance from the source of the vibration. Sensitive receptors for vibration include structures (especially older masonry structures), people (especially residents, the elderly, and sick), and vibration sensitive equipment. The effects of ground-borne vibration include movement of the building floors, rattling of windows, shaking of items on shelves or hanging on walls, and rumbling sounds. In extreme cases, the vibration can cause damage to buildings. Building damage is not a factor for most projects, with the occasional exception of blasting and pile-driving during construction. Annoyance from vibration often occurs when the vibration levels exceed the threshold of perception by only a small margin. A vibration level that causes annoyance will be well below the damage threshold for normal buildings. The FTA measure of the threshold of architectural damage for conventional sensitive structures is 0.2 in/sec PPV (FTA, 2006). In residential areas, the background vibration velocity level is usually around 50 VdB (approximately in/sec PPV). This level is well below the vibration velocity level threshold of perception for humans, which is approximately 65 VdB. A vibration velocity level of 75 VdB is considered to be the approximate dividing line between barely perceptible and distinctly perceptible levels for many people (FTA, 2006). Sensitive Receptors Land uses deemed sensitive by the State of California include schools, hospitals, rest homes, and longterm care and mental care facilities, which are considered to be more sensitive to ambient noise levels than others. Many jurisdictions also consider residential uses particularly noise-sensitive because families and individuals expect to use time in the home for rest and relaxation, and noise can interfere with those activities. Some jurisdictions may also identify other noise-sensitive uses such as churches, libraries, and parks. Furthermore, sensitive noise receptors may also include threatened or endangered biological species, although many jurisdictions have not adopted noise standards for wildlife areas. Land uses that

7 are generally not considered to be noise sensitive receptors include office, commercial, and retail developments Environmental Setting The project area consists of 1,350 acres of undeveloped but previously disturbed land (from uses such as agricultural and grazing) on two geographically separate sites. Located in the Fremont Valley, in southeastern unincorporated Kern County, the project area is situated just east of the southernmost portion of the Sierra Nevada, in the northwestern Mojave Desert. The southernmost boundary of the project area is approximately 8 miles north of California City, 15 miles north of Edwards Air Force Base, and 17 miles northeast of the unincorporated town of Mojave. The project area is generally flat with an elevation of approximately 2,000 feet above sea level. SR 14 is generally located to the west of the project sites, but also traverses through the westernmost portions of the project area. An existing Union Pacific rail line runs through the project area. Specifically, the existing rail line runs through Sons Ranch Sites 1 and 2. The existing noise environment in the project is defined primarily by the local roadway network, railroad activity, aircraft overflights, and agricultural activities. Existing Acoustical Environment To quantify the existing ambient noise environment in the project vicinity where noise-sensitive receptors are located, three continuous 24-hour noise level measurements and six short-term (10-minute) noise level measurements were conducted on and near the project sites by J.C. Brennan & Associates, Inc. on May 10, The noise monitoring locations were chosen to be representative of noise-sensitive receptors located in the vicinity of the proposed project or project-related construction activities, to the degree feasible. For determination of the L dn noise level, the use of a continuous (24-hour) sound monitor is preferred. However, as 24-hour measurements are not practical at all locations, short-term noise measurements during the daytime and nighttime hours were used to supplement the continuous noise monitoring data. The noise measurements were conducted using Larson Davis Laboratories (LDL) Model 820 and 824 precision integrating sound level meters, which were calibrated before and after use with an LDL Model CAL200 acoustical calibrator to ensure the accuracy of the measurements. The equipment used meets all pertinent specifications of the American National Standards Institute for Type 1 sound level meters (ANSI S1.4). The noise measurement locations for the project are shown in Figure A and the noise level measurement results are shown in Table Noise sensitive land uses located in the vicinity of the proposed project consist primarily of rural, single-family residential uses that are sparsely located around the two geographically separate project sites. The approximate location of the existing sensitive receptors in the vicinity of the project sites are shown in Figures B through D. Similar sensitive receptors are also located along the electrical transmission routes associated with the project. These sensitive receptors are located 100 feet or further from these project-related off-site facilities

