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Alameda County Community Development Agency Impact Analysis

Noise

APWRA Repowering Draft PEIR 3.11‐1

June 2014ICF 00323.08

3.11 Noise Thissectiondescribestheenvironmentalsettingandregulatorysettingfornoise.Italsodescribesthenoiseimpacts,ifany,thatwouldresultfromimplementationoftheprogramandtwoindividualprojects.Whereapplicable,mitigationmeasuresaredescribedthatwouldreducetheseimpacts.

3.11.1 Existing Conditions

Background Information on Noise

NoiseforthepurposesofenvironmentalanalysisunderCEQAiscommonlydefinedassoundthatannoysordisturbspeopleandpotentiallycausesanadversepsychologicalorphysiologicaleffectonhumanhealth.Becausenoiseisanenvironmentalpollutantthatcaninterferewithhumanactivities,evaluationofnoiseisnecessarywhenconsideringtheenvironmentalimpactsofaproposedproject.

Soundismechanicalenergy(vibration)transmittedbypressurewavesoveramediumsuchasairorwater.Soundischaracterizedbyvariousparametersthatincludetherateofoscillationofsoundwaves(frequency),thespeedofpropagation,andthepressurelevelorenergycontent(amplitude).Inparticular,thesoundpressurelevelisthemostcommondescriptorusedtocharacterizetheloudnessofanambient(existing)soundlevel.Althoughthedecibel(dB)scale,alogarithmicscale,isusedtoquantifysoundintensity,itdoesnotaccuratelydescribehowsoundintensityisperceivedbyhumanhearing.Thehumanearisnotequallysensitivetoallfrequenciesintheentirespectrum,sonoisemeasurementsareweightedmoreheavilyforfrequenciestowhichhumansaresensitiveinaprocesscalledA‐weighting,writtenasdBAandreferredtoasA‐weighteddecibels.Table3.11‐1definessoundmeasurementsandotherterminologyusedinthischapter,andTable3.11‐2summarizestypicalA‐weightedsoundlevelsfordifferentnoisesources.

Ingeneral,humansoundperceptionissuchthatachangeinsoundlevelof1dBcannottypicallybeperceivedbythehumanear,achangeof3dBisbarelynoticeable,achangeof5dBisclearlynoticeable,andachangeof10dBisperceivedasdoublingorhalvingthesoundlevel.

Differenttypesofmeasurementsareusedtocharacterizethetime‐varyingnatureofsound.Thesemeasurementsincludetheequivalentsoundlevel(Leq),theminimumandmaximumsoundlevels(LminandLmax),percentile‐exceededsoundlevels(suchasL10,L20),theday‐nightsoundlevel(Ldn),andthecommunitynoiseequivalentlevel(CNEL).LdnandCNELvaluesdifferbylessthan1dB.Asamatterofpractice,LdnandCNELvaluesareconsideredtobeequivalentandaretreatedassuchinthisassessment.

Forapointsourcesuchasastationarycompressororconstructionequipment,soundattenuatesbasedongeometryatrateof6dBperdoublingofdistance.Foralinesourcesuchasfreeflowingtrafficonafreeway,soundattenuatesatarateof3dBperdoublingofdistance(CaliforniaDepartmentofTransportation2009).Atmosphericconditionsincludingwind,temperaturegradients,andhumiditycanchangehowsoundpropagatesoverdistanceandcanaffectthelevelofsoundreceivedatagivenlocation.Thedegreetowhichthegroundsurfaceabsorbsacousticalenergyalsoaffectssoundpropagation.Soundthattravelsoveranacousticallyabsorptivesurfacesuchasgrassattenuatesatagreaterratethansoundthattravelsoverahardsurfacesuchaspavement.Theincreasedattenuationistypicallyintherangeof1to2dBperdoublingofdistance.


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Barrierssuchasbuildingsandtopographythatblockthelineofsightbetweenasourceandreceiveralsoincreasetheattenuationofsoundoverdistance.

Table 3.11‐1. Definition of Sound Measurements

SoundMeasurements Definition

Decibel(dB) Aunitlessmeasureofsoundonalogarithmicscale,whichindicatesthesquaredratioofsoundpressureamplitudetoareferencesoundpressureamplitude.Thereferencepressureis20micro‐pascals.

A‐WeightedDecibel(dBA) Anoverallfrequency‐weightedsoundlevelindecibelsthatapproximatesthefrequencyresponseofthehumanear.

C‐WeightedDecibel(dBC) ThesoundpressurelevelindecibelsasmeasuredusingtheC‐weightingfilternetwork.TheC‐weightingisveryclosetoanunweightedor“flat”response.C‐weightingisonlyusedinspecialcaseswhenlow‐frequencynoiseisofparticularimportance.AcomparisonofmeasuredAandCweightedlevelgivesanindicationoflowfrequencycontent.

MaximumSoundLevel(Lmax) Themaximumsoundlevelmeasuredduringthemeasurementperiod.

MinimumSoundLevel(Lmin) Theminimumsoundlevelmeasuredduringthemeasurementperiod.

EquivalentSoundLevel(Leq) Leqrepresentsanaverageofthesoundenergyoccurringoveraspecifiedperiod.Ineffect,Leqisthesteady‐statesoundlevelcontainingthesameacousticalenergyasthetime‐varyingsoundthatactuallyoccursduringthesameperiod.The1‐hourAweightedequivalentsoundlevel(Leq[h])istheenergyaverageofA‐weightedsoundlevelsoccurringduringa1‐hourperiod.

Percentile‐ExceededSoundLevel(Lxx)

Thesoundlevelexceeded“xx”percentofaspecifictimeperiod.L10isthesoundlevelexceeded10percentofthetime.L90isthesoundlevelexceeded90percentofthetime.L90isoftenconsideredtoberepresentativeofthebackgroundnoiselevelinagivenarea.

Day‐NightLevel(Ldn) TheenergyaverageoftheA‐weightedsoundlevelsoccurringduringa24‐hourperiod,with10dBaddedtotheA‐weightedsoundlevelsoccurringduringtheperiodfrom10:00p.m.to7:00a.m.

CommunityNoiseEquivalentLevel(CNEL)

TheenergyaverageoftheA‐weightedsoundlevelsoccurringduringa24‐hourperiodwith5dBaddedtotheA‐weightedsoundlevelsoccurringduringtheperiodfrom7:00p.m.to10:00p.m.and10dBaddedtotheA‐weightedsoundlevelsoccurringduringtheperiodfrom10:00p.m.to7:00a.m.

PeakParticleVelocity(PeakVelocityorPPV)

Ameasurementofgroundvibrationdefinedasthemaximumspeed(measuredininchespersecond)atwhichaparticleinthegroundismovingrelativetoitsinactivestate.PPVisusuallyexpressedininches/sec.

Frequency:Hertz(Hz) Thenumberofcompletepressurefluctuationspersecondaboveandbelowatmosphericpressure.


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Table 3.11‐2. Typical A‐weighted Sound Levels

CommonOutdoorActivitiesNoiseLevel(dBA) CommonIndoorActivities

—110— Rockband

Jetflyoverat1,000feet

—100—

Gaslawnmowerat3feet

—90—

Dieseltruckat50feetat50mph Foodblenderat3feet

—80— Garbagedisposalat3feet

Noisyurbanarea,daytime

Gaslawnmower,100feet —70— Vacuumcleanerat10feet

Commercialarea Normalspeechat3feet

Heavytrafficat300feet —60—

Largebusinessoffice

Quieturbandaytime —50— Dishwasherinnextroom

Quieturbannighttime —40— Theater,largeconferenceroom(background)

Quietsuburbannighttime

—30— Library

Quietruralnighttime Bedroomatnight,concerthall(background)

—20—

Broadcast/recordingstudio

—10—

—0—

Source:CaliforniaDepartmentofTransportation2009.

