NOISE AND VIBRATION IMPACT STUDY - Los Angeles...P:\BRS1601\Noise\Noise_20180423.docx (04/26/18) 5...

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CITY OF LOS ANGELES, LOS ANGELES COUNTY, CALIFORNIA

CITY OF LOS ANGELES, LOS ANGELES COUNTY, CALIFORNIA

Los Angeles, California 90025
(949) 5530666
Project No. BRS1601
NO I S E AND V I B RA T I ON IMPA C T S TUD Y APR I L 2018
PROPO S E D S ING L E FAM I L Y RE S I D EN T I A L DEVE LOPMEN T I N TH E CHA TSWOR TH COMMUN I T Y

TABLE OF CONTENTS
INTRODUCTION ...................................................................................................................................... 1 Project Location ............................................................................................................................................. 1 Project Description ........................................................................................................................................ 1
METHODOLOGY ...................................................................................................................................... 1 CHARACTERISTICS OF SOUND ................................................................................................................ 1
Measurement of Sound ................................................................................................................................. 4 Physiological Effects of Noise ........................................................................................................................ 5
FUNDAMENTALS OF VIBRATION ............................................................................................................ 9 REGULATORY SETTING ......................................................................................................................... 11
Federal Regulations ..................................................................................................................................... 11 Local Regulations ......................................................................................................................................... 12
THRESHOLDS OF SIGNIFICANCE ........................................................................................................... 14 Thresholds of Significance for Noise ............................................................................................................ 14 Thresholds of Significance for Vibration ...................................................................................................... 15
EXISTING SETTING ................................................................................................................................ 15 Land Uses in the Project Vicinity .................................................................................................................. 15 Overview of the Existing Noise Environment............................................................................................... 15 Ambient Noise Measurement ...................................................................................................................... 15 Train Noise ................................................................................................................................................... 16 Traffic Noise ................................................................................................................................................. 16
IMPACTS ............................................................................................................................................... 17 ShortTerm Construction Noise Impacts ...................................................................................................... 17 ShortTerm Construction Vibration Impacts ................................................................................................ 21 LongTerm Train Noise Impacts ................................................................................................................... 22 LongTerm Traffic Noise Impacts ................................................................................................................. 23 LongTerm OffSite Stationary Noise Impacts .............................................................................................. 25 LongTerm Vehicular Traffic Vibration Impacts ........................................................................................... 26
MITIGATION MEASURES ....................................................................................................................... 26 Construction Noise....................................................................................................................................... 26 Construction Vibration ................................................................................................................................. 26 Train Noise Impacts ..................................................................................................................................... 27 Traffic Noise Impacts ................................................................................................................................... 27 Operational/Stationary Sources Noise and Vibration Impacts .................................................................... 27
CONCLUSION ........................................................................................................................................ 27 REFERENCES ......................................................................................................................................... 27


FIGURES AND TABLES
Figure 1: Project Location ....................................................................................................................... 2 Figure 2: Site Plan ................................................................................................................................... 3
TABLES
Table A: Definitions of Acoustical Terms ................................................................................................ 6 Table B: Common Sound Levels and Their Noise Sources ...................................................................... 7 Table C: Land Use Noise Compatibility ................................................................................................... 8 Table D: Human Response to Different Levels of GroundBorne Noise and Vibration ........................ 10 Table E: GroundBorne Vibration and Noise Impact Criteria for General Assessment ........................ 11 Table F: Construction Vibration Damage Criteria ................................................................................. 12 Table G: City of Los Angeles Presumed Ambient Noise Levels............................................................. 14 Table H: ShortTerm Ambient Noise Monitoring Results ..................................................................... 15 Table I: Physical Location of Noise Level Measurements ..................................................................... 16 Table J: Existing (2016) Traffic Noise Levels ......................................................................................... 17 Table K: RCNM Default Noise Emission Reference Levels and Usage Factors ..................................... 18 Table L: Vibration Source Levels for Construction Equipment ............................................................. 22 Table M: Summary of Construction Equipment and Activity Vibration ............................................... 22 Table N: Opening Year Traffic Noise Levels .......................................................................................... 23 Table O: Future BuildOut Year (2030) Traffic Noise Levels ................................................................. 23

LIST OF ABBREVIATIONS AND ACRONYMS
ac acre(s)
dB decibels
FHWA Federal Highway Administration
Hz Hertz
Leq equivalent continuous sound level
Lmax maximum instantaneous noise level
LSA LSA Associates, Inc.
LV velocity in decibels
mph miles per hour
PPV peak particle velocity
STC sound transmission class


