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HomeMy WebLinkAboutTab 14 5005 1044 Route 28 Environmental Sound AssessmentEnvironmental SoundAssessmentWireless Communications FacilitySite MA-51041044 MA Route 28South Yurmouth, Mussuchusetts 02 664Revised - December 20,2022Prepared For:BlueSWTowers III, LLCBlue Sky Towers III' LLC352Park Street, Suite 106N. Reading, MA 01864Prepared By:Modeling Specialties30 Maple RoadWestford, MA 01886ModelingSpecialties ENVIRO, SOI]ND ASSN,SSMENTBlue Sky Towers III,LLC, T-Mobile and AT&T propose to build and operate a WirelessTelecommunications Facility in South Yarmouth, Massachusetts to support personalwireless communication in the area. The proposed installation will include antennasmounted on a new 115-foot church tower. Supporting electronic equipment will be ina fenced compound at the foot of the tower. T-Mobile and AT&T are already planningto be anchor tenants for the facility, which will also be made available for co- locators.This report addresses the existing sound levels in the area, sources of sound expectedat this installation and an evaluation ofits potential to affect the neighboring land uses.While only two wireless tenants are currently committed to the proposed facility, itis designed to supporl up to four commercial wireless catriers and their equipment.The equipment configuration and siting were designed specifically to minimizeenvironmental effects.What has Changed since the Previous Study?The mounting structure for the proposed antennas has changed along with its overallheight. The propane tanks have moved and the area of the compound has decreased. Asnoted in the study, the antennas and infrastructure have no potential of emitting sound.The only sources of significant sound are the equipment cabinets and generators. Theirlocations and configurations are the same as previously reported. The report's graphicsand text have been updated to reflect the stated changes. The modeling study wasupdated to the new layout, but the results are identical to the previous iteration oftheSound Study. Tabular and graphical summaries of the results are provided.Overview of Project and Site VicinityThe project is located on the site of a Catholic Church in South Yarmouth, MA. Theexisting building is relatively small and surrounded by a large parking area. The terrainis reasonably flat so most receivers have direct line-of-sight to the potential sounds fromthe facility equipment compound. There is an existing deciduous forest on the southwestcomer of the lot, which was defoliate at the time of the field survey. For these reasons,the site will be conservatively modeled without any shielding benefit of terrain or forest.Daytime and nighttime field measurements were made to survey existing conditions.The equipment sound was estimated using vendor data and measurements made atsimilar installations. The comesponding levels expected at the nearby sensitive locationswere estimated using noise modeling techniques prescribed in acoustical literature.Blue Sky Towers II plans provided the necessary information to support the evaluationof project sounds. This study is based on the plans issued by the ProTena Design Groupdated November 28,2022. This conservative study is based on the highest sound levelsthat the equipment is expected to make even though it makes that sound only a smallfraction of the time. Figure t has a backdrop of a Google aerial image and is annotatedto show the proposed site, surounding area and nearby receptor locations with theirorientations and distances to the nearest proposed equipment.IBlue Sky ktwers lll, LLC / S. YarmouthSound Assessment O Measurement L.ocation Q ModelingRecepor SCALEN TEET - Base from Google 1000 Figure 1: Project Area Showing the Proposed Equipment Compound and Nearest Receptors 2Blue Sky Towers III, LLC / S. Yarmouth SoundAssessment Discussion of General Noise Analysis MethodsThere are a number of ways in which sound (noise) levels are measured and quantified.All of them use the logarithmic decibel (dB) scale. Following is a brief introduction tothe noise measurement terminology used in this assessment.Noise MetricsThe Sound Level Meter used to measure noise is a standardized instrument.l It contains"weighting networks" to adjust the frequency response of the instrument to approximatethat of the human ear under various circurnstances. One of these is the A-weightingnetwork. A-weighted sound levels emphasize the middle frequency sounds and de-emphasize lower and higher frequency sounds; they are reported in decibels designatedas "dBA." A11 broadband levels represented in this study are weighted using the A-weighting scale. Figure 2 illustrates typical sound levels produced by sources that arefamiliar to most people.The sounds in our environment