17-105489-Noise Study-04-02-2020-V13
Prepared for:
Federal Way Campus, LLC
Prepared by:
Ramboll US Corporation
March 2020
Project Number:
1690002846
WOODBRIDGE BUSINESS PARK
DEVELOPMENT,
FEDERAL WAY, WASHINGTON
ENVIRONMENTAL NOISE REPORT
FEDERAL WAY, WASHINGTON
ENVIRONMENTAL NOISE REPORT
Executive Summary i Ramboll
EXECUTIVE SUMMARY
Ramboll US Corporation (Ramboll) completed a study of noise-related issues surrounding
the proposed development of three new buildings of varying sizes for Federal Way Campus,
LLC. The Technology Center (Tech Center) at the existing site will remain; however, the
parking lot associated with the Tech Center will be reconfigured to allow for the construction
of the new warehouse buildings (the Project). Building 1 will be 605,195 square feet in size,
Building 2 will be 240,675 square feet in size, and Building 3 will be 125,520 square feet in
size.
Existing sound levels were measured to document the ambient noise environment at a
residential property located immediately southeast of the Project. The measurement
location was considered representative of existing sound levels at several residential and
commercial properties in the Project vicinity.
Acoustically significant equipment anticipated during normal operations of the Project were
assumed to include rooftop HVAC units, Make-Up Air units, exhaust fans, ground-level
cooling towers, and truck traffic for loading and unloading of products.
Using noise source data from previously measured equipment similar to what is existing and
anticipated at the Project buildings, a noise model was prepared to estimate noise levels
received at nearby residential and commercial locations. An assessment of noise impact
was based on compliance with the applicable WAC noise limits, and on the predicted
increase over existing ambient conditions.
The assessment found that noise associated with the proposed Project would result in
negligible increases in ambient noise and would be within compliance of applicable noise
limits. An evaluation of the actual facility design, once submitted, should be completed to
ensure that the equipment to be installed at the warehouses, as well as warehouse
activities, are consistent or similar to those identified in this report.
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ENVIRONMENTAL NOISE REPORT
Contents ii Ramboll
CONTENTS
Executive Summary .................................................................................................. i
Contents .................................................................................................................. ii
Acronyms and Abbreviations .................................................................................. iii
1. Introduction .................................................................................................... 1
1.1 Project Description ...................................................................................... 1
1.2 Rationale for Noise Study ............................................................................. 1
2. Noise Terminology and Descriptors ................................................................. 2
3. Regulatory Setting ........................................................................................... 4
3.1 City of Federal Way ..................................................................................... 4
3.2 Washington Administrative Code ................................................................... 4
4. Existing Environment ....................................................................................... 6
4.1 Affected Environment .................................................................................. 6
4.2 Existing Noise Environment .......................................................................... 6
5. Noise Impact Assessment ................................................................................ 9
5.1 Construction Noise Assessment ..................................................................... 9
5.1.1 Construction Noise Best Management Practices ................................... 10
5.2 Operational Noise Assessment .................................................................... 10
5.2.1 Noise Prediction Model ..................................................................... 11
5.2.2 Emission Sources ............................................................................ 11
5.2.3 Noise Sensitive Receivers ................................................................. 13
5.2.4 Noise Modeling Results – Assessment of Compliance with WAC Limits .... 13
5.2.5 Noise Modeling Results – Assessment of Increase over Existing
Conditions ...................................................................................... 14
5.2.6 Additional Considerations – Loading Docks ......................................... 14
5.2.7 Additional Considerations – Off Site Traffic ......................................... 15
5.2.8 Operational Noise Assessment Results Summary ................................. 16
6. Conclusions ................................................................................................... 19
APPENDICIES
Appendix A - Figures
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Contents iii Ramboll
ACRONYMS AND ABBREVIATIONS
Acoustically neutral ............... A description of equipment or material such as a wind screen
used over a sound level meter microphone that, due to its
composition, has little or no effect on the sound pressure
levels reaching the microphone
Day-night sound level (Ldn) ... A 24-hour sound level metric similar to a 24-hour Leq, except
the Ldn includes an additional 10 dBA added to sound levels
in each hour between 10 PM and 7 AM to account for
increased sensitivity to noise during times when people are
typically trying to sleep
dB ....................................... decibel, referring to a unit measured on the decibel scale
used to quantify sound levels
dBA ..................................... A-weighted decibel, a system for weighting measured sound
levels to reflect the frequencies that people hear best
Distance attenuation .............. the rate at which sound levels decrease with increasing
distance from a noise source based on the dissipation of
sound energy as the sound wave increases in size (think of a
balloon getting thinner as it becomes more inflated)
Equivalent sound level (Leq) ... A sound level metric that is the level that if held constant
over the same period of time would have the same sound
energy as the actual, fluctuating sound (i.e., an energy-
average sound level)
Leq ...................................... Equivalent sound level (see above)
Ln ........................................ Statistical noise level, the level exceeded during n percent of
the measurement period, where n is a number between 0
and 100 (for example, L50 is the level exceeded 50 percent
of the time)
Noise criteria ........................ A set of definitions establishing the conditions under which a
noise impact is determined to have occurred.
