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Investigative Science and Engineering
3511 Camino Dtl Rio South, Suite 302 Phone/Fax: 619-640-9379 / 619-640-0763
San Diego, CA 92108-4003 wwwJso-advantage.com
March 14,1999 (Revised)
Mr. Gregg Linhoff
Standard Pacific Homes
9355 Chesapeake Drive
San Diego, CA 92123-1010
Re: Standard Pacific Poinsettia Property Acoustical Study (ISE Report #98-017)
Dear Mr. Linhoff:
At the request of Standard Pacific Properties, Investigative Science and
Engineering (ISE) was directed to investigate potential noise impacts to the proposed
Poinsettia Properties residential development located in Carlsbad, California. An
acoustical survey of the site was performed on August 27, 1998. The results of that
survey, as well as predicted future sound levels at the site, are presented in this letter
report.
Introduction and Definitions
Existing Site Characterization
The project site consists of 74.9 acres located in the central portion of the City
of Carlsbad in San Diego County, California (refer to Figure 1). The site resides on both
sides of Poinsettia Lane, approximately 1 mile east of Interstate 5. The lots are bound
by Aviara Parkway to the east single-family residential housing to the north, and high
density single-family housing to the west and south. The project site appears to have
been rough graded for existing agricultural and nonagricultural operations. Existing land
uses on the property include tomato fields on the eastern terraced side of the property,
and undeveloped open space. The property contains two structures, both of which are
single family homes. In addition, two access roads are located on the project site to the
south of Poinsettia Lane. The first road parallels the western boundary of the project
site connecting Poinsettia Lane to the existing nursery, while the second connects
Poinsettia Lane to the upper portion of the property. The site is currently zoned L-C and
R-1-10000 with a proposed zoning of R-1-7500 and RD-M-Q.
The eastern portion of the project site contains moderate westward facing
slopes while the western half of the site contains gentle slopes with minor relief (refer to
Figure 2). Elevations on the site range from approximately 308 feet above mean sea
level (MSL) at the northeastern portion of the property to approximately 195 feet MSL at
the southwestern comer of the property.
Mr. Gregg Linhoff
Standard Pacific Poinsettia Property Acoustical Study
ISE Report #98-017
March 14, 1999 (Revised)
Page 2
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Mr. Gregg Linhoff
Standard Pacific Poinsettia Property Acoustical Study
ISE Report #98-017
March 14,1999 (Revised)
Pages
Acoustical Definitions
Noise is generally defined as unwanted or annoying sound that is typically
associated with human activity and which interferes with or disrupts normal activities.
Although exposure to high noise levels has been demonstrated to cause hearing loss,
the principal human response to environmental noise is annoyance. The response of
individuals to similar noise events is diverse and influenced by the type of noise, the
perceived importance of the noise and its appropriateness in the setting, the time of
day, and the sensitivity of the individual hearing the sound.
Airborne sound is a rapid fluctuation of air pressure above and below
atmospheric levels. The loudest sounds the human ear can hear conformably is
approximately one trillion (a one with 12 zeros following it) times the acoustic energy
that the ear can barely detect. Because of this vast range, any attempt to represent the
acoustic intensity of a particular sound on a linear scale becomes unwieldy. As a result
of this, a logarithmic ratio known as the decibel (dB) is commonly employed. A sound
level of zero "0" dB is scaled such that it is defined as the threshold of human hearing
and would be barely audible to a human of normal hearing under extremely quiet
listening conditions and would correspond to a sound pressure level equal to the
reference level.
Most of the sounds we hear in the environment do not consist of a single
frequency, but rather a broad band of frequencies differing in sound level. The
intensities of each frequency add to generate the sound we hear. The method
commonly used to quantify environmental sounds consists of determining all of the
frequencies of a sound according to a weighting system that reflects the nonlinear
response characteristics of the human ear. This is called "A" weighting, and the decibel
level measured is called the A-weighted sound level (or dBA). In practice, the level of a
noise source is conveniently measured using a sound level meter that includes a filter
corresponding to the dBA curve.
Although the A-weighted sound level may adequately indicate the level of
environmental noise at any instant in time, community noise levels vary continuously.
Most environmental noise includes a conglomeration of sounds from distant sources
that create a relatively steady background noise in which no particular source is
identifiable. For this type of noise a single descriptor called the Leq (or equivalent
sound level) is used. Leq is the energy-mean A-weighted sound level during a
measured time interval. It is the 'equivalent* constant sound level that would have to be
produced by a given source to equal the fluctuating level measured.
