HomeMy WebLinkAboutAMEND 2024-0008; INNS OF AMERICA; NOISE EVALUATION; 2025-03-04..
dBF
Associates, Inc.
March 4, 2025
Jim McMenamin
Alliance Development Services, Inc.
17828 Villamora Drive
Poway, CA 92064
Re: The Flats at Terramar
5010 Avenida Encinas, Carlsbad
Noise Evaluation
Mr. McMenamin:
3129 Tiger Run Court Suite 202
Carlsbad, CA 92010
6 19-609-0712
At your request, we conducted an evaluation of noise produced by and affecting the
subject project. The purpose of the evaluation was to assess compliance with City of
Carlsbad and State of California noise level limits.
The project building is currently a Studio 6 hotel. The project is the conversion of the
building for multifamily residential use.
Exterior noise levels at outdoor use areas would not exceed 65 dBA CNEL, and would_be
in compliance with City of Carlsbad noise level limits.
Interior noise levels within residences would not exceed 45 dBA CNEL, and would be in
compliance with City of Carlsbad and State of California noise level limits.
Project-generated noise levels would not exceed 45 dBA Leq at sensitive land uses and
would be in compliance with City of Carlsbad noise level limits.
Noise Background
Noise is generally defined as loud, unpleasant, unexpected, or undesired sound typically
associated with human activity and that interferes with or disrupts normal activities. The
human environment is characterized by a certain consistent noise level which varies with
each area. This is called ambient noise. 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, perceived importance of the noise and its appropriateness
in the setting, time of day and type of activity during which the noise occurs, and
sensitivity of the individual. ••• [)
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dBF
Associates, Inc.
Mr. Jim McMenamin
March 4, 2025
Page2
Sound is a physical phenomenon consisting of minute vibrations that travel through a
medium, such as air, and are sensed by the human ear. Sound is generally characterized
by several variables, including frequency and intensity. Frequency describes the sound's
pitch and is measured in cycles per second, or hertz (Hz), whereas intensity describes the
sound's loudness and is measured in decibels (dB). Decibels are measured using a
logarithmic scale. A sound level of 0 dB is approximately the threshold of human hearing
and is barely audible under extremely quiet listening conditions. Normal speech has a
sound level of approximately 60 dB. Sound levels above about 120 dB begin to be felt
inside the human ear as discomfort and eventually as pain at still higher levels. Studies
have shown that the smallest perceptible change in sound level for a person with normal
hearing sensitivity is approximately 3 dBA. A change of at least 5 dBA would be
noticeable and would likely evoke a community reaction. A 10-dBA increase is
subjectively heard as a doubling in loudness and would cause a community response.
Sound levels of typical noise sources and environments are provided in Table 1.
Because of the logarithmic nature of the decibel unit, sound levels cannot be added or
subtracted directly and are somewhat cumbersome to handle mathematically. A simple
rule is useful, however, in dealing with sound levels. If a sound's intensity is doubled, the
sound level increases by 3 dB, regardless of the initial sound level. Thus, for example, 60
dB + 60 dB = 63 dB, and 80 dB + 80 dB = 83 dB. The normal human ear can detect
sounds that range in frequency from about 20 Hz to 20,000 Hz.
However, all sounds in this wide range of frequencies are not heard equally well by the
human ear, which is most sensitive to frequencies in the range of 1,000 Hz to 4,000 Hz.
This frequency dependence can be taken into account by applying a correction to each
frequency range to approximate the human ear's sensitivity within each range. This is
called A-weighting and is commonly used in measurements of community environmental
noise. The A-weighted sound pressure level (abbreviated as dBA) is the sound level with
the "A-weighting" frequency correction. 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.
Because community noise fluctuates over time, a single measure called the Equivalent
Sound Level (Leq) is often used to describe the time-varying character of community
noise. The Leq is the energy-averaged A-weighted sound level during a measured time
interval, and is equal to the level of a continuous steady sound containing the same total
acoustical energy over the averaging time period as the actual time-varying sound.
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dBF
Associates, Inc.
