107-Attachment 6. Noise Assessment.pdfAttachment 6
ENVIRONMENTAL NOISE ASSESSMENT
SUNFLOWER LEARNING CENTER
NEW DA YCARE AND PRE-SCHOOL
18900 STEVENS CREEK BOULEVARD
CUPERTINO, CALIFORNIA
March 10, 2011
Prepared for:
Ms. Piu Ghosh, Associate Planner
City of Cupertino
10300 Torre Avenue
Cupertino, CA 95014
Prepared by:
Fred M. Svinth, INCE, Assoc. AIA
ILLING WORTH& RODKIN, INC.
Acoustics Air Quality
505 Petaluma Boulevard South
Petaluma, CA 94952
(707) 766-7700
Job No.: 11-038
INTRODUCTION
The Sunflower Learning Center is planning to relocate from its current site at 19220 Stevens
Creek Boulevard in Cupertino to an existing office building at 18900 Stevens Creek Boulevard
also in Cupertino. At this new location Sunflower Learning Center would remodel the existing
building and site to expand it's current operations from a Kindergarten through 6`" grade after -
school only program to include a morning and daytime program for pre-school aged children.
This report describes potential noise effects at the new site resulting from the Sunflower
Learning Center pre-school and after school programs. Included is a discussion of the
fundamentals of acoustics, a description of state and local guidelines and policies, a description
of the existing onsite noise environment, and an assessment of noise generated by the proposed
use of the site.
SETTING
BACKGROUND INFORMATION ON NOISE
Noise may be defined as unwanted sound. Noise is usually objectionable because it is disturbing
or annoying. The objectionable nature of sound could be caused by its pitch or its loudness.
Pitch is the height or depth of a tone or sound, depending on the relative rapidity (frequency) of
the vibrations by which it is produced. Higher pitched signals sound louder to humans than
sounds with a lower pitch. Loudness is intensity of sound waves combined with the reception
characteristics of the ear. Intensity may be compared with the height of an ocean wave in that it
is a measure of the amplitude of the sound wave.
In addition to the concepts of pitch and loudness, there are several noise measurement scales that
are used to describe noise in a particular location. A decibel (dB) is a unit of measurement that
indicates the relative amplitude of a sound. The zero on the decibel scale is based on the lowest
sound level that the healthy, unimpaired human ear can detect. Sound levels in decibels are
calculated on a logarithmic basis. An increase of 10 decibels represents a ten -fold increase in
acoustic energy, while 20 decibels is 100 times more intense, 30 decibels is 1,000 times more
intense, etc. There is a relationship between the subjective noisiness or loudness of a sound and
its intensity. Each 10 decibel increase in sound level is perceived as approximately a doubling of
loudness over a fairly wide range of intensities. Technical terms are defined in Table 1.
There are several methods of characterizing sound. The most common in California is the A -
weighted sound level or dBA. This scale gives greater weight to the frequencies of sound to
which the human ear is most sensitive. Representative outdoor and indoor noise levels in units
of dBA are shown in Table 2. Because sound levels can vary markedly over a short period of
time, a method for describing either the average character of the sound or the statistical behavior
of the variations must be utilized. Most commonly, environmental sounds are described in terms
of an average level that has the same acoustical energy as the summation of all the time -varying
events. This energy -equivalent sound/noise descriptor is called Leq. The most common
averaging period is hourly, but Leq can describe any series of noise events of arbitrary duration.
The scientific instrument used to measure noise is the sound level meter. Sound level meters can
accurately measure environmental noise levels to within about plus or minus I dBA. Various
computer models are used to predict environmental noise levels from sources, such as roadways and
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airports. The accuracy of the predicted models depends upon the distance the receptor is from the
noise source. Close to the noise source, the models are accurate to within about plus or minus 1 to 2
dBA.
Table 1: Definitions of Acoustical Terms Used in this Report
Term
Definitions
Decibel, dB
A unit describing, the amplitude of sound, equal to 20 times the
logarithm to the base 10 of the ratio of the pressure of the sound
measured to the reference pressure. The reference pressure for air is 20.
