HomeMy WebLinkAbout1.26 Sound Modeling and Testing Report
SOUND MODELING AND TESTING REPORT
NUTRIENT FARM PUD
NUTRIENT HOLDINGS LLC
GARFIELD COUNTY, CO
December 9, 2020
Prepared by
118 West Sixth Street, Suite 200
Glenwood Springs, CO 81601
970.945.1004
970.945.5948 fax
#2018-271.002
Nutrient Farm PUD December 2020
Sound Modeling Report i
TABLE OF CONTENTS
1.0 Introduction 1
2.0 Sound Fundamentals 3
3.0 Proposed Music Venue and Moto Park 4
4.0 CRS 25-12-103 Noise Standards 4
5.0 Music Venue and Moto Park Sound Modeling 5
5.1 Music Venue Sound Modeling Methodology 5
5.2 Sound Sensitive Receptors 5
5.3 Nutrient Farm Music Venue Sound Tests 5
5.4 Moto Park Sound Tests 5
5.5 Sound Modeling Results 10
5.6 Sound Test Results 10
6.0 Conclusion 11
LIST OF TABLES
Table 4-1: CRS 25-12-103 Sound Standards 4
Table 5-1: Modelling Scenarios Employed 10
Table 5-2: Music Volume dBa Readings 10
Table 5-3: Onewheel motorcycle dBa Readings 11
Table 5-4: Zero FX motorcycle dBa Readings 11
LIST OF FIGURES
Figure 1-1: Proposed Use Areas Study 2
Figure 5-1: Nutrient Farm PUD Site Plan 7
Figure 5-2: Sound Test Location: Music Venue 8
Figure 5-3: Sound Test Location: County Road 335 9
LIST OF APPENDICES
Appendix A – Glossary of Acoustical Terms 12
Nutrient Farm PUD December 2020
Sound Modeling Report 1
1.0 Introduction
This report provides a sound testing assessment of the proposed music venue and off-highway
vehicle (OHV) track within the Nutrient Farm PUD in relation to surrounding lands, existing
residential areas, and how the proposed venues adhere to guidance in the Colorado Revised
Statutes (CRS) 25-12-103. The sound testing process includes currently proposed locations of the
music venue and Moto Park.
The Nutrient Farm PUD and the proposed music venue and Moto Park area are located on the south
side of the Colorado River between New Castle and Glenwood Springs (39.56033°N, -107.48101°W;
Figure 1), immediately adjacent to the Riverbend Community. The site is currently dominated by
grazed pastures and undeveloped hillsides on the southern side of the pastures.
Nutrient Farm would be an approximately 1,136-acre, agriculturally oriented mixed-use PUD that
revolves around the use and enjoyment of a working farm with multi-use education, entertainment,
and recreational facilities (Nutrient Farm PUD Guide 2020). The PUD would include a working farm,
a mix of residential homes, a commercial/industrial area, outdoor adventure parks with outdoor
entertainment/music venue, an Moto Park, a campground, lodge, non-motorized trails, and a
retreat/spa facility.
The following is provided in this report:
• A brief introduction to the fundamentals of sound
• A review of applicable State and County sound standards
• Existing conditions
• Discussion of sound testing methodology and results
Nutrient Farm PUD December 2020
Sound Modeling Report 2
Figure 1-1: Proposed Use Areas Study
Nutrient Farm PUD December 2020
Sound Modeling Report 3
2.0 Sound Fundamentals
Sound is most commonly experienced by people as pressure waves passing through the air. These
rapid changes in air pressure are processed by the human ear as the sensation of sound. The rate
at which the pressure fluctuates is called the frequency. Frequency is measured as the number of
oscillations per second, or Hertz (Hz). Audible frequencies range from 20 – 20,000 Hz for a healthy
human ear. Pitches at the lower end of this range are commonly experienced as a “rumble” or a
“boom.” Pitches at the higher end or the range might be described as a “screech” or a “hiss”. Lower
frequencies can have other impacts, such as causing windows to rattle and similar effects.
Sound can vary in volume as well as in pitch. This volume is usually expressed as decibels (dB). The
sound you hear generally comes in two forms. Environmental sound generally comes from a variety
of distant sources, such as distant traffic, wind in trees, and distant industrial or farming activities.
