4.10 NOISE Introduction

Transcription

1 4.10 NOISE Introduction The Noise chapter of the Draft EIR discusses the existing noise environment in the immediate project vicinity and identifies potential noise-related impacts and mitigation measures associated with the proposed project. Specifically, this chapter analyzes potential noise impacts due to and upon development within the project site relative to applicable noise criteria and to the existing ambient noise environment. Information presented in this chapter is primarily drawn from the Environmental Noise Assessment 1 prepared specifically for the proposed project by j.c. brennan & associates, Inc. (see Appendix I), as well as the Manteca General Plan 2 and the Manteca General Plan EIR Existing Environmental Setting The Existing Environmental Setting section provides background information on noise and vibration, a discussion of acoustical terminology and the effects of noise on people, existing sensitive receptors in the project vicinity, existing sources and noise levels in the project vicinity, and groundborne vibration. Acoustical Terminology Acoustics is the science of sound. Sound is a mechanical energy of vibrating transmitted by pressure waves through a medium to human (or animal) ears. If the pressure variations occur frequently enough, 20 times per second, they can be heard and are called sound. The number of pressure variations per second is called the frequency of sound, and is expressed as cycles per second, called Hertz (Hz). Noise is a subjective reaction to different types of sounds. Noise is typically defined as (airborne) sound that is loud, unpleasant, unexpected or undesired, and may therefore be classified as a more specific group of sounds. Perceptions of sound and noise are highly subjective from person to person. Measuring sound directly in terms of pressure would require a very large and awkward range of numbers. To avoid this, the decibel scale was devised. The decibel scale uses the hearing threshold (20 micropascals), as a point of reference, defined as 0 db. Other sound pressures are then compared to this reference pressure, and the logarithm is taken to keep the numbers in a practical range. The decibel scale allows a million-fold increase in pressure to be expressed as 120 db, and changes in levels (db) correspond closely to human perception of relative loudness. The perceived loudness of sounds is dependent upon many factors, including sound pressure level and frequency content. However, within the usual range of environmental noise levels,

2 perception of loudness is relatively predictable, and can be approximated by A-weighted sound levels. A strong correlation exists between A-weighted sound levels (expressed as dba) and the way the human ear perceives sound. Accordingly, the A-weighted sound level has become the standard tool of environmental noise assessment. All noise levels reported in this chapter are in terms of A-weighted levels, but are expressed as db, unless otherwise noted. The decibel scale is logarithmic, not linear. In other words, two sound levels 10 db apart differ in acoustic energy by a factor of 10. When the standard logarithmic decibel is A-weighted, an increase of 10 dba is generally perceived as a doubling in loudness. For example, a 70 dba sound is half as loud as an 80 dba sound, and twice as loud as a 60 dba sound. Community noise is commonly described in terms of the ambient noise level, which is defined as the all-encompassing noise level associated with a given environment. A common statistical tool to measure the ambient noise level is the average, or equivalent, sound level (L eq ), which corresponds to a steady-state A-weighted sound level containing the same total energy as a time varying signal over a given time period (usually one hour). The L eq is the foundation of the composite noise descriptor, L dn, and shows very good correlation with community response to noise. The day/night average noise level (L dn ) is based upon the average noise level over a 24-hour day, with a +10 decibel weighing applied to noise occurring during nighttime (10:00 PM to 7:00 AM) hours. The nighttime penalty is based upon the assumption that people react to nighttime noise exposures as though they were twice as loud as daytime exposures. Because L dn represents a 24- hour average, L dn tends to disguise short-term variations in the noise environment. Table provides a list of several examples of the noise levels associated with common activities. Effects of Noise on People The effects of noise on people can be placed in three categories: Subjective effects of annoyance, nuisance, and dissatisfaction; Interference with activities such as speech, sleep, and learning; or Physiological effects such as hearing loss or sudden startling. Environmental noise typically produces effects in the first two categories. Workers in industrial plants can experience noise in the last category. A completely satisfactory way to measure the subjective effects of noise or the corresponding reactions of annoyance and dissatisfaction does not exist. A wide variation in individual thresholds of annoyance exists and different tolerances to noise tend to develop based on an individual s past experiences with noise. Thus, an important way of predicting a human reaction to a new noise environment is the way the new noise environment compares to the existing environment to which one has adapted (i.e., the ambient noise level). In general, the more a new noise exceeds the previously existing ambient noise level, the less acceptable the new noise would be judged by those hearing the noise