Other Factors Related to Wind Turbines

Operatingwindturbinescangeneratetwotypesofsound:mechanicalsoundfromcomponentssuchasgearboxes,generators,yawdrives,andcoolingfans;andaerodynamicsoundfromtheflowofairoverandpasttherotorblades.Modernwindturbinedesignhasgreatlyreducedmechanicalsound,whichisgenerallyunnoticeableincomparisonwiththeaerodynamicsound,whichisoftendescribedasa“swishing”or“whooshing”sound.TheInternationalStandardIEC61400‐11forwindturbinenoiseassessmentprovidesarequirementforevaluatingtonality.Tonesarethendividedintocategoriesofprominenttone,audibletone,ornotone.(Illingworth&Rodkin2006.)

Comparedwithother,primarilyolderwindturbines,themodernwindturbinesthatwouldbeinstalledthroughtherepoweringprogramhaveseveralcharacteristicsthatreduceaerodynamicsoundlevels.Themodernturbinestypicallyareupwindturbines,meaningeachturbinefacesintothewind,sothewindencounterstherotorbladesbeforethetowerandnacelle,makingforquieteroperationsthanadownwindturbine.Additionally,themodernturbineshaverelativelylowrotationalspeedsandpitchcontrolontherotors,bothofwhichreducesoundlevels.


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Windturbinesproduceabroadbandsound(i.e.,thesoundoccursoverawiderangeoffrequencies,includinglowfrequencies).Low‐frequencysoundsareintherangeof20–100Hz,andinfrasonicsound(orinfrasound)islow‐frequencysoundoflessthan20hertz.Comparedwithhigherfrequencysound,low‐frequencysoundpropagatesoverlongerdistances,istransmittedthroughbuildingsmorereadily,andcanexcitestructuralvibrations(e.g.,rattlingwindowsordoors).Thethresholdofperception,indecibels,alsoincreasesasthefrequencydecreases.Forexample,inthefrequencyrangewherehumanshearbest(inthelowkilohertz),thethresholdofhearingisatabout0dB,butatafrequencyofonly10Hz,thethresholdofhearingisatabout100dB(Rogersetal.2006a).

Olderwindturbines—particularlythoseinwhichthebladeswereonthedownwindsideofthetower—producedmorelow‐frequencysoundbecausetheirtowersblockedwindflow,causingthebladestopassthroughmoreturbulentair.Modern,upwindturbinesproduceabroadbandsoundthatincludeslow‐frequencysounds,butnotatsignificantlevels.Aprimarycauseforlow‐frequencysoundsinmodernturbinesisthebladepassingthroughthechangeinairflowatthefrontofthetower,andthiscanbeaggravatedbyunusuallyturbulentwindconditions.Thiseffectisgenerallyreferredtoasbladeamplitudemodulationbecausetheaerodynamicnoisegeneratedbytheblades(the“swishing”sound)ismodulatedastheturbinebladespassthroughunevenairvelocities.Theunevenairthatcausesthiseffectmaybeduetointeractionofotherturbines,excessivewindshear,ortopography(Bowdler2008).

TheUniversityofMassachusettsatAmherstreportedonnoisemeasurementsmadeatfourdifferentwindturbinesrangingfrom450kilowattsto2megawatts(Rogersetal.2006b).Theresultsindicatedthatatdistancesofnomorethan118meters(387feet)fromtheturbines,allinfrasoundlevelswerebelowhumanperceptionlevels.Thereportfurtherstatesthatthereis“noreliableevidencethatinfrasoundbelowthehearingthresholdproducesphysiologicalorpsychologicaleffects.”Thislackofeffectsatlevelsbelowthehearingthresholdwassupportedbyascientificadvisorypanelcomposedofmedicaldoctors,audiologists,andacousticalprofessionalsestablishedbytheAmericanandCanadianWindEnergyAssociationstoreviewwindturbinesoundandhealtheffects(Colbyetal.2009).ItwasalsosupportedbyCanadianandAustraliangovernmentreviewsofavailablescientificliterature(AustraliaNationalHealthandMedicalResearchCouncil2010;OntarioChiefMedicalOfficerofHealth2010).

Additionalrecentstudiesconductedona2.3MWSiemensSWT‐2.3‐93turbine(O’Nealetal.2010)areausefulpointofreferencewiththeregardtolowfrequencynoisegeneratedbyamodernwindturbinegenerator.ThesestudiesconcludedthattheSiemensSWT‐2.3‐93windturbineatmaximumnoiseatadistanceofabout305meters(1,000feet)fromthenearestresidencedoesnotposealowfrequencynoiseorinfrasoundproblem.Atthisdistancetheturbinesatisfiesthefollowingobjectives.

MeetsAmericanNationalStandardsInstitute/AmericanStandardsAssociation[ANSI/ASA]S12.2indoorlevelsforlowfrequencysoundforbedrooms,classrooms,andhospitals.

MeetsANSI/ASAS12.2indoorlevelsformoderatelyperceptiblevibrationsinlightweightwallsandceilings.

MeetsANSIS12.9Part4thresholdsforannoyanceandbeginningofrattles.

Producesnoaudibleinfrasoundcapableofdetectionbythemostsensitivelisteners.

Windgeneratessoundwhenitinteractswithstructuresandvegetationontheground.Theamountofsoundgeneratedcanvarywidelydependingprimarilyontheamountofvegetationinthearea


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andthespeedofthewind.Foragivenwindspeed,thesoundlevelinadesertwithnotreesorvegetationwillbedifferentthaninahighlyvegetatedarea.Whentreesareinfullleaf,windinthetreesrustlestheleavesandhighfrequencysoundisproduced(HooverandKeith2000).Theamountofsoundgenerateddependsonwindspeed,thedistancefromtheobservedpositiontothetreesorfoliage,andtheapproximatefrontalareaofthetreesorfoliageasseenfromtheobservedposition.Soundlevelsgeneratedbywindcanrangefromabout20dBAto60dBAforwindspeedsintherangeof2to20milesperhour(HooverandKeith2000).

Regulatory Setting

Federal

Federal,state,andlocalagenciesregulatedifferentaspectsofenvironmentalnoise.Generally,thefederalgovernmentsetsnoisestandardsfortransportation‐relatednoisesourcescloselylinkedtointerstatecommerce.Theseincludeaircraft,locomotives,andtrucks.Thestategovernmentsetsnoisestandardsfortransportationnoisesourcessuchasautomobiles,lighttrucks,andmotorcycles.Noisesourcesassociatedwithindustrial,commercial,andconstructionactivitiesaregenerallysubjecttolocalcontrolthroughnoiseordinancesandgeneralplanpolicies.Localgeneralplansidentifygeneralprinciplesintendedtoguideandinfluencedevelopmentplans.

State

Part2,Title24oftheCaliforniaCodeofRegulations“CaliforniaNoiseInsulationStandards”establishesminimumnoiseinsulationstandardstoprotectpersonswithinnewhotels,motels,dormitories,long‐termcarefacilities,apartmenthouses,anddwellingsotherthansingle‐familyresidences.Underthisregulation,interiornoiselevelsattributabletoexteriornoisesourcescannotexceed45Ldninanyhabitableroom.Wheresuchresidencesarelocatedinanenvironmentwhereexteriornoiseis60Ldnorgreater,anacousticalanalysisisrequiredtoensurethatinteriorlevelsdonotexceedthe45Ldninteriorstandard.

TheStateofCaliforniaGeneralPlanGuidelines(Governor’sOfficeofPlanningandResearch2003)identifiesguidelinesforthenoiseelementsoflocalgeneralplans,includingasoundlevel/landusecompatibilitychartthatcategorizes,bylanduse,outdoorLdnrangesinuptofourcategories(normallyacceptable,conditionallyacceptable,normallyunacceptable,andclearlyunacceptable).Formanylanduses,thechartshowsoverlappingLdnrangesfortwoormorecompatibilitycategories.

