Codorniz TR 32070 BRES2014-1080 (Plans 1-3, 4-4 & 4-2) 2013 Code Update - Noise Impact AnalysisNOISE IMPACT ANALYSIS
5:2NDAND .JEFFERSON RESIDENTIAL DEVELOPMENT
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NOISE IMPAC TANALYSI&
57NID AN'DJE FFERSON RESIDENTIAL DEVELOPMENT
LAQUINTA, CALIFORNIA
Prepared for:
RJT Homes,EL
79760 50th Avenue
La QLfinta, California 922.53
june22.2004
1
TABLE OF CONTENTS
INTRODUCTION ....:........................................................... 1 ( Project Description l
Methodology Related to Noise Impact Assessment ................................... 1
Characteristics of Sound ..................................................... 1
•••.•....•.•..•..••••..••
Measurement of Sound •..... ...................... 4
Psychological and Physiological Effects of Noise .................................... 5
EXISTING CONDITIONS......................................................... 9
Sensitive Land Uses in the Project Vicinity ......................................... 9
Overview of the Existing Noise Environment ........................................ 9
Thresholds of Significance 9
IMPACTS AND MITIGATION MEASURES 10
.............................. tf Short -Term Construction -Related Impacts ......... 10
Long -Term Traffic Noise Impacts ................................................ it
MitigationMeasures.......................................................... 15
Level of Significance after Mitigation 16
t
REFERENCES.................................................................. 17
APPENDIX
A: FHWA TRAFFIC NOISE MODEL PRINTOUTS
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FIGURES AND TABLES
FIGURES
Figure 1: Project Location Map ...................................................... 2
Figure 2: Conceptual 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 Compatibility for Exterior Community Noise ........................... 8
Table D: Exterior Noise Standards ................................................... 9
Table E: Typical Construction Equipment Noise Levels .... ............................ 12
Table F: Projected Vehicular Traffic Noise ........................................... 13
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52ND AND JEFFERSON RESIDENTIAL DEVELOPMENT
INTRODUCTION
This noise impact analysis has been prepared for a due diligence effort to evaluate the potential noise
impacts and mitigation measures associated with the residential development on the southeast corner
of 52nd Avenue and Jefferson Street, in the City of La Quinta, California. This report is intended to
{ satisfy the City's reau, it ___mentor a project-suecific noise impact anal sis by examining the impacts of
the proposed noise -sensitive uses on the project site and evaluating the mitigation measures required
as part of the project design.
7 Project Description
Figure 1 illustrates the location of the proposed project, the 52nd and Jefferson Residential
Development. Figure 2 illustrates the project's conceptual site plan. The project site is located in the
City of La Quinta and is generally bounded by 52nd Avenue to the north, Jefferson Street to the west,
and vacant land and existing residences to the south and east. The project site is approximately level
with 52nd Avenue and Jefferson Street in the areas directly adjacent to these roads.
The proposed plan includes development of 109 single-family homes and 36 duplexes, for a total of
145 dwelling units. As this plan illustrates, direct access to the proposed development site will be via
access roads from 52nd Avenue from the west and Jefferson Street from the south.
Methodology Related to Noise Impact Assessment
Evaluation of noise impacts associated with a proposed residential project typically includes the
following:
• Determine the short-term construction noise impacts on off -site noise -sensitive uses
• Determine the long-term traffic noise impacts on on -site noise -sensitive uses
• Determine the required mitigation measures to reduce long -tern, on -site traffic noise impacts
Characteristics of Sound
!' Sound is increasing to such disagreeable levels in our environment that it can threaten our quality of
life. 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.
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L S A FIGURE I
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o 1000 2000 52nd and jefferson Residential
ffzr Project Location
SOURCE: USGS 7.S' QUAD, LA QUINTA, CALIF.
I-.%M3MLacatian.c6 (I0117103)
L S A FIGURE 2
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52ndand Jefferson Residential
SOURCLARS Conceptual Site Plan
. ......... ....... . .. . .....
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LSA ASSOCIATES. INC. NOISE IMPACT AN ALYS IS
JUNE 3004 S2ND AND JEPPERSON
CITY OF LA QUNITA
To the human ear, sound has two significant characteristics: pitch and loudness. Pitch is generally an
annoyance, while loudness can affect our 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 A -weighted scale to correct for the relative frequency
response of the human ear. That is, an A -weighted noise level de-emphasizes low and very high
frequencies of sound similar to the human ear's de -emphasis of these frequencies. Unlike linear
units, such as 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 decibel, 20 decibels are 100 times
more intense, and 30 decibels are 1,000 times more intense. Thirty decibels represent 1,000 times as
much acoustic energy as one decibel. 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 zero decibels. 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 decibel 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 dBA (very quiet) to 100 dBA (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 dBA for each doubling of distance from the
source. This drop-off rate is appropriate for noise generated by stationary equipment. If noise is
produced by a line source, such as highway traffic or railroad operations, the sound decreases 3 dBA
for each doubling of distance in a hard site environment. Line source, noise in a relatively flat
environment with absorptive vegetation, decreases 4.5 dBA for each doubling of distance.