INTRODUCTION
This noise and vibration impact study has been prepared to evaluate the potential noise and vibration impacts and mitigation measures associated with the proposed singlefamily residential development in the Chatsworth Community in the City of Los Angeles (City), Los Angeles County, California. This report is intended to satisfy the City’s requirement for a projectspecific noise and vibration impact study by examining the impact of the proposed uses on the project site and evaluating the mitigation measures the project requires.
Project Location
The project site is immediately west of Topanga Canyon Boulevard and approximately 0.5 mile south of the Ronald Reagan (State Route 118) Freeway in the community of Chatsworth, Los Angeles, California. Figure 1 shows the location of the project.
Project Description
The project site itself is generally bound by Old Santa Susana Pass Road on the east, Farralone Avenue on the west, Calle Milagros on the south, and by an existing developed parcel on the north.
The project includes the demolition of two of the existing residential structures, demolition of several old dilapidated accessory buildings, construct 19 singlefamily dwelling units, and rehabilitate an existing historical residential structure on an approximately 12acre site. Vehicular access to the project site will be provided primarily via a new roadway connecting to Old Santa Susana Pass Road and providing internal circulation to most of the new development, although one project lot will be accessed from Farralone Avenue. Figure 2 illustrates the site plan.
METHODOLOGY
The evaluation of the noise and vibration impacts associated with the proposed residential project includes the following:
Determine the shortterm construction noise and vibration impacts on offsite noisesensitive uses.
Determine the longterm mobile and stationary noise impacts.
Determine the required mitigation measures to reduce shortterm and longterm noise and vibration impacts.
CHARACTERISTICS OF SOUND
Noise is usually defined as unwanted sound. Noise consists of any sound that may produce physiological or psychological damage and/or interfere with communication, work, rest, recreation, and sleep.
SOURCE: ESRI World Topographic Map (2016)
I:\BRS1601\G\Project Locaon.cdr (9/14/2017)
FIGURE 1
Project Locaon
Proposed Single-Family Residenal Development in the Chatsworth Community

P:\BRS1601\Noise\Noise_20180423.docx (04/26/18) 4
To the human ear, sound has two significant characteristics: pitch and loudness. Pitch is generally an annoyance, while loudness can affect the ability to hear. Pitch is the number of complete vibrations, or cycles per second, of a wave resulting in the tone’s range from high to low. Loudness is the strength of a sound that describes a noisy or quiet environment and is measured by the amplitude of the sound wave. Loudness is determined by the intensity of the sound waves combined with the reception characteristics of the human ear. Sound intensity refers to how hard the sound wave strikes an object, which in turn produces the sound’s effect. This characteristic of sound can be precisely measured with instruments. The analysis of a project defines the noise environment of the project area in terms of sound intensity and its effect on adjacent sensitive land uses.
Measurement of Sound
Sound intensity is measured through the Aweighted scale to correct for the relative frequency response of the human ear. That is, an Aweighted noise level deemphasizes low and very high frequencies of sound similar to the human ear’s deemphasis of these frequencies. Unlike linear units (e.g., inches or pounds), decibels are measured on a logarithmic scale representing points on a sharply rising curve.
For example, 10 decibels (dB) are 10 times more intense than 1 dB, 20 dB are 100 times more intense, and 30 dB are 1,000 times more intense. Thirty (30) dB represent 1,000 times as much acoustic energy as 1 dB. The decibel scale increases as the square of the change, representing the sound pressure energy. A sound as soft as human breathing is about 10 times greater than 0 dB. The decibel system of measuring sound gives a rough connection between the physical intensity of sound and its perceived loudness to the human ear. A 10 dB increase in sound level is perceived by the human ear as only a doubling of the loudness of the sound. Ambient sounds generally range from 30 dB (very quiet) to 100 dB (very loud).
Sound levels are generated from a source, and their decibel level decreases as the distance from that source increases. Sound dissipates exponentially with distance from the noise source. For a single point source, sound levels decrease approximately 6 dB for each doubling of distance from the source. This dropoff rate is appropriate for noise generated by stationary equipment. If noise is produced by a line source (e.g., highway traffic or railroad operations), the sound decreases 3 dB for each doubling of distance in a hardsite environment. Line source noise in a relatively flat environment with absorptive vegetation decreases 4.5 dB for each doubling of distance.
There are many ways to rate noise for various time periods, but an appropriate rating of ambient noise affecting humans also accounts for the annoying effects of sound. Equivalent continuous sound level (Leq) is the total sound energy of time varying noise over a sample period. However, the predominant rating scales for human communities in the State of California are the Leq and community noise equivalent level (CNEL) or the daynight average level (Ldn) based on Aweighted decibels (dBA). CNEL is the time varying noise over a 24hour period, with a 5 dBA weighting factor applied to the hourly Leq for noises occurring from 7:00 p.m. to 10:00 p.m. (defined as relaxation hours) and 10 dBA weighting factor applied to noise occurring from 10:00 p.m. to 7:00 a.m. (defined as sleeping hours). Ldn is similar to the CNEL scale but without the adjustment for events occurring during the evening hours. CNEL and Ldn are within 1 dBA of each other and are normally exchangeable. The City uses the CNEL noise scale for longterm noise impact assessment.