To describe time-varying character of environmental noise, the statistical noise
descriptors L10, L50, and L90 are commonly used. They are the noise levels equaled
or exceeded during 10 percent, 50 percent, and 90 percent of a stated time. Sound
levels associated with the L10 typically describe transient or short-term events, while
levels associated with the L90 describe the steady state (or most prevalent) noise
conditions. In addition, it is often desirable to know the acoustic range of the noise
Mr. Gregg Linhoff
Standard Pacific Poinsettia Property Acoustical Study
ISE Report #98-017
March 14,1999 (Revised)
Page 4
source being measured. This is accomplished through the maximum and minimum
measured sound level (Lmax and Lmin) indicators. The Lmin value obtained for a
particular monitoring location is often called the acoustic floor tor that location.
Another sound measure employed by the State of California is known as the
Community Noise Equivalence Level (or CNEL) is defined as the "A" weighted average
sound level for a 24-hour day. It is calculated by adding a 5 decibel penalty to sound
levels in the evening (7:00 p.m. to 10:00 p.m.), and a 10 decibel penalty to sound levels
in the night (10:00 p.m. to 7:00 a.m.) to compensate for the increased sensitivity to
noise during the quieter evening and nighttime hours.
Applicable Significance Criteria
City of Carlsbad
The Noise Element of the City of Carlsbad identifies sound levels that are
compatible with various land uses. According to the City of Carlsbad Draft Noise
Guidelines Manual, sound levels up to 60 dBA CNEL are compatible with residential
land uses. Sound levels up to 65 dBA CNEL are compatible with recreational areas
such as parks and playgrounds. The City also requires an interior noise study
(compliant with State of California CCR Title 24 standards) where exterior exposure is
in excess of the above land use criteria.
Rear and side yard areas of the proposed Poinsettia Property development
would be classified as usable exterior living space; thus, the City's guidelines will be
applied in this report to determine the requirement of exterior and interior mitigation at
all proposed units within the development adjacent to Poinsettia Lane and Aviara
Parkway.
State of California CCR Title 24
The California Code of Regulations (CCR), Title 24, Noise Insulation Standards,
states that multi-family dwellings, hotels, and motels located where the CNEL exceeds
60 dBA, must obtain an acoustical analysis showing that the proposed design will limit
interior noise to less than 45 dBA CNEL. Worst case noise levels, either existing or
future, must be used for this determination. Future noise levels must be predicted at
least ten years from the time of building permit application. The City of Carlsbad has
accepted the CCR Title 24 standards.
Analysis Methodology
Existing Conditions Field Survey
A Larson Davis Model 700 ANSI Type 2 integrating sound level meter was used
as the data collection device. The meter was placed at the following locations: along
Poinsettia Lane at the southwestern comer of Lot #94 (ML 1); along Poinsettia Lane
Mr. Gregg Linhoff
Standard Pacific Poinsettia Property Acoustical Study
ISE Report #98-017
March 14,1999 (Revised)
PageS
Opposite from proposed 'A' Street intersection (ML 2); and, overlooking intersection of
Aviara and Poinsettia on Lot #7 (ML 3). The meter was mounted on a tripod roughly 5
feet above the ground in order to simulate the average height of the human ear above
ground. The measurements were performed on August 27, 1998. The sound level
meter was calibrated before and after each set of measurements.
Future Acoustical Environment Modeling
The Caltrans Sound 32 Traffic Noise Prediction Model with California
(CALVENO) noise emission factors (based on FHWA RD-77-108 and FHWA/CA/TL-
87/03 standards) was used to calculate future onsite vehicular traffic noise levels.
Model input included a digitized representation of the alignment of Poinsettia Lane and
Aviara Parkway, as well as any local site topography, future ADT volume, vehicle mix,
and receptor elevations. The roadway and site topography elevations were obtained
from the project site plan (Source: Standard Pacific Poinsettia Property TM - Buccola
Engineering - 3/3/99). Model output consisted of peak hour energy-mean A-weighted
sound levels (or Leq-h) for each receptor examined.
Receptor elevations were considered to be 5 feet above the appropriate floor
(pad) elevation. The model assumed a "hard" site sound propagation rule (i.e., a 3-dBA
loss per doubling of distance from roadway to receiver) in accordance with Caltrans
practices. The model also considered the attenuation due to the slope adjacent to the
project site. Future noise levels were calculated for the first and second floor
elevations (assumed to be five and 20 feet respectively above the building pad).
Findings
Ambient Sound Measurement Results
Testing conditions during the monitoring period were partly cloudy with an
average barometric pressure reading of 29.85 in-Hg, an average northerly wind speed
of 3 to 5 miles per hour (MPH), and an approximate mean temperature of 68 degrees
Fahrenheit. The results of the sound level monitoring are shown below in Table 1. The
values for the energy equivalent sound level (Leq), the maximum and minimum
measured sound levels (Lmax and Lmin), and the statistical indicators L10, L50, and
L90, are given for each monitoring location.