usually vary with time, so they cannot always bedescribed with a single nurnber. Two methods are used for describing variable sounds.These are exceedance levels and equivalent level. Both are derived from a large numberof moment-to-moment A-weighted sound level measurements. Exceedance levels aredesignated Ln, where "n" can have any value from 0 to 1 00 percent. For example:i Lso is the sound level in dBA exceeded 90 percent of the time during themeasurement period. The Lqo is close to the lowest sound level observed. It isessentially the same as the residual sound level, which is the sound level observedwhen there are no loud, transient noises.o Lso is the median sound level: the sound level in dBA exceeded 50 percent of thetime during the measurement period.I Lro is the sound level in dBA exceeded only 10 percent of the time. It is close to themaximum level observed during the measurement period. The Lro is sometimescalled the intrusive sound level because it is caused by occasional louder noises likethose from passing motor vehicles.By using exceedance levels, it is possible to separate prevailing, steady sounds (Lqo)from occasional, louder sounds (Lro) in the environment.American National Standard Specificationfor Sound Level Meters, ANSI S1.4-1983, published by the StandaldsSecretariat of the Acoustical Society of America, NY.3Blue Sky Towers lll, LLC / S. YarmouthSound Assessment Common lndoor SoundsRock BandFood BlcndcrCarbagc DisposalVacuum CleanerTV/Radio ListeningNormal ConversationGommon Outdoor SoundsChain Sawlnsidc NY Subway TrainTruck at 100 ft.Gas Larvn Mower at 100 ft.Auto at 50 ft. (40 mph)Ilcavily Travcllcd Ilighway at 1000 ft.dBADishrvasher itt Ncxt RooutModcratc Rainfall on FolingcBird Calls at 100 ft.Snrall Brook aJ 25 ft,Refi'igerator'LibraryBedroom nt NightRural Community (no nearhy sounds)Threshold of Hearing (lahorntory)Figure 2: Typical Sound Levels from Everyday Experience11010090807o60504030201004Blue Slq Towers III, LLC / S. YarmouthSound Assessment 2The equivalent level is the level of a hypothetical steady sound that has the same energyas the actual fluctuating sound observed. The equivalent level is designated L.o, and isalso A-weighted. The equivalent level is strongly influenced by occasional loud,intrusive noises. When a steady sound is observed, all of the Ln and Leq are equal.In the design of noise control treatments, it is essential to know something about thefrequency spectrum of the sound of interest. Noise control treatments do not functionlike the human ear, so simple A-weighted levels are not useful for noise-control designor the identification of tones. The spectra of sounds are usually stated in terms of octaveband sound pressure levels in dB, with the octave frequency bands being thoseestablished by standard.z The sounds at the proposed site were evaluated with respectto the octave band sound pressure levels, as well as the A-weighted equivalent soundlevel. Only the A-weighted values are presented here since they represent the moreeasily recognized sound scale that is relevant to the Town and regional standards.Noise Regulations and CriteriaSound compliance is judged on two bases: the extent to which governmental regulationsor guidelines are met, and the extent to which it is estimated that the community isprotected from the excessive sound levels. The govemmental regulations that may beapplicable to sound produced by activities at the project site are summarized below.Federal. Occupational noise exposure standards: 29 CFR 1910.95. This regulation restrictsthe noise exposure of employees at the workplace as referred to in OSHArequirements. Workers will not routinely attend this facility. Furthermore, thefacility will ernit only occasional sounds of modest levels, as demonstrated by thisstudy.State. In Massachusetts, noise is regulated as an air pollutant. 3 1 0 CMR $7' 10 Uqualitatively prohibits "unnecessaly emissions from [a] source of sound that maycause noise". This is interpreted quantitatively by MDEP's Fonn BWP AQ SFP3and their DAQC Policy 90-001. The MDEP's Noise Policy states that a newnoise intrusion may not increase the broadband sound level by more than 10 dBAover the pre-existing Lqo ambient level. Tonal sounds, defined as any octave bandlevel that exceeds the levels in adjacent octavebands by 3 dB ormore, are alsoprohibited. The MDEP usually defers to applicable quantitative local ordinanceswhen available.American National Standard Specificationfor Octave, Half-octave and Third-octave Band Filter Sets, ANSIsl.l 1-1966(R197s).5Blue Sky Towers III, LLC / S. YarmouthSound Assessment Locsl. The Town of Yarmouth Zoning Ordinance (Chapter 104. Noise) providesqualitative limits on sounds produced between 11:00 pm and 7:00 am'Regional Wireless Ordinances also provide