NORTH GILROY NEIGHBORHOOD DISTRICTS URBAN SERVICE AREA AMENDMENT EIR NOISE AND VIBRATION ASSESSMENT GILROY, CALIFORNIA

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1 NORTH GILROY NEIGHBORHOOD DISTRICTS URBAN SERVICE AREA AMENDMENT EIR NOISE AND VIBRATION ASSESSMENT GILROY, CALIFORNIA May 14, 2015 Prepared for: Richard James, AICP Principal Planner EMC Planning Group 301 Lighthouse Avenue, Suite C Monterey, California Prepared by: Jordan L. Roberts Michael S. Thill ILLINGWORTH & RODKIN, INC. Acoustics Air Quality 1 Willowbrook Court, Suite 120 Petaluma, CA (707) Job No

2 INTRODUCTION This report evaluates the potential significance of noise impacts that could result from the North Gilroy Neighborhood Districts (NGND) Urban Service Area (USA) Amendment (the project), including the noise and land use compatibility of proposed land use changes, as well as the potential for project-generated temporary, periodic, or permanent noise level increases at nearby sensitive receptors. The Amendment would facilitate single-family and high-density residential units, commercial space, a middle school, and an elementary school on approximately 721 acres, the majority of which would be north of the existing Gilroy city limit. The entirety of the NGND site is currently located outside the USA and the project proposes to amend the USA to include the NGND. The Setting section of this assessment presents the fundamentals of environmental noise, describes regulatory criteria that would be applicable to the project, and summarizes the results of a noise monitoring survey made in the vicinity of the NGND. The Impact and Mitigation Measures section describes the significance criteria used to evaluate impacts from the Amendment, provides a discussion of the project, and presents mitigation measures necessary to provide a compatible plan in relation to surrounding noise sources and sensitive land uses. 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. 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 (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- 1

3 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 (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 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 of Acoustical Terms Used in this Report 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 micro Pascals. 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. 3

5 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,

6 TABLE 2 Typical Noise Levels in the Environment Common Outdoor Activities Noise Level (dba) Common Indoor Activities 110 dba Rock band concert Jet fly-over at 1,000 feet Locomotive horn at 100 feet 100 dba Gas lawn mower at 3 feet 90 dba Loud stereo Diesel truck at 50 feet at 50 mph Food blender Noisy urban area, daytime 80 dba Garbage disposal Gas lawn mower, 30 feet 70 dba Vacuum cleaner Commercial area Heavy traffic at 300 feet 60 dba Normal speech face to face 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 Threshold of hearing 10 dba Source: Technical Noise Supplement (TeNS), Caltrans, September

7 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 generates the highest construction related groundborne vibration levels. Because of the impulsive nature of such activities, the use of the PPV descriptor has been routinely used to measure and assess groundborne 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. 6

8 TABLE 3 Reaction of People and Damage to Buildings From Continuous or Frequent Intermittent Vibration Levels Velocity Level, PPV (in/sec) Human Reaction Effect on Buildings 0.01 Barely perceptible No effect Distinctly perceptible 0.08 Distinctly perceptible to strongly perceptible 0.1 Strongly perceptible 0.3 Strongly perceptible to severe 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. Virtually no risk of damage to normal buildings. 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. Severe - Vibrations 0.5 considered unpleasant Source: Transportation and Construction Vibration Guidance Manual, California Department of Transportation, September Rail operations are potential sources of substantial groundborne vibration depending on distance, the type and the speed of trains, and the type of railroad track. People's response to groundborne vibration has been correlated best with the velocity of the ground. The velocity of the ground is expressed on the decibel scale. The reference velocity is 1 x 10-6 in/sec RMS, which equals 0 VdB, and 1 in/sec equals 120 VdB. Although not a universally accepted notation, the abbreviation "VdB" is used in this document for vibration decibels to reduce the potential for confusion with sound decibels. Vibration levels below 65 VdB are below the threshold for human perception. Typical background vibration levels in residential areas are usually 50 VdB or lower, well below the threshold of perception for most humans. Perceptible vibration levels inside residences are attributed to the operation of heating and air conditioning systems, door slams and foot traffic. Construction activities, train operations, and street traffic are some of the most common external sources of vibration that can be perceptible inside residences. The U.S. Department of Transportation (DOT), Federal Transit Administration (FTA) has developed vibration limits that can be used to evaluate human annoyance to groundborne vibration. These criteria are primarily based on experience with passenger train operations, such as rapid transit and commuter rail systems. The main difference between passenger and freight operations is the time duration of individual events; a passenger train lasts a few seconds whereas a long freight train may last several minutes, depending on speed and length. Table 4 summarizes the Federal Transit Administration Groundborne Vibration Impact Criteria. 7

9 TABLE 4 Land Use Category FTA Groundborne Vibration Impact Criteria Impact Levels Category 1: Buildings where vibration would interfere with interior operations. Frequent Events 1 (VdB re 1 micro-inch /sec) Occasional Events 2 Infrequent Events 3 65 VdB 4 65 VdB 4 65 VdB 4 Category 2: Residences and buildings where people normally sleep. 72 VdB 75 VdB 80 VdB Category 3: Institutional land uses with primarily daytime use. 75 VdB 78 VdB 83 VdB Source: US Department of Transportation Federal Transit Administration 2006 Notes: 1. "Frequent Events" is defined as more than 70 vibration events per day. Most rapid transit projects fall into this category. 2. "Occasional Events" is defined as between 30 and 70 vibration events of the same source per day. Most commuter trunk lines have this many operations. 3. "Infrequent Events" is defined as fewer than 30 vibration events per day. This category includes most commuter rail systems. 4. This limit is based on levels that are acceptable for most moderately sensitive equipment such as optical microscopes. Regulatory Background The proposed project would be subject to noise-related plans and policies established by the State of California, Santa Clara County, and the City of Gilroy. Applicable planning documents include: (1) Appendix G of the California Environmental Quality Act (CEQA) Guidelines, (2) Santa Clara County Airport Land Use Commission (ALUC), (3) the City of Gilroy General Plan, and (4) the City of Gilroy Zoning Ordinance. The plans and policies contained within these documents form the basis of the significance criteria used to assess project impacts and are implemented during the environmental review process to limit noise exposure at existing and proposed noise sensitive land uses. State CEQA Guidelines. The CEQA contains guidelines to evaluate the significance of effects of environmental noise attributable to a proposed project. CEQA asks the following applicable questions. Would the project result in: Exposure of persons to or generation of noise levels in excess of standards established in the local General Plan or Noise Ordinance, or applicable standards of other agencies? Exposure of persons to or generation of excessive groundborne vibration or groundborne noise levels? A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without 8 the project?