Mr. Jim McMenamin
March 4, 2025
Page3
Table 1. Sound Levels of Typical Noise Sources and Noise Environments
Human Judgment
Noise Source A-Weighted of Noise Loudness
Noise Environment (Relative to Reference (at Given Distance) Sound Level Loudness of 70
Decibels*)
Military Jet Takeoff Carner Flight Deck 140 Decibels 128 times as loud with Afterburner (50 ft)
Civil Defense Siren (100 ft) 130 64 times as loud
Commercial Jet Take-off (200 ft) 120 32 times as loud
Threshold of Pain
Rock Music Concert
Pile Drtver (50 ft) Inside Subway Station 110 16 times as loud
(New York)
Ambulance Siren (100 ft) 8 times as loud Newspaper Press (5 ft) 100 Very Loud Gas Lawn Mower (3 ft)
Food Blender (3 ft) Boiler Room Propeller Plane Flyover (1,000 ft) Printing Press Plant 90 4 times as loud
Diesel Truck ( 150 ft)
Garbage Disposal (3 ft) Noisy Urban Daytime 80 2 times as loud
Passenger Car, 65 mph (25 ft) Reference Loudness Living Room Stereo (15 ft) Commercial Areas 70 Moderately Loud Vacuum Cleaner (10 ft)
Normal Speech (5 ft) Data Processing Center 60 1/2 as loud Air Conditioning Unit (100 ft) Department Store
LightTraffic (100 ft) Large Business Office 50 1/4 as loud Quiet Urban Daytime
Bird Calls (distant) Quiet Urban Nighttime 40 1/8 as loud
Quiet
Soft Whisper (5 ft) Library and Bedroom at Night 30 1/16 as loud Quiet Rural Nighttime
Broadcast and Recording 20 1/32 as loud
Studio Just Audible
0 1/64 as loud
Threshold of Hearing
Source: Compiled by dBF Associates, Inc.
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dBF
Associates, Inc.
Mr. Jim McMenamin
March 4, 2025
Page4
The Community Noise Equivalent Level (CNEL) is an adjusted average sound level for a
24-hour day. It is calculated by adding a 5-dB adjustment to sound levels during evening
hours (7:00 p.m. to 10:00 p.m.) and a 10-dB adjustment to sound levels during nighttime
hours (10:00 p.m. to 7:00 a.m.). These adjustments compensate for the increased
sensitivity to noise during the typically quieter evening and nighttime hours. CNEL is
used by the City of Carlsbad and State of California to evaluate land-use compatibility
with regard to noise.
The Day-Night Level (DNL or Ldn) is an adjusted average sound level for a 24-hour day.
It is calculated by adding a 10-dB adjustment to sound levels during nighttime hours
(10:00 p.m. to 7:00 a.m.). This adjustment compensates for the increased sensitivity to
noise during the typically quieter nighttime hours. DNL is used by the City of Carlsbad to
evaluate land-use compatibility with regard to noise. CNEL and DNL are generally
considered interchangeable.
Regulatory Environment
City of Carlsbad General Plan Section 5: Noise provides noise standards.
The City of Carlsbad indicates acceptable noise limits in the Noise Element of its General
Plan [City of Carlsbad 2015]. At Multiple Family Residential uses, noise levels up to
65 dBA DNL are considered Normally Acceptable. Noise levels between 60-70 dBA
DNL are considered Conditionally Acceptable: "New construction or development
should be undertaken only after a detailed analysis of the noise reduction requirements is
made and needed noise isolation features included in the design."
Table 5-2 of the Noise Element indicates that the normal allowable noise exposure is
60 dBA CNEL for residential uses. However, footnote 4 of Table 5-2 states "An exterior
noise exposure level of 65 dBA CNEL is allowable ... for residential uses within the
McClellan-Palomar Airport Area oflnfluence (AoI), pursuant to the noise compatibility
policies contained in the ALUCP (Airport Land Use Compatibility Plan)." A review of
Exhibit III-5 of the McClellan-Palomar ALUCP shows that the project site is within the
Aol.
Within interior spaces of residential land uses, the allowable noise exposure is
45 dBA CNEL [City of Carlsbad 2015].
California Building Code (CBC), Chapter 12: Interior Environment, Section 1206: Sound
Transmission regulates noise levels in buildings with multiple habitable units [State of
California 2019]. Section 1206.4: Allowable interior noise levels states:
Interior noise levels attributable to exterior sources shall not exceed 45 dB in any
habitable room. The noise metric shall be either the day-night average sound
level (Ldn) or the community noise equivalent level (CNEL), consistent with the
noise element of the local general plan.
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dBF
Associates, Inc.
Mr. Jim McMenamin
March 4, 2025
Page 5
Table 5-3 of the Noise Element limits project-generated noise at sensitive uses to
55 I 45 dBA Leq during daytime/ nighttime hours.
Sound Level Measurements
Sound level measurements were conducted on Wednesday, September 11, 2024. The
measurements were conducted at the third (top) floor facing Interstate 5 (1-5), near the
north end of the building.
The interior measurement was conducted near the center ofroom 336. A RION Model
NL-31 American National Standards Institute (ANSI) Type 2 Integrating Sound Level
Meter was used as the data-collection device. The meter was mounted to a tripod roughly
five feet above floor level to simulate the average height of the human ear. The
microphone was fitted with a windscreen. The sound level meter was calibrated before
and after the measurement period. The measured sound level was 34.3 dBA Leq.