Sound Pressure Level
Sound pressure is the sound force per unit area, usually expressed in
micro Pascals (or 20 micro Newtons per square meter), where 1 Pascal
is the pressure resulting from a force of 1 Newton exerted over an area
of 1 square meter. The sound pressure level is expressed in decibels as
20 times the logarithm to the base 10 of the ratio between the pressures
exerted by the sound to a reference sound pressure (e.g., 20 micro
Pascals). Sound pressure level is the quantity that is directly measured
by a sound level meter.
Frequency, Hz
The number of complete pressure fluctuations per second above and
below atmospheric pressure. Normal human hearing is between 20 Hz
and 20,000 Hz. Infrasonic sound are below 20 Hz and Ultrasonic
sounds are above 20,000 Hz.
A -Weighted Sound Level,
The sound pressure level in decibels as measured on a sound level
dBA
meter using the A -weighting filter network. The A -weighting filter 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.
Equivalent Noise Level, L,y
The average A -weighted noise level during the measurement period.
n
The maximum and minimum A -weighted noise level during the
measurement period.
I-ol, Ljo, Lso, L90
The A -weighted noise levels that are exceeded 1%, 10%, 50%, and
90% of the time during the measurement period.
Day/Night Noise Level,
The average A -weighted noise level during a 24-hour day, obtained after
Ld.
addition of 10 decibels to levels measured in the night between 10:00 pm
and 7:00 am.
Community Noise
The average A -weighted noise level during a 24-hour day, obtained after
Equivalent Level, CNEL
addition of 5 decibels in the evening from 7:00 pm to 10:00 pm and after
addition of 10 decibels to sound levels measured in the night between
10:00 pin and 7:00 am.
Ambient Noise Level 4
The composite of noise from all sources near and far. The normal or
existing level of environmental noise at a given location.
Intrusive
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, and time of occurrence and tonal or
informational content as well as the prevailing ambient noise level.
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fable L: tvvicat iNoise Levels In the Environment
Common Outdoor Activities I Noise Level (dBA) Common Indoor Activities
110 dBA Rock band
Jet fly -over at 1,000 feet
Gas lawn mower at 3 feet
90 dBA
Diesel truck at 50 feet at 50 mph Food blender at 3 feet
80 dBA
Garbage disposal at 3 feet
Noisy urban area, daytime
Gas lawn mower, 100 feet
70 dBA
Vacuum cleaner at 10 feet
Commercial area
Normal speech at 3 feet
Heavy traffic at 300 feet
60 dBA
Large business office
Quiet urban daytime
50 dBA
Dishwasher in next room
Quiet urban nighttime 40 dBA Theater, large conference room
Quiet suburban nighttime
30 dBA Library
Quiet rural nighttime Bedroom at night, concert hall
20 dBA
Broadcast/recording studio
10 dBA
0 dBA
Since the sensitivity to noise increases during the evening and at night -- because excessive noise
interferes with the ability to sleep -- 24-hour descriptors have been developed that incorporate
artificial noise penalties added to quiet -time noise events. The Community Noise Equivalent Level,
CNEL, is a measure of the cumulative noise exposure in a community, with a 5 dB penalty added to
evening (7:00 pm - 10:00 pm) and a 10 dB addition to nocturnal (10:00 pm - 7:00 am) noise levels.
The Day/Night Average Sound Level, CNEL or Ld,,, is essentially the same as CNEL, with the
exception that the evening time period is dropped and all occurrences during this three-hour period
are grouped into the daytime period.