Noise impact......................... A measured or model-calculated condition in which the
absolute (i.e., total) sound level and/or a project-related
sound level increase exceed a defined noise impact criterion.
Noise metric ........................ One of a number of measures used to quantify noise (e.g.,
Leq, or Lmax)
SLM ..................................... Sound level measurement
Sound level ......................... Sound pressure level (see below)
Sound power level ................. A measure of the sound energy emitted by noise source
expressed as energy per unit of time. Not to be confused
with sound pressure level.
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Contents iv Ramboll
Sound pressure level ............ Ten times the base-10 logarithm of the square of the ratio of
the mean square sound pressure, in a stated frequency band
(often weighted), and the reference mean-square sound
pressure of 20 μPa (micro pascals, a standard reference unit
of pressure), which is approximately equal to the threshold
of human hearing at 1 kilohertz. Sound pressure level is
expressed in decibels.
Type I meter ........................ A type of sound level meter defined by American National
Standards Institute as being to measure sound pressure
levels to an accuracy within 0.5 dBA
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ENVIRONMENTAL NOISE REPORT
Introduction 1 Ramboll
1. INTRODUCTION
1.1 Project Description
Federal Way Campus, LLC is proposing to develop three new buildings of varying sizes. The
Technology Center (Tech Center) will remain; however, the parking lot associated with the
Tech Center will be reconfigured to allow for the construction of the new warehouse
buildings (the Project). Building 1 will be 605,195 square feet in size, Building 2 will be
240,675 square feet in size, and Building 3 will be 125,520 square feet in size. The Project
will include accessory parking for up to 1,551 vehicles. Site access will be provided by four
driveways located on Weyerhaeuser Way South. Right-of-Way dedication and frontage
improvements to meet the City’s Comprehensive Plan area are also proposed as part of the
Greenline Business Park Development.
At the time of this analysis, the exact use of the warehouses had not been established.
However it is anticipated that the warehouses will be used for general commodities that do
not require cold storage. Furthermore, the warehouses will not include processing or
manufacturing facilities. Equipment typical of a general commodities warehouses include
HVAC units to provide heating and cooling to office spaces; air handling equipment, such as
make-up air units (MUAs), to provide heat and ventilation to warehouse spaces; rooftop
exhaust vents; emergency generators; and access for truck deliveries and product loadout.
1.2 Rationale for Noise Study
The City of Federal Way has established submittal requirements for Process III application s.
These requirements include topographical surveys, site plans, drainage, building design, and
noise studies to support the application.
The City is also requiring a SEPA checklist be submitted as part of the application. The
checklist includes the following questions pertaining to noise:
• SEPA 7(b)(1): What types of noise existing in the area that may affect your project?
• SEPA 7(b)(2): What types and levels of noise would be created by or associated with
the project on a short-term or a long-term basis?
• SEPA 7(b)(1): Proposed measures to reduce or control noise impacts, if any?
The following noise assessment has been prepared to respond to the requirements of the
City’s Process III application and to support SEPA checklist and threshold determination.
The noise assessment evaluates both short-term noise from construction of the Project and
long-term noise from operation of the Project. The assessment of operational noise
evaluates compliance with applicable noise limits and the potential for noise impacts due to
increases over existing sound levels.
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Noise Terminology and Descriptors 2 Ramboll
2. NOISE TERMINOLOGY AND DESCRIPTORS
Noise is sometimes defined as unwanted sound. This report makes no such distinction, and
the terms noise and sound are used more or less synonymously.
The human ear responds to a very wide range of sound intensities. The decibel scale (dB)
used to describe sound is a logarithmic rating system which accounts for the large
differences in audible sound intensities. This scale accounts for the human perception of a
doubling of loudness as an increase of 10 dB. Therefore, a 70-dB sound level will sound
about twice as loud as a 60-dB sound level. People generally cannot detect differences of 1
or 2 dB. In ideal laboratory situations, differences of 2 or 3 dB can be detected by people,
but such a change probably would not be noticed in a typical outdoor environmen t. A 5-dB
change would probably be clearly perceived by most people under normal listening
conditions.
On the logarithmic decibel scale used to describe noise, a doubling of sound-generating
activity (i.e., a doubling of the sound energy) causes a 3-dB increase in average sound
produced by that source, not a doubling of the loudness of the sound (which requires a 10 -
dB increase). For example, if traffic along a road is causing a 60 dB sound level at some
nearby location, twice as much traffic on this same road would cause the sound level at this
same location to increase to 63 dB. Such an increase might not be discernible in a complex
acoustical environment.
When addressing the effects of noise on people, it is useful to consider the frequency
response of the human ear. Sound-measuring instruments are therefore often programmed
to “weight” measured sounds based on the way people hear. The frequency-weighting most
often used is A-weighting because it approximates the frequency response of human
hearing and is highly correlated to the effects of noise on people. Measurements from
instruments using this system are reported in "A weighted decibels" or dBA. All sound levels
in this evaluation are reported in A weighted decibels.
