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HomeMy WebLinkAboutTIR-3900FINALTECHNICALINFORMATIONREPORTforALPINENURSERY16023SE144thStreetand14609114625161stAvenueSERenton,WADRSProjectNo.14069RentonFileNo.U15007366Owner/AppilcantRoyBoyer14609161stAveSESeattle,WA98103Repot?PreparedbyD.R.STRONGConsultingEngineers,Inc.6207thAvenueKirklandWA98033(425)627-3063ReportIssueDateJuly29,2016I©20150.R.STRONGConsultingEngineersInc TECHNICALINFORMATIONREPORTALPINENURSERYTABLEOFCONTENTSSECTIONI1ProjectOverview1PredevelopedSiteConditions1DevelopedSiteConditions2NaturalDrainageSystemFunctions3SECTIONII13ConditionsandRequirementsSummary13SECTIONIII19Off-SiteAnalysis19SECTIONIV20FlowControlandWaterQualityFacilityAnalysisandDesign20ExistingSiteHydrology(PartA)20TDANorthPre-developedHourlyTimeStepModelingInput21TDANorthPre-developedHourlyTimeStepModelingOutput21TDASouthPre-developedHourlyTimeStepModelingInput21TDASouthPre-developedHourlyTimeStepModelingOutput22DevelopedSiteAreaHydrology(B)24DevelopedSiteAreaHydrology24TDANorthDevelopedHourlyTimeStepModelingInput25TDANorthDevelopedHourlyTimeStepModelingOutput25TDASouthDevelopedHourlyTimeStepModelingInput25TDASouthDevelopedHourlyTimeStepModelingOutput26161stBypassHourlyTimeStepModelingInput26161stBypassHourlyTimeStepModelingOutput26PerformanceStandards(PartC)28FlowControlSystem(PartD)28FlowControlBMPSelection28FlowControlFacilityDesignOutput30WaterQualityTreatmentSystem(PartE)39SECTIONV42ConveyanceSystemAnalysisandDesign42SECTIONVI59SpecialReportsandStudies5902015D.R.STRONGConsultingEngineersInc.AlpineNurseryPageiofiiTechnicalInformationReportCityofRenton .SECTIONVII.60OtherPermits,VariancesandAdjustments60SECTIONVIII61ESCPlanAnalysisandDesign(PartA)61SWPPSPlanDesign(PartB)63SECTIONIX64BondQuantities,FacilitySummaries,andDeclarationofCovenant64StormwaterFacilitySummarySheet65SECTIONX67OperationsandMaintenanceManual67APPENDIX“A”OFFSITEANALYSIS68APPENDIX“B”MOUNDINGANALYSIS69APPENDIX“C”CSWPPP70APPENDIX“D”BONDQUANTITYWORKSHEET71APPENDIX“E”OPERATIONSANDMAINTENANCEMANUAL72APPENDIX“F”WETLANDEVALUATION73APPENDIX“G”TRAFFICIMPACTANALYSIS74APPENDIX“H”GEOTECHNICALENGINEERINGSTUDY75APPENDIX“I”INFILTRATIONEVALUATION76APPENDIX“J”ARBORISTREPORT77ListofFiguresFigure1TIRWorksheet4Figure2VicinityMap9Figure3DrainageBasins,Subbasins,andSiteCharacteristics10Figure4Soils11Figure5PredevelopmentAreaMap23Figure6PostDevelopmentAreaMap27Figure7Detention&WaterQualityFacilityDetails41Figure8BackwaterAnalysisMap46©20150.R.STRONGConsultingengineersInc.AlpineNurseryPageiiofiiTechnicalInformationReportcityofRenlon SECTIONIPROJECTOVERVIEWTheProjectisthesubdivisionofthreeexistingparcelszonedR4(9.64ac.total)into27single-familyresidentiallots,pertheCityofRenton’s(City)subdivisionprocess.TheTaxParcelNumbersare232305-9044,-9099,and-9167.TheProject(Site)islocatedat16023SE144thStreetand14609/14625161stAvenueSERenton,Washington.TheProjectwillmeetthedrainagerequirementsofthe2009KingCountySurfaceWaterDesignManual(Manual),asadoptedbytheCity.PREDEVELOPEDSITECONDITIONSThetotalexistingSiteareaisapproximately419,829s.f.(9.64ac).ThetotalproposedProjectareais447,624s.f.(10.28ac).Thisincludesanupstreamtributaryarea(0.225ac)collectedandconveyedtotheinfiltrationfacilityandTractC,atreeretentiontract,whichwillremainundisturbedandnotbeconsideredinfinaldrainagecalculations(0.845acres,totaldevelopableareawillbe9.21acres).TheSitecontainstwosinglefamilyresidenceswithassociateddriveways.TheSitealsoincludesaplantnurserywithassociatedgreenhousesanddriveways.Theremainderofthesiteisbramble,pastureandanareaoftreesonthesouthernparcels.TheSitecontainstwoThresholdDischargeAreas(TDA),TDANorthandTDASouth.TDANorthincludesthenortheastcorneroftheProjectandtheassociatedfrontagearoundthecornerofSE144thStreetand161stAvenueSE.Runofffromapproximately18,929s.f.(0.43acres)sheetflowstothenorthintoacatchbasinonthesouthsideofSE144thStreet.Runoffcontinueswestthroughtheconveyancesystemforapproximately0.25milestotheintersectionwithlS6”AvenueSE.RunoffcontinueswestinthedirtroadwestofSEl44Streetandthencrossesunderneath154thPlaceSEwhereitoutletstoStewartCreek,aClass3stream.StewartCreekoutletstoCedarRiverapproximately0.4mileswestoftheSite.TDASouthisapproximately9.62acresinsize(8.77acresexcludingtreeretentionarea).Runoffsheetflowsacrossthesouthpropertylineandontoadjacentproperties.Runoffcontinuessouthassheetflowacrossadjacentpropertiestothesouthbeforeitenterstheconveyancesysteminthecul-de-sacof160thPlaceSEwhichoutletstotheditchatthenortheastcornerofSE148thStreetand160thPlaceSE.FlowentersaType2catchbasineastoftheintersectionapproximately100’andfollowstheconveyancesystemwestinSE148thStreetandthensouthinl6OPlaceSE.AtthecornerofSE149thStreetand160thPlaceSErunoffisdirectedsouthwestthroughapropertyandconveyeddownthehillsidethroughan18”HDPEpipe.Flowcontinuessouththroughtheconveyancesystemin160thPlaceSEandeventuallyoutletstoCedarRiver.SeeSectionIIIformoredetail.Duetositeconditions(grading)andrequiredright-of-wayimprovementsthepredevelopedareasforbothTDAswillbemodifiedinthedevelopedcondition(SeeSectionIV).Forthepurposeofhydrologiccalculations,bothTDAswillbemodeledasoutwashforest.ThereisalsoanupstreamtributaryareathatenterstheSitethatisapproximately9,800s.f.(0.225ac).Itiscurrentlydevelopedwithasinglefamilyresidenceandassociated©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage1TechnicalInformationReportCityofRenton gravelandpaveddriveways.ThisexistingupstreamareawillbecollectedandconveyedtotheproposedinfiltrationfacilityinTract“B”.Forthepurposeofhydrologiccalculations,theupstreamtributaryareawillbemodeledasexistingconditionsforboththepredevelopedanddevelopedconditions.DEVELOPEDSITECONDITIONSTheapplicanthasgainedapprovaltocreate27lotswithlotsizesrangingfromapproximately8,000s.f.to12,240s.f.AllexistingimprovementslocatedontheSitewillbedemolishedorremovedduringplatconstruction.TheProjectissubjecttoFullDrainageReviewandhastwodistinctTDAsasdescribedintheprevioussection.DevelopedTDASouthwillbeapproximately8.95acres,excludingthetreeretentiontract,whichmakesTDANorth11,009s.f.(0.253ac)inthedevelopedcondition.ThefrontageimprovementswithinTDANorthwillcreatelessthan10,000s.f.ofnewimpervioussurface(5,641s.f.total)andlessthan5,000s.f.ofpollutiongeneratingimpervioussurface(2,068s.f.total).TDANorthwillresultinnomorethana0.1-cfsdifferencebetweenthedeveloped100-yearpeakflowandthehistoricsiteconditions100-yearpeakflow.Therefore,TDANorthmeetsthecriteriaforConservationFlowControlAreaExceptionsandisexemptfromCoreRequirement#3FlowControl.Additionally,TDANorthisexemptfromCoreRequirement#8WaterQualitybymeetingthecriteriafortheSurfaceAreaExemption”.SeeSectionIVfordetail.TDASouthwillconsistoftheremainingfrontageimprovementsfortheProjectalongwiththe27single-familyresidences.Forpurposesofhydrologiccalculations,thetreeretentiontractwillnotbeincludedinthefollowingareacalculationsasitdoesnotconstituteatargetsurfaceasdefinedintheManual.The27single4amilyresidencescombinedwiththeirdrivewayswillcreateapproximately108,000s.f.(4,000s.f.perlot)ofimperviousarea.Theproposedinternalplatroad,RoadA’,willhaveaproposed53-footrightofwayandwillbeimprovedwith26feetofpavement,verticalcurb,gutter,8-footplanterstripandS4ootsidewalk.Theinternalplatroad,SE145thPlace,willhaveaproposed474ootrightofwayandwillbeimprovedwith20feetofpavement,verticalcurb,gutter,8-footplanterstripand5-footsidewalk.Road‘B’willhaveaproposed21-footrightofwayandwillbeimprovedwith20feetofpavement,verticalcurbandgutter.Theimprovementsfromtheinternalplatroadalongwiththeremainingfrontageimprovementswilladdapproximately114,841s.f.(2.64ac)ofimpervioussurface.TDASouth,includingbypassarea,willresultinatotalof5.44acofnewimpervioussurfaces.TheremainderoftheTDASouth(3.51ac)willconsistoflandscapingandlawns.Asdescribedabove,theupstreamtributaryareawillbemodeledasexistingconditionsinthedevelopedconditions.Theupstreamtributaryareaconsistsof4,580s.f.(0.105ac)ofimperviousareaand5,220s.f.(0.120ac)oflawn.TheProjectisrequiredtoprovideFlowControlDurationStandard,ForestedSiteConditionsandBasicWaterQualitytreatment,pertheManual.AllsurfacewaterrunofffromimpervioussurfacesexceptfromthebypassareaswillbecollectedandconveyedtoaninfiltrationpondlocatedinTract“B”;thepondisdesignedtoinfiltratethe100-yearstormeventandwilllimitthedischargetoemergencyoverflowsituationsonly.Priortoenteringthepond,runoffwillberoutedtoawetbiofiltrationswaletoaccommodate©20160.R.STRONGconsultingEngineersInc.AlpineNurseryPage2TechnicalInformationReportcityofRenton WaterQualityrequirements.Thebypassareaof1,110s.f.atthesoutheastcorneroftheProject161StBypassArea)willflowsouthintotheexistingconveyancesystemin161stAvenueSE.NATURALDRAINAGESYSTEMFUNCTIONSRunoffgenerallyflowssouthandsouthwestassheetflowacrosstheSite.ThenortheastportionoftheProjectincludingthefrontagealongtheintersectionofSE144thStreetand161stAvenueSE,approximately18,929s.f.,sheetflowsnorthwestofftheSiteandintoacatchbasinonthesouthsideofSE144thStreet.Thevegetationconsistsofpasture,underbrushandscatteredtrees.Siterunofftravelsassheetflowoverthewesternhalfofthesouthpropertylineontoneighboringproperties.AreviewoftheSCSsoilsmapforthearea(seeFigure4,Soils)indicatesEverettgravellysandyloamwith0to5percentslopes(EvB).PertheManual,thissoiltypeisclassifiedas“Outwash”material.TheSCSSoilseriesdescriptionsfollowFigure4.Inevaluatingtheupstreamarea,wereviewedKingCountyiMAPaerialtopography,CityofRentonMappingApplicationandconductedfieldreconnaissancetoevaluateconditionsandpotentialproblems.ThereissmallportionofupstreamtributaryrunoffenteringtheSite.Itwillbecollectedandconveyedtotheproposedinfiltrationpond.©2016D.R.STRONGconsultingEngineersInc.AlpineNurseryPage3TechnicalInformationReportcityofRenton FIGURE1TIRWORKSHEETKingCountyDepartmentofDevelopmentandEnvironmentalServicesTECHNICALINFORMATIONREPORT(TIR)WORKSHEETPart1PROJECTOWNERANDPart2PROJECTLOCATIONANDPROJECTENGINEERDESCRIPTIONProjectOwner:ProjectName:RoyBoyerAlpineNurseryAddress/Phone:Location:14609161stAvenueSETownship:23NorthRenton,WA98059Range:05EastSection:23ProjectEngineer:MaherA.Joudi,P.E.0.R.STRONGConsultingEngineersInc.Address/Phone:6207thAvenueKirklandWA98033(425)827-3063Part3TYPEOFPERMITAPPLICATIONPart4OTHERREVIEWSANDPERMITSLanduseServicesUDFWHPAUShorelineSubdivision/ShortSubd.UPDManagementoBuildingServicesUCOE404StructuralM/F/Commercial/SFRUDOEDamSafetyRockeryNaultlwallClearingandGrading0FEMAFloodplainUESASection7URight-of-Way0COEWetlandsoOther:UOther__________________________Part5PLANANDREPORTINFORMATIONTechnicalInformationReport—ConstructionPlanTypeofDrainageReview/Targeted/Type(circleone):j/ModifiedI(circle):LargeSiteSmallSiteDate(includerevisionAugust27,2015Date(includerevisionAugust27,2015dates):dates):DateofFinal:DateofFinal:©20160.R.STRONGConsullingengineersInc.AlpineNurseryPage4TechnicalInformationReportCityofRenton Part6ADJUSTMENTAPPROVALSType(circleone):Standard/Complex/Preapplication/ExperimentalIBlanketDescription:(includeconditionsinTIRSection2)StreetmodificationrequestwassubmittedtoCityforthel60”AvenueSEStreetcrosssection,southofSE145”'Place.inordertorealigntheextensionofAvenueSEtothewest.Astreetmodificationrequestwasalsosubmittedtoreducetherequiredright-of-waywidthofSE145thPlacefrom53’to47’.DateofApproval:PendingPart7MONITORINGREQUIREMENTSMonitoringRequired:Yes!NoDescribe:StartDate:CompletionDatePartSSITECOMMUNITYANDDRAINAGEBASINCommunityPlan:NewcastleSpecialDistrictOverlays:N!ADrainageBasin:LowerCedarRiverStormwaterRequirements:FlowControlDurationStandard,BasicWaterQualityPart9ONSITEANDADJACENTSENSITIVEAREASLiRivenStreamLiSteepSlope____________________flLakeLiErosionHazard__________________LiWetlandsLiLandslideHazard_________________LIClosedDepressionLiCoalMineHazard_________________LiFloodplainLiSeismicHazard___________________LiOtherLiHabitatProtection_________________Li__________________©2016D.R.STRONGconsultingEngineersInc.AlpineNurseryPage5TechnicalInformationReportCityofRenton Part10SOILSSoilTypeSlopesErosionPotentialEverett(EvB)0-5%SlightflHighGroundwaterTable(within5feet)flSoleSourceAquiferotherHighinfiltrationrateSeeps/SpringsAdditionalSheetsAttached:SCSMapandSoilDescription,Figure4Part11DRAINAGEDESIGNLIMITATIONSREFERENCELIMITATION/SITECONSTRAINTCore2—OffsiteAnalysisUSensitiveICriticalAreaUSEPAflOtherUAdditionalSheetAttachedPart12TIRSUMMARYSHEET(provideoneTIRSummarySheetperThresholdDischargeArea)ThresholdDischargeArea:Sitecomprisedoftwo,TDANorthandSouth(nameordescription)CoreRequirements(all8apply)•DischargeofNaturalLocationygNumberofNaturalDischargeLocations:IOffsiteAnalysisLevel:1/2/3dated:0111212015FlowControlLevel:1/2/orExemptionNumber(md.facilitysummarysheetSmallSiteBMPSNIAConveyanceSystemSpillcontainmentlocatedat:NIAErosionandSedimentControlESCSiteSupervisor:TIBIDContactPhone:TIB1DAfterHoursPhone:TIB1DMaintenanceandOperationResponsibility:Private/PublicI(Both)IfPrivate,MaintenanceLogRequired:YesINoFinancialGuaranteesandProvided:Yes/NoLiabilityWaterQualityType:BasicISensLake/EnhancedBasic/Bog(includefacilitysummarysheet)orexemptionNo.LandscapeManagementPlan:Yes/©2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage6TechnicalInformationReportcityofRenton SpecialRequirements(asapplicable)AreaSpecificDrainageType:CDA/SDOIMDP!BP/LMPIShared/NoneRequirementsName:Floodplain/FloodwayDelineationType:Major!MinorIExemption/None100-yearBaseFloodElevation(orrange):Datum:FloodProtecUonFacilitiesDescribe:N/ASourceControlDescribeLanduse:(comm.Iindustriallanduse)Describeanystructuralcontrols:OilControlHigh-useSite:Yes!fTreatmentBMP:MaintenanceAgreement:Yes/ti2withwhom?OtherDrainageStructuresDescribe:RunoffwillhecollectedandconveyedtotheinfiltrationfacilitylocatedinTract‘B’.Part13EROSIONANDSEDIMENTCONTROLREQUIREMENTSMINIMUMESCREQUIREMENTS—MINIMUMESCREQUIREMENTSDURINGCONSTRUCTIONAFTERCONSTRUCTIONClearingLimitsStabilizeExposedSurfacesRemoveandRestoreTemporaryESCCoverMeasuresFacilitiesPerimeterProtectionCleanandRemoveAllSiltand...Debris,EnsureOperationsofTrafficAreaStabilizationPermanentFacilitiesSedimentRetentionFlagLimitsofSAOandopenspaceSurfaceWaterCollectionPreservationareasElOtherElDewateringControlbustcontrolFlowControl—©2016D.R.STRONGconsultingEngineersInc.TechnicalInformationReportAlpineNurseryPage7cityofRenton Pad14STORMWATERFACILITYDESCRIPTIONS(Note:IncludeFacilitySummaryandSketchFlowControlType/Description—WaterQualityType/DescriptionElDetentionBiofiltrationWetBiofiltrationSwaleInfiltrationPondElWetpoolElRegionalElMediaFiltrationFacilityElSharedFacilityElOilControlElFlowControlElSpillControlBMPsElFlowControlElOtherBMPsElOtherPart15EASEMENTS/TRACTSPad16STRUCTURALANALYSISDrainageEasementElCastinPlaceVaultCovenantRetainingWallElNativeGrowthProtectionCovenantElRockery>4’HighTractElStructuralonSteepSlopeElOtherElOther:Pad17SIGNATUREOFPROFESSIONALENGINEERI,oracivilenginee/undermysupervision,havevisitedthesite.ActualsiteconditionsasobservedwereinrporatedintothisworksheetandtheattachedTechnicalInformationReport.Tothebetfmyknowledgetheinformationprovidedhereisaccurate.CI.Signed/Date020160.R.STRONGconsultingEngineersinc.AlpineNurseryPageSTechnicalinformationReportcityofRenton ©20160.R.STRONGConsultingEngineersInc.Page9TechnicalInformationReportCityofRentonFIGURE2VICINITYMAP:4t’-Renton‘TheinformationincludedonthismaphasbeencompiledbyKingCountystafffromavarietyofsourcesandissubjecttochangewithoutnotice.KingCountymakesnorepresentationsorwarranties,expressorimplied,astoaccuracy,completeness,timeliness,orrightstotheuseofsuchinformation.KingCountyshallnotbeliableforanygeneral,special,indirect,incidental,orconsequentialdamagesincluding,butnotlimitedto,lostrevenuesorlostprofitsresultingfromtheuseormisuseoftheinformationcontainedonthismap.AnysaleofthismaporinformationonthismapisprohibitedexceptbywrittenpermissionofKingCounty.AlpineNursery FIGURE3DRAINAGEBASINS!SUBBASINS,ANDSITECHARACTERISTICS©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPageIDTechnicalInformationReportCityofRenton ———1—I.Cl)Q)HiI—IIARROW(TR)/JTDANORTH‘1TDA1SOUTHIII,1I4’.’9RbNOFFDISCHARGES445SHEETFLOWTOISE144THSTREET-IIH—---I—,=1>I./‘I—N—zjt/Ln/.I:‘f‘/.i.=11>fr.....RUNOFFDISCHARGESASSHEETF4OWACROSSSO4ITHPROPERTYLiNE—3,1L160THAVESE_____—N—z-0Lt0LEGEND———PROJECTBOUNDARY.•TDABOUNDARYSITEBOUNDARYUPSTREAMTRIBUTARYAREAAREABREAKDOWNTDANORTH:18,929S.F.(0,435ACRES)TDASOUTH:415,825S.F.(9.615ACRES)UPSTREAMTRIBUTARYAREA:9,800S.F.(0.225ACRES)ri0lThGRAPHICSCALE0501901501INCH=100FT.DRAFIED8YtENDESIGNEDBPROJECTENDhEER:MAJDAFt:0&27.75pRo.ccrND.:74059[RGuRE:aP\2014\0\74069\3\0r0w4?gs\PIGtS\RPCItrjgures\FiC3_OAS!N_74069dwg3/7/2076701:29PMPStCOPYRIGHT©2075.DR.STRONGCONSULTINGEtJG’VEERS‘NC. •.• -10 M a a, r CD ftCt I igp k I-00 Ocz cornCf/f4 CD‘:2 1 - Prm—1) C’)WA. 9- 0 (0=0 It ‘4-.. 2 F. I S I It1’ EvB—Everettgravellysandyloam,0to5percentslopesMapUnitSetting•Nationalmapunitsymbol:1hmt2•Meanannualprecipitation:30to45inches•Meanannualairtemperature:50degreesF•Frost-freeperiod:180days•Farmlandclassification:PrimefarmlandifirrigatedMapUnitComposition•Everettandsimilarsoils:100percent•Estimatesarebasedonobsenjations,descriptions,andtransectsofthemapunit.DescriptionofEverettSetting•Landform:Terraces•Parentmaterial:GlacialoutwashwithacomponentofvolcanicashintheupperpartTypicalprofile•HI-0to17inches:gravellyashysandyloam•H2-17to32inches:verygravellysandyloam•H3-32to60inches:verygravellycoarsesandPropertiesandqualities•Slope:0to5percent•Depthtorestrictivefeature:Morethan80inches•Naturaldrainageclass:Somewhatexcessivelydrained•Capacityofthemostlimitinglayertotransmitwater(Ksat):High(1.98to5.95in/hr)•Depthtowatertable:Morethan80inches•Frequencyofflooding:None•Frequencyofpondthg:None•Availablewaterstorageinprofile:Low(about5.0inches)Interpretivegroups•Landcapabilityclassification(irrigated):Nonespecified•Landcapabilityclassification(nonirrigated):35•HydrologicSoilGroup:A•Othervegetativeclassification:DroughtySoils(GOO2XN4O2WA)02016D.R.STRONGconsultingEngineersInc.AlpineNurseryPage12TechnicalInformationReportcityofRenton SECTIONIICONDITIONSANDREQUIREMENTSSUMMARYTheProjectmustcomplywiththefollowingCoreandSpecialRequirements:C.R.#1—DischargeattheNaturalLocation:TDAsNorthandSouthwilldischargeattheirnaturallocation.TDANorthwilldischargeintotheexistingconveyancesystemwithinSE144thStreet.Whereas,TDASouthrunoffdischargesfromtheSiteassheetflowoverthewesternhalfofthesouthpropertyline.DevelopedSiterunoffwilldischargeatthesoutheastcornerintotheproposedconveyancesystemflowingsouthalong161stAvenueSEandthenwestintotheSE148thStreetconveyancesystem.Theexistingdownstreampathandproposeddownstreampathconvergeapproximately600’downstreamandarewithinthesameTDA.C.R.#2—OffsiteAnalysis:AnalysisisincludedinAppendixA.TheAnalysisdescribestheSite’srunoffpatternsindetail.C.R.#3—TheProjectislocatedintheFlowControlDurationStandard,ForestedSiteConditionsarea.Aninfiltrationpondwillprovideflowcontrolasrequired.TheProjectisrequiredtomatchdurationsfor50%ofthetwo-yearpeakflowuptothefull50-yearpeakflow.Alsomatchdevelopedpeakdischargeratestopredevelopedpeakdischargeratesforthe2-yearand10-yearreturnperiods(KCSWDM,Sec.1.2.).TheinfiltrationfacilityisdesignedtofullyinfiltrateSiterunoff(100yeardischargesetto0.00cfs).WithregardtoindividuallotFlowControlBMPs,Section1.2.3.3statesthat‘Anyimpervioussurfaceservedbyaninfiltrationfacilityinaccordancewiththeflowcontrolfacilityrequirement,thefacilityimplementationrequirements,andthedesigncriteriaforinfiltrationfacilitiesisexemptfromtheflowcontrolBMPsrequirement.”C.R.#4—ConveyanceSystem:Newpipesystemsandditches/channelsarerequiredtobedesignedwithsufficientcapacitytoconveyandcontain(atminimum)the25-yearpeakflow,assumingdevelopedconditionsforonsitetributaryareasandexistingconditionsforanyoffsitetributaryareas.Pipesystemstructuresandditches/channelsmayovertopforrunoffeventsthatexceedthe25-yeardesigncapacity,providedtheoverflowfroma100-yearrunoffeventdoesnotcreateoraggravatea“severefloodingproblem”or“severeerosionproblem”asdefinedinC.R.#2.Anyoverflowoccurringonsiteforrunoffeventsuptoandincludingthe100-yeareventmustdischargeatthenaturallocationfortheprojectSite.Inresidentialsubdivisions,suchoverflowmustbecontainedwithinanonsitedrainageeasement,tract,covenantorpublicright-of-way.TheproposedconveyancesystemwasanalyzedusingtheKCBWprogram,andiscapableofconveyingthe100-yearpeakstormwithoutovertoppinganystructuresorchannels.(SeeSectionV)CR.#5—ErosionandSedimentControl:TheProjectprovidesthenineminimumESCmeasures.C.R.#6—MaintenanceandOperations:MaintenanceoftheproposedstormdrainagefacilitieswillbetheresponsibilityoftheCity.AnOperationandMaintenanceManualisincludedinSectionX.©20160.R.STRONGconsultingEngineersInc.AlpineNurseryPage13TechnicalInformationReportcityofRenton CR.#7—FinancialGuarantees:Priortocommencingconstruction,theApplicantmustpostadrainagefacilitiesrestorationandSitestabilizationfinancialguarantee.ForanyconstructedormodifieddrainagefacilitiestobemaintainedandoperatedbytheCity,theApplicantmust:1)Postadrainagedefectandmaintenancefinancialguaranteeforaperiodoftwoyears,and2)Maintainthedrainagefacilitiesduringthetwo-yearperiodfollowingpostingofthedrainagedefectandmaintenancefinancialguarantee.C.R.#8—TheProjectislocatedintheBasicWaterQualityTreatmentarea.TheProjectwillutilizeaninfiltrationfacilityandisthereforerequiredtoprovidewaterqualitypriortoinfiltration.Awetbiofiltrationswaleisproposedtoaccommodatethisrequirement.SR.#1—OtherAdoptedArea-SpecificRequirements:NotapplicableforthisProject.S.R.#2—Floodplain/FloodwayDelineation:NotapplicableforthisProject.S.R.#3—FloodProtectionFacilities:NotapplicableforthisProject.SR.#4—SourceControl:NotapplicableforthisProject.S.R.#5—OilControl:NotapplicableforthisProject.SR.#6—AquiferProtectionArea:NotapplicableforthisProject.©20160.R.STRONGconsultingEngineersInc.AlpineNurseryPage14TechnicalInformationReportcityofRenton ConditionsofApprovalTHEPROPOSEDPRELIMINARYPLATISAPPROVEDSUBJECTTOTHEFOLLOWINGCONDITIONS:1.THEAPPLICANTSHALLCOMPLYWITHMITIGATIONMEASURESISSUEDASPARTOFTHEMITIGATEDDETERMINATIONOFNON-SIGNIFICANCEFORTHEPROPOSAL.2.ALLPROPOSEDSTREETNAMESSHALLBEAPPROVEDBYTHECITY.3.ALLLOTCORNERSATINTERSECTIONSOFDEDICATEDPUBLICRIGHTS-OF-WAY,EXCEPTALLEYS,SHALLHAVEMINIMUMRADIUSOFFIFTEENFEET(15’).4.SIDESEWERLINESSHALLBEINSTALLEDEIGHTFEET(8’)INTOEACHLOTIFSANITARYSEWERMAINSAREAVAILABLE,ORPROVIDEDWITHTHESUBDIVISIONDEVELOPMENT.5.ALLUTILITIESDESIGNEDTOSERVETHESUBDIVISIONSHALLBEPLACEDUNDERGROUND.ANYUTILITIESINSTALLEDINTHEPARKINGSTRIPSHALLBEPLACEDINSUCHAMANNERANDDEPTHTOPERMITTHEPLANTINGOFTREES.THOSEUTILITIESTOBELOCATEDBENEATHPAVEDSURFACESSHALLBEINSTALLED,INCLUDINGALLSERVICECONNECTIONS,ASAPPROVEDBYTHEDEPARTMENTOFPUBLICWORKS.SUCHINSTALLATIONSHALLBECOMPLETEDANDAPPROVEDPRIORTOTHEAPPLICATIONOFANYSURFACEMATERIAL.EASEMENTSMAYBEREQUIREDFORTHEMAINTENANCEANDOPERATIONOFUTILITIESASSPECIFIEDBYTHEDEPARTMENTOFPUBLICWORKS.6.ANYCABLETVCONDUITSSHALLBEUNDERGROUNDEDATTHESAMETIMEASOTHERBASICUTILITIESAREINSTALLEDTOSERVEEACHLOT.CONDUITFORSERVICECONNECTIONSSHALLBELAIDTOEACHLOTLINEBYAPPLICANTASTOOBVIATETHENECESSITYFORDISTURBINGTHESTREETAREA,INCLUDINGSIDEWALKS,ORALLEYIMPROVEMENTSWHENSUCHSERVICECONNECTIONSAREEXTENDEDTOSERVEANYBUILDING.THECOSTOFTRENCHING,CONDUIT,PEDESTALSAND/ORVAULTSANDLATERALSASWELLASEASEMENTSTHEREFOREREQUIREDTOBRINGSERVICETOTHEDEVELOPMENTSHALLBEBORNEBYTHEDEVELOPERAND/ORLANDOWNER.THEAPPLICANTSHALLBERESPONSIBLEONLYFORCONDUITTOSERVEHISDEVELOPMENT.CONDUITENDSSHALLBEELBOWEDTOFINALGROUNDELEVATIONANDCAPPED.THECABLETVCOMPANYSHALLPROVIDEMAPSANDSPECIFICATIONSTOTHEAPPLICANTANDSHALLINSPECTTHECONDUITANDCERTIFYTOTHECITYTHATITISPROPERLYINSTALLED.7.THEAPPLICANTSHALLINSTALLALLSTREETNAMESIGNSNECESSARYINTHESUBDIVISIONPRIORTOFINALPLATAPPROVAL.©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage15TechnicalInformationReportCityofRenton 8.ALLSTRUCTURESPROPOSEDFORREMOVALSHALLBEDEMOLISHEDANDALLINSPECTIONSCOMPLETEPRIORTOFINALPLATAPPROVAL.9.THEAPPLICANTSHALLESTABLISHANDRECORDAPERMANENTANDIRREVOCABLEDEEDRESTRICTIONONTHEPROPERTYTITLEOFTHETREEPROTECTIONTRACT.SUCHDEEDRESTRICTIONSHALLPROHIBITDEVELOPMENT,ALTERATION,ORDISTURBANCEWITHINTHETRACTEXCEPTFORTHEPURPOSESOFINSTALLINGADMINISTRATORAPPROVEDAMENITIESORHABITATENHANCEMENTACTIVITIES,ASPARTOFANENHANCEMENTPROJECT,WHICHHASRECEIVEDPRIORWRITTENAPPROVALFROMTHECITY.ACOVENANTSHALLBEPLACEDONTHETRACTRESTRICTINGITSSEPARATESALEANDSHALLBERECORDEDPRIORTOORCONCURRENTWITHTHERECORDINGOFTHEFINALPLAT.10.THEAPPLICANTSHALLPLACEPERMANENTFENCINGONTHEPERIMETEROFTHETREEPROTECTIONTRACT.THISSHALLBEACCOMPLISHEDBYINSTALLINGAWOOD,SPLIT-RAILFENCEWITHAPPLICABLESIGNAGE.THEADMINISTRATORMAYAPPROVEPEDESTRIAN-SIZEDOPENINGSFORTHEPURPOSEOFFACILITATINGPASSIVERECREATIONWITHINTHETRACTFORTHEBENEFITOFTHECOMMUNITY.THEADMINISTRATORMAYAUTHORIZEALTERNATESTYLESAND/ORMATERIALSFORTHEREQUIREDFENCING.THEPROPOSEDFENCINGSHALLBESUBMITTEDTO,ANDAPPROVEDBY,THECURRENTPLANNINGPROJECTMANAGERPRIORTOENGINEERINGPERMITAPPROVAL.11.ASTREETMODIFICATIONSHALLBESUBMITTEDTO,ANDAPPROVEDBY,THECURRENTPLANNINGPROJECTMANAGERPRIORTOENGINEERINGPERMITAPPROVALFORAMODIFICATIONOFTHE160THAVESESTREETCROSSSECTION,SOUTHOFROAD‘A’,INORDERTOREALIGNTHEEXTENSIONOF160THAVESETOTHEWEST.12.ASTREETMODIFICATIONSHALLBESUBMITTEDTO,ANDAPPROVEDBY,THECURRENTPLANNINGPROJECTMANAGER,PRIORTOENGINEERINGPERMITAPPROVAL,FORAMODIFICATIONTOREDUCETHEREQUIREDRIGHT-OF-WAYWIDTHOFROAD‘A’FROM53FEETTO47FEET.13.THEAPPLICANTSHALLBEREQUIREDTORECORDAPUBLICACCESSEASEMENTACROSSTHEPROPOSEDSOFTSURFACETRAILEXTENDEDFROMTHETERMINATIONOFI6OTHAVESESIDEWALK,THROUGHTHEPROPOSEDTREERETENTIONTRACT(TRACT‘C’),TO161STAVESE.THEEASEMENTSHALLBERECORDEDPRIORTO,ORCONCURRENTWITH,THERECORDINGOFTHEFINALPLAT.©2016ftR.STRONGConsultingEngineersInc.AlpineNurseryPage16TechnicalInformationReportCityofRenton 14.ACOVENANTSHALLBERECORDEDONTHEFACEOFTHEFLATRESTRICTINGVEHICULARACCESSFORPROPOSEDLOTS17-20TOTHEPROPOSEDPUBLICALLEY/UNNAMEDROADANDPROPOSEDLOTS1-6,21-27FROMROAD‘B.ADDITIONALLY,PROPOSEDLOTS17-20’SFRONTYARDSANDFRONTFACADE/ELEVATIONSSHALLBEORIENTEDTOTHENORTH(SE144THST).15.THEAPPLICANTSHALLBEREQUIREDTOCREATEAHOMEOWNERS!ASSOCIATIONANDMAINTENANCEAGREEMENT(S)FORTHESHAREDUTILITIES,STORMWATERFACILITIES,ANDMAINTENANCEANDRESPONSIBILITIESFORALLSHAREDIMPROVEMENTSOFTHISDEVELOPMENT.ADRAFTOFTHEDOCUMENT(S)SHALLBESUBMITTEDTOCURRENTPLANNINGPROJECTMANAGERFORREVIEWANDAPPROVALBYTHECITYATTORNEYANDPROPERTYSERVICESSECTIONPRIORTOTHERECORDINGOFTHEFINALPLAT.DATEDTHIS6THDAYOFAPRIL,2015.CITYOFRENTONHEARINGEXAMINER@2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage17TechnicalInformationReportCityofRenton SEPAConditionsofApproval1.ALLEARTHWORKPERFORMED,IMPLEMENTEDBYTHEAPPLICANT,SHALLBECONSISTENTWITHTHERECOMMENDATIONSOFTHEGEOTECHNICALREPORT,PREPAREDBYEARTHSOLUTIONSNW,DATEDJUNE5,2014ORANALTERNATEREPORTAPPROVEDBYTHECITY’SPLANREVIEWER.2.ADDITIONALSECONDARYREVIEWISREQUIREDFORTHEPROPOSED7-8FOOTSTORMWATERPONDWALLDURINGTHEFINALENGINEERINGDESIGNWHICHINCLUDESHYDRO-GEOTECHNICALEVALUATIONSFORBUOYANCYANDLINING,STRUCTURALREVIEWANDWALLDRAINAGERELIEFAGAINSTPOTENTIALHYDROSTATICPRESSURES.THESECONDARYREVIEWSHALLBECONDUCTEDBYANINDEPENDENTREVIEWERSELECTEDBYTHECITYATTHEAPPLICANT’SEXPENSEANDSHALLBEAPPROVEDBYTHECITY’SPLANREVIEWERPRIORTOENGINEERINGPLANAPPROVAL.3.THEAPPLICANTSHALLBEREQUIREDTOPROVIDE,TOTHECURRENTPLANNINGPROJECTMANAGER,TREERETENTIONINSPECTION/MONITORINGREPORTSAFTERINITIALCLEARING,FINALGRADING,ANDANNUALLYFORTWOYEARSBYAQUALIFIEDPROFESSIONALFORESTER.THEINSPECTION/MONITORINGREPORTSSHALLIDENTIFYANYRETAINEDTREESTHATDEVELOPPROBLEMSDUETOCHANGINGSITECONDITIONSANDPRESCRIBEMITIGATION.4.THEAPPLICANTSHALLSUBMITAREVISEDTRAFFICSTUDYINCLUDINGANANALYSISOFIMPACTSCAUSEDBYTHEPROPOSEDDEVELOPMENTTOTHE156THAVESE/SEL44THSTANDTHE156THAVENUESE/SE142NDSTREETINTERSECTIONSANDRECOMMENDAPPROPRIATEMITIGATIONASNECESSARY.THEREVISEDSTUDYSHALLBESUBMITTEDTO/APPROVEDBYTHECITY’SPLANREVIEWER,ANDAPPLICABLEMITIGATIONSHALLBEINCORPORATEDINTHEPROPOSAL,PRIORTOENGINEERINGPERMITAPPROVAL.THEAPPLICANTSHALLALSOBERESPONSIBLEFORPAYINGTHEIRFAIRSHAREOFTHECOSTOFANEWSIGNALTOBEINSTALLEDATTHE156THAVENUESE/SE142NDSTREETINTERSECTIONBASEDONANYNEWPMPEAKHOURTRIPSGENERATEDFROMTHESUBDIVISION.THEFEEWILLBEBASEDONNEWPMPEAKHOURTRIPS/i,310TOTALPMPEAKHOURTRIPSX$500,000(COSTOFNEWSIGNAL)ANDSHALLBEPAIDPRIORTOTHERECORDINGOFTHEFINALPLAT.©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage18TechnicalInformationReportCityofRenlon SECTIONIIIOFF-SITEANALYSISAnOffsiteLevelOneDownstreamAnalysiswaspreparedbyD.R.STRONGConsultingEngineersInc.andisincludedinAppendixA.020160.R.STRONGConsultingEngineersInc.AlpineNurseryPage19TechnicalInformationReportCityofRenton SECTIONIVFLOWCONTROLANDWATERQUALITYFACILITYANALYSISANDDESIGNEXISTINGSITEHYDROLOGY(PARTA)WWHM2012wasusedtomodelthepeakrunofffromtheSite.PerTable3.2.2.boftheManualthesoiltypeismodeledas“Outwash”fortheEverettgravellysandyloamSCSclassificationasshowninFigure4.Soils.TheentireSite,withtheexceptionoftheupstreamtributaryarea,ismodeledasForest.”ResultsoftheWWHM2O12analysisareincludedinthissection.AreaBreakdownTDANorthOutwashForest18,929s.f.0.435acresTDASouthOutwashForest382,007s.f.8.771acresUpstreamTributaryAreaImpervious4,580s.f.0.105acresTillGrass5,220s.f.0.120acresFormodelingpurposes,theupstreamtributaryareawascombinedwithTDASouthforanalysis.©2016U.R.STRONGconsultingEngineersInc.AlpineNurseryPage20TechnicalInformationReportcityofRenlon TDANORTHPRE-DEVELOPEDHOURLYTIMESTEPMODELINGINPUT;PREDEVELOPEDLANDUSEName:TDANorthPredevelopedBypass:NoGroundWater:NoPerviousLandUseAcresAB,Forest,FIat0.435PerviousTotal0.435ImperviousLandUseAcresImperviousTotalDBasinTotal0.435TDANORTHPRE-DEVELOPEDHOURLYTIMESTEPMODELINGOUTPUT:FlowFrequencyReturnPeriodsforPredeveloped.POC#1ReturnPeriodFlow(cfs)2year0.0000925year0.00014610year0.00019225year0.0002650year0.000321100year0.00039TDASOUTHPRE-DEVELOPEDHOURLYTIMESTEPMODELINGINPUT:PREDEVELOPEDLANDUSEName:TDASouthPredevelopedBypass:NoGroundWater:NoPerviousLandUseAcresAB,Forest,FIat8.771C,Lawn,Flat0.12PerviousTotal8.891ImperviousLandUseAcresROOFTOPSFLAT0.05DRIVEWAYSFLAT0.055ImperviousTotal0.105BasinTotal8.996©20l6D.R.STRONGConsultingEngineersInc.AlpineNurseryPage21TechnicalInformationReportCityofRenton TDASOUTHPRE-DEVELOPEDHOURLYTIMESTEPMODELINGOUTPUT:FlowFrequencyReturnPeriodsforPredeveloped.POC#1ReturnPeriodFIow(cfs)2year0.0329715year0.04459410year0.05344225year0.06601350year0.076444100year0.087842©2D16D.R.STRONGConsultingEngineersInc.AlpineNurseryPage22TechnicalInformationReportCityofRenton FIGURE5PREDEVELOPMENTAREAMAP©2016ftFtSTRONGConsultingEngineersInc.AlpineNurseryPage23TechnicalInformationReportCityofRenton U00clicmAREABREAKDOWNTOTALSITEAREA:419829S.F.(9.638ACRES)TOTALPROJECTAREA:447,624S.F.(10.276ACRES)TOTALDEVELOPABLEAREA:401,006S.F.(9.206ACRES)TDASOU77-IAREA:38Z0075.F.(8.771ACRES)TDANORTHAREA:78,929S.F(0.435ACRES)UPSTREAMTRIBUTARYAREACl)—t-4.0I’UjSI‘1‘U‘‘UItC’)TOTALPARCELAREA:9,800S.F.(0.225ACRES)IMPERVIOUSAREA:4,580SF.(0.105ACRES)PERVIOUSAREA(TILLGRASS):5,220SF.(0.120ACRES)LEGEND———PROJECTBOUNDARYTDABOUNDARYTDASOUTH__I10FzrS\\NTDANORTHGRAPHICSCALE--I950190IIUPSTREAMTRIBUTARYAREA1501INCH=100FT.CODYRIGHT©2015.ORSTRONGCONSULTINGENGINEERS[NCORAFItOBY:CENOESICNEOBY:PRO.ECTAEMAJDAlE:O&2775PRO.ECFNO-:l4O59flGVRE1A\ZGT4\0\4059\3\0’Dws\i1s\ofiF;;resVi55_PPitEV_l4OG9dwg9/29/2015l0J90AMPOE DEVELOPEDSITEAREAHYDROLOGY(B)DEVELOPEDSITEAREAHYDROLOGYWWHM2O12wasusedtomodelthedevelopedpeakrunofffromtheSite.Thesoiltypesareunchangedfromthepre-developedconditions.However,alllawnandlandscapingportionsoftheSitewillbemodeledas‘TillGrass”ratherthanoutwashtoaccountfortopsoilandlandscapedconditions.ResultsoftheWWHM2O12analysisareincludedinthissection.AreaBreakdownTDANorth*Impervious5,641s.f.0.130acresTillGrass5,368s.f.0.123acresTDASouthImpervious235,695s.f.5.411acresTillGrass152,728s.f.3.506acresUpstreamTributaryArealmperviaus4580s.f.0.105acresTillGrass5220s.f.0.120acres161StBypassAreaj1601stAveSE)Impervious1,110s.f.0.025acresTillGrass464s.f.0.011acres*Duetoconstructionoffrontageimprovements,thedevelopedTDAboundariesaredifferentthanthepredeveloped.TDASouthgrowsapproximately0.20acresinthedevelopedcondition.Thepredevelopedboundarieswereusedtocalculateallowabledischarges,astonotincreaseoralterrunoffgoingtoeachTDA.©2016ID.R.STRONGconsultingEngineersInc.AlpineNurseryPage24TechnicalInformationReportcityofRenton TDANORTHDEVELOPEDHOURLYTIMESTEPMODELINGINPUT:Name:TDANorthDevelopedBypass:NoGroundWater:NoPerviousLandUseAcresC,Lawn,Flat0.123PeMousTotal0.123ImperviousLandUseAcresROADSFLAT0.08SIDEWALKSFLAT0.05ImperviousTotal0.13BasinTotal0.253TDANORTHDEVELOPEDHOURLYTIMESTEPMODELINGOUTPUT:FlowFrequencyReturnPeriodsforMitigated.POC#1ReturnPeriodFtowfcfs)2year0.0394095year0.05160410year0.060325year0.07201950year0.081297100year0.091059TDASOUTHDEVELOPEDHOURLYTIMESTEPMODELINGINPUT:Name:TDASouthDevelopedBypass:NoGroundWater:NoPerviousLandUseAcresC,Lawn,Flat3.626PerviousTotal3.626ImperviousLandUseAcresROADSFLAT2.636ROOFTOPSFLAT2.509DRIVEWAYSFLAT0.37ImperviousTotal5.515BasinTotal9.145©2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage25TechnicalInformationReportCityofRenlon TDASOUTHDEVELOPEDHOURLYTIMESTEPMODELINGOUTPUT:FlowFrequencyReturnPeriodsforMitigated.POC#1ReturnPeriodFIow(cfs)2year1.5921565year2.05526810year2.38732225year2.82728750year3.173171100year3.5350581615TBYPASSHOURLYTIMESTEPMODELINGINPUT:Name:BypassBypass:NoGroundWater:NoPerviousLandUseAcresC,Lawn,FIat0.011PeMousTotal0.011ImperviousLandUseAcresROADSFLAT0.025ImperviousTotal0.025BasinTotal0.036161STBYPASSHOURLYTIMESTEPMODELINGOUTPUT:FlowFrequencyReturnPeriodsforMitigated.POC#1ReturnPeriodFIow(cfs)2year0.0069425year0.00888510year0.01024625year0.01205550year0.013469100year0.014943©2016ftR.STRONGConsultingEngineersInc.AlpineNurseryPage26TechnicalInformationReportCityofRenton .FIGURE6POSTDEVELOPMENTAREAMAP©2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage27TechnicalInformationReportCityofRenton ‘1I6ISTAVESECoAREABREAKDOWNTOTALEXIST/NcS/ITAREA:479,829SF.(9.538Ac)IUhi00hiHwSz%0389,997S.F.(6.953Ac)TOTALPROJECTAREA:447,624S.F.(10.276Ac)TOTALDEVELOPABLEAREA:407,006S.F.(9.206Ac)TRACTA/OPENSPACEAREA(COLLECTED):953S.F.(0.022Ac)fiLLCRASS:953S.F.(0.022Ac)/MPERVIOUS:00TWASNFOREST’TRACTC/UNDISTURBEDAREA(NOTCOLLECTED):DTDASOUTHAREA(DEVELOPED):LOTAREA(COLLECTED):IMPERVIOUS:TILLCRASS:ROWAREA(COLLECTED):IMPERVIOUS:TILLGRASS.TRACTSAREA(COLLECTED):IMPERVIOUS:TILLGRASS:244,96)S.F.106,000SF.136,961S.F.(5.624AC)(2.480AC)(3.144AC)O—I—CIt.3:tat36,818S.F.(0.845AC)0SF.(0.0AC)36818SF.(0.845AC)114,841S.F.(2636AC)714,841SF(2.636AQ)0S.F.(0.000AC)27,668S.F.(0.635AC)12,654SF.(0.295AC)74,814S.F.(0.340AC)BYPASS(161STAVESE):IMPERVIOUS:fiLLGRASS:çUS9UPSTREAMTRIBUTARYAREA(COLLECTED):tn!iJIMPERVIOUS:TILLCPASS:n::::IDANORTHAREA(NOTCOLLECTED):IMPERWOOS:TILLCRASS:1,574SF;(0.036AC)1,110S.F.(0.025AC)464S.F.(0.0FFAC)9,500S.F(0.225AC)4,580S.F.(0.105AC)5,220SF(0.120AC)11,009SF.5,641S.F.5,368SF.(0.253AC)(0.130AC)(0.123AC)NOrrSGRAPHICSCALE050100150LIII 1INCH=100FT.DR.srnc:oC5..LtN3E7,SIEtRSIC.PTh’7EDBY:DENDESIGNEDBY:PROJECTENGINEER:MAdDAZE:062775PROJECTNO.:(4069IR:\20!4\0\14O&9\3\CrawtnB,\PIot,\RCpOrflqurnkflGtOEV_?406gdw93/7/20(67-0305PMPSICCPtRCHI©205AGURE6 PERFORMANCESTANDARDS(PARTC)TheProjectisrequiredtoadheretoFlowControlDurationStandard,ForestSiteConditionscriteria.TheFlowControlperformancecriteriarequiresthatthedevelopedcondition’sdurationsmustmatchthepredevelopeddurationsrangingfrom50%ofthetwo-yearpeakflowuptothefull50-yearpeakflowandalsomatchdevelopedpeakdischargeratestopredeveloped(forested)peakdischargeratesforthe2-yearand10-yearreturnperiods(KCSWDM,Sec.1.2).TheBasicWaterQualityTreatmentgoalistoremove80%ofTSSforflowsorvolumesuptoandincludingtheWQdesignfloworvolume.ConveyancecriteriafortheProjectrequirethatallnewpipesbedesignedtoconveyandcontain(atminimum)the25-yearpeakflow.Giventheproposeddesignofafullinfiltrationpond,theactualdischargefromtheProjectwillbelimitedthatwhichisgeneratedbythebypassarea(TDASouth)andTDANorth.Asdiscussedpreviously,TDANorthwasexemptfromflowcontrolsincethedeveloped100-yearpeakflow(0.091cfs)didnotincreasebymorethan0.1cfsfromthepredeveloped100-yearpeakflow(0.000cfs).ForTDASouth,thePointofCompliancecomparisonshouldbemadebetweenthepredevelopedand161stBypasstimeseries.Theresultsaboveshowareductioninthe100-yearpeakfromthesite.FLOWCONTROLSYSTEM(PARTD)TheSitewillutilizeaninfiltrationpondmeetingtheFlowControlDurationStandard,ForestedSiteConditionsrequirements.TheWesternWashingtonHydrologyModel(WWHM2O12)softwarewasusedtosizetheinfiltrationfacility.Theinfiltrationponddesigninformationisincludedinthissection.Ameasuredinfiltrationrateof70inches/hourwasfoundforsoilswithinthesitebyEarthSolutions,onDecember22,2014.ThisratewasfoundusingtheEPAfallingheadtest.Thedesignedinfiltrationratewasdeterminedbyusingthesimplifiedmethod.‘Design=‘MeasuredxFTestingXFGeometryXFpiugginglMeasured=70inches/hourFTesng=0.30(EPAmethod)FGeoynetry4(D/W)+0.05=2.15(Maximum1)D=21-feet(Depthofpondbottomabovegroundtable)W=40-feet(Widthofpond)Fpiuggjng=1.0(InfiltrationFacilityprecededbywaterqualityfacility)1De&gn=21inches/hour(Maximumallowedfordesign20inches/hour)FLOWCONTROLBMPSELECTIONSubdivisionprojectsarerequiredtomitigateforimpervioussurfaceequaltoaminimumof10%ofeachlotareabyuseofFlowControlBestManagementPractices(SMP’s).WithregardtoindividuallotFlowControlBMPs,Section1.2.3.3statesthat“Anyimpervioussurfaceservedbyaninfiltrationfacilityinaccordancewiththeflowcontrol©2016D.R.STRONGconsultingEngineesInc.AlpineNurseryPage28TechnicalInformationReportcityofRenlon facilityrequirement,thefacilityimplementationrequirements,andthedesigncriteriaforinfiltrationfacilitiesisexemptfromtheflowcontrolBMPsrequirement.”02016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage29TechnicalInformationReportCityofRenton FLOWCONTROLFACILITYDESIGNOUTPUTWWHN2012PROJECTREPORTProjectName:InfiltrationPondSiteName:AlpineNurserySiteAddress:16023SE144thStreetCity:Renton,WAReportDate:2/10/2016Gage:SeatacDataStart:1948/10/01DataEnd:2009/09/30PrecipScale:1.00Version:2013/06/26LowFlowThresholdforPOC1:50Percentofthe2YearHighflowThresholdforPOC1:50yearPREDEVELOPEDLANDUSEName:PredevelopedBypass:NoGroundwater:NoPerviousLandUseAcresAB,Forest,Flat8.771C,Lawn,Flat.12PerviousTotal8.891ImperviousLandUseAcresROOFTOPSFLAT0.05DRIVEWAYSFLAT0.055ImperviousTotal0105BasinTotal8.996ElementFlowsTo:SurfaceInterflowGroundwater©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage30TechnicalInformationReportCftyofRenton MITIGATEDLAEDUSEName:RD:NBypass:NoGroundwater:NoPerviousLandUseAcresC,Lawn,Flat3.626PerviousTotal3.626ImperviousLandUseAcresROADSFLAT2.636ROOFTOPSFLAT2.509DRIVEWAYSFLAT0.37ImperviousTotal5.515BasinTotal9.141ElementFlowsTo:SurfaceInterflowGroundwaterTrapezoidalPondiTrapezoidalPondName:TrapezoidalPond1BottomLength:155.62ft.BottomWidth:24.05ft.Depth:5ft.Volumeatriserhead:0.4548acre-ft.InfiltrationOnInfiltrationrate:70Infiltrationsafetyfactor:0.285Sideslope1:0To1Sideslope2:3To1Sideslope3:3To1Sideslope4:0To1DischargeStructureRiserHeight:4ft.RiserDiameter:18in.ElementFlowsTo:Outlet1Outlet2©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage31TechnicalInformationReportCityofRenton PondHydraulicTableStage(ft)Area(ac)Voiune(ac—ft)Discharge(cfs)Infilt(cfs)357.000.0850.0000.0000.000357.060.0860.0040.0001.728357.110.0870.0090.0001.728357.170.0880.0140.0001.728357.220.0880.0190.0001.728357.280.0890.0240.0001.728357.330.0900.0290.0001.728357.390.0900.0340.0001.728357.440.0910.0390.0001.728357.500.0920.0440.0001.728357.560.0920.0490.0001.728357.610.0930.0540.0001.728357.670.0940.0600.0001.728357.720.0950.0650.0001.728357.780.0350.0700.0001.728357.830.0960.0750.0001.728357.890.0970.0810.0001.728357.940.0970.0860.0001.728358.000.0980.0920.0001.728358.060.0990.0970.0001.728358.fl0.0990.1030.0001.728358.170.1000.1030.0001.728358.220.1010.1140.0001.728358.280.1020.1200.0001.728358.330.1020.1250.0001.728358.390.1030.1310.0001.728.358.440.1040.1370.0001.728358.500.104o.:430.0001.725358.560.1050.1480.000:.728358.6:0.1060.1540.0001.728358.670.1070.1600.0001.728358.720.1070.1660.0001.728358.780.1080.1720.0001.728358.830.1090.1780.0001.728358.890.110ozs0.0001.728358.940.1100.1910.0001.728359.000.1110.1970.0001.728359.060.1220.2030.0001.728359.110.1130.2090.0001.728359.170.1130.2:50.0002.728359.220.1140.2220.0001.728359.280.1150.2280.0001.728359.330.1150.2350.0001.728359.390.1160.2410.0001.728359.440.1170.2480.0001.728359.500.1180.2540.0001.728359.560.1180.2610.0001.728359.610.1190.2670.0001.728359.670.1200.2740.0001.728359.720.1210.2810.0001.728359.780.1210.2870.0001.728359.830.1220.2940.0001.728359.890.1230.3010.0001.728.359.940.1240.3080.0001.728360.000.1240.3150.0001.728©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage32TechnicalInformationReportCityofkenton 360.060.1250.3220.0001.728360.110.1260.3290.0001.728360.170.1270.3360.0001.728360.220.1270.3430.0001.728360.280.1280.3500.0001.728360.330.1290.3570.0001.728360.390.1300.3640.0001.728360.440.1310.3720.0001.728360.500.1310.3790.0001.728360.560.1320.3860.0001.728360.610.1330.3940.0001.728360.670.1340.4010.0001.728360.720.1340.4090.0001.728360.780.1350.4160.0001.728360.830.1360.4240.0001.728360.890.1370.4310.0001.728363.940.1370.4390.0001.728361.000.1380.4470.0001.726361.060.1390.4540.191:.728361.1:0.1400.1620.5411.728361.170.1410.1700.9941.723361.220.140.4731.5301.723361.280.1420.1862.1381.728361.330.:430.4942.8111.728361.390.1440.5023.5421.728361.440.1450.5104.3281.728361.500.1450.5185.1641.728361.560.1460.5266.0491.728361.610.1470.5346.9781.728361.670.1480.5427.9511.728361.720.1480.5508.9661.728361.780.1490.55910.021.728361.83o.:so0.56711.111.728361.890.1510.57512.241.728361.940.1520.58413.401.728362.000.1520.55214.601.728362.060.1530.60115.841.728©2016aR.STRONGConsultingEngineersInc.AlpineNurseryPage33TechnicalInformationReportCityofRenton ANALYSISRESULTSStreamProtectionDurationPredevelopedLanduseTotalsforPOC#1TotalPerviousArea:8.891TotalImperviousArea:O.105MitigatedLanduseTotalsforPOC#1TotalPerviousArea:3.626TotalImperviousArea:5.515FlowFrequencyReturnPeriodsforPredeveloped.POC#1ReturnPeriodFlow(cfs)2year0.0329745year0.04461410year0.05347725year0.06607150year0.076525100year0.067949FlowFrequencyReturnPeriodsforMitigated.POC#1ReturnPeriodFlow(cfs)2year0Syear010year025year050year0100year0StreamProtectionDurationAnnualPeaksforPredevelopedandMitigated.POC#1YearPredevelopedMitigated19490.0340.00019500.0640.00019513.0380.00019520.0260.00019530.0240.00019340.0310.00019550.0320.00019560.0310.00319570.0360.00019560.0320.03013593.3240.00019630.0320.00019610.0270.00019620.0260.00019630.0270.00019640.0320.00019650.0270.00019660.0280.00019670.0420.000©2016D.R.STRONGConsultingengineersInc.AlpineNurseryPage34TechnicalInformationReportCityofRenton 19680.0460.00019690.0260.00019700.0280.00019710.0270.00019720.0440.00019730.0250.00019740.0290.00019750.0400.00019760.0260.00019770.0300.00019760.0400.00019790.0370.00019800.0360.00019810.0360.00019820.0550.00019630.0360.00019640.0290.00019850.0250.00019860.0380.00019870.0440.00019880.0200.00019890.0240.00019900.0640.00019910.0570.00019920.0290.00019930.0190.00019940.0210.00019950.0280.00019960.0450.00019970.0370.00019980.0360.00019990.0710.00020000.0360.00020010.0260.00020020.0370.00020030.0330.00020040.0690.00020050.0290.00020060.0270.00020070.1090.00020060.0570.00020090.0360.000StreamProtectionDurationRankedAnnualPeaksforPredevelopedandMitigated.POC#1RankPredevelopedMitigated10.10870.000020.07070.000030.06920.000040.06390.000050.06370.000060.05750.000070.05680.000080.05460.000090.04560.0000100.04500.0000©20160.R.STRONGConsulhngEngineersInc.AlpineNurseryPage35TechnicalInformationReportCityofRenton 110.04380.0000120.04370.0000130.04160.3000140.04040.0000150.03970.0000160.03830.0003170.03800.0000180.03760.0000190.03750.0000200.03750.0000210.03670.0000220.03670.0000230.03630.0000240.03620.0000250.03620.0000260.03600.0000270.03580.0000280.03430.0000290.03350.0000300.03230.0000310.03200.0000320.03190.0000330.03190.0000340.03090.0030350.03070.0000360.02960.0303370.02920.0000380.02890.0000390.02880.0000400.02860.0000410.02820.0303420.02800.0000430.02790.0000440.02740.0000450.02730.0000460.02710.0000470.02710.0000480.02660.0000490.02650.0000500.02640.0000510.02600.0000520.02590.0000530.02590.0000540.02540.0000550.02530.0000560.02430.0000570.02420.0000580.02410.0000590.02100.0030600.01970.0000610.01900.0303StreamProtectionDurationPoc#1TheFacilityPASSED©2016iiR.STRONGConsultingEngineersInc.AlpineNurseryPage36TechnicalInformationReportCityofRenton •TheFacilityPASSED.Flow(cfs)PredevMitPercentagePass/Fail0.0165129500Pass0.0171114700Pass0.0177102400Pass0.018391300Pass0.018982100Pass0.019573300Pass0.020164900Pass0.020759500Pass0.021354300Pass0.021949400Pass0.022644700Pass0.023240200Pass0.023836000Pass0.024432700Pass0.025031600Pass0.025629300Pass0.026227200Pass0.026824400Pass0.027421800Pass0.028020700Pass0.028619100Pass0.029216600Pass0.029815600Pass0.030414500Pass0.031013500Pass0.031612800Pass0.032311500Pass0.032910800Pass0.033510400Pass0.03419500Pass0.03478800Pass0.03538100Pass0.03597700Pass0.03657100Pass0.03716800Pass0.03776200Pass0.03835800Pass0.03895700Pass0.03955700Pass0.04015500Pass0.04075100Pass0.04144400Pass0.04204200Pass0.04264000Pass0.04323600Pass0.04383500Pass0.04443200Pass0.04503200Pass0.04563000Pass0.04622900Pass0.04682800Pass0.04742600Pass0.04802600Pass0.04862500Pass©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage37TechnicalInformationReportCityofRenton •0.04922300Pass0.04982200Pass0.05042000Pass0.05112000Pass0.05171600Pass0.05231600Pass0.05291500Pass0.05351300Pass0.05411300Pass0.05471300Pass0.05531200Pass0.05591100Pass0.05651000Pass0.0571900Pass0.0577800Pass0.0583700Pass0.0589700Pass0.0595700Pass0.0602700Pass0.0608700Pass0.0614700Pass0.0620700Pass0.0626700Pass0.0632700Pass0.0638600Pass0.0644500Pass0.0650500Pass0.0656500Pass0.0662300Pass0.0668300Pass0.0674300Pass0.0680300Pass0.0686300Pass0.0692200Pass0.0699200Pass0.0705200Pass0.0711100Pass0.0717100Pass0.0723100Pass0.0729100Pass0.0735100Pass0.0741100Pass0.0747100Pass0.0753100Pass0.0759100Pass0.0765100PassThegroundwatermoundinganalysisisincludedinAppendixB.©2016D.ftSTRONGConsultingEngineersInc.AlpineNurseryPage38TechnicalInformationReportCityofRenton WATERQUALITYTREATMENTSYSTEM(PARTE)TheProjectislocatedintheBasicWaterQualityTreatmentarea.Thetreatmentgoalis80%removaloftotalsuspendsolidsforatypicalrainfallyear,assumingtypicalpollutantconcentrationsinurbanrunoff.TheProjectwillutilizeaninfiltrationfacilityandisthereforerequiredtoprovidewaterqualitytreatmentpriortoinfiltration.RunoffwillbecollectedandconveyedtotheproposedinfiltrationfacilityinTractB,precededbyawetbiofiltrationswaletoaccommodateBasicWaterQualityrequirements.ThewetbiofiltrationswaledetailsareprovidedinFigure7.Theswalesizingdetailsareprovidedbelow.Thewaterqualitydesignflowrateisdefinedas60%ofthedeveloped,15minutetimestep,two-yearpeakflowratewhenprecedingdetention,whichequatesto1.404cfsforthedevelopedsite.15-MinuteAnalysisFlowFrequencyReturnPeriodsforMitigated.POC#1ReturnPeriodFlow(cfs)2year2.340855year3.05674710year3.55575325year4.21617650year4.730641100year5.264935WetBiofiltrationSwaleSizingDetailsStep1:Calculatedesignflows.Q(2yr.l5min)=2.34cfsQwq=0.6(2.34)=1.404cfsStep2:Calculateswalebottomwidthanddesignflowdepth.=0.2,s=0.005Wftb=18-feet(width),y=0.32’(designflowdepthbasedonwidth,slopeandflow)Step3:Determinedesignflowvelocity.Vwq=Qwx/Awq,Awq=by+Zy2(Z=sideslopes=3)Awq=18(0.32)+3(0.32)2=6.067ft2Vwq=1.404/6.067=0.2314Wsec<ift/secStep4:Calculateswalelength.L=54Q*Vwq=540*0.2314=125feet(130feetproposed)©2016U.R.STRONGConsultingEngineersInc.Page39TechnicalInformationReportCityofRentonA’pineNursery Step5:Adjustswalelayouttofitonsite.Calculatedswalelengthfitsthesjte.Step6:ProvideconveyancecapacityforflowshigherthanQWg.Q100=5.265cfs,b=18-feet,Z=3,s=0.005ft/ftn1=0.025(PerTable4.4.1.B,assumingnovegetationforearth,windingandsluggishopenchannels)=(1.49/nioj)*A100**S°5(Aioo=by+Zy2,R=A100/(b+2y/Ti1SolveforyiooYioo0.20’A100=18(0.2)+3(0.22)=3.72s.f.V100=Q/A100=5.265/3.72=1.415ft/sec<3ft/sec(Nohighflowbypasssystemneeded)Step7:Adiustforextendedwetseasonflow.Thewetbiofiltrationswalewillbeupstreamoftheinfiltrationfacility;therefore,noadjustmentisneeded.PertheManual,aManning’sroughnesscoefficientof0.20wasusedtocalculatethewaterqualitydesignflow,widthanddepth.However,inordertocalculatethe100-yearflowthroughthewetbiofiltrationswale,theManualrequirestheManning’sroughnesscoefficientbeselectedtoreflectthedeeperflowconditionswithlessresistanceprovidedbygrassduringthesehigh-flowevents.TheManning’sroughnesscoefficientwasselectedfromTable4.4.1.B.assumingnovegetationforearth,windingandsluggishopenchannels(niQo=0.025).Thisvaluewasselectedasaconservativeapproachwhendeterminingifahighflowbypasssystemwasneeded,sincethegreatertheroughnesscoefficient,thegreaterthevelocity.020160.R.STRONGConsultingEngineersInc.AlpineNurseryPage40TechnicalInformationReportCityofRenton FIGURE7DETENTION&WATERQUALITYFACILITYDETAILS©2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage41TechnicalInformationReportCityofRenton bJ>_UzUz-j0IW(AIWNTARUAPP404040INCIPPSULSEE501AM000M000NOTENE1/4SEC77ON23,TOWNSHIP23N,RANGE5E,WAd.ALPINENURSERYPhnhlnRequfrements1.Oslolblllbeell,bllthodofreughasthe‘ow,Heon000In.otthenale,objen‘athefallooongp701.3Seethflot..uorfeanq000gLnoA-ybnkfll00.)eea2rnSeprsbciaOciiSeo)n,and4.ip,nIIalysen,o0ath.,ntns’ntona!17104(atptasadnsibebISeednaybeçpbed0,.lydsienil.;ocbec.&niappiK0000alInit.d.ta,leHetIdnngthe(aol‘,en[dame,daEi4inifon&flocot110na,Snk,uededntheIiinayoNneedmopatonNne.etthea,ad&beooa1mantetteelbento.atdmien,aloalth,-pailcutsouMoLet1bedIsleplanangoScuida&tnolbeendforaprobln,orothanno,C[OTipVa.2Srni,nrar.e.’ano’aen11eetithdoy.nd,ttrc,ddotsnweUn.chOnofaednendebntAnasaofd,yon’andaH-mt,moospec.,thiscmcIa!TOwnO&ofotffELttTwomecytaid.Insoeedaknforth.KngCo00oyuosInhiath&mTa5c6)ICIp661)Tnseothfl&oazbooot&owtkntheSaim’asIncliiSCpasatAtathoton,.athen.nun,abaeuct,nineoaletstooloperationmardeed.paseed.QZcth:oodaedwthesit..TabieOilIfl.641)timpast’s‘abe,pinspctniaslyrokrns‘IntorondenoonSon.°ftheseseedlypes.benevee.naymoOtconsillyavid’s:.3Aanlytnnradowslesbflbeproini.dfr.mssoraw.oerSo.,nfiIpo:ohisb.eo.,uNIsh.thflonaybetonebthslnIton,eebyvoTers!the‘wokbos=.usckszphntcmoOthenfluntrootediftheseoctetsoleniefr.omie.oneosiee.roekolMaimobailbeplacedso-n(a.BnNvopp1kdseedmaS.edencb.dAPpa2TEDflCSm.daode.tordeausnossoornoibbnkels3.4bso-,thedesigone.mecr.Ienraoa.csatypocallawnseednixonbedicapepbnnnaybemedHYeevitfocswate000.edmcsnvcyba0hflowL500ddnnt000haUbepvtnlothes&lbiedoageçoatyoft&%egeutnAcceptablepassasodpoiiodeornsorepsesemedTobkdilE(pS-al)POsai.Iothnth.eho0snntbelsblen.ybeuoeiifofrcook),p*itelymiina.dioAth.plnoôcsedn,iosopnadntothecoat.ee,ntme,I,.5,1eelbeadbaam.ettsakecytoopcnLNodnpaopo(e.g..Litthoeici)aiepefentNoteroaneeee..,.ewdeeoosonfrilKeegCeo,.,an,shoe*0fOXanm,dnothetan.localheeoi&g.aAcnid0,ond‘arasbrthatscooemlercaraExitrooftiao2Sdn,ybeaioda,ateonI)ccondtorn.thewetse1500Owsdanncnsesen.eifedcthsnodobtflu0*400000lienOsthnthnucndrsretenadgeomotatnmit,,themdi,panfromaandmanoeshlefeethetenoneroadium,of.bbtoooiienow’ae.SodniotbeeeHnd0040enikdmonthetnletht,aaibefaernn&ro0000üeindlobe,efontntsthiE—bethuoned-—3m.ebebeJaiiat,Atool.,no‘5,0‘3’.o-orIniodnissiatIAbo.roo,noO$na.rteoado.4o8smsatabaItAteLi’)bismoLsob.ton.uoano.tteionoIacsmn.O.LS4th00000l5.san.ootth.aelen.doo’om•0——eq—as—gaAo,a.nasm,-b.,0.oAbsb,iaensdstbcia00000po’5&noa.dofleOx.nnynakonça.1Purss;ngaarmoAoeltb.soeeaooKpesnbaoo.o0b_,_ecst_t.._s[_0_co—c—a,basso•Ue,ssl.oloan•,dcnoec.eee,.!!fP’°°’2000,.w.._ntOIHehaOOsnWJ,teed,.,lOhannhaIa.tldo.aa00,Soda.tevdLalt.eI_joganaoweI000I:frwhsrinseNosebooscd,neat0.—N.e’s0WInceonoaosv-—Crare.,onAtenimaalicia4ten0105r’a°[0weCo..—.rotc-ne.Ca..Hea04aesoaodeehh.It.—00•oona,—0—0005aCOsta-A-AI.04C4204SAPE‘UPOL‘WACOYad54’0044100Wc.FadDEFTNT&AACW081ADAJSTTOdM4TAR45thUS04MWCCIL’BARSMCPQ.CMAXORUSS°AoFscF8405ARthaDLDIHOSlutBAFCSWTALPARISMISTCDERDS04RSWdTSOOnBARSHeISTSE£P0YYCOOTEDSlfllSI’PEXDE3S04800WISflSOPEC04WEHEVFad05104PC$110ItROSEWAY0805S.CLLWRISSIOdMOdPitU#CdlFadS000LECIIO°tTnPTadTOW2SIWIAIS)trsCEo_OS84ER‘SFadUSECl)OSFP040*010-F-WAYatFadOffiHSCIELSWOOdYP3400BIROCACEDETAIL(KCSHVMRGURE5J.LC)Os..,Oil.PoredPaulo1Cloth3D)AmoSH0370-lEO51TE20-lEO0007U’)D-JSOILAMENDMENTNOTE:SoIlkllendr-entITwoCoabenmaonom),fw,flroesrdeomp,rIobllbebiiedml.Lemonnv,ieu.aimeoOan.so.cndthetopsoil,oleaothesoildae.dyb.morgmiocoolenoofIpacedorpeoletThorappisestobolbtiiastaoiwcialuodyooilsEoreq-ro.tsesoilsfgnnloooroorses)bopnollmnolbeopedoliodomndedtoth.oeqonedongonivcoooont.)CtnpormaotbebidmootheminImamun,oslleadeptho6aothntopoemsthecoonposbfromterow.ohedooao.aIoo,maidaeotogodefmrdhire000dfftIeoOaoil’)2eotbtCflF°’°°deunwardp.ecobomtier.,.,,b)Congot‘billcal002unsoylowtheto.cow,o°’oosemdeo-000fflledn.y.c-cmaterortochair.b,mfJm,anuI,c)Ce,cthaieel002cmunacenheedmasonbenmeilankochferalcolifotnbuterüintooeOeoo100wiles2SoDorsod‘and,claysantoofpe,InlhanICpavonteboatobertsdedIfthneitroocenfoccootamaiba0!flelt&,17001moo4.oleeIteitlaleneonthaibeneedwoo.flonenitlicetopIne0[itiedwateeeobnstanSnSecam423t4.23)fordebis000eatsecthner.ptooo,KCSI$VMPLANENGREQUIREMENTSFORPETSIORL7RA170ffSWALESrBARSSWILL0WA040(4’UCMAR)Ti’(TOP)SECNOTEI4HOOf0.MsWS101010flAEECSEEDETAILBELOWALWBMIMadALUA4NOSCOSTEEL(rep)PLANViEW8000CCMAiN010(40401IanBrHeWING400055840500400571341.BARSAS£510500N1N01EAPP04tWOSSFTH40.44005/8th‘S403RY0000ELOCNONGMLONANISM(PATh.OOf)ad‘0504LOCATESlEWORECTEYSSDWPADLDO(TOOfftmOidS40Ar11€OTTF1440AR5NHETBIORLIRAnONSWALEStSEEMOlTILOPER70011.BAtCrsCWOE(24040050010weanSFNOTEI)aFADE-StantMsl1WLLASFTOtSRISERARGOTCOATEDSTEELSTEPS04LADDERDETAILHOOKCLAMPSEC17ONA—AKETBIOFILIRAnONsWALEC1?QSSSEC77ONB41II‘aoNOJENET8071.WATOadERASEHANTWOPEWLANOSCP,WNCP0.44740KCSINO41SFTHEshutN’sso_iI*005iltesrcInLoana?LA.MflTOE0015OrmalzAlloyStAllC2W*kçDey.Solon.‘foodD8110115ccUldenoodLocdoooCELLLINERNOW:(KCSWDM6.2.4.?)C2COMPACPEDTILLUIIERSIbceooetosbflbrllisthsthnrong.clioo2,SodshoDb.comportedIs92’.mmcmdi)dmnty.modif.dpeoamomthndo4ClM0-1337)3,AdieosdepthsoddonwryomdtaoucdodlbemflisodooniesoZi.tomoSespetmacto(IiIS’ntflm.yüoobetedmtinof(Ness,Iled2.4.Soiltheildbepbvedmlmrbhlz.N15DR.STRONGCONSULTINGENGINEERS04WN8KNWLYSaRbORSTINAOSMCIGOGANGWA040087.3P451072423loreo’anNIseatsenorS005ooniseN..wooa.Coil000se,,ossetaLootSwso.wmsalSr005beeEnelyno.otnO,,rea.IOtflNHen.f00.000t)eeoiiaoIaoeuea,,.550toWelOWOIsle0*00oem,cerIseWce,OssivoSteonIIS.SoilsmaybeusedthisfleeTbefobw’soppidataw%J0i.ri—i0ND.REVISICNGRAPHICSCALE00IS25INCH=ISFT,0thIIIALPINENURSERYogia.isASHOlEDCITYOFPRIwfl1<RENTONJBYGAstAJIacltkwPlanning/BuildingfPubIicWork,Dept.RECOMMENDEDFORAPPOVALBY:_____________________DaIe:,.._...,._BY:_________________Dalou....__.....BY:Date:......,___BY:Date:,..._..__WEBIOFILTRA11ONSWALEDETAiLSUi5007366DRSPROJECTNO.149IAIINI I-i>-wU(f)0-0zInz-J0.8NO1-1NE1/4SEClYON23,TOWNSHIP23N,RANGEALPINENURSERY5ff,V/Sf.[___TARI1u:.AROCKYROflCflOYATOflTMLSDI.:fl’eV.IocftyR50UIaLDPROILCIION•l0NIWIP24*(Ip.ILn.*...Mlab*amCCa.*.J4*.’)ffia,Tsp.Ih.clnn,I*141*LflgIh1———IaRsa.-t1*14Daa*4llt•41.tI.1t,ot.4Icl4e————aSItRp..pOF2p.sO4aapIt5.1C,a,n•52c41—.11001Ittx.e*o04.hp.ps.4.011.00..p’Ip.—IC=CflANIttfl<M1n144.1.6.4.44000.110_I20NMLOØ.r.44I0044100.44141Iqond024*11414,.00006.1144100.44244.__flSInOCC04fl.Tt*tSs.400a..hI.R1s50444—1flPP044141Pa00.0l-*o4104251.4%P.5.104*00440.244.40520%,a,b,rn,P...o5I,MIqs11a00.Sb10%041100411flsp,.p41.Ia.1.10101144004oadodolPQlada*1lMa’NM*140.0.24hIthOIIIosIflI44041411UtINbtON041.4.44[.nro14,fl.Cl00I010041+444.p.410a,CUWALLPROTECIIONSIZINGCd2WU0q52.4.YiOb611Ins..IkdnsidLccflscIeP.R.STRONGCONSULTINGENGINEERSS.WeawcRsaRlonRsflN4bt*lCE2VWEA%.4W4C043w7JCl3F4nW2C370EMERGENCYOWRFLOWSPILLWAYI—xc__-.IRI,Crn_I54WUPXKACCESSROADCROSSSECEON———!owtcwax1________________________________an.r-r‘3704’II(II‘70‘alA’fl!333.13JiN_____________________________________________________0+00+400+802+201+602+02+40SECEONA—ACRAb:CSCALEOIt20StIINCH2iFTHORIZONTALo2.55Lw!6R5J1IINCH=5Fr.VERTICAL00.0J-i.Jfl’icc0+400+80SECI7ONS—BRECOMMENDEDFORAPPOVALBY._________________Dale.BY:_______________________DY:_________________BY_______________I.—ALPINENURSERYO9.2L15PONDCROSSSECI1ONS&DETAILS01500736630’42DRSPRO&CTNO.14069IAizlfc]INAN SECTIONVCONVEYANCESYSTEMANALYSISANDDESIGNPerC.R.#4oftheKCSWDM,theconveyancesystemmustbeanalyzedanddesignedforexistingtributaryanddevelopedonsiterunofffromtheproposedproject.Pipesystemsshallbedesignedtoconveythe100-yeardesignstorm.TheRationalMethodwillbeusedtocalculatetheQ-Ratioforeachpipenode.AconveyancesystemconsistingprimarilyofpipesandcatchbasinshasbeendesignedfortheProject.Onsiterunoffwillbecollectedbythemultiplecatchbasins.Pipesaretypicallytwelve,eighteen,andtwenty-fourinchdiameterLCPEandDuctileIronmaterial.Thepipeswillhaveaminimumslopeof0.26%.TheproposedconveyancesystemwillmeetalloftherequirementssetforthbytheManual.KCBWCalculationsareincludedinthisSection.©2016D.R.STRONGconsultingEngineersInc.AlpineNurseryPage42TechnicalInformationReportcityofRenton BACKWATERANALYSISStormWaterRunoffVariables:AtTotalofSubasinandTribularyAreasRunoffCoefficient(theanticipatedproportionofrainfatvolunrthatrunsoffthearea)see2009KCSWMTable3.2.1ACc=ConpositeRunoffCoefficient;=S(CA,jIA1,TTimofConcentration,6.3niiutesatupstreamendandincreasedby[(lengthofpipe)/60VJforeachsubsequentreachR=designreftwnfrequencyUitpeakrainfallintenstyfactori=(a)(Tj(-b)a.b0=coefficientsfrom‘98KCSWMTable32.1.Busedtoadjusttheequationforthedesignstorm=akraifalluitensityfactorforastormofreturnfrequencyR=P1rtotalprecipitation(inches)forthe24-hourstormeventforthegh,enfrequency.SeesopluvialMapsin2009KCSWMRgses3.2.1.A-0Q=peakflow(cis)forastormofreturnfrequencyRQq=Cc*i*ATheQ-Ratiodescribestheratioofthetributaryflowtothen-ainupstreamflow.R100-yearstorma,=2.610.634inchesConveyanceSystemVariables:dpipediarreternManning’sNunterlengthofpipe02016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage43TechnicalInformationReportCityofRenton I0-QVBASINPIPECBtoCBAlClA2C2At—CcTcIRIRQrfcfs)ratiodMatinSlopeFinlEoutoverflowFuflFullBendLa——sfaBasinTotal.J!_.%ftftftcfs_cfsdeqreeDiaCB#13T0RIO131313hA219660.9324500.25544161.250.516.30.823.272.102.100.0012LCPE0.012430.52369.12368.9372.122.783.5402Run12-hA130420.9102330.25232750.53VIARunhA-h00.900.2500.00hAhA11130420.9102330.25232750.530.616.50.803.211.053.150.5012LCPE0.012480.50368.90368.66372.532.743.490411111110128930.991830.25220760.510.636.70.793.141.004.150.3212LCPE0.012812.05368.66367372.215.547.0502101010915920.900.2515920.040.906.90.773.090.104.260.0212LCPE0.012264.49367.00365.84370.008.2010.4402Run109-934140.98760.2542900.109Run9-800.900,2500.0099834140.98760.2542900.100.777.00,773.070.234.490.0518DI0.0121490.54365.34364.53370.348404.75904888774120.924250.2596370.230.747.50.732.940.494.980.1118Dl0.0121720.50364.53363.67367.036.074.560277766910.91830.258740.020.768.10.702.790.045.020.0118LCPE0.012370.48363.67363.49369.387.924.48454666527330.97680.2535010.080.766.30.692.760.175.190.0318LCPE0.012980.50363.49363369.508.084.57454Run205-5167640.968300.25255940.595Run54105530.996810.25202140.4655—427317018491025458081050M&6072.691.806.990.3516LOPE0.012260.42363.00362.89372.047.42420814Run404455580.919530.2576410.184Run4-300.900.2500.00414—35688OS195302576410.180.73810.67Z670.347.330.0518LOPE0.012370.51362.89362.7372.118.154.61694Run103-344510.915490.25:ëi”&::1.Run3-24040.900.254040.0133248550.915490.2564040.150.748.80.662,640.297.620.0424LCPE0.0122040.35362.70361.99372.7714.494.61814RunlO2-j_183850.9136670.25———2Run2-1166220.9142310.25308530.71221330080.9278960.25609061.400.609.60.632.512.129.740.2824LCPE0.012620.36361.99361.77368.1514.654.66334Run17141122OS468550.251i”Run1-81000.900.2500.001Ii—0106137305535760251149492.64—0.609.8ft622.48ao13.64OAO24LCPE0.012450.2636117361.65366.6812.654.0356.j_©2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage44TechnicalInformationReportCityofRenton -ia-IaVBASINPIPECBtoGBAlClA2C2—CclBOrcfs!s_jdMannSlopeEmlEoutoverflowFullFullBendCB——sf____j_BasinTotal‘inft%ftftdegree.—44’IE——!—216386OS137fQa300634Jar’*137aIfVL.rji!dE’i1orQ’tI344510907&i’TflI.O.rwri033————20520520510543820.94800.2546620.110.846.33.270.310.310.0012LCPE0.01228.8.00369.63367.4373.6310.9513.9402106105105512382098350025207320480646308232609913032512ICPE00123610753674036353724012.6916155252167640.988300.25255940.59068————4044044043049410.95150.2514560.030676.30.823.270.070.070.0012LCPE0.012880.50365.20364.76366.202.733.480230430430420414820.95150.2519970.050.736.70.793.140.110.181.4412LCPE0.012830.50364.76364.34368.652.753.503220420420410432650992302541880100767107630302204012312LCPE001237049364343641636921272346452..i:o4*ja4:::iibA’:400.900.2500.000257.30152.980.000.400012LCPE0.0121030.75364.16363.39369.513.354.2745456880919530257541018073——r—.:t:I—1091091091a:93414j—0250.250.00E1PE0.012JLt72———.——171717‘1624240‘03fl525:i\1nt07059tzat.2.060.00mgagixpa...0.012113100/”161616ISA4844.St4805&ãtv.9649.21ZL_jSL...2!jPIfi6.40247020PE0.012litiSAiSAISA1517313Sti9042056140386Q57d£dPEo.oiz-IRunlla___1225-“15Runl5j4__120009193j4lags—‘.15151424250.9493029:740142.960164.020.04wLOPE0.012256:e:.141414—10090jfl0004020001Dl0012IL‘r——•.,...‘.:.4.’v.&101101JQL—IX‘,‘•‘j.‘‘?/e115115JIL_..aa0.090.09a.oó’’Dl0.0120.51363.66163.59365.862.763.52Q/”CB#IATOPOND1A1A—PONDIA3555698.160.61I11.6I0.5612313.5713.570.0018LCPE0.01233152358.50358.361.0014.077.9602CB#I2TQCB#IIA121212—hA130420.910233025232750.530.61I6.3I0.823271.071.070.0012LCPE0.012110.55368.96368.9372.042883.6702ii-.,i3aaf#n.ir’ia::-‘r’p,vv“vpa..5M84070nIv368.367474231004364.606.543.7094J_“©20160.P.STRONGConsultingEngineersInc.TechnicalInformationReportPage45CityofRentonAlpineNursery FIGURE8BACKWATERANALYSISMAP©2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage46TechnicalInformationReportCityofRenton CQ@1flLLieck0)Ca-..cJtcri-LjAb.0CtNJOIThGRAPHICSCALE040801201INCH=80FT.DRAFTEDBYfl-PDESIGNEDDYtPPROJECTUqGWEED:MAJDATE:D&2715PROJECTNU:74059ncupt8R:\2Dr4\D\T4O59\3\orcwi1gS\PIDtS\RCPttFigires\O?—38M4069dw2J/7/20606:33FMPSTCCOI:5-r©205.RS1RQNGCONS’JUPNGENGINEERSNC BACKWATERANALYSISRESULTSBACKWATERCOMPUTERPROGRAMFORPIPESPipedatafromfiie:CB#lATOPONDINLET.bwpSurchargeconditionatintermediatejunctionsTailwaterElevation:357.feetDischargeRange:1.364to13.64Stepof1.364icfsiOverflowElevation:363.feetWeir:NONEUpstreamVelocity:0.feet/secPIPENO.1:31LF—18”CP81.61%OUTLET:358.00INLET:358.50INTYP:5Q(CFS)HW(FT)HWELEV.*N—FACDCDNTWDODEHWOHWI*******************************************************************************1.360.59359.09*0.0120.440.320.000.320.44***0.592.730.87359.37*0.0120.630.450.000.450.63*****0.874.091.12359.62*0.0120.780.550.000.550.78““1.125.461.36359.86*0.0120.910.640.000.640.91““1.366.821.60360.10*0.0121.020.730.000.731.021.608.181.84360.34*0.0121.110.810.000.811.11*****1.849.552.15360.65*0.0121.200.900.000.901.202.1510.912.51361.01*0.0121.270.980.000.981.272.5112.282.91361.41*0.0121.331.070.001.071.332.9113.643.36361.86*0.0121.381.160.001.161.383.36BACKWATERCOMPUTERPROGRAMFORPIPESPipedatafromfile:CB#13TOSWALEINLET.bwpSurchargeconditionatintermediatejunctionsTailwaterElevation:362.84feetDischargeRange:2.1to13.64Stepof1.154lcfsJOverflowElevation:372.12feetWeir:NONEUpstreamVelocity:0.feet/secPIPENO.1:45LF—24”CP80.26%OUTLET:361.65INLET:361.77INTYP:5JUNCNO.1:OVERFLOW—EL:366.68BEND:56DEGDIA/WIDTM:5.0Q—RATIO:0.40Q(CFS)HW(FT)MWELEV.*N—FACDCDNTWDODEI-iWOHWI2.101.11362.88*0.0120.510.561.191.191.081.110.683.251.16362.93*0.0120.640.701.191.191.081.160.874.411.24363.01*0.0120.740.821.191.191.091.241.025.561.33363.10*0.0120.840.931.191.191.111.331.176.721.44363.21*0.0120.921.041.191.191.131.441.317.871.56363.33*0.0121.001.151.191.191.171.561.449.021.68363.45*0.0121.081.261.191.191.221.681.5710.181.80363.57*0.0121.151.371.191.191.311.801.7011.331.93363.70*0.0121.211.491.191.211.411.931.8212.492.05363.82*0.0121.281.631.191.281.492.051.9513.642.17363.94*0.0121.342.001.191.341.572.172.0802016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage47TechnicalInformationReportCityofRenton PIPENO.2:61LF—24”CP60.36%OUTLET:361.77INLET:361.99INTYP:5JUNCNO.2:OVERFLOW—EL:368,15BEND:33DEGDIA/WIDTH:4.0Q—RATIO:0.28Q(CFS)HW(fl)MWELEV.N—FACDCONTWDODEHWOMW:***t*************t*tt****.********L530.93362.92*0.0120.430.441.111.110.900.930.572.321.01363.00*0.0120.530.541.161.160.951.010.723.151.11363.10*0.0120.620.641.241.241.031.110.843.971.23363.22*0.0120.700.721.331.331.131.230.964.791.36363.350.0120.780.791.441.441.241.361.065.621.49363.48*0.0120.840.871.561.561.361.491.166.441.62363.61*0.0120.900.931.681.681.491.621.267.271.76363.75*0.0120.961.001.801.801.621.761.358.091.90363.89*0.0121.021.071.931.931.761.901.448.912.05364.040.0121.071.132.052.031.902.051.539.742.22364.210.0121.121.202.172.172.052.221.61PIPENO.3:204LF—24’CP60.35%OUTLET:361.99INLET:362.70INTYP:5JUNCNO.3:OVERFLOW—EL:372.77BEND:81DEGDIA/WIDTH:4.0Q—RATIO:0.04Q(CFS)HW(FT)NWELEV.N—FACDCONTWDOOSNWONWI1.170.56363.26*0.0123.380.390.930.930.420.560.501.820.71363.41*0.0120.470.481.011.010.510.710.632.460.83363.53*0.0220.550.561.211.120.590.630.753.110.94363.64*0.0120.620.631.231.230.690.940.853.751.04363.74*0.0120.680.701.361.360.791.040.954.401.15363.85*0.0120.740.761.491.490.901.151.045.041.26363.96*0.0120.800.821.621.621.021.261.125.691.39364.09*0.0120.850.881.761.761.161.391.216.331.53364.230.0120.900.931.931.901.311.531.296.981.70364.40*0.0123.940.982.052.051.491.701.377.621.89364.59*0.0120.991.042.222.221.691.891.45PIPENO.4:37LF—18”CP@0.51%OUTLET:362.70INLET:362.89INTYP:5JUNCNO.4:OVERFLOW—EL:372.11BEND:69DEGDIA/WIDTH:4.0Q—RATIO:0.05Q(CFS)HW(FT)NWELEV.*N—FACDCONTWDOOSHWOHWI*******************************************************************************1.130.54363.43•0.0120.400.380.560.560.400.541.750.76363.650.0120.500.480.710.710.510.760.682.370.89363.780.0120.590.560.830.830.640.890.812.991.01363.900.0120.660.630.943.940.761.010.933.611.13364.02*0.0120.730.711.041.040.871.131.044.231.25364.14*0.0120.790.771.151.150.991.251.144.851.37364.26*0.0120.850.841.261.261.111.371.255.471.52364.41*0.0120.910.911.391.391.261.521.356.091.70364.59•0.0120.960.971.531.531.441.701.455.711.95364.84*0.0:22.011.041.701.702.642.952.567.332.23365.120.0121.051.121.891.891.862.231.66©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage48TechnicalInformationReportCityofRenton PIPENO.5:26LF—18”CP@0.42%OUTLET:362.89INLET:363.00INTYP:5JUNCNO.5:OVERFLOW—EL:372.04BEND:81DEGDIA/WIDTE:4.0Q—RATIO:0.35Q(CFS)NW(FT)NWELEV.*N—FACDCDNTWDOOSHWOHWI*********************************************************************##********1.080.59363.59*0.0120.390.390.540.540.440.590.531.670.78363.78*0.0120.490.490.760.760.660.780.672.260.93363.93+0.0123.570.570.890.890.790.930.802.851.07364.07*0.0120.650.651.011.010.921.070.913.441.21364.21*0.0120.710.721.131.131.041.211.034.031.35364.35*0.0120.770.791.251.251.161.351.144.621.51364.51*0.0120.830.861.371.371.301.511.245.221.69364.69*0.0120.880.931.521.521.461.691.355.811.94364.94*0.0120.341.011.701.701.661.941.466.402.26365.26*0.0120.981.081.951.951.922.261.576.992.62365.62*0.0121.031.172.232.232.212.621.68PIPENO.6:97LF—18’CP@0.50%OUTLET:363.00INLET:363.49INTYP:5JUNCNO.6:OVERFLOW—EL:369.50BEND;45058DIA/WIOTE:4.0Q—RATIO:0.03Q(CFS)NW(FT)NWELEV.*N—FACDCONTWDODEHWONWI*********************************************************************4*4******+0.800.45363.94*0.0120.340.320.590.590.340.451.240.56364.05*0.0120.420.400.780.780.42““0.561.680.74364.23*0.0120.490.470.930.930.510.740.662.110.83364.32*0.0120.550.531.071.070.630.830.752.550.93364.42*0.0120.610.591.211.210.760.930.832.991.05364.54*0.0120.660.641.351.350.911.050.913.431.20364.69*0.0120.710.691.511.511.091.200.983.871.39364.88*0.0120.760.741.691.691.301.391.054.311.69365.18*0.0120.800.791.941.941.601.691.124.752.05365.54*0.0120.840.832.262.261.942.051.185.192.46365.95*0.0120.880.882.622.622.342.461.25PIPENO.7;37LF—18”CP@0.48%OUTLET:363.49INLET:363.67INTYP:5JUNONO.7:OVERFLOW—EL:369.38BEND:45OEGOIA/WIDTH:4.0Q—RATIO;0.01Q(OFS)HW(FT)NWELEV.*N—FACDCONTW00DEHWOHWI0.770.44364.11*0.0120.330.320.450.450.330.441.200.55364.22*0.0120.410.400.560.560.41““0.551.620.72364.39*0.0120.480.470.740.740.560.720.652.050.82364.49*0.0120.540.530.630.830.650.820.742.470.92364.59*0.0120.600.580.930.930.760.920.822.901.02364.69*3.0120.650.631.051.050.881.020.893.321.16364.83*0.0120.700.661.201.201.041.160.963.741.33365.00*0.0120.740.731.391.391.241.331.034.171.64365.31*0.0120.790.781.691.691.561.641.094.592.03365.70*0.0120.830.832.052.051.932.031.165.022.47366.14*0.0120.870.872.462.462.362.471.22020160.R.STRONGConsultingEngineersInc.AlpineNurseryPage49TechnicalInformationReportCityofRenton PIPENO.8:JUNCNO.8:172LF—18”CP80.50%OUTLET:OVERFLOW—EL:367.03BEND:0DEG363.67INLET:364.53INTYP:5DIA/WIDTH:2.0Q—RATIO:0.11Page50CityofRentonQ(CFS)HW(rr)MWELEV.N—FACDCONTWDODEHWOEWI*****0.770.44364.970.0120.330.320.440.440.330.441.190.55365.03*0.0120.410.390.553.550.41““0.551.610.64365.17*0.0120.480.460.720.720.48““0.642.030.73365.26*0.0120.540.520.820.820.54*****0.732.450.81365.34*0.0120.600.570.920.920.60*****0.812.870.88365.41*0.0120.650.621.021.020.65““0.883.290.95365.48*0.0120.700.671.161.160.70*****0.953.711.01365.54*0.0120.740.721.331.330.74*****1.014.131.19365.72*0.0120.780.771.641.641.001.191.084.551.52366.05*0.0120.820.812.032.031.431.521.144.972.03366.580.0120.860.862.472.471.952.051.19PIPENO.9:149LF—18”CP@0.54%OUTLET:364.53INLET:365.34INTYP:5JUNCNC.9:OVERFLOW—EL:370.34BEND:90DEGDIA/WIDTH:4.0Q—RMIO:0.05Q(CFS)HW(FT)MWELEV.*N—FACDCDNTWDODEHWOHWI**************************&****************************************************0.690.42365.76*0.0120.310.300.440.440.31***0.421.070.53365.87*0.0120.390.370.550.550.39*****0.531.450.63365.97*0.0120.460.430.640.640.46““0.631.830.73366.07*0.0120.510.480.730.730.510.732.210.82366.16*0.0120.570.530.810.810.570.822.590.91366.25*0.0120.610.580.880.880.61““0.912.971.00366.34*0.0120.660.620.930.950.66*****1.003.351.09366.43*0.0120.700.661.011.010.70*****1.093.731.16366.52*0.0120.740.711.191.190.741.184.111.36366.70*0.0120.780.751.521.520.891.361.274.481.78367.12*0.0:20.820.792.052.051.461.781.37PIPENO.10:JUNCNO.10:Q(CFS)HW(FT)MWELEV.*N—FACDCDN************************************************25LF—12”CP84.49%OUTLET:365.84INLET:367.00INTYP:5OVERFLOW—EL:370.00BEND:0DEGDIA/WIDTH:2.0Q—RATIO:0.020.651.011.37L732.092.452.813.173.533.894.250.430.550.650.740.830.930.581.071.171.281.40367.43367.55367.65367.74367.83367.90367.58368.07368.17368.28368.40*0.012*0.0120.0120.0120.0120.012*0.012*0.012*0.012*0.012*0.0120.340.430.500.570.620.680.720.770.810.840.870.200.240.280.320.350.380.410.440.460.450.52TWDODEMWO*******************0.000.200.340.030.240.430.130.280.500.230.320.570.320.350.620.410.410.680.500.500.720.590.590.77”*0.680.680.81““0.860.860.84*****1.281.280.87HWI****0.430.550.650.740.830.930.981.071.171.281.40©2018D.R.STRONGConsultingEngineersInc.TechnicalInformationReportAlpineNursery PIPENO.11:80LF—12”CP@2.05%OUTLET:367.00INLET:368.66INTYP:5JUNCNO.11:OVERFLOW—EL:372.21BEND:0DEGD:A/WIDTH:2.0Q—RATIO:0.32Q(CFS)HW(FT)NWELEV.*N—FACDCDNTWDODEHWOHWI*0.640.43369.11*0.0120.340.230.43Q410.34**n0.450.990.57369.23*0.0120.420.2%0.550.550.42““0.571.340.68369.34*0.0120.490.340.650.650.49““0.681.690.78369.44*0.0120.560.380.740.740.560.782.040.88369.54*0.0120.620.430.830.830.620.882.390.97369.63*0.0120.670.470.900.900.67*****0.972.731.07369.73*0.0120.720.500.980.980.721.073.101.17369.83*0.0120.760.541.071.070.76*****1.173.451.30369.96*0.0120.800.581.171.170.80““1.303.801.43370.09*0.0120.830.611.281.280.83***1.434.151.56370.240.0120.870.651.401.400.87““1.58PIPENO.12:47LF—12”CP30.50%OUTLET:368.66:NLET:369.90INTYP:5JUNCNO.12:OVERFLOW—EL:372.33BEND:0DEGDIA/WIDTH:4.0Q—RATIO:0.50Q(CFS)HW(FT)NWELEV.*N—FACDCONTWDODEHWOHWI*******************************************************************************0.480.44369.34*0.0120.290.290.450.450.290.440.390.750.55369.45*0.0120.370.360.570.570.380.550.501.020.65369.55*0.0120.430.430.680.680.480.650.591.280.74369.64*0.0120.480.490.780.780.580.740.681.550.84369.74*0.0120.530.540.880.880.690.840.761.820.95369.85*0.0120.580.600.970.970.810.930.842.081.10370.00*0.0120.520.661.071.070.961.100.912.351.23370.18*0.0120.660.721.171.171.111.280.992.621.49370.39*0.0120.700.731.301.301.281.491.072.881.71370.61*0.0120.730.881.431.432.461.712.143.151.97370.87*0.0120.771.001.581.581.661.971.24PIPENO.13:42LF—12”CP00.52%OUTLET:368.90INLET:369.12INTYP:5Q(CFS)HW(FT)NWELEV.*N—FACDCONTNDODEHWOHWI*****************************************************************************0.320.35369.47*0.0120.240.240.440.440.260.350.320.500.45369.57*0.0120.300.290.350.550.350.450.400.680.54369.66*0.0120.350.340.650.650.440.540.470.650.63369.73*0.0120.390.390.740.740.540.630.541.030.73369.83*0.0120.430.430.840.840.640.730.601.210.84369.960.0120.470.470.950.950.760.840.661.391.01370.130.0120.500.501.101.100.931.010.721.561.22370.340.0:20.540.341.281.281.131.220.781.741.47370.590.0120.570.581.451.491.351.470.841.921.74370.86*0.0120.600.621.711.711.601.740.892.102.04371.16*0.0120.620.651.971.971.872.040.9502018D.R.STRONGConsultingEngineersInc.AlpineNurseryPage51TechnicalInformationReportCityofRenton BACKWATERCOMPUTERPROGRAMFORPIPESPipedatafromfile:CBU7TOCBfl.bwpSurchargeconditionatintermediatejunctionsTailwaterElevation:363.94feetDischargeRange:2.06to4.02Stepof0.19€[cfsOverflowElevation:377.51feetWeirNONEUpstreamVelocity:0.feet/secPIPENO.1:JUNCNO.1:70LF—18”CP80.33%OUTLET:361.77iNLET:362.00INTY?:5OVERFLOW—EL:364.50BEND:90DEGDIA/WIDTN:2.0Q—RATIO:0.000.582.172.171.970.612.172.171.970.642.172.171.970.672.172.171.980.702.172.171.980.722.172.171.990.752.172.172.000.782.172.172.000.802.172.172.010.832.172.172.020.862.172.172.032.010.762.310.802.030.842.040.882.060.922.070.962.091.002.111.032.131.072.151.112.171.15PIPENC.2:254LF—18”CP@0.43%OUTLET:JUNCNO.2:OVERFLOW—EL:368.36BEND:90DEG362.00INLET:363.09INTYP:50Th/WIDTH:4.0Q—RATIO:0.04PIPENO.3:JUNCNO.3:52LF—12”CP@2.69%OUTLET:OVERFLOW—EL:369.99BEND:0DEG363.59INLET:364.99INTYP:5DIA/WIDTH:2.0Q—RATIO:0.57Q(CFS)HW(FT)NWELEV.*N—FACDCONTWDODEHWOHWI***********************,4*****************************************************1.980.88365.87*0.0120.610.390.610.610.61““0.882.170.93365.52*0.0120.630.410.640.640.63““0.932.360.99365.58*0.3120.660.430.690.690.66“0.992.541.04366.03*0.3120.690.450.730.730.69“1.342.731.09366.08*0.0120.710.460.790.790.71*****1.092.921.15366.14*0.0120.740.480.840.840.741.153.111.21366.23*0.0120.760.500.890.890.76*****1.213.301.29366.28*0.0120.780.520.950.950.78“‘“1.293.491.36366.350.0120.800.531.011.010.80*****1.363.671.44366.43*0.0120.820.551.071.070.82***w*1.443.851.53366.520.0120.840.571.241.140.84**fl*1.53Q(CFSHW(FT)NWELEV.*N—FACDCONTWDODEEWOHWI*******************************************************************************2.062.01364.01*0.0120.552.262.01364.01*0.0120.572.452.03364.03*0.0120.602.652.04364.04*0.0120.622.842.06364.06*0.0120.653.042.07364.07*0.0120.673.242.09364.09*0.0120.693.432.11364.11*0.0120.713.632.13364.13*0.0120.733.822.15354.15*0.0120.754.022.17364.17*0.0120.77Q(CFS)HW(rr)NWELEV.*N—FACDCONTWDODEEWONW********************************************************************2.0€1.11354.200.0120.550.542.012.011.011.110.792.261.14354.23*0.0120.570.572.012.011.031.140.832.451.19364.28÷0.0120.600.602.032.031.061.190.882.651.23364.32*0.0120.620.622.042.341.091.230.932.841.29364.38*0.0120.650.652.062.061.131.290.973.041.34364.43*0.0120.670.672.072.071.161.341.023.241.39364.48*0.0120.690.702.092.091.201.391.063.431.45364.54*0.0120.710.722.112.111.241.451.113.631.51364.60*0.0120.730.742.132.131.281.511.163.821.57364.66*0.0120.750.772.152.151.331.571.204.021.64364.73*0.0120.770.792.172.171.381.641.2502016D.R.STRONGConsultingEngineersInc.TechnicalInformationReportAlpineNurseryPage52CityofRenton 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BACKWATERCOMPUTERPROGRAMFORPIPESPipedatafromfile:C8ff109TOCB#9.bwpSurchargeconditionatintermediatejunctionsTailwaterElevation:367.12feetDischargeRange:O.025to0.25Stepof0.025(cfsJOverflowElevation:370.33feetWeir:NONEUpstreamVelocity:0.feet/secPIPENO.1:86LF—12CP@1.72%OUTLET:365.84INLET:367.33INTYP:5Q(CFS)NW(FT)MWELEV.*N—FACDCONTWDODEHWOHWI0.030.08367.41*0.0120.070.061.261.280.070.080.050.11367.44*0.0120.100.081.281.280.10*fl0.110.080.14367.47*0.0123.120.091.281.280.12““0.140.100.16367.49*0.0120.130.131.281.280.13nn0.160.130.15367.520.0120.150.111.281.280.10.190.150.20367.53*0.0120.160.121.281.280.16““0.200.180.22367.55*0.0120.180.131.281.280.18““0.220.200.24367.57*0.0120.190.141.281.280.190.240.230.26367.59*0.0120.200.151.281.280.200.260.250.27367.60*0.0120.210.161.281.280.21““0.27BACKWATERCOMPGTERPROGRAMFORPIPESPipedatafromfile:CB#115TOCB15.bwpSurchargeconditionatintermediatejunctionsTailwaterElevation:364.73feetDischargeRange:0.01to0.09Stepof0.01[cfslOverflowElevation:365.86feetWeir:NONEUpstreamVelocity:0.feet/secPIPENO.1:53LF—12CP80.51%OUTLET:363.59INLET:363.86INTYP:5Q(CFS)HW(fl)MWELEV.N—FACDCONTWDODEHWOHWI*,,w*t***0.010.88364.740.0120.050.051.141.140.880.880.050.020.88364.74*0.0120.060.071.41.143.880.880.070.030.68364.74*0.0120.080.081.141.140.880.880.090.040.88364.74*0.0120.090.091.141.140.880.880.110.050.88364.74*0.0120.100.101.141.140.880.880.120.060.88364.74*0.0120.100.111.141.140.880.880.130.070.88364.74*0.0120.110.111.141.140.880.880.140.080.88364.74*0.0123.120.121.141.140.880.880.150.090.88364.74*0.0120.130.131.141.140.880.880.160.100.88364.74*0.0120.130.141.141.140.880.880.17.@20160.R.STRONGConsulting8ngineersInc.AlpineNurseryPage55TechnicalInformationReportCityofRenton PACKWATERCOMPUTERPROGRAMFORPIPES•Pipedatafromfile:CBê2O5TOCB#5.bwpSurchargeconditionatintermediatejunctionsTailwaterElevation:365.62feetDischargeRange:0.31to1.3Stepof0.099[cfsjOverflowElevation:373.63feetWeir:NONEUpstreamVelocity:O.feet/secPIPENO.1:36LF—12”CP@10.75%OUTLET:363.50INLET:367.40INTYP:5JUNCNO.1:OVERFLOW—EL:372.40BEND:52DEGDIA/WIDTH:2.0Q—RATIO:3.25Q(CFS)MW(FT)MWELEV.*N—FACDCDNTWDODEMWOHWI*******************************************************************************0.310.26367.66*0.0120.230.112.122.120.23*****0.260.410.31367.71*0.0120.270.132.122.120.27““0.310.510.33367.75*0.0120.300.142.122.120.30*****0.350.610.39367.79*0.0120.330.152.122.120.33*****0.390.710.43367.83*0.0120.360.172.122.120.360.430.800.47367.87*0.0120.380.182.122.120.38““0.470.900.51367.91*0.0120.400.192.122.120.400.511.000.34367.94*0.0120.430.202.122.120.430.541.100.58367.98*0.0120.450.202.122.120.450.581.200.61368.01*0.0120.470.212.122.120.470.611.300.64368.04*0.0120.490.222.122.120.490.641.300.64368.04*0.0120.490.222.122.120.490.64PIPENO.2:27LF—12”CP88.00%OUTLET:367.40INLET:369.63INTYP:5Q(CFS)HW(FT)MWELEV.*N—FACDCONTWDODEHWOHWI*******************************************************************************0.070.11369.74*0.0120.110.060.260.260.11““0.110.100.13369.76*0.0120.130.070.310.310.130.130.120.13369.78*0.0120.150.060.350.350.130.150.140.17369.80*0.0120.160.090.390.390.16*****0.170.170.19369.82*0.0120.170.090.430.430.17*****0.190.190.20369.83*0.0120.180.100.470.470.18*****0.200.210.22369.85*0.0120.190.100.510.310.19*****0.220.240.23369.86*0.0120.200.110.340.340.20*****0.230.260.24369.87*0.0120.210.110.580.580.21““0.240.280.26369.89*0.0120.220.120.610.610.220.260.310.27369.90*0.0120.230.120.640.640.23*****0.270.310.27369.90*0.0120.230.120.640.640.230.27©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage56TechnicalInformationReportCityofRenton BACKWATERCOMPUTERPROGRAMFORPIPESPipedatafromfi1e:CB404TOCB*4.bwpSurchargeconditionatintermediatejunctionsTailwaterEievation:365.12feetDischargeRange:0.07to0.4Stepof0.033[cfsjOverflowElevation:368.2feetWeir:NONEUpstreamVelocity:O.feet/sec020160.R.STRONGConsultingEngineersInc.TechnicalInformationReportPIPENO.1:1Q2LF—12”CP@0.75%OUTLET:363.39INLET:364.16INTYP:5JUNCNO.1:OVERFLOW—EL:369.51BEND:45DECDIA/WIDTH:4.00—RATIO:0.00O(CFS)HW(rr)HWELEV.*N—FACDCDNTWDODEHWOHWI***.*t*-,0.970.140.970.170.970.200.970.220.970.250.970.260.970.28D.970.300.970.320.970.340.9%0.350.9%0.370.070.97365.13*0.0120.110.111.731.730.970.100.97365.13*0.0120.140.131.731.730.970.140.97365.130.0120.160.141.731.730.970.170.97365.13*0.0120.170.161.731.730.970.200.97365.13*0.0120.190.171.731.730.970.230.97365.13*0.0120.200.181.731.730.970.270.97365.13*0.0120.220.201.731.730.970.300.97365.13*0.0120.230.211.731.730.970.330.97365.13*0.0120.240.221.731.730.970.370.97365.13•0.0120.260.231.731.730.970.400.98365.14*0.0120.270.241.731.730.980.430.98365.14*0.0120.280.251.731.730.98PIPENO.2:36:F—12”CP80.49%OUTLET:JUNCNO.2:OVERFLOW—EL:369.21BEND:45DECQ(CFS)HW(FT)11WELEV.*N—FACDC************************************************364.16INLET:364.34INTYP:5DIA/WIDTH:2.0Q—RATIO:1.23DNTWDODE******************0.070.100.140.170.200.230.270.300.330.370.400.430.800.800.800.800.800.800.800.800.810.810.820.82365.14365.14365.14365.14365.14365.14365.14365.14365.15365.15365.16365.16*0.012*0.012*0.012*0.012*0.012*0.0:2*0.012*0.012*0.012*0.012*0.012*0.0120.110.140.160.170.190.200.220.230.240.260.270.280.120.140.160.170.190.200.220.230.240.250.260.280.970.970.970.970.970.970.970.970.970.970.970.970.970.970.970.970.970.970.970.970.980.980.980.980.800.800.800.800.830.830.800.800.800.800.810.81I-iWOHWI*************0.800.140.800.170.800.200.800.220.800.250.800.270.800.290.800.300.810.320.810.340.820.360.820.37AlpineNurseryPage57CityofRenton BACKWATERCOMPUTERPROGRAMFORPIPESPipedatafromfi1e:CB12TOCB#11A.bwpSurchargeconditionatintermediatejunctionsTailwaterElevation:370.87feetDischargeRange:O.107to1.07Stepof0.107OverflowElevation:372.04feetWeir:NONEUpstreamVelocity:0.feet/sec(cfsJPIPENO.1:10LF—12”CP@0.55%OUTLET:368.90Q(CFS)Hwfrr)ENELEV.N—FACDCONTW*************0.111.92370.880.0120.140.141.970.211.91370.87*0.0120.190.191.970.321.91370.87*0.0120.240.231.970.431.92370.88*0.0120.280.271.970.541.92370.88*0.0120.310.301.970.641.93370.89*0.0120.340.331.970.751.94370.90*0.0120.370.351.970.661.94370.90*0.0120.390.331.970.961.95370.91*0.0120.420.401.571.071.96370.92*0.0120.440.431.97INLET:368.96INTYP:5DODEEWOHW:1.971.921.920.181.971.911.910.251.971.911.910.321.971.911.920.371.971.911.920.421.971.911.930.461.971.911.940.501.971.921.940.541.971.921.950.581.971.921.960.62.PIPENO.3:83LF—12’CP60.50%OUTLET:364.34INLET:364.76INTYP:5JUNCNO.3:OVERFLOW—EL:368.65BEND:3DEGDIA/WIDTH:2.0Q—RATIO:1.44Q(CFS)HW(FT)8WELEV.*N—SACDCONTNDODEHWOHWI*******************************************************************************0.030.39365.15*0.0120.080.080.800.800.390.390.100.050.39365.15*0.0120.090.100.800.800.390.390.110.060.39365.150.0120.110.110.800.800.390.390.130.080.39365.150.0120.120.120.600.800.390.390.150.090.39365.150.0120.130.130.800.600.390.390.1€0.110.39365.150.0120.140.140.800.800.390.390.160.120.39365.15*0.0120.150.150.800.600.390.390.190.130.40365.160.0120.160.160.800.800.390.400.200.150.40365.16*0.0120.160.160.810.810.390.400.210.160.41365.17*0.0120.170.170.810.810.400.410.220.180.42365.18*0.0120.180.180.820.820.410.420.230.190.42365.18*0.0120.190.190.820.820.410.420.24INLET:365.20INTYP:5DOOSHWOHWI**,,**.-***,(**,-**wfl*PIPENO.4:88LF—12”CP80.50%OUTLET:364.76Q(CFS)HW(n)HWELEV.*N—FACDCONTN***.**************rtt*******.0.010.07365.27*0.0120.050.050.390.390.060.070.060.020.08365.28*0.0120.060.060.390.390.070.080.070.020.10365.30*0.0120.070.070.390.390.080.100.080.030.11365.31*0.0120.080.080.390.390.090.110.090.040.12365.32*0.0120.080.090.390.390.090.120.100.040.13365.33*0.0120.090.090.390.390.100.130.110.050.13365.33*0.0120.100.100.390.390.100.130.120.060.14365.34*0.0120.100.100.400.400.110.140.130.060.15365.35*0.0120.110.110.400.400.110.150.130.070.16365.36*0.0120.110.110.410.410.120.160.140.070.16365.36*0.0120.120.120.420.420.130.160.150.080.17365.37*0.0120.120.120.420.420.130.170.15020160.R.STRONGConsultingEngineersInc.TechnicalInformationReportAlpineNurseryPage58CityofRenton SECTIONVISPECIALREPORTSANDSTUDIESThefollowingreportandstudieshavebeenprovidedwiththissubmittal.1.WetlandEvaluation—Re-AlignEnvironmentalJanuary4,20152.TrafficImpactAnalysis—TraffEx,Inc.,December31120143.GeotechnicalEngineeringStudy—EarthSolutionsNWLLC,June5,20144.InfiltrationEvaluation—EarthSolutionsNWLLC,January9,20155.ArboristReport—GreenForest,Inc.,January5,20156.SchoolWalkwayAnalysis—D.R.StrongConsultingEngineers,Inc.December30,2014©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage59TechnicalInformationReportCityofRenton SECTIONVIIOTHERPERMITS,VARIANCESANDADJUSTMENTS1.StreetmodificationforSE145thPlaceandl6O’AvenueSE2.ConstructionStormwaterGeneralPermit-WSDOE©2016D.R.STRONGConsullingEngineersInc.AlpineNurseryPage60TechnicalInformationReportCityofRenton •SECTIONVIIIESCPLANANALYSISANDDESIGN(PARTA)TheErosionandSedimentationControlDesignmeetsthenineminimumrequirements:1.ClearingLimits—Areastoremainundisturbedshallbedelineatedwithahigh-visibilityplasticfencepriortoanySiteclearingorgrading.2.CoverMeasures—DisturbedSiteareasshallbecoveredwithmulchandseeded,asappropriate,fortemporaryorpermanentmeasures.3.Perimeterprotection—Perimeterprotectionshallconsistofasiltfencedownslopeofanydisturbedareasorstockpiles.4.TrafficAreaStabilization—Astabilizedconstructionentrancewillbelocatedatthepointofingresslegress.5.SedimentRetention—SurfacewatercollectedfromdisturbedareasoftheSiteshallberoutedthroughasedimentvaultorsedimenttrapspriortoreleasefromtheSite.Thetrapswillbeinstalledpriortogradingofanycontributingarea.6.SurfaceWaterControl—Interceptorbermsorswalesshallbeinstalledtocontrolandinterceptallsurfacewaterfromdisturbedareas.Surfacewatercontrolsshallbeinstalledconcurrentlywithandlorimmediatelyfollowingroughgrading.7.DewateringControl—Willbeprovidedasneeded.8.DustControl—Dustcontrolshallbeprovidedbysprayingexposedsoilswithwateruntilwet.Thisisrequiredwhenexposedsoilsaredrytothepointthatwindtransportispossiblewhichwouldimpactroadways,drainageways,surfacewaters,orneighboringresidences.9.FlowControl—Flowcontrolwillbeprovidedbysedimenttrapsduringconstruction.InfiltrationFacilityProtectionandConstructionProtectionfromupstreamerosionErosionmustbecontrolledduringconstructionofareasupstreamofinfiltrationfacilitiessincesedimentladenrunoffcanpermanentlyimpairthefunctioningofthesystem.Erosioncontrolmeasuresmustbedesigned,installedandmaintainedwithgreatcare.Variousstrategiesmaybeemployedtoprotectinfiltrationfacilitiesduringconstruction,asdescribedbelow.Projectsmaybephasedtolimitclearingandminimizethetimethatsoilsareexposed.Analternativetothisapproachistoservetheundevelopedareawithalargesedimenttraponanundevelopedtractwiththetrapleftinplaceuntilallclearingandconstructioniscompleteandallpermanentlandscapingisinplace.Atthecompletionofallconstruction,thesedimenttrapmustbecleanedout(takingcarethatnosedimententersthedrainagesystem)andfilledin,andtheflowroutedtothepermanentdrainagesystem.020160.R.STRONGconsultingEngineersInc.AlpineNurseryPage61TechnicalInformationReportcityofRenton Anotheralternativeforsubdivisionsistostageexcavationofthepondasfollows:1.Bottomelevationofthepondpriortopavingofplatroadways:3feetabovethefinalpondbottomelevation.Atthisstageofroughgrading,thefacilitymaybeusedtomeetsedimentretentionrequirements.2.Bottomelevationofthepondduringandafterpavingandpriortoconstructionof80%ofthehouses:18inchesabovethefinalpondbottomelevationwithupstreamsedimentretention,asneeded.Atthisstage,thepondwillserveasaninterimflowcontrolfacilitypendingfinalstabilizationofthesite.NotethatKCC9.04.090requiresthatflowcontrolfacilitiesbeoperationalpriortotheconstructionofanyimprovements.FacilityconstructionguidelinesExcavationofinfiltrationfacilitiesshouldbedonewithabackhoeworkingat‘armslengthtominimizedisturbanceandcompactionofthecompletedinfiltrationsurface.Ifthebottomofthefacilitywillbelessthanthreefeetbelowfinalgrade,thefacilityareashouldbecordonedoffsothatconstructiontrafficdoesnottraversethearea.Theexposedsoilshouldbeinspectedbyasoilsengineerafterexcavationtoconfirmthatsoilconditionsaresuitable.Twosimplestaffgagesformeasuringsedimentdepthshouldbeinstalledatoppositeendsofthebottomofponds.Thegagesmayconsistof1-inchpipedrivenatleastonefootintothesoilinthebottomofthepond,with12inchesofthepipeprotrudingabovegrade.©2016U.R.STRONGconsultingEngineersInc.AlpineNurseryPage62TechnicalInformationReportcityofRenton SWPPSPLANDESIGN(PARTB)Constructionactivitiesthatcouldcontributepollutantstosurfaceandstormwaterincludethefollowing,withapplicableBMP’slistedforeachitem:1.Storageanduseofchemicals:Utilizesourcecontrol,andsoilerosionandsedimentationcontrolpractices,suchasusingonlyrecommendedamountsofchemicalmaterialsappliedinthepropermanner;neutralizingconcretewashwater,anddisposingofexcessconcretematerialonlyinareaspreparedforconcreteplacement,orreturntobatchplant;disposingofwash-upwatersfromwater-basedpaintsinsanitarysewer;disposingofwastesfromoil-basedpaints,solvents,thinners,andmineralspiritsonlythroughalicensedwastemanagementfirm,ortreatment,storage,anddisposal(TSD)facility.2.Materialdeliveryandstorage:Locatetemporarystorageareasawayfromvehiculartraffic,neartheconstructionentrance,andawayfromstormdrains.MaterialSafetyDataSheets(MSDS)shouldbesuppliedforallmaterialsstored,andchemicalskeptintheiroriginallabeledcontainers.Maintenance,fueling,andrepairofheavyequipmentandvehiclesshallbeconductedusingspillpreventionandcontrolmeasures.Contaminatedsurfacesshallbecleanedimmediatelyfollowinganyspillincident.Providecover,containment,andprotectionfromvandalismforallchemicals,liquidproducts,petroleumproducts,andotherpotentiallyhazardousmaterials.3.Buildingdemolition:Protectstormwaterdrainagesystemfromsediment-ladenrunoffandlooseparticles.Totheextentpossible,usedikes,berms,orothermethodstoprotectoverlanddischargepathsfromrunoff.Streetgutter,sidewalks,driveways,andotherpavedsurfacesintheimmediateareaofdemolitionmustbesweptdailytocollectandproperlydisposeofloosedebrisandgarbage.Spraytheminimumamountofwatertohelpcontrolwindblownfineparticlessuchasconcrete,dust,andpaintchips.AvoidexcessivesprayingsothatrunofffromtheSitedoesnotoccur,yetdustcontrolisachieved.Oilsmustneverbeusedfordustcontrol.4.Sawcuffing:Slurryandcuttingsshallbevacuumedduringtheactivitytopreventmigrationoffsiteandmustnotremainonpermanentconcreteorasphaltpavingovernight.Collectedslurryandcuttingsshallbedisposedofinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.ThecompleteCSWPPPcanbefoundinAppendixCofthisreport.Thesiteplanscanbefoundintheengineeringplanset.020160.R.STRONGConsultingEngineersInc.AlpineNurseryPage63TechnicalInformationReportcityofRenton SECTIONIXBONDQUANTITIES,FACILITYSUMMARIES,ANDDECLARATIONOFCOVENANT1.BondQuantityWorksheet—attachedinAppendixD2.TheStormwaterFacilitySummarySheetisincludedinthissection@20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage64TechnicalInformationReportCityofRenton STORMWATERFACILITYSUMMARYSHEETDevelopment.AmineNurseryDateAugust27,2015Location16023SE144thiStreetWashingtonand14609114625161stAvenueSE.Renton.ENGINEERDEVELOPERNameMaherA.Joudi,P.E.NameRoyBoyerFirmD.R.STRONGConsultingFirmEngineers,_Inc.Address6207thAvenueAddress14609161stAveSEKirkland,WA98033Renton,WA98059Phone(425)827-3063Phone(425)766-3066DevelopedSite:8.953acresNumberoflots27NumberofdetentionfacilitiesonSite:NumberofinfiltrationfacilitiesonSite:vaultsvaultspondIpondtankstanksFlowcontrolprovidedinregionalfacility(givelocation)_____________________________________Noflowcontrolrequired_____ExemptionnumberDownstreamDrainageBasinsImmediateMajorBasinBasinLowerCedarRiverCedarRiverNumber&typeofwaterqualityfacilitiesonIbiofiltrationswale(regular/wet!or___ ___ _sandfilter(basicorlarge?)___ ___ _large?)_ _ _ __________combineddetentioniWQvault___ ___ ______combineddetention/wetpond__ _ __ _ _ ___ ___compostfilter_____ __ ___ _ ___filterstrip___ ___ _______flowdispersion__ __ _ _______farmmanagementplan__ __ _ ________landscapemanagementplan___ _ ___oil/waterseparator(baffleorcoalescingplate?).Site:continuousinflow?)___ ___ _sandfilter,linear(basicor___ __CONTECHStormfilter___ ___ _sandfiltervault(basicorlarge?)___ ___ _stormwaterwetland_____ __wetvault(basicorlarge?)___ ___ _Wetvault_____ __pre-settlingpond_____ __flow-splittercatchbasin020160.R.STRONGConsultingEngineersInc.TechnicalInformationReportAlpineNurseryPage65CityofRenton ___ _ __ _catchbasininserts:Manufacturer____________________ __pre-settlingstructure:ManufacturerDESIGNINFORMATIONINDIVIDUAL_BASINWaterQualitydesignflowWaterQualitytreatedvolumeDrainagebasin(s)TDASouthOnsitearea(includesfrontage)8.953Offsitearea0.225TypeofStorageFacilityInfiltrationPondLiveStorageVolume(required)19829PredevRunoffRateI2-year0.033110-year0.053100-year0.088DevelopedRunoffRate2-year0.007(includesbypass)iD-year0.010100-year0.015TypeofRestrictorNIASizeoforifice/restrictionNo.1No.2No.3©2016D.R.STRONGConsuiüngEngineersInc.AlpineNurseryPage55TechnicalInformationReportCityofRenton SECTIONXOPERATIONSANDMAiNTENANCEMANUALSeeAppendixEforexcerptsfromthe2009KingCountySurfaceWaterDesignManualwithregardtoOperationsandMaintenance.©2016U.R.STRONGconsultingEngineersInc.AlpineNurseryPage67TechnicalInformationReportCityofRenton APPENDIX“A”OFFSITEANALYSIS©2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage68TechnicalInformationReportCityofRenton LEVELONEDOWNSTREAMANALYSISforALPINENURSERYPreliminaryPlat16023SE144thStreetand14609114625161stAvenueSE,Renton,WashingtonDRSProjectNo.14069RentonFileNo.LUAXXXXXXOwner/ApplicantRoyBoyer14609l6lStAveSERenton,WA98059ReportPreparedbyD.R.STRONGConsultingEngineers,Inc.6207thAvenueNEKirklandWA98033(425)827-3063ReportIssueDateJanuary12,2015©2015D.R.STRONGConsultingEngineersInc. LEVELONEDOWNSTREAMANALYSISALPINENURSERYTABLEOFCONTENTSTASKIDEFINEANDMAPTHESTUDYAREA2TASK2RESOURCEREVIEW6TASK3FIELDINSPECTION16UpstreamTributaryArea16GeneralOnsiteandOffsiteDrainageDescription16TASK4DRAINAGESYSTEMDESCRIPTIONANDPROBLEMDESCRIPTIONS...17DrainageSystemDescription17DownstreamPathTDA17TASKSMITIGATIONOFEXISTINGORPOTENTIALPROBLEMS21APPENDIXA23APPENDIXB26ListofFiguresFigure1.VicinityMap3Figure2.SiteMap4Figure3.CityofRentonTopography5Figure4.Streamsand100-YearFloodplainsandFloodway7Figure5.CityofRentonWetlands8Figure6.CityofRentonErosionHazardAreas9Figure7.KingCountyiMapLandslideHazardAreas10Figure8.CityofRentonSeismicHazardAreas11Figure9.FEMA—FloodInsuranceRateMap12Figure10.KingCountyiMapDrainageComplaints13Figure11.USDAKingCountySoilsSurveyMap14Figure12.DownstreamTable24Figure13.DownstreamMap30©20150.R.STRONGConsultingEngineersInc.LevelOneDownstreamAnalysisAlpineNurseryPage1CityofRenton DISCLAIMER:THISREPORTWASPREPAREDATTHEREQUESTOFROYBOYERFORTHE9.638ACREPARCELSKNOWNASAPORTIONOFTHENORTHEASTQUARTEROFSECTION23,TOWNSHIP23NORTH,RANGE5EAST,W.M.,INKINGCOUNTY,TAXPARCELNUMBER232305-9004,-9099,AND-9167(SITE).D.R.STRONGCONSULTINGENGINEERSINC.