10 A substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project? 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, exposure of people residing or working in the project area to excessive noise levels? For a project within the vicinity of a private airstrip, exposure of people residing or working in the project area to excessive noise levels? CEQA does not define what noise level increase would be considered substantial. Typically, project-generated noise level increases of 3 dba L dn or greater would be considered significant where exterior noise levels would exceed the normally acceptable noise level standard (60 dba L dn ). Where noise levels would remain at or below the normally acceptable noise level standard with the project, noise level increases of 5 dba L dn or greater would be considered significant. Santa Clara County Airport Land Use Commission (ALUC) Airport Land Use Plan. The Santa Clara County ALUC prepares an Airport Land Use Plan that provides for orderly growth of the area surrounding each public airport in Santa Clara County (Moffett Federal Airfield, San Jose International Airport, Palo Alto Airport, Reid-Hillview Airport, and South County Airport). The Plan is intended to minimize the public s exposure to excessive noise and safety hazards. The ALUC has established provisions for regulating land use, building height, safety and noise insulation within these areas that are adjacent to each of the airports ( referral boundaries ). The ALUC also reviews the general and specific plans prepared by local agencies (including Gilroy) for consistency with the ALUC plan. Recommendations made by the ALUC are advisory in nature to the local jurisdictions, not mandatory. City of Gilroy Noise Element. The noise-related goal of the City s General Plan is the, Protection of Gilroy residents from exposure to excessive noise and its effects through appropriate mitigation measures and responsive land use planning, especially in regard to noise-sensitive land uses such as schools, hospitals, and housing for seniors. The following policies, applicable to the development of the site, are set forth in the General Plan to facilitate this goal: Noise and Land Use. Establish a physical development pattern that is compatible with the noise environment of Gilroy, ensuring that residential neighborhoods and park areas are the quietest areas in the community Maximum Permissible Noise Levels. Ensure that outdoor and indoor noise levels are within the maximum permitted levels (see Table 5). Prohibit further development in areas where noise levels currently exceed these standards or where such development will cause levels to exceed the permitted maximum. 9

11 TABLE 5 City of Gilroy Maximum Permitted Outdoor and Indoor Noise Levels Land Use Category Maximum Outdoor L dn (dba) Maximum Indoor L dn (dba) Residential Commercial Industrial 76 see note 2 1 The Outdoor sound levels for residential properties shall be held to 60-dBA, or a maximum of 70-dBA if ALL of the following FINDINGS can be made: That potential noise levels, exceeding the 60 dba standard, are generally limited to less than 10% of the entire project site; That reasonably accepted sound attenuation measures have been incorporated in the project design; That potential noise levels are part of the developer s disclosure to future residents; That interior noise limits established by the General Plan are strictly maintained; and Potential noise levels will not jeopardize the health, safety, and general welfare of the public. 2 The indoor standards for industrial land uses have been set by the Occupational Safety and Health Administration. The maximum level to be exceeded no more than 10 percent of the time (L 10 ) is 65 dba, while the maximum level to be exceeded no more than 50 percent of the time (L 50 ) is 60 dba. Source: Gilroy General Plan, June 2002, as amended through Resolution No Buffering Standards. Enforce stringent buffering standards to protect residents from freeway, expressway, highway, and industrial noise. Use open land as a buffer between residential areas and highways or industrial areas wherever possible Acoustical Design. Consider the acoustical design of projects in the development review process to reduce noise to an acceptable level. Ensure that noise mitigation features are designed and implemented in an aesthetically pleasing and consistent manner Earth Berms. Require landscaped earth berms as an alternative to soundwalls where feasible to buffer noise along major thoroughfares adjacent to residential areas. Where an earth berm is not feasible, an alternative design approach [that may include a masonry wall screened with drought tolerant, low maintenance landscaping] should be explored that is sensitive to the natural and man-made environment Interagency Coordination. Coordinate with other agencies in the region in noise abatement measures Public Input. Provide opportunities for public input on noise issues and publicize the existence of avenues by which citizen noise problems can be measured and mitigated. City of Gilroy Zoning Ordinance. The City s zoning ordinance (Chapter 30, Section 41.31) contains quantitative noise limits for noise sources within the City of Gilroy based on the land use of the property receiving the noise. The noise ordinance establishes acceptable exterior noise levels and exemptions from the ordinance for special activities, such as emergency work and refuse and recycling collection. Special noise limits are also established for certain noisegenerating activities. The City s zoning ordinance (Chapter 30, Section 41.31) reads as follows: 10

12 Section Specific Provisions Noise It shall be unlawful to generate noise within the City limits that exceeds the limits established in this section of the Zoning Ordinance. (a) Definitions: (1) Decibel (dba): A unit measuring the amplitude of sound or noise, weighted to the range of human hearing (A-weighting scale on a sound level meter). (2) Noise Level: Measurement of sound in decibels (dba) obtained by using a sound level meter at slow response. (3) Sound Level Meter: An instrument comprised of a microphone, an amplifier, an output meter, and frequency weighing networks, used for measuring sound levels in decibel (dba) units. (4) L 10 : During a noise measurement interval, the noise being measured may not exceed the limit more than ten percent (10%) of the time. (b) Maximum outdoor noise levels: Residential noise impacting residential property Fixed source outdoor mechanical equipment (i.e. pool, spa, air conditioning equipment, etc ) - Max. 70 dba [L 10 ] measured at the property line (mechanical equipment installed after 7/1/07). The outside use of power tools, and yard & landscaping equipment, etc (including home garage vehicle repairs) - Limited to the hours of 7:00 am to 10:00 pm. Prohibited use between the hours of 10:00 pm & 7:00 am. ALSO SEE: Municipal Code Section also applies: " any loud boisterous, irritating, penetrating, or unusual noise which disrupts another in any residence...between the hours of 10:00 pm and 7:00 am of any day," is prohibited. 1. Permitted noise levels in outdoor spaces if ALL of the following findings can be made: (a) That potential noise levels exceeding the General Plan standard are generally limited to less than ten percent of the entire site; (b) That reasonably accepted sound attenuation measures have been incorporated into the project design; (c) That potential noise levels are part of the developer's disclosure to 11