8 Table : Summary of Existing Background Noise Measurement Data Average a Measured Hourly Noise Levels, dba Daytime (7 a.m. 7 p.m.) Nighttime (10 p.m. 7 a.m.) Location Date L dn L eq L 50 L max L eq L 50 L max Continuous 24 hour noise level measurements LT-1 5/10/ LT-2 5/10/ LT-3 5/10/ Short-term noise level measurements ST-1 Day: 5/ :45 a.m. Night: 5/9/12 10:33 p.m. 57 b ST-2 Day: 5/10/12 11:57 a.m. Night: 5/9/12 10:40 p.m. 51 b ST-3 Day: 5/10/12 12:13 p.m. Night: 5/9/12 10:52 p.m. 60 b ST-4 c Day: 5/10/12 12:41 p.m. Night: 5/9/12 11:07 p.m. 62 b Note: LT = Long Term (24-hour) Noise Monitoring Site ST = Short Term (10-minute) Noise Monitoring Site a Average values reported are the average of the hourly measured values over the daytime and nighttime periods. b L dn noise level at short-term monitoring locations is estimated based on the daytime and nighttime noise monitoring samples. c This location was chosen to represent noise receptors location along Phillips Road, a primary construction traffic route for the project. Source: JCBA, Based on the noise level data shown in Table , existing ambient noise at receptors in the project area generally do not exceed the County s 65 dba L dn exterior noise level standard for residential and other noise-sensitive uses. Existing identifiable noise sources in the study area include operations on the existing railroad line, traffic on the local roadway network, occasional aircraft overflights, and windgenerated noise

9 KERN COUNTY PLANNING AND COMMUNITY DEVELOPMENT DEPARTMENT FREMONT SOLAR (SPRINGBOK 2 SOLAR FARM) Note: Updated boundary since publication of the Noise Report. SOURCE: J.C. Brennan & Associates, Inc. Environmental Noise Assessment, 2012 Figure A: NOISE MONITORING LOCATIONS EIR 2015

10 KERN COUNTY PLANNING AND COMMUNITY DEVELOPMENT DEPARTMENT FREMONT SOLAR (SPRINGBOK 2 SOLAR FARM) Legend: LT Long Term (24-hr) Noise Monitoring Site ST Short Term Noise Monitoring Site Receptor Location SOURCE: J.C. Brennan & Associates, Inc. Environmental Noise Assessment, 2014 Figure B: NOISE MONITORING AND RECEPTOR LOCATIONS - HOMES RANCH SITE EIR 2015

11 KERN COUNTY PLANNING AND COMMUNITY DEVELOPMENT DEPARTMENT FREMONT SOLAR (SPRINGBOK 2 SOLAR FARM) Legend: LT Long Term (24-hr) Noise Monitoring Site ST Short Term Noise Monitoring Site Receptor Location Note: Updated boundary since publication of the Noise Report. SOURCE: J.C. Brennan & Associates, Inc. Environmental Noise Assessment, 2014 Figure C: NOISE MONITORING AND RECEPTOR LOCATIONS - SONS RANCH SITES 1 AND 2 EIR 2015

12 KERN COUNTY PLANNING AND COMMUNITY DEVELOPMENT DEPARTMENT FREMONT SOLAR (SPRINGBOK 2 SOLAR FARM) Legend: LT Long Term (24-hr) Noise Monitoring Site ST Short Term Noise Monitoring Site Receptor Location SOURCE: J.C. Brennan & Associates, Inc. Environmental Noise Assessment, 2014 EIR Figure D: NOISE MONITORING AND RECEPTOR LOCATIONS PHILLIPS ROAD RESIDENTIAL AREA 2015