(ORS)HASPREPAREDTHISREPORTFORTHEEXCLUSIVEUSEOFDRS,THEOWNER,ANDTHEIRAGENTS,FORSPECIFICAPPLICATIONTOTHEDEVELOPMENTPROJECTASDESCRIBEDHEREIN.USEORRELIANCEONTHISREPORT,ORANYOFITSCONTENTSFORANYREVISIONSOFTHISPROJECT,ORANYOTHERPROJECT,ORBYOTHERSNOTDESCRIBEDABOVE,ISFORBIDDENWITHOUTTHEEXPRESSEDPERMISSIONBYDRS.TASKIDEFINEANDMAPTHESTUDYAREAThisOffsiteAnalysiswaspreparedinaccordancewithCoreRequirement#2,Section1.2.2ofthe2009KingCountySurfaceWaterDesignManual(Manual)asadoptedbytheCity.TheSiteislocatedat16023SE144thStreetand14609)14625161stAvenueSEinRenton,Washington.SeeFigure1,Figure2,andFigure3formapsofthestudyarea.©2015D.R.STRONGConsultingEngineersInc.Page2LevelOneDownstreamAnalysisAlpineNurseryCityofRenton ©2015D.R.STRONGConsultingEngineersInc.Page3LevelOneDownstreamAnalysisCityofRentonFIGURE1.VICINITYMAPTheinformationincludedonthismaphasbeencompiledbyKingCountystafffromavarietyofsourcesandissubjecttochangewithoutnotice.KingCountymakesnorepresentationsorwarranties,expressorimplied,astoaccuracy,completeness,timeliness,orrightstotheuseofsuchinformation.KingCountyshallnotbeliableforanygeneral,special,indirect,incidental,orconsequentialdamagesincluding,butnotlimitedto,lostrevenuesorlostprofitsresultingfromtheuseormisuseoftheinformationcontainedonthismap.AnysaleofthismaporinformationonthismapisprohibitedexceptbywrittenpermissionofKingCounty.AlpineNursery FIGURE2.SITEMAP©2015ftR.STRONGConsultingEngineersInc.Page4LevelOneDownstreamAnalysisAlpineNurseryCityofRenton 1A0flMSlitl)MaMallililit7flMpaItittMaS4i74Aiti.eittt3:0anr17uBwaei.-w44ThJST-———-L_jIINrHnrHi1-/‘°‘tt=/I’r--LhtIIMr——.MiiixJ’-_-_-_-—1/’\/-——‘--—ian.s..t—\nm-cnitwitIi/I-IE--\r;L/•AliMflMi4-——/“1jpoaTit-N8754ICwz--_____________________St.4%39Xwas———IN.airaitcMi‘S‘—‘rn—-,.1c-aspanuj\MMmCMa4Ma-Ml.PC74.MaIMiili4SLn0‘O0Pi_AIMiWnJINMaS‘anMaitMa‘“In’A-iz0I0‘1H0MaMaP..I--mi—t&tAMi—PMa?‘aIn54-57.Ma7flflfl541a‘0C-SITEMAP/ALPINENURSERY16023SEI44THST&14609/14625I6ISTAVESERENTON,WA98059[[DRSJ)CONSULUNGENGINEERSfl/GSNSRSPLANNERSSURW)VAS-SAWOIUEOILIAND.WA9I304.U7.XF42i8fl24fl— FIGURE3.CITYOFRENTONTOPOGRAPHYrCPC’d’tT4*,n—B.wId—2..011.‘e.’1=I—*I,,rl.nda.—I56012$2fCv—V•I020150.R.STRONGConsultingEngineersInc.LevelOneDownstreamAnalysisPage5CityofRenton14121SE144thSt.1142011411144flSite‘IL,,1110414114ISl2lI.II314402—1140%III’’144o414434IW$l%flNIh“InIII”I442Ill,’I‘12014410a11317I—‘ccl.1111111121‘‘In10711112’11411Ill’’1412111111III,’It’ll14777‘4217IlII”,,‘Ills‘C-‘I’llurn14720‘WI14433‘WI1107114WSAlpineNursery •TASK2RESOURCEREVIEW•AdoptedBasinPlans:LowerCedarRiverBasinandNonpointActionPlanwasadoptedinJuly1998.•Floodplain/Floodway(FEMA)Map:Nofloodplainsexistonsite,SeeFigure9.•OtherOffsiteAnalysisReports:Noneavailableatthistime.•SensitiveAreasFolioMaps:SeeFigures4-8fordocumentationofthedistancedownstreamfromtheproposedprojecttothenearestcriticalareas.Included,aresectionsoftheCityofRentonMappingApplicationandKingCountySensitiveAreasFoliowhichindicatethefollowing:Figure4Streamsand100-YearFloodplainsandFloodway:ThereisoneTypeIriver,CedarRivertothesouth,withinonemileoftheSite.A100-yearfloodplainiswithinonemileoftheSitealongCedarRiver.•Figure5Wetlands:ThereisonewetlandaroundaportionofCedarRiverwithinonemileoftheSitealongthedownstreampath.•Figure6ErosionHazard:TherearemappedErosionHazardAreaswithinonemileoftheSitealongthedownstreampath.•Figure7LandslideHazard:TherearemappedLandslideHazardAreaswithinonemileoftheSitealongthedownstreampath.•Figure8SeismicHazard:TherearemappedSeismicHazardAreaswithinonemileoftheSitealongthedownstreampath.•DNRPDrainageComplaintsandStudies:AsshowninFigure10,therearedrainagecomplaintswithinImileoftheSitealongthedownstreampath.TherearethreedrainagecomplaintsonSitebuttheyregardfeere-measurementandarenotrelevanttothisreport.TheotherdrainagecomplaintswithinonemilealongthedownstreampatharenotrelevanttoaLevelOneAnalysis.SeeTask5.•RoadDrainageProblems:Nonenoted.•USDAKingCountySoilsSurvey:SeeFigureII.•WetlandsInventory:Thewetlandinventoryrevealednoadditionalwetlandswithinthedownstreampath.•MigratingRiverStudies:Noneareapplicabletothesite.•WashingtonStateDepartmentofEcology’slatestpublishedCleanWaterActSection303dlistofpollutedwaters:Nonelistedalongthedownstreampath.•KingCountyDesignatedWaterQualityProblems:Noneatthistime.•AdoptedStormwaterCompliancePlans:CityofRentonStormWaterManagementPlan;KingCounty2013StormwaterManagementPlan•BasinReconnaissanceSummaryReports:CedarRiverCurrentandFutureConditionsReport(April1993).©20150.R.STRONGconsultingEngineersInc.Page6LevelOneDownstreamAnalysisAlpineNurserycityofRenton FIGURE4.STREAMSAND100-YEARFL000PLAINSANDFLOODWAYNOL*139100Cfl—C..o’t,Penft0,thi‘L.’2_,‘—‘B‘‘flwtfl.ii0d..saWV‘eYSn——sa—I—%x4102305121023’—‘‘a’—©20150.R.STRONGConsultingEngineersInc.LevelOneDownstreamAnalysisPage7CityofRentonI.’Sitef—1IIp——SI.1ppAlpineNursery FIGURE5.CITYOFRENTONWETLANDSa‘4.Ct.niC..,.,On’4.L.P.,..DHId—JIdr.,OUCfl.lbMJnB44’u,E—102305121023’—•02015D.R.STRONGConsultingEngineersInc.LevelOneDownstreamAnalysisAlpineNurseryPage8CityofRentonSitelrj--Tn‘j•.H,i——-— FIGURE6.CITYOFRENTONEROSIONHAZARDAREASaU9.CIC‘fl.G,u,B,srd.I”P.c.fltft.,.Id2’3‘aj*BidflanOIeI1Q2305121023’—tIUb’ksd.tç.Page9CityofRentonI.,’SiteHaiiit-..Fr©2015D.R.STRONGConsultingEngineersInc.LevelOneDownstreamAnalysisAlpineNursery FIGURE7.KINGCOUNTYIMAPLANDSLIDEHAZARDAREASHighlightedFeatureICountyBoundaryxMountainPeaksHighwaysStreetsp4Ilqhwiy(cant)ParcelslskesandLargeRivenStreamsSAOLandslideW‘aSitefl‘eNSr—‘eN—$1NaIt*wI.&itLegend.9.1D020150.R.STRONGConsultingEngineersInc.LevelOneDownstreamAnalysisPage10CityofRentonAlpineNursery FIGURE8.CITYOFRENTONSEISMICHAZARDAREAS020150.R.STRONGConsultingEngineersInc.LevelOneDownstreamAnalysisPage11CityofRenton.1E.p\auwcCI—C4flPea.C.‘.‘—QrOS4dq.F.’—.1,etat305121023’—IIM4.S%t*.sa.I.!ce.AlpineNursery .FIGURE9.FEMA-FLOODINSURANCERATEMAP.nn.nsal__vn_,SCa—lEESnC——aRPMnflfleaLIIIki’•canwAnhL’aDNANSINrnmvRATt,AREASHasSS’SRU‘eRaRSEESIRSIRUIflIlb”s—Pa——ARMnofl&CUta’S22s0LtUNTT.WASUNCItNANDR1mIATTJ2AflASNaSRipRipiDSWSEED;RI,,-_——Page12CityofRentonZONEIC23NOTE:AMPAREASHOWNONTN’SPANTLISLOCATEDWITHINTOWNSHIP23NORTHANDPANOE5EAST.e©2015D.R.STRONGConsultingEngineersInc.LevelOneDownstreanAnalysisAlpineNursery FIGURE10.KINGCOUNTY1MAPDRAINAGECOMPLAINTSr.aI44Thft[--StSwisSite\MtdTHITwatoft7.S[wtft4140dStSSIIIS?(DSrS.Lo9endSolectedParcelsICooityBandaryxMountahiPeaksHighwaysincorporatedAmaStreets(cord)IIchwayLoaPar:aIstakesandLargeRivenStrcamsDraiageCamptain6C//©2015D.R.STRONGConsultingEngineersInc.LevelOneDownstreamAnalysisPage13CityofRentonAlpineNursery FIGURE11.USDAKINGCOUNTYSOILSSURVEYMAP050ILLpirti:VWjIbG.mozfl,aV4tjiflxLPN7aIlvaaiLSQ?btLnlRnoinn____Cc,ne,v,tionService©2015D.ftSTRONGConsulLingEngineersInc.LevelOneDownstreamAnalysisWe*Soil5oiwyNationalCocperatveSo)SurveySoiMap—Ks’gCamlyAn,.Wathngton—4’4’NoIvMs:tI.7%rp,LnJa,A1nW(LrmIID..zCAlC.12/15,2014Pe1ce3AlpineNurseryPage14CityofRenton EvB—Everettgravellysandyloam,0to5percentslopesMapUnitSetting•NationalmapunitsymboL1hmt2•Meanannualprecipitation:30to45inches•Meanannualairtemperature:50degreesF•Frost-freeperiod:180days•Farmlandclassification:PrimefarmlandifirrigatedMapUnitComposition•Everettandsimilarsoils:100percent•Estimatesarebasedonobservations,descriptions,andtransectsofthemapunit.DescriptionofEverettSetting•Landform:Terraces•Parentmaterial:GlacialoutwashwithacomponentofvolcanicashintheupperpartTypicalprofile•HI-0to17inches:gravellyashysandyloam•H2-17to32inches:verygravellysandyloam•H3-32to60inches:verygravellycoarsesandPropertiesandqualities•Slope:0to5percent•Depthtorestrictivefeature:Morethan80inches•Naturaldrainageclass:Somewhatexcessivelydrained•Capacityofthemostlimitinglayertotransmitwater(Ksat):High(1.98to5.95in/hr)•Depthtowatertable:Morethan80inches•Frequencyofflooding:None•Frequencyofponding:None•Availablewaterstorageinprofile:Low(about5.0inches)Interpretivegroups•Landcapabilityclassification(irrigated):Nonespecified•Landcapabilityclassification(nonirrigated):3s•HydrologicSoilGroup:A•Othervegetativeclassification:DroughtySoils(GOO2XN4O2WA)©2015D.R.STRONGConsultingEngineersInc.Page15LevelOneDownstreamAnalysisAlpineNurserycityofRenton TASK3FIELDINSPECTIONUPSTREAMTRIBUTARYAREAInevaluatingtheupstreamarea,wereviewedKingCountyiMAPaerialtopography,CityofRentonMappingApplication,conductedfieldreconnaissanceandhaveconcludedthatupstreamtributaryareafortheSiteisminimal.Upstreamrunofffromthenorthappearstobecollectedintothepipe/ditchconveyancesystemalongthenorthsideofSE144thStreet.161stAvenueSEborderingtheeasternpropertylineslopeseastanddirectsrunoffawayfromtheSite.TopographyshowsthewestandsouthpropertiesslopeawayfromtheSite.ThereisupstreamrunofffromParcel2323059156thatisinthenorthwestcorneroftheSite.ThispropertyconveysrunoffsouthontotheSiteandtheupstreamtributaryareaisconsideredminimal.GENERALONSITEANDOFFSITEDRAINAGEDESCRIPTIONRunofftravelssouthandsouthwestassheetflowacrossthepropertyovergrass,densebrush,andsoil/graveldrivingpaths.TheSitecontainstwoThresholdDischargeAreas(TDA),TDASouthandTDANorth.TDASouthconsistsofeverythingexceptapproximately0.5acresofthenortheastportionoftheSite.ThedischargepointofTDASouthisapproximatelythewesternhalfofthesouthpropertyline.RunoffsheetflowsontothepropertiestothesouthoftheSiteandcontinuessouththroughthepublicconveyancesystem.RunoffeventuallyreachestheCedarRiverapproximately0.5milessouthoftheSite.TDANorthconsistsofapproximately18,929s.f.ofthenortheastportionoftheproperty.RunoffsheetflowsnorthintotheconveyancesysteminSE144thStreet.RunoffcontinueswestthroughtheconveyancesysteminSE144thStreetandthencrossesunderneath154thPlaceSEwhereitoutletstoStewartCreek,aClass3stream.StewartCreekoutletstoCedarRiverapproximately0.4mileswestoftheSite.020150.R.STRONGConsultingEngineersInc.Page16LevelOneDownstreamAnalysisAlpineNurserycityofRenton TASK4DRAINAGESYSTEMDESCRIPTIONANDPROBLEMDESCRIPTIONSDRAINAGESYSTEMDESCRIPTIONThedownstreamanalysisisfurtherillustratedanddetailedintheDownstreamMapandDownstreamTablelocatedinAppendixA.ThedownstreamareaislocatedwithintheLowerCedarRiverbasin.Thedownstreamareawasevaluatedbyreviewingavailableresources,andbyconductingafieldreconnaissanceonDecember17,2014undercloudy/rainyconditions.TheSitecontainstwoTDA’s,TDANorthandTDASouth.RunofffromTDASouthexitsalongthesouthpropertyline.Runoffcontinuessouthassheetflowacrossadjacentpropertiestothesouthbeforeitenterstheconveyancesysteminthecul-de-sacof160thPlaceSEwhichoutletstotheditchatthenortheastcornerofSE148thStreetand160thPlaceSE.FlowentersaType2catchbasineastoftheintersectionapproximately100’andfollowstheconveyancesystemwestinSE148thStreetandthensouthin160thPlaceSE.AtthecornerofSE149thStreetand160tLPlaceSErunoffisdirectedsouthwestthroughapropertyandconveyeddownthehillsidethroughan18”HDPEpipe.Flowcontinuessouththroughtheconveyancesystemin160thPlaceSEandeventuallyoutletstoCedarRiver.RunofffromTDANorthsheetflowsnorthandintoacatchbasinonthesouthsideofSE144thStreet.FlowenterstheconveyancesysteminSEl44Streetandcontinueswestforapproximately0.25milestowardstheintersectionwith156thAvenueSE.RunoffcontinueswestintheinthedirtroadwestofSE144thStreetandthencrossesunderneath154thPlaceSEwhereitoutletstoStewartCreek,aClass3stream.StewartCreekoutletstoCedarRiverapproximately0.4mileswestoftheSite.DownstreamPathTDASouthPoint“A”isthenaturaldischargepointofTDASouth.Runoffisconveyedsouthacrossthesouthpropertylineassheetflow(±0’).FromPoint“A”toPoint“B”,runoffheadssouthassheetflowtothepavedcul-de-sacof160thPlaceSE(±0-110’).Point“B”,runoffentersthepavedcul-de-sacof150thPlaceSE(±110’).FromPoint“B”toPoint“C”,runoffheadssouthassheetflow.Noflowwasobserved(±110’-275’).Point“C”,runoffentersagrass-linedditchlocatedonthenortheastcornerofSE148thStreetand160°PlaceSE(±275’).FromPoint“C”toPoint“D”,runoffheadswestaschannelflowinthegrasslinedditch(6’top,1.5’deep,1.5’bottom).Noflowobserved(±275’-477’).Point“D”,runoffentersa12”corrugatedmetalpipe(CMP)locatedonthenorthsideofSE148thStreet(±477’).FromPoint“D”toPoint“E”,runoffcontinueswestaspipeflowviaa12-inchdiameterCMP.Noflowwasobserved(±477’-490’).©2015D.R.STRONGConsultingEngineersInc.Page17LevelOneDownstreamAnalysisAlpineNurserycityofRenton Point“E”,runoffentersaType2catchbasinattheeastendofSEl48Streetonthenorthside(±490’).FromPoint“E”toPoint“F”,runoffcontinuessouthaspipeflowviaa12-inchdiameterCMP.Noflowwasobserved(±490’-528’).Point“F”,runoffentersaType1catchbasinlocatedattheeastendofSE148thStreetonthesouthside(±528’).FromPoint“F”toPoint“G”,runoffheadseastaspipeflowviaa12-inchdiameterreinforcedconcretepipe(RCP).Noflowwasobserved(±528’-639’).Point“C”,runoffentersaType2catchbasinlocatedattheintersectionofSEl48°Streetand160thPlaceSE(±639’).FromPoint“G”toPoint“H”,runoffheadssouthaspipeflowviaa12-inchdiameterRCP.Noflowwasobserved(±639’-865’).Point“H”,runoffentersaType2catchbasinonthewestsideof160thPlaceSE(±865’).FromPoint“H”toPoint“I”,runoffcontinuessoutheastaspipeflowviaa12-inchdiameterRCP.Noflowwasobserved(±865-940’).Point“F’,runoffentersaType2catchbasinlocatedonthesouthsideofSE149thStreet(±940’).FromPoint“I”toPoint“4”,runoffheadssouthwestaspipeflowviaa12-inchdiameterRCP.Noflowwasobserved(±940’-1,161’).Point“J”,runoffentersaType2catchbasinlocatedinthesouthwestcornerofparcel7806500240(±1,161’).FromPoint“J”toPoint“K”,runoffcontinuessouthaspipeflowviaan18-inchdiameterhigh-densitypolyethylene(HDPE)pipe.TheHDPEpipebecomesanabovegroundpipeapproximately35’southofparcel7806400240.Catchbasinwasinaccessible(±1,161’-1,624’).Point“K”,runoffentersaType2catchbasinlocatedontheeasternportionofParcel7806450140(±1,624’).Runoffcontinuessouthintheconveyancesysteminl6OPlaceSEandoutletstoCedarRiverapproximately0.5milessouthoftheSite.DownstreamPathTDANorthPoint“A2”isthenaturaldischargepointofTDANorth.RunoffisconveyednorthwesttoSE144thStreetassheetflow(±0’).FromPoint“A2”toPoint“B2”,runoffheadsnorthwestassheetflowtothecatchbasinonthesouthsideofSE1441hStreetattheapproximatemidpointofthenorthpropertyline(±0’-19’).Point“B2”,runoffentersacatchbasinonthesouthsideofSE144thStreetattheapproximatemidpointofthenorthpropertyline(±19’).FromPoint“B2”toPoint“C2”,runoffheadswestaspipeflowviaan18-inchdiametercorrugatedmetalpipe(CMP).Flowobserved(±19-219’).020150.R.STRONGconsultingengineersInc.Page18LevelOneDownstreamAnalysisAlpineNurserycityofRenton Point“C2”,runoffentersaType1catchbasinlocatedatthesoutheastcornerofSEl44Streetand160thAvenueSE(±219’).FromPoint“C2”toPoint“D2”,runoffheadswestaspipeflowviaan18-inchdiameterCMP.Flowobserved(±219-260’).Point“D2’,runoffentersaType1catchbasinlocatedatthesouthwestcornerofSEl44’Streetand1601hAvenueSE(±260’).FromPoint“D2”toPoint“E2”,runoffheadswestaspipeflowviaan18-inchdiameterCMP.Flowobserved(±260’-378’).Point“E2”,runoffentersaType1catchbasinonthesouthsideofSEj44tu1Street(±378’).FromPoint“E2”toPoint“F2”,runoffcontinueswestaspipeflowviaan18-inchdiameterCMP.Flowobserved(±378-523’).Point“F2”,runoffentersaType1catchbasinlocatedonthesouthsideofSE144thStreet(±523’).FromPoint“F2”toPoint“G2”,runoffcontinueswestaspipeflowviaan18-inchdiameterCMP.Flowobserved(±523-689’).Point“G2”,runoffentersaType1catchbasinlocatedonthesoutheastcornerofSE144thStreetand158thPlaceSE(±689’).FromPoint“G2”toPoint“H2”,runoffcontinueswestaspipeflowviaan18-inchdiameterCMP.Flowobserved(±689’-832’).Point“H2”,runoffentersaTypeIonthesouthsideofSE144thStreet(±832’).FromPoint“H2”toPoint“12”,runoffcontinueswestaspipeflowviaan18-inchdiameterCMP.Flowobserved(±832’-1,009’).Point12”,runoffentersaType1catchbasinlocatedonthesouthsideofSE144thStreet(±1,009’).FromPoint“12”toPoint“J2”,runoffcontinueswestaspipeflowviaan18-inchdiameterCMP.Flowobserved(±1,009-1,188’).Point“J2’runoffentersaType1catchbasinonthesouthsideofSE144thStreet(±1,188’).FromPoint“J2”toPoint“K2”,runoffcontinueswestaspipeflowviaan18-inchdiameterCMP.Flowobserved(±1,188-1,360’).Point“K2”,runoffentersaType1catchbasinonthesouthsideofSE14401Street(±1,360’).FromPoint“K2”toPoint“L2”,runoffcontinueswestaspipeflowviaan18-inchdiameterCMP.Flowobserved(±1360-1,511’).Point12”,runoffentersaType1catchbasinonthesouthsideofSE144thStreet(±1,511’).ThisisjustpastthequartermiledownstreampathforNDANorth.Runoffcontinueswestinthisconveyancesystemandisdirectedsouthwestacross154thPlace©2015D.R.STRONGConsultingEngineersInc.Page19LevelOneDownstreamAnalysisAlpineNurseryCityofRenton •SEwhereitoutletstoStewartCreekwhichoutletstoCedarRiverapproximately0.4mileswestoftheSite.©20150.H.STRONGConsultingEngineersInc.Page20LevelOneDownstreamAnalysisAlpineNurseryCityofRenton TASK5MITIGATIONOFEXISTINGORPOTENTIALPROBLEMSAreviewoftheKingCountyWaterandLandResourcesDivision—DrainageServicesSectionDocumentedDrainageComplaintswithinonemileofthedownstreamflowpathsrevealed3complaintswithinthelasttenyears.Twoofthecomplaintsareaspecialpermituserequestandtheotherawaterqualitycomplaint,bothofwhicharenotrelevanttoaLevelOnedownstreamanalysis.Thethirdcomplaintisaresidentialfacilitycomplaintregardingdumpingofsodbyanadjacentpropertyownerandisnotapplicabletothisanalysis.AmapofthedrainagecomplaintsalongthedownstreampathisshowninAppendixB.ProjectrunoffwillbecollectedandreleasedpertheManual’srequirementstoaccommodateFlowControlDurationStandard,ForestedSiteConditionsandBasicWaterQualityrequirements.Duringconstruction,standardsedimentanderosioncontrolmethodswillbeutilized.Thiswillincludetheuseofastabilizedconstructionentrance,perimetersiltfencing,andothernecessarymeasurestominimizesoilerosionduringconstruction.TheprojectshouldnotcreateanyproblemsasspecifiedinSection1.2.2.1oftheManualandthereforeisnotrequiredtoprovideDrainageProblemImpactMitigationsubjecttotherequirementsofSection1.2.2.2.©20150.R.STRONGConsultingEngineersInc.Page21LevelOneDownstreamAnalysisAlpineNurseryCityofRenton ComplaintParcelSummaryRecurringTypeRequirednumberMitigation2006-05521079300100SpecialuseNoN/ANonepermitrequestingprivateuseofpond2002-02447806450230AdjacentNoN/ANonepropertyownerdumpingsod.2011-1008232305HYDRTwotelevisionsNoN/ANonedumpedintoCedarRiver@20150.R.STRONGConsultingEngineersInc.Page22LevelOneDownstreamAnalysisAlpineNurserycityofRenton APPENDIXA.OFFSITEANALYSISDRAINAGESYSTEMTABLE&DOWNSTREAMMAP©2015D.R.STRONGConsultingEngineersInc.Page23LevelOneDownstreamAnalysisAlpineNurseryCityofRenton Basin:Cedar River Subbasin Number Lower Cedar River ©2015 D.R.STRONG Consulting Engineers Inc.Page 24 ... FIGURE 12. DOWNSTREAM TABLE TDA South Symbol Drainage Drainage Component Slope Distance Existing Potential Observations of field inspectorComponentType,Description From site Problems Problems resource reviewer,or residentName,and Size Discharge Type:sheet flow,Constrictions,under capacity,ponding,tributary area,likelihood of problem,see map swale,Stream,drainage basin,vegetation,cover,1/4 miI320 ft overtopping,flooding,habitat or organism overflow pathways,potential impacts.channel,pipe,depth,lype of sensitive area,volume destruction,scouring,bank sloughing, Pond;Size:diameter sedimentation,incision,other erosion Surface area A NATURAL WESTERN HALF OF SOUTH ±0’NONE NONE DISCHARGE POINT PROPERTY LINE OBSERVED ANTICIPATED A-B SOUTHERLY SHEET NATIVE VEGETATION/GRASS NONE NONE NO FLOW OBSERVED FLOW OBSERVED ANTICIPATED B CUL-DE-SAC l6O PAVED CONVEYANCE SYSTEM ±110’NONE NONE PL SE OBSERVED ANTICIPATED B-C SOUTHERLY SHEET PAVED CONVEYANCE SYSTEM NONE NONE NO FLOW OBSERVED FLOW OBSERVED ANTICIPATED C DITCH GRASS-LINED DITCH ±275 NONE NONE OBSERVED ANTICIPATED C-D WESTERLY GRASS-LINED DITCH NONE NONE NO FLOW OBSERVED CHANNEL FLOW (6’TOP,1.5’DEEP,1.5’BOflOM)OBSERVED ANTICIPATED D PIPE INLET 12”0 CMP ±477’NONE NONE OBSERVED ANTICIPATED D-E WESTERLYPIPE 1T0CMP NONE NONE NOFLOWOBSERVED FLOW OBSERVED ANTICIPATED Level One Downstream Analysis Alpine Nursery City of Renton ... E CATCH BASIN -INLET (E)±490 NONE NONE -OUTLET(S)OBSERVED ANTICIPATED E-F SOUTHERLYPIPE 12”ØCMP NONE NONE NOFLOWOBSERVEDFLOWOBSERVEDANTICIPATED F CATCH BASIN -INLET (N)±528 NONE NONE -OUTLET (E)OBSERVED ANTICIPATED F-G EASTERLY PIPE 12”0 RCP NONE NONE NO FLOW OBSERVEDFLOWOBSERVEDANTICIPATED 0 CATCH BASIN -INLET )±639’NONE NONE -OUTLET(S)OBSERVED ANTICIPATED G-H SOUTHERLY PIPE 12”0 RCP NONE NONE NO FLOW OBSERVEDFLOWOBSERVEDANTICIPATED H CATCH BASIN -INLET (N)±865’NONE NONE -OUTLET (SE)OBSERVED ANTICIPATED H-I SOUTHEASTERLY 12”0RCP NONE NONE NOFLOWOBSERVEDPIPEFLOWOBSERVEDANTICIPATED I CATCH BASIN -INLET (NW)±940 NONE NONE -OUTLET (SW)OBSERVED ANTICIPATED I-J SOUTHWESTERLY 12”0 RCP NONE NONE NO FLOW OBSERVED PIPE FLOW OBSERVED ANTICIPATED J CATCH BASIN -INLET(NE)±1.161’NONE NONE -OUTLET (5)OBSERVED ANTICIPATED J-K SOUTHERLYPIPE 18”OHDPE NONE NONE INACCESSIBLE FLOW OBSERVED ANTICIPATED ©2015 D.R.STRONG Cansulling Engineers Inc.Page 25LevelOneDownstreamAnalysisAlpineNurseryCityofRenton (000)wW0Ua,U,za,CaUCU,a,a,=0)CLUtCU,mc,CC0<OwcooULUIDaLUxHU0CzLULUzI00HLUxH2rID0U)U)LUD2I20UL1U020LUU0I0-JH00C2LU0LUU0-C(0aLUI0>-0LU0aLUa000LU-J0>_-J±aI0CLUa0aCLU>QtLUU)0LUa02LUaCxS(0ator00 .. TDA North . Basin:Cedar River 02015 ft R.STRONG Consulting Engineers Inc.Level One Downstream Analysis Subbasin Number:Lower Cedar River Page 27 City of Renton Symbol Drainage Drainage Component Slope Distance Existing Potential Observations of field inspectorComponentType,Description From site Problems Problems resource reviewer,or residentName,and Size Discharge Type:sheet flow,Constrictions,under capacity,ponding,tributary area,likelihood of problem,See map swale,Stream,drainage basin,vegetation,cover,114 mil 320 ft overtopping,flooding,habitat or organism overflow pathways,potential impacts.channel,pipe,depth,type of sensitive area,volume destruction,scouring,bank sloughing,Pond;Size:diameter sedimentation,incision,other erosionSurfacearea A NATURAL SOUTH SIDE OF SE l44 STREET ±0’NONE NONE DISCHARGE POINT OBSERVED ANTICIPATED A-B NORTFMIESTERLY NATIVE VEGETATION!GRASS(SOIL NONE NONE NO FLOW OBSERVEDSHEETFLOWOBSERVEDANTICIPATED B CATCH BASIN -OUTLET)±19’NONE NONE OBSERVED ANTICIPATED B-C WESTERLY PIPE 1W’0 CMP NONE NONE NO FLOW OBSERVEDFLOWOBSERVEDANTICIPATED C CATCH BASIN -INLET (E)±219’NONE NONE -OUTLET )OBSERVED ANTICIPATED C-D WESTERLY PIPE 18’0 CMP NONE NONE FLOW OBSERVEDFLOWOBSERVEDANTICIPATED D PIPEINLET -INLET(E)±260’NONE NONE -OUTLET V)OBSERVED ANTICIPATED D-E WESTERLY PIPE 18’0 CMP NONE NONE FLOW OBSERVEDFLOWOBSERVEDANTICIPATED E CATCH BASIN -INLET (E)±378’NONE NONE -OUTLET )OBSERVED ANTICIPATED Alpine Nursery 0)ma)0U0Sza)=adCa)a)C0)CUi=52’CC0<Owza)0-;00 ... K-L WESTERLY PIPE 1S 0 CMP NONE NONE FLOW OBSERVEDFLOWOBSERVEDANTICIPATED L CATCHBASIN -INLET(E)±1,511 NONE NONE THISISTHEENDOFTHEQUARTER -OUTLET (NW)OBSERVED ANTICIPATED MILE DOWNSTREAM.RUNOFF CONTINUES WEST IN THIS CONVEYANCE SYSTEM AND CROSSES l54 PLACE SE AND OUTLETS TO STEWART CREEK WHICH OUTLETS TO CEDAR RIVER APPROXIMATELY 0.4 MILES WEST OF THE SITE. ©2015 D.R.STRONG Consulting Engineers Inc.Page 29LevelOneDownstreamAnalysisAlpineNurseryCityofReMan .FIGURE13.DOWNSTREAMMAP020150.R.STRONGConsultingEngineersInc.Page30LevelOneDownstreamAnalysisAlpineNurseryCityofRenton I-fln6IJ0Iz-ri-iGRAPHICSCALE0500CoC0JL_1INCH=500FT. APPENDIXB.DRAINAGECOMPLAINTSMAPHaH4maHHft10793001ItLINTHftwI\11HYDRLIH8©2015D.R.STRONGConsultingEngineersInc.LevelOneDownstreamAnalysisPage31CityofRentonAlpineNursery APPENDIX“B”MOUNDINGANALYSIS02016ftftSTRONGConsultingEngineersInc.AlpineNurseryPage69TechnicalInformationReportCityofRenton EarthSolutionsNWLLCSeptember2,2015EarthSolutionsNWLLCES-3377.03•CeotechnicalEngineering•ConstructionMonitoring•EnvironmentalSciencesGeonercoProperties,LLC1441North34thStreet,Suite200Seattle,Washington98103Attention:Mr.JamieWaltierSubject:GroundwaterMoundingAnalysisProposedInfiltrationPondBoyerProperty16023Southeast144thStreetRenton,WashingtonReference:ConceptualSiteLayoutD.R.ConsultingEngineersSheetCl,datedJanuary12,2015InfiltrationEvaluationEarthSolutionsNW,LLCES-3377.02,datedJanuary9,2015DearMr.Waltier:InaccordancewitharequestfromtheprojectCivilEngineer,D.R.Strong,EarthSolutionsNW,LLC(ESNW)haspreparedthisletterprovidingtheresultsofamoundinganalysiscompletedforthesubjectproject.ProjectDescriptionThesubjectsiteislocatedalongthewestsideof161stAvenueSoutheastacrossfromSoutheast146thPlaceinRenton,Washington.Thepropertyispartofalargerresidentialredevelopmentprojectcurrentlybeingdesigned.Thepropertyiscurrentlydevelopedwithsingle4amilyresidencesandassociatedimprovements.Stormwatermanagementdesignsincludeaninfiltrationpondlocatedinthesouthernportionofthepropertywithinatopographiclowarea.Thepondwillbecuttoaboutelevation356feet.1805-136thPlaceN.E.Suite201BellevueWA98005•(425)449-4704•FAX(425)449-4711 GeonercoProperties,LLCES-3377.03September22015Page2SubsurfaceConditionsAnESNWrepresentativeobserved,loggedandsampledtwotestpitsexcavatedwithintheinfiltrationpondbottomareaforpurposesofcharacterizingandclassifyingthesoilconditions.Pleaserefertothetestpitlogsinthereferencedletterforamoredetaileddescriptionofthesubsurfaceconditions.ExplorationProgramThesitewasexploredduringthreesitevisits;oneinDecember2014,oneinJanuary2015andoneinAugust2015.Atotalof11testpitsandoneboringwereexcavatedataccessiblelocationofthesiteduringthesitevisits.FallingHeadinginfiltrationtestswereconductedtocharacterizethein-siteinfiltrationcapacityofsitesoils.Thisinformationwasusedinthegroundwatermoundinganalysis.ConfiningSoilLayerWherepresent,aconfiningsoillayerisusedforModRetanalysis.Onthissite,aconfiningsoillayerwascharacterizedasaglacialtilllayerinadensecondition.DuringthesiteexplorationonAugust6,2015,aglacialtilllayerwasidentifiedatadepthof28feetbelowexistinggrade,correspondingtoanelevationof336feet.Acopyoftheboringlogisattached.GroundwaterGroundwaterwasnotobservedatthetestpitlocationswhichwereextendedtoamaximumdepthof31.5feetbelowexistinggradewhichcorrespondstoanelevationofabout332.5feet.However,nomottlingwasobservedintheuppersandlayers,suggestingthatgroundwaterdoesnotperchinthiszoneforextendedperiodsoftime.InfiltrationTestingArepresentativeofESNWwason-sitetoobservethesubsurfaceconditionsinDecemberof2014andJanuaryof2015.ESNWobservedtheexcavationofeighttestpitsusinghandtools,aswellasanexcavatorandoperator,contractedbyESNW,throughoutthestormwaterpondfootprintinsouthernportionofthesubjectsite.Thetestpitswereadvancedtoapproximately13feetdeepintothenativesoil.ESNWobservedpoorlygradedgravel(UnifiedSoilClassification,GP),andwellgradedgravel(GW)inadenseconditionatallthreetestlocationsatthebottom-of-pondelevation.Pleaseseethesoillogslaterinthisreportforadetaileddescriptionofthesubsurfaceconditions.EPAfallingheadinfiltrationtestingwasperformedwithinthewellgradedsandandgravelsoilsinthreeofthetestpits.Theexcavationswereterminatedinthewellgradedsandandgravelsoilsatmaximumof15feetbelowexistinggrade,whichequatestoaminimumofsixfeetbelow•bottom-of-pondelevation.ThesoilconditionswhichESNWobservedwereconsistentwiththegeologicmapdesignationofglacialoutwash.EarthSolullons,LLc GeonercoProperties,LLCES-3377.03September2,2015Page3.Testingwascompletedwithinthewellgradedgrave!soilsinordertoevaluatetheinfiltrationratesatthebottom-of-pondsoiltypes.Themeasuredinfiltrationrateswere70in/hourwithintheundisturbednativesoils.Atestmethodreductionof0.3,pluggingreductionof0.9andageometricreductionfactorof1.0yieldsadesigninfiltrationrateof18inchesperhour.TexturalAnalysesTexturalanalyseswereperformedonrepresentativesoilsamplescollectedfromthetestsitestosupplementtheinfiltrationtestingandtorefinetheinfiltrationratedetermination.ThetexturalclassificationswereperformedinaccordancewiththeUSDAsievemethod.ThisclassificationdiffersfromtheUSCSclassificationmethodinthatthesandfractionofthesampleisbasedontheminus#10sievefractionasopposedtotheminus#4sievefractionusedforUSGSclassification.Thewellgradedgravelcontainedafinescontentofabout2.6percentand2.3percent;andaUSDAdescriptionofExtremelyGravellyCoarseSand.GroundwaterMoundingAnalysisWeusedtheMODRET6.1hydrologiccomputermodelingsoftwareprogramtoevaluatemoundingofthelocalgroundwatertableduringastormevent.AsummaryoftheModRetinputparametersandpredictedresultsareincludedintheattachedModRetsummary.ModRetParametersandAssumptionsThedatainputincludedtheproposedinfiltrationfacilitygeometry,designhighwaterandbottomelevationandsoilandgroundwaterconditionsacquiredfromtestpitsandboringcompletedwithintheprojectarea.AcopyoftheModRetinputparameterspageisincludedintheattachment.VerticalandhorizontalhydrauHcconductivityparametersweredeterminedfromin-situinfiltrationtestingconductedwithintheproposedretentionpond.Adesigninfiltrationrateof10.0inches/hourwasusedformodelingpurposeswhichisconservative.Aconfininglayerwasobservedatadepthof28feetbelowexistinggradeattheboringlocation.Thiscorrespondstoanelevationofapproximately336feet.TheaquiferbasewasestimatedfromtheboringadvancedESNWformodelingpurposesonly.HydrographThemodelhydrographwasgeneratedbyD.R.StrongConsultingEngineersusingtheKCRTScomputersoftwareandwerepresentedin24-hourincrementsovera30dayperiod.ThehydrographdataprovidedtoESNWweretheninputintoMODRETaspartofouranalysis.ResultsandRecommendationsTheresultsofthemoundinganalysispredictsthemaximumwaterlevelduringapeakstormeventisbelowthebottomoftheinfiltrationpond.EarthSoluIonsNW,ac ES-3377.03GeonercoProperties,LLCSeptember2,2015Inouropinion,theresultsofthemoundinganalysiscorrelatewiththesoilandgroundwaterconditionsobservedatthetestsites.Thisopiniondoesnotcoverunforeseenorchangedconditions.ESNWshouldobservetheinfiltrationsurfaceduringconstructiontoconfirmsoilconditionsareasanticipatedandtoprovidesupplementalrecommendations,ifdeemednecessary.LIMITATIONSTherecommendationsandconclusionsprovidedinthisletterareprofessionalopinionsconsistentwiththelevelofcareandskillthatistypicalofothermembersintheprofessioncurrentlypracticingundersimilarconditionsinthisarea.Awarrantyisnotexpressedorimplied.Variationsinthesoilandgroundwaterconditionsobservedatthetestsitelocationmayexist,andmaynotbecomeevidentuntilconstruction.ESNWshouldreevaluatetheconclusionsinthisletterifvariationsareencountered.Wetrustthislettermeetsyourcurrentneeds.Ifyouhavequestionsregardingthecontentofthisletter,orifadditionalinformationisrequired,pleasecall.Sincerely,EARTHSOLUTIONSNW,LLCcc:D.R.StrongConsultingEngineers,Inc.Attention:Mr.MaherJoudi(Emailonly)Page4KyleR.Campbell,P.E.PrincipalAttachments:PartialSitePlanBoringLog(B-I)MODRETModelingSummaryEarthSolutionsNW,LLC -‘1-C7-f;;:I? JOBNO.339.3CLIENTBORINGNO.DATE.4/6jçBYELEVATIONDRILLINGMETHODSAMPLINGMETHODSHEET(ofHAMMERWEDROP]DRILLINGCONTR.SURFACECONDITIONSDs.iete.’yCcst4care\‘--cQZtek&ht._At_z?.(‘I,)Boringterminatedat_ _____feetbelowexistinggrade.NOGroundwater(tableIseepage)encounteredat______feetduringdhlhng.._JPVCstandpipeinstalledtooftomofboring)feetLower_____feetslotted.Boringbackfihledwithe,Sh>FirkeEarthSolutionsNWLLC 791—2—3—4—6—7—8—9-30-1—2—3—4—5—6—7—8—9—-Boringterminatedatfeetbelowexistinggrade.(NO)Groundwater(tableIseepage)encounteredat______feetduringdrilling._1’PVCstandpipeinstalledto(bottomofboring)feet.Lower______feetslotted.Boringbackfihledwith____________________________________EarthSolutionsNWLLC.JOBNO.CLIENTBORINGNO.DATEBYELEVATIONS—DRILLINGMETHODSAMPLINGMETHODSHEETHAMMERWT.JDROPDRILLINGCONTR.ww0SURFACECONDITIONSi;;—.naw.EEEflD£0cncwE’-tazfLat--ArM’s.en,,tfk-Si-%t.......lLk14St.neiSJ.Sj‘II MODRETSUMMARYOFUNSATURATED&SATURATEDINPUTPARAMETERSPondBottomAreaPondVolumebetweenBottom&DHWLPondLengthtoWidthRatio(L/W)ElevationofEffectiveAquiferBaseElevationofSeasonalHighGroundwaterTableElevationofStartingWaterLevelElevationofPondBottomDesignHighWaterLevelElevationAvg.EffectiveStorageCoefficientofSoilforUnsaturatedAnalysisUnsaturatedVerticalHydraulicConductivityFactorofSafetySaturatedHorizontalHydraulicConductivityAvg.EffectiveStorageCoefficientofSoilforSaturatedAnalysisAvg.EffectiveStorageCoefficientofPond/ExflltrationTrenchHydraulicControlFeatures:TopBottomIsftRightGroundwaterControlFeatures-YINDistancetoEdgeofPondElevationofWaterLevelImperviousBarrier-YINElevationofBarrierBottomNNNN0.000.000.000.000.000.000.000.00NNNN0.000.000.000.00PROJECTNAME:ES-3377.03AlpineNurseryMANUALRUNOFFDATAUSEDUNSATURATEDANALYSISEXCLUDED5,085.00ft227,055.00ft35.50336.00ft336.20ft357.00ft357.00ft361.00ft0.3020.00ft/d2.0060.00ftJd0.251.00AnalysisDate:8/12/2015 MODRETTIME-RUNOFFINPUTDATAAnalysisDate:8/12/201s(H2824.002,426.00PROJECTNAME:ES-3377.03ALPINENURSERYSTRESSINCREMENTVOLUMEPERIODOFTIMEOFRUNOFFNUMBER(hi’s)(ft3)Unsat0,000.00124.002,605.00224.00424.00324.003,828.00424.003,044.00524,00214.00624.003,854.00724.007,926.00824.0077.00924.0012.001024.004,943.001124.0014,424.001224.008,414.001324.00151.001424.00864.001524,00111,297.001624.0024,579.001724.0014,190.001824.005,479.001924.002,627.002024.001,311.002124,00658.002224.00327.002324.00164.002424.004,175.002524.00765.002624.00159,002724.00145.00“Innnnfl MODRETSUMMARYOFRESULTSPROJECTNAME:ES-3377.03AlpineNurseryCUMULATIVEWATERINSTANTANEOUSAVERAGECUMULATIVETIMEELEVATIONINFILTRATIONINFILTRATIONOVERFLOW(hrs)(feet)RATE(ds)RATE(cfs)(ft3)0000-0.00336.2000.000*0.000000.00336.2000.915780.6807624.00357.0000.445730.000.2107148.00357.0000.16979•0.000.1288672.00357.0000.110330.000.0918096.00357.0000.076430.000,06105120.00357.0000.062720.000.06439144.00357.0000.072830.000.08128168.00357.0000.064770.000.04825192.00357.0000.042130.000.03600216.00357.0000.043540.000.05108240.00357.0000.075110.000,09915264.00357.0000.094090.000,08902288.00357.0000.068930.000.04884312.00357.0000.043490.00AnalysisDate:8/12/2015 MODRETSUMMARYOFRESULTSPROJECTNAME:ES-3377.03AlpineNurseryCUMULATIVEWATERINSTANTANEOUSAVERAGECUMULATIVETIMEELEVATIONINFILTRATIONINFILTRATIONOVERFLOW(hrs)(feet)RATE(cl’s)RATE(cl’s)(if3)0.03814336.00357.0000.340540.000.64294360.00357.0000.497800.000.35266384.00357.0000.295510.000.23837408.00357.0000.195010.000.15166432.00357.0000.127420.000.10318456.00357,0000.088500.000.07382480.00357.0000.064440.000.05506504.00357.0000.048860.000.04266528.00357.0000.038480.000.03430552.00357.0000.041650.000.04899576.00357.0000.042060.000.03513600.00357.0000.031160.000.02719624.00357.0000.025170.000.02316648.00357.0000.027340.00AnalysisDate:8/12/2015 MODRETSUMMARYOFRESULTSPROJECTNAME:ES-3377.03AlpineNurseryCUMULATIVEWATERINSTANTANEOUSAVERAGECUMULATIVETIMEELEVATIONINFILTRATIONINFILTRATIONOVERFLOW(hrs)(feet)RATE(cfs)RATE(cfs)(ft3)0.03153672.00357.0000.026760.000.02200696.00343.2520.00MaximumWaterElevation:357.000feet©24,00hoursRecovery©0.000hoursTimeincrementwhenthereisnorunoffMaximumInfiltrationRate:8.696ft/dayAnalysisDate:8/12/2015 •APPENDIX“C”CSWPPP©20160.ftSTRONGConsultingEngineersInc.AlpineNurseryPage70TechnicalInformationReportCityofRenton ConstructionStormwaterGeneralPermitStormwaterPollutionPreventionPlan(SWPPP)forAlpineNurseryPreparedfor:TheWashingtonStateDepartmentofEcologyNorthwestRegionalOffice319016thAvenueSEBellevue,WA98008-5452PermitteeIOwnerDeveloperOperatorIContractorRoyBoyerRoyBoyerTBD14609l6lAvenueSE1460916?tAvenueSESeattle,WA98103Seattle,WA9810316023SEl44hIStreetand14609/14625161stAvenueSE,Renton,WashingtonCertifiedErosionandSedimentControlLead(CESCL)NameOrganizationContactPhoneNumberTBDEarthSolutionsNW,LLC425.284.3300SWPPP_Prepared_ByNameOrganizationContactPhoneNumberMaherA,Joudi,P2DRStrongConsulting(425)827-3063Engineers,Inc.SWPPPPreparationDateSeptember29,2015ProjectConstructionDatesActivity/PhaseStartDateEndDateSiteDevelopmentTBDTBDDR.STRONGConsultingEngineers,Inc.StormwaterPollutionPreventionPlanAlpineNursery TableofContentsProjectInformation.21.1ExistingConditions21.2ProposedConstructionActivities22ConstructionStormwaterBestManagementPractices(BMPs)42.1The12Elements42.1.1Element1:PreserveVegetation/MarkClearingLimits42.1.2Element2:EstablishConstructionAccess52.1.3Element3:ControlFlowRates62.1.4Element4:InstallSedimentControls72.1.5Element5:StabilizeSoils92.1.6Element6:ProtectSlopes102.1.7Element7:ProtectDrainInlets112.1.8Element8:StabilizeChannelsandOutlets122.1.9Element9:ControlPollutants132.1.10Element10:ControlDewatering162.1.11Element11:MaintainBMPs172.1.12Element12:ManagetheProject183PollutionPreventionTeam204MonitoringandSamplingRequirements214.1SiteInspection214.2StormwaterQualitySampling214.2.1TurbiditySampling224.2.2pHSampling235Dischargesto303(d)orTotalMaximumDailyLoad(TMDL)Waterbodies245.1303(d)ListedWaterbodies245.2TMDLWaterbodies246ReportingandRecordKeeping256.1RecordKeeping256.1.1SiteLogBook256.1.2RecordsRetention256.1.3UpdatingtheSWPPP256.2Reporting25621DischargeMonitoringReports256.2.2NotificationofNoncompliance26DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPagei ListofTablesTableI—SummaryofSitePollutantConstituents2Table3—pH-ModifyingSources15Table5—Management18Table7—TeamInformation20Table8—TurbiditySamplingMethod22Table9—pHSamplingMethod23ListofAppendicesA.SiteMapB.BMPDetailC.CorrespondenceD.SiteInspectionFormE.ConstructionStormwaterGeneralPermit(CSWGP)DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageii ListofAcronymsandAbbreviationsAcronymIAbbreviationExplanation303(d)SectionoftheCleanWaterActpertainingtoImpairedWaterbodiesBFOBellingharnFieldOfficeoftheDepartmentofEcologyBMP(s)BestManagementPractice(s)CESCLCertifiedErosionandSedimentControlLeadCO2CarbonDioxideCR0CentralRegionalOfficeoftheDepartmentofEcologyCSWGPConstructionStormwaterGeneralPermitCWACleanWaterActDMRDischargeMonitoringReportDODissolvedOxygenEcologyWashingtonStateDepartmentofEcologyEPAUnitedStatesEnvironmentalProtectionAgencyEROEasternRegionalOfficeoftheDepartmentofEcologyERTSEnvironmentalReportTrackingSystemESCErosionandSedimentControlGULDGeneralUseLevelDesignationNPDESNationalPollutantDischargeEliminationSystemNTUNephelometricTurbidityUnitsNWRONorthwestRegionalOfficeoftheDepartmentofEcologypHPowerofHydrogenRCWRevisedCodeofWashingtonSPCCSpillPrevention,Control,andCountermeasureSUStandardUnitsSWMMEWStormwaterManagementManualforEasternWashingtonSWMMWWStormwaterManagementManualforWesternWashingtonSWPPPStormwaterPollutionPreventionPlanTESCTemporaryErosionandSedimentControlSWROSouthwestRegionalOfficeoftheDepartmentofEcologyTMDLTotalMaximumDailyLoadVFOVancouverFieldOfficeoftheDepartmentofEcologyWACWashingtonAdministrativeCodeWSDOTWashingtonDepartmentofTransportationWWKMWesternWashingtonHydrologyModelDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage1 IProjectInformationProject/SiteName:AlpineNurseryStreet/Location:16023SEl44Streetand14609/1462516lAvenueSECity:RentonState:WAZipcode:98059Subdivision:N/AReceivingwaterbody:LowerCedarRiver1.1ExistingConditionsTotalacreage(includingsupportactivitiessuchasoff-siteequipmentstagingyards,materialstorageareas,borrowareas).Totalacreage:1028Disturbedacreage:9.21Existingstructures:0.85Landscapetopography:3.00(estimate)Drainagepatterns:0.00ExistingVegetation:5.36(estimate)CriticalAreas(wetlands,streams,higherosionStreamandadjacentwetlandrisk,steepordifficulttostabilizeslopes):0.00Listofknownimpairmentsfor303(d)listedorTotalMaximumDailyLoad(TMDL)forthereceivingwaterbody:NoneknownTable1includesalistofsuspectedand/orknowncontaminantsassociatedwiththeconstructionactivity.TableI—SummaryofSitePollutantConstituentsconstituentLocationDepthconcentration(Pollutant)NoknowncontaminantsexistontheSite1.2ProposedConstructionActivitiesTheapplicanthasgainedapprovaltosubdivide9.64acresinto27single—familyresidentiallots(Project),withlotsizesrangingfromapproximately8,000s.f.to12,240s.f.Theproposedimpervioussurfaceincludesaninternalplatroad,Road‘A’,whichwillhaveaproposed53-footrightofwayandwillbeimprovedwith26feetofpavement,verticalcurb,gutter,8-footplanterstripand5-footsidewalk.Theinternalplatroad,SE145mPlace,willhaveaproposed47-footrightofwayandwillbeimprovedwith20feetofpavement,verticalcurb,gutter,8-footplanterstripand5-footsidewalk.Road‘B’willhaveaproposed21-footrightofwayandwillbeimprovedwith20feetofpavement,verticalcurbandgutter.Theimprovementsfromtheinternalplatroadalongwiththeremainingfrontageimprovementswilladdapproximately114,841s.f.(2.64ac)ofimpervioussurface.TDASouth,includingbypassarea,D.R.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage2 willresultinatotalof5.44acofnewimpervioussurfaces.TheremainderoftheTDASouth(3.51ac)willconsistoflandscapingandlawns.ThefrontageimprovementswithinTDANorthwillcreatelessthan10000s.f.ofnewimpervioussurface(5641s.f.total)andlessthan5,000sf.ofpollutiongeneratingimpervioussurface(2,068s.f.total).Theupstreamtributaryareawillbemodeledasexistingconditionsinthedevelopedconditions.Theupstreamtributaryareaconsistsof4,580s.f.(0.105ac)ofimperviousareaand5,220s.f.(0.120ac)oflawn.ConstructionworkwillbecompletedundertheSiteDevelopmentpermit.Activitieswillincludeinstallationofsewer,wateranddryutilities;installationofstormsewer;constructionofstormwaterinfiltrationpond;roadandsidewalks;andlandscapingincludingenhancementplantingofstreambuffer.RunoffwillbecollectedandconveyedtotheproposedinfiltrationpondinTractB,precededbyawetbiofiltrationswaletoaccommodateBasicWaterQualityrequirements.Theprojectwillinfiltrate100%ofthestormwatergenerated.AppendixAshowstheSitePlanwithT.E.S.C.measures.Finalstabilizationofthedisturbedlandwillinclude:•Asphaltroadway•Concretesidewalks•Formallandscapeplanting•StreambufferlandscapeplantingContaminatedSiteInformation:Proposedactivitiesregardingcontaminatedsoilsorgroundwater(example:on-sitetreatmentsystem,authorizedsanitarysewerdischarge):Notapplicableasnoknowncontamination.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage3 2ConstructionStormwaterBestManagementPractices(BMPs)TheSWPPPisalivingdocumentreflectingcurrentconditionsandchangesthroughoutthelifeoftheproject.Thesechangesmaybeinformal(i.e.,hand-writtennotesanddeletions).UpdateSWPPPwhentheCESCLhasnotedadeficiencyinBMPsordeviationfromoriginaldesign.2.1The12ElementsElement1:PreserveVegetationIMarkClearingLimitsToprotectadjacentpropertiesandreducetheareaofsoilexposedtoconstruction,thelimitsofconstructionwillbeclearlymarkedbeforeland-disturbingactivitiesbegin.Treesthataretobepreserved,aswellasallsensitiveareasandtheirbuffers,shallbeclearlydelineated,bothinthefieldandontheplans.Ingeneral,naturalvegetationandnativetopsoilshallberetainedinanundisturbedstatetothemaximumextentpossible.TheBMPsrelevanttomarkingtheclearinglimitsthatwillbeappliedforthisprojectinclude:TheplasticormetalfencewillbeplacedaroundtheperimeterofthedevelopableareaoftheSite.BMPwillbeimplementedatthestartofconstruction.AlternateBMPsformarkingclearinglimitsareincludedinAppendixCasaquickreferencetoolfortheonsiteInspectorintheeventtheBMP(s)listedabovearedeemedineffectiveorinappropriateduringconstructiontosatisfytherequirementssetforthintheGeneralNPDESPermit(AppendixD).Toavoidpotentialerosionandsedimentcontrolissuesthatmaycauseaviolation(s)oftheNPDESConstructionStormwaterpermit(asprovidedinAppendixD),theCESCLwillpromptlyinitiatetheimplementationofoneormoreofthealternativeBMPslistedinAppendixCafterthefirstsignthatexistingBMPsareineffectiveorfailing.ListanddescribeBMPs:HighVisibilityPlasticorMetalFence(BMPC103)SiltFence(BMPC223)InstallationSchedules:Installationwilloccurbeforeallotheractivity.InspectionandMaintenanceplan:WeeklyResponsibleStaff:CESCLDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage4 Element2:EstablishConstructionAccessConstructionaccessoractivitiesoccurringonunpavedareaswillbeminimized,yetwherenecessary,accesspointsshallbestabilizedtominimizethetrackingofsedimentontopublicroads,andwheelwashing,streetsweeping,andstreetcleaningshallbeemployedtopreventsedimentfromenteringstatewaters.Allwashwastewatershallbecontrolledonsite.TheexistingdrivewayonSEI44thStreetwillbeutilizedfortheconstructionentrance.Constructionroadandparkingareastabilizationwilloccuralongtheexistingpaveddriveway.ListanddescribeBMPs:StabilizedConstructionEntrance(BMPC105)ConstructionRoad/ParkingAreaStabilization(BMPC107)InstallationSchedules:Installationwilloccuraftertheclearinglimitsaremarked.InspectionandMaintenanceplan:WeeklyResponsibleStaff:CESCLD.R.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage5 Element3:ControlFlowRatesInordertoprotectthepropertiesandwaterwaysdownstreamoftheprojectsite,stormwaterdischargesfromthesitewillbecontrolled.ThespecificOMPsforflowcontrolthatshallbeusedonthisprojectinclude:.SedimentTrap(BMPC240)TwoSedimentTrapswillbeutilizedduringconstructionasaflowcontrolandsedimentationdevice.Thewesternsedimenttrapwillutilizeanoverflowspillwaytodischargerunofftotheundisturbedtreeretentiontract(TractC).Theeasternsedimenttrapwillutilizeapumptoconveywatertotheundisturbedtreeretentiontract(TractC).Theprojectisproposingtoinfiltrate100%ofthestormwatergenerated.AlternateflowcontrolBMPsareincludedinAppendixCasaquickreferencetoolfortheonsiteinspectorintheeventtheBMP(s)listedabovearedeemedineffectiveorinappropriateduringconstructiontosatisfytherequirementssetforthintheGeneralNPDESPermit(AppendixD).Toavoidpotentialerosionandsedimentcontrolissuesthatmaycauseaviolation(s)oftheNPDESConstructionStormwaterpermit(asprovidedinAppendixD),theCertifiedErosionandSedimentControlLeadwillpromptlyinitiatetheimplementationofoneormoreofthealternativeBMPslistedinAppendixCafterthefirstsignthatexistingBMPsareineffectiveorfailing.TheprojectsiteislocatedwestoftheCascadeMountainCrest.Assuch,theprojectmustcomplywithMinimumRequirement7(Ecology2005).Ingeneral,dischargeratesofstormwaterfromthesitewillbecontrolledwhereincreasesin•imperviousareaorsoilcompactionduringconstructioncouldleadtodownstreamerosion,orwherenecessarytomeetlocalagencystormwaterdischargerequirements(e.g.dischargetocombinedsewersystems).Willyouconstructstormwaterretentionand/ordetentionfacilities?HYesNoWillyouusepermanentinfiltrationpondsorotherlowimpactdevelopment(example:raingardens,bio-retention,porouspavement)tocontrolflowduringconstruction?YesL)NoListanddescribeBMPs:SedimentTraps(BMPC240)BakerTanks(Asnecessary)InstallationSchedules:Installationwilloccurbeforeanygradingoccurs.InspectionandMaintenanceplan:WeeklyResponsibleStaff:CESCLD.R.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage6 Element4:InstallSedimentControlsSiltfencewillbeinstalledaroundtheperimeteroftheSiteinareaswhererunoffcouldsheet-flowoffsite.ThisBMPwillbeinstalledatthestartofconstruction.Theinterceptorswaleswillbeinstalledduringsitegrading.Theinterceptorswaleswillbedirectedtowardsthesedimenttraps.AlternatesedimentcontrolBMPsareincludedinAppendixCasaquickreferencetoolfortheonsiteinspectorintheeventtheBMP(s)listedabovearedeemedineffectiveorinappropriateduringconstructiontosatisfytherequirementssetforthintheGeneralNPDESPermit(AppendixD).Toavoidpotentialerosionandsedimentcontrolissuesthatmaycauseaviolation(s)oftheNPDESConstructionStormwaterpermit(asprovidedinAppendixD),theCertifiedErosionandSedimentControlLeadwillpromptlyinitiatetheimplementationofoneormoreofthealternativeBMPslistedinAppendixCafterthefirstsignthatexistingBMPsareineffectiveorfailing.Inaddition,sedimentwillberemovedfrompavedareasinandadjacenttoconstructionworkareasmanuallyorusingmechanicalsweepers,asneeded,tominimizetrackingofsedimentsonvehicletiresawayfromthesiteandtominimizewashoffofsedimentsfromadjacentstreetsinrunoff.Wheneverpossible,sedimentladenwatershallbedischargedintoonsite,relativelylevel,vegetatedareas(BMPC240paragraph5,page4-102).Insomecases,sedimentdischargeinconcentratedrunoffcanbecontrolledusingpermanentstormwaterBMPs(e.g.,infiltrationswales,ponds,trenches).SedimentloadscanlimittheeffectivenessofsomepermanentstormwaterBMPs,suchasthoseusedforinfiltrationorbiofiltration;however,thoseBMPsdesignedtoremovesolidsbysettling(wetpondsordetentionponds)canbeusedduringtheconstructionphase.WhenpermanentstormwaterBMPswillbeusedtocontrolsedimentdischargeduringconstruction,thestructurewillbeprotectedfromexcessivesedimentationwithadequateerosionandsedimentcontrolBMPs.AnyaccumulatedsedimentshallberemovedafterconstructioniscompleteandthepermanentstormwaterBMPwillberestabilizedwithvegetationperapplicabledesignrequirementsoncetheremainderofthesitehasbeenstabilized,ThefollowingBMPswillbeimplementedasend-of-pipesedimentcontrolsasrequiredtomeetpermittedturbiditylimitsinthesitedischarge(s).Priortotheimplementationofthesetechnologies,sedimentsourcesanderosioncontrolandsoilstabilizationBMPeffortswillbemaximizedtoreducetheneedforend-of-pipesedimentationcontrols.D.R.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage7 ListanddescribeBMPs:BakerTank(Asnecessary)SiltFence(BMPC233)InterceptorSwale(BMPC200)InstallationSchedules:Thesewillallbeinstalledbeforeanygradingoccurs.InspectionandMaintenanceplan:WeeklyResponsibleStaff:CESCLDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage8 Element5:StabilizeSoilsTemporaryseedingandcovermeasuresmayberequiredforinterimgradingactivityandatsoilstockpilesandtheTemporarySedimentTrap.PermanentSeedingwilloccurasgradingiscompleted.Allstabilizedsectionswillbeseededandvegetated.NetsandBlanketsalongwithPlasticCoveringwillbeusedonallslopesof2:1asshownontheplan.DustControlwilloccurthroughoutthesiteasdeemednecessarybythecontractorandCESCL.AlternatesoilstabilizationBMPsareincludedinAppendixCasaquickreferencetoolfortheonsiteinspectorintheeventtheBMP(s)listedabovearedeemedineffectiveorinappropriateduringconstructiontosatisfytherequirementssetforthintheGeneralNPDESPermit(AppendixD).Toavoidpotentialerosionandsedimentcontrolissuesthatmaycauseaviolation(s)oftheNPDESConstructionStormwaterpermit(asprovidedinAppendixD),theCertifiedErosionandSedimentControlLeadwillpromptlyinitiatetheimplementationofoneormoreofthealternativeBMPslistedinAppendixCafterthefirstsignthatexistingBMPsareineffectiveorfailing.Ingeneral,cutandfillslopeswillbestabilizedassoonaspossibleandsoilstockpileswillbetemporarilycoveredwithplasticsheeting.Allstockpiledsoilsshallbestabilizedfromerosion,protectedwithsedimenttrappingmeasures,andwherepossible,belocatedawayfromstormdraininlets,waterways,anddrainagechannels.WestoftheCascadeMountainsCrestNumberofDaysSoilsCanSeasonDatesbeLeftExposedDuringtheDrySeasonMay1—September307daysDuringtheWetSeasonOctober1—April302daysSoilsmustbestabilizedattheendoftheshiftbeforeaholidayorweekendifneededbasedontheweatherforecast.Anticipatedprojectdates:Startdate:TBDEnddate:TBDWillyouconstructduringthewetseason?YesENoListanddescribeBMPs:TemporaryandPermanentSeeding(BMPC120)NetsandBlankets(BMPC122)PlasticCovering(BMPC123)DustControl(BMPC140)InstallationSchedules:Thesewillallbeinstalledbeforeanygradingoccurs.InspectionandMaintenanceplan:WeeklyResponsibleStaff:CESCLD.R.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage9 Element6:ProtectSlopesTemporaryslopeprotectionmeasuresmayberequiredforinterimgradingactivityandatsoilstockpilesandtheTemporarySedimentTrap.PermanentSeedingwilloccurthroughoutthesiteasslopesarestabilized.NetsandBlanketsalongwithPlasticCoveringwillbeusedonallslopesof2:1asshownontheplan.ChecksDamswillbeinstalledevery50asshownontheplan.AlternateslopeprotectionBMPsareincludedinAppendixCasaquickreferencetoolfortheonsiteinspectorintheeventtheBMP(s)listedabovearedeemedineffectiveorinappropriateduringconstructiontosatisfytherequirementssetforthintheGeneralNPDESPermit(AppendixD).Toavoidpotentialerosionandsedimentcontrolissuesthatmaycauseaviolation(s)oftheNPDESConstructionStormwaterpermit(asprovidedinAppendixD),theCertifiedErosionandSedimentControlLeadwillpromptlyinitiatetheimplementationofoneormoreofthealternativeBMPslistedinAppendixCafterthefirstsignthatexistingBMPsareineffectiveorfailing.Willsteepslopesbepresentatthesiteduringconstruction?flYesLNoListanddescribeBMPs:TemporaryandPermanentSeeding(BMPC120)NetsandBlankets(BMPC122)PlasticCovering(BMPC123)CheckDams(BMPC207)InstallationSchedules:Ingeneral,cutandfillslopeswillbestabilizedassoonaspossibleandsoilstockpileswillbetemporarilycoveredwithplasticsheeting.InspectionandMaintenanceplan:WeeklyResponsibleStaff:CESCLD.R.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage10 Element7:ProtectDrainInletsAllstormdraininletsandculvertsmadeoperableduringconstructionshallbeprotectedtopreventunfilteredoruntreatedwaterfromenteringthedrainageconveyancesystem.However,thefirstpriorityistokeepallaccessroadscleanofsedimentandkeepstreetwashwaterseparatefromenteringstormdrainsuntiltreatmentcanbeprovided.StormDrainInletProtection(BMPC220)willbeimplementedforalldrainageinletsandculvertsthatcouldpotentiallybeimpactedbysediment-ladenrunoffonandneartheprojectsite.Thefollowinginletprotectionmeasureswillbeappliedonthisproject:CatchBasinFiltersThereareseveralexistingcatchbasinswhichwillrequirefilters.IftheBMPoptionslistedabovearedeemedineffectiveorinappropriateduringconstructiontosatisfytherequirementssetforthintheGeneralNPDESPermit(AppendixD),orifnoBMPsarelistedabovebutdeemednecessaryduringconstruction,theCertifiedErosionandSedimentControlLeadshallimplementoneormoreofthealternativeBMPinletprotectionoptionslistedinAppendixC.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage11 Element8:StabilizeChannelsandOutletsTheprojectwillnotdischargetoanyoutletsorchannels;therefore,noBMPsarerequired.Providestabilization,includingarmoringmaterial,adequatetopreventerosionofoutlets,adjacentstreambanks,slopes,anddownstreamreaches,willbeinstalledattheoutletsofallconveyancesystems.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage12 Element9:ControlPollutantsAllpollutants,includingwastematerialsanddemolitiondebris,thatoccuronsiteshallbehandledanddisposedofinamannerthatdoesnotcausecontaminationofstormwater.Goodhousekeepingandpreventativemeasureswillbetakentoensurethatthesitewillbekeptclean,well-organized,andfreeofdebris.Ifrequired,BMPstobeimplementedtocontrolspecificsourcesofpollutantsarediscussedbelow.Vehicles,constructionequipment,and/orpetroleumproductstorage/dispensing:•Allvehicles,equipment,andpetroleumproductstorage/dispensingareaswillbeinspectedregularlytodetectanyleaksorspills,andtoidentifymaintenanceneedstopreventleaksorspills.•On-sitefuelingtanksandpetroleumproductstoragecontainersshallincludesecondarycontainment.•Spillpreventionmeasures,suchasdrippans,willbeusedwhenconductingmaintenanceandrepairofvehiclesorequipment.•Inordertoperformemergencyrepairsonsite,temporaryplasticwillbeplacedbeneathand,ifraining,overthevehicle.•Contaminatedsurfacesshallbecleanedimmediatelyfollowinganydischargeorspillincident.Demolition:•Dustreleasedfromdemolishedsidewalks,buildings,orstructureswillbecontrolledusingDustControlmeasures(BMPC140).•Stormdraininletsvulnerabletostormwaterdischargecarryingdust,soil,ordebriswillbeprotectedusingStormDrainInletProtection(BMPC220asdescribedaboveforElement7).•ProcesswaterandslurryresultingfromsawcuttingandsurfacingoperationswillbepreventedfromenteringthewatersoftheStatebyimplementingSawcuttingandSurfacingPollutionPreventionmeasures(BMPC152).Concreteandgrout:•ProcesswaterandslurryresultingfromconcreteworkwillbepreventedfromenteringthewatersoftheStatebyimplementingConcreteHandlingmeasures(BMPC151).Sanitarywastewater:•Portablesanitationfacilitieswillbefirmlysecured,regularlymaintained,andemptiedwhennecessary.SolidWaste:•Solidwastewillbestoredinsecure,clearlymarkedcontainers.Other:•OtherBMPswillbeadministeredasnecessarytoaddressanyadditionalpollutantsourcesonsite.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage13 Theprojectisnotexpectedtoexceedthe1.320gallonstored-fuelthresholdthatrequiresdevelopingaSpillPrevention,Control,andCountermeasure(SPCC)PlanundertheFederalregulationsoftheCleanWaterAct(CWA).ListanddescribeBMPs:DustControlmeasures(BMPC140)ConcreteHandlingmeasures(BMPC151)SawcuttingandSurfacingPollutionPreventionmeasures(BMPC152)StormDrainInletProtection(BMPC220)InstallationSchedules:Immediatelyfollowingorinconjunctionwithactivities.InspectionandMaintenanceplan:WeeklyResponsibleStaff:CESCLWillmaintenance,fueling,and/orrepairofheavyequipmentandvehiclesoccuron-site?FEYesNNoListanddescribeBMPs:N/AInstallationSchedules:N/AInspectionandMaintenanceplan:WeeklyResponsibleStaff:CESCLWillwheelwashortirebathsystemBMPsbeusedduringconstruction?flYesNoListanddescribeBMPs:Presentlynotanticipated.SWPPPtobeamendedifwheelwashprovesnecessary.InstallationSchedules:TBDInspectionandMaintenanceplan:WeeklyResponsibleStaff:CESCLWillpH-modifyingsourcesbepresenton-site?DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage14 YesflNoTable3—pH-ModifyingSourcesListanddescribeBMPs:WashwatertobecontainedandroutedtoBakerTank.SpecificphtreatmentmeasurestobedeterminedbycontractorandCECSL.Presently,CO2spargingordryiceanticipatedapproachifpHmustbealtered.InstallationSchedules:priortoplacementofconcreteInspectionandMaintenanceplan:MonitoringwilloccuratthetimeofconcretewashoperationsResponsibleStaff:CESCLConcretetrucksmustnotbewashedoutontotheground,orintostormdrains,openditches,streets,orstreams.Excessconcretemustnotbedumpedon-site,exceptindesignatedconcretewashoutareaswithappropriateBMPsinstalled.DR.STRONGConsultingEngineers,Inc.StormwaterPollutionPreventionPlanAlpineNurseryLNoneflBulkcementflCementkilndustFlyashTOthercementitiousmaterialsNewconcretewashingorcuringwaters1CWastestreamsgeneratedfromconcretegrindingandsawingfTExposedaggregateprocessesflDewateringconcretevaultsConcretepumpingandmixerwashoutwatersFRecycledconcretefTOther(i.e.,calciumlignosulfate)pleasedescribe:Page15 Element10:ControlDewateringTherewillbenodewateringaspartofthisconstructionproject.Ifexcavationresultsintherequirementofdewatering,thisSWPPPcanbemodifiedtoincludedewateringmeasuresincludingcontrolofdischargewaters.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage16 Element11:MaintainBMPsAlltemporaryandpermanentErosionandSedimentControl(ESC)BMPsshallbemaintainedandrepairedasneededtoensurecontinuedperformanceoftheirintendedfunction.MaintenanceandrepairshallbeconductedinaccordancewitheachparticularBMPspecification(seeVolumeIIoftheSWMMWWorChapter7oftheSWMMEW).VisualmonitoringofallBMPsinstalledatthesitewillbeconductedatleastonceeverycalendarweekandwithin24hoursofanystorrnwaterornon-stormwaterdischargefromthesite.Ifthesitebecomesinactiveandistemporarilystabilized,theinspectionfrequencymaybereducedtoonceeverycalendarmonth.AlltemporaryESCBMPsshallberemovedwithin30daysafterfinalsitestabilizationisachievedorafterthetemporaryBMPsarenolongerneeded.Trappedsedimentshallbestabilizedon-siteorremoved.DisturbedsoilresultingfromremovalofeitherBMPsorvegetationshallbepermanentlystabilized.Additionally,protectionmustbeprovidedforallBMPsinstalledforthepermanentcontrolofstormwaterfromsedimentandcompaction.BMPsthataretoremaininplacefollowingcompletionofconstructionshallbeexaminedandrestoredtofulloperatingcondition.IfsedimententerstheseBMPsduringconstruction,thesedimentshallberemovedandthefacilityshallbereturnedtoconditionsspecifiedintheconstructiondocuments.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage17 Element12:ManagetheProjectProjectmanagementwillincorporatethekeycomponentslistedbelow:Table5—ManagementDesigntheprojecttofittheexistingtopography,soils,anddrainagepatternsEEmphasizeerosioncontrolratherthansedimentcontrolMinimizetheextentanddurationoftheareaexposedKeeprunoffvelocitieslowRetainsedimenton-siteThoroughlymonitorsiteandmaintainallESCmeasuresSchedulemajorearthworkduringthedryseasonflOther(pleasedescribe)AsthisprojectsiteislocatedwestoftheCascadeMountainCrest,theprojectwillbemanagedaccordingtothefollowingkeyprojectcomponents:PhasingofConstruction•Theconstructionprojectisbeingphasedtotheextentpracticableinordertopreventsoilerosion,and,tothemaximumextentpossible,thetransportofsedimentfromthesiteduringconstruction.•Revegetationofexposedareasandmaintenanceofthatvegetationshallbeanintegralpartoftheclearingactivitiesduringeachphaseofconstruction,pertheSchedulingBMP(C162).SeasonalWorkLimitations•FromOctober1throughApril30,clearing,grading,andothersoildisturbingactivitiesshallonlybepermittedifshowntothesatisfactionofthelocalpermittingauthoritythatsilt-ladenrunoffwillbepreventedfromleavingthesitethroughacombinationofthefollowing:oSiteconditionsincludingexistingvegetativecoverage,slope,soiltype,andproximitytoreceivingwaters;andoLimitationsonactivitiesandtheextentofdisturbedareas;andoProposederosionandsedimentcontrolmeasures.•Basedontheinformationprovidedand/orlocalweatherconditions,thelocalpermittingauthoritymayexpandorrestricttheseasonallimitationonsitedisturbance.•Thefollowingactivitiesareexemptfromtheseasonalclearingandgradinglimitations:oRoutinemaintenanceandnecessaryrepairoferosionandsedimentcontrolBMPs;oRoutinemaintenanceofpublicfacilitiesorexistingutilitystructuresthatdonotexposethesoilorresultintheremovalofthevegetativecovertosoil;andoActivitieswherethereis100percentinfiltrationofsurfacewaterrunoffwithinthesiteinapprovedandinstallederosionandsedimentcontrolfacilities.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage18 CoordinationwithUtilitiesandOtherJurisdictions•Carehasbeentakentocoordinatewithutilities,otherconstructionprojects,andthelocaljurisdictioninpreparingthisSWPPPandschedulingtheconstructionwork.lnsnectionandMonitoring•AllBMPsshallbeinspected,maintained,andrepairedasneededtoassurecontinuedperformanceoftheirintendedfunction.Siteinspectionsshallbeconductedbyapersonwhoisknowledgeableintheprinciplesandpracticesoferosionandsedimentcontrol.Thispersonhasthenecessaryskillsto:oAssessthesiteconditionsandconstructionactivitiesthatcouldimpactthequalityofstormwater,andoAssesstheeffectivenessoferosionandsedimentcontrolmeasuresusedtocontrolthequalityofstormwaterdischarges.•ACertifiedErosionandSedimentControlLeadshallbeon-siteoron-callatalltimes.•Wheneverinspectionand/ormonitoringrevealsthattheBMPsidentifiedinthisSWPPPareinadequate,duetotheactualdischargeoforpotentialtodischargeasignificantamountofanypollutant,appropriateBMPsordesignchangesshallbeimplementedassoonaspossible.MaintaininganUrdatedConstructionSWPPP•ThisSWPPPshallberetainedon-siteorwithinreasonableaccesstothesite.•TheSWPPPshallbemodifiedwheneverthereisachangeinthedesign,construction,operation,ormaintenanceattheconstructionsitethathas,orcouldhave,asignificanteffectonthedischargeofpollutantstowatersofthestate.•TheSWPPPshallbemodifiedif,duringinspectionsorinvestigationsconductedbytheowner/operator,ortheapplicablelocalorstateregulatoryauthority,itisdeterminedthattheSWPPPisineffectiveineliminatingorsignificantlyminimizingpollutantsinstormwaterdischargesfromthesite.TheSWPPPshallbemodifiedasnecessarytoincludeadditionalormodifiedBMPsdesignedtocorrectproblemsidentified.RevisionstotheSWPPPshallbecompletedwithinseven(7)daysfollowingtheinspection.•IfBMP(s)aredeemeddonotsatisfytherequirementssetforthintheGeneralNPDESPermit(AppendixD),theCESCLwillpromptlyimplementoneormoreofthealtemativeEMPslistedinAppendixCafterthefirstsignthatexistingBMPsareineffectiveorfailing.•SiteinspectionsandmonitoringwillbeconductedinaccordancewithSpecialConditionS4oftheCSWGP.Samplingwilloccuratthebakertankdischargepiping.•TheSWPPPwillbeupdated,maintained,andimplementedinaccordancewithSpecialConditionsS3,64,and69oftheCSWGP.•AssiteworkprogressestheSWPPPwillbemodifiedroutinelytoreflectchangingsiteconditions.TheSWPPPwillbereviewedmonthlytoensurethecontentiscurrent.•Uponrequest,contractorshallprovidetheDDEandCityofSammamishwithcurrentSWPPP.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage19 3PollutionPreventionTeamTable7—TeamInformationTitlejName(s)PhoneNumberCertifiedErosionandEarthSolutionsNW,LLC425.284.3300SedimentControlLead(CESCL)ResidentEngineerMaherA.Joudi,PE425-827-3063EmergencyEcologyHowardZorzi425-649-7130ContactEmergencyPermifteelRoyBoyer425-766-3066OwnerContactNon-EmergencyOwnerRoyBoyer425-766-3066ContactMonitoringPersonnelEarthSolutionsNW,LLC425.284.3300EcologyRegionalOfficeNorthwestRegion&Office425-649-7000CitySpillHotline(8:00amto425-295-05005:00pm)KingCountySpillHotline206-296-8100(AfterHours)DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage20 4MonitoringandSamplingRequirementsMonitoringincludesvisualinspection,samplingforwaterqualityparametersofconcern,anddocumentationoftheinspectionandsamplingfindingsinasitelogbook.Asitelogbookwillbemaintainedforallon-siteconstructionactivitiesandwillinclude:•ArecordoftheimplementationoftheSWPPPandotherpermitrequirements•Siteinspections•StormwatersamplingdataFileablankformunderAppendix0.Thesitelogbookmustbemaintainedon-sitewithinreasonableaccesstothesiteandbemadeavailableuponrequesttoEcologyorthelocaljurisdiction.Numericeffluentlimitsmayberequiredforcertaindischargesto303(d)listedwaterbodies.SeeCSWGPSpecialConditionS8andSection5ofthistemplate.4.1SiteInspectionAllBMPswillbeinspected,maintained,andrepairedasneededtoassurecontinuedperformanceoftheirintendedfunction.TheinspectorwillbeaCertifiedErosionandSedimentControlLead(CESCL)perBMPC160.ThenameandcontactinformationfortheCESCLisprovidedinSection3ofthisSWPPP.Siteinspectionwilloccurinallareasdisturbedbyconstructionactivitiesandatallstormwaterdischargepoints.Stormwaterwillbeexaminedforthepresenceofsuspendedsediment,turbidity,discoloration,andoilysheen.ThesiteinspectorwillevaluateanddocumenttheeffectivenessoftheinstalledBMPsanddetermineifitisnecessarytorepairorreplaceanyoftheBMPstoimprovethequalityofstormwaterdischarges.Allmaintenanceandrepairswillbedocumentedinthesitelogbookorformsprovidedinthisdocument.AllnewBMPsordesignchangeswillbedocumentedintheSWPPPassoonaspossible.Siteinspectionswillbeconductedatleastonceeverycalendarweekandwithin24hoursfollowinganydischargefromthesite.Forsitesthataretemporarilystabilizedandinactive,therequiredfrequencyisreducedtooncepercalendarmonth.TheprojectdoesnotanticipatetodischargeanystormwaterThesiteinspectorwillrecordeachsiteinspectionusingthesiteloginspectionformsprovidedinAppendixE.ThesiteinspectionlogformsmaybeseparatedfromthisSWPPPdocument,butwillbemaintainedon-siteorwithinreasonableaccesstothesiteandbemadeavailableuponrequesttoEcologyorthelocaljurisdiction.4.2StormwaterQualitySamplingRunoffwillbecollectedandconveyedtotheproposedinfiltrationfacilityinTractB,precededbyawetbiofiltrationswaletoaccommodateBasicWaterQualityrequirements.TheprojectwillDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage21 infiltrate100%ofthestormwatergenerated;howevertestingwilloccurasdeemednecessarybytheCESCLandtheexistingdownstreamcatchbasins.TurbiditySamplingRequirementsincludecalibratedturbiditymeterortransparencytubetosamplesitedischargesforcompliancewiththeCSWGP.Samplingwillbeconductedatalldischargepointsatleastoncepercalendarweek.Methodforsamplingturbidity:Table8—TurbiditySamplingMethodTurbidityMeter/Turbidimeter(requiredfordisturbances5acresorgreaterinsize)IEJTransparencyTube(optionfordisturbanceslessthan1acreandupto5acresinsize)Thebenchmarkforturbidityvalueis25nephelometricturbidityunits(NTU)andatransparencylessthan33centimeters.Ifthedischarge’sturbidityis26to249NTUorthetransparencyislessthan33cmbutequaltoorgreaterthan6cm,thefollowingstepswillbeconducted:1.ReviewtheSWPPPforcompliancewithSpecialCondition59.Makeappropriaterevisionswithin7daysofthedatethedischargeexceededthebenchmark.2.Immediatelybegintheprocesstofullyimplementandmaintainappropriatesourcecontroland/ortreatmentBMPsassoonaspossible.Addresstheproblemswithin10daysofthedatethedischargeexceededthebenchmark.IfinstallationofnecessarytreatmentBMPsisnotfeasiblewithin10days,EcologymayapproveadditionaltimewhenthePermilleerequestsanextensionwithintheinitial10-dayresponseperiod.3.DocumentBMPimplementationandmaintenanceinthesitelogbook.Iftheturbidityexceeds250NTUorthetransparencyis6cmorlessatanytime,thefollowingstepswillbeconducted:1.TelephonetheapplicableEcologyRegion’sEnvironmentalReportTrackingSystem(ERTS)numberwithin24hours.•CentralRegion(Benton,Chelan,Douglas,Kittitas,Klickitat,Okanogan,Yakima):(509)575-2490•EasternRegion(Adams,Asotin,Columbia,Ferry,Franklin,Garfield,Grant,Lincoln,PendOreille,Spokane,Stevens,WallaWalla,Whitman):(509)329-3400•NorthwestRegion(King,Kitsap,Island,SanJuan,Skagit,Snohomish,Whatcom):(425)649-7000•SouthwestRegion(Clallam,Clark,Cowlitz,GraysHarbor,Jefferson,Lewis,Mason,Pacific,Pierce,Skamania,Thurston,Wahkiakumj:(360)407-63002.Immediatelybegintheprocesstofullyimplementandmaintainappropriatesourcecontroland/ortreatmentBMPsassoonaspossible.Addresstheproblemswithin10daysofthedatethedischargeexceededthebenchmark.IfinstallationofnecessaryDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage22 treatmentBMPsisnotfeasiblewithin10days1EcologymayapproveadditionaltimewhenthePermitteerequestsanextensionwithintheinitial10-dayresponseperiod3.DocumentBMPimplementationandmaintenanceinthesitelogbook.4.Continuetosampledischargesdailyuntiloneofthefollowingistrue:•Turbidityis25NTU(orlower).•Transparencyis33cm(orgreater).•Compliancewiththewaterqualitylimitforturbidityisachieved.o1-5NTUoverbackgroundturbidity,ifbackgroundislessthan50NTUo1%-10%overbackgroundturbidity,ifbackgroundis50NTUorgreater•Thedischargestopsoriseliminated.pHSamplingpHmonitoringisrequiredfor‘Significantconcretework”(i.e.,greaterthan1000cubicyardspouredorrecycledconcreteoverthelifeoftheproject).Theuseofengineeredsoils(soilamendmentsincludingbutnotlimitedtoPortlandcement-treatedbase[CTB],cementkilndust[CKD]orflyash)alsorequirespHmonitoring.Forsignificantconcretework,pHsamplingwillstartthefirstdayconcreteispouredandcontinueuntilitiscured,typicallythree(3)weeksafterthelastpour.Forengineeredsoils,pHsamplingbeginswhenengineeredsoilsarefirstexposedtoprecipitationandcontinuesuntiltheareaisfullystabilized.IfthemeasuredpHis8.5orgreater,thefollowingmeasureswillbetaken:1.PreventhighpHwaterfromenteringstormsewersystemsorsurfacewater.2.AdjustorneutralizethehighpHwatertotherangeof6.5to8.5suusingappropriatetechnologysuchascarbondioxide(C02)sparging(liquidordryice).3.WrittenapprovalwillbeobtainedfromEcologypriortotheuseofchemicaltreatmentotherthanCO2spargingordryice.MethodforsamplingpH:Table9—pHSamplingMethodLipHmeterLipHtestkitLiWiderangepHindicatorpaperNot:pHmonitoringequipmentunknownatthistime;tobedeterminedbyCESCLDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage23 5Dischargesto303(d)orTotalMaximumDailyLoad(TMDL)Waterbodies5.1303(d)ListedWaterbodiesIsthereceivingwater303(d)(Category5)listedforturbidity,finesediment,phosphorus,orpH?flYesNoListtheimpairment(s):5.2TMDLWaterbodiesWasteLoadAllocationforCWSGPdischarges:ListanddescribeBMPs:DischargestoTMDLreceivingwaterbodieswillmeetin-streamwaterqualitycriteriaatthepointofdischarge.TheConstructionStormwaterGeneralPermitProposedNewDischargetoanImpairedWaterBodyformisincludedinAppendixF.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage24 6ReportingandRecordKeeping6.1RecordKeepingSiteLogBookAsitelogbookwillbemaintainedforallon-siteconstructionactivitiesandwillinclude:•ArecordoftheimplementationoftheSWPPPandotherpermitrequirements•Siteinspections•SamplelogsRecordsRetentionRecordswillberetainedduringthelifeoftheprojectandforaminimumofthree(3)yearsfollowingtheterminationofpermitcoverageinaccordancewithSpecialConditionS5.CoftheCSWGP.Permitdocumentationtoberetainedon-site:CSWGPPermitCoverageLetter•SWPPP•SiteLogBookPermitdocumentationwillbeprovidedwithin14daysofreceiptofawrittenrequestfromEcology.AcopyoftheSWPPPoraccesstotheSWPPPwillbeprovidedtothepublicwhenrequestedinwritinginaccordancewithSpecialConditionS5.G.2.boftheCSWGP.UpdatingtheSWPPPTheSWPPPwillbemodifiedif:•Foundineffectiveineliminatingorsignificantlyminimizingpollutantsinstormwaterdischargesfromthesite.•Thereisachangeindesign,construction,operation,ormaintenanceattheconstructionsitethathas,orcouldhave,asignificanteffectonthedischargeofpollutantstowatersoftheState.TheSWPPPwillbemodifiedwithinseven(7)daysifinspection(s)orinvestigation(s)determineadditionalormodifiedBMPsarenecessaryforcompliance.AnupdatedtimelineforBMPimplementationwillbeprepared.6.2ReportingDischargeMonitoringReportsCumulativesoildisturbanceisone(1)acreorlarger;therefore,DischargeMonitoringReports(DMRs)willbesubmittedtoEcologymonthly.IftherewasnodischargeduringagivenDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage25 monitoringperiodtheDMRwillbesubmittedasrequired,reporting“NoDischarge”.TheDMRduedateisfifteen(15)daysfollowingtheendofeachcalendarmonth.DMRswillbereportedonlinethroughEcology’sWQWebDMRSystem.NotificationofNoncomplianceIfanyofthetermsandconditionsofthepermitisnotmet,andtheresultingnoncompliancemaycauseathreattohumanhealthortheenvironment,thefollowingactionswillbetaken:1.EcologywillbeimmediatelynotifiedofthefailuretocomplybycallingtheapplicableRegionalofficeERTSphonenumber(Regionalofficenumberslistedbelow).2.Immediateactionwillbetakentopreventthedischarge/pollutionorotherwisestoporcorrectthenoncompliance.Ifapplicable,samplingandanalysisofanynoncompliancewillberepeatedimmediatelyandtheresultssubmittedtoEcologywithinfive(5)daysofbecomingawareoftheviolation.3.AdetailedwrittenreportdescribingthenoncompliancewillbesubmittedtoEcologywithinfive(5)days,unlessrequestedearlierbyEcology.Anytimeturbiditysamplingindicatesturbidityis250NTUsorgreater,orwatertransparencyis6cmorless,theEcologyRegionalofficewillbenotifiedbyphonewithin24hoursofanalysisasrequiredbySpecialCondition55.AoftheCSWGP.•CentralRegionat(509)575-2490forBenton,Chelan,Douglas,Kittitas,Klickitat,Okanogan,orYakimaCounty•EasternRegionat(509)329-3400forAdams,Asotin,Columbia,Ferry,Franklin,Garfield,Grant,Lincoln,PendOreille,Spokane,Stevens,WallaWalla,orWhitmanCounty•NorthwestRegionat(425)649-7000forIsland,King,Kitsap,SanJuan,Skagit,Snohomish,orWhatcomCounty•SouthwestRegionat(360)407-6300forClallam,Clark,Cowlitz,GraysHarbor,Jefferson,Lewis,Mason,Pacific,Pierce,Skamania,Thurston,orWahkiakumIncludethefollowinginformation:1.YournameandIPhonenumber2.Permitnumber3CityICountyofproject4.Sampleresults5.DateITimeofcall6.Date/Timeofsample7.ProjectnameInaccordancewithSpecialConditionS4.D.5.boftheCSWGP,theEcologyRegionalofficewillbenotifiedifchemicaltreatmentotherthanCO2spargingisplannedforadjustmentofhighpHwater.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPage26 AppendixASiteMapDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageA-i NE1/4SECTION23TOWNSHIP23N,RANGE5CWAd.L!I!r1r1H—•ntmDmaaALPINENURSERYMfl7!:iz)_____________—J/:re\,*frcQ__’80‘F’r—::t’1L€I3\:‘\7flfl•dL;ci:mm•—t,fs:LI±’:j;1a:jL_,,%z)LEj”’‘.,74,[c:!I-—HiLT24:N5</c__I__-__I__________________A;Lf,fltt’__________I/----I5I/-Hr-s160ThAvSE,wwr’--E7ii--iIIZrRaoc4mpCONSTRUCPONSEQUENCE:SEDIMENTTRAPIS/ZINCSUMMARY:NO7ES:7ESCLEGENDI.PRE-CONSmUGROYMEETINGTOMAJNTAJNIWOSOYCONTRaMEASURES24THEWCNCHTTRAPWASSlEDP50/CTRYREQLNREMEWTS7.4001170/ALEROSIONCONTROLMEASURESMATBEREQUIREDASDEEMEDCOYSPC/CRONlIMITS27AMANPHMACCORDANCE4/0/APPENDIX0°FTHESURFACESTATEDINAPPENDIXVDTHE2009KCSHOMSECTION/tECSSSARTarCONINSPECIOR.PM7’AqWATERDES/CMMANUALANDMANUFACTURERS01.557•MNCHREQUIRES2083SrOFSURFACEAREAPEP2.ALLa/S/ISEASTTNCIMPR0tMOST3TUBERCHD’!O.REINFORCEDSILTPENCEREQUIREDNOTICEOFCa/STRUtfaAUQTQPECDMMENOAIONS95OF/24/5000*0/WASCALCESATEDUS/ASPORTS(13LiLiSFLAGORFENCECEEAP/NCLIMITSANDPR/N/NETREEYV’IEPS)TOANALTIE‘REXEL0/EDslYFENCENOTE:STABILIZEDCO/STRUCTTON0/TRANCEPROWCRO/CA/ANtETHEEROSOYANDSEQ/MINTcCRDIaLsP010FENCE/SREQUIREDDURINGCONSTRUCTION,SEESlEETC28FOR4INSTALLCA7CMMA/NIPROTECT/NFlIFREQ/I/REDALWAYSINACCORDANCEMATHTHE0775EROS/ONmAN(CATCUMUITAREA’5933AC.)PETALSOUSTCONTROLSGRADEANDINSTALLCONSTRUCTIONENTRANCE(SDISTURBANCEAREA‘€NC/LOINSMA171N5*COMPOSTBLANKETSNOIYI—IB.INSTALLPERII9ETTRPROTECTION(SETFENCEMORETHANSKIEROATSPUN/NOTHEORESEASONOR5/379AGNESGRAPHICSCALEBRUSMBANNER,ETC)1740OATSDURINGTHEArTSEASON4/0/STRAINSEDIMENTTRAP2SIZINGSUMMARINLETPROTECTION02540ES7,Ca/S‘mitTSEDIMENTPONDSANDTRAPSULDt1Wt/N.RASRCS’EETS’GONpTHANWASJ,pgJTPAJQQ/jrANDP’AJWNG8GRADEANDSTABLI2ECO/STHUCP01ROADSSTATED‘NAPPENDIXU’OFTHE2002KCSAOMSECTION1INCH40FTB.CONSTRUCTSURFACEWATSRCONTROLS755TABILIAEALLAREASTHATREACHFINALGRAPE0,1STWICKREQUIRES2080S.F.OPSURFACEAREAPER3’STREETSB€ENNG&VACUUM/NOM,ACLEA4/N7ANDCRAO/VnHTOREMANUFIRSARYSSYALYZEnlExwLrwsir.._____Sw/NE4/rnROtA04/OPPAMRECOMMENDEDFORAPPDVALTiUPONCOMPLETIONQPTHEPR&LCTIALL72’MARTWLRSRTJOYDete:,.__.DISTURBEDAREASMUSTBESTABILIZEDANDBlIPSTRAP(CATCHMENTAREA:2.939AC)IREM/NEDIFAPPROPRIATE2IEARPEAKP5PNRATCt72OSTREEPROWCPZEAPENC5SEEOEM/CSHEETI01PRPROWSURFACEAPE/N..,..,:7800£FREMDPEEATSTTNGSTRUCTUREI0’DaIe:___._ImaTOBEREM/NWf’y,,,,,,,,‘ç’,(\I011eIUAn.REVIEWIMEl03.051611430/72IIIMN‘PPUR.STRONGOw01wunen.Rntwz—RUan’.MUASNOTED.-CITYOFALPINENURSERY09.28,15:::i::::\i!brrsjzRuala’..u:;.Ia1PIonning/BUiI/[ng/Pub/cWorksDtpLCLEARINGANDWSCPLANci(C.MV.IC.WAE‘ORAL\.ojCJEDYDIAWA3NQ.RXIS.C7IBYDATEAPPR‘S_F”U150073667-.42DRSPROJECTNo.14069AI—NNIN1r’44l6 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__ __ __ __ __ __ __ __ __5473114130?811I38471831382.8.79/1Nun143111381883270.7,?4?%84944j588341101181801288/104813401)8118143100483184315114‘410011871114731181152838/340841616-513304977880311348777116131083030‘0800350,7833?47048475-01788440014808fl1415350*111004’’S88888lt011968048888:“04oZSs04?Ow0I$0h*118898841358•080798814192NflA404080811T5(1011V3UI3dS5310(17OWNOON0$0?0700413)01?O3NWNINSNOulflfl?413N03401112)47043345—“40/808/fl?074087388404776404780400084)181038’98/7804044?018.1sdI)43458)l4)8413,00,841868858411419989fl9288144409fl7080rn1%.n•9i)7981048100471)80111404168)[048018144814088115747*478841108077380.9261468079/271fl670849fl76048180318*5041*4241998O4850TIII4SCM$804flfl0089848404730104816408)8041000100008494896014440404787414:47140111)0?86891371981--4K,—878780750447143)1470—yj.50145/111858151041330179898/9901-%1484808,81#01,848088094989/9/4l?987618408090)081871N1Ad3SdflNBN/d7VPCM‘3g3DNVd‘NCedIHSNMOI‘CeNOIIO3Si-/s3N2—-73113781>-ar2Ph2CU)Ph-<rCmlCr00C0-a AppendixBBMPDetailsDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageB-i BMPClOl:PreservingNaturalVegetationPurposeThepurposeofpreservingnaturalvegetationistoreduceerosionwhereverpracticable.Limitingsitedisturbanceisthesinglemosteffectivemethodforreducingerosion.Forexample,coniferscanholduptoabout50percentofallrainthatfallsduringastorm.Upto20-30percentofthisrainmayneverreachthegroundbutistakenupbythetreeorevaporates.Anotherbenefitisthattherainheldinthetreecanbereleasedslowlytothegroundafterthestorm.ConditionsofUseNaturalvegetationshouldbepreservedonsteepslopes,nearperennialandintermittentwatercoursesorswales.andonbuildingsitesinwoodedareas.•Asrequiredbylocalgovernments.•Phaseconstructiontopreservenaturalvegetationontheprojectsiteforaslongaspossibleduringtheconstructionperiod.DesignandNaturalvegetationcanbepreservedinnaturalclumpsorasindividualInstallationtrees.shrubsandvines.SpecfficationsThepreservationofindividualplantsismoredifficultbecauseheavyequipmentisgenerallyusedtoremoveunwantedvegetation.Thepointstorememberwhenattemptingtosaveindividualplantsare:•Istheplantworthsaving?Considerthelocation,species,size,age,vigor,andtheworkinvolved.Localgovernmentsmayalsohaveordinancestosavenaturalvegetationandtrees.•Fenceorclearlymarkareasaroundtreesthataretobesaved.Itispreferabletokeepgrounddisturbanceawayfromthetreesatleastasfaroutasthedripline.Plantsneedprotectionfromthreekindsofinjuries:•Constructionuimen!—Thisinjury’canbeaboveorbelowthegroundlevel.Damageresultsfromscarring,cuttingofroots,andcompactionofthesoil.Placingafencedbufferzonearoundplantstobesavedpriortoconstructioncanpreventconstructionequipmentinjuries.•GraeCanes-Changingthenaturalgroundlevelwillaltergrades,whichaffectstheplant’sabilitytoobtainthenecessaryair,water,andminerals.Minorfillsusuallydonotcauseproblemsalthoughsensitivitybetweenspeciesdoesvaryandshouldbechecked.Treescantypicallytoleratefillof6inchesorless.Forshrubsandotherplants,thefillshouldbeless.Whentherearemajorchangesingrade,itmaybecomenecessarytosupplyairtotherootsofplants.Thiscanbedonebyplacingalayerofgravelandatilesystemovertherootsbeforethefillismade.Atilesystemprotectsatreefromaraisedgrade.ThetilesystemshouldbeohmicConstructionStonnii’aterPollutionPreen/ionitus!2012 laidoutontheoriginalgradeleadingfromadryvellaroundthetreetrunk.Thesystemshouldthenbecoveredwithsmallstonestoallowairtocirculateovertherootarea.Loweringthenaturalgroundlevelcanseriouslydamagetreesandshrubs.Thehighestpercentageoftheplantrootsareintheupper12inchesofthesoilandcutsofonly2-3inchescancauseseriousinjury.Toprotecttherootsitmaybenecessarytoterracetheimmediateareaaroundtheplantstobesaved.Ifrootsareexposed,constructionofretainingwallsmaybeneededtokeepthesoilinplace.Plantscanalsobepreservedbyleavingthemonanundisturbed,gentlyslopingmound.Toincreasethechancesforsurvival,itisbesttolimitgradechangesandothersoildisturbancestoareasoutsidethedriplineoftheplant.cc;citiolls-Protecttreesandotherplantswhenexcavatingfordrainfields,power,water,andsewerlines.Wherepossible,thetrenchesshouldberoutedaroundtreesandlargeshrubs.Whenthisisnotpossible,itisbesttotunnelunderthem.Thiscanbedonewithhandtoolsorwithpoweraugers.Ifitisnotpossibletoroutethetrencharoundplantstobesaved,thenthefollowingshouldbeobserved:Cutasfewrootsaspossible.Whenyouhavetocut,cutclean.Paintcutrootendswithawooddressinglikeasphaltbasepaintifrootswillbeexposedformorethan24-hours.Backfillthetrenchassoonaspossible.Tunnelbeneathrootsystemsasclosetothecenterofthemaintrunktopreservemostoftheimportantfeederroots.Someproblemsthatcanbeencounteredwithafewspecifictreesare:•Maple,Dogwood,Redalder,Westernhemlock,Westernredcedar,andDouglasfirdonotreadilyadjusttochangesinenvironmentandspecialcareshouldbetakentoprotectthesetrees.•ThewindthrowhazardofPacificsilverfirandmadronaishigh,whilethatofWesternhemlockismoderate.Thedangerofwindthrowincreaseswheredensestandshavebeenthinned.Otherspecies(unlesstheyareonshallow,wetsoilslessthan20inchesdeep)havealowwindthrowhazard.•Cottonwoods,maples,andwillowshavewater-seekingroots.Thesecancausetroubleinsewerlinesandinfiltrationfields.Ontheotherhand,theythriveinhighmoistureconditionsthatothertreeswouldnot.•ThinningoperationsinpureormixedstandsofGrandfir,Pacificsilverfir.Noblefir.Sitkaspruce,Westernredcedar,Westernhemlock,Pacificdogwood,andRedaldercancauseseriousdiseaseproblems.Diseasecanbecomeestablishedthroughdamagedlimbs,trunks,roots,olzmwConstructionS/or,niratc;PollutionPrecut/oniius!2012 andfreshlycutstumps.Diseasedandweakenedtreesarealsosusceptibletoinsectattack.MaintenanceInspectflaggedand/orfencedareasregularlytomakesureflaggingorStandardsfencinghasnotbeenremovedordamaged.Iftheflaggingorfencinghasbeendamagedorvisibilityreduced,itshallberepairedorreplacedimmediatelyandvisibilityrestored.•Iftreerootshavebeenexposedorinjured.“prune”cleanlywithanappropriatepruningsaworlopersdirectlyabovethedamagedrootsandrecoverwithnativesoils.Treatmentofsapflowingtrees(fir.hemlock,pine,softmaples)isnotadvisedassapformsanaturalhealingbarrier.BMPC102:BufferZonesPurposeCreationclanundisturbedareaorstripofnaturalvegetationoranestablishedsuitableplantingthatwillprovidealivingfiltertoreducesoilerosionandrunoffvelocities.conditionsofUseNaturalbufferzonesareusedalongstreams.wetlandsandotherbodiesofwaterthatneedprotectionfromerosionandsedimentation.Vegetativebufferzonescanbeusedtoprotectnaturalswalesandcanbeincorporatedintothenaturallandscapingofanarea.Critical-areasbufferzonesshouldnotbeusedassedimenttreatmentareas.Theseareasshallremaincompletelyundisturbed.Thelocalpermittingauthoritymayexpandthebufferwidthstemporarilytoallowtheuseoftheexpandedareaforremovalofsediment.Designand•Preservingnaturalvegetationorplantingsinclumps,blocks,orstripsInstallationisgenerallytheeasiestandmostsuccessfulmethod.Specjfications•Leaveallunstablesteepslopesinnaturalvegetation.•Markclearinglimitsandkeepallequipmentandconstructiondebrisoutofthenaturalareasandbufferzones.Steelconstructionfencingisthemosteffectivemethodinprotectingsensitiveareasandbuffers.Alternatively,wire-backedsiltfenceonsteelpostsismarginallyeffective.Flaggingaloneistypicallynoteffective.•Keepallexcavationsoutsidethedriplineoftreesandshrubs.•Donotpushdebrisorextrasoilintothebufferzoneareabecauseitwillcausedamagefromburyingandsmothering.•Vcgetativcbufferzoncsforstreams,lakesorotherwaterwaysshallbcestablishedbythelocalpermittingauthorityorotherstateorfederalpermitsorapprovals.MaintenanceInspecttheareafrequentlytomakesureflaggingremainsinplaceandtheStandardsarearemainsundisturbed.Replacealldamagedflaggingimmediately.ohmicConstructionS!ornni’citerPollutionPiecottonUus!20)2 BMPC103:HighVisibilityFencePurposeFencingisintendedto:1.Restrictclearingtoapprovedlimits.2.Preventdisturbanceofsensitiveareas,theirbuffers,andotherareasrequiredtobeleftundisturbed.3.Limitconstructiontraffictodesignatedconstructionentrances,exits,orinternalroads.4.Protectareaswheremarkingwithsurveytapemaynotprovideadequateprotection.(‘auditionsofUseToestablishclearinglimitsplastic.fabric,ormetalfencemaybeused:•Attheboundaryofsensitiveareas,theirbuffers,andotherareasrequiredtobeleftuncleared.•Asnecessarytocontrolvehicleaccesstoandonthesite.DesignandHighvisibilityplasticfenceshallbecomposedofahigh-densityInstallationpolyethylenematerialandshallbeatleastfourfeetinheight.PostsforSpecjficationsthefencingshallbesteelorwoodandplacedevery6feetoncenter(maximum)orasneededtoensurerigidity.Thefencingshallbefastenedtotheposteverysixincheswithapolyethylenetie.Onlongcontinuouslengthsoffencing,atensionwireorropeshallbeusedasatopstringertopreventsaggingbetweenposts.Thefencecolorshallbehighvisibilityorange.Thefencetensilestrengthshallbe360lbs./ft.usingtheASTMD4595testingmethod.IfappropriateinstallfabricsiltfenceinaccordancewithBMPC233toactashighvisibilityfence.Siltfenceshallbeatleast3feethighandmustbehighlyvisibletomeettherequirementsofthisBMP.Metalfencesshallbedesignedandinstalledaccordingtothemanufacturer’sspecifications.Metalfencesshallbeatleast3feethighandmustbehighlyvisible.Fencesshallnotbewiredorstapledtotrees.MaintenanceIfthefencehasbccndamagedorvisibilityreduccd.itshallbcrepairedorStandardsreplacedimmediatelyandvisibilityrestored.ohmicConstructionStornni’a!erPollutionPieen/ioniius!2012 BMPC105:StabilizedConstructionEntrance!ExitPurposeStabilizedConstructionentrancesareestablishedtoreducetheamountofsedimenttransportedontopavedroadsbyvehiclesorequipment.Thisisdonebyconstructingastabilizedpadofquarryspallsatentrancesandexitsforconstructionsites.conditionsofUseConstructionentrancesshallbestabilizedwherevertrafficwillbeenteringorleavingaconstructionsiteifpavedroadsorotherpavedareasarewithin1.000feelofthesite.Forresidentialconstructionprovidestabilizedconstructionentrancesforeachresidence,ratherthanonlyatthemainsubdivisionentrance.Stabilizedsurfacesshallbeofsufficientlength/widthtoprovidevehicleaccess/parking,basedonlotsize/configuration.Onlargecommercial,highway,androadprojects,thedesignershouldincludeenoughextramaterialsinthecontracttoallowforadditionalstabilizedentrancesnotshownintheinitialConstructionSWPPP.Itisdifficulttodetermineexactlywhereaccesstotheseprojectswilltakeplace;additionalmaterialswillenablethecontractortoinstallthemwhereneeded.DesignandSeeFigure4.1.1fordetails.Note:the100’minimumlengthoftheInstallationentranceshallbereducedtothemaximumpracticablesizewhenthesizeSpecjflcationsorconfigurationofthesitedoesnotallowtheMIlength(100’).Constructstabilizedconstructionentranceswitha12-inchthickpadof4-inchto8-inchquarryspalls.a4-inchcourseofasphalttreatedbase(ATB),oruseexistingpavement.Donotusecrushedconcrete,cement,orcalciumchlorideforconstructionentrancestabilizationbecausetheseproductsraisepHlevelsinstormwaterandconcretedischargetosurfacewatersoftheStateisprohibited.Aseparationgeotextileshallbeplacedunderthespallstopreventfinesedimentfrompumpingupintotherockpad.Thegeotextileshallmeetthefollowingstandards:GrabTensileStrength(ASTMD4751)200psimm.GrabTensileElongation(ASTM30%max.D4632)MullenBurstStrength(ASTM400psimm.D3786-80a)AOS(ASTMD4751)20-45(U.S.standardsievesize)•Considerearlyinstallationofthefirstliftofasphaltinareasthatwillpaved;thiscanbeusedasastabilizedentrance.Alsoconsidertheinstallationofexcessconcreteasastabilizedentrance.Duringlargeconcretepours,excessconcreteisoftenavailableforthispurpose.ohiineConstructionStornni’aterPollutionPrc’entioniiitct2012 •Fencing(seeBMPC103)shallbeinstalledasnecessarytorestricttraffictotheconstructionentrance.•Wheneverpossible,theentranceshallbeconstructedonafirm,compactedsubgrade.Thiscansubstantiallyincreasetheeffectivenessofthepadandreducetheneedformaintenance.•Constructionentrancesshouldavoidcrossingexistingsidewalksandbackofwalkdrainsifatallpossible.Ifaconstructionentrarwemustcrossasidewalkorbackofwalkdrain,thefulllengthofthesidewalkandbackofwalkdrainmustbecoveredandprotectedfromsedimentleavingthesite.MaintenanceQuarryspallsshallbeaddedifthepadisnolongerinaccordancewithStandardsthespecifications.•Iftheentranccisnotpreventingsedimentfrombeingtrackedontopavement,thenalternativemeasurestokeepthestreetsfreeofsedimentshallbeused.Thismayincludereplacement/cleaningoftheexistingquarryspalls,streetsweeping,anincreaseinthedimensionsoftheentrance,ortheinstallationofawheelwash.•Anysedimentthatistrackedontopavementshallberemovedbyshovelingorstreetsweeping.Thesedimentcollectedbysweepingshallberemovedorstabilizedonsite.Thepavementshallnotbecleanedbywashingdownthestreet,exceptwhenhighefficiencysweepingisineffectiveandthereisathreattopublicsafety.Ifitisnecessarytowashthestreets,theconstructionofasmallsumptocontainthewashwatershallbeconsidered.Thesedimentwouldthenbewashedintothesumpwhereitcanbecontrolled.•Performstreetsweepingbyhandorwithahighefficiencysweeper.Donotuseanon-highefficiencymechanicalsweeperbecausethiscreatesdustandthrowssoilsintostormsystemsorconveyanceditches.•Anyquarryspallsthatareloosenedfromthepad,whichendupontheroadwayshallberemovedimmediately.•Ifvehiclesareenteringorexitingthesiteatpointsotherthantheconstructionentrance(s),fencing(seeBMPC103)shallbeinstalledtocontroltraffic.•Uponprojectcompletionandsitestabilization,allconstructionaccessesintendedaspermanentaccessformaintenanceshallbepermanentlystabilized.obtincCo,zs!ruc/ionS/orinwa!erPot/it/ionPreentioniius!2012 Figure4.1.1—StabilizedConstructionEntranceApprovedasEquivalei#EcologyhasapprovedproductsasabletomeettherequirementsofBMPC]05.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecv.wa.cov/programs/vg/stormwater/newtech/eguivalent.htmlBMPC106:WheelWashPurposeConditionsofUseWheelwashesreducetheamountofsedimenttransportedontopavedroadsbymotorvehicles.‘Whenastabilizedconstructionentrance(seeBMPC105)isnotpreventingsedimentfrombeingtrackedontopavement.WheelwashingisgcncrallyancffectivcBMPwheninstallcdwithcarefulattentiontotopography.Forexample,awheelwashcanbedetrimentalifinstalledatthetopofaslopeabuttingaright-of-waywherethewaterfromthedrippingtruckcanrununimpededintotheStreet.DiwayshaltmeetIrerequirementsofthepermittingagencyisrecommendedthattheentrancebecrownedsothatrunoffdrainsoffthepad-ltnsitdrivewaycutveriif?‘&eisaroadsideditchpresent4’—8’quarryspattsGeolextire17mm.thicknessPrcvdeluwidthoftgressJegressareaohinwConstructionStornnt’aterPollutionPreen/ioniiILV/2012 •Pressurewashingcombinedwithanadequatelysizedandsurfacedpadwithdirectdrainagetoalarge10-footx10-footsumpcanbevery’effective.•Dischargewheelwashortirebathwastewatertoaseparateon-sitetreatmentsystemthatpreventsdischargetosurfacewater,suchasclosed-looprecirculationoruplandlandapplication,ortothesanitarysewerwithlocalsewerdistrictapproval.•Wheelwashortirebathwastewatershouldnotincludewastewaterfromconcretewashoutareas.DesignandSuggesteddetailsareshowninFigure4.1.2.TheLocalPermittingInstallationAuthoritymayallowotherdesigns.Aminimumof6inchesofasphaltSpecjflcauonstreatedbase(ATB)overcrushedbasematerialor8inchesoveragoodsubgradeisrecommendedtopavethewheelwash.Usealowclearancetrucktotestthewheelwashbeforepaving.Eitherabellydumporlowboywillworkwelltotestclearance.Keepthewaterlevelfrom12to14inchesdeeptoavoiddamagetotruckhubsandfillingthetrucktongueswithwater.Midpointspraynozzlesareonlyneededinextremelymuddyconditions.Wheelwashsystemsshouldbedesignedwithasmallgradechange,6-to1-inchesfora10-foot-widepond,toallowsedimenttoflowtothelowsideofpondtohelppreventre-suspensionofsediment.Adrainpipewitha2-to3-footrisershouldbeinstalledonthelowsideofthepondtoallowforeasycleaningandrefilling.Polymersmaybeusedtopromotecoagulationandflocculationinaclosed-loopsystem.Polyacrylamide(PAM)addedtothewheelwashwateratarateof0.25-0.5poundsper1,000gallonsofwaterincreaseseffectivenessandreducescleanuptime.IfPAMisalreadybeingusedfordustorerosioncontrolandisbeingappliedbyawatertruck,thesametruckcanbeusedtochangethewashwater.MaintenanceThewheelwashshouldstartoutthedaywithfreshwater.StandardsThewashwatershouldbechangcdaminimumofonceperday.Onlargeearilworkjobswheremorethan10-20trucksperhourareexpected,the‘ashwaterwillneedtobechangedmoreoften.ohe;;wConstructionStonmi’ate,PollutionPreeu/ioniius!201210 ‘‘i[jMIDPOINTSPRAYNOZZLESJEDEDI2%s7I___iIIENEL1:11SLOPE-SLOPE,II2XSLOPEII-‘t—CAmCONSTRUCtONSLOPEACICTRANCE15’ATBAPRONTOPROTECTASPHALTCURBONTHEGROUNDFROMSPLASHINGWATERLOWROADSIDETODIRECT5SLEEVEUNDERROADWATERSACKTOPONDIPLANViEW]I_15_l15-2OI_15’__50Notes:Figure4.1.2—WheelWashI.Asphaltconstructionentrance6in.asphalttreatedbase(ATB).2.3-inchtrashpumpwithfloatsonthesuctionhose.3.Midpointspraynozzles,ifneeded.4.6-inchsewerpipewithbutterflyvalves.Bottomoneisadrain.Locatetoppipe’sinvert1footabovebottomofwheelwash.5.8footx8footsumpwith5feetofcatch.Buildsothesumpcanbecleanedwithatrackhoe.6.Asphaltcurbonthelowroadsidetodirectwaterbacktopond.7.6-inchsleeveunderroad.8.Ballvalves.9.15foot.ATBaprontoprotectgroundfromsplashingwater.ohuneConstructionStormu’a!erPollutionPieen/ionxius!20126SEWERPIPEWITHBU1TERFLYVALVES—WxB’SUMPWITH5’OFCATCH3TRASHPUMPWITHFLOATSAONSUCTIONHOSE—2SCHEDULE40l—T/2SCHEDULE40-FORSPRAYERSIIIICSLEEVEIELEVA11ONV1EWILOCATEINVERTOFTOPPIPE1•ABOVEBOTTOMOFWHEELWASHSxS’SWAP•‘N%‘\\WATERLEVEL4,I.3’5.DRAINPIPEISECT1ONA—AlNOTES:11SLOPE1.BUILDB’xWSUMPTOACCOMODATECLEANINGBYTRACKHOE.11 BMPC107:ConstructionRoadlParkingAreaStabilizationPurposeStabilizingsubdivisionroads,parkingareas,andotheron-sitevehicletransportationroutesimmediatelyaftergradingreduceserosioncausedbyconstructiontrafficorrunoff.ConditionsofUseRoadsorparkingareasshallbestabilizedwherevertheyareconstructed,whetherpermanentortemporary,forusebyconstructiontraffic.HighVisibilityFencing(seeBMPC103)shallbeinstalled,ifnecessary,tolimittheaccessofvehiclestoonlythoseroadsandparkingareasthatarestabilized.Designand•Onareasthatwillreceiveasphaltaspartoftheproject,installthefirstInstallationliftassoonaspossible.Specj,flcationsA6-inchdepthof2-to4-inchcrushedrock,gravelbase,orcrushedsurfacingbasecourseshallbeappliedimmediatelyaftergradingorutilityinstallation.A4-inchcourseofasphalttreatedbase(ATB)mayalsobeused,ortheroad/parkingareamaybepaved.Itmayalsobepossibletousecementorcalciumchlorideforsoilstabilization.Ifcementorcementkilndustisusedforroadbasestabilization,pHmonitoringandBMPs(BMPsC252andC253)arenecessarytoevaluateandminimizetheeffectsonstormwater.Iftheareawillnotbeusedforpermanentroads,parkingareas,orstructures,a6-inchdepthofhogfuelmayalsobeused,butthisislikelytorequiremoremaintenance.Wheneverpossible,constructionroadsandparkingareasshallbeplacedonafirm,compactedsubgrade.