Distant sound sources such as these create a low-level “background sound” in which no individual
source is identifiable. Background sound stays relatively constant moment to moment but can vary
through the day in accordance with natural forces or the daily pattern of human activity.
Superimposed on this background sound is a succession of distinct, identifiable noisy events of brief
duration. This can include the passing of single vehicles, aircraft flyovers, and the passage of sirens.
Detailed acoustical terms have been provided in Appendix A – Glossary of Acoustical Terms.
Nutrient Farm PUD December 2020
Sound Modeling Report 4
3.0 Proposed Music Venue and Moto Park
The outdoor music venue, recreational facilities including motorized tracks, trail and outdoor
adventure parks would introduce different land uses and human activity patterns to the area,
including increased noise from both the music venues and the motorized tracks. The location of both
the music venue and motorized tracks are along the base of the Grand Hogback, away from
residential development.
The music venue would consist of performance areas including a small, raised platform, facing the
steep slopes/hogback to the south. The venue would host a variety of music types (rock, country,
acoustical, electronica, etc.), with amplification also being variable. Nutrient Farm is also planning to
include additional sound dampening through the planting of trees, potential berming, and
aiming/focusing speakers southwest (away from residential areas). Music events will be relatively
small with approximately 50 people, however some music festivals will be planned with up to 350
people in attendance.
The Moto Park would be used by 100% electric vehicles only. These vehicles create virtually no
noise at close proximity and are guaranteed by Nutrient Farm not to become a sound nuisance. A list
of Electric OHVs are listed below:
• Future Motion Onewheel XR+ (already owned)
• Zero FX motorcycle (already owned)
• Tesla unnamed 4x4 (will be available in 2021)
Similar to the music venue, Nutrient Farm is planning to construct earth berms and planting
vegetation to create sound dampening/insertion loss. After further testing, if gasoline-powered
vehicles can prove to not become a sound nuisance, Nutrient Farm may elect to allow customers to
bring their own gasoline-powered vehicles to the park.
4.0 CRS 25-12-103 Noise Standards
SGM initially conducted a sound modelling analysis. The modeling analysis was developed to
predict operational sound levels at adjacent properties and verify compliance of operations with the
Colorado Revised Statutes (CRS) 25-12-103 noise standards. The CRS code establishes
permissible sound levels by type of property and time of day. For the purposes of the law, sound is
measured as “Levels of sound radiating from a property line at a distance of twenty-five feet” and
any sound “In excess of the dB(A) established for the following time periods and zones shall
constitute prima facie evidence that such sound is a public nuisance.” Defined sound levels are
provided in Table 4-1.
Table 4-1: CRS 25-12-103 Sound Standards
Zone 7:00 a.m. to next 7:00 p.m. 7:00 p.m. to next 7:00 a.m.
Residential 55 dB(A) 50 dB(A)
Commercial 60 dB(A) 55 dB(A)
Light Industrial 70 dB(A) 65 dB(A)
Industrial 80 dB(A) 75 dB(A)
The stringency of the sound requirements depends on the zoning of the site; however, the CRS 25-
12-103 does not reference “PUD zoning”, which is how Garfield County has zoned this area. For the
Nutrient Farm PUD December 2020
Sound Modeling Report 5
purposes of classifying the nearby Riverbend community, we assume a Residential zone, per CRS
25-12-103.
5.0 Music Venue and Moto Park Sound Modeling
5.1 Music Venue Sound Modeling Methodology
The SGM sound modeling was completed with the use of three-dimensional (3D) computerized
sound modeling software. All models in this report were developed with SoundPlan Essentials 5.0
software using the ISO 9613-2 standard. Sound levels are predicted based on the locations, sound
levels, and frequency spectra of the sound sources, and the geometry and reflective properties of
the local terrain and barriers. The predicted sound levels only take into consideration the sound
produced by the discrete sources at the music venue and motorized OHV track, using “worst case
scenario” levels such as a rock band and a gasoline-powered dirt bike, and no other sources, such
as traffic, other site operations, neighboring operations, other human activity, or environmental
factors were included.
