Appendix L. Acoustical Assessment

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1 Appendix L Acoustical Assessment

2 County of Monterey California Flats Solar Project Acoustical Assessment April 2014

3 California Flats Solar Project Acoustical Assessment Prepared for: Monterey County Resource Management Agency Planning Department 168 W. Alisal St., 2nd Floor Salinas, CA Prepared with the assistance of: Rincon Consultants, Inc. 437 Figueroa Street, Suite 203 Monterey, California April 2014

4 This report is printed on 50% recycled paper.

5 April 8, 2014 Project No Joe Sidor Delinda Robinson Monterey County Resource Management Agency Planning Department 168 W. Alisal St., 2 nd Floor Salinas, CA Dear Mr. Sidor and Ms. Robinson: ACOUSTICAL ASSESSMENT California Flats Solar Project Monterey County, California Rincon Consultants, Inc. is pleased to submit the attached Acoustical Assessment for the proposed California Flats Solar Project in Monterey County, California. The proposed project would have a less than significant impact related to temporary on-site and offsite construction noise, as well as short-term groundborne vibration during project construction. Similarly, the proposed project would not result in long-term operational or regional noise impacts, or otherwise conflict with applicable County General Plan Noise Element policies. As such, impacts related to noise as a result of the proposed project would be less than significant. If you have any questions regarding this study or if we can provide you with other environmental consulting services, please feel free to contact us. Sincerely, RINCON CONSULTANTS, INC. Chris Bersbach, MESM Environmental Planner Richard Daulton, MURP Principal E n v i r o n m e n t a l S c i e n t i s t s P l a n n e r s E n g i n e e r s

6 California Flats Solar Project Acoustical Assessment California Flats Solar Project Acoustical Assessment Table of Contents Page Cover Letter Project Description... 1 Setting... 1 Overview of Sound Measurement... 1 Sensitive Receptors... 2 Project Site Setting... 3 Regulatory Setting... 5 Impact Analysis... 9 Methodology and Significance Thresholds... 9 Short-Term On-Site (Stationary) Construction Noise Short-Term Off-Site (Mobile) Construction Noise Short Term Groundborne Vibration Long-Term Operational Noise Exposure Long-Term Regional Impacts References List of Tables Table 1 Noise Measurement Results... 5 Table 2 OSHA Permissible Noise Exposure Standards... 5 Table 3 Community Noise Exposure (Ldn or CNEL, db)... 6 Table 4 Significance of Changes in Operational Roadway Noise Exposure Table 5 Typical Construction Equipment Noise Levels Table 6 Typical Maximum Construction Noise Levels at Various Distances from Project Construction (dba) Table 7 Calculated Noise Associated with Traffic on Surrounding Highways Table 8 Estimated Noise Rating for Equipment Utilized During Project Operations Table 9 Calculated Noise Associated with Project Operation on Study Area Highways List of Figures Appendices Figure 1 Noise Measurement Locations and Sensitive Receptors... 4 Figure 2 OPR Guidelines for Land Use Compatibility... 7 Noise Measurement Data and Highway Noise Modeling i County of Monterey

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8 California Flats Solar Project Acoustical Assessment ACOUSTICAL ASSESSMENT CALIFORNIA FLATS SOLAR PROJECT MONTEREY COUNTY This report is an analysis of the potential acoustical impacts of the proposed California Flats Solar Project in Monterey County. The report has been prepared by Rincon Consultants, Inc. in support of the environmental documentation being prepared for the California Flats Solar Project pursuant to the California Environmental Quality Act (CEQA). The purpose of this study is to analyze the proposed project s potential temporary noise impacts associated with construction activity and long-term noise impacts associated with project operation, including traffic noise from vehicle trips generated by the proposed project during the construction and operational phases of the project. The analysis herein is based partially on the project Traffic Impact Analysis Report prepared by Kimley-Horn and Associates (August 5, 2013). PROJECT DESCRIPTION California Flats Solar, LLC (the project proponent), proposes to construct and operate a 280 megawatt (MW) alternating current (AC) photovoltaic (PV) solar project on an approximately 2,921-acre site in southeastern Monterey County, California, near the borders of Monterey County, San Luis Obispo County, Kings County and Fresno County. The project would include a 2,120-acre main project area with solar modules and related structures, electrical equipment and infrastructure improvements, including two substations and switching station, an operations and maintenance (O&M) facility, and construction staging areas. The switching station would be constructed adjacent to the proposed northern substation and Pacific Gas & Electric Company (PG&E) owned Morro Bay Gates 230 kilovolt (kv) overhead transmission line which currently transects the project site. The southern substation would be constructed in the southern portion of the site. A new 230kV overhead transmission line would convey power from the southern substation to the northern substation. The new 230kV overhead transmission line would be approximately 2.3 miles long. In addition, the solar project would require construction and operation of a new approximately 151-acre utility corridor and improvements to an existing private access road and within a California Department of Transportation ( Caltrans ) right-of-way at State Route 41. Primary access to the site would be provided from an existing private driveway off of California State Route 41 (SR 41), and emergency access also would be available from Turkey Flat Road. A complete description of the project is provided in the California Flats Solar Project, Project Description, (DD&A, Inc., April 2013). SETTING Overview of Sound Measurement Noise level (or volume) is generally measured in decibels (db) using the A-weighted sound pressure level (dba). The A-weighting scale is an adjustment to the actual sound pressure levels to be consistent with that of human hearing response, which is most sensitive to frequencies 1 County of Monterey