13 Existing Roadway Noise Levels Existing roadway noise levels were calculated at select roadway segments located in proximity of the project sites. Calculation of the existing roadway noise levels was accomplished using the Federal Highway Administration Highway Noise Prediction Model (FHWA-RD ) and traffic volumes at the study intersections analyzed in the proposed project s traffic study. The model calculates the average noise level at specific locations based on vehicle volumes, average speeds, roadway configurations, distance to the receiver, and site acoustical characteristics. Traffic noise levels were predicted at the sensitive receptors located at the closest typical setback distance along each project-area roadway segment. The modeled traffic noise levels at the nearest sensitive receptors along the roadway segments in the project area are presented in Table Table : Existing Roadway Noise Levels and Distances to Contours Distance to Contours (feet) Roadway Segment Exterior Noise Level, L dn 70 dba 65 dba 60 dba SR 14 SR 58 to Phillips Road SR 14 Phillips Road to Redrock Randsburg Road Phillips Road SR 14 to Neuralia Road Neuralia Road SR 14 to Munsey Road Neuralia Road Munsey Road to Phillips Road Notes: Distances to traffic noise contours are measured in feet from the centerlines of the roadways. Source: JCBA, Regulatory Setting Federal Noise Control Act of 1972 (42 USC 4910) This act establishes a national policy to promote an environment for all Americans to be free from noise that jeopardizes their health and welfare. To accomplish this, the act establishes a means for the coordination of federal research and activities in noise control, authorizes the establishment of federal noise emissions standards for products distributed in commerce, and provides information to the public with respect to the noise-emission and noise-reduction characteristics of such products. USEPA Recommendations in Information on Levels of Environmental Noise Requisite to Protect Health and Welfare with an Adequate Margin of Safety (NTIS 550\ , USEPA, Washington, D.C., March 1974) In response to the Federal Control Act of 1972, the United States Environmental Protection Agency (USEPA) provided this document that identifies noise levels requisite to protect public health and welfare

14 against hearing loss, annoyance and activity interference. These noise levels are shown in Table One of the purposes of this document is to provide a basis for state and local governments' judgments in setting standards. In doing so, the information presented by USEPA must be utilized along with other relevant factors. These factors include the balance between costs and benefits associated with setting standards at particular noise levels, the nature of the existing or projected noise problems in any particular area, and the local aspirations and the means available to control environmental noise. As shown in Table , a 24-hour exposure level of 70 db is identified as the level of environmental noise which would prevent any measurable hearing loss over a lifetime. Likewise, levels of 55 db outdoors and 45 db indoors are identified as preventing activity interference and annoyance. These levels of noise are considered those which will permit spoken conversation and other activities such as sleeping, working and recreation, which are part of the daily human condition. The levels are not single event or peak levels. Instead, they represent averages of acoustic energy over periods of time such as 8 or 24 hours and over even longer periods (e.g., years). Table : Summary of noise levels identified as requisite to protect the public health and welfare with an Adequate Margin of Safety Effect Level db Activity Area Hearing Loss 70 L eq (24-hour) All areas. Outdoor activity interference and annoyance Indoor activity Interference and Annoyance 55 L dn Outdoors in residential areas and farms and other outdoor areas where people spend widely varying amounts of time and other places in which quiet is a basis for use. 55 L eq (24-hour) Outdoor areas where people spend limited amounts of time (e.g., school yards, playgrounds) 45 L dn Indoor residential areas. 45 L eq (24-hour) Other indoor areas with human activities (e.g., school yards playgrounds). Note: L eq (24-hour) = Equivalent A-weighted sound level over 24 hours. L dn = 24-hour A-weighted equivalent sound level, with a 10 decibel penalty applied to nighttime levels. Source: USEPA, Federal Energy Regulatory Commission Guidelines on Noise Emissions from Compressor Stations, Substations, and Transmission Lines (18 CFR [d]5) These guidelines require that the noise attributable to any new compressor stations, compression added to an existing station, or any modification, upgrade, or update of an existing station must not exceed a L dn of 55 dba at any pre-existing noise-sensitive area (such as schools, hospitals, or residences). This policy was adopted based on the USEPA-identified level of significance of 55 L dn dba. Federal Highway Administration Noise Abatement Procedures (23 CFR Part 772) The purpose of 23 CFR Part 772 is to provide procedures for noise studies and noise abatement measures to help protect the public health and welfare, supply noise abatement criteria, and establish requirements for information to be given to local officials for use in the planning and design of highways. The Federal Highway Administration (FHWA) has established two types of criteria for evaluating noise impacts associated with highway projects: one related to land use type and the other to existing noise levels. The first type of noise assessment criteria (NAC) is shown in Table The FHWA requires