ThenoiseelementguidelinechartidentifiesthenormallyacceptablerangeofLdnvaluesforlow‐densityresidentialusesaslessthan60dBandtheconditionallyacceptablerangeas55–70dB.Thenormallyacceptablerangeforhigh‐densityresidentialusesisidentifiedasLdnvaluesoflessthan65dB,andtheconditionallyacceptablerangeisidentifiedas60–70dB.Foreducationalandmedicalfacilities,Ldnvaluesoflessthan70dBareconsiderednormallyacceptable,andLdnvaluesof60–70dBareconsideredconditionallyacceptable.Forofficeandcommerciallanduses,Ldnvaluesoflessthan70dBareconsiderednormallyacceptable,andLdnvaluesof67.5–77.5arecategorizedasconditionallyacceptable.Whennoiselevelsareintheconditionallyacceptablerangenewconstructionshouldbeundertakenonlyafteradetailedanalysisofthenoisereductionrequirementsismadeandneedednoiseinsulationrequirementsareincludedinthedesign.


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TheseoverlappingLdnrangesareintendedtoindicatethatlocalconditions(existingsoundlevelsandcommunityattitudestowarddominantsoundsources)shouldbeconsideredinevaluatinglandusecompatibilityatspecificlocations.

Local

General Plan Noise Element

TheAlamedaCountyGeneralPlanNoiseElement(AlamedaCounty1976)containsgoals,objectives,andimplementationprogramsfortheentirecountytoprovideitsresidentswithanenvironmentthatisfreefromexcessivenoiseandthatpromotescompatibilityoflanduseswithrespecttonoise.TheCountywideNoiseElementdoesnotexplicitlydefinetheacceptableoutdoornoiselevelforthebackyardsofsingle‐familyhomesorcommonoutdoorspacesofmulti‐familyhousingprojects,butitrecognizestheFederalEnvironmentalProtectionAgency(EPA)noiselevelstandardsforresidentiallanduses.ThesestandardsareanexteriorLdnof55dBAandaninteriorLdnof45dBA.(TheLdnmeasurement,whichalsoincludesa10dBweightingfornight‐timesound,isapproximatelyequaltotheCNELformostenvironmentalsettings.)TheNoiseElementalsoreferencesnoiseandlandusecompatibilitystandardsdevelopedbyanAssociationofBayAreaGovernments(ABAG)‐sponsoredstudy.

East County Area Plan

AlamedaCounty’sECAP(AlamedaCounty2000)containsthefollowinggoal,policiesandimplementationprogramsrelatedtocommunitynoiseandwindfarms.

Goal:TominimizeEastCountyresidents’andworkers’exposuretoexcessivenoise.

Policies

Policy170:TheCountyshallprotectnearbyexistingusesfrompotentialtraffic,noise,dust,visual,andotherimpactsgeneratedbytheconstructionandoperationofwindfarmfacilities.

Policy288:TheCountyshallendeavortomaintainacceptablenoiselevelsthroughoutEastCounty.

Policy289:TheCountyshalllimitorappropriatelymitigatenewnoisesensitivedevelopmentinareasexposedtoprojectednoiselevelsexceeding60dBbasedontheCaliforniaOfficeofNoiseControlLandUseCompatibilityGuidelines.

Policy290:TheCountyshallrequirenoisestudiesaspartofdevelopmentreviewforprojectslocatedinareasexposedtohighnoiselevelsandinareasadjacenttoexistingresidentialorothersensitivelanduses.Wherenoisestudiesshowthatnoiselevelsinareasofexistinghousingwillexceed“normallyacceptable”standards(asdefinedbytheCaliforniaOfficeofNoiseControlLandUseCompatibilityGuidelines),majordevelopmentprojectsshallcontributetheirpro‐ratedsharetothecostofnoisemitigationmeasuressuchasthosedescribedinProgram104.

ImplementationPrograms

Program74:TheCountyshallamendtheZoningOrdinancetoincorporatesitinganddesignstandardsforwindturbinestomitigatebiological,visual,noise,andotherimpactsgeneratedbywindfarmoperations.

Program104:TheCountyshallrequiretheuseofnoisereductiontechniques(suchasbuffers,buildingdesignmodifications,lotorientation,soundwalls,earthberms,landscaping,buildingsetbacks,andrealestatedisclosurenotices)tomitigatenoiseimpactsgeneratedbytransportation‐relatedandstationarysourcesasspecifiedintheCaliforniaOfficeofNoiseControlLandUseCompatibilityGuidelines.


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Noise Ordinance

AlamedaCounty’snoiseordinance(CountyGeneralCode,Chapter6.60)allowshighernoiseexposurelevelsforcommercialpropertiesthanforresidentialuses,schools,hospitals,churches,orlibraries.Thesestandardsaugmentthestate‐mandatedrequirementsoftheAlamedaCountyBuildingCode,whichestablishesstandardsforinteriornoiselevelsconsistentwiththenoiseinsulationstandardsintheCaliforniaStateBuildingCode.Table3.11‐3showsthenumberofcumulativeminutesthataparticularexternalnoiselevelispermitted,aswellasthemaximumnoiseallowedundertheAlamedaCountyGeneralCode.

Table 3.11‐3. Alameda County Exterior Noise Standards

CumulativeNumberofMinutesinAny1‐HourTimePeriodDaytime

Daytime(7a.m.to10p.m.)

Nighttime(10p.m.to7a.m.)

Residentialuses,schools,hospitals,churches,andlibraries

30 50dBA 45dBA

15 55dBA 50dBA

5 60dBA 55dBA

1 65dBA 60dBA

Maximum 70dBA 65dBA

Commercialuses

30 65dBA 60dBA

15 70dBA 65dBA

5 75dBA 70dBA

1 80dBA 75dBA

Maximum 85dBA 80dBA

Source:AlamedaCountyGeneralCode,Chapter6.60.

TheCountyZoningOrdinance(CountyGeneralCode,Chapter17)restrictsnoisefromcommercialactivitiesbyprohibitinganyusethatwouldgenerateanoiseorvibrationthatisdiscerniblewithoutinstrumentsbeyondthepropertyline.Thisperformancestandarddoesnotapplytotransportationactivitiesortemporaryconstructionwork.

Theprovisionsoftheordinancedonotapplytonoisesourcesassociatedwithconstruction,providedtheactivitiesdonottakeplacebefore7a.m.orafter7p.m.onanydayexceptSaturdayorSunday,orbefore8a.m.orafter5p.m.onSaturdayorSunday.

Conditional Use Permits

TheCounty’sCUPsforthecontinuedoperationofthewindfarmsafter2005,regulatedbyResolutionNumberR‐2005‐463,identifiedthefollowingspecificconditionregardingnoiselevels.

NoiseStandards:WindturbinesshallbeoperatedsoastonotexceedtheCounty’snoisestandardof55dBA(Ldn)or70dBC(Ldn)asmeasuredinbothcasesattheexteriorofanydwellingunit.IfthedwellingunitisonlandunderleasefromthePermittee,theapplicablestandardshallbe65dBA(Ldn)and70dBC(Ldn).

TheResolutionapprovingtheCUPsforwindfarmoperationsincludedafindingthatasalanduse,thewindenergyuse“isproperlyrelatedtootherlandusesandtransportationandservicefacilities


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inthevicinity,inthat…d)Althoughsomeresidentsmayobjecttothevisual,noise,orothereffectsoftheturbines,theCountyhasdeterminedthatthewindenergyprojectsareincompliancewiththeconditionsofapprovalandareanacceptableuseinthearea.”

Environmental Setting

Existing Land Uses

TheprogramareaistheAlamedaCountyportionoftheHCP‐revisedAPWRA.TheareaisdesignatedasLargeParcelAgricultureundertheCountyZoningOrdinanceandtheECAP.Generalagriculture,single‐familyresidences,grazing,andridingorhikingtrailsarealloweduses.ConditionalusesthatmaybeallowedthroughaCUPgrantedbytheCountyincludeoutdoorrecreationfacilities,transmissionfacilities,solidwastelandfills,andwindfarms.CUPsaredevelopedtobeconsistentwithgeneralplanpoliciesandotherlandusespermittedbytheCounty’sgeneralplan.