There are many ways to rate noise for various time periods, but an appropriate rating of ambient
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noise affecting humans also accounts for the annoying effects of sound. Equivalent continuous sound
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level (L,,) 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 L., and
community noise equivalent level (CNEL) or the day -night average level (Lb) based on A -weighted
decibels (dBA). CNEL is the time varying noise over a 24-hour. period, with a five dBA weighting
factor applied to the hourly L,, for noises occurring from 7:00 p.m. to 10:00 p.m. (defined as
relaxation hours) and a 10 dBA weighting factor applied to noise occurring from 10:00 p.m. to
7:00 a.m. (defined as sleeping hours). Ld. is similar to the CNEL scale, but without the adjustment for
events occurring during the evening hours. CNEL and L& are within one dBA of each other and are
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LSA ASSOCIATES. INC. NOISE INPACTANALYSIS
JUNE 2004 SIND AND JEPPERSON
CITY OF LAQUNITA
normally exchangeable The City of La Quinta uses the CNEL noise scale for lone term noise impact.
assessment. `
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Other noise rating scales of importance when assessing the annoyance factor include the maximum
noise level (L.,J, which is the highest exponential time averaged sound level that occurs during a
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stated time period. The noise environments discussed in this analysis for short-term noise impacts are
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specified in terms of maximum levels denoted by I., which reflects peak operating conditions and
addresses the annoying aspects of intermittent noise. It 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 Lto noise level represents the noise level exceeded 10 percent of the time
during a stated period. The L30 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 L,, and Lso 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
3.0 dB or greater since 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 1.0 and
3.0 dB. This range of noise levels has been found to be noticeable only in laboratory environments.
The last category is changes in noise level of less than 1.0 dB, which are inaudible to the human ear.
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Only audible changes in existing ambient or background noise levels are considered potentially
significant.
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I Psychological and 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 our 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 decibels, a tickling sensation occurs in the
E human ear even with short-term exposure. This level of noise is called the threshold of feeling. As
the sound reaches 140 decibels, the tickling sensation is replaced by the feeling of pain in the ear.
This is called the threshold of pain. A sound level of 190 decibels will rupture the eardrum and
1 permanently damage the inner ear. 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 "Land Use Compatibility for Exterior Community Use"
recommended by the California Department of Health, Office of Noise Control.
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LSA ASSOCIATES. INC. NOISE IMPACTANALYSIS
JUNE 2004 02ND AND JEPPERSON
CITY OF LA QUNITA
Table A: Definitions of Acoustical Terms
Term
Definitions
Decibel, dB
A unit of level that denotes the ratio between two quantities
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 one second (i.e., number of cycles per second).
A -Weighted Sound
The sound level obtained by use of A -weighting. The A -weighting filter
Level, dBA
de-emphasizes the very low and very high frequency components of the
sound in a manner similar to the frequency response of the human ear and
correlates well with subjective reactions to noise.
All sound levels in this report are A -weighted, unless reported otherwise.
L01, L10, LSot L90
The fast A -weighted noise levels equaled or exceeded by a
fluctuating sound level for 1 percent, 10 percent, 50 percent, and 90 percent
of a stated time period.
Equivalent
The level of a steady sound that, in a stated time period and at a stated
Continuous Noise
location, has the same A -weighted sound energy as the time varying sound.
Level, L
Community Noise
The 24-hour A -weighted average sound level from midnight to midnight,
Equivalent Level,
obtained after the addition of five decibels to sound levels occurring in the
CNEL
evening from 7:00 p.m. to 10:00 p.m. and after the addition of 10 decibels to
sound levels occurring in the night between 10:00 p.m. and 7:00 a.m.
Day/Night Noise
The 24-hour A -weighted average sound level from midnight to midnight,
Level, L&
obtained after the addition of 10 decibels to sound levels occurring in the
night between 10:00 p.m. and 7:00 a.m.
L..' Lm;,
The maximum and minimum A -weighted sound levels measured on a sound
level meter, during a designated time interval, using fast time averaging.
Ambient Noise
The all encompassing noise associated with a given environment at a
Level
specified time, usually a composite of sound from many sources at many
directions, near and far, no particular sound is 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, and time of occurrence and tonal or informational
content as well as the prevailing ambient noise level.
