Section 4.12 Noise Introduction. Terminology. Noise

Transcription

1 Section 4.12 Noise

2 Introduction Section 4.12 Noise This section of the Environmental Impact Report (EIR) addresses the potential noise impacts associated with construction and operation of the proposed project, which includes both the North Sky River Wind Energy Project and the Jawbone Wind Energy Project. It describes the existing noise conditions on the proposed project site, the regulatory setting, the impacts of the proposed project, and feasible mitigation measures to reduce impacts. The information in this section is based on the February 2011 Draft Revised Noise Technical Report,, Kern County, California prepared by CH2MHILL and the Noise Memorandum ( M01) from Mr. William Meade of Sapphos Environmental Inc. dated November 30, 2010, which are included in Appendix J of this EIR. Terminology Noise The assessment of noise impacts uses specific terminology and fundamental descriptors not commonly used in everyday conversation. Therefore, in order to assist in a thorough understanding of the subsequent analysis, these terms are discussed in this subsection. Acoustics is the study of sound, and noise is defined as unwanted sound. Airborne sound is a rapid fluctuation or oscillation of air pressure above and below atmospheric pressure creating a sound wave. The pitch or loudness of sound determines whether a sound is of a pleasant or objectionable nature. Pitch, which is the height or depth of a tone or sound, is louder to humans when it is high pitched versus low pitched. The loudness of a sound is determined by a combination of the intensity of the sound waves with the reception characteristics of the ear. Measurement scales are used to describe sounds. A decibel (db) is a unit used to describe the amplitude of sound, and sound levels are calculated on a logarithmic, not linear, basis. The lowest sound level that an unimpaired human ear can hear is described as zero on the decibel scale. Due to the logarithmic nature of measuring sound levels on the decibel scale, a 10-dB increase represents a tenfold increase in acoustic energy; whereas, a 20-dB increase represents a hundredfold increase in acoustic energy. Because a relationship exists between acoustic energy and intensity, each 10-dB increase in sound level can have an approximate doubling effect on loudness as perceived by the human ear. Acoustical terms used in this subsection are summarized in Table The most common metric is the overall A-weighted sound level measurement (dba) that has been adopted by regulatory bodies worldwide. The A-weighting network measures sound in a fashion similar to the way a person perceives or hears sound, thus achieving very good correlation in terms of evaluating acceptable and unacceptable sound levels. and Jawbone Wind Energy Project May 2011

3 Table Definition of Acoustical Terms Term Definition Ambient Noise Level The composite noise from all sources resulting in the normal, existing level of environmental noise at a given location. The ambient level is typically defined by the Leq level. Background Noise Level The underlying ever-present lower level noise that remains in the absence of intrusive or intermittent sounds. Distant sources, such as traffic, typically makeup the background. The background level is generally defined by the L90 percentile noise level. Intrusive Noise that intrudes over and above the existing ambient noise at a given location. The relative intrusiveness of a sound depends upon its amplitude, duration, frequency, time of occurrence, tonal content, the prevailing ambient noise level, and the sensitivity of the receiver. The intrusive level is generally defined by the L10 percentile noise level. Decibel (db) A unit describing the amplitude of sound, equal to 20 times the logarithm to the base 10 of the ratio of the pressure of the sound measured to the reference pressure, which is 20 micropascals (20 micronewtons per square meter). A-Weighted Sound Level The sound level in decibels as measured on a sound level meter using the (dba) A-weighted filter network. The A-weighted filter de-emphasizes the very low and very high frequency components of the sound in a manner similar to the frequency response of the human ear and correlates well with subjective reactions to noise. All sound levels in this report are A-weighted. Equivalent Noise Level (Leq) The average A-weighted noise level, on an equal energy basis, during the measurement period. Percentile Noise Level (Ln) The noise level exceeded during n percent of the measurement period, where n is a number between 0 and 100 (e.g., L90) Day-Night Average Level The energy average A-weighted noise level during a 24-hour day, obtained after the (Ldn) Community Noise Equivalent Level (CNEL) Hertz (Hz) addition of 10 decibels between the hours of 10:00 p.m. and 7:00 a.m. Represents the average daytime noise level during a 24-hour day, adjusted to an equivalent level to account for people s lower tolerance of noise during the evening and nighttime hours. Because community receptors are considered to be more sensitive to unwanted noise intrusion during the evening and night, an artificial decibel increment is added to quiet-time noise levels. Sound levels are increased by 5 dba during the evening, from 7:00 p.m. to 10:00 p.m. and by 10 dba during the nighttime, from 10:00 p.m. to 7:00 a.m. A unit of frequency. The number of times per second that the sine wave of sound repeats itself, or that the sine wave of a vibrating object repeats itself. One way to describe noise is to measure the maximum sound level (L max ) (as represented by the 70 dba noise level from the sports car in the example shown in Table ). The L max measurement does not account for the duration of the sound. Studies have shown that human response to noise involves the maximum level and its duration. For example, the aircraft in this case is not as loud as the sports car, but the aircraft sound lasts longer. For most people, the aircraft overflight would be more annoying than the shorter duration sports car event. Thus, the maximum sound level alone is not sufficient to predict reaction to environmental noise. A-weighted sound levels can be measured or presented as equivalent sound pressure level (L eq ). This is defined as the average noise level, on an equal-energy basis for a stated period of time and is commonly used to measure steady-state sound or noise that is usually dominant. Statistical measurements are typically denoted by L n, where n represents the percentile of time the sound level is exceeded. The measurement of L 90 represents the noise level that is exceeded during 90 percent of the measurement period. Similarly, the L 10 represents the noise level exceeded for 10 percent of the measurement period. As discussed below in Section (Regulatory Setting), Kern County uses the L 8 metric in its Wind Energy Ordinance policy requirements. and Jawbone Wind Energy Project May 2011

