3.11 Noise Noise.pdfidentify opportunities to avoid, reduce, or otherwise mitigate potential significant impacts due to ... Noise is defined as unwanted sound. Sound levels are measured

3.0 Setting, Environmental Impact Analysis, Mitigation Measures

3.11 Noise

Los Angeles Community College District 3.11-1 LAMC 2009 Facilities Master Plan DEIR

July 2009

3.11 Noise

As a result of the analysis undertaken in the Initial Study for the proposed 2009 Master Plan, the LACCD determined that the proposed project may result in environmental impacts due to noise. Therefore, this issue is addressed in detailed analysis in this EIR. This analysis was undertaken to identify opportunities to avoid, reduce, or otherwise mitigate potential significant impacts due to noise and to identify potential alternatives.

This noise impact section incorporates a description of the regulatory framework that guides the decision making process, existing conditions of the proposed 2009 Master Plan area, thresholds for determining if the proposed 2009 Master Plan would result in significant impacts, anticipated impacts (direct, indirect, and cumulative), mitigation measures, and level of significance after mitigation. The potential noise impacts have been analyzed in accordance with the methodologies and guidelines from federal and state agencies, the City of Los Angeles, and Appendix G of the California Environmental Quality Act (CEQA) Guidelines.1

Additional background information about noise, including the basic physics of sound generation and propagation and a glossary of acoustic terminology, is presented in Appendix G. This information may be useful in helping the reader become more familiar with the noise-related vocabulary and metrics, and assisting the reader in evaluating the noise issues presented in this Subsequent EIR.

3.11.1 Setting

Noise is defined as unwanted sound. Sound levels are measured on a logarithmic scale in decibels (dB). The most common descriptor of sound and noise associated with community noise measurements is the A-weighted sound pressure level (dBA). It is defined as the sound pressure level in decibels as measured on a sound meter using the A-weighting filter network. The A-weighted frequency filter de-emphasizes the very low and very high frequency components of sound in a manner similar to the frequency response of human hearing, and correlates well with people’s group reactions to sound and environmental noise. All sound levels in this report are A-weighted. Nearly all community noise metrics are expressed in units of dBA. A-weighted sound pressure levels of typical sources of noise are shown in Table 3.11-1.

The ambient sound level is the existing sound level resulting from natural and mechanical sources and human activity considered normally present in a particular area. The ambient noise level is composed of the cumulative sum of all noise sources, both near and far. The background noise level generally describes the mixture of indistinguishable sounds from many sources without any one dominating sound. It is the noise level that exists in the absence of identifiable, sporadic, individual noise events such as those caused by individual automobile pass-bys, aircraft overflights, intermittent dog barking, etc.

Humans are better able to perceive changes in noise level than to absolute noise levels. Potential responses of persons to changes in the noise environment are usually assessed by evaluating differences between the existing and total predicted future noise environments. The following

1 California Code of Regulations, Title 24, Division 6, Chapter 3, Sections 15000-15387. Available at http://ceres.ca.gov/topic/env_law/ceqa/guidelines/ (May 20, 2009)


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relationships of perception and response to quantifiable noise changes are used as a basis for assessing potential effects of these changes in environmental noise level:

● Except in a carefully controlled laboratory condition, a change of 1 dBA is very difficult to perceive.

● In the outside environment, a 3 dBA change is considered just perceptible.

● An increase of 5 dBA is considered readily perceptible and would generally result in a change in community response.

● A 10 dBA increase is perceived as a doubling in loudness and would likely result in a widespread community response.

Table 3.11-1 Sound Levels of Typical Noise Sources and Noise Environments

Noise Source

(at a given distance)

Scale of dBA

Sound Levels Noise Environment

Human Judgment of Noise

Loudness (Relative to a Reference

Loudness of 70 dBs*)

Commercial Jet Take-off (200 ft) 120 Threshold of pain

*32 times as loud

Pile Driver (50 ft) 110 Rock Music Concert *16 times as loud

Ambulance Siren (100 ft)

Newspaper Press (5 ft)

Power Lawn Mower (3 ft)

100 Very loud

*8 times as loud

Motorcycle (25 ft)

Propeller Plane Flyover (1000 ft)

Diesel Truck, 40 mph (50 ft)

90 Boiler Room

Printing Press Plant

*4 times as loud

Garbage Disposal (3 ft) 80 High Urban Ambient

Sound

*2 times as loud

Passenger Car, 65 mph (25 ft)

Vacuum Cleaner (10 ft)

70 Moderately loud

*70 decibels

(Reference loudness)

Normal Conversation (5 ft)

Air Conditioning Unit (100 ft)

60 Data Processing Center

Department Store

*1/2 as loud

Light Traffic (100 ft) 50 Private Business Office *1/4 as loud

Bird Calls (distant) 40 Lower Limit of Urban

Ambient Sound

Quiet

*1/8 as loud

Soft Whisper (5 ft) 30 Quiet Bedroom

20 Recording Studio Very quiet

10

0 Threshold of hearing

Source: Compiled by URS Corporation.