Other noise rating scales of importance when assessing the annoyance factor include the maximum noise level (Lmax), which is the highest exponential time averaged sound level that occurs during a stated time period. The noise environments discussed in this analysis for shortterm noise impacts are specified in terms of maximum levels denoted by Lmax. Lmax reflects peak operating conditions and addresses the annoying aspects of intermittent noise. Lmax is often used together with another noise scale, or noise standards in terms of percentile noise levels, in noise ordinances for enforcement purposes. For example, the L10 noise level represents the noise level exceeded 10 percent of the time during a stated period. The L50 noise level represents the median noise level. Half the time the noise level exceeds this level, and half the time it is less than this level. The L90 noise level represents the noise level exceeded 90 percent of the time and is considered the background noise level during a monitoring period. For a relatively constant noise source, the Leq and L50 are approximately the same.
Noise impacts can be described in three categories. The first is audible impacts that refer to increases in noise levels noticeable to humans. Audible increases in noise levels generally refer to a change of 3 dB or greater because this level has been found to be barely perceptible in exterior environments. The second category, potentially audible, refers to a change in the noise level between 1 dB and 3 dB. This range of noise levels has been found to be noticeable only in laboratory environments. The last category is changes in noise levels of less than 1 dB, which are inaudible to the human ear. Only audible changes in existing ambient or background noise levels are considered potentially significant.
Physiological Effects of Noise
Physical damage to human hearing begins at prolonged exposure to noise levels higher than 85 dBA. Exposure to high noise levels affects the entire system, with prolonged noise exposure in excess of 75 dBA increasing body tensions, thereby affecting blood pressure and functions of the heart and the nervous system. In comparison, extended periods of noise exposure above 90 dBA would result in permanent cell damage. When the noise level reaches 120 dBA, a tickling sensation occurs in the human ear even with shortterm exposure. This level of noise is called the threshold of feeling. As the sound reaches 140 dBA, the tickling sensation is replaced by the feeling of pain in the ear. This is called the threshold of pain. A sound level of 160 to 165 dBA will result in dizziness or loss of equilibrium. The ambient or background noise problem is widespread and generally more concentrated in urban areas than in outlying less developed areas.
Table A lists definitions of acoustical terms, and Table B shows common sound levels and their noise sources. Table C shows the City’s land use noise compatibility from the City’s Noise Element of the General Plan (City of Los Angeles, February 1999).

Term Definitions
Decibel, dB A unit of level that denotes the ratio between two quantities that are proportional to power; the number of decibels is 10 times the logarithm (to the base 10) of this ratio.
Frequency, Hz Of a function periodic in time, the number of times that the quantity repeats itself in 1 second (i.e., number of cycles per second).
AWeighted Sound Level, dBA
The sound level obtained by use of the Aweighting filter network. The Aweighting filter deemphasizes 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. All sound levels in this report are Aweighted, unless reported otherwise.
L01, L10, L50, L90 The fastresponse, Aweighted noise levels that are equaled or exceeded by a fluctuating sound level for npercent of a stated time period. For example, 1 percent, 10 percent, 50 percent, and 90 percent of the stated period. The L10 level is commonly called the ‘intrusive sound level’ and is near the maximum level in that time period, while the L90 is commonly called the ‘residual sound level’ and is near the minimum level in that period.
Equivalent Continuous Noise Level, Leq
The level of a steady sound that, in a stated time period and at a stated location, has the same Aweighted sound energy as the timevarying sound.
Community Noise Equivalent Level, CNEL
The 24hour Aweighted average sound level from midnight to midnight, obtained after the addition of 5 dBA to sound levels occurring in the evening from 7:00 p.m. to 10:00 p.m. and after the addition of 10 dBA to sound levels occurring in the nighttime between 10:00 p.m. and the following 7:00 a.m.
Day/Night Noise Level, Ldn The 24hour Aweighted average sound level from midnight to midnight, obtained after the addition of 10 dBA to sound levels occurring in the nighttime between 10:00 p.m. and 7:00 a.m.
Lmax, Lmin The maximum and minimum Aweighted sound levels measured on a sound level meter, during a designated time interval, using fastresponse time averaging. The Lmax is equal to the L0 and the Lmin is equal to the L100.
Ambient Noise Level The allencompassing noise associated with a given environment at a specified time. It is usually a composite of sounds from many sources and from many directions, both near and far, with no particular sound source being dominant.
Intrusive The noise that intrudes over and above the existing ambient noise at a given location. The relative intrusiveness of a sound depends upon its amplitude, duration, frequency, time of occurrence, and tonal or informational content, as well as the increment above the ambient noise level.