3 Table Typical Noise Levels Common Outdoor Activities Noise Level (dba) Common Indoor Activities Rock Band Jet Fly-over at 300 m (1,000 ft) Gas Lawn Mower at 1 m (3 ft) Diesel Truck at 15 m (50 ft), Food Blender at 1 m (3 ft) at 80 km/hr (50 mph) Garbage Disposal at 1 m (3 ft) Noisy Urban Area, Daytime Gas Lawn Mower, 30 m (100 ft) Vacuum Cleaner at 3 m (10 ft) Commercial Area Heavy Traffic at 90 m (300 ft) Normal Speech at 1 m (3 ft) Quiet Urban Daytime Large Business Office Dishwasher in Next Room Quiet Urban Nighttime Theater, Large Conference Room (Background) Quiet Suburban Nighttime Library Quiet Rural Nighttime Bedroom at Night, Concert Hall (Background) Broadcast/Recording Studio Lowest Threshold of Human Hearing Lowest Threshold of Human Hearing Source: Caltrans, Technical Noise Supplement, Traffic Noise Analysis Protocol. November, With regard to increases in A-weighted noise levels, the following relationships occur: Except in carefully controlled laboratory experiments, a change of 1 db cannot be perceived; Outside of the laboratory, a 3 db change is considered a barely perceivable difference; A change in level of at least 5 db is required before any noticeable change in human response would be expected; and A 10 db change is subjectively heard as approximately a doubling in loudness, and would typically cause an adverse response. Stationary point sources of noise including stationary mobile sources such as idling vehicles attenuate (lessen) at a rate of approximately six db per doubling of distance from the source, depending on environmental conditions (i.e., atmospheric conditions and either vegetative or manufactured noise barriers, etc.). Widely distributed noises, such as a large industrial facility spread over many acres, or a street with moving vehicles, would typically attenuate at a lower rate. Existing Sensitive Receptors Certain land uses are more sensitive to ambient noise levels than others due to the amount of noise exposure (in terms of both exposure time and shielding from noise sources) and the type of activities typically involved. Residences, motels and hotels, schools, libraries, churches, hospitals, nursing homes, auditoriums, parks, and outdoor recreation areas are generally more

4 sensitive to noise than are commercial and industrial land uses. Accordingly, such land uses are referred to as sensitive receptors. The proposed project site is surrounded by existing single-family residential uses to the north and west, and agricultural uses to the south and east. Thus, the existing nearby residences would be the nearest sensitive receptors to the project site. Existing Ambient Noise Levels To quantify the existing ambient noise environment in the project vicinity, short-term ambient noise level measurements and continuous (24-hour) noise level measurements were conducted at six overall locations on the project site and vicinity on October 24, 2013 (see Figure ). The ambient noise levels measured are presented in Table Noise levels were collected at each site at hourly intervals. The maximum value (L max ) represents the highest noise level measured during an interval. The average value (L eq ) represents the energy average of all of the noise measured during an interval. The median value (L 50 ) represents the sound level exceeded 50 percent of the time during an interval. Table Summary of Existing Background Noise Measurement Data Average Measured Hourly Noise Levels, db Daytime (7am-10pm) Nighttime (10pm-7am) Site Location L dn L eq L 50 L max L eq L 50 L max Continuous (24-hour) Noise Level Measurements LT-1 Northwest corner of site, 500 feet to Woodward Avenue centerline LT-2 North corner of site, 50 feet to Woodward Avenue centerline LT-3 Northeast of project site, 240 feet to UPRR centerline Short-term Noise Level Measurements ST-1 North side of site. NA :40 PM ST-2 Southwest corner of site NA :25 PM ST-3 Southeast corner of site NA :08 PM Source: j.c. brennan & associates, Inc., Environmental Noise Assessment, January 9, Existing Roadway Noise Levels To predict existing noise levels due to traffic, the Federal Highway Administration Highway Traffic Noise Prediction Model (FHWA) was used. Traffic volumes for existing conditions were obtained from the traffic study prepared for the project (Fehr & Peers). Truck percentages and vehicle speeds on the local area roadways were estimated from field observations

5 Figure Noise Measurement Locations Source: j.c. brennan & associates, Inc., Environmental Noise Assessment, January 9,

6 Traffic noise levels are predicted at the sensitive receptors located at the closest typical setback distance along each project-area roadway segment. Where traffic noise barriers are predominately along a roadway segment, a -5 db offset was added to the noise prediction model. In some locations sensitive receptors may be located at distances which vary from the assumed calculation distance and may experience shielding from intervening barriers or sound walls. However, the traffic noise analysis is believed to be representative of the majority of sensitive receptors located closest to the project-area roadway segments analyzed. The actual distances to noise level contours may vary from the distances predicted by the FHWA model due to roadway curvature, grade, shielding from local topography or structures, elevated roadways, or elevated receivers. However, the distances reported are generally considered to be conservative estimates of noise exposure along the project-area roadways. It should be noted that the contour distances include a -5 db offset for roadway segments that predominately include noise barriers at residential areas. Table presents the existing traffic noise levels in terms of L dn at closest sensitive receptors along each roadway segment, as well as the distances to existing traffic noise contours. Appendices to the Environmental Noise Analysis provide details regarding the FHWA modeling, including the complete inputs and results (see Appendix I). Railroad Noise Levels Railroad activity in the project vicinity occurs on the Union Pacific Railroad (UPRR) line, which is located approximately 900 feet, or further, from the project site. In order to quantify noise exposure from existing train operations, a continuous (24-hour) noise level measurement survey was conducted adjacent the UPRR line. The purpose of the noise level measurements was to determine the typical Sound Exposure Level (SEL) for railroad line operations, while accounting for the effects of travel speed, warning horns, and other factors that may affect noise generation. In addition, the noise level measurement equipment was programmed to identify individual train events, so that the typical number of train operations could be determined. Locations of continuous noise monitoring sites are shown on Figure Table presents a summary of the continuous noise measurement results. The L dn value for railroad line operations were calculated, and the distances to the L dn noise level contours are shown in Table Vibration While vibration is like noise in that vibration involves a source, a transmission path, and a receiver, vibration differs in that noise is generally considered to be pressure waves transmitted through air, whereas vibration usually consists of the excitation of a structure or surface. As with noise, vibration consists of an amplitude and frequency. A person s perception to the vibration depends on their individual sensitivity to vibration, as well as the amplitude and frequency of the source and the response of the system which is vibrating