4 Table Noise Metrics Comparative Noise Levels Human response to daytime and nighttime noise has been observed to vary. During the evening and nighttime, exterior background noises are generally lower than daytime levels. However, most household noise also decreases at night, and exterior noise becomes more noticeable. Furthermore, most people sleep at night and are sensitive to intrusive noises. To account for human sensitivity to evening and nighttime noise levels, the Day-Night Level (L dn ) was developed. The L dn is a noise index that accounts for the greater annoyance attributed to noise during the evening and nighttime hours. L dn values are calculated by averaging hourly L eq sound levels for a 24-hour period and applying weighting factors to evening and nighttime L eq values. The weighting factor, which reflects the increased sensitivity to noise during nighttime hours, is added to each hourly L eq sound level before the 24-hour L dn is calculated. For the purposes of assessing noise, the 24-hour day is divided into two time periods, with the following weightings: Daytime: 7:00 a.m. to 10:00 p.m. (15 hours), weighting factor of 0 db Nighttime: 10:00 p.m. to 7:00 a.m. (9 hours), weighting factor of 10 db The time periods are then averaged (on an energy basis) to compute the overall L dn value. For a continuous noise source, the L dn value can be computed by adding 6.4 db to the overall 24-hour noise level (L eq ). For example, if the expected continuous noise level from a power plant were 60.0 dba L eq for every hour, the resulting L dn from the plant would be 66.4 dba L dn. The community noise equivalent level (CNEL) metric is similar to the L dn but with an additional 5-dB weighting factor between 7:00 p.m. and 10:00 p.m. CNEL and L dn measures are frequently used interchangeably. For a continuous noise source, the CNEL value can be computed by adding 6.7 db to the overall 24-hour noise level (L eq ), meaning that the plant in the previous example would be 66.7 dba CNEL. The effects of noise on people can be grouped into three general categories: Subjective effects of annoyance, nuisance, dissatisfaction Interference with activities such as speech, sleep, learning Physiological effects such as startling and hearing loss In most cases, environmental noise produces effects in the first two categories of subjective effects and interference with activities only. However, workers in industrial plants might experience and Jawbone Wind Energy Project May 2011

5 physiological effects of noise. No satisfactory way exists to measure the subjective effects of noise, or to measure the corresponding reactions of annoyance and dissatisfaction. This lack of a common standard is due primarily to the wide variation in individual thresholds of annoyance and habituation to noise. Thus, an important way of determining a person s subjective reaction to a new noise is by comparison with the existing or ambient environment to which that person has adapted. In general, the more the level or the tonal (frequency) variations of a noise exceed the existing ambient noise level or tonal quality, the less acceptable the new noise will be, as judged by the exposed individual. When comparing sound levels from similar sources (for example, changes in traffic noise levels), a 3-dBA change is considered to be a just-perceivable difference; 5 dba is clearly perceivable, and 10 dba is considered a doubling in loudness. Vibration Vibration is defined as the mechanical motion of earth or ground, building, or other type of structure, induced by the operation of any mechanical device or equipment located upon or affixed thereto. Vibration generally results in an oscillatory motion in terms of the displacement, velocity, or acceleration of the ground- or structure(s) that causes a normal person to be aware of the vibration by means such as, but not limited to, sensation by touch or visual observation of moving objects. The effects of ground-borne vibration include movements of building floors, rattling of windows, and shaking of items on shelves or hangings on the walls. In extreme cases, vibration can cause damage to buildings. The noise radiated from the motion of the room surfaces is called groundborne noise. Typical levels of ground-borne vibration are listed in Table , below. The vibration motion normally does not provoke the same adverse human reactions as the noise unless there is an effect associated with the shaking of the building. In addition, the vibration noise can only occur inside buildings. Similar to the propagation of noise, vibration propagated from the source to the receptor depends on the receiving building (i.e., the weight of the building), soil conditions, layering of the soils, the depth of groundwater table, etc Typical Levels of Ground Borne Vibration Response Velocity Level a Typical Sources (At 50 feet) Minor cosmetic damage of fragile buildings 100 Blasting from construction projects Difficulty with tasks such as reading a video display Bulldozers and other heavy tracked 90 terminal (VDT) screen construction equipment Residential annoyance, infrequent events (e.g., 80 Rapid transit, upper range commuter rail) Residential annoyance, frequent events (e.g., rapid transit) 70 Approximate threshold for human perception of vibration; limit for vibration sensitive equipment 65 Bus or truck, typical None 50 Typical background vibration a. Root mean square (RMS) Vibration Velocity Level in VdB relative to 10-6 inches/second. Source: FTA, 2006 Figure 7-3. Rapid transit, typical; bus or truck over bump (slightly higher than 70 VdB) Environmental Setting Noise Sensitive Land Uses There are no known sensitive receptors within the project boundary (includes the North Sky River Wind Energy site and the Jawbone Wind Energy site). Sensitive receptors located within one mile of the project boundary include scattered residences and recreational users along the Pacific Crest and Jawbone Wind Energy Project May 2011

