This section discusses and analyzes the ambient noise characteristics of the proposed Cluster I Solar Power Project.

Transcription

1 This section discusses and analyzes the ambient noise characteristics of the proposed Cluster I Solar Power Project Environmental Setting Concepts and Terminology Acoustic Fundamentals Noise is generally defined as sound that is loud, disagreeable, or unexpected. Sound, as described in more detail below, is mechanical energy transmitted in the form of a wave because of a disturbance or vibration. Amplitude Amplitude is the difference between ambient air pressure and the peak pressure of the sound wave. Amplitude is measured in decibels (db) on a logarithmic scale. For example, a 65 db source of sound, such as a truck, when joined by another 65 db source results in a sound amplitude of 68dB (i.e., doubling the source strength increases the sound pressure by 3 db). Amplitude is interpreted by the ear as corresponding to different degrees of loudness. Laboratory measurements correlate a 10 db increase in amplitude with a perceived doubling of loudness and establish a 3 db change in amplitude as the minimum audible difference perceptible to the average person. Frequency Frequency is the number of fluctuations of the pressure wave per second. The unit of frequency is the Hertz (Hz). One Hz equals one cycle per second. The human ear is not equally sensitive to sound of different frequencies. Sound waves below 16 Hz or above 20,000 Hz cannot be heard at all, and the ear is more sensitive to sound in the higher portion of this range than in the lower. To approximate this sensitivity, environmental sound is usually measured in A-weighted decibels (dba). On this scale, the normal range of human hearing extends from about 10 dba to about 140 dba. Characteristics of Sound Propagation and Attenuation Noise can be generated by a number of sources, including mobile sources, such as automobiles, trucks and airplanes, and stationary sources, such as construction sites, machinery, and industrial operations. Noise generated by mobile sources typically attenuates (loudness is reduced) at a rate between 3.0 to 4.5 dba per doubling of distance. The rate depends on the ground surface and the number or type of solid objects between the noise source and the receiver that interrupt the sound wave. Mobile transportation sources, such as vehicles traveling on highways with hard and flat surfaces, such as concrete or asphalt, have an attenuation rate of 3.0 dba per doubling of distance. Soft surfaces, such as uneven or vegetated terrain, have an attenuation rate of about 4.5 dba per doubling of distance from the source. Noise generated by stationary sources typically attenuates at a rate of approximately 6.0 to 7.5 dba per doubling of distance from the source. Imperial County Planning & Development Services Department ESA /

2 Sound levels can be reduced by placing barriers between the noise source and the receiver. In general, barriers contribute to decreasing noise levels only when the structure breaks the line of sight between the source and the receiver. Buildings, concrete walls, and berms can all act as effective noise barriers. Wooden fences or broad areas of dense foliage can also reduce noise but are less effective than solid barriers. Noise Descriptors The selection of a proper noise descriptor for a specific source is dependent upon the spatial and temporal distribution, duration, and fluctuation of the noise. The noise descriptors most often encountered when dealing with traffic, community, and environmental noise are defined below. Maximum Noise Level (Lmax): The maximum instantaneous noise level during a specific period of time. Minimum Noise Level (Lmin): The minimum instantaneous noise level during a specific period of time. Energy Equivalent Noise Level (Leq): The energy mean (average) noise level. The instantaneous noise levels during a specific period of time in dba are converted to relative energy values. From the sum of the relative energy values, an average energy value (in dba) is calculated. Day-Night Noise Level (Ldn): The 24 hour Leq with a 10 dba penalty for noise events that occur during the noise sensitive hours between 10:00 PM and 7:00 AM. In other words, 10 dba is added to noise events that occur in the nighttime hours to account for increased human sensitivity to noise during these hours. Community Noise Equivalent Level (CNEL): The CNEL is similar to the Ldn described above, but with an additional 5 dba penalty added to noise events that occur in the evening between the hours of 7:00 PM to 10:00 PM. The calculated CNEL is typically approximately 0.5 dba higher than the calculated Ldn. Single Event Noise Level (SEL): The SEL describes a receiver s cumulative noise exposure from a single noise event, which is defined as an acoustical event of short duration and involves a change in sound pressure above a reference value. Human Response to Noise The human response to environmental noise is subjective and varies considerably from individual to individual. Noise in the community has often been cited as a health problem, not in terms of actual physiological damage, such as hearing impairment, but in terms of inhibiting general wellbeing and contributing to undue stress and annoyance. The health effects of noise in the community arise from interference with human activities, including sleep, speech, recreation and tasks that demand concentration or coordination. Hearing loss can occur at the highest noise intensity levels. When community noise interferes with human activities or contributes to stress, public annoyance with the noise source increases. The acceptability of noise and the threat to public well-being are the basis for land use planning policies preventing exposure to excessive community noise levels. Typical community noise levels are depicted in Table Imperial County Planning & Development Services Department ESA /