7 Table Existing Traffic Noise Levels and Distances to Contours Exterior Traffic Distance to Traffic Noise Contours, L dn Roadway Segment Noise Level, db L dn 70 db 65 db 60 db Atherton Dr West of Main St Atherton Dr Main St to Van Ryn Ave Atherton Dr North of Raymus Expy N/A N/A N/A N/A Austin Dr North of Raymus Expy N/A N/A N/A N/A Austin Dr South of Raymus Expy N/A N/A N/A N/A Austin Rd North of SR 99 Ramp Austin Rd SR 99 Ramp to Moffat Blvd Austin Rd South of Moffat Blvd Main St North of Mission Ridge Dr Mission Ridge Dr to SR 120 WB Main St Ramp Main St SR 120 EB Ramp to Atherton Dr Main St Atherton Dr to Woodward Ave S. Manteca Road South of Woodward Ave S. Manteca Road North of Raymus Expy N/A N/A N/A N/A Mission Ridge Dr West of Main St Moffat Blvd North of Spreckels Ave Woodward Ave to SR 99 SB Moffat Blvd Ramp Moffat Blvd SR 99 SB Ramp to Austin Rd Moffat Blvd East of Austin Rd Pillsbury Rd South of Woodward Ave Raymus Expy West of Main St N/A N/A N/A N/A Raymus Expy Main St to Pillsbury Rd N/A N/A N/A N/A Raymus Expy Pillsbury to Atherton Dr N/A N/A N/A N/A Raymus Expy Atherton Dr to Austin Rd N/A N/A N/A N/A Raymus Expy East of Austin Rd N/A N/A N/A N/A Raymus Expy East of Austin Rd N/A N/A N/A N/A Spreckels Ave East of Spreckels Ave Industrial Park Dr to Woodward Van Ryn Ave Ave Woodward Ave West of Main St Woodward Ave Main St to Buena Vista Dr Woodward Ave Buena Vista Dr to Van Ryn Ave Woodward Ave Van Ryn Dr to Pillsbury Rd Woodward Ave Pillsbury Dr to Atherton Dr Woodward Ave Atherton Dr to Moffat Blvd Note: Distances to traffic noise contours are measured in feet from the centerlines of the roadways. Source: j.c. brennan & associates, Inc., Environmental Noise Assessment, January 9,

8 Table Railroad Noise Measurement Results Grade Measurement Location Railroad Track Crossing/ Warning Horn Train Events Per 24-hr period Distance to CL SEL LT-3 UPRR Yes db Source: j.c. brennan & associates, Inc., Environmental Noise Assessment, January 9, Table Approximate Distances to the UPRR Line Noise Contours Exterior Railroad Distance to L dn Contour Noise Level at Measurement Site, L dn 60 db 65 db 70 db feet With Warning Horns 1,241 feet 576 feet 267 feet Source: j.c. brennan & associates, Inc., Environmental Noise Assessment, January 9, Vibration can be measured in terms of acceleration, velocity, or displacement. A common practice is to monitor vibration measures in terms of peak particle velocities in inches per second. Standards pertaining to perception as well as damage to structures have been developed for vibration levels defined in terms of peak particle velocities. Human and structural response to different vibration levels is influenced by a number of factors, including ground type, distance between source and receptor, duration, and the number of perceived vibration events. Table indicates that the threshold for damage to structures ranges from 2 to 6 peak particle velocity in inches per second (in/sec p.p.v). One-half this minimum threshold or 1 in/sec p.p.v. is considered a safe criterion that would protect against architectural or structural damage. The general threshold at which human annoyance could occur is noted as 0.1 in/sec p.p.v Regulatory Setting In order to limit exposure to physically and/or psychologically damaging noise levels, the State of California, various county governments, and most municipalities in the State have established standards and ordinances to control noise. The following provides a general overview of the existing regulations established regarding noise that are relevant to the proposed project. State Regulations California Environmental Quality Act The California Environmental Quality Act (CEQA) Guidelines, Appendix G, indicate that a significant noise impact may occur if a project exposes persons to noise or vibration levels in excess of local general plans or noise ordinance standards, or cause a substantial permanent or temporary increase in ambient noise levels