Relatively long, multi-source “line” sources, such as roads with continuous traffic, emit
cylindrical sound waves. Due to the cylindrical spreading of these sound waves, sound levels
from such sources decrease with each doubling of distance from the source at a rate of
about 3 dBA. Sound waves from discrete events or stationary “point” sources, such as a car
horn, spread as a sphere, and sound levels from such sources decrease 6 dBA per doubling
of the distance from the source. Conversely, moving half the distance closer to a source
increases sound levels by 3 dBA and 6 dBA for line and point sources, respectively.
For a given source, a number of factors affect the sound transmission from the source,
which in turn affect the potential for noise impacts. Important factors include distance from
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Noise Terminology and Descriptors 3 Ramboll
the source, frequency of the sound, atmospheric conditions, absorbency and roughness of
the intervening ground surface, the presence or absence of intervening obstructions (e.g.,
buildings), and the duration of the noise-producing event. The degree of impact on humans
also depends on who is listening (individual physiological and psychological factors) and on
existing sound levels (background noise).
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ENVIRONMENTAL NOISE REPORT
Regulatory Setting 4 Ramboll
3. REGULATORY SETTING
3.1 City of Federal Way
The City of Federal Way has established a noise ordinance in the Federal Way Revised Code
(FWRC) Chapter 7.10, Noise. FWRC 7.10.050(1) adopts the maximum permissible sound
level limits identified in the Chapter 173-60 of the Washington Administrative Code (WAC
173-60, see Section 3.2).
FWRC 7.10.020, Public Disturbance Noise, also identifies activities and events that are
considered by the City to cause a public disturbance. FWRC 7.10.020(8) identifies
construction noise as a public disturbance noise when it occurs between the hours of 8:00
p.m. and 7:00 a.m. on weekdays and 8:00 p.m. and 9:00 a.m. on weekends.
3.2 Washington Administrative Code
The City of Federal Way adopts the sound level limits established in WAC 173-60. WAC
173-60 identifies limits on sounds crossing property boundaries based on the Environmental
Designation for Noise Abatement (EDNA) of the sound source and the receiving propert ies.
EDNA classifications are typically designated based on land uses as follows :
EDNA Class A: Lands where human beings reside and sleep (e.g., residences, hospitals).
EDNA Class B: Lands involving uses requiring protection against noise interference with
speech (e.g., commercial and retail businesses, offices, public services).
EDNA Class C: Lands involving economic activities of such a nature that higher noise
levels than experienced in other areas is normally to be anticipated (e.g., industrial
property; warehouse and distribution facilities).
The applicable noise limits for EDNA source and receiver combinations are listed in Table 1.
Table 1. WAC Maximum Permissible Sound Level Limits
EDNA of
Source Property
EDNA of Receiving Property
Class A (a) Class B Class C
Class A 55 57 60
Class B 57 60 65
Class C 60 65 70
(a) The limitations for noise received in Class A EDNAs are reduced by 10 dBA during nighttime hours,
defined in the state rule as 10 p.m. to 7 a.m.
Source: WAC 173-60-40
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Regulatory Setting 5 Ramboll
The "maximum permissible" environmental noise levels may be exceeded for short periods
by a total of not more than 15 minutes in any one-hour period. The allowed short-term
increases follow: up to 5 dBA for no more than 15 minutes in any hour, or up to 10 dBA for
no more than 5 minutes of any hour, or up to 15 dBA for no more than 1.5 minutes of any
hour. These allowed short-term increases can be described in terms of noise metrics that
represent the percentage of time certain levels are exceeded. For example, the hourly L 25
metric represents the sound level that is exceeded 25 percent of the time or 15 minutes in
an hour. Similarly, the L8.3 and L2.5 are the sound levels exceeded 5 and 1.5 minutes in an
hour, respectively. The maximum permissible levels are not to be exceeded by more than
15 dBA at any time, and this limit is represented by the Lmax noise metric.
The zoning for the Project site is Corporate Park (CP-1). The proposed use of the site as
warehouses or distribution facility would result in its classification as a Class C EDNA noise
source. Residential properties in the Project vicinity are classified as Class A receiving
properties. Adjacent commercial buildings are designated Class B EDNA receivers.
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ENVIRONMENTAL NOISE REPORT
Existing Environment 6 Ramboll
4. EXISTING ENVIRONMENT
4.1 Affected Environment
The Project would be located on five parcels encompassing approximately 136 acres, and
the three new warehouses would cover approximately 971,390 square foot area (see
Appendix A, Figure 3), with additional area for parking and truck loading. The
warehouses would be bordered to the east by Weyerhaeuser Way S and the west shore of
North Lake, beyond which are residential land uses; to the north by commercial buildings;
to the west by I-5, beyond which are residential land uses; and to the south by commercial
property currently operated by Weyerhaeuser.
The Weyerhaeuser Tech Center is located on the existing Project site, surrounded by
densely wooded vegetation. The Tech Center will remain, however the parking lot
associated with the Tech Center will be reconfigured and some of the densely wooded area
would be cleared to make room for the new warehouse buildings, parking lots, and
driveways.
4.2 Existing Noise Environment
The existing acoustic environment within the Project vicinity is typical of a subu rban area
relatively close to major highways and/or local roadways. The main source of noise in the
Project vicinity is from traffic along I-5 and Weyerhaeuser Way South.