13 Vibration future residents; (d) That interior noise limits established by the General Plan are strictly maintained; and (e) Potential noise levels will not jeopardize the health, safety, and general welfare of the public. Commercial & Industrial noise impacting residential property Fixed source mechanical equipment - Maximum of 70 dba [L 10 ] measured at the residential property line. Power tools & yard equipment (outside use) - Limited to the hours of 7:00 am to 10:00 pm (same as the residential standard, with maximum of 70 dba [L 10 ] measured at the residential property line. Prohibited between the hours of 10:00 pm & 7:00 am. Power tools & equipment (indoor use) - Maximum of 70 dba [L 10 ] (measured at the residential property line. ALSO SEE: Municipal Code Section also applies: " any loud boisterous, irritating, penetrating, or unusual noise which disrupts another in any residence...between the hours of 10:00 p.m. and 7:00 a.m. of any day," is prohibited. (c) Exceptions to the exterior noise limits listed in subsection (b) above: 1. Persons, equipment, vehicles, alarms, or sirens utilized in essential activities necessary to preserve, protect, or save lives or property from danger, loss, or harm; 2. Refuse & recycling collection vehicles when operating between the hours of 5:00 am and 6:00 pm; 3. Special events operating in compliance with an approved Special Events Permit; and 4. City approved activities on public properties. The City of Gilroy has not identified quantifiable vibration limits that can be used to evaluate the compatibility of land uses with vibration levels experienced at a development site. The guidance provided by Caltrans for construction related vibration, and the FTA for ground vibration from transportation sources, discussed above, are used to establish significance thresholds for this assessment. 12

14 Existing Noise Environment The NGND is comprised of 88 land use parcels for an approximate total area of 721 acres. The project area is bordered by Fitzgerald Avenue to the north, Monterey Road to the east, the existing Gilroy city limit including multiple residential neighborhoods and agricultural land-uses to the south, and Santa Teresa Boulevard to the west. The primary sources of noise affecting the area are vehicular traffic along major roadways, including Monterey Road, Santa Teresa Boulevard, Fitzgerald Avenue, and Day Road. Intermittent railroad operations along the Union Pacific Railroad (UPRR), agricultural equipment noise, local roadway traffic, and industrial activities are also noise sources throughout the planning area. The UPRR main-line running north-south adjacent to Monterey Road carries both Caltrain and freight train traffic. According to the Caltrain weekday timetable, approximately 6 trains per day run to Gilroy, the southernmost end of the passenger train service. No freight trains were observed during field measurements, but based on noise measurements conducted adjacent to the rail line, it is estimated that approximately 4 to 8 freight trains pass through Gilroy per day. A noise monitoring survey was conducted from January 22, 2015 to January 27, 2015 to quantify ambient noise levels in the planning area. The noise monitoring survey consisted of four longterm (120-hour) noise measurements (LT-1 through LT-4) and six short-term (10-minute) noise measurements (ST-1 through ST-6). All noise measurements were made with Larson & Davis Model 820 Type 1 Sound Level Meters. The meters at long-term noise measurement locations were placed in lock boxes with windscreens affixed to the microphones on the exterior of the boxes, which were tethered to trees or utility poles ranging from 12 to 14 feet above ground. The meters at short-term measurement locations were placed on tripods at 5 feet above ground. Figure 1 shows the approximate locations of noise measurements made during the recent noise monitoring survey and additional locations where noise levels were measured by I&R in December 2013 for the Gilroy General Plan Update Project. The sites LT-1, LT-2, LT-3, and LT-4 were chosen to quantify noise levels along Fitzgerald Avenue, Monterey Road/UPRR corridor, Day Road, and Santa Teresa Boulevard, respectively. Short-term measurement sites were selected to measure ambient noise levels in areas away from the primary traffic noise sources in the project area. Table 6 summarizes the measured noise level data. Since long-term noise measurement data included minute intervals, overall levels for each metric will vary. For instance, wind may be significantly strong during some intervals and minimal during others, explaining a range in the L 90 metric. Peak-hour traffic volumes during one interval and off-peak traffic volumes during another interval could explain the variation in L 50 and L eq metrics. One loud event such as a motorcycle pass-by or a train horn could occur during one interval but not another, resulting in a range of L 1 noise levels. Due to the fluctuating nature of acoustic environments, noise levels will vary day-to-day, explaining the range of L dn levels, which were calculated from five 24-hour periods. Figures in the Appendix to this report show the daily variation in noise levels at LT-1, LT-2, LT-3, and LT-4. Along the Monterey Road/UPRR corridor, vehicular traffic on the roadway and trains on the UPRR tracks are both significant contributors to the L dn. The variation in nighttime trains was the primary cause of the relatively large range in noise levels along this corridor. Agricultural 13

15 operations near the sound level meter may also have contributed to noise levels. FIGURE 1 Noise Measurement Locations 14

16 TABLE 6 Summary of Noise Measurements Measured Noise Levels, dba Primary Measurement Location L eq L 1 L 50 L 90 L dn Noise Source LT-1: 60 feet from center of Traffic on Fitzgerald Avenue Fitzgerald (1/22/2015 to 1/27/2015, Avenue. daytime hours.) LT-2: 65 feet from center of Monterey Road. (1/22/2015 to 1/27/2015, daytime hours.) LT-3: 20 feet from center of Day Road. (1/22/2015 to 1/27/2015, daytime hours.) LT-4: 50 feet from center of Santa Teresa Boulevard. (1/22/2015 to 1/27/2015, daytime hours.) ST-1: From field, about 1,200 feet south of Fitzgerald Avenue. (1/22/2015, 10:53 to 11:03 a.m.) ST-2: Driveway of Santa Teresa Boulevard, 75 feet from roadway. (1/22/2015, 11:17 to 11:27 a.m.) ST-3: 430 feet west of Monterey Road and Buena Vista Avenue intersection. (1/22/2015, 11:41 to 11:51 a.m.) ST-4: 75 feet north of Day Road, 390 feet east of Santa Teresa Boulevard. (1/27/2015, 9:20 to 9:30 a.m.) * Traffic on Monterey Road. Traffic on Day Road. Traffic on Santa Teresa Boulevard. Agricultural equipment, distant traffic, birds, and wind * Santa Teresa Traffic along Boulevard * Monterey Traffic on Road * Traffic on Day Road, distant traffic on Santa Teresa Boulevard. 15

17 Primary Measured Noise Levels, dba Measurement Location L eq L 1 L 50 L 90 L dn Noise Source ST-5: Along Wren Avenue, near intersection with Farrell Traffic on Wren Avenue Avenue and Elementary * and Farrell School. (1/27/2015, 9:40 to Avenue, 9:50 a.m.) school children ST-6: 50 feet east of Kern Avenue near Tatum Avenue. (1/27/2015, 9:40 to 9:50 a.m.) M-1: 90 feet west of centerline of Santa Teresa Boulevard, near Day Road. (12/5/2013, 12:30-12:40 p.m.) M-2: 90 feet west of centerline of Monterey Road. (12/5/2013, 1:00-1:10 p.m.) M-3: 100 feet from center of Santa Teresa Boulevard. (12/5/2013, 12:00-12:10 p.m.) M-4: 65 feet from center of Mantelli Drive, 120 feet from center of Wren Avenue. (12/5/2013, 11:30-11: * 16 playing. Traffic on Kern Avenue, dog barking and birds chirping * Santa Teresa Traffic on Boulevard * Monterey Traffic on Road * Santa Teresa Traffic on Boulevard * Mantelli Drive and Wren Traffic on Avenue. p.m.) * Estimated by correlation to representative long-term site. The hourly trend in the daily noise level measured at the most representative location is applied to the short-term measurements to estimate L dn. 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 groundborne vibration levels, or if ambient noise levels at sensitive receivers would be substantially increased over a permanent, temporary, or periodic basis. The following criteria were used to evaluate the significance of environmental noise resulting from the project: A significant noise impact would be identified if the project would expose persons to or generate noise levels that would exceed applicable noise standards