•Temporaryroadgradientsshallnotexceed15percent.Roadwaysshallbecarefullygradedtodrain.Drainageditchesshallbeprovidedoneachsideoftheroadwayinthecaseofacrownedsection,orononesideinthecaseofasuper-elevatedsection.DrainageditchesshallbedirectedtoasedimentcontrolBMP.•Ratherthanrelyingonditches,itmayalsobepossibletogradetheroadsothatrunoffsheet-flowsintoaheavilyvegetatedareawithawell-developedtopsoil.Landscapedareasarenotadequate.Ifthisareahasatleast50feetofvegetationthatwatercanflowthrough,thenitisgenerallypreferabletousethevegetationtotreatrunoff,ratherthanasedimentpondortrap.The50feetshallnotincludewetlandsortheirbuffers.Ifrunoffisallowedtosheetfiowthroughadjacentvegetatedareas,itisvitaltodesigntheroadwaysandparkingareassothatnoconcentratedrunoffiscreated.•Stormdraininletsshallbeprotectedtopreventsediment-ladenwaterenteringthestormdrainsystem(seeBMPC220).MaintenanceInspectstabilizedarcasregularly,especiallyafterlargestormevents.StandardsCrushedrock,gravelbase,etc.shallbeaddedasrequiredtomaintainaohmicConstrue/iouStonnwa/erPollutionPieen/ionuus!201212 stabledrivingsurfaceandtostabilizeanyareasthathaveeroded.Followingconstruction,theseareasshallberestoredtopre-constructionconditionorbettertopreventfutureerosion.Performstreetcleaningattheendofeachdayormoreoftenifnecessary.BMPC120:TemporaryandPermanentSeedingPurposeSeedingreduceserosionbystabilizingexposedsoils.Awell-establishedvegetativecoverisoneofthemosteffectivemethodsofreducingerosion.conditionsofUseUseseedingthroughouttheprojectondisturbedareasthathavereachedfinalgradeorthatwillremainunworkedformorethan30days.TheoptimumseedingwindowsforwesternWashingtonareApril1throughJune30andSeptember1throughOctober1.BetweenJuly1andAugust30seedingrequiresirrigationuntil75percentgrasscoverisestablished.BetweenOctober1andMarch30seedingrequiresacoverofmulchwithstraworanerosioncontrolblanketuntil75percentgrasscoverisestablished.ReviewalldisturbedareasinlateAugusttoearlySeptemberandcompleteallseedingbytheendofSeptember.Otherwise,vegetationwillnotestablishitselfenoughtoprovidemorethanaverageprotection.•Mulchisrequiredatalltimesforseedingbecauseitprotectsseedsfromheat,moistureloss,andtransportduetorunoff.Mulchcanbeappliedontopoftheseedorsimultaneouslybyhydroseeding.SeeBMPC121:Mulchingforspecifications.•Seedandmulch,alldisturbedareasnototherwisevegetatedatfinalsitestabilization.Finalstabilizationmeansthecompletionofallsoildisturbingactivitiesatthesiteandtheestablishmentofapermanentvegetativecover,orequivalentpermanentstabilizationmeasures(suchaspavement,riprap,gabionsorgeotextiles)whichwillpreventerosion.DesignandSeedretention/detentionpondsasrequired.Installation..InstallchannelsintendedforvegetationbeforestartingmajorSpecificationsearthworkandhydroseedwithaBondedFiberMatrix.Forvegetatedchannelsthatwillhavehighflows,installerosioncontrolblanketsoverhydroseed.Beforeallowingwatertoflowinvegetatedchannels,establish75percentvegetationcover.Ifvegetatedchannelscannotbeestablishedbyseedbeforewaterflow;installsodinthechannelbottom—overhydromulchanderosioncontrolblankets.ohuneConstructionStormit’cg!erPollutionPreentionitus!2012I •Confirmtheinstallationofallrequiredsurfacewatercontrolmeasurestopreventseedfromwashingaway.•1-lydroseedapplicationsshallincludeaminimumof1,500poundsperacreofmulchwith3percenttackifier.SeeBMPC121:Mulchingforspecifications.•Areasthatwillhaveseedingonlyandnotlandscapingmayneedcompostormeal-basedmulchincludedinthehydroseedinordertoestablishvegetation.Re-installnativetopsoilonthedisturbedsoilsurfacebeforeapplication.•Wheninstallingseedviahydroseedingoperations,onlyabout1/3oftheseedactuallyendsupincontactwiththesoilsurface.Thisreducestheabilitytoestablishagoodstandofgrassquickly.Toovercomethis,considerincreasingseedquantitiesbyupto50percent.•Enhancevegetationestablishmentbydividingthehydromulchoperationintotwophases:1.Phase1-Installallseedandfertilizerwith25-30percentmulchandtackifierontosoilinthefirstlift.2.Phase2-Installtherestofthemulchandtackifieroverthefirstlift.Or,enhancevegetationby:1.Installingthemulch,seed,fertilizer,andtackifierinonelift.2.Spreadorblowstrawoverthetopofthehydromulchatarateof800-1000poundsperacre.3.Holdstrawinplacewithastandardtackifier.Bothoftheseapproacheswillincreasecostmoderatelybutwillgreatlyimproveandenhancevegetativeestablishment.Theincreasedcostmaybeoffsetbythereducedneedfor:•Irrigation.•Reapplicationofmulch.•Repairoffailedslopesurfaces.Thistechniqueworkswithstandardhydromulch(1,500poundsperacreminimum)andBFM/MBFMs(3,000poundsperacreminimum).•Seedmaybeinstalledbyhandif:•Temporaryandcoveredbystraw,mulch,ortopsoil.•Permanentinsmallareas(usuallylessthanIacre)andcoveredwithmulch,topsoil,orerosionblankets.•Theseedmixeslistedinthetablesbelowincluderecommendedmixesforbothtemporaryandpermanentseeding.ohinwCojs/riic/ionStonnwalerPollutionPreentionitus!20121 •Applythesemixes,withtheexceptionofthewetlandmix.atarateof120poundsperacre.Thisratecanbereducedifsoilamendmentsorslow-releasefertilizersareused.•Consultthelocalsuppliersorthelocalconservationdistrictfortheirrecommendationsbecausetheappropriatemixdependsonavarietyoffactors.includinglocation,exposure,soiltype.slope,andexpectedfoottraffic.Alternativeseedmixesapprovedbythelocalauthoritymaybeused.•Othermixesmaybeappropriate,dependingonthesoiltypeandhydrologyofthearea.Table4.1.2liststhestandardmixforareasrequiringatemporaryvegetativecover.Table4.1.2TemporaryErosionControlSeedMixVjPHGrmaionChewingsorannualbluegrass409890es/zetarubraarconnnzilataorFociannaPerennialrye-509890olizen,erauneRedtoporcolonialbentgrass59285rosilsa/baorrostistenzeisWhitedutchclover59890HolwnzleeflY•Table4.1.3listsarecommendedmixforlandscapingseed.Table4.1.3LandscapingSeedMixWIPriGrinnionPerennialryeblend709890oliuiiiL’PL’fl?7L’Chewingsandredfescueblend309890esnecarubraciicommu!a!aorestiecarzthraobtineConstrue/ionStornzwa!erPollutionPieen/ioniius!2012I •Table4.1.4listsaturfseedmixfordrysituationswherethereisnoneedforwatering.Thismixrequiresverylittlemaintenance.Table4.1.4Low-GrowingTurfSeedMixViPriGrinaionDwarftallfescue(severalvarieties)459890estucaaninmaccaat—____ ____ ____ ____ ____ ___Dwarfperennialrye(Barclay)309890olin,;,erenneatbare/aRedfescue209890estucarzthraColonialbentgrass59890roslislefliUS•Table4.1.5listsamixforbioswalesandotherintermittentlywetareas.Table4.1.5BioswaleSeedMix*ViPriGrinsionTallormeadowfescue75-809890extneaaruniizaceaoresfltcac/allotSeaside/Creepingbentgrass10-159285rostisalusirisRedtopbentgrass5-109080rostisathaorrosiLyian/caolierimteen,ncroseeinGuieel/ansSeeohmicCons/rudilonS!or,nii’a!erPolhthonPieenlionuus!2012I •Table4.1.6listsalow-growing,relativelynon-invasiveseedmixappropriateforverywetareasthatarenotregulatedwetlands.Applythismixtureatarateof60poundsperacre.Consult1-lydraulicPermitAuthority(HPA)forseedmixesifapplicable.Table4.1.6WetAreaSeedMix*WiPriCrinnionTallormeadowfescue60-709890cx!ucaan/nmaccaores/ucacia/lopSeaside/Creepinghentgrass10-159885rosilsa/its!risMeadowfoxtail10-159080icocurusratensisAlsikeclover1-69890,ioliumbriinnRedtopbentgrass1-69285rostisa/baolieriarreen,nerosecinGuiec//ansSeci•Table4.1.7listsarecommendedmeadowseedmixforinfrequentlymaintainedareasornon-maintainedareaswherecolonizationbynativeplantsisdesirable.Likelyapplicationsincluderuralroadandutilityright-of-way.SeedingshouldtakeplaceinSeptemberorveryearlyOctoberinordertoobtainadequateestablishmentpriortothewintermonths.Considertheappropriatenessofclover,afairlyinvasivespecies,inthemix.Amendingthesoilcanreducetheneedforclover.Table4.1.7MeadowSeedMixWIPriCrinnionRedtoporOregonbentgrass209285rostisa/baorrostisor e onensi s -____ _ _ ________ _ _ ________ _ _ ________ _ _ ________ _ _ ________ _ _Redfescue709890csfltcariebra-___________-___ __Whitedutchclover109890ri0/li/fl?PCCfl5oheineConstructionS!ornnva/crPo/huio,zPieeli//oiluus!20121 •RonmandRo01iiiTheseedbedshouldbefirmandrough.Roughenallsoilnomatterwhattheslope.Trackwalkslopesbeforeseedingifengineeringpurposesrequirecompaction.Backbladingorsmoothingofslopesgreaterthan4H:lVisnotallowediftheyaretobeseeded.•Restoration-basedlandscapepracticesrequiredeeperincorporationthanthatprovidedbyasimplesingle-passrototillingtreatment.Whereverpractical,initiallyripthesubgradetoimprovelong-termpermeability,infiltration,andwaterinflowqualities.Ataminimum,permanentareasshallusesoilamendmentstoachieveorganicmatterandpermeabilityperformancedefinedinengineeredsoil/landscapesystems.Forsystemsthataredeeperthan8inchescompletetherototillingprocessinmultiplelifts,orpreparetheengineeredsoilsystemperspecificationsandplacetoachievethespecifieddepth.•Friir•Conductingsoilteststodeterminetheexacttypeandquantityoffertilizerisrecommended.Thiswillpreventtheover-applicationoffertilizer.•Organicmatteristhemostappropriateformoffertilizerbecauseitprovidesnutrients(includingnitrogen,phosphorus,andpotassium)intheleastwater-solubleform.•Ingeneral,use10-4-6N-P-K(nitrogen-phosphorus-potassium)fertilizeratarateof90poundsperacre.Alwaysuseslow-releasefertilizersbecausetheyaremoreefficientandhavefewerenvironmentalimpacts.Donotaddfertilizertothehydromulchmachine,oragitate,morethan20minutesbeforeuse.Toomuchagitationdestroystheslow-releasecoating.•Therearenumerousproductsavailablethattaketheplaceofchemicalfertilizers.Theseincludeseveralwithseaweedextractsthatarebeneficialtosoilmicrobesandorganisms.If100percentcottonseedmealisusedasthemulchinhydroseed,chemicalfertilizermaynotbenecessary.Cottonseedmealprovidesagoodsourceoflong-term,slow-release,availablenitrogen.•BonddFirMaiiandManiaBonddFirMari•OnsteepslopesuseBondedFiberMatrix(BFM)orMechanicallyBondedFiberMatrix(MBFM)products.ApplyBFM/MBFMproductsataminimumrateof3,000poundsperacreofmulchwithapproximately10percenttackifier.Achieveaminimumof95pcrcentsoilcovcragcduringapplication.Numerousproductsarcavailablecommercially.Installedproductspermanufacturer’sinstructions.Mostproductsrequire24-36hourstocurebeforerainfallandcannotbeinstalledonwetorsaturatedsoils.ohiineConsfiuctionSlornni’aterPollutionPreentioniius!2012I Generally,productscomein40-50poundbagsandincludeallnecessaryingredientsexceptforseedandfertilizer.•BFMsandMBFMSprovidegoodalternativestoblanketsinmostareasrequiringvegetationestablishment.Advantagesoverblanketsinclude:•BFMandMBFMsdonotrequiresurfacepreparation.•HelicopterscanassistininstallingBFMandMBFMsinremoteareas.•Onslopessteeperthan2.5H:IV.blanketinstallersmayrequireropesandharnessesforsafety.•InstallingBFMandMBFMscansaveatleast$1,000peracrecomparedtoblankets.MaintenanceReseedanyseededareasthatfailtoestablishatleast80percentcoverStandards(100percentcoverforareasthatreceivesheetorconcentratedflows).Ifreseedingisineffective,useanalternatemethodsuchassodding,mulching.ornets/blankets.Ifwinterweatherpreventsadequategrassgrowth,thistimelimitmayberelaxedatthediscretionofthelocalauthoritywhensensitiveareaswouldotherwisebeprotected.Reseedandprotectbymulchanyareasthatexperienceerosionafterachievingadequatecover.Reseedandprotectbymulchanyerodedarea.Supplyseededareaswithadequatemoisture,butdonotwatertotheextentthatitcausesrunoffApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC120.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.LocaljurisdictionsmaychoosenottoacceptthisproductapprovedasequivalenLormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecy.wa.gov/proErams/wg/stornnvater/newtech/eguivalent.htmlBMPC121:MulchingPurposeMulchingsoilsprovidesimmediatetemporaryprotectionfromerosion.Mulchalsoenhancesplantestablishmentbyconservingmoisture,holdingfertilizer,seed,andtopsoilinplace,andmoderatingsoiltemperatures.Thereisanenormousvarietyofmulchesthatcanbeused.Thissectiondiscussesonlythemostcommontypesofmulch.Asatemporan’covermeasure,mulchshouMbeused:condznoizsofUse•Forlessthan30daysondisturbedareasthatrequirecover.•Atalltimesforseededareas,especiallyduringthewetseasonandolunieConstructionStonniva!erPollutionPieeu/ionuus!2012I duringthehotsummermonths.•Duringthewetseasononslopessteeperthan31T:IVwithmorethan10feetofverticalrelief.Mulchmaybeappliedatanytimeoftheyearandmustberefreshedperiodically.•Forseededareasmulchmaybemadeupof100percent:cottonseedmeal;fibersmadeofwood,recycledcellulose,hemp,kenaf;compost;orblendsofthese.Tackifiershallbeplant-based,suchasguaroralphaplantago,orchemical-basedsuchaspolyaciylamideorpolymers.Anymulchortackifierproductusedshallbeinstalledpermanufacturer’sinstructions.Generally,mulchescomein40-50poundbags.Seedandfertilizerareaddedattimeofapplication.DesignandFormulchmaterials,applicationrates,andspecifications,seeTable4.1.8.InstallationAlwaysusea2-inchminimummulchthickness;increasethethicknessSpecjficationsuntilthegroundis95%covered(i.e.notvisibleunderthemulchlayer).Note:Thicknessmaybeincreasedfordisturbedareasinornearsensitiveareasorotherareashighlysusceptibletoerosion.Mulchusedwithintheordinaryhigh-watermarkofsurfacewatersshouldbeselectedtominimizepotentialflotationoforganicmatter.Compostedorganicmaterialshavehigherspecificgravities(densities)thanstraw,wood,orchippedmaterial.ConsultHydraulicPermitAuthority(HPA)formulchmixesifapplicable.Maintenance•Thethicknessofthecovermustbemaintained.Standards•Anyareasthatexperienceerosionshallberemuichedand/orprotectedwithanetorblanket.Iftheerosionproblemisdrainagerelated,thentheproblemshallbefixedandtheerodedarearemulched.olnincCons/rue/jo,,Stonuwa/erPollutionPreen/ionuus!201220 Table4.1.8MulchStandardsandGuidelinesAiaionNIManaQaiSandardRaRanStrawAir-dried;freefrom2”-3”thick;SCost-effectiveprotectionwhenappliedwithadequatethickness.undesirableseedandbalesper1,000Hand-applicationgenerallyrequiresgreaterthicknessthancoarsematerial.sfor2-3tonsperblownstraw.Thethicknessofstrawmaybereducedbyhalfacrewhenusedinconjunctionwithseeding.Inwindyareasstrawmustbeheldinplacebycrimping,usingatackifier,orcoveringwithnetting,blownstrawalwayshastobeheldinplacewithatackiflerasevenlightwindswillblowitaway.Straw,however,hasseveraldeficienciesthatshouldbeconsideredwhenselectingmulchmaterials.Itofienintroducesand/orencouragesthepropagationofweedspeciesandithasnosignificantlongtermbenefits.Itshouldalsonotbeusedwithintheordinaryhigh-waterelevationofsurfacewaters(duetoflotation).HydromulchNogrowthApprox.25-30Shallbeappliedwithhydromulcher.Shallnotbeusedwithoutinhibitingfactors.lbsper1,000sfseedandtackilierunlesstheapplicationrateisatleastdoubled.or1,500-2,000Fiberslongerthanabout¼-Iinchcloghydromulchequipment.lbsperacreFibersshouldbekepttolessthan¼inch.CompostedNovisiblewateror2”thickmm.;MoreeffectivecontrolcanbeobtainedbyincreasingthicknessMulchanddustduringapprox.100tonsto3”.ExcellentmulchforprotectingfinalgradesuntilComposthandling.Mustbeperacre(approx.landscapingbecauseitcanbedirectlyseededortilledintosoilproducedin800lbsperyard)asanamendment.Compostedmulchhasacoarsersizeaccordancewithgradationthancompost.Itismorestableandpracticaltousein173-350,wetareasandduringrainyweatherconditions.DonotuseSolidWastecompostedmulchnearwetlandsornearphosphorousimpairedHandlingStandards,waterbodies.ChippedSiteAveragesizeshall2”thickmm.;Thisisacost-eflectivewaytodisposeofdebrisfromclearingVegetationbeseveralinches.andgrubbing,anditeliminatestheproblemsassociatedwithGradationsfromburning.Generally,itshouldnotbeusedonslopesabovefinesto6inchesinapprox.10%becauseofitstendencytobetransportedbylengthfortexture,runoff.Itisnotrecommendedwithin200feetofsurfacewaters.variation,andIfseedingisexpectedshortlyaftermulch,thedecompositionofinterlockingthechippedvegetationmaytieupnutrientsimportanttograssproperties.establishment.Wood-basedNovisiblewateror2”thickmm.;Thismaterialisoftencalled“hogorhoggedfuel.”TheuseofMulchorWooddustduringapprox.100tonsmulchultimatelyimprovestheorganicmatterinthesoil.Strawhandling.Mustbeperacre(approx.Specialcautionisadvisedregardingthesourceandcompositionpurchasedfroma800lbs.perolwood-basedmulches.ItspreparationtypicallydoesnotsupplierwithaSolidcubicyard)provideanyweedseedcontrol,soevidenceofresidualWasteHandlingvegetationinitscompositionorknowninclusionofweedplantsPermitoroneorseedsshouldbemonitoredandprevented(orminimized).exemptfromsolidwasteregulations.VoodStrandAblendofloose,2”thickmm.Cost-effectiveprotectionwhenappliedwithadequatethickness.Mulchlong.thinwoodAminimumof95-percentofthewoodstrandshallhavelengthspiecesderivedfrombetween2and10-inches,withawidthandthicknessbetweennativeconiferor1/16atid¼-inches.Themulchshallnotcontainresin,tannin,ordeciduoustreeswithothercompoundsinquantitiesthatwouldbedetrimentaltoplanthighlength-to-widthlife.Sawdustorwoodshavingsshallnotbeusedasmulch.ratio.(WSDOTspecification(9-14.4(4))ohimeCotis!ruc/ionS/ornnt’aterPollutionPreen/ionitus!201221 BMPC122:NetsandBlanketsPurposeErosioncontrolnetsandblanketsareintendedtopreventerosionandholdseedandmulchinplaceonsteepslopesandinchannelssothatvegetationcanbecomewellestablished.Inaddition,somenetsandblanketscanbeusedtopermanentlyreinforceturftoprotectdrainagewaysduringhighflows.Nets(commonlycalledmatting)arestrandsofmaterialwovenintoanopen,buthigh-tensilestrengthnet(forexample.coconutfibermatting).Blanketsarestrandsofmaterialthatarenottightlywoven,butinsteadformalayerofinterlockingfibers.typicallyheldtogetherbyabiodegradableorphotodegradablenetting(forexample,excelsiororstrawblankets).Theygenerallyhavelowertensilestrengththannets,butcoverthegroundmorecompletely.Coir(coconutfiber)fabriccomesasbothnetsandblankets.(‘ondiliousofUseErosioncontrolnetsandblanketsshouldbeused:•Toaidpermanentvegetatedstabilizationofslopes21-I:IVorgreaterandwithmorethan10feetofverticalrelief.•Fordrainageditchesandswales(highlyrecommended).Theapplicationofappropriatenettingorblankettodrainageditchesandswalescanprotectbaresoilfromchannelizedrunoffwhilevegetationisestablished.Netsandblanketsalsocancaptureagreatdealofsedimentduetotheiropen,porousstructure.Netsandblanketscanbeusedtopermanentlystabilizechannelsandmayprovideacost-effective,environmentallypreferablealternativetoriprap.100percentsyntheticblanketsmanufacturedforuseinditchesmaybeeasilyreusedastemporaryditchliners.Disadvantagesofblanketsinclude:•Surfacepreparationrequired.•Onslopessteeperthan2.5H:IV,blanketinstallersmayneedtoberopedandharnessedforsafety.•Theycostatleast$4,000-6,000peracreinstalled.Advantagesofblanketsinclude:•Installationwithoutmobilizingspecialequipment.•Installationbyanyonewithminimaltraining•Installationinstagesorphasesastheprojectprogresses.•Installerscanhandplaceseedandfertilizerastheyprogressdowntheslope.•Installationinanyweather.•Therearenumeroustypesofblanketsthatcanbedesignedwithvariousparametersinmind.Thoseparametersinclude:fiberblend,meshstrength,longevity,biodegradability,cost,andavailability.ohnneConstructionStornnt’a!crPollutionPieen/ionuus!2012‘2 Designand•SeeFiure4.1.3andFiQure4.1.4fortypicalorientationandInstallationinstallationofblanketsusedinchannelsandasslopeprotection.Note:Specjflcutionsthesearetypicalonly;allblanketsmustbeinstalledpermanufacturer’sinstallationinstructions.Installationiscriticaltotheeffectivenessoftheseproducts.Ifgoodgroundcontactisnotachieved.runoffcanconcentrateundertheproduct,resultinginsignificanterosion.InstallationofBlanketsonSlopes:I.Completefinalgradeandtrackwalkupanddowntheslope.2.Installhydromulehwithseedandfertilizer.3.Digasmalltrench,approximately12incheswideby6inchesdeepalongthetopoftheslope.4.Installtheleadingedgeoftheblanketintothesmalltrenchandstapleapproximatelyevery18inches.NOTE:Staplesaremetal,“U”-shaped,andaminimumof6incheslong.Longerstaplesareusedinsandysoils.Biodegradablestakesarealsoavailable.5.Rolltheblanketslowlydowntheslopeasinstallerwalksbackwards.NOTE:Theblanketrestsagainsttheinstaller’slegs.Staplesareinstalledastheblanketisunrolled.Itiscriticalthattheproperstaplepatternisusedfortheblanketbeinginstalled.Theblanketisnottobeallowedtorolldowntheslopeonitsownasthisstretchestheblanketmakingitimpossibletomaintainsoilcontact.Inaddition,nooneisallowedtowalkontheblanketafteritisinplace.6.Iftheblanketisnotlongenoughtocovertheentireslopelength,thetrailingedgeoftheupperblanketshouldoverlaptheleadingedgeofthelowerblanketandbestapled.Onsteeperslopes,thisoverlapshouldbeinstalledinasmalltrench,stapled,andcoveredwithsoil.Withthevarietyofproductsavailable,itisimpossibletocoverallthedetailsofappropriateuseandinstallation.Therefore,itiscriticalthatthedesignengineerconsultthemanufacturersinformationandthatasitevisittakesplaceinordertoensurethattheproductspecifiedisappropriate.Informationisalsoavailableatthefollowingwebsites:1.WSDOT(Section3.2.4):http://www.wsdot.wa.gov/NR!rdonlyres/3B4IE087-FA86-4717-932D-D7A8556CCD57/O/ErosionTraininaManual.pdf2.TexasTransportationInstitute:http://www.txdot.govfbusiness/doingbusiness/productevaluation!erosioncontrol.htmoIzll;?c’ConstruclionS/or,nii’c,/erPollutionPieen/ioniius!20122 •Usejutemattinginconjunctionwithmulch(BMPC121).Excelsior,wovenstrawblanketsandcoir(coconutfiber)blanketsmaybeinstalledwithoutmulch.Therearemanyothertypesoferosioncontrolnetsandblanketsonthemarketthatmaybeappropriateincertaincircumstances.•Ingeneral,mostnets(e.g.,jutematting)requiremulchinordertopreventerosionbecausetheyhaveafairlyopenstructure.Blanketstypicallydonotrequiremulchbecausetheyusuallyprovidecompleteprotectionofthesurface.•Extremelysteep,unstable,‘vet,orrockyslopesareoftenappropriatecandidatesforuseofsyntheticblankets,asareriverbanks,beachesandotherhigh-energyenvironments.Ifsyntheticblanketsareused,thesoilshouldbehvdromulchedfirst.•100-percentbiodegradableblanketsareavailableforuseinsensitiveareas.Theseorganicblanketsareusuallyheldtogetherwithapaperorfibermeshandstitchingwhichmaylastuptoayear.•Mostnettingusedwithblanketsisphotodegradable.meaningtheybreakdownundersunlight(notUVstabilized).However,thisprocesscantakemonthsoryearsevenunderbrightsun.Oncevegetationisestablished,sunlightdoesnotreachthemesh.Itisnotuncommontofindnon-degradednettingstillinplaceseveralyearsafterinstallation.Thiscanbeaproblemifmaintenancerequirestheuseofmowersorditchcleaningequipment.Tnaddition,birdsandsmallanimalscanbecometrappedinthenetting.Maintenance•Maintaingoodcontactwiththeground.ErosionmustnotoccurStandardsbeneaththenetorblanket.•Repairandstapleanyareasofthenetorblanketthataredamagedornotinclosecontactwiththeground.•Fixandprotecterodedareasiferosionoccursdue10poorlycontrolleddrainage.olwncConstructionStornni’aterPollutionPit’eu/ioniius!20)22 InitIalChannelAnchorTrenchNOTES:1.Checkplot,lobeeoo,wactedpermanufacorm.peciflcationL2.Stakingorstaplinglayoutpetmanufnrn.pcdliadou’.Figure4.1.3—ChannelInstallationFigure4.1.4—SlopeInstallationohmwConstructionStornnt’atc’rPollutionPieen/ionuus!2012LorçlkTh&ArtlorTrorchTerminalSlopeandChannelAnchorTrenchO4?IntermittentCheckSlotSlopesurfaceshallbesmoothbeforeplacementforpropersoilcontact.Staplingpatternaspermanufacturer’srecommendatic-ns.Mm.2OverlapIfthereisabermatthetopofslope,anchorupslopeoftheberm.Anchorhi&x6’mhi.Trenchandstapleat12”intervals.Mm.6’overlap.Stapleoverlapsmax.5”spacing.Bringmaterialdowntoalevelarea,turnDonotstretchblanketsimattingstight-theendunder4”andstapleat12’intervals.allowtherollstomoldtoanyirregularities.Forslopeslessthan3H1V,rollsmaybeplacedinhorizontalstrips,Lime,ferlilize,andseedbeforeinstallation.Plantingofshrubs,trees,etc.Shouldoccurafterinstallation.2 BMPC123:PlasticCoveringPurposePlasticcoveringprovidesimmediate,short-termerosionprotectiontoslopesanddisturbedareas.ConditionsofPlasticcoveringmaybeusedondisturbedareasthatrequirecoverUsemeasuresforlessthan30days,exceptasstatedbelow.•Plasticisparticularlyusefulforprotectingcutandfillslopesandstockpiles.Note:Therelativelyrapidbreakdownofmostpolyethylenesheetingmakesitunsuitableforlong-term(greaterthansixmonths)applications.•Duetorapidrunoffcausedbyplasticcovering,donotusethismethodupsiopeofareasthatmightbeadverselyimpactedbyconcentratedrunoff.Suchareasincludesteepand/orunstableslopes.•Plasticsheetingmayresultinincreasedrunoffvolumesandvelocities,requiringadditionalon-sitemeasurestocounteracttheincreases.Creatingatroughwithwattlesorothermaterialcanconveycleanwaterawayfromtheseareas.•Topreventundercutting,trenchandbackfillrolledplasticcoveringproducts.•Whileplasticisinexpensivetopurchase,theaddedcostofinstallation,maintenance,removal,anddisposalmakethisanexpensivematerial,upto$1.50-2.00persquareyard.•Wheneverplasticisusedtoprotectslopesinstallwatercollectionmeasuresatthebaseoftheslope.Thesemeasuresincludeplastic-coveredberms.channels,andpipesusedtocoveycleanrainwaterawayfrombaresoilanddisturbedareas.Donotmixcleanrunofffromaplasticcoveredslopewithdirtyrunofffromaproject.•Otherusesforplasticinclude:1.Temporaryditchliner.2.Pondlinerintemporarysedimentpond.3.Lincrforbcrmcdtcmporaiyfuelstoragearcaifplasticisnotreactivetothetypeoffuelbeingstored.4.Emergencyslopeprotectionduringheavyrains.5.Temporarydrainpipe(“elephanttrunk”)usedtodirectwater.Designand•Plasticslopecovermustbeinstalledasfollows:InstallationI.Runplasticupanddownslopc,notacrossslope.Specifications2.Plasticmaybeinstalledperpendiculartoaslopeiftheslopelengthislessthan10feet.3.Minimumof8-inchoverlapatseams.ohiineCons!uzictio,zStonmi’aterPollutionPieen/iouiius!2012 4.Onlongorwideslopes,orslopessubjecttowind,tapeallseams.5.Placeplasticintoasmall(12-inchwideby6-inchdeep)slottrenchatthetopoftheslopeandbackfillwithsoiltokeepwaterfromflowingunderneath.6.Placesandfilledburlaporgeotextilebagsevery3to6feetalongseamsandtiethemtogetherwithtwinetoholdtheminplace.7.Inspectplasticforrips,tears,andopenseamsregularlyandrepairimmediately.Thispreventshighvelocityrunofffromcontactingbaresoilwhichcausesextremeerosion.8.Sandbagsmaybeloweredintoplacetiedtoropes.However,allsandbagsmustbestakedinplace.•Plasticsheetingshallhaveaminimumthicknessof0.06millimeters.•Tferosionatthetoeofaslopeislikely,agravelberm,riprap,orothersuitableprotectionshallbeinstalledatthetoeoftheslopeinordertoreducethevelocityofrunoff.Maintenance•Tornsheetsmustbereplacedandopenseamsrepaired.Standards•Completelyremoveandreplacetheplasticifitbeginstodeteriorateduetoultravioletradiation.•Completelyremoveplasticwhennolongerneeded.•Disposeofoldtiresusedtoweightdownplasticsheetingappropriately.ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC123.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionalEestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://wwxv.ecy.wa.ov/proarams/wg/stormwater/newtech/eguivalent.htmlBMPC124:SoddingPurposeThepurposeofsoddingistocstablishpermanentturfforimmediateerosionprotectionandtostabilizedrainagewayswhereconcentratedoverlandflowwilloccur.C’onditionsofUseSoddingmaybeusedinthefollowingareas:•Disturbedareasthatrequireshort—termorlong-termcover.•Disturbedareasthatrequireimmcdiatcvegetativecover.•Allwaterwaysthatrequirevegetativelining.Watenvaysmayalsobeseededratherthansodded,andprotectedwithanetorblanket.olunwConsflue/ionS/ornnraterPollutionPieeu/b,,iijust20127 DesignandSodshallbefreeofweeds.ofuniformthickness(approximately1-inchInstallationthick).andshallhaveadenserootmatformechanicalstrength.SpecjficutionsThefollowingstepsarerecommendedforsodinstallation:Shapeandsmooththesurfacetofinalgradeinaccordancewiththeapprovedgradingplan.Theswaleneedstobeoverexcavated4to6inchesbelowdesignelevationtoallowroomforplacingsoilamendmentandsod.•Amend4inches(minimum)ofcompostintothetop8inchesofthesoiliftheorganiccontentofthesoilislessthantenpercentorthepermeabilityislessthan0.6inchesperhour.Seehttp://www.ecv.va.2ov/prourams/swfaioruanics/soil.hunlforfurtherinformation.•Fertilizeaccordingtothesuppliersrecommendations.•WorklimeandfertilizerIto2inchesintothesoil,andsmooththesurface.•Laystripsofsodbeginningatthelowestareatobesoddedandperpendiculartothedirectionofwaterflow.Wedgestripssecurelyintoplace.Squaretheendsofeachstriptoprovideforaclose,tightfit.Staggerjointsatleast12inches.Stapleonslopessteeperthan3H:JV.Stapletheupstreamedgeofeachsodstrip.•Rollthesoddedareaandirrigate.•Whensoddingiscarriedoutinalternatingstripsorotherpatterns,seedtheareasbetweenthesodimmediatelyaftersodding.MaintenanceIfthegrassisunhealthy,thecauseshallbedeterminedandappropriateStandardsactiontakentoreestablishahealthygroundcover.Ifitisimpossibletoestablishahealthygroundcoverduetofrequentsaturation,instability,orsomeothercause,thesodshallberemoved,theareaseededwithanappropriatemix,andprotectedwithanetorblanket.BMPC125:TopsoilingICompostingPurposeTopsoilingandcompostingprovidcasuitablegrowthmediumforfinalsitestabilizationwithvegetation.Whilenotapermanentcoverpracticeinitself,topsoilingandcompostingareanintegralcomponentofprovidingpermanentcoverinthoseareaswherethereisanunsuitablesoilsurfaceforplantgrowth.UsethisBMPinconjunctionwithotherBMPssuchasseeding,mulching,orsodding.Nativesoilsanddisturbedsoilsthathavebeenorganicallyamendednotonlyretainmuchmorestoimwater,buttheyalsoserveaseffectivebiofiltersforurbanpollutantsand,bysupportingmorevigorousplantgrowth,reducethewater,fertilizerandpesticidesneededtosupportohmicConstructionStonnwaterPollutionPieeniloniinsf20127 installedlandscapes.Topsoildoesnotincludeanysubsoilsbutonlythematerialfromthetopseveralinchesincludingorganicdebris.Conditionsof.PermanentlandscapedareasshallcontainhealthytopsoilthatreducesUsetheneedforfertilizers,improvesoveralltopsoilquality,providesforbettervegetalhealthandvitality,improveshydrologiccharacteristics,andreducestheneedforirrigation.Leavenativesoilsandthedufflayerundisturbedtothemaximumextentpracticable.Strippingofexisting,properlyffinctioningsoilsystemandvegetationforthepurposeoftopsoilingduringconstructionisnotacceptable.Preserveexistingsoilsystemsinundisturbedanduncompactedconditionsifflrnctioningproperly.•Areasthatalreadyhavegoodtopsoil,suchasundisturbedareas,donotrequiresoilamendments.•Restore,tothemaximumextentpractical,nativesoilsdisturbedduringclearingandgradingtoaconditionequaltoorbetterthantheoriginalsitecondition’smoisture-holdingcapacity.Useon-sitenativetopsoil,incorporateamendmentsintoon-sitesoil,orimportblendedtopsoiltomeetthisrequirement.•Topsoilingisarequiredprocedurewhenestablishingvegetationonshallowsoils,andsoilsofcriticallylowp1-i(highacid)levels.•Bewareofwherethetopsoilcomesfrom,andwhatvegetationwasonsitebeforedisturbance,invasiveplantseedsmaybeincludedandcouldcauseproblemsforestablishingnativeplants,landscapedareas,orgrasses.•TopsoilfromthesitewiHcontainmycorrhizalbacteriathatarenecessaryforhealthyrootgrowthandnutrienttransfer.Thesenativemycorrhizaareacclimatedtothesiteandwillprovideoptimumconditionsforestablishinggrasses.Usecommerciallyavailablemycorrhizaproductswhenusingoff-sitetopsoil.DesignandMeetthefollowingrequirementsforareasrequiringdisruptionandInstallationtopsoiling:Specffications•Maximizethedepthofthetopsoilwhereverpossibletoprovidethemaximumpossibleinfiltrationcapacityandbeneficialgrowthmedium.Topsoilshallhave:Aminimumdepthof8-inches.Scarifysubsoilsbelowthetopsoillayeratleast4-incheswithsomeincorporationoftheuppermaterialtoavoidstratifiedlayers,wherefeasible.Rippingorrestructuringthesubgrademayalsoprovideadditionalbenefitsregardingtheoverallinfiltrationandintcrflowdynamicsofthcsoilsystem.ohiiiit’Co,zs/muc/jo,,S!ornnt’a/e,PoihilionPieen/ioniius!20122 •Aminimumorganiccontentof10%dry’weight.and5%organicmattercontentinturfareas.Incorporateorganicamendmentstoaminimum8-inchdepthexceptwheretreerootsorothernaturalfeatureslimitthedepthofincorporation.•ApHbetween6.0and8.0ormatchingthepHoftheundisturbedsoil.•Ifblendedtopsoilisimported,thenfinesshouldbelimitedto25percentpassingthrougha200sieve.AccomplishtherequiredorganiccontentandpETbyeitherreturningnativetopsoiltothesiteand/orincorporatingorganicamendments.•Tomeettheorganiccontentusecompostthatmeetsthedefinitionof”compostedmaterials”in\VAC173-350-220.Thiscodeisavailableonlineat:http://apps.len.wa.ov/WAC/default.aspx?cite=173-350-220.Thecompostmustalsohaveanorganicmattercontentof35%to65%,andacarbontonitrogenratiobelow25H:IV.Thecarbontonitrogenratiomaybeashighas35H:IVforplantingscomposedentirelyofplantsnativetothePugetSoundLowlandsregion.•Fortillsoilsuseamixtureofapproximatelytwopartssoiltoonepartcompost.Thisequatesto4inchesofcompostmixedtoadepthof12inchesintiltsoils.Increasingtheconcentrationofcompostbeyondthislevelcanhavenegativeeffectsonvegetalhealth,whiledecreasingtheconcentrationscanreducethebenefitsofamendedsoils.•Gravelorcobbleoutwashsoils,mayrequiredifferentapproaches.Organicsandfineseasilymigratethroughtheloosestructureofthesesoils.Therefore,theimportationofatleast6inchesofqualitytopsoil,underlainbysometypeoffilterfabrictopreventthemigrationoffines,maybemoreappropriateforthesesoils.•Thefinalcompositionandconstructionofthesoilsystemwillresultinanaturalselectionorfavoringofcertainplantspeciesovertime.Forexample,incorporationoftopsoilmayfavorgrasses,whilelayeringwithmildlyacidic,high-carbonamendmentsmayfavormorewoodyvegctation.•Allowsufficienttimeinschedulingfortopsoilspreadingpriortoseeding,sodding,orplanting.•Takecarewhenapplyingtopsoiltosubsoilswithcontrastingtextures.Sandytopsoiloverclayeysubsoilisaparticularlypoorcombination,aswatercreepsalongthcjunctionbetweenthesoillayersandcausesthetopsoiltoslough.Iftopsoilandsubsoilarenotproperlybonded,waterwillnotinfiltratethesoilprofileevenlyanditwillbedifficulttoolunwCons/nicIlo;,&onnil’a!erPollutlo,,Preen!ioniius!2012U establishvegetation.Thebestmethodtopreventalackofbondingistoactuallyworkthetopsoilintothelayerbelowforadepthofatleast6inches.Fieldexplorationofthesheshallbemadetodetermineifthereissurfacesoilofsufficientquantityandqualitytojustifystripping.Topsoilshallbefriableandloamy(loam,sandyloam,siltloam,sandyclayloam,andclayloam).Avoidareasofnaturalgroundwaterrecharge.•Strippingshallbeconfinedtotheimmediateconstructionarea.A4-inchto6-inchstrippingdepthiscommon,butdepthmayvarydependingontheparticularsoil.Allsurfacerunoffcontrolstructuresshallbeinplacepriortostripping.•Donotplacetopsoilwhileinafrozenormuddycondition,whenthesubgradeisexcessivelywet,orwhenconditionsexistthatmayotherwisebedetrimentaltopropergradingorproposedsoddingorseeding.•Inanyareasrequiringgradingremoveandstockpilethedufflayerandtopsoilonsiteinadesignated,controlledarea,notadjacenttopublicresourcesandcriticalareas.Stockpiledtopsoilistobereappliedtootherportionsofthesitewherefeasible.•Locatethetopsoilstockpilesothatitmeetsspecificationsanddoesnotinterferewithworkonthesite.ftmaybepossibletolocatemorethanonepileinproximitytoareaswheretopsoilwillbeused.Stockpilingoftopsoilshalloccurinthefollowingmanner:•Sideslopesofthestockpileshallnotexceed2H:JV.•BetweenOctober1andApril30:•Aninterceptordikewithgraveloutletandsiltfenceshallsurroundalltopsoil.•Within2dayscompleteerosioncontrolseeding,orcoveringstockpileswithclearplastic,orothermulchingmaterials.•BetweenMayIandSeptember30:•Aninterceptordikewithgraveloutletandsiltfenceshallsurroundalltopsoilifthestockpilewillremaininplaceforalongerperiodoftimethanactiveconstructiongrading.•Within7dayscomplctccrosioncontrolsccding,orcoveringstockpileswithclearplastic,orothermulchingmaterials.Whennativetopsoilistobestockpiledandreusedthefollowingshouldapplytoensurethatthencorrhizalbacterial,earthworms,andotherbeneficialorganismswillnotbedestroyed:I.Re-installtopsoilwithin4to6weeks.oluineConstructionStornni’aterPollutionPieentioniius!2012I •2.Donotallowthesaturationoftopsoilwithwater.3.Donotuseplasticcovering.Maintenaitce.Inspectstockpilesregularly,especiallyafterlargestormevents.StandardsStabilizeanyareasthathaveeroded.•Establishsoilqualityanddepthtowardtheendofconstructionandonceestablished,protectfromcompaction.suchasfromlargemachineryuse,andfromerosion.•Plantandmulchsoilafterinstallation.•Leaveplantdebrisoritsequivalentonthesoilsurfacetoreplenishorganicmatter.•Reduceandadjust,wherepossible,theuseofirrigation,fertilizers,herbicidesandpesticides,ratherthancontinuingtoimplementformerlyestablishedpractices.BMPC126:Polyacrylamide(PAM)forSoilErosionProtectionPurposePolyacrylamide(PAM)isusedonconstructionsitestopreventsoilerosion.ApplyingPAMtobaresoilinadvanceofaraineventsignificantlyreduceserosionandcontrolssedimentintwoways.First,PAMincreasesthesoil’savailableporevolume,thusincreasinginfiltrationthroughflocculationandreducingthequantityofstormwaterrunoff.Second,itincreasesflocculationofsuspendedparticlesandaidsintheirdeposition,thusreducingstomwvaterrunoffturbidityandimprovingwaterquality.ConditionsofUsePAMshallnotbedirectlyappliedtowaterorallowedtoenterawaterbody.Inareasthatdraintoasedimentpond,PAMcanbeappliedtobaresoilunderthefollowingconditions:•Duringroughgradingoperations.•InStagingareas.•Balancedcutandfillearthwork.•Haulroadspriortoplaccmcntofcrushedrocksurfacing.•Compactedsoilroadbase.•Stockpiles.•Afterfinalgradeandbeforepavingorfinalseedingandplanting.•Pitsites.ohuneConstructionStonnwaterPollutionPieentionitus!2012 •Siteshavingawintershutdown.Inthecaseofwintershutdown,orwheresoilwillremainunworkedforseveralmonths.PAMshouldbeusedtogetherwithmulch.PAMmaybeappliedwithwaterindissolvedform.ThepreferredDesignand.applicationmethodisthedissolvedform.InstallationSpecjficationsPAMistobeappliedatamaximumrateof2/3poundPAMper1,000gallonswater(80mg/L)perIacreofbaresoil.Table4.1.9canbeusedtodeterminethePAMandwaterapplicationrateforadisturbedsoilarea.HigherconcentrationsofPAMdonoprovideanyadditionaleffectiveness.Table4.1.9PAMandWaterApplicationRatesDirdAra(a)PAM(1War(al0.500.33500I.000.66I,0001.50I.001,5002.001.322,0002.50I.652,5003.002.003,0003.502.333,5004.002.654,0004.503.004,5005.003.335.000ThePreferredMethod:•Pre-measuretheareawherePAMistobeappliedandcalculatetheamountofproductandwaternecessarytoprovidecoverageatthespecifiedapplicationrate(2/3poundPAM/I000gallons/acre).•PAMhasinfinitesolubilityinwater,butdissolvesveryslowly.Dissolvepre-measureddrygranularPAMwithaknownquantityofcleanwaterinabucketseveralhoursorovernight.MechanicalmixingwillhelpdissolvethePAM.AlwaysaddPAMtowater-notwatertoPAM.•Pre—fillthewatertruckabout1/8fillwithwater.Thewaterdoesnothavetobepotable,butitmusthaverelativelylowturbidity—intherangeof20NTUorless.•AddPAM/Watermixturetothetruck•Completelyfillthewatertrucktospecifiedvolume.•SprayPAM/Watermixtureontodrysoiluntilthesoilsurfaceisuniformlyandcompletelywetted.AmAlternateMethod:ohilneConstructionS/onnwa/crPollutionPvc’cm/ioniius!2012 PAMmayalsobeappliedasapowderattherateof5lbs.peracre.Thismustbeappliedonadaythatisdry’.Forareaslessthan5-10acres,ahand-held“organgrinder”fertilizerspreadersettothesmallestsettingwillwork.Tractor-mountedspreaderswillworkforlargerareas.ThefollowingshallbeusedforapplicationofpowderedPAM:•PoweredPAMshallbeusedinconjunctionwithotherBMPsandnotinplaceofotherBMPs.•DonotusePAMonaslopethatflowsdirectlyintoastreamorwetland.ThestormwaterrunoffshallpassthroughasedimentcontrolBMPpriortodischargingtosurfacewaters.•DonotaddPAMtowaterdischargingfromsite.•Whenthetotaldrainageareaisgreaterthanorequalto5acres,PAMtreatedareasshalldraintoasedimentpond.•Areaslessthan5acresshalldraintosedimentcontrolBMPs,suchasaminimumof3checkdamsperacre.Thetotalnumberofcheckdamsusedshallbemaximizedtoachievethegreatestamountofsettlementofsedimentpriortodischargingfromthesite.Eachcheckdamshallbespacedevenlyinthedrainagechannelthroughwhichstormwaterflowsaredischargedoff-site.•Onallsites,theuseofsiltfenceshallbemaximizedtolimitthedischargesofsedimentfromthesite.•Allareasnotbeingactivelyworkedshallbecoveredandprotectedfromrainfall.PAMshallnotbetheonlycoverBMPused.•PAMcanbeappliedtowetsoil,butdrysoilispreferredduetolesssedimentloss.•PAMwillworkwhenappliedtosaturatedsoilbutisnotaseffectiveasapplicationstodryordampsoil.•KeepthegranularPAMsupplyoutofthesun.GranularPAMlosesitseffectivenessinthreemonthsafterexposuretosunlightandair.•Properapplicationandre-applicationplansarcnecessarytoensuretotaleffectivenessofPAMusage.•PAM.combinedwithwater,isyen’slipperyandcanbeasafetyhazard.CaremustbetakentopreventspillsofPAMpowderontopavedsurfaces.DuringanapplicationofPAM,preventover-sprayfromreachingpavementaspavementwillbecomeslippery.IfPAMpowdergetsonskinorclothing,wipeitoffwitharoughtowelratherthanwashingwithwater-thisonlymakescleanupmessierandtakelonger.•SomePAMsaremoretoxicandcarcinogenicthanothers.OnlythemostenvironmentallysafePAMproductsshouldbeused.ohiiiieConstructionStornurcuerPollutionfireeu/ionuus!2012 ThespecificPAMcopolymerformulationmustbeanionic.CaioniPAManodinanaiaionaofnonaa1oIIroOnlythehighestdrinkingwatergradePAM,certifiedforcompliancewithANSI/NSFStandard60fordrinkingwatertreatment.vilIbeusedforsoilapplications.RecentmediaattentionandhighinterestinPAMhasresultedinsomeentrepreneurialexploitationoftheterm“polynwr“AllPAMarepolymers,butnotallpolymersarePAM,andnotallPAMproductscomplywithANSI/NSFStandard60.PAMuseshallbereviewedandapprovedbythelocalpermittingauthority.PAMdesignatedfortheseusesshouldbe“watersoluble”or“linearor“non-crosslinked”.Cross-linkedorwaterabsorbentPAM,polymerizedinhighlyacidic(p1-1<2)conditions,areusedtomaintainsoilmoisturecontent.ThePAManionicchargedensitymayvaryfrom2-30percent;avalueof18percentistypical.StudiesconductedbytheUnitedStatesDepartmentofAgriculture(USDA)/ARSdemonstratedthatsoilstabilizationwasoptimizedbyusingveryhighmolecularweight(12-15mg/mole),highlyanionic(>20%hydrolysis)PAM.•PAMtackifiersareavailableandbeingusedinplaceofguarandalphaplantago.Typically,PAMtackifiersshouldbeusedatarateofnomorethan0.5-1lb.per1000gallonsofwaterinahydromulehmachine.Sometackifierproductinstructionssaytouseatarateof3—5lbs.peracre,whichcanbetoomuch.Inaddition,pumpproblemscanoccurathigherratesduetoincreasedviscosity.Mai,,tenjuice•PAMmaybereappliedonactivelyworkedareasaftera48-hourStandardsperiod.•ReapplicationisnotrequiredunlessPAMtreatedsoilisdisturbedorunlessturbiditylevelsshowtheneedforanadditionalapplication.IfPAMtreatedsoilisleftundisturbedareapplicationmaybenecessaryaftertwomonths.MorePAMapplicationsmayberequiredforsteepslopes,siltyandclayeysoils(USDAClassificationType“C’and“D”soils).longgrades,andhighprecipitationareas.WhenPAMisappliedfirsttobaresoilandthencoveredwithstraw,areapplicationmaynotbenecessaryforseveralmonths.•LossofsedimentandPAMmaybeabasisforpenaltiesperRCW90.48.080.BMPC130:SurfaceRougheningPurposeSurfacerougheningaidsintheestablishmentofvegetativecover,reducesrunoffvelocity,increasesinfiltration,andprovidesforsedimenttrappingthroughtheprovisionofaroughsoilsurface.HorizontaldepressionsareohuncCons!rue/ionS/ornn’a/erPollutionPrecut/oniius!2012 createdbyoperatingatillerorothersuitableequipmentonthecontourorbyleavingslopesinaroughenedconditionbynotfinegradingthem.UsethisBMPinconjunctionwithotherBMPssuchasseeding.mulching,orsodding.Corn!itionsfor.Allslopessteeperthan3H:IVandgreaterthan5verticalfeetUserequiresurfacerougheningtoadepthof2to4inchespriortoseeding..•Areasthatwillnotbestabilizedimmediatelymayberoughenedtoreducerunoffvelocityuntilseedingtakesplace.•Slopeswithastablerockfacedonotrequireroughening.•Slopeswheremowingisplannedshouldnotbeexcessivelyroughened.DesignandTherearedifferentmethodsforachievingaroughenedsoilsurfaceonaInsta!!ationslope,andtheselectionofanappropriatemethoddependsuponihetypeofSpecjflcationsslope.Rougheningmethodsincludestair-stepgrading,grooving,contourffirrows,andtracking.SeeFiuure4.1.5fortrackingandcontourfurrows.Factorstobeconsideredinchoosingamethodareslopesteepness,mowingrequirements,andwhethertheslopeisformedbycuttingorfilling.•Disturbedareasthatwillnotrequiremowingmaybestair-stepgraded,grooved,orleftroughafterfilling.•Stair-stepgradingisparticularlyappropriateinsoilscontaininglargeamountsofsoftrock.Each“step’catchesmaterialthatsloughsfromabove,andprovidesalevelsitewherevegetationcanbecomeestablished.Stairsshouldbewideenoughtoworkwithstandardearthmovingequipment.Stairstepsmustbeoncontourorgullieswillformontheslope.•Areasthatwillbemowed(theseareasshouldhaveslopeslesssteepthan3H:IV)mayhavesmallfurrowsleftbydisking,harrowing,raking,orseed-plantingmachineryoperatedonthecontour.•Gradedareaswithslopessteeperthan3H:IVbutlessthan2H:IVshouldberoughenedbeforeseeding.Thiscanbeaccomplishedinavarietyofways.including‘trackwalking,’ordrivingacrawlertractorupanddowntheslope,leavingapatternofcleatimprintsparalleltoslopecontours.•TrackingisdonebyoperatingequipmentupanddowntheslopetoIcavehorizontaldepressionsinthesoil.Maintenance•AreasthataregradedinthismannershouldbeseededasquicklyasStandardspossible.•Regularinspectionsshouldbemadeofthearea.Ifrillsappear,theyshouldbere-gradedandre-seededimmediately.ohinwConstructionStorunraterPollutionPreentionitust2012 Trackingaa_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-aaaaaaaaaaaaaaa_aaaaaaaaContourFurrowsTRACKING’withmachineryupanddowntheslopeprovidesgroovesthatwillcatchseed,raInfallandreducerunoff.50’(150mm)Madmum1GroovesWillCatchSeed,Fertilizer,Mulch,RainfallandDecreaseRunoff.Figure4.1.5—SurfaceRougheningbyTrackingandContourFurrowsolinneConstrue/to,,S!onnii’a!erPollutionPit’en/iouiius!2012 BMPC131:GradientTerracesPurposeGradientterracesreduceerosiondamagebyinterceptingsurfacerunoffandconductingittoastableoutletatanon-erosivevelocity.C’o,,ditionsofUse•Gradientterracesnormallyarelimitedtodenudedlandhavingawatererosionproblem.Theyshouldnotbeconstructedondeepsandsoronsoilsthataretoostony,steep,orshallowtopermitpracticalandeconomicalinstallationandmaintenance.Gradientterracesmaybeusedonlywheresuitableoutletsareorwillbemadeavailable.SeeFigure4.1.6forgradientterraces.Designand•ThemaximumverticalspacingofgradientterracesshouldbeInstallationdeterminedbythefollowingmethod:Specj/lcationsVI(O.8)s+yWhere:VI=verticalintervalinfeets=landriseper100feet,expressedinfeety=asoilandcovervariablewithvaluesfrom1.0to4.0Valuesof”y”areinfluencedbysoilerodibilityandcoverpractices.Thelowervaluesareapplicabletoerosivesoilswherelittletonoresidueisleftonthesurface.Thehighervalueisapplicableonlytoerosion-resistantsoilswherealargeamountofresidue(1¼tonsofstraw/acreequivalent)isonthesurface.•Theminimumconstructedcross-sectionshouldmeetthedesigndimensions.•Thetopoftheconstructedridgeshouldnotbeloweratanypointthanthedesignelevationplusthespecifiedoverfillforsettlement.Theopeningattheoutletendoftheterraceshouldhaveacrosssectionequaltothatspecifiedfortheterracechannel.•Channelgradesmaybeeitheruniformorvariablewithamaximumgradeof0.6feetper100feetlength(0.6%).Forshortdistances,terracegradcsmaybeincrcascdtoimprovealignment.Thechannelvelocityshouldnotexceedthatwhichisnonerosiveforthesoiltype.•Allgradientterracesshouldhaveadequateoutlets.Suchanoutletmaybeagrassedwaterway,vegetatedarea,ortileoutlet.Inallcasestheoutletmustconveyrunofffromtheterraceorterracesystemtoapointwhcrctheoutflowwillnotcauscdamage.Vegetativecovershouldbeusedintheoutletchannel.•Thedesignelevationofthewatersurfaceoftheterraceshouldnotbelowerthanthedesignelevationofthewatersurfaceintheoutletattheirjunction,whenbothareoperatingatdesignflow.ohimeConstructionStonnwa/erPollutionPieen/ioniius!2012 •Verticalspacingdeterminedbytheabovemethodsmaybeincreasedasmuchas0.5feetor10percent,whicheverisgreater,toprovidebetteralignmentorlocation,toavoidobstacles,toadjustforequipmentsize,ortoreachasatisfactoryoutlet.Thedrainageareaabovetheterraceshouldnotexceedtheareathatwouldbedrainedbyaterracewithnormalspacing.•Theterraceshouldhaveenoughcapacitytohandlethepeakrunoffexpectedfroma2-year,24-hourdesignstormwithoutovertopping.•Theterracecross-sectionshouldbeproportionedtofitthelandslope.Theridgeheightshouldincludeareasonablesettlementfactor.Theridgeshouldhaveaminimumtopwidthof3feetatthedesignheight.Theminimumcross-sectionalareaoftheterracechannelshouldbeSsquarefeetforlandslopesof5percentorless,7squarefeetforslopesfrom5to8percent,and6squarefeetforslopessteeperthan8percent.Theterracecanbeconstructedwideenoughtobemaintainedusingasmallvehicle.Mahztena,,ce•Maintenanceshouldbeperformedasneeded.TerracesshouldbeStandardsinspectedregularly;atleastonceayear,andafterlargestormevents.Slopetoadequate10mm.Figure4.1.6—GradientTerracesobtineConstructionSIonnwaterPollutionPreeu/ionitust2012 BMPC140:DustControlPurposeDustcontrolpreventswindtransportofdustfromdisturbedsoilsurfacesontoroadways.drainageways.andsurfacewaters.conditionsofUse•Inareas(includingroadways)subjecttosurfaceandairmovementofdustwhereon-siteandoff-siteimpactstoroadways,drainageways,orsurfacewatersarelikely.Designand.Vegetateormulchareasthatwillnotreceivevehicletraffic.InareasInstallationwhereplanting,mulching,orpavingisimpractical,applygravelorSpecicationslandscapingrock.•Limitdustgenerationbyclearingonlythoseareaswhereimmediateactivitywilltakeplace,leavingtheremainingarea(s)intheoriginalcondition.Maintaintheoriginalgroundcoveraslongaspractical.•Constructnaturalorartificialwindbreaksorwindscreens.Thesemaybedesignedasenclosuresforsmalldustsources.•Sprinklethesitewithwateruntilsurfaceiswet.Repeatasneeded.Topreventcarryoutofmudontostreet.refertoStabilizedConstructionEntrance(BMPCl05).•Irrigationwatercanbeusedfordustcontrol.Irrigationsystemsshouldbeinstalledasafirststeponsiteswheredustcontrolisaconcern.•Sprayexposedsoilareaswithadustpalliative,followingthemanufacturer’sinstructionsandcautionsregardinghandlingandapplication.Usedoilisprohibitedfromuseasadustsuppressant.LocalgovernmentsmayapproveotherdustpalliativessuchascalciumchlorideorPAM.•PAM(BMPCl26)addedtowateratarateof0.5lbs.per1,000gallonsofwaterperacreandappliedfromawatertruckismoreeffectivethanwateralone.Thisisduetoincreasedinfiltrationofwaterintothesoilandreducedevaporation.Inaddition,smallsoilparticlesarebondedtogetherandarenotaseasilytransportedbywind.AddingPAMmayactuallyreducethequantityofwaterneededfordustcontrol.UseofPAMcouldbeacost-effectivedustcontrolmethod.Techniquesthatcanbeusedforunpavedroadsandlotsinclude:•Lowerspeedlimits.Highvehiclespeedincreasestheamountofduststirredupfromunpavedroadsandlots.•Upgradctheroadsurfacestrcngthbyimprovingparticlesize,shapc.andmineraltypesthatmakeupthesurfaceandbasematerials.•Addsurfacegraveltoreducethesourceofdustemission.Limittheamountoffineparticles(thosesmallerthan.075mm)to10to20percent.oltimeCons/nec/ionStonni’uterPollutionPieen/ioniius!20120 •Usegeotextilefabricstoincreasethestrengthofnewroadsorroadsundergoingreconstruction.•Encouragetheuseofalternate,pavedroutes,ifavailable.•Restrictuseofpavedroadwaysbytrackedvehiclesandheavytruckstopreventdamagetoroadsurfaceandbase.•Applychemicaldustsuppressantsusingtheadmixmethod,blendingtheproductwiththetopfewinchesofsurfacematerial.Suppressantsmayalsobeappliedassurfacetreatments.•Paveunpavedpermanentroadsandothertraffickedareas.•Usevacuumstreetsweepers.•Removemudandotherdirtpromptlysoitdoesnotdryandthenturnintodust.•Limitdust-causingworkonwindydays.•ContactyourlocalAirPollutionControlAuthorityforguidanceandtrainingonotherdustcontrolmeasures.CompliancewiththelocalAirPollutionControlAuthorityconstitutescompliancewiththisBMP.MaintenanceResprayareaasnecessarytokeepdusttoaminimum.StandardsBMPCISO:MaterialsonHandPurposeKeepquantitiesoferosionpreventionandsedimentcontrolmaterialsontheprojectsiteatalltimestobeusedforregularmaintenanceandemergencysituationssuchasunexpectedheavysummerrains.Havingthesematerialson-sitereducesthetimeneededtoimplementBMPswheninspectionsindicatethatexistingBMPsarenotmeetingtheConstructionSWPPPrequirements.Inaddition,contractorscansavemoneybybuyingsomematerialsinbulkandstoringthemattheirofficeoryard.C’o,,ditio,,sofUse•Constructionprojectsofanysizeortypecanbenefitfromhavingmaterialsonhand.Asmallcommercialdevelopmentprojectcouldhavearollofplasticandsomegravelavailableforimmediateprotectionofbaresoilandtemporarybermconstruction.Alargeearthworkproject,suchashighwayconstruction,mighthaveseveraltonsofstraw,severalrollsofplastic,flexiblepipe,sandbags,geotextilefabricandsteel“T”posts.•Materialsarestockpiledandreadilyavailablebeforeanysiteclearing,grubbing,orearthworkbegins.Alargecontractorordevelopercouldkeepastockpileofmaterialsthatareavailableforuseonseveralprojects.•Tfstoragespaceattheprojectsiteisatapremium,thecontractorcouldmaintainthematerialsattheirofficeoryard.Theofficeoryardmustbelessthananhourfromtheprojectsite.ohi;neConstructionStornni’atcrPollutionPreentioniiust2012I DesignandDependingonprojecttype,size,complexity,andlength,materialsandInstallationquantitieswillvary.AgoodminimumlistofitemsthatwillcoverSpecjficationsnumeroussituationsincludes:MaterialClearPlastic,6milDrainpipe,6or8inchdiameterSand b a g s ,filled___ _ ___ ___ ___ _ ___ __StrawBalesformulching,QuarrySpallsWashedGravelGeotextileFabricCatchBasinInsertsSteel‘7”PostsSiltfencematerialStrawWattlesMaintenance•Allmaterialswiththeexceptionofthequarryspalls,steel“I”posts,Standardsandgravelshouldbekeptcoveredandoutofbothsunandrain.•Re-stockmaterialsusedasneeded.BMPCISI:ConcreteHandlingPurposeConcreteworkcangenerateprocesswaterandslurrythatcontainfineparticlesandhighpH,bothofwhichcanviolatewaterqualitystandardsinthereceivingwater.ConcretespillageorconcretedischargetosurfacewatersoftheStateisprohibited.UsethisBMPtominimizeandeliminateconcrete,concreteprocesswater,andconcreteslurryfromenteringwatersofthestate.ConditionsofUseAnytimeconcreteisused,utilizethesemanagementpractices.Concreteconstructionprojectsinclude,butarenotlimitedto,thefollowing:•Curbs•Sidewalks•Roads•Bridges•Foundations•Floors•RunwaysDesignand•Washoutconcretetruckchutes,pumps,andinternalsintoformedInstallationareasonly.AssurethatwashoutofconcretetrucksisperformedoffchimeConstructionStonuwaterPollutionPieentioniius!20)22 Specjficationssiteorindesignatedconcretewashoutareas.Donotwashoutconcretetrucksontotheground,orintostormdrains,openditches,streets,orstreams.RefertoBMPC154forinformationonconcretewashoutareas.•Returnunusedconcreteremaininginthetruckandpumptotheoriginatingbatchplantforrecycling.Donotdumpexcessconcreteonsite,exceptindesignatedconcretewashoutareas.•Washoffhandtoolsincluding,butnotlimitedto,screeds,shovels,rakes,floats,andtrowelsintoformedareasonly.•Washequipmentdifficulttomove,suchasconcretepayersinareasthatdonotdirectlydraintonaturalorconstructedstormwaterconveyances.•Donotallowwashdownfromareas,suchasconcreteaggregatedriveways,todraindirectlytonaturalorconstructedstormwaterconveyances.•Containwashwaterandleftoverproductinalinedcontainerwhennoformedareasareavailable,.Disposeofcontainedconcreteinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.•Alwaysuseformsorsolidbarriersforconcretepours,suchaspilings,within15-feetofsurfacewaters.•RefertoBMPsC252andC253forpHadjustmentrequirements.•RefertotheConstructionStormwaterGeneralPermitforpHmonitoringrequirementsiftheprojectinvolvesoneofthefollowingactivities:•Significantconcretework(greaterthan1,000cubicyardspouredconcreteorrecycledconcreteusedoverthelifeofaproject).•Theuseofengineeredsoilsamendedwith(butnotlimitedto)Portlandcement-treatedbase,cementkilndustorflyash.•Dischargingstormwatertosegmentsofwaterbodiesonthe303(d)list(Category5)forhighpH.MaintenanceCheckcontainersforholesinthelinerdailyduringconcretepoursandStandardsrepairthesameday.obtineConstructionStornni’aterPollullo,,Pieentionuus!2012 BMPC152:SawcuttingandSurfacingPollutionPreventionPurposeSawcuttingandsurfacingoperationsgenerateslurryandprocesswaterthatcontainsfineparticlesandhighpH(concretecutting),bothofwhichcanviolatethewaterqualitystandardsinthereceivingwater.ConcretespillageorconcretedischargetosurfacewatersoftheStateisprohibited.UsethisBMPtominimizeandeliminateprocesswaterandslurrycreatedthroughsawcuttingorsurfacingfromenteringwatersoftheSlate.C’onditio,zsofUseUtilizethesemanagementpracticesanytimesawcuttingorsurfacingoperationstakeplace.Sawcuttingandsurfacingoperationsinclude,butarenotlimitedto,(liefollowing:•Sawing•Coring•Grinding•Roughening•Hydro-demolition•BridgeandroadsurfacingDesignand•Vacuumslurryandcuttingsduringcuttingandsurfacingoperations.Installation•SlurryandcuttingsshallnotremainonpermanentconcreteorasphaltSpec(flcationspavementovernight.•Slurryandcuttingsshallnotdraintoanynaturalorconstructeddrainageconveyanceincludingstornnvatersystems.Thismayrequiretemporarilyblockingcatchbasins.•Disposeofcollectedslurryandcuttingsinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.•Donotallowprocesswatergeneratedduringhydro-demohition,surfacerougheningorsimilaroperationstodraintoanynaturalorconstructeddrainageconveyanceincludingstormwatersystems.Disposeprocesswaterinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.•Handleanddisposecleaningwastematerialanddemolitiondebrisinamannerthatdoesnotcausecontaminationofwater.Disposeofsweepingmaterialfromapick-upsweeperatanappropriatedisposalsite.Mainte,,a,,ceContinuallymonitoroperationstodeterminewhetherslurry,cuttings,orStandardsprocesswatercouldenterwatersofthestate.Ifinspectionsshowthataviolationofwaterquali’standardscouldoccur,stopoperationsandimmediatelyimplementpreventivemeasuressuchasberms,barriers,secondarycontainment,andvacuumtrucks.ohmicCons/rue/jot;S/ornni’a/erPollulionPieen/ionitus!2012 BMPC153:MaterialDelivery,StorageandContainmentPurposePrevent,reduce,oreliminatethedischargeofpollutantstothestormwatersystemorwatercoursesfrommaterialdeliveryandstorage.Minimizethestorageofhazardousmaterialson-site,storematerialsinadesignatedarea,andinstallsecondarycontainment.conditionsofUseTrodrarIaforaaonrionidIrandoraoffooinana•Petroleumproductssuchasfuel,oilandgrease•Soilstabilizersandbinders(e.g.Polyacrylamide)•Fertilizers,pesticidesandherbicides•Detergents•Asphaltandconcretecompounds•1-lazardouschemicalssuchasacids,lime,adhesives,paints,solventsandcuringcompounds•AnyothermaterialthatmaybedetrimentalifreleasedtotheenvironmentDesignandTfooinodanomiIiiI,,stallatwn•Temporarystorageareashouldbelocatedawayfromvehiculartraffic,Specificationsneartheconstructionentrance(s),andawayfromwaterwaysorstormdrains.•MaterialSafetyDataSheets(MSDS)shouldbesuppliedforallmaterialsstored.Chemicalsshouldbekeptintheiroriginallabeledcontainers.•Hazardousmaterialstorageon-siteshouldbeminimized.•Hazardousmaterialsshouldbehandledasinfrequentlyaspossible.•Duringthewetweatherseason(Oct1—April30).considerstoringmaterialsinacoveredarea.•Materialsshouldbestoredinsecondarycontainments,suchasearthendike,horsetrough,orevenachildren’swadingpooifornon-reactivematerialssuchasdetergents,oil,grease,andpaints.Smallamountsofmaterialmaybesecondarilycontainedin“busboy”traysorconcretemixingtrays.•Donotstorechemicals,drums,orbaggedmaterialsdirectlyontheground.Placetheseitemsonapalletand,whenpossible,andwithinsecondary’containment.•Ifdrumsmustbekeptuncovered,storethemataslightangletoreducepondingofrainwateronthelidstoreducecorrosion.Domedplasticcoversareinexpensiveandsnaptothetopofdrums,preventingwaterfromcollecting.ohuneConstructionStornnraterPollutionPreentionuus!2012 ManaSeraAraandSondarConamnPraILiquids.petroleumproducts,andsubstanceslistedin40CFRParts110,117,or302shallbestoredinapprovedcontainersanddrumsandshallnotbeoverfilled.Containersanddrumsshallbestoredintemporarysecondarycontainmentfacilities.•Temporarysecondarycontainmentfacilitiesshallprovideforaspillcontainmentvolumeabletocontain10%ofthetotalenclosedcontainervolumeofallcontainers,or110%ofthecapacityofthelargcstcontainerwithinitsboundary,whicheverisgrcatcr.•Secondarycontainmentfacilitiesshallbeimpervioustothematerialsstorcdthereinforaminimumcontacttimeof72hours.•Secondarycontainmentfacilitiesshallbemaintainedfreeofaccumulatedrainwaterandspills.Intheeventofspillsorleaks,accumulatedrainwaterandspillsshallbecollectedandplacedintodrums.Theseliquidsshallbehandledashazardouswasteunlesstestingdeterminesthemtobenon-hazardous.•Sufficientseparationshouldbeprovidedbetweenstoredcontainerstoallowforspillcleanupandemergencyresponseaccess.•Duringthewetweatherseason(Oct1—April30),eachsecondarycontainmentfacilityshallbecoveredduringnon-workingdays,priortoandduringrainevents.•Keepmaterialstorageareasclean,organizedandequippedwithanamplesupplyofappropriatespillclean-upmaterial(spillkit).•Thespillkitshouldinclude,ataminimuni:•1-WaterResistantNylonBag•3-OilAbsorbentSocks3”x4’•2-OilAbsorbentSocks3”x10’•12-OilAbsorbentPadsI7”xl9”•1-PairSplashResistantGoggles•3-PairNitrileGloves•10-DisposableBagswithTies•InstructionsohmicConstructionSto,mu’atc;PollutionPreentioniiust20)2 BMPCl54:ConcreteWashoutAreaPurposePreventorreducethedischargeofpollutantstostormwaterfromconcretewastebyconductingwashoutoff-site,orperformingon-sitewashoutinadesignatedareatopreventpollutantsfromenteringsurfacewatersorgroundwater.(‘auditionsofUseConcretewashoutareabestmanagementpracticesareimplementedonconstructionprojectswhere:•Concreteisusedasaconstructionmaterial•Itisnotpossibletodisposeofallconcretewastewaterandwashoutoff-site(readymixplant,etc.).•Concretetrucks,pumpers,orotherconcretecoatedequipmentarewashedon-site.•Note:Iflessthan10concretetrucksorpumpersneedtobewashedouton-site,thewashwatermaybedisposedofinaformedareaawaitingconcreteoranuplanddisposalsitewhereitwillnotcontaminatesurfaceorgroundwater.Theuplanddisposalsiteshallbeatleast50feetfromsensitiveareassuchasstormdrains,openditches,orwaterbodies,includingwetlands.DesignandInaionInstallationThefollowingstepswillhelpreducestormwaterpollutionfromconcreteSpecificationswastes:•Performwashoutofconcretetrucksoff-siteorindesignatedconcretewashoutareasonly.•Donotwashoutconcretetrucksontotheground,orintostormdrains,openditches,streets,orstreams.•Donotallowexcessconcretetobedumpedon-site,exceptindesignatedconcretewashoutareas.•Concretewashoutareasmaybeprefabricatedconcretewashoutcontainers,orself-insEalledstructures(above-gradeorbelow-grade).•Prefabricatedcontaincrsarcmostresistanttodamagcandprotectagainstspillsandleaks.Companiesmayofferdeliveryserviceandprovideregularmaintenanceanddisposalofsolidandliquidwaste.•Ifself-installedconcretewashoutareasareused,below-gradestructuresarepreferredoverabove-gradestructuresbecausetheyarelesspronetospillsandleaks.•Self-installedabove-gradestructuresshouldonlybeusedifexcavationisnotpracticaLobtineConstructionStor,uni’cwerPothilionPreen/ioniius!2012 Edaion•DiscusstheconcretemanagementtechniquesdescribedinthisBMPwiththeready-mixconcretesupplierbeforeanydeliveriesaremade.•EducateemployeesandsubcontractorsontheconcretewastemanagementtechniquesdescribedinthisBMP.•Arrangeforcontractor’ssuperintendentorCertifiedErosionandSedimentControlLead(CESCL)tooverseeandenforceconcretewastemanagementprocedures.•Asignshouldbeinstalledadjacenttoeachtemporaryconcretewashoutfacilitytoinformconcreteequipmentoperatorstoutilizetheproperfacilities.ConraIncorporaterequirementsforconcretewastemanagementintoconcretesupplierandsubcontractoragreements.LoaionandPan•Locatewashoutareaatleast50feetfromsensitiveareassuchasstormdrains,openditches,orwaterbodies,includingwetlands.•Allowconvenientaccessforconcretetrucks,preferablyneartheareawheretheconcreteisbeingpoured.•Iftrucksneedtoleaveapavedareatoaccesswashout,preventtrack-outwithapadofrockorquarryspalls(seeBMPC105).Theseareasshouldbefarenoughawayfromotherconstructiontraffictoreducethelikelihoodofaccidentaldamageandspills.•Thenumberoffacilitiesyouinstallshoulddependontheexpecteddemandforstoragecapacity.•Onlargesiteswithextensiveconcretework,washoutsshouldbeplacedinmultiplelocationsforeaseofusebyconcretetruckdrivers.On-iTorarConrWaoFail,TraniTrWaoProdr•Temporaryconcrctcwashoutfacilitiesshallbelocatedaminimumof50ftfromsensitiveareasincludingstormdraininlets,opendrainagefacilities,andwatercourscs.SeeFigures4.1.7and4.1.8.•Concretewashoutfacilitiesshallbeconstructedandmaintainedinsufficientquantityandsizetocontainallliquidandconcretewastegcneratcdbywashoutoperations.•Approximately7gallonsofwashwaterareusedtowashonetruckchute.•Approximately50gallonsareusedtowashoutthehopperofaconcretepumptruck.obtineCenisiritetionS/ou,;ni’aterPollutionfireen/ioniius!2012 •Washoutofconcretetrucksshallbeperformedindesignatedareasonly.•Concretewashoutfromconcretepumperbinscanbewashedintoconcretepumpertrucksanddischargedintodesignatedwashoutareaorproperlydisposedofoff-site.•Onceconcretewastesarewashedintothedesignatedareaandallowedtoharden.theconcreteshouldbebrokenup,removed,anddisposedofperapplicablesolidwasteregulations.Disposeofhardenedconcreteonaregularbasis.•TemporaryAbove-GradeConcreteWashoutFacility•Temporaryconcretewashoutfacility(typeabovegrade)shouldbeconstructedasshownonthedetailsbelow,witharecommendedminimumlengthandminimumwidthof10ft,butwithsufficientquantityandvolumetocontainallliquidandconcretewastegeneratedbywashoutoperations.•Plasticliningmaterialshouldbeaminimumof10milpolyethylenesheetingandshouldbefreeofholes,tears,orotherdefectsthatcompromisetheimpermeabilityofthematerial.•TemporaryBelow-GradeConcreteWashoutFacility•Temporaryconcretewashoutfacilities(typebelowgrade)shouldbeconstructedasshownonthedetailsbelow,witharecommendedminimumlengthandminimumwidthof10ft.Thequantityandvolumeshouldbesufficienttocontainallliquidandconcretewastegeneratedbywashoutoperations.•Lathandflaggingshouldbecommercialtype.•Plasticliningmaterialshallbeaminimumof10milpolyethylenesheetingandshouldbefreeofholes,tears,orotherdefectsthatcompromisetheimpermeabilityofthematerial.•Linerseamsshallbeinstalledinaccordancewithmanufacturers’recommendations.•Soilbaseshallbepreparedfreeofrocksorotherdebristhatmaycausetearsorholesintheplasticliningmaterial.MaintenanceInionandMainnanStandards•InspectandverifythatconcretewashoutBMPsareinplacepriortothecommencementofconcretework.•Durinaperiodsofconcretework.inspectdailytoverifycontinuedperformance.•Checkoverallconditionandperformance.•Checkremainingcapacity(%full).olumeConstructionStor,nwaterPollutionPieentionuus!2012 •Ifusingself-installedwashoutfacilities.veri&plasticlinersareintactandsidewallsarenotdamaged.•Ifusingprefabricatedcontainers,checkforleaks.•Washoutfacilitiesshallbemaintainedtoprovideadequateholdingcapacitywithaminimumfreeboardof12inches.•Washoutfacilitiesmustbecleaned,ornewfacilitiesmustbeconstructedandreadyforuseoncethewashoutis75%hill.•Ifthewashoutisnearingcapacity,vacuumanddisposeofthewastematerialinanapprovedmanner.•Donotdischargeliquidorslurrytowaterways,stormdrainsordirectlyontoground.•Donotusesanitary’sewerwithoutlocalapproval.•Placeasecure,non-collapsing,non-watercollectingcoverovertheconcretewashoutfacility’priortopredictedwetweathertopreventaccumulationandoverflowofprecipitation.•Removeanddisposeofhardenedconcreteandreturnthestructuretoafunctionalcondition.Concretemaybereusedon-siteorhauledawayfordisposalorrecycling.•Whenyouremovematerialsfromtheself-installedconcretewashout,buildanewstructure;or,ifthepreviousstructureisstillintact,inspectforsignsofweakeningordamage,andmakeanynecessaryrepairs.Re-linethestructurewithnewplasticaftereachcleaning.RoaofTorarConrWaoFaiii•Whentemporaryconcretewashoutfacilitiesarenolongerrequiredforthework.thehardenedconcrete,slurriesandliquidsshallberemovedandproperlydisposedof.•Materialsusedtoconstructtemporaryconcretewashoutfacilitiesshallberemovedfromthesiteoftheworkanddisposedoforrecycled.•Holes,depressionsorothergrounddisturbancecausedbytheremovalofthctcmporaryconcrctcwashoutfaciliticsshallbebackfillcd,repaired,andstabilizedtopreventerosion.oluineCons/rite/ionS/ormii’aterPollutionPreentionitus!20120 Figure4.1.7a—ConcreteWashoutAreaohnneConstructionSlornni’aterPollutionPreenilonuus!2012I10riftAStCIn,lATHMOrNGONJSIDESNnA-KNUT10SCAII10r,ptThD___UNOT10SCALEMIIIIUUU—LqO0DWAIlSSECUREDF*SIENEOLJAOUPAOENIIREPEPIMEICHN._WITHTWOSIMS‘STWO.5FACgO2.12POUCH—.rI000FRMAEVAS:/IDmITHIJICHNINCI.ACTUALLAYCHJTDCTtRUI%Cp...ThEflt._D,2.ThECO.CRCTCWASHOUT5GW(551PACEb)$nAttOrn.SIuIloMThA.ToInOrfl!IWPoTmLONCRnrWASHOUTrAcIur,HOTTOSCAUTnflADQVCGRACrWIThW000FW{KS atE5JA,ILS(2PRBALE)s00STARES(2ERBALE)•1vmics/SNCaWIRE7/-7Y61PtASlICUMNO///PeAT?,tLLAWRLt/(OrIOML)n.-r(40110SCALEPLYA000-I200ow’.€SflnnPAJ,’TEDwHrTt-4—----—I.n.n!UU(59mm19mmr21.7.)COI4CRflWASHOUTSIGNDtTML(OREOJVAW(1)$HHST_200mmSTAPhDETAILI.ACIUALLAYOUTOCTETISArNED(NTHEFiCW,2.THEcONCRETEWASkCWLION(SEEnO.4—15)SKALLBEINSTALLEDWITHINIDmOFThE1ZUP0P.YCONCRETEWASHOUTFAC,LmY.r.LImn/rcA-I.OWISACftI’2Figure4.1.7b—ConcreteWashoutAreaFigure4.1.8—PrefabricatedConcreteWashoutContainerwlRampohinwConstructionS1orn,i’aterPollutionPreeu/ioniius!201270mAF.ASIICU0f2-NITTOSCALETYPEASOVECR4DrWITHSTRAWBAILS BMPC160:CertifiedErosionandSedimentControlLeadPurposeTheprojectproponentdesignatesatleastonepersonastheresponsiblerepresentativeinchargeoferosionandsedimentcontrol(ESC),andwaterqualityprotection.ThedesignatedpersonshallbetheCertifiedErosionandSedimentControlLead(CESCL)whoisresponsibleforensuringcompliancewithalllocal,state,andfederalerosionandsedimentcontrolandwaterqualityrequirements.ConditionsofUseACESCLshallbemadeavailableonprojectsoneacreorlargerthatdischargestormwatertosurfacewatersofthestate.SiteslessthanoneacremayhaveapersonwithoutCESCLcertificationconductinspections;samplingisnotrequiredonsitesthatdisturblessthananacre.•TheCESCLshall:•HaveacurrentcertificateprovingattendanceinanerosionandsedimentcontroltrainingcoursethatmeetstheminimumESCtrainingandcertificationrequirementsestablishedbyEcology(seedetailsbelow).EcologywillmaintainalistofESCtrainingandcertificationprovidersat:http://www.ecy.wa.aov/proQrams/wg/stormwater/cescl.htmlOR•BeaCertifiedProfessionalinErosionandSedimentControl(CPESC);foradditionalinformationgoto:nvw.cpesc.netSpecjfications•Certificationshallremainvalidforthreeyears.•TheCESCLshallhaveauthoritytoactonbehalfofthecontractorordeveloperandshallbeavailable,oron-call,24hoursperdaythroughouttheperiodofconstruction.•TheConstructionSWPPPshallincludethename,telephonenumber,faxnumber,andaddressofthedesignatedCESCL.•ACESCLmayprovideinspectionandcomplianceservicesformultipleconstructionprojectsinthesamegeographicregion.DutiesandresponsibilitiesofthcCESCLshallinclude,butarcnotlimitedtothefollowing:•MaintainingpermitfileonsiteatalltimeswhichincludestheConstructionSWPPPandanyassociatedpermitsandplans.•DirectingBMPinstallation,inspection,maintenance,modification,andremoval.ohimeConstructionStonnitoterPollutionPreeu/ionuus!2012 •UpdatingallprojectdrawingsandtheConstructionSWPPPwithchangesmade.•CompletinganysamplingrequirementsincludingreportingresultsusingWebDMR.•Keepingdailylogs,andinspectionreports.Inspectionreportsshouldinclude:•Inspectiondate/time.•Weatherinformation;generalconditionsduringinspectionandapproximateamountofprecipitationsincethelastinspection.•AsummaryorlistofallBMPsimplemented,includingobservationsofallerosion/sedimentcontrolstructuresorpractices.Thefollowingshallbenoted:1.LocationsofBMPsinspected.2.LocationsofBMPsthatneedmaintenance.3.LocationsofBMPsthatfailedtooperateasdesignedorintended.4.LocationsofwhereadditionalordifferentBMPsarerequired.•Visualmonitoringresults,includingadescriptionofdischargedstorrnwater.Thepresenceofsuspendedsediment,turbidwater,discoloration,andoilsheenshallbenoted,asapplicable.•Anywaterqualitymonitoringperformedduringinspection.•Generalcommentsandnotes,includingabriefdescriptionofanyBMPrepairs,maintenanceorinstallationsmadeasaresultoftheinspection.•Facilitate,participatein,andtakecorrectiveactionsresultingfrominspectionsperformedbyoutsideagenciesortheowner.BMPC162:SchedulingPurposeSequencingaconstmctionprojectreducestheamountanddurationofsoilexposedtoerosionbywind,rain,runoff,andvehicletracking.conditionsofUseTheconstructionsequencescheduleisanorderlylistingofallmajorland-disturbingactivitiestogetherwiththenecessaryerosionandsedimentationcontrolmeasuresplannedfortheproject.Thistypeofscheduleguidesthecontractoronworktobedonebeforeotherworkisstartedsothatseriouserosionandsedimentationproblemscanbeavoided.Followingaspecifiedworkschcdulethatcoordinatesthetimingofland-disturbingactivitiesandtheinstallationofcontrolmeasuresisperhapsthemostcost-effectivewayofcontrollingerosionduringconstruction.TheremovalofsurfacegroundcoverleavesasitevulnerabletoacceleratedolunieConstrudilonS/onnii’aterPollutionPit’en/ionuus!2012 erosion.Constructionproceduresthatlimitlandclearingprovidetimelyinstallationoferosionandsedimentationcontrols,andrestoreprotectivecoverquicklycansignificantlyreducetheerosionpotentialofasite.Design.Minimizeconstructionduringrainyperiods.Coissiderations.Scheduleprojectstodisturbonlysmallportionsofthesiteatanyonetime.Completegradingassoonaspossible.Immediatelystabilizethedisturbedportionbeforegradingthenextportion.Practicestagedseedinginordertorevegetatecutandfillslopesastheworkprogresses.ohinwConstructionS/ornni’aterPothilionPieen/ionxius!2012 BMPC200:InterceptorDikeandSwalePurposeProvidearidgeofcompactedsoil,oraridgewithanupslopeswale,atthetoporbaseofadisturbedslopeoralongtheperimeterofadisturbedconstructionareatoconveystormwater.Usethedikeandlorswaletointercepttherunofffromunprotectedareasanddirectittoareaswhereerosioncanbecontrolled.Thiscanpreventstormrunofffromenteringtheworkareaorsediment-ladenrunofffromleavingtheconstructionsite.C’onditionsofUseWheretherunofffromanexposedsiteordisturbedslopemustbeconveyedtoanerosioncontrolfacilitywhichcansafelyconveythestormwater.•Locateupslopeofaconstructionsitetopreventrunofffrontenteringdisturbedarea.•Whenplacedhorizontallyacrossadisturbedslope,itreducestheamountandvelocity’ofrunoffflowingdowntheslope.•Locatedownslopetocollectrunofffromadisturbedareaanddirectwatertoasedimentbasin.Designand•Dikeand/orswaleandchannelmustbestabilizedwithtemporaryorInstallatio,,permanentvegetationorotherchannelprotectionduringconstruction.Specjfications•Channelrequiresapositivegradefordrainage;steepergradesrequirechannelprotectionandcheckdams.•Reviewconstructionforareaswhereovertoppingmayoccur.•Canbeusedattopofnewfillbeforevegetationisestablished.•Maybeusedasapermanentdiversionchanneltocarrytherunoff.•Sub-basintributaryareashouldbeoneacreorless.•Designcapacityforthepeakflowfroma10-year,24-hourstorm,assumingaTypeIArainfalldistribution,fortemporary’facilities.Alternatively,use1.6timesthe10-year,1-hourflowindicatedbyanapprovedcontinuousrunoffmodel.Forfacilitiesthatwillalsoserveonapermanentbasis,consultthelocalgovernment’sdrainagerequirements.Inrordishallmeetthefollowingcriteria:TopWidth2feetminimum.Height1.5feetminimumonberm.SideSlope2H:IVorflatter.GradeDependsontopography,however,dikesystemminimumis0.5%,andmaximumis1%.CompactionMinimumof90percentASTMD698standardproctor.olitmeConstructionS!onnii’aterPollutionPieentionuus!2012 HorizontalSpacingofInterceptorDikes:AraSoSoPriiFoaEn20H:IVorless3-5%300feet(10to20)F1:lV5-10%200feet(4to10)1+IV10-25%100feet(2to4)H:IV25-50%50feetStabilizationdependsonvelocityandreachSlopes<5%Seedandmulchappliedwithin5daysofdikeconstruction(seeBMPC121.Mulching).Slopes5-40%Dependentonrunoffvelocitiesanddikematerials.Stabilizationshouldbedoneimmediatelyusingeithersodorripraporothermeasurestoavoiderosion.•Theupslopesideofthedikeshallprovidepositivedrainagetothedikeoutlet.Noerosionshalloccurattheoutlet.Provideenergydissipationmeasuresasnecessary.Sediment-ladenrunoffmustbereleasedthroughasedimenttrappingfacility.•Minimizeconstructiontrafficovertemporarydikes.Usetemporarycrossculvertsforchannelcrossing.Inrorashallmeetthefollowingcriteria:BottomWidth2feetminimum;thecross-sectionbottomshallbelevel.DepthI-footminimum.SideSlope2H:IVorflatter.GradeMaximum5percent,withpositivedrainagetoasuitableoutlet(suchasasedimentpond).StabilizationSeedasperBMPC120,cmoraranPennanentSeeinorPC202,Cmmcl12inchesthickriprappressedintothebankandextendingatleast8inchesverticalfromthebottom.•Inspectdiversiondikesandinterceptorswalesonceaweekandaftereveryrainfall.Immediatelyremovesedimentfromtheflowarea.•Damagecausedbyconstructiontrafficorotheractivitymustberepairedbeforetheendofeachworkingday.Checkoutletsandmaketimelyrepairsasneededtoavoidgullyformation.Whentheareabelowthetemporarydiversiondikeispermanentlystabilized,removethedikeandfillandstabilizethechanneltoblendwiththenaturalsurface.ohuneConstructionStonmi’a!erPollutionPieentionuus!2012 BMPC201:Grass-LinedChannelsPurposeToprovideachannelwithavegetativeliningforconveyanceofrunoff.SeeFhure4.2.1fortypicalgrass-linedchannels.ConditionsofUseThispracticeappliestoconstructionsiteswhereconcentratedrunoffneedstobecontainedtopreventerosionorflooding.•Whenavegetativeliningcanprovidesufficientstabilityforthechannelcrosssectionandatlowervelocitiesofwater(normallydependentongrade).Thismeansthatthechannelslopesaregenerallylessthan5percentandspaceisavailableforarelativelylargecrosssection.•Typicalusesincluderoadsideditches,channelsatpropertyboundaries,outletsfordiversions,andotherchannelsanddrainageditchesinlowareas.•Channelsthatwillbevegetatedshouldbeinstalledbeforemajorearthworkandhydroseededwithabondedfibermatrix(BFM).Thevegetationshouldbewellestablished(i.e.,75percentcover)beforewaterisallovedtoflowintheditch.Withchannelsthatwillhavehighflows,erosioncontrolblanketsshouldbeinstalledoverthehydroseed.Ifvegetationcannotbeestablishedfromseedbeforewaterisallowedintheditch,sodshouldbeinstalledinthebottomoftheditchinlieuofhydromulchandblankets.DesignandLocatethechannelwhereitcanconformtothetopographyandotherInstallationfeaturessuchasroads.Specfflcations•Locatethemtousenaturaldrainagesystemstothegreatestextentpossible.•Avoidsharpchangesinalignmentorbendsandchangesingrade.•Donotreshapethelandscapetofitthedrainagechannel.•Themaximumdesignvelocityshallbebasedonsoilconditions,typeofvcgctation,andmcthodofrcvegctation,butatnotimesshaLlvelocityexceed5feet/second.Thechannelshallnotbeovertoppedbythepeakrunofffroma10-year,24-hourstorm,assumingaTypeIArainfalldistribution.Alternatively,use1.6timesthe10-year,1-hourflowindicatedbyanapprovedcontinuousrunoffmodeltodetermineaflowratewhichthechannelmustcontain.•Wherethegrass-linedchannelwiLLalsofunctionasapermanenistormwaterconveyancefacility,consultthedrainageconveyancerequirementsofthelocalgovernmentwithjurisdiction.olzi;wConstructionS!onnii’aterPollutionPieen/ionxius!2012 •Anestablishedgrassorvegetatedliningisrequiredbeforethechannelcanbeusedtoconveystormwater,unlessstabilizedwithnetsorblankets.•Ifdesignvelocityofachanneltobevegetatedbyseedingexceeds2fUsec,atemporarychannellinerisrequired.Geotextileorspecialmulchprotectionsuchasfiberglassrovingorstrawandnettingprovidesstabilityuntilthevegetationisfullyestablished.SeeFicure4.2.2.•Checkdamsshallberemovedwhenthegrasshasmaturedsufficientlytoprotecttheditchorswaleunlesstheslopeoftheswaleisgreaterthan4percent.Theareabeneaththecheckdamsshallbeseededandmulchedimmediatelyafterdamremoval.•Ifvegetationisestablishedbysodding,thepermissiblevelocityforestablishedvegetationmaybeusedandnotemporarylinerisneeded.•Donotsubjectgrass-linedchanneltosedimentationfromdisturbedareas.Usesediment-trappingBMPsupstreamofthechannel.•V-shapedgrasschannelsgenerallyapplywherethequantityofwaterissmall,suchasinshortreachesalongroadsides.TheV-shapedcrosssectionisleastdesirablebecauseitisdifficulttostabilizethebottomwherevelocitiesmaybehigh.•Trapezoidalgrasschannelsareusedwhererunoffvolumesarelargeandslopeislowsothatvelocitiesarenonerosivetovegetatedlinings.(Note:itisdifficulttoconstructsmallparabolicshapedchannels.)•Subsurfacedrainage,orriprapchannelbottoms,maybenecessaryonsitesthataresubjecttoprolongedwetconditionsduetolongdurationflowsorahighwatertable.•Provideoutletprotectionatculvertendsandatchannelintersections.•Grasschannels,ataminimum,shouldcarrypeakrunofffortemporaryconstructiondrainagefacilitiesfromthe10-year,24-hourstormwithouteroding.Wherefloodhazardexists,increasethecapacityaccordingtothepotentialdamage.•Grassedchannelsideslopesgenerallyareconstructed3H:IVorflattertoaidintheestablishmentofvegetationandformaintenance.•Constructchannelsaminimumof0.2footlargeraroundtheperipherytoallowforsoilbulkingduringseedbedpreparationsandsodbuildup.MaintenanceDuringtheestablishmentperiod,checkgrass-linedchannelsaftereverySta,zdardsrainfall.•Aftergrassisestablished,periodicallycheckthechannel;checkitafterevery’heavy’rainfallevent.Immediatelymakerepairs.•Itisparticularlyimportanttocheckthechanneloutletandallroadcrossingsforbankstabilityandevidenceofpipingorscourholes.ohmicConstructionStornni’aterPollutionPreen/ioniius!20120 Removeallsignificantsedimentaccumulationstomaintainthedesignedcarryingcapacity.Keepthegrassinahealthy,vigorousconditionatalltimes,sinceitistheprimaryerosionprotectionforthechannel.TypicalV-ShapedChannelCross-sectionGrass-LinedChannelCross-SectionCl50.225mm)KeyInFabricWithChannelLinerWiIhRockChterlotBaseFlowTypicalTrapezoidalChannelCross-SectionDesignDepth‘ercutchannel2”150mm)toIIowhulkingduringscedbedpreparationandgrowthofveqetalionFillerFatyiic1L/%•StiFigure4.2.1—TypicalGrass-LinedChannelsohmicCons!rudilonS!or;mi’a!erPollulionPieeu/iouitus!2012FilterFabricTypicalParabolicRocRCenter(150-225mm1KeyinFabricFilterFabricWarnRockCenterForBaseFlowI Overlap6(150mm)minimumflf/ThI./-r(m)tyct’-//TPICALINSTALLATIONWITHEROSIONCONTROLBMNKETSORTRFREINFORCEMENTMATSLSLtaItNOTES:IntermittentCheckSlotLongitudinalAnchorTrenchtoprotecLseedandsoiluntilvegetationbecomesestablished.2Grass-linedchannelswithdesignvelocitiesexceeding6fl/sec(2m/sec)shouldincludeturfreinforcementmats.Figure4.2.2—TemporaryChannelLinersEcavateCtiann&toDeigiiGradeapdCrossSectionIoERCTCHANNEL2(50mm)TOALLOWBLKING0RINGSEEDBEDPREPARATIONLonaitudinalanchorTrenchShingle-lapsplicedendsorbeginnewrollinanintermittentcheckslot4Preparesoilandapplyseedbeforeinstallingblankets,matsorothertemporarychannellinersystem44(14-‘A’IbesigneIocitiesexceeding2ft/sec(O.5m!sec)requiretemporaryblanLets,matsorsimilarlinersohuneConstrue/ionSlornnt’aterPollutionPieen/ionuus!2012 BMPC202:ChannelLiningPurposeToprotectchannelsbyprovidingachannellinerusingeitherblanketsorriprap.ConditionsofWhennaturalsoilsorvegetatedstabilizedsoilsinachannelarenotadequatiUsetopreventchannelerosion.•Whenapermanentditchorpipesystemistobeinstalledandatemporarymeasureisneeded.•Inalmostallcases.syntheticandorganiccoconutblanketsaremoreeffectivethanriprapforprotectingchannelsfromerosion.Blanketscanbeusedwithandwithoutvegetation.Blanketedchannelscanbedesignedtohandleanyexpectedflowandlongevityrequirement.Somesyntheticblanketshaveapredictedlifespanof50yearsormore,eveninsunlight.•Otherreasonswhyblanketsarebetterthanrockincludetheavailabilityofblanketsoverrock.Inmanyareasofthestate,rockisnoteasilyobtainableorisveryexpensivetohaultoasite.Blanketscanbedeliveredanywhere.Rockrequirestheuseofdumptruckstohaulandheavyequipmenttoplace.Blanketsusuallyonlyrequirelaborerswithhandtools,andsometimesabackhoe.•TheFederalHighwayAdministrationrecommendsnotusingflexiblelinerswhenevertheslopeexceeds10percentortheshearstressexceeds8lbs/ft2.DesignandSeeBMPC122forinformationonblankets.Installation.....Sincenprapisusedwhereerosionpotentialishigh,constructionmustbeSpecificationssequencedsothattheriprapisputinplacewiththeminimumpossibledelay.•Disturbanceofareaswhereriprapistobeplacedshouldbeundertakenonlywhenfinalpreparationandplacementoftheriprapcanfollowimmediatelybehindtheinitialdisturbance.\Vhereriprapisusedforoutletprotection,theriprapshouldbeplacedbeforeorinconjunctionwiththeconstructionofthepipeorchannelsothatitisinplacewhenthepipeorchannelbeginstooperate.•Thedesigner,afterdeterminingtheriprapsizethatwillbestableundertheflowconditions,shallconsiderthatsizetobeaminimumsizeandthen,basedonriprapgradationsactuallyavailableinthearea,selectthesizeorsizesthatequalorexceedtheminimumsize.Thepossibilityofdrainagestructuredamagebychildrenshallbeconsideredinselectingariprapsize,especiallyifthereisnearbywateroragullyinwhichtotossthestones.•Stoneforriprapshallconsistoffieldstoneorquarrystoneofapproximatelyrectangularshape.ThestoneshallbehardandangularoluincConstructionStonnii’aterPollutionPrecut/oniius!20)2 andofsuchqualitythatitwillnotdisintegrateonexposuretowaterorweatheringanditshallbesuitableinallrespectsforthepurposeintended.Aliningofengineeringfilterfabric(geotextile)shallbeplacedbetweentheriprapandtheunderlyingsoilsurfacetopreventsoilmovementintoorthroughtheriprap.Thegeotextileshouldbekeyedinatthetopofthebank.Filterfabricshallnotbeusedonslopesgreaterthan1-1/2H:IVasslippagemayoccur.Itshouldbeusedinconjunctionwithalayerofcoarseaggregate(granularfilterblanket)whentheripraptobeplacedis12inchesandlarger.BMPC203:WaterBarsPurposeAsmallditchorridgeofmaterialisconstructeddiagonallyacrossaroadorright-of-waytodivertstormwaterrunofffromtheroadsurface,wheeltracks,orashallowroadditch.SeeFiaure4.2.3.Co,,ditionsofuseClearingright-of-wayandconstructionofaccessforpowerlines,pipelines,andothersimilarinstallationsoftenrequirelongnarrowright-of-waysoverslopingterrain.DisturbanceandcompactionpromotesgullyformationintheseclearedstripsbyincreasingthevolumeandvelocityofrunoffGullyformationmaybeespeciallysevereintiretracksandruts.Topreventgullying,runoffcanoftenbedivertedacrossthewidthoftheright-of-waytoundisturbedareasbyusingsmallpredesigneddiversions.•Givespecialconsiderationtoeachindividualoutletarea,aswellastothecumulativeeffectofaddeddiversions.Usegraveltostabilizethediversionwheresignificantvehiculartrafficisanticipated.DesignaudITeight:8-inchminimummeasuredfromthechannelbottomtotheridgetop.Installation•Sideslopeofchannel:2H:IVmaximum:3H:IVorflatterwhenSpecsflcatwizs..-vehicleswillcross.•Basewidthofridge:6-inchminimum.•Locatethemtousenaturaldrainagesystemsandtodischargeintowellvegetatedstableareas.•GuidelineforSpacing:SoSain(f)<51255-1010010-207520-3550>35UscrocklinedditchohiuwConstructionStornnt’atcrPollutionPreentionUus!2012 •Gradeofwaterbarandangle:Selectanglethatresultsinditchslopelessthan2percent.•Installassoonastheclearingandgradingiscomplete.Reconstructwhenconstructioniscompleteonasectionwhenutilitiesarebeinginstalled.•Compacttheridgewheninstalled.•Stabilize,seedandmulchtheportionsthatarenotsubjecttotraffic.Graveltheareascrossedbyvehicles.MahitenancePeriodicallyinspectright-of-waydiversionsforwearandaftereveryheavyStandardsrainfallforerosiondamage.•Immediatelyremovesedimentfromtheflowareaandrepairthedike.•Checkoutletareasandmaketimelyrepairsasneeded.•Whenpermanentroaddrainageisestablishedandtheareaabovethetemporaryright-of-waydiversionispermanentlystabilized,removethedikesandfillthechanneltoblendwiththenaturalground,andappropriatelystabilizethedisturbedarea.DEEPWATERBARA24to30inchesB6toioteaSHALLOWWATERBARA8to12inchesB6to12fedFigure4.2.3—WaterBarolwneConstrue/iouS/ormiraftrPollutionPreentioniius!2012 BMPC204:PipeSlopeDrainsPurposeTouseapipetoconveystormwateranytimewaterneedstobedivertedawayfromoroverbaresoiltopreventgullies,channelerosion,andsaturationofslide-pronesoils.ConditionsofUsePipeslopedrainsshouldbeusedwhenatemporaryorpermanentstormwaterconveyanceisneededtomovethewaterdownasteepslopetoavoiderosion(Figure4.2.4).Onhighwayprojects,pipeslopedrainsshouldbeusedatbridgeendstocollectrunoffandpipeittothebaseofthefillslopesalongbridgeapproaches.Thesecanbedesignedintoaprojectandincludedasbiditems.Anotheruseonroadprojectsistocollectrunofffrompavementandpipeitawayfromsideslopes.Theseareusefulbecausethereisgenerallyatimelagbetweenhavingthefirstliftofasphaltinstalledandthecurbs,gutters,andpermanentdrainageinstalled.Usedinconjunctionwithsandbags,orothertemporarydiversiondevices,thesewillpreventmassiveamountsofsedimentfromleavingaproject.Watercanbecollected,channeledwithsandbags,TriangularSiltDikes,berms,orothermaterial,andpipedtotemporarysedimentponds.Pipeslopedrainscanbe:•Connectedtonewcatchbasinsandusedtemporarilyuntilallpermanentpipingisinstalled;•Usedtodrainwatercollectedfromaquifersexposedoncutslopesandtakeittothebaseoftheslope;•Usedtocollectcleanrunofffromplasticsheetinganddirectitawayfromexposedsoil;•Tnstalledinconjunctionwithsiltfencetodraincollectedwatertoacontrolledarea;•Usedtodivertsmallseasonalstreamsawayfromconstruction.Theyhavebeenusedsuccessfullyonculvertreplacementandextensionjobs.Largeflexpipecanbeusedonlargerstreamsduringculvertremoval,repair,orreplacement;and,•Connectedtoexistingdownspoutsandroofdrainsandusedtodivertwaterawayfromworkareasduringbuildingrenovation,demolition,andconstructionprojects.Therearenowseveralcommerciallyavailablecollectorsthatareattachedtothepipeinletandhelppreventerosionattheinlet.ohimeConsirudilonS!onnii’aterPot/uiionPreen/ioniius!2012 DesignandSizethepipetoconveytheflow.ThecapacityfortemporarydrainsshallbeInstallatia,;sufficienttohandlethepeakflowfroma10-year,24-hourstormevent,Spec(ficationsassumingaTypeIArainfalldistribution.Alternatively,use1.6timesthe10-year,1-hourflowindicatedbyanapprovedcontinuousrunoffmodel.Consultlocaldrainagerequirementsforsizingpermanentpipeslopedrains.•Usecareinclearingvegetatedslopesforinstallation.•Re-establishcoverimmediatelyonareasdisturbedbyinstallation.•Usetemporarydrainsonnewcutorfillslopes.•Usediversiondikesorswalestocollectwateratthetopoftheslope.•Ensurethattheentranceareaisstableandlargeenoughtodirectflowintothepipe.•Pipingofwaterthroughthebermattheentranceareaisacommonfailuremode.•Theentranceshallconsistofastandardflaredendsectionforculverts12inchesandlargerwithaminimum6-inchmetaltoeplatetopreventrunofffromundercuttingthepipeinlet.Theslopeoftheentranceshallbeatleast3percent.Sandbagsmayalsobeusedatpipeentrancesasatemporarymeasure.•Thesoilaroundandunderthepipeandentrancesectionshallbethoroughlycompactedtopreventundercutting.•Theflaredinletsectionshallbesecurelyconnectedtotheslopedrainandhavewatertightconnectingbands.•Slopedrainsectionsshallbesecurelyfastenedtogether,ftisedorhavegasketedwatertightfittings,andshallbesecurelyanchoredintothesoil.•Thrustblocksshouldbeinstalledanytime90degreebendsareutilized.Dependingonsizeofpipeandflow,thesecanbeconstructedwithsandbags,strawbalesstakedinplace,“t”postsandwire,orecologyblocks.•Pipeneedstobesecuredalongitsfulllengthtopreventmovement.Thiscanbedonewithsteel“t”postsandwire.Apostisinstalledoneachsideofthepipeandthepipeiswiredtothem.Thisshouldbedoneevery10-20feetofpipelengthorso,dependingonthesizeofthepipeandquantityofwatertodivert.•Interceptordikesshallbeusedtodirectrunoffintoaslopedrain.Theheightofthedikeshallbeatleast1foothigheratallpointsthanthetopoftheinletpipe.•Theareabelowtheoutletmustbestabilizedwithariprapapron(seeBMPC209OutletProtection,fortheappropriateoutletmaterial).oIzinwConstructionStornni’aterPollutionPieen/iouuus!2012 Ifthepipeslopedrainisconveyingsediment-ladenwater,directallflowsintothesedimenttrappingfacility.•Materialsspecificationsforanypermanentpipedsystemshallbesetbythelocalgovernment.MaintenanceStandardsCheckinletandoutletpointsregularly,especiallyafterstorms.Theinletshouldbefreeofundercutting,andnowatershouldbegoingaroundthepointofentry.Ifthereareproblems,theheadwal!shouldbereinforcedwithcompactedearthorsandbags.•Theoutletpointshouldbefreeoferosionandinstalledwithappropriateoutletprotection.•Forpermanentinstallations,inspectpipeperiodicallyforvandalismandphysicaldistresssuchasslidesandwind-throw.•Normallythepipeslopeissosteepthatcloggingisnotaproblemwithsmoothwallpipe,however,debrismaybecomelodgedinthepipe.Figure4.2.4—PipeSlopeDrainDikematerialcompacted90%modifiedproctorCPEPorequivalentpipeDikeDischargetoastabilizedwatercourse,sedimentretentionfacility,orstabilizedoutletStandardflaredendsectionInletandallsectionsmustbesecurelyfastenedtogetherwithgasketedwatertightfittingsolwneConstructionS/onmi’atcrPollutionPreentioniius!2012 BMPC205:SubsurfaceDrainsPurposeTointercept,collect,andconveygroundwatertoasatisfactoryoutlet,usingaperforatedpipeorconduitbelowthegroundsurface.Subsurfacedrainsarealsoknownas“frenchdrains.”Theperforatedpipeprovidesadewateringmechanismtodrainexcessivelywetsoils,provideastablebaseforconstruction,improvestabilityofstructureswithshallowfoundations,ortoreducehydrostaticpressuretoimproveslopestability.(‘onditionsofUseUsewhenexcessivewatermustberemovedfromthesoil.Thesoilpermeability,depthtowatertableandimperviouslayersareallfactorswhichmaygoverntheuseofsubsurfacedrains.Designalit!RIfdrainareusedeithertolowerthewatertableinlarge.relativelyInstallationflatareas,improvethegrowthofvegetation,ortoremovesurfacewater.SpecjflcationsReliefdrainsareinstalledalongaslopeanddraininthedirectionoftheslope.Theycanbeinstalledinagridpattern,aherringbonepattern,orarandompattern.Inrordrainareusedtoremoveexcessgroundwaterfromaslope,stabilizesteepslopes,andlowerthewatertableimmediatelybelowaslopetopreventthesoilfrombecomingsaturated.Interceptordrainsareinstalledperpendiculartoaslopeanddraintothesideoftheslope.Theyusuallyconsistofasinglepipeorseriesofsinglepipesinsteadofapatternedlayout.•Dandainofinrordrain--Thedepthofaninterceptordrainisdeterminedprimarilybythedepthtowhichthewatertableistobeloweredorthedepthtoaconfininglayer.Forpracticalreasons,themaximumdepthisusuallylimitedto6feet,withaminimumcoverof2feettoprotecttheconduiL•Thesoilshouldhavedepthandsufficientpcrmcabiliwtopermitinstallationofaneffectivedrainagesystematadepthof2to6feet.•Anadequateoutletforthedrainagesystemmustbeavailableeitherbygravityorbypumping.•Thequantityandqualityofdischargeneedstobeaccountedforinthereccivingstream(additionaldetentionmaybcrequired).•Thisstandarddoesnotapplytosubsurfacedrainsforbuildingfoundationsordeepexcavations.•Thecapacityofaninterceptordrainisdeterminedbycalculatingthemaximumrateofgroundwaterflowtobeintercepted.Therefore,itisohi;neCons/rue/ionS/onn;i’a/erPollutionPieen/ionuus!2012 goodpracticetomakecompletesubsurfaceinvestigations,includinghydraulicconductivityofthesoil,beforedesigningasubsurfacedrainagesystem.•Siofdrain--Sizesubsurfacedrainstocarry’therequiredcapacitywithoutpressureflow.Minimumdiameterforasubsurfacedrainis4inches.•Theminimumvelocityrequiredtopreventsiltingis1.4ft./sec.Thelineshallbegradedtoachievethisvelocityataminimum.Themaximumallowablevelocityusingasand-gravelfilterorenvelopeis9fUsec.