A sound level measurement was taken in December 2016 to characterize the existing noise
environment in the project vicinity. The sound level measurement was conducted over a
period of four days, including both weekdays and weekend days, at a location
representative of residential properties in the vicinity of the Project, at 33636 30th Avenue
S in Federal Way. The meter was placed in the backyard of this property to represent noise
levels experienced at outdoor residential use areas near North Lake. The measurement
location is illustrated in Appendix A, Figure 1.
The sound level measurement was taken using a Larson Davis model LxT Class I sound level
meter set to capture hourly data over the four-day period. The meter's microphone was
placed in an acoustically-neutral wind screen positioned approximately five (5) feet above
ground. The meter was factory calibrated within the previous 12 months and was field
calibrated immediately prior to use.
The meter was located below the grade of Weyerhaeuser Way S and there was no direct line
of sight between the meter and Weyerhaeuser Way S. However, when present, traffic noise
from this road was a dominant noise source. Traffic noise from I-5, approximately 2,200
feet northwest, was observed as continuous and a steady source of background noise.
Additional noise sources included infrequent miscellaneous residential activity and birds.
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Existing Environment 7 Ramboll
Sound level measurement data are summarized in Table 2 and depicted graphically in
Figure 2. Included in Table 2 is the range of hourly average Leq1 and hourly Ln2 sound
level data for daytime (7 a.m. to 10 p.m.) and nighttime (10 p.m. to 7 a.m.) periods, as
well as the day-night sound level (Ldn3) for each day.
Table 2. Ambient Noise Monitoring Summary (dBA)
Period of
Measurement
Time of
Day (a)
Range of Hourly Sound Levels (b), (c)
Ldn
Leq Range L25 L8.2 L2.5 Lmax
Weekday
Day 51-59 52-59 54-62 56-65 63-77
59 - 60
Night 50-58 49-58 51-62 53-65 59-76
Weekend
Day 52-58 50-56 53-62 59-66 67-78
59
Night 46-55 47-54 48-61 49-65 54-73
(a) "Day" refers to the hours between 7 a.m. and 10 p.m., "Night" to the hours between 10 PM and 7 AM.
(b) Contributing sound sources included traffic from Weyerhaeuser Way S, I-5, and SR-18, as well as nearby
residential activity and birds.
(c) The L2.5, L8.3, and L25 levels are defined previously in this report in the discussion of the regulatory noise
limits.
Source: Ramboll
The range of data provided in Table 2 indicate that daytime sound levels varied only
slightly between weekday and weekend day and night periods.
As indicated, the applicable WAC sound level limits are based on maximum permissibl e
sound levels and allowed exceedances of these limits (e.g., L 25, L8.3,. etc.). This
assessment of existing conditions includes a computation of these WAC metrics for
comparison, however note that the WAC limits apply only to an assessment of compliance of
the future Project, relative to noise received at nearby residential properties.
The highest levels of noise occurred during the typical morning commute period (i.e.,
between 6 a.m. and 8 a.m.) and evening commute period (i.e., between 5 p.m. and 7
1 The Leq is the level that if held constant over the same period of time would have the same sound
energy as the actual, fluctuating sound. As such, the Leq can be considered an energy-average
sound level. This metric should not be confused with an arithmetic average which tends to de-
emphasize high and low values. The Leq noise metric has been found to be highly correlated to
community response to noise, and is often the metric calculated by noise models used to assess
potential impacts and the need for mitigation.
2 The “n” in Ln is the percent of time that a sound level is exceeded and is used describe the range of
sound levels recorded during the measurement period. For example, the L8.3 level is the noise level
that is exceeded 8.3% of the time (e.g., 5 minutes in any one hour).
3 The day-night sound level, Ldn, is similar to a 24-hour Leq, Leq(24), except that a 10-decibel penalty
is added to sound levels between 10 p.m. and 7 a.m. to account for potential sleep interference.
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Existing Environment 8 Ramboll
p.m.). Although Ramboll staff were not present during all measurement hours, it is likely
that traffic on Weyerhaeuser Way S was the source of the highest levels of noise received
during these peak commute periods. A full tabulation of all hourly sound level data can be
made available upon request. See Appendix A, Figure 2 for a graphical overview of
hourly sound level measurement results.
Note that the proposed Project is assumed to operate 24 hours per day, 7 days per week,
although truck traffic activity and generator testing would occur only during daytime hours.
Therefore, the lowest nighttime hourly sound level (46 dBA, Leq), measured between 4 a.m.
and 5 a.m. on Sunday, December 18, 2016, was used to represent the average existing
noise environment when assessing the potential for a worst-case increase over ambient
nighttime conditions (i.e., operation of the Project during nighttime hours). During daytime
hours, the lowest measured sound level was 51 dBA, Leq, measured between 12 p.m. and
1 p.m. on Thursday, December 15, 2016, and was used to represent the average existing
noise environment during daytime hours.
The nighttime and daytime sound levels have been assumed to be representative of the
existing noise environment at all residential receiving properties east of the Project. West
of the Project, the nearest residential properties are located adjacent to I-5 and dominated
by highway traffic noise. Existing noise levels west of I-5 have been assumed to be 50 dBA
during nighttime hours and 60 dBA during daytime hours.