Source: Handbook of Acoustical Measurements and Noise Control, 1991.
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{ LSA ASSOCIATES. INC. NOISE IMPACT ANALYSIS
JUNE 2004 SIND ANDJEPVERSON
CITY OV LA QUNITA
Table B: Common Sound Levels and Their Noise Sources
Noise Source
A -Weighted 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
Garba a"Dis osal
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
%: times as loud
Suburban Street
55
Quiet
Light Traffic; Soft Radio
Music in Apartment
50
Quiet
1/a times as loud
Large Transformer
45
Quiet
Average Residence Without
Stereo Playing
40
Faint
'/e times as loud
Soft Whisper
30
Faint
Rustling Leaves
20
Very Faint
Human Breathing
10
Very Faint
Threshold of
Hearin
0
Very Faint
Source: Compiled by LSA Associates, lnC. 2M.
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LSA ASSOCIATES. INC. NOISE IMPACT ANALYSIS
JUNE 2004 02ND AND JEPPERSON
CITY OP LA QUNITA
Table C: Land Use Compatibility for Exterior Community Noise
Land Use Category
Noise Range (Ldn or CNEL), dB
I
II
III
IV
Passively used open spaces
50
50-55
55-70
70+
Auditoriums, concert halls, amphitheaters
45-50
50-65
65-70
70+
Residential —low density single family, duplex,
mobile homes
50-55
55-70
70-75
75+
Residential —multifamily
50-60
60-70
70-75
75+
Transient lodging —motels, hotels
50-60
60-70
70-80
80+
Schools, libraries, churches, hospitals, nursing
homes
50-60
60-70
70-80
80+
Actively used open spaces —playgrounds,
neighborhood parks
50-67
—
67-73
73+
Golf courses, riding stables, water recreation,
cemeteries
50-70
—
70-80
80+
Office buildings, business commercial and
professional
50-67
67-75
75+
—
Industrial, manufacturing, utilities, agriculture
50-70
1 70-75
75+
—
Noise Range t Normally Acceptable: Specified land use is satisfactory, baseO upon the assumption that any buildings
involved are of normal conventional construction, without any special noise insulation requirements.
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Noise Range II —Conditionally Acceptable: New construction or development should be undertaken only after a detailed
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analysis of the noise reduction requirements is made and needed noise insulation features are included in the design.
Conventional construction, but with closed windows and fresh air supply systems or air conditioning, will normally suffice.
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Noise Range Ill —Normally Unacceptable: New construction or development should generally be discouraged. If new
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construction or development does proceed, a detailed analysis of the noise reduction requirements must be made and needed
noise insulation features included in the design.
Noise Range IV —Clearly Unacceptable: New construction or development should generally not be undertaken.
Source: Office of Noise Control, California Department of Health. 1976.
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LSA ASSOCIATES. I NC. NOISE I MPACT ANALYSIS
JUNE 2004 62ND AND JEFFERSON
CITY OF LA QUNITA
EXISTING CONDITIONS
Sensitive Land Uses in the Project Vicinity
The residences to the east and south of the project site are approximately 50 feet from the project
boundary. Construction on the project site would result in potential noise impacts to these nearest
sensitive uses.
Overview of the Existing Noise Environment
The primary existing noise sources in the project area are transportation facilities. Traffic on-52nd
Avenue, Jefferson Street, and other local streets is the dominant source of ambient noise.
Thresholds of Significance
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 City's noise criteria, which include the City's Noise
Element and Zoning Ordinance.
t City of La Quinta Noise Element. The City in its General Plan indicates that residential uses
impacted by long-term transportation sources such as vveh lar traffic are compatible in areas with
an exterior noise level of 65 dBA CNEL or lower in outdoor living areas. The interior noise standard
is 45 dBA CNEL. For the purposes of is noise impact analysis, residential uses with outdoor active
use areas exposed to noise levels exceeding 65 dBA CNEL would need to be mitigated.
City of La Quinta Zoning Ordinance. Section 9.100.210 of the City's Zoning Ordinance, Noise
Control, establishes exterior noise standards for stationary sources other than construction activities
for residential property, schools, hospitals, churches, and other nonresidential noise -sensitive uses.
Table D lists the exterior noise standards for these uses.
Table D: Exterior Noise Standards
Receiving Land Use
Noise Standard
Time Period
Noise Sensitive
60 dBA
7:00 a.m. - 10:00 p.m.
50 dBA
10:00 p.m. - 7:00 a.m.
Other Nonresidential
75 dBA
7:00 a.m. -10:00 p.m.
65 dBA
10:00 p.m. - 7:00 a.m.