6 Trail (PCT), as shown on Figure The closest residences located within one mile of the proposed project boundary are located west of the project site. The closest residence (Location N-9 on Figure ) is located 3,215 feet from the nearest wind turbine generator (WTG), which is associated with the. The nearest residence to the Jawbone Wind Energy Project boundary is located two miles away. Residences located along the proposed Wilderness transmission reinforcement line route are shown on Figure The PCT is located 0.8 miles west of the southwest corner of the proposed project site (at its closest point to the project site) and runs generally parallel to the proposed gen-tie route, which crosses the PCT in several locations. The minimum distance between the proposed transmission reinforcement line and a residence would be 1,000 feet. Existing Environment Project Site The proposed project is located in southeastern Kern County at the base of the Tehachapi and Piute mountain ranges within the Sierra Nevada, directly west of the Fremont Valley in the Western Mojave Desert. As discussed in the Project Description authorized and unauthorized off-highway vehicle (OHV) use and livestock grazing occur in the project area. The Bureau of Land Management s (BLM) Jawbone OHV Open Area is located north of Jawbone Canyon Road. Existing development in the area includes rural access roads, producing and non-producing water wells, cattle ranching and maintenance facilities, and existing meteorological towers. The distance between the PCT and the project site boundary varies, ranging from 5.5 miles at the northwest corner of the project to 0.8 mile at the southwest corner of the project. The distance between the PCT and the nearest WTG within the project site would be approximately 1.7 miles. A few residences are located on private lands west of the project site, ranging from 3,215 feet from the closest proposed WTG to over 4.5 miles. Major transportation corridors in the region include State Route (SR) 14 (north south) and SR-58 (east west), which intersect about 20 miles south of the project area in the community of Mojave. Population centers within 20 miles of the project site include the city of Tehachapi (southwest) and the community of Mojave (south). Existing noise levels at the project site are expected to be typical of an agricultural or rural area, as the primary existing land use is cattle grazing. As noted in the Noise Technical Report (CH2MHILL 2011, see Appendix J), no significant noise sources have been identified other than the few roads that run through the project area, which are mostly unpaved roads with minimal traffic. Per the BLM s Final Programmatic Environmental Impact Statement on Wind Energy Development on BLM-Administered Lands in the Western United States (June 2005), for a typical rural environment, background noise is expected to be approximately 40 db(a) during the day and 30 db(a) at night or about 35 db(a) as DNL. Furthermore, according to information on noise levels presented by the United States Environmental Protection Agency (EPA), outdoor noise levels are generally near 35 dba L dn in wilderness areas; near 40 dba L dn in rural residential areas; and near 44 dba L dn in agricultural cropland (EPA, 1978 Figure 4). Based on these levels, existing background noise levels in the vicinity of the project area are estimated to be approximately dba. In addition, it should be noted that wind-induced noise may result in these levels being periodically exceeded. As part of the Noise Technical Report (see Appendix J) prepared for the project, a continuous ambient noise survey was conducted to further assist in determining the current level of noise in the and Jawbone Wind Energy Project May 2011

7 project area. The monitoring site was located west of the project boundary near the closest residences (see Figure ). A Larson Davis LD831 ANSI Type 1 statistical sound level meter was used to conduct the continuous measurement. The sound level meter was field calibrated before and after the measurement with a Larson Davis CAL200 and was factory calibrated within the previous 12 months. The LD831 meter was set to measure in 10-minute increments, which is the same time interval used for the meteorological measurements. This allowed a direct correlation of noise level with concurrent wind speed. Measurements were conducted from approximately 2:00 p.m. on November 19, 2010 through 9:20 a.m. on November 24, The measured L8.3 noise levels ranged from as low as approximately 20 dba with some periods measuring as high as 60 dba. The lower noise levels of dba generally occurred in the late evening hours and early morning hours with noise levels between dba during the mid-morning to early evening hours. Noise levels between dba occurred over short durations in the mid-morning and afternoon hours (see Appendix J, Figure 5-1). Wilderness Transmission Line Due to the minimal distance traversed by the Wilderness transmission reinforcement line, existing corona noise was not modeled Regulatory Setting Federal There are no federal regulations that apply to noise specifically from commercial WTG operation. State Local There are no State regulations that apply to noise specifically from commercial WTG operation; however, there are general State guidelines provided by the California Department of Health Services that define acceptable noise levels based on a land-use compatibility matrix (OPR, 2003, Appendix C, Figure 2). These guidelines may help to define a threshold for acceptable noise levels for residences in the project area. The California Department of Health Services has identified L dn or CNEL values of 60 dba or less as normally acceptable outdoor levels for residential use. Within the State of California, noise from WTG operations is typically regulated at the County level. For Kern County, the applicable documents are the Noise Element of the Kern County General Plan (KCGP), the Ordinance Code of Kern County, and Chapter 19.64, Wind Energy (WE) Combining District, of the Kern County Zoning Ordinance. and Jawbone Wind Energy Project May 2011

