NOISE AND VIBRATION ASSESSMENT THE SHOPS AT AUSTIN CREEK 5173 SONOMA HIGHWAY SANTA ROSA, CA

Transcription

1 ATTACHMENT 11d NOISE AND VIBRATION ASSESSMENT THE SHOPS AT AUSTIN CREEK 5173 SONOMA HIGHWAY SANTA ROSA, CA August 12, 2014 Prepared for: Mr. Bruce Codding C/O J. Kapolchok & Associates nd Street Santa Rosa, CA Prepared by: Fred M. Svinth, INCE, Assoc. AIA ILLINGWORTH & RODKIN, INC. Acoustics Air Quality 505 Petaluma Boulevard South Petaluma, CA (707) Job No.:

2 INTRODUCTION This report evaluates potential noise and vibration impacts resulting from the proposed Shops at Shops at Austin Creek retail center, located on the northwest corner of Sonoma Highway and Calistoga Road (see Figure 1). The proposed project is the development of a ±44,000 sq. ft. retail center on a ±5.32 acre property consisting of two separate parcels (APN s & 060APN ). The site is currently used commercially as the Prickett s Nursery, and is bordered by a CG zoned commercial shopping center to the east across Calistoga Road, PD zoned small lot residential land across Sonoma Highway to the South, R1-6 zoned single family residential uses to the north opposite Austin Creek, and PD zoned small lot residential uses to the west. The Setting Section of this report presents the fundamentals of environmental noise and vibration, describes regulatory criteria that are applicable in the project s assessment, and summarizes the results of the ambient noise monitoring survey. The Impacts and Mitigation Measures Section describes the significance criteria used to evaluate ST-1 LT-1 PROJECT SITE ST-2 Figure 1: Noise Measurement Locations and Project Vicinity potential project impacts, provides a discussion of each impact, and presents measures to mitigate any significant impacts. SETTING Fundamentals of Environmental Noise Noise may be defined as unwanted sound. Noise is usually objectionable because it is disturbing or annoying. The objectionable nature of sound could be caused by its pitch or its loudness. Pitch is the height or depth of a tone or sound, depending on the relative rapidity (frequency) of the vibrations by which it is produced. Higher pitched signals sound louder to humans than sounds with a lower pitch. Loudness is intensity of sound waves combined with the reception characteristics of the ear. Intensity may be compared with the height of an ocean wave in that it is a measure of the amplitude of the sound wave. 1

3 In addition to the concepts of pitch and loudness, there are several noise measurement scales which are used to describe noise in a particular location. A decibel (db) is a unit of measurement which indicates the relative amplitude of a sound. The zero on the decibel scale is based on the lowest sound level that the healthy, unimpaired human ear can detect. Sound levels in decibels are calculated on a logarithmic basis. An increase of 10 decibels represents a ten-fold increase in acoustic energy, while 20 decibels is 100 times more intense, 30 decibels is 1,000 times more intense, etc. There is a relationship between the subjective noisiness or loudness of a sound and its intensity. Each 10 decibel increase in sound level is perceived as approximately a doubling of loudness over a fairly wide range of intensities. Technical terms are defined in Table 1. There are several methods of characterizing sound. The most common in California is the A- weighted sound level or dba. This scale gives greater weight to the frequencies of sound to which the human ear is most sensitive. Representative outdoor and indoor noise levels in units of dba are shown in Table 2. Because sound levels can vary markedly over a short period of time, a method for describing either the average character of the sound or the statistical behavior of the variations must be utilized. Most commonly, environmental sounds are described in terms of an average level that has the same acoustical energy as the summation of all the time-varying events. This energy-equivalent sound/noise descriptor is called L eq. The most common averaging period is hourly, but L eq can describe any series of noise events of arbitrary duration. The scientific instrument used to measure noise is the sound level meter. Sound level meters can accurately measure environmental noise levels to within about plus or minus 1 dba. Various computer models are used to predict environmental noise levels from sources, such as roadways and airports. The accuracy of the predicted models depends upon the distance the receptor is from the noise source. Close to the noise source, the models are accurate to within about plus or minus 1 to 2 dba. Since the sensitivity to noise increases during the evening and at night -- because excessive noise interferes with the ability to sleep hour descriptors have been developed that incorporate artificial noise penalties added to quiet-time noise events. The Community Noise Equivalent Level, CNEL, is a measure of the cumulative noise exposure in a community, with a 5 db penalty added to evening (7:00 pm - 10:00 pm) and a 10 db addition to nocturnal (10:00 pm - 7:00 am) noise levels. The Day/Night Average Sound Level, DNL or L dn, is essentially the same as CNEL, with the exception that the evening time period is dropped and all occurrences during this three-hour period are grouped into the daytime period. 2