9 California Flats Solar Project Acoustical Assessment around 4,000 Hertz (about the highest note on a piano) and less sensitive to low frequencies (below 100 Hertz). Sound pressure level is measured on a logarithmic scale with the 0 db level based on the lowest detectable sound pressure level that people can perceive (an audible sound that is not zero sound pressure level). Based on the logarithmic scale, a doubling of sound energy is equivalent to an increase of 3 dba, and a sound that is 10 dba less than the ambient sound level has no effect on ambient noise. Because of the nature of the human ear, a sound must be about 10 dba greater than the reference sound to be judged as twice as loud. In general, a 3 dba change in community noise levels is noticeable, while 1-2 db changes generally are not perceived. Quiet suburban areas typically have noise levels in the range of dba, while arterial streets are in the dba range. Normal conversational levels are in the dba range, and ambient noise levels greater than 65 dba can interrupt conversations. Noise levels typically attenuate (or drop off) at a rate of 6 dba per doubling of distance from point sources (such as industrial machinery). Noise from lightly traveled roads typically attenuates at a rate of about 4.5 dba per doubling of distance. Noise from heavily traveled roads typically attenuates at about 3 dba per doubling of distance. Noise levels may also be reduced by intervening structures; generally, a single row of buildings between the receptor and the noise source reduces the noise level by about 5 dba, while a solid wall or berm reduces noise levels by 5 to 10 dba. The manner in which older homes in California were constructed (approximately 30 years old or older) generally provides a reduction of exterior-to-interior noise levels of about 20 to 25 dba with closed windows. The exterior-to-interior reduction of newer residential units and office buildings is generally 30 dba or more (FTA, May 2006). In addition to the actual instantaneous measurement of sound levels, the duration of sound is important since sounds that occur over a long period of time are more likely to be an annoyance or cause direct physical damage or environmental stress. One of the most frequently used noise metrics that considers both duration and sound power level is the equivalent noise level (Leq). The Leq is defined as the single steady A-weighted level that is equivalent to the same amount of energy as that contained in the actual fluctuating levels over a period of time (essentially, the average noise level). Typically, Leq is summed over a one-hour period. Lmax is the highest RMS (root mean squared) sound pressure level within the measuring period, and Lmin is the lowest RMS sound pressure level within the measuring period. The time period in which noise occurs is also important since noise that occurs at night tends to be more disturbing than that which occurs during the day. Community noise is usually measured using Day-Night Average Level (Ldn), which is the 24-hour average noise level with a 10-dBA penalty for noise occurring during nighttime (10 p.m. to 7 a.m.) hours, or Community Noise Equivalent Level (CNEL), which is the 24-hour average noise level with a 5 dba penalty for noise occurring from 7 p.m. to 10 p.m. and a 10 dba penalty for noise occurring from 10 p.m. to 7 a.m. Noise levels described by Ldn and CNEL usually do not differ by more than 1 db. Sensitive Receptors Noise exposure goals for various types of land uses reflect the varying noise sensitivities associated with each of these uses. The County of Monterey 2010 General Plan Noise Element (contained in the General Plan Safety Element) identifies normally acceptable, conditionally 2 County of Monterey