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Effects of Noise
Sleep and Speech Interference
The thresholds for speech interference indoors are about 45 dBA if the noise is steady and above
55 dBA if the noise is fluctuating. Outdoors the thresholds are about 15 dBA higher. Steady
noise of sufficient intensity (above 35 dBA) and fluctuating noise levels above about 45 dBA
have been shown to affect sleep. Interior residential standards for multi -family dwellings are set
by the State of California at 45 dBA Ldn. Typically, the highest steady traffic noise level during
the daytime is about equal to the Ldn and nighttime levels are 10 dBA lower. The standard is
designed for sleep and speech protection and most jurisdictions apply the same criterion for all
residential uses. Typical structural attenuation is 12-17 dBA with open windows. With closed
windows in good condition, the noise attenuation factor is around 20 dBA for an older structure
and 25 dBA for a newer dwelling. Sleep and speech interference is therefore possible when
exterior noise levels are about 57-62 dBA Ldn with open windows and 65-70 dBA Ldn if the
windows are closed. Levels of 55-60 dBA are common along collector streets and secondary
arterials, while 65-70 dBA is a typical value for a primary/major arterial. Levels of 75-80 dBA
are normal noise levels at the first row of development outside a freeway right-of-way.
Annoyance
Attitude surveys are used for measuring the annoyance felt in a community for noises intruding
into homes or affecting outdoor activity areas. In these surveys, it was determined that the
causes for annoyance include interference with speech, radio and television, house vibrations,
and interference with sleep and rest. The Ldn as a measure of noise has been found to provide a
valid correlation of noise level and the percentage of people annoyed. People have been asked to
judge the annoyance caused by aircraft noise and ground transportation noise. There continues
to be disagreement about the relative annoyance of these different sources. When measuring the
percentage of the population highly annoyed, the threshold for ground vehicle noise is about 50
dBA Ldn. At an Ldn of about 60 dBA, approximately 12 percent of the population is highly
annoyed. When the Ldn increases to 70 dBA, the percentage of the population highly annoyed
increases to about 25-30 percent of the population. There is, therefore, an increase of about 2
percent per dBA between an Ldn of 60-70 dBA. Between an Ldn of 70-80 dBA, each decibel
increase increases by about 3 percent the percentage of the population highly annoyed. People
appear to respond more adversely to aircraft noise. When the Ldn is 60 dBA, approximately 30-
35 percent of the population is believed to be highly annoyed. Each decibel increase to 70 dBA
adds about 3 percentage points to the number of people highly annoyed. Above 70 dBA, each
decibel increase results in about a 4 percent increase in the percentage of the population highly
annoyed.
REGULATORY BACKGROUND s'
The State of California and the City of Cupertino establish guidelines, regulations, and policies
designed to limit noise exposure at noise sensitive land uses. These plans and policies include:
(1) the State CEQA Guidelines, Appendix G; (2) the City of Cupertino General Plan; and (3) the
City of Cupertino Municipal Code.
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State CEQA Guidelines
The California Environmental Quality Act (CEQA) includes qualitative guidelines for
determining significance of adverse environmental noise impacts. A project will typically have a
significant impact if it would:
a. Expose people to or generate noise levels in excess of standards established in the local
general plan, noise ordinance, or applicable standards of other agencies.
b. Expose people to or generate excessive groundborne vibration or groundborne noise
levels.
C. Result in a substantial permanent increase in ambient noise levels in the project vicinity
above levels existing without the project.
d. Result in a substantial temporary or periodic increase in ambient noise levels in the
project vicinity above levels existing without the project.
e. For projects within an area covered by an airport land use plan or within two miles of a
public airport or public use airport when such an airport land use plan has not been
adopted, or within the vicinity of a private airstrip, expose people residing or working in
the project area to excessive aircraft noise levels.
f. For a project within the vicinity of a private airstrip, expose people residing or working in
the project area to excessive noise levels.
Of these guidelines, items (a), (c), and (d) are applicable to the proposed project. Guideline (b) is
not applicable to the project because the project is not located adjacent to, nor would it introduce,
any known sources of groundborne vibration. Guidelines (e) and (f) are not applicable because the
project is not located within an airport land use plan or in the vicinity of a private airstrip.
Therefore, checklist items (b), (e), and (f) are not carried forward for further analysis.