Table B: Common Sound Levels and Their Noise Sources
Noise Source AWeighted Sound Level in Decibels
Noise Environments
Subjective Evaluations
Near Jet Engine 140 Deafening 128 times as loud
Civil Defense Siren 130 Threshold of Pain 64 times as loud
Hard Rock Band 120 Threshold of Feeling 32 times as loud
Accelerating Motorcycle at a Few Feet Away 110 Very Loud 16 times as loud
Pile Driver; Noisy Urban Street/Heavy City Traffic 100 Very Loud 8 times as loud
Ambulance Siren; Food Blender 95 Very Loud
Garbage Disposal 90 Very Loud 4 times as loud
Freight Cars; Living Room Music 85 Loud
Pneumatic Drill; Vacuum Cleaner 80 Loud 2 times as loud
Busy Restaurant 75 Moderately Loud
Near Freeway Auto Traffic 70 Moderately Loud
Average Office 60 Quiet Onehalf as loud
Suburban Street 55 Quiet
Light Traffic; Soft Radio Music in Apartment 50 Quiet Onequarter as loud
Large Transformer 45 Quiet
Average Residence without Stereo Playing 40 Faint Oneeighth as loud
Soft Whisper 30 Faint
Human Breathing 10 Very Faint Threshold of Hearing
0 Very Faint Source: Compiled by LSA (2016).


Source: City of Los Angeles General Plan Noise Element (1999)

FUNDAMENTALS OF VIBRATION
Vibration refers to groundborne noise and perceptible motion. Groundborne vibration is almost exclusively a concern inside buildings and is rarely perceived as a problem outdoors, where the motion may be discernible; without the effects associated with the shaking of a building, there is less adverse reaction. Vibration energy propagates from a source through intervening soil and rock layers to the foundations of nearby buildings. The vibration then propagates from the foundation throughout the remainder of the structure. Building vibration may be perceived by occupants as the motion of building surfaces, the rattling of items on shelves or hanging on walls, or a lowfrequency rumbling noise. The rumbling noise is caused by the vibration of walls, floors, and ceilings that radiate sound waves. Annoyance from vibration often occurs when the vibration exceeds the threshold of perception by 10 dB or less. This is an order of magnitude below the damage threshold for normal buildings.
Typical sources of groundborne vibration are construction activities (e.g., blasting, pile driving, and operating heavyduty earthmoving equipment), steelwheeled trains, and occasional traffic on rough roads. Problems with both groundborne vibration and noise from these sources are usually localized to areas within approximately 100 ft from the vibration source, although there are examples of groundborne vibration causing interference out to distances greater than 200 ft (FTA 2006). When roadways are smooth, vibration from traffic, even heavy trucks, is rarely perceptible. For most projects it is assumed that the roadway surface will be smooth enough that groundborne vibration from street traffic will not exceed the impact criteria; however, both construction of the project and the delivery truck operations could result in groundborne vibration that may be perceptible and annoying.
Groundborne noise is not likely to be a problem because noise arriving via the normal airborne path will usually be greater than groundborne noise.
Groundborne vibration has the potential to disturb people and damage buildings. It is not uncommon for construction processes (e.g., blasting and pile driving) to cause vibration of sufficient amplitudes to damage nearby buildings (FTA 2006). Groundborne vibration is usually measured in terms of vibration velocity, either the rootmeansquare (RMS) velocity or peak particle velocity (PPV). The RMS is best for characterizing human response to building vibration, and PPV is used to characterize potential for damage. Decibel notation acts to compress the range of numbers required to describe vibration. Vibration velocity level in decibels is defined as:
Lv = 20 log10 [V/Vref]
where Lv is the vibration velocity in decibels (VdB), “V” is the RMS velocity amplitude, and “Vref” is the reference velocity amplitude, or 1 x 106 inches per second (in/sec) used in the United States. Table D illustrates human response to various vibration levels, as described in the Transit Noise and Vibration Impact Assessment (FTA 2006).