Program Area

Scatteredsingle‐familyruralresidencesarelocatedwithintheprogramboundary,includinghomesonbothverylargeparcels(morethan100acres)andcomparativelysmalllots(lessthan5acres).Single‐familyruralresidencesaremostlylocatedalongthewestandnortheastsidesoftheprogramarea.Withintheprogramboundary,severalresidencesalongAltamontPassRoadarelocatedascloseasabout600feetfromexistingturbines.TworesidencesalongFlynnRoadarelocatedabout800feetfromexistingturbines.SeveralresidenceslocatedalongDyerRoadarewithinabout1,100feetofexistingturbines.Nootherresidencesarelocatedwithin1,500feetoftheexistingturbinesintheprogramboundary.

Golden Hill Project Area

TworesidenceslocatedalongFlynnRoadareabout800feetfromthenearestturbineswithintheprojectboundary.Nootherresidencesarelocatedwithin1,500feetoftheexistingturbineswithintheprojectboundary.

Patterson Pass Project Area

TheclosestresidenceislocatedoffPattersonPassRoadabout2,200feetawayofthenearestturbineswithintheprojectboundary.

Existing Noise Conditions

TrafficonI‐580andwindturbineoperationsarethepredominantsourcesofnoiseintheprogramarea.Basedontrafficnoiseprojectionsfor2010,the60LdncontourfortraffictravelingonI‐580extendsabout1,800feetfromthefreeway(AlamedaCounty2000).

ThefollowingisasummaryofambientnoisemeasurementsconductedatsevenpositionsintheAltamontPassareaonMay17,2013(ICFInternational2013).Thesemeasurementsaregenerallyrepresentativeofnoiselevelsintheprogramareawherefirstgenerationwindturbinesarecurrentlyoperating.

PositionM1.AltamontPassRoad1.2mileswestofWestGrantLineRoad.300feetfromthenearestoperatingturbine.


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PositionM4.MountainHouseRoad.1.4milesnorthofWestGrantLineRoad.590feetfromthenearestoperatingturbine.

PositionM5.MountainHouseRoad.500feetnorthofWestGrantLineRoad.1,200feetfromthenearestoperatingturbine.

PositionM6.NorthMidwayRoad.0.9milessouthofI‐205.315feetfromthenearestoperatingturbine.

PositionM7.NorthMidwayRoad.0.6milessouthofI‐205.1,710feetfromthenearestoperatingturbine.

Table 3.11‐4. Summary of Noise Measurements in the APWRA

Position StartTime Duration Leq Lmax Lmin L10 L33 L50 L90

M1 10:17a.m. 5min 58.4 67.9 54.7 60.4 58.3 57.5 55.9

M2 10:38a.m. 5min 56.1 62.6 53.6 57.6 56.0 55.5 54.3

M3 10:38a.m. 5min 53.3 67.2 49.1 54.5 62.9 52.3 50.5

M4 11:24a.m. 5min 56.7 73.6 51.2 57.4 56.1 55.6 53.8

M5 11:43a.m. 5min 47.0 60.3 40.8 50.0 46.6 45.6 43.1

M6 12:18p.m. 5min 50.0 55.0 44.6 52.1 50.5 49.6 47.1

M7 12:36p.m. 5min 56.8 65.4 50.9 59.1 56.9 55.6 52.6

Althoughsoundfromexistingoperatingturbinesisaudibleadjacenttothem,thereisnodocumentedevidencethatnoisestandardsoftheexistingCUPs,asdefinedaboveintheConditionalUsePermitssection,havebeenexceeded.

3.11.2 Environmental Impacts

ThissectiondescribestheimpactanalysisrelatingtonoisefortheproposedprogramandtheGoldenHillsandPattersonPassprojects.Itdescribesthemethodsusedtodeterminetheimpactsoftheprogramandprojectsandliststhethresholdsusedtoconcludewhetheranimpactwouldbesignificant.Measurestomitigate(i.e.,avoid,minimize,rectify,reduce,eliminate,orcompensatefor)significantimpactsaccompanytheimpactdiscussion.

Methods for Analysis

Wind Turbine Noise

Theproposedprogramwouldreplacetheexistingturbines(first‐andsecond‐generationturbines)withfewerandlargercurrent‐generationturbines.Section2.3ofthisProgramEIR,WindTurbineTechnology,providesadescriptionandcomparisonofexistingandproposedturbines.Thespecifictypesorsounddataofcurrentgenerationwindturbinestobeusedintheprogramareaarenotknownand,therefore,thelevelsofnoiseproducedbytheinstallationofnewturbinescannotbe


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specificallydetermined.However,noiseproducedbycurrentgenerationturbinessuchastheREpowerMM92turbineandtheVestasV90turbineareknowntoproduceasoundlevelofabout44dBAat1,000feet(SolanoCounty2011).Continuousoperationovera24‐hourperiodwouldresultinabout50dBA(Ldn)at1,000feet.Atanygivenreceptorlocation,thereceivednoiselevelfromturbineoperationcouldbepotentiallyinfluencedbyseveralturbines,dependingonthegeometricrelationshipbetweentheturbinesandthereceptor.Table3.11‐5providesanindicationofpotentialreceivednoiselevelsexpressedindBA(Ldn)basedonthedistancetoareceiverandthenumberofturbinesinfluencingnoisereceivedatthereceptor.Thetablealsohighlights(usingshading)thedistanceswithinwhichtheCountystandardof55dBA(Ldn)wouldbeexceeded.Undertheassumptionthatupto10turbinescouldaffectthereceivednoiselevelatareceptor,theresultsinTable3.11‐5indicatethattheCountynoisestandardof55dBA(Ldn)couldbeexceededwithinabout1,750feetofareceptor.

Table 3.11‐5. Turbine Noise Level, dBA (Ldn), as a Function of Distance and Number of Turbines

Distance(feet)

NumberofTurbinesInfluencingtheReceivedNoiseLevel

1 2 3 4 5 7 10

500 56 59 61 62 63 64 66

550 55 58 60 61 62 63 65

750 52 55 57 58 59 60 62

1,000 50 53 55 56 57 58 60

1,150 49 52 54 55 56 57 59

1,250 48 51 53 54 55 56 58

1,400 47 50 52 53 54 55 57

1,500 46 49 51 52 53 54 56

1,750 45 48 50 51 52 53 55

2,000 44 47 49 50 51 52 54

2,500 42 45 47 48 49 50 52

3,000 40 43 45 46 47 48 50

Note:Basedonsimplegeometricattenuationof6dBperdoublingofdistance.

C‐weightedsoundlevelsprovideameasureoflowfrequencysoundenergyassociatedwithoperationofawindturbine.C‐weightedsoundlevelsfortheREpowerMM92turbineandtheVestasV90areabout10dBhigherthanA‐weightedsoundlevels.TheC‐weightedcountystandardforwindturbinesis70dBC(Ldn).

Table3.11‐6providesanindicationofpotentialreceivednoiselevelsexpressedindBC(Ldn)basedonthedistancetoareceiverandthenumberofturbinesinfluencingnoisereceivedatthereceptor.ThetablealsohighlightsdistanceswithinwhichtheCountystandardof70dBC(Ldn)wouldbeexceeded.Undertheassumptionthatupto10turbinescouldaffectthereceivednoiselevelatareceptor,theresultsinTable3.11‐6indicatethattheCountynoisestandardof70dBC(Ldn)couldbeexceededwithinabout1,000feetofareceptor.