Because environmental noise varies with time, it is beneficial to define certain measurement terms that are used to characterize this fluctuating quantity. The true energy-average level over a specific period is defined as the Equivalent Sound Level (Leq). Leq is the sound pressure level over a time interval that is equivalent to a perfectly constant sound pressure level containing the same acoustic energy over the same interval. Thus, Leq includes all sporadic or transient events occurring during the given event. In terms of community noise, the City of Los Angeles uses the Leq metric to describe ambient noise level.


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In addition to the Leq metric, the statistical distribution of measured sound levels is used to describe the range of noise levels measured during a given period. This metric is presented as LN, which is the sound level exceeded N percent of the time during a given interval. For example, L10 (in dBA) is the sound level exceeded 10 percent of the time and this level is commonly used to represent the peak noise levels of the measurement. L50 is the sound level that is exceeded 50 percent of the time and represents the median sound level. L90 is the sound level exceeded 90 percent of the time and this level represents the background noise levels of the measurement.

Other descriptors of noise are also commonly used to identify noise/land use compatibility guidelines and assist in the prediction of community reaction to adverse effects of environmental noise, including traffic-generated and industrial noise. These descriptors include the Day-Night Noise Level (DNL or Ldn); in California, the Community Noise Equivalent Level (CNEL) descriptor is used. The maximum A-weighted noise level recorded for a single event is defined as Lmax. Each of these descriptors uses units of dBA. Both Ldn and CNEL noise metrics represent 24-hour periods and both apply a time-weighted factor designed to penalize noise events that occur during evening or nighttime hours, when relaxation and sleep disturbance is of more concern. Both the Ldn and CNEL metrics add a 10 dBA penalty to the hourly Leq noise levels from 10:00 p.m. to 7:00 a.m. (nighttime period). The CNEL metric additionally adds a 5 dBA penalty to the hourly Leq noise levels from 7:00 p.m. to 10:00 p.m. (evening period). For CNEL, daytime is defined as the time between 7:00 a.m. to 7:00 p.m., and for Ldn daytime is defined as the time between 7:00 a.m. to 10:00 p.m. The use of either the CNEL or Ldn noise metrics are mandated by state guideline for noise/land use compatibility planning purposes (State of California, General Plan Guidelines, November 1990) and are the predominant metrics used by local governments to describe noise environments within their jurisdictions.

3.11.1.1 Regulatory Setting

Federal

There are no federal noise standards that directly regulate environmental noise related to the construction or operation of the proposed project. With regard to noise exposure and workers, the Office of Safety and Health Administration (OSHA) regulations safeguard the hearing of workers exposed to occupational noise. These regulations are essentially implemented by California OSHA (Cal/OSHA) regulations.

State

The California Department of Health Services (CDHS) has studied the correlation of noise levels and their effects on various land uses and has established guidelines for evaluating the compatibility of various land uses as a function of community noise exposure. California Government Code Section 65302(f) requires each community to prepare and adopt a comprehensive long-range general plan for its physical development containing seven mandatory elements, including a noise element. The noise element must (1) identify and appraise noise problems in the community, (2) recognize Office of Noise Control guidelines, and (3) analyze and quantify current and projected noise levels.


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The California Noise Insulation Standards (California Building Code (CBC), California Code of Regulations (CCR), Title 24, Part 2) regulates the level of external environmental noise allowed within buildings used for residential purposes. While this would include school dormitories, none are planned for LAMC. California also regulates occupational noise exposure from both construction and operation noise.