15 that primary consideration be given to exterior areas (Activity Categories A, B, and C). The interior NAC is used only where either there are no affected exterior activities or where exterior activities are not impacted because of sufficient distance or shielding from the roadway. The second type of NAC is a substantial increase in noise levels ranging from 5-15 db(a) in the design year, over existing noise levels. Table : Noise Abatement Criteria Activity Category NAC, Hourly A-Weighted Noise Level (dba-l eq [h]) Description of Activities A 57 (exterior) Lands on which serenity and quiet are of extraordinary significance and serve an important public need and where the preservation of those qualities is essential if the area is to continue to serve its intended purpose. B 67 (exterior) Picnic areas, recreation areas, playgrounds, active sport areas, parks, residences, motels, hotels, schools, churches, libraries, and hospitals. C 72 (exterior) Developed lands, properties, or activities not included in categories A or B above. D Undeveloped lands. E 52 (interior) Residences, motels, hotels, public meeting rooms, schools, churches, libraries, hospitals, and auditoriums. NAC = noise assessment criteria L eq (h) = hourly L eq Source: FTA, The FTA has also established a method for the assessing construction source noise levels. Unless local noise ordinances can be found to apply, this method can be used to develop criteria on a project-specific basis. For major construction projects where a known noise-sensitive receptor (e.g., residential land use) is next to the sites, the use of the levels in Table is recommended by the FTA. Table : Recommended Noise Levels for Major Construction Projects with Adjacent Noise- Sensitive Receptors L eq (8-Hour) dba Land Use Day Night L dn (30-Day Average) dba Residential Source: FTA, Occupational Safety and Health Administration Occupational Noise Exposure; Hearing Conservation Amendment (Federal Register 48 [46], , 1983) The standard stipulates that protection against the effects of noise exposure shall be provided for employees when sound levels exceed 90 dba over an 8-hour exposure period. Protection shall consist of feasible administrative or engineering controls. If such controls fail to reduce sound levels to within acceptable levels, personal protective equipment shall be provided and used to reduce exposure of the employee. Additionally, a Hearing Conservation Program must be instituted by the employers whenever employee noise exposure equals or exceeds the action level of an 8-hour time-weighted average sound level of 85 dba. The Hearing Conservation Program requirements consist of periodic area and personal

16 noise monitoring, performance and evaluation of audiograms, provision of hearing protection, annual employee training, and record keeping. FTA Vibration Criteria To address the human response to groundborne vibration, FTA has also set forth guidelines for maximum-acceptable vibration criteria for different types of land uses. These include 65 VdB referenced to 1 micro inch per second (µin/sec) and based on the RMS velocity amplitude for land uses where low ambient vibration is essential for interior operations (e.g., hospitals, high-tech manufacturing, laboratory facilities); VdB for residential uses and buildings where people normally sleep; and VdB for instructional land uses with primarily daytime operations (e.g., schools, churches, clinics, offices; FTA 2006). The low end of the vibration scale is intended for frequent vibration events occurring more than 70 times per day. The high end of the scale is intended for infrequent vibration events occurring less than 30 times per day. Standards have also been established to address the potential for groundborne vibration to cause structural damage to buildings. These standards are shown in Table Table : Construction Vibration Damage Criteria Building Category PPV (in/sec) a Approximate L v I. Reinforced-concrete, steel, or timber (no plaster) II. Engineered concrete and masonry (no plaster) III. Non-engineered timber and masonry buildings IV. Buildings extremely susceptible to vibration damage a RMS velocity in decibels (VdB) re 1 micro-inch/second. Source: FTA, State Noise In California, most cities and counties have adopted noise ordinances which serve as enforcement mechanisms for controlling noise, and general plan noise elements, which are used as planning guidelines to ensure that long-term noise generated by a source is compatible with adjacent land uses. The California Department of Health Services Office of Noise Control studied the correlation of noise levels and their effects on various land uses and published land use compatibility guidelines for the noise elements of local general plans. The guidelines are the basis for most noise element land use compatibility guidelines in California. The land use compatibility for community noise environment chart identifies the normally acceptable range for several different land uses, as shown in Figure Persons in low-density residential settings are most sensitive to noise intrusion, with noise levels of 60 dba CNEL and below considered acceptable. For land uses such as schools, libraries, churches, hospitals, and parks, acceptable noise levels go up to 70 dba CNEL. The State of California also establishes noise limits for vehicles licensed to operate on public roads. For heavy trucks, the state pass-by standard is consistent with the federal limit of 80 dba at 15 meters. The state pass-by standard for light trucks and passenger cars (less than 4.5 tons, gross vehicle rating) is also 80 dba at