5.2 Sound Sensitive Receptors
The noise modelling sensitive receptor locations were chosen to be consistent with the requirements
of CRS 25-12-103, specifically that sound levels radiating from the site perimeter (property
boundary) at 25 feet or more, in excess of the dB(A) established for the established time and zone
shall constitute evidence that the sound is a public nuisance. As such, receptor locations were
chosen to give the largest sound level reading, representing potential regulatory measurement
points, should a complaint be made.
5.3 Nutrient Farm Music Venue Sound Tests
Additional sound testing was conducted by Nutrient Farm through employing a variety of amplifiers,
and actual sound levels were recorded with the use of a BAFX Products BAF3370 Digital Sound
Level Meter (range: 30-130 dB(A)). These sound tests were performed in the Nutrient Farm West
pasture, and North of the Vulcan ditch near the proposed music venue area. A sizable professional
audio system was installed as close to the proposed music venue location as possible and the
volume was played at the highest level possible. The following audio speaker system was set up
facing southwest (towards the hogback):
• Eight (8) Funktion1 F121 21” Subs on 10,000-watt FFA amplifier
• Four (4) Funktion1 Evo6 10”/15” Pair Mids on 6,000-watt FFA amplifier
• Four (4) Funktion1 Evo6 1.4” Highs on 3,000-watt FFA amplifier
The audio engineer administering the system stated that a small music event could be operated with
the test system at volume level 4.
5.4 Moto Park Sound Tests
The vehicles used in the test are actual vehicles planned for use in the park. Decibel readings were
recorded by Nutrient Farm staff with the vehicles driving by at various speeds at various distances
from receptors. The following vehicles were tested:
Vehicle Models
• 2018 Future Motion Onewheel XR+
• 2021 Zero FX
Nutrient Farm PUD December 2020
Sound Modeling Report 6
The sound level recordings were completed with the use of a BAFX Products BAF3370 Digital
Sound Level Meter, range: 30-130 dB(A). Receptor location for these tests was at County Road 335
crossing the Nutrient Farm West pasture, just west of the developed Nutrient Farm Road.
Nutrient Farm PUD December 2020
Sound Modeling Report 7
Figure 5-1: Nutrient Farm PUD Site Plan
Music Venue Area
Moto Park Area
Receiver Location #1
Receiver Location #2
Nutrient Farm PUD December 2020
Sound Modeling Report 8
Figure 5-2: Sound Test Location: Music Venue
LEGEND
Orange = Receptor Locations
Yellow = Sound Test Locations
Red = Future Proposed Music Venue Locations
Nutrient Farm PUD December 2020
Sound Modeling Report 9
Figure 5-3: Sound Test Location: County Road 335
LEGEND
Orange = Receptor Locations
Yellow = Sound Test Location
Nutrient Farm PUD December 2020
Sound Modeling Report 10
5.5 Sound Modeling Results
For the music venue, various modeled sound volumes were measured across the project area. Two
receiver locations were chosen due to the potential nuisance to existing residential areas. The
description is found in Table 5-1, and the results of the Nutrient Farm music sound tests is found in
Table 5-2. The results of the Nutrient Farm vehicle sound tests are listed in Table 5-3 and Table 5-4.
Table 5-1: Modelling Scenarios Employed
Modeled Scenario Description
Music Venue
Receptors placed at Location #1 (nearby existing
residence owned by “Chris Lake)and the other receptor
placed in the center of the Riverbend Community
“Riverbend” Location #2. Receptors were also placed in
the front and rear of the speakers.
Vehicles Receptors were measured along County Road 335 as
vehicles drove by at various speeds.