Local

City of Los Angeles General Plan Noise Element

The City of Los Angeles has adopted local guidelines based on the community noise compatibility guidelines established by CDHS for use in assessing the compatibility of various land use types with a range of noise levels. These guidelines are set forth in the City General Plan Noise Element and are expressed in terms of CNELs. CNEL guidelines for specific land uses are classified into four categories: (1) “normally acceptable,” (2) “conditionally acceptable,” (3) “normally unacceptable,” and (4) “clearly unacceptable.” A CNEL value of 70 dBA is considered the dividing line between a “conditionally acceptable” and “normally unacceptable” noise environment for noise-sensitive land uses, including single-family and multi-family residences and schools.

City of Los Angeles Noise Regulation

The City of Los Angeles Noise Regulation is provided in Chapter 11 of the Los Angeles Municipal Code (Municipal Code). Section 111.02 of the Municipal Code provides procedures and criteria for the measurement of the sound level of “offending” noise sources. These procedures recognize and account for perceived differences in the nuisance level of different types of noise and/or noise sources. Specifically, the procedures provide for a penalty of 5 dBA for steady high-pitched noise or repeated impulsive noises to account for the nuisance nature of these types of noise. Conversely, the procedures provide a credit of 5 dBA for noise occurring less than 15 minutes in a period of 60 consecutive minutes during the day, as short-term noise events are typically less of a nuisance than sustained noise levels. The Municipal Code provides presumed ambient noise levels, where the actual measured ambient conditions are not known or are less than the presumed daytime (7:00 a.m. to 10:00 p.m.) and nighttime (10:00 p.m. to 7:00 a.m.) minimum ambient noise levels defined in Municipal Code Section 111.02. These presumed ambient noise levels are provided in Table 3.11-2.

Figure 3.11-1 presents general guidelines for environmental noise levels and land use compatibility. These guidelines are used by many agencies, environmental planners, and acoustical specialists as a starting point to evaluate the potential for noise impact on and by the project, and are designed to achieve noise-compatibility with respect to the nearby existing uses.


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Figure 3.11-1 Noise Exposure Levels and Land Use Compatibilities


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blank page for back of figure


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Table 3.11-2 City of Los Angeles Presumed Ambient Noise Levels

Presumed Noise Levels (dBA, Leq)

Daytime Nighttime

Land Use Zone (7:00 a.m. to 10:00 p.m.) (10:00 p.m. to 7:00 a.m.)

Residential 50 40

Commercial 60 55

Light Industrial 65 65

Heavy Industrial 70 70

Source: Los Angeles Municipal Code, Chapter 11, Section 111.02

Municipal Code Section 111.03 states the following:

“Where the ambient noise level is less than the presumed ambient noise level designated in this section, the presumed ambient noise level in this section shall be deemed to be the minimum ambient noise level for purposes of this chapter.”

Municipal Code Section 112.05 sets a maximum noise level for powered equipment of 75 dBA at a distance of 50 feet when operated within 500 feet of a residential zone. Compliance with this standard is only required where “technically feasible.” Municipal Code Section 41.40 also prohibits construction between the hours of 9:00 p.m. and 7:00 a.m. Monday through Friday, 6:00 p.m. and 8:00 a.m. on Saturday, and at any time on Sunday. In general, the City of Los Angeles Department of Building and Safety enforces noise ordinance provisions relative to equipment and the Los Angeles Police Department enforces provisions relative to noise generated by people.

In accordance with the Municipal Code, a noise level increase of 5 dBA over the existing average ambient noise level at an adjacent property line is considered a noise violation. This standard applies to: (1) radios, televisions, and similar devices as defined in Municipal Code Section 112.01; (2) air conditioning, refrigeration, heating, pumping, filtering equipment as defined in Municipal Code Section 112.02; (3) powered equipment intended for repetitive use in residential areas and other machinery, equipment, and devices as defined in Municipal Code Section 112.04; and (4) motor vehicles driven on site as defined in Municipal Code Section 114.02.

No specific noise thresholds are provided for “general noise,” except for Article 6 of the Noise Regulation, which makes it “unlawful for any person to willfully make or continue, or cause to be made or continued, any loud, unnecessary, and unusual noise which disturbs the peace or quiet of any neighborhood or which causes discomfort or annoyance to any reasonable person of normal sensitiveness residing in the area.” The Noise Regulation does not provide any definition of “loud” noise.

3.11.1.2 Environmental Setting

The existing noise environment was quantified by a noise measurement survey conducted in the campus environs and nearby off-campus locations. Existing noise levels for various noise sensitive receiver locations off-campus were measured on May 12 through May 14, 2009. Noise measurements were conducted at seven representative locations which included three long-term measurement and four short-term measurements. A map of the noise measurement locations is presented in Figure 3.11-2. Long-term measurements consisted of 24-hour continuous data, while short-term measurement periods were a minimum 1 hour to a maximum 2 hours in duration.