9 Table Effects of Vibration on People and Buildings Draft EIR Peak Particle Velocity inches/second mm/second Human Reaction Effect on Buildings Threshold of perception; Vibrations unlikely to cause possibility of intrusion damage of any type Recommended upper level of the Vibrations readily perceptible vibration to which ruins and ancient monuments should be subjected Level at which continuous Virtually no risk of architectural vibrations begin to annoy people damage to normal buildings Threshold at which there is a risk Vibrations annoying to people in buildings (this agrees with the of architectural damage to normal dwelling - houses with levels established for people plastered walls and ceilings. standing on bridges and Special types of finish such as subjected to relative short periods of vibrations) lining of walls, flexible ceiling treatment, etc., would minimize architectural damage Vibrations considered unpleasant by people subjected to continuous vibrations and unacceptable to some people walking on bridges Vibrations at a greater level than normally expected from traffic, but would cause architectural damage and possibly minor structural damage Source: Caltrans. Transportation Related Earthborne Vibrations. TAV R9601. February 20, California State Building Codes The State Building Code, Title 24, Part 2 of the State of California Code of Regulations establishes uniform minimum noise insulation performance standards to protect persons within new buildings which house people, including hotels, motels, dormitories, apartment houses, and dwellings other than single-family dwellings. Title 24 mandates that interior noise levels attributable to exterior sources shall not exceed 45 db L dn or CNEL in any habitable room. Title 24 also mandates that for structures containing noise-sensitive uses to be located where the L dn or CNEL exceeds 60 db, an acoustical analysis must be prepared to identify mechanisms for limiting exterior noise to the prescribed allowable interior levels. If the interior allowable noise levels are met by requiring that windows be kept closed, the design for the structure must also specify a ventilation or air conditioning system to provide a habitable interior environment Local Regulations Manteca General Plan The Manteca General Plan Noise Element contains goals, policies, and implementation measures for assessing noise impacts within the City. The following noise goals, policies, and implementation measures are applicable to the proposed project. It should be noted that the City

10 of Manteca does not have specific policies pertaining to vibration levels; however, vibration levels associated with construction activities and railroad operations are addressed as potential noise impacts associated with project implementation. Goal N-1. Goal N-3. Goal N-4. Goal N-5. Protect the residents of Manteca from the harmful and annoying effects of exposure to excessive noise. Ensure that the downtown core noise levels remain acceptable and compatible with commercial and higher density residential land uses. Protect public health and welfare by eliminating existing noise problems where feasible, by establishing standards for acceptable indoor and outdoor noise, and by preventing significant increases in noise levels. Incorporate noise considerations into land use planning decisions, and guide the location and design of transportation facilities to minimize the effects of noise on adjacent land uses. Policy N-P-2: New development of residential or other noise-sensitive land uses will not be permitted in noise-impacted areas unless effective mitigation measures are incorporated into the project design to satisfy the performance standards in Table 9-1 (see Table ). Table Maximum Allowable Noise Exposure Mobile Noise Sources Outdoor Activity Areas 1 Land Use 4 L dn /CNEL, db Interior Spaces L dn /CNEL, db L eq, db 3 Residential Transient Lodging Hospitals, Nursing Homes Theaters, Auditoriums, Music Halls Churches, Meeting Halls Office Buildings Schools, Libraries, Museums Playgrounds, Neighborhood Parks Outdoor activity areas for residential development are considered to be backyard patios or decks of single family dwellings, and the common areas where people generally congregate for multi-family developments. Outdoor activity areas for non-residential developments are considered to be those common areas where people generally congregate, including pedestrian plazas, seating areas, and outside lunch facilities. Where the location of outdoor activity areas is unknown, the exterior noise level standard shall be applied to the property line of the receiving land use. 2 In areas where it is not possible to reduce exterior noise levels to 60 db L dn or below using a practical application of the best noise-reduction technology, an exterior noise level of up to 65 L dn will be allowed. 3 Determined for a typical worst-case hour during periods of use. 4 Where a proposed use is not specifically listed on the table, the use shall comply with the noise exposure standards for the nearest similar use as determined by the City

11 Policy N-P-3: The City may permit the development of new noise-sensitive uses only where the noise level due to fixed (non-transportation) noise sources satisfies the noise level standards of Table 9-2 (see Table ). Noise mitigation may be required to meet Table 9-2 (see Table ) performance standards. Table Performance Standards for Stationary Noise Sources Or Projects Affected By Stationary Noise Sources 1,2 Noise Level Descriptor Daytime (7 AM to 10 PM) Nighttime (10 PM to 7 AM) Hourly L eq, db Maximum Level, db Each of the noise levels specified above should be lowered by five (5) db for simple noise tones, noises consisting primarily of speech or music, or recurring impulsive noises. Such noises are generally considered by residents to be particularly annoying and are a primary source of noise complaints. 2 No standards have been included for interior noise levels. Standard construction practices should, with the exterior noise levels identified, result in acceptable interior noise levels. Policy N-P-5: In accord with the Table 9-2 (see Table ) standards, the City shall regulate construction-related noise impacts on adjacent uses. Implementation N-I-1. Implementation N-I-3. New development in residential areas with an actual or projected exterior noise level of greater than 60 db L dn will be conditioned to use mitigation measures to reduce exterior noise levels to less than or equal to 60 db L dn. In making a determination of impact under the California Environmental Quality Act (CEQA), a substantial increase will occur if ambient noise levels are increased by 10 db or more. An increase from 5-10 db may be substantial. Factors to be considered in determining the significance of increases from 5-10 db include: the resulting noise levels the duration and frequency of the noise the number of people affected the land use designation of the affected receptor sites public reactions or controversy as demonstrated at workshops or hearings, or by correspondence prior CEQA determinations by other agencies specific to the project Implementation N-I-4. Control noise at the source through use of insulation, berms, building design and orientation, buffer space, staggered operating hours and other techniques. Use noise barriers to attenuate noise to acceptable levels