10 California Flats Solar Project Acoustical Assessment acceptable, normally unacceptable, and clearly unacceptable noise levels for a variety of land use and development types, based on the Office of Planning and Research (OPR) General Plan Guidelines. The most noise sensitive land uses include residences, hotels, schools, libraries, churches, hospitals, and nursing homes. Sensitive receptors near the project site include rural residences located north of the northwestern corner of the project site boundary. These residences are located approximately 775 feet from the project site boundary, near the eastern public road terminus of Turkey Flat Road (refer to Figure 1). In addition, there are residential receptors along SR 46 and SR 41 that may be affected by noise from increased traffic along these highway segments. Project Site Setting The proposed project would be built and operated on an approximately 2,921-acre portion of an existing 72,000-acre cattle ranch, known as the Jack Ranch. The general noise environment of the project area is characterized by open space, rural residential, or agricultural use with low ambient noise levels during the evening and nighttime hours. The primary ambient sources of noise on the project site and in the surrounding area include wind, cattle, other fauna (birds, small mammals, etc.), and buzzing from the existing transmission line that transects the project site. Noise generators during the day could include those typically associated with minor agricultural activities, and local passenger and heavy-duty truck traffic along SR 41. In addition, occasional off-highway vehicle travel may contribute to local noise levels. Turkey Flat Road, which carries a low volume of vehicle trips associated with the rural residences near the project site, terminates at the northwestern boundary of the project site. The nearest major roadway to the project site is SR 41, located approximately four miles to the south, which carries approximately 6,200 average daily vehicle trips (e.g., automobiles, buses, trucks, and motorcycles) (Caltrans Traffic Data Branch, 2011). Motor vehicle noise is of concern because it is characterized by a high number of individual events, which often create a sustained noise level. The County of Monterey 2010 General Plan Noise Element provides existing and projected noise contours associated with airports, stationary sources, and roadway sources, which provide a visualization of estimates of sound level. The project site is not within any of the identified noise contours in the 2010 General Plan, indicating that ambient noise levels on the project site are generally below 50 dba. Land forms and man-made structures have very complex effects on sound transmission and on noise contours. Generally, barriers between a source and receiver absorb or reflect noise resulting in a quieter environment. Where barriers or land forms do not interrupt the noise transmission path from source to receiver, the contours prove to be good estimates of the average noise level from roadway traffic. In areas where barriers or land forms interrupt the sound transmission, the noise contours overestimate the extent to which a source intrudes into the community. The noise contour distances describe worst-case conditions because they do not account for any obstructions to the noise path, such as walls, berms, or buildings. Four weekday morning 20-minute ambient noise measurements were taken at the project site using an ANSI Type II integrating sound level meter in accordance with standard protocols on May 13, These noise measurements provide an estimate of the general noise environment on and around the project site. The noise measurement locations are shown on Figure 1. Table 1 identifies the noise measurement locations and measured noise levels. 3 County of Monterey

11 California Flats Solar Project Acoustical Assessment 87 Turkey Flat Rd 8787 D Noise Measurement 4 D Noise Measurement 3 D Noise Measurement 2 Cholame Valley Rd D 87 Project Area Noise Measurement Location Sensitive Receptor 4WD Roads ± Miles Imagery provided by ESRI and its licensors Cholame D ST 41 Noise Measurement 1 Noise Measurement Locations and Sensitive Receptors Figure 1 ST 46 County of Monterey

12 California Flats Solar Project Acoustical Assessment Table 1 Noise Measurement Results (dba) Measurement Location Primary Noise Source Sample Time Leq Lmax Lmin 1. Project site access road intersection with SR 41 (approximately 40 feet from centerline) Vehicle traffic on SR 41 5/13/2013 9:27 a.m. 9:47 a.m Terminus of proposed access road, approximately 300 feet south of proposed O&M facility On-site ambient noise, including light wind, fauna, etc. 5/13/ :53 a.m. 11:13 a.m Northern portion of the project site, below the transmission line that transects the project site On-site ambient noise, including light wind, fauna, etc. 5/13/ :47 a.m. 12:12 a.m Terminus of Turkey Flat Road at the northwestern project site boundary On-site ambient noise, including light wind, fauna, etc. 5/13/ :26 a.m. 12:46 a.m Source: Field visit using ANSI Type II Integrating sound level meter. See Appendix for noise measurement data sheets Regulatory Setting Federal. Under the Occupational Safety and Health Act of 1970 (OSHA) (29 U.S.C. 651 et seq.), the United States Department of Labor, Occupational Safety and Health Administration (OSHA) adopted regulations (29 CFR ) designed to protect workers against the effects of occupational noise exposure. These regulations list limits on noise exposure levels as a function of the amount of time during which the worker is exposed, as shown in Table 2. The regulations further specify requirements for a hearing conservation program ( (c)), a monitoring program ( (d)), an audiometric testing (i.e., test of hearing ability) program ( (g)), and hearing protection ( (i)). There are no federal laws governing community noise. Table 2 OSHA Permissible Noise Exposure Standards Duration of Noise (Hours/Day) A-Weighted Noise Level (dba) or less 115 Source: USEPA 29 CFR , Table G County of Monterey

13 California Flats Solar Project Acoustical Assessment State. California Government Code encourages each local government entity to implement a noise element as part of its general plan. In addition, OPR has developed guidelines for preparing noise elements, which include recommendations for evaluating the compatibility of various land uses as a function of community noise exposure. The recommendations established by the Office of Planning and Research are listed in Figure 2. County of Monterey. The County of Monterey 2010 General Plan Noise Element (contained in the General Plan Safety Element) identifies normally acceptable, conditionally acceptable, normally unacceptable, and clearly unacceptable noise levels for a variety of land use and development types, based on OPR General Plan Guidelines. Table 3 shows the County of Monterey community noise exposure levels. Table 3 Community Noise Exposure (Ldn or CNEL, db) Land Use Category Normally Acceptable Conditionally Acceptable Normally Unacceptable Clearly Unacceptable Residential Low Density Single Family, Duplex, Mobile Homes Residential Multi. Family Transient Lodging Motels, Hotels Schools, Libraries, Churches, Hospitals, Nursing Homes Auditoriums, Concert Halls, 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 Source: Monterey County 2010 General Plan Noise Element. 6 County of Monterey