CEQA does not define what noise level increase would be considered substantial. Typically,
project -generated noise level increases of 3 dBA CNEL or greater would be considered
significant where exterior noise levels would exceed the normally acceptable noise level
standard. Where noise levels would remain at or below the normally acceptable noise level
standard with the project, noise level increases of 5 dBA CNEL or greater would be considered
significant.
City of Cupertino General Plan
The Health and Safety Element of the City of Cupertino General Plan identifies noise and land
use compatibility standards for various land uses. Residential land uses are considered
"normally acceptable" in noise environments of 60 dBA CNEL or less while Schools are
considered "normally acceptable" in noise environments of 70 dBA CNEL or less. Goal L of the
noise section is to provide a compatible noise environment for existing and future land uses.
Goal N of the noise section is to protect residential areas as much as possible from intrusive'hon-
traffic noise. The policies included in the Health and Safety Element are not directly applicable
to the proposed project.
City of Cupertino Municipal Code
The City of Cupertino regulates noise within the community in Chapter 10.48 (Community
Noise Control) of the Municipal Code. Quantitative noise level limits are presented in Table 3.
Section 10.48.040 states that, individual noise sources, or the combination of a group of noise
sources located on the same property, shall not produce a noise level exceeding those presented
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in Table 3. Nonresidential land uses, such as the proposed project, can generate noise levels up
to 65 dBA during the daytime and 55 dBA during the nighttime at the complaint site of a
receiving property. The "residential" standard allows noise levels up to 60 dBA during the
daytime and 50 dBA during the nighttime. Although not explicitly stated, these limits are
assumed to be in terms of the average noise level (Leq).
TABLE 3: Daytime and Nighttime Maximum Noise Levels (Lej
Land Use
Maximum Noise Level at Com laint Site of Receiving Property
at Point of Origin
Nighttime'
Da time
Residential
50 dBA
60 dBA
Nonresidential
55 dBA
65 dBA
Notes:
1. Nighttime is defined as between 8:00 p.m. to 7:00 a.m. (weekdays) and between 6:00 p.m. to 9:00 a.m.
(weekends) in Municipal Code section 10.48.010.
2. Daytime is defined as between 7:00 a.m. to 8:00 p.m. (weekdays) and between 9:00 a.m. to 6:00 p.m.
weekends in Municipal Code section 10.48.010.
Section 10.48.050 allows for brief exceedances of the daytime noise limit providing that the sum
of the noise duration in minutes plus the excess noise level does not exceed twenty in a two-hour
period. Table 4 shows the allowable exceedance increment for periods in a 2 hour period per
Section 10.48.050. An example using the noise increments shown in Table 4 would be that a
noise level of 79 dBA could be experienced at a residential property for no more than 1 minute in
any 2-hour period during the day. 80 dBA would be the maximum instantaneous noise level
limit during daytime hours. Theoretically, the noise level limits presented in Section
10.48.050 are more restrictive than the noise level limits in Section 10.48.040 alone. For
instance, a maximum noise level greater than 80 dBA could be generated by an activity over a
short period of time; however, the average noise level could continue to be less than 60 dBA Leq
during the two-hour averaging period.
TABLE 4 Exeedances Allowed Above Da time Standard
Noise Increment Above Normal Standard
Noise Duration in 2-Hour Period
5 dBA
15 minutes
10 dBA
10 minutes
15 dBA
5 minutes
19 dBA
1 minute
The Municipal Code does not specify statistical noise limits for noises occurring during
nighttime hours. A reasonable interpretation of these regulations would similarly restrict
nighttime events provided that the sum of the noise duration in minutes plus the excess noise
level does not exceed twenty in a two-hour period. For example, a maximum instantaneous
noise level of 70 dBA Lma,, would not be allowed between 8:00 PM and 7:00 AM on weekdays
and 6:00 PM and 9:00 AM on weekends.