quantitative sound requirements of theequipment at this facility shown in the excerpt below:408.7.13.3 Ground-mounted equipment for Personal Wireless Service Facilities shall not,during normal operation, generate noise in excess of 5o db (non-continuous) at theproperty line.This analysis presents sound levels at the property line as specified by the ordinance,but also includes receptors representing other sensitive community locations.Existing Community Sound LevelsA site survey and noise measurement study were conducted on December 18, 2018 tomeasure the existing sound levels at and around the site. Additional measurements weremade on September 14, 2020 to update the dataset. The measured levels includedoccasional intrusive sound from traffrc, commercial activities, birds and small aircraft.The area around the church is paved for access and parking. The parking lots aresurrounded by deciduous forest, which was defoliate at the time of the 2018 survey andfoliate in 2020. In both cases, the nighttime surveys were conducted during the quiethours of the night on the same day as dalime conditions. The routine operation of thegenerators is never expected at night, but the nighttime sound levels were used as areference for the character ofthe existing sound and the routine facility operation.Me as ur ement Metho dol o glSince sound impacts are greatest when existing sound levels are lowest, this study wasdesigned to measure community sound levels under conditions typical of "quiet periods"for the area. This study uses methodology to support a MDEP type study (increase inambient) and also supports the property line analysis. The MDEP uses the backgroundmetric (Lso), which statistically excludes all non-steady sources. The Lqo metric givesthe lowest 10 percent of the many samples gathered during a 20-minute measurementtaken in the project area. Meteorological conditions during the surveys were all withinthe ANSI required conditions to conduct sound measwements. This includesrepresentative seasonal temperatures, calm or light winds and no precipitation (or waterstanding on roadways). A11 meteorological conditions were noted from fieldobservations, but were also compared to the reports at Barnstable Municipal Airport,MA (KHYA). It is typical for airport winds to be higher than measured in thecommunity because they are measured at elevated locations in widely open areas.Measurements were made within the open paved area at the approximate setback of theneighboring residences and equipment compound. Based on spot observations in thearea, the levels represent both the site and the nearby community locations. All6Blue Slcy Towers III, LLC / S. YarmouthSound Assessment measurements were attended and made with a Rion NA-28 sound level meter. Themeter meets the requirements of ANSI Sl.4 Type I - Precision specification for soundlevel meters. The meter was mounted at approximately 5 feet above the ground. Themicrophone was fitted with factory recommended foam windscreen. The meter wasused to sample the environmental sound and to process the sound into various statisticalmetrics for use in this analysis. The meter is equipped with real time octave band filterset, which allowed it to process sound levels into 1/3 octave bands. While frequencyspecific data were collected, the survey results are reported only in combined A-weighted levels for simplicity and consistency with the criteria. The filters comply withthe requirements of the ANSI S 1 - I I for octave band filter sets. The meter was calibratedin the field using a Larsen Davis Cal-200 sound level calibrator before and after themeasurement sessions. The results of the field calibration indicated that the meter didnot drift during the study.The results of the surveys allow both quantitative and qualitative analyses of theacoustical environment surrounding the proposed equipment. The characterization ofambient sound levels reflects the variations caused by volume of traffrc on localroadways, occasional aitctaft passes and community sounds.Meusurement ResultsThe measured background levels in the project area ranged from 50 dBA during thedaytime to 37 dBA in the quietest hours of the night. The corresponding Leq valuesrange from 59 dBA to 48 dBA. The measurement results are summarized in Table LTable 1: Measured BackgroundSound Levels in the Proiect AreaPeriodTimeLeq dBALso dBA2018 Daytime8:55 AM59502018 Nighttime4:30 AM48372020Daytime7:35 AM58482020 Nighttime4:32 ANI5146Sounds from the Proposed InstallationThe project's current plans include T-Mobile and AT&T equipment and provide someengineering detail for their proposed equipment. The tower is expected to attract othercarriers, but each carrier designs their system based on the particular needs oftheirnetwork. For that reason, this study addresses the sound from only the equipmentproposed in the current plan. Cabling and piping for utilities will be underground.The tower, infrastructure and most of the equipment planned for this facility has nopotential of emitting sound. Only two types of sources are planned for this facility asquantified in this study. The antennas will be supported by cabinet mounted radioelectronics and generators at the foot of the tower.7Blue Sl+y Towers III, LLC / S. YarmouthSound Assessment 0a o(, !0 (A o{ oa Fo Lll o oo p- FD o. +o rnX @ oa 4 0c-o b G l-,N N ao t--t..o h o s9 -l '--- r.v::I lx, ix t_la .