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All sound level meters were set to measure dBA noise levels at the slow meter response setting. Long-term and short-term measurements sites were placed at noise sensitive receivers in key locations around the perimeter of LAMC. Each meter was calibrated before and after each measurement period. Locations where measurements were conducted were considered representative receivers of existing ambient noise levels within the study area. Existing noise levels for long-term and short term sites are presented in Table 3.11-3 and Table 3.11-4, respectively. Ambient conditions at the time of measurement consisted mostly of birds, wind blowing through trees and bushes, and traffic from the roadway.

Long-term sites were selected according to the proximity to either the proposed Athletics Fields or the Nursery Property. Long-term Site 1 (LT-1) was positioned in the backyard of one of the residences in the neighborhood adjacent to the southeast location of the proposed Athletics Fields along Harding Street. Long-term Site 2 (LT-2) was positioned in the backyard of a residence adjacent to Eldridge Avenue across from the golf course. This section of Eldridge Avenue is considered to be the main arterial from the college campus to the Athletic Fields. Long-term Site 3 (LT-3) was positioned in the backyard of a residence on Aztec Street. This residence is adjacent to the Nursery Property.

Short-term sites were also selected according to the proximity of the proposed project. Short-term Site 1 (ST-1) is in a residential area at the north end of the Sylmar Independent Baseball League (SIBL) complex. Short-term Site 2 (ST-2) is across the SIBL complex and the Pacoima Wash. Short-term Site 3 (ST-3) was on Harding Street directly across from the Pacoima Wash and the proposed Athletic Fields, south of the SIBL complex. Short-term Site 4 (ST-4) is on Eldridge Avenue, south of Hubbard Street and north of Pasha Street across from the Main Campus.

3.11.2 Significance Thresholds

Significance thresholds for noise are based on review of Appendix G of the CEQA Guidelines, local standards and regulations, and applicable significance criteria adopted by the City of Los Angeles. Thresholds for construction and operation apply to this project. An impact to noise is considered significant if the project would:

● Expose persons to generation of noise levels in excess of standards established in local general plans or noise ordinances

● Expose persons to generation of excessive groundborne vibration or groundborne noise levels

● Result in substantial permanent increase in ambient noise in the project vicinity

● Result in substantial temporary or periodic increase in ambient noise levels in the project vicinity


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Figure 3.11-2 Location of Noise Measurement Sites


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Table 3.11-3 Long-Term Measurement Data

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3.11.2.1 Construction

Municipal Code Section 112.05 sets a maximum noise level for powered equipment of 75 dBA at a distance of 50 feet when operated within 500 feet of a residential zone. Compliance with this standard is only required where “technically feasible.” This standard differentiates between mobile or stationary pieces of equipment. In addition, the City of Los Angeles CEQA Thresholds Guide provides that a significant impact related to construction noise would result if project construction activities cause the exterior ambient noise level to increase by 5 dBA or more at a noise sensitive use, which in the case of the project alternatives is the property line of any residence. The existing ambient noise levels in the vicinity of the campus were measured between 47.8 and 63.4 dBA Leq; therefore, these significance thresholds for construction range from 52.8 to 68.4 dBA Leq, depending on the specific site.

3.11.2.2 Operations

As discussed above, the City has established community noise compatibility guidelines in the Noise Element of the General Plan. While the City of Los Angeles does not provide a significance threshold in its plan, the City of Los Angeles CEQA Thresholds Guide does provide a numerical significance threshold; therefore, the following thresholds of significance will be applied to the proposed 2009 Master Plan as set forth in the City of Los Angeles CEQA Thresholds Guide, which states that a significant impact related to operational noise would result if:

● The project causes the ambient noise level measured at the property line of affected uses to increase by 3 dBA in CNEL to or within the “normally unacceptable” or “clearly unacceptable” noise/land use compatibility category; or

● The project causes any 5 dBA or greater noise increase.

Municipal Code Section 111.02 provides procedures and criteria for the measurement of the sound level of “offending” noise sources. These procedures recognize and account for perceived differences in the nuisance level of different types of noise and/or noise sources. In accordance with the Municipal Code, a noise level increase of 5 dBA over the existing average ambient noise level at an adjacent property line is considered a noise violation.