Construction noise is limited in Section 10.48.053 as follows:
A. Grading, construction and demolition activities shall be allowed to exceed the noise limits of
Section 10.48.040 during daytime hours; provided, that the equipment utilized has high -
quality noise muffler and abatement devices installed and in good condition, and the activity
meets one of the following two criteria:
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1. No individual device produces a noise level more than eighty-seven dBA at a distance of
twenty-five feet (7.5 meters); or
2. The noise level on any nearby property does not exceed eighty dBA.
B. Notwithstanding Section 10.48.053A, it is a violation of this chapter to engage in any
grading, street construction, demolition or underground utility work within seven hundred
fifty feet of a residential area on Saturdays, Sundays and holidays, and during the nighttime
period, except as provided in Section 10.48.030.
C. Construction, other than street construction, is prohibited on holidays, except as provided in
Sections 10.48.029 and 10.48.030.
D. Construction, other than street construction, is prohibited during nighttime periods unless it
meets the nighttime standards of Section 10.48.040.
E. The use of helicopters as a part of a construction and/or demolition activity shall be restricted
to between the hours of nine a.m. and six thirty p.m. Monday through Friday only, and
prohibited on the weekends and holidays. The notice shall be given at least twenty-four hours
in advance of said usage. In cases of emergency, the twenty-four hour period may be
waived.
EXISTING NOISE ENVIRONMENT
The proposed site for the relocation
of the Sunflower Learning Center is
an existing office building and
parking lot at the southwest corner
of the intersection of Stevens Creek
Blvd. and Stern Avenue (18900
Stevens Creek Blvd) in Cupertino,
California. This site is bordered by
single-family homes to the west and
south and commercial businesses
across Stern Avenue to the east.
One of the single-family homes to
the west (10038 Bret Avenue) also
appears to operate as a preschool
under the name of "The Learning
Child (TLC) of Cupertino'. Figure
1 shows an aerial photo of the
project site and these surrounding
uses.
Figure 1: Aerial Photo of Site Vicinity
The existing ambient noise environment at the project site was quantified at two long-term and
one short-term location. The first long-term measurement (LT-1) was made at the southern
property line, and the second long-term measurement (LT-2) was made at the western property
line adjacent to the home, which operates as a preschool between February 28 and March 1,
2011. The short-term measurement (ST) was made at the approximate center of the proposed
project playground. The noise measurement locations are shown on Figure 1. All noise levels
were measured using a Larson -Davis Laboratories (LDL) model 820 precision Type 1 sound level
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1-118
ineter fitted with a 1/2--inch pre -polarized condenser microphone and windscreen. The meters were
calibrated before and after installation with a 114 dB, 1000 hertz LDL LICOUStical calibrator.
Continuous I 0-minute duration noise measurements were conducted at the long-terin positions to
clot UTIlenttlie daily trend in ambient. noise levels over the course ofa, 25-hourperiod. During
each interval the maxinlUrn instantaneous sound level energy equivalent noise level (L,q)
sound levels and the sound levels exceeded 1, 10, 50, and 90 percent Of thC time interval (Lc)I,
L10, 1,50, 1,90) were documented. Average (I.,q) TlOiSC� IeVCk for were also surnined for each of the
25 hot,trs measured,
The first long -.term sound level meter (1-1% 1) was positioned in the branches of a tree on the southern
properly line shared between the project site and the ad " jacent single-family horne on Stern Avenue
(see Figure Fl. 'rhe rnea,sured noise levels at this location, and the average energy equivalent noise
level (L,,) for each hour are shown on Chart 1.
no
85
ME
W
-70
t
,65
6 0
55
50
M
M
Chart 1: Aleasured Noise Levels at I.T-1
It' 1µ 12 2
C, C) wC•, TRN ", o c, 0 C.", 0 "R, 0 C, C> r ", ID C, C, 0 I= C0
r -
14 IN 11 1`1 mt "1. c",, cKo" 6 6 n 7 n m
140W,Begipnirf�,J," 4ruar) 28(flJoINIarchIst 2011
X'. Lmax Lo I L 10 I-eq ---,6--- L50 1,90 - - + LI'llin a I fourly Lecj I
A review of Chart I shows that the noise levels at site LT -I follow a diurnal pattern characteristic of
traffic noise, with the daythne and nighttime average hourly noise levels ranging frown 50 to 66
dBA and 48 to 62 dBA, respectively, and with an average daytime L, I of.50 dBA and an average
nighttime I....,eq of 55 dBA,I'he (.",o min unity Noise Equivalent I-evel (CNF'L) over the ineasuremcrit
period was calculated to be 63 dBA.