4 TABLE 1: Definitions of Acoustical Terms Used in this Report Term Decibel, db Sound Pressure Level Frequency, Hz A-Weighted Sound Level, dba Equivalent Noise Level, L eq L max, L min L 01, L 10, L 50, L 90 Day/Night Noise Level, L dn or DNL Community Noise Equivalent Level, CNEL Ambient Noise Level Definition 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. The reference pressure for air is 20. Sound pressure is the sound force per unit area, usually expressed in micro Pascals (or 20 micro Newtons per square meter), where 1 Pascal is the pressure resulting from a force of 1 Newton exerted over an area of 1 square meter. The sound pressure level is expressed in decibels as 20 times the logarithm to the base 10 of the ratio between the pressures exerted by the sound to a reference sound pressure (e.g., 20 micro Pascals). Sound pressure level is the quantity that is directly measured by a sound level meter. The number of complete pressure fluctuations per second above and below atmospheric pressure. Normal human hearing is between 20 Hz and 20,000 Hz. Infrasonic sound are below 20 Hz and Ultrasonic sounds are above 20,000 Hz. The sound pressure level in decibels as measured on a sound level meter using the A-weighting filter network. The A-weighting 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. The average A-weighted noise level during the measurement period. The maximum and minimum A-weighted noise level during the measurement period. The A-weighted noise levels that are exceeded 1%, 10%, 50%, and 90% of the time during the measurement period. The average A-weighted noise level during a 24-hour day, obtained after addition of 10 decibels to levels measured in the night between 10:00 pm and 7:00 am. The average A-weighted noise level during a 24-hour day, obtained after addition of 5 decibels in the evening from 7:00 pm to 10:00 pm and after addition of 10 decibels to sound levels measured in the night between 10:00 pm and 7:00 am. The composite of noise from all sources near and far. The normal or existing level of environmental noise at a given location. Intrusive That noise which intrudes over and above the existing ambient noise at a given location. The relative intrusiveness of a sound depends upon its amplitude, duration, frequency, and time of occurrence and tonal or informational content as well as the prevailing ambient noise level. Source: Handbook of Acoustical Measurements and Noise Control, Harris,

5 TABLE 2: Typical Noise Levels in the Environment Common Outdoor Activities Noise Level (dba) Common Indoor Activities 110 dba Rock band Jet fly-over at 1,000 feet Gas lawn mower at 3 feet 100 dba 90 dba Diesel truck at 50 feet at 50 mph Food blender at 3 feet 80 dba Garbage disposal at 3 feet Noisy urban area, daytime Gas lawn mower, 100 feet 70 dba Vacuum cleaner at 10 feet Commercial area Normal speech at 3 feet Heavy traffic at 300 feet 60 dba Large business office Quiet urban daytime 50 dba Dishwasher in next room Quiet urban nighttime 40 dba Theater, large conference room Quiet suburban nighttime 30 dba Library Quiet rural nighttime Bedroom at night, concert hall (background) 20 dba Broadcast/recording studio 10 dba 0 dba Source: Technical Noise Supplement (TeNS), Caltrans, November

6 Fundamentals of Groundborne Vibration Ground vibration consists of rapidly fluctuating motions or waves with an average motion of zero. Several different methods are typically used to quantify vibration amplitude. One is the Peak Particle Velocity (PPV) and another is the Root Mean Square (RMS) velocity. The PPV is defined as the maximum instantaneous positive or negative peak of the vibration wave. The RMS velocity is defined as the average of the squared amplitude of the signal. The PPV and RMS vibration velocity amplitudes are used to evaluate human response to vibration. In this section, a PPV descriptor with units of mm/sec or in/sec is used to evaluate construction generated vibration for building damage and human complaints. Table 3 displays the reactions of people and the effects on buildings that continuous vibration levels produce. The annoyance levels shown in Table 3 should be interpreted with care since vibration may be found to be annoying at much lower levels than those shown, depending on the level of activity or the sensitivity of the individual. To sensitive individuals, vibrations approaching the threshold of perception can be annoying. Low-level vibrations frequently cause irritating secondary vibration, such as a slight rattling of windows, doors or stacked dishes. The rattling sound can give rise to exaggerated vibration complaints, even though there is very little risk of actual structural damage. In high noise environments, which are more prevalent where groundborne vibration approaches perceptible levels, this rattling phenomenon may also be produced by loud airborne environmental noise causing induced vibration in exterior doors and windows. Construction activities can cause vibration that varies in intensity depending on several factors. The use of pile driving and vibratory compaction equipment typically generate the highest construction related ground-borne vibration levels. Because of the impulsive nature of such activities, the use of the peak particle velocity descriptor (PPV) has been routinely used to measure and assess ground-borne vibration and almost exclusively to assess the potential of vibration to induce structural damage and the degree of annoyance for humans. The two primary concerns with construction-induced vibration, the potential to damage a structure and the potential to interfere with the enjoyment of life are evaluated against different vibration limits. Studies have shown that the threshold of perception for average persons is in the range of to in/sec PPV. Human perception to vibration varies with the individual and is a function of physical setting and the type of vibration. Persons exposed to elevated ambient vibration levels such as people in an urban environment may tolerate a higher vibration level. Structural damage can be classified as cosmetic only, such as minor cracking of building elements, or may threaten the integrity of the building. Safe vibration limits that can be applied to assess the potential for damaging a structure vary by researcher and there is no general consensus as to what amount of vibration may pose a threat for structural damage to the building. Construction-induced vibration that can be detrimental to the building is very rare and has only been observed in instances where the structure is at a high state of disrepair and the construction activity occurs immediately adjacent to the structure. 5