The City of Los Angeles Noise Ordinance standard states that the daytime (7:00 a.m. to 10:00 p.m.) Leq should not exceed 50 dBA. Exceedance of this level would be a significant impact.

3.11.3 Environmental Impact Analysis

Noise impacts from the proposed 2009 Master Plan could result from construction activities due to construction equipment and traffic, and from operational activities due to increased traffic, recreational activities, and other LAMC activities. The following is a description of the assessment methodology, Campus impacts, and Athletic Fields impacts from these sources.

3.11.3.1 Methodology

Noise from construction activity is generated by the broad array of powered noise-producing mechanical equipment used in the construction process. This equipment ranges from handheld pneumatic tools to scrapers, bulldozers, and dump trucks. The exact complement of noise-producing equipment that would be in use during any particular period of construction has not yet


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been determined for the proposed 2009 Master Plan. Noisy construction activities could be in progress at more than one part of the proposed 2009 Master Plan site at a given time. However, the noise levels from construction activity during various phases of a typical construction project can be evaluated, and their use provides an acceptable prediction of a project’s potential construction noise impacts. The impact assessment procedure follows Municipal Code Section 112.05 which covers construction noise. The noise metric used to evaluate construction noise impacts is Lmax.

Future noise impacts resulting from vehicular traffic on roadways were modeled using the Federal Highway Administration (FHWA) Highway Traffic Noise Prediction Model (FHWA-RD-77-108) which includes the California-specific vehicle noise curves (CALVENO). The model is used to calculate an energy average noise level for the different classes of vehicles (automobiles, medium truck, heavy trucks) using the roadways. The model also incorporates the total number of vehicles using the road each day, the vehicle speed, and the percentage of vehicles on the road during the three time periods of the day used to calculate CNEL (as listed in Appendix G), in order to calculate the total noise exposure for the roadway for a given case. Site-specific information is entered, such as distances from the roadway to a noise barrier or to the receiver, along with the elevations and heights of the roadway, noise barrier and receiver. The average daily traffic (ADT) volumes for each road segment analyzed are based upon the latest traffic data collected and calculated in the traffic analysis conducted for this study. The noise metric used to evaluate traffic noise impacts is CNEL.

Noise levels from recreational activity generated by the activities occurring on and around the Athletic Fields are assessed based on the use of the public address system and the crowd attendance. The assessment procedure follows Municipal Code Section 111.02. The noise metric used to evaluate noise impacts from recreational activities in and around the Athletic Fields is Leq.

3.11.3.2 Combined Campus and Athletic Fields Impacts

Development of the proposed 2009 Master Plan facilities would result in an increase in traffic on the roadways surrounding the project site, which would result in an increase in noise emanating from these roadways. The most heavily traveled roadways in the vicinity of the proposed 2009 Master Plan area are now (and would continue to be) Harding Street, located on the east side of the Nursery Property; Eldridge Avenue, located in the middle of the project area; and Maclay Street, located near the East Campus. Higher noise levels would be experienced along these streets during the daytime hours when traffic volumes are higher, and lower noise levels are experienced during nighttime hours when traffic volumes are lower.

The traffic volumes associated with the proposed 2009 Master Plan would have the potential to increase roadway noise levels on these and other local roadways in the project area. The traffic analysis examined the projected changes in the ADT volumes for several of the roadways where an increase in traffic due to the project is expected. The projected change in noise level due to the increases in traffic volume was calculated and the results are presented in Table 3.11-5. This table lists the existing traffic volumes and speeds along with the existing noise level at a distance of 50 feet from the centerline of the roadway. Table 3.11-5 also includes the “Future No Project” and “Future Plus Project” traffic volumes, the traffic volume increases due to the project alone, and the increase in noise level due to the increases in project related traffic volumes.

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Table 3.11-5 Existing and Future Roadway Noise Levels (dBA CNEL)

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3.11 Noise


July 2009

The increase in noise levels due to project-related traffic would range from 0 up to 1.6 dB CNEL. The largest increases in traffic noise are expected to occur along Harding Street north of Eldridge Avenue (1.6 dB CNEL), and along Maclay Street west of the driveway leading to SIBL complex (1.3 dB CNEL). There are no noise-sensitive land uses along either of these sections of roadway; therefore, there would be no noise impacts due to project-related traffic along these two roadway sections. No other sections of roadway would experience an increase in noise level of 0.5 dB CNEL or more. Noise level increases of this magnitude are inaudible and are well below the significance threshold of 3 dB; therefore, there would be less-than-significant impact due to project-related traffic noise on any of the roadway segments analyzed.