14 Panoche Valley Solar Farm Project C.11 NOISE California Flats Solar Project EIR Section 4.11 Noise Table C Guidelines for Land Use Compatibility LAND USE CATEGORY Residential - Low Density Single Family, Duplex, Mobile Home Residential - Multi-Family Transient Lodging - Motels, Hotels 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 COMMUNITY NOISE EXPOSURE Ldn or CNEL (dba) Normally Acceptable. Specified land use is satisfactory, based upon the assumption that any buildings involved are of normal conventional construction, without any special noise insulation requirements. Conditionally Acceptable. 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. Normally Unacceptable. New construction or development should generally be discouraged. If new construction or development does proceed, a detailed analysis of the noise reduction requirements must be made and needed noise insulation features included in the design. Clearly Unacceptable. New construction or development should generally not be undertaken. Source: OPR, OPR Guidelines for Land Use Compatibility Figure 2 Source: OPR, 2003 Final EIR C.11 6 County September 2010 of Monterey

15 California Flats Solar Project Acoustical Assessment The County of Monterey 2010 General Plan Noise Element also includes policies that are designed to meet General Plan Goal S-7, to maintain a healthy and quiet environment free from annoying and harmful sounds. These policies address requirements for new noisesensitive land uses, development in areas that may be exposed to high levels of noise, construction of new noise-generating uses, procedures for acoustical analysis and environmental review, regulations for construction activity and the use of heavy construction equipment, and standard noise protection measures for new construction. The applicable General Plan policies include the following: S-7.1 S-7.3 S-7.4 S-7.5 S-7.6 S-7.8 New noise-sensitive land uses may only be allowed in areas where existing and projected noise levels are acceptable according to Land Use Compatibility for Community Noise Table (Table 3). A Community Noise Ordinance shall be established consistent with said Table that addresses, but is not limited to the following (Noise level maps are located at the end of this Element): a. Capacity-related roadway improvement projects. b. Construction-related noise impacts on adjacent land uses. c. New residential land uses exposed to aircraft operations at any airport or air base. d. Site planning and project design techniques to achieve acceptable noise levels such as: building orientation, setbacks, earthen berms, and building construction practices. The use of masonry sound walls for noise control in rural areas shall be discouraged. e. Design elements necessary to mitigate significant adverse noise impacts on surrounding land uses. f. Impulse noise. g. Existing railroad locations & noise levels. Development may occur in areas identified as normally unacceptable provided effective measures to reduce both the indoor and outdoor noise levels to acceptable levels are taken. New noise generators may be allowed in areas where projected noise levels (Figure 10) are conditionally acceptable only after a detailed analysis of the noise reduction requirements is made and needed noise mitigation features are included in project design. New noise generators shall be discouraged in areas identified as normally unacceptable. Where such new noise generators are permitted, mitigation to reduce both the indoor and outdoor noise levels will be required. Acoustical analysis shall be part of the environmental review process for projects when: a. Noise sensitive receptors are proposed in areas exposed to existing or projected noise levels (Figures 9 and 10) that are normally unacceptable or higher according to Table S-2 ( Land Use Compatibility for Community Noise ). b. Proposed noise generators are likely to produce noise levels exceeding the levels shown in the adopted Community Noise Ordinance when received at existing or planned noisesensitive receptors. All discretionary projects that propose to use heavy construction equipment that has the potential to create vibrations that could cause structural damage to adjacent structures within 100 feet shall be required to submit a pre-construction vibration study prior to the approval of a building permit. Projects shall be required to incorporate specified measures and 8 County of Monterey

16 California Flats Solar Project Acoustical Assessment monitoring identified to reduce impacts. Pile driving or blasting are illustrative of the type of equipment that could be subject to this policy. S-7.9 No construction activities pursuant to a County permit that exceed acceptable levels listed in Policy S-7.1 shall be allowed within 500 feet of a noise sensitive land use during the evening hours of Monday through Saturday, or anytime on Sunday or holidays, prior to completion of a noise mitigation study. Noise protection measures, in the event of any identified impact, may include but not be limited to: Constructing temporary barriers, or Using quieter equipment than normal. S-7.10 Construction projects shall include the following standard noise protection measures: Construction shall occur only during times allowed by ordinance/code unless such limits are waived for public convenience; All equipment shall have properly operating mufflers; and Lay-down yards and semi-stationary equipment such as pumps or generators shall be located as far from noise-sensitive land uses as practical. In addition to applicable General Plan policies, Title 24 of the California Health and Safety Code establishes an interior noise standard of 45 dba for residential units. IMPACT ANALYSIS Methodology and Significance Thresholds Methodology. The analysis of noise impacts considers the effects of both temporary construction--related noise and long-term noise associated with operation of the proposed project. The analysis also includes a brief qualitative discussion of potential future decommissioning of the project. Construction noise estimates are based upon noise levels reported by the Federal Transit Administration (FTA), Office of Planning and Environment (FTA, May 2006), and the distance to nearby sensitive receptors. Reference noise levels from that document were then used to estimate noise levels at nearby sensitive receptors based on a standard noise attenuation rate of 6 db per doubling of distance (line-of-sight method of sound attenuation for point sources of noise). Construction noise level estimates do not account for the presence of intervening structures or topography, which could reduce noise levels at receptor locations. Therefore, the noise levels presented herein represent a conservative, reasonable worst-case estimate of actual construction noise. The maximum community noise exposure levels shown above in Table 3 and applicable County General Plan Noise Element policies were used to determine whether noise generated during the project construction or operational phases would result in a significant impact on nearby sensitive receptors. Long-term operational point sources of noise (including PV solar arrays, transformers, inverters, the substation, collector lines, and the operations and maintenance facility) were calculated using a similar methodology to short-term construction equipment. Operational noise would result in a significant impact if long-term noise from equipment located on the project site would exceed the County s maximum community noise exposure levels (refer to Table 3), or would conflict with applicable County General Plan Noise Element policies. 9 County of Monterey