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Noise Impact Assessment 9 Ramboll
5. NOISE IMPACT ASSESSMENT
5.1 Construction Noise Assessment
During construction of the proposed warehouses, there would be temporary increases in
sound levels near active construction areas of the properties due to the use of heavy
equipment and along roadways used for hauling construction materials and for removal of
clearing material (e.g., trees, earth). The increases in noise levels would depend on the type
of equipment being used and the amount of time it is in use. Expected activities include
clearing, grading, excavation, road building, paving, and building construction.
Table 3 displays typical noise levels produced by equipment that could be used during
construction of the Project. Noise from construction equipment decrease at a rate of about
6 dBA for each doubling of distance from the source. Typical construction sound levels are
given for distances of 100, 200, and 400 feet to give some idea of equipment sound levels
at varying distances.
Table 3. Typical Noise Levels From Construction Activities & Equipment (dBA)
Activity
Range of Hourly Leqs
At 100 Feet At 200 Feet At 400 Feet
Clearing 77 71 65
Grading 69-82 63-76 57-70
Paving 66-82 60-76 54-70
Erection 66-78 60-72 54-66
Types of Equipment
Range of Hourly Sound Levels
At 100 Feet At 200 Feet At 400 Feet
Bulldozer 71-90 65-84 59-78
Dump Truck 76-88 70-82 64-76
Scraper 74-87 68-81 62-75
Paver 80-82 74-76 68-70
Generators 65-76 59-70 53-64
Compressors 68-75 62-69 56-63
Source: EPA and others, compiled by Ramboll
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Noise Impact Assessment 10 Ramboll
Site development and construction of the proposed warehouses could generate relatively
high sound levels on and near the project property, particularly at commercial facilities to
the north. Primary sound sources could include excavation and grading equipment, large
haul trucks used for materials such as concrete, and earth and tree removal. Other smaller
pieces of equipment may include generators, compressors, and pumps all with the potential
to contribute to cumulative noise emissions during construction.
As summarized above in Section 3, FWRC 7.10.020(8) states that sounds from construction
sites during nighttime hours are considered a public disturbance (nighttime hours are
defined by the City of Federal Way as between 8:00 p.m. and 7:00 a.m. on weekdays and
between 8:00 p.m. and 9:00 a.m. on weekends).
During daytime hours, when Project construction is expected to occur, construction
activities could result in elevated levels of noise near the Project site. Although daytime
construction could be perceived as intrusive at residential properties, the temporary nature
of construction activities, as well as the limitation of construction to daytime hours only, is
expected to minimize the potential for noise impacts. In addition, the developer would be
expected to employ best management practices to reduce construction noise .
5.1.1 Construction Noise Best Management Practices
The following best management practices, if employed by the construction contractor, would
reduce the potential for high levels of noise during construction activities, and may reduce
the potential for perceived noise impact:
• Require that all equipment be fitted with properly sized mufflers, and if necessary,
engine intake silencers
• Require that all equipment be in good working order.
• Use quieter construction equipment models if available, and whenever possible use
pneumatic tools rather than diesel or gas-powered tools.
• Place portable stationary equipment as far as possible from existing residential and
noise-sensitive commercial areas, and if necessary, place temporary barriers around
stationary equipment.
• For mobile equipment, consider replacing typical pure-tone backup alarms with ambient-
sensing and/or broadband backup alarms.
5.2 Operational Noise Assessment
Operation of the proposed warehouses is expected to generate noise emissions that would
be received at nearby residential and commercial facilities. Noise from stationary
equipment, as well as from mobile sources such as trucks, are common at a light industrial
business parks. The following summarizes the assessment completed to evaluate
operational noise from these sources and includes a summary of the noise model used for
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Noise Impact Assessment 11 Ramboll
the assessment, details of the expected sound sources, a review of nearby noise sensitive
receiving properties, and assessment results.
5.2.1 Noise Prediction Model
Ramboll completed noise modeling using the CadnaA noise model, based on the noise
propagation algorithms established in ISO 9613-2. CadnaA is a computerized noise
prediction model that can calculate sound levels after considering the noise reductions or
enhancements of a range of factors including distance, topography, ground surface types,
intervening structures, atmospheric absorption, and meteorological conditions. Noise
sources were based on frequency-specific measurements of representative equipment or on
estimates of equipment noise levels based on relative throughput ratings for specified
equipment. The modeling considered noise emissions from all Project-related sources and
predicted off-site sound levels at nearby receptor locations.
The Project buildings were modeled at an assumed height of 45 feet, and local topography
was imported from a publicly-available online source. Ground was assumed to be soft, or
acoustically “absorptive”, with the exception of paved roads, parking lots, and North Lake.
The paved roads, parking lots, and North Lake were modeled as hard, or acoustically
“reflective”, increasing noise transmission across these surfaces. Other obstructions, such as
all existing trees within the Project, as well as off-site buildings, were not included.
Estimates of sound levels received at the closest sensitive receivers therefore are
considered conservative.