-t i aaJOoq OC oo to zo ! Fz .,.,xs ':i= <t-t9loll:ol'l=] it *: I l___l t q 6 € Il* ao fo aJ 6' d Oo -o a -<m ol-.'-@ --+-go $Ef a 9L @ Tmm--t (^ o- s_ !hq h (\ ..-'-f t !I I ---T:..- : !-'--t i I t- I T-Mobile RF EqmtBehind ShroudAT&T RF EqmtBehind ShroudGround EqurpmenlWrlhin Fenced Conrpound6 ft Stockade Fence-\L \.. )l- './r'i lIrGraphic Scale in FeetELEVATIONFigure 4: Elevation Plan Showing the Verlical Character of the Church Tower and Compound1ll1+ilrililjjil1illillil#Nllllllillilllilllllll9Blue Sky Towers III, LLC / S. YarmouthSound Assessment Routine Sound EmissionsThe only routine sound emissions planned from the proposedT-Mobile equipment is from the electronics cabinet fans. Thesmall fans in the cabinet draws outside air through the unit. Ithas a smooth broadband character that produces about 50 dBAat 3 feet from the unit. The field image to the right has an insetshowing that the rear or sides have no louvered openings.Therefore, the T-Mobile cabinets only emit sound in theforward direction. Three cabinets are planned, but only onefaces the sensitive west direction. The modeling is based on asingle unit emitting in every direction.In a similar way, the AT&T Walk-In-Cabinet (WIC) is usuallycooled by ambient air. The WIC cooling fans increase in speedas the need for cooling increases. Their sound at full speedexceeds the modest sound from the door mounted cooler. Thecooler engages before the full speed fans are needed, usuallyabout 90o F. The highest sound is expected from the WIC isabout 50 dBA at 23 ft. The fans on the WIC will operatecontinuously, so there will be no variation from moment tomoment or cycling from equipment startup. Fans are mounted onthe inside of the cabinets (which will always remain closed). Inthis way, the cabinet configuration is designed for minimal effecton the surrounding area. The sketch to the right shows the cooleron the front of the AT&T WIC. For most sites, the sound fromthe cabinets is a non-issue because they are such modest sources.They are modeled here as the highest expected nighttime soundemission.Door MountedAir CoolerAT&T's WICScale FEET012 1t=E-N o n- Ro utin e S o u nd EmisslbnsThe installation will include two generators installed inside sound reducingenclosures. T-Mobile proposes a propane-fired 36 kW Kohler 36CCL Seriesgenerator. The system is rated at only 57 dBA at23 feet during theequipment tests. This low sound level is far below typical sound fromgenerators of a comparable output.AT&T proposes a propane-fired Polar 15 kW generator. As a DC unit, itprovides support in a very different way than the more familiar ACgenerators. A DC generator will only operate to the level demanded bythe load. It has a capacity to produce 15 kW which may be demanded inan emergency. But it will have no load during routine tests so the unitwill essentially operate at a high idle during the test. The full load soundrating is 59 dBA, but the sound level associated with the generator test isabout 56 dBA at 23 feet from the unit. Since the emergency operation is considered an upset condition, thetest condition is modeled for this study.Blue Sky Towers III, LLC / S. Yarmoutht0Sound Assessment Project Sound Level Mitigation FeaturesThe proposed generators will be monitored remotely and tested regularly to assure thesafe and effective operation of the equipment during a loss of utility power. Variousdesign features were implemented at this facility to reduce the potential sound. Theequipment location is as far as practical from sensitive locations while meeting the hostrequirements. The primary source of facility sound is the infrequent operation of thegenerators. Again, the generators were placed as far as practical from the sensitivedirections. A supplementary 6-foot sound barrier is planned to further shield thereceivers from generator sound. The carriers selected generator models that are highlymitigated for sound. For example, a typical residential generator in the 4,000-watt rangecommon in most communities operates at about 70 dBA at23 feet. Both of the plannedunits are far higher capacity, yet each is expected to operate below 60 dBA at thereference distance. Worst-case modeling of the