•Filtermaterialandfabricshallbeusedaroundalldrainsforproperbeddingandfiltrationoffinematerials.Envelopesandfiltersshouldsurroundthedraintoaminimumof3-inchthickness.•Theoutletofthesubsurfacedrainshallempty’intoasedimentpondthroughacatchbasin.Iffreeofsediment,itcanthenemptyintoareceivingchannel,swale,orstablevegetatedareaadequatelyprotectedfromerosionandundermining.•Thetrenchshallbeconstructedonacontinuousgradewithnoreversegradesorlowspots.•Softoryieldingsoilsunderthedrainshallbestabilizedwithgravelorothersuitablematerial.•Backlillingshallbedoneimmediatelyafterplacementofthepipe.Nosectionsofpipeshallremainuncoveredovernightorduringarainstorm.Backfillmaterialshallbeplacedinthetrenchinsuchamannerthatthedrainpipeisnotdisplacedordamaged.•Donotinstallpermanentdrainsneartreestoavoidthetreerootsthattendtoclogtheline.Usesolidpipewithwatertightconnectionswhereitisnecessary’topassasubsurfacedrainagesystemthroughastandoftrees.•0--Ensurethattheoutletofadrainemptiesintoachannelorotherwatercourseabovethenormalwaterlevel.•Secureananimalguardtotheoutletendofthepipetokeepoutrodents.•Useoutletpipeofcorrugatedmetal,castiron,orheavy-dutyplasticwithoutperforationsandatleast10feetlong.Donotuseanenvelopeorfiltermaterialaroundtheoutletpipe,andburyatleasttwo-thirdsofthepipelength.•Whenoutletvelocitiesexceedthoseallowableforthereceivingstream,outletprotectionmustbeprovided.obtineConsinictionStonmi’aterPollze/io;iPieentionitits!20120 MaintenanceSubsurfacedrainsshallbecheckedperiodicallytoensurethattheyareStandardsfree-flowingandnotcloggedwithsedimentorroots.•Theoutletshallbekeptcleanandfreeofdebris.•SurfaceinletsshalLbekeptopenandfreeofsedimentandotherdebris.•Treeslocatedtooclosetoasubsurfacedrainoftenclogthesystemwiththeirroots.Ifadrainbecomesclogged,relocatethedrainorremovethetreesasalastresort.Drainplacementshouldbeplannedtominimizethisproblem.•Wheredrainsarecrossedbyheavyvehicles,thelineshallbecheckedtoensurethatitisnotcrushed.BMPC206:LevelSpreaderPurposeToprovideatemporaryoutletfordikesanddiversionsconsistingofanexcavateddepressionconstructedatzerogradeacrossaslope.Toconvertconcentratedrunofftosheetflowandreleaseitontoareasstabilizedbyexistingvegetationoranengineeredfilterstrip.ConditionsofUseUsedwhenaconcentratedflowofwaterneedstobedispersedoveralargeareawithexistingstablevegetation.•Itemstoconsiderare:I.Whatistheriskoferosionordamageiftheflowmaybecomeconcentrated?2.Isaneasementrequiredifdischargedtoadjoiningproperty?3.Mostoftheflowshouldbeasgroundwaterandnotassurfaceflow.4.Isthereanunstableareadownstreamthatcannotacceptadditionalgroundwater?•Useonlywheretheslopesaregentle,thewatervolumeisrelativelylow,andthesoilwilladsorbmostofthelowflowevents.DesignandUseaboveundisturbedareasthatarestabilizedbyexistingvegetation.InstallationTfthelevelspreaderhasanylowpoints,flowwillconcentrate,createSpecificationschannelsandmaycauseerosion.•Dischargeareabelowtheoutletmustbeuniformwithaslopeflatterthan511:IV.•Outlettobeconstructedlevelinastable,undisturbedsoilprofile(notonfill).•Therunoffshallnotre-concentrateafterreleaseunlessinterceptedbyanotherdownstreammeasure.ohuneConstructionStormii’a!erPollutionPreen/ioniius!20)2I •Thegradeofthechannelforthelast20feetofthedikeorinterceptorenteringthelevelspreadershallbelessthanorequalto1percent.Thegradeofthelevelspreadershallbe0percenttoensureuniformspreadingofstormrunofE•A6-inchhighgravelbermplacedacrossthelevellipshallconsistofwashedcrushedrock,2-to4-inchor3/4-inchtoIVa-inchsize.•Thespreaderlengthshallbedeterminedbyestimatingthepeakflowexpectedfromthe10-year,24-hourdesignstorm.Thelengthofthespreadershallbeaminimumof15feetfor0.1cfsandshallincreaseby10feetforeach0.1cfsthereaftertoamaximumof0.5cfsperspreader.Usemultiplespreadersforhigherflows.•Thewidthofthespreadershouldbeatleast6feet.AlaintenanceStandards•Thedepthofthespreaderasmeasuredfromthelipshouldbeatleast6inchesanditshouldbeuniformacrosstheentirelength.•Levelspreadersshallbesetbackfromthepropertylineunlessthereisaneasementforflow.•Levelspreaders,wheninstalledeverysoofteningrassyswales,keeptheflowsfromconcentrating.Materialsthatcanbeusedincludesandbags,lumber,logs,concrete,andpipe.Tofunctionproperly,thematerialneedstobeinstalledlevelandoncontour.Figures4.2.5Fiaure425and4.2.6provideacross-sectionandadetailofalevelspreader.Acappedperforatedpipecouldalsobeusedasaspreader.Thespreadershouldbeinspectedaftereveryrunoffeventtoensurethatitisffinctioningcorrectly.•Thecontractorshouldavoidtheplacementofanymaterialonthestructureandshouldpreventconstructiontrafficfromcrossingoverthestructure.•Ifthespreaderisdamagedbyconstructiontraffic,itshallbeimmediatelyrepaired.Figure4.2.5—CrossSectionofLevelSpreaderolunwConstructionS!onnu’aterPollutionPreentioniius!2012Pressure-Treated2’xlO’Dens&yvegetatedforaMm.of100’andslopelessthan5:13Mm.—I BMPC207:CheckDamsPurposeConstructionofsmalldamsacrossaswaleorditchreducesthevelocityofconcentratedflowanddissipatesenergyatthecheckdarn.ConditionsofUse\\Theretemporarychannelsorpermanentchannelsarenotyetvegetated,channelliningisinfeasible,and/orvelocitychecksarerequired.•CheckdamsmaynotbeplacedinstreamsunlessapprovedbytheStateDepartmentofFishandWildlife.Checkdamsmaynotbeplacedinwetlandswithoutapprovalfromapermittingagency.•DonotplacecheckdamsbelowtheexpectedbackwaterfromanysalmonidbearingwaterbetweenOctober1andMay31toensurethatthereisnolossofhighflowrefugehabitatforoverwinteringjuvenilesalmonidsandemergentsalmonidfry.•Constructrockcheekdamsfromappropriatelysizedrock.Therockusedmustbelargeenoughtostayinplacegiventheexpecteddesignflowthroughthechannel.Therockmustbeplacedbyhandorbymechanicalmeans(nodumpingofrocktoformdarn)toachievecompletecoverageoftheditchorswaleandtoensurethatthecenterofthedamislowerthantheedges.•Checkdamsmayalsobeconstructedofeitherrockorpea-gravelfilledbags.Numerousnewproductsarealsoavailableforthispurpose.Theytendtobere-usable,quickandeasytoinstall,effective,andcostefficient.•Placecheckdamsperpendiculartotheflowofwater.•Thedamshouldformatrianglewhenviewedfromtheside.Thispreventsundercuttingaswaterflowsoverthefaceofthedamratherthanfallingdirectlyontotheditchbottom.Spreadermustbelevel6”mmTreated2x1O”maybeabuttedendtoendformax.spreaderlengthof50- - -H41”mm.6”mm.tV11=11=111=111=1118mm.rebarsupporls8max.spacing—Figure4.2.6—DetailofLevelSpreaderoh,,,,eConstructionStornni’aterPollutionPieeli/jo,?uus!2012 •Beforeinstallingcheckdamsimpoundandbypassupstreamwaterflowawayfromtheworkarea.Optionsforbypassingincludepumps,siphons,ortemporarychannels.•Checkdamsinassociationwithsumpsworkmoreeffectivelyatslowingflowandretainingsedimentthanjustacheckdamalone.Adeepsumpshouldbeprovidedimmediatelyupstreamofthecheckdam.•Insomecases,ifcarefullylocatedanddesigned,checkdamscanremainaspermanentinstallationswithveryminorregrading.Theymaybeleftaseitherspillways,inwhichcaseaccumulatedsedimentwouldbegradedandseeded,orascheekdamstopreventifirthersedimentfromleavingthesite.•Themaximumspacingbetweenthedamsshallbesuchthatthetoeoftheupstreamdarnisatthesameelevationasthetopofthedownstreamdam.•Keepthemaximumheightat2feetatthecenterofthedam.•Keepthecenterofthecheckdamatleast12incheslowerthantheouteredgesatnaturalgroundelevation.•Keepthesideslopesofthecheckdamat2H:IVorflatter.•Keythestoneintotheditchbanksandextenditbeyondtheabutmentsaminimumof18inchestoavoidwashoutsfromoverflowaroundthedarn.•Usefilterfabricfoundationunderarockorsandbagcheckdam.Ifablanketditchlinerisused,filterfabricisnotnecessary.Apieceoforganicorsyntheticblanketcuttofitwillalsoworkforthispurpose.•Inthecaseofgrass-linedditchesandswales,allcheckdamsandaccumulatedsedimentshallberemovedwhenthegrasshasmaturedsufficientlytoprotecttheditchorswale-unlesstheslopeoftheswaleisgreaterthan4percent.Theareabeneaththecheckdamsshallbeseededandmulchedimmediatelyafterdamremoval.•Ensurethatchannelappurtenances,suchasculvertentrancesbelowcheckdams,arenotsubjecttodamageorblockagefromdisplacedstones.Ficure4.2.7depictsatypicalrockcheckdarn.MaintenanceCheckdamsshallbemonitoredforperformanceandsedimentStandardsaccumulationduringandaftcreachrunoffproducingrainfall.Sedimentshallberemovedwhenitreachesonehalfthesumpdepth.•Anticipatesubmergenceanddepositionabovethecheckdamanderosionfromhighflowsaroundtheedgesofthedam.•Ifsignificanterosionoccursbetweendams,installaprotectiveripraplinerinthatportionofthechannel.ohimeConstructionS!onmi’aterPollutionPieen/ionuus!2012 ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC207.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecv.wa.uov/prorams/vg/stormvater/ne;•’tech/eguiva1ent.htm1oh,,neConstructionStonnii’aterPollutionPieentionuus!2012 ohmieConstructionStornzii’a/crPothitionPieentionuus!2012Figure4.2.7—RockCheckDam BMPC208:TriangularSiltDike(TSD)(Geotextile-EncasedCheckDam)PurposeTriangularsiltdikesmaybeusedascheckdams,forperimeterprotection,fortemporarysoilstockpileprotection,fordropinletprotection,orasatemporaryinterceptordike.Condilio,,sofuse•Maybeusedonsoilorpavementwithadhesiveorstaples.TSDshavebeenusedtobuildtemporary:1.sedimentponds;2.diversionditches;3.concretewashoutfacilities;4.curbing;5.waterbars;6.levelspreaders;and,7.berms.DesignandMadeofurethanefoamsewnintoawovengeosyntheticfabric.Installation.....Itistrianoular,10inchesto14incheshighinthecenter,witha20-inchtoSpecifications28-inchbase.A2—footapronextendsbeyondbothsidesofthetrianglealongitsstandardsectionof7feet.Asleeveatoneendallowsattachmentofadditionalsectionsasneeded.•Installwithendscurveduptopreventwaterfromflowingaroundtheends.•Thefabricflapsandcheckdamunitsareattachedtothegroundwithwirestaples.WirestaplesshouldbeNo.11gaugewireandshouldbe200mmto300mminlength.•Whenmultipleunitsareinstalled,thesleeveoffabricattheendoftheunitshalloverlaptheabuttingunitandbestapled.•Checkdamsshouldbelocatedandinstalledassoonasconstructionwillallow.•Checkdamsshouldbeplacedperpendiculartotheflowofwater.•Whenusedascheekdams,theleadingedgemustbesecuredwithrocks,sandbags,orasmallkeyslotandstaples.•Inthecaseofgrass-linedditchesandswales,checkdamsandaccumulatedsedimentshallberemovedwhenthegrasshasmaturedsufficientlytoprotecttheditchorswaleunlesstheslopeoftheswaleisgreaterthan4percent.Theareabeneaththecheckdarnsshallbesccdcdandmulchedimmediatelyafterdamremoval.MaintenanceaTriangularsiltdamsshallbeinspectedforperformanceandsedimentohuneCons/rue/jo;;S/ornni’a/erPollutionPieeu/ionuus!2012 AppendixBBMPDetailsDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageB-i BMPClOl:PreservingNaturalVegetationPurposeThepurposeofpreservingnaturalvegetationistoreduceerosionwhereverpracticable.Limitingsitedisturbanceisthesinglemosteffectivemethodforreducingerosion.Forexample,coniferscanholduptoabout50percentofallrainthatfallsduringastorm.Upto20-30percentofthisrainmayneverreachthegroundbutistakenupbythetreeorevaporates.Anotherbenefitisthattherainheldinthetreecanbereleasedslowlytothegroundafterthestorm.ConditionsofUseNaturalvegetationshouldbepreservedonsteepslopes,nearperennialandintermittentwatercoursesorswales.andonbuildingsitesinwoodedareas.•Asrequiredbylocalgovernments.•Phaseconstructiontopreservenaturalvegetationontheprojectsiteforaslongaspossibleduringtheconstructionperiod.DesignandNaturalvegetationcanbepreservedinnaturalclumpsorasindividualInstallationtrees.shrubsandvines.SpecfficationsThepreservationofindividualplantsismoredifficultbecauseheavyequipmentisgenerallyusedtoremoveunwantedvegetation.Thepointstorememberwhenattemptingtosaveindividualplantsare:•Istheplantworthsaving?Considerthelocation,species,size,age,vigor,andtheworkinvolved.Localgovernmentsmayalsohaveordinancestosavenaturalvegetationandtrees.•Fenceorclearlymarkareasaroundtreesthataretobesaved.Itispreferabletokeepgrounddisturbanceawayfromthetreesatleastasfaroutasthedripline.Plantsneedprotectionfromthreekindsofinjuries:•Constructionuimen!—Thisinjury’canbeaboveorbelowthegroundlevel.Damageresultsfromscarring,cuttingofroots,andcompactionofthesoil.Placingafencedbufferzonearoundplantstobesavedpriortoconstructioncanpreventconstructionequipmentinjuries.•GraeCanes-Changingthenaturalgroundlevelwillaltergrades,whichaffectstheplant’sabilitytoobtainthenecessaryair,water,andminerals.Minorfillsusuallydonotcauseproblemsalthoughsensitivitybetweenspeciesdoesvaryandshouldbechecked.Treescantypicallytoleratefillof6inchesorless.Forshrubsandotherplants,thefillshouldbeless.Whentherearemajorchangesingrade,itmaybecomenecessarytosupplyairtotherootsofplants.Thiscanbedonebyplacingalayerofgravelandatilesystemovertherootsbeforethefillismade.Atilesystemprotectsatreefromaraisedgrade.ThetilesystemshouldbeohmicConstructionStonnii’aterPollutionPreen/ionitus!2012 laidoutontheoriginalgradeleadingfromadryvellaroundthetreetrunk.Thesystemshouldthenbecoveredwithsmallstonestoallowairtocirculateovertherootarea.Loweringthenaturalgroundlevelcanseriouslydamagetreesandshrubs.Thehighestpercentageoftheplantrootsareintheupper12inchesofthesoilandcutsofonly2-3inchescancauseseriousinjury.Toprotecttherootsitmaybenecessarytoterracetheimmediateareaaroundtheplantstobesaved.Ifrootsareexposed,constructionofretainingwallsmaybeneededtokeepthesoilinplace.Plantscanalsobepreservedbyleavingthemonanundisturbed,gentlyslopingmound.Toincreasethechancesforsurvival,itisbesttolimitgradechangesandothersoildisturbancestoareasoutsidethedriplineoftheplant.cc;citiolls-Protecttreesandotherplantswhenexcavatingfordrainfields,power,water,andsewerlines.Wherepossible,thetrenchesshouldberoutedaroundtreesandlargeshrubs.Whenthisisnotpossible,itisbesttotunnelunderthem.Thiscanbedonewithhandtoolsorwithpoweraugers.Ifitisnotpossibletoroutethetrencharoundplantstobesaved,thenthefollowingshouldbeobserved:Cutasfewrootsaspossible.Whenyouhavetocut,cutclean.Paintcutrootendswithawooddressinglikeasphaltbasepaintifrootswillbeexposedformorethan24-hours.Backfillthetrenchassoonaspossible.Tunnelbeneathrootsystemsasclosetothecenterofthemaintrunktopreservemostoftheimportantfeederroots.Someproblemsthatcanbeencounteredwithafewspecifictreesare:•Maple,Dogwood,Redalder,Westernhemlock,Westernredcedar,andDouglasfirdonotreadilyadjusttochangesinenvironmentandspecialcareshouldbetakentoprotectthesetrees.•ThewindthrowhazardofPacificsilverfirandmadronaishigh,whilethatofWesternhemlockismoderate.Thedangerofwindthrowincreaseswheredensestandshavebeenthinned.Otherspecies(unlesstheyareonshallow,wetsoilslessthan20inchesdeep)havealowwindthrowhazard.•Cottonwoods,maples,andwillowshavewater-seekingroots.Thesecancausetroubleinsewerlinesandinfiltrationfields.Ontheotherhand,theythriveinhighmoistureconditionsthatothertreeswouldnot.•ThinningoperationsinpureormixedstandsofGrandfir,Pacificsilverfir.Noblefir.Sitkaspruce,Westernredcedar,Westernhemlock,Pacificdogwood,andRedaldercancauseseriousdiseaseproblems.Diseasecanbecomeestablishedthroughdamagedlimbs,trunks,roots,olzmwConstructionS/or,niratc;PollutionPrecut/oniius!2012 andfreshlycutstumps.Diseasedandweakenedtreesarealsosusceptibletoinsectattack.MaintenanceInspectflaggedand/orfencedareasregularlytomakesureflaggingorStandardsfencinghasnotbeenremovedordamaged.Iftheflaggingorfencinghasbeendamagedorvisibilityreduced,itshallberepairedorreplacedimmediatelyandvisibilityrestored.•Iftreerootshavebeenexposedorinjured.“prune”cleanlywithanappropriatepruningsaworlopersdirectlyabovethedamagedrootsandrecoverwithnativesoils.Treatmentofsapflowingtrees(fir.hemlock,pine,softmaples)isnotadvisedassapformsanaturalhealingbarrier.BMPC102:BufferZonesPurposeCreationclanundisturbedareaorstripofnaturalvegetationoranestablishedsuitableplantingthatwillprovidealivingfiltertoreducesoilerosionandrunoffvelocities.conditionsofUseNaturalbufferzonesareusedalongstreams.wetlandsandotherbodiesofwaterthatneedprotectionfromerosionandsedimentation.Vegetativebufferzonescanbeusedtoprotectnaturalswalesandcanbeincorporatedintothenaturallandscapingofanarea.Critical-areasbufferzonesshouldnotbeusedassedimenttreatmentareas.Theseareasshallremaincompletelyundisturbed.Thelocalpermittingauthoritymayexpandthebufferwidthstemporarilytoallowtheuseoftheexpandedareaforremovalofsediment.Designand•Preservingnaturalvegetationorplantingsinclumps,blocks,orstripsInstallationisgenerallytheeasiestandmostsuccessfulmethod.Specjfications•Leaveallunstablesteepslopesinnaturalvegetation.•Markclearinglimitsandkeepallequipmentandconstructiondebrisoutofthenaturalareasandbufferzones.Steelconstructionfencingisthemosteffectivemethodinprotectingsensitiveareasandbuffers.Alternatively,wire-backedsiltfenceonsteelpostsismarginallyeffective.Flaggingaloneistypicallynoteffective.•Keepallexcavationsoutsidethedriplineoftreesandshrubs.•Donotpushdebrisorextrasoilintothebufferzoneareabecauseitwillcausedamagefromburyingandsmothering.•Vcgetativcbufferzoncsforstreams,lakesorotherwaterwaysshallbcestablishedbythelocalpermittingauthorityorotherstateorfederalpermitsorapprovals.MaintenanceInspecttheareafrequentlytomakesureflaggingremainsinplaceandtheStandardsarearemainsundisturbed.Replacealldamagedflaggingimmediately.ohmicConstructionS!ornni’citerPollutionPiecottonUus!20)2 BMPC103:HighVisibilityFencePurposeFencingisintendedto:1.Restrictclearingtoapprovedlimits.2.Preventdisturbanceofsensitiveareas,theirbuffers,andotherareasrequiredtobeleftundisturbed.3.Limitconstructiontraffictodesignatedconstructionentrances,exits,orinternalroads.4.Protectareaswheremarkingwithsurveytapemaynotprovideadequateprotection.(‘auditionsofUseToestablishclearinglimitsplastic.fabric,ormetalfencemaybeused:•Attheboundaryofsensitiveareas,theirbuffers,andotherareasrequiredtobeleftuncleared.•Asnecessarytocontrolvehicleaccesstoandonthesite.DesignandHighvisibilityplasticfenceshallbecomposedofahigh-densityInstallationpolyethylenematerialandshallbeatleastfourfeetinheight.PostsforSpecjficationsthefencingshallbesteelorwoodandplacedevery6feetoncenter(maximum)orasneededtoensurerigidity.Thefencingshallbefastenedtotheposteverysixincheswithapolyethylenetie.Onlongcontinuouslengthsoffencing,atensionwireorropeshallbeusedasatopstringertopreventsaggingbetweenposts.Thefencecolorshallbehighvisibilityorange.Thefencetensilestrengthshallbe360lbs./ft.usingtheASTMD4595testingmethod.IfappropriateinstallfabricsiltfenceinaccordancewithBMPC233toactashighvisibilityfence.Siltfenceshallbeatleast3feethighandmustbehighlyvisibletomeettherequirementsofthisBMP.Metalfencesshallbedesignedandinstalledaccordingtothemanufacturer’sspecifications.Metalfencesshallbeatleast3feethighandmustbehighlyvisible.Fencesshallnotbewiredorstapledtotrees.MaintenanceIfthefencehasbccndamagedorvisibilityreduccd.itshallbcrepairedorStandardsreplacedimmediatelyandvisibilityrestored.ohmicConstructionStornni’a!erPollutionPieen/ioniius!2012 BMPC105:StabilizedConstructionEntrance!ExitPurposeStabilizedConstructionentrancesareestablishedtoreducetheamountofsedimenttransportedontopavedroadsbyvehiclesorequipment.Thisisdonebyconstructingastabilizedpadofquarryspallsatentrancesandexitsforconstructionsites.conditionsofUseConstructionentrancesshallbestabilizedwherevertrafficwillbeenteringorleavingaconstructionsiteifpavedroadsorotherpavedareasarewithin1.000feelofthesite.Forresidentialconstructionprovidestabilizedconstructionentrancesforeachresidence,ratherthanonlyatthemainsubdivisionentrance.Stabilizedsurfacesshallbeofsufficientlength/widthtoprovidevehicleaccess/parking,basedonlotsize/configuration.Onlargecommercial,highway,androadprojects,thedesignershouldincludeenoughextramaterialsinthecontracttoallowforadditionalstabilizedentrancesnotshownintheinitialConstructionSWPPP.Itisdifficulttodetermineexactlywhereaccesstotheseprojectswilltakeplace;additionalmaterialswillenablethecontractortoinstallthemwhereneeded.DesignandSeeFigure4.1.1fordetails.Note:the100’minimumlengthoftheInstallationentranceshallbereducedtothemaximumpracticablesizewhenthesizeSpecjflcationsorconfigurationofthesitedoesnotallowtheMIlength(100’).Constructstabilizedconstructionentranceswitha12-inchthickpadof4-inchto8-inchquarryspalls.a4-inchcourseofasphalttreatedbase(ATB),oruseexistingpavement.Donotusecrushedconcrete,cement,orcalciumchlorideforconstructionentrancestabilizationbecausetheseproductsraisepHlevelsinstormwaterandconcretedischargetosurfacewatersoftheStateisprohibited.Aseparationgeotextileshallbeplacedunderthespallstopreventfinesedimentfrompumpingupintotherockpad.Thegeotextileshallmeetthefollowingstandards:GrabTensileStrength(ASTMD4751)200psimm.GrabTensileElongation(ASTM30%max.D4632)MullenBurstStrength(ASTM400psimm.D3786-80a)AOS(ASTMD4751)20-45(U.S.standardsievesize)•Considerearlyinstallationofthefirstliftofasphaltinareasthatwillpaved;thiscanbeusedasastabilizedentrance.Alsoconsidertheinstallationofexcessconcreteasastabilizedentrance.Duringlargeconcretepours,excessconcreteisoftenavailableforthispurpose.ohiineConstructionStornni’aterPollutionPrc’entioniiitct2012 •Fencing(seeBMPC103)shallbeinstalledasnecessarytorestricttraffictotheconstructionentrance.•Wheneverpossible,theentranceshallbeconstructedonafirm,compactedsubgrade.Thiscansubstantiallyincreasetheeffectivenessofthepadandreducetheneedformaintenance.•Constructionentrancesshouldavoidcrossingexistingsidewalksandbackofwalkdrainsifatallpossible.Ifaconstructionentrarwemustcrossasidewalkorbackofwalkdrain,thefulllengthofthesidewalkandbackofwalkdrainmustbecoveredandprotectedfromsedimentleavingthesite.MaintenanceQuarryspallsshallbeaddedifthepadisnolongerinaccordancewithStandardsthespecifications.•Iftheentranccisnotpreventingsedimentfrombeingtrackedontopavement,thenalternativemeasurestokeepthestreetsfreeofsedimentshallbeused.Thismayincludereplacement/cleaningoftheexistingquarryspalls,streetsweeping,anincreaseinthedimensionsoftheentrance,ortheinstallationofawheelwash.•Anysedimentthatistrackedontopavementshallberemovedbyshovelingorstreetsweeping.Thesedimentcollectedbysweepingshallberemovedorstabilizedonsite.Thepavementshallnotbecleanedbywashingdownthestreet,exceptwhenhighefficiencysweepingisineffectiveandthereisathreattopublicsafety.Ifitisnecessarytowashthestreets,theconstructionofasmallsumptocontainthewashwatershallbeconsidered.Thesedimentwouldthenbewashedintothesumpwhereitcanbecontrolled.•Performstreetsweepingbyhandorwithahighefficiencysweeper.Donotuseanon-highefficiencymechanicalsweeperbecausethiscreatesdustandthrowssoilsintostormsystemsorconveyanceditches.•Anyquarryspallsthatareloosenedfromthepad,whichendupontheroadwayshallberemovedimmediately.•Ifvehiclesareenteringorexitingthesiteatpointsotherthantheconstructionentrance(s),fencing(seeBMPC103)shallbeinstalledtocontroltraffic.•Uponprojectcompletionandsitestabilization,allconstructionaccessesintendedaspermanentaccessformaintenanceshallbepermanentlystabilized.obtincCo,zs!ruc/ionS/orinwa!erPot/it/ionPreentioniius!2012 Figure4.1.1—StabilizedConstructionEntranceApprovedasEquivalei#EcologyhasapprovedproductsasabletomeettherequirementsofBMPC]05.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecv.wa.cov/programs/vg/stormwater/newtech/eguivalent.htmlBMPC106:WheelWashPurposeConditionsofUseWheelwashesreducetheamountofsedimenttransportedontopavedroadsbymotorvehicles.‘Whenastabilizedconstructionentrance(seeBMPC105)isnotpreventingsedimentfrombeingtrackedontopavement.WheelwashingisgcncrallyancffectivcBMPwheninstallcdwithcarefulattentiontotopography.Forexample,awheelwashcanbedetrimentalifinstalledatthetopofaslopeabuttingaright-of-waywherethewaterfromthedrippingtruckcanrununimpededintotheStreet.DiwayshaltmeetIrerequirementsofthepermittingagencyisrecommendedthattheentrancebecrownedsothatrunoffdrainsoffthepad-ltnsitdrivewaycutveriif?‘&eisaroadsideditchpresent4’—8’quarryspattsGeolextire17mm.thicknessPrcvdeluwidthoftgressJegressareaohinwConstructionStornnt’aterPollutionPreen/ioniiILV/2012 •Pressurewashingcombinedwithanadequatelysizedandsurfacedpadwithdirectdrainagetoalarge10-footx10-footsumpcanbevery’effective.•Dischargewheelwashortirebathwastewatertoaseparateon-sitetreatmentsystemthatpreventsdischargetosurfacewater,suchasclosed-looprecirculationoruplandlandapplication,ortothesanitarysewerwithlocalsewerdistrictapproval.•Wheelwashortirebathwastewatershouldnotincludewastewaterfromconcretewashoutareas.DesignandSuggesteddetailsareshowninFigure4.1.2.TheLocalPermittingInstallationAuthoritymayallowotherdesigns.Aminimumof6inchesofasphaltSpecjflcauonstreatedbase(ATB)overcrushedbasematerialor8inchesoveragoodsubgradeisrecommendedtopavethewheelwash.Usealowclearancetrucktotestthewheelwashbeforepaving.Eitherabellydumporlowboywillworkwelltotestclearance.Keepthewaterlevelfrom12to14inchesdeeptoavoiddamagetotruckhubsandfillingthetrucktongueswithwater.Midpointspraynozzlesareonlyneededinextremelymuddyconditions.Wheelwashsystemsshouldbedesignedwithasmallgradechange,6-to1-inchesfora10-foot-widepond,toallowsedimenttoflowtothelowsideofpondtohelppreventre-suspensionofsediment.Adrainpipewitha2-to3-footrisershouldbeinstalledonthelowsideofthepondtoallowforeasycleaningandrefilling.Polymersmaybeusedtopromotecoagulationandflocculationinaclosed-loopsystem.Polyacrylamide(PAM)addedtothewheelwashwateratarateof0.25-0.5poundsper1,000gallonsofwaterincreaseseffectivenessandreducescleanuptime.IfPAMisalreadybeingusedfordustorerosioncontrolandisbeingappliedbyawatertruck,thesametruckcanbeusedtochangethewashwater.MaintenanceThewheelwashshouldstartoutthedaywithfreshwater.StandardsThewashwatershouldbechangcdaminimumofonceperday.Onlargeearilworkjobswheremorethan10-20trucksperhourareexpected,the‘ashwaterwillneedtobechangedmoreoften.ohe;;wConstructionStonmi’ate,PollutionPreeu/ioniius!201210 ‘‘i[jMIDPOINTSPRAYNOZZLESJEDEDI2%s7I___iIIENEL1:11SLOPE-SLOPE,II2XSLOPEII-‘t—CAmCONSTRUCtONSLOPEACICTRANCE15’ATBAPRONTOPROTECTASPHALTCURBONTHEGROUNDFROMSPLASHINGWATERLOWROADSIDETODIRECT5SLEEVEUNDERROADWATERSACKTOPONDIPLANViEW]I_15_l15-2OI_15’__50Notes:Figure4.1.2—WheelWashI.Asphaltconstructionentrance6in.asphalttreatedbase(ATB).2.3-inchtrashpumpwithfloatsonthesuctionhose.3.Midpointspraynozzles,ifneeded.4.6-inchsewerpipewithbutterflyvalves.Bottomoneisadrain.Locatetoppipe’sinvert1footabovebottomofwheelwash.5.8footx8footsumpwith5feetofcatch.Buildsothesumpcanbecleanedwithatrackhoe.6.Asphaltcurbonthelowroadsidetodirectwaterbacktopond.7.6-inchsleeveunderroad.8.Ballvalves.9.15foot.ATBaprontoprotectgroundfromsplashingwater.ohuneConstructionStormu’a!erPollutionPieen/ionxius!20126SEWERPIPEWITHBU1TERFLYVALVES—WxB’SUMPWITH5’OFCATCH3TRASHPUMPWITHFLOATSAONSUCTIONHOSE—2SCHEDULE40l—T/2SCHEDULE40-FORSPRAYERSIIIICSLEEVEIELEVA11ONV1EWILOCATEINVERTOFTOPPIPE1•ABOVEBOTTOMOFWHEELWASHSxS’SWAP•‘N%‘\\WATERLEVEL4,I.3’5.DRAINPIPEISECT1ONA—AlNOTES:11SLOPE1.BUILDB’xWSUMPTOACCOMODATECLEANINGBYTRACKHOE.11 BMPC107:ConstructionRoadlParkingAreaStabilizationPurposeStabilizingsubdivisionroads,parkingareas,andotheron-sitevehicletransportationroutesimmediatelyaftergradingreduceserosioncausedbyconstructiontrafficorrunoff.ConditionsofUseRoadsorparkingareasshallbestabilizedwherevertheyareconstructed,whetherpermanentortemporary,forusebyconstructiontraffic.HighVisibilityFencing(seeBMPC103)shallbeinstalled,ifnecessary,tolimittheaccessofvehiclestoonlythoseroadsandparkingareasthatarestabilized.Designand•Onareasthatwillreceiveasphaltaspartoftheproject,installthefirstInstallationliftassoonaspossible.Specj,flcationsA6-inchdepthof2-to4-inchcrushedrock,gravelbase,orcrushedsurfacingbasecourseshallbeappliedimmediatelyaftergradingorutilityinstallation.A4-inchcourseofasphalttreatedbase(ATB)mayalsobeused,ortheroad/parkingareamaybepaved.Itmayalsobepossibletousecementorcalciumchlorideforsoilstabilization.Ifcementorcementkilndustisusedforroadbasestabilization,pHmonitoringandBMPs(BMPsC252andC253)arenecessarytoevaluateandminimizetheeffectsonstormwater.Iftheareawillnotbeusedforpermanentroads,parkingareas,orstructures,a6-inchdepthofhogfuelmayalsobeused,butthisislikelytorequiremoremaintenance.Wheneverpossible,constructionroadsandparkingareasshallbeplacedonafirm,compactedsubgrade.•Temporaryroadgradientsshallnotexceed15percent.Roadwaysshallbecarefullygradedtodrain.Drainageditchesshallbeprovidedoneachsideoftheroadwayinthecaseofacrownedsection,orononesideinthecaseofasuper-elevatedsection.DrainageditchesshallbedirectedtoasedimentcontrolBMP.•Ratherthanrelyingonditches,itmayalsobepossibletogradetheroadsothatrunoffsheet-flowsintoaheavilyvegetatedareawithawell-developedtopsoil.Landscapedareasarenotadequate.Ifthisareahasatleast50feetofvegetationthatwatercanflowthrough,thenitisgenerallypreferabletousethevegetationtotreatrunoff,ratherthanasedimentpondortrap.The50feetshallnotincludewetlandsortheirbuffers.Ifrunoffisallowedtosheetfiowthroughadjacentvegetatedareas,itisvitaltodesigntheroadwaysandparkingareassothatnoconcentratedrunoffiscreated.•Stormdraininletsshallbeprotectedtopreventsediment-ladenwaterenteringthestormdrainsystem(seeBMPC220).MaintenanceInspectstabilizedarcasregularly,especiallyafterlargestormevents.StandardsCrushedrock,gravelbase,etc.shallbeaddedasrequiredtomaintainaohmicConstrue/iouStonnwa/erPollutionPieen/ionuus!201212 stabledrivingsurfaceandtostabilizeanyareasthathaveeroded.Followingconstruction,theseareasshallberestoredtopre-constructionconditionorbettertopreventfutureerosion.Performstreetcleaningattheendofeachdayormoreoftenifnecessary.BMPC120:TemporaryandPermanentSeedingPurposeSeedingreduceserosionbystabilizingexposedsoils.Awell-establishedvegetativecoverisoneofthemosteffectivemethodsofreducingerosion.conditionsofUseUseseedingthroughouttheprojectondisturbedareasthathavereachedfinalgradeorthatwillremainunworkedformorethan30days.TheoptimumseedingwindowsforwesternWashingtonareApril1throughJune30andSeptember1throughOctober1.BetweenJuly1andAugust30seedingrequiresirrigationuntil75percentgrasscoverisestablished.BetweenOctober1andMarch30seedingrequiresacoverofmulchwithstraworanerosioncontrolblanketuntil75percentgrasscoverisestablished.ReviewalldisturbedareasinlateAugusttoearlySeptemberandcompleteallseedingbytheendofSeptember.Otherwise,vegetationwillnotestablishitselfenoughtoprovidemorethanaverageprotection.•Mulchisrequiredatalltimesforseedingbecauseitprotectsseedsfromheat,moistureloss,andtransportduetorunoff.Mulchcanbeappliedontopoftheseedorsimultaneouslybyhydroseeding.SeeBMPC121:Mulchingforspecifications.•Seedandmulch,alldisturbedareasnototherwisevegetatedatfinalsitestabilization.Finalstabilizationmeansthecompletionofallsoildisturbingactivitiesatthesiteandtheestablishmentofapermanentvegetativecover,orequivalentpermanentstabilizationmeasures(suchaspavement,riprap,gabionsorgeotextiles)whichwillpreventerosion.DesignandSeedretention/detentionpondsasrequired.Installation..InstallchannelsintendedforvegetationbeforestartingmajorSpecificationsearthworkandhydroseedwithaBondedFiberMatrix.Forvegetatedchannelsthatwillhavehighflows,installerosioncontrolblanketsoverhydroseed.Beforeallowingwatertoflowinvegetatedchannels,establish75percentvegetationcover.Ifvegetatedchannelscannotbeestablishedbyseedbeforewaterflow;installsodinthechannelbottom—overhydromulchanderosioncontrolblankets.ohuneConstructionStormit’cg!erPollutionPreentionitus!2012I •Confirmtheinstallationofallrequiredsurfacewatercontrolmeasurestopreventseedfromwashingaway.•1-lydroseedapplicationsshallincludeaminimumof1,500poundsperacreofmulchwith3percenttackifier.SeeBMPC121:Mulchingforspecifications.•Areasthatwillhaveseedingonlyandnotlandscapingmayneedcompostormeal-basedmulchincludedinthehydroseedinordertoestablishvegetation.Re-installnativetopsoilonthedisturbedsoilsurfacebeforeapplication.•Wheninstallingseedviahydroseedingoperations,onlyabout1/3oftheseedactuallyendsupincontactwiththesoilsurface.Thisreducestheabilitytoestablishagoodstandofgrassquickly.Toovercomethis,considerincreasingseedquantitiesbyupto50percent.•Enhancevegetationestablishmentbydividingthehydromulchoperationintotwophases:1.Phase1-Installallseedandfertilizerwith25-30percentmulchandtackifierontosoilinthefirstlift.2.Phase2-Installtherestofthemulchandtackifieroverthefirstlift.Or,enhancevegetationby:1.Installingthemulch,seed,fertilizer,andtackifierinonelift.2.Spreadorblowstrawoverthetopofthehydromulchatarateof800-1000poundsperacre.3.Holdstrawinplacewithastandardtackifier.Bothoftheseapproacheswillincreasecostmoderatelybutwillgreatlyimproveandenhancevegetativeestablishment.Theincreasedcostmaybeoffsetbythereducedneedfor:•Irrigation.•Reapplicationofmulch.•Repairoffailedslopesurfaces.Thistechniqueworkswithstandardhydromulch(1,500poundsperacreminimum)andBFM/MBFMs(3,000poundsperacreminimum).•Seedmaybeinstalledbyhandif:•Temporaryandcoveredbystraw,mulch,ortopsoil.•Permanentinsmallareas(usuallylessthanIacre)andcoveredwithmulch,topsoil,orerosionblankets.•Theseedmixeslistedinthetablesbelowincluderecommendedmixesforbothtemporaryandpermanentseeding.ohinwCojs/riic/ionStonnwalerPollutionPreentionitus!20121 •Applythesemixes,withtheexceptionofthewetlandmix.atarateof120poundsperacre.Thisratecanbereducedifsoilamendmentsorslow-releasefertilizersareused.•Consultthelocalsuppliersorthelocalconservationdistrictfortheirrecommendationsbecausetheappropriatemixdependsonavarietyoffactors.includinglocation,exposure,soiltype.slope,andexpectedfoottraffic.Alternativeseedmixesapprovedbythelocalauthoritymaybeused.•Othermixesmaybeappropriate,dependingonthesoiltypeandhydrologyofthearea.Table4.1.2liststhestandardmixforareasrequiringatemporaryvegetativecover.Table4.1.2TemporaryErosionControlSeedMixVjPHGrmaionChewingsorannualbluegrass409890es/zetarubraarconnnzilataorFociannaPerennialrye-509890olizen,erauneRedtoporcolonialbentgrass59285rosilsa/baorrostistenzeisWhitedutchclover59890HolwnzleeflY•Table4.1.3listsarecommendedmixforlandscapingseed.Table4.1.3LandscapingSeedMixWIPriGrinnionPerennialryeblend709890oliuiiiL’PL’fl?7L’Chewingsandredfescueblend309890esnecarubraciicommu!a!aorestiecarzthraobtineConstrue/ionStornzwa!erPollutionPieen/ioniius!2012I •Table4.1.4listsaturfseedmixfordrysituationswherethereisnoneedforwatering.Thismixrequiresverylittlemaintenance.Table4.1.4Low-GrowingTurfSeedMixViPriGrinaionDwarftallfescue(severalvarieties)459890estucaaninmaccaat—____ ____ ____ ____ ____ ___Dwarfperennialrye(Barclay)309890olin,;,erenneatbare/aRedfescue209890estucarzthraColonialbentgrass59890roslislefliUS•Table4.1.5listsamixforbioswalesandotherintermittentlywetareas.Table4.1.5BioswaleSeedMix*ViPriGrinsionTallormeadowfescue75-809890extneaaruniizaceaoresfltcac/allotSeaside/Creepingbentgrass10-159285rostisalusirisRedtopbentgrass5-109080rostisathaorrosiLyian/caolierimteen,ncroseeinGuieel/ansSeeohmicCons/rudilonS!or,nii’a!erPolhthonPieenlionuus!2012I •Table4.1.6listsalow-growing,relativelynon-invasiveseedmixappropriateforverywetareasthatarenotregulatedwetlands.Applythismixtureatarateof60poundsperacre.Consult1-lydraulicPermitAuthority(HPA)forseedmixesifapplicable.Table4.1.6WetAreaSeedMix*WiPriCrinnionTallormeadowfescue60-709890cx!ucaan/nmaccaores/ucacia/lopSeaside/Creepinghentgrass10-159885rosilsa/its!risMeadowfoxtail10-159080icocurusratensisAlsikeclover1-69890,ioliumbriinnRedtopbentgrass1-69285rostisa/baolieriarreen,nerosecinGuiec//ansSeci•Table4.1.7listsarecommendedmeadowseedmixforinfrequentlymaintainedareasornon-maintainedareaswherecolonizationbynativeplantsisdesirable.Likelyapplicationsincluderuralroadandutilityright-of-way.SeedingshouldtakeplaceinSeptemberorveryearlyOctoberinordertoobtainadequateestablishmentpriortothewintermonths.Considertheappropriatenessofclover,afairlyinvasivespecies,inthemix.Amendingthesoilcanreducetheneedforclover.Table4.1.7MeadowSeedMixWIPriCrinnionRedtoporOregonbentgrass209285rostisa/baorrostisor e onensi s -____ _ _ ________ _ _ ________ _ _ ________ _ _ ________ _ _ ________ _ _Redfescue709890csfltcariebra-___________-___ __Whitedutchclover109890ri0/li/fl?PCCfl5oheineConstructionS!ornnva/crPo/huio,zPieeli//oiluus!20121 •RonmandRo01iiiTheseedbedshouldbefirmandrough.Roughenallsoilnomatterwhattheslope.Trackwalkslopesbeforeseedingifengineeringpurposesrequirecompaction.Backbladingorsmoothingofslopesgreaterthan4H:lVisnotallowediftheyaretobeseeded.•Restoration-basedlandscapepracticesrequiredeeperincorporationthanthatprovidedbyasimplesingle-passrototillingtreatment.Whereverpractical,initiallyripthesubgradetoimprovelong-termpermeability,infiltration,andwaterinflowqualities.Ataminimum,permanentareasshallusesoilamendmentstoachieveorganicmatterandpermeabilityperformancedefinedinengineeredsoil/landscapesystems.Forsystemsthataredeeperthan8inchescompletetherototillingprocessinmultiplelifts,orpreparetheengineeredsoilsystemperspecificationsandplacetoachievethespecifieddepth.•Friir•Conductingsoilteststodeterminetheexacttypeandquantityoffertilizerisrecommended.Thiswillpreventtheover-applicationoffertilizer.•Organicmatteristhemostappropriateformoffertilizerbecauseitprovidesnutrients(includingnitrogen,phosphorus,andpotassium)intheleastwater-solubleform.•Ingeneral,use10-4-6N-P-K(nitrogen-phosphorus-potassium)fertilizeratarateof90poundsperacre.Alwaysuseslow-releasefertilizersbecausetheyaremoreefficientandhavefewerenvironmentalimpacts.Donotaddfertilizertothehydromulchmachine,oragitate,morethan20minutesbeforeuse.Toomuchagitationdestroystheslow-releasecoating.•Therearenumerousproductsavailablethattaketheplaceofchemicalfertilizers.Theseincludeseveralwithseaweedextractsthatarebeneficialtosoilmicrobesandorganisms.If100percentcottonseedmealisusedasthemulchinhydroseed,chemicalfertilizermaynotbenecessary.Cottonseedmealprovidesagoodsourceoflong-term,slow-release,availablenitrogen.•BonddFirMaiiandManiaBonddFirMari•OnsteepslopesuseBondedFiberMatrix(BFM)orMechanicallyBondedFiberMatrix(MBFM)products.ApplyBFM/MBFMproductsataminimumrateof3,000poundsperacreofmulchwithapproximately10percenttackifier.Achieveaminimumof95pcrcentsoilcovcragcduringapplication.Numerousproductsarcavailablecommercially.Installedproductspermanufacturer’sinstructions.Mostproductsrequire24-36hourstocurebeforerainfallandcannotbeinstalledonwetorsaturatedsoils.ohiineConsfiuctionSlornni’aterPollutionPreentioniius!2012I Generally,productscomein40-50poundbagsandincludeallnecessaryingredientsexceptforseedandfertilizer.•BFMsandMBFMSprovidegoodalternativestoblanketsinmostareasrequiringvegetationestablishment.Advantagesoverblanketsinclude:•BFMandMBFMsdonotrequiresurfacepreparation.•HelicopterscanassistininstallingBFMandMBFMsinremoteareas.•Onslopessteeperthan2.5H:IV.blanketinstallersmayrequireropesandharnessesforsafety.•InstallingBFMandMBFMscansaveatleast$1,000peracrecomparedtoblankets.MaintenanceReseedanyseededareasthatfailtoestablishatleast80percentcoverStandards(100percentcoverforareasthatreceivesheetorconcentratedflows).Ifreseedingisineffective,useanalternatemethodsuchassodding,mulching.ornets/blankets.Ifwinterweatherpreventsadequategrassgrowth,thistimelimitmayberelaxedatthediscretionofthelocalauthoritywhensensitiveareaswouldotherwisebeprotected.Reseedandprotectbymulchanyareasthatexperienceerosionafterachievingadequatecover.Reseedandprotectbymulchanyerodedarea.Supplyseededareaswithadequatemoisture,butdonotwatertotheextentthatitcausesrunoffApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC120.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.LocaljurisdictionsmaychoosenottoacceptthisproductapprovedasequivalenLormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecy.wa.gov/proErams/wg/stornnvater/newtech/eguivalent.htmlBMPC121:MulchingPurposeMulchingsoilsprovidesimmediatetemporaryprotectionfromerosion.Mulchalsoenhancesplantestablishmentbyconservingmoisture,holdingfertilizer,seed,andtopsoilinplace,andmoderatingsoiltemperatures.Thereisanenormousvarietyofmulchesthatcanbeused.Thissectiondiscussesonlythemostcommontypesofmulch.Asatemporan’covermeasure,mulchshouMbeused:condznoizsofUse•Forlessthan30daysondisturbedareasthatrequirecover.•Atalltimesforseededareas,especiallyduringthewetseasonandolunieConstructionStonniva!erPollutionPieeu/ionuus!2012I duringthehotsummermonths.•Duringthewetseasononslopessteeperthan31T:IVwithmorethan10feetofverticalrelief.Mulchmaybeappliedatanytimeoftheyearandmustberefreshedperiodically.•Forseededareasmulchmaybemadeupof100percent:cottonseedmeal;fibersmadeofwood,recycledcellulose,hemp,kenaf;compost;orblendsofthese.Tackifiershallbeplant-based,suchasguaroralphaplantago,orchemical-basedsuchaspolyaciylamideorpolymers.Anymulchortackifierproductusedshallbeinstalledpermanufacturer’sinstructions.Generally,mulchescomein40-50poundbags.Seedandfertilizerareaddedattimeofapplication.DesignandFormulchmaterials,applicationrates,andspecifications,seeTable4.1.8.InstallationAlwaysusea2-inchminimummulchthickness;increasethethicknessSpecjficationsuntilthegroundis95%covered(i.e.notvisibleunderthemulchlayer).Note:Thicknessmaybeincreasedfordisturbedareasinornearsensitiveareasorotherareashighlysusceptibletoerosion.Mulchusedwithintheordinaryhigh-watermarkofsurfacewatersshouldbeselectedtominimizepotentialflotationoforganicmatter.Compostedorganicmaterialshavehigherspecificgravities(densities)thanstraw,wood,orchippedmaterial.ConsultHydraulicPermitAuthority(HPA)formulchmixesifapplicable.Maintenance•Thethicknessofthecovermustbemaintained.Standards•Anyareasthatexperienceerosionshallberemuichedand/orprotectedwithanetorblanket.Iftheerosionproblemisdrainagerelated,thentheproblemshallbefixedandtheerodedarearemulched.olnincCons/rue/jo,,Stonuwa/erPollutionPreen/ionuus!201220 Table4.1.8MulchStandardsandGuidelinesAiaionNIManaQaiSandardRaRanStrawAir-dried;freefrom2”-3”thick;SCost-effectiveprotectionwhenappliedwithadequatethickness.undesirableseedandbalesper1,000Hand-applicationgenerallyrequiresgreaterthicknessthancoarsematerial.sfor2-3tonsperblownstraw.Thethicknessofstrawmaybereducedbyhalfacrewhenusedinconjunctionwithseeding.Inwindyareasstrawmustbeheldinplacebycrimping,usingatackifier,orcoveringwithnetting,blownstrawalwayshastobeheldinplacewithatackiflerasevenlightwindswillblowitaway.Straw,however,hasseveraldeficienciesthatshouldbeconsideredwhenselectingmulchmaterials.Itofienintroducesand/orencouragesthepropagationofweedspeciesandithasnosignificantlongtermbenefits.Itshouldalsonotbeusedwithintheordinaryhigh-waterelevationofsurfacewaters(duetoflotation).HydromulchNogrowthApprox.25-30Shallbeappliedwithhydromulcher.Shallnotbeusedwithoutinhibitingfactors.lbsper1,000sfseedandtackilierunlesstheapplicationrateisatleastdoubled.or1,500-2,000Fiberslongerthanabout¼-Iinchcloghydromulchequipment.lbsperacreFibersshouldbekepttolessthan¼inch.CompostedNovisiblewateror2”thickmm.;MoreeffectivecontrolcanbeobtainedbyincreasingthicknessMulchanddustduringapprox.100tonsto3”.ExcellentmulchforprotectingfinalgradesuntilComposthandling.Mustbeperacre(approx.landscapingbecauseitcanbedirectlyseededortilledintosoilproducedin800lbsperyard)asanamendment.Compostedmulchhasacoarsersizeaccordancewithgradationthancompost.Itismorestableandpracticaltousein173-350,wetareasandduringrainyweatherconditions.DonotuseSolidWastecompostedmulchnearwetlandsornearphosphorousimpairedHandlingStandards,waterbodies.ChippedSiteAveragesizeshall2”thickmm.;Thisisacost-eflectivewaytodisposeofdebrisfromclearingVegetationbeseveralinches.andgrubbing,anditeliminatestheproblemsassociatedwithGradationsfromburning.Generally,itshouldnotbeusedonslopesabovefinesto6inchesinapprox.10%becauseofitstendencytobetransportedbylengthfortexture,runoff.Itisnotrecommendedwithin200feetofsurfacewaters.variation,andIfseedingisexpectedshortlyaftermulch,thedecompositionofinterlockingthechippedvegetationmaytieupnutrientsimportanttograssproperties.establishment.Wood-basedNovisiblewateror2”thickmm.;Thismaterialisoftencalled“hogorhoggedfuel.”TheuseofMulchorWooddustduringapprox.100tonsmulchultimatelyimprovestheorganicmatterinthesoil.Strawhandling.Mustbeperacre(approx.Specialcautionisadvisedregardingthesourceandcompositionpurchasedfroma800lbs.perolwood-basedmulches.ItspreparationtypicallydoesnotsupplierwithaSolidcubicyard)provideanyweedseedcontrol,soevidenceofresidualWasteHandlingvegetationinitscompositionorknowninclusionofweedplantsPermitoroneorseedsshouldbemonitoredandprevented(orminimized).exemptfromsolidwasteregulations.VoodStrandAblendofloose,2”thickmm.Cost-effectiveprotectionwhenappliedwithadequatethickness.Mulchlong.thinwoodAminimumof95-percentofthewoodstrandshallhavelengthspiecesderivedfrombetween2and10-inches,withawidthandthicknessbetweennativeconiferor1/16atid¼-inches.Themulchshallnotcontainresin,tannin,ordeciduoustreeswithothercompoundsinquantitiesthatwouldbedetrimentaltoplanthighlength-to-widthlife.Sawdustorwoodshavingsshallnotbeusedasmulch.ratio.(WSDOTspecification(9-14.4(4))ohimeCotis!ruc/ionS/ornnt’aterPollutionPreen/ionitus!201221 BMPC122:NetsandBlanketsPurposeErosioncontrolnetsandblanketsareintendedtopreventerosionandholdseedandmulchinplaceonsteepslopesandinchannelssothatvegetationcanbecomewellestablished.Inaddition,somenetsandblanketscanbeusedtopermanentlyreinforceturftoprotectdrainagewaysduringhighflows.Nets(commonlycalledmatting)arestrandsofmaterialwovenintoanopen,buthigh-tensilestrengthnet(forexample.coconutfibermatting).Blanketsarestrandsofmaterialthatarenottightlywoven,butinsteadformalayerofinterlockingfibers.typicallyheldtogetherbyabiodegradableorphotodegradablenetting(forexample,excelsiororstrawblankets).Theygenerallyhavelowertensilestrengththannets,butcoverthegroundmorecompletely.Coir(coconutfiber)fabriccomesasbothnetsandblankets.(‘ondiliousofUseErosioncontrolnetsandblanketsshouldbeused:•Toaidpermanentvegetatedstabilizationofslopes21-I:IVorgreaterandwithmorethan10feetofverticalrelief.•Fordrainageditchesandswales(highlyrecommended).Theapplicationofappropriatenettingorblankettodrainageditchesandswalescanprotectbaresoilfromchannelizedrunoffwhilevegetationisestablished.Netsandblanketsalsocancaptureagreatdealofsedimentduetotheiropen,porousstructure.Netsandblanketscanbeusedtopermanentlystabilizechannelsandmayprovideacost-effective,environmentallypreferablealternativetoriprap.100percentsyntheticblanketsmanufacturedforuseinditchesmaybeeasilyreusedastemporaryditchliners.Disadvantagesofblanketsinclude:•Surfacepreparationrequired.•Onslopessteeperthan2.5H:IV,blanketinstallersmayneedtoberopedandharnessedforsafety.•Theycostatleast$4,000-6,000peracreinstalled.Advantagesofblanketsinclude:•Installationwithoutmobilizingspecialequipment.•Installationbyanyonewithminimaltraining•Installationinstagesorphasesastheprojectprogresses.•Installerscanhandplaceseedandfertilizerastheyprogressdowntheslope.•Installationinanyweather.•Therearenumeroustypesofblanketsthatcanbedesignedwithvariousparametersinmind.Thoseparametersinclude:fiberblend,meshstrength,longevity,biodegradability,cost,andavailability.ohnneConstructionStornnt’a!crPollutionPieen/ionuus!2012‘2 Designand•SeeFiure4.1.3andFiQure4.1.4fortypicalorientationandInstallationinstallationofblanketsusedinchannelsandasslopeprotection.Note:Specjflcutionsthesearetypicalonly;allblanketsmustbeinstalledpermanufacturer’sinstallationinstructions.Installationiscriticaltotheeffectivenessoftheseproducts.Ifgoodgroundcontactisnotachieved.runoffcanconcentrateundertheproduct,resultinginsignificanterosion.InstallationofBlanketsonSlopes:I.Completefinalgradeandtrackwalkupanddowntheslope.2.Installhydromulehwithseedandfertilizer.3.Digasmalltrench,approximately12incheswideby6inchesdeepalongthetopoftheslope.4.Installtheleadingedgeoftheblanketintothesmalltrenchandstapleapproximatelyevery18inches.NOTE:Staplesaremetal,“U”-shaped,andaminimumof6incheslong.Longerstaplesareusedinsandysoils.Biodegradablestakesarealsoavailable.5.Rolltheblanketslowlydowntheslopeasinstallerwalksbackwards.NOTE:Theblanketrestsagainsttheinstaller’slegs.Staplesareinstalledastheblanketisunrolled.Itiscriticalthattheproperstaplepatternisusedfortheblanketbeinginstalled.Theblanketisnottobeallowedtorolldowntheslopeonitsownasthisstretchestheblanketmakingitimpossibletomaintainsoilcontact.Inaddition,nooneisallowedtowalkontheblanketafteritisinplace.6.Iftheblanketisnotlongenoughtocovertheentireslopelength,thetrailingedgeoftheupperblanketshouldoverlaptheleadingedgeofthelowerblanketandbestapled.Onsteeperslopes,thisoverlapshouldbeinstalledinasmalltrench,stapled,andcoveredwithsoil.Withthevarietyofproductsavailable,itisimpossibletocoverallthedetailsofappropriateuseandinstallation.Therefore,itiscriticalthatthedesignengineerconsultthemanufacturersinformationandthatasitevisittakesplaceinordertoensurethattheproductspecifiedisappropriate.Informationisalsoavailableatthefollowingwebsites:1.WSDOT(Section3.2.4):http://www.wsdot.wa.gov/NR!rdonlyres/3B4IE087-FA86-4717-932D-D7A8556CCD57/O/ErosionTraininaManual.pdf2.TexasTransportationInstitute:http://www.txdot.govfbusiness/doingbusiness/productevaluation!erosioncontrol.htmoIzll;?c’ConstruclionS/or,nii’c,/erPollutionPieen/ioniius!20122 •Usejutemattinginconjunctionwithmulch(BMPC121).Excelsior,wovenstrawblanketsandcoir(coconutfiber)blanketsmaybeinstalledwithoutmulch.Therearemanyothertypesoferosioncontrolnetsandblanketsonthemarketthatmaybeappropriateincertaincircumstances.•Ingeneral,mostnets(e.g.,jutematting)requiremulchinordertopreventerosionbecausetheyhaveafairlyopenstructure.Blanketstypicallydonotrequiremulchbecausetheyusuallyprovidecompleteprotectionofthesurface.•Extremelysteep,unstable,‘vet,orrockyslopesareoftenappropriatecandidatesforuseofsyntheticblankets,asareriverbanks,beachesandotherhigh-energyenvironments.Ifsyntheticblanketsareused,thesoilshouldbehvdromulchedfirst.•100-percentbiodegradableblanketsareavailableforuseinsensitiveareas.Theseorganicblanketsareusuallyheldtogetherwithapaperorfibermeshandstitchingwhichmaylastuptoayear.•Mostnettingusedwithblanketsisphotodegradable.meaningtheybreakdownundersunlight(notUVstabilized).However,thisprocesscantakemonthsoryearsevenunderbrightsun.Oncevegetationisestablished,sunlightdoesnotreachthemesh.Itisnotuncommontofindnon-degradednettingstillinplaceseveralyearsafterinstallation.Thiscanbeaproblemifmaintenancerequirestheuseofmowersorditchcleaningequipment.Tnaddition,birdsandsmallanimalscanbecometrappedinthenetting.Maintenance•Maintaingoodcontactwiththeground.ErosionmustnotoccurStandardsbeneaththenetorblanket.•Repairandstapleanyareasofthenetorblanketthataredamagedornotinclosecontactwiththeground.•Fixandprotecterodedareasiferosionoccursdue10poorlycontrolleddrainage.olwncConstructionStornni’aterPollutionPit’eu/ioniius!20)22 InitIalChannelAnchorTrenchNOTES:1.Checkplot,lobeeoo,wactedpermanufacorm.peciflcationL2.Stakingorstaplinglayoutpetmanufnrn.pcdliadou’.Figure4.1.3—ChannelInstallationFigure4.1.4—SlopeInstallationohmwConstructionStornnt’atc’rPollutionPieen/ionuus!2012LorçlkTh&ArtlorTrorchTerminalSlopeandChannelAnchorTrenchO4?IntermittentCheckSlotSlopesurfaceshallbesmoothbeforeplacementforpropersoilcontact.Staplingpatternaspermanufacturer’srecommendatic-ns.Mm.2OverlapIfthereisabermatthetopofslope,anchorupslopeoftheberm.Anchorhi&x6’mhi.Trenchandstapleat12”intervals.Mm.6’overlap.Stapleoverlapsmax.5”spacing.Bringmaterialdowntoalevelarea,turnDonotstretchblanketsimattingstight-theendunder4”andstapleat12’intervals.allowtherollstomoldtoanyirregularities.Forslopeslessthan3H1V,rollsmaybeplacedinhorizontalstrips,Lime,ferlilize,andseedbeforeinstallation.Plantingofshrubs,trees,etc.Shouldoccurafterinstallation.2 BMPC123:PlasticCoveringPurposePlasticcoveringprovidesimmediate,short-termerosionprotectiontoslopesanddisturbedareas.ConditionsofPlasticcoveringmaybeusedondisturbedareasthatrequirecoverUsemeasuresforlessthan30days,exceptasstatedbelow.•Plasticisparticularlyusefulforprotectingcutandfillslopesandstockpiles.Note:Therelativelyrapidbreakdownofmostpolyethylenesheetingmakesitunsuitableforlong-term(greaterthansixmonths)applications.•Duetorapidrunoffcausedbyplasticcovering,donotusethismethodupsiopeofareasthatmightbeadverselyimpactedbyconcentratedrunoff.Suchareasincludesteepand/orunstableslopes.•Plasticsheetingmayresultinincreasedrunoffvolumesandvelocities,requiringadditionalon-sitemeasurestocounteracttheincreases.Creatingatroughwithwattlesorothermaterialcanconveycleanwaterawayfromtheseareas.•Topreventundercutting,trenchandbackfillrolledplasticcoveringproducts.•Whileplasticisinexpensivetopurchase,theaddedcostofinstallation,maintenance,removal,anddisposalmakethisanexpensivematerial,upto$1.50-2.00persquareyard.•Wheneverplasticisusedtoprotectslopesinstallwatercollectionmeasuresatthebaseoftheslope.Thesemeasuresincludeplastic-coveredberms.channels,andpipesusedtocoveycleanrainwaterawayfrombaresoilanddisturbedareas.Donotmixcleanrunofffromaplasticcoveredslopewithdirtyrunofffromaproject.•Otherusesforplasticinclude:1.Temporaryditchliner.2.Pondlinerintemporarysedimentpond.3.Lincrforbcrmcdtcmporaiyfuelstoragearcaifplasticisnotreactivetothetypeoffuelbeingstored.4.Emergencyslopeprotectionduringheavyrains.5.Temporarydrainpipe(“elephanttrunk”)usedtodirectwater.Designand•Plasticslopecovermustbeinstalledasfollows:InstallationI.Runplasticupanddownslopc,notacrossslope.Specifications2.Plasticmaybeinstalledperpendiculartoaslopeiftheslopelengthislessthan10feet.3.Minimumof8-inchoverlapatseams.ohiineCons!uzictio,zStonmi’aterPollutionPieen/iouiius!2012 4.Onlongorwideslopes,orslopessubjecttowind,tapeallseams.5.Placeplasticintoasmall(12-inchwideby6-inchdeep)slottrenchatthetopoftheslopeandbackfillwithsoiltokeepwaterfromflowingunderneath.6.Placesandfilledburlaporgeotextilebagsevery3to6feetalongseamsandtiethemtogetherwithtwinetoholdtheminplace.7.Inspectplasticforrips,tears,andopenseamsregularlyandrepairimmediately.Thispreventshighvelocityrunofffromcontactingbaresoilwhichcausesextremeerosion.8.Sandbagsmaybeloweredintoplacetiedtoropes.However,allsandbagsmustbestakedinplace.•Plasticsheetingshallhaveaminimumthicknessof0.06millimeters.•Tferosionatthetoeofaslopeislikely,agravelberm,riprap,orothersuitableprotectionshallbeinstalledatthetoeoftheslopeinordertoreducethevelocityofrunoff.Maintenance•Tornsheetsmustbereplacedandopenseamsrepaired.Standards•Completelyremoveandreplacetheplasticifitbeginstodeteriorateduetoultravioletradiation.•Completelyremoveplasticwhennolongerneeded.•Disposeofoldtiresusedtoweightdownplasticsheetingappropriately.ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC123.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionalEestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://wwxv.ecy.wa.ov/proarams/wg/stormwater/newtech/eguivalent.htmlBMPC124:SoddingPurposeThepurposeofsoddingistocstablishpermanentturfforimmediateerosionprotectionandtostabilizedrainagewayswhereconcentratedoverlandflowwilloccur.C’onditionsofUseSoddingmaybeusedinthefollowingareas:•Disturbedareasthatrequireshort—termorlong-termcover.•Disturbedareasthatrequireimmcdiatcvegetativecover.•Allwaterwaysthatrequirevegetativelining.Watenvaysmayalsobeseededratherthansodded,andprotectedwithanetorblanket.olunwConsflue/ionS/ornnraterPollutionPieeu/b,,iijust20127 DesignandSodshallbefreeofweeds.ofuniformthickness(approximately1-inchInstallationthick).andshallhaveadenserootmatformechanicalstrength.SpecjficutionsThefollowingstepsarerecommendedforsodinstallation:Shapeandsmooththesurfacetofinalgradeinaccordancewiththeapprovedgradingplan.Theswaleneedstobeoverexcavated4to6inchesbelowdesignelevationtoallowroomforplacingsoilamendmentandsod.•Amend4inches(minimum)ofcompostintothetop8inchesofthesoiliftheorganiccontentofthesoilislessthantenpercentorthepermeabilityislessthan0.6inchesperhour.Seehttp://www.ecv.va.2ov/prourams/swfaioruanics/soil.hunlforfurtherinformation.•Fertilizeaccordingtothesuppliersrecommendations.•WorklimeandfertilizerIto2inchesintothesoil,andsmooththesurface.•Laystripsofsodbeginningatthelowestareatobesoddedandperpendiculartothedirectionofwaterflow.Wedgestripssecurelyintoplace.Squaretheendsofeachstriptoprovideforaclose,tightfit.Staggerjointsatleast12inches.Stapleonslopessteeperthan3H:JV.Stapletheupstreamedgeofeachsodstrip.•Rollthesoddedareaandirrigate.•Whensoddingiscarriedoutinalternatingstripsorotherpatterns,seedtheareasbetweenthesodimmediatelyaftersodding.MaintenanceIfthegrassisunhealthy,thecauseshallbedeterminedandappropriateStandardsactiontakentoreestablishahealthygroundcover.Ifitisimpossibletoestablishahealthygroundcoverduetofrequentsaturation,instability,orsomeothercause,thesodshallberemoved,theareaseededwithanappropriatemix,andprotectedwithanetorblanket.BMPC125:TopsoilingICompostingPurposeTopsoilingandcompostingprovidcasuitablegrowthmediumforfinalsitestabilizationwithvegetation.Whilenotapermanentcoverpracticeinitself,topsoilingandcompostingareanintegralcomponentofprovidingpermanentcoverinthoseareaswherethereisanunsuitablesoilsurfaceforplantgrowth.UsethisBMPinconjunctionwithotherBMPssuchasseeding,mulching,orsodding.Nativesoilsanddisturbedsoilsthathavebeenorganicallyamendednotonlyretainmuchmorestoimwater,buttheyalsoserveaseffectivebiofiltersforurbanpollutantsand,bysupportingmorevigorousplantgrowth,reducethewater,fertilizerandpesticidesneededtosupportohmicConstructionStonnwaterPollutionPieeniloniinsf20127 installedlandscapes.Topsoildoesnotincludeanysubsoilsbutonlythematerialfromthetopseveralinchesincludingorganicdebris.Conditionsof.PermanentlandscapedareasshallcontainhealthytopsoilthatreducesUsetheneedforfertilizers,improvesoveralltopsoilquality,providesforbettervegetalhealthandvitality,improveshydrologiccharacteristics,andreducestheneedforirrigation.Leavenativesoilsandthedufflayerundisturbedtothemaximumextentpracticable.Strippingofexisting,properlyffinctioningsoilsystemandvegetationforthepurposeoftopsoilingduringconstructionisnotacceptable.Preserveexistingsoilsystemsinundisturbedanduncompactedconditionsifflrnctioningproperly.•Areasthatalreadyhavegoodtopsoil,suchasundisturbedareas,donotrequiresoilamendments.•Restore,tothemaximumextentpractical,nativesoilsdisturbedduringclearingandgradingtoaconditionequaltoorbetterthantheoriginalsitecondition’smoisture-holdingcapacity.Useon-sitenativetopsoil,incorporateamendmentsintoon-sitesoil,orimportblendedtopsoiltomeetthisrequirement.•Topsoilingisarequiredprocedurewhenestablishingvegetationonshallowsoils,andsoilsofcriticallylowp1-i(highacid)levels.•Bewareofwherethetopsoilcomesfrom,andwhatvegetationwasonsitebeforedisturbance,invasiveplantseedsmaybeincludedandcouldcauseproblemsforestablishingnativeplants,landscapedareas,orgrasses.•TopsoilfromthesitewiHcontainmycorrhizalbacteriathatarenecessaryforhealthyrootgrowthandnutrienttransfer.Thesenativemycorrhizaareacclimatedtothesiteandwillprovideoptimumconditionsforestablishinggrasses.Usecommerciallyavailablemycorrhizaproductswhenusingoff-sitetopsoil.DesignandMeetthefollowingrequirementsforareasrequiringdisruptionandInstallationtopsoiling:Specffications•Maximizethedepthofthetopsoilwhereverpossibletoprovidethemaximumpossibleinfiltrationcapacityandbeneficialgrowthmedium.Topsoilshallhave:Aminimumdepthof8-inches.Scarifysubsoilsbelowthetopsoillayeratleast4-incheswithsomeincorporationoftheuppermaterialtoavoidstratifiedlayers,wherefeasible.Rippingorrestructuringthesubgrademayalsoprovideadditionalbenefitsregardingtheoverallinfiltrationandintcrflowdynamicsofthcsoilsystem.ohiiiit’Co,zs/muc/jo,,S!ornnt’a/e,PoihilionPieen/ioniius!20122 •Aminimumorganiccontentof10%dry’weight.and5%organicmattercontentinturfareas.Incorporateorganicamendmentstoaminimum8-inchdepthexceptwheretreerootsorothernaturalfeatureslimitthedepthofincorporation.•ApHbetween6.0and8.0ormatchingthepHoftheundisturbedsoil.•Ifblendedtopsoilisimported,thenfinesshouldbelimitedto25percentpassingthrougha200sieve.AccomplishtherequiredorganiccontentandpETbyeitherreturningnativetopsoiltothesiteand/orincorporatingorganicamendments.•Tomeettheorganiccontentusecompostthatmeetsthedefinitionof”compostedmaterials”in\VAC173-350-220.Thiscodeisavailableonlineat:http://apps.len.wa.ov/WAC/default.aspx?cite=173-350-220.Thecompostmustalsohaveanorganicmattercontentof35%to65%,andacarbontonitrogenratiobelow25H:IV.Thecarbontonitrogenratiomaybeashighas35H:IVforplantingscomposedentirelyofplantsnativetothePugetSoundLowlandsregion.•Fortillsoilsuseamixtureofapproximatelytwopartssoiltoonepartcompost.Thisequatesto4inchesofcompostmixedtoadepthof12inchesintiltsoils.Increasingtheconcentrationofcompostbeyondthislevelcanhavenegativeeffectsonvegetalhealth,whiledecreasingtheconcentrationscanreducethebenefitsofamendedsoils.•Gravelorcobbleoutwashsoils,mayrequiredifferentapproaches.Organicsandfineseasilymigratethroughtheloosestructureofthesesoils.Therefore,theimportationofatleast6inchesofqualitytopsoil,underlainbysometypeoffilterfabrictopreventthemigrationoffines,maybemoreappropriateforthesesoils.•Thefinalcompositionandconstructionofthesoilsystemwillresultinanaturalselectionorfavoringofcertainplantspeciesovertime.Forexample,incorporationoftopsoilmayfavorgrasses,whilelayeringwithmildlyacidic,high-carbonamendmentsmayfavormorewoodyvegctation.•Allowsufficienttimeinschedulingfortopsoilspreadingpriortoseeding,sodding,orplanting.•Takecarewhenapplyingtopsoiltosubsoilswithcontrastingtextures.Sandytopsoiloverclayeysubsoilisaparticularlypoorcombination,aswatercreepsalongthcjunctionbetweenthesoillayersandcausesthetopsoiltoslough.Iftopsoilandsubsoilarenotproperlybonded,waterwillnotinfiltratethesoilprofileevenlyanditwillbedifficulttoolunwCons/nicIlo;,&onnil’a!erPollutlo,,Preen!ioniius!2012U establishvegetation.Thebestmethodtopreventalackofbondingistoactuallyworkthetopsoilintothelayerbelowforadepthofatleast6inches.Fieldexplorationofthesheshallbemadetodetermineifthereissurfacesoilofsufficientquantityandqualitytojustifystripping.Topsoilshallbefriableandloamy(loam,sandyloam,siltloam,sandyclayloam,andclayloam).Avoidareasofnaturalgroundwaterrecharge.•Strippingshallbeconfinedtotheimmediateconstructionarea.A4-inchto6-inchstrippingdepthiscommon,butdepthmayvarydependingontheparticularsoil.Allsurfacerunoffcontrolstructuresshallbeinplacepriortostripping.•Donotplacetopsoilwhileinafrozenormuddycondition,whenthesubgradeisexcessivelywet,orwhenconditionsexistthatmayotherwisebedetrimentaltopropergradingorproposedsoddingorseeding.•Inanyareasrequiringgradingremoveandstockpilethedufflayerandtopsoilonsiteinadesignated,controlledarea,notadjacenttopublicresourcesandcriticalareas.Stockpiledtopsoilistobereappliedtootherportionsofthesitewherefeasible.•Locatethetopsoilstockpilesothatitmeetsspecificationsanddoesnotinterferewithworkonthesite.ftmaybepossibletolocatemorethanonepileinproximitytoareaswheretopsoilwillbeused.Stockpilingoftopsoilshalloccurinthefollowingmanner:•Sideslopesofthestockpileshallnotexceed2H:JV.•BetweenOctober1andApril30:•Aninterceptordikewithgraveloutletandsiltfenceshallsurroundalltopsoil.•Within2dayscompleteerosioncontrolseeding,orcoveringstockpileswithclearplastic,orothermulchingmaterials.•BetweenMayIandSeptember30:•Aninterceptordikewithgraveloutletandsiltfenceshallsurroundalltopsoilifthestockpilewillremaininplaceforalongerperiodoftimethanactiveconstructiongrading.•Within7dayscomplctccrosioncontrolsccding,orcoveringstockpileswithclearplastic,orothermulchingmaterials.Whennativetopsoilistobestockpiledandreusedthefollowingshouldapplytoensurethatthencorrhizalbacterial,earthworms,andotherbeneficialorganismswillnotbedestroyed:I.Re-installtopsoilwithin4to6weeks.oluineConstructionStornni’aterPollutionPieentioniius!2012I •2.Donotallowthesaturationoftopsoilwithwater.3.Donotuseplasticcovering.Maintenaitce.Inspectstockpilesregularly,especiallyafterlargestormevents.StandardsStabilizeanyareasthathaveeroded.•Establishsoilqualityanddepthtowardtheendofconstructionandonceestablished,protectfromcompaction.suchasfromlargemachineryuse,andfromerosion.•Plantandmulchsoilafterinstallation.•Leaveplantdebrisoritsequivalentonthesoilsurfacetoreplenishorganicmatter.•Reduceandadjust,wherepossible,theuseofirrigation,fertilizers,herbicidesandpesticides,ratherthancontinuingtoimplementformerlyestablishedpractices.BMPC126:Polyacrylamide(PAM)forSoilErosionProtectionPurposePolyacrylamide(PAM)isusedonconstructionsitestopreventsoilerosion.ApplyingPAMtobaresoilinadvanceofaraineventsignificantlyreduceserosionandcontrolssedimentintwoways.First,PAMincreasesthesoil’savailableporevolume,thusincreasinginfiltrationthroughflocculationandreducingthequantityofstormwaterrunoff.Second,itincreasesflocculationofsuspendedparticlesandaidsintheirdeposition,thusreducingstomwvaterrunoffturbidityandimprovingwaterquality.ConditionsofUsePAMshallnotbedirectlyappliedtowaterorallowedtoenterawaterbody.Inareasthatdraintoasedimentpond,PAMcanbeappliedtobaresoilunderthefollowingconditions:•Duringroughgradingoperations.•InStagingareas.•Balancedcutandfillearthwork.•Haulroadspriortoplaccmcntofcrushedrocksurfacing.•Compactedsoilroadbase.•Stockpiles.•Afterfinalgradeandbeforepavingorfinalseedingandplanting.•Pitsites.ohuneConstructionStonnwaterPollutionPieentionitus!2012 •Siteshavingawintershutdown.Inthecaseofwintershutdown,orwheresoilwillremainunworkedforseveralmonths.PAMshouldbeusedtogetherwithmulch.PAMmaybeappliedwithwaterindissolvedform.ThepreferredDesignand.applicationmethodisthedissolvedform.InstallationSpecjficationsPAMistobeappliedatamaximumrateof2/3poundPAMper1,000gallonswater(80mg/L)perIacreofbaresoil.Table4.1.9canbeusedtodeterminethePAMandwaterapplicationrateforadisturbedsoilarea.HigherconcentrationsofPAMdonoprovideanyadditionaleffectiveness.Table4.1.9PAMandWaterApplicationRatesDirdAra(a)PAM(1War(al0.500.33500I.000.66I,0001.50I.001,5002.001.322,0002.50I.652,5003.002.003,0003.502.333,5004.002.654,0004.503.004,5005.003.335.000ThePreferredMethod:•Pre-measuretheareawherePAMistobeappliedandcalculatetheamountofproductandwaternecessarytoprovidecoverageatthespecifiedapplicationrate(2/3poundPAM/I000gallons/acre).•PAMhasinfinitesolubilityinwater,butdissolvesveryslowly.Dissolvepre-measureddrygranularPAMwithaknownquantityofcleanwaterinabucketseveralhoursorovernight.MechanicalmixingwillhelpdissolvethePAM.AlwaysaddPAMtowater-notwatertoPAM.•Pre—fillthewatertruckabout1/8fillwithwater.Thewaterdoesnothavetobepotable,butitmusthaverelativelylowturbidity—intherangeof20NTUorless.•AddPAM/Watermixturetothetruck•Completelyfillthewatertrucktospecifiedvolume.•SprayPAM/Watermixtureontodrysoiluntilthesoilsurfaceisuniformlyandcompletelywetted.AmAlternateMethod:ohilneConstructionS/onnwa/crPollutionPvc’cm/ioniius!2012 PAMmayalsobeappliedasapowderattherateof5lbs.peracre.Thismustbeappliedonadaythatisdry’.Forareaslessthan5-10acres,ahand-held“organgrinder”fertilizerspreadersettothesmallestsettingwillwork.Tractor-mountedspreaderswillworkforlargerareas.ThefollowingshallbeusedforapplicationofpowderedPAM:•PoweredPAMshallbeusedinconjunctionwithotherBMPsandnotinplaceofotherBMPs.•DonotusePAMonaslopethatflowsdirectlyintoastreamorwetland.ThestormwaterrunoffshallpassthroughasedimentcontrolBMPpriortodischargingtosurfacewaters.•DonotaddPAMtowaterdischargingfromsite.•Whenthetotaldrainageareaisgreaterthanorequalto5acres,PAMtreatedareasshalldraintoasedimentpond.•Areaslessthan5acresshalldraintosedimentcontrolBMPs,suchasaminimumof3checkdamsperacre.Thetotalnumberofcheckdamsusedshallbemaximizedtoachievethegreatestamountofsettlementofsedimentpriortodischargingfromthesite.Eachcheckdamshallbespacedevenlyinthedrainagechannelthroughwhichstormwaterflowsaredischargedoff-site.•Onallsites,theuseofsiltfenceshallbemaximizedtolimitthedischargesofsedimentfromthesite.•Allareasnotbeingactivelyworkedshallbecoveredandprotectedfromrainfall.PAMshallnotbetheonlycoverBMPused.•PAMcanbeappliedtowetsoil,butdrysoilispreferredduetolesssedimentloss.•PAMwillworkwhenappliedtosaturatedsoilbutisnotaseffectiveasapplicationstodryordampsoil.•KeepthegranularPAMsupplyoutofthesun.GranularPAMlosesitseffectivenessinthreemonthsafterexposuretosunlightandair.•Properapplicationandre-applicationplansarcnecessarytoensuretotaleffectivenessofPAMusage.•PAM.combinedwithwater,isyen’slipperyandcanbeasafetyhazard.CaremustbetakentopreventspillsofPAMpowderontopavedsurfaces.DuringanapplicationofPAM,preventover-sprayfromreachingpavementaspavementwillbecomeslippery.IfPAMpowdergetsonskinorclothing,wipeitoffwitharoughtowelratherthanwashingwithwater-thisonlymakescleanupmessierandtakelonger.•SomePAMsaremoretoxicandcarcinogenicthanothers.OnlythemostenvironmentallysafePAMproductsshouldbeused.ohiiiieConstructionStornurcuerPollutionfireeu/ionuus!2012 ThespecificPAMcopolymerformulationmustbeanionic.CaioniPAManodinanaiaionaofnonaa1oIIroOnlythehighestdrinkingwatergradePAM,certifiedforcompliancewithANSI/NSFStandard60fordrinkingwatertreatment.vilIbeusedforsoilapplications.RecentmediaattentionandhighinterestinPAMhasresultedinsomeentrepreneurialexploitationoftheterm“polynwr“AllPAMarepolymers,butnotallpolymersarePAM,andnotallPAMproductscomplywithANSI/NSFStandard60.PAMuseshallbereviewedandapprovedbythelocalpermittingauthority.PAMdesignatedfortheseusesshouldbe“watersoluble”or“linearor“non-crosslinked”.Cross-linkedorwaterabsorbentPAM,polymerizedinhighlyacidic(p1-1<2)conditions,areusedtomaintainsoilmoisturecontent.ThePAManionicchargedensitymayvaryfrom2-30percent;avalueof18percentistypical.StudiesconductedbytheUnitedStatesDepartmentofAgriculture(USDA)/ARSdemonstratedthatsoilstabilizationwasoptimizedbyusingveryhighmolecularweight(12-15mg/mole),highlyanionic(>20%hydrolysis)PAM.•PAMtackifiersareavailableandbeingusedinplaceofguarandalphaplantago.Typically,PAMtackifiersshouldbeusedatarateofnomorethan0.5-1lb.per1000gallonsofwaterinahydromulehmachine.Sometackifierproductinstructionssaytouseatarateof3—5lbs.peracre,whichcanbetoomuch.Inaddition,pumpproblemscanoccurathigherratesduetoincreasedviscosity.Mai,,tenjuice•PAMmaybereappliedonactivelyworkedareasaftera48-hourStandardsperiod.•ReapplicationisnotrequiredunlessPAMtreatedsoilisdisturbedorunlessturbiditylevelsshowtheneedforanadditionalapplication.IfPAMtreatedsoilisleftundisturbedareapplicationmaybenecessaryaftertwomonths.MorePAMapplicationsmayberequiredforsteepslopes,siltyandclayeysoils(USDAClassificationType“C’and“D”soils).longgrades,andhighprecipitationareas.WhenPAMisappliedfirsttobaresoilandthencoveredwithstraw,areapplicationmaynotbenecessaryforseveralmonths.•LossofsedimentandPAMmaybeabasisforpenaltiesperRCW90.48.080.BMPC130:SurfaceRougheningPurposeSurfacerougheningaidsintheestablishmentofvegetativecover,reducesrunoffvelocity,increasesinfiltration,andprovidesforsedimenttrappingthroughtheprovisionofaroughsoilsurface.HorizontaldepressionsareohuncCons!rue/ionS/ornn’a/erPollutionPrecut/oniius!2012 createdbyoperatingatillerorothersuitableequipmentonthecontourorbyleavingslopesinaroughenedconditionbynotfinegradingthem.UsethisBMPinconjunctionwithotherBMPssuchasseeding.mulching,orsodding.Corn!itionsfor.Allslopessteeperthan3H:IVandgreaterthan5verticalfeetUserequiresurfacerougheningtoadepthof2to4inchespriortoseeding..•Areasthatwillnotbestabilizedimmediatelymayberoughenedtoreducerunoffvelocityuntilseedingtakesplace.•Slopeswithastablerockfacedonotrequireroughening.•Slopeswheremowingisplannedshouldnotbeexcessivelyroughened.DesignandTherearedifferentmethodsforachievingaroughenedsoilsurfaceonaInsta!!ationslope,andtheselectionofanappropriatemethoddependsuponihetypeofSpecjflcationsslope.Rougheningmethodsincludestair-stepgrading,grooving,contourffirrows,andtracking.SeeFiuure4.1.5fortrackingandcontourfurrows.Factorstobeconsideredinchoosingamethodareslopesteepness,mowingrequirements,andwhethertheslopeisformedbycuttingorfilling.•Disturbedareasthatwillnotrequiremowingmaybestair-stepgraded,grooved,orleftroughafterfilling.•Stair-stepgradingisparticularlyappropriateinsoilscontaininglargeamountsofsoftrock.Each“step’catchesmaterialthatsloughsfromabove,andprovidesalevelsitewherevegetationcanbecomeestablished.Stairsshouldbewideenoughtoworkwithstandardearthmovingequipment.Stairstepsmustbeoncontourorgullieswillformontheslope.•Areasthatwillbemowed(theseareasshouldhaveslopeslesssteepthan3H:IV)mayhavesmallfurrowsleftbydisking,harrowing,raking,orseed-plantingmachineryoperatedonthecontour.•Gradedareaswithslopessteeperthan3H:IVbutlessthan2H:IVshouldberoughenedbeforeseeding.Thiscanbeaccomplishedinavarietyofways.including‘trackwalking,’ordrivingacrawlertractorupanddowntheslope,leavingapatternofcleatimprintsparalleltoslopecontours.•TrackingisdonebyoperatingequipmentupanddowntheslopetoIcavehorizontaldepressionsinthesoil.Maintenance•AreasthataregradedinthismannershouldbeseededasquicklyasStandardspossible.•Regularinspectionsshouldbemadeofthearea.Ifrillsappear,theyshouldbere-gradedandre-seededimmediately.ohinwConstructionStorunraterPollutionPreentionitust2012 Trackingaa_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-aaaaaaaaaaaaaaa_aaaaaaaaContourFurrowsTRACKING’withmachineryupanddowntheslopeprovidesgroovesthatwillcatchseed,raInfallandreducerunoff.50’(150mm)Madmum1GroovesWillCatchSeed,Fertilizer,Mulch,RainfallandDecreaseRunoff.Figure4.1.5—SurfaceRougheningbyTrackingandContourFurrowsolinneConstrue/to,,S!onnii’a!erPollutionPit’en/iouiius!2012 BMPC131:GradientTerracesPurposeGradientterracesreduceerosiondamagebyinterceptingsurfacerunoffandconductingittoastableoutletatanon-erosivevelocity.C’o,,ditionsofUse•Gradientterracesnormallyarelimitedtodenudedlandhavingawatererosionproblem.Theyshouldnotbeconstructedondeepsandsoronsoilsthataretoostony,steep,orshallowtopermitpracticalandeconomicalinstallationandmaintenance.Gradientterracesmaybeusedonlywheresuitableoutletsareorwillbemadeavailable.SeeFigure4.1.6forgradientterraces.Designand•ThemaximumverticalspacingofgradientterracesshouldbeInstallationdeterminedbythefollowingmethod:Specj/lcationsVI(O.8)s+yWhere:VI=verticalintervalinfeets=landriseper100feet,expressedinfeety=asoilandcovervariablewithvaluesfrom1.0to4.0Valuesof”y”areinfluencedbysoilerodibilityandcoverpractices.Thelowervaluesareapplicabletoerosivesoilswherelittletonoresidueisleftonthesurface.Thehighervalueisapplicableonlytoerosion-resistantsoilswherealargeamountofresidue(1¼tonsofstraw/acreequivalent)isonthesurface.•Theminimumconstructedcross-sectionshouldmeetthedesigndimensions.•Thetopoftheconstructedridgeshouldnotbeloweratanypointthanthedesignelevationplusthespecifiedoverfillforsettlement.Theopeningattheoutletendoftheterraceshouldhaveacrosssectionequaltothatspecifiedfortheterracechannel.•Channelgradesmaybeeitheruniformorvariablewithamaximumgradeof0.6feetper100feetlength(0.6%).Forshortdistances,terracegradcsmaybeincrcascdtoimprovealignment.Thechannelvelocityshouldnotexceedthatwhichisnonerosiveforthesoiltype.•Allgradientterracesshouldhaveadequateoutlets.Suchanoutletmaybeagrassedwaterway,vegetatedarea,ortileoutlet.Inallcasestheoutletmustconveyrunofffromtheterraceorterracesystemtoapointwhcrctheoutflowwillnotcauscdamage.Vegetativecovershouldbeusedintheoutletchannel.•Thedesignelevationofthewatersurfaceoftheterraceshouldnotbelowerthanthedesignelevationofthewatersurfaceintheoutletattheirjunction,whenbothareoperatingatdesignflow.ohimeConstructionStonnwa/erPollutionPieen/ioniius!2012 •Verticalspacingdeterminedbytheabovemethodsmaybeincreasedasmuchas0.5feetor10percent,whicheverisgreater,toprovidebetteralignmentorlocation,toavoidobstacles,toadjustforequipmentsize,ortoreachasatisfactoryoutlet.Thedrainageareaabovetheterraceshouldnotexceedtheareathatwouldbedrainedbyaterracewithnormalspacing.•Theterraceshouldhaveenoughcapacitytohandlethepeakrunoffexpectedfroma2-year,24-hourdesignstormwithoutovertopping.•Theterracecross-sectionshouldbeproportionedtofitthelandslope.Theridgeheightshouldincludeareasonablesettlementfactor.Theridgeshouldhaveaminimumtopwidthof3feetatthedesignheight.Theminimumcross-sectionalareaoftheterracechannelshouldbeSsquarefeetforlandslopesof5percentorless,7squarefeetforslopesfrom5to8percent,and6squarefeetforslopessteeperthan8percent.Theterracecanbeconstructedwideenoughtobemaintainedusingasmallvehicle.Mahztena,,ce•Maintenanceshouldbeperformedasneeded.TerracesshouldbeStandardsinspectedregularly;atleastonceayear,andafterlargestormevents.Slopetoadequate10mm.Figure4.1.6—GradientTerracesobtineConstructionSIonnwaterPollutionPreeu/ionitust2012 BMPC140:DustControlPurposeDustcontrolpreventswindtransportofdustfromdisturbedsoilsurfacesontoroadways.drainageways.andsurfacewaters.conditionsofUse•Inareas(includingroadways)subjecttosurfaceandairmovementofdustwhereon-siteandoff-siteimpactstoroadways,drainageways,orsurfacewatersarelikely.Designand.Vegetateormulchareasthatwillnotreceivevehicletraffic.InareasInstallationwhereplanting,mulching,orpavingisimpractical,applygravelorSpecicationslandscapingrock.•Limitdustgenerationbyclearingonlythoseareaswhereimmediateactivitywilltakeplace,leavingtheremainingarea(s)intheoriginalcondition.Maintaintheoriginalgroundcoveraslongaspractical.•Constructnaturalorartificialwindbreaksorwindscreens.Thesemaybedesignedasenclosuresforsmalldustsources.•Sprinklethesitewithwateruntilsurfaceiswet.Repeatasneeded.Topreventcarryoutofmudontostreet.refertoStabilizedConstructionEntrance(BMPCl05).•Irrigationwatercanbeusedfordustcontrol.Irrigationsystemsshouldbeinstalledasafirststeponsiteswheredustcontrolisaconcern.•Sprayexposedsoilareaswithadustpalliative,followingthemanufacturer’sinstructionsandcautionsregardinghandlingandapplication.Usedoilisprohibitedfromuseasadustsuppressant.LocalgovernmentsmayapproveotherdustpalliativessuchascalciumchlorideorPAM.•PAM(BMPCl26)addedtowateratarateof0.5lbs.per1,000gallonsofwaterperacreandappliedfromawatertruckismoreeffectivethanwateralone.Thisisduetoincreasedinfiltrationofwaterintothesoilandreducedevaporation.Inaddition,smallsoilparticlesarebondedtogetherandarenotaseasilytransportedbywind.AddingPAMmayactuallyreducethequantityofwaterneededfordustcontrol.UseofPAMcouldbeacost-effectivedustcontrolmethod.Techniquesthatcanbeusedforunpavedroadsandlotsinclude:•Lowerspeedlimits.Highvehiclespeedincreasestheamountofduststirredupfromunpavedroadsandlots.•Upgradctheroadsurfacestrcngthbyimprovingparticlesize,shapc.andmineraltypesthatmakeupthesurfaceandbasematerials.•Addsurfacegraveltoreducethesourceofdustemission.Limittheamountoffineparticles(thosesmallerthan.075mm)to10to20percent.oltimeCons/nec/ionStonni’uterPollutionPieen/ioniius!20120 •Usegeotextilefabricstoincreasethestrengthofnewroadsorroadsundergoingreconstruction.•Encouragetheuseofalternate,pavedroutes,ifavailable.•Restrictuseofpavedroadwaysbytrackedvehiclesandheavytruckstopreventdamagetoroadsurfaceandbase.•Applychemicaldustsuppressantsusingtheadmixmethod,blendingtheproductwiththetopfewinchesofsurfacematerial.Suppressantsmayalsobeappliedassurfacetreatments.•Paveunpavedpermanentroadsandothertraffickedareas.•Usevacuumstreetsweepers.•Removemudandotherdirtpromptlysoitdoesnotdryandthenturnintodust.•Limitdust-causingworkonwindydays.•ContactyourlocalAirPollutionControlAuthorityforguidanceandtrainingonotherdustcontrolmeasures.CompliancewiththelocalAirPollutionControlAuthorityconstitutescompliancewiththisBMP.MaintenanceResprayareaasnecessarytokeepdusttoaminimum.StandardsBMPCISO:MaterialsonHandPurposeKeepquantitiesoferosionpreventionandsedimentcontrolmaterialsontheprojectsiteatalltimestobeusedforregularmaintenanceandemergencysituationssuchasunexpectedheavysummerrains.Havingthesematerialson-sitereducesthetimeneededtoimplementBMPswheninspectionsindicatethatexistingBMPsarenotmeetingtheConstructionSWPPPrequirements.Inaddition,contractorscansavemoneybybuyingsomematerialsinbulkandstoringthemattheirofficeoryard.C’o,,ditio,,sofUse•Constructionprojectsofanysizeortypecanbenefitfromhavingmaterialsonhand.Asmallcommercialdevelopmentprojectcouldhavearollofplasticandsomegravelavailableforimmediateprotectionofbaresoilandtemporarybermconstruction.Alargeearthworkproject,suchashighwayconstruction,mighthaveseveraltonsofstraw,severalrollsofplastic,flexiblepipe,sandbags,geotextilefabricandsteel“T”posts.•Materialsarestockpiledandreadilyavailablebeforeanysiteclearing,grubbing,orearthworkbegins.Alargecontractorordevelopercouldkeepastockpileofmaterialsthatareavailableforuseonseveralprojects.•Tfstoragespaceattheprojectsiteisatapremium,thecontractorcouldmaintainthematerialsattheirofficeoryard.Theofficeoryardmustbelessthananhourfromtheprojectsite.ohi;neConstructionStornni’atcrPollutionPreentioniiust2012I DesignandDependingonprojecttype,size,complexity,andlength,materialsandInstallationquantitieswillvary.AgoodminimumlistofitemsthatwillcoverSpecjficationsnumeroussituationsincludes:MaterialClearPlastic,6milDrainpipe,6or8inchdiameterSand b a g s ,filled___ _ ___ ___ ___ _ ___ __StrawBalesformulching,QuarrySpallsWashedGravelGeotextileFabricCatchBasinInsertsSteel‘7”PostsSiltfencematerialStrawWattlesMaintenance•Allmaterialswiththeexceptionofthequarryspalls,steel“I”posts,Standardsandgravelshouldbekeptcoveredandoutofbothsunandrain.•Re-stockmaterialsusedasneeded.BMPCISI:ConcreteHandlingPurposeConcreteworkcangenerateprocesswaterandslurrythatcontainfineparticlesandhighpH,bothofwhichcanviolatewaterqualitystandardsinthereceivingwater.ConcretespillageorconcretedischargetosurfacewatersoftheStateisprohibited.UsethisBMPtominimizeandeliminateconcrete,concreteprocesswater,andconcreteslurryfromenteringwatersofthestate.ConditionsofUseAnytimeconcreteisused,utilizethesemanagementpractices.Concreteconstructionprojectsinclude,butarenotlimitedto,thefollowing:•Curbs•Sidewalks•Roads•Bridges•Foundations•Floors•RunwaysDesignand•Washoutconcretetruckchutes,pumps,andinternalsintoformedInstallationareasonly.AssurethatwashoutofconcretetrucksisperformedoffchimeConstructionStonuwaterPollutionPieentioniius!20)22 Specjficationssiteorindesignatedconcretewashoutareas.Donotwashoutconcretetrucksontotheground,orintostormdrains,openditches,streets,orstreams.RefertoBMPC154forinformationonconcretewashoutareas.•Returnunusedconcreteremaininginthetruckandpumptotheoriginatingbatchplantforrecycling.Donotdumpexcessconcreteonsite,exceptindesignatedconcretewashoutareas.•Washoffhandtoolsincluding,butnotlimitedto,screeds,shovels,rakes,floats,andtrowelsintoformedareasonly.•Washequipmentdifficulttomove,suchasconcretepayersinareasthatdonotdirectlydraintonaturalorconstructedstormwaterconveyances.•Donotallowwashdownfromareas,suchasconcreteaggregatedriveways,todraindirectlytonaturalorconstructedstormwaterconveyances.•Containwashwaterandleftoverproductinalinedcontainerwhennoformedareasareavailable,.Disposeofcontainedconcreteinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.•Alwaysuseformsorsolidbarriersforconcretepours,suchaspilings,within15-feetofsurfacewaters.•RefertoBMPsC252andC253forpHadjustmentrequirements.•RefertotheConstructionStormwaterGeneralPermitforpHmonitoringrequirementsiftheprojectinvolvesoneofthefollowingactivities:•Significantconcretework(greaterthan1,000cubicyardspouredconcreteorrecycledconcreteusedoverthelifeofaproject).•Theuseofengineeredsoilsamendedwith(butnotlimitedto)Portlandcement-treatedbase,cementkilndustorflyash.•Dischargingstormwatertosegmentsofwaterbodiesonthe303(d)list(Category5)forhighpH.MaintenanceCheckcontainersforholesinthelinerdailyduringconcretepoursandStandardsrepairthesameday.obtineConstructionStornni’aterPollullo,,Pieentionuus!2012 BMPC152:SawcuttingandSurfacingPollutionPreventionPurposeSawcuttingandsurfacingoperationsgenerateslurryandprocesswaterthatcontainsfineparticlesandhighpH(concretecutting),bothofwhichcanviolatethewaterqualitystandardsinthereceivingwater.ConcretespillageorconcretedischargetosurfacewatersoftheStateisprohibited.UsethisBMPtominimizeandeliminateprocesswaterandslurrycreatedthroughsawcuttingorsurfacingfromenteringwatersoftheSlate.C’onditio,zsofUseUtilizethesemanagementpracticesanytimesawcuttingorsurfacingoperationstakeplace.Sawcuttingandsurfacingoperationsinclude,butarenotlimitedto,(liefollowing:•Sawing•Coring•Grinding•Roughening•Hydro-demolition•BridgeandroadsurfacingDesignand•Vacuumslurryandcuttingsduringcuttingandsurfacingoperations.Installation•SlurryandcuttingsshallnotremainonpermanentconcreteorasphaltSpec(flcationspavementovernight.•Slurryandcuttingsshallnotdraintoanynaturalorconstructeddrainageconveyanceincludingstornnvatersystems.Thismayrequiretemporarilyblockingcatchbasins.•Disposeofcollectedslurryandcuttingsinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.•Donotallowprocesswatergeneratedduringhydro-demohition,surfacerougheningorsimilaroperationstodraintoanynaturalorconstructeddrainageconveyanceincludingstormwatersystems.Disposeprocesswaterinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.•Handleanddisposecleaningwastematerialanddemolitiondebrisinamannerthatdoesnotcausecontaminationofwater.Disposeofsweepingmaterialfromapick-upsweeperatanappropriatedisposalsite.Mainte,,a,,ceContinuallymonitoroperationstodeterminewhetherslurry,cuttings,orStandardsprocesswatercouldenterwatersofthestate.Ifinspectionsshowthataviolationofwaterquali’standardscouldoccur,stopoperationsandimmediatelyimplementpreventivemeasuressuchasberms,barriers,secondarycontainment,andvacuumtrucks.ohmicCons/rue/jot;S/ornni’a/erPollulionPieen/ionitus!2012 BMPC153:MaterialDelivery,StorageandContainmentPurposePrevent,reduce,oreliminatethedischargeofpollutantstothestormwatersystemorwatercoursesfrommaterialdeliveryandstorage.Minimizethestorageofhazardousmaterialson-site,storematerialsinadesignatedarea,andinstallsecondarycontainment.conditionsofUseTrodrarIaforaaonrionidIrandoraoffooinana•Petroleumproductssuchasfuel,oilandgrease•Soilstabilizersandbinders(e.g.Polyacrylamide)•Fertilizers,pesticidesandherbicides•Detergents•Asphaltandconcretecompounds•1-lazardouschemicalssuchasacids,lime,adhesives,paints,solventsandcuringcompounds•AnyothermaterialthatmaybedetrimentalifreleasedtotheenvironmentDesignandTfooinodanomiIiiI,,stallatwn•Temporarystorageareashouldbelocatedawayfromvehiculartraffic,Specificationsneartheconstructionentrance(s),andawayfromwaterwaysorstormdrains.•MaterialSafetyDataSheets(MSDS)shouldbesuppliedforallmaterialsstored.Chemicalsshouldbekeptintheiroriginallabeledcontainers.•Hazardousmaterialstorageon-siteshouldbeminimized.•Hazardousmaterialsshouldbehandledasinfrequentlyaspossible.•Duringthewetweatherseason(Oct1—April30).considerstoringmaterialsinacoveredarea.•Materialsshouldbestoredinsecondarycontainments,suchasearthendike,horsetrough,orevenachildren’swadingpooifornon-reactivematerialssuchasdetergents,oil,grease,andpaints.Smallamountsofmaterialmaybesecondarilycontainedin“busboy”traysorconcretemixingtrays.•Donotstorechemicals,drums,orbaggedmaterialsdirectlyontheground.Placetheseitemsonapalletand,whenpossible,andwithinsecondary’containment.•Ifdrumsmustbekeptuncovered,storethemataslightangletoreducepondingofrainwateronthelidstoreducecorrosion.Domedplasticcoversareinexpensiveandsnaptothetopofdrums,preventingwaterfromcollecting.ohuneConstructionStornnraterPollutionPreentionuus!2012 ManaSeraAraandSondarConamnPraILiquids.petroleumproducts,andsubstanceslistedin40CFRParts110,117,or302shallbestoredinapprovedcontainersanddrumsandshallnotbeoverfilled.Containersanddrumsshallbestoredintemporarysecondarycontainmentfacilities.•Temporarysecondarycontainmentfacilitiesshallprovideforaspillcontainmentvolumeabletocontain10%ofthetotalenclosedcontainervolumeofallcontainers,or110%ofthecapacityofthelargcstcontainerwithinitsboundary,whicheverisgrcatcr.•Secondarycontainmentfacilitiesshallbeimpervioustothematerialsstorcdthereinforaminimumcontacttimeof72hours.•Secondarycontainmentfacilitiesshallbemaintainedfreeofaccumulatedrainwaterandspills.Intheeventofspillsorleaks,accumulatedrainwaterandspillsshallbecollectedandplacedintodrums.Theseliquidsshallbehandledashazardouswasteunlesstestingdeterminesthemtobenon-hazardous.•Sufficientseparationshouldbeprovidedbetweenstoredcontainerstoallowforspillcleanupandemergencyresponseaccess.•Duringthewetweatherseason(Oct1—April30),eachsecondarycontainmentfacilityshallbecoveredduringnon-workingdays,priortoandduringrainevents.•Keepmaterialstorageareasclean,organizedandequippedwithanamplesupplyofappropriatespillclean-upmaterial(spillkit).•Thespillkitshouldinclude,ataminimuni:•1-WaterResistantNylonBag•3-OilAbsorbentSocks3”x4’•2-OilAbsorbentSocks3”x10’•12-OilAbsorbentPadsI7”xl9”•1-PairSplashResistantGoggles•3-PairNitrileGloves•10-DisposableBagswithTies•InstructionsohmicConstructionSto,mu’atc;PollutionPreentioniiust20)2 BMPCl54:ConcreteWashoutAreaPurposePreventorreducethedischargeofpollutantstostormwaterfromconcretewastebyconductingwashoutoff-site,orperformingon-sitewashoutinadesignatedareatopreventpollutantsfromenteringsurfacewatersorgroundwater.(‘auditionsofUseConcretewashoutareabestmanagementpracticesareimplementedonconstructionprojectswhere:•Concreteisusedasaconstructionmaterial•Itisnotpossibletodisposeofallconcretewastewaterandwashoutoff-site(readymixplant,etc.).•Concretetrucks,pumpers,orotherconcretecoatedequipmentarewashedon-site.•Note:Iflessthan10concretetrucksorpumpersneedtobewashedouton-site,thewashwatermaybedisposedofinaformedareaawaitingconcreteoranuplanddisposalsitewhereitwillnotcontaminatesurfaceorgroundwater.Theuplanddisposalsiteshallbeatleast50feetfromsensitiveareassuchasstormdrains,openditches,orwaterbodies,includingwetlands.DesignandInaionInstallationThefollowingstepswillhelpreducestormwaterpollutionfromconcreteSpecificationswastes:•Performwashoutofconcretetrucksoff-siteorindesignatedconcretewashoutareasonly.•Donotwashoutconcretetrucksontotheground,orintostormdrains,openditches,streets,orstreams.•Donotallowexcessconcretetobedumpedon-site,exceptindesignatedconcretewashoutareas.•Concretewashoutareasmaybeprefabricatedconcretewashoutcontainers,orself-insEalledstructures(above-gradeorbelow-grade).•Prefabricatedcontaincrsarcmostresistanttodamagcandprotectagainstspillsandleaks.Companiesmayofferdeliveryserviceandprovideregularmaintenanceanddisposalofsolidandliquidwaste.•Ifself-installedconcretewashoutareasareused,below-gradestructuresarepreferredoverabove-gradestructuresbecausetheyarelesspronetospillsandleaks.•Self-installedabove-gradestructuresshouldonlybeusedifexcavationisnotpracticaLobtineConstructionStor,uni’cwerPothilionPreen/ioniius!2012 Edaion•DiscusstheconcretemanagementtechniquesdescribedinthisBMPwiththeready-mixconcretesupplierbeforeanydeliveriesaremade.•EducateemployeesandsubcontractorsontheconcretewastemanagementtechniquesdescribedinthisBMP.•Arrangeforcontractor’ssuperintendentorCertifiedErosionandSedimentControlLead(CESCL)tooverseeandenforceconcretewastemanagementprocedures.•Asignshouldbeinstalledadjacenttoeachtemporaryconcretewashoutfacilitytoinformconcreteequipmentoperatorstoutilizetheproperfacilities.ConraIncorporaterequirementsforconcretewastemanagementintoconcretesupplierandsubcontractoragreements.LoaionandPan•Locatewashoutareaatleast50feetfromsensitiveareassuchasstormdrains,openditches,orwaterbodies,includingwetlands.•Allowconvenientaccessforconcretetrucks,preferablyneartheareawheretheconcreteisbeingpoured.•Iftrucksneedtoleaveapavedareatoaccesswashout,preventtrack-outwithapadofrockorquarryspalls(seeBMPC105).Theseareasshouldbefarenoughawayfromotherconstructiontraffictoreducethelikelihoodofaccidentaldamageandspills.•Thenumberoffacilitiesyouinstallshoulddependontheexpecteddemandforstoragecapacity.•Onlargesiteswithextensiveconcretework,washoutsshouldbeplacedinmultiplelocationsforeaseofusebyconcretetruckdrivers.On-iTorarConrWaoFail,TraniTrWaoProdr•Temporaryconcrctcwashoutfacilitiesshallbelocatedaminimumof50ftfromsensitiveareasincludingstormdraininlets,opendrainagefacilities,andwatercourscs.SeeFigures4.1.7and4.1.8.•Concretewashoutfacilitiesshallbeconstructedandmaintainedinsufficientquantityandsizetocontainallliquidandconcretewastegcneratcdbywashoutoperations.•Approximately7gallonsofwashwaterareusedtowashonetruckchute.•Approximately50gallonsareusedtowashoutthehopperofaconcretepumptruck.obtineCenisiritetionS/ou,;ni’aterPollutionfireen/ioniius!2012 •Washoutofconcretetrucksshallbeperformedindesignatedareasonly.•Concretewashoutfromconcretepumperbinscanbewashedintoconcretepumpertrucksanddischargedintodesignatedwashoutareaorproperlydisposedofoff-site.•Onceconcretewastesarewashedintothedesignatedareaandallowedtoharden.theconcreteshouldbebrokenup,removed,anddisposedofperapplicablesolidwasteregulations.Disposeofhardenedconcreteonaregularbasis.•TemporaryAbove-GradeConcreteWashoutFacility•Temporaryconcretewashoutfacility(typeabovegrade)shouldbeconstructedasshownonthedetailsbelow,witharecommendedminimumlengthandminimumwidthof10ft,butwithsufficientquantityandvolumetocontainallliquidandconcretewastegeneratedbywashoutoperations.•Plasticliningmaterialshouldbeaminimumof10milpolyethylenesheetingandshouldbefreeofholes,tears,orotherdefectsthatcompromisetheimpermeabilityofthematerial.•TemporaryBelow-GradeConcreteWashoutFacility•Temporaryconcretewashoutfacilities(typebelowgrade)shouldbeconstructedasshownonthedetailsbelow,witharecommendedminimumlengthandminimumwidthof10ft.Thequantityandvolumeshouldbesufficienttocontainallliquidandconcretewastegeneratedbywashoutoperations.•Lathandflaggingshouldbecommercialtype.•Plasticliningmaterialshallbeaminimumof10milpolyethylenesheetingandshouldbefreeofholes,tears,orotherdefectsthatcompromisetheimpermeabilityofthematerial.•Linerseamsshallbeinstalledinaccordancewithmanufacturers’recommendations.•Soilbaseshallbepreparedfreeofrocksorotherdebristhatmaycausetearsorholesintheplasticliningmaterial.MaintenanceInionandMainnanStandards•InspectandverifythatconcretewashoutBMPsareinplacepriortothecommencementofconcretework.•Durinaperiodsofconcretework.inspectdailytoverifycontinuedperformance.•Checkoverallconditionandperformance.•Checkremainingcapacity(%full).olumeConstructionStor,nwaterPollutionPieentionuus!2012 •Ifusingself-installedwashoutfacilities.veri&plasticlinersareintactandsidewallsarenotdamaged.•Ifusingprefabricatedcontainers,checkforleaks.•Washoutfacilitiesshallbemaintainedtoprovideadequateholdingcapacitywithaminimumfreeboardof12inches.•Washoutfacilitiesmustbecleaned,ornewfacilitiesmustbeconstructedandreadyforuseoncethewashoutis75%hill.•Ifthewashoutisnearingcapacity,vacuumanddisposeofthewastematerialinanapprovedmanner.•Donotdischargeliquidorslurrytowaterways,stormdrainsordirectlyontoground.•Donotusesanitary’sewerwithoutlocalapproval.•Placeasecure,non-collapsing,non-watercollectingcoverovertheconcretewashoutfacility’priortopredictedwetweathertopreventaccumulationandoverflowofprecipitation.•Removeanddisposeofhardenedconcreteandreturnthestructuretoafunctionalcondition.Concretemaybereusedon-siteorhauledawayfordisposalorrecycling.•Whenyouremovematerialsfromtheself-installedconcretewashout,buildanewstructure;or,ifthepreviousstructureisstillintact,inspectforsignsofweakeningordamage,andmakeanynecessaryrepairs.Re-linethestructurewithnewplasticaftereachcleaning.RoaofTorarConrWaoFaiii•Whentemporaryconcretewashoutfacilitiesarenolongerrequiredforthework.thehardenedconcrete,slurriesandliquidsshallberemovedandproperlydisposedof.