7 TABLE 3: Reaction of People and Damage to Buildings at Various Continuous Vibration Levels Velocity Level, PPV (in/sec) Human Reaction Effect on Buildings 0.01 Barely perceptible 0.08 Distinctly perceptible Vibration unlikely to cause damage of any type to any structure Recommended upper level of the vibration to which ruins and ancient monuments should be subjected Source: Strongly perceptible Virtually no risk of damage to normal buildings 0.3 Strongly perceptible to severe 0.5 Severe - Vibrations considered unpleasant Threshold at which there is a risk of damage to older residential dwellings such as plastered walls or ceilings. Threshold at which there is a risk of damage to newer residential structures Transportation- and Construction-Induced Vibration Guidance Manual, California Department of Transportation, June Regulatory Background The State of California and the City of Santa Rosa establish guidelines, regulations, and policies designed to limit noise exposure at noise sensitive land uses. These plans and policies include: (1) the State CEQA Guidelines, Appendix G; (2) The Santa Rosa General Plan 2035; and (3) the City of Santa Rosa Municipal Code. (1) State CEQA Guidelines. The California Environmental Quality Act (CEQA) includes qualitative guidelines for determining significance of adverse environmental noise impacts. A project will typically have a significant impact if it would: a. Expose people to or generate noise levels in excess of standards established in the local general plan, noise ordinance, or applicable standards of other agencies. b. Expose people to or generate excessive groundborne vibration or groundborne noise levels. c. Result in a substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project. d. Result in a substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project. e. For projects within an area covered by an airport land use plan or within two miles of a public airport or public use airport when such an airport land use plan has not been adopted, or within the vicinity of a private airstrip, expose people residing or working in the project area to excessive aircraft noise levels. f. For a project within the vicinity of a private airstrip, expose people residing or working in the project area to excessive noise levels. 6

8 (2) Santa Rosa General Plan. The City of Santa Rosa has adopted policies and land use compatibility standards for community noise exposure in the Noise and Safety Element of the General Plan. The following policies are applicable: NS-B-3 Prevent new stationary and transportation noise sources from creating a nuisance in existing developed areas. Use a comprehensive program of noise prevention through planning and mitigation, and consider noise impacts as a crucial factor in project approval. The Land Use Compatibility Standards specify normally acceptable levels for community noise in various land use areas. The proposed uses would fall within the category designated Office Buildings, Business Commercial and Professional. The noise environment is considered Normally Acceptable up to a noise exposure level of 70 dba L dn, Conditionally Acceptable up to a noise exposure level of 77 dba L dn, and Normally Unacceptable at a noise exposure level exceeding 77 dba L dn. NS-B-4 Require new projects in the following categories to submit an acoustical study, prepared by a qualified acoustical consultant: All new projects that could generate noise whose impacts on other existing uses would be greater than those normally acceptable. NS-B-5 Pursue measures to reduce noise impacts primarily through site planning. Engineering solutions for noise mitigation, such as sound walls, are the least desirable alternatives. NS-B-6 Do not permit existing uses to generate new noises exceeding normally acceptable levels unless those noises are mitigated to acceptable levels. NS-B-10 Work with private enterprises to reduce or eliminate nuisance noise from industrial and commercial sources that impact nearby residential areas. If progress is not made within a reasonable time, the City shall issue abatement orders or take other legal measures. NS-B-14 Discourage new projects that have potential to create ambient noise levels more than 5 dba L dn above existing background, within 250 feet of sensitive receptors. (3) Santa Rosa Noise Ordinance. The City of Santa Rosa has adopted a quantitative noise ordinance in Chapter of the Municipal Code. Section regulates noise from machinery and equipment: It is unlawful for any person to operate any machinery, equipment, pump, fan, air conditioning apparatus, or similar mechanical device in any manner so as to create any noise which would cause the noise level at the property line of any property to exceed the ambient base noise level by more than five decibels. The ambient base noise levels for residential, office, commercial, and industrial areas are established in Section The applicable ambient noise level criteria are shown in Table 4; 7