Measurements collected at monitoring locations ML 1 through ML 3 reflect
typical sound levels associated with the community setting observed and the
topography of the surrounding terrain. The onsite hourly energy average sound levels
(or Leq-h) recorded at 50 foot setback points along the edge of Poinsettia Lane was
fairly constant over the three consecutive hours monitored. As indicated by the
monitoring equipment, at least 90 percent of the time the onsite sound level averaged
between 44 and 52 dBA. The difference between the Leq and L90 metrics was directly
attributable to the intermittent nature of automobile traffic along Poinsettia Lane during
morning peak hour conditions. The acoustic floor for the site, as seen by the Lmin
Mr. Gregg Linhoff W
Standard Pacific Poinsettia Property Acoustical Study
ISE Report #98-017
March 14,1999 (Revised)
Page 6
indicator was low (between 38 and 46 dBA for all locations monitored) and reflects the
semi-rural community noise environment of the project site.
Table 1: Measured Ambient Sound Levels - Standard Pacific Poinsettia Property
Site
ML
ML
ML
1
2
3
Start Time
6:00 a.m.
7:00 a.m.
8:00 a.m.
1-Hour Noise Level Descriptors in dBA
Leq Lmax
57.3 67
57.4 70
58.3 72
.5
.0
.0
Lmin
38.0
41.0
45.5
L10
61
60
61
.0
.5
.0
L50
54.5
55.0
56.5
L90
43.5
46.0
51.5
Monitoring Locations:
* ML 1: Meter positioned along Poinsettia Lane at the southwestern comer of Lot #94
* ML 2: Meter positioned along Poinsettia Lane opposite from proposed 'A' Street
intersection
* ML 3: Meter positioned overlooking intersection of Aviara and Poinsettia on Lot #7
All positions taken at an approximate 50 foot setback from the edge of Poinsettia Lane
Measurements performed by ISE on August 27,1998.
Future Traffic Noise Impacts
The primary source of future traffic noise in the vicinity of the project would be
from Poinsettia Lane. Future year 2010 volume along this roadway alignment is
projected to be 36,000 ADT traveling at the posted speed of 40 MPH (Source: Urban
Systems Associates, ISE, 7998). The projected year 2010 ADT for adjacent Aviara
Parkway is 19,000 with a posted speed of 40 MPH. Peak hour traffic values are
calculated for an 8% traffic flow pattern and a 98/1/1 (automobiles/medium/heavy
vehicles) percent mix in accordance with Caltrans traffic forecasting practices. For peak
hour traffic percentages between approximately 8 and 12 percent (and a Level of
Service, or LOS, between A through C) the energy-mean A-weighted sound level is
equivalent to the 24-hour Community Noise Equivalent Level (CNEL). Outside this
range, a maximum variance of up to 2 dBA occurs between Leq-h and CNEL.
The results of the acoustical modeling are shown below in Table 2. Values for
selected pad locations adjacent to Poinsettia Lane and Aviary Parkway are given. Also
shown are the predicted noise levels for 1) unmitigated ground floor areas, 2) mitigated
ground floor areas, and 3) mitigated second floor levels. Based on the model results,
some lots adjacent to Poinsettia Lane and Aviara Parkway were found to be above the
60 dBA CNEL threshold criteria established by the City.
Mr. Gregg Linhoff
Standard Pacific Poinsettia Property Acoustical Study
ISE Report #98-017
March 14,1999 (Revised)
Page?
Table 2: Acoustical Modeling Results of Representative Lots - Standard Pacific
Poinsettia Property
Receptor
Location
R1
R2
R3
R4
R5
R6
R8
R9
R13
R17
R60
R88
R89
R90
R92
R93
R94
R213
R214
Ground
Level
(Unmit.)
56.1
57.2
60.5
58.3
61.3
60.2
60.8
59.3
57.4
55.3
68.1
59.9
65.3
65.4
59.5
57.3
57.4
65.5
66.8
Ground
Level
(Mit.)
52.2
53.6
56.0
54.5
56.9
58.1
56.7
56.6
57.3
55.1
56.9
56.5
60.0
60.0
55.2
52.4
53.8
59.5
59.1
Second
Floor
Areas
59.4
62.2(1)
67.7(1)
63.2(1)
67.9(1)
67.6(1)
63.9(1)
59.9
57.3
55.1
65.4(1)
58.4
65.7(1)
69.1(1)
60.0(1)
58.5
57.7
66.5(1)
67.5(1)
'
Receptor
Location
R223
R224
R225
R226
R227
R228
R229
R235
R236
R237
R238
R240
R241
R242
R243
R244
R245
R246
Illllfll
Ground
Level
(Unmit.)
