Noise Element NOISE ELEMENT
CITY OF ENCINITAS GENERAL PLAN
As Amended 9/21/94
TABLE OF CONTENTS
Section Page
Introduction to the Noise Element N-1
Purpose of the Element N-1
Related Plans and Programs N-2
Format and Scope of this Element N-2
Definitions N-2
Noise Element Goals and Policies N-5
Land Use Planning N-5
Related Goals and Policies N-8
Future Noise Environment N-9
Future Noise Exposure N-9
Noise Mitigation Plan N-12
Description of Plan N-12
Noise Reduction Strategies N-12
Noise and Land Use Compatibility Guidelines N-14
LIST OF TABLES
Table Page
Table 1: Noise Policy Matrix N-8
LIST OF FIGURES
Figure Page
Figure 1: Noise Exposure - Future Conditions (Map A) N-10
Figure 1: Noise Exposure - Future Conditions (Map B) N-11
Figure 2: State of California Noise and Land Use
Compatibility Guidelines
INTRODUCTION TO THE NOISE ELEMENT
Purpose of Noise is generally defined as unwanted or unpleasant
Element sound. Of all neighborhood problems reported in a 1975 U.S.
Housing Census survey, traffic-related noise led as the principal
disturbance among those surveys. For most people, the usual
consequences of noise are associated with interference with speech
and other communication, distractions at home and at work,
disturbance of rest and sleep, and the disruption of various
recreational pursuits. The long-term effects of noise are
widespread and include both psychological as well as physiological
effects.
Noise is also a concern among residents of the City. New
development in the City has resulted in a corresponding increase in
traffic which, in turn, has resulted in increased levels of noise.
In addition, a number of areas are experiencing problems from
stationary noise sources such as loud music and talking from
restaurants and businesses.
The State of California recognizes the relationship between noise
and noise-sensitive land uses, and emphasizes the need to control
noise at the local level through land-use regulation. A noise
element as well as other general plan policy and implementing
ordinances (Zoning Code, Noise Ordinance, etc.) are effective tools
in noise reduction and mitigation. Section 65302(g) of the
California Government Code requires that each City have a Noise
Element as part of the General Plan. This Noise Element follows
the guidelines adopted by the Office of Noise Control, pursuant to
Section 46050.1 of the Health and Safety Code.
State guidelines are very specific as to the content of the General
Plan Noise Element. Government Code, Section 65302(f) states that
the noise element should be prepared according to guidelines
established by the State Department of Health Services. At a
minimum, the Government Code requires the element to analyze the
noise levels for:
Highways and freeways;
Primary arterials and major local streets;
Passenger and freight on-line railroad operations and ground
rapid transit systems;
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Commercial, general aviation, heliport, helistop and military
airport operations, aircraft overflights, jet engine test stands,
and all other ground facilities and maintenance functions related
to airport operation;
Local industrial plants, including, but not -limited to railroad
classification yards; and
Other ground sources identified by local agencies as contributing
to the community noise environment.
This element quantifies the community noise environment in terms of noise
exposure contours. These contours serve as guidelines for the
development outlined in the Community Development Element in order to
achieve noise-compatible land uses and to provide baseline levels and
noise source identification for local noise ordinance enforcement.
Related Plans A number of Federal and State agencies have prepared
and Programs guidelines which identify standards and regulations concerning noise
mitigation in both the work place and in residences. The California
Department of Health Office of Noise Control and the U.S. Department of
Housing and Urban Development have identified standards and regulations
concerning noise mitigation. The former published the Guidelines used in
the preparation of this Element.
Format and The Noise Element is by far the most technical of all
Scope of This the elements included in the General Plan and every
Element effort has been made to clearly define terms, explain measurement
techniques and describe the implications of future land use policy on the
noise environment. The format of this element is similar to that of the
other elements. The Noise Element Technical Report describes the
existing noise environment in Encinitas.
Definitions A-Weighted Sound Level (dB(A)): An A-weighted sound level is the sound
pressure level in decibels as measured on a sound level meter using the
A-weighting filter network. The A-weighting filter deemphasizes the very
low and very high frequency components of the sound in a manner similar
to the response of the human ear and provides good correlation with
subjective reactions to noise.
Ambient Noise Level: The combined noise from all sources near and far is
the ambient noise level. The ambient noise level is the existing level
of environmental noise at a location.