9 TABLE 4:City of Santa Rosa Municipal Code Ambient Base Noise Levels Land Use Zone Daytime Level (7am to 7pm) Evening Level (7pm to 10pm) Nighttime Level (10pm to 7am) Single-Family Residential (R1 and R2) 55 dba 50 dba 45 dba Multi-Family Residential 55 dba 55 dba 50 dba Office and Commercial 60 dba 60 dba 55 dba Intensive Commercial 65 dba 65 dba 55 dba Industrial 70 dba 70 dba 70 dba Source: City of Santa Rosa, City of Santa Rosa Municipal Code The Noise Ordinance defines ambient noise as follows: Ambient noise is the all-encompassing noise associated with a given environment usually a composite of sounds from many sources near and far. For the purpose of this chapter, ambient noise level is the level obtained when the noise level is averaged over a period of 15 minutes without inclusion of noise from isolated identifiable sources at the location and time of day near that at which a comparison is to be made. Existing Noise Environment The proposed retail development is located at the intersection of Sonoma Highway and Calistoga Road in the City of Santa Rosa, an area comprised primarily of commercial, residential and open space land uses. The site where the development would is currently used commercially as the Prickett s Nursery, and is bordered by a commercial shopping center to the east across Calistoga Road, and residential uses to the south across Sonoma Highway to the north opposite Austin Creek, and to the west. The predominant noise source affecting the project site and nearby land uses is traffic on Sonoma Highway and Calistoga Road. A noise monitoring survey was performed at the site between August 13 th and 14 th, This survey consisted of one long-term noise measurement across Austin Creek near the single family residential neighborhood north of the site, a short-term noise measurement on the Hidden Creek Place west of the site, and a short-term noise measurement on Firestone Way south of the site. These measurements represent the noise environment of the nearest noise sensitive receptors to the project site. Noise levels were monitored using Larson-Davis Laboratories Model 820 Integrating Sound Level Meters fitted with precision microphones and windscreens. Noise measurement locations are shown on Figure 1. The long-term noise measurement (see LT-1, Figure 1) was conducted between 2 p.m. on August 13 th and 2 p.m. on August 14 th, 2014 on an the an existing tree at 10 feet above ground level near the project property line in the wooded area north of Austin Creek and south of Fravel Lane. Noise measurements at this location represent the current noise exposure of single family homes in this area. The trend in noise levels measured at the long term location including the energy equivalent average noise level (L eq ), maximum (L max ), minimum (L min ), and noise levels exceeded 01, 10, 50 and 90 percent of the time (indicated as L 1, L 10, L 50 and L 90 ) over 15-minute measurement periods are shown on Chart 1. The L eq noise level is typically considered the average noise level, while the L 1 is considered the intrusive level, the L 50 is considered the median noise level and the L 90 is considered the background noise level. 8

10 A review of Chart 1 indicates that daytime, evening and nighttime average (L eq ) noise levels ranged from 45 to 50 dba, 47 to 52 dba, and 41 to 50 dba, respectively, with an average daytime L eq of 67 dba, and average evening L eq of 51 dba and nighttime L eq of 46 dba. In reviewing this chart it is interesting to note an increase in background and average noise levels after 8 pm which then gradually diminish until 3am. Based on experience conducting sound level measurements in wooded and riparian areas, these nightly sound level increases are judged to be a result of insect, frog, or other natural noise sources occurring during warm summer months. The average Day-Night noise Level (L dn ) for the measurement period was 53 dba. The first short-term noise measurement (see ST-1, Figure 1) was made at the end of Hidden Creek Place west of the site. This measurement location was approximately 300 feet north of the Sonoma Highway centerline and 80 feet west of the project property line. The second short-term noise measurement (see ST-2, Figure 1) was made at the end of Firestone Way across Sonoma Highway south of the site. This measurement location was approximately 115 feet south of the Sonoma Highway centerline and 170 feet south of the project property line. Measurements at the short term locations were conducted simultaneously with the sound level meter at the long-term position to allow for the determination of the relative attenuation of traffic noise. The results of the short-term measurements relative to the simultaneously measured levels at the long-term meter indicate that noise levels are 3 to 4 dba higher at the end of Hidden Creek Place (ST-1), and that noise levels are 10 to 11 dba higher at the end of Firestone Way (ST-2) than at the long term position (LT-1). Based on these results, the average (L eq ) noise levels at this location 9