12 City of Manteca Municipal Code Noise Ordinance Section of the City of Manteca Municipal Code prohibits excessive or annoying noise or vibration to residential and commercial properties in the City. The following general rules are outlined in the ordinance: Prohibited noises - General standard. No person shall make, or cause to suffer, or permit to be made upon any public property, public right-of-way or private property, any unnecessary and unreasonable noises, sounds or vibrations which are physically annoying to reasonable persons of ordinary sensitivity or which are so harsh or so prolonged or unnatural or unusual in their use, time or place as to cause or contribute to the unnecessary and unreasonable discomfort of any persons within the neighborhood from which said noises emanate or which interfere with the peace and comfort of residents or their guests, or the operators or customers in places of business in the vicinity, or which may detrimentally or adversely affect such residences or places of business. (Ord (part), 2007) D. Exempt Activities 8. Construction activities when conducted as part of an approved Building Permit, except as prohibited in Subsection (E)(1) (Prohibited Activities) below E. Prohibited Activities 1. Construction Noise. Operating or causing the operation of tools or equipment on private property used in alteration, construction, demolition, drilling, or repair work daily between the hours of 7:00 PM and 7:00 AM, so that the sound creates a noise disturbance across a residential property line, except for emergency work of public service utilities Impacts and Mitigation Measures Standards of Significance In accordance with Appendix G of the CEQA Guidelines, the City of Manteca has determined that implementation of the project would result in significant noise and vibration impacts if the project would result in any of the following: Exposure of persons to or generation of noise levels in excess of standards established in the Manteca General Plan. Specifically, exterior and interior noise levels of 60 db L dn and 45 db L dn, respectively, for residential uses exposed to transportation noise sources. A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project, defined as an increase of 10 db by the City of Manteca. An increase of 5 to 10 db may be considered substantial according the guidelines outlined in noise Implementation Measure N-I-3 outlined above. A substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project, defined as an increase of 10 db by the City of Manteca. An increase of 5 to 10 db may be considered substantial according the

13 guidelines outlined in noise Implementation Measure N-I-3 outlined above. Exposure of persons to or generation of excessive ground borne vibration or ground borne noise levels. Specifically, a threshold of 0.1 in/sec p.p.v. is considered a safe criterion that would protect against architectural or structural damage and human annoyance. Per Appendix G of the CEQA Guidelines, projects within the vicinity of a public airport or private airstrip could expose people residing or working in the project area to excessive noise and vibration levels. The proposed project is not located within two miles of an airport. Therefore, aircraft noise or vibration would not impact the proposed project and such impacts are not examined further in this Draft EIR. Method of Analysis Below are descriptions of the methodologies utilized to determine traffic noise, as well as construction noise and vibration impacts. Further modeling details and calculations are provided in the Environmental Noise Assessment (see Appendix I). The results of the noise impact analyses were compared to the standards of significance discussed above in order to determine the associated level of impact. Traffic Noise Impact Assessment Methodology To describe future noise levels due to traffic, the FHWA RD was used. Direct inputs to the model included traffic volumes provided by Fehr & Peers. The FHWA model is based upon the Calveno reference noise factors for automobiles, medium trucks and heavy trucks, with consideration given to vehicle volume, speed, roadway configuration, distance to the receiver, and the acoustical characteristics of the site. The FHWA model was developed to predict hourly L eq values for free-flowing traffic conditions. To predict L dn /CNEL values, determination of the day/night distribution of traffic and adjustment of the traffic volume input data is necessary to yield an equivalent hourly traffic volume. It should be noted that the Existing Plus Project conditions, as well as the Cumulative Plus Project conditions were utilized to determine the project-level impacts associated with trafficrelated noise levels. The Cumulative Plus Project condition assumes development of reasonably foreseeable land uses in the City and in adjacent jurisdictions, including pending projects, the proposed project, and buildout of the Manteca and Ripon General Plans. In addition, the Cumulative Plus Project condition assumes various planned roadway improvements in the area. As such, the Cumulative Plus Project condition would represent the maximum increases in traffic and subsequently traffic-related noise. Any noise attenuation features would need to be designed sufficient to reduce the maximum noise levels anticipated to reasonable levels. Because the maximum noise levels would occur during the Cumulative Plus Project condition, noise attenuation features would need to be designed sufficient to reduce unacceptable noise levels under Cumulative Plus Project conditions as well as Existing Plus Project conditions

