HomeMy WebLinkAboutEnvironmental Noise Analysis - UP14-0009Environmental Noise Analysis
Afton Road Cellular Facility
Butte County, California
BAC Job # 2014-262
Prepared For:
Complete Wireless Consulting
Attn: Mr. Paul Vlnar
2009 V Street
Sacramento, CA. 95818
Prepared By:
Bollard Acoustical Consultants, Inc.
Paul Bollard, President
September 24, 2014
3551 Bankhead Road Loomis, CA 95650 Phone: (916) 663-0500 Fax: (916) 663-0501 BACNOISE.COM
Bollard Acoustical Consultants, Inc.
Environmental Noise Analysis
Afton Road Cellular Facility
Butte County, California
Page 1
Introduction
The Afton Road Verizon Wireless Unmanned Telecommunications Facility Project (project)
proposes the construction of a cellular tower (monopole), a pre-fabricated cellular equipment
shelter, and an emergency diesel standby generator inside a 40 x 40 fenced lease area located
at 4409 Aguas Frias Road in Durham (Butte County), California. The external HVAC units of
the equipment shelter and the emergency diesel standby generator have been identified as the
primary noise sources associated with the project. Please see Figure 1 for the general site
location. The studied site design is dated August 25, 2014.
Bollard Acoustical Consultants, Inc. has been contracted by Complete Wireless Consulting, Inc.
to complete an environmental noise assessment regarding the proposed project cellular
equipment operations. Specifically, the following addresses daily noise production and
exposure associated with operation of the project emergency generator and external HVAC
equipment.
Please refer to Appendix A for definitions of acoustical terminology used in this report.
Criteria for Acceptable Noise Exposure
Butte County Noise Ordinance
Butte County Code of Ordinances Chapter 41A (Noise Control), Article II (Noise Regulations),
Section 41A-7 provides exterior noise standards for noise-sensitive exterior areas within the
County. The standards are provided in terms of maximum (Lmax) and average (Leq) noise
descriptors for daytime (7am – 7pm), evening (7 pm – 10 pm) and nighttime (10 pm – 7 am)
periods. The standards are further categorized under “Urban” and “Non-Urban” headings. The
specific noise standards of this section are provided in Table 1.
Bollard Acoustical Consultants, Inc.
Environmental Noise Analysis
Afton Road Cellular Facility
Butte County, California
Page 3
Table 1
Butte County Exterior Noise Standards
Code of Ordinances 41A-7
Time of Day
Allowable Exterior Sound Level
Hourly Average Leq (dB) Maximum (Lmax)
Urban Non-Urban Urban Non-Urban
7:00 AM to 7:00 PM 55 50 70 60
7:00 PM to 10:00 PM 50 45 60 55
10:00 PM to 7:00 AM 45 40 55 50
A. The following noise standards, unless otherwise specifically indicated in this chapter, shall apply to all noise sensitive
exterior areas within Butte County.
B. It is unlawful for any person at any location within the County to create any noise which causes the noise levels on an
affected property, when measured in the designated exterior location, to exceed the noise standards specified above.
C. Each of the noise limits specified in subdivision (a) of this section shall be reduced by five (5) dBA for recurring
impulsive noise, simple or pure tone noise, or for noises consisting of speech or music.
D. Noise level standards, which are up to five (5) dBA less than those specified above, based upon determination of
existing low ambient noise levels in the vicinity of the project site may be imposed.
E. In urban areas, the exterior noise level standard shall be applied to the property line of the receiving property. In non-
urban areas, the exterior noise level standard shall be applied at a point one hundred (100) feet away from the
residence or at the property line if the residence is closer than one hundred (100) feet. The above standards shall be
measured only on property containing a noise sensitive land use.
The nearest off-site noise-sensitive receivers (residences) are located over 7,000 feet to the
west and southwest from the proposed cellular facility. Given the considerable distance to the
nearest off-site residences, project equipment noise levels would be well within compliance with
the County’s exterior noise level standards presented above in Table 1. However, as illustrated
on Figure 1, the proposed cellular facility is located within the same parcel as two existing
single-family residences. The County may or may not consider the residences on the same
parcel as noise-sensitive. For the purposes of this noise analysis, it was assumed that the
County would consider the two existing residences as noise-sensitive and, as a result, the
County’s exterior noise level standards were applied at those locations.
Because subject parcel is zoned A-80 Agricultural, the “Non-Urban” noise standards were
applied in the assessment of the project equipment noise at the nearest residences.
Furthermore, the noise standards were applied at a position 100 feet away from the residences,
as required by Footnote E of Table 1.
Project Noise Generation
Sources and Reference Noise Levels
Noise exposure from the proposed project HVAC units is expected to be approximately 67 dB
(Leq) at a distance of 10 feet from the equipment. This reference noise level of 67 dB at 10 feet
is based on a Bard WA3S1 Wall-Mount Step Capacity Air Conditioner, which is reportedly
similar to the type of equipment being proposed at the project site.
The generator which is proposed at this site would only operate during emergencies (power
outages) and brief daytime periods for periodic maintenance/lubrication. The reference noise
Bollard Acoustical Consultants, Inc.