8 County of Kern Water Supply Parcel Figure Sensitive Receptor Locations Near the Proposed Project Site Source: CH2MHILL, and Jawbone Wind Energy Project May 2011

9 County of Kern Source: CH2MHILL, and Jawbone Wind Energy Project Figure Sensitive Receptor Locations Near the Proposed Regional Transmission Reinforcements May 2011

10 KCGP The KCGP Noise Element identifies goals, policies, and implementation measures that are used to guide development with regard to noise. The KCGP Noise Element identifies residential areas, schools, convalescence and acute care hospitals, parks and recreational areas, and churches as noise sensitive land uses. In noise sensitive areas, exterior noise levels generated by new projects are 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 or other noise sensitive interior spaces. The following General Plan goals, policies, and implementation measures are applicable to the proposed project: Chapter 3. Noise Element Goals Goal 1. Ensure that residents of Kern County are protected from excessive noise and that moderate levels of noise are maintained. Policies Policy 1. Review discretionary industrial, commercial, or other noise-generating land use projects for compatibility with nearby noise-sensitive land uses. Policy 2. 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) Policy 3. Encourage vegetation and landscaping along roadways and adjacent to other noise sources in order to increase absorption of noise. Policy 4. Utilize good land use planning principles to reduce conflicts related to noise emissions. Policy 5. 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 living spaces or other noise sensitive interior spaces. Policy 7. Employ the best available methods of noise control. Implementation Measures Implementation Measure A. Utilize zoning regulations to assist in achieving noisecompatible land use patterns. Implementation Measure C. 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. Implementation Measure F. 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. Implementation Measure G. 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: and Jawbone Wind Energy Project May 2011

11 (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. Implementation Measure H. Encourage cooperation between the County and the incorporated cities within the County to control noise. Implementation 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, in terms of CNEL, 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. Implementation 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. Kern County Health and Safety Ordinance (Title 8 of the Ordinance Code) Chapter 8.36, Noise Control (Section , Prohibited Sounds) of the Ordinance Code of Kern County prohibits construction noise between the hours of 9:00 p.m. and 6:00 a.m. on weekdays and 9:00 p.m. and 8:00 a.m. on weekends, which is audible to a person with average hearing faculties or capacity at a distance of 150 feet from the construction site, if the construction site is within 1,000 feet of an occupied residential dwelling except for emergency work or when the resource management director or his designated representative provides an exemption for a limited time. Kern County Zoning Ordinance (Title 19 of the Ordinance Code) Chapter WE Combining District. The WE Combining District (Chapter 19.64) contains development standards and conditions (Section ) that would be applicable to the siting and operation of WTGs. The following provisions apply to noise issues related to the proposed project. Section (J): Where a residence, school, church, public library, or other sensitive or highly sensitive land use, as identified in the Noise Element of the County General Plan, is located within one (1) mile in a prevailing downwind direction or within one-half (½) mile in any other direction of a project's exterior boundary, an acoustical analysis shall be prepared by a qualified acoustical consultant prior to the issuance of any building permit. The consultant and the resulting report shall be subject to review and approval by the Kern County Health Department. The report shall address and Jawbone Wind Energy Project May 2011