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Community Noise Equivalent Level (CNEL): A CNEL is the average
equivalent A-weighted sound level during a 24-hour day, obtained after
addition of 5 decibels to sound levels occurring during the evening from
7 p.m. to 10 p.m. and addition of 10 decibels to sound levels occurring
during the night from 10 p.m. to 7 a.m. The 5 and 10 decibel penalties
are applied to account for increased noise sensitivity during the evening
and nighttime hours. The CNEL represents the daily energy noise exposure
averaged on an annual basis. It is not measured, but is computed.
Day-Night Average Level (Ldn): The average equivalent A-weighted sound
level during a 24-hour day is obtained after addition of ten decibels to
sound levels occurring during the nighttime from 10 p.m. to 7 a.m. The
10 decibel penalty is applied to account for increased noise sensitivity
during the nighttime hours. The Ldn represents the daily energy noise
exposure averaged on an annual basis.
Decibel (dB): A decibel is the unit for measuring sound pressure level
and is equal to 10 times the logarithm (to the base 10) of the ratio of
the measured sound pressure squared to a reference pressure (i.e., 20
micro-pascals) squared.
Equivalent Energy Level (Leq): Leq is the sound level corresponding to a
steady state sound level containing the same total energy as a
time-varying signal over a given sample period. An Leq value is designed
to average all of the loud and quiet sound levels occurring over a time
period.
Intrusive Noise: Intrusive noise in that noise which intrudes over and
above the existing ambient noise at a given location. The relative
intrusiveness of a sound depends upon its amplitude, duration, frequency,
time of occurrence, tonal or informational content, one prevailing
ambient noise level.
L Percentile: L percentiles represent the A-weighted sound level
exceeded for the identified x% of the sample time (eg. L10, L90).
Noise: Noise is any unwanted sound, or sound which is undesirable
because it interferes with speech and hearing, or is intense enough to
damage hearing, or is otherwise annoying.
Noise Contours: The lines drawn about a noise source indicating constant
or equal level of noise exposure are called noise contours.
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Noise Sensitive Land Use: Noise sensitive land uses are land uses
associated with indoor and/or outdoor human activities that may be
subject to stress and/or significant interference from noise. They
include residential (single and multi-family dwellings, mobile home
parks, dormitories, and similar uses); transient lodging (including
hotels, motels, and similar uses); hospitals, nursing homes, convalescent
hospitals, and other facilities for long-term medical care; and public or
private educational facilities, libraries, churches, and other places of
public gathering.
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NOISE ELEMENT GOALS AND POLICIES
Future noise levels, to a great extent, will be determined by the type,
intensity, and location of future development in addition to new roadway
construction. The primary source of noise in the City will continue to
be vehicular traffic travelling on the Interstate and major arterials.
New development will result in increased traffic and possibly even
require new roadways to be constructed. For this reason, it is
imperative that noise considerations be taken into account in future land
use planning.
Land Use The following goals and the supporting policies
Planning emphasize noise reduction through standards, site planning, and in the
construction of new development that focus on noise mitigation. The
Noise Mitigation Plan identifies standards that will be considered in the
planning and construction of new development.
GOAL 1: Provide an acceptable noise environment for existing and future
residents of the City of Encinitas.
POLICY 1.1: Review actions or projects that may have noise generation
potential to determine what impact they may have on existing land uses.
If a project would cause an increase in traffic noise levels, the policy
of the City of Encinitas is to accept an increase up to an Ldn of 55 dB
in outdoor residential use areas without mitigation. If a project would
increase the traffic noise level by more than 5 dB and the resulting Ldn
would be over 55 dB, then mitigation measures must be evaluated. If the
project, or action, would increase traffic noise levels by 3 dB or more
and the resulting Ldn would exceed 60 dB in outdoor use areas in
residential development, noise mitigation must be similarly evaluated.
The impact of non-transportation projects must generally be evaluated on
a case-by-case basis. The following guidelines will aid in evaluating
the impacts of commercial and industrial projects.
a) Performance Standards Adjacent to Residential Areas. New
commercial construction adjacent to residential areas should not
increase noise levels in a residential area by more than 3 dB (Ldn)
or create noise impacts which would increase noise levels to more
than an Ldn of 60 dB at the boundary of the nearest residential
area, whichever is more restrictive.
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b) Performance Standards Adjacent to Commercial and Industrial Areas.
New commercial projects should not increase noise levels in a commercial
area by more than 5 dB (Ldn) or increase noise levels to an Ldn in excess
of 70 dB (office buildings, business and professional) or an Ldn of 75 dB
(industrial) at the property line of an adjacent commercial/industrial
use, whichever is more restrictive.