18 presented in the General Plan or Municipal Code. A significant impact would be identified if the construction of the project would expose persons to excessive vibration levels. Groundborne vibration levels exceeding 0.3 in/sec PPV would have the potential to result in architectural damage to normal buildings or railroad train vibration would exceed FTA thresholds. 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 would occur if existing plus project noise levels would be 3 dba L dn or greater where exterior noise levels would exceed the normally acceptable noise level standard (60 dba L dn ) or if existing plus project noise levels would be 5 dba L dn or greater where noise levels would remain at or below the normally acceptable noise level. A significant noise impact would be identified if construction related noise would temporarily increase ambient noise levels at sensitive receivers. Hourly average noise levels exceeding 60 dba L eq, and the ambient by at least 5 dba L eq, for a period greater than one year would constitute a significant temporary noise increase at noise-sensitive residential land uses. Impact 1: Noise and Land Use Compatibility. Land uses are proposed along existing and planned transportation corridors where noise levels would exceed the acceptability thresholds established in the Gilroy General Plan. This is a significant impact. As shown on Figure 2, the NGND is divided into two Districts, the Rancho 101 Neighborhood District north of the Buena Vista Avenue extension, and the North Central Neighborhood District south of the extension. Rancho 101 is divided into Neighborhoods 1 and 2, and the area designated for Open Space. North Central is divided into Neighborhoods 3, 4, and 5. The future noise exposure levels were calculated using the existing measured noise levels adjusted upward to account for increased traffic on the roadways due to cumulative development including the build out of the NGND, and by modeling noise levels along new roadway segments using the Federal Highway Administration (FHWA) Traffic Noise Model (TNM) algorithms. Railroad train noise from operations on the UPRR tracks was assumed to be similar to existing conditions. The California High Speed Train (HST) San Jose to Merced Section is proposed to pass through the City of Gilroy. There are several alternative alignments and design options under consideration for the Morgan Hill to Gilroy sub-section as described in the Supplemental Alternatives Analysis (May 2011). The East of UPRR to Downtown Gilroy alignment would be located along the east of side of the existing UPRR right-of-way. This alignment would be within about 200 feet of the eastern edge of the NGND, and would effectively become another source of noise and vibration within the Monterey Road/UPRR corridor. The other alignments would be located further to the east and would be outside the potential area of effect for the HST. The design options under consideration through Gilroy include HST on an aerial 17

19 structure, HST at-grade, HST in a trench, and HST in a partially covered trench in downtown Gilroy. Representative noise and vibration data for the proposed California High Speed Rail Project was obtained from various sources, including data from published environmental documents that have studied the project and data provided by the California High Speed Rail Authority, most of which appears to have been based upon the U.S. DOT High Speed Ground Transportation Noise and Vibration Impact Assessment. FIGURE 2 NGND Neighborhoods Diagram 18

20 19

21 Noise and vibration studies and environmental impact reports (EIRs) that were utilized in this assessment were programmatic, as specific development plans for the HST have not been finalized. For the purpose of this analysis, credible worst case assumptions were made regarding the speed, frequency, location of right-of-way, and other factors. This analysis assumes that trains will travel either at-grade or on an aerial platform (approximately 24 feet above grade) past the NGND at maximum speeds of 125 mph 200 mph. During peak periods and full build-out of the high-speed rail system, approximately 10 to 12 trains are expected to travel past the site per hour in each direction. During off-peak periods, 6 to 8 trains are expected per hour in each direction. Trains would not travel between the hours of midnight and 5:00 am. Using data from the California HST Program EIR/EIS, day-night average noise levels are anticipated to range from dba L dn at the eastern boundary of the NGND, and maximum noise levels generated by a passing HST are anticipated to reach approximately 75 to 80 dba L max. The HST would make an incremental contribution to the total noise level of less than 1 dba L dn, and maximum noise levels from trains passing by would be below the noise levels generated by trains and trucks utilizing the existing corridor. However, there are other considerations. If the HST is placed on an aerial structure, noise mitigation for the Monterey Road/UPRR corridor such as earthen berms, at-grade sound walls, or a combination of the two would not mitigate the HST noise. HST noise mitigation would need to be incorporated into the HST project design. Existing and future outdoor noise exposure levels calculated for the NGND are summarized in Table 7. 20

22 TABLE 7 Traffic Noise Levels at 75 feet from Roadway Segments, Distances to Noise Contours Future Distance Distance Distance Distance (2040) (ft) to (ft) to (ft) to (ft) to L dn future future future future at L dn 65 L dn 70 L dn 75 L dn Roadway Segment Existing L dn at 75 feet feet contour contour contour contour Buena Vista Ave, Monterey Rd to Hwy 101 Buena Vista Ave Future n/a Extension, Santa Teresa Blvd to Monterey Rd Church St (Future) n/a n/a Cohansey Ave, Santa Teresa Blvd to Monterey Rd Day Rd, Santa Teresa Blvd to Monterey Rd Day Rd, west of Santa Teresa Blvd Farrell Ave, east of Wren Ave Farrell Ave, west of Monterey Rd Fitzgerald Ave, Santa Teresa Blvd to Monterey Rd Kern Ave, north of Mantelli Dr Monterey Rd/UPRR Corridor Santa Teresa Blvd, South of Fitzgerald Ave Santa Teresa Blvd, North of Day Rd Santa Teresa Blvd, South of Day Rd Sunrise Dr, west of Santa Teresa Blvd Wren Ave, north of Farrell Ave Wren Ave, south of Farrell Ave 63 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