17 California Flats Solar Project Acoustical Assessment Noise levels associated with existing and future traffic along area highways were calculated using the Traffic Noise Model Version 2.5 Look-Up Tables (U.S. Department of Transportation, Federal Highway Administration [FHWA], April 2004) (noise modeling data sheets can be viewed in the Appendix). The model calculations are based on traffic data from the project Traffic Impact Analysis Report prepared by Kimley-Horn and Associates (August 5, 2013). Significance Thresholds. For traffic-related noise, impacts are considered significant if project-generated traffic would result in exposure of sensitive receptors to an unacceptable increase in noise levels. Recommendations contained in the May 2006 Transit Noise and Vibration Impact Assessment created by the FTA were used to determine whether increases in traffic noise would be unacceptable. With these standards, the allowable noise exposure increase is reduced with increasing ambient existing noise exposure, such that higher ambient noise levels have a lower allowable noise exposure increase. Table 4 shows the significance thresholds for increases in traffic-related noise levels caused by the project. Table 4 Significance of Changes in Operational Roadway Noise Exposure Existing Noise Exposure (dba Ldn or Leq) Allowable Noise Exposure Increase (dba Ldn or Leq) Source: Federal Transit Administration. Transit Noise and Vibration Impact Assessment. May If sensitive receptors would be exposed to traffic noise increases exceeding the above criteria, impacts would be considered significant. Impacts related to on-site activities, such as noise from long-term project operation, would be considered significant if project activities would result in noise levels exceeding the County of Monterey community noise exposure levels shown in Table 3, or conflict with applicable County General Plan Noise Element policies. Note that, as described in the project traffic study, the use of the site emergency access at Turkey Flat Road would be infrequent and consistent with the number of trips generated by current ranch operations (approximately 10 trips per day). Existing ranch-related trips to the Turkey Flat Road access would be transferred to the project driveway at SR 41 due the proposed driveway improvements at that intersection. The transfer of ranch trips to the primary site access would offset potential additional project related trips to Turkey Flat Road, and would result in a zero net increase in trips on Turkey Flat Road during both the project construction 10 County of Monterey

18 California Flats Solar Project Acoustical Assessment and operational phase; therefore, no noise impacts along Turkey Flat Road are anticipated as a result of the project. Short-Term On-Site (Stationary) Construction Noise Maximum noise levels associated with the use of heavy equipment at construction sites can range from about 74 to 101 dba at 50 feet from the source, depending upon the types of equipment in operation at any given time and phase of construction (FHWA, 2006). Table 5 demonstrates the typical noise levels associated with heavy construction equipment, including pile-driving. Table 5 Typical Construction Equipment Noise Levels Equipment Acoustical Usage Factor (%) 1 Measured Lmax (db at 50 feet) Augur Drill Rig Backhoe Compactor (ground) Dozer Dump Truck Excavator Flat Bed Truck Front End Loader Generator Grader Impact/Vibratory Pile Driver Pickup Truck Pneumatic Tools Roller Scraper Warning Horn 5 83 Welder/Torch : The average fraction of time each piece of construction equipment is operating at full power (i.e., its loudest condition) during a construction operation. Source: FHWA, Project construction activities would involve the use of a variety of construction equipment throughout the various phases of construction, including transport of personnel and materials to the site, heavy machinery used in grading and clearing the site, track-mounted vibratory pile drivers for foundation support post installation, as well as equipment used during construction 11 County of Monterey