These criteria may be waived if, as determined by a noise analysis, there
are mitigating circumstances (such as higher existing noise levels)
and/or no uses would be adversely affected. Where conditions are unusual
or where backgrounds are unusually low and the characteristics of a new
noise source are not adequately described by using the Ldn noise
descriptor, additional acoustical analysis is encouraged and the
conclusions of such analysis will be considered by the City.
POLICY 1.2: An Ldn of 60 dB is the maximum acceptable outdoor noise
level in residential outdoor use areas. The City recognizes that there
are residential areas in which existing noise levels exceed an acceptable
level. The City will adopt a Noise Wall/Barrier Installation Policy for
determining which areas should receive soundwalls along the major street
system and to evaluate possible cost participation programs for
constructing these soundwalls.
POLICY 1.3: To further improve the noise environment in the City of
Encinitas, the police department will enforce the provisions in Sections
27-150 and 27-151 of the California State Motor Vehicle Code. These
sections require that all vehicles be equipped with a properly maintained
muffler and that exhaust systems not be modified.
POLICY 1.4: The City will limit truck traffic in residential and
commercial areas to designated truck routes. Limit construction,
delivery, and through truck traffic to designated routes. Distribute
maps of approved truck routes to City traffic officers.
POLICY 1.5: The City will establish and maintain coordination among
City, County, and State agencies involved in noise abatement and other
agencies to reduce noise generated from sources outside the City's
jurisdiction.
POLICY 1.6: Include noise mitigation measures in
the design of new roadway projects recognizing that
driveways, street openings, and other existing site conditions make noise
mitigation impossible.
Policy 1.6
Amended
9/21/94
N-6
POLICY 1.7: Apply Title 24 of the California Administrative Code,
associated with noise insulation standards, to single-family dwellings.
POLICY 1.8: Establish noise standards for all types of noise not already
identified in the General Plan or governed by existing ordinances.
GOAL 2: Require that new development be designed to provide acceptable
indoor and outdoor noise environments.
POLICY 2.1: Figure 2, the Noise and Land Use Compatibility Guidelines,
and the accompanying discussion set forth the criteria for siting new
development in the City of Encinitas. Any project which would be located
in a normally unacceptable noise exposure area, based on the Land Use
Compatibility Guidelines, shall require an acoustical analysis. Noise
mitigation in the future shall be incorporated in the project as needed.
As a condition of approval of a project, the City may require
post-construction noise monitoring and sign off by an acoustician to
ensure that City requirements have been met.
GOAL 3: Ensure that residents are protected from harmful and irritating
noise sources to the greatest extent possible.
POLICY 3.1: The City will adopt and enforce a quantitative noise
ordinance to resolve neighborhood conflicts and to control unnecessary
noise in the City of Encinitas. Examples of the types of noise sources
that can be controlled through the use of a quantitative noise ordinance
are barking dogs, noisy mechanical equipment such as swimming pool and
hot tub pumps, amplified music in commercial establishments, etc.
GOAL 4: Provide for measures to reduce noise impacts from stationary
noise sources.
POLICY 4.1: Ensure inclusion of noise mitigation measures in the design
and operation of new and existing development.
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Related Goals Goals and policies contained in other elements
and Policies included in the General Plan will also be effective in reducing
noise levels or mitigating the effects of noise. Policies that
relate directly or indirectly with those included in this element
are identified in Table 1, Noise Policy Matrix.
Table 1
NOISE POLICY MATRIX
Resource
Issue Area Land Use Management Recreation Circulation
Land Use X X X
Planning
Noise X X
Abatement
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FUTURE NOISE ENVIRONMENT
Future Noise
Exposure Future transportation noise exposure levels
have been calculated for Post 2010 traffic
conditions. The resulting noise exposure
contours in Ldn are shown on Figure 1.
Noise levels along the most heavily traveled
streets and highways (Interstate 5, Encinitas
Boulevard, El Camino Real and La Costa Avenue)
are calculated to increase by 1-2 decibels Ldn
over existing levels. Noise levels along some
of the streets serving the eastern portion of
the City, where new development is expected to
occur, will receive significantly greater
increases of traffic. Mountain Vista,
Manchester Avenue and Quail Gardens Road are
examples of streets that will carry
significantly greater traffic volumes in the
future. Noise levels along these streets will
increase by up to 5 decibels Ldn over existing
levels.