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Table 3.11‐6. Turbine Noise Level, dBC (Ldn), as a Function of Distance and Number of Turbines

Distance(feet)

NumberofTurbinesInfluencingtheReceivedNoiseLevel

1 2 3 4 5 7 10

500 66 69 71 72 73 74 76

550 65 68 70 71 72 73 75

650 64 67 69 70 71 72 74

700 63 66 68 69 70 71 73

800 62 65 67 68 69 70 72

1,000 60 63 65 66 67 68 70

2,500 52 55 57 58 59 60 62

3,000 50 53 55 56 57 58 60

Construction Noise

Constructionactivitieswouldinvolvetheuseofheavyequipment.Toassessnoiseimpactsassociatedwiththeseactivities,constructionequipmentisidentifiedandnoiseisevaluatedusingmethodsrecommendedbytheFederalHighwayAdministration(FederalHighwayAdministration2006).NoiseimpactsassociatedwithincreasedconstructiontrafficisevaluatedusingmethodsfortheFHWAtrafficnoisemodel(TNM).

TheCountyusesanoisestandardforwindturbinesintheprogramareaof55dBA(Ldn)or70dBC(Ldn)atdwellingunits,withtheexceptionthatdwellingunitsonthesameparcelbeingleasedforwindfarmusemaybeexposedtoupto65dBA(Ldn).Noiseimpactsassociatedwiththeproposedprogramareevaluatedbasedonhowtheprojectwouldchangethedailynoiselevelassociatedwithwindturbineoperations.Thethresholdof5dBisusedbecauseitisgenerallyconsideredtobethelowestsoundlevelchangeclearlynoticeablebythehumanear.

Determination of Significance

InaccordancewithAppendixGoftheStateCEQAGuidelinesandtheCountyconditionsofapprovalfortheexistingturbineoperations,programAlternative1,programAlternative2,theGoldenHillsproject,orthePattersonPassprojectwouldbeconsideredtohaveasignificanteffectifitwouldresultinanyoftheconditionslistedbelow.

Exposureofresidencestonoisefromnewwindturbinesinexcessof55dBA(Ldn)wherewindturbinenoiseiscurrentlylessthan55dBA(Ldn).Inthesituationwherethedwellingunitisonthesameparcelbeingleasedforwindfarm,65dBA(Ldn)isusedasthethreshold.

Exposureofresidencestonoisefromnewwindturbinesinexcessof70dBC(Ldn)wherewindturbinenoiseiscurrentlylessthan70dBC(Ldn).

ExposureofresidencestoadailynoiseincreaseinLdnvalueofmorethan5dBfromtheadditionofnewwindturbineswheretheexistingnoiselevelisinexcessof55dBA(Ldn).Inthesituationwherethedwellingunitisonthesameparcelbeingleasedforwindfarm,65dBA(Ldn)isusedasthethreshold.


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ExposureofresidencestoequipmentnoiseassociatedwithconstructionactivitiesthatexceedAlamedaCountynoiseordinancestandards(Table3.11‐3)duringnonexempthours(7p.m.to7a.m.onweekdaysand5p.m.to8a.m.onSaturdayandSunday).

Impacts and Mitigation Measures

ImpactNOI‐1a‐1:Exposureofresidencestonoisefromnewwindturbines—programAlternative1:417MW(lessthansignificantwithmitigation)

ProgramAlternative1wouldreplacetheexistingturbines(first‐andsecond‐generationturbines)withfewerandlargercurrent‐generationturbines.Thelocationandtypesofturbinestobeusedwouldbedeterminedasprojectsareproposed.Section2.5.2discussesCountysitingrequirementsandtechnicalsitingrequirementsfortheproposedturbines;updatedsetbackrequirementsarepresentedinTable2‐2.

Asdiscussedabove,therearenodocumentedinstancesofwindturbinescausingexceedanceofnoisestandardsintheexistingCUPs.Inaddition,current‐generationturbinesexpectedtobeinstalledthroughtherepoweringprogramhaveseveralcharacteristicsthatreduceaerodynamicsoundlevels.Themodernturbinestypicallyareupwindturbines,meaningeachturbinefacesintothewind,sothewindencounterstherotorbladesbeforethetowerandnacelle,makingforquieteroperationsthanadownwindturbine.Additionally,themodernturbineshaverelativelylowrotationalspeedsandpitchcontrolontherotors,bothofwhichreducesoundlevels.

ThenoisepredictionresultsinTable3.11‐5,however,indicatethatresidenceslocatedwithinabout1,500feetofagroupofturbinescouldbeexposedtonoisethatexceeds55dBA(Ldn).ThenoisepredictionresultsinTable3.11‐6alsoindicatesthatresidenceslocatedwithinabout800feetofagroupofturbinescouldbeexposedtonoisethatexceeds70dBC(Ldn).BecauseofthepossibilitythatimplementationofprogramAlternative1couldresultindailyLdnvaluescausedbywindturbinestoincreasebymorethan5dBatlocationswherenoisecurrentlyexceeds55dBA(Ldn),exposeresidencestonoiseinexcessof55dBA(Ldn)wherenoiseiscurrentlylessthan55dBA(Ldn),orexposeresidencetonoiseinexcessof70dBC(Ldn)thisimpactisconsideredtobesignificant.ImplementationofMitigationMeasureNOI‐1wouldreducethisimpacttoaless‐than‐significantlevel.

MitigationMeasureNOI‐1:Performproject‐specificnoisestudiesandimplementmeasurestocomplywithCountynoisestandards

Theapplicantforanyproposedrepoweringprojectwillretainaqualifiedacousticconsultanttoprepareareportthatevaluatesnoiseimpactsassociatedwithoperationoftheproposedwindturbines.Thisevaluationwillincludeanoisemonitoringsurveytoquantifyexistingnoiseconditionsatnoisesensitivereceptorslocatedwithin2,000feetofanyproposedturbinelocation.ThissurveywillincludemeasurementofthedailyA‐weightedandC‐weighedLdnvaluesovera1‐weekperiodandconcurrentloggingofwindspeedsatthenearestmeteorologicalstation.Thestudywillincludeasite‐specificevaluationofpredictedoperationalnoiselevelsatnearbynoisesensitiveuses.Ifoperationoftheprojectispredictedtoresultinnoiseinexcessof55dBA(Ldn)wherenoiseiscurrentlylessthan55dBA(Ldn),resultina5dBincreasewherenoiseiscurrentlygreaterthan55dBA(Ldn),orresultinnoisethatexceeds70dBC(Ldn),theapplicantwillmodifytheproject,includingselectingnewspecificinstallationsiteswithintheprogramarea,toensurethattheseperformancestandardswillnotbeexceeded.


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Methodsthatcanbeusedtoensurecompliancewiththeseperformancestandardsincludeincreasingthedistancebetweenproposedturbinesandnoisesensitiveusesandtheuseofalternativeturbineoperationalmodestoreducenoise.Uponcompletionoftheevaluation,theprojectapplicantwillsubmitareporttotheCountydemonstratinghowtheprojectwillcomplywiththeseperformancestandards.AfterreviewandapprovalofthereportbyCountystaff,theapplicantwillincorporatemeasuresasnecessaryintotheprojecttoensurecompliancewiththeseperformancestandards.

ImpactNOI‐1a‐2:Exposureofresidencestonoisefromnewwindturbines—programAlternative2:450MW(lessthansignificantwithmitigation)

ProgramAlternative2wouldreplacetheexistingturbines(first‐andsecond‐generationturbines)withfewerandlargercurrent‐generationturbines.Thelocationandtypesofturbinestobeusedwouldbedeterminedasprojectsareproposed.Section2.5.2discussesCountysitingrequirementsandtechnicalsitingrequirementsfortheproposedturbines;updatedsetbackrequirementsarepresentedinTable2‐2.