If the noise consists entirely of impact noise, simple tone noise, speech or music, or any combination thereof,
each of the noise levels specified in the table shall be reduced by five (5) dBA.
4 Source: City of La Quinta, Zoning Ordinance.
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43A AS90CIATE9. INC. NOISE IMPACTANAIYSIS
JUNE 2004 92ND ANDJEPYERSON
CITY Of LA QUNITA
It shall be unlawful for any person at any location within the City to create any noise or to allow the
creation of any noise on property owned, leased, occupied or otherwise controlled by such person
when such noise causes the noise level, when measured on any adjacent property, to exceed:
• The noise standard for a cumulative period of more than 30 minutes in any hour;
• The noise standard plus 5 dBA for a cumulative period of more than 15 minutes in any hour:
• The noise standard plus 10 dBA for a cumulative period of more than five minutes in any hour,
• The noise standard plus 15 dBA for a cumulative period of more than one minute in any hour; or
• The noise standard plus 20 dBA for any period of time.
If the ambient, or background, noise level exceeds any of the preceding noise categories, no increase
above such prevailing ambient noise level shall be permitted. Construction activities regulated by
Section 6.08 of the La Quinta Municipal Code are exempt from the noise restrictions of the Zoning
Ordinance.
Municipal Code. Section 6.08, Nuisances, of the La Quinta Municipal Code specifies nuisances and
1 disturbances from construction noise. The permitted hours of construction work are from 7:00 a.m. to
5:30 p.m. Monday through Friday and from 8:00 a.m. to 5:00 p.m. Saturday during the period of
October I through April 30. No construction is permitted on Sundays and government code holidays.
I During the period of May 1 through September 30, the permitted hours of construction for weekdays
(Monday through Friday) are from 6:00 a.m. to 7:00 p.m. Permitted construction hours for Saturdays
are from 8:00 a.m. to 5:00 p.m.
IMPACTS AND MITIGATION MEASURES
Short -Term Construction -Related Impacts
Noise levels from grading and other construction activities for the proposed project may range up to
91 dBA at the closest residences east and south of the project site for very limited times when
construction occurs near the project's boundary. This range of noise levels is similar to ambient
noise from vehicular traffic in the project vicinity. Construction -related noise impacts from the
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proposed project would not be considered adverse; in addition, compliance with the City's
construction hours requirement would reduce the impact to a less than significant level.
Short-term noise impacts would be associated with excavation, grading, and erecting of buildings on
site during construction of the proposed project. Construction -related short-term noise levels would
be higher than existing ambient noise levels in the project area today, but would no longer occur once
construction of the project is completed.
Two types of short-term noise impacts could occur during the construction of the proposed project.
First, construction crew commutes and the transport of construction equipment and materials to the
site for the proposed project would incrementally increase noise levels on access roads leading to the
site. Although there would be a relatively high single -event noise exposure potential causing
intermittent noise nuisance (passing trucks at 50 feet would generate up to a maximum of 87 dBA),
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LSA ASSOCIATES. INC. NOISE IMPACT ANALYSIS
JUNE 2004 S2ND AND JE➢FERSON
CITY OF LA QUNITA
the effect on longer term (hourly or daily) ambient noise levels would be small. Therefore, short-term
construction -related impacts associated with worker commute and equipment transport to the project
site would be less than significant.
The second type of short-term 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
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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 construction -
related noise ranges to be categorized by work phase. Table E lists typical construction equipment noise
levels recommended for noise impact assessments, based on a distance of 50 feet between the
equipment and a noise receptor. Typical noise levels range up to 91 dBA L.. at 50 feet 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 such as 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 one or two minutes of full power operation followed by three or four minutes at lower
power settings.
Construction of the proposed project is expected to require the use of earthmovers, bulldozers, and
water and pickup trucks. This equipment would be used on the project site. Based on the information
in Table E, the maximum noise level generated by each earthmover on the proposed project site is
assumed to be 88 dBA L.. at 50 feet from the earthmover. Each bulldozer would also generate 88
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dBA L.. at 50 feet. The maximum noise level generated by water and pickup trucks is
approximately 86 dBA L.. at 50 feet from these vehicles. Each doubling of the sound sources with
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equal strength increases the noise level by 3 dBA. Assuming that each piece of construction
from level
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equipment operates at some distance the other equipment, the worst -case combined noise
during this phase of construction would be 91 dBA L. at a distance of 50 feet from the active
construction area.
The residences nearest to the project site are about 50 feet to the east of the project boundary. These
residences may be subject to short-term, intermittent, maximum noise reaching 91 dBA L...,
generated by construction activities on the project site. This range of noise levels is higher than
ambient noise from vehicular traffic in the project vicinity. Compliance with the construction hours
specified in the City's Noise Ordinance would reduce the construction noise impacts to less than
significant.