3.11.3.3 Campus Impacts

Construction

Construction activities would result in a temporary increase in the ambient noise level near the Nursery Property and along Eldridge Avenue. Noise would result from the operation of construction equipment. The increased noise level would be primarily experienced close to the noise source (in the vicinity of the project site). The magnitude of the impact would depend on the type of construction activity, the noise level generated by various pieces of construction equipment, the duration of the construction phase, and the distance between the noise source and receiver. Construction for these two 2009 Master Plan facilities is expected to take place over a period of approximately 12 months.

Studies conducted for the United States Environmental Protection Agency have found that various phases of construction (e.g., clearing and grading, excavation, finishing) generate fairly consistent average noise levels during a particular construction activity. The loudest phases (excavation and finishing) would generate a noise level of 89 dBA2 at a distance of 50 feet from the activity center. Because residences adjacent to the Nursery Property and to the proposed Eldridge Avenue Streetscape Improvements would be as close as 50 feet to the equipment, the maximum construction noise levels at these locations would be as high as 89 dBA Lmax. Some project construction activities would generate noise clearly audible at the nearest residential properties, and noise from construction occurring on the project site could temporarily disrupt noise-sensitive activities at residential areas. This noise would be of limited duration and much of the time would not be at the maximum levels. Nonetheless, maximum construction noise levels would exceed ambient levels (49 to 63 dBA) by 24 to 40 dBA, which would exceed the City’s 5 dBA impact significance threshold. Therefore, for residents near these two 2009 Master Plan facilities, construction noise would be a temporary significant impact.

Operations

To a lesser extent, the noise environment would be affected by LAMC activities, recreational activities, and landscape maintenance activities. Existing noise sensitive receivers adjacent to the Nursery Property will hear noise from these activities. Receivers near roadways around the project site will hear noise from cars and trucks on those roadways. In some cases, the noise emanating from individual cars and trucks can be loud and disturbing. Other sources of noise in the immediate project area include commercial activities (e.g., delivery and refuse trucks, diesel trucks, etc.),

2 FHWA Roadway Construction Noise Model (RCNM), January 2006


3.11 Noise


July 2009

residential activities (e.g., passenger vehicles, people walking their pets, landscape maintenance operations, etc.), and park activities (e.g., bicyclist, walkers/runners, etc.). Because the project would not add to or increase any of these noises or introduce new non-existing noises, impacts from individual noise sources would be less than significant.

Operational activities associated with the development to be located on the Nursery Property would include vehicle traffic in the parking lot, pedestrian traffic from the parking lot to the bungalows, and potentially the operation of air conditioning condenser units. The number of parking spaces planned for the temporary facilities at the Nursery Property is 34. The traffic into and out of the parking area will be traveling at slow speeds and the noise level associated with these operations is expected to be low compared to the existing ambient noise coming from traffic traveling on Hubbard Street. Noise from door and trunk slams and engine start-ups will be heard above the ambient level, however the noise sensitive land uses adjacent to this property will be shielded from parking lot activities by the temporary buildings which will reduce any noise occurring in the parking lot. Any air conditioning units attached to the temporary buildings should be located on the parking lot side of the structure so that the building will provide mitigation to any noise emanating from these units. Noise levels generated by these activities is expected to be less than significant.

The number of parking spaces planned for the permanent facilities at the Nursery Property is 58. As with the temporary facility, the traffic into and out of the parking area will be traveling at slow speeds and the noise level associated with these operations is expected to be low compared to the existing ambient noise coming from traffic traveling on Hubbard Street. The noise sensitive land uses currently on this site will be removed when the permanent buildings are constructed on site. The homes on the east side of Aztec Street will be further away from the parking lot than are the existing homes on the site, and these homes will be partially shielded by the location of the permanent facilities. The air conditioning units for the permanent facilities would be expected to be located near the center of the roofs of the buildings. The perimeter roof line of these building would provide some mitigation to the noise emanating from the roof-top equipment. Noise levels generated by these activities are expected to be less than significant.

3.11.3.4 Athletic Fields Impacts

Construction

Maximum noise levels from construction would produce levels as high as 77 dBA Lmax for the residences nearest the proposed Athletic Fields. Maximum construction noise levels would exceed ambient levels (49 to 63 dBA) by 12 to 28 dBA, which would exceed the City’s 5 dBA impact significance threshold. Therefore, for residents near this part of the project area, construction noise would be a temporary significant impact.