3 TABLE TYPICAL COMMUNITY NOISE LEVELS INDOORS A-Weighted Decibels Perceived Loudness Relative to 60 dba OUTDOORS 140 Threshold of Pain x256 Military Jet Takeoff with Afterburner (at 50 feet) Rock Band Inside Subway Train, New York Deafening Uncomfortably Loud x128 x64 x32 x16 Jet Takeoff at 200 Feet Takeoff (4 Miles From Start of Roll) Power Lawnmower (at 50 Feet) Ambulance Siren (at 100 Feet) Noisy Cocktail Bar Jet Aircraft Cabin, at Cruise Shouting (at 3 Feet) Noisy Restaurant Vacuum Cleaner at 3 Feet Large Business Office Normal Conversation (at 3 Feet) Moderately Loud Very Loud x8 x4 x2 x Takeoff (4 Miles From Start of Roll) Diesel Truck, 40 mph (at 50 Feet) Automobile, 65 mph (at 50 Feet) Busy Street (at 50 Feet) Takeoff (4 Miles From Start of Roll) Automobile, 30 mph (at 50 Feet) Cessna 172 Landing (3,300 Feet From Rwy End) Quiet Office Quiet Library Moderately Quite x1/2 x1/4 Quiet Urban Area, Nighttime Quiet Suburban Area, Nighttime Concert Hall, Background Recording Studio Very Quiet x1/8 x1/16 Quiet Rural Area, Nighttime Leaves Rustling 10 0 Barely Audible x1/32 x1/64 Imperial County Planning & Development Services Department ESA /

4 Existing Noise Setting Project Site The three project sites are located in central Imperial County, California, in a rural area within 2.5 miles north of the City of Calipatria. The project vicinity is actively cultivated, and irrigation canals and drains border most fields. The project site is characterized by agricultural fields that are currently in crop production. There are no buildings or structures on the project sites. The southern boundary of the Calipatria I site borders the City of Calipatria s city limits and is within the City s sphere of influence. This area is zoned A2U, general agriculture/urban zone. The areas immediately north, east and west of the project area are designated for agricultural uses. The western border of Calipatria I is bounded by the Union Pacific Railroad. Midway I and II are entirely surrounded by agricultural land. The three sites are primarily bounded by public roads. Calipatria I is surrounded by Young Road to the south, Blair Road to the East, West Lindsey Road to the north and the railroad to the west. Midway I is bounded by East Peterson Road to the South, English Road to the east, Sinclair Road to the north, and farmland to the west. Midway II is bounded by West Lindsey Road and Montgomery to the south, a private road to the east, East Hoober road to the north and English Road to the west. Ambient Noise Environment Primary sources of noise in the project area include aircraft overflights, agricultural equipment, operations on the UPRR line, and vehicle traffic. The predominant land use in the area is agriculture. Noise sources associated with agricultural operations include the field machinery and aircraft. Typical electric pump noise emissions from agricultural operations range from 69 to 77 dba at 50 feet. Existing Airport Noise The nearest general airport is the Cliff Hatfield Memorial Airport, located approximately 1900 square feet southwest of the of the proposed Calipatria I Solar Farm site. Calipatria I is located within the airport planning area/airport influence area for Cliff Hatfield Memorial Airport as defined in the ALUCP, Imperial County Airports (Imperial County, 1996). It is partially located within Zone B-1 Approach/Departure Zone and Adjacent to Runway and Zone C Common Traffic Pattern which are defined in Chapter 2 of the ALUCP. Noise Sensitive Land Uses Some land uses are considered more sensitive to ambient noise levels than others because of the amount of noise exposure (in terms of both exposure duration and insulation from noise) and the types of activities typically involved. Residences, hotels, schools, rest homes, and hospitals are generally more sensitive to noise than commercial and industrial land uses. The nearest sensitive receptors to the project are residences and a place of worship located approximately 200 feet from the Calipatria I site. Imperial County Planning & Development Services Department ESA /