Long -Term Traffic Noise Impacts
Project related long-term vehicular trip increases are anticipated to be small. However, proposed
on -site residential uses would be potentially exposed to traffic noise levels exceeding the exterior
noise standard of 65 dBA CNEL andlor the interior noise standard of 45 dBA CNEL. Mitigation
measures would be required.
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LSA ASSOCIATES, INC. NOISE IMPACT ANALYSIS
June 2004 SIND AND JEPPERSON
CITY OP LA QVNITA
Table E. Typical Construction Equipment Noise Levels
Type of Equipment
Range of
Maximum Sound
Levels Measured
(dBA at 50 feet)
Suggested
Maximum Sound
Levels for Analysis
(dBA at 50 feet)
Pile Drivers, 12,000 to 18,000 fi-lb/blow
81 to 96
93
Rock Drills
83 to 99
96
Jack Hammers
75 to 85
82
Pneumatic Tools
78 to 88
85
Pumps .
74 to 84
80
Scrapers
83 to 91
87
Haul Trucks
83 to 94
88
Cranes
79 to 86
82
Portable Generators
71 to 87
80
Rollers
75 to 82
80
Dozers
77 to 90
85
Tractors
77 to 82
80
Front -End Loaders
77 to 90
86
Hydraulic Backhoe
81 to 90
86
Hydraulic Excavators
81 to 90
86
Graders
79 to 89
86
Air Compressors
76 to 89
86
Trucks
81 to 87
86
Source: Noise I;Onlrol for Buildings and Manutaciunng rlants, Bolt, BCraneK & Newman. I Y57.
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LSA ASSOCIATES. INC. NOISE IMPACT ANALYSIS
JUNE 2004 SIND AND jEPPeQSoN
CITY OF LA QUNITA
It takes a doubling of the traffic volume to have a three decibel increase in traffic noise. Vehicular
traffic trips associated with the proposed project would not result in significant traffic noise impacts
on off -site sensitive uses. However, as shown in Figure 2, the proposed residential units adjacent to
52nd Avenue and Jefferson Street would be potentially exposed to significant traffic noise from the
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street.
The FHWA highway traffic noise prediction model (FHWA RD-77-108) was used to evaluate
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highway traffic -related noise conditions along 52nd Avenue and Jefferson Street in the project
vicinity. For a worst -case scenario analysis, future traffic volumes included in the City's General
Plan (post 2020) build out scenario (Mr. Brian Ching, City of La Quints Public Works/Engineering,
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October 14, 2003) were used in this noise impact analysis. Jefferson Street is categorized as a six -
lane divided Major Arterial that has a projected volume of 30,800 average daily traffic (ADT)
volume north of 52nd Avenue and 47,200 ADT south of 52nd Avenue. Fifty-second Avenue is
categorized as a four -lane divided road that has a projected volume of 32,900 ADT west of Jefferson
Street and 26,900 ADT east of Jefferson Street. Typical vehicle mix for urban areas in Southem
California was used for these two streets. Mitigation measures for the future homes along these
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roadway segments were determined using these worst -case traffic volumes. The modeled 24-hour
CNEL levels are shown in Table F.
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Table F: Projected Vehicular Traffic Noise
Centerline
Centerline
Centerline
to 70 dBA
to 65 dBA
to 60 dBA
CNEL (dBA)
CNEL
CNEL
CNEL
50 feet from
Roadway Segment
ADT
feet
feet
feet
outermost lane
Jefferson Street, north
30,800
94
191
405
71
of 52nd Avenue
Jefferson Street, south
47,200
121
251
537
73
of 52nd Avenue
52nd Avenue, west of
32,900
80
166
354
71
Jefferson Street
52nd Avenue, east of
26,900
71
146
310
70
Jefferson Street
Source: LSA Associates, Inc., October 2003.
Table F provides the traffic noise levels along Jefferson Street and 52nd Avenue adjacent to the
1�^
project site. These noise levels represent the worst -case scenario, which assumes that no shielding is
provided between the traffic and the location where the noise contours are drawn. The specific
assumptions used in developing these noise levels and model printouts are provided in Appendix A.
The proposed project site is directly adjacent to 52nd Avenue north of Jefferson Street and Jefferson
{
Street east of 52nd Avenue. The following identifies potential impact areas along these two roads.
t�
i
t
PARj1330woi9e.wp&C61221043- 13
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LSA ASSOCIATES. INC. NOISE IMPACTANALYSIS
JUNE 2004 52ND ANDJEYPERSON
CITY Of LA QUNITA
Jefferson Street. The property line of proposed dwelling units on lots fronting Jefferson Street is
within 251 feet of the centerline of Jefferson Street; outdoor active use areas, including backyards
and patios that allow recreational uses, would be exposed to traffic noise exceeding 65 dBA CNEL.
g,ar-eass�tosbelow�the-City',�s�noise standard ofbS dBA GNEMThe wall can be the
of a six-foot sound wa 1 o p of a two -foot earthen berm for an effective height of
eight feet.