12 any potential impacts on sensitive or highly sensitive land uses. In addition, the acoustical report shall demonstrate that the proposed development shall comply with the following criteria: 1. Audible noise due to wind turbine operations shall not be created which causes the exterior noise level to exceed forty-five (45) dba for more than five (5) minutes out of any one- (1-) hour time period using the L8 metric or to exceed fifty (50) dba for any period of time when measured within fifty (50) feet of any existing residence, school, hospital, church, or public library. 2. Low frequency noise or infrasound from wind turbine operations shall not be created which causes the exterior noise level to exceed the following limits when measured within fifty (50) feet of any existing residence, school, hospital, church, or public library. One-third Octave Band Center Frequency (Hz) Sound Pressure Level (db) 2 to 1 70 (each band) In the event audible noise due to wind turbine operations contains a steady pure tone, such as a whine, screech, or hum, the standards for audible noise set forth in Subparagraph (1) of this subsection shall be reduced by five (5) dba. A pure tone is defined to exist if the one-third (1/3) octave band sound pressure level in the band, including the tone, exceeds the arithmetic average of the sound pressure levels of the two (2) contiguous one-third (1/3) octave bands by five (5) dba for center frequencies of five hundred (500) Hz and above, by eight (8) dba for center frequencies between one hundred and sixty (160) Hz and four hundred (400) Hz, or by fifteen (15) dba for center frequencies less than or equal to one hundred and twenty-five (125) Hz. 4. In the event the audible noise due to wind turbine operations contains repetitive impulsive sounds, the standards for audible noise set forth in Subparagraph (1) of this subsection shall be reduced by five (5) dba. 5. In the event the audible noise due to wind turbine operations contains both a pure tone and repetitive impulsive sounds, the standards for audible noise set forth in Subparagraph (1) of this subsection shall be reduced by a total of five (5) dba. 6. In the event the ambient noise level (exclusive of the development in question) exceeds one (1) of the standards given above, the applicable standard shall be adjusted so as to equal the ambient noise level. For audible noise, the ambient noise level shall be expressed in terms of the highest whole number sound pressure level in dba which is exceeded for no more than five (5) minutes per hour (L8). For low frequency noise or infrasound, the ambient noise level shall be expressed in terms of the equivalent level (Leq) for the one-third (1/3) octave band in question, rounded to the nearest whole decibel. Ambient noise levels shall be measured within fifty (50) feet of potentially affected existing residences, schools, hospitals, churches, or public libraries. Ambient noise level measurement techniques shall employ all practical and Jawbone Wind Energy Project May 2011

13 means of reducing the effects of wind-generated noise at the microphone. Ambient noise level measurements may be performed when wind velocities at the proposed project site are sufficient to allow wind turbine operation, provided that the wind velocity does not exceed thirty (30) miles per hour (mph) at the ambient noise measurement location. 7. Any noise level falling between two (2) whole decibels shall be the lower of the two (2). 8. In the event that noise levels, resulting from a proposed development, exceed the criteria listed above, a waiver to said levels may be granted by the Planning Director provided that the following has been accomplished: a. Written consent from the affected property owners has been obtained stating that they are aware of the proposed development and the noise limitations imposed by this code, and that consent is granted to allow noise levels to exceed the maximum limits allowed. b. A permanent noise impact easement has been recorded in the County Hall of Records which describes the benefited and burdened properties and which advises all subsequent owners of the burdened property that noise levels in excess of those permitted by this code may exist on or at the burdened property. Vibration Kern County does not include thresholds of significance for vibration levels. Per the Federal Transit Administration, engineered concrete and masonry buildings (no plaster) susceptible to vibration damage begin to experience structural damage at vibration levels of 0.3 inch per second Peak Particle Velocity (PPV) (FTA, 2006 Table 12-3) Impacts and Mitigation Measures Methodology CEQA requires determination of the significance of noise impacts associated with proposed projects. The process of assessing the significance of noise impacts associated with the project involves establishing thresholds at which significant impacts on noise-sensitive uses may occur. Noise levels associated with construction and operational activities related to the project, which includes both the and Jawbone Wind Energy Project, were predicted and compared to these significance thresholds. Construction noise levels to be generated by the proposed project would be typical of comparable large construction project. Noise levels would vary during the construction period depending on the construction phase and types of equipment in use. Construction noise levels were estimated based on the Federal Highway Administration (FHWA) Roadway Construction Noise Model (RCNM) estimates of noise levels for the operation of heavy equipment. The anticipated construction noise at the closest sensitive receptor was calculated based on the distance of the sensitive receptor from the potential construction areas. Predicted levels are conservative because the only attenuating mechanism considered was divergence of the sound waves in open air, which equates to a 6 db reduction per doubling of distance. This noise level at the closest sensitive receptor was then compared to the significance threshold. The operational noise level for the WTGs was calculated using the computer software noise model, CADNA/A by DataKustick GmbH of Munich, Germany, with sound propagation factors adopted from ISO Acoustics Sound Attenuation During Propagation Outdoors and VDI 2714 and Jawbone Wind Energy Project May 2011