The exterior measurement was conducted roughly five feet from the fa9ade, by using a
microphone attached to an extension pole through the window ofroom 334. A RION
Model NA-28 ANSI Type 1 Integrating meter was used as the data-collection device. The
microphone was fitted with a windscreen. The sound level meter was calibrated before
and after the measurement period. The measured sound level was 70.1 dBA Leq.
The building envelope, which includes double dual-glazed windows, provides
approximately 35.8 dBA of noise reduction (70.1-34.3). It is our understanding that the
envelope configuration is identical at all habitable rooms.
The Acoustical Analysis for the original project building [Brown-Buntin Associates, Inc.
2000] indicated that the windows facing 1-5 were STC 35, and all others were STC 34.
Our field testing measurements, described above, corroborate this design requirement.
Free-flowing traffic on 1-5 was the primary observed noise source during the
measurements. Traffic counts were obtained from the Caltrans Freeway Performance
Measurement System (PeMS) website. The source data was from Vehicle Detector
Stations (VDS) 1108659 and 1108661. During the 15-minute measurement period, 1,874
northbound vehicles and 1,422 southbound vehicles passed by on 1-5.
Future Exterior Noise Exposure
On Wednesday, November 13, 2024, sound level measurements were conducted at the
project outdoor use areas. At the pool deck, the sound level was approximately 54 dBA
Leq. At the northeast pickleball court/ dog run location, the sound level was
approximately 62 dBA Leq. At the northwest pickleball court location, the sound level
was approximately 59 dBA Leq. At all locations, 1-5 traffic was the dominant noise
source.
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dBF
Associates, Inc.
Mr. Jim McMenamin
March 4, 2025
Page 6
As described above, I-5 noise is expected to increase by roughly 1 dBA in the future. As
such, noise levels at the outdoor use areas would range from roughly 55-63 dBA CNEL.
Future Interior Noise Exposure
The peak hour traffic noise level was considered equivalent to the CNEL [24 CFR
§51.106]. The peak hour traffic volume was considered to be 10% of the average daily
traffic (ADT) volume. Interstate 5, including high-occupancy vehicle lanes, is projected
to carry a future (year 2050) ADT volume of 177,500 vehicles past the project site
[SANDAG 2024]. The speed limit and traffic mix on Interstate 5 are not expected to
change in the future.
To determine the maximum exterior noise level from I-5, the measured noise level and
simultaneous traffic counts were compared to the future traffic volume. Refer to Table 2
for details.
Table 2. Maximum Noise Level
Hourly-Future Traffic Resultant
Location Measured Equivalent Hourly Noise Maximum Leq Vehicles Vehicle Increase CNEL Counted Volume
East exterior fagade 70.1 dBA 13,184 17,750 + 1.3 dBA 71.4 dBA
The south end of the building is approximately 280 feet from the centerline ofl-5,
whereas the measurements were conducted near the north end, which is approximately
375 feet away. Sound levels from line sources such as roadways increase at a minimum
rate of 3 dBA per halving of distance. Accordingly, the exterior noise level at the south
end of the building could be as much as 1.3 dBA higher than at the north end. Therefore,
the worst-case noise level at any project building fai;:ade would be 72.7 dBA CNEL.
As the building envelope demonstrably provides 35.8 dBA of noise reduction, the interior
noise level within any residential room would be a maximum of roughly 37 dBA CNEL.
Project-Generated Noise Levels
The project is surrounded by roadways and commercial uses. The closest noise-sensitive
receptors are the West Inn & Suites roughly 525 feet north beyond Cannon Road, and
single-family residences roughly 650 feet west beyond a primary rail corridor and
Avenida Encinas. There is an office building roughly 475 feet south of the pickleball
courts location.
Noise measurements of pickleball court usage were conducted at the Lake San Marcos
facility. Average sound levels at the edge of the courts were as high as 67 dBA Leg.
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dBF
Associates, Inc.
Mr. Jim McMenamin
March 4, 2025
Page 7
The Datakustik Cadna/ A industrial noise prediction model was used to estimate
pickleball noise levels. It was assumed that activity would occur continuously within the
court boundaries. No noise reduction related to ground effects, atmospheric absorption, or
intervening topography was included in the model.
Pickleball noise levels would be as high as 35 dBA Leq at the single-family residences,
38 dBA Leq at the hotel, and 40 dBA at the office building.
Conclusions
Because exterior noise levels at outdoor use areas would be Normally Acceptable and
allowable, the project adheres to the General Plan noise exposure standards.
Because the maximum interior noise level within any habitable residential room of the
project would not exceed 45 dBA CNEL, the existing project building is in compliance
with City of Carlsbad and State of California sound level limits as built.
Because project-generated noise levels would not exceed 45 dBA Leq at sensitive land
uses, the project adheres to the General Plan noise generation standards.
This concludes the evaluation. Please contact me at 619-609-0712 x102 if you have any
questions.
Sincerely,
dBF ASSOCIATES, INC.
Steven Fiedler,
Principal
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