Typical sound level reduction of buildings in a warm climate such as Southern California is 12 dBA
with windows open and 24 dBA with windows closed (Protective Noise Levels, EPA 550/9-79-100,
November 1978). Any residential structures proposed directly along Jefferson Street that are within
`140"feet of the.c ne erline wuld'Fe impacted -by -traffic noise exceeding 69 dBA CNEL. With
I _i ..
RE -
Windows s open, the interior noise level`would tie°highUthan 45 dBA CNEL. Even with windows
closed. interior noise levels of the_dwellin- units within 1I40Ifeet ofithe roadway 6enteriinemould nc
be reduced to 45 dBA CNEL or lower. These residential structures require building facade upgrades,
suchdo
dd uble-paned windows with sound transmission class (STC) ratings higher than standard
construction (typically in the range of STC 24 to STC 28). Windows with a minimum of STC-32 are
recommended for bedroom windows associated withfrontline units directly adjacent to Jefferson 3
Street and within _1_4O feet of the roadway centerline. An air conditioning system, a form of
mechanical ven ililation, would be required for these frontline units along Jefferson Street that
6e impacted by 57 dBA CNEL-or higher.
Residential structur_es_proposed along Jefferson Street that are more than 140 feet from the roadway
with wind pen, interior noise levels these fron I dwelling units would exceed the 45 dBA
CNEL standard. An air conditioning system, a form of mechanical ventila on; would�be required for
these frontline units along Jefferson Street. With eight -foot sound walls implemented, ground floor
bedrooms would receive a minimum of 6 dBA in noise reduction, in addition to the 12 to 24 dBA
exterior -to -interior noise attenuation.
If outdoor active use areas (balconies or decks that allow recreational uses) on the second floor
proposed for these dwelling units on the side facing Jefferson Street that would be exposed to traffic
noise exceeding the 65 dBA. CNEL standard, mitigation measures, such as combination of
concrete/plexiglass wall with a minimum effective height of five feet, would be required for the
perimeter of the balconies/decks. In addition, mechanical ventilation, such as an air conditioning
system, would also be required. However, small outdoor areas that would not allow recreational uses
would not be considered active use areas and do not require to be sound -attenuated.
52nd Avenue. The property line of proposed dwelling units on lots fronting 52nd Avenue is within
146 feet of the centerline of 52nd Avenue; outdoor active use areas, including backyards and patios
that allow recreational uses, would be exposed to traffic noise exceeding 65 dBA CNEL. A noise
barrier with a minimum height of six feet is required for these frontline units along 52nd Avenue to
1
rP:utjc33Moise.wpda6n2/04> \, 1 / 14
LSA ASSOCIATES, INC. NO[ SE tM PACT AN ALYS IS
JUNE SSO• S=NO ANOJEYPERSON
CITY Of LA OUNITA
i
mitigate the exterior noise in outdoor living areas to below the City's noise standard of 65 dBA
CNEL.
If the residential structures proposed for any of the frontline dwelling units along 52nd Avenue are
within 83 feet of the roadway centerline, where the traffic noise would exceed 69 dBA CNEL,
building facade upgrades such as double -paned windows with a minimum of STC-30 are
recommended. Air conditioning systems, a form of mechanical ventilation, would also be required
for residential structures proposed along 52nd Avenue that would be impacted by 57 dBA CNEL or
higher.
When the structures proposed for these frontline dwelling units are more than 83 feet from the 52nd
Avenue centerline, where the traffic noise would be 69 dBA CNEL or lower, no building facade
upgrades, such as double -paned windows with STC ratings higher than standard construction, are
required. With windows closed, interior noise levels at these frontline dwelling units would be
reduced to 45 dBA CNEL or lower. This range of noise levels is lower than the City's 45 dBA CNEL
"1
noise standard. However, with windows open, the interior noise level would be potentially higher
than 45 dBA CNEL. An air conditioning system, a form of mechanical ventilation, would be required
for these frontline units along 52nd Avenue.
