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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.