Asdiscussedabove,therearenodocumentedinstancesofwindturbinescausingexceedanceofnoisestandardsintheexistingCUPs.Inaddition,current‐generationturbinesexpectedtobeinstalledthroughtherepoweringprogramhaveseveralcharacteristicsthatreduceaerodynamicsoundlevels.Themodernturbinestypicallyareupwindturbines,meaningeachturbinefacesintothewind,sothewindencounterstherotorbladesbeforethetowerandnacelle,makingforquieteroperationsthanadownwindturbine.Additionally,themodernturbineshaverelativelylowrotationalspeedsandpitchcontrolontherotors,bothofwhichreducesoundlevels.

ThenoisepredictionresultsinTable3.11‐5,however,indicatethatresidenceslocatedwithinabout1,500feetofagroupofturbinescouldbeexposedtonoisethatexceeds55dBA(Ldn).ThenoisepredictionresultsinTable3.11‐6alsoindicatesthatresidenceslocatedwithinabout800feetofagroupofturbinescouldbeexposedtonoisethatexceeds70dBC(Ldn).BecauseofthepossibilitythatimplementationofprogramAlternative2couldresultindailyLdnvaluescausedbywindturbinestoincreasebymorethan5dBatlocationswherenoisecurrentlyexceeds55dBA(Ldn),exposeresidencestonoiseinexcessof55dBA(Ldn)wherenoiseiscurrentlylessthan55dBA(Ldn),orexposeresidencetonoiseinexcessof70dBC(Ldn)thisimpactisconsideredtobesignificant.ImplementationofMitigationMeasureNOI‐1wouldreducethisimpacttoaless‐than‐significantlevel.


ImpactNOI‐1b:Exposureofresidencestonoisefromnewwindturbines—GoldenHillsProject(lessthansignificantwithmitigation)

Theprojectwouldremovethemajorityoftheexistingturbines(about734turbines)intheprojectareaandinstall27to48larger,current‐generationturbines.Thespecificsounddataforturbinestobeusedintheprojectareaarenotknown.Figure2‐15showsthelayoutofproposedturbinesintheprojectarea.Thenewturbineswouldbeinstalledfartherfromexistingresidencesthantheexistingturbines.TworesidenceslocatedalongFlynnRoadthatareabout800feetfromtheexistingturbineswouldbeabout1,300to1,800feetfromproposedturbines.


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AsdiscussedunderImpactNOI‐1a,therearenodocumentedinstancesofwindturbinescausingexceedanceofnoisestandardsintheexistingCUPs.Inaddition,proposedmodernturbineshaveseveralcharacteristicsthatreduceaerodynamicsoundlevelsandmakeforquieteroperationsthantheexistingturbines.Themodernturbineshaverelativelylowrotationalspeedsandpitchcontrolontherotors,bothofwhichreducesoundlevels.

ThenoisepredictionresultsinTable3.11‐5however,indicatethatresidenceslocatedwithinabout1,500feetofagroupofturbinescouldbeexposedtonoisethatexceeds55dBA(Ldn)orincreasesinnoisegreaterthan5dB.ThenoisepredictionresultsinTable3.11‐6alsoindicatethatresidenceslocatedwithinabout800feetofagroupofturbinescouldbeexposedtonoisethatexceeds70dBC(Ldn).Nonewturbinesareanticipatedtobelocatedwithin1,000feetofexistingresidences.BecauseofthepossibilitythatdailyLdnvaluecausedbywindturbinescouldincreasebymorethan5dBatlocationswherenoisecurrentlyexceeds55dBA(Ldn),exposeresidencestonoiseinexcessof55dBA(Ldn)wherenoiseiscurrentlylessthan55dBA(Ldn),orexposeresidencestonoiseinexcessof70dBC(Ldn)thisimpactisconsideredtobesignificant.ImplementationofMitigationMeasureNOI‐1,asdiscussedunderImpactNOI‐1a,wouldreducethisimpacttoaless‐than‐significantlevel.


ImpactNOI‐1c:Exposureofresidencestonoisefromnewwindturbines—PattersonPassProject(lessthansignificant)

Implementationoftheprojectwouldremovetheexistingturbines(about317turbines)intheprojectareaandinstall8to12larger,current‐generationturbines.Figure2‐17showsthelayoutofproposedturbinesintheprojectarea.Thespecifictypeofturbinetobeusedandturbine‐specificnoiselevelshavenotyetbeendetermined.Thenewturbineswouldbeinstalledfartherawayfromtheexistingresidence.OneresidencelocatedoffPattersonPassRoadiscurrentlylocatedabout2,200feetfromtheexistingturbinesandwouldbelocatedabout3,300feetfromthenearestproposednewturbines.

AsdiscussedunderImpactNOI‐1a,therearenodocumentedinstancesofwindturbinescausingexceedanceofnoisestandardsintheexistingCUPs.Inaddition,proposedmodernturbineshaveseveralcharacteristicsthatreduceaerodynamicsoundlevelsandmakeforquieteroperationsthantheexistingturbines.Themodernturbineshaverelativelylowrotationalspeedsandpitchcontrolontherotors,bothofwhichreducesoundlevels.

ThenoisepredictionresultsinTable3.11‐5indicatethatresidenceslocatedwithinabout1,750feetofagroupofturbinescouldbeexposedtonoisethatexceeds55dBA(Ldn)orincreasesinnoisegreaterthan5dB.ThenoisepredictionresultsinTable3.11‐6alsoindicatethatresidenceslocatedwithinabout1,000feetofagroupofturbinescouldbeexposedtonoisethatexceeds70dBC(Ldn).Becausethenearestresidencewouldbemorethan3,000feetfromthenewturbines,operationofthenewturbinesisnotexpectedtoresultinnoisethatexceeds55dBA(Ldn),70dBC(Ldn)orresultina5dBAincreaseinnoiseatresidences.Theoperationalnoiseimpactisconsideredtobelessthansignificant.Nomitigationisrequired.


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ImpactNOI‐2a‐1:Exposureofresidencestonoiseduringdecommissioningandnewturbineconstruction—programAlternative1:417MW(lessthansignificantwithmitigation)

Construction Equipment Noise

ProgramAlternative1wouldgenerallyinvolvethefollowingconstructionphases.

Phase1—Decommissioningofexistingwindturbinesandfoundationremoval

Phase2—Constructionoflaydownareas,substationsandswitchyards

Phase3—Roadconstruction

Phase4—Constructionofwindturbinegenerator(WTG)foundationsandbatchplant

Phase5—WTGdeliveryandinstallation

Phase6—Utilitycollectorlineinstallation

Phase7—Cleanupandrestoration

Table3.11‐7liststheconstructionequipmentthatisexpectedtobeusedforeachconstructionphase,basedontheassumptionsprovidedinAppendixD.

Table 3.11‐7. Construction Phases and Equipment

ConstructionPhase Equipment

1—Decommissioningandfoundationremoval

Crane,truckandlowboytrailer,excavator,grader,dumptruck

2—Laydownareas,substationsandswitchyardsconstruction

Roadgrader,tracktypedozer,drumtypecompactor,watertruck,truckandlowboytrailer,backhoe/frontloader

3—Roadconstruction Roadgrader,tracktypedozer,drumtypecompactor,watertruck,truckandlowboytrailer,backhoe/frontloader,excavator,rockcrusher

4—WTGfoundationsandbatchplant Roadgrader,tracktypedozer,drumtypecompactor,watertruck,truckandlowboytrailer,backhoe/frontloader,excavator,rockcrusher,cementtruck

5—WTGdeliveryandinstallation Crane,truckandlowboytrailer,excavator

6—Utilitycollectorlineinstallation Watertruck,backhoe/frontloader,trencher,horizontaldirectionaldrilling(HDD)boremachine

7—Cleanupandrestoration Roadgrader,excavator

Source:AppendixD.