Operations

To estimate the effect of adding sounds from the proposed Athletic Fields, sound level measurements were conducted at the baseball field at El Cariso Regional Park, just north of the Main Campus, during the final game of the regular season, on April 28, 2009. Measurements were taken behind home plate, near the bleachers on the first base side, and at several locations around the perimeter of the outfield in order to quantify sound levels emanating from the ballgame, the crowd, and the public address (PA) system. During the noise measurements, the sound level meter was approximately 20 feet from the bleachers and 75 feet from the single PA loudspeaker. Music,


3.11 Noise


July 2009

player introductions, and other various game announcements originated from the loudspeaker. At the beginning of the game, approximately 30 people were cheering from the bleachers. By the end of the game, however, the number of people in the bleachers grew to between 75 and 100 people. Using the sound level measurement data from the measurement location behind home plate, which was closest to the crowd and the PA loudspeaker, a single point source noise level was calculated.

To model the noise emanating from the proposed Athletic Fields, a computer software modeling program, Cadna/A, was used. Cadna/A is a Windows-based program that allows for the input of sound sources and their corresponding noise source sound power levels. Cadna/A produces accurate sound level predictions at noise-sensitive receptors by taking into account attenuation due to wave divergence, topography, and attenuation due to atmospheric absorption. Detailed terrain files could not be obtained for modeling the proposed Athletic Fields site; however, because terrain files are not used, direct line-of-sight is assumed and this produces a worst-case scenario for predicted noise levels at noise-sensitive receiver locations. Table 3.11-6 displays the results of the ambient noise level survey from ST-1, ST-2, ST-3, LT-1 and LT-2, the five noise measurement sites closest to the proposed Athletic Fields. For the Cadna/A model, a single point source noise level was designed to represent one PA loudspeaker, noise from the baseball game, and noise from the crowd. This point source was then input into the Cadna/A model at six locations within the stands at the baseball field, four locations within the stands at the softball field and four locations within the stands at the soccer field. The number of point sources placed at each athletic field represents the number of bleacher sections planned for each ball field. This configuration illustrates a worst-case scenario because it assumes that games are being played at all three Athletic Fields at the same time. The total projected noise level emanating from all three ball fields was calculated along with the projected noise levels at each of the noise-sensitive receivers nearest the Athletic Fields.

The results of the noise modeling are presented in Figure 3.11-3, which displays a series of noise contours calculated using the Cadna/A model. This figure shows the location of the projected 65 to 35 dBA Leq noise contours from activities at the proposed Athletic Fields. This is a worst-case analysis as noise from cheering crowds and PA systems was modeled at all bleacher sections at all three Athletic Fields at the same time. The noise contour lines extend only to 35 dBA because below that level, the modeled noise level from proposed activities at the Athletic Fields would be less than the lowest measured ambient noise level in the area.

The projected noise level was also calculated at the five community noise-monitoring locations around the Athletic Fields; these results are listed in Table 3.11-6.

Table 3.11-6 Athletic Fields Noise Impacts

Site ID

Measured

Ambient

Noise Level

(dBA Leq)

Modeled Future

Athletic Field

Noise Level

(dBA Leq)

Noise Ordinance Standard

(dBA Leq)

ST-1 47.8 39.4 50.0

ST-2 48.7 36.9 50.0

ST-3 39.3 45.5 50.0

LT-1 53.1 43.3 50.0

LT-2 55.2 40.8 50.0


3.11 Noise


July 2009

Municipal Code Section 111.03 establishes 50 dBA as the minimum ambient noise level; the results of the analysis show that the noise from the proposed Athletic Fields would not exceed the daytime noise ordinance level standard of 50 dBA Leq at any of the noise-sensitive land uses near the Athletic Fields, even under worst case conditions. Therefore, less-than-significant impact is anticipated at these locations.

The proposed Athletic Fields are expected to be built at an elevation below that of the existing golf course directly to the west. The change in topography would result in a surface that may reflect some of the sound emanating from the Athletic Fields back toward the east. Some of the sound energy that hits this sloping surface would be partially absorbed due to the consistence of the soil and the foliage growing on the surface. Some of the sound energy would be diffused due to the angle of the slope and the unevenness of the surface. A very small amount of acoustic energy is expected to be reflected directly back toward the homes east of the Athletic Fields. Due to the distance traveled, the reflected sound levels would be much lower than the direct sound already reaching the noise-sensitive receptors to the east. Given that the direct noise level is less than the noise ordinance level, any reflected noise also would be much less than the noise ordinance level, and the impact from reflected noise would be less than significant.