Table D: Human Response to Different Levels of GroundBorne Noise and Vibration
Vibration Velocity Level
Human Response LowFrequency1 MidFrequency2
65 VdB 25 dBA 40 dBA Approximate threshold of perception for many humans. Low frequency sound usually inaudible; midfrequency sound excessive for quiet sleeping areas.
75 VdB 35 dBA 50 dBA Approximate dividing line between barely perceptible and distinctly perceptible. Many people find transit vibration at this level annoying. Lowfrequency noise acceptable for sleeping areas; midfrequency noise annoying in most quiet occupied areas.
85 VdB 45 dBA 60 dBA Vibration acceptable only if there are an infrequent number of events per day. Lowfrequency noise annoying for sleeping areas; midfrequency noise annoying even for infrequent events with institutional land uses such as schools and churches.
Source: Transit Noise and Vibration Impact Assessment, Table 71 (FTA 2006). 1 Approximate noise level when vibration spectrum peak is near 30 Hz. 2 Approximate noise level when vibration spectrum peak is near 60 Hz. dBA = Aweighted decibels FTA = Federal Transit Administration
Hz = Hertz VdB = vibration velocity decibels
Factors that influence groundborne vibration and noise include the following:
Vibration Source: Vehicle suspension, wheel types and condition, railroad track/roadway surface, railroad track support system, speed, transit structure, and depth of vibration source
Vibration Path: Soil type, rock layers, soil layering, depth to water table, and frost depth
Vibration Receiver: Foundation type, building construction, and acoustical absorption
Among these factors, there are significant differences in the vibration characteristics when the source is underground compared to at the ground surface. In addition, soil conditions are known to have a strong influence on the levels of groundborne vibration. Among the most important factors are the stiffness and internal damping of the soil and the depth to bedrock.
Experience with groundborne vibration indicates (1) vibration propagation is more efficient in stiff clay soils than in loose sandy soils, and (2) shallow rock seems to concentrate the vibration energy close to the surface and can result in groundborne vibration problems at large distances from a railroad track. Factors including the layering of the soil and the depth to the water table can have significant effects on the propagation of groundborne vibration. Soft, loose, sandy soils tend to attenuate more vibration energy than hard rocky materials. Vibration propagation through groundwater is more efficient than through sandy soils.

REGULATORY SETTING
Federal Regulations
Federal Transit Administration. Based on the Federal Transit Administration (FTA) Transit Noise and Vibration Impact Assessment (2006) and depending on the building category of the nearest buildings adjacent to the project site, the potential construction vibration damage criteria vary. The FTA Transit Noise and Vibration Impact Assessment (2006) includes groundborne vibration and noise impact criteria guidance (Table E).
Table E: GroundBorne Vibration and Noise Impact Criteria for General Assessment
Land Use Category
Frequent Events
Category 1: Buildings where vibration would interfere with interior operations.
65 VdB4 65 VdB4 65 VdB4 N/A5 N/A5 N/A5
Category 2: Residences and buildings where people normally sleep.
72 VdB 75 VdB 80 VdB 35 dBA 38 dBA 43 dBA
Category 3: Institutional land uses with primarily daytime use.
75 VdB 78 VdB 83 VdB 40 dBA 43 dBA 48 dBA
Source: Transit Noise and Vibration Impact Assessment, Table 81 (FTA 2006). 1 “Frequent Events” is defined as more than 70 vibration events of the same source 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 of the same kind per day. This category includes most commuter rail branch lines.
4 This criterion limit is based on levels that are acceptable for most moderately sensitive equipment (e.g., optical microscopes). Vibrationsensitive manufacturing or research will require detailed evaluation to define the acceptable vibration levels. Ensuring lower vibration levels in a building often requires special design of the HVAC systems and stiffened floors.
5 Vibrationsensitive equipment is generally not sensitive to groundborne noise. µin/sec = microinches per second µPa = micropascals dB = decibels
dBA = Aweighted decibels FTA = Federal Transit Administration HVAC = heating, ventilation, and air conditioning
N/A = not applicable VdB = vibration velocity decibels
The criteria presented in Table E account for variation in project types, as well as the frequency of events, which differ widely among transit projects. Although the criteria are provided for community response to groundborne vibration from rail rapid transit systems, they also provide useful guidelines for human response to exposure to vibration in general and are used in this analysis for vibration impact assessment. Table F lists the vibration damage criteria for various structural categories. These are identified by the FTA as criteria that should be used during the environmental impact assessment phase or environmental review process in general to identify problem locations that must be addressed during final design (FTA 2006).

Building Category PPV (in/sec) Approximate Lv 1
Reinforced concrete, steel, or timber (no plaster) 0.5 102
Engineered concrete and masonry (no plaster) 0.3 98
Nonengineered timber and masonry buildings 0.2 94
Buildings extremely susceptible to vibration damage 0.12 90 Source: Table 123. Transit Noise and Vibration Impact Assessment (FTA 2006). 1 RMS VdB re 1 µin/sec. µin/sec = microinches per second in/sec = inches per second Lv = 20 log10 (V/Vref) is the vibration velocity in decibels
PPV = peak particle velocity RMS = root mean square VdB = vibration velocity decibels
Table E (criteria in terms of VdB) and Table F (criteria in terms of in/sec and VdB) are used to evaluate the effects of vibration on human response and structural damage. For example, for a building that is constructed with reinforced concrete with no plaster, the FTA guidelines show that a vibration level of up to 102 VdB (0.5 PPV [in/sec]) (FTA 2006) is considered safe and would not result in any construction vibration damage. For a nonengineered timber and masonry building, the construction vibration damage criterion is 94 VdB (0.2 in/sec).
Local Regulations
City of Los Angeles
General Plan Noise Element. The Noise Element of the City General Plan is intended to identify sources of noise and provide objectives and policies that ensure that noise from various sources does not create an unacceptable noise environment. Overall, the City’s Noise Element describes the noise environment (including noise sources) in the City; addresses noise mitigation regulations, strategies, and programs; and delineates federal, State, and City jurisdiction relative to rail, automotive, aircraft, and nuisance noise.
The City’s noise standards correlate with land use zoning classifications to maintain identified ambient noise levels and to limit, mitigate, or eliminate intrusive noise that exceeds the ambient noise levels within a specified zone. The City has adopted local guidelines based, in part, on the community noise compatibility guidelines established by the Governor’s Office of Planning and Research for use in assessing the compatibility of various land use types with a range of noise levels.
In accordance with the Noise Element of the City’s General Plan, a noise exposure of up to 55 dBA CNEL is considered the most desirable target for the exterior of noisesensitive land uses, or sensitive receptors (e.g., homes, schools, churches, and libraries). It is also recognized that such a level may not always be possible in areas of substantial traffic noise intrusion. The City considers exposures up to 65 dBA CNEL for noisesensitive uses conditionally acceptable if all measures to reduce such exposure have been taken. Noise levels up to 70 dBA CNEL are normally unacceptable and noise levels above 75 dBA CNEL are clearly unacceptable for sensitive receptors.