•Materialsusedtoconstructtemporaryconcretewashoutfacilitiesshallberemovedfromthesiteoftheworkanddisposedoforrecycled.•Holes,depressionsorothergrounddisturbancecausedbytheremovalofthctcmporaryconcrctcwashoutfaciliticsshallbebackfillcd,repaired,andstabilizedtopreventerosion.oluineCons/rite/ionS/ormii’aterPollutionPreentionitus!20120 Figure4.1.7a—ConcreteWashoutAreaohnneConstructionSlornni’aterPollutionPreenilonuus!2012I10riftAStCIn,lATHMOrNGONJSIDESNnA-KNUT10SCAII10r,ptThD___UNOT10SCALEMIIIIUUU—LqO0DWAIlSSECUREDF*SIENEOLJAOUPAOENIIREPEPIMEICHN._WITHTWOSIMS‘STWO.5FACgO2.12POUCH—.rI000FRMAEVAS:/IDmITHIJICHNINCI.ACTUALLAYCHJTDCTtRUI%Cp...ThEflt._D,2.ThECO.CRCTCWASHOUT5GW(551PACEb)$nAttOrn.SIuIloMThA.ToInOrfl!IWPoTmLONCRnrWASHOUTrAcIur,HOTTOSCAUTnflADQVCGRACrWIThW000FW{KS atE5JA,ILS(2PRBALE)s00STARES(2ERBALE)•1vmics/SNCaWIRE7/-7Y61PtASlICUMNO///PeAT?,tLLAWRLt/(OrIOML)n.-r(40110SCALEPLYA000-I200ow’.€SflnnPAJ,’TEDwHrTt-4—----—I.n.n!UU(59mm19mmr21.7.)COI4CRflWASHOUTSIGNDtTML(OREOJVAW(1)$HHST_200mmSTAPhDETAILI.ACIUALLAYOUTOCTETISArNED(NTHEFiCW,2.THEcONCRETEWASkCWLION(SEEnO.4—15)SKALLBEINSTALLEDWITHINIDmOFThE1ZUP0P.YCONCRETEWASHOUTFAC,LmY.r.LImn/rcA-I.OWISACftI’2Figure4.1.7b—ConcreteWashoutAreaFigure4.1.8—PrefabricatedConcreteWashoutContainerwlRampohinwConstructionS1orn,i’aterPollutionPreeu/ioniius!201270mAF.ASIICU0f2-NITTOSCALETYPEASOVECR4DrWITHSTRAWBAILS BMPC160:CertifiedErosionandSedimentControlLeadPurposeTheprojectproponentdesignatesatleastonepersonastheresponsiblerepresentativeinchargeoferosionandsedimentcontrol(ESC),andwaterqualityprotection.ThedesignatedpersonshallbetheCertifiedErosionandSedimentControlLead(CESCL)whoisresponsibleforensuringcompliancewithalllocal,state,andfederalerosionandsedimentcontrolandwaterqualityrequirements.ConditionsofUseACESCLshallbemadeavailableonprojectsoneacreorlargerthatdischargestormwatertosurfacewatersofthestate.SiteslessthanoneacremayhaveapersonwithoutCESCLcertificationconductinspections;samplingisnotrequiredonsitesthatdisturblessthananacre.•TheCESCLshall:•HaveacurrentcertificateprovingattendanceinanerosionandsedimentcontroltrainingcoursethatmeetstheminimumESCtrainingandcertificationrequirementsestablishedbyEcology(seedetailsbelow).EcologywillmaintainalistofESCtrainingandcertificationprovidersat:http://www.ecy.wa.aov/proQrams/wg/stormwater/cescl.htmlOR•BeaCertifiedProfessionalinErosionandSedimentControl(CPESC);foradditionalinformationgoto:nvw.cpesc.netSpecjfications•Certificationshallremainvalidforthreeyears.•TheCESCLshallhaveauthoritytoactonbehalfofthecontractorordeveloperandshallbeavailable,oron-call,24hoursperdaythroughouttheperiodofconstruction.•TheConstructionSWPPPshallincludethename,telephonenumber,faxnumber,andaddressofthedesignatedCESCL.•ACESCLmayprovideinspectionandcomplianceservicesformultipleconstructionprojectsinthesamegeographicregion.DutiesandresponsibilitiesofthcCESCLshallinclude,butarcnotlimitedtothefollowing:•MaintainingpermitfileonsiteatalltimeswhichincludestheConstructionSWPPPandanyassociatedpermitsandplans.•DirectingBMPinstallation,inspection,maintenance,modification,andremoval.ohimeConstructionStonnitoterPollutionPreeu/ionuus!2012 •UpdatingallprojectdrawingsandtheConstructionSWPPPwithchangesmade.•CompletinganysamplingrequirementsincludingreportingresultsusingWebDMR.•Keepingdailylogs,andinspectionreports.Inspectionreportsshouldinclude:•Inspectiondate/time.•Weatherinformation;generalconditionsduringinspectionandapproximateamountofprecipitationsincethelastinspection.•AsummaryorlistofallBMPsimplemented,includingobservationsofallerosion/sedimentcontrolstructuresorpractices.Thefollowingshallbenoted:1.LocationsofBMPsinspected.2.LocationsofBMPsthatneedmaintenance.3.LocationsofBMPsthatfailedtooperateasdesignedorintended.4.LocationsofwhereadditionalordifferentBMPsarerequired.•Visualmonitoringresults,includingadescriptionofdischargedstorrnwater.Thepresenceofsuspendedsediment,turbidwater,discoloration,andoilsheenshallbenoted,asapplicable.•Anywaterqualitymonitoringperformedduringinspection.•Generalcommentsandnotes,includingabriefdescriptionofanyBMPrepairs,maintenanceorinstallationsmadeasaresultoftheinspection.•Facilitate,participatein,andtakecorrectiveactionsresultingfrominspectionsperformedbyoutsideagenciesortheowner.BMPC162:SchedulingPurposeSequencingaconstmctionprojectreducestheamountanddurationofsoilexposedtoerosionbywind,rain,runoff,andvehicletracking.conditionsofUseTheconstructionsequencescheduleisanorderlylistingofallmajorland-disturbingactivitiestogetherwiththenecessaryerosionandsedimentationcontrolmeasuresplannedfortheproject.Thistypeofscheduleguidesthecontractoronworktobedonebeforeotherworkisstartedsothatseriouserosionandsedimentationproblemscanbeavoided.Followingaspecifiedworkschcdulethatcoordinatesthetimingofland-disturbingactivitiesandtheinstallationofcontrolmeasuresisperhapsthemostcost-effectivewayofcontrollingerosionduringconstruction.TheremovalofsurfacegroundcoverleavesasitevulnerabletoacceleratedolunieConstrudilonS/onnii’aterPollutionPit’en/ionuus!2012 erosion.Constructionproceduresthatlimitlandclearingprovidetimelyinstallationoferosionandsedimentationcontrols,andrestoreprotectivecoverquicklycansignificantlyreducetheerosionpotentialofasite.Design.Minimizeconstructionduringrainyperiods.Coissiderations.Scheduleprojectstodisturbonlysmallportionsofthesiteatanyonetime.Completegradingassoonaspossible.Immediatelystabilizethedisturbedportionbeforegradingthenextportion.Practicestagedseedinginordertorevegetatecutandfillslopesastheworkprogresses.ohinwConstructionS/ornni’aterPothilionPieen/ionxius!2012 BMPC200:InterceptorDikeandSwalePurposeProvidearidgeofcompactedsoil,oraridgewithanupslopeswale,atthetoporbaseofadisturbedslopeoralongtheperimeterofadisturbedconstructionareatoconveystormwater.Usethedikeandlorswaletointercepttherunofffromunprotectedareasanddirectittoareaswhereerosioncanbecontrolled.Thiscanpreventstormrunofffromenteringtheworkareaorsediment-ladenrunofffromleavingtheconstructionsite.C’onditionsofUseWheretherunofffromanexposedsiteordisturbedslopemustbeconveyedtoanerosioncontrolfacilitywhichcansafelyconveythestormwater.•Locateupslopeofaconstructionsitetopreventrunofffrontenteringdisturbedarea.•Whenplacedhorizontallyacrossadisturbedslope,itreducestheamountandvelocity’ofrunoffflowingdowntheslope.•Locatedownslopetocollectrunofffromadisturbedareaanddirectwatertoasedimentbasin.Designand•Dikeand/orswaleandchannelmustbestabilizedwithtemporaryorInstallatio,,permanentvegetationorotherchannelprotectionduringconstruction.Specjfications•Channelrequiresapositivegradefordrainage;steepergradesrequirechannelprotectionandcheckdams.•Reviewconstructionforareaswhereovertoppingmayoccur.•Canbeusedattopofnewfillbeforevegetationisestablished.•Maybeusedasapermanentdiversionchanneltocarrytherunoff.•Sub-basintributaryareashouldbeoneacreorless.•Designcapacityforthepeakflowfroma10-year,24-hourstorm,assumingaTypeIArainfalldistribution,fortemporary’facilities.Alternatively,use1.6timesthe10-year,1-hourflowindicatedbyanapprovedcontinuousrunoffmodel.Forfacilitiesthatwillalsoserveonapermanentbasis,consultthelocalgovernment’sdrainagerequirements.Inrordishallmeetthefollowingcriteria:TopWidth2feetminimum.Height1.5feetminimumonberm.SideSlope2H:IVorflatter.GradeDependsontopography,however,dikesystemminimumis0.5%,andmaximumis1%.CompactionMinimumof90percentASTMD698standardproctor.olitmeConstructionS!onnii’aterPollutionPieentionuus!2012 HorizontalSpacingofInterceptorDikes:AraSoSoPriiFoaEn20H:IVorless3-5%300feet(10to20)F1:lV5-10%200feet(4to10)1+IV10-25%100feet(2to4)H:IV25-50%50feetStabilizationdependsonvelocityandreachSlopes<5%Seedandmulchappliedwithin5daysofdikeconstruction(seeBMPC121.Mulching).Slopes5-40%Dependentonrunoffvelocitiesanddikematerials.Stabilizationshouldbedoneimmediatelyusingeithersodorripraporothermeasurestoavoiderosion.•Theupslopesideofthedikeshallprovidepositivedrainagetothedikeoutlet.Noerosionshalloccurattheoutlet.Provideenergydissipationmeasuresasnecessary.Sediment-ladenrunoffmustbereleasedthroughasedimenttrappingfacility.•Minimizeconstructiontrafficovertemporarydikes.Usetemporarycrossculvertsforchannelcrossing.Inrorashallmeetthefollowingcriteria:BottomWidth2feetminimum;thecross-sectionbottomshallbelevel.DepthI-footminimum.SideSlope2H:IVorflatter.GradeMaximum5percent,withpositivedrainagetoasuitableoutlet(suchasasedimentpond).StabilizationSeedasperBMPC120,cmoraranPennanentSeeinorPC202,Cmmcl12inchesthickriprappressedintothebankandextendingatleast8inchesverticalfromthebottom.•Inspectdiversiondikesandinterceptorswalesonceaweekandaftereveryrainfall.Immediatelyremovesedimentfromtheflowarea.•Damagecausedbyconstructiontrafficorotheractivitymustberepairedbeforetheendofeachworkingday.Checkoutletsandmaketimelyrepairsasneededtoavoidgullyformation.Whentheareabelowthetemporarydiversiondikeispermanentlystabilized,removethedikeandfillandstabilizethechanneltoblendwiththenaturalsurface.ohuneConstructionStonmi’a!erPollutionPieentionuus!2012 BMPC201:Grass-LinedChannelsPurposeToprovideachannelwithavegetativeliningforconveyanceofrunoff.SeeFhure4.2.1fortypicalgrass-linedchannels.ConditionsofUseThispracticeappliestoconstructionsiteswhereconcentratedrunoffneedstobecontainedtopreventerosionorflooding.•Whenavegetativeliningcanprovidesufficientstabilityforthechannelcrosssectionandatlowervelocitiesofwater(normallydependentongrade).Thismeansthatthechannelslopesaregenerallylessthan5percentandspaceisavailableforarelativelylargecrosssection.•Typicalusesincluderoadsideditches,channelsatpropertyboundaries,outletsfordiversions,andotherchannelsanddrainageditchesinlowareas.•Channelsthatwillbevegetatedshouldbeinstalledbeforemajorearthworkandhydroseededwithabondedfibermatrix(BFM).Thevegetationshouldbewellestablished(i.e.,75percentcover)beforewaterisallovedtoflowintheditch.Withchannelsthatwillhavehighflows,erosioncontrolblanketsshouldbeinstalledoverthehydroseed.Ifvegetationcannotbeestablishedfromseedbeforewaterisallowedintheditch,sodshouldbeinstalledinthebottomoftheditchinlieuofhydromulchandblankets.DesignandLocatethechannelwhereitcanconformtothetopographyandotherInstallationfeaturessuchasroads.Specfflcations•Locatethemtousenaturaldrainagesystemstothegreatestextentpossible.•Avoidsharpchangesinalignmentorbendsandchangesingrade.•Donotreshapethelandscapetofitthedrainagechannel.•Themaximumdesignvelocityshallbebasedonsoilconditions,typeofvcgctation,andmcthodofrcvegctation,butatnotimesshaLlvelocityexceed5feet/second.Thechannelshallnotbeovertoppedbythepeakrunofffroma10-year,24-hourstorm,assumingaTypeIArainfalldistribution.Alternatively,use1.6timesthe10-year,1-hourflowindicatedbyanapprovedcontinuousrunoffmodeltodetermineaflowratewhichthechannelmustcontain.•Wherethegrass-linedchannelwiLLalsofunctionasapermanenistormwaterconveyancefacility,consultthedrainageconveyancerequirementsofthelocalgovernmentwithjurisdiction.olzi;wConstructionS!onnii’aterPollutionPieen/ionxius!2012 •Anestablishedgrassorvegetatedliningisrequiredbeforethechannelcanbeusedtoconveystormwater,unlessstabilizedwithnetsorblankets.•Ifdesignvelocityofachanneltobevegetatedbyseedingexceeds2fUsec,atemporarychannellinerisrequired.Geotextileorspecialmulchprotectionsuchasfiberglassrovingorstrawandnettingprovidesstabilityuntilthevegetationisfullyestablished.SeeFicure4.2.2.•Checkdamsshallberemovedwhenthegrasshasmaturedsufficientlytoprotecttheditchorswaleunlesstheslopeoftheswaleisgreaterthan4percent.Theareabeneaththecheckdamsshallbeseededandmulchedimmediatelyafterdamremoval.•Ifvegetationisestablishedbysodding,thepermissiblevelocityforestablishedvegetationmaybeusedandnotemporarylinerisneeded.•Donotsubjectgrass-linedchanneltosedimentationfromdisturbedareas.Usesediment-trappingBMPsupstreamofthechannel.•V-shapedgrasschannelsgenerallyapplywherethequantityofwaterissmall,suchasinshortreachesalongroadsides.TheV-shapedcrosssectionisleastdesirablebecauseitisdifficulttostabilizethebottomwherevelocitiesmaybehigh.•Trapezoidalgrasschannelsareusedwhererunoffvolumesarelargeandslopeislowsothatvelocitiesarenonerosivetovegetatedlinings.(Note:itisdifficulttoconstructsmallparabolicshapedchannels.)•Subsurfacedrainage,orriprapchannelbottoms,maybenecessaryonsitesthataresubjecttoprolongedwetconditionsduetolongdurationflowsorahighwatertable.•Provideoutletprotectionatculvertendsandatchannelintersections.•Grasschannels,ataminimum,shouldcarrypeakrunofffortemporaryconstructiondrainagefacilitiesfromthe10-year,24-hourstormwithouteroding.Wherefloodhazardexists,increasethecapacityaccordingtothepotentialdamage.•Grassedchannelsideslopesgenerallyareconstructed3H:IVorflattertoaidintheestablishmentofvegetationandformaintenance.•Constructchannelsaminimumof0.2footlargeraroundtheperipherytoallowforsoilbulkingduringseedbedpreparationsandsodbuildup.MaintenanceDuringtheestablishmentperiod,checkgrass-linedchannelsaftereverySta,zdardsrainfall.•Aftergrassisestablished,periodicallycheckthechannel;checkitafterevery’heavy’rainfallevent.Immediatelymakerepairs.•Itisparticularlyimportanttocheckthechanneloutletandallroadcrossingsforbankstabilityandevidenceofpipingorscourholes.ohmicConstructionStornni’aterPollutionPreen/ioniius!20120 Removeallsignificantsedimentaccumulationstomaintainthedesignedcarryingcapacity.Keepthegrassinahealthy,vigorousconditionatalltimes,sinceitistheprimaryerosionprotectionforthechannel.TypicalV-ShapedChannelCross-sectionGrass-LinedChannelCross-SectionCl50.225mm)KeyInFabricWithChannelLinerWiIhRockChterlotBaseFlowTypicalTrapezoidalChannelCross-SectionDesignDepth‘ercutchannel2”150mm)toIIowhulkingduringscedbedpreparationandgrowthofveqetalionFillerFatyiic1L/%•StiFigure4.2.1—TypicalGrass-LinedChannelsohmicCons!rudilonS!or;mi’a!erPollulionPieeu/iouitus!2012FilterFabricTypicalParabolicRocRCenter(150-225mm1KeyinFabricFilterFabricWarnRockCenterForBaseFlowI Overlap6(150mm)minimumflf/ThI./-r(m)tyct’-//TPICALINSTALLATIONWITHEROSIONCONTROLBMNKETSORTRFREINFORCEMENTMATSLSLtaItNOTES:IntermittentCheckSlotLongitudinalAnchorTrenchtoprotecLseedandsoiluntilvegetationbecomesestablished.2Grass-linedchannelswithdesignvelocitiesexceeding6fl/sec(2m/sec)shouldincludeturfreinforcementmats.Figure4.2.2—TemporaryChannelLinersEcavateCtiann&toDeigiiGradeapdCrossSectionIoERCTCHANNEL2(50mm)TOALLOWBLKING0RINGSEEDBEDPREPARATIONLonaitudinalanchorTrenchShingle-lapsplicedendsorbeginnewrollinanintermittentcheckslot4Preparesoilandapplyseedbeforeinstallingblankets,matsorothertemporarychannellinersystem44(14-‘A’IbesigneIocitiesexceeding2ft/sec(O.5m!sec)requiretemporaryblanLets,matsorsimilarlinersohuneConstrue/ionSlornnt’aterPollutionPieen/ionuus!2012 BMPC202:ChannelLiningPurposeToprotectchannelsbyprovidingachannellinerusingeitherblanketsorriprap.ConditionsofWhennaturalsoilsorvegetatedstabilizedsoilsinachannelarenotadequatiUsetopreventchannelerosion.•Whenapermanentditchorpipesystemistobeinstalledandatemporarymeasureisneeded.•Inalmostallcases.syntheticandorganiccoconutblanketsaremoreeffectivethanriprapforprotectingchannelsfromerosion.Blanketscanbeusedwithandwithoutvegetation.Blanketedchannelscanbedesignedtohandleanyexpectedflowandlongevityrequirement.Somesyntheticblanketshaveapredictedlifespanof50yearsormore,eveninsunlight.•Otherreasonswhyblanketsarebetterthanrockincludetheavailabilityofblanketsoverrock.Inmanyareasofthestate,rockisnoteasilyobtainableorisveryexpensivetohaultoasite.Blanketscanbedeliveredanywhere.Rockrequirestheuseofdumptruckstohaulandheavyequipmenttoplace.Blanketsusuallyonlyrequirelaborerswithhandtools,andsometimesabackhoe.•TheFederalHighwayAdministrationrecommendsnotusingflexiblelinerswhenevertheslopeexceeds10percentortheshearstressexceeds8lbs/ft2.DesignandSeeBMPC122forinformationonblankets.Installation.....Sincenprapisusedwhereerosionpotentialishigh,constructionmustbeSpecificationssequencedsothattheriprapisputinplacewiththeminimumpossibledelay.•Disturbanceofareaswhereriprapistobeplacedshouldbeundertakenonlywhenfinalpreparationandplacementoftheriprapcanfollowimmediatelybehindtheinitialdisturbance.\Vhereriprapisusedforoutletprotection,theriprapshouldbeplacedbeforeorinconjunctionwiththeconstructionofthepipeorchannelsothatitisinplacewhenthepipeorchannelbeginstooperate.•Thedesigner,afterdeterminingtheriprapsizethatwillbestableundertheflowconditions,shallconsiderthatsizetobeaminimumsizeandthen,basedonriprapgradationsactuallyavailableinthearea,selectthesizeorsizesthatequalorexceedtheminimumsize.Thepossibilityofdrainagestructuredamagebychildrenshallbeconsideredinselectingariprapsize,especiallyifthereisnearbywateroragullyinwhichtotossthestones.•Stoneforriprapshallconsistoffieldstoneorquarrystoneofapproximatelyrectangularshape.ThestoneshallbehardandangularoluincConstructionStonnii’aterPollutionPrecut/oniius!20)2 andofsuchqualitythatitwillnotdisintegrateonexposuretowaterorweatheringanditshallbesuitableinallrespectsforthepurposeintended.Aliningofengineeringfilterfabric(geotextile)shallbeplacedbetweentheriprapandtheunderlyingsoilsurfacetopreventsoilmovementintoorthroughtheriprap.Thegeotextileshouldbekeyedinatthetopofthebank.Filterfabricshallnotbeusedonslopesgreaterthan1-1/2H:IVasslippagemayoccur.Itshouldbeusedinconjunctionwithalayerofcoarseaggregate(granularfilterblanket)whentheripraptobeplacedis12inchesandlarger.BMPC203:WaterBarsPurposeAsmallditchorridgeofmaterialisconstructeddiagonallyacrossaroadorright-of-waytodivertstormwaterrunofffromtheroadsurface,wheeltracks,orashallowroadditch.SeeFiaure4.2.3.Co,,ditionsofuseClearingright-of-wayandconstructionofaccessforpowerlines,pipelines,andothersimilarinstallationsoftenrequirelongnarrowright-of-waysoverslopingterrain.DisturbanceandcompactionpromotesgullyformationintheseclearedstripsbyincreasingthevolumeandvelocityofrunoffGullyformationmaybeespeciallysevereintiretracksandruts.Topreventgullying,runoffcanoftenbedivertedacrossthewidthoftheright-of-waytoundisturbedareasbyusingsmallpredesigneddiversions.•Givespecialconsiderationtoeachindividualoutletarea,aswellastothecumulativeeffectofaddeddiversions.Usegraveltostabilizethediversionwheresignificantvehiculartrafficisanticipated.DesignaudITeight:8-inchminimummeasuredfromthechannelbottomtotheridgetop.Installation•Sideslopeofchannel:2H:IVmaximum:3H:IVorflatterwhenSpecsflcatwizs..-vehicleswillcross.•Basewidthofridge:6-inchminimum.•Locatethemtousenaturaldrainagesystemsandtodischargeintowellvegetatedstableareas.•GuidelineforSpacing:SoSain(f)<51255-1010010-207520-3550>35UscrocklinedditchohiuwConstructionStornnt’atcrPollutionPreentionUus!2012 •Gradeofwaterbarandangle:Selectanglethatresultsinditchslopelessthan2percent.•Installassoonastheclearingandgradingiscomplete.Reconstructwhenconstructioniscompleteonasectionwhenutilitiesarebeinginstalled.•Compacttheridgewheninstalled.•Stabilize,seedandmulchtheportionsthatarenotsubjecttotraffic.Graveltheareascrossedbyvehicles.MahitenancePeriodicallyinspectright-of-waydiversionsforwearandaftereveryheavyStandardsrainfallforerosiondamage.•Immediatelyremovesedimentfromtheflowareaandrepairthedike.•Checkoutletareasandmaketimelyrepairsasneeded.•Whenpermanentroaddrainageisestablishedandtheareaabovethetemporaryright-of-waydiversionispermanentlystabilized,removethedikesandfillthechanneltoblendwiththenaturalground,andappropriatelystabilizethedisturbedarea.DEEPWATERBARA24to30inchesB6toioteaSHALLOWWATERBARA8to12inchesB6to12fedFigure4.2.3—WaterBarolwneConstrue/iouS/ormiraftrPollutionPreentioniius!2012 BMPC204:PipeSlopeDrainsPurposeTouseapipetoconveystormwateranytimewaterneedstobedivertedawayfromoroverbaresoiltopreventgullies,channelerosion,andsaturationofslide-pronesoils.ConditionsofUsePipeslopedrainsshouldbeusedwhenatemporaryorpermanentstormwaterconveyanceisneededtomovethewaterdownasteepslopetoavoiderosion(Figure4.2.4).Onhighwayprojects,pipeslopedrainsshouldbeusedatbridgeendstocollectrunoffandpipeittothebaseofthefillslopesalongbridgeapproaches.Thesecanbedesignedintoaprojectandincludedasbiditems.Anotheruseonroadprojectsistocollectrunofffrompavementandpipeitawayfromsideslopes.Theseareusefulbecausethereisgenerallyatimelagbetweenhavingthefirstliftofasphaltinstalledandthecurbs,gutters,andpermanentdrainageinstalled.Usedinconjunctionwithsandbags,orothertemporarydiversiondevices,thesewillpreventmassiveamountsofsedimentfromleavingaproject.Watercanbecollected,channeledwithsandbags,TriangularSiltDikes,berms,orothermaterial,andpipedtotemporarysedimentponds.Pipeslopedrainscanbe:•Connectedtonewcatchbasinsandusedtemporarilyuntilallpermanentpipingisinstalled;•Usedtodrainwatercollectedfromaquifersexposedoncutslopesandtakeittothebaseoftheslope;•Usedtocollectcleanrunofffromplasticsheetinganddirectitawayfromexposedsoil;•Tnstalledinconjunctionwithsiltfencetodraincollectedwatertoacontrolledarea;•Usedtodivertsmallseasonalstreamsawayfromconstruction.Theyhavebeenusedsuccessfullyonculvertreplacementandextensionjobs.Largeflexpipecanbeusedonlargerstreamsduringculvertremoval,repair,orreplacement;and,•Connectedtoexistingdownspoutsandroofdrainsandusedtodivertwaterawayfromworkareasduringbuildingrenovation,demolition,andconstructionprojects.Therearenowseveralcommerciallyavailablecollectorsthatareattachedtothepipeinletandhelppreventerosionattheinlet.ohimeConsirudilonS!onnii’aterPot/uiionPreen/ioniius!2012 DesignandSizethepipetoconveytheflow.ThecapacityfortemporarydrainsshallbeInstallatia,;sufficienttohandlethepeakflowfroma10-year,24-hourstormevent,Spec(ficationsassumingaTypeIArainfalldistribution.Alternatively,use1.6timesthe10-year,1-hourflowindicatedbyanapprovedcontinuousrunoffmodel.Consultlocaldrainagerequirementsforsizingpermanentpipeslopedrains.•Usecareinclearingvegetatedslopesforinstallation.•Re-establishcoverimmediatelyonareasdisturbedbyinstallation.•Usetemporarydrainsonnewcutorfillslopes.•Usediversiondikesorswalestocollectwateratthetopoftheslope.•Ensurethattheentranceareaisstableandlargeenoughtodirectflowintothepipe.•Pipingofwaterthroughthebermattheentranceareaisacommonfailuremode.•Theentranceshallconsistofastandardflaredendsectionforculverts12inchesandlargerwithaminimum6-inchmetaltoeplatetopreventrunofffromundercuttingthepipeinlet.Theslopeoftheentranceshallbeatleast3percent.Sandbagsmayalsobeusedatpipeentrancesasatemporarymeasure.•Thesoilaroundandunderthepipeandentrancesectionshallbethoroughlycompactedtopreventundercutting.•Theflaredinletsectionshallbesecurelyconnectedtotheslopedrainandhavewatertightconnectingbands.•Slopedrainsectionsshallbesecurelyfastenedtogether,ftisedorhavegasketedwatertightfittings,andshallbesecurelyanchoredintothesoil.•Thrustblocksshouldbeinstalledanytime90degreebendsareutilized.Dependingonsizeofpipeandflow,thesecanbeconstructedwithsandbags,strawbalesstakedinplace,“t”postsandwire,orecologyblocks.•Pipeneedstobesecuredalongitsfulllengthtopreventmovement.Thiscanbedonewithsteel“t”postsandwire.Apostisinstalledoneachsideofthepipeandthepipeiswiredtothem.Thisshouldbedoneevery10-20feetofpipelengthorso,dependingonthesizeofthepipeandquantityofwatertodivert.•Interceptordikesshallbeusedtodirectrunoffintoaslopedrain.Theheightofthedikeshallbeatleast1foothigheratallpointsthanthetopoftheinletpipe.•Theareabelowtheoutletmustbestabilizedwithariprapapron(seeBMPC209OutletProtection,fortheappropriateoutletmaterial).oIzinwConstructionStornni’aterPollutionPieen/iouuus!2012 Ifthepipeslopedrainisconveyingsediment-ladenwater,directallflowsintothesedimenttrappingfacility.•Materialsspecificationsforanypermanentpipedsystemshallbesetbythelocalgovernment.MaintenanceStandardsCheckinletandoutletpointsregularly,especiallyafterstorms.Theinletshouldbefreeofundercutting,andnowatershouldbegoingaroundthepointofentry.Ifthereareproblems,theheadwal!shouldbereinforcedwithcompactedearthorsandbags.•Theoutletpointshouldbefreeoferosionandinstalledwithappropriateoutletprotection.•Forpermanentinstallations,inspectpipeperiodicallyforvandalismandphysicaldistresssuchasslidesandwind-throw.•Normallythepipeslopeissosteepthatcloggingisnotaproblemwithsmoothwallpipe,however,debrismaybecomelodgedinthepipe.Figure4.2.4—PipeSlopeDrainDikematerialcompacted90%modifiedproctorCPEPorequivalentpipeDikeDischargetoastabilizedwatercourse,sedimentretentionfacility,orstabilizedoutletStandardflaredendsectionInletandallsectionsmustbesecurelyfastenedtogetherwithgasketedwatertightfittingsolwneConstructionS/onmi’atcrPollutionPreentioniius!2012 BMPC205:SubsurfaceDrainsPurposeTointercept,collect,andconveygroundwatertoasatisfactoryoutlet,usingaperforatedpipeorconduitbelowthegroundsurface.Subsurfacedrainsarealsoknownas“frenchdrains.”Theperforatedpipeprovidesadewateringmechanismtodrainexcessivelywetsoils,provideastablebaseforconstruction,improvestabilityofstructureswithshallowfoundations,ortoreducehydrostaticpressuretoimproveslopestability.(‘onditionsofUseUsewhenexcessivewatermustberemovedfromthesoil.Thesoilpermeability,depthtowatertableandimperviouslayersareallfactorswhichmaygoverntheuseofsubsurfacedrains.Designalit!RIfdrainareusedeithertolowerthewatertableinlarge.relativelyInstallationflatareas,improvethegrowthofvegetation,ortoremovesurfacewater.SpecjflcationsReliefdrainsareinstalledalongaslopeanddraininthedirectionoftheslope.Theycanbeinstalledinagridpattern,aherringbonepattern,orarandompattern.Inrordrainareusedtoremoveexcessgroundwaterfromaslope,stabilizesteepslopes,andlowerthewatertableimmediatelybelowaslopetopreventthesoilfrombecomingsaturated.Interceptordrainsareinstalledperpendiculartoaslopeanddraintothesideoftheslope.Theyusuallyconsistofasinglepipeorseriesofsinglepipesinsteadofapatternedlayout.•Dandainofinrordrain--Thedepthofaninterceptordrainisdeterminedprimarilybythedepthtowhichthewatertableistobeloweredorthedepthtoaconfininglayer.Forpracticalreasons,themaximumdepthisusuallylimitedto6feet,withaminimumcoverof2feettoprotecttheconduiL•Thesoilshouldhavedepthandsufficientpcrmcabiliwtopermitinstallationofaneffectivedrainagesystematadepthof2to6feet.•Anadequateoutletforthedrainagesystemmustbeavailableeitherbygravityorbypumping.•Thequantityandqualityofdischargeneedstobeaccountedforinthereccivingstream(additionaldetentionmaybcrequired).•Thisstandarddoesnotapplytosubsurfacedrainsforbuildingfoundationsordeepexcavations.•Thecapacityofaninterceptordrainisdeterminedbycalculatingthemaximumrateofgroundwaterflowtobeintercepted.Therefore,itisohi;neCons/rue/ionS/onn;i’a/erPollutionPieen/ionuus!2012 goodpracticetomakecompletesubsurfaceinvestigations,includinghydraulicconductivityofthesoil,beforedesigningasubsurfacedrainagesystem.•Siofdrain--Sizesubsurfacedrainstocarry’therequiredcapacitywithoutpressureflow.Minimumdiameterforasubsurfacedrainis4inches.•Theminimumvelocityrequiredtopreventsiltingis1.4ft./sec.Thelineshallbegradedtoachievethisvelocityataminimum.Themaximumallowablevelocityusingasand-gravelfilterorenvelopeis9fUsec.•Filtermaterialandfabricshallbeusedaroundalldrainsforproperbeddingandfiltrationoffinematerials.Envelopesandfiltersshouldsurroundthedraintoaminimumof3-inchthickness.•Theoutletofthesubsurfacedrainshallempty’intoasedimentpondthroughacatchbasin.Iffreeofsediment,itcanthenemptyintoareceivingchannel,swale,orstablevegetatedareaadequatelyprotectedfromerosionandundermining.•Thetrenchshallbeconstructedonacontinuousgradewithnoreversegradesorlowspots.•Softoryieldingsoilsunderthedrainshallbestabilizedwithgravelorothersuitablematerial.•Backlillingshallbedoneimmediatelyafterplacementofthepipe.Nosectionsofpipeshallremainuncoveredovernightorduringarainstorm.Backfillmaterialshallbeplacedinthetrenchinsuchamannerthatthedrainpipeisnotdisplacedordamaged.•Donotinstallpermanentdrainsneartreestoavoidthetreerootsthattendtoclogtheline.Usesolidpipewithwatertightconnectionswhereitisnecessary’topassasubsurfacedrainagesystemthroughastandoftrees.•0--Ensurethattheoutletofadrainemptiesintoachannelorotherwatercourseabovethenormalwaterlevel.•Secureananimalguardtotheoutletendofthepipetokeepoutrodents.•Useoutletpipeofcorrugatedmetal,castiron,orheavy-dutyplasticwithoutperforationsandatleast10feetlong.Donotuseanenvelopeorfiltermaterialaroundtheoutletpipe,andburyatleasttwo-thirdsofthepipelength.•Whenoutletvelocitiesexceedthoseallowableforthereceivingstream,outletprotectionmustbeprovided.obtineConsinictionStonmi’aterPollze/io;iPieentionitits!20120 MaintenanceSubsurfacedrainsshallbecheckedperiodicallytoensurethattheyareStandardsfree-flowingandnotcloggedwithsedimentorroots.•Theoutletshallbekeptcleanandfreeofdebris.•SurfaceinletsshalLbekeptopenandfreeofsedimentandotherdebris.•Treeslocatedtooclosetoasubsurfacedrainoftenclogthesystemwiththeirroots.Ifadrainbecomesclogged,relocatethedrainorremovethetreesasalastresort.Drainplacementshouldbeplannedtominimizethisproblem.•Wheredrainsarecrossedbyheavyvehicles,thelineshallbecheckedtoensurethatitisnotcrushed.BMPC206:LevelSpreaderPurposeToprovideatemporaryoutletfordikesanddiversionsconsistingofanexcavateddepressionconstructedatzerogradeacrossaslope.Toconvertconcentratedrunofftosheetflowandreleaseitontoareasstabilizedbyexistingvegetationoranengineeredfilterstrip.ConditionsofUseUsedwhenaconcentratedflowofwaterneedstobedispersedoveralargeareawithexistingstablevegetation.•Itemstoconsiderare:I.Whatistheriskoferosionordamageiftheflowmaybecomeconcentrated?2.Isaneasementrequiredifdischargedtoadjoiningproperty?3.Mostoftheflowshouldbeasgroundwaterandnotassurfaceflow.4.Isthereanunstableareadownstreamthatcannotacceptadditionalgroundwater?•Useonlywheretheslopesaregentle,thewatervolumeisrelativelylow,andthesoilwilladsorbmostofthelowflowevents.DesignandUseaboveundisturbedareasthatarestabilizedbyexistingvegetation.InstallationTfthelevelspreaderhasanylowpoints,flowwillconcentrate,createSpecificationschannelsandmaycauseerosion.•Dischargeareabelowtheoutletmustbeuniformwithaslopeflatterthan511:IV.•Outlettobeconstructedlevelinastable,undisturbedsoilprofile(notonfill).•Therunoffshallnotre-concentrateafterreleaseunlessinterceptedbyanotherdownstreammeasure.ohuneConstructionStormii’a!erPollutionPreen/ioniius!20)2I •Thegradeofthechannelforthelast20feetofthedikeorinterceptorenteringthelevelspreadershallbelessthanorequalto1percent.Thegradeofthelevelspreadershallbe0percenttoensureuniformspreadingofstormrunofE•A6-inchhighgravelbermplacedacrossthelevellipshallconsistofwashedcrushedrock,2-to4-inchor3/4-inchtoIVa-inchsize.•Thespreaderlengthshallbedeterminedbyestimatingthepeakflowexpectedfromthe10-year,24-hourdesignstorm.Thelengthofthespreadershallbeaminimumof15feetfor0.1cfsandshallincreaseby10feetforeach0.1cfsthereaftertoamaximumof0.5cfsperspreader.Usemultiplespreadersforhigherflows.•Thewidthofthespreadershouldbeatleast6feet.AlaintenanceStandards•Thedepthofthespreaderasmeasuredfromthelipshouldbeatleast6inchesanditshouldbeuniformacrosstheentirelength.•Levelspreadersshallbesetbackfromthepropertylineunlessthereisaneasementforflow.•Levelspreaders,wheninstalledeverysoofteningrassyswales,keeptheflowsfromconcentrating.Materialsthatcanbeusedincludesandbags,lumber,logs,concrete,andpipe.Tofunctionproperly,thematerialneedstobeinstalledlevelandoncontour.Figures4.2.5Fiaure425and4.2.6provideacross-sectionandadetailofalevelspreader.Acappedperforatedpipecouldalsobeusedasaspreader.Thespreadershouldbeinspectedaftereveryrunoffeventtoensurethatitisffinctioningcorrectly.•Thecontractorshouldavoidtheplacementofanymaterialonthestructureandshouldpreventconstructiontrafficfromcrossingoverthestructure.•Ifthespreaderisdamagedbyconstructiontraffic,itshallbeimmediatelyrepaired.Figure4.2.5—CrossSectionofLevelSpreaderolunwConstructionS!onnu’aterPollutionPreentioniius!2012Pressure-Treated2’xlO’Dens&yvegetatedforaMm.of100’andslopelessthan5:13Mm.—I BMPC207:CheckDamsPurposeConstructionofsmalldamsacrossaswaleorditchreducesthevelocityofconcentratedflowanddissipatesenergyatthecheckdarn.ConditionsofUse\\Theretemporarychannelsorpermanentchannelsarenotyetvegetated,channelliningisinfeasible,and/orvelocitychecksarerequired.•CheckdamsmaynotbeplacedinstreamsunlessapprovedbytheStateDepartmentofFishandWildlife.Checkdamsmaynotbeplacedinwetlandswithoutapprovalfromapermittingagency.•DonotplacecheckdamsbelowtheexpectedbackwaterfromanysalmonidbearingwaterbetweenOctober1andMay31toensurethatthereisnolossofhighflowrefugehabitatforoverwinteringjuvenilesalmonidsandemergentsalmonidfry.•Constructrockcheekdamsfromappropriatelysizedrock.Therockusedmustbelargeenoughtostayinplacegiventheexpecteddesignflowthroughthechannel.Therockmustbeplacedbyhandorbymechanicalmeans(nodumpingofrocktoformdarn)toachievecompletecoverageoftheditchorswaleandtoensurethatthecenterofthedamislowerthantheedges.•Checkdamsmayalsobeconstructedofeitherrockorpea-gravelfilledbags.Numerousnewproductsarealsoavailableforthispurpose.Theytendtobere-usable,quickandeasytoinstall,effective,andcostefficient.•Placecheckdamsperpendiculartotheflowofwater.•Thedamshouldformatrianglewhenviewedfromtheside.Thispreventsundercuttingaswaterflowsoverthefaceofthedamratherthanfallingdirectlyontotheditchbottom.Spreadermustbelevel6”mmTreated2x1O”maybeabuttedendtoendformax.spreaderlengthof50- - -H41”mm.6”mm.tV11=11=111=111=1118mm.rebarsupporls8max.spacing—Figure4.2.6—DetailofLevelSpreaderoh,,,,eConstructionStornni’aterPollutionPieeli/jo,?uus!2012 •Beforeinstallingcheckdamsimpoundandbypassupstreamwaterflowawayfromtheworkarea.Optionsforbypassingincludepumps,siphons,ortemporarychannels.•Checkdamsinassociationwithsumpsworkmoreeffectivelyatslowingflowandretainingsedimentthanjustacheckdamalone.Adeepsumpshouldbeprovidedimmediatelyupstreamofthecheckdam.•Insomecases,ifcarefullylocatedanddesigned,checkdamscanremainaspermanentinstallationswithveryminorregrading.Theymaybeleftaseitherspillways,inwhichcaseaccumulatedsedimentwouldbegradedandseeded,orascheekdamstopreventifirthersedimentfromleavingthesite.•Themaximumspacingbetweenthedamsshallbesuchthatthetoeoftheupstreamdarnisatthesameelevationasthetopofthedownstreamdam.•Keepthemaximumheightat2feetatthecenterofthedam.•Keepthecenterofthecheckdamatleast12incheslowerthantheouteredgesatnaturalgroundelevation.•Keepthesideslopesofthecheckdamat2H:IVorflatter.•Keythestoneintotheditchbanksandextenditbeyondtheabutmentsaminimumof18inchestoavoidwashoutsfromoverflowaroundthedarn.•Usefilterfabricfoundationunderarockorsandbagcheckdam.Ifablanketditchlinerisused,filterfabricisnotnecessary.Apieceoforganicorsyntheticblanketcuttofitwillalsoworkforthispurpose.•Inthecaseofgrass-linedditchesandswales,allcheckdamsandaccumulatedsedimentshallberemovedwhenthegrasshasmaturedsufficientlytoprotecttheditchorswale-unlesstheslopeoftheswaleisgreaterthan4percent.Theareabeneaththecheckdamsshallbeseededandmulchedimmediatelyafterdamremoval.•Ensurethatchannelappurtenances,suchasculvertentrancesbelowcheckdams,arenotsubjecttodamageorblockagefromdisplacedstones.Ficure4.2.7depictsatypicalrockcheckdarn.MaintenanceCheckdamsshallbemonitoredforperformanceandsedimentStandardsaccumulationduringandaftcreachrunoffproducingrainfall.Sedimentshallberemovedwhenitreachesonehalfthesumpdepth.•Anticipatesubmergenceanddepositionabovethecheckdamanderosionfromhighflowsaroundtheedgesofthedam.•Ifsignificanterosionoccursbetweendams,installaprotectiveripraplinerinthatportionofthechannel.ohimeConstructionS!onmi’aterPollutionPieen/ionuus!2012 ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC207.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecv.wa.uov/prorams/vg/stormvater/ne;•’tech/eguiva1ent.htm1oh,,neConstructionStonnii’aterPollutionPieentionuus!2012 ohmieConstructionStornzii’a/crPothitionPieentionuus!2012Figure4.2.7—RockCheckDam BMPC208:TriangularSiltDike(TSD)(Geotextile-EncasedCheckDam)PurposeTriangularsiltdikesmaybeusedascheckdams,forperimeterprotection,fortemporarysoilstockpileprotection,fordropinletprotection,orasatemporaryinterceptordike.Condilio,,sofuse•Maybeusedonsoilorpavementwithadhesiveorstaples.TSDshavebeenusedtobuildtemporary:1.sedimentponds;2.diversionditches;3.concretewashoutfacilities;4.curbing;5.waterbars;6.levelspreaders;and,7.berms.DesignandMadeofurethanefoamsewnintoawovengeosyntheticfabric.Installation.....Itistrianoular,10inchesto14incheshighinthecenter,witha20-inchtoSpecifications28-inchbase.A2—footapronextendsbeyondbothsidesofthetrianglealongitsstandardsectionof7feet.Asleeveatoneendallowsattachmentofadditionalsectionsasneeded.•Installwithendscurveduptopreventwaterfromflowingaroundtheends.•Thefabricflapsandcheckdamunitsareattachedtothegroundwithwirestaples.WirestaplesshouldbeNo.11gaugewireandshouldbe200mmto300mminlength.•Whenmultipleunitsareinstalled,thesleeveoffabricattheendoftheunitshalloverlaptheabuttingunitandbestapled.•Checkdamsshouldbelocatedandinstalledassoonasconstructionwillallow.•Checkdamsshouldbeplacedperpendiculartotheflowofwater.•Whenusedascheekdams,theleadingedgemustbesecuredwithrocks,sandbags,orasmallkeyslotandstaples.•Inthecaseofgrass-linedditchesandswales,checkdamsandaccumulatedsedimentshallberemovedwhenthegrasshasmaturedsufficientlytoprotecttheditchorswaleunlesstheslopeoftheswaleisgreaterthan4percent.Theareabeneaththecheckdarnsshallbesccdcdandmulchedimmediatelyafterdamremoval.MaintenanceaTriangularsiltdamsshallbeinspectedforperformanceandsedimentohuneCons/rue/jo;;S/ornni’a/erPollutionPieeu/ionuus!2012 Standardsaccumulationduringandaftereachrunoffproducingrainfall.Sedimentshallberemovedwhenitreachesonehalftheheightofthedam.Anticipatesubmergenceanddepositionabovethetriangularsiltdamanderosionfromhighflowsaroundtheedgesofthedam.Immediatelyrepairanydamageoranyundercuttingofthedam.BMPC209:OutletProtectionPurposeOutletprotectionpreventsscouratconveyanceoutletsandminimizesthepotentialfordownstreamerosionbyreducingthevelocityofconcentratedstorirnvaterflows.ConditionsofuseOutletprotectionisrequiredattheoutletsofallponds,pipes,ditches,orotherconveyances,andwhererunoffisconveyedtoanaturalormanmadedrainaaefeaturesuchasastream.wetland.lake,orditch.DesignandThereceivingchannelattheoutletofaculvertshallbeprotectedfromInstallationerosionbyrockliningaminimumof6feetdownstreamandextendingupSpecjflcationsthechannelsidesaminimumof1—footabovethemaximummilwaterelevationor1-footabovethecrown,whicheverishigher.Forlargepipes(morethan18inchesindiameter).theoutletprotectionliningofthechannelislengthenedtofourtimesthediameteroftheculvert.•Standardwingwalls,andtaperedoutletsandpavedchannelsshouldalsobeconsideredwhenappropriateforpermanentculvertoutletprotection.(SeeWSDOTFlydraulicManual,availablethroughWSDOTEngineeringPublications).•Organicorsyntheticerosionblankets,withorwithoutvegetation,areusuallymoreeffectivethanrock,cheaper,andeasiertoinstall.Materialscanbechosenusingmanufacturerproductspecifications.ASTMtestresultsareavailableformostproductsandthedesignercanchoosethecorrectmaterialfortheexpectedflow.•Withlowflows,vegetation(includingsod)canbeeffective.•Thefollowingguidelinesshallbeusedforriprapoutletprotection:1.Ifthedischargevelocityattheoutletislessthan5fps(pipeslopelessthan1percent),use2—inchto8—inchriprap.Minimumthicknessis1-foot.2.For5to10fpsdischargevelocityattheoutlet(pipeslopelessthan3percent),use24-inchto48-inchriprap.Minimumthicknessis2feet.3.Foroutletsatthebaseofsteepslopepipes(pipeslopegreaterthan10percent),anengineeredenergydissipatershallbeused.•Filterfabricorerosioncontrolblanketsshouldalwaysbeusedunderripraptopreventscourandchannelerosion.ohmic(‘onstructionStornni’atcrPollutionPit’entioniizit2012 •Newpipeoutfallscanprovideanopportunityforlow-costfishhabitatimprovements.Forexample,analcoveoflow-velocitywatercanbecreatedbyconstructingthepipeoutfallandassociatedenergydissipaterbackfromthestreamedgeanddiggingachannel,over-widenedtotheupstreamside,fromtheoutfall.Ovenvinterinajuvenileandmigratingadultsalmonidsmayusethealcoveasshelterduringhighflows.Bankstabilization,bioengineering,andhabitatfeaturesmayberequiredfordisturbedareas.ThisworkmayrequireaHPA.SeeVolumeVformoreinformationonoutfallsystemdesign.Maintenance•Inspectandrepairasneeded.Standards.•Addrockasneededtomaintaintheintendedfunction.•Cleanenergydissipaterifsedimentbuildsup.BMPC220:StormDrainInletProtectionPurposeStormdraininletprotectionpreventscoarsesedimentfromenteringdrainagesystemspriortopcrmancntstabilizationofthedisturbedarea.Co,,ditionsofUseUsestormdraininletprotectionatinletsthatareoperationalbeforepermanentstabilizationofthedisturbeddrainagearea.Provideprotectionforallstormdraininletsdownslopeandwithin500feetofadisturbedorconstructionarea,unlessconveyingrunoffenteringcatchbasinstoasedimentpondortrap.Alsoconsiderinletprotectionforlawnandyarddrainsonnewhomeconstruction.Thesesmallandnumerousdrainscoupledwithlackofguttersinnewhomeconstructioncanaddsignificantamountsofsedimentintotheroofdrainsystem.Ifpossibledelayinstallinglawnandyarddrainsuntiljustbeforelandscapingorcapthesedrainstopreventsedimentfromenteringthesystemuntilcompletionoflandscaping.Provide18—inchesofsodaroundeachfinishedlawnandyarddrain.Table4.2.2listsseveraloptionsforinletprotection.Allofthemethodsforstormdraininletprotectiontendtoplugandrequireahighfrequencyofmaintenance.Limitdrainageareastooneacreorless.Possiblyprovideemergencyoverflowswithadditionalend-of-pipetreatmentwherestormwaterpondingwouldcauseahazard.olnuwConstructionSlormiraterPollutionPieentioniius!2012 Table4.2.2StormDrainInletProtectionApplicableforTypeofInletEmergencyPaved!EarthenProtectionOverflowSurfacesConditionsofUseDropInletProtectionExcavateddropinletYes,EarthenApplicableforheavyflows.Easyprotectiontemporarytomaintain.LargeareafloodingwillRequirement:30’X30/acreoccurBlockandgraveldropYesPavedorEarthenApplicableforheavyconcentratedinletprotectionflows.Willnotpond.GravelandwiredropNoApplicableforheavyconcentratedinletprotectionflows.Willpond.Canwithstandtraffic.CatchbasinfiltersYesPavedorEarthenFrequentmaintenancerequired.CurbInletProtectionCurbinletprotectionSmallcapacityPavedUsedforsturdymorecompactwithawoodenweiroverflowinstallation.BlockandgravelcurbYesPavedSturdy,butlimitedfiltration.inletprotectionCulvertInletProtectionCulvertinletsediment18monthexpectedlife.trapDesignandcciateDivnielProtection-AnexcavatedimpoundmentaroundtheInstallationstormdrain.SedimentsettlesoutofthestormwaterpriortoenteringtheSpecjficationsstormdrain.•Provideadepthof1-2ftasmeasuredfromthecrestoftheinletstructure.•Slopesidesofexcavationnosteeperthan2H:IV.•Minimumvolumeofexcavation35cubicyards.•ShapebasintoFitsitewithlongestdimensionorientedtowardthelongestinflowarea.•Installprovisionsfordrainingtopreventstandingwaterproblems.•Cleartheareaofalldebris.•Gradetheapproachtotheinletuniformly.•Drillweepholesintothesideoftheinlet.•Protectweepholeswithscreenwireandwashedaggregate.•Sealweepholeswhenremovingstructureandstabilizingarea.ohuneConstructionStonnii’caerPollutionPreen/ioniiUSI20120 •.Buildatemporary’dike,ifnecessary’,tothedownslopesideofthestructuretopreventbypassflow.TheanGritciil/cr-Abanierformedaroundthestormdraininletwithstandardconcreteblocksandgravel.SeeFigure4.2.8.•ProvideaheightofIto2feetaboveinlet.•Recessthefirstrow2-inchesintothegroundforstability.•Supportsubsequentcoursesbyplacinga2x4throughtheblockopening.•Donotusemortar.•Laysomeblocksinthebottomrowontheirsidefordewateringthepool.•PlacehardwareclothorcomparablewiremeshwithV-inchopeningsoverallblockopenings.•Placegraveljustbelowthetopofblocksonslopesof2Ff:IVorflatter.•Analternativedesignisagraveldonut.•Provideaninletslopeof3H:IV.•Provideanoutletslopeof2H:IV.•Provideal-footwidelevelstoneareabetweenthestructureandtheinlet.•Useinletslopestones3inchesindiameterorlarger.•Usegravel‘/2-toV4-inchataminimumthicknessofI-footfortheoutletslope.olunicConstructionStornni’aterPollutionPreen/ionitus!2012I .Figure4.2.8—BlockandGravelFilterGracianireesliter-Agravelbarrierplacedoverthetopoftheinlet.Thisstructuredoesnotprovideanoverflow.•Useahardwareclothorcomparablewiremeshwith¼-inchopenings.•Usecoarseaggregate.•Provideaheight1-footormore,18-incheswiderthaninletonallsides.•PlacewiremeshoverthedropinletsothatthewireextendsaminimumofI-footbeyondeachsideoftheinletstructure.•Overlapthestripsifmorethanonestripofmeshisnecessary.olunwconstructionStonniraterPollutionPreen/ionuus!2012PlanViewDrainGrateA’ConcreteBlockGravelBackfillSectionA—AConcreteBlockGravelBackfill___OverflowWaterWireScreenor/////FilterFabricPondingHeight_____ _ ___Notes:1.Dropinletsedimentbarriersaretobeusedforsmall,nearlyleveldrainageareas.(lessthan5%)2.Excavateabasinofsufficientsizeadjacenttothedropinlet.3.Thetopofthestructure(pondinglieilit)rousthewellbclovthegmundelevationdownslopetopreventrunofffromhvpassingtheinlet.Atemporarydilemayhenecessaryonthedownslopesideof(liestruclure ••Placecoarseaggregateoverthewiremesh.Provideatleasta12-inchdepthofgravelovertheentireinletopeningandextendatleast18-inchesonallsides.Cafebasinfliers—Useinsertsdesignedbymanufacturersforconstructionsites.Thelimitedsedimentstoragecapacityincreasestheamountofinspectionandmaintenancerequired,whichmaybedailyforheavysedimentloads.Toreducemaintenancerequirementscombineacatchbasinfilterwithanothertypeofinletprotection.Thistypeofinletprotectionprovidesflowbypasswithoutoverflowandthereforemaybeabettermethodforinletslocatedalongactiverights-of-way.•Provides5cubicfeetofstorage.•Requiresdewateringprovisions.•Providesahigh-flowbypassthatwillnotclogundernormaluseataconstructionsite.•Insertthecatchbasinfilterinthecatchbasinjustbelowthegrating.Curbtile!Protectionwitooeneir—Barrierformedaroundacurbinletwithawoodenframeandgravel.•Usewiremeshwith4-inchopenings.•Useextrastrengthfiltercloth.•Constructaframe.•Attachthewireandfilterfabrictotheframe.•Pilecoarsewashedaggregateagainstwire/fabric.•Placeweightonframeanchors.bcanGmciCurbizietProtection—Barrierformedaroundacurbinletwithconcreteblocksandgravel.SeeFigure4.2.9.•Usewiremeshwith¼-inchopenings.•Placetwoconcreteblocksontheirsidesabuttingthecurbateithersideoftheinletopening.Thesearespacerblocks.•Placea2x4studthroughtheouterholesofeachspacerblocktoalignthefrontblocks.•Placeblocksontheirsidesacrossthefrontoftheinletandabuttingthespacerblocks.•Placewiremeshovertheoutsideverticalface.•Pilecoarseaggregateagainstthewiretothetopofthebarrier.CurbanGutterScintentairier—Sandbagorrockberm(riprapandaggregate)3feethighand3feetwideinahorseshoeshape.SeeFiae4.2.10.c/tuneCons/rite/ionS/or,mi’a/erPollutionPreen/ionxius!2012 •Constructahorseshoeshapedberm,facedwithcoarseaggregateifusingriprap,3feethighand3feetwide,atleast2feetfromtheinlet.•Consiructahorseshoeshapedsedimentationtrapontheoutsideofthebermsizedtosedimenttrapstandardsforprotectingaculvertinlet.Maintenance•Inspectcatchbasinfiltersfrequently,especiallyafterstormevents.StandardsCleanandreplacecloggedinserts.Forsystemswithcloggedstonefilters:pullawaythestonesfromtheinletandcleanorreplace.Analternativeapproachwouldbetousethecloggedstoneasfillandputfreshstonearoundtheinlet.•Donotwashsedimentintostormdrainswhilecleaning.Spreadallexcavatedmaterialevenlyoverthesurroundinglandareaorstockpileandstabilizeasappropriate.ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC220.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecy.wa.gov/proarams/wg/stormwater/newtech/epuivalent.htmlolzmwCons/rue/ionStonnii’a/erPothillonPreen/ioniius!2012 PlanViewNOTES:1.Useblockandgraveltypesedimentbarrierwhencurbinletislocatedingentlyslopingstreetsegment,wherewatercanpondandallowsedimenttoseparatefromrunoff.2.Barriershallallowforoverflowfromseverestormevent.3.Inspectbarriersandremovesedimentaftereachstormevent,Sedimentandgravelmustberemovedfromthetraveledwayimmediately.Figure4.2.9—BlockandGravelCurbInletProtectionCatchBasinBackofSidewalkABackofCurbSectionA-A2x4WoodStudConcreteBlock%‘Drain(20mm)3,4DrainGravel(20mm)ConcreteBlockHeightConcreteBlockWireScreenorFilterFabricCurbInletWoodStud(100x50TimberStud)CatchBasinohoneConstructionStormwa!erPollutionPieen/ioniiust2012 PlanViewBackofSidew&kNOTES:1.Placecurbtypesedimentbarriersongentlyslopingstreetsegments,wherewatercanpondandallowsedimenttoseparatefromrunoff.2.Sandbagsofeitherburlaporwoven‘geotexfile’fabric,axefilledwithgravel,layeredandpackedtightly.3.Leaveaonesandbaggapinthetoprowtoprovideaspillwayforoverflow.4.InspectbarriersandremovesedimentaftereachstormeventSedimentandgravelmustberemovedfromthetraveledwayimmediately.Figure4.2.10—CurbandGutterBarrierBurlapSackstoontoCurbCatchBasinCurbInletRUNOFFBackofSandbagsStackedTightlyohmicConstructionStonnii’aterPollutionPieen/ioniius!2012 BMPC231:BrushBarrierPurposeConditionsofUseDesignandInstallationSpec(flcations.[Vlàintw,anceStandardsThepurposeofbrushbarriersistoreducethetransportofcoarsesedimentfromaconstructionsitebyprovidingatemporaryphysicalbarriertosedimentandreducingtherunoffvelocitiesofoverlandflow.•Brushbarriersmaybeuseddownslopeofalldisturbedareasoflessthanone-quarteracre.•Brushbarriersarenotintendedtotreatconcentratedflows,noraretheyintendedtotreatsubstantialamountsofoverlandflow.Anyconcentratedflowsmustbeconveyedthroughthedrainagesystemtoasedimentpond.Theonlycircumstanceinwhichoverlandflowcanbetreatedsolelybyabrushbarrier,ratherthanbyasedimentpond,iswhentheareadrainingtothebarrierissmall.•Brushbarriersshouldonlybeinstalledoncontours.•Height2feet(minimum)to5feet(maximum).•Width5feetatbase(minimum)to15feet(maximum).•Filterfabric(geotextile)maybeanchoredoverthebrushbermtoenhancethefiltrationabilityofthebarrier.Ten-ounceburlapisanadequatealternativetofilterfabric.•Chippedsitevegetation,compostedmulch,orwood-basedmulch(hogfuel)canbeusedtoconstructbrushbarriers.•A100percentbiodegradableinstallationcanbeconstructedusing10-ounceburlapheldinplacebywoodenstakes.Figure4.2.11depictsatypicalbrushbarrier.•Thereshallbenosignsoferosionorconcentratedrunoffunderoraroundthebarrier.Ifconcentratedflowsarebypassingthebarrier,itmustbeexpandedoraugmentedbytoed-infilterfabric.Thedimensionsofthebarriermustbemaintained.Ifrequired,drapefilterfabricoverbrushandsecurein4y4mm.trenchwithcompactedbackfill.Mm.5widebrushbarrierwithmay.6”diameterwoodydebris.Alternativelytopsoilstrippingsmaybeusedtoformthebarrier.Figure4.2.11—BrushBarrierohaneConstructionStonmi’a!erPollutionPreentionuus!2012 BMPC232:GravelFilterBermPurposeAgravelfilterbermisconstructedonrights-of-wayortrafficareaswithinaconstructionsitetoretainsedimentbyusingafilterbermofgravelorcrushedrock.ConditionsofUseWhereatemporarymeasureisneededtoretainsedimentfromrights-of-wayorintrafficareasonconstructionsites.Designand•Bermmaterialshallbe¼to3inchesinsize,washedwell-gradegravelInstallationorcrushedrockwithlessthan5percentfines.Specftications•Spacingofberms:—Every300feetonslopeslessthan5percent—Every200feetonslopesbetween5percentand10percent—Every100feetonslopesgreaterthan10percent•Bermdimensions:—1foothighwith3H:IVsideslopes—8linearfeetper1cfsrunoffbasedonthe10-year,24-hourdesignstormMaintenance•Regularinspectionisrequired.SedimentshallberemovedandfilterStandardsmaterialreplacedasneeded.BMPC233:SiltFencePurposeUseofasiltfencereducesthetransportofcoarsesedimentfromaconstructionsitebyprovidingatemporaryphysicalbarriertosedimentandreducingtherunoffvelocitiesofoverlandflow.SeeFiuure4.2.12fordetailsonsiltfenceconstruction.ConditionsofUseSiltfencemaybeuseddownslopeofalldisturbedareas.•Siltfenceshallpreventsoilcarriedbyrunoffwaterfromgoingbeneath,through,oroverthetopofthesiltfence,butshallallowthewatertopassthroughthefence.•Siltfenceisnotintendedtotreatconcentratedflows,norisitintendedtotreatsubstantialamountsofoverlandflow.Conveyanyconcentratedflowsthroughthedrainagesystemtoasedimentpond.•DonotconstructsiltfencesinstreamsoruseinV-shapedditches.Siltfencesdonotprovideanadequatemethodofsiltcontrolforanythingdeeperthansheetoroverlandflow.olinuc’Cons/ritdilonS!ori;npa/c,’PollutionPit’eli/jo,,iius!2012 Jointsinfilterfabricshallbesplicedatposts.Usestaples,wireringsor2”x2”b14Gawireorequivalenttoattachfabrictopostsequivarent,ifstandardAtl;:lflEJ2istrengthfabricusedIr.zJIiJ4AFilterfabricIIIIIUtIflhtlEj4jIiThH-i.9I6max—-Minimum4x4’trench—4’.9iiBackfilltrenchwithnativesoilPostspacingmaybeincreasedor3!4-1.5”washedgravelto8iiwirebackingIsused2”x2’woodposts,steeltenceposts,orequivalentFigure4.2.12—SiltFenceDesignand•UseincombinationwithsedimentbasinsorotherBMPs.Installation•Maxtmumslopesteepness(normal(perpendtcular)tofenceline)SpecificationsIH:IV.•Maximumsheetoroverlandflowpathlengthtothefenceof100feet.•Donotallowflowsgreaterthan0.5cfs.•Thegeotextileusedshallmeetthefollowingstandards.Allgeotextilepropertieslistedbelowareminimumaveragerollvalues(i.e.,thetestresultforanysampledrollinalotshallmeetorexceedthevaluesshowninTable4.2.3):Table4.2.3GeotextileStandardsPolymericMeshAOS0.60nmmaximumforslitfilmwoven(#30sieve).0.30(ASTM04751)mmmaximumforallothergeotextiletypes(#50sieve).0.15mmminimumforallfabrictypes(#100sieve).WaterPermlttlvltyO.OsecmInImum(ASTMD4491)GrabTensileStrength180lbs.Minimumforextrastrengthfabric.(ASTM04632)100lbsminimumforstandardstrengthfabric.GrabTensileStrength30%maximum(ASTMD4632)UltravioletResistance70%niinimum(ASTMD4355)•Supportstandardstrengthfabricswithwiremesh,chickenwire,2-inchx2-inchwire,safety’fence,orjutemeshtoincreasethestrengthofthedianeCons/rue/jo,;S/ornzitaterPollu/ioizPieen/ionaus!2012 •fabric.Siltfencematerialsareavailablethathavesyntheticmeshbackingattached.Filterfabricmaterialshallcontainultravioletrayinhibitorsandstabilizerstoprovideaminimumofsixmonthsofexpectedusableconstructionlifeatatemperaturerangeof0°F.to120°F.•One-hundredpercentbiodegradablesiltfenceisavailablethatisstrong,longlasting,andcanbeleftinplaceaftertheprojectiscompleted,ifpermittedbylocalregulations.•RefertoFigure4.2.12forstandardsiltfencedetails.IncludethefollowingstandardNotesforsiltfenceonconstructionplansandspecifications:1.ThecontractorshallinstallandmaintaintemporarysiltfencesatthelocationsshowninthePlans.2.Constructsiltfencesinareasofclearing.grading,ordrainagepriortostartingthoseactivities.3.Thesiltfenceshallhavea2-feetmm.anda2Y2-feetmax.heightabovetheoriginalgroundsurface.4.Thefilterfabricshallbesewntogetheratthepointofmanufacturetoformfilterfabriclengthsasrequired.Locateallsewnseamsatsupportposts.Alternatively,twosectionsofsiltfencecanbeoverlapped,providedtheContractorcandemonstrate,tothesatisfactionoftheEngineer,thattheoverlapislongenoughandthattheadjacentfencesectionsarecloseenoughtogethertopreventsiltladenwaterfromescapingthroughthefenceattheoverlap.5.Attachthefilterfabricontheup-slopesideofthepostsandsecurewithstaples,wire,orinaccordancewiththemanufacturersrecommendations.Attachthefilterfabrictothepostsinamannerthatreducesthepotentialfortearing.6.Supportthefilterfabricwithwireorplasticmesh,dependentonthepropertiesofthegeotextileselectedforuse.Ifwireorplasticmeshisused,fastenthemeshsecurelytotheup-slopesideofthepostswiththefilterfabricup-slopeofthemesh.7.Meshsupport,ifused,shallconsistofsteelwirewithamaximummeshspacingof2-inches,oraprefabricatedpolymericmesh.Thestrengthofthewireorpolymericmeshshallbeequivalenttoorgreaterthan180lbs.grabtensilestrength.Thepolymericmeshmustbeasresistanttothesamelevelofultravioletradiationasthefilterfabricitsupports.8.Burythebottomofthefilterfabric4-inchesmibelowthegroundsurface.Backfillandtampsoilinplaceovertheburiedportionofthefilterfabric,sothatnoflowcanpassbeneaththefenceandohitneConstructionStonnit’oterPollutionPieen/ionuus!2012U •scouringcannotoccur.Whenwireorpolymericback-upsupportmeshisused,thewireorpolymericmeshshallextendintotheground3-inchesmm.9.Driveorplacethefencepostsintotheground18-inchesmm.A12—inchmm.depthisallowediftopsoilorothersoftsubgradesoilisnotpresentand18-inchescannotbereached.Increasefencepostmm.depthsby6inchesifthefenceislocatedonslopesof3H:IVorsteeperandtheslopeisperpendiculartothefence.Ifrequiredpostdepthscannotbeobtained,thepostsshallbeadequatelysecuredbybracingorguyingtopreventoverturningofthefenceduetosedimentloading.10.Usewood,steelorequivalentposts.Thespacingofthesupportpostsshallbeamaximumof6-feet.Postsshallconsistofeither:•Woodwithdimensionsof2-inchesby2-incheswidemm.anda3-feetmm.length.Woodpostsshallbefreeofdefectssuchasknots,splits,orgouges.•No.6steelrebarorlarger.•ASTMA120steelpipewithaminimumdiameterof1-inch.•U,T,L,orCshapesteelpostswithaminimumweightof1.35lbs./ft.•Othersteelpostshavingequivalentstrengthandbendingresistancetothepostsizeslistedabove.11.Locatesiltfencesoncontourasmuchaspossible,exceptattheendsofthefence,wherethefenceshallbeturneduphillsuchthatthesiltfencecapturestherunoffwaterandpreventswaterfromflowingaroundtheendofthefence.12.Ifthefencemustcrosscontours,withtheexceptionoftheendsofthefence,placegravelcheekdamsperpendiculartothebackofthefencetominimizeconcentratedflowanderosion.Theslopeofthefencelinewherecontoursmustbecrossedshallnotbesteeperthan311:1V.•Gravelcheckdamsshallbeapproximately1-footdeepatthebackofthefence.Gravelcheckdamsshallbecontinuedperpendiculartothefenceatthesameelevationuntilthetopofthecheckdarninterceptsthegroundsurfacebehindthefence.•Gravelcheckdamsshallconsistofcrushedsurfacingbasecourse,gravelbackfillforwalls,orshoulderballast.Gravelcheckdamsshallbelocatedevery10feetalongthefencewherethefencemustcrosscontours.RefertoFigure4.2.13forslicingmethoddetails.Siltfenceinstallationusingtheslicingmethodspecifications:olumeConstructionStor,niiaierPollutionPieen/ia,;iius!2012I •1.Thebaseofbothendpostsmustbeatleast2-to4-inchesabovethetopofthefilterfabriconthemiddlepostsforditchcheckstodrainproperly.Useahandlevelorstringlevel,ifnecessan’,tomarkbasepointsbeforeinstallation.2.Installposts3-to4-feetapartincriticalretentionareasand6-to7-feetapartinstandardapplications.3.Installposts24-inchesdeeponthedownstreamsideofthesiltfence,andascloseaspossibletothefilterfabric,enablingpoststosupportthefilterfabricfromupstreamwaterpressure.4.Installpostswiththenipplesfacingawayfromthefilterfabric.5.Attachthefilterfabrictoeachpostwiththreeties,allspacedwithinthetop8-inchesofthefilterfabric.Attacheachtiediagonally45degreesthroughthefilterfabric,witheachpunctureatleast1-inchverticallyapart.Eachtieshouldbepositionedtohangonapostnipplewhentighteningtopreventsagging.6.Wrapapproximately6-inchesoffabricaroundtheendpostsandsecurewith3ties.7.Nomorethan24-inchesofa36-inchfilterfabricisallowedabovegroundlevel.Compactthesoilimmediatelynexttothefilterfabricwiththefrontwheelofthetractor,skidsteer,orrollerexertingatleast60poundspersquareinch.Compacttheupstreamsidefirstandtheneachsidetwiceforatotaloffourtrips.Checkandcorrectthesiltfenceinstallationforanydeviationbeforecompaction.Useaflat-bladedshoveltotuckfabricdeeperintothegroundifnecessary.oIiiiiwCo,,sir,,ctio,zStomnnrale,PollutionPieentionitits!2012 •RepairanydamageimmediatelyStandards•Interceptandconveyallevidentconcentratedflowsuphillofthesiltfencetoasedimentpond.•Checktheuphillsideofthefenceforsignsofthefencecloggingandactingasabarriertoflowandthencausingchannelizationofflowsparalleltothefence.Ifthisoccurs,replacethefenceorremovethetrappedsediment.olu;neConstructionStormwa!erPollutionPieen/ioniius!2012Afabi/e:anceFigure4.2.13—SiltFenceInstallationbySlicingMethod •.Removesedimentdepositswhenthedepositreachesapproximatelyone-thirdtheheightofthesiltfence,orinstallasecondsiltfence.Replacefilterfabricthathasdeterioratedduetoultravioletbreakdown.BMPC234:VegetatedStripPurposeVegetatedstripsreducethetransportofcoarsesedimentfromaconstructionsitebyprovidingatemporaryphysicalbarriertosedimentandreducingtherunoffvelocitiesofoverlandflow.ConditionsofUseaVegetatedstripsmaybeuseddownslopeofalldisturbedareas.Vegetatedstripsarenotintendedtotreatconcentratedflows,noraretheyintendedtotreatsubstantialamountsofoverlandflow.Anyconcentratedflowsmustbeconveyedthroughthedrainagesystemtoasedimentpond.Theonlycircumstanceinwhichoverlandflowcanbetreatedsolelybyastrip,ratherthanbyasedimentpond,iswhenthefollowingcriteriaaremet(seeTable4.2.4):Table4.2.4ContributingDrainageAreaforVegetatedStripsAraCanriinAraConriinaraMaConriinaraSoPrnSoaraFoaLnI.5H:IVorflatter67%orflatter100feet2H:1Vorflatter50%orflatter115feet4H:IVorflatter25%orflatter150feet6H:IVorflatter16.7%orflatter200feetIOH:IVorflatterI10%orflatter250feetDesignand•Thevegetatedstripshallconsistofaminimumofa25-footflowpathInstallationlengthcontinuousstripofdensevegetationwithtopsoil.Grass-Specjflcationscovered,landscapedareasaregenerallynotadequatebecausethevolumeofsedimentoverwhelmsthegrass.Ideally,vegetatedstripsshallconsistofundisturbednativegrowthwithawell-developedsoilthatallowsforinfiltrationofrunoff.•Theslopewithinthestripshallnotexceed4H:lV.•Theuphillboundaryofthevegetatedstripshallbedelineatedwithclearinglimits.Maintenance•AnyareasdamagedbyerosionorconstructionactivityshallbeStandardsseededimmediatelyandprotectedbymulch.•Ifmorethan5feetoftheoriginalvegetatedstripwidthhashadvegetationremovedorisbeingeroded,sodmustbeinstalled.•Ifthereareindicationsthatconcentratedflowsaretravelingacrossthebuffer,surfacewatercontrolsmustbeinstalledtoreducetheflowsohnneConstructionStornni’a/erPollutionPieen/ioniius!20)2 enteringthebuffer,oradditionalperimeterprotectionmustbeinstalled.BMPC235:WafflesPurposeWattlesaretemporan’erosionandsedimentcontrolbarriersconsistingofstraw,compost,orothermaterialthatiswrappedinbiodegradabletubularplasticorsimilarencasingmaterial.Theyreducethevelocityandcanspreadtheflowofnhandsheetrunoff,andcancaptureandretainsediment.Wattlesaretypically8to10inchesindiameterand25to30feetinlength.Wattlesareplacedinshallowtrenchesandstakedalongthecontourofdisturbedornewlyconstructedslopes.SeeFigure4.2.14fortypicalconstructiondetails.WSDOTStandardPlan1-30.30-00alsoprovidesinformationonWattles(http://wv.wsdot.wa.uov/Desien/Standards/Plans.htm#Section1)ConditionsofUse•Usewattles:•Indisturbedareasthatrequireimmediateerosionprotection.•Onexposedsoilsduringtheperiodofshortconstructiondelays.oroverwintermonths.•Onslopesrequiringstabilizationuntilpermanentvegetationcanbeestablished.•Thematerialuseddictatestheeffectivenessperiodofthewattle.Generally,Wattlesaretypicallyeffectiveforonetotwoseasons.•Preventrilhingbeneathwattlesbyproperlyentrenchingandabuttingwattlestogethertopreventwaterfrompassingbetweenthem.DesignCriteria•Installwattlesperpendiculartotheflowdirectionandparalleltotheslopecontour.•Narrowtrenchesshouldbedugacrosstheslopeoncontourtoadepthof3-to5-inchesonclaysoilsandsoilswithgradualslopes.Onloosesoils,steepslopes,andareaswithhighrainfall,thetrenchesshouldbedugtoadepthof5-to7-inches,or1/2to2/3ofthethicknessofthewattle.•Startbuildingtrenchesandinstallingwattlesfromthebaseoftheslopeandworkup.Spreadexcavatedmaterialevenlyalongtheuphillslopeandcompactedusinghandtampingorothermethods.•Constructtrenchesatintervalsof10-to25-feetdependingonthesteepnessoftheslope,soiltype,andrainfall.Thesteepertheslopetheclosertogetherthetrenches.•Installthewattlessnuglyintothetrenchesandabuttightlyendtoend.Donotoverlaptheends.•Installstakesateachendofthewattle,andat4-footcentersalongentirelengthofwattle.ohmicConslruclioiiStornn:’aterPollutionPieentioniius!2012 ••Ifrequired,installpilotholesforthestakesusingastraightbartodriveholesthroughthewattleandintothesoil.•Woodenstakesshouldbeapproximately3/4x3/4x24inchesmm.WilLowcuttingsor3/8-inchrebarcanalsobeusedforstakes.•Stakesshouldbedriventhroughthemiddleofthewattle,leaving2to3inchesofthestakeprotrudingabovethewattle.Mainteiiaiice•WattlesmayrequiremaintenancetoensuretheyareincontactwithStandardssoilandthoroughlyentrenched,especiallyaftersignificantrainfallonsteepsandysoils.ohmicCons/inc/ionS/or,,nvalc,’PothdionPieen/iouuits!2012 .StrawRollsMustBePlacedAlongSlopeContoursFigure4.2.14—Wattles10-25’(3-em)SedIment,organIcmatter,—andnativeseedsarecapturedbehindtherolis.SpacIngDependsonSoilTypeandSlopeSteepnessLive3’5”(75.125mm)8’-lO’DIA.1”Xl”Stakenottoscale(25x25mm)NOTE:1.Struwrollinstallationrequirestheplacementandsecurestakingoftherollinafrench,3-5’(75-125mm)deep,dugoncontour.runoffmustnotbeallowedtorununderoraroundroil.ohmicCons/inc/jo,;Stonmiak,-PollutionPieentionUUS!2012 •.Inspecttheslopeaftersignificantstormsandrepairanyareaswherewattlesarenottightlyabuttedorwaterhasscouredbeneaththewattles.ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquiva!entC235.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecy.wa.gov/prourams/wg/stormwater/newtech/eguivalent.htmlBMPC236:VegetativeFiltrationPurposeVegetativeFiltrationmaybeusedinconjunctionwithBMPC241TemporarySedimentPonds,BMPC206LevelSpreaderandapumpingsystemwithsurfaceintaketoimproveturbiditylevelsofstormwaterdischargesbyfilteringthroughexistingvegetationwhereundisturbedforestfloordufflayerorestablishedlawnwiththatchlayerarepresent.VegetativeFiltrationcanalsobeusedtoinfiltratedewateringwastefromfoundations,vaults,andtrenchesaslongasrunoffdoesnotoccur.ConditionsofUse•Foreveryfiveacreofdisturbedsoiluseoneacreofgrassfield,farmpasture,orwoodedarea.Reduceorincreasethisareadependingonprojectsize,groundwatertableheight,andothersiteconditions.•Wetlandsshallnotbeusedforfiltration.•DonotusethisBMPinareaswithahighgroundwatertable,orinareasthatwillhaveahighseasonalgroundwatertableduringtheuseofthisBMP.•ThisBMPmaybelesseffectiveonsoilsthatpreventtheinfiltrationofthewater,suchashardtill.•UsingothereffectivesourcecontrolmeasuresthroughoutaconstructionsitewillpreventthegenerationofadditionalhighlyturbidwaterandmayreducethetimeperiodorareaneedforthisBMP.•Stopdistributingwaterintothevegetatedareaifstandingwaterorerosionresults.DesignCriteria•Findlandadjacenttotheprojectthathasavegetatedfield,preferablyafarmfield,orwoodedarea.•Iftheprojectsitedoesnotcontainenoughvegetatedfieldareaconsiderobtainingpermissionfromadjacentlandowners(especiallyforfarmfields).•Installapumpanddownstreamdistributionmanifolddependingontheprojectsize.Generally,themaindistributionlineshouldreach100to200-feetlong(manylargeprojects,orprojectsontightsoil,willoliuneCons/rue/ionS/orn,ii’a/erPollutionPreen/ionitus!2012 requiresystemsthatreachseveralthousandfeetlongwithnumerousbranchlinesoffofthemaindistributionline).•Thernanifo)dshouWhaveseveralvalves,allowingforcontroloverthedistributionareainthefield.•Installseveralbranchesof4”schedule20.swaged-fitcommonseptictight-linedsewerline,or6”firehose,whichcanconveytheturbidwaterouttovarioussectionsofthefield.SecFiuure4.2.15.•Determinethebranchlengthbasedonthefieldareageographyandnumberofbranches.Typically,branchesstretchfrom200-feettoseveralthousandfeet.Always.laybranchesoncontourwiththeslope.•Onunevenground,sprinklersperformwell.Spacesprinklerheadssothatspraypatternsdonotoverlap.•Onrelativelyevensurfaces,alevelspreaderusing4-inchperforatedpipemaybeusedasanalternativeoptiontothesprinklerheadsetup.Installdrainpipeatthehighestpointonthefieldandatvariouslowerelevationstoensurefullcoverageofthefiltrationarea.Pipeshouldbeplacewiththeholesuptoallowforagentleweepingofstormwaterevenlyoutallholes.Levelingthepipebystakingandusingsandbagsmayberequired.•Topreventtheoversaturationofthefieldarea,rotatetheuseofbranchesorsprayheads.Dothisasneededbasedonmonitoringthesprayfield.•Monitorthesprayfieldonadailybasistoensurethatoversaturationofanyportionofthefielddoesn’toccuratanytime.Thepresenceofstandingpuddlesofwaterorcreationofconcentratedflowsvisuallysignithatoversaturationofthefieldhasoccurred.•Sincetheoperatorishandlingcontaminatedwater,physicallymonitorthevegetatedsprayfieldallthewaydowntothenearestsurfacewater,orfrrthestsprayarea,toensurethatthewaterhasnotcausedoverlandorconcentratedflows,andhasnotcreatederosionaroundthespraynozzle.•Monitoringusuallyneedstotakeplace3-5timesperdaytoensuresheet-flowintostatewaters.Donotexceedwaterqualitystandardsforturbidity.•Ecologystronglyrecommendsthatascparatcinspcctionlogbedeveloped,maintainedandkeptwith[heexistingsitelogbooktoaidtheoperatorconductinginspections.Thisseparate“FieldFiltrationLogbook”canalsoaidthefacilityindemonstratingcompliancewithpermitconditions.MahztenancL’•Inspectthespraynozzlesdaily,ataminimum,forleaksandpluggingStandardsfromsedimentparticles.olznneConstructionStonuwaterPollutionPit’en/ionuus!2012 •Iferosion,concentratedflows,oroversaturationofthefieldoccurs,rotatetheuseofbranchesorsprayheadsormovethebranchestoanewfieldlocation.•Checkallbranchesandthemanifoldforunintendedleaks.FlowpathGuidelinesforVegetativeFiltrationAverageSlopeAverageArea%SlopeEstimatedFlowpathLength{ft}1.SH:1V67%2502H:1V50%2004H:1V25%1506H:1V16.7%1151OH:1V10%100ohmicConstructionS/orn;it’atcrPollutionPieentionuus!2012100Figure4.2.15—ManifoldandBrachesinawooded,vegetatedsprayfield BMPC240:SedimentTrapPurposeAsedimenttrapisasmalltemporarypondingareawithagraveloutletusedtocollectandstoresedimentfromsitesclearedand/orgradedduringconstruction.Sedimenttraps,alongwithotherperimetercontrols,shallbeinstalledbeforeanylanddisturbancetakesplaceinthedrainagearea.(‘o,,djfjo,,sofUsePriortoleavingaconstructionsite,stormwaterrunoffmustpassthroughasedimentpondortraporotherappropriatesedimentremovalbestmanagementpractice.Non-engineeredsedimenttrapsmaybeusedon-sitepriortoanengineeredsedimenttraporsedimentpondtoprovideadditionalsedimentremovalcapacity.Itisintendedforuseonsiteswherethetributarydrainageareaislessthan3acres,withnounusualdrainagefeatures,andaprojectedbuild-outtimeofsixmonthsorless.Thesedimenttrapisatemporarymeasure(withadesignlifeofapproximately6months)andshallbemaintaineduntilthesiteareaispermanentlyprotectedagainsterosionbyvegetationand/orstructures.Sedimenttrapsandpondsareonlyeffectiveinremovingsedimentdowntoaboutthemediumsiltsizefraction.Runoffwithsedimentoffinergrades(finesiltandclay)willpassthroughuntreated,emphasizingtheneedtocontrolerosiontothemaximumextentfirst.Wheneverpossible,sediment-ladenwatershallbedischargedintoon-site,relativelylevel,vegetatedareas(seeBMPC234—VegetatedStrip).Thisistheonlywaytoeffectivelyremovefineparticlesfromrunoffunlesschemicaltreatmentorfiltrationisused.Thiscanbeparticularlyusefulafterinitialtreatmentinasedimenttraporpond.Theareasofreleasemustbeevaluatedonasite-by-sitebasisinordertodetermineappropriatelocationsforandmethodsofreleasingrunoff.Vegetatedwetlandsshallnotbeusedforthispurpose.Frequently,itmaybepossibletopumpwaterfromthecollectionpointatthedownhillendofthesitetoanupslopevegetatedarea.Pumpingshallonlyaugmentthetreatmentsystem,notreplaceit,becauseofthepossibilityofpumpfailureorrunoffvolumeinexcessofpumpcapacity.Allprojectsthatareconstructingpermanentfacilitiesforrunoffquantitycontrolshouldusetherough-gradedorfinal-gradedpermanentfacilitiesfortrapsandponds.Thisincludescombinedfacilitiesandinfiltrationfacilities.Whenpermanentfacilitiesareusedastemporarysedimentationfacilities,thesurfacearearequirementofasedimenttraporpondmustbemet.Ifthesurfacearearequirementsarelargerthanthesurfaceareaofthepermanentfacility,thenthetraporpondshallbeenlargedtocomplywiththesurfacearearequirement.Thepermanentpondshallalsobedividedintotwocellsasrequiredforsedimentponds.olwneCons/rue/jo,,S!ornni’aterPollutionPieen/ioniius!2012101 Eitherapermanentcontrolstructureorthetemporarycontrolstructure(describedinBMPC241,TemporarySedimentPond)canbeused.Ifapermanentcontrolstructureisused,itmaybeadvisabletopartiallyrestrictthelowerorificewithgraveltoincreaseresidencetimewhilestillallowingdewateringofthepond.Ashut-offvalvemaybeaddedtothecontrolstructuretoallowcompleteretentionofstormwaterinemergencysituations.Inthiscase,anemergencyoverflowweirmustbeadded.AskimmermaybeusedforthesedimenttrapoutletifapprovedbytheLocalPermittingAuthority.Designand•SeeFiaures4.2.16and4.2.17fordetails.Installation.Specjfications•Ifpermanentrunoffcontrolfacilitiesarepartoftheproject,theyshouldbeusedforsedimentretention.Todeterminethesedimenttrapgeometry,firstcalculatethedesignsurfacearea(SA)ofthetrap,measuredattheinvertoftheweir.Usethefollowingequation:S=S(2!)where2=Designinflowbasedonthepeakdischargefromthedeveloped2-yearrunoffeventfromthecontributingdrainageareaascomputedinthehydrologicanalysis.The10-yearpeakflowshallbeusediftheprojectsize,expectedtiminganddurationofconstruction,ordownstreamconditionswarrantahigherlevelofprotection.Ifnohydrologicanalysisisrequired,theRationalMethodmaybeused.=Thesettlingvelocityofthesoilparticleofinterest.The0.02mm(mediumsilt)particlewithanassumeddensityof2.65g/cm3hasbeenselectedastheparticleofinterestandhasasettlingvelocity(.)of0.00096ft/sec.S=Asafetyfactorof2toaccountfornon-idealsettling.Therefore,theequationforcomputingsurfaceareabecomes:S=2x2/0.00096or2080squarefeetpercfsofinflowNote:Evenifpermanentfacilitiesareused,theymuststillhaveasurfaceareathatisatleastaslargeasthatderivedfromtheaboveformula.Iftheydonot,thepondmustbeenlarged.Toaidindeterminingsedimentdepth,allsedimenttrapsshallhaveastaffgaugewithaprominentmark1-footabovethebottomofthetrap.oheineConstructionS/ornni’a/erPollutionPieen/ionitits!2012102 Sedimenttrapsmaynotbefeasibleonutilityprojectsduetothelimitedworkspaceortheshort-termnatureofthework.Portabletanksmaybeusedinplaceofsedimenttrapsforutility’projects.A’IuintenanceStandards•Sedimentshallberemovedfromthetrapwhenitreaches1-footindepth.Anydamagetothepondembankmentsorslopesshallberepaired.SurfaceareadeterminedattopofweirFigure4.2.17—SedimentTrapOutletohuneConstructionStor,nii’aterPollutionPit’en/ion10itits!20123515FlatBottom4MmW’-1.5Vtashedgravel\2.4RockRipRapNote:TrapmaybeformedbybermorbypartialorcompleteexcavationGeotextileFigure4.2.16—CrossSectionofSedimentTrapDischargetostabilizedconveyance,outlet,orlevelspreaderI6Mm.Nativesoilorcompactedbackfill1’Mm.depthoverflowspillway BMPC241:TemporarySedimentPondPurposeSedimentpondsremovesedimentfromrunofforiginatingfromdisturbedareasofthesite.Sedimentpondsaretypicallydesignedtoremovesedimentnosmallerthanmediumsilt(0.02mm).Consequently,theyusuallyreduceturbidityonlyslightly.ConditionsofUsePriortoleavingaconstructionsite,stormwaterrunoffmustpassthroughasedimentpondorotherappropriatesedimentremovalbestmanagementpractice.Asedimentpondshallbeusedwherethecontributingdrainageareais3acresormore.Pondsmustbeusedinconjunctionwitherosioncontrolpracticestoreducetheamountofsedimentflowingintothebasin.Designand•SedimentbasinsmustbeinstalledonlyonsiteswherefailureofdieI,,sta!!ationstructurewouldnotresultinlossoflife,damagetohomesorSpecificationsbuildings,orinterruptionofuseorserviceofpublicroadsorutilities.Also,sedimenttrapsandpondsareattractivetochildrenandcanbeverydangerous.Compliancewithlocalordinancesregardinghealthandsafetymustbeaddressed.Iffencingofthepondisrequired,thetypeoffenceanditslocationshallbeshownontheESCplan.•Structureshavingamaximumstoragecapacityatthetopofthedamof10acre-ft(435,600ft3)ormorearesubjecttotheWashingtonDamSafetyRegulations(Chapter173-175WAC).•SeeFines4.2.18,4.2.19,and4.2.20fordetails.•Ifpermanentrunoffcontrolfacilitiesarepartoftheproject,theyshouldbeusedforsedimentretention.Thesurfacearearequirementsofthesedimentbasinmustbemet.Thismayrequiretemporarilyenlargingthepermanentbasinlocomplywiththesurfacearearequirements.Thepermanentcontrolstructuremustbetemporarilyreplacedwithacontrolstructurethatonlyallowswatertoleavethepondfromthesurfaceorbypumping.Thepermanentcontrolstructuremustbeinstalledafterthesiteisfillystabilized.•Useofinfiltrationfacilitiesforsedimentationbasinsduringconstructiontendstoclogthesoilsandreducetheircapacity’toinfiltrate.Ifinfiltrationfacilitiesaretobeused,thesidesandbottomofthefacilitymustonlyberoughexcavatedtoaminimumof2feetabovefinalgrade.Finalgradingof11winfiltrationfacilityshalloccuronlywhenallcontributingdrainageareasarefullystabilized.Theinfiltrationpretreatmentfacility’shouldbefillyconstructedandusedwiththesedimentationbasintohelppreventclogging.•DeterminingPondGeometryObtainthedischargefromthehydrologiccalculationsofthcpcakflowforthe2-yearrunoffevent(2).The10-yearpeakflowshallbeusedifohmicConstructionSlormwatcrPollutionPieen/ioniius!201210 theprojectsize,expectedtiminganddurationofconstruction,ordownstreamconditionswarrantahigherlevelofprotection.Ifnohydrologicanalysisisrequired,theRationalMethodmaybeused.Determinetherequiredsurfaceareaatthetopoftheriserpipewiththeequation:S=2x2/0.00096or2080squarefeetpercfsofinflowSeeBMPC240formoreinformationonthederivationofthesurfaceareacalculation.Thebasicgeometryofthepondcannowbedeterminedusingthefollowingdesigncriteria:•RequiredsurfaceareaSA(fromStep2above)attopofriser.•Minimum3.5-footdepthfromtopofrisertobottomofpond.•Maximum3H:IVinteriorsideslopesandmaximum2H:IVexteriorslopes.Theinteriorslopescanbeincreasedtoamaximumof2H:IViffencingisprovidedatorabovethemaximumwatersurface.•Onefootoffreeboardbetweenthetopoftheriserandthecrestoftheemergencyspillway.•Flatbottom.•Minimum1-footdeepspillway.•Length-to-widthratiobetween3:1and6:1.•SizingofDischargeMechanisms.Theoutletforthebasinconsistsofacombinationofprincipalandemergencyspiliways.Theseoutletsmustpassthepeakrunoffexpectedfromthecontributingdrainageareafora100-yearstorm.If,duetositeconditionsandbasingeometry,aseparateemergencyspill-wayisnotfeasible,theprincipalspillwaymustpasstheentirepeakrunoffexpectedfromthe100-yearstorm.However,anattempttoprovideaseparateemergencyspillwayshouldalwaysbemade.Therunoffcalculationsshouldbebasedonthesiteconditionsduringconstruction.Theflowthroughthedewateringorificecannotbeutilizedwhencalculatingthe100-yearstormelevationbecauseofitspotentialtobecomeclogged;therefore,availablespillwaystoragemustbeginattheprincipalspillwayrisercrest.Theprincipalspiliwaydesignedbytheprocedurescontainedinthisstandardwillresultinsomereductioninthepeakrateofrunoff.However,theriseroutletdesignwillnotadequatelycontrolthebasindischargetothepredevelopmentdischargelimitationsasstatedinMinimumRequirement#7:FlowControl.However,ifthebasinforapermanentstormwaterdetentionpondisusedforatemporaryohinwCons/ruclionS/onnii’a/erPoihilionPieen/ioniius!2012I0 sedimentationbasin,thecontrolstructureforthepermanentpondcanbeusedtomaintainpredevelopmentdischargelimitations.Thesizeofthebasin,theexpectedlifeoftheconstructionproject,theanticipateddownstreameffectsandtheanticipatedweatherconditionsduringconstruction,shouldbeconsideredtodeterminetheneedofadditionaldischargecontrol.SeeFigure4.2.21forriserinflowcurves.Figure4.2.19—SedimentPondCrossSectionohuneCons/rue/ionS/oniii’olctP0111(1ionPieen/ion10itus!2012Note:PondmaybeformedbybermorbypartialorcempleteexcavationDischargetostabilizedconveyance,outlet,orlevelspreaderFigure4.2.18—SedimentPondPlanViewRiserpipe(principalspitway)openattopwithtrashrackDewateringdevice(seeriserdetail)CrestofWrebacked&ltn1=1DewaternIIschargetostabizedstakedhaybaleswrappedorificeconveyanceoutletorwithfilterfabric,orlevelspreaderequivalentdividerConcretebase(seeriserdetail) Pclyelr.ylerecaPrc.ideade1aaeFigure4.2.20—SedimentPondRiserDetailohtnwConstructionSiornniatcrPollutionRn’entioniiits!201210Peioaedpolyalnylenedairaetib4nadamalermU,2IrgorliendewaledngQhfica,TubingshallcamptyASTMF667andAASHTOA294DewatedngcrWe.zhedule,40eeleubmm.DiameteraspercalcuIsonsAlternatively,metalstakesandAUSmaybeusedtopreventflotation 100C0UC,•7I..C,aa.0zUC0IncIa,0andHInfeetSlopechangeoccursatwdr-orificetransitionFigure4.2.21—RiserInflowCurvesohuneConstructionStormivaterPollutionPieen/ion10iius!2012.I__‘r/. ___iIIEEEEE100.1HEADINFEET(moasJredfromQ,,,=9.739DH”0a,iiicc820‘H112crestofriser)10 PriniaSiaDeterminetherequireddiameterfortheprincipalspillway(riserpipe).Thediametershallbetheminimumnecessarytopassthesite’s15-minute.10-yearflowrate.IfusingtheWesternWashingtonHydrologyModel(WWHM),Version2or3,designflowisthe10-year(Ihour)flowforthedeveloped(unmitigated)site,multipliedbyafactorof1.6.UseFigure4.2.21todeterminethisdiameter(=1-foot).oleennanen!con/nils/inc/L/remabeuseins/caoawi;iorarriser£rn0rfosiaDeterminetherequiredsizeanddesignoftheemergencyoverflowspillwayforthedeveloped100-yearpeakflowusingthemethodcontainedinVolumeIII.BarinOrifiDeterminethesizeofthedewateringorifice(s)(minimum1-inchdiameter)usingamodifiedversionofthedischargeequationforaverticalorificeandabasicequationfortheareaofacircularorifice.Determinetherequiredareaoftheorificewiththefollowingequation:—(2)fh—0.6x360005where=orificearea(squarefeet)=pondsurfacearea(squarefeet)=headofwateraboveorifice(heightofriserinfeet)=dewateringtime(24hours)accelerationofgravity(32.2feet/second2)ConverttherequiredsurfaceareatotherequireddiameterDoftheorifice:D=24xF=I3.54xThevertical,perforatedtubingconnectedtothedewateringorificemustbeatleast2incheslargerindiameterthantheorificetoimproveflowcharacteristics.Thesizeandnumberofperforationsinthetubingshouldbelargeenoughsothatthetubingdoesnotrestrictflow.Theorificeshouldcontroltheflowrate.AdditionalDesignSpecificationsThepondshallbedividedintotworoughlyequalvolumecellsbyapermeabledividerthatwillreduceturbulencewhileallowingmovementofwaterbetweencells.Thedividershallbeatleastone-halftheheightoftheriserandaminimumofonefootbelowthetopoftheriser.Wire-backed.2-to3-foothigh,extrastrengthfilterfabricsupportedbytreated4x4’scanbeusedasadivider.Alternatively,stakedstrawbaleswrappedwithfilterfabric(geotextile)maybeused.Ifthepondismorethan6feetdeep,adifferentmechanismmustbeproposed.AriprapembankmentisoneacceptablemethodofohiiiieCons/inc/ionS/or,nii’a!crFolly/ionPieeli/ionnus!201210 separationfordeeperponds.Otherdesignsthatsatisb’theintentofthisprovisionareallowedaslongasthedividerispermeable,structurallysound,anddesignedtopreventerosionunderoraroundthebarrier.Toaidindeterminingsedimentdepth,one-footintervalsshallbeprominentlymarkedontheriser.Ifanembankmentofmorethan6feetisproposed,thepondmustcomplywiththecriteriacontainedinVolumeIIIregardingdamsafetyfordetentionBMPs.•Themostcommonstructuralfailureofsedimentationbasinsiscausedbypiping.Pipingreferstotwophenomena:(1)waterseepingthroughfine-grainedsoil,erodingthesoilgrainbygrainandformingpipesortunnels;and,(2)waterunderpressureflowingupwardthroughagranularsoilwithaheadofsufficientmagnitudetocausesoilgrainstolosecontactandcapabilityforsupport.Themostcriticalconstructionsequencestopreventpipingwillbe:I.Tightconnectionsbetweenriserandbarrelandotherpipeconnections.2.Adequateanchoringofriser.3.Propersoilcompactionoftheembankmentandriserfooting.4.Properconstructionofanti-seepdevices.Maintenance•SedimentshallberemovedfromthepondwhenitreachesI—footinStandardsdepth.•Anydamagetothepondembankmentsorslopesshallberepaired.BMPC250:ConstructionStormwaterChemicalTreatmentPurposeThisRMPapplieswhenusingstormwaterchemicalsinbatchtreatmentorflow-throughtreatment.Turbidityisdifficulttocontroloncefineparticlesaresuspendedinslormwaterrunofffromaconstructionsite.Sedimentationpondsareeffectiveatremovinglargerparticulatematterbygravitysettling,butareineffectiveatremovingsmallerparticulatessuchasclayandfinesilt.TraditionalerosionandsedimentcontrolBMPsmaynotbeadequatetoensurecompliancewiththewaterqualitystandardsforturbidityinreceivingwater.Chemicaltreatmentcanreliablyprovideexceptionalreductionsofturbidityandassociatedpollutants.Chemicaltreatmentmayberequiredtomeetturbiditystormwaterdischargerequirements,especiallywhenconstructionistoproceedthroughthewetseason.ConditionsofUseFormalwrittenapprovalfromEcologyisrequiredfortheuseofchemicaltreatmentregardlessofsitesize.TheLocalPermittingAuthoritymayalsoolzmwConstrue/jonStornnra!erPollu/jo;,Preentionuus!2012110 •requirereviewandapproval.Whenapproved,thechemicaltreatmentsystemsmustbeincludedintheConstructionStormwaterPollutionPreventionPlan(SWPPP).DesignandSeeAppendixTI-Bforbackgroundinformationonchemicaltreatment.InstallalionSpecjficationsCr1naforCiaTraxiProdUChemicallytreatedstornnvaterdischargedfromconstructionsitesmustbenontoxictoaquaticorganisms.TheChemicalTechnologyAssessmentProtocol(CTAPE)mustbeusedtoevaluatechemicalsproposedforstormwatertreatment.OnlychemicalsapprovedbyEcologyundertheCTAPEmaybeusedforstonmvatertreatment.Theapprovedchemicals,theirallowableapplicationtechniques(batchtreatmentorflow-throughtreatment),allowableapplicationrates,andconditionsofusecanbefoundattheDepartmentofEcologyEmergingTechnologieswebsite:http://4”ww.ecv.wa.tzov/proErams/;vg/stormwater/newtechItechnolrndes.html.TranSDIxiConIdraionThedesignandoperationofachemicaltreatmentsystemshouldtakeintoconsiderationthefactorsthatdetermineoptimum,cost-effectiveperformance.Itisimportanttorecognizethefollowing:•OnlyEcologyapprovedchemicalsmaybeusedandmustfollowapproveddoserate.•ThepHofthestormwatermustbeintheproperrangeforthepolymerstobeeffective,whichistypically6.5to8.5•Thecoagulantmustbemixedrapidlyintothewatertoensureproperdispersion.•Aflocculationstepisimportanttoincreasetherateofsettling.toproducethelowestturbidity,andtokeepthedosagerateaslowaspossible.•Toolittleenergyinputintothewaterduringtheflocculationphaseresultsinflocsthataretoosmalland/orinsufficientlydense.Toomuchenergycanrapidlydestroyflocasitisformed.•Caremustbetakeninthedesignofthewithdrawalsystemtominimizeoutflowvelocitiesandtopreventbcdischarge.Dischargefromabatchtreatmentsystemshouldbedirectedthroughaphysicalfiltersuchasavcgctatcdswalcthatwouldcatchanyunintendedflocdischarge.Currently.flow-throughsystemsalwaysdischargethroughthechemicallyenhancedsandfiltrationsystem.•Systemdischargeratesmusttakeintoaccountdownstreamconveyanceintegrity.ohnneConstructionStor,niIa/crPollutionPreen/ionitus!2012Ill PurliaTranProDriionAbatchchemicaltreatmentsystemconsistsofthestormwatercollectionsystem(eithertemporarydiversionorthepermanentsitedrainagesystem).astoragepond.pumps.achemicalfeedsystem,treatmentcells,andinterconnectingpiping.Thebatchtreatmentsystemshalluseaminimumoftwolinedtreatmentcellsinadditiontoanuntreatedstonmvaterstoragepond.Multipletreatmentcellsallowforclarificationoftreatedwaterwhileothercellsarebeingfilledoremptied.Treatmentcellsmaybepondsortanks.Pondswithconstructedearthenembankmentsgreaterthansixfeethighorwhichimpoundmorethan10acre-feetrequirespecialengineeringanalyses.TheEcologyDamSafetySectionhasspecificdesigncriteriafordamsinWashingtonState(seelittp://www.ecy.wa.gov/prorams/wr/dams/GuidanceDocs.html).Stormwateriscollectedatinterceptionpoint(s)onthesiteandisdivertedbygravityorbypumpingtoanuntreatedstormwaterstoragepondorotheruntreatedstormwaterholdingarea.Thestormwaterisstoreduntiltreatmentoccurs.Itisimportantthattheholdingpondbelargeenoughtoprovideadequatestorage.ThefirststepinthetreatmentsequenceistocheckthepHofthestormwaterintheuntreatedstormwaterstoragepond.ThepHisadjustedbytheapplicationofcarbondioxideorabaseuntilthestormwaterinthestoragepondiswithinthedesiredpHrange,6.5to8.5.Whenused,carbondioxideisaddedimmediatelydownstreamofthetransferpump.Typicallysodiumbicarbonate(bakingsoda)isusedasabase,althoughotherbasesmaybeused.Whenneeded,baseisaddeddirectlytotheuntreatedstomiwaterstoragepond.Thestormwaterisrecirculatedwiththetreatmentpumptoprovidemixinginthestoragepond.InitialpHadjustmentsshouldbebasedondailybenchtests.FurtherpHadjustmentscanbemadeatanypointintheprocess.OncethestormwateriswithinthedesiredpHrange(dependantonpolymerbeingused),thestormwaterispumpedfromtheuntreatedstormwaterstoragepondtoatreatmentcellaspolymerisadded.Thepolymerisaddedupstreamofthepumptofacilitaterapidmixing.Afterpolymeraddition,thewateriskeptinalinedtreatmentcellforclarificationofthesediment-floc.Inabatchmodeprocess,clarificationtypicallytakesfrom30minutestoseveralhours.PriortodischargesamplesarewithdrawnforanalysisofpH,flocculentchemicalconcentration,andturbidity.Ifbothareacceptable,thetreatedwaterisdischarged.Severalconfigurationshavebeendevelopedtowithdrawtreatedwaterfromthetreatmentcell.TheoriginalconfigurationisadevicethatwithdrawsthetreatedwaterfromjustbeneaththewatersurfaceusingaolunieCons/nw/iouS/ornnra/erPollutionPreen/ionuus!2012111 floatwithadjustablestrutsthatpreventthefloatfromsettlingonthecellbottom.Thisreducesthepossibilityofpickingupsedirnent-flocfromthebottomofthepond.Thestrutsareusuallysetataminimumclearanceofabout12inches;thatis,thefloatwillcomewithin12inchesofthebottomofthecell.Othersystemshaveusedverticalguidesorcableswhichconstrainthefloat,allowingittodriftupanddownwiththewaterlevel.MorerecentdesignshaveanH-shapedarrayofpipes,setonthehorizontal.Thisschemeprovidesforwithdrawalfromfourpointsratherthanone.Thisconfigurationreducesthelikelihoodofsuckingsettledsolidsfromthebottom.Italsoreducesthetendencyforavortextoform.Inletdifftisers,alongfloatingorfixedpipewithmanysmallholesinit,arealsoanoption.Safetyisaprimaryconcern.Designshouldconsiderthehazardsassociatedwithoperations.suchassampling.Facilitiesshouldbedesignedtoreducesliphazardsanddrowning.Tanksandpondsshouldhaveliferings,ladders,orstepsextendingfromthebottomtothetop.PorHaTranProDriionAtaminimum,aflow-throughchemicaltreatmentsystemconsistsofthestormwatercollectionsystem(eithertemporary’diversionorthepermanentsitedrainagesystem),anuntreatedstormwaterstoragepond,andthechemicallyenhancedsandfiltrationsystem.Stormwateriscollectedatinterceptionpoint(s)onthesiteandisdivertedbygravityorbypumpingtoanuntreatedstormwaterstoragepondorotheruntreatedstormwaterholdingarea.Thestormwaterisstoreduntiltreatmentoccurs.Itisimportantthattheholdingpondbelargeenoughtoprovideadequatestorage.Stormwateristhenpumpedfromtheuntreatedstormwaterstoragepondtothechemicallyenhancedsandfiltrationsystemwherepolymerisadded.Adjustmentstop1-1maybenecessary’beforechemicaladdition.ThesandfiltrationsystemcontinuallymonitorsthestorniwaterforturbidityandpH.Ifthedischargewateriseveroutofanacceptablerangeforturbidityorp1-i,thewaterisrecycledtotheuntreatedstormwaterpondwhereitcanberetreated.Forhatchtreatmentandflow—throng!:treatment,thcfollowingcquipmcntshouldbelocatedinalockableshed:•Thechemicalinjector.•Secondarycontainmentforacid,caustic,bufferingcompound,andtreatmentchemical.•Emergencyshowerandeyewash.•MonitoringequipmentwhichconsistsofapHmeterandaturbidimeter.ohmicConstructionStonnit’aterPollutionPit’en/iouuus!201211 SSun:Certainsitesarerequiredtoimplementflowcontrolforthedevelopedsites.Thesesitesmustalsocontrolstormwaterreleaseratesduringconstruction.Generally,thesearesitesthatdischargestormwaterdirectly,orindirectly,throughaconveyancesystem,intoafreshwater.Systemsizingisdependentonflowcontrolrequirements.SiinCr1riaforBaTranSforFoConroEWarBodiThetotalvolumeoftheuntreatedstormwaterstoragepondandtreatmentpondsortanksmustbelargeenoughtotreatstormwaterthatisproducedduringmultipledaystormevents.Itisrecommendedthatataminimumtheuntreatedstorrnwaterstoragepondbesizedtohold1.5timestherunoffvolumeofthe10-year,24-hourstormevent.Bypassshouldbeprovidedaroundthechemicaltreatmentsystemtoaccommodateextremestormevents.RunoffvolumeshallbecalculatedusingthemethodspresentedinVolume3.Chapter2.Worst-caselandcoverconditions(i.e.,producingthemostrunoff)shouldbeusedforanalyses(inmostcases,thiswouldbethelandcoverconditionsjustpriortofinallandscaping).Primarysettlingshouldbeencouragedintheuntreatedstormwaterstoragepond.Aforebaywithaccessformaintenancemaybebeneficial.Therearetwoopposingconsiderationsinsizingthetreatmentcells.Alargercellisabletotreatalargervolumeofwatereachtimeabatchisprocessed.However,thelargerthecellthelongerthetimerequiredtoempty’thecell.Alargercellmayalsobelesseffectiveatflocculationandthereforerequirealongersettlingtime.Thesimplestapproachtosizingthetreatmentcellistomultiplytheallowabledischargeflowratetimesthedesireddrawdowntime.A4-hourdrawdowntimeallowsonebatchpercellper8-hourworkperiod,given1hourofflocculationfollowedbytwohoursofsettling.IfthedischargeisdirectlytoaflowcontrolexemptreceivingwaterlistedinAppendix1-EofVolumeIortoaninfiltrationsystem,thereisnodischargeflowlimit.Pondssizedforflowcontrolwaterbodiesmustataminimummeetthesizingcriteriaforflowcontrolexemptwaters.SiinCririaforFo-TroTranSforFoConroEWarBodiWhensizingstoragepondsortanksforflow-throughsystemsforflowcontrolexemptwaterbodies,thetreatmentsystemcapacityshouldbeafactor.Theuntreatedstormwaterstoragepondortankshouldbesizedtohold1.5timestherunoffvolumeofthe10-year,24-hourstormeventminusthetreatmentsystemflowrateforan8-hourperiod.Forachitosanenhancedsandfiltrationsystem,thetreatmentsystemflowrateshouldbesizedusingahydraulicloadingratebetween6-8gpm/ft2.OtherhydrauliccluineCo,zsfrz,c/jo,iS!onnii’alerPollulionPieentioniius!20)2I) loadingratesmaybemoreappropriateforothersystems.Bypassshouldbeprovidedaroundthechemicaltreatmentsystemtoaccommodateextremestorms.RunoffvolumeshallbecalculatedusingthemethodspresentedinVolume3,Chapter2.Worst-caselandcoverconditions(i.e..producingthemostrunoff)shouldbeusedforanalyses(inmostcases,thiswouldbethelandcoverconditionsjustpriortofinallandscaping).SiinCr1naforFoConroWarBodiSitesthatmustimplementflowcontrolforthedevelopedsiteconditionmustalsocontrolstormwaterreleaseratesduringconstruction.Constructionsitestormwaterdischargesshallnotexceedthedischargedurationsofdiepre-developedconditionfortherangeofpre-developeddischargeratesfrom¼ofthe2-yearflowthroughthe10-yearflowaspredictedbyanapprovedcontinuousrunoffmodel.Thepre-developedconditiontobematchedshallbethelandcoverconditionimmediatelypriortothedevelopmentproject.Thisrestrictiononreleaseratescanaffectthesizeofthestoragepondandtreatmentcells.ThefollowingishowWWHMcanbeusedtodeterminethereleaseratesfromthechemicaltreatmentsystems:1.Determinethepre-developedflowdurationstobematchedbyenteringtheexistinglanduseareaunderthe“Pre-developed”scenarioinWWHM.Thedefaultflowrangeisfrom¼ofthe2-yearflowthroughthe10-yearflow.2.Enterthepostdevelopedlanduseareainthe“DevelopedUnmitigated”scenarioinWWHM.3.Copythelanduseinformationfromthe“DevelopedUnmitigated”to“DevelopedMitigated”scenario.4.Whileinthe“DevelopedMitigated”scenario,addapondelementunderthebasinelementcontainingdiepost-developedlanduseareas.Thispondelementrepresentsinformationontheavailableuntreatedstormwaterstorageanddischargefromthechemicaltreatmentsystem.Incaseswherethedischargefromthechemicaltreatmentsystemiscontrolledbyapump,astage/storage/discharge(SSD)tablerepresentingthepondmustbegeneratedoutsideWWHMandimportedintoWWHM.WWI-JMcanroutetherunofffromthepost-developedconditionthroughthisSSDtable(thepond)anddeterminecompliancewithdieflowdurationstandard.ThiswouldbeaniterativedesignprocedurewhereiftheinitialSSDtableprovedtobeinadequate,thedesignerwouldhavetomodif’theSSDtableoutsideWWHMandre-importinWWHMandroutetherunoffthroughitagain.Theiterationwillcontinueuntilapondthatcomplieswiththeflowdurationstandardiscorrectlysized.NotesonSSDtablecharacteristics:ohuneCo,,s/n,c/ionStornnratcrPollutionPieentioniius!20]211 •Thepumpdischargeratewouldlikelybeinitiallysetatjustbelow‘/2ofthe2-yearflowfromthepre-developedcondition.Asrunoffcomingintotheuntreatedstormwaterstoragepondincreasesandtheavailableuntreatedstormwaterstoragevolumegetsusedup,itwouldbenecessarytoincreasethepumpdischargerateabove‘/2ofthe2-year.Theincrease(s)above‘/2ofthe2-yearmustbesuchthattheyprovidesomerelieftotheuntreatedstormwaterstorageneedsbutatthesametimewillnotcauseviolationsoftheflowdurationstandardatthehigherflows.ThefinaldesignSSDtablewillidentifytheappropriatepumpingratesandthecorrespondingstageandstorages.