17 15 meters from the centerline. These standards are implemented through controls on vehicle manufacturers and by legal sanction of vehicle operators by state and local law enforcement officials. The state has also established noise insulation standards for new multi-family residential units, hotels, and motels that would be subject to relatively high levels of transportation-related noise. These requirements are collectively known as the California Noise Insulation Standards (Title 24, California Code of Regulations). The noise insulation standards set forth an interior standard of 45 dba CNEL or L dn in any habitable room. They require an acoustical analysis demonstrating how dwelling units have been designed to meet this interior standard where such units are proposed in areas subject to noise levels greater than 60 dba CNEL or L dn. Title 24 standards are typically enforced by local jurisdictions through the building permit application process. Occupational exposure to noise is regulated by California Division of Occupational Safety and Health in Title 8, Group 15, Article 105, Sections The standard stipulates that protection against the effects of noise exposure shall be provided when sound levels exceed 90 dba over an 8-hour exposure period. Protection shall consist of feasible administrative or engineering controls. If such controls fail to reduce sound levels to within acceptable levels, personal protective equipment shall be provided and used to reduce exposure of the employee. Additionally, a Hearing Conservation Program must be instituted by the employers whenever employee noise exposure equals or exceeds the action level of an 8-hour time-weighted average sound level of 85 dba. The Hearing Conservation Program requirements consist of periodic area and personal noise monitoring, performance and evaluation of audiograms, provision of hearing protection, annual employee training, and record keeping

18 Figure : Land Use Compatibility for Community Noise Environment Community Noise Exposure - L dn or CNEL (dba) Land Use Category Residential Low Density Single Family, Duplex, Mobile Home Residential Multi-Family Transient Lodging Motel/Hotel Schools, Libraries, Churches, Hospitals, Nursing Homes Auditorium, Concert Hall, Amphitheaters Sports Arena, Outdoor Spectator Sports Playgrounds, Neighborhood Parks Golf Courses, Riding Stables, Water Recreation, Cemeteries Office Buildings, Business, Commercial and Professional Industrial, Manufacturing, Utilities, Agriculture Normally Acceptable Conditionally Acceptable Normally Unacceptable Clearly Unacceptable Specified land use is satisfactory, based upon the assumption that any buildings involved are of normal conventional construction, without any special noise insulation requirements. New construction or development should be undertaken only after a detailed analysis of the noise reduction requirements is made and needed noise insulation features are included in the design. Conventional construction, but with closed windows and fresh air supply systems or air conditioning will normally suffice. New construction or development should be discouraged. If new construction or development does proceed, a detailed analysis of the noise reduction requirement must be made and needed noise insulation features included in the design. New construction or development generally should not be undertaken. SOURCE: State of California, Governor s Office of Planning and Research, General Plan Guidelines

19 Vibration Human and structural response to different vibration levels is influenced by a number of factors, including ground type, distance between source and receptor, duration, and the number of perceived vibration events. The California Department of Transportation (Caltrans) has established criteria that define the vibration levels that would normally be required to result in damage to structures. These vibration levels are shown in Table , and are presented in terms of PPV in inches per second. Table indicates that the threshold for architectural damage to structures is 0.20 in/sec PPV and continuous vibrations of 0.10 in/sec PPV, or greater, would likely cause annoyance to sensitive receptors. Table : Effects of Various Vibration Levels on People and Buildings Vibration Level (Peak Particle Velocity) a mm/s in/sec Human Reaction Effect on Buildings Threshold of perception; possibility of intrusion. Vibrations unlikely to cause damage of any type Vibrations readily perceptible. Recommended upper level of the vibration to which ruins and ancient monuments should be subjected Level at which continuous vibrations begin to annoy people Vibrations annoying to people in buildings (this agrees with the levels established for people standing on bridges and subjected to relative short periods of vibrations). Virtually no risk of architectural damage to normal buildings. Threshold at which there is a risk of architectural damage to normal dwelling - houses with plastered walls and ceilings. Special types of finish such as lining of walls, flexible ceiling treatment, etc., would minimize architectural damage Vibrations considered unpleasant by people subjected to continuous Vibrations at a greater level than normally expected from traffic, but vibrations and unacceptable to some would cause architectural damage people walking on bridges. and possibly minor structural damage. Note: mm/s = millimeters per second in/sec = inches per second a The vibration levels are based on peak particle velocity in the vertical direction. Where human reactions are concerned, the value is at the point at which the person is situated. For buildings, the value refers to the ground motion. No allowance is included for the amplifying effect, if any, of structural components. Source: Caltrans,