5 Regulatory Framework Federal Federal Transit Administration (FTA) Currently, the County of Imperial does not have regulations regarding vibration impact criteria. However, the FTA publication, Transit Noise and Vibration Noise Impact Assessment (2006), established vibration standards. The criteria for acceptable groundborne vibration are expressed in terms of root-mean-square velocity levels in decibels. The criteria are related to groundborne vibration causing human annoyance or interfering with use of vibration-sensitive equipment. Structural Response Criteria Vibration tolerance criteria typically depend on the type of structures that are affected. Structural response to vibration is typically evaluated in terms of peak particle velocity (PPV), which is often used since it is related to the stresses that are experienced by buildings. Various general standards are contained in the International Standards Organization standards 3945, 4866, and Limits set by these standards indicate a low probability of structural damage occurring to common structures at a PPV of 2.0 inches per second. Older (and non-reinforced) masonry structures would have a limit of 0.75 to 1.0 inches per second. The FTA identifies a vibration damage threshold criterion of 0.20 inches per second for non-engineered timber and masonry buildings (i.e., fragile buildings) or 0.12 inches per second for buildings extremely susceptible to vibration (i.e., fragile historic buildings). State The State of California regulates vehicular and freeway noise affecting classrooms, sets standards for sound transmission and occupational noise control, and identifies noise insulation standards and airport noise/land use compatibility criteria. The State of California General Plan Guidelines (2003), published by the Governor s Office of Planning and Research, also provides guidance for the acceptability of projects within specific CNEL/Ldn contours. The guidelines present adjustment factors that may be used in order to arrive at noise acceptability standards that reflect the noise control goals of the community, the particular community s sensitivity to noise, and the community s assessment of the relative importance of noise pollution. The County of Imperial has utilized the adjustment factors provided and has modified the state s land use compatibility standards for the purpose of implementing the Noise Element of its General Plan. Table summarizes the acceptable and unacceptable community noise exposure limits for various land use categories as currently defined by the State of California. Local County of Imperial General Plan The County has established noise guidelines in the Noise Element of the General Plan. These guidelines identify compatible exterior noise levels for various land use types. The maximum allowable noise exposure for various land uses are depicted in Table As shown in the table, the normally acceptable exterior noise level for residential uses is 60 db CNEL. Exterior Imperial County Planning & Development Services Department ESA /

6 noise levels above 60 db CNEL (up to 70 db CNEL) are conditionally acceptable for residential uses after a detailed analysis of the noise reduction requirements is made and needed noise insulation features included in the design. Commercial uses are subject to a maximum normally acceptable exterior noise level of 65 db CNEL, while playgrounds and neighborhood parks are 70 db CNEL (County of Imperial 1993). TABLE LAND USE COMPATIBILITY Land Use Category Normally Acceptable Conditionally Acceptable Normally Unacceptable Clearly Unacceptable Residential To 60 db db db Over 75 db Transient Lodging Motels, Hotels To 60 db db db Over 80 db Schools, Libraries, Churches, Hospitals, Nursing Homes To 60 db db db Over 80 db Auditoriums, Concert Halls, Amphitheatres To 70 db Over 70 db Sports Arena, Outdoor Spectator Sports To 70 db db Over 75 db Playgrounds, Neighborhood Parks To 70 db db Over 75 db Golf Courses, Riding Stables, Water Recreation, Cemeteries Office Buildings, Business Commercial and Professional Industrial, Manufacturing, Utilities, Agriculture To 70 db db Over 80 db To 65 db db db Over 80 db To 70 db db db Over 80 db SOURCE: County of Imperial 1993 Construction Noise Per the Noise Element of the Imperial County General Plan, impacts from construction are defined as construction noise from a single piece of construction equipment or a combination of equipment that exceeds 75 dba Leq when averaged over an 8-hour period and measured at the nearest sensitive receptor (e.g., residences, schools, hospitals, parks, office buildings, and certain non-human species, including riparian bird species). In cases of extended length construction times, the standard may be tightened so as not to exceed 75 db Leq when averaged over a onehour period. The County s General Plan limits sound levels from construction activities during specific hours of the day and night through a set of construction noise standards presented below in Table The standards apply to the noise measured at the nearest sensitive receptor. Imperial County Planning & Development Services Department ESA /