•V/henbuildingsuchaflowcontrolsystem,thedesignmustensurethatanyautomaticadjustmentstothepumpingrateswillbeasaresultofchangestotheavailablestorageinaccordancewiththefinaldesignSSDtable.5.Iishouldbenotedthattheaboveprocedureswouldbeusedtomeettheflowcontrolrequirements.Thechemicaltreatmentsystemmustbeabletomeettherunofftreatmentrequirements.Itislikelythatthedischargeflowrateof%ofthe2-yearormoremayexceedthetreatmentcapacity’ofthesystem.Ifthatisthecase,theuntreatedstormwaterdischargerate(s)(i.e.,influenttothetreatmentsystem)mustbereducedtoallowpropertreatment.Anyreductionintheflowswouldlikelyresultintheneedforalargeruntreatedstormwaterstoragevolume.Ifthedischargeistoamunicipalstormdrainagesystem.theallowabledischargeratemaybelimitedbythecapacityolthepublicsystem.Itmaybenecessarytocleanthemunicipalstormdrainagesystempriortothestartofthedischargetopreventscouringsolidsfromthedrainagesystem.lfthemunicipalstormdrainagesystemdischargestoawaterbodynotontheflowcontrolexemptlist,theprojectsiteissubjecttoflowcontrolrequirements.Obtainpermissionfromtheownerofthecollectionsystembeforedischargingtoit.Ifsystemdesigndoesnotallowyoutodischargeattheslowerratesasdescribedaboveandifthesitehasaretentionordetentionpondthatwillservetheplanneddevelopment,thedischargefromthetreatmentsystemmaybedirectedtothepermanentretention/detentionpondtocomplywiththeflowcontrolrequirement.Inthiscase,theuntreatedstormwaterstoragepondandtreatmentsystemwillbesizedaccordingtothesizingcriteriaforflow-throughtreatmentsystemsforflowcontrolexemptwaterbodiesdescribedearlierexceptalldischarge(waterpassingthroughthetreatmentsystemandstormwaterbypassingthetreatmentsystem)willbedirectedintothepermanentretention/detentionpond.Ifsiteconstraintsmakelocatingtheuntreatedstorrnwaterstorageponddifficult,thepermanentretention/detentionpondmaybedividedtoserveastheuntreatedstormwaterstoragepondandthepost-treatmentflowcontrolpond.AbermorbarriermustbeusedinthiscasesotheuntreatedwaterdoesnotmixwiththetreatedohuneConstructionStonnu’aterPollutionPieentionitits!201211 water.Bothuntreatedstormwaterstoragerequirements,andadequatepost-treatmentflowcontrolmustbeachieved.Thepost-treatmentflowcontrolpond’sreviseddimensionsmustbeenteredintotheWWHMandtheWWHMmustberuntoconfirmcompliancewiththeflowcontrolrequirement.MaintenanceMoniannAtaminimum,thefollowingmonitoringshallbeStandardsconducted.TestresultsshallbcrecordedonadailyJogkeptonsite.AdditionaltestingmayberequiredbytheNPDESpermitbasedonsiteconditions.OperationalMonitorinu:•Totalvolumetreatedanddischarged.•Flowmustbecontinuouslymonitoredandrecordedatnotgreaterthan15-minuteintervals.•TypeandamountofchemicalusedforpHadjustment.•Amountofpolymerusedfortreatment.•Settlingtime.ComplianceMonitoring:•InfluentandeffluentpH,flocculentchemicalconcentration,andturbiditymustbecontinuouslymonitoredandrecordedatnotgreaterthan15-minuteintervals.pHandturbidityofthereceivingwater.Biomonitoring:Treatedstormwatermustbenon-toxictoaquaticorganisms.Treatedstormwatermustbetestedforaquatictoxicityorresidualchemicals.FrequencyofbiomonitoringwillbedeterminedbyEcology.ResidualchemicaltestsmustbeapprovedbyEcologypriortotheiruse.Iftestingtreatedstormwaterforaquatictoxicity,youmusttestforacute(lethal)toxicity.BioassaysshallbeconductedbyalaboratojyaccreditedbyEcology,unlessotherwiseapprovedbyEcology.AcutetoxicitytestsshallbeconductedpertheCTAPEprotocol.DiarCoianPriorodiar,radoraradanddforoinnIH,foninonnraion,andridiiI.TheselimitsmaybeestablishedbytheConstructionStormwaterGeneralPermitorasite-specificdischargepermit.Samplingandtestingforotherpollutantsmayalsobenecessaryatsomesites.p11mustbewithintherangeof6.5to8.5standardunitsandnotcauseachangeinthepHofthereceivingwaterofmorethan0.2standardunits.Treatedstormwatersamplesandmeasurementsshallbetakenfromthedischargepipeoranotherlocationrepresentativeofthenatureofthetreatedstormwaterdischarge.Samplesusedfordeterminingcompliancewiththewaterqualitystandardsinthereceivingwatershallnotbetakenfromthetreatmentpondpriortodecanting.Compliancewiththewaterqualitystandardsisdeterminedinthereceivingwater.olumeConstructionStormii’aterPollutionPreentionuact201211 oraorTraininEachcontractorwhointendstousechemicaltreatmentshallbetrainedbyanexperiencedcontractor.EachsiteusingchemicaltreatmentmusthaveanoperatortrainedandcertifiedbyanorganizationapprovedbyEcology.SandardBMPSurfacestabilizationBMPsshouldbeimplementedonsitetopreventsignificanterosion.Allsitesshalluseatruckwheelwashtopreventtrackingofsedimentoffsite.SdinRoaandflioa•Sedimentshallberemovedfromthestorageortreatmentcellsasnecessary.Typically,sedimentremovalisrequiredatleastonceduringawetseasonandatthedecommissioningofthecells.Sedimentremaininginthecellsbetweenbatchesmayenhancethesettlingprocessandreducetherequiredchemicaldosage.•Sedimentthatisknowntobenon-toxicmaybeincorporatedintothesiteawayfromdrainages.BMPC251:ConstructionStormwaterFiltrationPurposeFiltrationremovessedimentfromrunofforiginatingfromdisturbedareasofthesite.Backgroundinformation:Filtrationwithsandmediahasbeenusedforoveracenturytotreatwaterandwastewater.Theuseofsandfiltrationfortreatmentofstormwaterhasdevelopedrecently,generallytotreatrunofffromstreets,parkinglots,andresidentialareas.Theapplicationoffiltrationtoconstructionstormwatertreatmentiscurrentlyunderdevelopment.ConditionsofUseTraditionalBMPsusedtocontrolsoilerosionandsedimentlossfromsitesunderdevelopmentmaynotbeadequatetoensurecompliancewiththewaterqualitystandardforturbidityinthereceivingwater.Filtrationmaybeusedinconjunctionwithgravitysettlingtoremovesedimentassmallasfinesilt(0.5g.tm).Thereductioninturbiditywillbedependentontheparticlesizedistributionofthesedimentinthestormwater.Insomecircumstances,sedimentationandfiltrationmayachievecomplianceviththewaterqualitystandardforturbidity.TheuseofconstructionstormwaterfiltrationdoesnotrequireapprovalfromEcologyaslongastreatmentchemicalsarenotused.FiltrationinconjunctionwithpolymertreatmentrequirestestingundertheChemicalTechnologyAssessmentProtocol—Ecology(CTAPE)beforeitcanbeinitiated.ApprovalfromtheappropriateregionalEcologyofficemustbeobtainedateachsitewherepolymersuseisproposedpriortouse.FormoreguidanceonstormwaterchemicaltreatmentseeBMPC250.ohiuwConstruction,ctor,ni’ate,Pothuionfireentionuus!2012II DesignandTwotypesoffiltrationsystemsmaybeappliedtoconstructionstormwaterInstallationtreatment:rapidandslow.RapidsandfiltersarethetypicalsystemusedSpecjficationsforwateraridwastewatertreatmenLTheycanachieverelativelyhighhydraulicflowrates,ontheorderof2to20gpm/sf,becausetheyhaveautomaticbackwashsystemstoremoveaccumulatedsolids.Incontrast,slowsandfiltershaveverylowhydraulicrates,ontheorderof0.02gpm/sf,becausetheydonothavebackwashsystems.Slowsandfiltrationhasgenerallybeenusedtotreatstorrnwater.Slowsandfiltrationismechanicallysimpleincomparisontorapidsandfiltrationbutrequiresamuchlargerfilterarea.FiraionEIn.Sandmediafiltersareavailablewithautomaticbackwashingfeaturesthatcanfilterto50jimparticlesize.Screenorbagfilterscanfilterdownto5jim.Fiberwoundfilterscanremoveparticlesdownto0.5lam.Filtersshouldbesequencedfromthelargesttothesmallestporeopening.Sedimentremovalefficiencywillberelatedtoparticlesizedistributioninthestormwater.TranProDriion.Stormwateriscollectedatinterceptionpoint(s)onthesiteandisdivertedtoanuntreatedstornnvatersedimentpondortankforremovaloflargesedimentandstorageofthestormwaterbeforeitistreatedbythefiltrationsystem.Theuntreatedstormwaterispumpedfromthetrap,pond,ortankthroughthefiltrationsysteminarapidsandfiltrationsystem.Slowsandfiltrationsystemsaredesignedasflowthroughsystemsusinggravity.MaintenanceRapidsandfilterstypicallyhaveautomaticbackwashsystemsthatareStandardstriggeredbyapre-setpressuredropacrossthefilter.Ifthebackwashwatervolumeisnotlargeorsubstantiallymoreturbidthantheuntreatedstormwaterstoredintheholdingpondortank,backwashreturntotheuntreatedstormwaterpondortankmaybeappropriate.However,othermeansoftreatmentanddisposalmaybenecessary.•Screen,bag,andfiberfiltersmustbecleanedand/orreplacedwhentheybecomeclogged.•Sedimentshallberemovedfromthestorageand/ortreatmentpondsasnecessary.Typically,sedimentremovalisrequiredonceortwiceduringawetseasonandatthedecommissioningoftheponds.SiinCr1riaforFo-TroTranSforFoConroEWarBodiWhensizingstoragepondsortanksforflow-throughsystemsforflowcontrolexemptwaterbodiesthetreatmentsystemcapacityshouldbeafactor.Theuntreatedstormwaterstoragepondortankshouldbesizedtohold1.5timestherunoffvolumeofthe10-year,24-hourstormeventminusthetreatmentsystemflowrateforan8-hourperiod.Forachitosanenhancedsandfiltrationsystem.thetreatmentsystemflowrateshouldbesizedusingahydraulicloadingratebetween6-8gpm/ft2.OtherhydraulicolwncConstructionStornni’olcrPollzuio,,PieenlionuILl201211 loadingratesmaybemoreappropriateforothersystems.Bypassshouldbeprovidedaroundthechemicaltreatmentsystemtoaccommodateextremestorms.RunoffvolumeshallbecalculatedusingthemethodspresentedinVolume3.Chapter2.Worst-caseconditions(i.e.,producingthemostrunoff)shouldbeusedforanalyses(mostlikelyconditionspresentpriortofinallandscaping).SiinCdnaforFoConroVarBodiSitesthatmustimplementflowcontrolforthedevelopedsiteconditionmustalsocontrolstorrnwaterreleaseratesduringconstruction.Constructionsitestormwaterdischargesshallnotexceedthedischargedurationsofthepre-developedconditionfortherangeofpre-developeddischargeratesfrom1/2ofthe2-yearflowthroughthe10-yearflowaspredictedbyanapprovedcontinuousrunoffmodel.Thepre-developedconditiontobematchedshallbethelandcoverconditionimmediatelypriortothedevelopmentproject.Thisrestrictiononreleaseratescanaffectthesizeofthestoragepond,thefiltrationsystem,andtheflowratethroughthefiltersystem.ThefollowingishowWWHMcanbeusedtodeterminethereleaseratesfromthefiltrationsystems:1.Determinethepre-developedflowdurationstobematchedbyenteringthelanduseareaunderthe“Pre-developed”scenarioinWWHM.Thedefaultflowrangeisfrom‘/2ofthe2-yearflowthroughthe10-yearflow.2.Enterthepostdevelopedlanduseareainthe“DevelopedUnmitigated”scenarioinWWHM.3.Copythelanduseinformationfromthe“DevelopedUnmitigated”to“DevelopedMitigated”scenario.4.Therealetwopossiblewaystomodelstormwaterfiltrationsystems:a.ThestormwaterfiltrationsystemusesanuntreatedstormwaterstoragepondItankandthedischargefromthispond/tankispumpedtooneormorefillers.In-linefiltrationchemicalswouldbeaddedtotheflowrightafterthepond/tankaridbeforethefilter(s).Becausethedischargeispumped,WWHMcan’tgenerateastage/storage/discharge(SSD)tableforthissystem.ThissystemismodeledthesamewayasdescribedinBMPC250andisasfollows:Whileinthe“DevelopedMitigated”scenario,addapondelementunderthebasinelementcontainingthepost-developedlanduseareas.Thispondelementrepresentsinformationontheavailableuntreatedstormwaterstorageanddischargefromthefiltrationsystem.Incaseswherethedischargefromthefiltrationsystemiscontrolledbyapump,astage/storage/discharge(SSD)tablerepresentingthepondmustbegeneratedoutsideWV/TIMandohmicConsinwilonS!ormii’atcrPollutionPieenlionuus!2012120 importedintoWWHM.WWHMcanroutetherunofffromthepost-developedconditionthroughthisSSDtable(thepond)anddeterminecompliancewiththeflowdurationstandard.ThiswouldbeaniterativedesignprocedurewhereiftheinitialSSDtableprovedtobeoutofcompliance,thedesignerwouldhavetomodi1’theSSDtableoutsideWWI-IMandre-importinWWHMandroutetherunoffthroughitagain.Theiterationwillcontinueuntilapondthatenablescompliancewiththeflowdurationstandardisdesigned.NotesonSSDtablecharacteristics:Thepumpdischargeratewouldlikelybeinitiallysetatjustbelow‘/:ifthe2-yearflowfromthepre-developedcondition.Asrunoffcomingintotheuntreatedstormwaterstoragepondincreasesandtheavailableuntreatedstormwaterstoragevolumegetsusedup,itwouldbenecessarytoincreasethepumpdischargerateabove4ofthe2-year.Theincrease(s)above%ofthe2-yearmustbesuchthattheyprovidesomerelieftotheuntreatedstormwaterstorageneedsbutatthesametimetheywillnotcauseviolationsoftheflowdurationstandardatthehigherflows.ThefinaldesignSSDtablewillidentifStheappropriatepumpingratesandthecorrespondingstageandstorages.Whenbuildingsuchaflowcontrolsystem,thedesignmustensurethatanyautomaticadjustmentstothepumpingrateswillbeasaresultofchangestotheavailablestorageinaccordancewiththefinaldesignSSDtable.b.Thestormwaterfiltrationsystemusesastoragepond/tankandthedischargefromthispond/tankgravityflowstothefilter.ThisisusuallyaslowsandfillersystemanditispossibletomodelitinWWHMasaFilterelementorasacombinationofPondandFilterelementplacedinseries.Thestage/storage/dischargetable(s)maythenbegeneratedwithinWWHMasfollows:(i)Whileinthe“DevelopedMitigated”scenario,addaFilterelementunderthebasinelementcontainingthepost-developedlanduseareas.Thelengthandwidthofthisfilterelementwouldhavetobethesameasthebottomlengthandwidthoftheupstreamuntreatedstormwaterstoragepond/tank.(ii)Incaseswherethelengthandwidthofthefilterisnotthesameasthoseforthebottomoftheupstreamuntreatedstormwaterstoragetank/pond,thetreatmentsystemmaybemodeledasaPondelementfollowedbyaFilterelement.Byhavingthesetwoelements,WWI-IMwouldthengenerateaSSDtableforthestoragepondwhichthengravityflowstotheFilterelement.TheFilterelementdownstreamoftheuntreatedstormwaterolunieCons/rue/to,,Siormipate,PollutionPieen/ionitus!2012121 storagepondwouldhaveastoragecomponentthroughthemedia,andanoverflowcomponentforwhenthefiltrationcapacityisexceeded.WWHMcanroutetherunofffromthepost-developedconditionthroughthetreatmentsystemsin4banddeterminecompliancewiththeflowdurationstandard.Thiswouldbeaniterativedesignprocedurewhereiftheinitialsizingestimatesforthetreatmentsystemprovedtobeinadequate,thedesignerwouldhavetomodifythesystemandroutetherunoffthroughitagain.Theiterationwouldcontinueuntilcompliancewiththeflowdurationstandardisachieved.5.Itshouldbenotedthattheaboveprocedureswouldbeusedtomeettheflowcontrolrequirements.Thefiltrationsystemmustbeabletomeettherunofftreatmentrequirements.ItislikelythatthedischargeflowrateofVzofthe2-yearormoremayexceedthetreatmentcapacityofthesystem.Ifthatisthecase,theuntreatedstormwaterdischargerate(s)(i.e..influenttothetreatmentsystem)mustbereducedtoallowpropertreatment.Anyreductionintheflowswouldlikelyresultintheneedforalargeruntreatedstormwaterstoragevolume.Ifsystemdesigndoesnotallowyoutodischargeattheslowerratesasdescribedaboveandifthesitehasaretentionordetentionpondthatwillservetheplanneddevelopment,thedischargefromthetreatmentsystemmaybedirectedtothepermanentretention/detentionpondtocomplywiththeflowcontrolrequirements.Inthiscase,theuntreatedstormwaterstoragepondandtreatmentsystemwillbesizedaccordingtothesizingcriteriaforflow-throughtreatmentsystemsforflowcontrolexemptwaterbodiesdescribedearlierexceptalldischarges(waterpassingthroughthetreatmentsystemandstornnvaterbypassingthetreatmentsystem)willbedirectedintothepermanentretention/detentionpond.Ifsiteconstraintsmakelocatingtheuntreatedstormwaterstorageponddifficult,thepermanentretention/detentionpondmaybedividedtoserveastheuntreatedstormwaterdischargepondandthepost-treatmentflowcontrolpond.Abermorbarriermustbeusedinthiscasesotheuntreatedwaterdoesnotmixwiththetreatedwater.Bothuntreatedstomiwaterstoragerequirements,andadequatepost-treatmentflowcontrolmustbeachieved.Thepost-treatmentflowcontrolpond’sreviseddimensionsmustbeenteredintotheWWIIMandtheWWIIMmustberuntoconfirmcompliancewiththeflowcontrolrequirement.oht;;wConstructionS!ornni’aterPollutionPieen/ionitus!2012122 BMPC252:HighpHNeutralizationUsingCO2PurposeWhenp1-Ilevelsinstormwaterriseabove8.5itisnecessarytolowerthep1-Ilevelstotheacceptablerangeof6.5to8.5,thisprocessiscalledpHneutralization.p1-Ineutralizationinvolvestheuseofsolidorcompressedcarbondioxidegasinwaterrequiringneutralization.NeutralizedstormwatermaybedischargedtosurfacewatersundertheGeneralConstructionNPDESpermit.NeutralizedprocesswatersuchasconcretetrucLwash-out.hydrodemolition,orsaw-cuttingslurrymustbemanagedtopreventdischargetosurfacewaters.Anystormwatercontaminatedduringconcreteworkisconsideredprocesswastewaterandmustnotbedischargedtosurfacewaters.RaonforHNraiaionApHlevelrangeof6.5to8.5istypicalformostnaturalwatercourses.andthisneutralpHisrequiredforthesurvivalofaquaticorganisms.ShouldthepHriscordropoutofthisrange,fishandotheraquaticorganismsmaybecomestressedandmaydie.CalciumhardnesscancontributetohighpHvaluesandcausetoxicitythatisassociatedwithhighpHconditions.Ahighlevelofcalciumhardnessinwatersofthestateisnotallowed.ThewaterqualitystandardforpHinWashingtonStateisintherangeof6.5to8.5.GroundwaterstandardforcalciumandoilierdissolvedsolidsinWashingtonStateislessthan500mg/I.(‘onditiousofUseCaofHiHHighpHatconstructionsitesismostcommonlycausedbythecontactofstormwaterwithpouredorrecycledconcrete,cement,mortars,andoilierPortlandcementorlimecontainingconstructionmaterials.(SeeBMPCl51:ConcreteHandlingformoreinformationonconcretehandlingprocedures).Theprincipalcausticagentincementiscalciumhydroxide(freelime).AdanaofCO2Sarin•Rapidlyneutralizeshighp11water.•Costeffectiveandsafertohandlethanacidcompounds.•CO2isself-buffering.ItisdifficulttooverdoseandcreateharmfullylowpHlcvcls.•Materialisreadilyavailable.ohuneCons/inc/ionS!onnii’a/erPollutionPreentioniitist201212 •TCiaProWhencarbondioxide(C02)isaddedtowater(H20),carbonicacid(H2C03)isformedwhichcanffirtherdissociateintoaproton(14+)andabicarbonateanion(HCOr)asshownbelow:C02±H20::H2C03:.‘H++HC03ThefreeprotonisaweakacidthatcanlowerthepH.Watertemperaturehasaneffectonthereactionaswell.Thecolderthewatertemperatureistheslowerthereactionoccursandthewarmerthewatertemperatureisthequickerthereactionoccurs.MostconstructionapplicationsinWashingtonStatehavewatertemperaturesinthe50°Forhigherrangesothereactionisalmostsimultaneous.DesignandTranProInstallationFlighp1-Iwatermaybetreatedusingcontinuoustreatment,continuousSpecificationsdischargesystems.Thesemanufacturedsystemscontinuouslymonitorinfluentandeffluentpl-ltoensurethatpHvaluesarewithinanacceptablerangebeforebeingdischarged.AllsystemsmusthavefailsafeautomaticshutoffswitchesintheeventthatpHisnotwithintheacceptabledischargerange.Onlytrainedoperatorsmayoperatemanufacturedsystems.Systemmanufacturersoftenprovidetrainedoperatorsortrainingontheirdevices.Thefollowingproceduremaybeusedwhennotusingacontinuousdischargesystem:1.Priortotreatment,theappropriatejurisdictionshouldbenotifiedinaccordancewiththeregulationssetbythejurisdiction.2.EveryeffortshouldbemadetoisolatethepotentialhighpHwaterinordertotreatitseparatelyfromotherstormwateron-site.3.Watershouldbestoredinanacceptablestoragefacility,detentionpond,orcontainmentcellpriortotreatment.4.Transferwatertobetreatedtothetreatmentstructure.Ensurethattreatmentstructuresizeissufficienttoholdtheamountofwaterthatistobetreated.Donotfilltankcompletely,allowatleast2feetoffreeboard.5.TheoperatorsamplesthewaterforpHandnotestheclarityofthewater.Asaruleofthumb.lessCO2isnecessaryforclearerwater.Thisinformationshouldberecorded.6.InthepHadjustmentstructure,addC02untilthepHfaLlsintherangeof6.9-7.1.RememberthatpHwaterqualitystandardsapplysoadjustingpHtowithin0.2pHunitsofreceivingwater(backgroundpH)isrecommended.ItisunlikelythatpHcanbeadjustedtowithin0.2pHunitsusingdryice.CompressedcarbondioxidegasshouldbeintroducedtothewaterusingacarbondioxidedilThserlocatednearolwncConstruclionS!oniiiiakrPollutionPieen/jot;itus!201212 thebottomofthetank,thiswillallowcarbondioxidetobubbleupthroughthewateranddifilisemoreevenly.7.Slowlydischargethewatermakingsurewaterdoesnotgetstinedupintheprocess.Releaseabout80%ofthewaterfromthestructureleavinganysludgebehind.8.Dischargetreatedwaterthroughapondordrainagesystem.9.Excesssludgeneedstobedisposedofproperlyasconcretewaste.IfseveralbatchesofwaterareundergoingpHtreatment,sludgecanbeleftintreatmentstructureforthenextbatchtreatment.Disposeofsludgewhenitfills50%oftankvolume.Sitesthatmustimplementflowcontrolforthedevelopedsitemustalsocontrolstormwaterreleaseratesduringconstruction.Alltreatedstormwatermustgothroughaflowcontrolfacilitybeforebeingreleasedtosurfacewaterswhichrequireflowcontrol.MaintenanceSafandManaHandinStandards•AllequipmentshouldbehandledinaccordancewahOSHArulesandregulations.•Followmanufacturerguidelinesformaterialshandling.oraorRordEachoperatorshouldprovide:•Adiagramofthemonitoringandtreatmentequipment.•Adescriptionofthepumpingratesandcapacitythetreatmentequipmentiscapableoftreating.Eachoperatorshouldkeepawrittenrecordofthefollowing:•Clientnameandphonenumber.•Dateoftreatment.•Weatherconditions.•Projectnameandlocation.•Volumeofwatertreated.•p1-1ofuntreatedwater.•AmountofCO2neededtoadjustwatertoap1-Irangeof6.9-7.1.•p11oftreatedwater.•Dischargepointlocationanddescription.Acopyofthisrecordshouldbegiventotheclient/contractorwhoshouldretaintherecordforthreeyears.ohinwConstrue/in,,SlorunvaterPollutionPieen/to,,iius/201212 BMPC253:pHControlforHighpHWaterPurposeWhenpHlevelsinstornnvaterriseabove8.5itisnecessarytolowerthepHlevelstotheacceptablerangeof6.5to8.5.thisprocessiscalledpHneutralization.Stormwaterwithp14levelsexceedingwaterqualitystandardsmaybetreatedbyinfiltration,dispersioninvegetationorcompost,pumpingtoasanitarysewer,disposalatapermittedconcretebatchplantwithpHneutralizationcapabilities,orcarbondioxidesparging.BMPC252givesguidelinesforcarbondioxidesparging.RaonforHNralalonApHlevelrangeof6.5to8.5istypicalformostnaturalwatercourses,andthispHrangeisrequiredforthesurvivalofaquaticorganisms.Shouldthep1-Iriseordropoutofthisrange,fishandotheraquaticorganismsmaybecomestressedandmaydie.condiriojisofUseCaofIIIHHighpHlevelsatconstructionsitesaremostcommonlycausedbythecontactofstormwaterwithpouredorrecycledconcrete,cement,mortars,andotherPortlandcementorlimecontainingconstructionmaterials.(SeeBMPCl51:ConcreteHandlimzformoreinformationonconcretehandlingprocedures).Theprincipalcausticagentincementiscalciumhydroxide(freelime).DesignandDioaModInstallationTnfiraionSpecifications•Infiltrationisonlyallowedifsoiltypeallowsallwatertoinfiltrate(nosurfacerunoff)withoutcausingorcontributingtoaviolationofsurfaceorgroundwaterqualitystandards.•InfiltrationtechniquesshouldbeconsistentwithVolumeV,Chapter7DinonUseBMPT5.30FullDispersionSaniarSrDioa•Localsewerauthorityapprovalisrequiredpriortodisposalviathesanitarysewer.ConnBaPanDioa•OnlypermittedfacilitiesmayaccepthighpHwater.•FacilityshouldbecontactedbeforetreatmenttoensuretheycanacceptthehighpHwater.SotarDiarAnypHtreatmentoptionsthatgeneratetreatedwaterthatmustbedischargedoffsitearesubjecttoflowcontrolrequirements.SitesthatmustimplementflowcontrolforthedevelopedsitemustalsocontrolohitneConstructionStonnii’atcrPollutionPreentionitact201212 storrnwaterreleaseratesduringconstruction.Alltreatedstormwatermustgothroughaflowcontrolfacilitybeforebeingreleasedtosurfacewaterswhichrequireflowcontrol.ohiuwConstructionStonn;:’aterPothitionPreeu/iouitits!201212 AppendixCCorrespondenceConstructionstormwaterisnotanticipatedtoleavethesiteatanytimeduringconstruction.Ifstormwateristobedischarged,atanypointduringconstruction,aNPDESpermitshallbeappliedforimmediately.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageC-i AppendixDSiteInspectionFormTheresultsofeachinspectionshallbesummarizedinaninspectionreportorchecklistthatisenteredintoorattachedtothesitelogbook.Itissuggestedthattheinspectionreportorchecklistbeincludedinthisappendixtokeepmonitoringandinspectioninformationinonedocument,butthisisoptional.However,itismandatorythatthisSWPPPandthesiteinspectionformsbekeptonsiteatalltimesduringconstruction,andthatinspectionsbeperformedanddocumentedasoutlinedbelow.Ataminimum,eachinspectionreportorchecklistshallinclude:Inspectiondate/timesWeatherinformation:generalconditionsduringinspection,approximateamountofprecipitationsincethelastinspection,andapproximateamountofprecipitationwithinthelast24hours.AsummaryorlistofallBMPsthathavebeenimplemented,includingobservationsofallerosion/sedimentcontrolstructuresorpractices.Thefollowingshallbenoted:locationsofBMPsinspected,locationsofEMPsthatneedmaintenance,thereasonmaintenanceisneeded,locationsofBMPsthatfailedtooperateasdesignedorintended,andlocationswhereadditionalordifferentBMPsareneeded,andthereason(s)whyAdescriptionofstormwaterdischargedfromthesite.Thepresenceofsuspendedsediment,turbidwater,discoloration,and/oroilsheenshallbenoted,asapplicable.Adescriptionofanywaterqualitymonitoringperformedduringinspection,andtheresultsofthatmonitoring.Generalcommentsandnotes,includingabriefdescriptionofanyBMPrepairs,maintenanceorinstallationsmadeasaresultoftheinspection.Astatementthat,inthejudgmentofthepersonconductingthesiteinspection,thesiteiseitherincomplianceoroutofcompliancewiththetermsandconditionsoftheSWPPPandtheNPDESpermit.Ifthesiteinspectionindicatesthatthesiteisoutofcompliance,theinspectionreportshallincludeasummaryoftheremedialactionsrequiredtobringthesitebackintocompliance,aswellasascheduleofimplementation.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageD-1 AppendixBBMPDetailsDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageB-i BMPClOl:PreservingNaturalVegetationPurposeThepurposeofpreservingnaturalvegetationistoreduceerosionwhereverpracticable.Limitingsitedisturbanceisthesinglemosteffectivemethodforreducingerosion.Forexample,coniferscanholduptoabout50percentofallrainthatfallsduringastorm.Upto20-30percentofthisrainmayneverreachthegroundbutistakenupbythetreeorevaporates.Anotherbenefitisthattherainheldinthetreecanbereleasedslowlytothegroundafterthestorm.ConditionsofUseNaturalvegetationshouldbepreservedonsteepslopes,nearperennialandintermittentwatercoursesorswales.andonbuildingsitesinwoodedareas.•Asrequiredbylocalgovernments.•Phaseconstructiontopreservenaturalvegetationontheprojectsiteforaslongaspossibleduringtheconstructionperiod.DesignandNaturalvegetationcanbepreservedinnaturalclumpsorasindividualInstallationtrees.shrubsandvines.SpecfficationsThepreservationofindividualplantsismoredifficultbecauseheavyequipmentisgenerallyusedtoremoveunwantedvegetation.Thepointstorememberwhenattemptingtosaveindividualplantsare:•Istheplantworthsaving?Considerthelocation,species,size,age,vigor,andtheworkinvolved.Localgovernmentsmayalsohaveordinancestosavenaturalvegetationandtrees.•Fenceorclearlymarkareasaroundtreesthataretobesaved.Itispreferabletokeepgrounddisturbanceawayfromthetreesatleastasfaroutasthedripline.Plantsneedprotectionfromthreekindsofinjuries:•Constructionuimen!—Thisinjury’canbeaboveorbelowthegroundlevel.Damageresultsfromscarring,cuttingofroots,andcompactionofthesoil.Placingafencedbufferzonearoundplantstobesavedpriortoconstructioncanpreventconstructionequipmentinjuries.•GraeCanes-Changingthenaturalgroundlevelwillaltergrades,whichaffectstheplant’sabilitytoobtainthenecessaryair,water,andminerals.Minorfillsusuallydonotcauseproblemsalthoughsensitivitybetweenspeciesdoesvaryandshouldbechecked.Treescantypicallytoleratefillof6inchesorless.Forshrubsandotherplants,thefillshouldbeless.Whentherearemajorchangesingrade,itmaybecomenecessarytosupplyairtotherootsofplants.Thiscanbedonebyplacingalayerofgravelandatilesystemovertherootsbeforethefillismade.Atilesystemprotectsatreefromaraisedgrade.ThetilesystemshouldbeohmicConstructionStonnii’aterPollutionPreen/ionitus!2012 laidoutontheoriginalgradeleadingfromadryvellaroundthetreetrunk.Thesystemshouldthenbecoveredwithsmallstonestoallowairtocirculateovertherootarea.Loweringthenaturalgroundlevelcanseriouslydamagetreesandshrubs.Thehighestpercentageoftheplantrootsareintheupper12inchesofthesoilandcutsofonly2-3inchescancauseseriousinjury.Toprotecttherootsitmaybenecessarytoterracetheimmediateareaaroundtheplantstobesaved.Ifrootsareexposed,constructionofretainingwallsmaybeneededtokeepthesoilinplace.Plantscanalsobepreservedbyleavingthemonanundisturbed,gentlyslopingmound.Toincreasethechancesforsurvival,itisbesttolimitgradechangesandothersoildisturbancestoareasoutsidethedriplineoftheplant.cc;citiolls-Protecttreesandotherplantswhenexcavatingfordrainfields,power,water,andsewerlines.Wherepossible,thetrenchesshouldberoutedaroundtreesandlargeshrubs.Whenthisisnotpossible,itisbesttotunnelunderthem.Thiscanbedonewithhandtoolsorwithpoweraugers.Ifitisnotpossibletoroutethetrencharoundplantstobesaved,thenthefollowingshouldbeobserved:Cutasfewrootsaspossible.Whenyouhavetocut,cutclean.Paintcutrootendswithawooddressinglikeasphaltbasepaintifrootswillbeexposedformorethan24-hours.Backfillthetrenchassoonaspossible.Tunnelbeneathrootsystemsasclosetothecenterofthemaintrunktopreservemostoftheimportantfeederroots.Someproblemsthatcanbeencounteredwithafewspecifictreesare:•Maple,Dogwood,Redalder,Westernhemlock,Westernredcedar,andDouglasfirdonotreadilyadjusttochangesinenvironmentandspecialcareshouldbetakentoprotectthesetrees.•ThewindthrowhazardofPacificsilverfirandmadronaishigh,whilethatofWesternhemlockismoderate.Thedangerofwindthrowincreaseswheredensestandshavebeenthinned.Otherspecies(unlesstheyareonshallow,wetsoilslessthan20inchesdeep)havealowwindthrowhazard.•Cottonwoods,maples,andwillowshavewater-seekingroots.Thesecancausetroubleinsewerlinesandinfiltrationfields.Ontheotherhand,theythriveinhighmoistureconditionsthatothertreeswouldnot.•ThinningoperationsinpureormixedstandsofGrandfir,Pacificsilverfir.Noblefir.Sitkaspruce,Westernredcedar,Westernhemlock,Pacificdogwood,andRedaldercancauseseriousdiseaseproblems.Diseasecanbecomeestablishedthroughdamagedlimbs,trunks,roots,olzmwConstructionS/or,niratc;PollutionPrecut/oniius!2012 andfreshlycutstumps.Diseasedandweakenedtreesarealsosusceptibletoinsectattack.MaintenanceInspectflaggedand/orfencedareasregularlytomakesureflaggingorStandardsfencinghasnotbeenremovedordamaged.Iftheflaggingorfencinghasbeendamagedorvisibilityreduced,itshallberepairedorreplacedimmediatelyandvisibilityrestored.•Iftreerootshavebeenexposedorinjured.“prune”cleanlywithanappropriatepruningsaworlopersdirectlyabovethedamagedrootsandrecoverwithnativesoils.Treatmentofsapflowingtrees(fir.hemlock,pine,softmaples)isnotadvisedassapformsanaturalhealingbarrier.BMPC102:BufferZonesPurposeCreationclanundisturbedareaorstripofnaturalvegetationoranestablishedsuitableplantingthatwillprovidealivingfiltertoreducesoilerosionandrunoffvelocities.conditionsofUseNaturalbufferzonesareusedalongstreams.wetlandsandotherbodiesofwaterthatneedprotectionfromerosionandsedimentation.Vegetativebufferzonescanbeusedtoprotectnaturalswalesandcanbeincorporatedintothenaturallandscapingofanarea.Critical-areasbufferzonesshouldnotbeusedassedimenttreatmentareas.Theseareasshallremaincompletelyundisturbed.Thelocalpermittingauthoritymayexpandthebufferwidthstemporarilytoallowtheuseoftheexpandedareaforremovalofsediment.Designand•Preservingnaturalvegetationorplantingsinclumps,blocks,orstripsInstallationisgenerallytheeasiestandmostsuccessfulmethod.Specjfications•Leaveallunstablesteepslopesinnaturalvegetation.•Markclearinglimitsandkeepallequipmentandconstructiondebrisoutofthenaturalareasandbufferzones.Steelconstructionfencingisthemosteffectivemethodinprotectingsensitiveareasandbuffers.Alternatively,wire-backedsiltfenceonsteelpostsismarginallyeffective.Flaggingaloneistypicallynoteffective.•Keepallexcavationsoutsidethedriplineoftreesandshrubs.•Donotpushdebrisorextrasoilintothebufferzoneareabecauseitwillcausedamagefromburyingandsmothering.•Vcgetativcbufferzoncsforstreams,lakesorotherwaterwaysshallbcestablishedbythelocalpermittingauthorityorotherstateorfederalpermitsorapprovals.MaintenanceInspecttheareafrequentlytomakesureflaggingremainsinplaceandtheStandardsarearemainsundisturbed.Replacealldamagedflaggingimmediately.ohmicConstructionS!ornni’citerPollutionPiecottonUus!20)2 BMPC103:HighVisibilityFencePurposeFencingisintendedto:1.Restrictclearingtoapprovedlimits.2.Preventdisturbanceofsensitiveareas,theirbuffers,andotherareasrequiredtobeleftundisturbed.3.Limitconstructiontraffictodesignatedconstructionentrances,exits,orinternalroads.4.Protectareaswheremarkingwithsurveytapemaynotprovideadequateprotection.(‘auditionsofUseToestablishclearinglimitsplastic.fabric,ormetalfencemaybeused:•Attheboundaryofsensitiveareas,theirbuffers,andotherareasrequiredtobeleftuncleared.•Asnecessarytocontrolvehicleaccesstoandonthesite.DesignandHighvisibilityplasticfenceshallbecomposedofahigh-densityInstallationpolyethylenematerialandshallbeatleastfourfeetinheight.PostsforSpecjficationsthefencingshallbesteelorwoodandplacedevery6feetoncenter(maximum)orasneededtoensurerigidity.Thefencingshallbefastenedtotheposteverysixincheswithapolyethylenetie.Onlongcontinuouslengthsoffencing,atensionwireorropeshallbeusedasatopstringertopreventsaggingbetweenposts.Thefencecolorshallbehighvisibilityorange.Thefencetensilestrengthshallbe360lbs./ft.usingtheASTMD4595testingmethod.IfappropriateinstallfabricsiltfenceinaccordancewithBMPC233toactashighvisibilityfence.Siltfenceshallbeatleast3feethighandmustbehighlyvisibletomeettherequirementsofthisBMP.Metalfencesshallbedesignedandinstalledaccordingtothemanufacturer’sspecifications.Metalfencesshallbeatleast3feethighandmustbehighlyvisible.Fencesshallnotbewiredorstapledtotrees.MaintenanceIfthefencehasbccndamagedorvisibilityreduccd.itshallbcrepairedorStandardsreplacedimmediatelyandvisibilityrestored.ohmicConstructionStornni’a!erPollutionPieen/ioniius!2012 BMPC105:StabilizedConstructionEntrance!ExitPurposeStabilizedConstructionentrancesareestablishedtoreducetheamountofsedimenttransportedontopavedroadsbyvehiclesorequipment.Thisisdonebyconstructingastabilizedpadofquarryspallsatentrancesandexitsforconstructionsites.conditionsofUseConstructionentrancesshallbestabilizedwherevertrafficwillbeenteringorleavingaconstructionsiteifpavedroadsorotherpavedareasarewithin1.000feelofthesite.Forresidentialconstructionprovidestabilizedconstructionentrancesforeachresidence,ratherthanonlyatthemainsubdivisionentrance.Stabilizedsurfacesshallbeofsufficientlength/widthtoprovidevehicleaccess/parking,basedonlotsize/configuration.Onlargecommercial,highway,androadprojects,thedesignershouldincludeenoughextramaterialsinthecontracttoallowforadditionalstabilizedentrancesnotshownintheinitialConstructionSWPPP.Itisdifficulttodetermineexactlywhereaccesstotheseprojectswilltakeplace;additionalmaterialswillenablethecontractortoinstallthemwhereneeded.DesignandSeeFigure4.1.1fordetails.Note:the100’minimumlengthoftheInstallationentranceshallbereducedtothemaximumpracticablesizewhenthesizeSpecjflcationsorconfigurationofthesitedoesnotallowtheMIlength(100’).Constructstabilizedconstructionentranceswitha12-inchthickpadof4-inchto8-inchquarryspalls.a4-inchcourseofasphalttreatedbase(ATB),oruseexistingpavement.Donotusecrushedconcrete,cement,orcalciumchlorideforconstructionentrancestabilizationbecausetheseproductsraisepHlevelsinstormwaterandconcretedischargetosurfacewatersoftheStateisprohibited.Aseparationgeotextileshallbeplacedunderthespallstopreventfinesedimentfrompumpingupintotherockpad.Thegeotextileshallmeetthefollowingstandards:GrabTensileStrength(ASTMD4751)200psimm.GrabTensileElongation(ASTM30%max.D4632)MullenBurstStrength(ASTM400psimm.D3786-80a)AOS(ASTMD4751)20-45(U.S.standardsievesize)•Considerearlyinstallationofthefirstliftofasphaltinareasthatwillpaved;thiscanbeusedasastabilizedentrance.Alsoconsidertheinstallationofexcessconcreteasastabilizedentrance.Duringlargeconcretepours,excessconcreteisoftenavailableforthispurpose.ohiineConstructionStornni’aterPollutionPrc’entioniiitct2012 •Fencing(seeBMPC103)shallbeinstalledasnecessarytorestricttraffictotheconstructionentrance.•Wheneverpossible,theentranceshallbeconstructedonafirm,compactedsubgrade.Thiscansubstantiallyincreasetheeffectivenessofthepadandreducetheneedformaintenance.•Constructionentrancesshouldavoidcrossingexistingsidewalksandbackofwalkdrainsifatallpossible.Ifaconstructionentrarwemustcrossasidewalkorbackofwalkdrain,thefulllengthofthesidewalkandbackofwalkdrainmustbecoveredandprotectedfromsedimentleavingthesite.MaintenanceQuarryspallsshallbeaddedifthepadisnolongerinaccordancewithStandardsthespecifications.•Iftheentranccisnotpreventingsedimentfrombeingtrackedontopavement,thenalternativemeasurestokeepthestreetsfreeofsedimentshallbeused.Thismayincludereplacement/cleaningoftheexistingquarryspalls,streetsweeping,anincreaseinthedimensionsoftheentrance,ortheinstallationofawheelwash.•Anysedimentthatistrackedontopavementshallberemovedbyshovelingorstreetsweeping.Thesedimentcollectedbysweepingshallberemovedorstabilizedonsite.Thepavementshallnotbecleanedbywashingdownthestreet,exceptwhenhighefficiencysweepingisineffectiveandthereisathreattopublicsafety.Ifitisnecessarytowashthestreets,theconstructionofasmallsumptocontainthewashwatershallbeconsidered.Thesedimentwouldthenbewashedintothesumpwhereitcanbecontrolled.•Performstreetsweepingbyhandorwithahighefficiencysweeper.Donotuseanon-highefficiencymechanicalsweeperbecausethiscreatesdustandthrowssoilsintostormsystemsorconveyanceditches.•Anyquarryspallsthatareloosenedfromthepad,whichendupontheroadwayshallberemovedimmediately.•Ifvehiclesareenteringorexitingthesiteatpointsotherthantheconstructionentrance(s),fencing(seeBMPC103)shallbeinstalledtocontroltraffic.•Uponprojectcompletionandsitestabilization,allconstructionaccessesintendedaspermanentaccessformaintenanceshallbepermanentlystabilized.obtincCo,zs!ruc/ionS/orinwa!erPot/it/ionPreentioniius!2012 Figure4.1.1—StabilizedConstructionEntranceApprovedasEquivalei#EcologyhasapprovedproductsasabletomeettherequirementsofBMPC]05.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecv.wa.cov/programs/vg/stormwater/newtech/eguivalent.htmlBMPC106:WheelWashPurposeConditionsofUseWheelwashesreducetheamountofsedimenttransportedontopavedroadsbymotorvehicles.‘Whenastabilizedconstructionentrance(seeBMPC105)isnotpreventingsedimentfrombeingtrackedontopavement.WheelwashingisgcncrallyancffectivcBMPwheninstallcdwithcarefulattentiontotopography.Forexample,awheelwashcanbedetrimentalifinstalledatthetopofaslopeabuttingaright-of-waywherethewaterfromthedrippingtruckcanrununimpededintotheStreet.DiwayshaltmeetIrerequirementsofthepermittingagencyisrecommendedthattheentrancebecrownedsothatrunoffdrainsoffthepad-ltnsitdrivewaycutveriif?‘&eisaroadsideditchpresent4’—8’quarryspattsGeolextire17mm.thicknessPrcvdeluwidthoftgressJegressareaohinwConstructionStornnt’aterPollutionPreen/ioniiILV/2012 •Pressurewashingcombinedwithanadequatelysizedandsurfacedpadwithdirectdrainagetoalarge10-footx10-footsumpcanbevery’effective.•Dischargewheelwashortirebathwastewatertoaseparateon-sitetreatmentsystemthatpreventsdischargetosurfacewater,suchasclosed-looprecirculationoruplandlandapplication,ortothesanitarysewerwithlocalsewerdistrictapproval.•Wheelwashortirebathwastewatershouldnotincludewastewaterfromconcretewashoutareas.DesignandSuggesteddetailsareshowninFigure4.1.2.TheLocalPermittingInstallationAuthoritymayallowotherdesigns.Aminimumof6inchesofasphaltSpecjflcauonstreatedbase(ATB)overcrushedbasematerialor8inchesoveragoodsubgradeisrecommendedtopavethewheelwash.Usealowclearancetrucktotestthewheelwashbeforepaving.Eitherabellydumporlowboywillworkwelltotestclearance.Keepthewaterlevelfrom12to14inchesdeeptoavoiddamagetotruckhubsandfillingthetrucktongueswithwater.Midpointspraynozzlesareonlyneededinextremelymuddyconditions.Wheelwashsystemsshouldbedesignedwithasmallgradechange,6-to1-inchesfora10-foot-widepond,toallowsedimenttoflowtothelowsideofpondtohelppreventre-suspensionofsediment.Adrainpipewitha2-to3-footrisershouldbeinstalledonthelowsideofthepondtoallowforeasycleaningandrefilling.Polymersmaybeusedtopromotecoagulationandflocculationinaclosed-loopsystem.Polyacrylamide(PAM)addedtothewheelwashwateratarateof0.25-0.5poundsper1,000gallonsofwaterincreaseseffectivenessandreducescleanuptime.IfPAMisalreadybeingusedfordustorerosioncontrolandisbeingappliedbyawatertruck,thesametruckcanbeusedtochangethewashwater.MaintenanceThewheelwashshouldstartoutthedaywithfreshwater.StandardsThewashwatershouldbechangcdaminimumofonceperday.Onlargeearilworkjobswheremorethan10-20trucksperhourareexpected,the‘ashwaterwillneedtobechangedmoreoften.ohe;;wConstructionStonmi’ate,PollutionPreeu/ioniius!201210 ‘‘i[jMIDPOINTSPRAYNOZZLESJEDEDI2%s7I___iIIENEL1:11SLOPE-SLOPE,II2XSLOPEII-‘t—CAmCONSTRUCtONSLOPEACICTRANCE15’ATBAPRONTOPROTECTASPHALTCURBONTHEGROUNDFROMSPLASHINGWATERLOWROADSIDETODIRECT5SLEEVEUNDERROADWATERSACKTOPONDIPLANViEW]I_15_l15-2OI_15’__50Notes:Figure4.1.2—WheelWashI.Asphaltconstructionentrance6in.asphalttreatedbase(ATB).2.3-inchtrashpumpwithfloatsonthesuctionhose.3.Midpointspraynozzles,ifneeded.4.6-inchsewerpipewithbutterflyvalves.Bottomoneisadrain.Locatetoppipe’sinvert1footabovebottomofwheelwash.5.8footx8footsumpwith5feetofcatch.Buildsothesumpcanbecleanedwithatrackhoe.6.Asphaltcurbonthelowroadsidetodirectwaterbacktopond.7.6-inchsleeveunderroad.8.Ballvalves.9.15foot.ATBaprontoprotectgroundfromsplashingwater.ohuneConstructionStormu’a!erPollutionPieen/ionxius!20126SEWERPIPEWITHBU1TERFLYVALVES—WxB’SUMPWITH5’OFCATCH3TRASHPUMPWITHFLOATSAONSUCTIONHOSE—2SCHEDULE40l—T/2SCHEDULE40-FORSPRAYERSIIIICSLEEVEIELEVA11ONV1EWILOCATEINVERTOFTOPPIPE1•ABOVEBOTTOMOFWHEELWASHSxS’SWAP•‘N%‘\\WATERLEVEL4,I.3’5.DRAINPIPEISECT1ONA—AlNOTES:11SLOPE1.BUILDB’xWSUMPTOACCOMODATECLEANINGBYTRACKHOE.11 BMPC107:ConstructionRoadlParkingAreaStabilizationPurposeStabilizingsubdivisionroads,parkingareas,andotheron-sitevehicletransportationroutesimmediatelyaftergradingreduceserosioncausedbyconstructiontrafficorrunoff.ConditionsofUseRoadsorparkingareasshallbestabilizedwherevertheyareconstructed,whetherpermanentortemporary,forusebyconstructiontraffic.HighVisibilityFencing(seeBMPC103)shallbeinstalled,ifnecessary,tolimittheaccessofvehiclestoonlythoseroadsandparkingareasthatarestabilized.Designand•Onareasthatwillreceiveasphaltaspartoftheproject,installthefirstInstallationliftassoonaspossible.Specj,flcationsA6-inchdepthof2-to4-inchcrushedrock,gravelbase,orcrushedsurfacingbasecourseshallbeappliedimmediatelyaftergradingorutilityinstallation.A4-inchcourseofasphalttreatedbase(ATB)mayalsobeused,ortheroad/parkingareamaybepaved.Itmayalsobepossibletousecementorcalciumchlorideforsoilstabilization.Ifcementorcementkilndustisusedforroadbasestabilization,pHmonitoringandBMPs(BMPsC252andC253)arenecessarytoevaluateandminimizetheeffectsonstormwater.Iftheareawillnotbeusedforpermanentroads,parkingareas,orstructures,a6-inchdepthofhogfuelmayalsobeused,butthisislikelytorequiremoremaintenance.Wheneverpossible,constructionroadsandparkingareasshallbeplacedonafirm,compactedsubgrade.•Temporaryroadgradientsshallnotexceed15percent.Roadwaysshallbecarefullygradedtodrain.Drainageditchesshallbeprovidedoneachsideoftheroadwayinthecaseofacrownedsection,orononesideinthecaseofasuper-elevatedsection.DrainageditchesshallbedirectedtoasedimentcontrolBMP.•Ratherthanrelyingonditches,itmayalsobepossibletogradetheroadsothatrunoffsheet-flowsintoaheavilyvegetatedareawithawell-developedtopsoil.Landscapedareasarenotadequate.Ifthisareahasatleast50feetofvegetationthatwatercanflowthrough,thenitisgenerallypreferabletousethevegetationtotreatrunoff,ratherthanasedimentpondortrap.The50feetshallnotincludewetlandsortheirbuffers.Ifrunoffisallowedtosheetfiowthroughadjacentvegetatedareas,itisvitaltodesigntheroadwaysandparkingareassothatnoconcentratedrunoffiscreated.•Stormdraininletsshallbeprotectedtopreventsediment-ladenwaterenteringthestormdrainsystem(seeBMPC220).MaintenanceInspectstabilizedarcasregularly,especiallyafterlargestormevents.StandardsCrushedrock,gravelbase,etc.shallbeaddedasrequiredtomaintainaohmicConstrue/iouStonnwa/erPollutionPieen/ionuus!201212 stabledrivingsurfaceandtostabilizeanyareasthathaveeroded.Followingconstruction,theseareasshallberestoredtopre-constructionconditionorbettertopreventfutureerosion.Performstreetcleaningattheendofeachdayormoreoftenifnecessary.BMPC120:TemporaryandPermanentSeedingPurposeSeedingreduceserosionbystabilizingexposedsoils.Awell-establishedvegetativecoverisoneofthemosteffectivemethodsofreducingerosion.conditionsofUseUseseedingthroughouttheprojectondisturbedareasthathavereachedfinalgradeorthatwillremainunworkedformorethan30days.TheoptimumseedingwindowsforwesternWashingtonareApril1throughJune30andSeptember1throughOctober1.BetweenJuly1andAugust30seedingrequiresirrigationuntil75percentgrasscoverisestablished.BetweenOctober1andMarch30seedingrequiresacoverofmulchwithstraworanerosioncontrolblanketuntil75percentgrasscoverisestablished.ReviewalldisturbedareasinlateAugusttoearlySeptemberandcompleteallseedingbytheendofSeptember.Otherwise,vegetationwillnotestablishitselfenoughtoprovidemorethanaverageprotection.•Mulchisrequiredatalltimesforseedingbecauseitprotectsseedsfromheat,moistureloss,andtransportduetorunoff.Mulchcanbeappliedontopoftheseedorsimultaneouslybyhydroseeding.SeeBMPC121:Mulchingforspecifications.•Seedandmulch,alldisturbedareasnototherwisevegetatedatfinalsitestabilization.Finalstabilizationmeansthecompletionofallsoildisturbingactivitiesatthesiteandtheestablishmentofapermanentvegetativecover,orequivalentpermanentstabilizationmeasures(suchaspavement,riprap,gabionsorgeotextiles)whichwillpreventerosion.DesignandSeedretention/detentionpondsasrequired.Installation..InstallchannelsintendedforvegetationbeforestartingmajorSpecificationsearthworkandhydroseedwithaBondedFiberMatrix.Forvegetatedchannelsthatwillhavehighflows,installerosioncontrolblanketsoverhydroseed.Beforeallowingwatertoflowinvegetatedchannels,establish75percentvegetationcover.Ifvegetatedchannelscannotbeestablishedbyseedbeforewaterflow;installsodinthechannelbottom—overhydromulchanderosioncontrolblankets.ohuneConstructionStormit’cg!erPollutionPreentionitus!2012I •Confirmtheinstallationofallrequiredsurfacewatercontrolmeasurestopreventseedfromwashingaway.•1-lydroseedapplicationsshallincludeaminimumof1,500poundsperacreofmulchwith3percenttackifier.SeeBMPC121:Mulchingforspecifications.•Areasthatwillhaveseedingonlyandnotlandscapingmayneedcompostormeal-basedmulchincludedinthehydroseedinordertoestablishvegetation.Re-installnativetopsoilonthedisturbedsoilsurfacebeforeapplication.•Wheninstallingseedviahydroseedingoperations,onlyabout1/3oftheseedactuallyendsupincontactwiththesoilsurface.Thisreducestheabilitytoestablishagoodstandofgrassquickly.Toovercomethis,considerincreasingseedquantitiesbyupto50percent.•Enhancevegetationestablishmentbydividingthehydromulchoperationintotwophases:1.Phase1-Installallseedandfertilizerwith25-30percentmulchandtackifierontosoilinthefirstlift.2.Phase2-Installtherestofthemulchandtackifieroverthefirstlift.Or,enhancevegetationby:1.Installingthemulch,seed,fertilizer,andtackifierinonelift.2.Spreadorblowstrawoverthetopofthehydromulchatarateof800-1000poundsperacre.3.Holdstrawinplacewithastandardtackifier.Bothoftheseapproacheswillincreasecostmoderatelybutwillgreatlyimproveandenhancevegetativeestablishment.Theincreasedcostmaybeoffsetbythereducedneedfor:•Irrigation.•Reapplicationofmulch.•Repairoffailedslopesurfaces.Thistechniqueworkswithstandardhydromulch(1,500poundsperacreminimum)andBFM/MBFMs(3,000poundsperacreminimum).•Seedmaybeinstalledbyhandif:•Temporaryandcoveredbystraw,mulch,ortopsoil.•Permanentinsmallareas(usuallylessthanIacre)andcoveredwithmulch,topsoil,orerosionblankets.•Theseedmixeslistedinthetablesbelowincluderecommendedmixesforbothtemporaryandpermanentseeding.ohinwCojs/riic/ionStonnwalerPollutionPreentionitus!20121 •Applythesemixes,withtheexceptionofthewetlandmix.atarateof120poundsperacre.Thisratecanbereducedifsoilamendmentsorslow-releasefertilizersareused.•Consultthelocalsuppliersorthelocalconservationdistrictfortheirrecommendationsbecausetheappropriatemixdependsonavarietyoffactors.includinglocation,exposure,soiltype.slope,andexpectedfoottraffic.Alternativeseedmixesapprovedbythelocalauthoritymaybeused.•Othermixesmaybeappropriate,dependingonthesoiltypeandhydrologyofthearea.Table4.1.2liststhestandardmixforareasrequiringatemporaryvegetativecover.Table4.1.2TemporaryErosionControlSeedMixVjPHGrmaionChewingsorannualbluegrass409890es/zetarubraarconnnzilataorFociannaPerennialrye-509890olizen,erauneRedtoporcolonialbentgrass59285rosilsa/baorrostistenzeisWhitedutchclover59890HolwnzleeflY•Table4.1.3listsarecommendedmixforlandscapingseed.Table4.1.3LandscapingSeedMixWIPriGrinnionPerennialryeblend709890oliuiiiL’PL’fl?7L’Chewingsandredfescueblend309890esnecarubraciicommu!a!aorestiecarzthraobtineConstrue/ionStornzwa!erPollutionPieen/ioniius!2012I •Table4.1.4listsaturfseedmixfordrysituationswherethereisnoneedforwatering.Thismixrequiresverylittlemaintenance.Table4.1.4Low-GrowingTurfSeedMixViPriGrinaionDwarftallfescue(severalvarieties)459890estucaaninmaccaat—____ ____ ____ ____ ____ ___Dwarfperennialrye(Barclay)309890olin,;,erenneatbare/aRedfescue209890estucarzthraColonialbentgrass59890roslislefliUS•Table4.1.5listsamixforbioswalesandotherintermittentlywetareas.Table4.1.5BioswaleSeedMix*ViPriGrinsionTallormeadowfescue75-809890extneaaruniizaceaoresfltcac/allotSeaside/Creepingbentgrass10-159285rostisalusirisRedtopbentgrass5-109080rostisathaorrosiLyian/caolierimteen,ncroseeinGuieel/ansSeeohmicCons/rudilonS!or,nii’a!erPolhthonPieenlionuus!2012I •Table4.1.6listsalow-growing,relativelynon-invasiveseedmixappropriateforverywetareasthatarenotregulatedwetlands.Applythismixtureatarateof60poundsperacre.Consult1-lydraulicPermitAuthority(HPA)forseedmixesifapplicable.Table4.1.6WetAreaSeedMix*WiPriCrinnionTallormeadowfescue60-709890cx!ucaan/nmaccaores/ucacia/lopSeaside/Creepinghentgrass10-159885rosilsa/its!risMeadowfoxtail10-159080icocurusratensisAlsikeclover1-69890,ioliumbriinnRedtopbentgrass1-69285rostisa/baolieriarreen,nerosecinGuiec//ansSeci•Table4.1.7listsarecommendedmeadowseedmixforinfrequentlymaintainedareasornon-maintainedareaswherecolonizationbynativeplantsisdesirable.Likelyapplicationsincluderuralroadandutilityright-of-way.SeedingshouldtakeplaceinSeptemberorveryearlyOctoberinordertoobtainadequateestablishmentpriortothewintermonths.Considertheappropriatenessofclover,afairlyinvasivespecies,inthemix.Amendingthesoilcanreducetheneedforclover.Table4.1.7MeadowSeedMixWIPriCrinnionRedtoporOregonbentgrass209285rostisa/baorrostisor e onensi s -____ _ _ ________ _ _ ________ _ _ ________ _ _ ________ _ _ ________ _ _Redfescue709890csfltcariebra-___________-___ __Whitedutchclover109890ri0/li/fl?PCCfl5oheineConstructionS!ornnva/crPo/huio,zPieeli//oiluus!20121 •RonmandRo01iiiTheseedbedshouldbefirmandrough.Roughenallsoilnomatterwhattheslope.Trackwalkslopesbeforeseedingifengineeringpurposesrequirecompaction.Backbladingorsmoothingofslopesgreaterthan4H:lVisnotallowediftheyaretobeseeded.•Restoration-basedlandscapepracticesrequiredeeperincorporationthanthatprovidedbyasimplesingle-passrototillingtreatment.Whereverpractical,initiallyripthesubgradetoimprovelong-termpermeability,infiltration,andwaterinflowqualities.Ataminimum,permanentareasshallusesoilamendmentstoachieveorganicmatterandpermeabilityperformancedefinedinengineeredsoil/landscapesystems.Forsystemsthataredeeperthan8inchescompletetherototillingprocessinmultiplelifts,orpreparetheengineeredsoilsystemperspecificationsandplacetoachievethespecifieddepth.•Friir•Conductingsoilteststodeterminetheexacttypeandquantityoffertilizerisrecommended.Thiswillpreventtheover-applicationoffertilizer.•Organicmatteristhemostappropriateformoffertilizerbecauseitprovidesnutrients(includingnitrogen,phosphorus,andpotassium)intheleastwater-solubleform.•Ingeneral,use10-4-6N-P-K(nitrogen-phosphorus-potassium)fertilizeratarateof90poundsperacre.Alwaysuseslow-releasefertilizersbecausetheyaremoreefficientandhavefewerenvironmentalimpacts.Donotaddfertilizertothehydromulchmachine,oragitate,morethan20minutesbeforeuse.Toomuchagitationdestroystheslow-releasecoating.•Therearenumerousproductsavailablethattaketheplaceofchemicalfertilizers.Theseincludeseveralwithseaweedextractsthatarebeneficialtosoilmicrobesandorganisms.If100percentcottonseedmealisusedasthemulchinhydroseed,chemicalfertilizermaynotbenecessary.Cottonseedmealprovidesagoodsourceoflong-term,slow-release,availablenitrogen.•BonddFirMaiiandManiaBonddFirMari•OnsteepslopesuseBondedFiberMatrix(BFM)orMechanicallyBondedFiberMatrix(MBFM)products.ApplyBFM/MBFMproductsataminimumrateof3,000poundsperacreofmulchwithapproximately10percenttackifier.Achieveaminimumof95pcrcentsoilcovcragcduringapplication.Numerousproductsarcavailablecommercially.Installedproductspermanufacturer’sinstructions.Mostproductsrequire24-36hourstocurebeforerainfallandcannotbeinstalledonwetorsaturatedsoils.ohiineConsfiuctionSlornni’aterPollutionPreentioniius!2012I Generally,productscomein40-50poundbagsandincludeallnecessaryingredientsexceptforseedandfertilizer.•BFMsandMBFMSprovidegoodalternativestoblanketsinmostareasrequiringvegetationestablishment.Advantagesoverblanketsinclude:•BFMandMBFMsdonotrequiresurfacepreparation.•HelicopterscanassistininstallingBFMandMBFMsinremoteareas.•Onslopessteeperthan2.5H:IV.blanketinstallersmayrequireropesandharnessesforsafety.•InstallingBFMandMBFMscansaveatleast$1,000peracrecomparedtoblankets.MaintenanceReseedanyseededareasthatfailtoestablishatleast80percentcoverStandards(100percentcoverforareasthatreceivesheetorconcentratedflows).Ifreseedingisineffective,useanalternatemethodsuchassodding,mulching.ornets/blankets.Ifwinterweatherpreventsadequategrassgrowth,thistimelimitmayberelaxedatthediscretionofthelocalauthoritywhensensitiveareaswouldotherwisebeprotected.Reseedandprotectbymulchanyareasthatexperienceerosionafterachievingadequatecover.Reseedandprotectbymulchanyerodedarea.Supplyseededareaswithadequatemoisture,butdonotwatertotheextentthatitcausesrunoffApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC120.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.LocaljurisdictionsmaychoosenottoacceptthisproductapprovedasequivalenLormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecy.wa.gov/proErams/wg/stornnvater/newtech/eguivalent.htmlBMPC121:MulchingPurposeMulchingsoilsprovidesimmediatetemporaryprotectionfromerosion.Mulchalsoenhancesplantestablishmentbyconservingmoisture,holdingfertilizer,seed,andtopsoilinplace,andmoderatingsoiltemperatures.Thereisanenormousvarietyofmulchesthatcanbeused.Thissectiondiscussesonlythemostcommontypesofmulch.Asatemporan’covermeasure,mulchshouMbeused:condznoizsofUse•Forlessthan30daysondisturbedareasthatrequirecover.•Atalltimesforseededareas,especiallyduringthewetseasonandolunieConstructionStonniva!erPollutionPieeu/ionuus!2012I duringthehotsummermonths.•Duringthewetseasononslopessteeperthan31T:IVwithmorethan10feetofverticalrelief.Mulchmaybeappliedatanytimeoftheyearandmustberefreshedperiodically.•Forseededareasmulchmaybemadeupof100percent:cottonseedmeal;fibersmadeofwood,recycledcellulose,hemp,kenaf;compost;orblendsofthese.Tackifiershallbeplant-based,suchasguaroralphaplantago,orchemical-basedsuchaspolyaciylamideorpolymers.Anymulchortackifierproductusedshallbeinstalledpermanufacturer’sinstructions.Generally,mulchescomein40-50poundbags.Seedandfertilizerareaddedattimeofapplication.DesignandFormulchmaterials,applicationrates,andspecifications,seeTable4.1.8.InstallationAlwaysusea2-inchminimummulchthickness;increasethethicknessSpecjficationsuntilthegroundis95%covered(i.e.notvisibleunderthemulchlayer).Note:Thicknessmaybeincreasedfordisturbedareasinornearsensitiveareasorotherareashighlysusceptibletoerosion.Mulchusedwithintheordinaryhigh-watermarkofsurfacewatersshouldbeselectedtominimizepotentialflotationoforganicmatter.Compostedorganicmaterialshavehigherspecificgravities(densities)thanstraw,wood,orchippedmaterial.ConsultHydraulicPermitAuthority(HPA)formulchmixesifapplicable.Maintenance•Thethicknessofthecovermustbemaintained.Standards•Anyareasthatexperienceerosionshallberemuichedand/orprotectedwithanetorblanket.Iftheerosionproblemisdrainagerelated,thentheproblemshallbefixedandtheerodedarearemulched.olnincCons/rue/jo,,Stonuwa/erPollutionPreen/ionuus!201220 Table4.1.8MulchStandardsandGuidelinesAiaionNIManaQaiSandardRaRanStrawAir-dried;freefrom2”-3”thick;SCost-effectiveprotectionwhenappliedwithadequatethickness.undesirableseedandbalesper1,000Hand-applicationgenerallyrequiresgreaterthicknessthancoarsematerial.sfor2-3tonsperblownstraw.Thethicknessofstrawmaybereducedbyhalfacrewhenusedinconjunctionwithseeding.Inwindyareasstrawmustbeheldinplacebycrimping,usingatackifier,orcoveringwithnetting,blownstrawalwayshastobeheldinplacewithatackiflerasevenlightwindswillblowitaway.Straw,however,hasseveraldeficienciesthatshouldbeconsideredwhenselectingmulchmaterials.Itofienintroducesand/orencouragesthepropagationofweedspeciesandithasnosignificantlongtermbenefits.Itshouldalsonotbeusedwithintheordinaryhigh-waterelevationofsurfacewaters(duetoflotation).HydromulchNogrowthApprox.25-30Shallbeappliedwithhydromulcher.Shallnotbeusedwithoutinhibitingfactors.lbsper1,000sfseedandtackilierunlesstheapplicationrateisatleastdoubled.or1,500-2,000Fiberslongerthanabout¼-Iinchcloghydromulchequipment.lbsperacreFibersshouldbekepttolessthan¼inch.CompostedNovisiblewateror2”thickmm.;MoreeffectivecontrolcanbeobtainedbyincreasingthicknessMulchanddustduringapprox.100tonsto3”.ExcellentmulchforprotectingfinalgradesuntilComposthandling.Mustbeperacre(approx.landscapingbecauseitcanbedirectlyseededortilledintosoilproducedin800lbsperyard)asanamendment.Compostedmulchhasacoarsersizeaccordancewithgradationthancompost.Itismorestableandpracticaltousein173-350,wetareasandduringrainyweatherconditions.DonotuseSolidWastecompostedmulchnearwetlandsornearphosphorousimpairedHandlingStandards,waterbodies.ChippedSiteAveragesizeshall2”thickmm.;Thisisacost-eflectivewaytodisposeofdebrisfromclearingVegetationbeseveralinches.andgrubbing,anditeliminatestheproblemsassociatedwithGradationsfromburning.Generally,itshouldnotbeusedonslopesabovefinesto6inchesinapprox.10%becauseofitstendencytobetransportedbylengthfortexture,runoff.Itisnotrecommendedwithin200feetofsurfacewaters.variation,andIfseedingisexpectedshortlyaftermulch,thedecompositionofinterlockingthechippedvegetationmaytieupnutrientsimportanttograssproperties.establishment.Wood-basedNovisiblewateror2”thickmm.;Thismaterialisoftencalled“hogorhoggedfuel.”TheuseofMulchorWooddustduringapprox.100tonsmulchultimatelyimprovestheorganicmatterinthesoil.Strawhandling.Mustbeperacre(approx.Specialcautionisadvisedregardingthesourceandcompositionpurchasedfroma800lbs.perolwood-basedmulches.ItspreparationtypicallydoesnotsupplierwithaSolidcubicyard)provideanyweedseedcontrol,soevidenceofresidualWasteHandlingvegetationinitscompositionorknowninclusionofweedplantsPermitoroneorseedsshouldbemonitoredandprevented(orminimized).exemptfromsolidwasteregulations.VoodStrandAblendofloose,2”thickmm.Cost-effectiveprotectionwhenappliedwithadequatethickness.Mulchlong.thinwoodAminimumof95-percentofthewoodstrandshallhavelengthspiecesderivedfrombetween2and10-inches,withawidthandthicknessbetweennativeconiferor1/16atid¼-inches.Themulchshallnotcontainresin,tannin,ordeciduoustreeswithothercompoundsinquantitiesthatwouldbedetrimentaltoplanthighlength-to-widthlife.Sawdustorwoodshavingsshallnotbeusedasmulch.ratio.(WSDOTspecification(9-14.4(4))ohimeCotis!ruc/ionS/ornnt’aterPollutionPreen/ionitus!201221 BMPC122:NetsandBlanketsPurposeErosioncontrolnetsandblanketsareintendedtopreventerosionandholdseedandmulchinplaceonsteepslopesandinchannelssothatvegetationcanbecomewellestablished.Inaddition,somenetsandblanketscanbeusedtopermanentlyreinforceturftoprotectdrainagewaysduringhighflows.Nets(commonlycalledmatting)arestrandsofmaterialwovenintoanopen,buthigh-tensilestrengthnet(forexample.coconutfibermatting).Blanketsarestrandsofmaterialthatarenottightlywoven,butinsteadformalayerofinterlockingfibers.typicallyheldtogetherbyabiodegradableorphotodegradablenetting(forexample,excelsiororstrawblankets).Theygenerallyhavelowertensilestrengththannets,butcoverthegroundmorecompletely.Coir(coconutfiber)fabriccomesasbothnetsandblankets.(‘ondiliousofUseErosioncontrolnetsandblanketsshouldbeused:•Toaidpermanentvegetatedstabilizationofslopes21-I:IVorgreaterandwithmorethan10feetofverticalrelief.•Fordrainageditchesandswales(highlyrecommended).Theapplicationofappropriatenettingorblankettodrainageditchesandswalescanprotectbaresoilfromchannelizedrunoffwhilevegetationisestablished.Netsandblanketsalsocancaptureagreatdealofsedimentduetotheiropen,porousstructure.Netsandblanketscanbeusedtopermanentlystabilizechannelsandmayprovideacost-effective,environmentallypreferablealternativetoriprap.100percentsyntheticblanketsmanufacturedforuseinditchesmaybeeasilyreusedastemporaryditchliners.Disadvantagesofblanketsinclude:•Surfacepreparationrequired.•Onslopessteeperthan2.5H:IV,blanketinstallersmayneedtoberopedandharnessedforsafety.•Theycostatleast$4,000-6,000peracreinstalled.Advantagesofblanketsinclude:•Installationwithoutmobilizingspecialequipment.•Installationbyanyonewithminimaltraining•Installationinstagesorphasesastheprojectprogresses.•Installerscanhandplaceseedandfertilizerastheyprogressdowntheslope.•Installationinanyweather.•Therearenumeroustypesofblanketsthatcanbedesignedwithvariousparametersinmind.Thoseparametersinclude:fiberblend,meshstrength,longevity,biodegradability,cost,andavailability.ohnneConstructionStornnt’a!crPollutionPieen/ionuus!2012‘2 Designand•SeeFiure4.1.3andFiQure4.1.4fortypicalorientationandInstallationinstallationofblanketsusedinchannelsandasslopeprotection.Note:Specjflcutionsthesearetypicalonly;allblanketsmustbeinstalledpermanufacturer’sinstallationinstructions.Installationiscriticaltotheeffectivenessoftheseproducts.Ifgoodgroundcontactisnotachieved.runoffcanconcentrateundertheproduct,resultinginsignificanterosion.InstallationofBlanketsonSlopes:I.Completefinalgradeandtrackwalkupanddowntheslope.2.Installhydromulehwithseedandfertilizer.3.Digasmalltrench,approximately12incheswideby6inchesdeepalongthetopoftheslope.4.Installtheleadingedgeoftheblanketintothesmalltrenchandstapleapproximatelyevery18inches.NOTE:Staplesaremetal,“U”-shaped,andaminimumof6incheslong.Longerstaplesareusedinsandysoils.Biodegradablestakesarealsoavailable.5.Rolltheblanketslowlydowntheslopeasinstallerwalksbackwards.NOTE:Theblanketrestsagainsttheinstaller’slegs.Staplesareinstalledastheblanketisunrolled.Itiscriticalthattheproperstaplepatternisusedfortheblanketbeinginstalled.Theblanketisnottobeallowedtorolldowntheslopeonitsownasthisstretchestheblanketmakingitimpossibletomaintainsoilcontact.Inaddition,nooneisallowedtowalkontheblanketafteritisinplace.6.Iftheblanketisnotlongenoughtocovertheentireslopelength,thetrailingedgeoftheupperblanketshouldoverlaptheleadingedgeofthelowerblanketandbestapled.Onsteeperslopes,thisoverlapshouldbeinstalledinasmalltrench,stapled,andcoveredwithsoil.Withthevarietyofproductsavailable,itisimpossibletocoverallthedetailsofappropriateuseandinstallation.Therefore,itiscriticalthatthedesignengineerconsultthemanufacturersinformationandthatasitevisittakesplaceinordertoensurethattheproductspecifiedisappropriate.Informationisalsoavailableatthefollowingwebsites:1.WSDOT(Section3.2.4):http://www.wsdot.wa.gov/NR!rdonlyres/3B4IE087-FA86-4717-932D-D7A8556CCD57/O/ErosionTraininaManual.pdf2.TexasTransportationInstitute:http://www.txdot.govfbusiness/doingbusiness/productevaluation!erosioncontrol.htmoIzll;?c’ConstruclionS/or,nii’c,/erPollutionPieen/ioniius!20122 •Usejutemattinginconjunctionwithmulch(BMPC121).Excelsior,wovenstrawblanketsandcoir(coconutfiber)blanketsmaybeinstalledwithoutmulch.Therearemanyothertypesoferosioncontrolnetsandblanketsonthemarketthatmaybeappropriateincertaincircumstances.•Ingeneral,mostnets(e.g.,jutematting)requiremulchinordertopreventerosionbecausetheyhaveafairlyopenstructure.Blanketstypicallydonotrequiremulchbecausetheyusuallyprovidecompleteprotectionofthesurface.•Extremelysteep,unstable,‘vet,orrockyslopesareoftenappropriatecandidatesforuseofsyntheticblankets,asareriverbanks,beachesandotherhigh-energyenvironments.Ifsyntheticblanketsareused,thesoilshouldbehvdromulchedfirst.•100-percentbiodegradableblanketsareavailableforuseinsensitiveareas.Theseorganicblanketsareusuallyheldtogetherwithapaperorfibermeshandstitchingwhichmaylastuptoayear.•Mostnettingusedwithblanketsisphotodegradable.meaningtheybreakdownundersunlight(notUVstabilized).However,thisprocesscantakemonthsoryearsevenunderbrightsun.Oncevegetationisestablished,sunlightdoesnotreachthemesh.Itisnotuncommontofindnon-degradednettingstillinplaceseveralyearsafterinstallation.Thiscanbeaproblemifmaintenancerequirestheuseofmowersorditchcleaningequipment.Tnaddition,birdsandsmallanimalscanbecometrappedinthenetting.Maintenance•Maintaingoodcontactwiththeground.ErosionmustnotoccurStandardsbeneaththenetorblanket.•Repairandstapleanyareasofthenetorblanketthataredamagedornotinclosecontactwiththeground.•Fixandprotecterodedareasiferosionoccursdue10poorlycontrolleddrainage.olwncConstructionStornni’aterPollutionPit’eu/ioniius!20)22 InitIalChannelAnchorTrenchNOTES:1.Checkplot,lobeeoo,wactedpermanufacorm.peciflcationL2.Stakingorstaplinglayoutpetmanufnrn.pcdliadou’.Figure4.1.3—ChannelInstallationFigure4.1.4—SlopeInstallationohmwConstructionStornnt’atc’rPollutionPieen/ionuus!2012LorçlkTh&ArtlorTrorchTerminalSlopeandChannelAnchorTrenchO4?IntermittentCheckSlotSlopesurfaceshallbesmoothbeforeplacementforpropersoilcontact.Staplingpatternaspermanufacturer’srecommendatic-ns.Mm.2OverlapIfthereisabermatthetopofslope,anchorupslopeoftheberm.Anchorhi&x6’mhi.Trenchandstapleat12”intervals.Mm.6’overlap.Stapleoverlapsmax.5”spacing.Bringmaterialdowntoalevelarea,turnDonotstretchblanketsimattingstight-theendunder4”andstapleat12’intervals.allowtherollstomoldtoanyirregularities.Forslopeslessthan3H1V,rollsmaybeplacedinhorizontalstrips,Lime,ferlilize,andseedbeforeinstallation.Plantingofshrubs,trees,etc.Shouldoccurafterinstallation.2 BMPC123:PlasticCoveringPurposePlasticcoveringprovidesimmediate,short-termerosionprotectiontoslopesanddisturbedareas.ConditionsofPlasticcoveringmaybeusedondisturbedareasthatrequirecoverUsemeasuresforlessthan30days,exceptasstatedbelow.•Plasticisparticularlyusefulforprotectingcutandfillslopesandstockpiles.Note:Therelativelyrapidbreakdownofmostpolyethylenesheetingmakesitunsuitableforlong-term(greaterthansixmonths)applications.•Duetorapidrunoffcausedbyplasticcovering,donotusethismethodupsiopeofareasthatmightbeadverselyimpactedbyconcentratedrunoff.Suchareasincludesteepand/orunstableslopes.•Plasticsheetingmayresultinincreasedrunoffvolumesandvelocities,requiringadditionalon-sitemeasurestocounteracttheincreases.Creatingatroughwithwattlesorothermaterialcanconveycleanwaterawayfromtheseareas.•Topreventundercutting,trenchandbackfillrolledplasticcoveringproducts.•Whileplasticisinexpensivetopurchase,theaddedcostofinstallation,maintenance,removal,anddisposalmakethisanexpensivematerial,upto$1.50-2.00persquareyard.•Wheneverplasticisusedtoprotectslopesinstallwatercollectionmeasuresatthebaseoftheslope.Thesemeasuresincludeplastic-coveredberms.channels,andpipesusedtocoveycleanrainwaterawayfrombaresoilanddisturbedareas.Donotmixcleanrunofffromaplasticcoveredslopewithdirtyrunofffromaproject.•Otherusesforplasticinclude:1.Temporaryditchliner.2.Pondlinerintemporarysedimentpond.3.Lincrforbcrmcdtcmporaiyfuelstoragearcaifplasticisnotreactivetothetypeoffuelbeingstored.4.Emergencyslopeprotectionduringheavyrains.5.Temporarydrainpipe(“elephanttrunk”)usedtodirectwater.Designand•Plasticslopecovermustbeinstalledasfollows:InstallationI.Runplasticupanddownslopc,notacrossslope.Specifications2.Plasticmaybeinstalledperpendiculartoaslopeiftheslopelengthislessthan10feet.3.Minimumof8-inchoverlapatseams.ohiineCons!uzictio,zStonmi’aterPollutionPieen/iouiius!2012 4.Onlongorwideslopes,orslopessubjecttowind,tapeallseams.5.Placeplasticintoasmall(12-inchwideby6-inchdeep)slottrenchatthetopoftheslopeandbackfillwithsoiltokeepwaterfromflowingunderneath.6.Placesandfilledburlaporgeotextilebagsevery3to6feetalongseamsandtiethemtogetherwithtwinetoholdtheminplace.7.Inspectplasticforrips,tears,andopenseamsregularlyandrepairimmediately.Thispreventshighvelocityrunofffromcontactingbaresoilwhichcausesextremeerosion.8.Sandbagsmaybeloweredintoplacetiedtoropes.However,allsandbagsmustbestakedinplace.•Plasticsheetingshallhaveaminimumthicknessof0.06millimeters.•Tferosionatthetoeofaslopeislikely,agravelberm,riprap,orothersuitableprotectionshallbeinstalledatthetoeoftheslopeinordertoreducethevelocityofrunoff.Maintenance•Tornsheetsmustbereplacedandopenseamsrepaired.Standards•Completelyremoveandreplacetheplasticifitbeginstodeteriorateduetoultravioletradiation.•Completelyremoveplasticwhennolongerneeded.•Disposeofoldtiresusedtoweightdownplasticsheetingappropriately.ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC123.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionalEestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://wwxv.ecy.wa.ov/proarams/wg/stormwater/newtech/eguivalent.htmlBMPC124:SoddingPurposeThepurposeofsoddingistocstablishpermanentturfforimmediateerosionprotectionandtostabilizedrainagewayswhereconcentratedoverlandflowwilloccur.C’onditionsofUseSoddingmaybeusedinthefollowingareas:•Disturbedareasthatrequireshort—termorlong-termcover.•Disturbedareasthatrequireimmcdiatcvegetativecover.•Allwaterwaysthatrequirevegetativelining.Watenvaysmayalsobeseededratherthansodded,andprotectedwithanetorblanket.olunwConsflue/ionS/ornnraterPollutionPieeu/b,,iijust20127 DesignandSodshallbefreeofweeds.ofuniformthickness(approximately1-inchInstallationthick).andshallhaveadenserootmatformechanicalstrength.SpecjficutionsThefollowingstepsarerecommendedforsodinstallation:Shapeandsmooththesurfacetofinalgradeinaccordancewiththeapprovedgradingplan.Theswaleneedstobeoverexcavated4to6inchesbelowdesignelevationtoallowroomforplacingsoilamendmentandsod.•Amend4inches(minimum)ofcompostintothetop8inchesofthesoiliftheorganiccontentofthesoilislessthantenpercentorthepermeabilityislessthan0.6inchesperhour.Seehttp://www.ecv.va.2ov/prourams/swfaioruanics/soil.hunlforfurtherinformation.•Fertilizeaccordingtothesuppliersrecommendations.•WorklimeandfertilizerIto2inchesintothesoil,andsmooththesurface.•Laystripsofsodbeginningatthelowestareatobesoddedandperpendiculartothedirectionofwaterflow.Wedgestripssecurelyintoplace.Squaretheendsofeachstriptoprovideforaclose,tightfit.Staggerjointsatleast12inches.Stapleonslopessteeperthan3H:JV.Stapletheupstreamedgeofeachsodstrip.•Rollthesoddedareaandirrigate.•Whensoddingiscarriedoutinalternatingstripsorotherpatterns,seedtheareasbetweenthesodimmediatelyaftersodding.MaintenanceIfthegrassisunhealthy,thecauseshallbedeterminedandappropriateStandardsactiontakentoreestablishahealthygroundcover.Ifitisimpossibletoestablishahealthygroundcoverduetofrequentsaturation,instability,orsomeothercause,thesodshallberemoved,theareaseededwithanappropriatemix,andprotectedwithanetorblanket.BMPC125:TopsoilingICompostingPurposeTopsoilingandcompostingprovidcasuitablegrowthmediumforfinalsitestabilizationwithvegetation.Whilenotapermanentcoverpracticeinitself,topsoilingandcompostingareanintegralcomponentofprovidingpermanentcoverinthoseareaswherethereisanunsuitablesoilsurfaceforplantgrowth.UsethisBMPinconjunctionwithotherBMPssuchasseeding,mulching,orsodding.Nativesoilsanddisturbedsoilsthathavebeenorganicallyamendednotonlyretainmuchmorestoimwater,buttheyalsoserveaseffectivebiofiltersforurbanpollutantsand,bysupportingmorevigorousplantgrowth,reducethewater,fertilizerandpesticidesneededtosupportohmicConstructionStonnwaterPollutionPieeniloniinsf20127 installedlandscapes.Topsoildoesnotincludeanysubsoilsbutonlythematerialfromthetopseveralinchesincludingorganicdebris.Conditionsof.PermanentlandscapedareasshallcontainhealthytopsoilthatreducesUsetheneedforfertilizers,improvesoveralltopsoilquality,providesforbettervegetalhealthandvitality,improveshydrologiccharacteristics,andreducestheneedforirrigation.Leavenativesoilsandthedufflayerundisturbedtothemaximumextentpracticable.Strippingofexisting,properlyffinctioningsoilsystemandvegetationforthepurposeoftopsoilingduringconstructionisnotacceptable.Preserveexistingsoilsystemsinundisturbedanduncompactedconditionsifflrnctioningproperly.•Areasthatalreadyhavegoodtopsoil,suchasundisturbedareas,donotrequiresoilamendments.•Restore,tothemaximumextentpractical,nativesoilsdisturbedduringclearingandgradingtoaconditionequaltoorbetterthantheoriginalsitecondition’smoisture-holdingcapacity.Useon-sitenativetopsoil,incorporateamendmentsintoon-sitesoil,orimportblendedtopsoiltomeetthisrequirement.•Topsoilingisarequiredprocedurewhenestablishingvegetationonshallowsoils,andsoilsofcriticallylowp1-i(highacid)levels.•Bewareofwherethetopsoilcomesfrom,andwhatvegetationwasonsitebeforedisturbance,invasiveplantseedsmaybeincludedandcouldcauseproblemsforestablishingnativeplants,landscapedareas,orgrasses.•TopsoilfromthesitewiHcontainmycorrhizalbacteriathatarenecessaryforhealthyrootgrowthandnutrienttransfer.Thesenativemycorrhizaareacclimatedtothesiteandwillprovideoptimumconditionsforestablishinggrasses.Usecommerciallyavailablemycorrhizaproductswhenusingoff-sitetopsoil.DesignandMeetthefollowingrequirementsforareasrequiringdisruptionandInstallationtopsoiling:Specffications•Maximizethedepthofthetopsoilwhereverpossibletoprovidethemaximumpossibleinfiltrationcapacityandbeneficialgrowthmedium.Topsoilshallhave:Aminimumdepthof8-inches.Scarifysubsoilsbelowthetopsoillayeratleast4-incheswithsomeincorporationoftheuppermaterialtoavoidstratifiedlayers,wherefeasible.Rippingorrestructuringthesubgrademayalsoprovideadditionalbenefitsregardingtheoverallinfiltrationandintcrflowdynamicsofthcsoilsystem.ohiiiit’Co,zs/muc/jo,,S!ornnt’a/e,PoihilionPieen/ioniius!20122 •Aminimumorganiccontentof10%dry’weight.and5%organicmattercontentinturfareas.Incorporateorganicamendmentstoaminimum8-inchdepthexceptwheretreerootsorothernaturalfeatureslimitthedepthofincorporation.•ApHbetween6.0and8.0ormatchingthepHoftheundisturbedsoil.•Ifblendedtopsoilisimported,thenfinesshouldbelimitedto25percentpassingthrougha200sieve.AccomplishtherequiredorganiccontentandpETbyeitherreturningnativetopsoiltothesiteand/orincorporatingorganicamendments.•Tomeettheorganiccontentusecompostthatmeetsthedefinitionof”compostedmaterials”in\VAC173-350-220.Thiscodeisavailableonlineat:http://apps.len.wa.ov/WAC/default.aspx?cite=173-350-220.Thecompostmustalsohaveanorganicmattercontentof35%to65%,andacarbontonitrogenratiobelow25H:IV.Thecarbontonitrogenratiomaybeashighas35H:IVforplantingscomposedentirelyofplantsnativetothePugetSoundLowlandsregion.•Fortillsoilsuseamixtureofapproximatelytwopartssoiltoonepartcompost.Thisequatesto4inchesofcompostmixedtoadepthof12inchesintiltsoils.Increasingtheconcentrationofcompostbeyondthislevelcanhavenegativeeffectsonvegetalhealth,whiledecreasingtheconcentrationscanreducethebenefitsofamendedsoils.•Gravelorcobbleoutwashsoils,mayrequiredifferentapproaches.Organicsandfineseasilymigratethroughtheloosestructureofthesesoils.Therefore,theimportationofatleast6inchesofqualitytopsoil,underlainbysometypeoffilterfabrictopreventthemigrationoffines,maybemoreappropriateforthesesoils.•Thefinalcompositionandconstructionofthesoilsystemwillresultinanaturalselectionorfavoringofcertainplantspeciesovertime.Forexample,incorporationoftopsoilmayfavorgrasses,whilelayeringwithmildlyacidic,high-carbonamendmentsmayfavormorewoodyvegctation.•Allowsufficienttimeinschedulingfortopsoilspreadingpriortoseeding,sodding,orplanting.•Takecarewhenapplyingtopsoiltosubsoilswithcontrastingtextures.Sandytopsoiloverclayeysubsoilisaparticularlypoorcombination,aswatercreepsalongthcjunctionbetweenthesoillayersandcausesthetopsoiltoslough.Iftopsoilandsubsoilarenotproperlybonded,waterwillnotinfiltratethesoilprofileevenlyanditwillbedifficulttoolunwCons/nicIlo;,&onnil’a!erPollutlo,,Preen!ioniius!2012U establishvegetation.Thebestmethodtopreventalackofbondingistoactuallyworkthetopsoilintothelayerbelowforadepthofatleast6inches.Fieldexplorationofthesheshallbemadetodetermineifthereissurfacesoilofsufficientquantityandqualitytojustifystripping.Topsoilshallbefriableandloamy(loam,sandyloam,siltloam,sandyclayloam,andclayloam).Avoidareasofnaturalgroundwaterrecharge.•Strippingshallbeconfinedtotheimmediateconstructionarea.A4-inchto6-inchstrippingdepthiscommon,butdepthmayvarydependingontheparticularsoil.Allsurfacerunoffcontrolstructuresshallbeinplacepriortostripping.•Donotplacetopsoilwhileinafrozenormuddycondition,whenthesubgradeisexcessivelywet,orwhenconditionsexistthatmayotherwisebedetrimentaltopropergradingorproposedsoddingorseeding.•Inanyareasrequiringgradingremoveandstockpilethedufflayerandtopsoilonsiteinadesignated,controlledarea,notadjacenttopublicresourcesandcriticalareas.Stockpiledtopsoilistobereappliedtootherportionsofthesitewherefeasible.•Locatethetopsoilstockpilesothatitmeetsspecificationsanddoesnotinterferewithworkonthesite.ftmaybepossibletolocatemorethanonepileinproximitytoareaswheretopsoilwillbeused.Stockpilingoftopsoilshalloccurinthefollowingmanner:•Sideslopesofthestockpileshallnotexceed2H:JV.•BetweenOctober1andApril30:•Aninterceptordikewithgraveloutletandsiltfenceshallsurroundalltopsoil.•Within2dayscompleteerosioncontrolseeding,orcoveringstockpileswithclearplastic,orothermulchingmaterials.•BetweenMayIandSeptember30:•Aninterceptordikewithgraveloutletandsiltfenceshallsurroundalltopsoilifthestockpilewillremaininplaceforalongerperiodoftimethanactiveconstructiongrading.•Within7dayscomplctccrosioncontrolsccding,orcoveringstockpileswithclearplastic,orothermulchingmaterials.Whennativetopsoilistobestockpiledandreusedthefollowingshouldapplytoensurethatthencorrhizalbacterial,earthworms,andotherbeneficialorganismswillnotbedestroyed:I.Re-installtopsoilwithin4to6weeks.oluineConstructionStornni’aterPollutionPieentioniius!2012I •2.Donotallowthesaturationoftopsoilwithwater.3.Donotuseplasticcovering.Maintenaitce.Inspectstockpilesregularly,especiallyafterlargestormevents.StandardsStabilizeanyareasthathaveeroded.•Establishsoilqualityanddepthtowardtheendofconstructionandonceestablished,protectfromcompaction.suchasfromlargemachineryuse,andfromerosion.•Plantandmulchsoilafterinstallation.•Leaveplantdebrisoritsequivalentonthesoilsurfacetoreplenishorganicmatter.•Reduceandadjust,wherepossible,theuseofirrigation,fertilizers,herbicidesandpesticides,ratherthancontinuingtoimplementformerlyestablishedpractices.BMPC126:Polyacrylamide(PAM)forSoilErosionProtectionPurposePolyacrylamide(PAM)isusedonconstructionsitestopreventsoilerosion.ApplyingPAMtobaresoilinadvanceofaraineventsignificantlyreduceserosionandcontrolssedimentintwoways.First,PAMincreasesthesoil’savailableporevolume,thusincreasinginfiltrationthroughflocculationandreducingthequantityofstormwaterrunoff.Second,itincreasesflocculationofsuspendedparticlesandaidsintheirdeposition,thusreducingstomwvaterrunoffturbidityandimprovingwaterquality.ConditionsofUsePAMshallnotbedirectlyappliedtowaterorallowedtoenterawaterbody.Inareasthatdraintoasedimentpond,PAMcanbeappliedtobaresoilunderthefollowingconditions:•Duringroughgradingoperations.•InStagingareas.•Balancedcutandfillearthwork.•Haulroadspriortoplaccmcntofcrushedrocksurfacing.•Compactedsoilroadbase.•Stockpiles.•Afterfinalgradeandbeforepavingorfinalseedingandplanting.•Pitsites.ohuneConstructionStonnwaterPollutionPieentionitus!2012 •Siteshavingawintershutdown.Inthecaseofwintershutdown,orwheresoilwillremainunworkedforseveralmonths.PAMshouldbeusedtogetherwithmulch.PAMmaybeappliedwithwaterindissolvedform.ThepreferredDesignand.applicationmethodisthedissolvedform.InstallationSpecjficationsPAMistobeappliedatamaximumrateof2/3poundPAMper1,000gallonswater(80mg/L)perIacreofbaresoil.Table4.1.9canbeusedtodeterminethePAMandwaterapplicationrateforadisturbedsoilarea.HigherconcentrationsofPAMdonoprovideanyadditionaleffectiveness.Table4.1.9PAMandWaterApplicationRatesDirdAra(a)PAM(1War(al0.500.33500I.000.66I,0001.50I.001,5002.001.322,0002.50I.652,5003.002.003,0003.502.333,5004.002.654,0004.503.004,5005.003.335.000ThePreferredMethod:•Pre-measuretheareawherePAMistobeappliedandcalculatetheamountofproductandwaternecessarytoprovidecoverageatthespecifiedapplicationrate(2/3poundPAM/I000gallons/acre).•PAMhasinfinitesolubilityinwater,butdissolvesveryslowly.Dissolvepre-measureddrygranularPAMwithaknownquantityofcleanwaterinabucketseveralhoursorovernight.MechanicalmixingwillhelpdissolvethePAM.AlwaysaddPAMtowater-notwatertoPAM.•Pre—fillthewatertruckabout1/8fillwithwater.Thewaterdoesnothavetobepotable,butitmusthaverelativelylowturbidity—intherangeof20NTUorless.•AddPAM/Watermixturetothetruck•Completelyfillthewatertrucktospecifiedvolume.•SprayPAM/Watermixtureontodrysoiluntilthesoilsurfaceisuniformlyandcompletelywetted.AmAlternateMethod:ohilneConstructionS/onnwa/crPollutionPvc’cm/ioniius!2012 PAMmayalsobeappliedasapowderattherateof5lbs.peracre.Thismustbeappliedonadaythatisdry’.Forareaslessthan5-10acres,ahand-held“organgrinder”fertilizerspreadersettothesmallestsettingwillwork.Tractor-mountedspreaderswillworkforlargerareas.ThefollowingshallbeusedforapplicationofpowderedPAM:•PoweredPAMshallbeusedinconjunctionwithotherBMPsandnotinplaceofotherBMPs.•DonotusePAMonaslopethatflowsdirectlyintoastreamorwetland.ThestormwaterrunoffshallpassthroughasedimentcontrolBMPpriortodischargingtosurfacewaters.•DonotaddPAMtowaterdischargingfromsite.•Whenthetotaldrainageareaisgreaterthanorequalto5acres,PAMtreatedareasshalldraintoasedimentpond.•Areaslessthan5acresshalldraintosedimentcontrolBMPs,suchasaminimumof3checkdamsperacre.Thetotalnumberofcheckdamsusedshallbemaximizedtoachievethegreatestamountofsettlementofsedimentpriortodischargingfromthesite.Eachcheckdamshallbespacedevenlyinthedrainagechannelthroughwhichstormwaterflowsaredischargedoff-site.•Onallsites,theuseofsiltfenceshallbemaximizedtolimitthedischargesofsedimentfromthesite.•Allareasnotbeingactivelyworkedshallbecoveredandprotectedfromrainfall.PAMshallnotbetheonlycoverBMPused.•PAMcanbeappliedtowetsoil,butdrysoilispreferredduetolesssedimentloss.•PAMwillworkwhenappliedtosaturatedsoilbutisnotaseffectiveasapplicationstodryordampsoil.•KeepthegranularPAMsupplyoutofthesun.GranularPAMlosesitseffectivenessinthreemonthsafterexposuretosunlightandair.•Properapplicationandre-applicationplansarcnecessarytoensuretotaleffectivenessofPAMusage.•PAM.combinedwithwater,isyen’slipperyandcanbeasafetyhazard.CaremustbetakentopreventspillsofPAMpowderontopavedsurfaces.DuringanapplicationofPAM,preventover-sprayfromreachingpavementaspavementwillbecomeslippery.IfPAMpowdergetsonskinorclothing,wipeitoffwitharoughtowelratherthanwashingwithwater-thisonlymakescleanupmessierandtakelonger.•SomePAMsaremoretoxicandcarcinogenicthanothers.OnlythemostenvironmentallysafePAMproductsshouldbeused.ohiiiieConstructionStornurcuerPollutionfireeu/ionuus!2012 ThespecificPAMcopolymerformulationmustbeanionic.CaioniPAManodinanaiaionaofnonaa1oIIroOnlythehighestdrinkingwatergradePAM,certifiedforcompliancewithANSI/NSFStandard60fordrinkingwatertreatment.vilIbeusedforsoilapplications.RecentmediaattentionandhighinterestinPAMhasresultedinsomeentrepreneurialexploitationoftheterm“polynwr“AllPAMarepolymers,butnotallpolymersarePAM,andnotallPAMproductscomplywithANSI/NSFStandard60.PAMuseshallbereviewedandapprovedbythelocalpermittingauthority.PAMdesignatedfortheseusesshouldbe“watersoluble”or“linearor“non-crosslinked”.Cross-linkedorwaterabsorbentPAM,polymerizedinhighlyacidic(p1-1<2)conditions,areusedtomaintainsoilmoisturecontent.ThePAManionicchargedensitymayvaryfrom2-30percent;avalueof18percentistypical.StudiesconductedbytheUnitedStatesDepartmentofAgriculture(USDA)/ARSdemonstratedthatsoilstabilizationwasoptimizedbyusingveryhighmolecularweight(12-15mg/mole),highlyanionic(>20%hydrolysis)PAM.•PAMtackifiersareavailableandbeingusedinplaceofguarandalphaplantago.Typically,PAMtackifiersshouldbeusedatarateofnomorethan0.5-1lb.per1000gallonsofwaterinahydromulehmachine.Sometackifierproductinstructionssaytouseatarateof3—5lbs.peracre,whichcanbetoomuch.Inaddition,pumpproblemscanoccurathigherratesduetoincreasedviscosity.Mai,,tenjuice•PAMmaybereappliedonactivelyworkedareasaftera48-hourStandardsperiod.•ReapplicationisnotrequiredunlessPAMtreatedsoilisdisturbedorunlessturbiditylevelsshowtheneedforanadditionalapplication.IfPAMtreatedsoilisleftundisturbedareapplicationmaybenecessaryaftertwomonths.MorePAMapplicationsmayberequiredforsteepslopes,siltyandclayeysoils(USDAClassificationType“C’and“D”soils).longgrades,andhighprecipitationareas.WhenPAMisappliedfirsttobaresoilandthencoveredwithstraw,areapplicationmaynotbenecessaryforseveralmonths.•LossofsedimentandPAMmaybeabasisforpenaltiesperRCW90.48.080.BMPC130:SurfaceRougheningPurposeSurfacerougheningaidsintheestablishmentofvegetativecover,reducesrunoffvelocity,increasesinfiltration,andprovidesforsedimenttrappingthroughtheprovisionofaroughsoilsurface.HorizontaldepressionsareohuncCons!rue/ionS/ornn’a/erPollutionPrecut/oniius!2012 createdbyoperatingatillerorothersuitableequipmentonthecontourorbyleavingslopesinaroughenedconditionbynotfinegradingthem.UsethisBMPinconjunctionwithotherBMPssuchasseeding.mulching,orsodding.Corn!itionsfor.Allslopessteeperthan3H:IVandgreaterthan5verticalfeetUserequiresurfacerougheningtoadepthof2to4inchespriortoseeding..•Areasthatwillnotbestabilizedimmediatelymayberoughenedtoreducerunoffvelocityuntilseedingtakesplace.•Slopeswithastablerockfacedonotrequireroughening.•Slopeswheremowingisplannedshouldnotbeexcessivelyroughened.DesignandTherearedifferentmethodsforachievingaroughenedsoilsurfaceonaInsta!!ationslope,andtheselectionofanappropriatemethoddependsuponihetypeofSpecjflcationsslope.Rougheningmethodsincludestair-stepgrading,grooving,contourffirrows,andtracking.SeeFiuure4.1.5fortrackingandcontourfurrows.Factorstobeconsideredinchoosingamethodareslopesteepness,mowingrequirements,andwhethertheslopeisformedbycuttingorfilling.•Disturbedareasthatwillnotrequiremowingmaybestair-stepgraded,grooved,orleftroughafterfilling.•Stair-stepgradingisparticularlyappropriateinsoilscontaininglargeamountsofsoftrock.Each“step’catchesmaterialthatsloughsfromabove,andprovidesalevelsitewherevegetationcanbecomeestablished.Stairsshouldbewideenoughtoworkwithstandardearthmovingequipment.Stairstepsmustbeoncontourorgullieswillformontheslope.•Areasthatwillbemowed(theseareasshouldhaveslopeslesssteepthan3H:IV)mayhavesmallfurrowsleftbydisking,harrowing,raking,orseed-plantingmachineryoperatedonthecontour.•Gradedareaswithslopessteeperthan3H:IVbutlessthan2H:IVshouldberoughenedbeforeseeding.Thiscanbeaccomplishedinavarietyofways.including‘trackwalking,’ordrivingacrawlertractorupanddowntheslope,leavingapatternofcleatimprintsparalleltoslopecontours.•TrackingisdonebyoperatingequipmentupanddowntheslopetoIcavehorizontaldepressionsinthesoil.Maintenance•AreasthataregradedinthismannershouldbeseededasquicklyasStandardspossible.•Regularinspectionsshouldbemadeofthearea.Ifrillsappear,theyshouldbere-gradedandre-seededimmediately.ohinwConstructionStorunraterPollutionPreentionitust2012 Trackingaa_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-aaaaaaaaaaaaaaa_aaaaaaaaContourFurrowsTRACKING’withmachineryupanddowntheslopeprovidesgroovesthatwillcatchseed,raInfallandreducerunoff.50’(150mm)Madmum1GroovesWillCatchSeed,Fertilizer,Mulch,RainfallandDecreaseRunoff.Figure4.1.5—SurfaceRougheningbyTrackingandContourFurrowsolinneConstrue/to,,S!onnii’a!erPollutionPit’en/iouiius!2012 BMPC131:GradientTerracesPurposeGradientterracesreduceerosiondamagebyinterceptingsurfacerunoffandconductingittoastableoutletatanon-erosivevelocity.C’o,,ditionsofUse•Gradientterracesnormallyarelimitedtodenudedlandhavingawatererosionproblem.Theyshouldnotbeconstructedondeepsandsoronsoilsthataretoostony,steep,orshallowtopermitpracticalandeconomicalinstallationandmaintenance.Gradientterracesmaybeusedonlywheresuitableoutletsareorwillbemadeavailable.SeeFigure4.1.6forgradientterraces.Designand•ThemaximumverticalspacingofgradientterracesshouldbeInstallationdeterminedbythefollowingmethod:Specj/lcationsVI(O.8)s+yWhere:VI=verticalintervalinfeets=landriseper100feet,expressedinfeety=asoilandcovervariablewithvaluesfrom1.0to4.0Valuesof”y”areinfluencedbysoilerodibilityandcoverpractices.Thelowervaluesareapplicabletoerosivesoilswherelittletonoresidueisleftonthesurface.Thehighervalueisapplicableonlytoerosion-resistantsoilswherealargeamountofresidue(1¼tonsofstraw/acreequivalent)isonthesurface.•Theminimumconstructedcross-sectionshouldmeetthedesigndimensions.•Thetopoftheconstructedridgeshouldnotbeloweratanypointthanthedesignelevationplusthespecifiedoverfillforsettlement.Theopeningattheoutletendoftheterraceshouldhaveacrosssectionequaltothatspecifiedfortheterracechannel.•Channelgradesmaybeeitheruniformorvariablewithamaximumgradeof0.6feetper100feetlength(0.6%).Forshortdistances,terracegradcsmaybeincrcascdtoimprovealignment.Thechannelvelocityshouldnotexceedthatwhichisnonerosiveforthesoiltype.•Allgradientterracesshouldhaveadequateoutlets.Suchanoutletmaybeagrassedwaterway,vegetatedarea,ortileoutlet.Inallcasestheoutletmustconveyrunofffromtheterraceorterracesystemtoapointwhcrctheoutflowwillnotcauscdamage.Vegetativecovershouldbeusedintheoutletchannel.•Thedesignelevationofthewatersurfaceoftheterraceshouldnotbelowerthanthedesignelevationofthewatersurfaceintheoutletattheirjunction,whenbothareoperatingatdesignflow.ohimeConstructionStonnwa/erPollutionPieen/ioniius!2012 •Verticalspacingdeterminedbytheabovemethodsmaybeincreasedasmuchas0.5feetor10percent,whicheverisgreater,toprovidebetteralignmentorlocation,toavoidobstacles,toadjustforequipmentsize,ortoreachasatisfactoryoutlet.Thedrainageareaabovetheterraceshouldnotexceedtheareathatwouldbedrainedbyaterracewithnormalspacing.•Theterraceshouldhaveenoughcapacitytohandlethepeakrunoffexpectedfroma2-year,24-hourdesignstormwithoutovertopping.•Theterracecross-sectionshouldbeproportionedtofitthelandslope.Theridgeheightshouldincludeareasonablesettlementfactor.Theridgeshouldhaveaminimumtopwidthof3feetatthedesignheight.Theminimumcross-sectionalareaoftheterracechannelshouldbeSsquarefeetforlandslopesof5percentorless,7squarefeetforslopesfrom5to8percent,and6squarefeetforslopessteeperthan8percent.Theterracecanbeconstructedwideenoughtobemaintainedusingasmallvehicle.Mahztena,,ce•Maintenanceshouldbeperformedasneeded.TerracesshouldbeStandardsinspectedregularly;atleastonceayear,andafterlargestormevents.Slopetoadequate10mm.Figure4.1.6—GradientTerracesobtineConstructionSIonnwaterPollutionPreeu/ionitust2012 BMPC140:DustControlPurposeDustcontrolpreventswindtransportofdustfromdisturbedsoilsurfacesontoroadways.drainageways.andsurfacewaters.conditionsofUse•Inareas(includingroadways)subjecttosurfaceandairmovementofdustwhereon-siteandoff-siteimpactstoroadways,drainageways,orsurfacewatersarelikely.Designand.Vegetateormulchareasthatwillnotreceivevehicletraffic.InareasInstallationwhereplanting,mulching,orpavingisimpractical,applygravelorSpecicationslandscapingrock.•Limitdustgenerationbyclearingonlythoseareaswhereimmediateactivitywilltakeplace,leavingtheremainingarea(s)intheoriginalcondition.Maintaintheoriginalgroundcoveraslongaspractical.•Constructnaturalorartificialwindbreaksorwindscreens.Thesemaybedesignedasenclosuresforsmalldustsources.•Sprinklethesitewithwateruntilsurfaceiswet.Repeatasneeded.Topreventcarryoutofmudontostreet.refertoStabilizedConstructionEntrance(BMPCl05).•Irrigationwatercanbeusedfordustcontrol.Irrigationsystemsshouldbeinstalledasafirststeponsiteswheredustcontrolisaconcern.•Sprayexposedsoilareaswithadustpalliative,followingthemanufacturer’sinstructionsandcautionsregardinghandlingandapplication.Usedoilisprohibitedfromuseasadustsuppressant.LocalgovernmentsmayapproveotherdustpalliativessuchascalciumchlorideorPAM.•PAM(BMPCl26)addedtowateratarateof0.5lbs.per1,000gallonsofwaterperacreandappliedfromawatertruckismoreeffectivethanwateralone.Thisisduetoincreasedinfiltrationofwaterintothesoilandreducedevaporation.Inaddition,smallsoilparticlesarebondedtogetherandarenotaseasilytransportedbywind.AddingPAMmayactuallyreducethequantityofwaterneededfordustcontrol.UseofPAMcouldbeacost-effectivedustcontrolmethod.Techniquesthatcanbeusedforunpavedroadsandlotsinclude:•Lowerspeedlimits.Highvehiclespeedincreasestheamountofduststirredupfromunpavedroadsandlots.•Upgradctheroadsurfacestrcngthbyimprovingparticlesize,shapc.andmineraltypesthatmakeupthesurfaceandbasematerials.•Addsurfacegraveltoreducethesourceofdustemission.Limittheamountoffineparticles(thosesmallerthan.075mm)to10to20percent.oltimeCons/nec/ionStonni’uterPollutionPieen/ioniius!20120 •Usegeotextilefabricstoincreasethestrengthofnewroadsorroadsundergoingreconstruction.•Encouragetheuseofalternate,pavedroutes,ifavailable.•Restrictuseofpavedroadwaysbytrackedvehiclesandheavytruckstopreventdamagetoroadsurfaceandbase.•Applychemicaldustsuppressantsusingtheadmixmethod,blendingtheproductwiththetopfewinchesofsurfacematerial.Suppressantsmayalsobeappliedassurfacetreatments.•Paveunpavedpermanentroadsandothertraffickedareas.•Usevacuumstreetsweepers.•Removemudandotherdirtpromptlysoitdoesnotdryandthenturnintodust.•Limitdust-causingworkonwindydays.•ContactyourlocalAirPollutionControlAuthorityforguidanceandtrainingonotherdustcontrolmeasures.CompliancewiththelocalAirPollutionControlAuthorityconstitutescompliancewiththisBMP.MaintenanceResprayareaasnecessarytokeepdusttoaminimum.StandardsBMPCISO:MaterialsonHandPurposeKeepquantitiesoferosionpreventionandsedimentcontrolmaterialsontheprojectsiteatalltimestobeusedforregularmaintenanceandemergencysituationssuchasunexpectedheavysummerrains.Havingthesematerialson-sitereducesthetimeneededtoimplementBMPswheninspectionsindicatethatexistingBMPsarenotmeetingtheConstructionSWPPPrequirements.Inaddition,contractorscansavemoneybybuyingsomematerialsinbulkandstoringthemattheirofficeoryard.C’o,,ditio,,sofUse•Constructionprojectsofanysizeortypecanbenefitfromhavingmaterialsonhand.Asmallcommercialdevelopmentprojectcouldhavearollofplasticandsomegravelavailableforimmediateprotectionofbaresoilandtemporarybermconstruction.Alargeearthworkproject,suchashighwayconstruction,mighthaveseveraltonsofstraw,severalrollsofplastic,flexiblepipe,sandbags,geotextilefabricandsteel“T”posts.