20 Local The majority of noise-sensitive receptors potentially affected by the proposed project are located within unincorporated areas of Kern County. However, the proposed project would also include construction of electrical transmission lines. Most jurisdictions have unique standards and guidelines regarding noise and nuisance. These are set out in county and municipal codes and general plans. Each noise ordinance or noise element within a municipal/county code will address noise levels that create a nuisance to surrounding communities. Noise ordinances and noise elements occasionally classify different areas within these communities based on zoning standards. Such zones can include residential areas (analyzed further based on the density of the population), industrial areas, commercial areas, agricultural areas, and rural areas. The possible adverse effects of construction noise are included within the noise standards. Ambient noise level, type of noise source, distance to the noise source, time of day, duration of the noise, and zoning of the areas are variables considered when assessing the adverse effects of noise on noisesensitive receptors. Virtually all municipal/county codes categorize noise by dba. Many standards will use a continuous L eq, CNEL, or L dn in order to express the sound levels over a given timeframe. Kern County General Plan Chapter 3: Noise Element The Noise Element of the General Plan is a mandatory element as required by California Government Code Section (f). The state requires that local jurisdictions prepare statements of policy indicating their intentions regarding noise and noise sources, establish desired maximum noise levels according to land use categories, set standards for noise emission from transportation and fixed-point sources, and prepare implementation measures to control noise. Noise Elements are prepared in accordance with Guidelines for the Preparation and Content of Noise Elements of the General Plan, published by the California Office of Noise Control in The Kern County Noise Element (Chapter 3 of the Kern County General Plan) provides a blueprint that contains goals and policies that guide the physical development of the unincorporated areas under the county s discretionary land use authority. The general plan also influences the development of incorporated cities and State and federal lands within the county that bear relation to the county s planning. The Kern County General Plan Noise Element was updated in June The Noise Element identifies goals, policies, and implementation measures that are used to guide development with regard to noise. The Kern County General Plan Noise Element identifies both residential and park/recreational areas as noise sensitive. In noise sensitive areas, the noise generated by new projects is to be mitigated to 65 db L dn or less in outdoor activity areas and 45 db L dn or less within interior living spaces. The following general plan goals and policies are applicable to the proposed project: Goals Goal 1: Ensure that residents of Kern County are protected from excessive noise and that moderate levels of noise are maintained

21 Goal 2: Policies Protect the economic base of Kern County by preventing the encroachment of incompatible land uses near known noise producing roadways, industries, railroads, airports, oil and gas extraction, and other sources. Policy 1: Policy 2: Policy 3: Policy 4: Policy 5: Policy 6: Policy 7: Implementation Measures Review discretionary industrial, commercial, or other noise-generating land use projects for compatibility with nearby noise-sensitive land uses. Require noise level criteria applied to all categories of land uses to be consistent with the recommendations of the California Division of Occupational Safety and Health (DOSH). Encourage vegetation and landscaping along roadways and adjacent to other noise sources in order to increase absorption of noise. Utilize good land use planning principles to reduce conflicts related to noise emissions. Prohibit new noise-sensitive land uses in noise-impacted areas unless effective mitigation measures are incorporated into the project design. Such mitigation shall be designed to reduce noise to the following levels: a) 65 db L dn or less in outdoor activity areas; b) 45 db L dn or less within interior living spaces or other noise sensitive interior spaces. Ensure that new development in the vicinity of airports will be compatible with existing and projected airport noise levels as set forth in the ALUCP. Employ the best available methods of noise control. Measure C: Measure F: Measure G: Review discretionary development plans, programs and proposals, including those initiated by both the public and private sectors, to ascertain and ensure their conformance to the policies outlined in this element. Require proposed commercial and industrial uses or operations to be designed or arranged so that they will not subject residential or other noise sensitive land uses to exterior noise levels in excess of 65 db L dn and interior noise levels in excess of 45 db L dn. At the time of any discretionary approval, such as a request for a General Plan Amendment, zone change or subdivision, the developer may be required to submit an acoustical report indicating the means by which the developer proposes to comply with the noise standards. The acoustical report shall: a) Be the responsibility of the applicant. b) Be prepared by a qualified acoustical consultant experienced in the fields of environmental noise assessment and architectural acoustics. c) Be subject to the review and approval of the Kern County Planning Department and the Environmental Health Services Department. All recommendations therein shall be complied with prior to final approval of the project. Measure H: Encourage cooperation between the County and the incorporated cities within the County to control noise