14 Outdoor Sound Propagation. The model treated each WTG as a point source, where each WTG was assumed to emit noise at the hub height. As discussed in Section 3.2, the conceptual site plan for the project would include GE XLE (1.5 MW), GE XL (2.5 MW), GE XL (2.75 MW), Goldwind 2.5/90 (2.5 MW), Siemens SWT (2.3 MW) and Siemens SWT (2.3 MW) model WTGs. A noise model of the project was developed using available typical source input octave band sound power levels for a wind turbine generator with a rated power output of 2.5 MW. The project proposes to include 2.75 MW WTGs; however, specific input octave band sound power level data is not currently available for the turbines proposed. The sound power levels that were used are anticipated to represent the standard performance of the WTGs and were assigned based on data supplied by the manufacturer. Using these sound power levels as a basis, the model then calculated the sound pressure levels that would occur at each receptor from each WTG after consideration of losses from distance, air absorption, ground effects, and screening, as required under the noise criteria of the WE Combining District. In addition, the software calculated the low frequency noise from the WTGs based on typical one-third octave band WTG sound power levels relative to the limits established by the WE Combining District. The low frequency limits in the Kern County WE Combining District ordinance are expressed as limits on one-third octave band sound pressure levels for center frequencies of 1 Hz, 2 Hz, and 20 Hz through 125 Hz; however, narrow band sound data were not available for WTG noise in the 1 Hz, 2 Hz, and 20 Hz bands, so the low frequency analysis addressed only the 25 Hz through 125 Hz one-third octave bands. Where a noise level is predicted to exceed a threshold, the impact is considered significant and mitigation measures are proposed, as applicable. Audible corona noise levels for the 230-kV transmission line from the Tehachapi Substation to the Wilderness Substation, and the existing 230-kV single-circuit transmission line from the Sky River Substation through the Tehachapi Substation to the Wilderness Substation were estimated for both existing conditions and future conditions with implementation of the proposed project utilizing the EMF Workstation: ENVIRO (Version 3.52) modeling program. This modeling program requires inputs for the locations and voltages of the energized and grounded conductors, the conductor diameters and their bundling dimensions and geometry, the elevation of the site, as well as other parameters. The modeling input parameters are provided in Noise Technical Report, Table 6-3 (see Appendix J). Thresholds of Significance The Kern County CEQA Implementation Document and Kern County Environmental Checklist state that a project would normally be considered to have a significant impact if it would: Exposure of persons to, or generation of, noise levels in excess of standards established in the local general plan or noise ordinance or applicable standards of other agencies. Exposure of persons to, or generation of, excessive ground borne vibration or ground borne noise levels. Substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project. Substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project. and Jawbone Wind Energy Project May 2011

15 For a project located within the Kern County Airport Land Use Compatibility Plan, exposure of people residing or working in the project area to excessive noise levels. For a project within the vicinity of a private airstrip, exposure of people residing or working in the project area to excessive noise levels. As discussed in Appendix A (Notice of Preparation/Initial Study [NOP/IS]), the proposed project was determined to have no impact with regard to the following impact thresholds: For a Project Located within the Kern County Airport Land Use Compatibility Plan, Exposure of People Residing or Working in the Project Area to Excessive Noise Levels; and For a project within the vicinity of a private airstrip, exposure of people residing or working in the project area to excessive noise levels. These issues are being re-evaluated in the EIR because it was determined after circulation of the NOP/IS that the project site falls inside the boundaries of the Special Use Airspace of the Joint Service Restricted R-2508 Complex. Project Impacts Impact : Exposure of Persons to, or Generation of, Noise Levels in Excess of Standards Established in the Local General Plan or Noise Ordinance or Applicable Standards of Other Agencies The information in this analysis is based on the Noise Technical Report (2011) prepared by CH2MHILL for the and the Noise Memorandum (2010) for the Jawbone Wind Energy Project, which are included in Appendix J of this EIR. As discussed above and shown in Figures and , sensitive receptors including residences and recreationists along the PCT are located in and near the proposed project site. Operations of the proposed project were analyzed, specifically related to noise generated from the operation of the WTGs, noise generated by operation of the wind energy supporting infrastructure (e.g., substation and transmission lines), and as a result of increased traffic in the project area. The following types of operational noise were analyzed: A-Weighted WTG Noise; Substation and Transmission Line Noise; and Low Frequency WTG Noise; Traffic Noise A-Weighted WTG Noise Based on the CADNA/A modeling results, the estimated overall A-weighted sound pressure levels from all of the WTGs are shown in Figure as contours of constant noise levels. These estimates are based on the WTGs operating at their maximum noise output levels. The highest noise level at a residence resulting from the WTGs is predicted to be 42 dba, and 34 dba at the PCT. For the residences, the Noise Element of the KCGP sets an exterior noise limit of 65 db L dn and an interior noise limit of 45 L dn ). The regulations of the WE Combining District zoning, which are specific to WTG operations, specifies that audible noise levels due to WTG operations that cause the exterior noise levels to exceed 45 dba for more than five minutes out of any 1-hour time period (L8.3) or to exceed 50 dba for any period of time when measured within 50 feet of any existing and Jawbone Wind Energy Project May 2011

16 County of Kern Water Supply Parcel Source: CH2MHILL, and Jawbone Wind Energy Project Figure Wind Turbine Generator Noise Contours at Maximum Output, dba May 2011