Environmental Noise Analysis
Afton Road Cellular Facility
Butte County, California
Page 4
level for the generator is 63 dB at 23 feet (Generac Power Systems, Inc. 48 kW SD050 Diesel).
The noise level data specification sheet for the proposed generator is provided as Appendix B.
The project emergency generator would be tested during daytime hours only, and even then
only for brief periods of time. The emergency generator would only operate at night during
power outages. It is expected that nighttime operation of the project emergency generator
would be exempt from the County’s exterior noise exposure criteria due to the need for
continuous cellular service provided by the project equipment.
Predicted Facility Noise Levels at Nearby Sensitive Receptors
As indicated in Figure 1, the project facility maintains a separation of at least 300 feet from the
nearest noise-sensitive receivers. Assuming standard spherical spreading loss (-6 dB per
doubling of distance), project-equipment noise exposure at the nearest noise-sensitive receiver
location was calculated and the results of those calculations are presented in Table 2. The
exterior noise level standards were applied at a point 100 feet away from the residences.
Table 2
Summary of Project-Related Noise Exposure at Nearest Residences
Afton Road Verizon Wireless Telecommunications Facility Project
Receiver1
Distance from Cellular
Equipment (feet)
Predicted Noise Levels (dBA)2,3
HVAC (Leq) Generator (Lmax)
1 360 39 42
2 300 36 39
Notes:
1. Receiver locations can be seen in Figure 1.
2. The predicted equipment noise levels were assessed at a point 100 feet away from the residences.
3. A -5 dB adjustment was applied to the predicted equipment levels at receiver location 2 due to the
shielding provided by the intervening building structure, illustrated on Figure 1.
Because the proposed HVAC units of the equipment shelter could potentially be in operation
during nighttime hours for the duration of an hour, the operation of the HVAC units would be
subject to the County’s nighttime noise level standard of 40 dB Leq. As shown in Table 2, the
predicted HVAC noise levels of 36-39 dB Leq at the nearest noise-sensitive receiver locations
would satisfy the Butte County 40 dB Leq nighttime noise level standard. As a result, no
additional noise mitigation measures would be warranted for this aspect of the project.
Because the project generator would only operate during daytime hours for brief periods
required for testing and maintenance, the operation of the generator would be subject to the
County’s daytime noise level standard of 60 dB Lmax. As shown in Table 2, the predicted
generator noise levels of 39-42 dB Lmax would satisfy the Butte County 60 dB Lmax daytime noise
level standard. As a result, no additional noise mitigation measures would be warranted for this
aspect of the project.
Bollard Acoustical Consultants, Inc.
Environmental Noise Analysis
Afton Road Cellular Facility
Butte County, California
Page 5
Conclusions
Based on the equipment noise level data and analyses presented above, project-related
equipment noise exposure is expected to satisfy the applicable Butte County noise exposure
limits at the closest residential receivers. As a result, no additional noise mitigation measures
would be warranted for this project.
This concludes our environmental noise assessment for the proposed Afton Road Cellular
Facility in Butte County, California. Please contact me at (916) 663-0500 or
paulb@bacnoise.com if you have any questions or require additional information.
Appendix A
Acoustical Terminology
Acoustics The science of sound.
Ambient The distinctive acoustical characteristics of a given space consisting of all noise sources
Noise audible at that location. In many cases, the term ambient is used to describe an existing
or pre-project condition such as the setting in an environmental noise study.
Attenuation The reduction of an acoustic signal.
A-Weighting A frequency-response adjustment of a sound level meter that conditions the output signalto approximate human response.
Decibel or dB Fundamental unit of sound, A Bell is defined as the logarithm of the ratio of the soundpressure squared over the reference pressure squared. A Decibel is one-tenth of a Bell.
CNEL Community Noise Equivalent Level. Defined as the 24-hour average noise level with
noise occurring during evening hours (7 - 10 p.m.) weighted by a factor of three andnighttime hours weighted by a factor of 10 prior to averaging.
Frequency The measure of the rapidity of alterations of a periodic signal, expressed in cycles persecond or hertz.
Ldn Day/Night Average Sound Level. Similar to CNEL but with no evening weighting.
Leq Equivalent or energy-averaged sound level.
Lmax The highest root-mean-square (RMS) sound level measured over a given period of time.
Loudness A subjective term for the sensation of the magnitude of sound.
Masking The amount (or the process) by which the threshold of audibility is for one sound is raised
by the presence of another (masking) sound.
Noise Unwanted sound.
Peak Noise The level corresponding to the highest (not RMS) sound pressure measured over a given
period of time. This term is often confused with the Maximum level, which is the highest
RMS level.
RT6060 The time it takes reverberant sound to decay by 60 dB once the source has beenremoved.
Sabin The unit of sound absorption. One square foot of material absorbing 100% of incident
sound has an absorption of 1 sabin.
SEL A rating, in decibels, of a discrete event, such as an aircraft flyover or train passby, that compresses the total sound energy of the event into a 1-s time period.
Threshold The lowest sound that can be perceived by the human auditory system, generally
of Hearing considered to be 0 dB for persons with perfect hearing.
Threshold Approximately 120 dB above the threshold of hearing.
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