For the purpose of the noise analysis, LSA used an exterior noise standard of 65 dBA CNEL and an interior noise standard of 45 dBA CNEL to evaluate potential noise impacts for residential land uses. The interior noise standard of 45 dBA CNEL is consistent with California noise insulation standards specified under Title 24 in the California Building Code (California Code of Regulations, Title 24, Part 2).
Municipal Code. The City’s comprehensive noise ordinance, found in Chapter XI of the Los Angeles Municipal Code, sets forth sound measurement and criteria, minimum ambient noise levels for different land use zoning classifications, sound emission levels for specific uses, hours of operation for certain uses, standards for determining when noise is deemed to be a disturbance, and legal remedies for violations. The following discusses specific key provisions of Chapter XI of the Los Angeles Municipal Code.
Chapter XI, Section 112.05 of the Los Angeles Municipal Code prohibits the operation of any powered equipment or powered hand tool that produces a maximum noise level exceeding the following noise limits at a distance of 50 ft from the source of the noise between the hours of 7:00 a.m. and 10:00 p.m. when the source is located within 500 ft of a residential zone:
75 dBA for construction, industrial, and agricultural machinery, including crawlertractors, dozers, rotary drills and augers, loaders, power shovels, cranes, derricks, motor graders, paving machines, offhighway trucks, ditchers, trenchers, compactors, scrapers, wagons, pavement breakers, compressors, and pneumatic or other powered equipment;
75 dBA for powered equipment of 20 horsepower or less intended for infrequent use in residential areas, including chainsaws, log chippers, and powered hand tools; or
65 dBA for powered equipment intended for repetitive use in residential areas, including lawnmowers, backpack blowers, small lawn and garden tools, and riding tractors.
However, the noise limitations would not apply where compliance is deemed technically infeasible, which means that said noise limitations cannot be complied with despite the use of mufflers, shields, sound barriers, and/or other noise reduction devices or techniques during the operation of the equipment. The aforementioned limitations apply only to uses in residential zones or within 500 ft thereof.
In accordance with the Los Angeles 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, television sets, and similar devices as defined in Los Angeles Municipal Code Section 112.01; (2) airconditioning, refrigeration, heating, pumping, and filtering equipment as defined in Los Angeles Municipal Code Section 112.02; (3) powered equipment intended for repetitive use in residential areas and other machinery, equipment, and devices as defined in Los Angeles Municipal Code Section 112.04; and (4) motor vehicles driven on site as

defined in Los Angeles Municipal Code Section 114.02. These standards apply regardless of the off site land use. For the purposes of determining whether a violation of the noise regulations is occurring, the sound level measurements of an offending noise that has a duration of 5 minutes or less during a 1hour period is reduced by 5 dBA to account for people’s increased tolerance for shortduration noise events.
The ambient noise, as defined by the Los Angeles Municipal Code, is the measured noise level averaged over a period of at least 15 minutes (Leq). For the purposes of determining whether a violation of the noise regulations is occurring, the sound level measurements of an offending noise are averaged over a minimum duration of 15 minutes and compared with the baseline ambient noise level. The baseline ambient noise level is the actual measured ambient noise level (without the offending noise source) or the City’s presumed ambient noise level (Table G), whichever is greater. In cases where the actual measured ambient noise level is not known, the City’s presumed ambient noise level will be used as the baseline. As indicated in Table G, the City’s presumed daytime (7:00 a.m. to 10:00 p.m.) ambient equivalent noise level (Leq) for residential and hotel uses is 50 dBA, while the nighttime (10:00 p.m. to 7:00 a.m.) presumed ambient noise level is 40 dBA.
Table G: City of Los Angeles Presumed Ambient Noise Levels
Zone
Day Night
Commercial 60 55
Manufacturing (M1, MR1, and MR2) 60 55
Heavy Manufacturing (M2 and M3) 65 65 Source: City of Los Angeles Municipal Code, Section 111.03, Table II (2013). Note: In this chart, daytime levels are to be used from 7:00 a.m. to 10:00 p.m. and nighttime levels from 10:00 p.m. to 7:00 a.m. dBA = Aweighted decibel(s) Leq = equivalent continuous sound level
The presumed daytime ambient noise level for commercial uses is 60 dBA, while the nighttime presumed ambient noise level is 55 dBA for commercial uses.
In addition, Section 41.40 of the Los Angeles Municipal Code prohibits construction activity (including demolition) and repair work where the use of any power tool, device, or equipment would disturb persons occupying sleeping quarters in any dwelling, hotel, apartment, or other place of residence between the hours of 9:00 p.m. and 7:00 a.m. Monday through Friday, and between 6:00 p.m. and 8:00 a.m. on Saturday, unless the Board of Police Commissioners has authorized such use. All such activities are also prohibited on Sundays and all federal holidays.
THRESHOLDS OF SIGNIFICANCE
Thresholds of Significance for Noise
A project will normally have a significant effect on the environment related to noise if it will substantially increase the ambient noise levels for adjoining areas or conflict with adopted