•Materialsarestockpiledandreadilyavailablebeforeanysiteclearing,grubbing,orearthworkbegins.Alargecontractorordevelopercouldkeepastockpileofmaterialsthatareavailableforuseonseveralprojects.•Tfstoragespaceattheprojectsiteisatapremium,thecontractorcouldmaintainthematerialsattheirofficeoryard.Theofficeoryardmustbelessthananhourfromtheprojectsite.ohi;neConstructionStornni’atcrPollutionPreentioniiust2012I DesignandDependingonprojecttype,size,complexity,andlength,materialsandInstallationquantitieswillvary.AgoodminimumlistofitemsthatwillcoverSpecjficationsnumeroussituationsincludes:MaterialClearPlastic,6milDrainpipe,6or8inchdiameterSand b a g s ,filled___ _ ___ ___ ___ _ ___ __StrawBalesformulching,QuarrySpallsWashedGravelGeotextileFabricCatchBasinInsertsSteel‘7”PostsSiltfencematerialStrawWattlesMaintenance•Allmaterialswiththeexceptionofthequarryspalls,steel“I”posts,Standardsandgravelshouldbekeptcoveredandoutofbothsunandrain.•Re-stockmaterialsusedasneeded.BMPCISI:ConcreteHandlingPurposeConcreteworkcangenerateprocesswaterandslurrythatcontainfineparticlesandhighpH,bothofwhichcanviolatewaterqualitystandardsinthereceivingwater.ConcretespillageorconcretedischargetosurfacewatersoftheStateisprohibited.UsethisBMPtominimizeandeliminateconcrete,concreteprocesswater,andconcreteslurryfromenteringwatersofthestate.ConditionsofUseAnytimeconcreteisused,utilizethesemanagementpractices.Concreteconstructionprojectsinclude,butarenotlimitedto,thefollowing:•Curbs•Sidewalks•Roads•Bridges•Foundations•Floors•RunwaysDesignand•Washoutconcretetruckchutes,pumps,andinternalsintoformedInstallationareasonly.AssurethatwashoutofconcretetrucksisperformedoffchimeConstructionStonuwaterPollutionPieentioniius!20)22 Specjficationssiteorindesignatedconcretewashoutareas.Donotwashoutconcretetrucksontotheground,orintostormdrains,openditches,streets,orstreams.RefertoBMPC154forinformationonconcretewashoutareas.•Returnunusedconcreteremaininginthetruckandpumptotheoriginatingbatchplantforrecycling.Donotdumpexcessconcreteonsite,exceptindesignatedconcretewashoutareas.•Washoffhandtoolsincluding,butnotlimitedto,screeds,shovels,rakes,floats,andtrowelsintoformedareasonly.•Washequipmentdifficulttomove,suchasconcretepayersinareasthatdonotdirectlydraintonaturalorconstructedstormwaterconveyances.•Donotallowwashdownfromareas,suchasconcreteaggregatedriveways,todraindirectlytonaturalorconstructedstormwaterconveyances.•Containwashwaterandleftoverproductinalinedcontainerwhennoformedareasareavailable,.Disposeofcontainedconcreteinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.•Alwaysuseformsorsolidbarriersforconcretepours,suchaspilings,within15-feetofsurfacewaters.•RefertoBMPsC252andC253forpHadjustmentrequirements.•RefertotheConstructionStormwaterGeneralPermitforpHmonitoringrequirementsiftheprojectinvolvesoneofthefollowingactivities:•Significantconcretework(greaterthan1,000cubicyardspouredconcreteorrecycledconcreteusedoverthelifeofaproject).•Theuseofengineeredsoilsamendedwith(butnotlimitedto)Portlandcement-treatedbase,cementkilndustorflyash.•Dischargingstormwatertosegmentsofwaterbodiesonthe303(d)list(Category5)forhighpH.MaintenanceCheckcontainersforholesinthelinerdailyduringconcretepoursandStandardsrepairthesameday.obtineConstructionStornni’aterPollullo,,Pieentionuus!2012 BMPC152:SawcuttingandSurfacingPollutionPreventionPurposeSawcuttingandsurfacingoperationsgenerateslurryandprocesswaterthatcontainsfineparticlesandhighpH(concretecutting),bothofwhichcanviolatethewaterqualitystandardsinthereceivingwater.ConcretespillageorconcretedischargetosurfacewatersoftheStateisprohibited.UsethisBMPtominimizeandeliminateprocesswaterandslurrycreatedthroughsawcuttingorsurfacingfromenteringwatersoftheSlate.C’onditio,zsofUseUtilizethesemanagementpracticesanytimesawcuttingorsurfacingoperationstakeplace.Sawcuttingandsurfacingoperationsinclude,butarenotlimitedto,(liefollowing:•Sawing•Coring•Grinding•Roughening•Hydro-demolition•BridgeandroadsurfacingDesignand•Vacuumslurryandcuttingsduringcuttingandsurfacingoperations.Installation•SlurryandcuttingsshallnotremainonpermanentconcreteorasphaltSpec(flcationspavementovernight.•Slurryandcuttingsshallnotdraintoanynaturalorconstructeddrainageconveyanceincludingstornnvatersystems.Thismayrequiretemporarilyblockingcatchbasins.•Disposeofcollectedslurryandcuttingsinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.•Donotallowprocesswatergeneratedduringhydro-demohition,surfacerougheningorsimilaroperationstodraintoanynaturalorconstructeddrainageconveyanceincludingstormwatersystems.Disposeprocesswaterinamannerthatdoesnotviolategroundwaterorsurfacewaterqualitystandards.•Handleanddisposecleaningwastematerialanddemolitiondebrisinamannerthatdoesnotcausecontaminationofwater.Disposeofsweepingmaterialfromapick-upsweeperatanappropriatedisposalsite.Mainte,,a,,ceContinuallymonitoroperationstodeterminewhetherslurry,cuttings,orStandardsprocesswatercouldenterwatersofthestate.Ifinspectionsshowthataviolationofwaterquali’standardscouldoccur,stopoperationsandimmediatelyimplementpreventivemeasuressuchasberms,barriers,secondarycontainment,andvacuumtrucks.ohmicCons/rue/jot;S/ornni’a/erPollulionPieen/ionitus!2012 BMPC153:MaterialDelivery,StorageandContainmentPurposePrevent,reduce,oreliminatethedischargeofpollutantstothestormwatersystemorwatercoursesfrommaterialdeliveryandstorage.Minimizethestorageofhazardousmaterialson-site,storematerialsinadesignatedarea,andinstallsecondarycontainment.conditionsofUseTrodrarIaforaaonrionidIrandoraoffooinana•Petroleumproductssuchasfuel,oilandgrease•Soilstabilizersandbinders(e.g.Polyacrylamide)•Fertilizers,pesticidesandherbicides•Detergents•Asphaltandconcretecompounds•1-lazardouschemicalssuchasacids,lime,adhesives,paints,solventsandcuringcompounds•AnyothermaterialthatmaybedetrimentalifreleasedtotheenvironmentDesignandTfooinodanomiIiiI,,stallatwn•Temporarystorageareashouldbelocatedawayfromvehiculartraffic,Specificationsneartheconstructionentrance(s),andawayfromwaterwaysorstormdrains.•MaterialSafetyDataSheets(MSDS)shouldbesuppliedforallmaterialsstored.Chemicalsshouldbekeptintheiroriginallabeledcontainers.•Hazardousmaterialstorageon-siteshouldbeminimized.•Hazardousmaterialsshouldbehandledasinfrequentlyaspossible.•Duringthewetweatherseason(Oct1—April30).considerstoringmaterialsinacoveredarea.•Materialsshouldbestoredinsecondarycontainments,suchasearthendike,horsetrough,orevenachildren’swadingpooifornon-reactivematerialssuchasdetergents,oil,grease,andpaints.Smallamountsofmaterialmaybesecondarilycontainedin“busboy”traysorconcretemixingtrays.•Donotstorechemicals,drums,orbaggedmaterialsdirectlyontheground.Placetheseitemsonapalletand,whenpossible,andwithinsecondary’containment.•Ifdrumsmustbekeptuncovered,storethemataslightangletoreducepondingofrainwateronthelidstoreducecorrosion.Domedplasticcoversareinexpensiveandsnaptothetopofdrums,preventingwaterfromcollecting.ohuneConstructionStornnraterPollutionPreentionuus!2012 ManaSeraAraandSondarConamnPraILiquids.petroleumproducts,andsubstanceslistedin40CFRParts110,117,or302shallbestoredinapprovedcontainersanddrumsandshallnotbeoverfilled.Containersanddrumsshallbestoredintemporarysecondarycontainmentfacilities.•Temporarysecondarycontainmentfacilitiesshallprovideforaspillcontainmentvolumeabletocontain10%ofthetotalenclosedcontainervolumeofallcontainers,or110%ofthecapacityofthelargcstcontainerwithinitsboundary,whicheverisgrcatcr.•Secondarycontainmentfacilitiesshallbeimpervioustothematerialsstorcdthereinforaminimumcontacttimeof72hours.•Secondarycontainmentfacilitiesshallbemaintainedfreeofaccumulatedrainwaterandspills.Intheeventofspillsorleaks,accumulatedrainwaterandspillsshallbecollectedandplacedintodrums.Theseliquidsshallbehandledashazardouswasteunlesstestingdeterminesthemtobenon-hazardous.•Sufficientseparationshouldbeprovidedbetweenstoredcontainerstoallowforspillcleanupandemergencyresponseaccess.•Duringthewetweatherseason(Oct1—April30),eachsecondarycontainmentfacilityshallbecoveredduringnon-workingdays,priortoandduringrainevents.•Keepmaterialstorageareasclean,organizedandequippedwithanamplesupplyofappropriatespillclean-upmaterial(spillkit).•Thespillkitshouldinclude,ataminimuni:•1-WaterResistantNylonBag•3-OilAbsorbentSocks3”x4’•2-OilAbsorbentSocks3”x10’•12-OilAbsorbentPadsI7”xl9”•1-PairSplashResistantGoggles•3-PairNitrileGloves•10-DisposableBagswithTies•InstructionsohmicConstructionSto,mu’atc;PollutionPreentioniiust20)2 BMPCl54:ConcreteWashoutAreaPurposePreventorreducethedischargeofpollutantstostormwaterfromconcretewastebyconductingwashoutoff-site,orperformingon-sitewashoutinadesignatedareatopreventpollutantsfromenteringsurfacewatersorgroundwater.(‘auditionsofUseConcretewashoutareabestmanagementpracticesareimplementedonconstructionprojectswhere:•Concreteisusedasaconstructionmaterial•Itisnotpossibletodisposeofallconcretewastewaterandwashoutoff-site(readymixplant,etc.).•Concretetrucks,pumpers,orotherconcretecoatedequipmentarewashedon-site.•Note:Iflessthan10concretetrucksorpumpersneedtobewashedouton-site,thewashwatermaybedisposedofinaformedareaawaitingconcreteoranuplanddisposalsitewhereitwillnotcontaminatesurfaceorgroundwater.Theuplanddisposalsiteshallbeatleast50feetfromsensitiveareassuchasstormdrains,openditches,orwaterbodies,includingwetlands.DesignandInaionInstallationThefollowingstepswillhelpreducestormwaterpollutionfromconcreteSpecificationswastes:•Performwashoutofconcretetrucksoff-siteorindesignatedconcretewashoutareasonly.•Donotwashoutconcretetrucksontotheground,orintostormdrains,openditches,streets,orstreams.•Donotallowexcessconcretetobedumpedon-site,exceptindesignatedconcretewashoutareas.•Concretewashoutareasmaybeprefabricatedconcretewashoutcontainers,orself-insEalledstructures(above-gradeorbelow-grade).•Prefabricatedcontaincrsarcmostresistanttodamagcandprotectagainstspillsandleaks.Companiesmayofferdeliveryserviceandprovideregularmaintenanceanddisposalofsolidandliquidwaste.•Ifself-installedconcretewashoutareasareused,below-gradestructuresarepreferredoverabove-gradestructuresbecausetheyarelesspronetospillsandleaks.•Self-installedabove-gradestructuresshouldonlybeusedifexcavationisnotpracticaLobtineConstructionStor,uni’cwerPothilionPreen/ioniius!2012 Edaion•DiscusstheconcretemanagementtechniquesdescribedinthisBMPwiththeready-mixconcretesupplierbeforeanydeliveriesaremade.•EducateemployeesandsubcontractorsontheconcretewastemanagementtechniquesdescribedinthisBMP.•Arrangeforcontractor’ssuperintendentorCertifiedErosionandSedimentControlLead(CESCL)tooverseeandenforceconcretewastemanagementprocedures.•Asignshouldbeinstalledadjacenttoeachtemporaryconcretewashoutfacilitytoinformconcreteequipmentoperatorstoutilizetheproperfacilities.ConraIncorporaterequirementsforconcretewastemanagementintoconcretesupplierandsubcontractoragreements.LoaionandPan•Locatewashoutareaatleast50feetfromsensitiveareassuchasstormdrains,openditches,orwaterbodies,includingwetlands.•Allowconvenientaccessforconcretetrucks,preferablyneartheareawheretheconcreteisbeingpoured.•Iftrucksneedtoleaveapavedareatoaccesswashout,preventtrack-outwithapadofrockorquarryspalls(seeBMPC105).Theseareasshouldbefarenoughawayfromotherconstructiontraffictoreducethelikelihoodofaccidentaldamageandspills.•Thenumberoffacilitiesyouinstallshoulddependontheexpecteddemandforstoragecapacity.•Onlargesiteswithextensiveconcretework,washoutsshouldbeplacedinmultiplelocationsforeaseofusebyconcretetruckdrivers.On-iTorarConrWaoFail,TraniTrWaoProdr•Temporaryconcrctcwashoutfacilitiesshallbelocatedaminimumof50ftfromsensitiveareasincludingstormdraininlets,opendrainagefacilities,andwatercourscs.SeeFigures4.1.7and4.1.8.•Concretewashoutfacilitiesshallbeconstructedandmaintainedinsufficientquantityandsizetocontainallliquidandconcretewastegcneratcdbywashoutoperations.•Approximately7gallonsofwashwaterareusedtowashonetruckchute.•Approximately50gallonsareusedtowashoutthehopperofaconcretepumptruck.obtineCenisiritetionS/ou,;ni’aterPollutionfireen/ioniius!2012 •Washoutofconcretetrucksshallbeperformedindesignatedareasonly.•Concretewashoutfromconcretepumperbinscanbewashedintoconcretepumpertrucksanddischargedintodesignatedwashoutareaorproperlydisposedofoff-site.•Onceconcretewastesarewashedintothedesignatedareaandallowedtoharden.theconcreteshouldbebrokenup,removed,anddisposedofperapplicablesolidwasteregulations.Disposeofhardenedconcreteonaregularbasis.•TemporaryAbove-GradeConcreteWashoutFacility•Temporaryconcretewashoutfacility(typeabovegrade)shouldbeconstructedasshownonthedetailsbelow,witharecommendedminimumlengthandminimumwidthof10ft,butwithsufficientquantityandvolumetocontainallliquidandconcretewastegeneratedbywashoutoperations.•Plasticliningmaterialshouldbeaminimumof10milpolyethylenesheetingandshouldbefreeofholes,tears,orotherdefectsthatcompromisetheimpermeabilityofthematerial.•TemporaryBelow-GradeConcreteWashoutFacility•Temporaryconcretewashoutfacilities(typebelowgrade)shouldbeconstructedasshownonthedetailsbelow,witharecommendedminimumlengthandminimumwidthof10ft.Thequantityandvolumeshouldbesufficienttocontainallliquidandconcretewastegeneratedbywashoutoperations.•Lathandflaggingshouldbecommercialtype.•Plasticliningmaterialshallbeaminimumof10milpolyethylenesheetingandshouldbefreeofholes,tears,orotherdefectsthatcompromisetheimpermeabilityofthematerial.•Linerseamsshallbeinstalledinaccordancewithmanufacturers’recommendations.•Soilbaseshallbepreparedfreeofrocksorotherdebristhatmaycausetearsorholesintheplasticliningmaterial.MaintenanceInionandMainnanStandards•InspectandverifythatconcretewashoutBMPsareinplacepriortothecommencementofconcretework.•Durinaperiodsofconcretework.inspectdailytoverifycontinuedperformance.•Checkoverallconditionandperformance.•Checkremainingcapacity(%full).olumeConstructionStor,nwaterPollutionPieentionuus!2012 •Ifusingself-installedwashoutfacilities.veri&plasticlinersareintactandsidewallsarenotdamaged.•Ifusingprefabricatedcontainers,checkforleaks.•Washoutfacilitiesshallbemaintainedtoprovideadequateholdingcapacitywithaminimumfreeboardof12inches.•Washoutfacilitiesmustbecleaned,ornewfacilitiesmustbeconstructedandreadyforuseoncethewashoutis75%hill.•Ifthewashoutisnearingcapacity,vacuumanddisposeofthewastematerialinanapprovedmanner.•Donotdischargeliquidorslurrytowaterways,stormdrainsordirectlyontoground.•Donotusesanitary’sewerwithoutlocalapproval.•Placeasecure,non-collapsing,non-watercollectingcoverovertheconcretewashoutfacility’priortopredictedwetweathertopreventaccumulationandoverflowofprecipitation.•Removeanddisposeofhardenedconcreteandreturnthestructuretoafunctionalcondition.Concretemaybereusedon-siteorhauledawayfordisposalorrecycling.•Whenyouremovematerialsfromtheself-installedconcretewashout,buildanewstructure;or,ifthepreviousstructureisstillintact,inspectforsignsofweakeningordamage,andmakeanynecessaryrepairs.Re-linethestructurewithnewplasticaftereachcleaning.RoaofTorarConrWaoFaiii•Whentemporaryconcretewashoutfacilitiesarenolongerrequiredforthework.thehardenedconcrete,slurriesandliquidsshallberemovedandproperlydisposedof.•Materialsusedtoconstructtemporaryconcretewashoutfacilitiesshallberemovedfromthesiteoftheworkanddisposedoforrecycled.•Holes,depressionsorothergrounddisturbancecausedbytheremovalofthctcmporaryconcrctcwashoutfaciliticsshallbebackfillcd,repaired,andstabilizedtopreventerosion.oluineCons/rite/ionS/ormii’aterPollutionPreentionitus!20120 Figure4.1.7a—ConcreteWashoutAreaohnneConstructionSlornni’aterPollutionPreenilonuus!2012I10riftAStCIn,lATHMOrNGONJSIDESNnA-KNUT10SCAII10r,ptThD___UNOT10SCALEMIIIIUUU—LqO0DWAIlSSECUREDF*SIENEOLJAOUPAOENIIREPEPIMEICHN._WITHTWOSIMS‘STWO.5FACgO2.12POUCH—.rI000FRMAEVAS:/IDmITHIJICHNINCI.ACTUALLAYCHJTDCTtRUI%Cp...ThEflt._D,2.ThECO.CRCTCWASHOUT5GW(551PACEb)$nAttOrn.SIuIloMThA.ToInOrfl!IWPoTmLONCRnrWASHOUTrAcIur,HOTTOSCAUTnflADQVCGRACrWIThW000FW{KS atE5JA,ILS(2PRBALE)s00STARES(2ERBALE)•1vmics/SNCaWIRE7/-7Y61PtASlICUMNO///PeAT?,tLLAWRLt/(OrIOML)n.-r(40110SCALEPLYA000-I200ow’.€SflnnPAJ,’TEDwHrTt-4—----—I.n.n!UU(59mm19mmr21.7.)COI4CRflWASHOUTSIGNDtTML(OREOJVAW(1)$HHST_200mmSTAPhDETAILI.ACIUALLAYOUTOCTETISArNED(NTHEFiCW,2.THEcONCRETEWASkCWLION(SEEnO.4—15)SKALLBEINSTALLEDWITHINIDmOFThE1ZUP0P.YCONCRETEWASHOUTFAC,LmY.r.LImn/rcA-I.OWISACftI’2Figure4.1.7b—ConcreteWashoutAreaFigure4.1.8—PrefabricatedConcreteWashoutContainerwlRampohinwConstructionS1orn,i’aterPollutionPreeu/ioniius!201270mAF.ASIICU0f2-NITTOSCALETYPEASOVECR4DrWITHSTRAWBAILS BMPC160:CertifiedErosionandSedimentControlLeadPurposeTheprojectproponentdesignatesatleastonepersonastheresponsiblerepresentativeinchargeoferosionandsedimentcontrol(ESC),andwaterqualityprotection.ThedesignatedpersonshallbetheCertifiedErosionandSedimentControlLead(CESCL)whoisresponsibleforensuringcompliancewithalllocal,state,andfederalerosionandsedimentcontrolandwaterqualityrequirements.ConditionsofUseACESCLshallbemadeavailableonprojectsoneacreorlargerthatdischargestormwatertosurfacewatersofthestate.SiteslessthanoneacremayhaveapersonwithoutCESCLcertificationconductinspections;samplingisnotrequiredonsitesthatdisturblessthananacre.•TheCESCLshall:•HaveacurrentcertificateprovingattendanceinanerosionandsedimentcontroltrainingcoursethatmeetstheminimumESCtrainingandcertificationrequirementsestablishedbyEcology(seedetailsbelow).EcologywillmaintainalistofESCtrainingandcertificationprovidersat:http://www.ecy.wa.aov/proQrams/wg/stormwater/cescl.htmlOR•BeaCertifiedProfessionalinErosionandSedimentControl(CPESC);foradditionalinformationgoto:nvw.cpesc.netSpecjfications•Certificationshallremainvalidforthreeyears.•TheCESCLshallhaveauthoritytoactonbehalfofthecontractorordeveloperandshallbeavailable,oron-call,24hoursperdaythroughouttheperiodofconstruction.•TheConstructionSWPPPshallincludethename,telephonenumber,faxnumber,andaddressofthedesignatedCESCL.•ACESCLmayprovideinspectionandcomplianceservicesformultipleconstructionprojectsinthesamegeographicregion.DutiesandresponsibilitiesofthcCESCLshallinclude,butarcnotlimitedtothefollowing:•MaintainingpermitfileonsiteatalltimeswhichincludestheConstructionSWPPPandanyassociatedpermitsandplans.•DirectingBMPinstallation,inspection,maintenance,modification,andremoval.ohimeConstructionStonnitoterPollutionPreeu/ionuus!2012 •UpdatingallprojectdrawingsandtheConstructionSWPPPwithchangesmade.•CompletinganysamplingrequirementsincludingreportingresultsusingWebDMR.•Keepingdailylogs,andinspectionreports.Inspectionreportsshouldinclude:•Inspectiondate/time.•Weatherinformation;generalconditionsduringinspectionandapproximateamountofprecipitationsincethelastinspection.•AsummaryorlistofallBMPsimplemented,includingobservationsofallerosion/sedimentcontrolstructuresorpractices.Thefollowingshallbenoted:1.LocationsofBMPsinspected.2.LocationsofBMPsthatneedmaintenance.3.LocationsofBMPsthatfailedtooperateasdesignedorintended.4.LocationsofwhereadditionalordifferentBMPsarerequired.•Visualmonitoringresults,includingadescriptionofdischargedstorrnwater.Thepresenceofsuspendedsediment,turbidwater,discoloration,andoilsheenshallbenoted,asapplicable.•Anywaterqualitymonitoringperformedduringinspection.•Generalcommentsandnotes,includingabriefdescriptionofanyBMPrepairs,maintenanceorinstallationsmadeasaresultoftheinspection.•Facilitate,participatein,andtakecorrectiveactionsresultingfrominspectionsperformedbyoutsideagenciesortheowner.BMPC162:SchedulingPurposeSequencingaconstmctionprojectreducestheamountanddurationofsoilexposedtoerosionbywind,rain,runoff,andvehicletracking.conditionsofUseTheconstructionsequencescheduleisanorderlylistingofallmajorland-disturbingactivitiestogetherwiththenecessaryerosionandsedimentationcontrolmeasuresplannedfortheproject.Thistypeofscheduleguidesthecontractoronworktobedonebeforeotherworkisstartedsothatseriouserosionandsedimentationproblemscanbeavoided.Followingaspecifiedworkschcdulethatcoordinatesthetimingofland-disturbingactivitiesandtheinstallationofcontrolmeasuresisperhapsthemostcost-effectivewayofcontrollingerosionduringconstruction.TheremovalofsurfacegroundcoverleavesasitevulnerabletoacceleratedolunieConstrudilonS/onnii’aterPollutionPit’en/ionuus!2012 erosion.Constructionproceduresthatlimitlandclearingprovidetimelyinstallationoferosionandsedimentationcontrols,andrestoreprotectivecoverquicklycansignificantlyreducetheerosionpotentialofasite.Design.Minimizeconstructionduringrainyperiods.Coissiderations.Scheduleprojectstodisturbonlysmallportionsofthesiteatanyonetime.Completegradingassoonaspossible.Immediatelystabilizethedisturbedportionbeforegradingthenextportion.Practicestagedseedinginordertorevegetatecutandfillslopesastheworkprogresses.ohinwConstructionS/ornni’aterPothilionPieen/ionxius!2012 BMPC200:InterceptorDikeandSwalePurposeProvidearidgeofcompactedsoil,oraridgewithanupslopeswale,atthetoporbaseofadisturbedslopeoralongtheperimeterofadisturbedconstructionareatoconveystormwater.Usethedikeandlorswaletointercepttherunofffromunprotectedareasanddirectittoareaswhereerosioncanbecontrolled.Thiscanpreventstormrunofffromenteringtheworkareaorsediment-ladenrunofffromleavingtheconstructionsite.C’onditionsofUseWheretherunofffromanexposedsiteordisturbedslopemustbeconveyedtoanerosioncontrolfacilitywhichcansafelyconveythestormwater.•Locateupslopeofaconstructionsitetopreventrunofffrontenteringdisturbedarea.•Whenplacedhorizontallyacrossadisturbedslope,itreducestheamountandvelocity’ofrunoffflowingdowntheslope.•Locatedownslopetocollectrunofffromadisturbedareaanddirectwatertoasedimentbasin.Designand•Dikeand/orswaleandchannelmustbestabilizedwithtemporaryorInstallatio,,permanentvegetationorotherchannelprotectionduringconstruction.Specjfications•Channelrequiresapositivegradefordrainage;steepergradesrequirechannelprotectionandcheckdams.•Reviewconstructionforareaswhereovertoppingmayoccur.•Canbeusedattopofnewfillbeforevegetationisestablished.•Maybeusedasapermanentdiversionchanneltocarrytherunoff.•Sub-basintributaryareashouldbeoneacreorless.•Designcapacityforthepeakflowfroma10-year,24-hourstorm,assumingaTypeIArainfalldistribution,fortemporary’facilities.Alternatively,use1.6timesthe10-year,1-hourflowindicatedbyanapprovedcontinuousrunoffmodel.Forfacilitiesthatwillalsoserveonapermanentbasis,consultthelocalgovernment’sdrainagerequirements.Inrordishallmeetthefollowingcriteria:TopWidth2feetminimum.Height1.5feetminimumonberm.SideSlope2H:IVorflatter.GradeDependsontopography,however,dikesystemminimumis0.5%,andmaximumis1%.CompactionMinimumof90percentASTMD698standardproctor.olitmeConstructionS!onnii’aterPollutionPieentionuus!2012 HorizontalSpacingofInterceptorDikes:AraSoSoPriiFoaEn20H:IVorless3-5%300feet(10to20)F1:lV5-10%200feet(4to10)1+IV10-25%100feet(2to4)H:IV25-50%50feetStabilizationdependsonvelocityandreachSlopes<5%Seedandmulchappliedwithin5daysofdikeconstruction(seeBMPC121.Mulching).Slopes5-40%Dependentonrunoffvelocitiesanddikematerials.Stabilizationshouldbedoneimmediatelyusingeithersodorripraporothermeasurestoavoiderosion.•Theupslopesideofthedikeshallprovidepositivedrainagetothedikeoutlet.Noerosionshalloccurattheoutlet.Provideenergydissipationmeasuresasnecessary.Sediment-ladenrunoffmustbereleasedthroughasedimenttrappingfacility.•Minimizeconstructiontrafficovertemporarydikes.Usetemporarycrossculvertsforchannelcrossing.Inrorashallmeetthefollowingcriteria:BottomWidth2feetminimum;thecross-sectionbottomshallbelevel.DepthI-footminimum.SideSlope2H:IVorflatter.GradeMaximum5percent,withpositivedrainagetoasuitableoutlet(suchasasedimentpond).StabilizationSeedasperBMPC120,cmoraranPennanentSeeinorPC202,Cmmcl12inchesthickriprappressedintothebankandextendingatleast8inchesverticalfromthebottom.•Inspectdiversiondikesandinterceptorswalesonceaweekandaftereveryrainfall.Immediatelyremovesedimentfromtheflowarea.•Damagecausedbyconstructiontrafficorotheractivitymustberepairedbeforetheendofeachworkingday.Checkoutletsandmaketimelyrepairsasneededtoavoidgullyformation.Whentheareabelowthetemporarydiversiondikeispermanentlystabilized,removethedikeandfillandstabilizethechanneltoblendwiththenaturalsurface.ohuneConstructionStonmi’a!erPollutionPieentionuus!2012 BMPC201:Grass-LinedChannelsPurposeToprovideachannelwithavegetativeliningforconveyanceofrunoff.SeeFhure4.2.1fortypicalgrass-linedchannels.ConditionsofUseThispracticeappliestoconstructionsiteswhereconcentratedrunoffneedstobecontainedtopreventerosionorflooding.•Whenavegetativeliningcanprovidesufficientstabilityforthechannelcrosssectionandatlowervelocitiesofwater(normallydependentongrade).Thismeansthatthechannelslopesaregenerallylessthan5percentandspaceisavailableforarelativelylargecrosssection.•Typicalusesincluderoadsideditches,channelsatpropertyboundaries,outletsfordiversions,andotherchannelsanddrainageditchesinlowareas.•Channelsthatwillbevegetatedshouldbeinstalledbeforemajorearthworkandhydroseededwithabondedfibermatrix(BFM).Thevegetationshouldbewellestablished(i.e.,75percentcover)beforewaterisallovedtoflowintheditch.Withchannelsthatwillhavehighflows,erosioncontrolblanketsshouldbeinstalledoverthehydroseed.Ifvegetationcannotbeestablishedfromseedbeforewaterisallowedintheditch,sodshouldbeinstalledinthebottomoftheditchinlieuofhydromulchandblankets.DesignandLocatethechannelwhereitcanconformtothetopographyandotherInstallationfeaturessuchasroads.Specfflcations•Locatethemtousenaturaldrainagesystemstothegreatestextentpossible.•Avoidsharpchangesinalignmentorbendsandchangesingrade.•Donotreshapethelandscapetofitthedrainagechannel.•Themaximumdesignvelocityshallbebasedonsoilconditions,typeofvcgctation,andmcthodofrcvegctation,butatnotimesshaLlvelocityexceed5feet/second.Thechannelshallnotbeovertoppedbythepeakrunofffroma10-year,24-hourstorm,assumingaTypeIArainfalldistribution.Alternatively,use1.6timesthe10-year,1-hourflowindicatedbyanapprovedcontinuousrunoffmodeltodetermineaflowratewhichthechannelmustcontain.•Wherethegrass-linedchannelwiLLalsofunctionasapermanenistormwaterconveyancefacility,consultthedrainageconveyancerequirementsofthelocalgovernmentwithjurisdiction.olzi;wConstructionS!onnii’aterPollutionPieen/ionxius!2012 •Anestablishedgrassorvegetatedliningisrequiredbeforethechannelcanbeusedtoconveystormwater,unlessstabilizedwithnetsorblankets.•Ifdesignvelocityofachanneltobevegetatedbyseedingexceeds2fUsec,atemporarychannellinerisrequired.Geotextileorspecialmulchprotectionsuchasfiberglassrovingorstrawandnettingprovidesstabilityuntilthevegetationisfullyestablished.SeeFicure4.2.2.•Checkdamsshallberemovedwhenthegrasshasmaturedsufficientlytoprotecttheditchorswaleunlesstheslopeoftheswaleisgreaterthan4percent.Theareabeneaththecheckdamsshallbeseededandmulchedimmediatelyafterdamremoval.•Ifvegetationisestablishedbysodding,thepermissiblevelocityforestablishedvegetationmaybeusedandnotemporarylinerisneeded.•Donotsubjectgrass-linedchanneltosedimentationfromdisturbedareas.Usesediment-trappingBMPsupstreamofthechannel.•V-shapedgrasschannelsgenerallyapplywherethequantityofwaterissmall,suchasinshortreachesalongroadsides.TheV-shapedcrosssectionisleastdesirablebecauseitisdifficulttostabilizethebottomwherevelocitiesmaybehigh.•Trapezoidalgrasschannelsareusedwhererunoffvolumesarelargeandslopeislowsothatvelocitiesarenonerosivetovegetatedlinings.(Note:itisdifficulttoconstructsmallparabolicshapedchannels.)•Subsurfacedrainage,orriprapchannelbottoms,maybenecessaryonsitesthataresubjecttoprolongedwetconditionsduetolongdurationflowsorahighwatertable.•Provideoutletprotectionatculvertendsandatchannelintersections.•Grasschannels,ataminimum,shouldcarrypeakrunofffortemporaryconstructiondrainagefacilitiesfromthe10-year,24-hourstormwithouteroding.Wherefloodhazardexists,increasethecapacityaccordingtothepotentialdamage.•Grassedchannelsideslopesgenerallyareconstructed3H:IVorflattertoaidintheestablishmentofvegetationandformaintenance.•Constructchannelsaminimumof0.2footlargeraroundtheperipherytoallowforsoilbulkingduringseedbedpreparationsandsodbuildup.MaintenanceDuringtheestablishmentperiod,checkgrass-linedchannelsaftereverySta,zdardsrainfall.•Aftergrassisestablished,periodicallycheckthechannel;checkitafterevery’heavy’rainfallevent.Immediatelymakerepairs.•Itisparticularlyimportanttocheckthechanneloutletandallroadcrossingsforbankstabilityandevidenceofpipingorscourholes.ohmicConstructionStornni’aterPollutionPreen/ioniius!20120 Removeallsignificantsedimentaccumulationstomaintainthedesignedcarryingcapacity.Keepthegrassinahealthy,vigorousconditionatalltimes,sinceitistheprimaryerosionprotectionforthechannel.TypicalV-ShapedChannelCross-sectionGrass-LinedChannelCross-SectionCl50.225mm)KeyInFabricWithChannelLinerWiIhRockChterlotBaseFlowTypicalTrapezoidalChannelCross-SectionDesignDepth‘ercutchannel2”150mm)toIIowhulkingduringscedbedpreparationandgrowthofveqetalionFillerFatyiic1L/%•StiFigure4.2.1—TypicalGrass-LinedChannelsohmicCons!rudilonS!or;mi’a!erPollulionPieeu/iouitus!2012FilterFabricTypicalParabolicRocRCenter(150-225mm1KeyinFabricFilterFabricWarnRockCenterForBaseFlowI Overlap6(150mm)minimumflf/ThI./-r(m)tyct’-//TPICALINSTALLATIONWITHEROSIONCONTROLBMNKETSORTRFREINFORCEMENTMATSLSLtaItNOTES:IntermittentCheckSlotLongitudinalAnchorTrenchtoprotecLseedandsoiluntilvegetationbecomesestablished.2Grass-linedchannelswithdesignvelocitiesexceeding6fl/sec(2m/sec)shouldincludeturfreinforcementmats.Figure4.2.2—TemporaryChannelLinersEcavateCtiann&toDeigiiGradeapdCrossSectionIoERCTCHANNEL2(50mm)TOALLOWBLKING0RINGSEEDBEDPREPARATIONLonaitudinalanchorTrenchShingle-lapsplicedendsorbeginnewrollinanintermittentcheckslot4Preparesoilandapplyseedbeforeinstallingblankets,matsorothertemporarychannellinersystem44(14-‘A’IbesigneIocitiesexceeding2ft/sec(O.5m!sec)requiretemporaryblanLets,matsorsimilarlinersohuneConstrue/ionSlornnt’aterPollutionPieen/ionuus!2012 BMPC202:ChannelLiningPurposeToprotectchannelsbyprovidingachannellinerusingeitherblanketsorriprap.ConditionsofWhennaturalsoilsorvegetatedstabilizedsoilsinachannelarenotadequatiUsetopreventchannelerosion.•Whenapermanentditchorpipesystemistobeinstalledandatemporarymeasureisneeded.•Inalmostallcases.syntheticandorganiccoconutblanketsaremoreeffectivethanriprapforprotectingchannelsfromerosion.Blanketscanbeusedwithandwithoutvegetation.Blanketedchannelscanbedesignedtohandleanyexpectedflowandlongevityrequirement.Somesyntheticblanketshaveapredictedlifespanof50yearsormore,eveninsunlight.•Otherreasonswhyblanketsarebetterthanrockincludetheavailabilityofblanketsoverrock.Inmanyareasofthestate,rockisnoteasilyobtainableorisveryexpensivetohaultoasite.Blanketscanbedeliveredanywhere.Rockrequirestheuseofdumptruckstohaulandheavyequipmenttoplace.Blanketsusuallyonlyrequirelaborerswithhandtools,andsometimesabackhoe.•TheFederalHighwayAdministrationrecommendsnotusingflexiblelinerswhenevertheslopeexceeds10percentortheshearstressexceeds8lbs/ft2.DesignandSeeBMPC122forinformationonblankets.Installation.....Sincenprapisusedwhereerosionpotentialishigh,constructionmustbeSpecificationssequencedsothattheriprapisputinplacewiththeminimumpossibledelay.•Disturbanceofareaswhereriprapistobeplacedshouldbeundertakenonlywhenfinalpreparationandplacementoftheriprapcanfollowimmediatelybehindtheinitialdisturbance.\Vhereriprapisusedforoutletprotection,theriprapshouldbeplacedbeforeorinconjunctionwiththeconstructionofthepipeorchannelsothatitisinplacewhenthepipeorchannelbeginstooperate.•Thedesigner,afterdeterminingtheriprapsizethatwillbestableundertheflowconditions,shallconsiderthatsizetobeaminimumsizeandthen,basedonriprapgradationsactuallyavailableinthearea,selectthesizeorsizesthatequalorexceedtheminimumsize.Thepossibilityofdrainagestructuredamagebychildrenshallbeconsideredinselectingariprapsize,especiallyifthereisnearbywateroragullyinwhichtotossthestones.•Stoneforriprapshallconsistoffieldstoneorquarrystoneofapproximatelyrectangularshape.ThestoneshallbehardandangularoluincConstructionStonnii’aterPollutionPrecut/oniius!20)2 andofsuchqualitythatitwillnotdisintegrateonexposuretowaterorweatheringanditshallbesuitableinallrespectsforthepurposeintended.Aliningofengineeringfilterfabric(geotextile)shallbeplacedbetweentheriprapandtheunderlyingsoilsurfacetopreventsoilmovementintoorthroughtheriprap.Thegeotextileshouldbekeyedinatthetopofthebank.Filterfabricshallnotbeusedonslopesgreaterthan1-1/2H:IVasslippagemayoccur.Itshouldbeusedinconjunctionwithalayerofcoarseaggregate(granularfilterblanket)whentheripraptobeplacedis12inchesandlarger.BMPC203:WaterBarsPurposeAsmallditchorridgeofmaterialisconstructeddiagonallyacrossaroadorright-of-waytodivertstormwaterrunofffromtheroadsurface,wheeltracks,orashallowroadditch.SeeFiaure4.2.3.Co,,ditionsofuseClearingright-of-wayandconstructionofaccessforpowerlines,pipelines,andothersimilarinstallationsoftenrequirelongnarrowright-of-waysoverslopingterrain.DisturbanceandcompactionpromotesgullyformationintheseclearedstripsbyincreasingthevolumeandvelocityofrunoffGullyformationmaybeespeciallysevereintiretracksandruts.Topreventgullying,runoffcanoftenbedivertedacrossthewidthoftheright-of-waytoundisturbedareasbyusingsmallpredesigneddiversions.•Givespecialconsiderationtoeachindividualoutletarea,aswellastothecumulativeeffectofaddeddiversions.Usegraveltostabilizethediversionwheresignificantvehiculartrafficisanticipated.DesignaudITeight:8-inchminimummeasuredfromthechannelbottomtotheridgetop.Installation•Sideslopeofchannel:2H:IVmaximum:3H:IVorflatterwhenSpecsflcatwizs..-vehicleswillcross.•Basewidthofridge:6-inchminimum.•Locatethemtousenaturaldrainagesystemsandtodischargeintowellvegetatedstableareas.•GuidelineforSpacing:SoSain(f)<51255-1010010-207520-3550>35UscrocklinedditchohiuwConstructionStornnt’atcrPollutionPreentionUus!2012 •Gradeofwaterbarandangle:Selectanglethatresultsinditchslopelessthan2percent.•Installassoonastheclearingandgradingiscomplete.Reconstructwhenconstructioniscompleteonasectionwhenutilitiesarebeinginstalled.•Compacttheridgewheninstalled.•Stabilize,seedandmulchtheportionsthatarenotsubjecttotraffic.Graveltheareascrossedbyvehicles.MahitenancePeriodicallyinspectright-of-waydiversionsforwearandaftereveryheavyStandardsrainfallforerosiondamage.•Immediatelyremovesedimentfromtheflowareaandrepairthedike.•Checkoutletareasandmaketimelyrepairsasneeded.•Whenpermanentroaddrainageisestablishedandtheareaabovethetemporaryright-of-waydiversionispermanentlystabilized,removethedikesandfillthechanneltoblendwiththenaturalground,andappropriatelystabilizethedisturbedarea.DEEPWATERBARA24to30inchesB6toioteaSHALLOWWATERBARA8to12inchesB6to12fedFigure4.2.3—WaterBarolwneConstrue/iouS/ormiraftrPollutionPreentioniius!2012 BMPC204:PipeSlopeDrainsPurposeTouseapipetoconveystormwateranytimewaterneedstobedivertedawayfromoroverbaresoiltopreventgullies,channelerosion,andsaturationofslide-pronesoils.ConditionsofUsePipeslopedrainsshouldbeusedwhenatemporaryorpermanentstormwaterconveyanceisneededtomovethewaterdownasteepslopetoavoiderosion(Figure4.2.4).Onhighwayprojects,pipeslopedrainsshouldbeusedatbridgeendstocollectrunoffandpipeittothebaseofthefillslopesalongbridgeapproaches.Thesecanbedesignedintoaprojectandincludedasbiditems.Anotheruseonroadprojectsistocollectrunofffrompavementandpipeitawayfromsideslopes.Theseareusefulbecausethereisgenerallyatimelagbetweenhavingthefirstliftofasphaltinstalledandthecurbs,gutters,andpermanentdrainageinstalled.Usedinconjunctionwithsandbags,orothertemporarydiversiondevices,thesewillpreventmassiveamountsofsedimentfromleavingaproject.Watercanbecollected,channeledwithsandbags,TriangularSiltDikes,berms,orothermaterial,andpipedtotemporarysedimentponds.Pipeslopedrainscanbe:•Connectedtonewcatchbasinsandusedtemporarilyuntilallpermanentpipingisinstalled;•Usedtodrainwatercollectedfromaquifersexposedoncutslopesandtakeittothebaseoftheslope;•Usedtocollectcleanrunofffromplasticsheetinganddirectitawayfromexposedsoil;•Tnstalledinconjunctionwithsiltfencetodraincollectedwatertoacontrolledarea;•Usedtodivertsmallseasonalstreamsawayfromconstruction.Theyhavebeenusedsuccessfullyonculvertreplacementandextensionjobs.Largeflexpipecanbeusedonlargerstreamsduringculvertremoval,repair,orreplacement;and,•Connectedtoexistingdownspoutsandroofdrainsandusedtodivertwaterawayfromworkareasduringbuildingrenovation,demolition,andconstructionprojects.Therearenowseveralcommerciallyavailablecollectorsthatareattachedtothepipeinletandhelppreventerosionattheinlet.ohimeConsirudilonS!onnii’aterPot/uiionPreen/ioniius!2012 DesignandSizethepipetoconveytheflow.ThecapacityfortemporarydrainsshallbeInstallatia,;sufficienttohandlethepeakflowfroma10-year,24-hourstormevent,Spec(ficationsassumingaTypeIArainfalldistribution.Alternatively,use1.6timesthe10-year,1-hourflowindicatedbyanapprovedcontinuousrunoffmodel.Consultlocaldrainagerequirementsforsizingpermanentpipeslopedrains.•Usecareinclearingvegetatedslopesforinstallation.•Re-establishcoverimmediatelyonareasdisturbedbyinstallation.•Usetemporarydrainsonnewcutorfillslopes.•Usediversiondikesorswalestocollectwateratthetopoftheslope.•Ensurethattheentranceareaisstableandlargeenoughtodirectflowintothepipe.•Pipingofwaterthroughthebermattheentranceareaisacommonfailuremode.•Theentranceshallconsistofastandardflaredendsectionforculverts12inchesandlargerwithaminimum6-inchmetaltoeplatetopreventrunofffromundercuttingthepipeinlet.Theslopeoftheentranceshallbeatleast3percent.Sandbagsmayalsobeusedatpipeentrancesasatemporarymeasure.•Thesoilaroundandunderthepipeandentrancesectionshallbethoroughlycompactedtopreventundercutting.•Theflaredinletsectionshallbesecurelyconnectedtotheslopedrainandhavewatertightconnectingbands.•Slopedrainsectionsshallbesecurelyfastenedtogether,ftisedorhavegasketedwatertightfittings,andshallbesecurelyanchoredintothesoil.•Thrustblocksshouldbeinstalledanytime90degreebendsareutilized.Dependingonsizeofpipeandflow,thesecanbeconstructedwithsandbags,strawbalesstakedinplace,“t”postsandwire,orecologyblocks.•Pipeneedstobesecuredalongitsfulllengthtopreventmovement.Thiscanbedonewithsteel“t”postsandwire.Apostisinstalledoneachsideofthepipeandthepipeiswiredtothem.Thisshouldbedoneevery10-20feetofpipelengthorso,dependingonthesizeofthepipeandquantityofwatertodivert.•Interceptordikesshallbeusedtodirectrunoffintoaslopedrain.Theheightofthedikeshallbeatleast1foothigheratallpointsthanthetopoftheinletpipe.•Theareabelowtheoutletmustbestabilizedwithariprapapron(seeBMPC209OutletProtection,fortheappropriateoutletmaterial).oIzinwConstructionStornni’aterPollutionPieen/iouuus!2012 Ifthepipeslopedrainisconveyingsediment-ladenwater,directallflowsintothesedimenttrappingfacility.•Materialsspecificationsforanypermanentpipedsystemshallbesetbythelocalgovernment.MaintenanceStandardsCheckinletandoutletpointsregularly,especiallyafterstorms.Theinletshouldbefreeofundercutting,andnowatershouldbegoingaroundthepointofentry.Ifthereareproblems,theheadwal!shouldbereinforcedwithcompactedearthorsandbags.•Theoutletpointshouldbefreeoferosionandinstalledwithappropriateoutletprotection.•Forpermanentinstallations,inspectpipeperiodicallyforvandalismandphysicaldistresssuchasslidesandwind-throw.•Normallythepipeslopeissosteepthatcloggingisnotaproblemwithsmoothwallpipe,however,debrismaybecomelodgedinthepipe.Figure4.2.4—PipeSlopeDrainDikematerialcompacted90%modifiedproctorCPEPorequivalentpipeDikeDischargetoastabilizedwatercourse,sedimentretentionfacility,orstabilizedoutletStandardflaredendsectionInletandallsectionsmustbesecurelyfastenedtogetherwithgasketedwatertightfittingsolwneConstructionS/onmi’atcrPollutionPreentioniius!2012 BMPC205:SubsurfaceDrainsPurposeTointercept,collect,andconveygroundwatertoasatisfactoryoutlet,usingaperforatedpipeorconduitbelowthegroundsurface.Subsurfacedrainsarealsoknownas“frenchdrains.”Theperforatedpipeprovidesadewateringmechanismtodrainexcessivelywetsoils,provideastablebaseforconstruction,improvestabilityofstructureswithshallowfoundations,ortoreducehydrostaticpressuretoimproveslopestability.(‘onditionsofUseUsewhenexcessivewatermustberemovedfromthesoil.Thesoilpermeability,depthtowatertableandimperviouslayersareallfactorswhichmaygoverntheuseofsubsurfacedrains.Designalit!RIfdrainareusedeithertolowerthewatertableinlarge.relativelyInstallationflatareas,improvethegrowthofvegetation,ortoremovesurfacewater.SpecjflcationsReliefdrainsareinstalledalongaslopeanddraininthedirectionoftheslope.Theycanbeinstalledinagridpattern,aherringbonepattern,orarandompattern.Inrordrainareusedtoremoveexcessgroundwaterfromaslope,stabilizesteepslopes,andlowerthewatertableimmediatelybelowaslopetopreventthesoilfrombecomingsaturated.Interceptordrainsareinstalledperpendiculartoaslopeanddraintothesideoftheslope.Theyusuallyconsistofasinglepipeorseriesofsinglepipesinsteadofapatternedlayout.•Dandainofinrordrain--Thedepthofaninterceptordrainisdeterminedprimarilybythedepthtowhichthewatertableistobeloweredorthedepthtoaconfininglayer.Forpracticalreasons,themaximumdepthisusuallylimitedto6feet,withaminimumcoverof2feettoprotecttheconduiL•Thesoilshouldhavedepthandsufficientpcrmcabiliwtopermitinstallationofaneffectivedrainagesystematadepthof2to6feet.•Anadequateoutletforthedrainagesystemmustbeavailableeitherbygravityorbypumping.•Thequantityandqualityofdischargeneedstobeaccountedforinthereccivingstream(additionaldetentionmaybcrequired).•Thisstandarddoesnotapplytosubsurfacedrainsforbuildingfoundationsordeepexcavations.•Thecapacityofaninterceptordrainisdeterminedbycalculatingthemaximumrateofgroundwaterflowtobeintercepted.Therefore,itisohi;neCons/rue/ionS/onn;i’a/erPollutionPieen/ionuus!2012 goodpracticetomakecompletesubsurfaceinvestigations,includinghydraulicconductivityofthesoil,beforedesigningasubsurfacedrainagesystem.•Siofdrain--Sizesubsurfacedrainstocarry’therequiredcapacitywithoutpressureflow.Minimumdiameterforasubsurfacedrainis4inches.•Theminimumvelocityrequiredtopreventsiltingis1.4ft./sec.Thelineshallbegradedtoachievethisvelocityataminimum.Themaximumallowablevelocityusingasand-gravelfilterorenvelopeis9fUsec.•Filtermaterialandfabricshallbeusedaroundalldrainsforproperbeddingandfiltrationoffinematerials.Envelopesandfiltersshouldsurroundthedraintoaminimumof3-inchthickness.•Theoutletofthesubsurfacedrainshallempty’intoasedimentpondthroughacatchbasin.Iffreeofsediment,itcanthenemptyintoareceivingchannel,swale,orstablevegetatedareaadequatelyprotectedfromerosionandundermining.•Thetrenchshallbeconstructedonacontinuousgradewithnoreversegradesorlowspots.•Softoryieldingsoilsunderthedrainshallbestabilizedwithgravelorothersuitablematerial.•Backlillingshallbedoneimmediatelyafterplacementofthepipe.Nosectionsofpipeshallremainuncoveredovernightorduringarainstorm.Backfillmaterialshallbeplacedinthetrenchinsuchamannerthatthedrainpipeisnotdisplacedordamaged.•Donotinstallpermanentdrainsneartreestoavoidthetreerootsthattendtoclogtheline.Usesolidpipewithwatertightconnectionswhereitisnecessary’topassasubsurfacedrainagesystemthroughastandoftrees.•0--Ensurethattheoutletofadrainemptiesintoachannelorotherwatercourseabovethenormalwaterlevel.•Secureananimalguardtotheoutletendofthepipetokeepoutrodents.•Useoutletpipeofcorrugatedmetal,castiron,orheavy-dutyplasticwithoutperforationsandatleast10feetlong.Donotuseanenvelopeorfiltermaterialaroundtheoutletpipe,andburyatleasttwo-thirdsofthepipelength.•Whenoutletvelocitiesexceedthoseallowableforthereceivingstream,outletprotectionmustbeprovided.obtineConsinictionStonmi’aterPollze/io;iPieentionitits!20120 MaintenanceSubsurfacedrainsshallbecheckedperiodicallytoensurethattheyareStandardsfree-flowingandnotcloggedwithsedimentorroots.•Theoutletshallbekeptcleanandfreeofdebris.•SurfaceinletsshalLbekeptopenandfreeofsedimentandotherdebris.•Treeslocatedtooclosetoasubsurfacedrainoftenclogthesystemwiththeirroots.Ifadrainbecomesclogged,relocatethedrainorremovethetreesasalastresort.Drainplacementshouldbeplannedtominimizethisproblem.•Wheredrainsarecrossedbyheavyvehicles,thelineshallbecheckedtoensurethatitisnotcrushed.BMPC206:LevelSpreaderPurposeToprovideatemporaryoutletfordikesanddiversionsconsistingofanexcavateddepressionconstructedatzerogradeacrossaslope.Toconvertconcentratedrunofftosheetflowandreleaseitontoareasstabilizedbyexistingvegetationoranengineeredfilterstrip.ConditionsofUseUsedwhenaconcentratedflowofwaterneedstobedispersedoveralargeareawithexistingstablevegetation.•Itemstoconsiderare:I.Whatistheriskoferosionordamageiftheflowmaybecomeconcentrated?2.Isaneasementrequiredifdischargedtoadjoiningproperty?3.Mostoftheflowshouldbeasgroundwaterandnotassurfaceflow.4.Isthereanunstableareadownstreamthatcannotacceptadditionalgroundwater?•Useonlywheretheslopesaregentle,thewatervolumeisrelativelylow,andthesoilwilladsorbmostofthelowflowevents.DesignandUseaboveundisturbedareasthatarestabilizedbyexistingvegetation.InstallationTfthelevelspreaderhasanylowpoints,flowwillconcentrate,createSpecificationschannelsandmaycauseerosion.•Dischargeareabelowtheoutletmustbeuniformwithaslopeflatterthan511:IV.•Outlettobeconstructedlevelinastable,undisturbedsoilprofile(notonfill).•Therunoffshallnotre-concentrateafterreleaseunlessinterceptedbyanotherdownstreammeasure.ohuneConstructionStormii’a!erPollutionPreen/ioniius!20)2I •Thegradeofthechannelforthelast20feetofthedikeorinterceptorenteringthelevelspreadershallbelessthanorequalto1percent.Thegradeofthelevelspreadershallbe0percenttoensureuniformspreadingofstormrunofE•A6-inchhighgravelbermplacedacrossthelevellipshallconsistofwashedcrushedrock,2-to4-inchor3/4-inchtoIVa-inchsize.•Thespreaderlengthshallbedeterminedbyestimatingthepeakflowexpectedfromthe10-year,24-hourdesignstorm.Thelengthofthespreadershallbeaminimumof15feetfor0.1cfsandshallincreaseby10feetforeach0.1cfsthereaftertoamaximumof0.5cfsperspreader.Usemultiplespreadersforhigherflows.•Thewidthofthespreadershouldbeatleast6feet.AlaintenanceStandards•Thedepthofthespreaderasmeasuredfromthelipshouldbeatleast6inchesanditshouldbeuniformacrosstheentirelength.•Levelspreadersshallbesetbackfromthepropertylineunlessthereisaneasementforflow.•Levelspreaders,wheninstalledeverysoofteningrassyswales,keeptheflowsfromconcentrating.Materialsthatcanbeusedincludesandbags,lumber,logs,concrete,andpipe.Tofunctionproperly,thematerialneedstobeinstalledlevelandoncontour.Figures4.2.5Fiaure425and4.2.6provideacross-sectionandadetailofalevelspreader.Acappedperforatedpipecouldalsobeusedasaspreader.Thespreadershouldbeinspectedaftereveryrunoffeventtoensurethatitisffinctioningcorrectly.•Thecontractorshouldavoidtheplacementofanymaterialonthestructureandshouldpreventconstructiontrafficfromcrossingoverthestructure.•Ifthespreaderisdamagedbyconstructiontraffic,itshallbeimmediatelyrepaired.Figure4.2.5—CrossSectionofLevelSpreaderolunwConstructionS!onnu’aterPollutionPreentioniius!2012Pressure-Treated2’xlO’Dens&yvegetatedforaMm.of100’andslopelessthan5:13Mm.—I BMPC207:CheckDamsPurposeConstructionofsmalldamsacrossaswaleorditchreducesthevelocityofconcentratedflowanddissipatesenergyatthecheckdarn.ConditionsofUse\\Theretemporarychannelsorpermanentchannelsarenotyetvegetated,channelliningisinfeasible,and/orvelocitychecksarerequired.•CheckdamsmaynotbeplacedinstreamsunlessapprovedbytheStateDepartmentofFishandWildlife.Checkdamsmaynotbeplacedinwetlandswithoutapprovalfromapermittingagency.•DonotplacecheckdamsbelowtheexpectedbackwaterfromanysalmonidbearingwaterbetweenOctober1andMay31toensurethatthereisnolossofhighflowrefugehabitatforoverwinteringjuvenilesalmonidsandemergentsalmonidfry.•Constructrockcheekdamsfromappropriatelysizedrock.Therockusedmustbelargeenoughtostayinplacegiventheexpecteddesignflowthroughthechannel.Therockmustbeplacedbyhandorbymechanicalmeans(nodumpingofrocktoformdarn)toachievecompletecoverageoftheditchorswaleandtoensurethatthecenterofthedamislowerthantheedges.•Checkdamsmayalsobeconstructedofeitherrockorpea-gravelfilledbags.Numerousnewproductsarealsoavailableforthispurpose.Theytendtobere-usable,quickandeasytoinstall,effective,andcostefficient.•Placecheckdamsperpendiculartotheflowofwater.•Thedamshouldformatrianglewhenviewedfromtheside.Thispreventsundercuttingaswaterflowsoverthefaceofthedamratherthanfallingdirectlyontotheditchbottom.Spreadermustbelevel6”mmTreated2x1O”maybeabuttedendtoendformax.spreaderlengthof50- - -H41”mm.6”mm.tV11=11=111=111=1118mm.rebarsupporls8max.spacing—Figure4.2.6—DetailofLevelSpreaderoh,,,,eConstructionStornni’aterPollutionPieeli/jo,?uus!2012 •Beforeinstallingcheckdamsimpoundandbypassupstreamwaterflowawayfromtheworkarea.Optionsforbypassingincludepumps,siphons,ortemporarychannels.•Checkdamsinassociationwithsumpsworkmoreeffectivelyatslowingflowandretainingsedimentthanjustacheckdamalone.Adeepsumpshouldbeprovidedimmediatelyupstreamofthecheckdam.•Insomecases,ifcarefullylocatedanddesigned,checkdamscanremainaspermanentinstallationswithveryminorregrading.Theymaybeleftaseitherspillways,inwhichcaseaccumulatedsedimentwouldbegradedandseeded,orascheekdamstopreventifirthersedimentfromleavingthesite.•Themaximumspacingbetweenthedamsshallbesuchthatthetoeoftheupstreamdarnisatthesameelevationasthetopofthedownstreamdam.•Keepthemaximumheightat2feetatthecenterofthedam.•Keepthecenterofthecheckdamatleast12incheslowerthantheouteredgesatnaturalgroundelevation.•Keepthesideslopesofthecheckdamat2H:IVorflatter.•Keythestoneintotheditchbanksandextenditbeyondtheabutmentsaminimumof18inchestoavoidwashoutsfromoverflowaroundthedarn.•Usefilterfabricfoundationunderarockorsandbagcheckdam.Ifablanketditchlinerisused,filterfabricisnotnecessary.Apieceoforganicorsyntheticblanketcuttofitwillalsoworkforthispurpose.•Inthecaseofgrass-linedditchesandswales,allcheckdamsandaccumulatedsedimentshallberemovedwhenthegrasshasmaturedsufficientlytoprotecttheditchorswale-unlesstheslopeoftheswaleisgreaterthan4percent.Theareabeneaththecheckdamsshallbeseededandmulchedimmediatelyafterdamremoval.•Ensurethatchannelappurtenances,suchasculvertentrancesbelowcheckdams,arenotsubjecttodamageorblockagefromdisplacedstones.Ficure4.2.7depictsatypicalrockcheckdarn.MaintenanceCheckdamsshallbemonitoredforperformanceandsedimentStandardsaccumulationduringandaftcreachrunoffproducingrainfall.Sedimentshallberemovedwhenitreachesonehalfthesumpdepth.•Anticipatesubmergenceanddepositionabovethecheckdamanderosionfromhighflowsaroundtheedgesofthedam.•Ifsignificanterosionoccursbetweendams,installaprotectiveripraplinerinthatportionofthechannel.ohimeConstructionS!onmi’aterPollutionPieen/ionuus!2012 ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC207.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecv.wa.uov/prorams/vg/stormvater/ne;•’tech/eguiva1ent.htm1oh,,neConstructionStonnii’aterPollutionPieentionuus!2012 ohmieConstructionStornzii’a/crPothitionPieentionuus!2012Figure4.2.7—RockCheckDam BMPC208:TriangularSiltDike(TSD)(Geotextile-EncasedCheckDam)PurposeTriangularsiltdikesmaybeusedascheckdams,forperimeterprotection,fortemporarysoilstockpileprotection,fordropinletprotection,orasatemporaryinterceptordike.Condilio,,sofuse•Maybeusedonsoilorpavementwithadhesiveorstaples.TSDshavebeenusedtobuildtemporary:1.sedimentponds;2.diversionditches;3.concretewashoutfacilities;4.curbing;5.waterbars;6.levelspreaders;and,7.berms.DesignandMadeofurethanefoamsewnintoawovengeosyntheticfabric.Installation.....Itistrianoular,10inchesto14incheshighinthecenter,witha20-inchtoSpecifications28-inchbase.A2—footapronextendsbeyondbothsidesofthetrianglealongitsstandardsectionof7feet.Asleeveatoneendallowsattachmentofadditionalsectionsasneeded.•Installwithendscurveduptopreventwaterfromflowingaroundtheends.•Thefabricflapsandcheckdamunitsareattachedtothegroundwithwirestaples.WirestaplesshouldbeNo.11gaugewireandshouldbe200mmto300mminlength.•Whenmultipleunitsareinstalled,thesleeveoffabricattheendoftheunitshalloverlaptheabuttingunitandbestapled.•Checkdamsshouldbelocatedandinstalledassoonasconstructionwillallow.•Checkdamsshouldbeplacedperpendiculartotheflowofwater.•Whenusedascheekdams,theleadingedgemustbesecuredwithrocks,sandbags,orasmallkeyslotandstaples.•Inthecaseofgrass-linedditchesandswales,checkdamsandaccumulatedsedimentshallberemovedwhenthegrasshasmaturedsufficientlytoprotecttheditchorswaleunlesstheslopeoftheswaleisgreaterthan4percent.Theareabeneaththecheckdarnsshallbesccdcdandmulchedimmediatelyafterdamremoval.MaintenanceaTriangularsiltdamsshallbeinspectedforperformanceandsedimentohuneCons/rue/jo;;S/ornni’a/erPollutionPieeu/ionuus!2012 Standardsaccumulationduringandaftereachrunoffproducingrainfall.Sedimentshallberemovedwhenitreachesonehalftheheightofthedam.Anticipatesubmergenceanddepositionabovethetriangularsiltdamanderosionfromhighflowsaroundtheedgesofthedam.Immediatelyrepairanydamageoranyundercuttingofthedam.BMPC209:OutletProtectionPurposeOutletprotectionpreventsscouratconveyanceoutletsandminimizesthepotentialfordownstreamerosionbyreducingthevelocityofconcentratedstorirnvaterflows.ConditionsofuseOutletprotectionisrequiredattheoutletsofallponds,pipes,ditches,orotherconveyances,andwhererunoffisconveyedtoanaturalormanmadedrainaaefeaturesuchasastream.wetland.lake,orditch.DesignandThereceivingchannelattheoutletofaculvertshallbeprotectedfromInstallationerosionbyrockliningaminimumof6feetdownstreamandextendingupSpecjflcationsthechannelsidesaminimumof1—footabovethemaximummilwaterelevationor1-footabovethecrown,whicheverishigher.Forlargepipes(morethan18inchesindiameter).theoutletprotectionliningofthechannelislengthenedtofourtimesthediameteroftheculvert.•Standardwingwalls,andtaperedoutletsandpavedchannelsshouldalsobeconsideredwhenappropriateforpermanentculvertoutletprotection.(SeeWSDOTFlydraulicManual,availablethroughWSDOTEngineeringPublications).•Organicorsyntheticerosionblankets,withorwithoutvegetation,areusuallymoreeffectivethanrock,cheaper,andeasiertoinstall.Materialscanbechosenusingmanufacturerproductspecifications.ASTMtestresultsareavailableformostproductsandthedesignercanchoosethecorrectmaterialfortheexpectedflow.•Withlowflows,vegetation(includingsod)canbeeffective.•Thefollowingguidelinesshallbeusedforriprapoutletprotection:1.Ifthedischargevelocityattheoutletislessthan5fps(pipeslopelessthan1percent),use2—inchto8—inchriprap.Minimumthicknessis1-foot.2.For5to10fpsdischargevelocityattheoutlet(pipeslopelessthan3percent),use24-inchto48-inchriprap.Minimumthicknessis2feet.3.Foroutletsatthebaseofsteepslopepipes(pipeslopegreaterthan10percent),anengineeredenergydissipatershallbeused.•Filterfabricorerosioncontrolblanketsshouldalwaysbeusedunderripraptopreventscourandchannelerosion.ohmic(‘onstructionStornni’atcrPollutionPit’entioniizit2012 •Newpipeoutfallscanprovideanopportunityforlow-costfishhabitatimprovements.Forexample,analcoveoflow-velocitywatercanbecreatedbyconstructingthepipeoutfallandassociatedenergydissipaterbackfromthestreamedgeanddiggingachannel,over-widenedtotheupstreamside,fromtheoutfall.Ovenvinterinajuvenileandmigratingadultsalmonidsmayusethealcoveasshelterduringhighflows.Bankstabilization,bioengineering,andhabitatfeaturesmayberequiredfordisturbedareas.ThisworkmayrequireaHPA.SeeVolumeVformoreinformationonoutfallsystemdesign.Maintenance•Inspectandrepairasneeded.Standards.•Addrockasneededtomaintaintheintendedfunction.•Cleanenergydissipaterifsedimentbuildsup.BMPC220:StormDrainInletProtectionPurposeStormdraininletprotectionpreventscoarsesedimentfromenteringdrainagesystemspriortopcrmancntstabilizationofthedisturbedarea.Co,,ditionsofUseUsestormdraininletprotectionatinletsthatareoperationalbeforepermanentstabilizationofthedisturbeddrainagearea.Provideprotectionforallstormdraininletsdownslopeandwithin500feetofadisturbedorconstructionarea,unlessconveyingrunoffenteringcatchbasinstoasedimentpondortrap.Alsoconsiderinletprotectionforlawnandyarddrainsonnewhomeconstruction.Thesesmallandnumerousdrainscoupledwithlackofguttersinnewhomeconstructioncanaddsignificantamountsofsedimentintotheroofdrainsystem.Ifpossibledelayinstallinglawnandyarddrainsuntiljustbeforelandscapingorcapthesedrainstopreventsedimentfromenteringthesystemuntilcompletionoflandscaping.Provide18—inchesofsodaroundeachfinishedlawnandyarddrain.Table4.2.2listsseveraloptionsforinletprotection.Allofthemethodsforstormdraininletprotectiontendtoplugandrequireahighfrequencyofmaintenance.Limitdrainageareastooneacreorless.Possiblyprovideemergencyoverflowswithadditionalend-of-pipetreatmentwherestormwaterpondingwouldcauseahazard.olnuwConstructionSlormiraterPollutionPieentioniius!2012 Table4.2.2StormDrainInletProtectionApplicableforTypeofInletEmergencyPaved!EarthenProtectionOverflowSurfacesConditionsofUseDropInletProtectionExcavateddropinletYes,EarthenApplicableforheavyflows.Easyprotectiontemporarytomaintain.LargeareafloodingwillRequirement:30’X30/acreoccurBlockandgraveldropYesPavedorEarthenApplicableforheavyconcentratedinletprotectionflows.Willnotpond.GravelandwiredropNoApplicableforheavyconcentratedinletprotectionflows.Willpond.Canwithstandtraffic.CatchbasinfiltersYesPavedorEarthenFrequentmaintenancerequired.CurbInletProtectionCurbinletprotectionSmallcapacityPavedUsedforsturdymorecompactwithawoodenweiroverflowinstallation.BlockandgravelcurbYesPavedSturdy,butlimitedfiltration.inletprotectionCulvertInletProtectionCulvertinletsediment18monthexpectedlife.trapDesignandcciateDivnielProtection-AnexcavatedimpoundmentaroundtheInstallationstormdrain.SedimentsettlesoutofthestormwaterpriortoenteringtheSpecjficationsstormdrain.•Provideadepthof1-2ftasmeasuredfromthecrestoftheinletstructure.•Slopesidesofexcavationnosteeperthan2H:IV.•Minimumvolumeofexcavation35cubicyards.•ShapebasintoFitsitewithlongestdimensionorientedtowardthelongestinflowarea.•Installprovisionsfordrainingtopreventstandingwaterproblems.•Cleartheareaofalldebris.•Gradetheapproachtotheinletuniformly.•Drillweepholesintothesideoftheinlet.•Protectweepholeswithscreenwireandwashedaggregate.•Sealweepholeswhenremovingstructureandstabilizingarea.ohuneConstructionStonnii’caerPollutionPreen/ioniiUSI20120 •.Buildatemporary’dike,ifnecessary’,tothedownslopesideofthestructuretopreventbypassflow.TheanGritciil/cr-Abanierformedaroundthestormdraininletwithstandardconcreteblocksandgravel.SeeFigure4.2.8.•ProvideaheightofIto2feetaboveinlet.•Recessthefirstrow2-inchesintothegroundforstability.•Supportsubsequentcoursesbyplacinga2x4throughtheblockopening.•Donotusemortar.•Laysomeblocksinthebottomrowontheirsidefordewateringthepool.•PlacehardwareclothorcomparablewiremeshwithV-inchopeningsoverallblockopenings.•Placegraveljustbelowthetopofblocksonslopesof2Ff:IVorflatter.•Analternativedesignisagraveldonut.•Provideaninletslopeof3H:IV.•Provideanoutletslopeof2H:IV.•Provideal-footwidelevelstoneareabetweenthestructureandtheinlet.•Useinletslopestones3inchesindiameterorlarger.•Usegravel‘/2-toV4-inchataminimumthicknessofI-footfortheoutletslope.olunicConstructionStornni’aterPollutionPreen/ionitus!2012I .Figure4.2.8—BlockandGravelFilterGracianireesliter-Agravelbarrierplacedoverthetopoftheinlet.Thisstructuredoesnotprovideanoverflow.•Useahardwareclothorcomparablewiremeshwith¼-inchopenings.•Usecoarseaggregate.•Provideaheight1-footormore,18-incheswiderthaninletonallsides.•PlacewiremeshoverthedropinletsothatthewireextendsaminimumofI-footbeyondeachsideoftheinletstructure.•Overlapthestripsifmorethanonestripofmeshisnecessary.olunwconstructionStonniraterPollutionPreen/ionuus!2012PlanViewDrainGrateA’ConcreteBlockGravelBackfillSectionA—AConcreteBlockGravelBackfill___OverflowWaterWireScreenor/////FilterFabricPondingHeight_____ _ ___Notes:1.Dropinletsedimentbarriersaretobeusedforsmall,nearlyleveldrainageareas.(lessthan5%)2.Excavateabasinofsufficientsizeadjacenttothedropinlet.3.Thetopofthestructure(pondinglieilit)rousthewellbclovthegmundelevationdownslopetopreventrunofffromhvpassingtheinlet.Atemporarydilemayhenecessaryonthedownslopesideof(liestruclure ••Placecoarseaggregateoverthewiremesh.Provideatleasta12-inchdepthofgravelovertheentireinletopeningandextendatleast18-inchesonallsides.Cafebasinfliers—Useinsertsdesignedbymanufacturersforconstructionsites.Thelimitedsedimentstoragecapacityincreasestheamountofinspectionandmaintenancerequired,whichmaybedailyforheavysedimentloads.Toreducemaintenancerequirementscombineacatchbasinfilterwithanothertypeofinletprotection.Thistypeofinletprotectionprovidesflowbypasswithoutoverflowandthereforemaybeabettermethodforinletslocatedalongactiverights-of-way.•Provides5cubicfeetofstorage.•Requiresdewateringprovisions.•Providesahigh-flowbypassthatwillnotclogundernormaluseataconstructionsite.•Insertthecatchbasinfilterinthecatchbasinjustbelowthegrating.Curbtile!Protectionwitooeneir—Barrierformedaroundacurbinletwithawoodenframeandgravel.•Usewiremeshwith4-inchopenings.•Useextrastrengthfiltercloth.•Constructaframe.•Attachthewireandfilterfabrictotheframe.•Pilecoarsewashedaggregateagainstwire/fabric.•Placeweightonframeanchors.bcanGmciCurbizietProtection—Barrierformedaroundacurbinletwithconcreteblocksandgravel.SeeFigure4.2.9.•Usewiremeshwith¼-inchopenings.•Placetwoconcreteblocksontheirsidesabuttingthecurbateithersideoftheinletopening.Thesearespacerblocks.•Placea2x4studthroughtheouterholesofeachspacerblocktoalignthefrontblocks.•Placeblocksontheirsidesacrossthefrontoftheinletandabuttingthespacerblocks.•Placewiremeshovertheoutsideverticalface.•Pilecoarseaggregateagainstthewiretothetopofthebarrier.CurbanGutterScintentairier—Sandbagorrockberm(riprapandaggregate)3feethighand3feetwideinahorseshoeshape.SeeFiae4.2.10.c/tuneCons/rite/ionS/or,mi’a/erPollutionPreen/ionxius!2012 •Constructahorseshoeshapedberm,facedwithcoarseaggregateifusingriprap,3feethighand3feetwide,atleast2feetfromtheinlet.•Consiructahorseshoeshapedsedimentationtrapontheoutsideofthebermsizedtosedimenttrapstandardsforprotectingaculvertinlet.Maintenance•Inspectcatchbasinfiltersfrequently,especiallyafterstormevents.StandardsCleanandreplacecloggedinserts.Forsystemswithcloggedstonefilters:pullawaythestonesfromtheinletandcleanorreplace.Analternativeapproachwouldbetousethecloggedstoneasfillandputfreshstonearoundtheinlet.•Donotwashsedimentintostormdrainswhilecleaning.Spreadallexcavatedmaterialevenlyoverthesurroundinglandareaorstockpileandstabilizeasappropriate.ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquivalentC220.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecy.wa.gov/proarams/wg/stormwater/newtech/epuivalent.htmlolzmwCons/rue/ionStonnii’a/erPothillonPreen/ioniius!2012 PlanViewNOTES:1.Useblockandgraveltypesedimentbarrierwhencurbinletislocatedingentlyslopingstreetsegment,wherewatercanpondandallowsedimenttoseparatefromrunoff.2.Barriershallallowforoverflowfromseverestormevent.3.Inspectbarriersandremovesedimentaftereachstormevent,Sedimentandgravelmustberemovedfromthetraveledwayimmediately.Figure4.2.9—BlockandGravelCurbInletProtectionCatchBasinBackofSidewalkABackofCurbSectionA-A2x4WoodStudConcreteBlock%‘Drain(20mm)3,4DrainGravel(20mm)ConcreteBlockHeightConcreteBlockWireScreenorFilterFabricCurbInletWoodStud(100x50TimberStud)CatchBasinohoneConstructionStormwa!erPollutionPieen/ioniiust2012 PlanViewBackofSidew&kNOTES:1.Placecurbtypesedimentbarriersongentlyslopingstreetsegments,wherewatercanpondandallowsedimenttoseparatefromrunoff.2.Sandbagsofeitherburlaporwoven‘geotexfile’fabric,axefilledwithgravel,layeredandpackedtightly.3.Leaveaonesandbaggapinthetoprowtoprovideaspillwayforoverflow.4.InspectbarriersandremovesedimentaftereachstormeventSedimentandgravelmustberemovedfromthetraveledwayimmediately.Figure4.2.10—CurbandGutterBarrierBurlapSackstoontoCurbCatchBasinCurbInletRUNOFFBackofSandbagsStackedTightlyohmicConstructionStonnii’aterPollutionPieen/ioniius!2012 BMPC231:BrushBarrierPurposeConditionsofUseDesignandInstallationSpec(flcations.[Vlàintw,anceStandardsThepurposeofbrushbarriersistoreducethetransportofcoarsesedimentfromaconstructionsitebyprovidingatemporaryphysicalbarriertosedimentandreducingtherunoffvelocitiesofoverlandflow.•Brushbarriersmaybeuseddownslopeofalldisturbedareasoflessthanone-quarteracre.•Brushbarriersarenotintendedtotreatconcentratedflows,noraretheyintendedtotreatsubstantialamountsofoverlandflow.Anyconcentratedflowsmustbeconveyedthroughthedrainagesystemtoasedimentpond.Theonlycircumstanceinwhichoverlandflowcanbetreatedsolelybyabrushbarrier,ratherthanbyasedimentpond,iswhentheareadrainingtothebarrierissmall.•Brushbarriersshouldonlybeinstalledoncontours.•Height2feet(minimum)to5feet(maximum).•Width5feetatbase(minimum)to15feet(maximum).•Filterfabric(geotextile)maybeanchoredoverthebrushbermtoenhancethefiltrationabilityofthebarrier.Ten-ounceburlapisanadequatealternativetofilterfabric.•Chippedsitevegetation,compostedmulch,orwood-basedmulch(hogfuel)canbeusedtoconstructbrushbarriers.•A100percentbiodegradableinstallationcanbeconstructedusing10-ounceburlapheldinplacebywoodenstakes.Figure4.2.11depictsatypicalbrushbarrier.•Thereshallbenosignsoferosionorconcentratedrunoffunderoraroundthebarrier.Ifconcentratedflowsarebypassingthebarrier,itmustbeexpandedoraugmentedbytoed-infilterfabric.Thedimensionsofthebarriermustbemaintained.Ifrequired,drapefilterfabricoverbrushandsecurein4y4mm.trenchwithcompactedbackfill.Mm.5widebrushbarrierwithmay.6”diameterwoodydebris.Alternativelytopsoilstrippingsmaybeusedtoformthebarrier.Figure4.2.11—BrushBarrierohaneConstructionStonmi’a!erPollutionPreentionuus!2012 BMPC232:GravelFilterBermPurposeAgravelfilterbermisconstructedonrights-of-wayortrafficareaswithinaconstructionsitetoretainsedimentbyusingafilterbermofgravelorcrushedrock.ConditionsofUseWhereatemporarymeasureisneededtoretainsedimentfromrights-of-wayorintrafficareasonconstructionsites.Designand•Bermmaterialshallbe¼to3inchesinsize,washedwell-gradegravelInstallationorcrushedrockwithlessthan5percentfines.Specftications•Spacingofberms:—Every300feetonslopeslessthan5percent—Every200feetonslopesbetween5percentand10percent—Every100feetonslopesgreaterthan10percent•Bermdimensions:—1foothighwith3H:IVsideslopes—8linearfeetper1cfsrunoffbasedonthe10-year,24-hourdesignstormMaintenance•Regularinspectionisrequired.SedimentshallberemovedandfilterStandardsmaterialreplacedasneeded.BMPC233:SiltFencePurposeUseofasiltfencereducesthetransportofcoarsesedimentfromaconstructionsitebyprovidingatemporaryphysicalbarriertosedimentandreducingtherunoffvelocitiesofoverlandflow.SeeFiuure4.2.12fordetailsonsiltfenceconstruction.ConditionsofUseSiltfencemaybeuseddownslopeofalldisturbedareas.•Siltfenceshallpreventsoilcarriedbyrunoffwaterfromgoingbeneath,through,oroverthetopofthesiltfence,butshallallowthewatertopassthroughthefence.•Siltfenceisnotintendedtotreatconcentratedflows,norisitintendedtotreatsubstantialamountsofoverlandflow.Conveyanyconcentratedflowsthroughthedrainagesystemtoasedimentpond.•DonotconstructsiltfencesinstreamsoruseinV-shapedditches.Siltfencesdonotprovideanadequatemethodofsiltcontrolforanythingdeeperthansheetoroverlandflow.olinuc’Cons/ritdilonS!ori;npa/c,’PollutionPit’eli/jo,,iius!2012 Jointsinfilterfabricshallbesplicedatposts.Usestaples,wireringsor2”x2”b14Gawireorequivalenttoattachfabrictopostsequivarent,ifstandardAtl;:lflEJ2istrengthfabricusedIr.zJIiJ4AFilterfabricIIIIIUtIflhtlEj4jIiThH-i.9I6max—-Minimum4x4’trench—4’.9iiBackfilltrenchwithnativesoilPostspacingmaybeincreasedor3!4-1.5”washedgravelto8iiwirebackingIsused2”x2’woodposts,steeltenceposts,orequivalentFigure4.2.12—SiltFenceDesignand•UseincombinationwithsedimentbasinsorotherBMPs.Installation•Maxtmumslopesteepness(normal(perpendtcular)tofenceline)SpecificationsIH:IV.•Maximumsheetoroverlandflowpathlengthtothefenceof100feet.•Donotallowflowsgreaterthan0.5cfs.•Thegeotextileusedshallmeetthefollowingstandards.Allgeotextilepropertieslistedbelowareminimumaveragerollvalues(i.e.,thetestresultforanysampledrollinalotshallmeetorexceedthevaluesshowninTable4.2.3):Table4.2.3GeotextileStandardsPolymericMeshAOS0.60nmmaximumforslitfilmwoven(#30sieve).0.30(ASTM04751)mmmaximumforallothergeotextiletypes(#50sieve).0.15mmminimumforallfabrictypes(#100sieve).WaterPermlttlvltyO.OsecmInImum(ASTMD4491)GrabTensileStrength180lbs.Minimumforextrastrengthfabric.(ASTM04632)100lbsminimumforstandardstrengthfabric.GrabTensileStrength30%maximum(ASTMD4632)UltravioletResistance70%niinimum(ASTMD4355)•Supportstandardstrengthfabricswithwiremesh,chickenwire,2-inchx2-inchwire,safety’fence,orjutemeshtoincreasethestrengthofthedianeCons/rue/jo,;S/ornzitaterPollu/ioizPieen/ionaus!2012 •fabric.Siltfencematerialsareavailablethathavesyntheticmeshbackingattached.Filterfabricmaterialshallcontainultravioletrayinhibitorsandstabilizerstoprovideaminimumofsixmonthsofexpectedusableconstructionlifeatatemperaturerangeof0°F.to120°F.•One-hundredpercentbiodegradablesiltfenceisavailablethatisstrong,longlasting,andcanbeleftinplaceaftertheprojectiscompleted,ifpermittedbylocalregulations.•RefertoFigure4.2.12forstandardsiltfencedetails.IncludethefollowingstandardNotesforsiltfenceonconstructionplansandspecifications:1.ThecontractorshallinstallandmaintaintemporarysiltfencesatthelocationsshowninthePlans.2.Constructsiltfencesinareasofclearing.grading,ordrainagepriortostartingthoseactivities.3.Thesiltfenceshallhavea2-feetmm.anda2Y2-feetmax.heightabovetheoriginalgroundsurface.4.Thefilterfabricshallbesewntogetheratthepointofmanufacturetoformfilterfabriclengthsasrequired.Locateallsewnseamsatsupportposts.Alternatively,twosectionsofsiltfencecanbeoverlapped,providedtheContractorcandemonstrate,tothesatisfactionoftheEngineer,thattheoverlapislongenoughandthattheadjacentfencesectionsarecloseenoughtogethertopreventsiltladenwaterfromescapingthroughthefenceattheoverlap.5.Attachthefilterfabricontheup-slopesideofthepostsandsecurewithstaples,wire,orinaccordancewiththemanufacturersrecommendations.Attachthefilterfabrictothepostsinamannerthatreducesthepotentialfortearing.6.Supportthefilterfabricwithwireorplasticmesh,dependentonthepropertiesofthegeotextileselectedforuse.Ifwireorplasticmeshisused,fastenthemeshsecurelytotheup-slopesideofthepostswiththefilterfabricup-slopeofthemesh.7.Meshsupport,ifused,shallconsistofsteelwirewithamaximummeshspacingof2-inches,oraprefabricatedpolymericmesh.Thestrengthofthewireorpolymericmeshshallbeequivalenttoorgreaterthan180lbs.grabtensilestrength.Thepolymericmeshmustbeasresistanttothesamelevelofultravioletradiationasthefilterfabricitsupports.8.Burythebottomofthefilterfabric4-inchesmibelowthegroundsurface.Backfillandtampsoilinplaceovertheburiedportionofthefilterfabric,sothatnoflowcanpassbeneaththefenceandohitneConstructionStonnit’oterPollutionPieen/ionuus!2012U •scouringcannotoccur.Whenwireorpolymericback-upsupportmeshisused,thewireorpolymericmeshshallextendintotheground3-inchesmm.9.Driveorplacethefencepostsintotheground18-inchesmm.A12—inchmm.depthisallowediftopsoilorothersoftsubgradesoilisnotpresentand18-inchescannotbereached.Increasefencepostmm.depthsby6inchesifthefenceislocatedonslopesof3H:IVorsteeperandtheslopeisperpendiculartothefence.Ifrequiredpostdepthscannotbeobtained,thepostsshallbeadequatelysecuredbybracingorguyingtopreventoverturningofthefenceduetosedimentloading.10.Usewood,steelorequivalentposts.Thespacingofthesupportpostsshallbeamaximumof6-feet.Postsshallconsistofeither:•Woodwithdimensionsof2-inchesby2-incheswidemm.anda3-feetmm.length.Woodpostsshallbefreeofdefectssuchasknots,splits,orgouges.•No.6steelrebarorlarger.•ASTMA120steelpipewithaminimumdiameterof1-inch.•U,T,L,orCshapesteelpostswithaminimumweightof1.35lbs./ft.•Othersteelpostshavingequivalentstrengthandbendingresistancetothepostsizeslistedabove.11.Locatesiltfencesoncontourasmuchaspossible,exceptattheendsofthefence,wherethefenceshallbeturneduphillsuchthatthesiltfencecapturestherunoffwaterandpreventswaterfromflowingaroundtheendofthefence.12.Ifthefencemustcrosscontours,withtheexceptionoftheendsofthefence,placegravelcheekdamsperpendiculartothebackofthefencetominimizeconcentratedflowanderosion.Theslopeofthefencelinewherecontoursmustbecrossedshallnotbesteeperthan311:1V.•Gravelcheckdamsshallbeapproximately1-footdeepatthebackofthefence.Gravelcheckdamsshallbecontinuedperpendiculartothefenceatthesameelevationuntilthetopofthecheckdarninterceptsthegroundsurfacebehindthefence.•Gravelcheckdamsshallconsistofcrushedsurfacingbasecourse,gravelbackfillforwalls,orshoulderballast.Gravelcheckdamsshallbelocatedevery10feetalongthefencewherethefencemustcrosscontours.RefertoFigure4.2.13forslicingmethoddetails.Siltfenceinstallationusingtheslicingmethodspecifications:olumeConstructionStor,niiaierPollutionPieen/ia,;iius!2012I •1.Thebaseofbothendpostsmustbeatleast2-to4-inchesabovethetopofthefilterfabriconthemiddlepostsforditchcheckstodrainproperly.Useahandlevelorstringlevel,ifnecessan’,tomarkbasepointsbeforeinstallation.2.Installposts3-to4-feetapartincriticalretentionareasand6-to7-feetapartinstandardapplications.3.Installposts24-inchesdeeponthedownstreamsideofthesiltfence,andascloseaspossibletothefilterfabric,enablingpoststosupportthefilterfabricfromupstreamwaterpressure.4.Installpostswiththenipplesfacingawayfromthefilterfabric.5.Attachthefilterfabrictoeachpostwiththreeties,allspacedwithinthetop8-inchesofthefilterfabric.Attacheachtiediagonally45degreesthroughthefilterfabric,witheachpunctureatleast1-inchverticallyapart.Eachtieshouldbepositionedtohangonapostnipplewhentighteningtopreventsagging.6.Wrapapproximately6-inchesoffabricaroundtheendpostsandsecurewith3ties.7.Nomorethan24-inchesofa36-inchfilterfabricisallowedabovegroundlevel.Compactthesoilimmediatelynexttothefilterfabricwiththefrontwheelofthetractor,skidsteer,orrollerexertingatleast60poundspersquareinch.Compacttheupstreamsidefirstandtheneachsidetwiceforatotaloffourtrips.Checkandcorrectthesiltfenceinstallationforanydeviationbeforecompaction.Useaflat-bladedshoveltotuckfabricdeeperintothegroundifnecessary.oIiiiiwCo,,sir,,ctio,zStomnnrale,PollutionPieentionitits!2012 •RepairanydamageimmediatelyStandards•Interceptandconveyallevidentconcentratedflowsuphillofthesiltfencetoasedimentpond.•Checktheuphillsideofthefenceforsignsofthefencecloggingandactingasabarriertoflowandthencausingchannelizationofflowsparalleltothefence.Ifthisoccurs,replacethefenceorremovethetrappedsediment.olu;neConstructionStormwa!erPollutionPieen/ioniius!2012Afabi/e:anceFigure4.2.13—SiltFenceInstallationbySlicingMethod •.Removesedimentdepositswhenthedepositreachesapproximatelyone-thirdtheheightofthesiltfence,orinstallasecondsiltfence.Replacefilterfabricthathasdeterioratedduetoultravioletbreakdown.BMPC234:VegetatedStripPurposeVegetatedstripsreducethetransportofcoarsesedimentfromaconstructionsitebyprovidingatemporaryphysicalbarriertosedimentandreducingtherunoffvelocitiesofoverlandflow.ConditionsofUseaVegetatedstripsmaybeuseddownslopeofalldisturbedareas.Vegetatedstripsarenotintendedtotreatconcentratedflows,noraretheyintendedtotreatsubstantialamountsofoverlandflow.Anyconcentratedflowsmustbeconveyedthroughthedrainagesystemtoasedimentpond.Theonlycircumstanceinwhichoverlandflowcanbetreatedsolelybyastrip,ratherthanbyasedimentpond,iswhenthefollowingcriteriaaremet(seeTable4.2.4):Table4.2.4ContributingDrainageAreaforVegetatedStripsAraCanriinAraConriinaraMaConriinaraSoPrnSoaraFoaLnI.5H:IVorflatter67%orflatter100feet2H:1Vorflatter50%orflatter115feet4H:IVorflatter25%orflatter150feet6H:IVorflatter16.7%orflatter200feetIOH:IVorflatterI10%orflatter250feetDesignand•Thevegetatedstripshallconsistofaminimumofa25-footflowpathInstallationlengthcontinuousstripofdensevegetationwithtopsoil.Grass-Specjflcationscovered,landscapedareasaregenerallynotadequatebecausethevolumeofsedimentoverwhelmsthegrass.Ideally,vegetatedstripsshallconsistofundisturbednativegrowthwithawell-developedsoilthatallowsforinfiltrationofrunoff.•Theslopewithinthestripshallnotexceed4H:lV.•Theuphillboundaryofthevegetatedstripshallbedelineatedwithclearinglimits.Maintenance•AnyareasdamagedbyerosionorconstructionactivityshallbeStandardsseededimmediatelyandprotectedbymulch.•Ifmorethan5feetoftheoriginalvegetatedstripwidthhashadvegetationremovedorisbeingeroded,sodmustbeinstalled.•Ifthereareindicationsthatconcentratedflowsaretravelingacrossthebuffer,surfacewatercontrolsmustbeinstalledtoreducetheflowsohnneConstructionStornni’a/erPollutionPieen/ioniius!20)2 enteringthebuffer,oradditionalperimeterprotectionmustbeinstalled.BMPC235:WafflesPurposeWattlesaretemporan’erosionandsedimentcontrolbarriersconsistingofstraw,compost,orothermaterialthatiswrappedinbiodegradabletubularplasticorsimilarencasingmaterial.Theyreducethevelocityandcanspreadtheflowofnhandsheetrunoff,andcancaptureandretainsediment.Wattlesaretypically8to10inchesindiameterand25to30feetinlength.Wattlesareplacedinshallowtrenchesandstakedalongthecontourofdisturbedornewlyconstructedslopes.SeeFigure4.2.14fortypicalconstructiondetails.WSDOTStandardPlan1-30.30-00alsoprovidesinformationonWattles(http://wv.wsdot.wa.uov/Desien/Standards/Plans.htm#Section1)ConditionsofUse•Usewattles:•Indisturbedareasthatrequireimmediateerosionprotection.•Onexposedsoilsduringtheperiodofshortconstructiondelays.oroverwintermonths.•Onslopesrequiringstabilizationuntilpermanentvegetationcanbeestablished.•Thematerialuseddictatestheeffectivenessperiodofthewattle.Generally,Wattlesaretypicallyeffectiveforonetotwoseasons.•Preventrilhingbeneathwattlesbyproperlyentrenchingandabuttingwattlestogethertopreventwaterfrompassingbetweenthem.DesignCriteria•Installwattlesperpendiculartotheflowdirectionandparalleltotheslopecontour.•Narrowtrenchesshouldbedugacrosstheslopeoncontourtoadepthof3-to5-inchesonclaysoilsandsoilswithgradualslopes.Onloosesoils,steepslopes,andareaswithhighrainfall,thetrenchesshouldbedugtoadepthof5-to7-inches,or1/2to2/3ofthethicknessofthewattle.•Startbuildingtrenchesandinstallingwattlesfromthebaseoftheslopeandworkup.Spreadexcavatedmaterialevenlyalongtheuphillslopeandcompactedusinghandtampingorothermethods.•Constructtrenchesatintervalsof10-to25-feetdependingonthesteepnessoftheslope,soiltype,andrainfall.Thesteepertheslopetheclosertogetherthetrenches.•Installthewattlessnuglyintothetrenchesandabuttightlyendtoend.Donotoverlaptheends.•Installstakesateachendofthewattle,andat4-footcentersalongentirelengthofwattle.ohmicConslruclioiiStornn:’aterPollutionPieentioniius!2012 ••Ifrequired,installpilotholesforthestakesusingastraightbartodriveholesthroughthewattleandintothesoil.•Woodenstakesshouldbeapproximately3/4x3/4x24inchesmm.WilLowcuttingsor3/8-inchrebarcanalsobeusedforstakes.•Stakesshouldbedriventhroughthemiddleofthewattle,leaving2to3inchesofthestakeprotrudingabovethewattle.Mainteiiaiice•WattlesmayrequiremaintenancetoensuretheyareincontactwithStandardssoilandthoroughlyentrenched,especiallyaftersignificantrainfallonsteepsandysoils.ohmicCons/inc/ionS/or,,nvalc,’PothdionPieen/iouuits!2012 .StrawRollsMustBePlacedAlongSlopeContoursFigure4.2.14—Wattles10-25’(3-em)SedIment,organIcmatter,—andnativeseedsarecapturedbehindtherolis.SpacIngDependsonSoilTypeandSlopeSteepnessLive3’5”(75.125mm)8’-lO’DIA.1”Xl”Stakenottoscale(25x25mm)NOTE:1.Struwrollinstallationrequirestheplacementandsecurestakingoftherollinafrench,3-5’(75-125mm)deep,dugoncontour.runoffmustnotbeallowedtorununderoraroundroil.ohmicCons/inc/jo,;Stonmiak,-PollutionPieentionUUS!2012 •.Inspecttheslopeaftersignificantstormsandrepairanyareaswherewattlesarenottightlyabuttedorwaterhasscouredbeneaththewattles.ApprovedasEcologyhasapprovedproductsasabletomeettherequirementsofBMPEquiva!entC235.TheproductsdidnotpassthroughtheTechnologyAssessmentProtocol—Ecology(TAPE)process.Localjurisdictionsmaychoosenottoacceptthisproductapprovedasequivalent,ormayrequireadditionaltestingpriortoconsiderationforlocaluse.TheproductsareavailableforreviewonEcology’swebsiteathttp://www.ecy.wa.gov/prourams/wg/stormwater/newtech/eguivalent.htmlBMPC236:VegetativeFiltrationPurposeVegetativeFiltrationmaybeusedinconjunctionwithBMPC241TemporarySedimentPonds,BMPC206LevelSpreaderandapumpingsystemwithsurfaceintaketoimproveturbiditylevelsofstormwaterdischargesbyfilteringthroughexistingvegetationwhereundisturbedforestfloordufflayerorestablishedlawnwiththatchlayerarepresent.VegetativeFiltrationcanalsobeusedtoinfiltratedewateringwastefromfoundations,vaults,andtrenchesaslongasrunoffdoesnotoccur.ConditionsofUse•Foreveryfiveacreofdisturbedsoiluseoneacreofgrassfield,farmpasture,orwoodedarea.Reduceorincreasethisareadependingonprojectsize,groundwatertableheight,andothersiteconditions.•Wetlandsshallnotbeusedforfiltration.•DonotusethisBMPinareaswithahighgroundwatertable,orinareasthatwillhaveahighseasonalgroundwatertableduringtheuseofthisBMP.•ThisBMPmaybelesseffectiveonsoilsthatpreventtheinfiltrationofthewater,suchashardtill.•UsingothereffectivesourcecontrolmeasuresthroughoutaconstructionsitewillpreventthegenerationofadditionalhighlyturbidwaterandmayreducethetimeperiodorareaneedforthisBMP.•Stopdistributingwaterintothevegetatedareaifstandingwaterorerosionresults.DesignCriteria•Findlandadjacenttotheprojectthathasavegetatedfield,preferablyafarmfield,orwoodedarea.•Iftheprojectsitedoesnotcontainenoughvegetatedfieldareaconsiderobtainingpermissionfromadjacentlandowners(especiallyforfarmfields).•Installapumpanddownstreamdistributionmanifolddependingontheprojectsize.Generally,themaindistributionlineshouldreach100to200-feetlong(manylargeprojects,orprojectsontightsoil,willoliuneCons/rue/ionS/orn,ii’a/erPollutionPreen/ionitus!2012 requiresystemsthatreachseveralthousandfeetlongwithnumerousbranchlinesoffofthemaindistributionline).•Thernanifo)dshouWhaveseveralvalves,allowingforcontroloverthedistributionareainthefield.•Installseveralbranchesof4”schedule20.swaged-fitcommonseptictight-linedsewerline,or6”firehose,whichcanconveytheturbidwaterouttovarioussectionsofthefield.SecFiuure4.2.15.•Determinethebranchlengthbasedonthefieldareageographyandnumberofbranches.Typically,branchesstretchfrom200-feettoseveralthousandfeet.Always.laybranchesoncontourwiththeslope.•Onunevenground,sprinklersperformwell.Spacesprinklerheadssothatspraypatternsdonotoverlap.•Onrelativelyevensurfaces,alevelspreaderusing4-inchperforatedpipemaybeusedasanalternativeoptiontothesprinklerheadsetup.Installdrainpipeatthehighestpointonthefieldandatvariouslowerelevationstoensurefullcoverageofthefiltrationarea.Pipeshouldbeplacewiththeholesuptoallowforagentleweepingofstormwaterevenlyoutallholes.Levelingthepipebystakingandusingsandbagsmayberequired.•Topreventtheoversaturationofthefieldarea,rotatetheuseofbranchesorsprayheads.Dothisasneededbasedonmonitoringthesprayfield.•Monitorthesprayfieldonadailybasistoensurethatoversaturationofanyportionofthefielddoesn’toccuratanytime.Thepresenceofstandingpuddlesofwaterorcreationofconcentratedflowsvisuallysignithatoversaturationofthefieldhasoccurred.•Sincetheoperatorishandlingcontaminatedwater,physicallymonitorthevegetatedsprayfieldallthewaydowntothenearestsurfacewater,orfrrthestsprayarea,toensurethatthewaterhasnotcausedoverlandorconcentratedflows,andhasnotcreatederosionaroundthespraynozzle.•Monitoringusuallyneedstotakeplace3-5timesperdaytoensuresheet-flowintostatewaters.Donotexceedwaterqualitystandardsforturbidity.•Ecologystronglyrecommendsthatascparatcinspcctionlogbedeveloped,maintainedandkeptwith[heexistingsitelogbooktoaidtheoperatorconductinginspections.Thisseparate“FieldFiltrationLogbook”canalsoaidthefacilityindemonstratingcompliancewithpermitconditions.MahztenancL’•Inspectthespraynozzlesdaily,ataminimum,forleaksandpluggingStandardsfromsedimentparticles.olznneConstructionStonuwaterPollutionPit’en/ionuus!2012 •Iferosion,concentratedflows,oroversaturationofthefieldoccurs,rotatetheuseofbranchesorsprayheadsormovethebranchestoanewfieldlocation.•Checkallbranchesandthemanifoldforunintendedleaks.FlowpathGuidelinesforVegetativeFiltrationAverageSlopeAverageArea%SlopeEstimatedFlowpathLength{ft}1.SH:1V67%2502H:1V50%2004H:1V25%1506H:1V16.7%1151OH:1V10%100ohmicConstructionS/orn;it’atcrPollutionPieentionuus!2012100Figure4.2.15—ManifoldandBrachesinawooded,vegetatedsprayfield BMPC240:SedimentTrapPurposeAsedimenttrapisasmalltemporarypondingareawithagraveloutletusedtocollectandstoresedimentfromsitesclearedand/orgradedduringconstruction.Sedimenttraps,alongwithotherperimetercontrols,shallbeinstalledbeforeanylanddisturbancetakesplaceinthedrainagearea.(‘o,,djfjo,,sofUsePriortoleavingaconstructionsite,stormwaterrunoffmustpassthroughasedimentpondortraporotherappropriatesedimentremovalbestmanagementpractice.Non-engineeredsedimenttrapsmaybeusedon-sitepriortoanengineeredsedimenttraporsedimentpondtoprovideadditionalsedimentremovalcapacity.Itisintendedforuseonsiteswherethetributarydrainageareaislessthan3acres,withnounusualdrainagefeatures,andaprojectedbuild-outtimeofsixmonthsorless.Thesedimenttrapisatemporarymeasure(withadesignlifeofapproximately6months)andshallbemaintaineduntilthesiteareaispermanentlyprotectedagainsterosionbyvegetationand/orstructures.Sedimenttrapsandpondsareonlyeffectiveinremovingsedimentdowntoaboutthemediumsiltsizefraction.Runoffwithsedimentoffinergrades(finesiltandclay)willpassthroughuntreated,emphasizingtheneedtocontrolerosiontothemaximumextentfirst.Wheneverpossible,sediment-ladenwatershallbedischargedintoon-site,relativelylevel,vegetatedareas(seeBMPC234—VegetatedStrip).Thisistheonlywaytoeffectivelyremovefineparticlesfromrunoffunlesschemicaltreatmentorfiltrationisused.Thiscanbeparticularlyusefulafterinitialtreatmentinasedimenttraporpond.Theareasofreleasemustbeevaluatedonasite-by-sitebasisinordertodetermineappropriatelocationsforandmethodsofreleasingrunoff.Vegetatedwetlandsshallnotbeusedforthispurpose.Frequently,itmaybepossibletopumpwaterfromthecollectionpointatthedownhillendofthesitetoanupslopevegetatedarea.Pumpingshallonlyaugmentthetreatmentsystem,notreplaceit,becauseofthepossibilityofpumpfailureorrunoffvolumeinexcessofpumpcapacity.Allprojectsthatareconstructingpermanentfacilitiesforrunoffquantitycontrolshouldusetherough-gradedorfinal-gradedpermanentfacilitiesfortrapsandponds.Thisincludescombinedfacilitiesandinfiltrationfacilities.Whenpermanentfacilitiesareusedastemporarysedimentationfacilities,thesurfacearearequirementofasedimenttraporpondmustbemet.Ifthesurfacearearequirementsarelargerthanthesurfaceareaofthepermanentfacility,thenthetraporpondshallbeenlargedtocomplywiththesurfacearearequirement.Thepermanentpondshallalsobedividedintotwocellsasrequiredforsedimentponds.olwneCons/rue/jo,,S!ornni’aterPollutionPieen/ioniius!2012101 Eitherapermanentcontrolstructureorthetemporarycontrolstructure(describedinBMPC241,TemporarySedimentPond)canbeused.Ifapermanentcontrolstructureisused,itmaybeadvisabletopartiallyrestrictthelowerorificewithgraveltoincreaseresidencetimewhilestillallowingdewateringofthepond.Ashut-offvalvemaybeaddedtothecontrolstructuretoallowcompleteretentionofstormwaterinemergencysituations.Inthiscase,anemergencyoverflowweirmustbeadded.AskimmermaybeusedforthesedimenttrapoutletifapprovedbytheLocalPermittingAuthority.Designand•SeeFiaures4.2.16and4.2.17fordetails.Installation.Specjfications•Ifpermanentrunoffcontrolfacilitiesarepartoftheproject,theyshouldbeusedforsedimentretention.Todeterminethesedimenttrapgeometry,firstcalculatethedesignsurfacearea(SA)ofthetrap,measuredattheinvertoftheweir.Usethefollowingequation:S=S(2!)where2=Designinflowbasedonthepeakdischargefromthedeveloped2-yearrunoffeventfromthecontributingdrainageareaascomputedinthehydrologicanalysis.The10-yearpeakflowshallbeusediftheprojectsize,expectedtiminganddurationofconstruction,ordownstreamconditionswarrantahigherlevelofprotection.Ifnohydrologicanalysisisrequired,theRationalMethodmaybeused.=Thesettlingvelocityofthesoilparticleofinterest.The0.02mm(mediumsilt)particlewithanassumeddensityof2.65g/cm3hasbeenselectedastheparticleofinterestandhasasettlingvelocity(.)of0.00096ft/sec.S=Asafetyfactorof2toaccountfornon-idealsettling.Therefore,theequationforcomputingsurfaceareabecomes:S=2x2/0.00096or2080squarefeetpercfsofinflowNote:Evenifpermanentfacilitiesareused,theymuststillhaveasurfaceareathatisatleastaslargeasthatderivedfromtheaboveformula.Iftheydonot,thepondmustbeenlarged.Toaidindeterminingsedimentdepth,allsedimenttrapsshallhaveastaffgaugewithaprominentmark1-footabovethebottomofthetrap.oheineConstructionS/ornni’a/erPollutionPieen/ionitits!2012102 Sedimenttrapsmaynotbefeasibleonutilityprojectsduetothelimitedworkspaceortheshort-termnatureofthework.Portabletanksmaybeusedinplaceofsedimenttrapsforutility’projects.A’IuintenanceStandards•Sedimentshallberemovedfromthetrapwhenitreaches1-footindepth.Anydamagetothepondembankmentsorslopesshallberepaired.SurfaceareadeterminedattopofweirFigure4.2.17—SedimentTrapOutletohuneConstructionStor,nii’aterPollutionPit’en/ion10itits!20123515FlatBottom4MmW’-1.5Vtashedgravel\2.4RockRipRapNote:TrapmaybeformedbybermorbypartialorcompleteexcavationGeotextileFigure4.2.16—CrossSectionofSedimentTrapDischargetostabilizedconveyance,outlet,orlevelspreaderI6Mm.Nativesoilorcompactedbackfill1’Mm.depthoverflowspillway BMPC241:TemporarySedimentPondPurposeSedimentpondsremovesedimentfromrunofforiginatingfromdisturbedareasofthesite.Sedimentpondsaretypicallydesignedtoremovesedimentnosmallerthanmediumsilt(0.02mm).Consequently,theyusuallyreduceturbidityonlyslightly.ConditionsofUsePriortoleavingaconstructionsite,stormwaterrunoffmustpassthroughasedimentpondorotherappropriatesedimentremovalbestmanagementpractice.Asedimentpondshallbeusedwherethecontributingdrainageareais3acresormore.Pondsmustbeusedinconjunctionwitherosioncontrolpracticestoreducetheamountofsedimentflowingintothebasin.Designand•SedimentbasinsmustbeinstalledonlyonsiteswherefailureofdieI,,sta!!ationstructurewouldnotresultinlossoflife,damagetohomesorSpecificationsbuildings,orinterruptionofuseorserviceofpublicroadsorutilities.Also,sedimenttrapsandpondsareattractivetochildrenandcanbeverydangerous.Compliancewithlocalordinancesregardinghealthandsafetymustbeaddressed.Iffencingofthepondisrequired,thetypeoffenceanditslocationshallbeshownontheESCplan.•Structureshavingamaximumstoragecapacityatthetopofthedamof10acre-ft(435,600ft3)ormorearesubjecttotheWashingtonDamSafetyRegulations(Chapter173-175WAC).•SeeFines4.2.18,4.2.19,and4.2.20fordetails.•Ifpermanentrunoffcontrolfacilitiesarepartoftheproject,theyshouldbeusedforsedimentretention.Thesurfacearearequirementsofthesedimentbasinmustbemet.Thismayrequiretemporarilyenlargingthepermanentbasinlocomplywiththesurfacearearequirements.Thepermanentcontrolstructuremustbetemporarilyreplacedwithacontrolstructurethatonlyallowswatertoleavethepondfromthesurfaceorbypumping.Thepermanentcontrolstructuremustbeinstalledafterthesiteisfillystabilized.•Useofinfiltrationfacilitiesforsedimentationbasinsduringconstructiontendstoclogthesoilsandreducetheircapacity’toinfiltrate.Ifinfiltrationfacilitiesaretobeused,thesidesandbottomofthefacilitymustonlyberoughexcavatedtoaminimumof2feetabovefinalgrade.Finalgradingof11winfiltrationfacilityshalloccuronlywhenallcontributingdrainageareasarefullystabilized.Theinfiltrationpretreatmentfacility’shouldbefillyconstructedandusedwiththesedimentationbasintohelppreventclogging.•DeterminingPondGeometryObtainthedischargefromthehydrologiccalculationsofthcpcakflowforthe2-yearrunoffevent(2).The10-yearpeakflowshallbeusedifohmicConstructionSlormwatcrPollutionPieen/ioniius!201210 theprojectsize,expectedtiminganddurationofconstruction,ordownstreamconditionswarrantahigherlevelofprotection.Ifnohydrologicanalysisisrequired,theRationalMethodmaybeused.Determinetherequiredsurfaceareaatthetopoftheriserpipewiththeequation:S=2x2/0.00096or2080squarefeetpercfsofinflowSeeBMPC240formoreinformationonthederivationofthesurfaceareacalculation.Thebasicgeometryofthepondcannowbedeterminedusingthefollowingdesigncriteria:•RequiredsurfaceareaSA(fromStep2above)attopofriser.•Minimum3.5-footdepthfromtopofrisertobottomofpond.•Maximum3H:IVinteriorsideslopesandmaximum2H:IVexteriorslopes.Theinteriorslopescanbeincreasedtoamaximumof2H:IViffencingisprovidedatorabovethemaximumwatersurface.•Onefootoffreeboardbetweenthetopoftheriserandthecrestoftheemergencyspillway.•Flatbottom.•Minimum1-footdeepspillway.•Length-to-widthratiobetween3:1and6:1.•SizingofDischargeMechanisms.Theoutletforthebasinconsistsofacombinationofprincipalandemergencyspiliways.Theseoutletsmustpassthepeakrunoffexpectedfromthecontributingdrainageareafora100-yearstorm.If,duetositeconditionsandbasingeometry,aseparateemergencyspill-wayisnotfeasible,theprincipalspillwaymustpasstheentirepeakrunoffexpectedfromthe100-yearstorm.However,anattempttoprovideaseparateemergencyspillwayshouldalwaysbemade.Therunoffcalculationsshouldbebasedonthesiteconditionsduringconstruction.Theflowthroughthedewateringorificecannotbeutilizedwhencalculatingthe100-yearstormelevationbecauseofitspotentialtobecomeclogged;therefore,availablespillwaystoragemustbeginattheprincipalspillwayrisercrest.Theprincipalspiliwaydesignedbytheprocedurescontainedinthisstandardwillresultinsomereductioninthepeakrateofrunoff.However,theriseroutletdesignwillnotadequatelycontrolthebasindischargetothepredevelopmentdischargelimitationsasstatedinMinimumRequirement#7:FlowControl.However,ifthebasinforapermanentstormwaterdetentionpondisusedforatemporaryohinwCons/ruclionS/onnii’a/erPoihilionPieen/ioniius!2012I0 sedimentationbasin,thecontrolstructureforthepermanentpondcanbeusedtomaintainpredevelopmentdischargelimitations.Thesizeofthebasin,theexpectedlifeoftheconstructionproject,theanticipateddownstreameffectsandtheanticipatedweatherconditionsduringconstruction,shouldbeconsideredtodeterminetheneedofadditionaldischargecontrol.SeeFigure4.2.21forriserinflowcurves.Figure4.2.19—SedimentPondCrossSectionohuneCons/rue/ionS/oniii’olctP0111(1ionPieen/ion10itus!2012Note:PondmaybeformedbybermorbypartialorcempleteexcavationDischargetostabilizedconveyance,outlet,orlevelspreaderFigure4.2.18—SedimentPondPlanViewRiserpipe(principalspitway)openattopwithtrashrackDewateringdevice(seeriserdetail)CrestofWrebacked&ltn1=1DewaternIIschargetostabizedstakedhaybaleswrappedorificeconveyanceoutletorwithfilterfabric,orlevelspreaderequivalentdividerConcretebase(seeriserdetail) Pclyelr.ylerecaPrc.ideade1aaeFigure4.2.20—SedimentPondRiserDetailohtnwConstructionSiornniatcrPollutionRn’entioniiits!201210Peioaedpolyalnylenedairaetib4nadamalermU,2IrgorliendewaledngQhfica,TubingshallcamptyASTMF667andAASHTOA294DewatedngcrWe.zhedule,40eeleubmm.DiameteraspercalcuIsonsAlternatively,metalstakesandAUSmaybeusedtopreventflotation 100C0UC,•7I..C,aa.0zUC0IncIa,0andHInfeetSlopechangeoccursatwdr-orificetransitionFigure4.2.21—RiserInflowCurvesohuneConstructionStormivaterPollutionPieen/ion10iius!2012.I__‘r/. ___iIIEEEEE100.1HEADINFEET(moasJredfromQ,,,=9.739DH”0a,iiicc820‘H112crestofriser)10 PriniaSiaDeterminetherequireddiameterfortheprincipalspillway(riserpipe).Thediametershallbetheminimumnecessarytopassthesite’s15-minute.10-yearflowrate.IfusingtheWesternWashingtonHydrologyModel(WWHM),Version2or3,designflowisthe10-year(Ihour)flowforthedeveloped(unmitigated)site,multipliedbyafactorof1.6.UseFigure4.2.21todeterminethisdiameter(=1-foot).oleennanen!con/nils/inc/L/remabeuseins/caoawi;iorarriser£rn0rfosiaDeterminetherequiredsizeanddesignoftheemergencyoverflowspillwayforthedeveloped100-yearpeakflowusingthemethodcontainedinVolumeIII.BarinOrifiDeterminethesizeofthedewateringorifice(s)(minimum1-inchdiameter)usingamodifiedversionofthedischargeequationforaverticalorificeandabasicequationfortheareaofacircularorifice.Determinetherequiredareaoftheorificewiththefollowingequation:—(2)fh—0.6x360005where=orificearea(squarefeet)=pondsurfacearea(squarefeet)=headofwateraboveorifice(heightofriserinfeet)=dewateringtime(24hours)accelerationofgravity(32.2feet/second2)ConverttherequiredsurfaceareatotherequireddiameterDoftheorifice:D=24xF=I3.54xThevertical,perforatedtubingconnectedtothedewateringorificemustbeatleast2incheslargerindiameterthantheorificetoimproveflowcharacteristics.Thesizeandnumberofperforationsinthetubingshouldbelargeenoughsothatthetubingdoesnotrestrictflow.Theorificeshouldcontroltheflowrate.AdditionalDesignSpecificationsThepondshallbedividedintotworoughlyequalvolumecellsbyapermeabledividerthatwillreduceturbulencewhileallowingmovementofwaterbetweencells.Thedividershallbeatleastone-halftheheightoftheriserandaminimumofonefootbelowthetopoftheriser.Wire-backed.2-to3-foothigh,extrastrengthfilterfabricsupportedbytreated4x4’scanbeusedasadivider.Alternatively,stakedstrawbaleswrappedwithfilterfabric(geotextile)maybeused.Ifthepondismorethan6feetdeep,adifferentmechanismmustbeproposed.AriprapembankmentisoneacceptablemethodofohiiiieCons/inc/ionS/or,nii’a!crFolly/ionPieeli/ionnus!201210 separationfordeeperponds.Otherdesignsthatsatisb’theintentofthisprovisionareallowedaslongasthedividerispermeable,structurallysound,anddesignedtopreventerosionunderoraroundthebarrier.Toaidindeterminingsedimentdepth,one-footintervalsshallbeprominentlymarkedontheriser.Ifanembankmentofmorethan6feetisproposed,thepondmustcomplywiththecriteriacontainedinVolumeIIIregardingdamsafetyfordetentionBMPs.