17 residence shall not be created. The more stringent of these shall be used to determine the noise impacts to residences. The WE District s limits on noise from WTGs, however, do not apply to outdoor recreation areas such as the PCT; therefore, the KCGP exterior noise limit of 65 db L dn would be used to determine noise impacts to the PCT. The predicted noise level from the WTGs at the closest residence, which is located 3,215 feet away from the closest North Sky River WTG, is less than the Kern County WE Combining District exterior limit of 45 dba (for 5 minutes in any one hour). A worst-case 24 hour noise level at this residence, assuming the 42 dba level would be consistent over the 24-hour period, would be 48 dba an L dn. This level is also less than the KCGP exterior noise limit of 65 dba L dn. For the PCT, the predicted noise level of 34 dba would also fall well below the KCGP exterior noise limit of 65 dba L dn. These estimates are based on estimates from the 2.5 MW WTG; and the noise from the marginal increase in power of the proposed 2.75 MW turbine is not anticipated to exceed any limits. Low Frequency WTG Noise The CADNA/A model was also used to calculate the maximum octave band low frequency WTG noise level at the nearest receptor and compared to the WE Combining District s limits. The results of the modeling are summarized below in Table Estimated WTG Low Frequency Noise Levels at the Nearest Sensitive Receptor One-third Octave Band Center Frequency, Hz Limit Estimated level from WTGs Sound Pressure Level, db Exceed Limit? Amount of Exceedance No None No None No None No None No None No None No None No None Source: CH2MHILL, February 2011 (Table 6-2). See Appendix J. As shown in Table , there are no projected exceedances of the low frequency noise limits identified in the Kern County Zoning Ordinance, Section J (WE Combining District). Therefore, the low frequency noise generated by the proposed WTGs would be less than significant. These estimates are based on estimates from the 2.5 MW WTG; and the noise from the marginal increase in power of the proposed 2.75 MW turbine is not anticipated to exceed any limits. Substation and Transmission Line Noise Operation of the proposed project s collector substation and transmission lines (gen-tie line and transmission reinforcement line) would have the potential to result in noise impacts. Noise impacts attributed to the substations and transmission lines would be considered significant if they were to exceed the 65 db L dn exterior noise limit or the 45 L dn interior noise limit specified in the Noise Element of the KCGP. For the substations, the dominant noise source would be the transformers. Assuming a transformer operating at a maximum capacity of 350 megavolt ampere (MVA), noise levels from the collector substation at the nearest sensitive receptor would be approximately 25 dba (CH2MHILL, 2011). and Jawbone Wind Energy Project May 2011

18 The substation noise levels would be lower when operating at lower loads (i.e., when there is less power being generated by the WTGs under low wind conditions). Therefore, the proposed substation would not result in significant noise impacts. Future corona noise was not evaluated for the transmission reinforcement line due to the short distance traversed, and because there is an existing 230 kv transmission line in the area currently generating corona noise such that the short segment of new line would not noticeably increase ambient noise levels. Therefore, impacts related to corona noise for the Wilderness transmission reinforcement line are less than significant. A new gen-tie line would be constructed between the project site and the Sky River Substation, and the potential exists for a gen-tie line to also be constructed between the Jawbone Wind Energy Project site and the Pine Tree Substation. The new gen-tie lines and associated corona noise would be introduced to an area where no corona noise currently exists. Future corona noise for the new 230-kV gen-tie lines have been estimated in the Noise Technical Report, Table 6-3 (see Appendix J) to be 47 dba under foul (rain) weather conditions and 22 dba under fair weather conditions at the edge of the ROW. This level of noise would be similar to existing ambient noise levels (40-45 dba) and would attenuate quickly. Furthermore, these noise levels are below the KCGP limit of 65 dba L dn. Therefore, impacts related to corona noise from the gen-tie lines would be less than significant. The gen-tie line proposed to be located between the project site and the Sky River Substation would be located in close proximity to the PCT, both paralleling the PCT and in several instances crossing the PCT. Under fair weather conditions, the previously referenced estimated corona noise level of 22 dba at the edge of the transmission line ROW would be below ambient noise levels for the project area and would therefore result in a less-than-significant impact. Under rain (foul) weather conditions, the estimated corona noise level of 47 dba would potentially be higher than existing ambient noise levels; however, ambient noise levels would also likely increase as a result of the rain itself. As such, the increase in corona noise levels under rain (foul) weather conditions would likely not be perceivable and would therefore be considered less than significant. Furthermore, these noise levels are below the KCGP limit of 65 dba L dn ; therefore, impacts related to corona noise on the PCT are less than significant. Traffic Noise The proposed project site is accessed from SR-14 by continuing west on Jawbone Canyon Road for 13 miles. Operations of the proposed project would require up to 32 full- and part-time wind turbine technicians, operations personnel, administrative personnel, and managers. However, not all staff would be working at the same time. Normal operations could involve deployment of up to three crews of two technicians around the site and two to three personnel in the O&M office, resulting in up to nine staff at the project site at any given time. In addition, traffic would be generated as a result of periodic materials and equipment deliveries (e.g., cranes for major repairs, power line or substation repairs, etc.). The level of traffic generated by operation and maintenance staff and the occasional delivery of materials and equipment would not result in a noticeable increase in noise levels along Jawbone Canyon Road or be expected to exceed the KCGP Noise Element limit of 65 db L dn or less in outdoor activity areas. As such, traffic noise impacts would be less than significant. Mitigation Measures The project would comply with the goals, policies, and implementation measures of the KCGP. No additional mitigation measures are proposed. and Jawbone Wind Energy Project May 2011