7 TABLE COUNTY OF IMPERIAL CONSTRUCTION NOISE STANDARDS Construction Duration Sound Level (db Leq) Averaging Period Hours of Operation Restriction Short-Term (days or weeks) 75 8 hours 7 AM 7 PM Monday to Friday 9 AM 5 PM Saturday No commercial construction operation is permitted on Sundays and holidays. Extended Periods 75 1 hour 7 AM 7 PM Monday to Friday 9 AM 5 PM Saturday No commercial construction operation is permitted on Sundays and holidays. SOURCE: County of Imperial 1993 The Noise Element also states that construction equipment operation be limited to the hours of 7 AM to 7 PM, Monday through Friday, and 9 AM to 5 PM Saturday. Operational Noise Noise-generating sources in Imperial County are regulated by the County of Imperial Codified Ordinances, Title 9, Division 7. The sound limits apply to noise generation from one property to an adjacent property. The sound level limits depend on the time of day and the receiving land use. The sound level limits are depicted in Table The sound level limits must not be exceeded on or beyond the boundaries of the property on which the noise is produced. The sound level limit between two zoning districts (different land uses) is measured at the property line between the properties. TABLE COUNTY OF IMPERIAL SOUND LEVEL LIMITS Land Use Zone Time of Day One-Hour Average Sound Level (dba) Residential (all R1) 7:00 AM to 10:00 PM 50 10:00 PM to 7:00 AM 45 Residential (all R2, R3, R4 and other residential) 7:00 AM to 10:00 PM 55 10:00 PM to 7:00 AM 50 Commercial 7:00 AM to 10:00 PM 60 10:00 PM to 7:00 AM 55 Manufacturing, all other industrial, including agricultural and extraction industry Anytime 70 General Industrial Anytime 75 SOURCE: County of Imperial 1993 Imperial County Planning & Development Services Department ESA /

8 During operation of the facility, the maximum permitted continuous sound level would not be more than 45 dba Leq, as measured at the nearest residence using the A scale and measured with a sound level meter and associated octave band analyzer. If this level is exceeded it would only be by ten percent (10%) intermittently and during daylight hours Impacts and Mitigation Measures This section describes the impact analysis relating to noise for the proposed project. It describes the methods used to determine the impacts of the project and lists the thresholds used to conclude whether an impact would be significant. Measures to mitigate (i.e., avoid, minimize, rectify, reduce, eliminate, or compensate for) significant impacts accompany each impact discussion, where applicable. Methodology Noise impacts are assessed based on a comparative analysis of the noise levels resulting from the project and the noise levels under existing conditions. Analysis of temporary construction noise effects is based on typical construction phases, equipment noise levels and attenuation of those noise levels due to distances, and any barriers between the construction activity and the sensitive receptors near the sources of construction noise. Thresholds of Significance The Imperial County CEQA Implementation Document and Imperial County Environmental Checklist identify the following criteria, as established in Appendix G of the CEQA Guidelines, to determine if a project could potentially have significant adverse noise impacts if it would: Exposure of persons to or generation of noise levels in excess of standards established in the local general plan or nose ordinances, or applicable standards of other agencies; A substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project; or For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels. The following criteria were eliminated from the EIR scope of analysis based on the findings made in the IS/NOP published for the proposed project. Please refer to Appendix A and B of this EIR for a copy of the IS/NOP and additional information regarding these issue areas. A project could have significant adverse noise impacts if it would: Exposure of persons to or generation of excessive groundborne vibration or groundborne noise levels; A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project; or Imperial County Planning & Development Services Department ESA /