11 ST-1 are calculated to be 50 dba daytime, 54 dba evening, and 50 dba nighttime, with an average Day-Night noise Level (L dn ) of 56 dba, and those at location ST-2 are calculated to be 58 dba daytime, 62 dba evening, and 57 dba nighttime, with an L dn of 64 dba. The closest façades of the building proposed at the project site will be about 90 feet from the centerline of Sonoma Highway. Based on the results of measurements at location ST-2 and a consideration of the typical distance attenuation from traffic noise source of 3 dba be distance doubling, these closest building facades will be exposed to an L dn of 65 dba. NOISE IMPACTS AND MITIGATION MEASURES Significance Criteria Paraphrasing from Appendix G of the CEQA Guidelines, a project would normally result in significant noise impacts if noise levels generated by the project conflict with adopted environmental standards or plans, if the project would generate excessive ground-borne vibration, or if ambient noise levels at sensitive receivers would be substantially increased over a permanent, temporary, or periodic basis. The project is not located within the environs of an airport, so there is no further discussion of aircraft noise. The following criteria were used to evaluate the significance of environmental noise resulting from the project: 1) Exposure of persons to, or generation of, noise levels in excess of standards established in the local general plan or noise ordinance, or of applicable standards of other agencies. A significant noise impact would be identified if the project would expose persons to, or generate noise levels that would exceed applicable noise standards presented in the General Plan or Municipal Code. For office buildings, business commercial, and professional offices the noise exposure is considered normally acceptable up to 70 dba L dn and conditionally acceptable up to 77 dba L dn. The noise standard in the municipal code limits noise generation of machinery and equipment on the project site to 60 dba during the daytime (7 AM to 7 PM), 55 dba during the evening (7 PM to 10 PM) and 50 dba during the nighttime (10 PM to 7 AM) at existing single-family and small lot residences in the area. 2) Exposure of persons to or generation of excessive groundborne vibration or groundborne noise levels. A significant impact would be identified if the project would expose persons to excessive vibration levels. During construction, ground-borne vibration levels exceeding 0.30 in/sec PPV (peak particle velocity) would result in a significant impact as such levels would have the potential to result in damage to older residential buildings, and vibration levels exceeding 0.2 in/sec PPV would result in a significant impact as such levels would have the potential to result in human annoyance. 3) A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project. A significant impact would be identified if traffic generated by the project would substantially increase noise levels at sensitive receivers in the vicinity. A substantial increase to noise levels would occur if the project resulted in an increase of 3 dba L dn or more at noise-sensitive land uses where noise levels already exceed 60 dba L dn, or an increase of 5 dba L dn or more at noise-sensitive land uses where noise levels are below 60 dba L dn. 10

12 4) A substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project. Significant noise impacts would result from construction if noise levels were sufficiently high to interfere with speech, sleep, or normal residential activities. Construction-related hourly average noise levels received at noisesensitive land uses exceeding 60 dba L eq(hr), and at least 5 dba above the ambient, would be considered significant if the noise-generating construction affected the noise environment at a sensitive receiver for more than one year. Impact 1: Noise and Land Use Compatibility. Noise levels at the project site are below the City of Santa Rosa s noise and land use compatibility guidelines for retail/commercial development. This is a less-than-significant impact. The project site is adjacent to Sonoma Highway and Calistoga Road. The calculated noise level at the setback of the building façade closest to Sonoma Highway is 65 dba L dn. Noise levels on the remainder of the site are expected to be lower. The project s design orients outdoor circulation areas away from the adjacent roadways and toward the parking lot area (See Figure 2). The noise exposure for the project site is, therefore, less than 70 dba L dn and therefore is considered Normally Acceptable for the proposed retail/commercial development. Mitigation 1: None Required. Building 2 Building 1 Building 3 8-foot wall at Loading Dock 6-foot wall at Entry Drive Building 4 Figure 2: Project Site Plan 11

13 Impact 2: Consistency with Local Noise Standards. Operation and use of the proposed uses of the project site may exceed established noise standards and criteria at adjacent residential uses without the incorporation of mitigation. This is a lessthan-significant impact with incorporation of mitigation. Project Operational Noise The existing noise levels at the nearest residences are primarily due to local and distant traffic and local residential noise sources. As discussed previously, ambient noise levels at residences nearest the project site range for an L dn of 53 dba at the single family residential neighborhood north of the site, to an L dn of 56 dba at the end of Hidden Creek Place, and an L dn of 64 dba at the end of Firestone Way. The proposed project would generate noise and introduce new noise sources into the existing noise environment. Operational noise sources would include; 1. Truck deliveries and trash collection at the Building 3 loading dock, 2. Truck deliveries at other uses on the site 3. Parking lot activity, 4. Drive through window activity at Building 4, 5. Trash collection at the interior of the site, and 6. Building mechanical equipment. The Noise Element of the Santa Rosa General Plan s primary goal (Goal NS-B) is to maintain an acceptable community noise level to protect the health and comfort of people living, working, and/or visiting in Santa Rosa, while maintaining a visually-appealing community. Policy NS- B-3 prevents new stationary noise sources from creating a nuisance in existing developed areas. Noise impacts resulting from new projects must be evaluated prior to project approval. The City of Santa Rosa Municipal Code states that It is unlawful for any person to operate any machinery, equipment, pump, fan, air-conditioning apparatus or similar mechanical device in any manner so as to create any noise which would cause the noise level at the property line of any property to exceed the ambient base noise level by more than five decibels. Using the municipal code limits, noise generation from mechanical equipment on the project site would be limited to 60 dba during the daytime (7 AM to 7 PM), 55 dba during the evening (7 PM to 10 PM) and 50 dba during the nighttime (10 PM to 7 AM) at existing single-family and small lot residences in the area. The City Code does not define the acoustical time descriptor such as L eq (the average noise level) or L max (the maximum instantaneous noise level) that is associated with the above limits. A reasonable interpretation of the City Code would identify the ambient base noise level criteria as an average or median noise level (L eq /L 50 ). In many Bay Area communities, the average base noise level limit is adjusted upwards in 5 dba increments to account for shorter duration noise events. For example, prior to the recent General Plan Update, Sonoma County limited median noise levels (noise level exceeded 30 minutes or more in an hour) to 50 dba L 50 daytime and 45 dba L 50 at night and maximum instantaneous noise levels to 70 dba L max during the day and 65 dba L max at night. Following this approach, this analysis also uses 70 dba L max during the day, 65 dba L max during the evening, and 60 dba L max at night for transient, non-equipment related, noise sources, such as truck and automobile operations, at the residential uses in the site vicinity. 12