Table3.11‐8summarizestypicalnoiselevelsproducedbyanticipatedconstructionequipment(FederalHighwayAdministration2006).Lmaxsoundlevelsat50feetareshownalongwiththetypicalacousticalusefactors.Theacousticalusefactoristhepercentageoftimeeachpieceofconstructionequipmentisassumedtobeoperatingatfullpower(i.e.,itsnoisiestcondition)duringconstructionoperationandisusedtoestimateLeqvaluesfromLmaxvalues.Forexample,theLeqvalueforapieceofequipmentthatoperatesatfullpower50%ofthetime(acousticalusefactorof50)is3dBlessthantheLmaxvalue.


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Table 3.11‐8. Typical Construction Equipment Noise Levels

EquipmentTypeTypicalLmaxNoiseLevelat50FeetfromSource(dBA)

AcousticalUseFactor(%)

LeqNoiseLevelat50FeetfromSource(dBA)

Cementtruck 79 40 75

Compactor 83 20 76

Crane 81 16 73

Dozer 82 40 78

Dumptruck 76 40 72

Excavator 81 40 77

Flat‐bedtruck 74 40 70

Front‐endloader 79 40 75

Grader 85 40 81

HDDboremachine 82 25 76

Rockcrusher 85 50 82

Trencher 80 50 77

Watertruck 76 40 72

Source:FederalHighwayAdministration2006.

Table3.11‐9summarizesthecombinednoiselevelofequipmentassociatedwitheachconstructionphase.

Table 3.11‐9. Combined Noise Level by Construction Phase

ConstructionPhase

LmaxNoiseLevelat50FeetfromSource(dBA)

LeqNoiseLevelat50FeetfromSource(dBA)

1—Decommissioningandfoundationremoval 88 83

2—Laydownareas,substationsandswitchyardsconstruction 89 85

3—Roadconstruction 91 87

4—WTGfoundationsandbatchplant 95 86

5—WTGdeliveryandinstallation 84 79

6—Utilitycollectorlineinstallation 86 81

7—Cleanupandrestoration 86 82

Basedongeometricattenuationof6dBperdoublingofdistanceandadditionalattenuationresultingfromgroundabsorptionandatmosphericeffects,potentialconstructionnoiselevelsatvariousdistancesforeachconstructionphasehavebeencalculatedrelativetotheAlamedaCountynoiseordinancestandards.Table3.11‐10summarizestheresultsofthisanalysisandidentifiesdistanceswithinwhichAlamedaCountynoisestandardscouldbeexceededasaresultoftheconstructionactivities.ThecalculationsofconstructionequipmentnoiselevelsareincludedinAppendixD.


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Table 3.11‐10. Construction Noise Analysis

ConstructionPhase

DaytimeHours(7a.m.to10p.m.) NighttimeHours(10p.m.to7a.m.)

Distance(feet)to70dBALmax

Distance(feet)to50dBALeq

Distance(feet)to65dBALmax

Distance(feet)to45dBALeq

1—Decommissioningandfoundationremoval

235 820 345 1,105

2—Laydownareas,substationsandswitchyardsconstruction

260 910 385 1,225

3—Roadconstruction 290 1,130 460 1,520

4—WTGfoundationsandbatchplant

435 1,035 625 1,390

5—WTGdeliveryandinstallation

170 545 270 865

6—Utilitycollectorlineinstallation

190 675 285 1,075

7—Cleanupandrestoration

205 750 300 1,190

Inanumberofinstances,thereareresidenceslocated600to800feetofwhereturbineconstructionactivitiescouldoccur.TheresultsinTable3.11‐10indicatethatconstructionactivitiescouldresultinnoisethatexceedsAlamedaCountynoiseordinancestandardsduringnonexempthours.Therefore,theexposureofresidencestoconstructionequipmentnoiseisconsideredtobeasignificantimpact.ImplementationofMitigationMeasureNOI‐2wouldreducethisimpacttoaless‐than‐significantlevel.

MitigationMeasureNOI‐2:Employnoise‐reducingpracticesduringdecommissioningandnewturbineconstruction

Projectapplicantswillemploynoise‐reducingconstructionpracticessothatconstructionnoisedoesnotexceedAlamedaCountynoiseordinancestandards.Measurestolimitnoisemayincludethefollowing:

Prohibitnoise‐generatingactivitiesbefore7a.m.andafter7p.m.onanydayexceptSaturdayorSunday,andbefore8a.m.andafter5p.m.onSaturdayorSunday.

Locateequipmentasfaraspracticalfromnoisesensitiveuses.

Requirethatallconstructionequipmentpoweredbygasolineordieselengineshavesound‐controldevicesthatareatleastaseffectiveasthoseoriginallyprovidedbythemanufacturerandthatallequipmentbeoperatedandmaintainedtominimizenoisegeneration.

Usenoise‐reducingenclosuresaroundnoise‐generatingequipmentwherepracticable.

ImplementothermeasureswithdemonstratedpracticabilityinreducingequipmentnoiseuponpriorapprovalbytheCounty.

Innocasewilltheapplicantbeallowedtousegasolineordieselengineswithoutmuffledexhausts.


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Construction Traffic Noise

BasedontheanalysisforVascoWindRepoweringProject(ContraCostaCounty2010),whichisintheprogramvicinity,anddataprovidedbytheprojectapplicants,atypical80MWrepoweringprojectintheprogramareaisanticipatedtogenerateanaverageof420vehicletripsperday(300trucktripsand120workertrips)throughthecourseoftheconstructionperiod.TheconstructiontrafficnoiseimpactisevaluatedusingtherecenttrafficvolumescollatedonPattersonPassRoad,whichisconsideredasatypicalmajorcountyroadthatwouldbeusedforconstructioncrewstoaccesstheprojectarea.ThetrafficvolumesalongPattersonPassRoadareabout2,700to3,700vehiclesperday(AlamedaCounty2013).Theconstructiontrafficincreasewouldincreasetrafficnoisebylessthan2dB,whichwouldnotbeanoticeableincreaseatnearbyresidentialusesalongthemajorcountyroads.Therefore,thetrafficnoiseimpactduringconstructionisconsideredtobelessthansignificant.

ImpactNOI‐2a‐2:Exposureofresidencestonoiseduringdecommissioningandnewturbineconstruction—programAlternative2:450MW(lessthansignificantwithmitigation)

Construction Equipment Noise

ProgramAlternative2wouldgenerallyinvolvethefollowingconstructionphases.

Phase1—Decommissioningofexistingwindturbinesandfoundationremoval

Phase2—Constructionoflaydownareas,substationsandswitchyards

Phase3—Roadconstruction

Phase4—Constructionofwindturbinegenerator(WTG)foundationsandbatchplant

Phase5—WTGdeliveryandinstallation

Phase6—Utilitycollectorlineinstallation

Phase7—Cleanupandrestoration

Table3.11‐7liststhecequipmentthatisexpectedtobeusedforeachconstructionphase,basedontheassumptionsprovidedinAppendixD.

Table3.11‐8summarizestypicalnoiselevelsproducedbyanticipatedconstructionequipment(FederalHighwayAdministration2006).Lmaxsoundlevelsat50feetareshownalongwiththetypicalacousticalusefactors.Theacousticalusefactoristhepercentageoftimeeachpieceofconstructionequipmentisassumedtobeoperatingatfullpower(i.e.,itsnoisiestcondition)duringconstructionoperationandisusedtoestimateLeqvaluesfromLmaxvalues.Forexample,theLeqvalueforapieceofequipmentthatoperatesatfullpower50%ofthetime(acousticalusefactorof50)is3dBlessthantheLmaxvalue.

Table3.11‐9summarizesthecombinednoiselevelofequipmentassociatedwitheachconstructionphase.

Basedongeometricattenuationof6dBperdoublingofdistanceandadditionalattenuationresultingfromgroundabsorptionandatmosphericeffects,potentialconstructionnoiselevelsatvariousdistancesforeachconstructionphasehavebeencalculatedrelativetotheAlamedaCountynoiseordinancestandards.Table3.11‐10summarizestheresultsofthisanalysisandidentifiesdistanceswithinwhichAlamedaCountynoisestandardscouldbeexceededasaresultofthe


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constructionactivities.ThecalculationsofconstructionequipmentnoiselevelsareincludedinAppendixD.