9 For a project within the vicinity of a private airstrip, would the project expose people residing or working in the project area to excessive noise levels. Some guidance as to the significance of changes in ambient noise levels is provided by the 1992 findings of the Federal Interagency Committee on Noise (FICON), which assessed the annoyance effects of changes in ambient noise levels resulting from aircraft operations. The recommendations are based upon studies that relate aircraft noise levels to the percentage of persons highly annoyed by the noise. Annoyance is a summary measure of the general adverse reaction of people to noise that generates speech interference, sleep disturbance, or interference with the desire for a tranquil environment. Although the FICON recommendations were specifically developed to assess aircraft noise impacts, it has been asserted that they are applicable to all sources of noise described in terms of cumulative noise exposure metrics such as the Ldn, as shown in Table TABLE MEASURES OF SUBSTANTIAL INCREASE FOR NOISE EXPOSURE Ambient Noise Level Without Project (Ldn) Significant Impact Assumed to Occur if the Project Increases Ambient Noise Levels By: <60 db db or more db db or more >65 db db or more SOURCE: Federal Interagency Committee on Noise (FICON), The rationale for the Table criteria is that, as ambient noise levels increase, a small increase in decibel levels is sufficient to cause significant annoyance. The quieter the ambient noise level is, the more the noise can increase (in decibels) before it causes significant annoyance. Construction Noise. Construction noise would be a significant impact if noise levels would exceed Imperial County s Construction Noise Standard limit of 75 dba. Or if construction noise would not comply with the restricted construction hours of 7 AM to 7 PM Monday through Friday, 9 AM to 5 PM Saturdays, and no construction is permitted on Sundays and holidays. construction activity occurs between the hours of 8 PM and sunrise (Monday through Saturday) or anytime on Sunday. Stationary Noise. Operational noise would be a significant impact if the project resulted in an offsite noise level at a residence from a stationary non-transportation source that would exceed an exterior maximum of 50 dba during the daytime hours, or 45 dba during the nighttime hours. Traffic Noise. As described in Table above, the project would result in a significant traffic noise impact if mobile noise would result in increased noise levels of 1.5 dba Ldn or more in an ambient noise environment greater than 65 dba Ldn; or increased noise of 3 dba Ldn or more in an ambient noise environment between 60 and 65 dba Ldn; or increased noise of 5 dba Ldn or more in an ambient environment of less than 60 dba Ldn. Imperial County Planning & Development Services Department ESA /

10 Project Impacts Impact : Would construction of the proposed project expose persons to or generate noise levels in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies? Construction activity noise levels at and near the construction areas would fluctuate depending on the particular type, number, and duration of uses of various pieces of construction equipment. Construction-related material haul trips would raise ambient noise levels along haul routes, depending on the number of haul trips made and types of vehicles used. In addition, certain types of construction equipment generate impulsive noises (such as pile driving), which can be particularly disruptive. Pile driving, however, is not proposed during project construction. Table shows typical noise levels during different construction stages. Table shows typical noise levels produced by various types of construction equipment. TABLE TYPICAL CONSTRUCTION NOISE LEVELS Construction Phase Ground Clearing Excavation Foundations Erection Finishing Noise Level (dba, Leq) a a Average noise levels correspond to a distance of 50 feet from the noisiest piece of equipment associated with a given phase of construction and 200 feet from the rest of the equipment associated with that phase. SOURCE: USEPA, Noise from Construction Equipment and Operations, Building Equipment, and Home Appliances, TABLE TYPICAL NOISE LEVELS FROM CONSTRUCTION EQUIPMENT Construction Equipment Noise Level (dba, Leq at 50 feet ) Dump Truck Portable Air Compressor Concrete Mixer (Truck) Scraper Jack Hammer Dozer Paver Generator Pile Driver Backhoe SOURCE: Cunniff, Environmental Noise Pollution, Imperial County Planning & Development Services Department ESA /