flu=
90
M
SO
75
`�70
J
65
60
55
50
M
40
The second long; -terra sound level meter (L,T-2) was positioned in. a utility pole on the western
property line shared between the project site and the single-family home at 10038 Bret Avenue,
which is also the horne of the 'ITC of Cbpertino dayeare center (see Figure 1). The iricasured
noise levels at t1ris location, and the average energy equivalent noise level (L,,) fior each hour are
shown on Chart 2, following,
Chart 2: Measured Noise Levels at LT-2
>.!>�� "I �E
<
C11 1=1 11
In, 1�� 11� C� 1.1! In, 1P In, 1.� 1� C� In 7_� 11� In 1,� rn 0 o o - cp In 1;b 1,
'D 66 6, 6 6
-------- 10,u_r, Be'ginnin"%_)(4rytry 28th Omar _0111_11111�1't, 4nj�
-1 L, 1 9 1 0 - Llylil I_ 11c)-uTly Lcq]
.A review of C',hart 2 shows that the noise levels at site LT-2 also R-Alowed a diurnal pattern
characteristic of traffic noise, with the daytime and nigfittirne average ho.)urly noise levels
ranging born 46 to 68 dBA and 47 to 60 dBA, respectively, with an. average daytime 1`-eq of'61
dBA and an average nighttime 1,eq of'54 (113A, The (.',ornmUnity Noise Equivalent Level (CNEL)
,over the i'neasurernent period was calculated to be 62 dBA.
An analysis of the measurement results at LT-2 vcrsus those at LT-lindicates that, in general,
noise levels measured at 1,'T-2 were within 2 dBA (plus or minus) of" those measured at LA'- l,
which is expected based on sornewhat greater shielding frorn traftic noise, at this location and the
variability of traffic,, noise within, parking lots. However, during some I 0-ininute periods
between 8 am and l2pm and 3 pm, and 5 pin the average noise levels measured at 1,T-2 were
between 4 to 10 dBA higher than those at site LT-- I. Based on the timing of these increases, the
proximity to the outdoor play area at the adJacent daycare to the rneasurerrient locations, these
11'age 10
noise levels increases are judged to be due to sound produced by outdoor activities at the TLC
daycare center.
Calculations using the differences in average noise levels at the two long term measurement
positions during 10-minute periods when outdoor play was judged to occur, average noise levels
due to outdoor play at the TLC daycare center were found to range from 58 to 66 dBA at the
property line.
The results of the short-term measurement, conducted over made a 10-minute period
simultaneous with the measurements at the long-term positions, indicate that noise levels at the
center of the proposed playground can be characterized by an average daytime Leq of between 61
and 63 dBA and a CNEL of 64 dBA.
A noise measurement survey was also conducted adjacent to the outdoor activity of the existing
facility located at 19220 Stevens Creek Boulevard during scheduled periods of outdoor play on
February 28, 2011. Measurements were made in a parking lot island at a distance of 50 feet from
the edge of the play area. Outdoor recess is scheduled between 4:00 and 4:10 pm and 5:00 and
5:10 pm daily at the current facility. Significant sound from outdoor play activities occurred
between 4:00 pm and 4:13 pm and again between 4:59 and 5:12pm. The purpose for these
measurements was to establish the noise level is generated during outdoor play so that the
potential effects could be assessed at the proposed site. The results of these measurements,
including the maximum instantaneous sound level (Lm), energy equivalent noise level (Leq)
sound levels and the sound levels exceeded 1, 10, 50, and 90 percent of the time interval (41,
Llo, L50, L90) are shown in Table 5.