14 Construction Noise and Vibration Impact Methodology Draft EIR Construction noise and vibration was analyzed using data compiled for various pieces of construction equipment at a representative distance of 50 feet. Construction activities are discussed relative to the applicable City of Manteca noise policies. Project-Specific Impacts and Mitigation Measures The following discussion of impacts is based on the implementation of the proposed project in comparison with the standards of significance identified above Transportation noise impacts to existing sensitive receptors in the project vicinity. Development of the project includes the construction of approximately 706 residential units. Vehicles trips associated with operation of the project would result in changes to traffic on the existing roadway network within the project vicinity. As a result, project buildout would cause an increase in traffic noise levels on the local roadway network. To assess noise impacts due to project-related traffic increases on the existing local roadway network, traffic noise levels are predicted at a representative distance for both existing and cumulative without and with project conditions. Table shows the predicted traffic noise level increases on the local roadway network for Existing and Existing Plus Project conditions. Table shows the predicted traffic noise level increases on the local roadway network for Cumulative and Cumulative Plus Project conditions. As shown in the tables, some noise sensitive receptors located along the project-area roadways are currently exposed to exterior traffic noise levels exceeding the City of Manteca 60 db L dn exterior noise level standard for residential uses. The receptors would continue to experience elevated exterior noise levels with implementation of the proposed project; however, the proposed project s contribution to traffic noise increases is predicted to 5.8 dba L dn, or less, which is less than the City s substantial increase criteria of 10 db. Nonetheless, the City s substantial increase criterion indicates that an increase of 5 dba or more could be considered substantial, and the following factors should be considered: the resulting noise levels; the duration and frequency of the noise; the number of people affected; the land use designation of the affected receptor sites; public reactions or controversy as demonstrated at workshops or hearings, or by correspondence; and prior CEQA determinations by other agencies specific to the project. The 5.8 db increase in noise levels is predicted on Pillsbury Road, south of Woodward Avenue. The resulting noise levels under the Existing Plus Project traffic conditions are predicted to be 55.9 dba L dn. Under the Cumulative Plus Project conditions, traffic noise levels are predicted to be 58.3 db L dn at existing receptors along the roadway segment

15 Table Existing and Existing Plus Project Traffic Noise Levels Noise Levels (L dn, db) at Nearest Sensitive Receptors Distance to Existing + Project Traffic Noise Contours (feet) 1 Roadway Segment Existing Existing + Project Change 70 db L dn 65 db L dn 60 db L dn Atherton Dr West of Main St Atherton Dr Main St to Van Ryn Ave Atherton Dr North of Raymus Expy N/A N/A N/A N/A N/A N/A Austin Dr North of Raymus Expy N/A N/A N/A N/A N/A N/A Austin Dr South of Raymus Expy N/A N/A N/A N/A N/A N/A Austin Rd North of SR 99 Ramp Austin Rd SR 99 Ramp to Moffat Blvd Austin Rd South of Moffat Blvd Main St North of Mission Ridge Dr Main St Mission Ridge Dr to SR 120 WB Ramp Main St SR 120 EB Ramp to Atherton Dr Main St Atherton Dr to Woodward Ave S. Manteca Road South of Woodward Ave S. Manteca Road North of Raymus Expy N/A N/A N/A N/A N/A N/A Mission Ridge Dr West of Main St Moffat Blvd North of Spreckels Ave Moffat Blvd Woodward Ave to SR 99 SB Ramp Moffat Blvd SR 99 SB Ramp to Austin Rd Moffat Blvd East of Austin Rd Pillsbury Rd South of Woodward Ave Raymus Expy West of Main St N/A N/A N/A N/A N/A N/A Raymus Expy Main St to Pillsbury Rd N/A N/A N/A N/A N/A N/A (Continued on next page)

16 Table Existing and Existing Plus Project Traffic Noise Levels Noise Levels (L dn, db) at Nearest Sensitive Receptors Distance to Existing + Project Traffic Noise Contours (feet) 1 Roadway Segment Existing Existing + Project Change 70 db L dn 65 db L dn 60 db L dn Raymus Expy Pillsbury to Atherton Dr N/A N/A N/A N/A N/A N/A Raymus Expy Atherton Dr to Austin Rd N/A N/A N/A N/A N/A N/A Raymus Expy East of Austin Rd N/A N/A N/A N/A N/A N/A Raymus Expy East of Austin Rd N/A N/A N/A N/A N/A N/A Spreckels Ave East of Spreckels Ave Van Ryn Ave Industrial Park Dr to Woodward Ave Woodward Ave West of Main St Woodward Ave Main St to Buena Vista Dr Woodward Ave Buena Vista Dr to Van Ryn Ave Woodward Ave Van Ryn Dr to Pillsbury Rd Woodward Ave Pillsbury Dr to Atherton Dr Woodward Ave Atherton Dr to Moffat Blvd Distances to traffic noise contours are measured in feet from the centerlines of the roadways. 2 Traffic noise levels do not account for shielding from existing noise barriers or intervening structures. Traffic noise levels may vary depending on actual setback distances and localized shielding. Source: j.c. brennan & associates, Inc., Environmental Noise Assessment, January 9,