5.6 Sound Test Results
At volume level 4, the sounds first became humanly audible over ambient (background) sounds at both
receptor locations. At volume level 8 the sound levels were still just humanly audible over ambient
sounds at both receptor locations. At the highest system volume (level 10), the highest receptor
reading was 59 dB (A) at Location 2, a couple decibels over ambient sound levels, and four (4) dB (A)
over diurnal Residential sound standards, and nine (9) dB (A) over nighttime Residential sound
standards
Table 5-2: Music Volume dBa Readings
Volume
Level
Location 1
Chris Lake
Location 2
Riverbend
Front of
Speakers
Rear of
Speakers Notes
0 52 57 - - Ambient
1 53 57 72 74
2 53 56 74 75
3 51 58 77 73
4 52 59 81 75 First audible
over ambient
5 53 59 84 76
6 54 59 85 74
7 53 57 87 78
8 54 59 92 82 Audible over
ambient
9 57 59 96 86
10 58 59 101 91
Nutrient Farm PUD December 2020
Sound Modeling Report 11
Table 5-3: Onewheel motorcycle dBa Readings
Speed
Location 1
20’
Distance
Location 2
50’
Distance
Notes
0 55 55 Ambient
15 62 58
Table 5-4: Zero FX motorcycle dBa Readings
Speed
Location 1
50’
Distance
Location 2
100’
Distance
Location 3
200’
Distance
Notes
0 63 58 58 Ambient
10 59 59 55
20 69 63 54
30 66 60 58
40 67 64 60
55 72 68 59
6.0 Conclusion
Predictively modeled sound levels and actual sound tests were conducted to represent the proposed
music venue and motorized OHVs at the Nutrient Farm PUD. Sound sensitive receptors locations
included in the model runs were placed in accordance with the sound standards of CRS 25-12-103.
The numerical sound level results for the music venue can be improved with simple sound diffusion
efforts. Only half of the speakers during the music test had a partial haystack berm behind them to
simulate sound mitigations. The other half of the speakers had no haystack berm at all. In the future, to
achieve better results, larger and more robust berms could be used, and the berms could be used on
all speakers. Crowd noise was not measured during this test however, simple sound barriers such as
orchards and other trees are planned to be planted as sound diffusers, and the proposed music venue
locations would be 0.1 to 0.2-miles further away from the receptor locations than the location of the
sound test speakers.
It is found that the vehicles proposed for use in the Nutrient Adventure Moto Park will not create a
sound nuisance if developed at a responsible distance from residential areas. If the parks are
developed with a minimum distance of 200-feet from any property lines, it is anticipated that no sound
nuisance will be created. These great results can be improved further with sound mitigation efforts.
Performing acoustical engineering techniques, such as using soil berms for sound isolation or planting
dense trees to behave as sound diffusers, will be employed to reduced sound emissions further.
Nutrient Farm PUD December 2020
Sound Modeling Report 12
Appendix A – Glossary of Acoustical Terms
Ambient Noise - The all-encompassing noise associated with a given environment at a specified time,
usually a composite of sound from many sources both near and far.
Average Sound Level - See Equivalent-Continuous Sound Level
Community Noise Equivalent Level (CNEL) - A 24-hour A-weighted average sound level which
considers the fact that a given level of noise may be more or less tolerable depending on when it
occurs. The CNEL measure of noise exposure weights average hourly noise levels by 5 dB for the
evening hours (between 7:00 pm and 10:00 pm), and 10 dB between 10:00 pm and 7:00 am, then
combines the results with the daytime levels to produce the final CNEL value. It is measured in
decibels, dbs.
Day-Night Average Sound Level (Ldn) - A measure of noise exposure level that is similar to CNEL
except that there is no weighting applied to the evening hours of 7:00 pm to 10:00 pm. It is measured
in decibels, dB.
Daytime Average Sound Level - The time-averaged A-weighted sound level measured between the
hours of 7:00 am to 7:00 pm. It is measured in decibels, dB.
Decay Rate - The time taken for the sound pressure level at a given frequency to decrease in a room.
It is measured in decibels per second, dB/s.
Decibel (dB) - The basic unit of measurement for sound level.
Direct Sound - Sound that reaches a given location in a direct line from the source without any
reflections.
Divergence - The spreading of sound waves from a source in a free field, resulting in a reduction in
sound pressure level with increasing distance from the source.
Energy Basis - This refers to the procedure of summing or averaging sound pressure levels based on
their squared pressures. This method involves the conversion of decibels to pressures, then
performing the necessary arithmetic calculations, and finally changing the pressure back to decibels.