The average noise level (Leq) resulting from the children's play at a distance of 50 feet was
between 61 and 63 dBA with maximum noise levels ranging from 74 and 75 dBA measured at a
distance of 50 feet from the perimeter of the play area. This is judged to be a representative
number to evaluate the potential effects at the new site.
Table 5: Sound levels due to Outdoor Activity at 50 feet from the existing Play Area
Time of outdoor activity (2/28/2011)
Lmax
L01
L10
Leq
L50
L90
Primary Source of Noise
4:00pm to 4:13pm
75
69
65
61
59
48
Children's voices and play
4:59pm to 5:12pm
74
70
66
63
61
55
Children's voices and play
NOISE IMPACTS AND MITIGATION MEASURES
SIGNIFICANCE CRITERIA
The following criteria are used in this report to evaluate the significance of noise impacts:
1. Consistency with Local Noise Standards. A significant noise impact would result if the
operation of the project would expose future project or adjacent noise sensitive users to
noise levels that exceed applicable General Plan or Municipal Code noise standards.
2. Substantial Permanent Noise Increase. A significant noise impact would result if the
project would increase noise levels at noise sensitive receptors by 3 dBA CNEL or
greater where exterior noise levels would exceed the normally acceptable noise level
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1-121
standard. Where noise levels would remain at or below the normally acceptable noise
level standard with the project, noise level increases of 5 dBA CNEL or greater would be
considered significant.
3. Construction Noise. Construction noise impacts would be considered significant if
hourly average noise levels received at noise sensitive residential land uses are 60 dBA
Leq and at least 5 dBA Leq above the ambient noise environment when the duration of the
noise -generating activities last for more than one year.
Impact la: Consistency with Local Noise Standards at the proposed Facility. Noise
Exposure at the project site does not exceed the General Plan noise and land use
compatibility standards. This is a less than significant impact.
The results of the noise measurement survey and indicate that the playground area
proposed at the project site would be exposed to a CNEL of 64 dBA under current
conditions. Based on a review of the future traffic noise contours in the General Plan and
a consideration that, under most conditions, for a 25 % increase traffic volumes in needed
to produce a 1 dBA increase in traffic, future noise traffic noise are expected to remain
within 1 dBA of current levels. Therefore, the outdoor use are of the proposed facility
would be considered to be "normally acceptable" in for school usage under both current
and future conditions.
Mitigation Measures: None Needed
Impact lb: Consistency with Local Noise Standards at Adjacent Uses. Noise produced by
the operation of the project would not generate noise levels in excess of the noise
limits established in the Municipal Code and General Plan. This is a less than
significant impact.
The proposed projects hours of operation (8:30am to 6:30 pm Monday to Friday) fall
within daytime hours as defined by in the City's Municipal Code. The Municipal code
noise limits respective daytime noise levels produced by residential and nonresidential
uses to 60 and 65 dBA Leq during these hours. The General Plan limits daily average
noise levels to 60 dBA CNEL at residential land uses. The above standards are used in
this assessment as a measure of acceptability for community noise in Cupertino.
Use of the project site by the Sunflower Learning Center. would primarily involve indoor
activities, which do not have the potential for produce any significant noise impact on the
surrounding residential uses. The most significant noise effect related to the use of the
site by the Sunflower Learnijig Center would be due to children playing in the main
outdoor playground areas proposed in a portion of the existing parking area immediately
south of the existing office building and children playing in the small outdoor activity
area adjacent to the building at the western edge of the site (see Figure 2). The main
playground will have a play structure installed, which will include an elevated play areas
and slide(s), while the small outdoor activity would have no elevated play areas. The
daily schedules for the pre-school and after -school programs proposed for the new site
would include outdoor activities in the playground areas between 11:00 to 11:30am, 4:00
to 4:1Opm, and 5:00 to 5:3Opm.
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a.D
k-
VIC.