5.2.2 Emission Sources
Noise modeling was completed based on assumed business park operations for each of the
proposed new warehouses. Note that the existing building also was included in the
modeling assessment to fully assess overall noise emissions from the business park. Sound
level data for typical warehouse sources were taken from Ramboll’s sound source library
and included the sources identified in Table 4.
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Table 4. Noise Source Summary by Building
Building Equipment Type Total Number of Units b, c Operating Period
Tech Center
(Existing Building)
HVAC 3 Day / Night
Exhaust Fan 20 Day / Night
Make Up Air Unit 8 Day / Night
Cooling Tower a 2 Day / Night
Emergency Generator 1 Day
Building 1
HVAC 5 Day / Night
Exhaust Fan 15 Day / Night
Make Up Air Unit 10 Day / Night
Emergency Generator 1 Day
Building 2
HVAC 6 Day / Night
Exhaust Fan 15 Day / Night
Make Up Air Unit 12 Day / Night
Emergency Generator 1 Day
Building 3
HVAC 3 Day / Night
Exhaust Fan 12 Day / Night
Make Up Air Unit 6 Day / Night
Emergency Generator 1 Day
Truck Routes
(All Buildings)
Building 1, North Side 17 trucks/hr Day
Building 1, South Side 17 trucks/hr Day
Building 2 & 3 17 trucks/hr Day
(a) Each cooling tower assumed to have 2 fans, modeled as 2 sources per tower
(b) Each unit modeled as an individual noise source
(c) All units assumed to be operating continuously over an hour
Source: Ramboll
As noted in Table 4, all sound sources were assumed to operate continuously and
concurrently during daytime hours (i.e., between 7 a.m. and 10 p.m.). Note that the
assessment also assumes that all emergency power generators would be tested
simultaneously for a full hour, an unlikely and worst-case operating scenario.
During nighttime hours, there would be no truck traffic at the business park and no testing
of the emergency power generators.
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Noise Impact Assessment 13 Ramboll
An illustration of the assumed location of equipment at each warehouse is found in
Appendix A, Figure 4.
Table 5 provides a tabular summary of the sound levels for each source used in this
assessment.
Table 5. Noise Source Sound Levels (dBA)
Source Type Number of Units Sound Power Level Per Unit (dBA)
Rooftop HVAC Unit 17 86 dBA (a)
Rooftop Exhaust Fan 62 90 dBA (a)
Rooftop MUA Unit 36 88 dBA (a)
Cooling Tower Fan 4 88 dBA (a)
Emergency Generator 4 100 dBA (b)
Truck Route 51 per hour total over 3 routes (17 each) 105 dBA (per truck) (a)
(d) Sound power level based on sound level measurements taken by Ramboll
(e) Sound level for generator based on manufacturer specifications for 30 kW generator plus 5 dBA penalty
added to conservatively estimate potentially larger generators at the Project.
Source: Ramboll
5.2.3 Noise Sensitive Receivers
Noise modeling was completed to estimate operational noise levels at receptors in the
Project vicinity. A graphical illustration of noise-sensitive receiving locations is found in
Figure 3.
5.2.4 Noise Modeling Results – Assessment of Compliance with WAC Limits
Model-calculated sound levels are presented in Table 7, and graphical representations of
results for daytime and nighttime hours are found in Appendix A, Figure 5 and Figure 6,
respectively, illustrating noise contours for each time period.
At the nearest Class A EDNA receiver represented by R8, located west of I-5 (see Figure
3), predicted worst-case operating conditions would resul t in an hourly nighttime sound
level of 39 dBA, well below the applicable nighttime limit of 50 dBA. During daytime hours
the predicted sound levels at R8 would be 43 dBA, well below the applicable daytime limit of
60 dBA.
East of the Project, the nearest residences are represented by receptor R4 (see Figure 3),
representing west-facing waterfront property on North Lake. At R4, Project sound levels
could reach up to 44 dBA during daytime hours and 38 dBA during nighttime hours. Noise
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ENVIRONMENTAL NOISE REPORT
Noise Impact Assessment 14 Ramboll
levels in this range are far below the applicable WAC day and night limits of 60 dBA and 50
dBA, respectively.
At the nearest Class B EDNA receiver, represented by C1, located adjacent to the north of
the Project (see Figure 3), predicted worst-case operating conditions would result in an
hourly sound level of 52 dBA, well below the applicable limit of 65 dBA (applicable during
both daytime and nighttime hours). Operational sound levels at all remaining Class B EDNA
receivers are predicted to be lower than 52 dBA.
Operation of the Project is expected be in compliance with the applicable WAC sound level
limits at all nearby Class A and Class B EDNA receivers during both daytime and nighttime
hours.
5.2.5 Noise Modeling Results – Assessment of Increase over Existing Conditions
The assessment of increase in noise over ambient conditions is determined by adding
Project noise to ambient noise levels, and evaluating against ambient noise levels without
the Project. Note that Project noise levels that are 10 dBA or more below ambient
conditions, when added to ambient noise levels, would result in no net increase in noise.