63.3
67.0
67.4
67.3
66.6
65.6
63.2
57.2
55.8
55.3
55.5
58.4
58.3
58.1
60.2
62.4
61.6
52.8
XXXXXXX/XXXXXX
Ground
Level
(Mit)
57.6
58.9
59.4
59.2
58.4
59.1
58.0
57.2
55.8
55.2
55.4
54.7
54.3
54.1
55.3
56.5
56.8
50.2
XXXXXXXXXXXXXX.*
Second
Floor
Areas
66.0(1)
67.2(1)
67.6(1)
67.4(1)
66.7(1)
65.7(1)
63.6(1)
64.1(1)
63.8(1)
63.2(1)
63.6(1)
63.2(1)
62.0(1)
62.0(1)
65.2(1)
65.6(1)
64.3(1)
56.0
'/////S// //////
Notes:
* Values represent a sampling of potentially impacted lots along Poinsettia Lane and Aviara
Parkway. Lots 'sandwiched' between the lots shown above would also require the same
treatment.
* Modeled using the Caltrans Sound 32 Traffic Noise Prediction Model with California
(CALVENO) noise emission factors (based on FHWA RD-77-108 and FHWA/CA/TL-87/03
standards).
* Levels denoted with (I) indicates the requirement (or potential for requirement) of interior
noise mitigation.
<« All sound levels given in dBA CNEL.
Lots numbered 3 though 8, 61, 61, 89 through 92, 213, 214, 223 through 229,
and 243 though 245 were found to have projected future (ground level) traffic-related
noise levels in excess of the 60 dBA CNEL threshold established by the City. These
lots would require noise walls ranging from five to seven feet to be located along the
rear property line between Poinsettia Lane and the residential receptor. A schematic of
Mr. Gregg Linhoff
Standard Pacific Poinsettia Property Acoustical Study
ISE Report #98-017
March 14.1999 (Revised)
PageS
the proposed wall design is shown in Figure 3 as an attachment to this report.
Projected traffic volumes along Aviara Parkway combined with site topography negated
the need for mitigation along this roadway.
In addition, second floor receptor areas denoted with an (I) in Table 2 would
require an interior acoustical analysis to determine acceptable construction materials
and design measures to lower interior noise levels to 45 dBA CNEL per California CCR
Title 24 Noise Insulation Standards. Any lots 'sandwiched' between these lots (or
having a line-of-sight to the roadway) would also require interior noise control
measures. Thus, for completeness, the identified lots requiring interior mitigation would
be: 2 through 8, 60, 61, 89 through 92, 213, 214, 223 through 230, and 235 through
245 inclusive.
The interior acoustical analysis should be completed prior to submission of final
architectural designs for the proposed units situated on the affected pads.
Aircraft Transportation Noise Sources Identified
The project site lies outside the influence areas of McClellan-Palomar Airport
and associated industrial uses. The airport is currently operating at full capacity
(maximum typical number of flight operations per day) and no appreciable increase in
the contours is expected within the project analysis horizon. Thus, no significant
impacts to the project site due to aircraft operations are expected.
Conclusions
Future noise levels for units located along Poinsettia Lane and Aviara Parkway
were found to be in excess the 60 dBA CNEL threshold established by the City.
Exterior and interior mitigation measures were deemed necessary to reduce impacts to
below a level of significance. The following mitigation measures are required:
1. Lots numbered 3 though 8, 61, 61, 89 through 92, 213, 214, 223 through 229,
and 243 though 245 were found to have projected future (ground level) traffic-
related noise levels in excess of the 60 dBA CNEL threshold established by the
City.
2. Noise mitigation would require noise walls ranging from five to seven feet to be
located along the rear property line between Poinsettia Lane and the residential
receptor. A schematic of the proposed wall design is shown in Figure 3.
3. Projected traffic volumes along Aviara Parkway combined with site topography
negated the need for mitigation along this roadway.
4. Second floor receptor areas denoted with an (I) in Table 2 would require an
interior acoustical analysis to determine acceptable construction materials and
design measures to lower interior noise levels to 45 dBA CNEL per California
CCR Title 24 Noise Insulation Standards. Any lots 'sandwiched' between these
Mr. Gregg Linhoff
Standard Pacific Poinsettia Property Acoustical Study
ISE Report #98-017
March 14,1999 (Revised)
Page 9
lots (or having a line-of-sight to the roadway) would also require interior noise
control measures.
5. The identified lots requiring interior noise mitigation would be: 2 through 8, 60,
61, 89 through 92, 213, 214, 223 through 230, and 235 through 245 inclusive.
Should you have any questions regarding the above conclusion, please do not
hesitate to contact me at (619) 640-9379.
Sincei
lickTavares, EIT, REA, INGE
Project Principal
Investigative Science and Engineering
Cc: Glen Laube, ISE
Attachments: Figure 3 - Proposed Mitigation Design: Standard Pacific Poinsettia
Property Development
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