If balconies or decks that allow outdoor recreational uses are proposed for the frontline dwelling
units on the side facing 52nd Avenue, the outdoor active use areas (balconies/decks) on the second
floor would be exposed to traffic noise exceeding the 65 dBA CNEL standard. Mitigation measures,
such as a combination concrete/plexiglass wall with a minimum effective height of five feet, would
be required for the perimeter of the balconies/decks. However, building facade upgrades would still
be required for second -floor bedrooms within 83 feet of the 52nd Avenue centerline. Therefore,
second -floor bedrooms within 83 feet of the roadway centerline and with windows exposed to the
traffic from 52nd Avenue require building facade upgrades such as double -paned windows with an
STC-30 or higher. In addition, mechanical ventilation, such as an air conditioning system, would also
be required. No building facade upgrades are required for second -floor bedrooms more than 83 feet
from the centerline of 52nd Avenue.
Mitigation Measures
Construction Impacts. Construction of the proposed project would potentially result in relatively
high noise levels and annoyance at the closest residences. The following measures would reduce
short-term construction -related noise impacts resulting from the proposed project:
• During all project site excavation and grading on site, the project contractors shall equip all
construction equipment, fixed or mobile, with properly operating and maintained mufflers
consistent with manufacturers' standards.
• The project contractor shall place all stationary construction equipment so that emitted noise is
directed away from sensitive receptors nearest the project site.
• The construction contractor shall locate equipment staging in areas that will create the greatest
distance between construction -related noise sources and noise -sensitive receptors nearest the
project site during all project construction.
PARjt3301Noise.wpd<6/22/04> . 15
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LSA ASSOCIATES. INC. NOISE IMPACT ANALYSIS
JUNE 2004 52NO AND JEPPERSON
CITY OF LA QUNITA
i The permitted hours of construction work are from 7:00 a.m. to 5:30 p.m. Monday through
Friday, and from 8:00 a.m. to 5:00 p.m. Saturday during the period of October 1 through April
30. No construction is permitted on Sundays and government code holidays. During the period of
s May 1 through September 30, the permitted hours of construction for weekdays (Monday
through Friday) are from 6:00 a.m. to 7.00 p.m. Permitted construction hours for Saturdays are
from 8:00 a.m. to 5:00 P.M.
Traffic Noise Impacts. The following mitigation measures shall be implemented for the proposed
project:
• An air conditioning system for all frontline units along Jefferson Street exposed to traffic on
Jefferson Street.
• An eight -foot noise wall along the project's southern property line along Jefferson Street for
dwelling units with outdoor active use areas such as backyards. The eight -foot noise wall can
consist of a six-foot concrete masonry unit wall on top of a two -foot earthen berm.
• Windows with a minimum sound rating of STC-32 for residential structures proposed on
frontline dwelling units along Jefferson Street and within 140 feet of the roadway centerline.
• A combination concrete/plexiglass wall with a minimum effective height of five feet would be
required for the perimeter of the balconies or decks, if proposed, associated with frontline
dwelling units along Jefferson Street that allow outdoor recreational uses and directly exposed to
Jefferson Street traffic.
j A six-foot noise wall along the project's western property line along 52nd Avenue for dwelling
t units with outdoor active use areas such as backyards.
• An air conditioning system for all frontline units along 52nd Avenue exposed to traffic on 52nd
(' Avenue.
• Windows with a minimum sound rating of STC-30 for residential structures proposed on
frontline dwelling units along 52nd Avenue and within 83 feet of the roadway centerline.
• A combination concrete/plexiglass wall with a minimum effective height of five feet would be
required for the perimeter of the balconies and decks, if proposed, associated with frontline
dwelling units along 52nd Avenue that allow outdoor recreational uses and exposed to 52nd
Avenue traffic.
Level of Significance after Mitigation
With implementation of the identified mitigation measures, potential long-term noise impacts would
be reduced to below the level of significance.
PARjt3301Noiu.wpda6/22M:s- 16
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[ LSA ASSOCIATES. INC. NOISE IMPACT ANALYSIS
JUNE 1004 52ND AHD JEVVERSON
CITY OF LA QUNITA
REFERENCES
Bolt, Beranek & Newman. 1987. Noise Control for Buildings and Manufacturing Plants.
i
City of La Quinta. 2002. Noise Element.
City of La Quinta, Municipal Code Noise Ordinance.
�+ City of La Quinta, Zoning Ordinance.
Environmental Protection Agency. November 1978. Protective Noise Levels, EPA 550/9-79-100.
Federal Highway Administration. 1977. Highway Traffic Noise Prediction Model, FHWA RD-77-
108.