Noise conditions along the AT & SF Railroad are
not projected to change significantly in the
future. The resulting noise exposure in the
Pacific Highway First Street/AT & SF Railroad
corridor is not expected to be significantly
different in the future. However, noise
conditions along this corridor are directly
related to the frequency of trains on a daily
basis. Establishment of intercity commuter rail
service, and upgrade and expansion of AMTRAK
service between San Diego and Los Angeles, are
now being planned along the AT & SF Railroad
corridor. To the extent that the daily number of
trains using the corridor increases in the
future, land uses along the corridor will be
exposed to the resulting noise increase.
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NOISE MITIGATION PLAN
In some situations it is necessary to construct
noise- sensitive developments in noisy areas. The
following discussion of noise reduction strategies
is intended to provide an overview of the kinds of
steps that can be taken to reduce or eliminate noise
impacts. Noise control engineering is a complex
discipline. Any proposed solutions to noise
problems must not interfere with structural,
architectural, or building code requirements. Noise
mitigation measures should also be assessed against
other community values such as open space,
aesthetics, and maintenance problems. Each project
has its own special problems, and mitigation
measures which are cost-effective for one project
may not be for another. Regardless of the measures
employed for a project, mitigation is always cheaper
and generally more effective if it is included
during the design phase of a project.
The measures or combinations of measures used to
mitigate noise fall into four major categories:
Site Planning
Architectural Layout
Noise Barriers
Construction Modifications
Site Planning
Proper site planning to reduce noise impacts is
the first area that should be investigated for a
given project. By taking advantage of the natural
shape and terrain of the site, it is often possible
to arrange the buildings and other uses in a manner
which will reduce and possibly eliminate noise
impact. Planned unit developments are particularly
conducive to site planning techniques. Site
planning techniques include:
1) Increasing the distance between the noise
source and the receiver
2) Placing non-noise sensitive land uses such as
parking lots, maintenance facilities, and
utility areas between the source and the
receiver.
3) Using non-noise sensitive structures such as
garages to shield noise-sensitive areas.
4) Orienting buildings to shield outdoor spaces
from a noise source.
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Description
of Plan
Noise Reduction
Strategies
Architectural Layout
In many cases noise reduction requirements can be
met by giving attention to the layout of
noise-sensitive spaces. Bedrooms, for example, will
be considerably quieter if placed on the side of the
housing facing away from the freeway. Similarly,
balconies facing freeways should be avoided. Quiet
indoor spaces can be provided next to a noisy
highway by creating a U-shaped development which
faces away from the highway. Proper architectural
layout can often eliminate the need for costly
construction modifications.
Noise Barriers
Noise barriers or walls are commonly used to reduce
noise levels from ground transportation noise
sources and industrial sources. Noise barriers
serve a dual purpose in that they can reduce the
noise level both outdoors and indoors.
To be effective, a noise barrier must be massive
enough to prevent significant noise transmission
through it and high enough and long enough to shield
the receiver from the noise source. A safe minimum
surface weight for a noise barrier is 3.5
pounds/square foot (equivalent to 3/4-inch plywood),
and the barrier must be carefully constructed so
that there are no cracks or openings. To be
effective, a barrier must interrupt the
line-of-sight between the noise source and the
receiver. To illustrate this relationship, consider
a flat area with a housing tract next to a road. If
there are no diesel trucks on the road, a 7-foot
high barrier will reduce the traffic noise by about
8 dB(A). If there are trucks, then the noise from
the trucks will be reduced only by about 4 dB(A).
The reason is that the stacks of the diesel trucks
will be visible above the barrier and the direct
noise path will not be completely interrupted.
Another important and often overlooked consideration in
the design of noise barriers is the phenomenon of
"flanking." Flanking is a term used to describe the
manner by which a noise barrier's performance is
compromised by noise passing around the end of a
barrier. Short barriers regardless of height
provide essentially no reduction in the overall
noise level. The effects of flanking can be
minimized by bending the wall back from the noise
source at the ends of the barrier.
In addition to meeting acoustical requirements,
noise barriers must be evaluated for possible
maintenance problems, aesthetic and environmental
considerations, safety conflicts, and cost.
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Construction Modifications
If site planning, architectural layout, noise
barriers, or a combination of these measures does not
achieve the required noise reduction for the building,
it will be necessary to modify the building's
construction. Indoor noise levels from exterior
sources are controlled by the noise reduction
characteristics of the building shell. The walls,
roof, ceilings, doors, windows and other penetrations
are all determinants of the structure's overall noise
reduction capabilities.
In general, windows and doors are the acoustical weak
links in a building. Often all that is required is
that the windows be sealed on the noisy side of the
building and an alternative means of ventilating the
building provided. Beyond this, thicker windows or
double-glazed windows will be required. Doors should
not be located on the side of the building facing a
noise source. If they are, they should be solid-core
doors and should be equipped with an appropriate
acoustical door gasket. In cases in which more noise
reduction is required, the ceiling/roof and/or the
walls must be modified to provide the required noise
reduction. The actual modifications will depend on
the amount of noise reduction required.