14 1. Truck deliveries and trash collection at the Building 3 loading dock Noise measurements made by I&R at similar stores indicate that the highest noise levels generated by the proposed project would typically result from delivery and garbage trucks circulating to and from this docking area. Trucks would access the site from Sonoma Highway or Calistoga Road and back down a driveway to the loading dock and trash collection area. Based on review of the project site plan the Building 3 loading dock is as close as 30 feet from the nearest residential property line to the west. Truck trips would be subject to store volume and seasonal variations. Based on experience with other retail developments we expect no more than one delivery a day, with from one to seven deliveries per week. Heavy truck deliveries typically generate maximum instantaneous noise levels of 70 to 75 dba L max at a distance of 50 feet. Smaller delivery trucks typically generate maximum noise levels of 60 to 65 dba L max at the same distance. Commercial trash collection trucks typically generate noise levels of 70 to 75 dba L max at 50 feet. Low speed truck noise results from a combination of engine, exhaust, and tire noise as well as the intermittent sounds of back-up alarms and releases of compressed air associated with truck/trailer air-brakes. The noise level of backup alarms can vary depending on the type and directivity of the sound, but maximum noise levels are typically in the range of 65 to 75 dba L max at a distance of 50 feet. Noise generated by loading dock activities and slow moving trucks increase or decrease at a rate of about 6 db per halving or doubling of distance between the noise source and receiver, respectively. Accounting for the effects of distance, maximum instantaneous noise levels generated by trucks and back up alarms as close as 30 feet from the nearest residential property to the west are calculated to be between 64 to 74 dba L max. This level of noise would exceed the transient, non-equipment related daytime, evening and nighttime noise criteria established above (respectively, 70 dba L max, 65 dba L max, and 60 dba L max ). 2. Truck deliveries at other uses on the site Heavy truck deliveries to other areas of the project site would also be expected to generate maximum instantaneous noise levels of 70 to 75 dba L max at a distance of 50 feet. Smaller delivery trucks would also expected to generate maximum noise levels of 60 to 65 dba L max at the same distance. All potential stores delivery areas are over 300 feet from the nearest residential property lines. At this distance truck delivery noise would be between be between 50 to 60 dba L max. This level of noise would comply with the transient, non-equipment related, daytime, evening and nighttime noise criteria (established above) and no mitigation for such activities would be needed. 3. Parking Lot Activity The primary parking lot noise at the site would be from patrons parking and vehicles circulating in the central portions of the site, with some vehicular passby noise in the southern, Sonoma Highway entrance. Noise from such activities is typically generated by circulating vehicles, engine starts, door slams, and the sound of human voices. The maximum (L max ) sound of a passing car at 15 mph typically range from 55 dba to 65 dba at 25 feet. The noise of an engine start is similar. Door slams and patron voices create noise levels lower than engine starts. Based on a review of the project site plan (see Figure 2), vehicles will pass within about 75 feet of the residential property lines to the west when using the Sonoma Highway entry. Other vehicle movements and parking activities would be further from these and other surrounding residences. Based on this distance, the source levels for passing vehicles, and 13