19 California Flats Solar Project Acoustical Assessment of the proposed solar arrays, infrastructure improvements, and related structures. Temporary noise impacts associated with construction may adversely affect nearby rural residential uses. The highest noise levels during construction would result from pile-driving foundation support posts (similar to steel posts used in highway guard rails) for the solar array modules. Noise levels would diminish at approximately 6 dba per doubling of distance (refer to Overview of Sound Measurement above). Noise-sensitive uses near the project site include rural residences located north of the northwestern corner of the project site boundary near the terminus of Turkey Flat Road. One of these residences is approximately 775 feet from the project site boundary, and the second is approximately 1,000 feet from the project site boundary (refer Figure 1). These land uses would experience a temporary increase in noise during construction of the proposed project. Table 6 shows typical maximum construction noise levels at various distances from construction activity, including 775 feet (the distance to the nearest sensitive noise receptor), based on a standard noise attenuation rate of 6 dba per doubling of distance for point sources of noise. Table 6 Typical Maximum Construction Noise Levels at Various Distances from Project Construction (dba) Distance from Construction Maximum Noise Level at Receptor (with Pile-Driving) Maximum Noise Level at Receptor (no Pile-Driving) 50 feet feet feet feet feet ,000 feet ,500 feet At 775 feet from the project site boundary (the distance to the nearest residential receptor), simultaneous heavy equipment use at the project site during construction would generate a combined maximum noise level of up to approximately 77 dba Leq during system installation, which is when post driving activities would occur. This maximum noise level would only result when construction activities are occurring at the northernmost edge of the project site. Construction would proceed generally from the northern end of the project site to the south, and most construction activities, including post driving activities, would occur further from nearby noise receptors, and would therefore result in substantially lower noise levels, especially later during the construction phase. Based on the County of Monterey s community noise exposure levels shown in the County s General Plan Noise Element policies S-7.9 and S-7.10, noise levels in this range would be unacceptable if they occurred within 500 feet of a noise-sensitive land use during the evening hours of Monday through Saturday, or anytime on Sunday or holidays, prior to completion of a noise mitigation study. Between October 1 and May 31, construction activities would normally 12 County of Monterey

20 California Flats Solar Project Acoustical Assessment occur on the site from 6:00 AM to 6:00 PM, Monday through Friday. Due to hot weather, between June 1 and September 30, construction activities may begin as early as 5:00 AM and continue to 9:00 PM, Monday through Friday. Some nighttime construction may be required to finish construction activities that cannot be readily stopped at the end of the regular construction day or to maintain the construction schedule. Activities that may extend into nighttime hours include concrete pouring, substation equipment installation, and drilling operations for installation of the wells. In addition, construction of the project may require nighttime activities, including the delivery of materials, construction, and security patrols, to maintain the project schedule and accommodate deliveries requiring special logistics, such as transformers. Forty percent of all equipment deliveries, excavation debris, and material hauling trips are anticipated to take place in the nighttime or daytime off-peak hours. The night time trip generation represents the maximum number of trips that can reasonably be expected to deliver equipment to the site on one or more nights. These trips will vary, depending on the ability of equipment providers and shippers to deliver goods in the daytime, and also the ability to offload equipment in a timely manner. No more than 80 total night time trips are expected to occur during the 12 to 18 month construction period; however, there may be up to six deliveries (12 delivery vehicle trips) per night during the peak installation of the inverters and substations. Because construction activities would not occur within 500 feet of any residential receptor, construction noise impacts would be less than significant. Nevertheless, the project would be required to comply with County General Plan Noise Element Policy S-7.10, which includes standard noise protection measures, including construction timing limits, construction equipment muffler requirements, and lay-down yard and semi-stationary equipment location requirements. At the end of the project s useful life (anticipated to be 30 years or more), the proposed solar facility and associated infrastructure may be decommissioned in accordance with then-standard decommissioning practices, site conditions, and regulatory requirements. Given the project s operating life cycle and distant timeframe for decommissioning activities, it is too speculative to provide details describing specific decommissioning activities and potential impacts that could occur far into the future. As such, this analysis evaluates decommissioning based on current standard decommissioning practices, which include dismantling and repurposing, salvaging/recycling, or disposing of the solar energy improvements, and site restoration. The California Flats Solar Project, Conceptual Restoration Plan for Project Decommissioning (July 2012), submitted as part of the CDP application, describes the general nature of the actions that would typically occur to decommission the project, including the removal of various solar power improvements that do not have any residual use to the landowner or that could be incompatible with resuming cattle ranching/agricultural activities on the site. The conceptual decommissioning plan also included a generalized discussion of the type of temporary effects that that could occur during decommissioning (e.g., as a result of grading).. At this time it is not possible to quantitatively or qualitatively evaluate potential noise associated with project decommissioning, due to the uncertainty of when decommissioning would occur and the technology or construction practices that would be available at that time. However, decommissioning and site restoration activities would be conducted in accordance with all applicable requirements in effect at the time of project termination, and a final decommissioning plan, based on then-current technology, site conditions, and regulations, would be prepared prior to actual decommissioning. 13 County of Monterey