3.11.3.5 Cumulative Impacts

The potential cumulative impacts of traffic-related noise increases were calculated and the results of that analysis are shown in Table 3.11-5. The cumulative increases take into account increases in traffic due to all of the non-project-related growth in the vicinity of the proposed 2009 Master Plan site, as well as the increase due to the proposed 2009 Master Plan itself. The projected change in noise levels is expected to range from 0.7 dB to 4.4 dB CNEL along the roadways in the area of the project. Two of the largest increases in traffic noise are expected to occur along Harding Street north of Eldridge Avenue (4.4 dB CNEL), and along Maclay Street west of the driveway leading to the SIBL complex (2.3 dB CNEL). There are no noise-sensitive land uses along either of these sections of roadway; therefore, there would be no noise impacts due to project-related traffic along these two roadway sections. All remaining sections of roadway would see a noise level increase of less than 3 dB CNEL. Noise level increases of this magnitude would be difficult to detect and are below the significance threshold of 3 dB; therefore, the cumulative impact due to project-related traffic noise on any of the roadway segments analyzed would be less than significant.

3.11.4 Mitigation Measures for Significant Impacts

Mitigation measures for significant impacts are listed below.

Construction

NOI-1 – Project construction noise would exceed the 5 dB CNEL increase limit as set forth in the City’s CEQA Thresholds Guide.

MM-NOI-1 – The project shall include noise-control measures within the plans, specifications, and estimates (“bid”) documents for each construction project to reduce noise impacts to the extent feasible.


3.11 Noise


July 2009

Figure 3.11-3 Proposed Athletic Fields Noise Contours


3.11 Noise


July 2009



3.11 Noise


July 2009

Impact Number Impact

Mitigation

Measure (MM)

Number Mitigation Measure

Post Mitigation

Level of Impact

Construction

Impact NOI-1 Project construction

noise at the Nursery

Property and

Athletic Fields site

would exceed the

5 decibel CNEL

increase limit as set

forth in the City’s

CEQA Thresholds

Guide

MM NOI-1 Incorporate noise-control measures within

the plans, specifications, and estimates

(“bid”) documents for each construction

project to reduce noise impact, including:

(1) compliance with City of Los Angeles

standards for short-term operation of mobile

equipment and long-term construction

operations of stationary equipment,

including noise levels and hours of operation;

(2) compliance with owner-approved Noise

Control Plan; (3) preparation of readily visible

signs indicating “Noise Control Zone”;

(4) utilization of noise-control devices that

meets original specifications and

performance; (5) usage of fixed noise-

producing equipment to comply with

regulations in the course of project activity;

(6) usage of mobile or fixed noise-producing

equipment that are equipped to mitigate

noise as much as it is practical; (7) use of

electrically-powered equipment; (8) use of

noise control techniques, procedures, and

acoustically treated equipment to minimize

impact noise; (9) erection of temporary noise

barriers and sound-control curtains where

project activity is unavoidably close to noise-

sensitive receptors; (10) use of route based

on the least overall noise impact; (11) use of

project-related vehicles in designated

parking area; (12) location of stockpiles,

staging areas, and other noise-producing

operations as far as practicable from noise-

sensitive receptors; (13) limitation with use

of horns, whistles, alarms, and bells;

(14) avoidance of loudspeaker within

500 feet of the project boundaries;

(15) avoidance of shouting, yelling,

screaming or profanity at location outside

the project site boundaries; (16) limitation of

construction heavy-haul truck traffic

between the hours of 9:30 am and 3:30 pm.

Significant

Operation

No potential impacts are identified

3.11.5 Level of Significance after Mitigation

Even with the implementation of Mitigation Measure MM NOI-1, which includes all feasible mitigation measures, construction noise would remain a significant temporary impact due to the difficulty of quantifying the reduction in noise impacts and due to the proximity of the construction activities to the existing sensitive receptors. Even though the construction noise impacts are temporary, they are significant and unavoidable.

Documents

3.11 Noise Noise.pdfidentify opportunities to avoid, reduce, or otherwise mitigate potential significant impacts due to ... Noise is defined as unwanted sound. Sound levels are measured