15 typical distance attenuation relationship of 3 dba per doubling of distance for vehicular traffic, the vehicular passby noise on the southern, Sonoma Highway entrance is expected to be between 50 to 60 dba L max at the rear property lines of the homes on Hidden Creek Place. This level of noise would comply with the transient, non-equipment related daytime, evening and nighttime noise criteria established above (respectively, 70 dba L max, 65 dba L max, and 60 dba L max ). The parking area surface of similar shopping centers are cleaned periodically (about once per week) using small mechanical parking lot sweepers/vacuum trucks. Based on measurements taken at other stores, it was determined that at a distance of 50 feet, the noise of the parking lot sweeper/vacuum truck was 75 dba L max. Sweepers could operate as close as 150 feet from the nearest residences to the west. The operation of a sweeper truck would generate maximum noise levels up to about 65 dba L max to the west, similar to other on-site truck circulation discussed above. This level of noise would comply with the transient, non-equipment related daytime and evening noise criteria established above (respectively, 70 dba L max, 65 dba L max ) but exceed the nighttime noise criteria (60 dba L max ). 4. Drive-through Window Activity at Building 4 Based on measurements conducted at other drive-through type uses, the audio system and patron voices are expected to produce sound levels of 75 dba at 3 feet from the ordering unit. The use of the drive-through will also result in noise from vehicles idling while waiting to enter and within the drive-through and vehicles leaving the drive through and circulating through the parking area. Idling vehicles typically produce noise levels of between 59 and 64 dba at 15 feet with the noise produced by idling tending to mask the vocal content of the drive-through speaker. Based on a review of the project site plan and vicinity maps, the drive through window will be over 200 feet from the closest residential uses. Sound levels from the audio system and patron voices would be below 40 dba and sound levels from idling vehicles would be below 45 dba at this distance. This level of noise would comply with the transient, nonequipment related daytime, evening and nighttime noise criteria established above (respectively, 70 dba L max, 65 dba L max, and 60 dba L max ). 5. Trash and recycling collection at the interior of the site As discussed above Commercial trash collection trucks typically generate noise levels of 70 to 75 dba L max at 50 feet. The interior Trash and Recycling area is located over 300 feet from the nearest residential property line. Accounting for the effects of distance attenuation, maximum instantaneous noise levels generated by this activity are calculated to be 55 to 60 dba L max. This level of noise would comply with the transient, non-equipment related daytime, evening and nighttime noise criteria established above (respectively, 70 dba L max, 65 dba L max, and 60 dba L max ). 6. Building Mechanical Equipment Mechanical equipment associated with the development will likely include Heating, Ventilation, and Air Conditioning (HVAC) equipment to be located on the rooftops or in attics of the buildings. Noise generated by rooftop/attic mounted mechanical equipment varies significantly depending upon the equipment type and size. The precise noise impacts of project mechanical equipment cannot be determined without detailed system design specifications regarding location, type, size, capacity, etc., details which are typically provided during later phases of the project design and development review along with other more detailed project engineering specifications. However, based on noise measurements 14

16 made at other commercial centers, mechanical systems noise levels are typically 70 to 80 dba at 3 feet in the open environment. Considering distance attenuation, and no attenuation from a the roof edge or parapet wall, the sound level at a position five feet above ground level at the closest residential property line to the west would be expected to range from 45 to 55 dba. This level of noise would comply with the daytime and evening noise ordinance limits of 60 dba L eq and 55 dba L eq for mechanical equipment, but may exceed the nighttime noise criteria of 50 dba L eq. Mitigation 2: Project Operational Noise The following measures are recommended to allow operations at the project site to comply with the transient, non-equipment related daytime and evening noise criteria established in this report at the adjacent residential uses; A. Nighttime (10 pm to 7 am) deliveries should be prohibited at the Building 3 loading dock B. A noise barrier with to a height of 8 feet above the grade of the loading dock should be built in the footprint of indicated screen wall around the Building 3 loading dock as shown in Figure 2. C. To allow for nighttime parking lot sweepers/vacuum truck cleaning a noise barrier with to a height of 6 feet above grade should be built along the Sonoma Highway entry drive as shown in Figure 2. To be effective as a noise barrier, these walls should be built without cracks or gaps in the face or large or continuous gaps at the base and have a minimum surface weight of 3.0 lbs. per sq. ft. Acceptable materials include, but are not limited to, masonry block and pre-cast concrete panels. Wood may also be used. For a wood wall to meet these requirements we typically recommend that a homogenous sheet material, such as 3/4" plywood, be used as a backing for typical 1" thick (nominal) wood fence slats. Using the plywood ensures the continued effectiveness of the barrier with age, since wood slats alone have a tendency to warp and separate with age allowing gaps to form and the barrier effect of the wall to diminish. A variety of other materials may be used for the barrier wall as long as the above specifications for noise attenuation are met. D. Rooftop mechanical equipment should be located behind noise barrier parapet walls capable of blocking the line of sight from surrounding residential uses to the top of the equipment by a minimum of one foot. During final project design, the locations and specification of all exterior mechanical equipment should be reviewed by a qualified acoustical professional to ensure that operational noise does not exceed the City s Noise Ordinance Limits at the adjacent residential properties. Impact 3: Exposure to Excessive Groundborne Vibration. Construction related vibration would not be excessive at nearby land uses. Table 5 presents typical vibration levels that could be expected from construction equipment at a distance of 25 feet. Pile driving would not be required for this project. Project construction activities such as drilling, the use of jackhammers, rock drills and other high-power or vibratory tools, and rolling stock equipment (tracked vehicles, compactors, etc.) may generate substantial 15