21 California Flats Solar Project Acoustical Assessment On a rough basis, deconstruction would be similar to project construction and be completed in 12 to 18 months. Assuming that the facility will be torn down and the materials present recycled or disposed, temporary noise associated with such actions are assumed to be generally similar to the noise levels that would result from project construction; therefore, decommissioning of the project would result in less than significant noise impacts. Short-Term Off-Site (Mobile) Construction Noise Construction of the proposed project would generate noise off-site, primarily from commuting construction workers and from haul trucks bringing materials to the project site. As discussed in the project traffic study prepared by Kimley-Horn and Associates (August 5, 2013), projectrelated construction traffic (12- to 18-month construction duration) would include approximately 93 passenger vehicle trips and 170 heavy truck trips each day, or approximately 41 passenger vehicle trips and 47 heavy truck trips during the a.m. and p.m. peak hours. According to the applicant s preliminary grading plan, grading would include approximately 880,000 cubic yards (CY) of cut and 880,000 CY of fill, and would be balanced on-site; therefore grading would not result in off-site trips, and noise associated with grading and transportation of cut and fill soil on the project site is characterized under Short-Term On-Site Stationary Construction Noise, above. The project traffic study analyzed turning movements at three intersections: Cholame Valley Road and SR 46; SR 41 and SR 46; and the private access road to the project site and SR 41. There are no residential noise receptors adjacent to the segments of SR 41 in the vicinity of the project site. West of the project site, there are rural residences along SR 46 at varying distances from the highway, with the closest being located 125 feet south of the highway centerline (this receptor is approximately 7.5 miles southwest of the project site access road). In addition, there are mobile home residential receptors along SR 46 near Paso Robles, located approximately 100 feet north of the centerline of the highway. East of the project site, there are residential noise receptors along SR 46, with the closest being 100 feet south of the highway centerline in the community of Lost Hills. The Jack Ranch Café is located approximately 55 feet from the centerline of SR 46, but is not a sensitive noise receptor. Based on the location of these off-site sensitive receptors, traffic noise levels were assessed along four potentially affected highway segments that would experience the worst-case traffic noise increases that may affect sensitive noise receptors. Using 2011 peak-hour traffic volumes, including medium and heavy truck volumes (Caltrans Traffic Data Branch, 2013) and the construction vehicle trip distribution for SR 41 and SR 46 shown in the project traffic study, the resulting peak hour noise levels were calculated for segments of SR 46 that are in proximity to residential noise receptors. Table 7 shows the resulting peak hour noise levels at off-site sensitive receptors along affected segments of SR 46 and SR County of Monterey

22 California Flats Solar Project Acoustical Assessment Table 7 Calculated Noise Associated with Construction Traffic on Study Area Highways Highway Segment Existing (Peak Hour) Projected Noise Level (dba Leq) Existing + Construction (Peak Hour) Change In Noise Level (dba Leq) due to Project Construction Traffic (Peak Hour) 1. SR 46, east of SR 41 S junction near Shandon (125 feet from centerline) 2. SR 46, west of Paso Robles Airport Road (100 feet from centerline) 1 3. SR 46, west of Warren Drive in Lost Hills (100 feet from centerline) 4. Highway 41, east of project site access at the Kern/Kings County line (100 feet from centerline) Model estimate includes existing ~7 foot masonry barrier. All other segments do not include any sound barriers. Refer to Appendix for full noise model output. Noise levels presented do not account for attenuation provided by existing barriers or future barriers; therefore, actual noise levels at sensitive receptor locations influenced by study area roadways may in many cases be lower than presented herein. Source: Federal Highway Administration Traffic Noise Model Version 2.5 Look-Up Tables. As shown in Table 7, traffic related to project construction would increase weekday peak hour traffic noise levels by 0.2 to 0.3 dba at sensitive noise receptors along SR 46 and SR 41. As described above, there are no residential noise receptors along the portion of SR 41 that would be affected by construction traffic. Based on the existing ambient noise levels from traffic along the affected segments of SR 46 (65+ dba), an increase in traffic noise of greater than 1 dba would result in a significant impact (refer to Table ). The anticipated noise level increases along the affected segments during the construction period (0.2 to 0.3 dba) would not exceed 1 dba. Therefore, traffic noise during the construction phase would not result in a significant impact. In addition, p.m. peak hour trips are required by mitigation included in the Traffic Impact Analysis Report to travel north on SR 41, whereas the a.m. trips would be on the segment south of the site access road and SR 46. Because there are no sensitive noise receptors along the portion of SR 41 that would be affected by construction traffic, this mitigation would not result in a potential traffic noise impact. In addition, as described above, project decommissioning activities would be generally similar to project construction and be completed in 12 to 18 months. Assuming that the facility will be torn down and the materials present recycled or disposed, temporary traffic noise associated with such actions are assumed to be generally similar to the noise levels that would occur during project construction; therefore, decommissioning of the project would result in less than significant transportation noise impacts. 15 County of Monterey