23 Note: Noise contour data is not presented at distances of less than 25 feet from the roadway centerline. 22

24 Neighborhood 1 Neighborhood 1 is bounded by Fitzgerald Avenue on the north, the Monterey Road/UPRR railroad corridor on the east, Wren Avenue extension and a linear park (Neighborhood 2) along the west, and the Buena Vista Avenue Extension on the south. Extensions of Wren Avenue and Church Street would transect Neighborhood 1 parallel with Monterey Road, and two minor interior roadways would transect Neighborhood 1 parallel with Fitzgerald Avenue. The residential and commercial uses proposed adjacent to the Monterey Road/UPRR corridor would be exposed to future noise levels of up to 78 dba L dn, and up to 71 dba L dn along Fitzgerald Avenue through the Amendment area. Exterior noise levels in these areas would exceed the maximum permissible levels of 60 dba L dn for residential uses and 65 dba L dn for commercial uses established in Policy of the Gilroy General Plan (see Table 5). The first row of development adjacent to the transportation routes suffers the greatest noise exposure due to proximity and a lack of shielding from intervening structures. Development within the interior of Neighborhood 1, away from the major noise sources, would be exposed to substantially lower levels of noise. However, given the severity of the noise exposure along the Monterey Road/UPRR corridor, and the elevated noise levels along the Wren Avenue extension, Fitzgerald Avenue, and the Buena Vista Avenue Extension, noise levels approaching the residential threshold for outdoor noise of 60 dba L dn could occur throughout Neighborhood 1. In residential buildings of typical California construction, with the windows partially open, interior noise levels are generally 15 dba lower than exterior noise levels. With the windows maintained closed, standard residential construction typically provides about 20 to 25 decibels of noise reduction. 1 Exterior noise levels throughout the project site are calculated to potentially exceed 60 dba L dn ; therefore, interior noise levels with the windows partially open for ventilation would exceed 45 dba L dn. Given the projected noise exposure levels along the major transportation corridors, indoor noise levels would approach or exceed the City of Gilroy s 45 dba L dn interior noise threshold for residential compatibility with the windows closed. Noise levels in outdoor areas and inside buildings located within Neighborhood 1 would exceed the acceptability thresholds established in the Gilroy General Plan. Neighborhood 2 Neighborhood 2 is bounded by existing residential development on the north, a linear park and Wren Avenue on the east, the Buena Vista Avenue extension on the south, and Santa Teresa Avenue and existing residences on the west. Major noise sources affecting planned residential areas in Neighborhood 2 include Santa Teresa Boulevard and the extension of Wren Avenue. Noise levels are projected to range from 70 to 72 dba L dn adjacent to these roadways. Exterior noise levels in these areas would exceed the maximum permissible levels of 60 dba L dn for 1 Attenuation levels from residential construction are based on measurements and calculations made by Illingworth & Rodkin Inc. since

25 residential uses. Noise levels at residences in the second or subsequent rows of homes away from these roadways would generally be satisfactory. Exterior noise levels near the major roads are calculated to potentially exceed 60 dba L dn ; therefore, interior noise levels with the windows partially open for ventilation would exceed 45 dba L dn. Given the projected noise exposure levels along the major transportation corridors, indoor noise levels would approach or exceed the City of Gilroy s 45 dba L dn interior noise threshold for residential compatibility with the windows closed. Noise levels in outdoor areas and inside buildings located within Neighborhood 2 would exceed the acceptability thresholds established in the Gilroy General Plan. Neighborhood 3 Neighborhood 3 is bounded by the Buena Vista Avenue extension on the north, the Monterey Road/UPRR corridor on the east, existing residential areas on the south, and the extension of Wren Avenue on the west. The outdoor and indoor noise exposures in Neighborhood 3 are similar to Neighborhood 1. Future noise levels are estimated to reach 78 dba L dn adjacent to the Monterey Road/UPRR corridor and up to 71 dba L dn throughout the Amendment area. Exterior noise levels throughout the plan area are calculated to exceed 60 dba L dn ; therefore, interior noise levels with the windows partially open for ventilation would exceed 45 dba L dn. Given the projected noise exposure levels along the major transportation corridors, indoor noise levels would exceed the City of Gilroy s 45 dba L dn interior noise threshold for residential compatibility with the windows closed. Noise levels in outdoor areas and inside buildings located within Neighborhood 3 would exceed the acceptability thresholds established in the Gilroy General Plan. Neighborhood 4 Neighborhood 4 is bounded by the Buena Vista Avenue extension on the north, the extension of Wren Avenue and Neighborhood 5 on the east, the connection between Sunrise Drive and Cohansey Avenue, and existing residential on the south, and Santa Teresa Boulevard on the west. Major noise sources affecting planned residential areas in Neighborhood 4 include Santa Teresa Boulevard and the Buena Vista Avenue Extension. Noise levels are projected to range up to 72 dba L dn adjacent to Santa Teresa Boulevard and up to 66 dba L dn along the Buena Vista Avenue Extension. Exterior noise levels in these areas would exceed the maximum permissible levels of 60 dba L dn for residential uses and 65 dba L dn for commercial uses. Noise levels at residences in the second or subsequent rows of homes away from these roadways would generally be satisfactory. Exterior noise levels near the major roads are calculated to potentially exceed 60 dba L dn ; therefore, interior noise levels with the windows partially open for ventilation would exceed 45 dba L dn. Given the projected noise exposure levels along the major transportation corridors, indoor noise levels would approach or exceed the City of Gilroy s 45 dba L dn interior noise 24

26 threshold for residential compatibility with the windows closed. Noise levels in outdoor areas and inside buildings located within Neighborhood 4 would exceed the acceptability thresholds established in the Gilroy General Plan. Neighborhood 5 Neighborhood 5 is bounded by the connection of Sunset Drive and Cohansey Avenue on the north, wren Avenue and existing residences on the east, existing residences on the south, and Kern Avenue, existing residences, and Neighborhood 4 on the west. The major noise source affecting Neighborhood 5 is Wren Avenue traffic, where the noise exposure along the roadway is calculated to be 63 dba L dn north of Farrell Avenue, and 64 dba L dn south of Farrell Avenue. Exterior noise levels near the major roads are calculated to potentially exceed 60 dba L dn ; therefore, interior noise levels with the windows partially open for ventilation would exceed 45 dba L dn. Given the projected noise exposure levels along the major transportation corridors, indoor noise levels would approach or exceed the City of Gilroy s 45 dba L dn interior noise threshold for residential compatibility with the windows closed. Noise levels in outdoor areas and inside buildings located within Neighborhood 5 would exceed the acceptability thresholds established in the Gilroy General Plan. Noise levels in the NGND would exceed the acceptability thresholds established in the Gilroy General Plan. This is a significant environmental impact. Mitigation 1: Implement measures that would mitigate transportation noise in outdoor activity areas and inside new buildings in the NGND. Development projects within the NGND shall demonstrate that site-specific noise reduction measures have been incorporated into the design plans and will meet the City s noise standards. These measures may include, but are not limited to, some or all of the following: Use sound walls, or sound walls in combination with earthen berms where proposed, to reduce noise levels to meet the City s noise standards in outdoor activity areas associated with proposed residential developments and neighborhood commercial developments. Noise barriers along roadways would typically range from 6 to 12 feet in height to reduce exterior noise levels to acceptable levels (60 dba L dn ). Preliminary noise modeling indicates that a noise barrier at least 15 feet high would be required at outdoor use areas adjacent to the Monterey Road/UPRR Corridor to reduce exterior noise levels to acceptable levels in residential areas. The final height and design of these barriers would be completed during the site specific review when detailed site plans and grading plans are available. If the HST is placed on an aerial structure, noise mitigation would need to be incorporated into the HST project design. The City of Gilroy should continue to coordinate with the California High Speed Rail Authority to ensure that 25