Equivalent-Continuous Sound Level (Leq) - The average sound level measured over a specified
time period. It is a single-number measure of time-varying noise over a specified time period. It is the
level of a steady sound that, in a stated time period and at a stated location, has the same A-Weighted
sound energy as the time-varying sound. For example, a person who experiences an Leq of 60 dB(A)
for a period of 10 minutes standing next to a busy street is exposed to the same amount of sound
energy as if he had experienced a constant noise level of 60 dB(A) for 10 minutes rather than the time-
varying traffic noise level. It is measured in decibels, dB.
Fast Response - A setting on the sound level meter that determines how sound levels are averaged
over time. A fast sound level is always more strongly influenced by recent sounds, and less influenced
by sounds occurring in the distant past, than the corresponding slow sound level. For the same non-
steady sound, the maximum fast sound level is generally greater than the corresponding maximum
slow sound level. Fast response is typically used to measure impact sound levels.
Field Impact Insulation Class (FIIC) - A single number rating similar to the impact insulation class
except that the impact sound pressure levels are measured in the field.
Field Sound Transmission Class (FSTC) - A single number rating similar to sound transmission
class except that the transmission loss values used to derive this class are measured in the field.
Nutrient Farm PUD December 2020
Sound Modeling Report 13
Flanking Sound Transmission - The transmission of sound from a room in which a source is located
to an adjacent receiving room by paths other than through the common partition. Also, the diffraction of
noise around the ends of a barrier.
Frequency - The number of oscillations per second of a sound wave
Hourly Average Sound Level (HNL) - The equivalent-continuous sound level, Leq, over a 1-hour
period.
Impact Insulation Class (IIC) - A single number rating used to compare the effectiveness of
floor/ceiling assemblies in providing reduction of impact-generated sound such as the sound of a
person’s walking across the upstairs floor.
Impact Noise - The noise that results when two objects collide.
Impulse Noise - Noise of a transient nature due to the sudden impulse of pressure like that created by
a gunshot or balloon bursting.
Insertion Loss - The decrease in sound power level measured at the location of the receiver when an
element (e.g., a noise barrier) is inserted in the transmission path between the sound source and the
receiver.
Inverse Square Law - A rule by which the sound intensity varies inversely with the square of the
distance from the source. This results in a 6dB decrease in sound pressure level for each doubling of
distance from the source.
Ln Percentile Sound Level - The noise level exceeded for n% of the measurement period where n is
between 0.01% and 99.99%. Usually includes a descriptor i.e. A-weighting. Common Ln values
include LA10, LA50, and LA90 levels. LA10 would represent the A-weighted sound level that is
exceeded for 10% of the measurement period.
Masking - The process by which the threshold of hearing for one sound is raised by the presence of
another sound.
Maximum Sound Level (Lmax) - The greatest sound level measured on a sound level meter during a
designated time interval or event.
NC Curves (Noise Criterion Curves) - A system for rating the noisiness of an occupied indoor space.
An actual octave-band spectrum is compared with a set of standard NC curves to determine the NC
level of the space.
Noise Isolation Class (NIC) - A single number rating derived from the measured values of noise
reduction between two enclosed spaces that are connected by one or more partitions. Unlike STC or
NNIC, this rating is not adjusted or normalized to a measured or standard reverberation time.
Noise Reduction - The difference in sound pressure level between any two points.
Noise Reduction Coefficient (NRC) - A single number rating of the sound absorption properties of a
material. It is the average of the sound absorption coefficients at 250, 500, 1000, and 2000 Hz,
rounded to the nearest multiple of 0.05.
Normalized Noise Isolation Class (NNIC) - A single number rating similar to the noise isolation class
except that the measured noise reduction values are normalized to a reverberation time of 0.5
seconds.
Octave - The frequency interval between two sounds whose frequency ratio is 2. For example, the
frequency interval between 500 Hz and 1,000 Hz is one octave.
Octave-Band Sound Level - For an octave frequency band, the sound pressure level of the sound
contained within that band.
Nutrient Farm PUD December 2020
Sound Modeling Report 14
Outdoor-Indoor Transmission Class (OITC) - A single number rating used to compare the sound
insulation properties of building façade elements. This rating is designed to correlate with subjective
impressions of the ability of façade elements to reduce the overall loudness of ground and air
transportation noise.
Peak Sound Level (Lpk) - The maximum instantaneous sound level during a stated time period or
event.
Point Source - A source that radiates sound as if from a single point.