23 California Flats Solar Project Acoustical Assessment Short-Term Groundborne Vibration Track-mounted vibratory pile drivers would be utilized for installation of the PV solar array foundation support posts and water pipeline posts, which could cause vibration impacts at close distances. While these construction activities would result in minor amounts of ground borne vibration, such groundborne noise or vibration would attenuate rapidly from the source and would not be perceptible outside of the construction areas. Pursuant to General Plan Policy S-7.8, projects that propose to use heavy construction equipment that has the potential to create vibrations, such as pile driving equipment, are required to submit a pre-construction vibration study if operation of such equipment could cause structural damage to adjacent structures within 100 feet. The sensitive receptors nearest to the proposed construction site are rural residences located approximately 775 feet north of the northwestern corner of the project site boundary. Therefore, a pre-construction vibration study would not be required for the proposed project. No sources of groundborne vibration would be expected to impact receptors outside of the project site, and there would not be any potential for excessive exposure of persons to or generation of ground borne vibration levels. If decommissioning of the project would require the use of equipment that causes substantial sources of groundborne vibration, the vibration impacts would likely be similar to the construction phase impacts are therefore less than significant. Long-Term Operational Noise Exposure The proposed project would operate continuously, seven days a week. Potential stationary noise sources associated with the project would include PV solar arrays with associated electrical equipment (such as a transformer or inverter), substations, collector lines, and the operations and maintenance facility. PV Solar Arrays. Acoustic assessments of similar equipment to that proposed on the project site have been conducted for existing solar projects in Ontario, Canada and Boulder City, Nevada; and an existing solar facility located at Nellis Air Force Base in Las Vegas, Nevada (Topaz Solar Farm Project Final EIR, County of San Luis Obispo, March 2011; California Valley Solar Ranch Project Final EIR, County of San Luis Obispo, January 2011). Based on data from these facilities, the noise rating of each piece of equipment has been estimated (refer to Table 8). Table 8 Estimated Noise Rating for Equipment Utilized During Project Operations Equipment Type Noise Rating at Source (operating at full power) 500+ kw Inverter (uncontrolled) 80 dba 500+ kw Inverter (within enclosure) 58 dba Transformer 57 dba Exhaust Fan 71 dba HVAC System 79 dba Source: Topaz Solar Farm Project Final EIR, County of San Luis Obispo, March 2011; California Valley Solar Ranch Project Final EIR, County of San Luis Obispo, January County of Monterey

24 California Flats Solar Project Acoustical Assessment As shown in Table 8, uncontrolled inverter noise could be as high as 80 dba. The noise from inverters is frequently controlled by housing them in steel and concrete enclosures. Transformers would be located with the inverters, either inside or outside of the inverter enclosure. Within enclosures, a typical inverter would result in average sound levels of 58 dba Leq at the sources, based on National Electrical Manufacturers Association (NEMA) requirements (NEMA, 2000). It is unknown at this time whether the inverters/transformers would be enclosed or uncontrolled. This would be determined during design once the inverter/transformer manufacturer has been selected. Based on these measurements, the worst-case (uncontrolled) noise generated from this type of equipment, which would only operate during daytime hours when the solar project is generating power, would be approximately 52 dba at 75 feet from the inverters (California Valley Solar Project Final EIR, January 2011). If the inverters are enclosed, each inverter enclosure would also include an exhaust fan and may also include heating, ventilation, and air conditioning (HVAC) systems mounted on the exterior of the inverter enclosure, which would be more audible than the inverters themselves. These infrastructural systems would result in average sound levels of up to 79 dba Leq at the sources, or up to 51 dba at 75 feet from the enclosed inverters. The proposed project is not a noise sensitive use and the existing or future ambient noise environment would not be expected to adversely affect the proposed project. For the nearest off-site sensitive noise receptor, which is approximately 775 feet north of the northwestern corner of the project site boundary, the anticipated noise level would be 35 dba Leq or lower, whether the inverters are uncontrolled or enclosed. Comparing this operational noise level to the ambient noise levels in the project area (29 to 58 dba Leq daytime; refer to Table ), permanent noise levels in the project area would not increase substantially above existing ambient noise levels as a result of the proposed PV solar arrays. Therefore, operational noise impacts resulting from the PV solar arrays would be less than significant. Substations and Collector Lines. Substations usually generate steady noise from the process of power conversion and the operation of transformers and auxiliary equipment needed to cool the transformers, including cooling fans and oil pumps. Transformer noise contains pure-tone or hum components. This tonal quality is typically the most offensive characteristic of transformer noise. Operational noise levels of the substation transformers would produce a peak daytime noise level of 89 dba Lmax at six feet from the source, with a nighttime noise level of 86 dba Lmax at a distance of one foot from the source, which, as noted above, is attributed to transformer hum (Topaz Solar Farm Project Final EIR, March 2011). The closest residential receptor to either of the project s two new substations is approximately two miles northwest of the northern substation, and would be expected to experience estimated noise levels of less than 30 dba Leq from the substations, which would be within the existing ambient noise levels of the project area. The collector lines would not be a substantial source of noise. Similarly, the operations and maintenance facility would not be a stationary source of noise. Site Personnel and Other Operational Activities. Normal operating hours of the project would be between 6:00 AM and 6:00 PM, Monday through Friday. Vehicle trips that would be associated with operations and maintenance of the project are described in Impact N-5. In addition, the project would require some nighttime activities, including occasional deliveries, 17 County of Monterey