Inanumberofinstances,thereareresidenceslocated600to800feetofwhereturbineconstructionactivitiescouldoccur.TheresultsinTable3.11‐10indicatethatconstructionactivitiescouldresultinnoisethatexceedsAlamedaCountynoiseordinancestandardsduringnonexempthours.Therefore,theexposureofresidencestoconstructionequipmentnoiseisconsideredtobeasignificantimpact.ImplementationofMitigationMeasureNOI‐2wouldreducethisimpacttoaless‐than‐significantlevel.


Construction Traffic Noise

BasedontheanalysisforVascoWindRepoweringProject(ContraCostaCounty2010),whichisintheprogramvicinity,anddataprovidedbytheprojectapplicants,atypical80MWrepoweringprojectintheprogramareaisanticipatedtogenerateanaverageof420vehicletripsperday(300trucktripsand120workertrips)throughthecourseoftheconstructionperiod.TheconstructiontrafficnoiseimpactisevaluatedusingtherecenttrafficvolumescollatedonPattersonPassRoad,whichisconsideredasatypicalmajorcountyroadthatwouldbeusedforconstructioncrewstoaccesstheprojectarea.ThetrafficvolumesalongPattersonPassRoadareabout2,700to3,700vehiclesperday(AlamedaCounty2013).Theconstructiontrafficincreasewouldincreasetrafficnoisebylessthan2dB,whichwouldnotbeanoticeableincreaseatnearbyresidentialusesalongthemajorcountyroads.Therefore,thetrafficnoiseimpactduringconstructionisconsideredtobelessthansignificant.

ImpactNOI‐2b:Exposureofresidencestonoiseduringdecommissioningandnewturbineconstruction—GoldenHillsProject(lessthansignificantwithmitigation)

ConstructionnoiselevelsassociatedwithanticipatedconstructionphasesandequipmentforrepoweringprojectsarediscussedunderImpactNOI‐2aandsummarizedinTables3.11‐7and3.11‐9.Table3.11‐10summarizesthedistanceswithinwhichAlamedaCountynoisestandardscouldbeexceededasaresultoftheconstructionactivities.

Inanumberofinstances,thereareresidenceslocatedwithin800feetofwhereturbineremovalandrestorationactivitiescouldoccur.TheresultsinTable3.11‐10indicatethattheseactivitiescouldresultinnoisethatexceedsAlamedaCountynoiseordinancestandardsduringnonexempthours.Thisimpactisthereforeconsideredtobesignificant.ImplementationofMitigationMeasureNOI‐2wouldreducethisimpacttoaless‐than‐significantlevel.


AsdiscussedunderImpactNOI‐2a‐1andNOI‐2a‐2,theconstructiontrafficincreasewouldincreasetrafficnoisebylessthan2dB,whichwouldnotbeanoticeableincreaseatnearbyresidentialusesalongthemajorcountyroads.Therefore,theimpactofconstructiontrafficnoiseisconsideredtobelessthansignificant.


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ImpactNOI‐2c:Exposureofresidencestonoiseduringdecommissioningandnewturbineconstruction—PattersonPassProject(lessthansignificant)

ConstructionnoiselevelsassociatedwithanticipatedconstructionphasesandequipmentforrepoweringprojectsarediscussedunderImpactNOI‐2aandsummarizedinTables3.11‐7and3.11‐9.Table3.11‐10summarizesthedistanceswithinwhichAlamedaCountynoisestandardscouldbeexceededasaresultoftheconstructionactivities.

Becausetheclosestresidenceislocatedabout2,200feetfromthenearestturbines,whichisbeyondtheimpactdistancesidentifiedinTable3.11‐10,theconstructionnoiseimpactonresidencesisconsideredtobelessthansignificant.Nomitigationisrequired.

AsdiscussedunderImpactNOI‐2a‐1andNOI‐2a‐2,theconstructiontrafficincreasewouldincreasetrafficnoisebylessthan2dB,whichwouldnotbeanoticeableincreaseatnearbyresidentialusesalongthemajorcountyroads.Therefore,theimpactofconstructiontrafficnoiseisconsideredtobelessthansignificant.

3.11.3 References Cited

AlamedaCounty.1976.GeneralPlanNoiseElement.AdoptedJanuary8.AmendedMay5,1994.

———.2000.EastCountyAreaPlan.AdoptedMay1994.Oakland,CA.ModifiedbypassageofMeasureD,effectiveDecember22,2000.Available:http://www.acgov.org/cda/planning/generalplans/index.htm.Accessed:March1,2013.

———.2013.PattersonPassRoadandTeslaRoadSafetyStudy.PublicMeetingPresentationonMarch27.AlamedaCountyPublicWorksAgency.Available:http://www.acgov.org/pwa/updates/pattersonpassstudy.htm.Accessed:June27,2013.

AustraliaNationalHealthandMedicalResearchCouncil.2010.WindTurbinesandHealth:ARapidReviewoftheEvidence.July.

Bowdler,D.2008.AmplitudeModulationofWindTurbineNoise:AReviewoftheEvidence.InstituteofAcousticsBulletin33(4).

CaliforniaDepartmentofTransportation.2009.TechnicalNoiseSupplementtotheTrafficNoiseAnalysisProtocol.November.Available:http://www.dot.ca.gov/hq/env/noise/.Accessed:March1,2013.

Colby,W.D.,R.Dobie,G.Leventhall,D.M.Lipscomb,R.J.McCunney,M.T.Seilo,B.Sondergaard.2009.WindTurbineSoundandHealthEffects:AnExpertPanelReview.December.PreparedforAmericanWindEnergyAssociationandCanadianWindEnergyAssociation.

ContraCostaCounty.2010.VascoWindsRepoweringProjectDraftEnvironmentalImpactReport.December.DepartmentofConservationandDevelopment.Martinez,CA.

FederalHighwayAdministration.2006.FHWARoadwayConstructionNoiseModelUser’sGuide.FHWA‐HEP‐05‐054.January.

Governor’sOfficeofPlanningandResearch.2003.StateofCaliforniaGeneralPlanGuidelines.Sacramento,CA.Available:http://www.opr.ca.gov.Accessed:March1,2013.


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Hoover,R.M.,andR.H.Keith.2000.Noise Control for Buildings, Manufacturing Plants, Equipment, and Products. Lecturenotes,firstpublished1981.Houston,TX:Hoover&KeithInc.

ICFInternational.2013.NoiseTechnicalReportfortheSandHillWindProject,AlamedaCounty,CA.Draft.June.Sacramento,CA.

Illingworth&Rodkin.2006.MontezumaWindProjectNoiseTechnicalReport,SolanoCounty,California.Petaluma,CA.

O’NealR.D.,R.D.Hellweg,Jr.,R.M.Lampeter.2010.LowFrequencySoundandInfrasoundfromWindTurbines.April.AcousticalSocietyofAmerica,159thMeetingLayLanguagePapers.

OntarioChiefMedicalOfficerofHealth.2010.ThePotentialHealthImpactofWindTurbines.May.Ontario,Canada.

Rogers,A.L.,J.F.Manwell,S.Wright.2006a.WindTurbineAcousticNoise.January.RenewableEnergyResearchLaboratory,DepartmentofMechanicalandIndustrialEngineering,UniversityofMassachusetts.Amherst,MA.

Rogers,A.L.,Ph.D.,2006b.WindTurbineNoise,InfrasoundandNoisePerception.RenewableEnergyResearchLaboratory,UniversityofMassachusettsatAmherst.January18.Available:<http://www.windpoweringamerica.gov/pdfs/workshops/mwwg_turbine_noise.pdf>

SolanoCounty.2011.ShilohIVWindEnergyProjectEnvironmentalImpactReport.November30.PreparedforSolanoCountyDepartmentofResourceManagement.