RC Curves (Room Criterion Curves) - A system for rating the noisiness of an occupied indoor space.
An actual octave-band spectrum is compared with a set of standard RC curves to determine the RC
level of the space.
Real-Time Analyzer (RTA) - An instrument for the determination of a sound spectrum.
Receiver - A person (or persons) or equipment which is affected by noise.
Reflected Sound - Sound that persists in an enclosed space as a result of repeated reflections or
scattering. It does not include sound that travels directly from the source without reflections.
Reverberation - The persistence of a sound in an enclosed or partially enclosed space after the
source of the sound has stopped, due to the repeated reflection of the sound waves.
Room Absorption - The total absorption within a room due to all objects, surfaces and air absorption
within the room. It is measured in Sabins or metric Sabins.
Slow Response - A setting on the sound level meter that determines how measured sound levels are
averaged over time. A slow sound level is more influenced by sounds occurring in the distant past that
the corresponding fast sound level.
Sound - A physical disturbance in a medium (e.g., air) that is capable of being detected by the human
ear.
Sound Absorption Coefficient - A measure of the sound-absorptive property of a material.
Sound Insulation - The capacity of a structure or element to prevent sound from reaching a receiver
room either by absorption or reflection.
Sound Level Meter (SLM) - An instrument used for the measurement of sound level, with a standard
frequency-weighting and standard exponentially weighted time averaging.
Sound Power Level - A physical measure of the amount of power a sound source radiates into the
surrounding air. It is measured in decibels.
Sound Pressure Level - A physical measure of the magnitude of a sound. It is related to the sound’s
energy. The terms sound pressure level and sound level are often used interchangeably.
Sound Transmission Class (STC) - A single number rating used to compare the sound insulation
properties of walls, floors, ceilings, windows, or doors. This rating is designed to correlate with
subjective impressions of the ability of building elements to reduce the overall loudness of speech,
radio, television, and similar noise sources in offices and buildings.
Source Room - A room that contains a noise source or sources
Spectrum - The spectrum of a sound wave is a description of its resolution into components, each of
different frequency and usually different amplitude.
Tapping Machine - A device used in rating different floor constructions against impacts. It produces a
series of impacts on the floor under test, 10 times per second.
Nutrient Farm PUD December 2020
Sound Modeling Report 15
Tone - A sound with a distinct pitch
Transmission Loss (TL) - A property of a material or structure describing its ability to reduce the
transmission of sound at a particular frequency from one space to another. The higher the TL value
the more effective the material or structure is in reducing sound between two spaces. It is measured in
decibels.
Weighted Decibel Scale - The human ear is more sensitive to some sound frequencies than others. It
is therefore common practice to apply a filter to measured sound levels to approximate the frequency
sensitivity of the human ear. One such filter is called the A-weighted decibel scale which emphasizes
sounds between 1,000 and 5,000 Hertz by discounting the frequencies outside of this range. As the
human ear is less sensitive to low frequency noise, the A-weighted decibel scale begins to increasingly
discount noise below 500 Hertz.
Measurements conducted utilizing the A-weighted decibel scale are denoted with an “(A)” or “A” after
the decibel abbreviation (dB(A) or dBA). The A-weighted scale is nearly universally used when
assessing noise impact on humans.
High level low frequency noise can propagate large distances from its source. Although not always
audible, high levels of low frequency noise can induce vibrations in objects or structures which could
become evident in ways that might be annoying to humans (e.g., rattling of windows). The C-
weighted decibel scale, which was developed to estimate human ear sensitivity to high noise levels, is
a flatter filter that does not discount low frequency noise as much as the A-weighted decibel scale. As
a result, a C-weighted decibel measurement could be significantly higher than an A-weighted decibel
measurement if the noise being measured contains a heavy low frequency content.
Measurements conducted utilizing the C-weighted decibel scale are denoted with an “(C)” or “C” after
the decibel abbreviation (dB(C) or dBC). C-weighted noise level limits are sometimes included in noise
regulations as a way to address low frequency environmental noise issues.
White Noise - Noise that has approximately equal intensities at all frequencies.
Windscreen - A porous covering for a microphone, designed to reduce the noise generated by the
passage of wind over the microphone.