17 vibration in the immediate vicinity. Erection of the building structure is not anticipated to be a source of substantial vibration with the exception of sporadic events such as dropping of heavy objects, which should be avoided to the extent possible. Jackhammers typically generate vibration levels of in/sec PPV and drilling typically generates vibration levels of 0.09 in/sec PPV at a distance of 25 feet. Vibration levels would vary depending on soil conditions, construction methods, and equipment used. At the nearest residential land uses, typical construction activities would cause vibration levels of 0.08 in/sec PPV or less, below the significance thresholds for annoyance and building damage. TABLE 5: Vibration Source Levels for Construction Equipment 1 Equipment PPV at 25 ft. (in/sec) Approximate L v at 25 ft. (VdB) Pile Driver (Impact) upper range (N/A) 112 typical (N/A) 104 Pile Driver (Sonic) upper range (N/A) 105 typical (N/A) 93 Clam shovel drop Hydromill (slurry wall) in soil in rock Vibratory Roller Hoe Ram Large bulldozer Caisson drilling Loaded trucks Jackhammer Small bulldozer Impact 4: Construction Noise: The project site is bordered by residential uses to the west, north and south. Noise generated by construction activities at the site would not be expected to adversely affect adjacent land uses provided standard construction noise controls are implemented at the site and the cumulative duration of significant noise-producing activities is limited to one year or less. This is a lessthan-significant impact with the incorporation of mitigation. Construction activities generate considerable amounts of noise. Construction-related noise levels are normally highest during the demolition phase and during the construction of project infrastructure. These phases of construction require heavy equipment that normally generates the highest noise levels over extended periods of time. Typical hourly average construction generated noise levels are about 81 dba to 88 dba measured at a distance of 50 feet from the center of the site during busy construction periods (e.g., earth moving equipment, impact tools, 1 Transit Noise and Vibration Impact Assessment, United States Department of Transportation, Office of Planning and Environment, Federal Transit Administration, May

18 etc.). Construction-related noise levels are normally less during building erection, finishing, and landscaping phases. There would be variations in construction noise levels on a day-to-day basis depending on the actual activities occurring at the site. Construction generated noise levels drop off at a rate of about 6 dba per doubling of distance between the source and receptor. The nearest existing residential receivers are about 80 feet from the project site. Hourly average noise levels would range from 77 dba to 84 dba during the busiest construction periods along the westernmost property line of the site. Shielding by barriers or buildings would provide an additional 5 to 10 decibels of attenuation at distant receptors. Noise impacts resulting from construction depend on the noise generated by various pieces of construction equipment, the timing and duration of noise generating activities, and the distance between construction noise sources and noise sensitive receptors. Construction noise impacts primarily occur when construction activities occur during noise-sensitive times of the day (early morning, evening, or nighttime hours), the construction occurs in areas immediately adjoining noise sensitive land uses, or when construction durations last over extended periods of time. Where noise from construction activities exceeds 60 dba L eq and exceeds the ambient noise environment by at least 5 dba L eq at noise-sensitive uses in the project vicinity for a period greater than one year, the impact would be considered significant. Demolition, grading, and the construction of project infrastructure would be completed first. The project buildings would then be constructed. As construction moves away from noise-sensitive receptors noise levels generated by heavy construction will be lower. Noise generated by demolition, grading, infrastructure improvements and the construction of units nearest the westernmost portion of the project site would not be expected to exceed ambient noise levels at receivers to the west, north, or south by more than 5 dba L eq for a period greater than one year. Significant noise impacts do not normally occur when standard construction noise control measures are enforced at the project site and when the duration of the noise generating construction period at a particular receiver or group of receivers is limited to one construction season (typically one year) or less. Construction noises associated with projects of this type are disturbances that are necessary for the construction or repair of buildings and structures in urban areas. Reasonable regulation of the hours of construction, as well as regulation of the arrival and operation of heavy equipment and the delivery of construction materials, are necessary to protect the health and safety of persons, promote the general welfare of the community, and maintain the quality of life. The following standard controls are assumed to be included in the project: Noise-generating activities at the construction site or in areas adjacent to the construction site associated with the project in any way should be restricted to the hours of 7:00 a.m. to 6:00 p.m., Monday through Friday, and 8:00 a.m. to 5:00 p.m. on Saturdays. No construction activities should occur Sundays or holidays. Equip all internal combustion engine driven equipment with intake and exhaust mufflers that are in good condition and appropriate for the equipment. Locate stationary noise generating equipment as far as possible from sensitive receptors when sensitive receptors adjoin or are near a construction project area. 17

19 Utilize "quiet" air compressors and other stationery noise sources where technology exists. The contractor shall prepare a detailed construction plan identifying the schedule for major noise-generating construction activities which will be distributed in a notice sent to the neighbors of the project site. Designate a "disturbance coordinator" who would be responsible for responding to any local complaints about construction noise. The disturbance coordinator will determine the cause of the noise complaint (e.g., starting too early, bad muffler, etc.) and will require that reasonable measures warranted to correct the problem be implemented. Conspicuously post a telephone number for the disturbance coordinator at the construction site and include it in the notice sent to neighbors regarding the construction schedule. With the incorporation of these standards measures, the noise impact resulting from project construction would be considered less-than-significant. Mitigation Measure 4: No additional measures are required. 18