27 HST incorporates appropriate mitigation measures. Utilize site planning to minimize noise in residential areas by locating residences further from the centerline of the noise source or by using the buildings as noise barriers to shield outdoor use areas. Appropriate noise reduction would need to be demonstrated with site-specific acoustical analyses. If 60 dba L dn or less is not achieved for exterior noise levels where residential units are proposed (e.g., at unshielded upper stories of single or multi-family homes), the City of Gilroy requires project-specific acoustical analyses to achieve interior noise levels of 45 dba L dn or lower. Building sound insulation requirements would need to include the provision of forced-air mechanical ventilation in noise environments exceeding 60 dba L dn so that windows could be kept closed at the occupant s discretion to control noise. Special building construction techniques (e.g., sound-rated windows and building facade treatments) may be required where exterior noise levels exceed 65 dba L dn. These treatments include, but are not limited to sound rated windows and doors, sound rated exterior wall assemblies, acoustical caulking, etc. The specific determination of what treatments are necessary will be conducted on a unit-by-unit basis during project design. Results of the analysis, including the description of the necessary noise control treatments, will be submitted to the City along with the building plans and approved prior to issuance of a building permit. Feasible construction techniques such as these would adequately reduce interior noise levels to 45 dba L dn or less. The implementation of these measures could feasibly reduce the significant noise impact to a less-than-significant level, however, since mitigation that would be incorporated into the HST Project is unknown and beyond the control of the City, the impact would be significant and unavoidable. Impact 2: The NGND proposes neighborhood-serving commercial uses adjacent to residential land uses. New commercial development proposed adjacent to residential development could result in noise levels exceeding City standards. New commercial, office, or other non-residential development could produce noise that could affect existing or proposed residences. New projects developed under the NGND would be subject to the City s Municipal Code, which sets a limit of 70 dba L 10 for permissible noise levels during the day and night. New commercial development proposed adjacent to residential development could create noise exceeding City standards. Noise sources at these commercial uses could include loading docks, outdoor mechanical equipment (e.g., heating and cooling equipment, etc.), and parking lots. Restaurants, bars, and other entertainment-oriented uses could also generate noise from music and patrons. Noise associated with the use of parking lots would include vehicular circulation, loud engines, car alarms, squealing tires, door slams, and human voices. The maximum sound (L max ) of a passing car at 15 mph typically ranges from 43 dba to 53 dba at 150 feet. The noise generated during an engine start is similar. Door slams create lower noise levels. Hourly average 26

28 noise level resulting from all of these noise-generating activities in a busy parking lot could range from 35 dba to 45 dba L eq at a distance of 150 feet from the parking area. Heating, ventilation, and cooling equipment could generate noise levels in the range of 50 dba to 70 dba L eq at 150 feet depending on the number, type, and size of the proposed equipment. Trash compactors typically generate maximum noise levels of 40 to 50 dba at 150 feet, depending on the power rating and enclosure characteristics. Noise levels exceeding City standards for stationary noise sources could occur at the nearest receivers within and around the NGND, depending on the ultimate commercial uses, and if the noise levels generated by such uses are not regulated or adequately mitigated. This represents a potentially significant impact. Mitigation 2: Noise levels at residential property lines from commercial development should be maintained not in excess of the noise limits set forth in the Municipal Code. The approvals of the commercial development should require a noise study demonstrating how the business, including loading docks, refuse areas, and ventilation systems, etc., would be consistent with the City s noise standards. Implementation of these measures would reduce the impact to a less-than-significant level. The implementation of these measures would feasibly reduce the significant noise impact to a less-than-significant level. Impact 3: Train Vibration. Vibration levels produced by high-speed trains may exceed the FTA Guidelines for acceptable vibration levels. This is a significant impact. Many factors influence levels of groundborne vibration from trains experienced in buildings, including operational factors, geology, building construction, train speed, and track type. For the purposes of this analysis, assumptions were made regarding these factors to predict vibration levels from HST at the nearest receivers. Steel-wheel technology is regarded at the type of train system that will be implemented, with wheels in proper working condition (e.g., no worn wheels or wheels with flats). The analysis again assumes that the maximum speed would be between mph and the design option would be either at-grade or on an aerial platform approximately 24 feet above grade. Using data from the California HST Program EIR/EIS, the vibration level at a distance of 200 feet from the tracks resulting from a train traveling at-grade at 125 mph would be about 70 VdB, increasing to about 75 VdB at a speed of 200 mph. The impact threshold is 72 VdB, so the threshold could be exceeded at the higher travel speed. Utilizing appropriate adjustment factors, vibration levels can be adjusted up or down based on known conditions. An adjustment of 10 VdB is subtracted from the reference level for a train traveling on an aerial platform. If the design option for an aerial structure is selected, projected vibration levels within the NGND would be below the impact threshold. Vibration from conventional rail traffic is typically below the FTA thresholds at 27

29 distances greater than 100 feet. NGND land uses would be located at least 150 feet from the center of the UPRR, therefore, vibration levels due to conventional rail trains would be less-thansignificant. Mitigation 3: If the HST is placed at-grade and train speeds exceed 125 mph opposite the NGND, vibration mitigation would need to be incorporated into the HST project design. The City of Gilroy should continue to coordinate with the California High Speed Rail Authority to ensure that HST incorporates appropriate mitigation measures. The implementation of these measures could feasibly reduce the significant noise impact to a less-than-significant level, however, as with Mitigation 1, mitigation incorporated as a result of the HST Project are unknown and beyond the control of the City, resulting in a significant and unavoidable impact. Impact 4: Construction Vibration. Vibration levels generated during construction activities may at times be perceptible at neighboring land uses, but vibration levels would not be excessive causing cosmetic or structural damage to buildings. This is a less-than-significant impact. Construction activities would include excavation, grading, and site preparation work, including the construction of roadways and project infrastructure and ultimately the construction of buildings. The California Department of Transportation recommends a vibration limit of 0.5 in/sec PPV for buildings structurally sound and designed to modern engineering standards, 0.3 in/sec PPV for buildings that are found to be structurally sound but where structural damage is a major concern, and a conservative limit of 0.08 in/sec PPV for ancient buildings or buildings that are documented to be structurally weakened. This analysis assumes that no ancient buildings or buildings that are documented to be structurally weakened adjoin the project site. Therefore, groundborne vibration levels exceeding 0.3 in/sec PPV would have the potential to result in a significant vibration impact. Table 8 presents typical vibration levels that could be expected from construction equipment at a distance of 25 feet. 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 vibration in the immediate vicinity. 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. Vibration levels from typical construction activities would be expected to be 0.2 in/sec PPV or less at a distance of 25 feet, below the 0.3 in/sec PPV significance threshold. Vibration generated by construction activities occurring adjacent to existing single-family residential land uses would at times be perceptible. However, intermittent and perceptible vibration levels would not be expected to result in cosmetic damage to these buildings. This is a less-than-significant impact. 28