Noise and Community noise levels are generally presented in
Land Use terms of CNEL (Community Noise Equivalent Level) or
Compatibility Ldn (Day-Night Noise Level). CNEL is the average
Guidelines equivalent A-weighted sound level during a 24-hour
day. It is based on the premise that noise during the
evening and night is more annoying than daytime noise.
To calculate CNEL, 5 decibels are added to the sound
levels in the evening (7 p.m. to 10 p.m.) and 10
decibels are added to the sound levels at night (10
p.m. to 7 a.m.). The A-weighted scale measures noise
levels that correspond to the human hearing range.
Ldn is identical to CNEL except no weighting is added
to the evening period. CNEL and Ldn noise levels
usually agree within one decibel for the same noise.
For all practical purposes, CNEL and Ldn can therefore
be considered synonymous.
Figure 2 (page N-17), the Noise and Land Use
Compatibility Guidelines, is a chart showing the
limits of acceptable noise in Ldn for various types of
Land uses.
The objective of Figure 2 is to provide an acceptable
community noise environment and to minimize noise-related
complaints from residents. The compatibility guidelines
should be used in conjunction with the future noise
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exposure levels in Figure 1 to identify projects or
activities which may require special treatment to
minimize noise exposure. Homes should not be allowed
near a freeway, for example, unless mitigation
measures can effectively reduce noise exposure to
acceptable levels.
A land use or project in the "normally acceptable"
category will be acceptable within the noise levels
indicated, in most cases, without special noise
abatement measures. For example, a home of standard
construction would be an acceptable use in any area of
60 Ldn or less without special insulation, setback, or
building design. The same home in an area projected
for noise levels of 60 to 70 Ldn should be allowed
only following an acoustical study which recommends
site-specific noise attenuation measures such as
double pane windows, setbacks, and/or construction of
soundwalls.
The following considerations should be taken into
account when using the Noise and Land Use
Compatibility Guidelines:
The goal for maximum outdoor noise levels in
residential areas is an Ldn of 60 dB. This level is a
requirement to guide the design and location of future
development and a goal for the reduction of noise in
existing development. However, 60 Ldn is a goal which
cannot necessarily be reached in all residential areas
within the realm of economic or aesthetic feasibility.
This goal should be applied where outdoor use is a
major consideration (eg., backyards in single-family
housing projects). The outdoor standards should not
normally be applied to the small decks associated with
apartments and condominiums because of the lack of use
of these decks even in quiet areas. A multi-family
development can often be designed in such a way that
the buildings shield common outdoor areas and achieve
an acceptable outdoor noise level without the use of
soundwalls. For this reason, multi-family housing can
often be developed more successfully in noise
environments in which the Ldn exceeds 60 dB.
The indoor noise level as required by the State of
California Noise Insulation Standards must not exceed
an Ldn of 45 dB in multi-family dwellings. This
indoor criterion should also be the maximum acceptable
indoor noise level in single-family homes.
If the noise source is aircraft or helicopters, people
are generally annoyed at a lower average sound level than
for surface transportation sources. Recent studies have
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shown that aircraft noise at a given Ldn is more
annoying than traffic noise at the same Ldn.
Residential developments should be strongly
discouraged where the exterior Ldn exceeds 55 dB due
to aircraft. If residential uses are allowed in areas
in which the Ldn exceeds 55 dB, then interior noise
levels should be controlled so that maximum
instantaneous noise levels do not exceed 50 dB in
bedrooms or 55 dB in other rooms. Residential
construction should not be allowed in areas where the
Ldn exceeds 65 dB from aircraft.
Appropriate interior noise levels in commercial,
industrial, and office buildings are a function of the
use of space. For example, the noise level in private
offices should generally be quieter than for data
processing rooms. Interior noise levels in offices
generally should be maintained at 45 dB or less.
Acoustical designs to achieve this level should be
demonstrated by the project sponsor in sufficient
detail to satisfy City staff and OSHA requirements.
The guidelines are not intended to be applied
reciprocally. In other words, if an area currently is
below the desired noise standard, an increase in noise up
to the maximum should not necessarily be allowed. The
impact of a proposed project on an existing land use
should be evaluated in terms of the potential for adverse
community response, based on a significant increase in
existing noise levels, regardless of the compatibility
guidelines (see Policy 1.1).
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