environmental plans and goals of the community in which it is located. The applicable noise standards governing the project site are the criteria in the City’s Noise Element of the General Plan and Municipal Code.
Thresholds of Significance for Vibration
Federal Transit Administration
The criteria for environmental impact from groundborne vibration are based on the maximum levels for a single event. Table F lists the potential vibration damage criteria associated with construction activities, as suggested in the Transit Noise and Vibration Impact Assessment (FTA 2006).
EXISTING SETTING
Land Uses in the Project Vicinity
Land uses located within the project site include residences and a health service/rehabilitation facility (United Cerebral Palsy). Singlefamily residences are located to the west and south of the project site. The health service/rehabilitation facility is located north of the project site.
Overview of the Existing Noise Environment
Transportation facilities make up the primary existing noise sources in the project area. Traffic on Topanga Canyon Boulevard, Santa Susana Avenue, and other local streets is the primary source of noise in the project vicinity. Other noise sources include train noise.
Ambient Noise Measurement
Ambient noise level measurements were conducted in the project vicinity near the adjacent noise sensitive receiver locations. A shortterm 20minute noise measurement was conducted at two representative sites, one on the east side along Old Santa Susana Pass Road, and the other on the west side of the project site.
Table H lists the noise monitoring results. As shown in Table H, shortterm noise measurements in the project vicinity ranged from 56.6 to 63.5 dBA Leq, with the maximum noise levels ranging from 65.4 to 71.3 dBA Lmax. These noise levels are both higher than the City’s presumed ambient noise level of 50 dBA Leq, and at times are higher than the 75 dBA Lmax maximum noise level.
Table H: ShortTerm Ambient Noise Monitoring Results
Monitor No. Date Start Time Duration dBA Leq dBA Lmax
ST1 August 3, 2016 10:50 AM 20 minutes 63.5 71.3
ST2 August 3, 2016 11:20 AM 20 minutes 56.6 65.4 Source: Compiled by LSA (2017). dBA = Aweighted decibel Leq = equivalent continuous noise level
Lmax = maximum instantaneous noise level ST = shortterm


Table I describes the physical location of the noise measurement locations and noise sources at the noise measurement locations. As shown in Table I, ambient noise sources in the project area include mostly vehicular traffic. Ambient noise levels measured over a short period of time (Leq) represent a snapshot in time of the noise environment, and should not be confused with the 24hour weighted average noise level of the CNEL.
Table I: Physical Location of Noise Level Measurements
Monitor No. Location Description Noise Sources
ST1 Along Old Santa Susana Pass Road. The meter was placed 10 ft west of the curb.
Traffic on Santa Susana Avenue and Topanga Canyon Boulevard.
ST2 On the west side of project site, approximately 300 ft from Old Santa Susana Pass Road.
Traffic on Topanga Canyon Boulevard and Santa Susana Avenue.
Source: Compiled by LSA (2017). ft = foot/feet ST = shortterm
Train Noise
The Union Pacific Railroad (UPRR) tracks, which also carry Amtrak and Metrolink trains, are 600 ft north of the project site. The train crossing data from the Federal Railroad Administration Office of Safety Analysis show that there are a total of 22 freight trains per day. Also, there are a total of five Amtrak trains and 11 Metrolink trains per day based on the Amtrak and Metrolink schedules, respectively, posted on their websites. The FTA’s 2006 Transit Noise and Vibration Impact Assessment manual was used to evaluate train related noise impacts. These trains would operate 7 days per week, 24 hours per day. Similar to vehicular traffic on roadways, train noise is also a line source that would be assumed to have the train along the centerline of the train tracks so that it covers both directions and balances the train noise emissions. Train noise projected from the edge of the train tracks would be the same as train noise projected from the centerline of the train tracks, with a slight modification to the calculation process for the noise source and distance attenuation. Using the FTA’s guidelines, it is calculated that train operations in the study area would result in a noise level of 67.9 dBA CNEL at 50 ft from the train tracks. The project site is 600 ft from the track centerline. Train noise is a line source with 4.5 dBA reduction per doubling of distance (noise reduction from a line source is based on 15Log (D2/D1), where D1 in this case is 50 ft and D2 is the distance from the line source to the location of concern). At this distance, train noise would be reduced to 51.7 dBA CNEL at the northern project boundary. Multiple intervening structures and terrain changes from rail line to the project site would provide a noise reduction of 5 dBA. Therefore, noise levels generated from train operations would be 46.7 dBA CNEL.
Traffic Noise
The Federal Highway Administration (FHWA) Highway Traffic Noise Prediction Model (1977; FHWA RD77108) was used to evaluate trafficrelated noise conditions along roadway segments in the project vicinity. This model requires various parameters, including traffic volumes, vehicle mix, vehicle speed, and roadway geometry to compute typical equivalent noise levels during daytime, evening, and nighttime hours. The resultant noise levels are weighted and summed over 24 hour periods to determine the CNEL values. The standard vehicle mix for Southern California roadways