Figure 2: Project Site Plan
Q
03
A review of the prQject site plan shows that the edge of the inain play area will be 63 feet
from the southern property line and 57 feet from the western property line. "nis review
also shows that the smaller outdoor activity area will be as close as 4 f12 feet from the
western property line with the center of the activity area. at approxiniately 20 feet froni
the western property line. Both the playground and activity areas will be enclosed with a
6-foot high solid wood terice. Currently, 5'8" high niasonry block walls are installed at
both the western and southern property lines of the site. The project includes increasing
the height of this wall from 58"to eight feel, (8'-0") high with solid masonry materials.
Based on noise levels measured during outdoor recss periods at the current facility (see
'hble 5, page 11), considering the rate at which sound atterRiates with increased distance,
and the sound attenuation provided. by 8-foot Ingh niasoury block property line walls,
calculations indicate that average SOLInd levels due to children's voices and play at
the smaller outdoor activity area at the residential side of the western project property line
would range froirt 43 to 45 (113A when children are in the center of the activity area to
between 46 to 48 dBA when children are at: the western edge ofthe activity area. These
calculations also show that rnaximum smind levels at the residential side of" the
western project property line due to children playing at the smaller outdoor activity area
would range from. 56 to 57 dBA when children are in the center of the activity area to
between 59 to 60 dBA when children are, at the western edge of the activity area.
Using the sarne assumptions as above', and the variable source height at the mifti
playground 2, CalCUlatiorts indicate that average (L,) sound levels due to ground level
Noise levels incasured during outdoor recess periods at the current fticility (see Lable 5, page 11), the rate at which
&ouild attenuates ,vrth increased distance, and the souild attentiation provided by 8-foot high masonry block f-WOPCII)d
line Nvalls.
Page 13
play at the main playground would range from 37 to 39 dBA at the residential side of the
western property line and from 36 to 38 dBA at the residential side of the southern
property line. The maximum (Lma-,) sound levels due to ground level play at the main
playground would also range from 50 to 51 dBA at the residential side of the western
property line and from 49 to 50 dBA at the residential side of the southern property line.
Based on the preceding discussion, all sound levels produced by outdoor activities at the
proposed project will comply with the residential (60 dBA Leq, 80 dBA L.,,) municipal
code standards at the adjacent residential uses.
Mitigation Measures: None Needed
Impact 2: Substantial Noise Increase. Noise resulting from the operation of the proposed
project would not substantially increase noise levels at residential receptors at the
site perimeter. This is a less than significant impact.
In addition to noise from outdoor play, the project activities would also produce noise
during the pick and drop off of students in the parking lot. Noise produced by parking lot
use from the proposed use of the site is not expected to differ substantially from that the
current parking lot usage and therefore is not judged to result in a potentially significant
change in the noise environment at the surrounding residences. The existing noise
environment at the adjacent residential uses exceeds the "normally acceptable" limit of
60 dBA CNEL. The current noise environment also includes noise due to outdoor play in
from the existing daycare adjacent to the site (see pages 9 to 11). Based on
measurements and analysis completed for this study, noise from the use of the proposed
project is not expected to increase noise levels at adjacent residences by 3 dBA CNEL or
greater or significantly alter the type, or quality, of noise in the site vicinity.
Mitigation Measures: None Needed
Impact 3: Construction Noise. Noise levels generated by construction activities on the site
would not be expected to adversely affect adjacent land uses provided standard
construction noise restrictions are implemented at the site. This is a less than
significant impact.
Though improvements to the existing facility will largely involve changes to the building
interior, site improvements and work on the exterior fagade of the building will involve
periods of noise. The construction of the project would generate noise, and would
temporarily increase noise levels at adjacent residential land uses. With the incorporation
of the construction noise limitations found in Section 10.48.053 of the Municipal Code
the noise impact resulting from project construction would be considered less than
significant.
Mitigation Measures: None Needed
The height of children's voices are modeled as up to 7 feet above ground level on the play structure, and between 3 to 4
feet above ground level in all other areas.
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