30 TABLE 8 Vibration Source Levels for Construction Equipment Equipment PPV at 25 ft. (in/sec) Approximate L v at 25 ft. (VdB) Pile Driver (Impact) upper range typical Pile Driver (Sonic) upper range typical Clam shovel drop Hydromill (slurry wall) in soil in rock Vibratory Roller Hoe Ram Large bulldozer Caisson drilling Loaded trucks Jackhammer Small bulldozer Source: Transit Noise and Vibration Impact Assessment, United States Department of Transportation, Office of Planning and Environment, Federal Transit Administration, May Mitigation 4: None required. Impact 5: Traffic Noise: The increase in vehicular traffic due to the implementation of the NGND would not result in a substantial increase in traffic noise levels at existing residences in the project vicinity. Cumulative development, including the project, would result in a substantial noise increase at residences along Wren Avenue between Cohansey Avenue and Mantelli Drive. This is a significant impact. Traffic noise levels are assessed in two ways: project generated noise levels compared to the existing ambient noise environment and cumulative noise levels compared to the existing ambient noise environment. Cumulative noise levels include traffic from The Gilroy General Plan build-out as well as all proposed changes (both land use and roadway network changes) associated with the proposed NGND Amendment project. Table 9 shows noise level increases as a result of existing and cumulative traffic scenarios, both with and without the project. Project-Generated Traffic Noise Traffic volume information contained in the project s traffic impact analysis 2 was reviewed to calculate the change in traffic noise levels attributable to the operation of the project. Traffic volumes under the Existing and Existing Plus Project traffic scenarios were compared to calculate the relative increase in traffic noise attributable to the proposed project. A noise impact would be identified at noise-sensitive land uses where the project would result in a noise level increase of 3 dba L dn or more where exterior noise levels would exceed the normally acceptable 2 North Gilroy Neighborhood Districts Urban Service Area Amendment Administrative Draft Traffic Impact Analysis, Hexagon Transportation Consultants Inc., April

31 noise level standard (60 dba L dn ) or if existing plus project noise levels would be 5 dba L dn or greater where noise levels would remain at or below the normally acceptable noise level. A comparison of the Existing and Existing Plus Project traffic scenarios shows that, with the exception of Wren Avenue north of Farrell Avenue, traffic volumes on all other roadways serving the project site would only be slightly increased with the project as compared to existing conditions. Traffic noise levels on area roadways, excluding Wren Avenue, are calculated to increase by less than 2 dba L dn as a result of the project. This segment of Wren Avenue would provide access to Antonio Del Buono Elementary School, north of which is an existing neighborhood that is not part of the NGND. Outdoor activity areas at these residences are located at distances of 75 feet or greater from the centerline of the roadway. Based on noise data collected at ST-5 and long-term measurements throughout the site, existing noise levels are calculated to be approximately 61 dba L dn at a distance of 75 feet from the centerline of the roadway. Traffic noise levels assuming Existing and Existing Plus Project traffic conditions during the PM peak traffic hour were modeled to calculate the change in noise levels expected at the nearest residential outdoor use areas. Existing traffic noise levels are calculated to increase by 2 dba L dn with the operation of the project and reach 63 dba L dn at a distance of 75 feet. While the noise environment at existing residences in the project s vicinity would noticeably introduce increased local traffic as noise sources, these increases would not be substantial. Existing Plus Project traffic noise levels would not exceed the 3 dba L dn threshold (where noise levels would exceed 60 dba L dn ), therefore, the impact related to project generated traffic along Wren Avenue would be less-than-significant. 30

32 TABLE 9 Traffic Noise Levels at 75 feet from Roadway Segments Roadway Segment Existing L dn No Project Buena Vista Ave, Monterey Rd to Hwy Buena Vista Ave Future Extension, Santa n/a Teresa Blvd to Monterey Rd Church St (Future) n/a Cohansey Ave, Santa Teresa Blvd to n/a Monterey Rd Day Rd, Santa Teresa Blvd to Monterey n/a n/a Rd Cumulative Traffic Noise Existing L dn With Project Cumulative L dn No Project Cumulative L dn With Project Day Rd, west of Santa Teresa Blvd Farrell Ave, east of Wren Ave Farrell Ave, west of Monterey Rd Fitzgerald Ave, Santa Teresa Blvd to Monterey Rd Kern Ave, north of Mantelli Dr Monterey Rd/UPRR Corridor Santa Teresa Blvd, South of Fitzgerald Ave Santa Teresa Blvd, North of Day Rd Santa Teresa Blvd, South of Day Rd Sunrise Dr, west of Santa Teresa Blvd Wren Ave, north of Farrell Ave Wren Ave, south of Farrell Ave Traffic volumes along roadways serving the project site will increase as a result of cumulative growth planned in the Gilroy General Plan and with implementation of the NGND. The project would make a cumulatively considerable contribution to cumulative traffic noise increases. This is a significant impact. The project would result in a significant cumulative traffic noise impact if sensitive receptors would be exposed to cumulative traffic noise level increases greater than 3 dba L dn, where exterior noise levels would exceed 60 dba L dn, or 5 dba L dn or greater where noise levels would remain at or below 60 dba L dn, and where the project would make a cumulatively considerable contribution to the overall traffic noise level increase. A cumulatively considerable contribution would be defined as an increase of 1 dba L dn or more attributable solely to the proposed project. Cumulative traffic noise level increases were calculated by comparing Cumulative traffic volumes to Existing traffic volumes. Cumulative plus Project traffic noise level 31