was used for traffic on this roadway segment. A project specific traffic analysis has not been prepared. Therefore, the potential noise impacts were calculated using the City’s database for traffic volumes along Topanga Canyon Boulevard near Santa Susana Avenue in 2015. An average daily traffic (ADT) volume of 49,100 was calculated for Topanga Canyon Boulevard in the project area in 2016. The traffic noise levels were modeled using vehicle speeds of 45 miles per hour (mph) along Topanga Canyon Boulevard in the project area. Table J provides the traffic noise levels for the existing conditions. These noise levels represent the worstcase scenario, which assumes that no shielding will be provided between the traffic and the location where the noise contours are drawn. Appendix A provides the specific assumptions used in developing these noise levels and model printouts.
Table J: Existing (2016) Traffic Noise Levels
Roadway Segment ADT
(ft)
(ft)
(ft)
Outermost Lane
49,100 101 215 462 72.7
Source: Compiled by LSA (2017). ADT = average daily traffic CNEL = Community Noise Equivalent Level dBA = Aweighted decibels ft = feet
Table J shows that traffic noise levels along Topanga Canyon Boulevard are moderately high. Table J shows that the 70, 65, and 60 dBA CNEL impact zones extend 101, 215, and 462 ft, respectively, from the roadway centerline.
IMPACTS
ShortTerm Construction Noise Impacts
Two types of shortterm noise impacts could occur during project construction. First, construction crew commutes and the transport of construction equipment and materials to the project site would incrementally increase noise levels on access roads leading to the site. Although there would be a relatively high singleevent noise exposure potential at a maximum level of 84 dBA Lmax from trucks passing at 50 ft, the effect on longerterm (hourly or daily) ambient noise levels would be less than 3 dBA. Therefore, shortterm constructionrelated impacts associated with worker commute and equipment transport to the project site would be less than significant.
The second type of shortterm noise impact is related to noise generated during excavation, grading, and building erection on the project site. Construction is completed in discrete steps, each of which has its own mix of equipment, and consequently, its own noise characteristics. These various sequential phases would change the character of the noise generated on the site and, therefore, the noise levels surrounding the site as construction progresses. Despite the variety in the type and size of construction equipment, similarities in the dominant noise sources and patterns of operation allow constructionrelated noise ranges to be categorized by work phase. Table K lists typical construction equipment noise levels recommended for noise impact assessments, based on a

distance of 50 ft between the equipment and a noise receptor, taken from the Federal Highway Administration (FHWA) Roadway Construction Noise Model (RCNM) (FHWA 2006).
Typical noise levels range up to 88 dBA Lmax at 50 ft during the noisiest construction phases. The site preparation phase, which includes excavation and grading of the site, tends to generate the highest noise levels because the noisiest construction equipment is earthmoving equipment. Earthmoving equipment includes excavating machinery (e.g., backfillers, bulldozers, draglines, and front loaders). Earthmoving and compacting equipment includes compactors, scrapers, and graders. Typical operating cycles for these types of construction equipment may involve 1 or 2 minutes of fullpower operation followed by 3 or 4 minutes at lower power settings.
Table K: RCNM Default Noise Emission Reference Levels and Usage Factors
Equipment Description Acoustical
Usage Factor1 Spec. 721.560 Lmax at 50 ft (dBA, slow)
2 Actual Measured Lmax at
50 ft (dBA, slow) 3
All Other Equipment > 5 HP 50 85 N/A4
Auger Drill Rig 20 85 84
Backhoe 40 80 78
Blasting N/A 94 N/A
Chain&

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