22 Measure I: Noise analyses shall include recommended mitigation, if required, and shall: a) Include representative noise level measurements with sufficient sampling periods and locations to adequately describe local conditions. b) Include estimated noise levels for existing and projected future (10 20 years hence) conditions, with a comparison made to the adopted policies of the Noise Element. c) Include recommendations for appropriate mitigation to achieve compliance with the adopted policies and standards of the Noise Element. d) Include estimates of noise exposure after the prescribed mitigation measures have been implemented. If compliance with the adopted standards and policies of the Noise Element will not be achieved, a rationale for acceptance of the project must be provided. Measure J: Develop implementation procedures to ensure that requirements imposed pursuant to the findings of an acoustical analysis are conducted as part of the project permitting process. Chapter 5: Energy Element The Kern County General Plan also requires the analysis of noise impacts relating to energy projects that might impact sensitive land uses. Policy Policy 10: The County should require acoustical analysis for energy project proposals that might impact sensitive and highly-sensitive uses in accordance with the Noise Element of the General Plan. Kern County Noise Ordinance Noise issues are also addressed in Chapter 8.36 of the Kern County Municipal Code. These include acceptable hours of construction and limitations on construction related noise impacts on adjacent sensitive receptors. Noise producing construction activities that are audible to a person with average hearing ability at a distance of 150 feet from the construction sites, or within 1,000 feet of an occupied residential dwelling are prohibited between the hours of 9:00 p.m. to 6:00 a.m. on weekdays, and 9:00 p.m. to 8:00 a.m. on weekends. However the following exceptions are permitted: 1) The resource management director or his designated representative may for good cause exempt some construction work for a limited time. 2) Emergency work is exempt from this section. Kern County currently does not have specific policies pertaining to vibration levels

23 Impacts and Mitigation Measures Methodology Potential sources of noise associated with the proposed project include: Pile driving during installation of solar panels; Solar operations; and, Construction traffic The noise levels generated during project construction from the various noise sources were calculated based on data from standard references, previous studies, and data from the equipment manufacturers. Projected construction noise levels from these sources were then estimated using a point-source attenuation model, which assumed that the noise from the source would attenuate at a rate of 6 dba for each doubling of distance. Noise levels generated from project-related traffic during construction were predicted using the FHWA-RD Model. The model was used in conjunction with the California vehicle noise (Calveno) reference noise emission curves, and accounted for vehicle volume and speed, roadway configuration, distance to the receiver, and the acoustical characteristics of the project sites. The FHWA Model was developed to predict hourly L eq values for free-flowing traffic conditions. To calculate L dn, average daily traffic (ADT) volume data was adjusted based on the assumed day/evening/night distribution of traffic on the project roadways. The traffic volumes for the project were obtained from the Traffic Study (McIntosh, 2014 located in Appendix N of this EIR, while the truck usage and vehicle speeds on the local area roadways were estimated from field observations and Caltrans data (where available) (McIntosh, 2014). To determine the potential noise impacts of the project on nearby noise-sensitive receptors, the estimated construction and operational noise levels for the project were compared to the Kern County General Plan 65 dba L dn exterior noise level standard for noise-sensitive uses. Thresholds of Significance The Kern County CEQA Implementation Document and Kern County Environmental Checklist identify the following criteria, as established in Appendix G of the CEQA Guidelines, to determine if a project could potentially have a significant adverse affect on noise. A project could have a have a significant adverse affect on noise if it: Exposure of persons to, or generate, noise levels in excess of standards established in a local general plan or noise ordinance or applicable standards of other agencies; Exposure of persons to or generated excessive ground-borne vibration or ground-borne noise levels; A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project; A substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project;