17 Table Cumulative and Cumulative Plus Project Traffic Noise Levels Noise Levels (L dn, db) at Nearest Sensitive Receptors Distance to Cumulative + Project Cumulat Cumulative + Traffic Noise Contours (feet) 1 Roadway Segment ive Project Change 70 db L dn 65 db L dn 60 db L dn Atherton Dr West of Main St Atherton Dr Main St to Van Ryn Ave Atherton Dr North of Raymus Expy Austin Dr North of Raymus Expy Austin Dr South of Raymus Expy Austin Rd North of SR 99 Ramp Austin Rd SR 99 Ramp to Moffat Blvd Austin Rd South of Moffat Blvd Main St North of Mission Ridge Dr Main St Mission Ridge Dr to SR 120 WB Ramp Main St SR 120 EB Ramp to Atherton Dr Main St Atherton Dr to Woodward Ave S. Manteca Road South of Woodward Ave S. Manteca Road North of Raymus Expy Mission Ridge Dr West of Main St Moffat Blvd North of Spreckels Ave Moffat Blvd Woodward Ave to SR 99 SB Ramp N/A N/A N/A N/A N/A N/A Moffat Blvd SR 99 SB Ramp to Austin Rd Moffat Blvd East of Austin Rd Pillsbury Rd North of Raymus Expy Raymus Expy West of Main St Raymus Expy Main St to Pillsbury Rd (Continued on next page)

18 Table Cumulative and Cumulative Plus Project Traffic Noise Levels Noise Levels (L dn, db) at Nearest Sensitive Receptors Distance to Cumulative + Project Cumulat Cumulative + Traffic Noise Contours (feet) 1 Roadway Segment ive Project Change 70 db L dn 65 db L dn 60 db L dn Raymus Expy Pillsbury to Atherton Dr Raymus Expy Atherton Dr to Austin Rd Raymus Expy East of Austin Rd Raymus Expy East of Austin Rd Spreckels Ave East of Spreckels Ave Van Ryn Ave Industrial Park Dr to Woodward Ave Woodward Ave West of Main St Woodward Ave Main St to Buena Vista Dr Woodward Ave Buena Vista Dr to Van Ryn Ave Woodward Ave Van Ryn Dr to Pillsbury Rd Woodward Ave Pillsbury Dr to Atherton Dr Woodward Ave Atherton Dr to Moffat Blvd Distances to traffic noise contours are measured in feet from the centerlines of the roadways. 2 Traffic noise levels do not account for shielding from existing noise barriers or intervening structures. Traffic noise levels may vary depending on actual setback distances and localized shielding. Source: j.c. brennan & associates, Inc., Environmental Noise Assessment, January 9,

19 The resulting traffic noise levels are not predicted to exceed 60 dba L dn at existing sensitive receptors. Therefore, the increase of 5.8 db L dn would still be considered less than significant relative to the City s substantial increase threshold. Because the proposed project would not result in exterior noise levels at existing noisesensitive residential receptors in excess of the City s 60 db L dn or a substantial permanent increase in ambient noise levels above existing levels, traffic-related noise impacts to existing sensitive receptors would be considered less than significant. Mitigation Measure(s) None required Transportation noise impacts to new sensitive receptors in the project vicinity. Development of the proposed 706 residential units would introduce new sensitive receptors to the area. The new sensitive receptors could be exposed to potentially substantial exterior or interior noise levels associated with nearby transportation noise, including traffic and UPRR activity. Exterior Noise Levels The proposed project includes residential development adjacent to Woodward Avenue to the north, Atherton Drive to the east, and Pillsbury Road to the west. Cumulative Plus Project traffic noise levels were predicted at the proposed residential land uses associated with the project. Table shows the predicted traffic noise levels at the proposed residential uses adjacent to the major project-area arterial roadways. Table also indicates the property line noise barrier heights required to achieve compliance with the exterior noise level standard of 60 db L dn. The modeled noise barriers assume flat site conditions where roadway elevations, base of wall elevations, and building pad elevations are approximately equivalent. As shown in the table, a noise barrier of 6 feet in height would be required along Woodward Avenue in order to achieve compliance with the City s 60 db L dn exterior noise level standard for the proposed residential uses. In addition, a 7-foot-tall barrier would be required for the residential uses located along Atherton Drive. The proposed project site is located approximately 900 feet, or further, from the UPRR line. Based on data in Table , the UPRR line was measured to generate an exterior noise level of 71 dba L dn at a distance of 240 feet. Accordingly, railroad noise levels at the project site were predicted as presented in Table As shown in the table, railroad noise levels are predicted to exceed the City of Manteca 60 db L dn exterior noise level standards, and use of a noise barrier is warranted in order to achieve compliance with the City s standard. A 6-foot-tall noise barrier would be sufficient to reduce noise levels from railroad activity to less than 60 db L dn