PARjt330Woiw.wpdC6/22/049 17
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LSA ASSOCIATES. INC. NOISE IMPACT ANALYSIS
JUNE 2004 52ND AND JEPPERSOH
CITY OF LA QUNITA
APPENDIX A
FHWA TRAFFIC NOISE MODEL PRINTOUTS
PARjt330V4oisc wpdC61 M;30,
TABLE RJT330BT1
FHWA ROADWAY NOISE LEVEL ANALYSIS
RUN DATE: 10/15/03
ROADWAY SEGMENT: JEFFERSON ST N/0 52ND AVENUE
NOTES: POST 2020 GP BUILD OUT TRAFFIC VOLUMES
* * ASSUMPTIONS * *
AVERAGE DAILY TRAFFIC: 30800 SPEED (MPH): 50 GRADE: .5
TRAFFIC DISTRIBUTION PERCENTAGES
DAY EVENING NIGHT
AUTOS
75.51 12.57 9.34
M-TRUCKS
1.56 0.09 0.19
H-TRUCKS
0.64 0.02 0:08
ACTIVE HALF -WIDTH (FT): 36 SITE CHARACTERISTICS: SOFT
* * CALCULATED NOISE LEVELS * *
CNEL AT 50 FT FROM NEAR TRAVEL LANE CENTERLINE (dB) = 70.70
DISTANCE (FEET) FROM ROADWAY CENTERLINE TO CNEL
70 CNEL 65 CNEL 60 CNEL 55 CNEL
94.0 190.6 404.7 869.1
TABLE RJT330BT2
FHWA ROADWAY NOISE LEVEL ANALYSIS
RUN DATE: 10/15/03
ROADWAY SEGMENT: JEFFERSON ST S/O 52ND AVENUE
NOTES: POST 2020 GP BUILD OUT TRAFFIC VOLUMES
* * ASSUMPTIONS
AVERAGE DAILY TRAFFIC: 47200 SPEED (MPH): 50 GRADE: .5
TRAFFIC DISTRIBUTION PERCENTAGES
DAY EVENING NIGHT
AUTOS
75.51 12.57 9.34
M-TRUCKS
1.56 0.09 0.19
H-TRUCKS
0.64 0.02 0.08
ACTIVE HALF -WIDTH (FT): 36 SITE CHARACTERISTICS: SOFT
* * CALCULATED NOISE LEVELS * *
CNEL AT 50 FT FROM NEAR TRAVEL LANE CENTERLINE (dB) = 72.55
DISTANCE (FEET) FROM ROADWAY CENTERLINE TO CNEL
70 CNEL 65 CNEL 60 CNEL 55 CNEL
- 121.0251.4 537.0 1154.8
TABLE RJT330BT3
FHWA ROADWAY NOISE LEVEL ANALYSIS
RUN DATE: 10/15/03
ROADWAY SEGMENT: 52ND AVENUE W/O JEFFERSON ST
NOTES: POST 2020 GP BUILD OUT TRAFFIC VOLUMES
* * ASSUMPTIONS * *
AVERAGE DAILY TRAFFIC: 32900 SPEED (MPH): 45 GRADE: .5
TRAFFIC DISTRIBUTION PERCENTAGES
DAY EVENING NIGHT
AUTOS
75.51 12.57 9.34
M-TRUCKS
1.56 0.09 0.19
H-TRUCKS
0.64 0.02 0.08
ACTIVE HALF -WIDTH (FT): 24 SITE CHARACTERISTICS: SOFT
* * CALCULATED NOISE LEVELS * *
CNEL AT 50 FT FROM NEAR TRAVEL LANE CENTERLINE (dB) = 70.55
DISTANCE (FEET) FROM ROADWAY CENTERLINE TO CNEL
70 CNEL 65 CNEL 60 CNEL 55 CNEL
----------------------------
79.9 165.8 354.2 761.7
TABLE RJT330BT4
FHWA ROADWAY NOISE LEVEL ANALYSIS
RUN DATE: 10/15/03
(" ROADWAY SEGMENT: 52ND AVENUE E/O JEFFERSON ST
l NOTES: POST 2020 GP BUILD OUT TRAFFIC VOLUMES
* * ASSUMPTIONS
AVERAGE DAILY TRAFFIC: 26900 SPEED (MPH): 45 GRADE: .5
TRAFFIC DISTRIBUTION PERCENTAGES
DAY EVENING NIGHT
�?+ AUTOS
75.51 12.57 9.34
M-TRUCKS
1.56 0.09 0.19
H-TRUCKS
0.64 0.02 .0.08
ACTIVE HALF -WIDTH (FT): 24 SITE CHARACTERISTICS: SOFT
* * CALCULATED NOISE LEVELS * *
CNEL AT 50 FT FROM NEAR TRAVEL LANE CENTERLINE (dB) = 69.68
DISTANCE (FEET) FROM ROADWAYCENTERLINE -TO -CNEL
70 CNEL 65 CNEL 60 CNEL 55 CNEL
- --
70.8 145.5 310.0 666.1
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