The nearest Class A EDNA receiver (R8), is located on the west side of I-5, very near the
highway, and very likely dominated by I-5 traffic noise. As indicated, ambient sound levels
at this location conservatively have been assumed to be 50 dBA during nighttime hours and
60 dBA during daytime hours. Therefore Project-related noise levels of 39 dBA during
nighttime hours and 43 dBA during daytime hours would result in no noise increase and
would not be audible at this location.
East of the Project site, on the east side and north of North Lake, noise sensitive receptors
currently are exposed to much quieter ambient noise levels, assumed to be similar to
measured levels (see Table 2). Worst-case and unlikely Project operating conditions during
nighttime hours would be up to 38 dBA at the most affected receptor, R4. The Project
therefore would be well below the quietest nighttime sound level of 46 dBA, and would
result in an acoustically negligible increase of 1 dBA over ambient conditions . During
daytime hours, worst-case operation of the Project would be up to 44 dBA at this location,
well below the quietest daytime hour sound level of 51 dBA during weekdays, and resulting
in an acoustically negligible increase of 1 dBA over ambient conditions (see Table 2).
Note that increases over ambient conditions are not evaluated for commercial receivers.
5.2.6 Additional Considerations – Loading Docks
Noise emissions from up to 51 trucks per hour, divided equally over 3 truck routes, would
include driveways for ingress and egress, as illustrated in Figure 4. Although trucks would
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ENVIRONMENTAL NOISE REPORT
Noise Impact Assessment 15 Ramboll
be expected to load and unload at warehouse loading docks, noise from typical loading dock
activities would be negligible when compared to noise from truck movement. Therefore,
loading dock activity is not anticipated to generate noise emissions that would exceed the
sources evaluated for this study.
5.2.7 Additional Considerations – Off Site Traffic
Noise from traffic traveling on public roadways is exempt from WAC 173-60 for vehicles
regulated under WAC 173-62 (WAC 173-60-50(4)(a)). Therefore, noise from traffic
accessing the Project would be exempt from the WAC (and therefore from FWRC) when
traveling on public roadways. However, increases in traffic volumes on area roadways may
result in increases in ambient noise levels during peak Project hours.
Trucks accessing the Project (maximum assumed total volume of 51 trucks per hour) are
expected to arrive along Weyerhaeuser Way South to/from SR-18 to the south, or S 320th
Street to the north. Automobile traffic accessing the Project, including staff and visitors,
would access the site using the ingress/egress points on Weyerhaeuser Way South.
Class A EDNA receivers identified along the potential access routes are south of the Project,
north of the roundabout at Weyerhaeuser Way South and 33rd Place S (in the vicinity of
R7). Applying traffic volumes from the Project’s traffic study, during the a.m. and p.m.
peak-hour periods, existing sound levels at the Class A EDNA (residence) near the
roundabout are estimated to be approximately 62 and 63 dBA, respectively. A future No
Build scenario (i.e., without the Project) during the a.m. and p.m peak-hour periods would
result in sound levels of 63 and 64 dBA, respectively. With the Project, sound levels during
the a.m. and p.m. peak hour periods increase to 64 and 65 dBA, a 1-dBA increase over the
No Build peak periods. Note that a 1-dBA increase is acoustically insignificant and would be
not be noticed. Therefore Project-related traffic is not expected to result in off-site traffic-
related impacts. Results are summarized in Table 6.
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ENVIRONMENTAL NOISE REPORT
Noise Impact Assessment 16 Ramboll
Table 6. Off-Site Traffic Noise near R7 (dBA)
Peak Period Existing Sound
Levels (a)
Future No Build
Scenario (a)
Future With Project
Scenario (b)
Increase, With
Project over No
Build Scenario
AM 62 63 64 1
PM 63 64 65 1
Notes:
(a) Traffic modeling based on an assumed traffic composition of 97% cars, 2% medium duty trucks, 1% heavy
duty trucks
(b) Traffic modeling based on same existing and No Build traffic composition, plus an assumed additional 28
heavy-duty trucks, representative of half of all Project -related truck traffic during the peak-hour periods
Source: Ramboll
5.2.8 Operational Noise Assessment Results Summary
As indicated, operation of the Project is expected to comply with WAC noise limits at all
nearby Class A and Class B EDNA receivers, as is summarized in Table 7 and Table 8. The
predicted worst-case increase over existing conditions during nighttime and daytime hours
is not expected to be perceptible at the nearest Class A EDNA receivers. Noise mitigation
measures are not warranted at this time for on-site sources of noise.
In addition, off-site increases in traffic noise due to the Project are estimated to be
acoustically insignificant and would not result in off-site traffic noise impacts.
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ENVIRONMENTAL NOISE REPORT
Noise Impact Assessment 17 Ramboll
Table 7. Noise Modeling Results: Nighttime Hours (dBA)
Receiver
A
Background: Existing
Noise Level During
Quietest Nighttime
Hour (a)
Assessment of Noise Impact Assessment of WAC Compliance
B
Project Only Sound
Levels Nighttime
Hours
C
Project plus
Background
(A + B)
D
Increase from Project
+ Background Over
Background
(C - A) (b)
E
WAC Nighttime
Sound Level
Limit
F
Project Only (B)
Complies with
WAC?