33 increases were calculated in the same manner by comparing Cumulative plus Project traffic volumes to Existing traffic volumes. Vehicular traffic on roadways would increase as development occurs and population increases. These projected increases in traffic would occur over time and would increase noise levels throughout the project and vicinity. Traffic noise levels were projected for cumulative development with and without the project to determine how additional roadways and changes in vehicular traffic volumes would affect traffic noise levels. Noise impacts resulting from the build-out of cumulative development and from build-out of the project were assessed by comparing cumulative plus project traffic conditions and cumulative (without project) conditions to existing traffic conditions. Substantial noise increases (3 dba L dn or greater) would occur along Monterey Road, Santa Teresa Boulevard, Day Road, Buena Vista Avenue, and Wren Avenue as a result of cumulative and cumulative plus project conditions. Substantial noise increases (3 dba L dn or greater) as a result of cumulative and cumulative plus project traffic conditions would also occur along future roadways and roadway extensions including Cohansey Avenue, Kern Avenue, Buena Vista Extension, and Wren Avenue. However, these substantial increases are based on local traffic levels alone and do not take into account other significant ambient noise sources such as distant traffic and railroad noise. Additionally, cumulative plus project conditions result in an over-all decrease in traffic noise along existing roadways when compared to cumulative conditions. Increases in cumulative noise levels as a result of the project are limited to future roadway segments that are either extensions or new roads. Noise increases are expected at existing noise sensitive areas adjoining future roadways along the southeast borders of the NGND Amendment area. The largest relative traffic noise increases are expected in areas with relatively low existing traffic volumes. Noise levels from traffic future roadways were calculated using SoundPlan (version 7.3) noise modeling software. The project would make a cumulatively considerable contribution to cumulative traffic noise increases along Wren Avenue, between Cohansey Avenue and Mantelli Drive. Outdoor activity areas at residences along this roadway segment are located at distances of 75 feet or greater from the centerline of the roadway. Based on noise data collected at ST-5 and long-term measurements throughout the site, existing ambient noise levels are calculated to be approximately 61 dba L dn at a distance of 75 feet from the centerline of the roadway. A 2 dba L dn increase was calculated to occur under cumulative conditions and a 3 dba L dn increase was calculated to occur under cumulative plus project conditions. An increase of 1 dba L dn or more is attributable solely to the proposed project. This is a significant impact. Mitigation 5: Methods available to mitigate cumulative traffic noise level increases would need to be studied on a case-by-case basis at receivers that would be considered noise impacted. Noise reduction methods could include the following: New or larger noise barriers or other noise reduction techniques could be 32

34 constructed to protect sensitive outdoor use areas at existing residential land uses where reasonable and feasible. Final design of such barriers should be completed during project level review on a parcel by parcel basis. Alternative noise reduction techniques could be implemented, such as re-paving streets with "quieter" pavement types such as Open-Grade or Rubberized Asphalt Concrete. The use of "quiet" pavement can reduce noise levels by 2 to 5 dba depending on the existing pavement type, traffic speed, traffic volumes, and other factors. The implementation of these measures would feasibly reduce the significant noise impact to a less-than-significant level. Impact 6: Construction Noise. Noise generated by construction activities as a result of the Amendment would temporarily elevate ambient noise levels at sensitive land uses in the vicinity. Due to the proximity of existing residential land uses, there is a potential that construction noise levels would exceed 60 dba L eq, and the ambient by at least 5 dba L eq, for a period greater than one year. This is a significant impact. 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. Typically, significant noise impacts do not result when standard construction noise control measures are enforced at a given project site and when the duration of the noise generating construction period is limited to one construction season (typically one year) or less. Once construction moves indoors, minimal noise would be generated at off-site locations. Construction activities can generate high noise levels, especially during the construction of project infrastructure when heavy equipment is used. Maximum instantaneous noise levels from the majority of construction equipment ranges from about 73 to 85 dba L max at a distance of 50 feet. Demolition tools such as concrete saws and hoe rams can result in maximum instantaneous noise levels of about 90 dba L max at a distance of 50 feet from the noise source. Typical hourly average construction generated noise levels are about 81 to 88 dba L eq measured at a distance of 50 feet from the center of the site during busy construction periods (e.g., earth moving equipment, impact tools, etc.). Figure 3 shows typical construction noise levels at a distance of 50 feet. Construction generated noise levels drop off at a rate of about 6 dba per doubling of distance between the source and receptor. Shielding by buildings or terrain often result in lower construction noise levels at distant receptors. 33

35 FIGURE 3 Typical Construction Equipment Noise Levels 34

36 Noise from construction activities could exceed 60 dba L eq and the ambient noise environment by at least 5 dba L eq at noise-sensitive uses in the NGND vicinity for a period of one year or more, and the impact would be considered significant. Mitigation 6: The City s approach to mitigating construction related noise impacts is to condition General Plan EIR Mitigation Measure 4.7-B on all construction projects. All construction activities shall comply with General Plan Mitigation Measure 4.7-B, which is presented, with revisions, as follows: As part of normal City review and approval procedures for future projects the following measures shall be incorporated to mitigate construction noise, as determined feasible by the City Planning and Engineering divisions: Limit construction activity to weekdays between 7:00 am and 7:00 pm and Saturdays and holidays between 9:00 am and 7:00 pm, with no construction on Sundays; Locate stationary noise-generating equipment as far as possible from sensitive receptors when sensitive receptors adjoin or are near a construction project area; and Construct sound walls or other noise reduction measures prior to developing the project site. The following standard construction noise controls shall be implemented at a project site: Equip all internal combustion engine driven equipment with intake and exhaust mufflers that are in good condition and appropriate for the equipment; Prohibit all unnecessary idling of internal combustion engines; Utilize quiet models of air compressors and other stationary noise sources where technology exists; Designate a "disturbance coordinator" who would be responsible for responding to any complaints about construction noise. The disturbance coordinator will determine the cause of the noise complaint (e.g., bad muffler, etc.) and will require that reasonable measures be implemented to correct the problem. The implementation of the above measures would reduce construction noise levels emanating from a given site, limit construction hours, and minimize disruption and annoyance. With the implementation of these measures, the substantial temporary increase in ambient noise levels would be less-than-significant. Impact 7: Noise and Land Use Compatibility (Aircraft). The NGND is located within two miles of South County Airport, but outside of the 65 dba L dn aircraft noise contour. This is a less-than significant impact. The Santa Clara County Airport Land Use Commission ALUC has jurisdiction over new 35

37 land uses in the vicinity of airports, and establishes 65 dba L dn as the maximum allowable noise level considered compatible with residential uses. The nearest portion of the NGND project area is located approximately 1.5 miles southwest of South County Airport. A review of the Santa Clara County Comprehensive Land Use Plan and a noise contour map 3 in the South County Airport Master Plan Report indicates that the 65 dba L dn contour line does not extend southward beyond the airport boundaries. This would be considered a less-than-significant impact. Mitigation 7: None Required. 3 South County Airport Master Plan Report, County of Santa 36 Clara, July 2006.

38 Appendix A Noise Measurement Data

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45