20 Table Cumulative Plus Project Transportation Noise Levels at Proposed Residential Uses Approximate Residential 2 Predicted Noise Levels, db L dn Roadway Receptor Description Setback, feet 1 ADT No Wall 6 Wall 7 Wall 8 Wall Traffic Noise Woodward Woodword Park II - Avenue Backyards , Woodward DeJong Property - Avenue Backyards 75 11, Atherton Drive DeJong/Woodward I - Backyards 75 15, Woodward Park - Pillsbury Road Backyards 75 7, Rail Noise DeJong Backyards / First Floor Property Façade 900 Rail Setback distances are measured in feet from the centerlines of the roadways to the center of residential backyards. 2 The modeled noise barriers assume flat site conditions where roadway elevations, base of wall elevations, and building pad elevations are approximately equivalent. -- Meets the City of Manteca exterior noise standard without mitigation. Standard does not apply to second floor facades. Source: j.c. brennan & associates, Inc., Environmental Noise Assessment, January 9, Interior Noise Levels Modern construction typically provides a 25 db exterior-to-interior noise level reduction with windows closed. Accordingly, sensitive receptors exposed to exterior noise levels of 70 db L dn or less would typically comply with the City of Manteca 45 db L dn interior noise level standard. Additional noise reduction measures, such as acoustically rated windows are generally required for exterior noise levels exceeding 70 db L dn. It should be noted that exterior noise levels are typically 2 to 3 db higher at second floor locations, and noise barriers do not reduce exterior noise levels at second floor locations. The proposed residential uses are predicted to be exposed to exterior transportation noise levels ranging between 52 to 66 db L dn on the first floor. Thus, second floor facades are predicted to be exposed to exterior noise levels of up to 55 to 69 db L dn. Based on a 25 db exterior-to-interior noise level reduction, interior noise levels are predicted to range between 30 to 44 db L dn, which would comply with the City of Manteca 45 db L dn interior noise level standard. Accordingly, interior noise mitigation would not be required for the proposed project, assuming that mechanical ventilation is provided to allow residents to keep doors and windows closed, as desired for acoustical isolation

21 Conclusion As discussed above, the interior noise levels expected at the proposed project site would comply with the City s interior noise level standard of 45 db L dn, provided mechanical ventilation is available to allow future residents to keep doors and windows closed. However, noise barriers would be required along Woodward Avenue and Atherton Drive in order to achieve compliance with the City s 60 db L dn exterior noise level standard for the proposed residential uses. In addition, a 6-foot-tall noise barrier would be required to reduce noise levels from railroad activity to less than the 60 db L dn standard (see Figure Noise Barrier Location). Therefore, without mechanical ventilation and implementation of noise barriers, the new sensitive receptors of the proposed project may be exposed to noise levels in excess of established standards, and impacts would be considered potentially significant. Mitigation Measure(s) Implementation of the following mitigation measures would reduce the above impact to a less-than-significant level (a) (b) (c) In conjunction with submittal of Improvement Plans, the applicant shall show on the Improvement Plans that minimum 6-foot-tall sound walls and/or landscaped berms shall be constructed along Woodward Avenue, adjacent to proposed residential uses. Noise barrier walls shall be constructed of decorative concrete masonry unit (CMU) block walls, landscaped berms, or any combination of these materials. Wood is not recommended due to eventual warping and degradation of acoustical performance. The Improvement Plans shall be subject to review and approval by the City Engineer. In conjunction with submittal of Improvement Plans, the applicant shall show on the Improvement Plans that minimum 7-foot-tall sound walls and/or landscaped berms shall be constructed along Atherton Drive, adjacent to proposed residential uses. Noise barrier walls shall be constructed of decorative concrete masonry unit (CMU) block walls, landscaped berms, or any combination of these materials. Wood is not recommended due to eventual warping and degradation of acoustical performance. The Improvement Plans shall be subject to review and approval by the City Engineer. Prior to issuance of Building Permits, the applicant shall show on the plans that mechanical ventilation shall be installed in all residential uses to allow residents to keep doors and windows closed, as desired for acoustical isolation. The plans shall be subject to review and approval by the City Building Official

22 Figure Noise Barrier Location Source: j.c. brennan & associates, Inc., Environmental Noise Assessment, January 9,

23 Construction noise impacts to existing sensitive receptors in the project vicinity. During the construction of the proposed project, including roads, water and sewer lines, and related infrastructure, noise from construction activities would add to the noise environment in the project vicinity. As shown in Table , activities involved in construction would generate maximum noise levels ranging from 76 to 90 db at a distance of 50 feet. Construction activities would be temporary in nature and are anticipated to occur during normal daytime working hours, as regulated by the City of Manteca. Noise would also be generated during the construction phase by increased truck traffic on area roadways, such as truck traffic associated with the transport of heavy materials and equipment to and from construction sites. The noise increase would be of short duration, and would likely occur primarily during daytime hours, as regulated by the City of Manteca. Table Construction Equipment Noise Type of Equipment Maximum Level, db at 50 feet Backhoe 78 Compactor 83 Compressor (air) 78 Concrete Saw 90 Dozer 82 Dump Truck 76 Excavator 81 Generator 81 Jackhammer 89 Pneumatic Tools 85 Source: Roadway Construction Noise Model User s Guide. Federal Highway Administration. FHWA-HEP January According to the City s Municipal Code, construction activities are exempt from noise regulation during the hours of 7:00 AM to 7:00 PM Nonetheless, the proposed project is located adjacent to existing residences to the north and west, and activities associated with project construction could result in a substantial temporary increase in ambient noise levels, with maximum noise levels ranging from 76 to 90 db at 50 feet. Therefore, construction activities would result in periods of elevated noise levels that could result in a potentially significant impact. Mitigation Measure(s) Implementation of the following mitigation measures would mitigate potential impacts to a less-than-significant level (a) Noise-generating activities at the construction site or in areas adjacent to the construction site associated with the proposed project in any way shall adhere to the requirements of the City of Manteca Municipal Code with