R1
46
34 46 0
50 (c)
Yes
R2 36 46 0 Yes
R3 35 46 0 Yes
R4 38 47 1 Yes
R5 37 47 1 Yes
R6 36 46 0 Yes
R7 34 46 0 Yes
R8
50
39 50 0 Yes
R9 39 50 0 Yes
C1 (d) 42 (e) (e) 65 Yes
(a) Existing noise level measured at 33636 30th Avenue South, used to represent existing environment at residential noise receiver locations R1
through R7; R8 and R9 existing nighttime noise levels conservatively estimated based on proximity to I -5.
(b) Tabulated results are rounded to the nearest whole number, and apparent calculations errors are due to rounding.
(c) Represents the nighttime sound level limits, 10-dBA below the daytime limit of 60 dBA.
(d) Assessment of Noise Increase Not Applicable to Class B EDNA Receivers
(e) Assessment of Noise Increase Not Applicable to Class B EDNA Receivers
Source: Ramboll
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ENVIRONMENTAL NOISE REPORT
Noise Impact Assessment 18 Ramboll
Table 8. Noise Modeling Results: Daytime Hours (dBA)
Receiver
A
Background: Existing
Noise Level During
Quietest Daytime
Hour (a)
Assessment of Noise Impact Assessment of WAC Compliance
B
Project Only Sound
Levels Daytime Hours
C
Project plus
Background
(A + B)
D
Increase from Project
+ Background Over
Background
(C - A) (b)
E
WAC Daytime
Sound Level
Limit
F
Project Only (B)
Complies with
WAC?
R1
51
40 51 0
60 (c)
Yes
R2 42 52 1 Yes
R3 42 51 0 Yes
R4 44 52 1 Yes
R5 42 52 1 Yes
R6 41 51 0 Yes
R7 38 51 0 Yes
R8
60
43 60 0 Yes
R9 42 60 0 Yes
C1 (d) 52 (e) (e) 65 Yes
(a) Existing noise level measured at 33636 30th Avenue South, used to represent existing environment at residential noise receiver locations R1
through R7; R8 and R9 existing daytime noise levels conservatively estimated based on proximity to I -5.
(b) Tabulated results are rounded to the nearest whole number, and apparent calculations errors are due to rounding.
(c) Represents the nighttime sound level limits, 10-dBA below the daytime limit of 60 dBA.
(d) Assessment of Noise Increase Not Applicable to Class B EDNA Receivers
(e) Assessment of Noise Increase Not Applicable to Class B EDNA Receivers
Source: Ramboll
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ENVIRONMENTAL NOISE REPORT
Conclusions 19 Ramboll
6. CONCLUSIONS
The proposed Project would be located on five parcels encompassing approximately 136
acres, and the three warehouses would cover approximately 971,390 square foot area in
Federal Way, Washington. The noise assessment was prepared to respond to the
requirements of the City’s Process III application and to support the Project’s SEPA
checklist.
Sound level measurements were taken at a residential property located immediately
southeast of the proposed business park, on a property owned by Weyerhaeuser, and
considered representative of residential properties evaluated for this study.
Construction of the Project is expected to comply with the public disturbance nighttime
timing restrictions established within the Federal Way Revised C ode. Temporary daytime
construction noise is expected to result in short -term increases in noise that may be
mitigated by simple, common sense techniques to reduce construction noise.
During operation, noise emissions for equipment common to warehouses were assumed for
the Project including rooftop HVAC units, Make-Up Air units, and exhaust fans; cooling
towers; emergency generators, and; truck traffic.
A noise model was prepared to estimate operational noise at nearby residential (Class A
EDNA) and commercial (Class B EDNA) receivers. An assessment of noise impact was
based on compliance with the applicable WAC noise limits, and on the predicted increase
over existing ambient conditions at EDNA Class A receivers.
The noise study found that the proposed Project would comply with all applicable WAC limits
during both daytime and nighttime hours. Further, the Project is expected to result in
insignificant or no increases over the existing ambient noise environment at the nearest
residential properties during both nighttime and daytime hours.
Project related traffic is expected to result in acoustically insignificant increases in off-site
traffic noise along nearby access routes, when compared with a No Build scenario.
Noise mitigation measures are not recommended at this time. A detailed review of final
operating conditions should be completed to ensure that this noise study accurately and
conservatively reflects future Project operation.
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ENVIRONMENTAL NOISE REPORT
Appendix A Ramboll
APPENDIX A
Figures
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ENVIRONMENTAL NOISE REPORT
Appendix A Ramboll
Figure 1. Sound Level Measurement Location
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ENVIRONMENTAL NOISE REPORT
Appendix A Ramboll
Figure 2. Long Term Sound Level Measurement - Graphically Summary
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ENVIRONMENTAL NOISE REPORT
Appendix A Ramboll
Figure 3. Project and Noise Receptor Locations
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ENVIRONMENTAL NOISE REPORT
Appendix A Ramboll
Figure 4. Noise Source Locations
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ENVIRONMENTAL NOISE REPORT
Appendix A Ramboll
Figure 5. Noise Model Isopleth Contours: Nighttime Hours
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ENVIRONMENTAL NOISE REPORT
Appendix A Ramboll
Figure 6. Noise Model Isopleth Contours: Daytime Hours