19 Level of Significance Impacts would be less than significant. Impact : Exposure of Persons to, or Generation of, Excessive Ground borne Vibration or Ground borne Noise Levels Construction activities have the potential to generate a substantial amount of vibration from earth moving activities such as impact pile driving and blasting, as well as from the use of large construction equipment, which can annoy residences and, in severe cases, damage structures. As discussed in the Noise Technical Report, potential vibration impacts from construction were determined based on guidance provided in the Federal Transit Administration s Transit Noise and Vibration Impact Assessment document (FTA, 2006). To avoid damage to structures considered to be extremely susceptible to vibration damage, a vibration velocity limit (or peak particle velocity, PPV) of 0.12 inches per second levels would apply. To avoid annoyance to residences, the appropriate criterion was determined to be a ground-borne vibration level of 80 VdB for infrequent events (see Table ). An analysis using the Federal Transit Administration approach and typical source reference levels for impact pile driving concluded that impacts from construction of the proposed project would not occur beyond approximately 77 feet for damage to structures or beyond 158 feet for residential annoyance (CH2MHILL, 2011). The closest residence is located 3,215 feet from the nearest WTG and would therefore not be affected by the groundborne vibrations generated during construction. According to a recent study titled Wind Turbine Sound and Health Effects: An Expert Panel Review completed for the American Wind Association (Colby, et al., 2009), it was concluded that ground-borne vibrations from the operation of WTGs are too weak to be detected by, or to affect humans. As such, operation of the WTGs would not result in significant levels of ground-borne vibration at the sensitive receptors. Therefore, construction and operation of the proposed project is not anticipated to result in significant vibration impacts. Mitigation Measures No additional mitigation measures are proposed. Level of Significance Impacts would be less than significant. Impact : Substantial Permanent Increase in Ambient Noise Levels in the Project Vicinity above Levels Existing without the Project As discussed in Section , existing background noise levels in the vicinity of the project area are estimated to be approximately dba, and operation of the proposed WTGs would result in estimated noise levels of 42 dba at the closest residence, which is within the range of existing noise levels. Modeled corona noise levels would be similar to existing ambient noise levels (40-45 dba) and would attenuate quickly. As such, the proposed project would not result in a substantial permanent increase in ambient noise levels in the project vicinity. and Jawbone Wind Energy Project May 2011

20 Mitigation Measures No additional mitigation measures are proposed. Level of Significance Impacts would be less than significant. Impact : Substantial Temporary or Periodic Increase in Ambient Noise Levels in the Project Vicinity above Levels Existing without the Project Construction of the proposed project ( and Jawbone Wind Energy Project) would result in temporary increases in ambient noise levels in the project vicinity, both on and off site, during the anticipated 12-month construction duration. On-site noise levels would fluctuate depending on the phase of construction, equipment type and duration of use, distance between the noise source and receptor, and presence or absence of noise-attenuation barriers. Project Description Table 3-7 lists the types of equipment that would be used during the various stages of construction for the. The construction equipment requirements for the Jawbone Wind Energy Project are provided in Project Description Table 3-8. A temporary water reservoir, back-up well, two underground water pipelines, and a postconstruction low profile partially submerged concrete tank would also potentially be constructed on the water supply parcel located northwest of the project site. Excavation, grading, and compaction activities for the reservoir, back-up well, and two pipelines would require two 13-yard self-loading scrapers, one D6 bulldozer, a water truck, and an 84-inch sheep foot vibratory compactor (Sapphos, 2011). Construction of these elements would take approximately seven days and occur concurrently with the first month of grading activities required for the other elements of the proposed project (e.g., WTGs and met towers). Following construction of the above mentioned elements at the water supply parcel, 3.75 miles of Jawbone Canyon Road between the water supply parcel and the point of delivery would be repaired. Equipment required to repair the road would include a motor grader, 9-wheel rubber tire roller, and a water truck (Sapphos, 2011). Typical noise levels from various equipment used during construction are listed in Table , below. This table shows noise levels of individual equipment at distances of 50 and 2,500 feet from the construction noise source. These noise levels are based on surveys conducted by the EPA in the early 1970s. Since 1970, regulations have been enforced to reduce noise generated by certain types of construction equipment to meet worker noise-exposure standards; however, many older pieces of equipment are still in use. As such, the construction equipment noise levels indicated in Table represent worst-case conditions Maximum Noise Levels of Common Construction Equipment Noise Source Noise Level (dba) 1 50 feet 2,500 feet Backhoe Compactor (ground) Crane Dozer Dump Truck Excavator Flat Bed Truck Front End Loader and Jawbone Wind Energy Project May 2011