11 Noise from construction activities generally attenuates at a rate of 6 to 7.5 dba per doubling distance. Based on the proposed project site layout and terrain, an attenuation of 7.5 dba will be assumed. The nearest sensitive receptor to project construction is approximately 200 feet away. Table states that excavation is 89 dba at 50 feet, if attenuated out to 200 feet, these residences would experience noise levels of about 74 dba Leq during finishing and excavation, the loudest of construction activities that would occur. Construction noise at these levels would be below Imperial County s Construction Noise Standard limit of 75 dba as depicted in Table However, construction noise is restricted to between the hours of 7 AM to 7 PM Monday through Friday, 9 AM to 5 PM Saturdays, and no construction is permitted on Sundays and holidays. The project requires a construction schedule that would exceed these hours. Heavy construction will be scheduled to occur between 6 AM and 5 PM, Monday through Friday. However, some activities may continue 24 hours per day, seven days per week. This impact would be less than significant with mitigation. Mitigation Measure : The project applicant shall incorporate the following requirements into the construction contract specifications: Equipment and trucks used for construction shall use the industry standard noise control techniques (e.g., improved mufflers, equipment redesign, use of intake silencers, ducts, engine enclosures, and acoustically-attenuating shields or shrouds, wherever feasible). Stationary noise sources shall be located as far from adjacent receptors, whenever feasible, and they shall be muffled and enclosed within temporary sheds, incorporate insulation barriers, or other measures to the extent feasible. Signs shall be posted at the construction sites that include permitted construction days and hours, a day and evening contact number for the job site, and a contact number in the event of problems. An onsite complaint and enforcement manager shall respond to and track complaints and questions related to noise. The construction contractor shall implement the use of sound blankets or sound walls along the southern portion of the Calipatria property lines located between the proposed site and the adjacent residences. Such attenuation measures could be expected to reduce noise levels by 8 to 10 dba. Impact tools (e.g., jack hammers, pavement breakers, and rock drills) used for construction shall be hydraulically or electrically powered wherever possible to avoid noise associated with compressed air exhaust from pneumatically powered tools. Where use of pneumatic tools is unavoidable, an exhaust muffler on the compressed air exhaust shall be used. External jackets on the tools themselves shall be used where feasible. Quieter procedures, such as use of drills rather than impact tools, shall be used whenever feasible. Level of Significance after Mitigation: Impacts would be less than significant. Imperial County Planning & Development Services Department ESA /

12 Impact : Would operation of the proposed project expose persons to or generate noise levels in excess of standards established in the local general plans or noise ordinances, or applicable standards of other agencies? Operational activities associated with the project that would generate noise include employee vehicle circulation and the operation of certain electrical equipment. Equipment associated with solar power fields do not create a substantial amount of noise. Operations of the Proposed Projects would not result in a permanent increase of ambient noise in their site vicinities above those that are currently occurring nor result in noise levels that exceed applicable County Code significance thresholds. In order to result in a 3 dba increase, traffic would have to double on local roadways. Operational vehicle trip increases would be minimal (approximately 18 round trips per day) and would not generate a substantial increase in noise along local roadways. As a result the Proposed Projects would not permanently increase ambient noise levels in the areas and potential impacts would be less than significant. Mitigation: None required. Impact : Would operation of the proposed project that is adjacent to an airport expose employees to excessive noise levels? The proposed site for Calipatria I solar farm site is approximately 1,900 feet northeast of Cliff Hatfield Memorial Airport. The Calipatria I solar farm site is partially located within the CNEL 65 dba noise contour projected for the airport (Imperial County, 1996) while the Midway I and Midway II solar farm sites are located well outside the airport s projected CNEL 65 dba noise contour. The proposed projects do not involve the development of noise-sensitive land uses and aircraft noise is not anticipated to negatively affect the six full time employees that will operate the Calipatria I solar farm since they will be inside the O&M building which is located outside the CNEL 65 dba noise contour. Implementation of the proposed projects would not increase the number of people exposed to excessive levels of aircraft noise. Project impacts would be less than significant. Mitigation: None required. Imperial County Planning & Development Services Department ESA /