facility assumes simultaneous operationof the two generators (which is unlikely). Together, they are expected to operate at alevel lower than the existing measured ambient at the property line. The Cape CodCommission recommendation that LP fuel be used further quiets the operation. Gaseousfuel is quieter, but also lowers the equipment profile by eliminating the belly tank. Thisincreases the benefit ofthe proposed sound shields.Modeling DetailsNoise prediction modeling was performed using CADNA software under downwindweather conditions as assumed in the standard ISO 9613-2. Table 2 summarizes themodeling input parameters.Table 2:Modeling Input ParametersItemModeling Input and Desg.!p!!94_TerrainFlat Terrain assumedTemperature100cRelative Humiditv70%Weather Condition6.5 mph, directly from facility toGround Attenuation0.2. hard surface (0.5 : soft ground, 0.0: pure reflection)Atmospheric InversionCONCAWE - Catesory F**# ofSound Reflections2Receptor Heisht1.5 meter above ground level* Propagation calculations incorporate the adverse effects ofcertain atmospheric andmeteorological conditions on sound propagation, such as gentle breeze o/ l to 5 m/s(lSO 1996-2: 1987)from source to receiver.** Category F represents a stable atmosphere that promotes noise propagation.Sound Level Modeling ResultsSince all the equipment with the potential to emit sound will be at ground level, thesound will be shielded in some directions by other equipment and surrounding forest.The sound barriers are also included in the modeling, but the conservative study didnot take any credit for attenuation by the forest. The worst-case equipment levels willbe 45 dBA or less at the property line. This is lower than the daytime ambient level of48 dBA. Sounds that are less than the arnbient level rnay be heard but are not noticedin a typical community. For this reason, the daytime tests are expected to beBlue Sky T'owers III, LLC / S. YarmouthilSound Assessment compatible with existing daytime traffic and community sources and not be noticed atthe residences beyond the property line. Tables 3 and 4 provide a summary of themodeling results. A graphical summary of the results is also provided in Figure 5.Table 3: Summarv of Modeling Results of Property Line Sound LevelsReceptorLocationDist(Ft)Ambient LevelDav/Nieht (dBA)HVAC Only(dBA)With Generators(dBA)Comply?P/L SW12848/373945YesTable 4Summary of Modeling at the other Area SensitiveConclusionsReceptorLocationDist(Ft)Ambient LevelDay (dBA)CombinedSound (dBA)Increase(dB)Res SWI2084838+1Res SW22804836+0Res SW33364837+0Res West2104840+1Bank, East2504844+1The potential sound of the proposed Wireless Telecommunications Facility wasevaluated using measured fie1d data and numerical modeling methods. Ambient soundlevels were established by field measurernents using equipment that is standardized tothe current ANSI standards. Equipment operating sound levels were quantified usingvendor estimates confirmed by representative fie1d measurement at other installations.Much of the time, the proposed facility will produce no significant sound. The cabinetfans will operate continuously at a very low level of sound that will be well below theambient level, so are never expected to be noticed in the community.Infrequently, for one half-hour per week, the proposed facility sounds will include thedaytime testing of the emergency generators. The combined sound from the T-Mobileand AT&T generators is expected to be the worst-case daytime sound level. During asimultaneous test, the facility sound is expected to be 45 dBA or less at the property line.The analysis shows that the facility sources will usually emit no sound that would benoticed outside the equipment compound. The cabinet fans will operate as needed toprotect the cabinet electronics without affecting the community. Under high ambienttemperatures, usually above 85" F, the cabinet heat load may trigger elevated fan poweror the supplementary cooling system on the WIC. Another infrequent event is theroutine test of the facility generators. The study is based on the facility's worst-casesound, which is a rare combination of both the high fans and generators. The results ofthe study indicate the worst-case facility equipment sound will remain withincompliance goal of 50 dBA at the properly line. It also meets the MDEP standard withonly a minor increase in sound at the receptors. In this way, the study indicates thefacility is expected to rneet applicable noise standards under all operational conditions.Blue Sky Towers lll, LLC / S. Yarmoutht2Sound Assessment 6A O mor,r*nrr* Laetion O uooetinERecegor SCALEN TEET Base #!GA 476A 38GA Figure 5: Graphical Summary of the Facility Sound Modeling with Cabinets plus Generators Blue Sky Towers III, LLC / S. Yarmouth t3 SoundAssessment