•Themostcommonstructuralfailureofsedimentationbasinsiscausedbypiping.Pipingreferstotwophenomena:(1)waterseepingthroughfine-grainedsoil,erodingthesoilgrainbygrainandformingpipesortunnels;and,(2)waterunderpressureflowingupwardthroughagranularsoilwithaheadofsufficientmagnitudetocausesoilgrainstolosecontactandcapabilityforsupport.Themostcriticalconstructionsequencestopreventpipingwillbe:I.Tightconnectionsbetweenriserandbarrelandotherpipeconnections.2.Adequateanchoringofriser.3.Propersoilcompactionoftheembankmentandriserfooting.4.Properconstructionofanti-seepdevices.Maintenance•SedimentshallberemovedfromthepondwhenitreachesI—footinStandardsdepth.•Anydamagetothepondembankmentsorslopesshallberepaired.BMPC250:ConstructionStormwaterChemicalTreatmentPurposeThisRMPapplieswhenusingstormwaterchemicalsinbatchtreatmentorflow-throughtreatment.Turbidityisdifficulttocontroloncefineparticlesaresuspendedinslormwaterrunofffromaconstructionsite.Sedimentationpondsareeffectiveatremovinglargerparticulatematterbygravitysettling,butareineffectiveatremovingsmallerparticulatessuchasclayandfinesilt.TraditionalerosionandsedimentcontrolBMPsmaynotbeadequatetoensurecompliancewiththewaterqualitystandardsforturbidityinreceivingwater.Chemicaltreatmentcanreliablyprovideexceptionalreductionsofturbidityandassociatedpollutants.Chemicaltreatmentmayberequiredtomeetturbiditystormwaterdischargerequirements,especiallywhenconstructionistoproceedthroughthewetseason.ConditionsofUseFormalwrittenapprovalfromEcologyisrequiredfortheuseofchemicaltreatmentregardlessofsitesize.TheLocalPermittingAuthoritymayalsoolzmwConstrue/jonStornnra!erPollu/jo;,Preentionuus!2012110 •requirereviewandapproval.Whenapproved,thechemicaltreatmentsystemsmustbeincludedintheConstructionStormwaterPollutionPreventionPlan(SWPPP).DesignandSeeAppendixTI-Bforbackgroundinformationonchemicaltreatment.InstallalionSpecjficationsCr1naforCiaTraxiProdUChemicallytreatedstornnvaterdischargedfromconstructionsitesmustbenontoxictoaquaticorganisms.TheChemicalTechnologyAssessmentProtocol(CTAPE)mustbeusedtoevaluatechemicalsproposedforstormwatertreatment.OnlychemicalsapprovedbyEcologyundertheCTAPEmaybeusedforstonmvatertreatment.Theapprovedchemicals,theirallowableapplicationtechniques(batchtreatmentorflow-throughtreatment),allowableapplicationrates,andconditionsofusecanbefoundattheDepartmentofEcologyEmergingTechnologieswebsite:http://4”ww.ecv.wa.tzov/proErams/;vg/stormwater/newtechItechnolrndes.html.TranSDIxiConIdraionThedesignandoperationofachemicaltreatmentsystemshouldtakeintoconsiderationthefactorsthatdetermineoptimum,cost-effectiveperformance.Itisimportanttorecognizethefollowing:•OnlyEcologyapprovedchemicalsmaybeusedandmustfollowapproveddoserate.•ThepHofthestormwatermustbeintheproperrangeforthepolymerstobeeffective,whichistypically6.5to8.5•Thecoagulantmustbemixedrapidlyintothewatertoensureproperdispersion.•Aflocculationstepisimportanttoincreasetherateofsettling.toproducethelowestturbidity,andtokeepthedosagerateaslowaspossible.•Toolittleenergyinputintothewaterduringtheflocculationphaseresultsinflocsthataretoosmalland/orinsufficientlydense.Toomuchenergycanrapidlydestroyflocasitisformed.•Caremustbetakeninthedesignofthewithdrawalsystemtominimizeoutflowvelocitiesandtopreventbcdischarge.Dischargefromabatchtreatmentsystemshouldbedirectedthroughaphysicalfiltersuchasavcgctatcdswalcthatwouldcatchanyunintendedflocdischarge.Currently.flow-throughsystemsalwaysdischargethroughthechemicallyenhancedsandfiltrationsystem.•Systemdischargeratesmusttakeintoaccountdownstreamconveyanceintegrity.ohnneConstructionStor,niIa/crPollutionPreen/ionitus!2012Ill PurliaTranProDriionAbatchchemicaltreatmentsystemconsistsofthestormwatercollectionsystem(eithertemporarydiversionorthepermanentsitedrainagesystem).astoragepond.pumps.achemicalfeedsystem,treatmentcells,andinterconnectingpiping.Thebatchtreatmentsystemshalluseaminimumoftwolinedtreatmentcellsinadditiontoanuntreatedstonmvaterstoragepond.Multipletreatmentcellsallowforclarificationoftreatedwaterwhileothercellsarebeingfilledoremptied.Treatmentcellsmaybepondsortanks.Pondswithconstructedearthenembankmentsgreaterthansixfeethighorwhichimpoundmorethan10acre-feetrequirespecialengineeringanalyses.TheEcologyDamSafetySectionhasspecificdesigncriteriafordamsinWashingtonState(seelittp://www.ecy.wa.gov/prorams/wr/dams/GuidanceDocs.html).Stormwateriscollectedatinterceptionpoint(s)onthesiteandisdivertedbygravityorbypumpingtoanuntreatedstormwaterstoragepondorotheruntreatedstormwaterholdingarea.Thestormwaterisstoreduntiltreatmentoccurs.Itisimportantthattheholdingpondbelargeenoughtoprovideadequatestorage.ThefirststepinthetreatmentsequenceistocheckthepHofthestormwaterintheuntreatedstormwaterstoragepond.ThepHisadjustedbytheapplicationofcarbondioxideorabaseuntilthestormwaterinthestoragepondiswithinthedesiredpHrange,6.5to8.5.Whenused,carbondioxideisaddedimmediatelydownstreamofthetransferpump.Typicallysodiumbicarbonate(bakingsoda)isusedasabase,althoughotherbasesmaybeused.Whenneeded,baseisaddeddirectlytotheuntreatedstomiwaterstoragepond.Thestormwaterisrecirculatedwiththetreatmentpumptoprovidemixinginthestoragepond.InitialpHadjustmentsshouldbebasedondailybenchtests.FurtherpHadjustmentscanbemadeatanypointintheprocess.OncethestormwateriswithinthedesiredpHrange(dependantonpolymerbeingused),thestormwaterispumpedfromtheuntreatedstormwaterstoragepondtoatreatmentcellaspolymerisadded.Thepolymerisaddedupstreamofthepumptofacilitaterapidmixing.Afterpolymeraddition,thewateriskeptinalinedtreatmentcellforclarificationofthesediment-floc.Inabatchmodeprocess,clarificationtypicallytakesfrom30minutestoseveralhours.PriortodischargesamplesarewithdrawnforanalysisofpH,flocculentchemicalconcentration,andturbidity.Ifbothareacceptable,thetreatedwaterisdischarged.Severalconfigurationshavebeendevelopedtowithdrawtreatedwaterfromthetreatmentcell.TheoriginalconfigurationisadevicethatwithdrawsthetreatedwaterfromjustbeneaththewatersurfaceusingaolunieCons/nw/iouS/ornnra/erPollutionPreen/ionuus!2012111 floatwithadjustablestrutsthatpreventthefloatfromsettlingonthecellbottom.Thisreducesthepossibilityofpickingupsedirnent-flocfromthebottomofthepond.Thestrutsareusuallysetataminimumclearanceofabout12inches;thatis,thefloatwillcomewithin12inchesofthebottomofthecell.Othersystemshaveusedverticalguidesorcableswhichconstrainthefloat,allowingittodriftupanddownwiththewaterlevel.MorerecentdesignshaveanH-shapedarrayofpipes,setonthehorizontal.Thisschemeprovidesforwithdrawalfromfourpointsratherthanone.Thisconfigurationreducesthelikelihoodofsuckingsettledsolidsfromthebottom.Italsoreducesthetendencyforavortextoform.Inletdifftisers,alongfloatingorfixedpipewithmanysmallholesinit,arealsoanoption.Safetyisaprimaryconcern.Designshouldconsiderthehazardsassociatedwithoperations.suchassampling.Facilitiesshouldbedesignedtoreducesliphazardsanddrowning.Tanksandpondsshouldhaveliferings,ladders,orstepsextendingfromthebottomtothetop.PorHaTranProDriionAtaminimum,aflow-throughchemicaltreatmentsystemconsistsofthestormwatercollectionsystem(eithertemporary’diversionorthepermanentsitedrainagesystem),anuntreatedstormwaterstoragepond,andthechemicallyenhancedsandfiltrationsystem.Stormwateriscollectedatinterceptionpoint(s)onthesiteandisdivertedbygravityorbypumpingtoanuntreatedstormwaterstoragepondorotheruntreatedstormwaterholdingarea.Thestormwaterisstoreduntiltreatmentoccurs.Itisimportantthattheholdingpondbelargeenoughtoprovideadequatestorage.Stormwateristhenpumpedfromtheuntreatedstormwaterstoragepondtothechemicallyenhancedsandfiltrationsystemwherepolymerisadded.Adjustmentstop1-1maybenecessary’beforechemicaladdition.ThesandfiltrationsystemcontinuallymonitorsthestorniwaterforturbidityandpH.Ifthedischargewateriseveroutofanacceptablerangeforturbidityorp1-i,thewaterisrecycledtotheuntreatedstormwaterpondwhereitcanberetreated.Forhatchtreatmentandflow—throng!:treatment,thcfollowingcquipmcntshouldbelocatedinalockableshed:•Thechemicalinjector.•Secondarycontainmentforacid,caustic,bufferingcompound,andtreatmentchemical.•Emergencyshowerandeyewash.•MonitoringequipmentwhichconsistsofapHmeterandaturbidimeter.ohmicConstructionStonnit’aterPollutionPit’en/iouuus!201211 SSun:Certainsitesarerequiredtoimplementflowcontrolforthedevelopedsites.Thesesitesmustalsocontrolstormwaterreleaseratesduringconstruction.Generally,thesearesitesthatdischargestormwaterdirectly,orindirectly,throughaconveyancesystem,intoafreshwater.Systemsizingisdependentonflowcontrolrequirements.SiinCr1riaforBaTranSforFoConroEWarBodiThetotalvolumeoftheuntreatedstormwaterstoragepondandtreatmentpondsortanksmustbelargeenoughtotreatstormwaterthatisproducedduringmultipledaystormevents.Itisrecommendedthatataminimumtheuntreatedstorrnwaterstoragepondbesizedtohold1.5timestherunoffvolumeofthe10-year,24-hourstormevent.Bypassshouldbeprovidedaroundthechemicaltreatmentsystemtoaccommodateextremestormevents.RunoffvolumeshallbecalculatedusingthemethodspresentedinVolume3.Chapter2.Worst-caselandcoverconditions(i.e.,producingthemostrunoff)shouldbeusedforanalyses(inmostcases,thiswouldbethelandcoverconditionsjustpriortofinallandscaping).Primarysettlingshouldbeencouragedintheuntreatedstormwaterstoragepond.Aforebaywithaccessformaintenancemaybebeneficial.Therearetwoopposingconsiderationsinsizingthetreatmentcells.Alargercellisabletotreatalargervolumeofwatereachtimeabatchisprocessed.However,thelargerthecellthelongerthetimerequiredtoempty’thecell.Alargercellmayalsobelesseffectiveatflocculationandthereforerequirealongersettlingtime.Thesimplestapproachtosizingthetreatmentcellistomultiplytheallowabledischargeflowratetimesthedesireddrawdowntime.A4-hourdrawdowntimeallowsonebatchpercellper8-hourworkperiod,given1hourofflocculationfollowedbytwohoursofsettling.IfthedischargeisdirectlytoaflowcontrolexemptreceivingwaterlistedinAppendix1-EofVolumeIortoaninfiltrationsystem,thereisnodischargeflowlimit.Pondssizedforflowcontrolwaterbodiesmustataminimummeetthesizingcriteriaforflowcontrolexemptwaters.SiinCririaforFo-TroTranSforFoConroEWarBodiWhensizingstoragepondsortanksforflow-throughsystemsforflowcontrolexemptwaterbodies,thetreatmentsystemcapacityshouldbeafactor.Theuntreatedstormwaterstoragepondortankshouldbesizedtohold1.5timestherunoffvolumeofthe10-year,24-hourstormeventminusthetreatmentsystemflowrateforan8-hourperiod.Forachitosanenhancedsandfiltrationsystem,thetreatmentsystemflowrateshouldbesizedusingahydraulicloadingratebetween6-8gpm/ft2.OtherhydrauliccluineCo,zsfrz,c/jo,iS!onnii’alerPollulionPieentioniius!20)2I) loadingratesmaybemoreappropriateforothersystems.Bypassshouldbeprovidedaroundthechemicaltreatmentsystemtoaccommodateextremestorms.RunoffvolumeshallbecalculatedusingthemethodspresentedinVolume3,Chapter2.Worst-caselandcoverconditions(i.e..producingthemostrunoff)shouldbeusedforanalyses(inmostcases,thiswouldbethelandcoverconditionsjustpriortofinallandscaping).SiinCr1naforFoConroWarBodiSitesthatmustimplementflowcontrolforthedevelopedsiteconditionmustalsocontrolstormwaterreleaseratesduringconstruction.Constructionsitestormwaterdischargesshallnotexceedthedischargedurationsofdiepre-developedconditionfortherangeofpre-developeddischargeratesfrom¼ofthe2-yearflowthroughthe10-yearflowaspredictedbyanapprovedcontinuousrunoffmodel.Thepre-developedconditiontobematchedshallbethelandcoverconditionimmediatelypriortothedevelopmentproject.Thisrestrictiononreleaseratescanaffectthesizeofthestoragepondandtreatmentcells.ThefollowingishowWWHMcanbeusedtodeterminethereleaseratesfromthechemicaltreatmentsystems:1.Determinethepre-developedflowdurationstobematchedbyenteringtheexistinglanduseareaunderthe“Pre-developed”scenarioinWWHM.Thedefaultflowrangeisfrom¼ofthe2-yearflowthroughthe10-yearflow.2.Enterthepostdevelopedlanduseareainthe“DevelopedUnmitigated”scenarioinWWHM.3.Copythelanduseinformationfromthe“DevelopedUnmitigated”to“DevelopedMitigated”scenario.4.Whileinthe“DevelopedMitigated”scenario,addapondelementunderthebasinelementcontainingdiepost-developedlanduseareas.Thispondelementrepresentsinformationontheavailableuntreatedstormwaterstorageanddischargefromthechemicaltreatmentsystem.Incaseswherethedischargefromthechemicaltreatmentsystemiscontrolledbyapump,astage/storage/discharge(SSD)tablerepresentingthepondmustbegeneratedoutsideWWHMandimportedintoWWHM.WWI-JMcanroutetherunofffromthepost-developedconditionthroughthisSSDtable(thepond)anddeterminecompliancewithdieflowdurationstandard.ThiswouldbeaniterativedesignprocedurewhereiftheinitialSSDtableprovedtobeinadequate,thedesignerwouldhavetomodif’theSSDtableoutsideWWHMandre-importinWWHMandroutetherunoffthroughitagain.Theiterationwillcontinueuntilapondthatcomplieswiththeflowdurationstandardiscorrectlysized.NotesonSSDtablecharacteristics:ohuneCo,,s/n,c/ionStornnratcrPollutionPieentioniius!20]211 •Thepumpdischargeratewouldlikelybeinitiallysetatjustbelow‘/2ofthe2-yearflowfromthepre-developedcondition.Asrunoffcomingintotheuntreatedstormwaterstoragepondincreasesandtheavailableuntreatedstormwaterstoragevolumegetsusedup,itwouldbenecessarytoincreasethepumpdischargerateabove‘/2ofthe2-year.Theincrease(s)above‘/2ofthe2-yearmustbesuchthattheyprovidesomerelieftotheuntreatedstormwaterstorageneedsbutatthesametimewillnotcauseviolationsoftheflowdurationstandardatthehigherflows.ThefinaldesignSSDtablewillidentifytheappropriatepumpingratesandthecorrespondingstageandstorages.•V/henbuildingsuchaflowcontrolsystem,thedesignmustensurethatanyautomaticadjustmentstothepumpingrateswillbeasaresultofchangestotheavailablestorageinaccordancewiththefinaldesignSSDtable.5.Iishouldbenotedthattheaboveprocedureswouldbeusedtomeettheflowcontrolrequirements.Thechemicaltreatmentsystemmustbeabletomeettherunofftreatmentrequirements.Itislikelythatthedischargeflowrateof%ofthe2-yearormoremayexceedthetreatmentcapacity’ofthesystem.Ifthatisthecase,theuntreatedstormwaterdischargerate(s)(i.e.,influenttothetreatmentsystem)mustbereducedtoallowpropertreatment.Anyreductionintheflowswouldlikelyresultintheneedforalargeruntreatedstormwaterstoragevolume.Ifthedischargeistoamunicipalstormdrainagesystem.theallowabledischargeratemaybelimitedbythecapacityolthepublicsystem.Itmaybenecessarytocleanthemunicipalstormdrainagesystempriortothestartofthedischargetopreventscouringsolidsfromthedrainagesystem.lfthemunicipalstormdrainagesystemdischargestoawaterbodynotontheflowcontrolexemptlist,theprojectsiteissubjecttoflowcontrolrequirements.Obtainpermissionfromtheownerofthecollectionsystembeforedischargingtoit.Ifsystemdesigndoesnotallowyoutodischargeattheslowerratesasdescribedaboveandifthesitehasaretentionordetentionpondthatwillservetheplanneddevelopment,thedischargefromthetreatmentsystemmaybedirectedtothepermanentretention/detentionpondtocomplywiththeflowcontrolrequirement.Inthiscase,theuntreatedstormwaterstoragepondandtreatmentsystemwillbesizedaccordingtothesizingcriteriaforflow-throughtreatmentsystemsforflowcontrolexemptwaterbodiesdescribedearlierexceptalldischarge(waterpassingthroughthetreatmentsystemandstormwaterbypassingthetreatmentsystem)willbedirectedintothepermanentretention/detentionpond.Ifsiteconstraintsmakelocatingtheuntreatedstorrnwaterstorageponddifficult,thepermanentretention/detentionpondmaybedividedtoserveastheuntreatedstormwaterstoragepondandthepost-treatmentflowcontrolpond.AbermorbarriermustbeusedinthiscasesotheuntreatedwaterdoesnotmixwiththetreatedohuneConstructionStonnu’aterPollutionPieentionitits!201211 water.Bothuntreatedstormwaterstoragerequirements,andadequatepost-treatmentflowcontrolmustbeachieved.Thepost-treatmentflowcontrolpond’sreviseddimensionsmustbeenteredintotheWWHMandtheWWHMmustberuntoconfirmcompliancewiththeflowcontrolrequirement.MaintenanceMoniannAtaminimum,thefollowingmonitoringshallbeStandardsconducted.TestresultsshallbcrecordedonadailyJogkeptonsite.AdditionaltestingmayberequiredbytheNPDESpermitbasedonsiteconditions.OperationalMonitorinu:•Totalvolumetreatedanddischarged.•Flowmustbecontinuouslymonitoredandrecordedatnotgreaterthan15-minuteintervals.•TypeandamountofchemicalusedforpHadjustment.•Amountofpolymerusedfortreatment.•Settlingtime.ComplianceMonitoring:•InfluentandeffluentpH,flocculentchemicalconcentration,andturbiditymustbecontinuouslymonitoredandrecordedatnotgreaterthan15-minuteintervals.pHandturbidityofthereceivingwater.Biomonitoring:Treatedstormwatermustbenon-toxictoaquaticorganisms.Treatedstormwatermustbetestedforaquatictoxicityorresidualchemicals.FrequencyofbiomonitoringwillbedeterminedbyEcology.ResidualchemicaltestsmustbeapprovedbyEcologypriortotheiruse.Iftestingtreatedstormwaterforaquatictoxicity,youmusttestforacute(lethal)toxicity.BioassaysshallbeconductedbyalaboratojyaccreditedbyEcology,unlessotherwiseapprovedbyEcology.AcutetoxicitytestsshallbeconductedpertheCTAPEprotocol.DiarCoianPriorodiar,radoraradanddforoinnIH,foninonnraion,andridiiI.TheselimitsmaybeestablishedbytheConstructionStormwaterGeneralPermitorasite-specificdischargepermit.Samplingandtestingforotherpollutantsmayalsobenecessaryatsomesites.p11mustbewithintherangeof6.5to8.5standardunitsandnotcauseachangeinthepHofthereceivingwaterofmorethan0.2standardunits.Treatedstormwatersamplesandmeasurementsshallbetakenfromthedischargepipeoranotherlocationrepresentativeofthenatureofthetreatedstormwaterdischarge.Samplesusedfordeterminingcompliancewiththewaterqualitystandardsinthereceivingwatershallnotbetakenfromthetreatmentpondpriortodecanting.Compliancewiththewaterqualitystandardsisdeterminedinthereceivingwater.olumeConstructionStormii’aterPollutionPreentionuact201211 oraorTraininEachcontractorwhointendstousechemicaltreatmentshallbetrainedbyanexperiencedcontractor.EachsiteusingchemicaltreatmentmusthaveanoperatortrainedandcertifiedbyanorganizationapprovedbyEcology.SandardBMPSurfacestabilizationBMPsshouldbeimplementedonsitetopreventsignificanterosion.Allsitesshalluseatruckwheelwashtopreventtrackingofsedimentoffsite.SdinRoaandflioa•Sedimentshallberemovedfromthestorageortreatmentcellsasnecessary.Typically,sedimentremovalisrequiredatleastonceduringawetseasonandatthedecommissioningofthecells.Sedimentremaininginthecellsbetweenbatchesmayenhancethesettlingprocessandreducetherequiredchemicaldosage.•Sedimentthatisknowntobenon-toxicmaybeincorporatedintothesiteawayfromdrainages.BMPC251:ConstructionStormwaterFiltrationPurposeFiltrationremovessedimentfromrunofforiginatingfromdisturbedareasofthesite.Backgroundinformation:Filtrationwithsandmediahasbeenusedforoveracenturytotreatwaterandwastewater.Theuseofsandfiltrationfortreatmentofstormwaterhasdevelopedrecently,generallytotreatrunofffromstreets,parkinglots,andresidentialareas.Theapplicationoffiltrationtoconstructionstormwatertreatmentiscurrentlyunderdevelopment.ConditionsofUseTraditionalBMPsusedtocontrolsoilerosionandsedimentlossfromsitesunderdevelopmentmaynotbeadequatetoensurecompliancewiththewaterqualitystandardforturbidityinthereceivingwater.Filtrationmaybeusedinconjunctionwithgravitysettlingtoremovesedimentassmallasfinesilt(0.5g.tm).Thereductioninturbiditywillbedependentontheparticlesizedistributionofthesedimentinthestormwater.Insomecircumstances,sedimentationandfiltrationmayachievecomplianceviththewaterqualitystandardforturbidity.TheuseofconstructionstormwaterfiltrationdoesnotrequireapprovalfromEcologyaslongastreatmentchemicalsarenotused.FiltrationinconjunctionwithpolymertreatmentrequirestestingundertheChemicalTechnologyAssessmentProtocol—Ecology(CTAPE)beforeitcanbeinitiated.ApprovalfromtheappropriateregionalEcologyofficemustbeobtainedateachsitewherepolymersuseisproposedpriortouse.FormoreguidanceonstormwaterchemicaltreatmentseeBMPC250.ohiuwConstruction,ctor,ni’ate,Pothuionfireentionuus!2012II DesignandTwotypesoffiltrationsystemsmaybeappliedtoconstructionstormwaterInstallationtreatment:rapidandslow.RapidsandfiltersarethetypicalsystemusedSpecjficationsforwateraridwastewatertreatmenLTheycanachieverelativelyhighhydraulicflowrates,ontheorderof2to20gpm/sf,becausetheyhaveautomaticbackwashsystemstoremoveaccumulatedsolids.Incontrast,slowsandfiltershaveverylowhydraulicrates,ontheorderof0.02gpm/sf,becausetheydonothavebackwashsystems.Slowsandfiltrationhasgenerallybeenusedtotreatstorrnwater.Slowsandfiltrationismechanicallysimpleincomparisontorapidsandfiltrationbutrequiresamuchlargerfilterarea.FiraionEIn.Sandmediafiltersareavailablewithautomaticbackwashingfeaturesthatcanfilterto50jimparticlesize.Screenorbagfilterscanfilterdownto5jim.Fiberwoundfilterscanremoveparticlesdownto0.5lam.Filtersshouldbesequencedfromthelargesttothesmallestporeopening.Sedimentremovalefficiencywillberelatedtoparticlesizedistributioninthestormwater.TranProDriion.Stormwateriscollectedatinterceptionpoint(s)onthesiteandisdivertedtoanuntreatedstornnvatersedimentpondortankforremovaloflargesedimentandstorageofthestormwaterbeforeitistreatedbythefiltrationsystem.Theuntreatedstormwaterispumpedfromthetrap,pond,ortankthroughthefiltrationsysteminarapidsandfiltrationsystem.Slowsandfiltrationsystemsaredesignedasflowthroughsystemsusinggravity.MaintenanceRapidsandfilterstypicallyhaveautomaticbackwashsystemsthatareStandardstriggeredbyapre-setpressuredropacrossthefilter.Ifthebackwashwatervolumeisnotlargeorsubstantiallymoreturbidthantheuntreatedstormwaterstoredintheholdingpondortank,backwashreturntotheuntreatedstormwaterpondortankmaybeappropriate.However,othermeansoftreatmentanddisposalmaybenecessary.•Screen,bag,andfiberfiltersmustbecleanedand/orreplacedwhentheybecomeclogged.•Sedimentshallberemovedfromthestorageand/ortreatmentpondsasnecessary.Typically,sedimentremovalisrequiredonceortwiceduringawetseasonandatthedecommissioningoftheponds.SiinCr1riaforFo-TroTranSforFoConroEWarBodiWhensizingstoragepondsortanksforflow-throughsystemsforflowcontrolexemptwaterbodiesthetreatmentsystemcapacityshouldbeafactor.Theuntreatedstormwaterstoragepondortankshouldbesizedtohold1.5timestherunoffvolumeofthe10-year,24-hourstormeventminusthetreatmentsystemflowrateforan8-hourperiod.Forachitosanenhancedsandfiltrationsystem.thetreatmentsystemflowrateshouldbesizedusingahydraulicloadingratebetween6-8gpm/ft2.OtherhydraulicolwncConstructionStornni’olcrPollzuio,,PieenlionuILl201211 loadingratesmaybemoreappropriateforothersystems.Bypassshouldbeprovidedaroundthechemicaltreatmentsystemtoaccommodateextremestorms.RunoffvolumeshallbecalculatedusingthemethodspresentedinVolume3.Chapter2.Worst-caseconditions(i.e.,producingthemostrunoff)shouldbeusedforanalyses(mostlikelyconditionspresentpriortofinallandscaping).SiinCdnaforFoConroVarBodiSitesthatmustimplementflowcontrolforthedevelopedsiteconditionmustalsocontrolstorrnwaterreleaseratesduringconstruction.Constructionsitestormwaterdischargesshallnotexceedthedischargedurationsofthepre-developedconditionfortherangeofpre-developeddischargeratesfrom1/2ofthe2-yearflowthroughthe10-yearflowaspredictedbyanapprovedcontinuousrunoffmodel.Thepre-developedconditiontobematchedshallbethelandcoverconditionimmediatelypriortothedevelopmentproject.Thisrestrictiononreleaseratescanaffectthesizeofthestoragepond,thefiltrationsystem,andtheflowratethroughthefiltersystem.ThefollowingishowWWHMcanbeusedtodeterminethereleaseratesfromthefiltrationsystems:1.Determinethepre-developedflowdurationstobematchedbyenteringthelanduseareaunderthe“Pre-developed”scenarioinWWHM.Thedefaultflowrangeisfrom‘/2ofthe2-yearflowthroughthe10-yearflow.2.Enterthepostdevelopedlanduseareainthe“DevelopedUnmitigated”scenarioinWWHM.3.Copythelanduseinformationfromthe“DevelopedUnmitigated”to“DevelopedMitigated”scenario.4.Therealetwopossiblewaystomodelstormwaterfiltrationsystems:a.ThestormwaterfiltrationsystemusesanuntreatedstormwaterstoragepondItankandthedischargefromthispond/tankispumpedtooneormorefillers.In-linefiltrationchemicalswouldbeaddedtotheflowrightafterthepond/tankaridbeforethefilter(s).Becausethedischargeispumped,WWHMcan’tgenerateastage/storage/discharge(SSD)tableforthissystem.ThissystemismodeledthesamewayasdescribedinBMPC250andisasfollows:Whileinthe“DevelopedMitigated”scenario,addapondelementunderthebasinelementcontainingthepost-developedlanduseareas.Thispondelementrepresentsinformationontheavailableuntreatedstormwaterstorageanddischargefromthefiltrationsystem.Incaseswherethedischargefromthefiltrationsystemiscontrolledbyapump,astage/storage/discharge(SSD)tablerepresentingthepondmustbegeneratedoutsideWV/TIMandohmicConsinwilonS!ormii’atcrPollutionPieenlionuus!2012120 importedintoWWHM.WWHMcanroutetherunofffromthepost-developedconditionthroughthisSSDtable(thepond)anddeterminecompliancewiththeflowdurationstandard.ThiswouldbeaniterativedesignprocedurewhereiftheinitialSSDtableprovedtobeoutofcompliance,thedesignerwouldhavetomodi1’theSSDtableoutsideWWI-IMandre-importinWWHMandroutetherunoffthroughitagain.Theiterationwillcontinueuntilapondthatenablescompliancewiththeflowdurationstandardisdesigned.NotesonSSDtablecharacteristics:Thepumpdischargeratewouldlikelybeinitiallysetatjustbelow‘/:ifthe2-yearflowfromthepre-developedcondition.Asrunoffcomingintotheuntreatedstormwaterstoragepondincreasesandtheavailableuntreatedstormwaterstoragevolumegetsusedup,itwouldbenecessarytoincreasethepumpdischargerateabove4ofthe2-year.Theincrease(s)above%ofthe2-yearmustbesuchthattheyprovidesomerelieftotheuntreatedstormwaterstorageneedsbutatthesametimetheywillnotcauseviolationsoftheflowdurationstandardatthehigherflows.ThefinaldesignSSDtablewillidentifStheappropriatepumpingratesandthecorrespondingstageandstorages.Whenbuildingsuchaflowcontrolsystem,thedesignmustensurethatanyautomaticadjustmentstothepumpingrateswillbeasaresultofchangestotheavailablestorageinaccordancewiththefinaldesignSSDtable.b.Thestormwaterfiltrationsystemusesastoragepond/tankandthedischargefromthispond/tankgravityflowstothefilter.ThisisusuallyaslowsandfillersystemanditispossibletomodelitinWWHMasaFilterelementorasacombinationofPondandFilterelementplacedinseries.Thestage/storage/dischargetable(s)maythenbegeneratedwithinWWHMasfollows:(i)Whileinthe“DevelopedMitigated”scenario,addaFilterelementunderthebasinelementcontainingthepost-developedlanduseareas.Thelengthandwidthofthisfilterelementwouldhavetobethesameasthebottomlengthandwidthoftheupstreamuntreatedstormwaterstoragepond/tank.(ii)Incaseswherethelengthandwidthofthefilterisnotthesameasthoseforthebottomoftheupstreamuntreatedstormwaterstoragetank/pond,thetreatmentsystemmaybemodeledasaPondelementfollowedbyaFilterelement.Byhavingthesetwoelements,WWI-IMwouldthengenerateaSSDtableforthestoragepondwhichthengravityflowstotheFilterelement.TheFilterelementdownstreamoftheuntreatedstormwaterolunieCons/rue/to,,Siormipate,PollutionPieen/ionitus!2012121 storagepondwouldhaveastoragecomponentthroughthemedia,andanoverflowcomponentforwhenthefiltrationcapacityisexceeded.WWHMcanroutetherunofffromthepost-developedconditionthroughthetreatmentsystemsin4banddeterminecompliancewiththeflowdurationstandard.Thiswouldbeaniterativedesignprocedurewhereiftheinitialsizingestimatesforthetreatmentsystemprovedtobeinadequate,thedesignerwouldhavetomodifythesystemandroutetherunoffthroughitagain.Theiterationwouldcontinueuntilcompliancewiththeflowdurationstandardisachieved.5.Itshouldbenotedthattheaboveprocedureswouldbeusedtomeettheflowcontrolrequirements.Thefiltrationsystemmustbeabletomeettherunofftreatmentrequirements.ItislikelythatthedischargeflowrateofVzofthe2-yearormoremayexceedthetreatmentcapacityofthesystem.Ifthatisthecase,theuntreatedstormwaterdischargerate(s)(i.e..influenttothetreatmentsystem)mustbereducedtoallowpropertreatment.Anyreductionintheflowswouldlikelyresultintheneedforalargeruntreatedstormwaterstoragevolume.Ifsystemdesigndoesnotallowyoutodischargeattheslowerratesasdescribedaboveandifthesitehasaretentionordetentionpondthatwillservetheplanneddevelopment,thedischargefromthetreatmentsystemmaybedirectedtothepermanentretention/detentionpondtocomplywiththeflowcontrolrequirements.Inthiscase,theuntreatedstormwaterstoragepondandtreatmentsystemwillbesizedaccordingtothesizingcriteriaforflow-throughtreatmentsystemsforflowcontrolexemptwaterbodiesdescribedearlierexceptalldischarges(waterpassingthroughthetreatmentsystemandstornnvaterbypassingthetreatmentsystem)willbedirectedintothepermanentretention/detentionpond.Ifsiteconstraintsmakelocatingtheuntreatedstormwaterstorageponddifficult,thepermanentretention/detentionpondmaybedividedtoserveastheuntreatedstormwaterdischargepondandthepost-treatmentflowcontrolpond.Abermorbarriermustbeusedinthiscasesotheuntreatedwaterdoesnotmixwiththetreatedwater.Bothuntreatedstomiwaterstoragerequirements,andadequatepost-treatmentflowcontrolmustbeachieved.Thepost-treatmentflowcontrolpond’sreviseddimensionsmustbeenteredintotheWWIIMandtheWWIIMmustberuntoconfirmcompliancewiththeflowcontrolrequirement.oht;;wConstructionS!ornni’aterPollutionPieen/ionitus!2012122 BMPC252:HighpHNeutralizationUsingCO2PurposeWhenp1-Ilevelsinstormwaterriseabove8.5itisnecessarytolowerthep1-Ilevelstotheacceptablerangeof6.5to8.5,thisprocessiscalledpHneutralization.p1-Ineutralizationinvolvestheuseofsolidorcompressedcarbondioxidegasinwaterrequiringneutralization.NeutralizedstormwatermaybedischargedtosurfacewatersundertheGeneralConstructionNPDESpermit.NeutralizedprocesswatersuchasconcretetrucLwash-out.hydrodemolition,orsaw-cuttingslurrymustbemanagedtopreventdischargetosurfacewaters.Anystormwatercontaminatedduringconcreteworkisconsideredprocesswastewaterandmustnotbedischargedtosurfacewaters.RaonforHNraiaionApHlevelrangeof6.5to8.5istypicalformostnaturalwatercourses.andthisneutralpHisrequiredforthesurvivalofaquaticorganisms.ShouldthepHriscordropoutofthisrange,fishandotheraquaticorganismsmaybecomestressedandmaydie.CalciumhardnesscancontributetohighpHvaluesandcausetoxicitythatisassociatedwithhighpHconditions.Ahighlevelofcalciumhardnessinwatersofthestateisnotallowed.ThewaterqualitystandardforpHinWashingtonStateisintherangeof6.5to8.5.GroundwaterstandardforcalciumandoilierdissolvedsolidsinWashingtonStateislessthan500mg/I.(‘onditiousofUseCaofHiHHighpHatconstructionsitesismostcommonlycausedbythecontactofstormwaterwithpouredorrecycledconcrete,cement,mortars,andoilierPortlandcementorlimecontainingconstructionmaterials.(SeeBMPCl51:ConcreteHandlingformoreinformationonconcretehandlingprocedures).Theprincipalcausticagentincementiscalciumhydroxide(freelime).AdanaofCO2Sarin•Rapidlyneutralizeshighp11water.•Costeffectiveandsafertohandlethanacidcompounds.•CO2isself-buffering.ItisdifficulttooverdoseandcreateharmfullylowpHlcvcls.•Materialisreadilyavailable.ohuneCons/inc/ionS!onnii’a/erPollutionPreentioniitist201212 •TCiaProWhencarbondioxide(C02)isaddedtowater(H20),carbonicacid(H2C03)isformedwhichcanffirtherdissociateintoaproton(14+)andabicarbonateanion(HCOr)asshownbelow:C02±H20::H2C03:.‘H++HC03ThefreeprotonisaweakacidthatcanlowerthepH.Watertemperaturehasaneffectonthereactionaswell.Thecolderthewatertemperatureistheslowerthereactionoccursandthewarmerthewatertemperatureisthequickerthereactionoccurs.MostconstructionapplicationsinWashingtonStatehavewatertemperaturesinthe50°Forhigherrangesothereactionisalmostsimultaneous.DesignandTranProInstallationFlighp1-Iwatermaybetreatedusingcontinuoustreatment,continuousSpecificationsdischargesystems.Thesemanufacturedsystemscontinuouslymonitorinfluentandeffluentpl-ltoensurethatpHvaluesarewithinanacceptablerangebeforebeingdischarged.AllsystemsmusthavefailsafeautomaticshutoffswitchesintheeventthatpHisnotwithintheacceptabledischargerange.Onlytrainedoperatorsmayoperatemanufacturedsystems.Systemmanufacturersoftenprovidetrainedoperatorsortrainingontheirdevices.Thefollowingproceduremaybeusedwhennotusingacontinuousdischargesystem:1.Priortotreatment,theappropriatejurisdictionshouldbenotifiedinaccordancewiththeregulationssetbythejurisdiction.2.EveryeffortshouldbemadetoisolatethepotentialhighpHwaterinordertotreatitseparatelyfromotherstormwateron-site.3.Watershouldbestoredinanacceptablestoragefacility,detentionpond,orcontainmentcellpriortotreatment.4.Transferwatertobetreatedtothetreatmentstructure.Ensurethattreatmentstructuresizeissufficienttoholdtheamountofwaterthatistobetreated.Donotfilltankcompletely,allowatleast2feetoffreeboard.5.TheoperatorsamplesthewaterforpHandnotestheclarityofthewater.Asaruleofthumb.lessCO2isnecessaryforclearerwater.Thisinformationshouldberecorded.6.InthepHadjustmentstructure,addC02untilthepHfaLlsintherangeof6.9-7.1.RememberthatpHwaterqualitystandardsapplysoadjustingpHtowithin0.2pHunitsofreceivingwater(backgroundpH)isrecommended.ItisunlikelythatpHcanbeadjustedtowithin0.2pHunitsusingdryice.CompressedcarbondioxidegasshouldbeintroducedtothewaterusingacarbondioxidedilThserlocatednearolwncConstruclionS!oniiiiakrPollutionPieen/jot;itus!201212 thebottomofthetank,thiswillallowcarbondioxidetobubbleupthroughthewateranddifilisemoreevenly.7.Slowlydischargethewatermakingsurewaterdoesnotgetstinedupintheprocess.Releaseabout80%ofthewaterfromthestructureleavinganysludgebehind.8.Dischargetreatedwaterthroughapondordrainagesystem.9.Excesssludgeneedstobedisposedofproperlyasconcretewaste.IfseveralbatchesofwaterareundergoingpHtreatment,sludgecanbeleftintreatmentstructureforthenextbatchtreatment.Disposeofsludgewhenitfills50%oftankvolume.Sitesthatmustimplementflowcontrolforthedevelopedsitemustalsocontrolstormwaterreleaseratesduringconstruction.Alltreatedstormwatermustgothroughaflowcontrolfacilitybeforebeingreleasedtosurfacewaterswhichrequireflowcontrol.MaintenanceSafandManaHandinStandards•AllequipmentshouldbehandledinaccordancewahOSHArulesandregulations.•Followmanufacturerguidelinesformaterialshandling.oraorRordEachoperatorshouldprovide:•Adiagramofthemonitoringandtreatmentequipment.•Adescriptionofthepumpingratesandcapacitythetreatmentequipmentiscapableoftreating.Eachoperatorshouldkeepawrittenrecordofthefollowing:•Clientnameandphonenumber.•Dateoftreatment.•Weatherconditions.•Projectnameandlocation.•Volumeofwatertreated.•p1-1ofuntreatedwater.•AmountofCO2neededtoadjustwatertoap1-Irangeof6.9-7.1.•p11oftreatedwater.•Dischargepointlocationanddescription.Acopyofthisrecordshouldbegiventotheclient/contractorwhoshouldretaintherecordforthreeyears.ohinwConstrue/in,,SlorunvaterPollutionPieen/to,,iius/201212 BMPC253:pHControlforHighpHWaterPurposeWhenpHlevelsinstornnvaterriseabove8.5itisnecessarytolowerthepHlevelstotheacceptablerangeof6.5to8.5.thisprocessiscalledpHneutralization.Stormwaterwithp14levelsexceedingwaterqualitystandardsmaybetreatedbyinfiltration,dispersioninvegetationorcompost,pumpingtoasanitarysewer,disposalatapermittedconcretebatchplantwithpHneutralizationcapabilities,orcarbondioxidesparging.BMPC252givesguidelinesforcarbondioxidesparging.RaonforHNralalonApHlevelrangeof6.5to8.5istypicalformostnaturalwatercourses,andthispHrangeisrequiredforthesurvivalofaquaticorganisms.Shouldthep1-Iriseordropoutofthisrange,fishandotheraquaticorganismsmaybecomestressedandmaydie.condiriojisofUseCaofIIIHHighpHlevelsatconstructionsitesaremostcommonlycausedbythecontactofstormwaterwithpouredorrecycledconcrete,cement,mortars,andotherPortlandcementorlimecontainingconstructionmaterials.(SeeBMPCl51:ConcreteHandlimzformoreinformationonconcretehandlingprocedures).Theprincipalcausticagentincementiscalciumhydroxide(freelime).DesignandDioaModInstallationTnfiraionSpecifications•Infiltrationisonlyallowedifsoiltypeallowsallwatertoinfiltrate(nosurfacerunoff)withoutcausingorcontributingtoaviolationofsurfaceorgroundwaterqualitystandards.•InfiltrationtechniquesshouldbeconsistentwithVolumeV,Chapter7DinonUseBMPT5.30FullDispersionSaniarSrDioa•Localsewerauthorityapprovalisrequiredpriortodisposalviathesanitarysewer.ConnBaPanDioa•OnlypermittedfacilitiesmayaccepthighpHwater.•FacilityshouldbecontactedbeforetreatmenttoensuretheycanacceptthehighpHwater.SotarDiarAnypHtreatmentoptionsthatgeneratetreatedwaterthatmustbedischargedoffsitearesubjecttoflowcontrolrequirements.SitesthatmustimplementflowcontrolforthedevelopedsitemustalsocontrolohitneConstructionStonnii’atcrPollutionPreentionitact201212 storrnwaterreleaseratesduringconstruction.Alltreatedstormwatermustgothroughaflowcontrolfacilitybeforebeingreleasedtosurfacewaterswhichrequireflowcontrol.ohiuwConstructionStonn;:’aterPothitionPreeu/iouitits!201212 AppendixCCorrespondenceConstructionstormwaterisnotanticipatedtoleavethesiteatanytimeduringconstruction.Ifstormwateristobedischarged,atanypointduringconstruction,aNPDESpermitshallbeappliedforimmediately.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageC-i AppendixDSiteInspectionFormTheresultsofeachinspectionshallbesummarizedinaninspectionreportorchecklistthatisenteredintoorattachedtothesitelogbook.Itissuggestedthattheinspectionreportorchecklistbeincludedinthisappendixtokeepmonitoringandinspectioninformationinonedocument,butthisisoptional.However,itismandatorythatthisSWPPPandthesiteinspectionformsbekeptonsiteatalltimesduringconstruction,andthatinspectionsbeperformedanddocumentedasoutlinedbelow.Ataminimum,eachinspectionreportorchecklistshallinclude:Inspectiondate/timesWeatherinformation:generalconditionsduringinspection,approximateamountofprecipitationsincethelastinspection,andapproximateamountofprecipitationwithinthelast24hours.AsummaryorlistofallBMPsthathavebeenimplemented,includingobservationsofallerosion/sedimentcontrolstructuresorpractices.Thefollowingshallbenoted:locationsofBMPsinspected,locationsofEMPsthatneedmaintenance,thereasonmaintenanceisneeded,locationsofBMPsthatfailedtooperateasdesignedorintended,andlocationswhereadditionalordifferentBMPsareneeded,andthereason(s)whyAdescriptionofstormwaterdischargedfromthesite.Thepresenceofsuspendedsediment,turbidwater,discoloration,and/oroilsheenshallbenoted,asapplicable.Adescriptionofanywaterqualitymonitoringperformedduringinspection,andtheresultsofthatmonitoring.Generalcommentsandnotes,includingabriefdescriptionofanyBMPrepairs,maintenanceorinstallationsmadeasaresultoftheinspection.Astatementthat,inthejudgmentofthepersonconductingthesiteinspection,thesiteiseitherincomplianceoroutofcompliancewiththetermsandconditionsoftheSWPPPandtheNPDESpermit.Ifthesiteinspectionindicatesthatthesiteisoutofcompliance,theinspectionreportshallincludeasummaryoftheremedialactionsrequiredtobringthesitebackintocompliance,aswellasascheduleofimplementation.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageD-1 Name,title,andsignatureofpersonconductingthesiteinspection;andthefollowingstatement:1certifyunderpenaltyoflawthatthisreportistrue,accurate,andcomplete,tothebestofmyknowledgeandbelier.WhenthesiteinspectionindicatesthatthesiteisnotincompliancewithanytermsandconditionsoftheNPDESpermit,thePermitteeshalltakeimmediateaction(s)to:stop,contain,andcleanuptheunauthorizeddischarges,orotherwisestopthenoncompliance;correcttheproblem(s);implementappropriateBestManagementPractices(BMPs),and/orconductmaintenanceofexistingBMPs;andachievecompliancewithallapplicablestandardsandpermitconditions.Inaddition,ifthenoncompliancecausesathreattohumanhealthortheenvironment,thePermitteeshallcomplywiththeNoncomplianceNotificationrequirementsinSpecialConditionS5.Fofthepermit.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageD-2 ConstructionStormwaterSiteInspectionForm—roJectNamePermit4:Date:Time:NameofCertifiedErosionSedimentControlLead(CESCL)orqualifiedinspectoriflessthanoneacrePrintName:Approximaterainfallamountsincethelastinspection(ininches):_________________________________________Approximaterainfallamountinthelast24hours(ininches):______________________________________CurrentWeatherClearDCloudyDMistRainWindDFogDA.Typeofinspection:WeeklyDPostStormEventOtherDB.Pha5eofActiveConstruction(checkallthatapply):PreConstruction/installationoferosion/sedimentcontrolsClearing/Demo/GradingInfrastructure/storm/roadsConcretepoursVerticalConstruction/buildingsUtilitiesOIfsiteimprovementsSitetemporarystabilizedFinalstabilizationC.Questions:(Wereallareasofconstructionanddischargepointsinspected?Yes—No—2.Didyouobservethepresenceofsuspendedsediment,turbidity,discoloration,oroilsheenYes—No—3.Wasawaterqualitysampletakenduringinspection?(refertopermitconditions54&55)Yes—No4.Wasthereaturbiddischarge250NTUorgreater,orTransparency6cmorless?*Yes—No—5.Ifyesto#4wasitreportedtoEcology?Yes—No—6.IspHsamplingrequired?pHrangerequiredis6.5to83.YesNo—Ifansweringyestoadischarge,describetheevent.Includewhen,where,andwhyithappened;whatactionwastaken,andwhen.*Ifansweringyesto#4recordNTU/Transparencywithcontinualsamplingdailyuntilturbidityis25NTUorless?transparencyis33cmorgreater.SamplingResults:Date:ParameterMethod(circleone)ResultOther/NoteNTUcmpHTurbiditytube,meter,laboratorypHPaper,kit,meterDR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageD-3 ConstructionStormwaterSiteInspectionFormChecktheobservedstatusofallitems.Provide“ActionRequired“detailsanddates.Element#InspectionBMPsBMPneedsBMPActionrequiredInspectedmaintenancefailed(describein5sectionF)aBeforebeginninglanddisturbingClearingactivitiesareallclearinglimits,naturalLimitsresourceareas(streams,wetlands,buffers,trees)protectedwithbarriersorsimilarBMPs?(highvisibilityrecommended)2ConstructionaccessisstabilizedwithConstructionquarryspaNsorequivalentBMPtoAccesspreventsedimentfrombeingtrackedontoroads?Sedimenttrackedontotheroadwaywascleanedthoroughlyattheendofthedayormorefrequentasnecessary.3AreflowcontrolmeasuresinstalledtoControlFlowcontrolstormwatervolumesandRatesvelocityduringconstructionanddotheyprotectdownstreampropertiesandwaterwaysfromerosion?Ifpermanentinfiltrationpondsareusedforflowcontrolduringconstruction,aretheyprotectedfromsiltation?4Allperimetersedimentcontrols(e.g.Sedimentsiltfence,wattles,compostsocks,Controlsberms,etc.)installed,andmaintainedinaccordancewiththeStormwaterPollutionPreventionPlan(SWPPP).SedimentcontrolBMPs(sedimentponds,traps,filtersetc.)havebeenconstructedandfunctionalasthefirststep_ofgrading.StormwaterrunofffromdisturbedareasisdirectedtosedimentremovalBMP.SHaveexposedun-workedsoilsbeenStabilizeSoilsstabilizedwitheffectiveBMPtopreventerosionandsedimentdeposition?Arestockpilesstabilizedfromerosion,protectedwithsedimenttrappingmeasuresandlocatedawayfromdraininlet,waterways,anddrainagechannels?Havesoilsbeenstabilizedattheendoftheshift,beforeaholidayorweekendifneededbasedontheweatherforecast?DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageD4 ConstructionStormwaterSiteInspectionFormElementSInspectionBMPsInspectedBMPneedsBMPActionrequired—maintenancefailed(describeinyesnon/asectionF)6HasstormwaterandgroundwaterProtectbeendivertedawayfromslopesandSlopesdisturbedareaswithinterceptordikes,pipesandorswales?Isoff-sitestormwatermanagedseparatelyfromstormwatergeneratedonthesite?Isexcavatedmaterialplacedonuphillsideoftrenchesconsistentwithsafetyandspaceconsiderations?Havecheckdamsbeenplacedatregularintervalswithinconstructedchannelsthatarecutdownaslope?7Stormdraininletsmadeoperable—DrainInletsduringconstructionareprotected.—Areexistingstormdrainswithintheinfluenceoftheprojectprotected?SHaveallon-siteconveyancechannelsStabilizebeendesigned)constructedandChannelandstabilizedtopreventerosionfromOutletsexpectedpeakflows?Isstabilization,includingarmoringmaterial,adequatetopreventerosionofoutlets,adjacentstreambanks,slopesanddownstreamconveyancesystems?9ArewastematerialsanddemolitionControldebrishandledanddisposedoftoPollutantspreventcontaminationofstormwater?—Hascoverbeenprovidedforallchemicals,liquidproducts,petroleumproducts,andothermaterial?Hassecondarycontainmentbeenprovidedcapableofcontaining110%ofthevolume?Werecontaminatedsurfacescleanedimmediately_after_a_spill_incident?WereBMPsusedtopreventcontaminationofstormwaterbyapHmodifying_sources?Wheelwashwastewaterishandledanddisposedofproperly.10Concretewashoutindesignatedareas.ControlNowashoutorexcessconcreteontheDewateringground.DewateringhasbeendonetoanapprovedsourceandincompliancewiththeSWPPP.Werethereanycleannonturbid____ ___ __ _ __dewateringdischarges?D.R.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageD-5 ConstructionStormwaterSiteInspectionFormE.Checkallareasthathavebeeninspected.v’AllinplaceBMPsAlldischargelocationsAlldisturbedsoilsAllmaterialstorageareasDAllconcretewashoutareasDAllequipmentstorageareasDDAllconstructionentrances/exitsF.Elementschecked“ActionRequired”(sectionD)describecorrectiveactiontobetaken.Listtheelementnumber;bespecificonlocationandworkneeded.Documentinitial,anddatewhenthecorrectiveactionhasbeencompleted‘pdinspected.ElementDescriptionandLocationActionRequiredCompletionInitials#DateAttachadditionalpageifneededSignthefollowingcertification:“1certifythatthisreportistrue,accurate,andcomplete,tothebestofmyknowledgeandbelier’Inspectedby:PrintTitle/QualificationofInspectorSignatureDateDR.STRONGConsultingEngineers,Inc.StormwaterPollutionPreventionPlanAlpineNurseryElement#InspectionBMPsInspectedBMPneedsBMPActionrequiredyesnon/amaintenancefailed(describeinsectionF)11ArealltemporaryandpermanentMaintainerosionandsedimentcontrolBMPsBMPmaintainedtoperformasintended?12Hastheprojectbeenphasedtothe—Managethemaximumdegreepracticable?ProjectHasregularinspection,monitoringand——maintenancebeenperformedasrequired_bythe_permit?HastheSWPPPbeenupdated,implementedandrecordsmaintained?PageD-6 AppendixEConstructionStormwaterGeneralPermit(CSWGP)DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageF-2 IssuanceDate:December1,2010EffectiveDate:January1,2011ExpirationDate:December31,2015CONSTRUCTIONSTORMWATERGENERALPERMITNationalPoliptantDischargeEliminationSystem(NPDES)andStateWasteDischargeGeneral•PermitforStormwaterDischargesAssociatedwithConstructionActivity•StateofWashingtonDepartmentofEcologyOlympia,Washington98504IncompliancewiththeprovisionsofChapter90.48RevisedCodeofWashington(StateofWashingtonWaterPollutionControlAct)andTitle33UnitedStatesCode,Section1251etseq.TheFederalWaterPollutionControlAct(TheCleanWaterAct)Untilthispermitexpires,ismodifiedorrevoked,Permitteesthathaveproperlyobtainedcoverageunderthisgeneralpermitareauthorizedtodischargein-accordancewiththespecialandgeneralconditionsthatfollow.VKcJW’Susewind,PiE.,P.G./WaterQualityProgramManagerWashingtonStateDepartmentofEcology TABLEOFCONTENTSLISTOFTABLES.3SPECIALCONDITIONS5SI.PERMITCOVERAGE5S2.APPLICATIONREQUIREMENTS853.COMPLIANCEWITHSTANDARDS11S4.MONITORINGREQUIREMENTS12S5.REPORTINGANDRECORDKEEPINGREQUIREMENTS19S6.PERMITFEES22S7.SOLIDANDLIQUIDWASTEDISPOSAL22S8.DISCHARGESTO303(D)ORTMDLWATERBODIES22S9.STORMWATERPOLLUTIONPREVENTIONPLAN26Sb.NOTICEOFTERMINATION34GENERALCONDITIONS36GI.DISCHARGEVIOLATIONS36G2.SIGNATORYREQUIREMENTS36G3.RIGHTOFINSPECTIONANDENTRY37G4.GENERALPERMITMODIFICATIONANDREVOCATION37G5.REVOCATIONOFCOVERAGEUNDERTHEPERMIT37G6.REPORTINGACAUSEFORMODIFICATION38G7.COMPLIANCEWITHOTHERLAWSANDSTATUTES3808.DUTYTOREAPPLY38G9.TRANSFEROFGENERALPERMITCOVERAGE39Gb.REMOVEDSUBSTANCES39GIl.DUTYTOPROVIDEINFORMATION39G12.OTHERREQUIREMENTSOF40CFR39G13.ADDITIONALMONITORING39014.PENALTIESFORVIOLATINGPERMITCONDITIONS40015.UPSET40ConsiructionStomnni’aterGeneralPermit—December1,2010Page2 .G16.PROPERTYRIGHTS.40G17.DUTYTOCOMPLY40G18.TOXICPOLLUTANTS41GI9.PENALTIESFORTAMPERING41G20.REPORTINGPLANNEDCHANGES41G21.REPORTINGOTHERINFORMATION42G22.REPORTINGANTICIPATEDNON-COMPLIANCE42G23.REQUESTSTOBEEXCLUDEDFROMCOVERAGEUNDERTHEPERMIT42G24.APPEALS42G25.SEVERABILITY43G26.BYPASSPROHIBITED43APPENDIXA-DEFINITIONS46APPENDIXB-ACRONYMS54LISTOFTABLESTableI.SummaryofPermitReportSubmittals4Table2.SummaryofRequiredOn-siteDocumentation4Table3.SummaryofPrimaryMonitoringRequirements12Table4.MonitoringandReportingRequirements16Table5.Turbidity,FineSediment&PhosphorusSamplingandLimitsfor303(d)-Listed...24Table6.pHSamplingandLimitsfor303(d)-ListedWaters24ConstructionStonnii’aterGeneralPermitDecember1,2010Page3 SUMMARYOFPERMITREPORTSUBMITTALSRefertotheSpecialandGeneralConditionswithinthispermitforadditionalsubmittalrequirements.AppendixAprovidesalistofdefinitions.AppendixBprovidesalistofacronyms.Table1.SummaryofPermitReportSubmittalsPermitSubmittalFrequencyFirstSubmittalDateSectionS5.AandHighTurbidity/TransparencyPhoneAsNecessaryWithin24hoursS8ReportingS5.BDischargeMonitoringReportMonthly*Within15daysofapplicablemonitoringperiod55.FandNoncomplianceNotificationAsnecessaryImmediately68S5.FNoncomplianceNotification—AsnecessaryWithin5DaysofnonWrittenReportcomplianceG2.NoticeofChangeinAuthorizationAsnecessaryGO.PermitApplicationforSubstantiveAsnecessaryChangestotheDischargeGe.ApplicationforPermitRenewal1/permitcycleNolaterthan180daysbeforeexpirationG9.NoticeofPermitTransferAsnecessaryG20.NoticeofPlannedChangesAsnecessaryG22.ReportingAnticipatedNon-AsnecessarycomplianceSPECIALNOTE:*PenjtteesmustsubmitDischargeMonitoringReports(DMRs)totheWashingtonStateDepartmentofEcologymonthly,regardlessofsitedischarge,forthefulldurationofpermitcoverage.RefertoSectionSIBofthisGeneralPermitformorespecificinformationregardingDMRs.Table2.SummaryofRequiredOn-siteDocumentationDocumentTitlePermitConditionsPermitCoverageLetterSeeConditionsS2,S5ConstructionStormwaterGeneralPermitSeeConditions52,55SiteLogBookSeeConditionsS4,55StormwaterPollutionPreventionPlan(SWPPP)SeeConditionsS9,S5ConstructionSlonnii’aterGenera!PennitDecember1,2010Page4 SPECIALCONDITIONSSI.PERMITCOVERAGEA.PermitAreaThisConstructionStormwaterGeneralPermit(CSWGP)coversallareasofWashingtonState,exceptforfederalandTriballandsasspecifiedinSpecialConditionSl.E.3.B.OperatorsRequiredtoSeekCoverateUnderthisGeneralPermit:OperatorsofthefollowingconstructionactivitiesarerequiredtoseekcoverageunderthisCSWGP:a.Clearing,gradingand/orexcavationthatresultsinthedisturbanceofoneormoreacresanddischargesstormwatertosurfacewatersoftheState;andclearing,gradingand/orexcavationonsitessmallerthanoneacrethatarepartofalargercommonplanofdevelopmentorsale,ifthecommonplanofdevelopmentorsalewillultimatelydisturboneacreormoreanddischargestormwatertosurfacewatersoftheState.i.Thisincludesforestpractices(including,butnotlimitedto,classIVconversions)thatarepartofaconstructionactivitythatwillresultinthedisturbanceofoneornioreacres,anddischargetosurfacewatersoftheState(thatis,forestpracticesthatprepareasiteforconstructionactivities);andb.AnysizeconstructionactivitydischargingstormwatertowatersoftheStatethattheDepartmentofEcology(“Ecology”):i.DeterminestobeasignificantcontributorofpollutantstowatersoftheStateofWashington.ii.Reasonablyexpectstocauseaviolationofanywaterqualitystandard.2.OperatorsofthefollowingactivitiesarenotrequiredtoseekcoverageunderthisCSWGP(unlessspecificallyrequiredunderSpecia’ConditionSI.Bi.b.above):a.Constructionactivitiesthatdischargeallstormwaterandnon-stormwatertogroundwater,sanitarysewer,orcombinedsewer,andhavenopointsourcedischargetoeithersurfacewaterorastormsewersystemthatdrainstosurfacewatersoftheState.b.ConstructionactivitiescoveredunderanErosivityWaiver(SpecialConditionS2.C).c.Routinemaintenancethatisperformedtomaintaintheoriginallineandgrade,hydrauliccapacity,ororiginalpurposeofafacility.ConstructionStor,nii’aterGeneralPermitDecenther12010Page5 C.AuthorizedDischarges:StormwaterAssociatedwithConstructionActiviw.Subjecttocompliancewiththetermsandconditionsofthispermit,PermitteesareauthorizedtodischargestormwaterassociatedwithconstructionactivitytosurfacewatersoftheStateortoastormsewersystemthatdrainstosurface‘watersoftheState.(Notethat“surfacewatersoftheState”mayexistonaconstructionsiteaswellasoffsite;forexample,acreekrunningthroughasite.)2.StorrnwaterAssociatedwithConstructionSupportActivity.Thispermitalsoauthorizesstormwaterdischargefromsupportactivitiesrelatedtothepermittedconstructionsite(forexample,anon-siteportablerockcrusher,off-siteequipmentstagingyards,materialstorageareas,borrowareas,etc.)provided:a.ThesupportactivityrelatesdirectlytothepermittedconstructionsitethatisrequiredtohaveaNPDESpermit;andb.Thesupportactivityisnotacommercialoperationservingmultipleunrelatedconstructionprojects,anddoesnotoperatebeyondthecompletionoftheconstructionactivity;ande.AppropriatecontrolsandmeasuresareidentifiedintheStormwaterPollutionPreventionPlan(SWPPP)forthedischargesfromthesupportactivityareas.3.Non-StormwaterDischarges.Thecategoriesandsourcesofnon-stormwaterdischargesidentifiedbelowareauthorizedconditionally,providedthedischargeisconsistentwiththetermsandconditionsofthispermit:a.Dischargesfromfire-fightingactivities.b.Firehydrantsystemflushing.c.Potablewater,includinguncontaminatedwaterlineflushing.d.Pipelinehydrostatictestwater.e.Uncontaminatedairconditioningorcompressorcondensate.1’.Uncontaminatedgroundwaterorspringwater.g.Uncontaminatedexcavationdewatedngwater(inaccordancewith59.D.lO).h.Uncontaminateddischargesfromfoundationorfootingdrains.i.Waterusedtocontroldust.Permitteesmustminimizetheamountofdustcontrolwaterused.j.Routineexternalbuildingwashdownthatdoesnotusedetergents.k.Landscapeirrigationwater.TheSWPPPmustadequatelyaddressallauthorizednon-stormwaterdischarges,exceptfordischargesfromfire-fightingactivities,andmustcomplywithSpecialConstructionStornn:’aterGeneralPermitDecember1,2010Page6 Condition53.Ataminimum,dischargesfrompotablewater(includingwaterlineflushing),firehydrantsystemflushing,andpipelinehydrostaticlestwatermustundergothefollowing:dechlorinationtoaconcentrationof0.1partspermillion(ppm)orless,andp1-Iadjustmenttowithin6.5—8.5standardunits(su),ifnecessary.D.ProhibitedDischarges:ThefollowingdischargestowatersoftheState,includinggroundwater,areprohibited.1.Concretewastewater.2.Wastewaterfromwashoutandclean-upofstucco,paint,formreleaseoils,curingcompoundsandotherconstructionmaterials.3.Processwastewaterasdefinedby40CodeofFederalRegulations(CFR)122.1(seeAppendixAofthispermit).4.Slurrymaterialsandwastefromshaftdrilling.5.Fuels,oils.orotherpollutantsusedinvehicleandequipmentoperationandmaintenance.6.Soapsorsolventsusedinvehicleandequipmentwashing.7.Wheelwashwastewater,unlessdischargedaccordingtoSpecialConditionS9.D.9.d.8.Dischargesfromdewateringactivities,includingdischargesfromdewatedngoftrenchesandexcavations,unlessmanagedaccordingtoSpecialConditionS9.D.10.B.LimitsonCoveraueEcologymayrequireanydischargertoapplyforandobtaincoverageunderanindividualpermitoranothermorespecificgeneralpermit.SuchalternativecoveragewillberequiredwhenEcologydeterminesthatthisCSWGPdoesnotprovideadequateassurancethatwaterqualitywillbeprotected,orthereisareasonablepotentialfortheprojecttocauseorcontributetoaviolationofwaterqualitystandards.Thefollowingstormwaterdischargesarenotcoveredbythispermit:1.Post-constructionstormwaterdischargesthatoriginatefromthesiteaftercompletionofconstructionactivitiesandthesitehasundergonefinalstabilization.2.Non-pointsourcesilviculturalactivitiessuchasnurseryoperations,sitepreparation,reforestationandsubsequentculturaltreatment,thinning,prescribedburning,pestandfirecontrol,harvestingoperations,surfacedrainage,orroadconstructionandmaintenance,fromwhichthereisnaturalrunoffasexcludedin40CFRSubpart122.3.StonrnvaterfromanyfederalprojectorprojectonfederallandorlandwithinanIndianReservationexceptforthePuyallupReservation.WithinthePuyallupConstructionStornni’aterGeneralPermitDecember1,2010Page7 Reservation,anyprojectthatdischargestosurfacewateronlandheldintrustbythefederalgovernmentmaybecoveredbythispermit.4.StormwaterfromanysitecoveredunderanexistingNPDESindividualpermitinwhichstormwatermanagementand/ortreatmentrequirementsareincludedforallstormwaterdischargesassociatedwithconstructionactivity.5.StormwaterfromasitewhereanapplicableTotalMaximumDailyLoad(TMDL)requirementspecificallyprecludesorprohibitsdischargesfromconstructionactivity.S2.APPLICATIONREQUIREMENTSA.PermitApplicationFormsNoticeofIntentForm/Tirnelinea.Operatorsofneworpreviouslyunpermittedconstructionactivitiesmustsubmitacompleteandaccuratepermitapplication(NoticeofIntent,orNOl)toEcology.b.TheoperatormustsubmittheNOlatleast60daysbeforedischargingstormwaterfromconstructionactivitiesandmustsubmititonorbeforethedateofthefirstpublicnotice(seeSpecialConditionS2.Bbelovfordetails).The30-daypubliccommentperiodrequiredbyWAC173-226-130(5)beginsonthepublicationdateofthesecondpublicnotice.UnlessEcologyrespondstothecompleteapplicationinwriting,basedonpubliccomments,oranyotherrelevantfactors,coverageunderthegeneralpermitwililautomaticallycommenceonthethirty-firstdayfollowingreceiptbyEcologyofacompletedNOl,ortheissuancedateofthispermit,whicheverislater,unlessEcologyspecifiesalaterdateinwriting.c.ApplicantswhoproposelodischargetoastormorsewersystemoperatedbySeattle,KingCounty,SnohomishCounty,Tacoma,PierceCounty,orClarkCountymustalsosubmitacopyoftheNOltotheappropriatejurisdiction.d.IfanapplicantintendstouseaBestManagementPractice(BMP)selectedonthebasisofSpecialConditionS9.C.4(“demonstrablyequivalent”BMPs),theapplicantmustnotifyEcologyofitsselectionaspartoftheNOl.IntheeventtheapplicantselectsBMPsaftersubmissionoftheNOl,itmustprovidenoticeoftheselectionofanequivalentBMPtoEcologyatleast60daysbeforeintendeduseoftheequivalentBMP.e.PermitteesmustnotifyEcologyregardinganychangestotheinformationprovidedontheNOIbysubmittinganupdatedNOl.Examplesofsuchchangesinclude,butarenotlimitedto,i.changestothePermittee’smailingaddress,ii.changestotheon-sitecontactpersoninformation,andConstructionStornn,’aterGeneralPennitDecenther1,2010Page8 iii.changestothearea/acreageaffectedbyconstructionactivity.2.TransferofCoveraueFormThePermitteecantransfercurrentcoverageunderthispermittooneormorenewoperators,includingoperatorsofsiteswithinaCommonPlanofDevelopment,providedthePermineesubmitsaTransferofCoverageForminaccordancewithGeneralConditionG9.Transfersdonotrequirepublicnotice.B.PublicNoticeForneworpreviouslyunpermittedconstructionactivities,theapplicantmustpublishapublicnoticeatleastonetimeeachweekfortwoconsecutiveweeks,atleast7daysapart,inanewspaperwithgeneralcirculationinthecountywheretheconstructionistotakeplace.Thenoticemustcontain:I.Astatementthat“TheapplicantisseekingcoverageundertheWashingtonStateDepartmentofEcology’sConstructionStormwaterNPDESandStateWasteDischargeGeneralPermit.”2.Thename,addressandlocationoftheconstructionsite.3.Thenameandaddressoftheapplicant.4.Thetypeofconstructionactivitythatwillresultinadischarge(forexample,residentialconstruction,commercialconstruction,etc.),andthenumberofacrestobedisturbed.5.Thenameofthereceivingwater(s)(thatis,thesurfacewater(s)towhichthesitewilldischarge),or,ifthedischargeisthroughastormsewersystem,thenameoftheoperatorofthesystem.6.Thestatement:“AnypersonsdesiringtopresenttheirviewstotheWashingtonStateDepartmentofEcologyregardingthisapplication,orinterestedinEcology’sactiononthisapplication,maynotifyEcologyinwritingnolaterthan30daysofthelastdateofpublicationofthisnotice.Ecologyreviewspubliccommentsandconsiderswhetherdischargesfromthisprojectwouldcauseameasurablechangeinreceivingwaterquality,and,ifso,whethertheprojectisnecessaryandintheoverridingpublicinterestaccordingtoTierIIantidegradationrequirementsunderWAC173-201A-320.Commentscanbesubmittedto:DepartmentofEcology,P.O.Box47696,Olympia,WA98504-7696Attn:\VaterQualityProgram.ConstructionStormwater”ConstructionStormwaterGeneralPermitDecember1,2010Page9 C.ErosivilyWaiverConstructionsiteoperatorsmayqualifyforanerosivitywaiverfromtheCSWGPifthefollowingconditionsaremet:Thesitewillresultinthedisturbanceoffewerthan5acresandthesiteisnotaportionofacommonplanofdevelopmentorsalethatwilldisturb5acresorgreater.2.CalculationofErosivity“R”FactorandRegionalTimeframe:a.Theproject’srainfallerosivityfactorC’R”Factor)mustbelessthan5duringtheperiodofconstructionactivity,ascalculatedusingeithertheTexasA&MUniversityonlinerainfallerosivitycalculatorat:http://ei.tamu.edu!orEPA’scalculatorathttp://cfpub.epa.izov/npdes!stormwater/lew/lewcalculator.cfm.Theperiodofconstructionactivitystartswhenthelandisfirstdisturbedandendswithfinalstabilization.Inaddition:b.Theentireperiodofconstructionactivitymustfallwithinthefollowingtimeframes:I.ForsiteswestoftheCascadesCrest:June15—September15.ii.ForsiteseastoftheCascadesCrest,excludingtheCentralBasin:June15—October15.iii.ForsiteseastoftheCascadesCrest,withintheCentralBasin:noadditionaltimeframerestrictionsapply.TheCentralBasinisdefinedastheportionsofEasternWashingtonwithmeanannualprecipitationoflessthan12inches.ForamapoftheCentralBasin(Region2),refertohttp://www.ecv.wa.eov/pubs/ecv070202.pdf.3.ConstructionsiteoperatorsmustsubmitacompleteErosivityWaivercertificationformatleastoneweekbeforedisturbingtheland.Certificationmustincludestatementsthattheoperatorwill:a.Complywithapplicablelocalstormwaterrequirements;andb.ImplementappropriateerosionandsedimentcontrolBMPstopreventviolationsofwaterqualitystandards.4.ThiswaiverisnotavailableforfacilitiesdeclaredsignificantcontributorsofpollutantsasdefinedinSpecialConditionS1.B.1.b.5.ThiswaiverdoesnotapplytoconstructionactivitieswhichincludenonstormwaterdischargeslistedinSpecialConditionS1.C.3.6.Ifconstructionactivityextendsbeyondthecertifiedwaiverperiodforanyreason,theoperatormusteither:a.Recalculatetherainfallerosivity“R”factorusingtheoriginalstartdateandanewprojectedendingdateand,ifthe“R”factorisstillunder5nçjtheentireConstructionStwwni’aterGeneralPermit—December1,2010Page10 projectfallswithintheapplicableregionaltimeframeinSpecialConditionS2.C.2.b,completeandsubmitanamendedwaivercertificationformbeforetheoriginalwaiverexpires;orb.SubmitacompletepermitapplicationtoEcologyinaccordancewithSpecialConditionS2.AandBbeforetheendofthecertifiedwaiverperiod.53.COMPLIANCEWITHSTANDARDSA.Dischargesmustnotcauseorcontributetoaviolationofsurfacewaterqualitystandards(Chapter173-20IAWAC),groundwaterqualitystandards(Chapter173-200WAC),sedimentmanagementstandards(Chapter173-204WAC),andhumanhealth-basedcriteriaintheNationalToxicsRule(40CFRPart131.36).Dischargesnotincompliancewiththesestandardsarenotauthorized.B.Priortothedischargeofstormwaterandnon-stormwatertowatersoftheState,thePermitteemustapplyallknown,available,andreasonablemethodsofprevention,control,andtreatment(AKART).ThisincludesthepreparationandimplementationofanadequateStormwaterPollutionPreventionPlan(SWPPP).withallappropriateBMPsinstalledmidmaintainedinaccordancewiththeSWPPPandthetermsandconditionsofthispermit.C.EcologypresumesthataPermitteecomplieswithwaterqualitystandardsunlessdischargemonitoringdataorothersite-specificinformationdemonstratesthatadischargecausesorcontributestoaviolationofwaterqualitystandards,whenthePermitteecomplieswiththefollowingconditions.ThePermitteemusthilly:I.Complywithallpermitconditions,includingplanning,sampling,monitoring,reporting,andrecordkeepingconditions.2.ImplementstormwaterBMPscontainedinstormwatermanagementmanualspublishedorapprovedbyEcology,orBMPsthataredemonstrablyequivalenttoBMPscontainedinstormwatertechnicalmanualspublishedorapprovedbyEcology,includingtheproperselection,implementation,andmaintenanceofallapplicableandappropriateBMPsforon-sitepollutioncontrol.(Forpurposesofthissection,thestormwatermanualslistedinAppendix10ofthePhaseIMunicipalStomiwaterPermitareapprovedbyEcology.)D.Whereconstructionsitesalsodischargetogroundwater,thegroundwaterdischargesmustalsomeetthetermsandconditionsofthisCSWGP.PermitteeswhodischargetogroundwaterthroughaninjectionwellmustalsocomplywithanyapplicablerequirementsoftheUndergroundInjectionControl(UIC)regulations,Chapter173-218WAC.ConstructionStonmi’atcrGenetalPermit—Decenther1,2010Page11 54.MONITORINGREQUIREMENTS,BENCHMARKSANDREPORTINGTRIGGERSTable3.SummaryofPrimaryMonitoringRequirementsSizeofSoilWeeklySiteWeeklyWeeklyWeeklypHRequiresDisturbance1InspectionsSamplingwISamplingWISampling2CESCLTurbidityTransparencyCertification?MeterTubeSitesthatdisturbRequiredNotRequiredNotRequiredNotRequiredNolessthanIacre,butarepartofalargerCommonPlanofDevelopmentSitesthatdisturb1RequiredSamplingReciuired—RequiredYesacreormore,buteithermethodfewerthan5acresSitesthatdisturbSRequiredRequiredJNotRequiredRequiredYesacresormoreA.SiteLoBookThePermitteemustmaintainasitelogbookthatcontainsarecordoftheimplementationoftheSWPPPandotherpermitrequirements,includingtheinstallationandmaintenanceofBMPs.siteinspections,andstormwatermonitoring.B.SiteInspectionsThePermittee’s(operator’s)siteinspectionsmustincludeallareasdisturbedbyconstructionactivities,allBMPs,andallstormwaterdischargepoints.(SeeSpecialConditionsS4.B.3andB.4belowfordetailedrequirementsofthePermittee’sCertifiedErosionandSedimentControlLead[CESCLJ).Soildisturbanceiscalculatedbyaddingtogetherallareasaffectedbyconstructionactivity.Constructionactivitymeansclearine.grading,excavation,andanyotheractivitythatdisturbsthesurfaceoftheland,includingingress/egressfromthesite.2IfconstructionactivityresultsinthedisturbanceofIacreormore,andinvolvessignificantconcretework(1,000cubicyardsofpouredorrecycledconcreteoverthelifeofaproject)ortheuseofengineeredsoils(soilamendmentsincludingbutnotlimitedtoPortlandcement-treatedbase[CTB],cementkilndust[CKD],orflyash),andstormwaterfromtheaffectedareadrainstosurfacewatersoftheStateortoastormsewerstormwatercollectionsystemthatdrainstoothersurfacewatersoftheState,thePermitteemustconductp11monitoringsamplinginaccordancewithSpecialConditionS4.D.Siteswithoneormoreacres,butfewerthan5acresofsoildisturbance,mustconductturbidityortransparencysamplinginaccordancewithSpecialCondition54.C.Sitesequaltoorgreaterthan5acresofsoildisturbancemustconductturbiditysamplingusingaturbiditymeterinaccordancewithSpecialConditionS4.C.ConstructionSionnwaterGeneralPermitDecenther1,2010Page12 ConstructionsitesoneacreorlargerthatdischargestormwatertosurfacewatersoftheStatemusthavesiteinspectionsconductedbyacertifiedCESCL.SiteslessthanoneacremayhaveapersonwithoutCESCLcertificationconductinspections;samplingisnotrequiredonsitesthatdisturblessthananacre.ThePermitteemustexaminestormwatervisuallyforthepresenceofsuspendedsediment,turbidity,discoloration,andoilsheen.ThePermitteemustevaluatetheeffectivenessofBMPsanddetermineifitisnecessarytoinstall,maintain,orrepairBMPstoimprovethequalityofstontwaterdischarges.Basedontheresultsoftheinspection,thePermitteemustcorrecttheproblemsidentifiedby:a.ReviewingtheSWPPPforcompliancewithSpecialConditionS9andmakingappropriaterevisionswithin7daysoftheinspection.b.Immediatelybeginningtheprocessoffullyimplementingandmaintainingappropriatesourcecontroland/ortreatmentBMPsassoonaspossible,addressingtheproblemsnolaterthanwithin10daysoftheinspection.IfinstallationofnecessarytreatmentBMPsisnotfeasiblewithin10days,EcologymayapproveadditionaltimewhenanextensionisrequestedbyaPermitteewithintheinitial10-dayresponseperiod.c.DocumentingBMPimplementationandmaintenanceinthesitelogbook.2.ThePermitteemustinspectallareasdisturbedbyconstructionactivities,allBMPs,andallstormwaterdischargepointsatleastonceeverycalendarweekandwithin24hoursofanydischargefromthesite.(Forpurposesofthiscondition,individualdischargeeventsthatlastmorethanonedaydonotrequiredailyinspections.Forexample,ifastormwaterponddischargescontinuouslyoverthecourseofaweek,onlyoneinspectionisrequiredthatweek.)ThePermitteemayreducetheinspectionfrequencyfortemporarilystabilized,inactivesitestoonceeverycalendarmonth.3.ThePermitteemusthavestaffknowledgeableintheprinciplesandpracticesoferosionandsedimentcontrol.TheCESCL(sitesoneacreormore)orinspector(siteslessthanoneacre)musthavetheskillstoassessthe:a.Siteconditionsandconstructionactivitiesthatcouldimpactthequalityofstormwater.andb.Effectivenessoferosionandsedimentcontrolmeasuresusedtocontrolthequalityofstormwaterdischarges.4.TheSWPPPmustidentifytheCESCLorinspector,whomustbepresentonsiteoron-callatalltimes.TheCESCLmustobtainthiscertificationthroughanapprovederosionandsedimentcontroltrainingprogramthatmeetstheminimumtrainingstandardsestablishedbyEcology(seeBMPC160inthemanualreferredtoinSpecialConditionS9.C.1and2).ConstructionStornns’aterGeneralPermit—December1,2010Page13 5.ThePermitteemustsummarizetheresultsofeachinspectioninaninspectionreportorchecklistandenterthereport/checklistinto,orattachitto,thesitelogbook.Ataminimum,eachinspectionreportorchecklistmustinclude:a.Inspectiondateandtime.b.Weatherinformation,thegeneralconditionsduringinspectionandtheapproximateamountofprecipitationsincethelastinspection,andprecipitationwithinthelast24hours.c.AsummaryorlistofallimplementedBMPs.includingobservationsofallerosion/sedimentcontrolstructuresorpractices.d.Adescriptionofthelocations:i.OfBMPsinspected.ii.OfBMPsthatneedmaintenanceandwhy.iii.OfBMPsthatfailedtooperateasdesignedorintended,andiv.WhereadditionalordifferentBMPsareneeded,andwhy.e.Adescriptionofstormwaterdischargedfromthesite.ThePermitteemustnotethepresenceofsuspendedsediment,turbidity,discoloration,andoilsheen,asapplicable.f.Anywaterqualitymonitoringperformedduringinspection.g.Generalcommentsandnotes,includingabriefdescriptionofanyBMPrepairs,maintenanceorinstallationsmadefollowingtheinspection.h.AsummaryreportandascheduleofimplementationoftheremedialactionsthatthePermineeplanstotakeifthesiteinspectionindicatesthatthesiteisoutofcompliance.TheremedialactionstakenmustmeettherequirementsoftheSWPPPandthepermit.i.Thename,title,andsignatureofthepersonconductingthesiteinspection,aphonenumberorotherreliablemethodtoreachthisperson,andthefollowingstatement:CUcertifythatthisreportistwe,accurate,andcompletetothebestofmyknowledgeandbelief.”C.Turbidity/TransparencySamplingRequirementsSamplingMethodsa.Ifconstructionactivityinvolvesthedisturbanceof5acresormore,thePermineemustconductturbiditysamplingperSpecialConditionS4.C.b.IfconstructionactivityinvolvesIacreormorebutfewerthan5acresofsoildisturbance,thePemiitteemustconducteithertransparencysamplingorturbiditysamplingperSpecialConditionS4.C.ConstuiectionStor,nii’ateuGeneralPermitDecember1,2010Page14 2.SamplingFrequencya.ThePermitteemustsamplealldischargelocationsatleastonceeverycalendarweekwhenstormwater(orauthorizednon-stormwater)dischargesfromthesiteorentersanyon-sitesurfacewatersofthestate(forexample,acreekrunningthroughasite).b.Samplesmustberepresentativeoftheflowandcharacteristicsofthedischarge.c.Samplingisnotrequiredwhenthereisnodischargeduringacalendarweek.d.Samplingisnotrequiredoutsideofnormalworkinghoursorduringunsafeconditions.e.IfthePermitteeisunabletosampleduringamonitoringperiod,thePermitteemustincludeabriefexplanationinthemonthlyDischargeMonitoringReport(DMR).fSamplingisnotrequiredbeforeconstructionactivitybegins.3.SamplingLocationsa.Samplingisrequiredatallpointswherestormwaterassociatedwithconstructionactivity(orauthorizednon-stormwater)isdischargedoffsite,includingwhereitentersanyon-sitesurfacewatersofthestate(forexample,acreekrunningthroughasite).b.ThePermitteemaydiscontinuesamplingatdischargepointsthatdrainareasoftheprojectthatarefullystabilizedtopreventerosion.c.ThePermitteemustidentifyallsamplingpoint(s)ontheSWPPPsitemapandclearlymarkthesepointsinthefieldwithaflag,tape,stakeorothervisiblemarker.d.Samplingisnotrequiredfordischargethatissentdirectlytosanitaryorcombinedsewersystems.4.SamplingandAnalysisMethodsa.ThePermitteeperformsturbidityanalysiswithacalibratedturbiditymeter(turbidimeter)eitheronsiteoratanaccreditedlab.ThePermitteemustrecordtheresultsinthesitelogbookinnephelometdcturbidityunits(NTU).b.ThePermitteeperformstransparencyanalysisonsitewitha1%-inch-diameter,60-centimeter(cm)-longtransparencytube.ThePermitteewillrecordtheresultsinthesitelogbookincentimeters(cm).Transparencytubesareavailablefrom:http://watermonitorinuepuip.com/pa2es/stream.html.ConstruclionStonmi’aterGeneralPermitDecember1,2010Page15 Table4.MonitoringandReportingRequirementsParameterUnitAnalyticalMethodSamplingBenchmarkPhoneFrequencyValueReportingTriggerValueTurbidityNTUSM2130orEPAWeekly,if25NTU250NTU180.1dischargingTransparencycmManufacturerWeekly,if33cm6cminstructions,ordischargingEcology_guidance5.Turbidity/TransparencyBenchmarkValuesandReportingTriggersThebenchmarkvalueforturbidityis25NTUorless.Thebenchmarkvaluefortransparencyis33centimeters(cm).Note:BenchmarkvaluesdonotapplytodischargestosegmentsofwaterbodiesonWashingtonState’s303(d)list(Category5)forturbidity,finesediment,orphosphorus;thesedischargesaresubjecttoanumericeffluentlimitforturbidity.RefertoSpecialCondition58formoreinformation.a.Turbidity26—249NTU.orTransparency32—7cm:Ifthedischargeturbidityis26to249NTU;orifdischargetransparencyislessthan33cm,butequaltoorgreaterthan6cm,thePermitteemust:i.ReviewtheSWPPPforcompliancewithSpecialConditionS9andmakeappropriaterevisionswithin7daysofthedatethedischargeexceededthebenchmark.ii.Immediatelybegintheprocesstofullyimplementandmaintainappropriatesourcecontroland/ortreatmentBMPsassoonaspossible,addressingtheproblemswithin10daysofthedatethedischargeexceededthebenchmark.IfinstallationofnecessarytreatmentBMPsisnotfeasiblewithin10days,EcologymayapproveadditionaltimewhenthePermifteerequestsanextensionwithintheinitial10-dayresponseperiod.ill.DocumentBMPimplementationandmaintenanceinthesitelogbook.b.Turbidity250NTUorcreater.orTransparency6cmorless:Ifadischargepoint’sturbidityis250NTUorgreater,orifdischargetransparencyislessthanorequalto6cm,thePermitteemustcompletethereportingandadaptivemanagementprocessdescribedbelow.i.TelephonetheapplicableEcologyRegion’sEnvironmentalReportTrackingSystem(ERTS)numberwithin24hours,inaccordancewithSpecialConditionS5.F.•CentralReaion(Okanogan.Chelan.Douglas,Kittitas,Yakima,Klickitat,Benton):(509)575-2490ConstructionStonmi’aterGeneralPermitDecember1,2010Page16 •EasternReaion(Adams,Asotin,Columbia,Ferry,Franklin,Garfield.Grant,Lincoln,PendOreille.Spokane,Stevens,WallaWalla,Whitman):(509)329-3400•NorthwestRegion(Kitsap,Snohomish,Island,King,SanJuan,Skagit,Whatcorn):(425)649-7000•SouthwestReEion(GraysHarbor,Lewis,Mason,Thurston,Pierce,Clark,Cowlitz.Skamania.Wahkiakum.Clallam.Jefferson,Pacific):(360)407-6300Thesenumbersarealsolistedatthefollowingwebsite:http://www.ecv.wa.ov/prorzrams/wq/storrnwater/construction/perrnit.htrnlii.ReviewtheSWPPPforcompliancewithSpecialConditionS9andmakeappropriaterevisionswithin7daysofthedatethedischargeexceededthebenchmark.iii.Immediatelybegintheprocesstofullyimplementandmaintainappropriatesourcecontroland/ortreatmentBMPsassoonaspossible,addressingtheproblemswithin0daysofthedatethedischargeexceededthebenchmark.IfinstallationofnecessarytreatmentBMPsisnotfeasiblewithin10days,EcologymayapproveadditionaltimewhenthePenlifteerequestsanextensionwithintheinitial10-dayresponseperiod.iv.DocumentBMPimplementationandmaintenanceinthesitelogbook.v.Continuetosampledischargesdailyuntil:a)Turbidityis25NTU(orlower);orb)Transparencyis33cm(orgreater);orc)ThePermitteehasdemonstratedcompliancewiththewaterqualitylimitforturbidity:1)Nomorethan5NTUoverbackgroundturbidity,ifbackgroundislessthan50NTU,or2)Nomorethan10%overbackgroundturbidity,ifbackgroundis50NTUorgreater;ord)Thedischargestopsoriseliminated.D.pI-lSamplingRequirements--SianificantConcreteWorkorEngineeredSoilsIfconstructionactivityresultsinthedisturbanceofIacreormore,andinvolvessignificantconcretework(significantconcreteworkmeansgreaterthan1000cubicyardspouredconcreteorrecycledconcreteusedoverthelifeofaproject)ortheuseofengineeredsoils(soilamendmentsincludingbutnotlimitedtoPortlandcement-treatedbase[CTBI,cementkilndust[CKDJ,orflyash),andstormwaterfromtheaffectedareaConstructionStormwaterGeneralPermitDecember1,2010Page17 drainstosurfacewatersoftheStateortoastormsewersystemthatdrainstosurfacewatersofthestate,thePermitteemustconductpHmonitoringassetforthbelow.Note:Inaddition.dischargestosegmentsofwaterbodiesonWashingtonState’s303(d)list(Category’5)forhighpHaresubjecttoanumericeffluentlimitforpH;refertoSpecialConditionS8.1.Forsiteswithsignificantconcretework,thePermitteemustbeginihepHmonitoringperiodwhentheconcreteisfirstpouredandexposedtoprecipitation,andcontinueweeklythroughoutandaftertheconcretepourandcuringperiod,untilstoimwaterpHisintherangeof6.5to8.5(su).2.Forsiteswithengineeredsoils,thePermitteemustbeginthep1-Imonitoringperiodwhenthesoilamendmentsarefirstexposedtoprecipitationandmustcontinueuntiltheareaofengineeredsoilsisfullystabilized.3.DuringtheapplicablepHmonitoringperioddefinedabove,thePermitteemustobtainarepresentativesampleofstormwaterandconductpHanalysisatleastonceperweek.4.ThePermitteemustmonitorpHinthesedimenttrap/pond(s)orotherlocationsthatreceivestormwaterrunofffromtheareaofsignificantconcreteworkorengineeredsoilsbeforethestormwaterdischargestosurfacewaters.5.Thebenchmarkvalueforp1-1is8.5standardunits.AnytimesamplingindicatesthatpHis8.5orgreater,thePermitteemusteither:a.PreventthehighpHwater(8.5orabove)fromenteringstormsewersystemsorsurfacewaters;orb.Ifnecessary,adjustorneutralizethehighpHwateruntilitisintherangeofp’16.5to8.5(su)usinganappropriatetreatmentBMPsuchascarbondioxide(C02)spargingordry’ice.ThePermitteemustobtainwrittenapprovalfromEcologybeforeusinganyformofchemicaltreatmentotherthanCO2spargingordry’ice.6.ThePermitteemustperformpHanalysisonsitewithacalibratedpHmeter,p1-1testkit,orwiderangepHindicatorpaper.ThePermitteemustrecordp1-Imonitoringresultsinthesitelogbook.I(‘ons/ruc/lonSlormu’a/erGenera!PermitDecember1,2010Page18 S5.REPORTINGANDRECORUKEEPINGREQUIREMENTSA.HighTurbidityPhoneReportinaAnytimesamplingperformedinaccordancewithSpecialConditionS4.Cindicatesturbidityhasreachedthe250NTUphonereportinglevel,thePermitteemustcallEcology’sRegionalofficebyphonewithin24hoursofanalysis.Thewebsiteishttp://www.ecy.wa.iov/programs/wg/storrnwater/construction/pennit.htrnl.AlsoseephonenumbersinSpecialCondition54.C.5.b.i.B.DischargeMonitoringReportsPermitteesreqtLiredtoconductwaterqualitysamplinginaccordancewithSpecialConditions54.C(Turbidity/Transparency),S4.D(pH).58(303[dj/TMDLsampling),and/orG13(AdditionalSampling)mustsubmittheresultstoEcology.PermitteesmustsubmitmonitoringdatausingEcology’sWebDMRprogram.TofindoutmoreinformationandtosignupforWebDMRgoto:http://xvvw.ecv.wa.gov/proarams/wp/yerrnits/paris/webdmr.html.Permitteesunabletosubmitelectronically(forexample,thosewhodonothaveaninternetconnection)mustcontactEcologytorequestawaiverandobtaininstructionsonhowtoobtainapapercopyDMRat:MailingAddress:DepartmentofEcologyWaterQualityProgramAttn:StormwaterComplianceSpecialistP0Box47696Olympia,WA98504-7696PermitteeswhoobtainawaivernottouseWebDMRmustusetheformsprovidedtothembyEcology;submittalsmustbemailedtotheaddressabove.PermitteesshallsubmitDMRformstobereceivedbyEcologywithin15daysfollowingtheendofeachmonth.Iftherewasnodischargeduringagivenmonitoringperiod,allPermitteesmustsubmitaDMRasrequiredwith“nodischarge”enteredinplaceofthemonitoringresults.Formoreinformation,contactEcologystaffusinginformationprovidedatthefollowingwebsite:http:/Avww.ecy.wa.gov/programs/spills/response/assistancesoiI%2omay.pdfC.RecordsRetentionThePermitteemustretainrecordsofallmonitoringinformation(sitelogbook,samplingresults,inspectionreports/checklists,etc.),StormwaterPollutionPreventionPlan,andanyotherdocumentationofcompliancewithpermitrequirementsfortheentirelifeoftheconstructionprojectandforaminimumofthreeyearsfollowingtheterminationofpermitcoverage.Suchinformationmustincludeallcalibrationandmaintenancerecords,andrecordsofalldatausedtocompletetheapplicationforthisConstructionStonuwaterGenera!Per,;zitDecember1,2010Page19 permit.ThisperiodofretentionmustbeextendedduringthecourseofanyunresolvedlitigationregardingthedischargeofpollutantsbythePermitteeorwhenrequestedbyEcology.D.RecordiiwResultsForeachmeasurementorsampletaken.thePermitteemustrecordthefollowinginformation:1.Date,place,method,andtimeofsamplingormeasurement.2.Thefirstandlastnameoftheindividualwhoperformedthesamplingormeasurement.3.Thedate(s)theanalyseswereperformed.4.Thefirstandlastnameoftheindividualwhoperformedtheanalyses.5.Theanalyticaltechniquesormethodsused.6.Theresultsofallanalyses.E.AdditionalMonitorinibythePermitteeIfthePermitteemonitorsanypollutantmorefrequentlythanrequiredbythispermitusingtestproceduresspecifiedbySpecialConditionS4ofthispermit,theresultsofthismonitoringmustbeincludedinthecalculationandreportingofthedatasubmittedinthePermittee’sDMR.F.NoncomplianceNotificationIntheeventthePermitteeisunabletocomplywithanypartofthetermsandconditionsofthispermit,andtheresultingnoncompliancemaycauseathreattohumanhealthortheenvironment,thePermitteemust:1.ImmediatelynotifyEcologyofthefailuretocomplybycallingtheapplicableRegionalofficeERTSphonenumber(findathttp://vww.ecv.wa.aov/programs/spilIs/response/assistancesoil%20map.pdf)orrefertoSpecialConditionS4.C.5.b.i.2.Immediatelytakeactiontopreventthedischarge/pollution,orotherwisestoporcorrectthenoncompliance,and,ifapplicable,repeatsamplingandanalysisofanynoncomplianceimmediatelyandsubmittheresultstoEcologywithinfive(5)daysofbecomingawareoftheviolation.3.SubmitadetailedwrittenreporttoEcologywithinfive(5)days,unlessrequestedearlierbyEcology.Thereportmustcontainadescriptionofthenoncompliance,includingexactdatesandtimes,andifthenoncompliancehasnotbeencorrected,theanticipatedtimeitisexpectedtocontinue;andthestepstakenorplannedtoreduce,eliminate,andpreventreoccurrenceofthenoncompliance.Cons/nectionStonnit’aterGeneralPermitDecember1,2010Page20 ThePermitteemustreportanyunanticipatedbypassand/orupsetthatexceedsanyeffluentlimitinthepermitinaccordancewiththe24-hourreportingrequirementcontainedin40C.F.R.122.4l(l)(6)).CompliancewiththeserequirementsdoesnotrelievethePermiffeefromresponsibilitytomaintaincontinuouscompliancewiththetermsandconditionsofthispermitortheresultingliabilityforfailuretocomply.RefertoSectionG14ofthispemiitforspecificinformationregardingnon-compliance.G.AccesstoPlansandRecordsThePermitteemustretainthefollowingpermitdocumentation(plansandrecords)onsite,orwithinreasonableaccesstothesite,forusebytheoperatororforon-sitereviewbyEcologyorthelocaljurisdiction:a.GeneralPermit.b.PermitCoverageLetter.c.StormwaterPollutionPreventionPlan(SWPPP).d.SiteLogBook.2.ThePermitteemustaddresswrittenrequestsforplansandrecordslistedabove(SpecialConditionS5.G.1)asfollows:a.ThePermitteemustprovideacopyofplansandrecordstoEcologywithin14daysofreceiptofawrittenrequestfromEcology.b.ThePermitteemustprovideacopyofplansandrecordstothepublicwhenrequestedinwriting.UponreceivingawrittenrequestfromthepublicforthePermittee’splansandrecords,thePermitteemusteither:i.Provideacopyoftheplansandrecordstotherequesterwithin14daysofareceiptofthewrittenrequest;orii.Notifytherequesterwithin10daysofreceiptofthewrittenrequestofthelocationandtimeswithinnormalbusinesshourswhentheplansandrecordsmaybeviewed;andprovideaccesstotheplansandrecordswithin14daysofreceiptofthewrittenrequest;orWithin14daysofreceiptofthewrittenrequest,thePermitteemaysubmitacopyoftheplansandrecordstoEcologyforviewingand/orcopyingbytherequesteratanEcologyoffice,oramutuallyagreedlocation.Ifplansandrecordsareviewedand/orcopiedatalocationotherthanatanEcologyoffice,thePermitteewillprovidereasonableaccesstocopyingservicesforwhichareasonablefeemaybecharged.ThePermitteemustnotii5’therequesterwithin10daysofreceiptoftherequestwheretheplansandrecordsmaybeviewedand/orcopied.ConsfrzwllonStonnwa!erGeneralPermitDecember1,2010Page21 S6.PERMITFEESThePermitteemustpaypermitfeesassessedbyEcology.FeesforstormwaterdischargescoveredunderthispermitareestablishedbyChapter173-224WAC.EcologycontinuestoassesspermitfeesuntilthepermitisterminatedinaccordancewithSpecialConditionSlOorrevokedinaccordancewithGeneralConditionG5.S7.SOLIDANDLIQUIDWASTEDISPOSALThePermitteemusthandleanddisposeofsolidandliquidwastesgeneratedbyconstructionactivity,suchasdemolitiondebris,constructionmaterials,contaminatedmaterials,andwastematerialsfrommaintenanceactivities,includingliquidsandsolidsfromcleaningcatchbasinsandotherstormwaterfacilities,inaccordancewith:A.SpecialConditionS3,CompliancewithStandards.B.WAC173-216-110.C.Otherapplicableregulations.SS.DISCHARGESTO303(D)ORTMDLWATERBODIESA.SamplingandNumericEffluentLimitsForCertainDischargesto303(d)-listedWaterBodies1.PermitteeswhodischargetosegmentsofwaterbodieslistedasimpairedbytheStateofWashingtonunderSection303(d)oftheCleanWaterActforturbidity,finesediment,highpH,orphosphorus,mustconductwaterqualitysamplingaccordingtotherequirementsofthissection,andSpecialConditionsS4.C.2.b-fandS4.C.3.b-d,andmustcomplywiththeapplicablenumericeffluentlimitationsinS8.Cand58.D.2.AllreferencesandrequirementsassociatedwithSection303(d)oftheCleanWaterActmeanthemostcurrentlistingbyEcologyofimpairedwaters(Category5)thatexistsonJanuary1,2011,orthedatewhentheoperator’scompletepermitapplicationisreceivedbyEcology,whicheverislater.B.LimitsonCoverageforNewDischargestoTMDLor303(d)-listedWatersOperatorsofconstructionsitesthatdischargetoa303(d)-listedwaterbodyarenoteligibleforcoverageunderthispermitunlesstheoperator:1.Preventsexposingstormwatertopollutantsforwhichthewaterbodyisimpaired,andretainsdocumentationintheSWPPPthatdetailsprocedurestakentopreventexposureonsite;or2.Documentsthatthepollutantsforwhichthewaterbodyisimpairedarenotpresentatthesite,andretainsdocumentationofthisfindingwithintheSWPPP;orConstructionStormwaterGeneralPermit—December1,2010Page22 3.ProvidesEcologywithdataindicatingthedischargeisnotexpectedtocauseorcontributetoanexceedanceofawaterqualitystandard,andretainssuchdataonsitewiththeSWPPP.TheoperatormustprovidedataandothertechnicalinformationtoEcologythatsufficientlydemonstrate:a.FordischargestowaterswithoutanEPA-approvedor-establishedTMDL,thatthedischargeofthepollutantforwhichthewaterisimpairedwillmeetin-streamwaterqualitycriteriaatthepointofdischargetothewaterbody;orb.FordischargestowaterswithanEPA-approvedor-establishedTMDL,thatthereissufficientremainingwasleloadallocationintheTMDLtoallowconstructionstormwaterdischargeandthatexistingdischargerstothewaterbodyaresubjecttocomplianceschedulesdesignedtobringthewaterbodyintoattainmentwithwaterqualitystandards.OperatorsofconstructionsitesareeligibleforcoverageunderthispermitifEcologyissuespermitcoveragebaseduponanaffirmativedeterminationthatthedischargewillnotcauseorcontributetotheexistingimpairment.C.SamplingandNumericEffluentLimitsforDischargestoWaterBodiesonthe303(d)ListforTurbidity.FineSediment,orPhosphorusPermitteeswhodischargetosegmentsofwaterbodiesonthe303(d)list(Category5)forturbidity,finesediment,orphosphorusmustconductturbiditysamplinginaccordancewithSpecialConditionS4.C.2andcomplywitheitherofthenumericeffluentlimitsnotedinTable5below.2.AsanaLternativetothe25NTUeffluentlimitnotedinTable5below(appliedatthepointwherestormwater[orauthorizednon-stormwaterjisdischargedoff-site),permitteesmaychoosetocomplywiththesurfacewaterqualitystandardforturbidity.Thestandardis:nomorethan5NTUoverbackgroundturbiditywhenthebackgroundturbidityis50NTVorless,ornomorethana10%increaseinturbiditywhenthebackgroundturbidityismorethan50NTU.Inordertousethewaterqualitystandardrequirement,thesamplingmusttakeplaceatthefollowinglocations:a.Backgroundturbidityinthe303(d)-listedreceivingwaterimmediatelyupstream(upgradient)oroutsidetheareaofinfluenceofthedischarge.b.Turbidityatthepointofdischargeintothe303(d)-listedreceivingwater,insidetheareaofinfluenceofthedischarge.3.Dischargesthatexceedthenumericeffluentlimitforturbidityconstituteaviolationofthispermit.4.PermitteeswhosedischargesexceedthenumericeffluentlimitshallsampledischargesdailyuntiltheviolationiscorrectedandcomplywiththenoncompliancenotificationrequirementsinSpecialConditionS5.F.ConstructionStormii’aterGeneralPermit—Decenther1,2010Page23 Table5.Turbidity,FineSediment&PhosphorusSamplingandLimitsfor303(d)-ListedWatersParameteridentifiedParameterUnitAnalyticalSamplingNumericEffluentin303(d)listingSamptedMethodFrequencyLimit1•TurbidityTurbidityNTUSM2130orWeekly,if25NTU,atthepoint•FineSedimentEPA18O.1dischargingwherestormwateris•Phosphorusdischargedfromthesite;ORIncompliancewiththesurfacewaterqualitystandardforturbidity(S8.C.1a)1Permitteessubjecttoanumericeffluentlimitforturbiditymay,attheirdiscretion!chooseeithernumericeffluentlimitationbasedonsite-specificconsiderationsincluding!butnotlimitedto,safety,accessandconvenience.D.DischargestoWaterBodiesonthe303(dListforI-HuhDRI.Permitteeswhodischargetosegmentsofwaterbodiesonthe5)forhighpHmustconductp1-IsamplinginaccordancewithcomplywiththenumericeffluentlimitofpH6.5to8.5su(Table6).303(d)list(Categorythetablebelow,andTable6.pHSamplingandLimitsfor303(d)-ListedWatersParameteridentifiedinParameterAnalyticalSamplingNumericEffluent303(d)listingSamplede’UnitsMethodFrequencyLimitHighpHpH/StandardpHmeterWeekly,ifIntherangeof6.5—Unitsdischarging8.52.AtthePermittee’sdiscretion,compliancewiththelimitshallthefollowinglocations:a.Directlyinthe303(d)-listedwaterbodysegment,insideinfluenceofthedischarge;orbeassessedatoneoftheimmediateareaofb.Alternatively,thepermitteemaymeasurepHatthepointwherethedischargeleavestheconstructionsite,ratherthaninthereceivingwater.3.Dischargesthatexceedthenumericeffluentlimitforp14(outsidetherangeof6.5—8.5su)constituteaviolationofthispermit.4.PermitteeswhosedischargesexceedthenumericeffluentlimitshallsampledischargesdailyuntiltheviolationiscorrectedandcomplywiththenoncompliancenotificationrequirementsinSpecialConditionS5.F.ConstructionSlonni:’aterGeneralFermi!Page24December1,2010 E.SamplinciandLimitsforSitesDiseharaingtoWatersCoveredbyaTMDLorAnotherPollutionControlPlan1.DischargestoawaterbodythatissubjecttoaTotalMaximumDailyLoad(TMDL)forturbidity,finesediment,highpH,orphosphorusmustbeconsistentwiththeTMDL.Refertohttp://www.ecy.wagov/programs/wg/tmdl/index.htrnlformoreinformationonTMDLs.a.WhereanapplicableTMDLsetsspecificwasteloadallocationsorrequirementsfordischargescoveredbythispermit,dischargesmustbeconsistentwithanyspecificwasteloadallocationsorrequirementsestablishedbytheapplicableTMDL.i.ThePermitteemustsampledischargesweeklyorasotherwisespecifiedbytheTMDLtoevaluatecompliancewiththespecificwasteloadallocationsorrequirements.ii.AnalyticalmethodsusedtomeetthemonitoringrequirementsmustconformtothelatestrevisionoftheGuidelinesEstablishingTestProceduresfortheAnalysisofPollutantscontainedin40CFRPart136.Turbidityandp1-Imethodsneednotbeaccreditedorregisteredunlessconductedatalaboratorywhichmustotherwisebeaccreditedorregistered.b.WhereanapplicableTMDLhasestablishedageneralwasteloadallocationforconstructionstormwaterdischarges,buthasnotidentifiedspecificrequirements,compliancewithSpecialConditionsS4(Monitoring)and59(SWPPPs)willconstitutecompliancewiththeapprovedTMDL.c.WhereanapplicableTMDLhasnotspecifiedawasteloadallocationforconstructionstormwaterdischarges,buthasnotexcludedthesedischarges,compliancewithSpecialConditions54(Monitoring)andS9(SWPPPs)willconstitutecompliancewiththeapprovedTMDL.d.WhereanapplicableTMDLspecificallyprecludesorprohibitsdischargesfromconstructionactivity,theoperatorisnoteligibleforcoverageunderthispermit.2.ApplicableTMDLmeansaTMDLforturbidity,finesediment,highpH,orphosphorusthatiscompletedandapprovedbyEPAbeforeJanuary’1,2011,orbeforethedatetheoperator’scompletepermitapplicationisreceivedbyEcology,whicheverislater.TMDLscompletedaftertheoperator’scompletepermitapplicationisreceivedbyEcologybecomeapplicabletothePermifteeonlyiftheyareimposedthroughanadministrativeorderbyEcology,orthroughamodificationofpermitcoverage.ConstructionStonnii’aterGeneralPermitDecember1,2010Page25 S9.STORMWATERPOLLUTIONPREVENTIONPLANThePermitteemustprepareandproperlyimplementanadequateStormwaterPollutionPreventionPlan(SWPPP)forconstructionactivityinaccordancewiththerequirementsofthispermitbeginningwithinitialsoildisturbanceanduntilfinalstabilization.A.ThePermittee’sSWPPPmustmeetthefollowinczobjectives:1.Toimplementbestmanagementpractices(BMPs)topreventerosionandsedimentation,andtoidentify,reduce,eliminateorpreventstormwatercontaminationandwaterpollutionfromconstructionactivity.2.Topreventviolationsofsurfacewaterquality,groundwaterquality,orsedimentmanagementstandards.3.Tocontrolpeakvolumetricflowratesandvelocitiesofstornnvaterdischarges.B.GeneralRequirements1.TheSWPPPmustincludeanarrativeanddrawings.AllBMPsmustbeclearlyreferencedinthenarrativeandmarkedonthedrawings.TheSWPPPnarrativemustincludedocumentationtoexplainandjustifythepollutionpreventiondecisionsmadefortheproject.Documentationmustinclude:a.Informationaboutexistingsiteconditions(topography,drainage,soils,vegetation,etc.).b.Potentialerosionproblemareas.c.The12elementsofaSWPPPinSpecialConditionS9.D.1-12,includingBMPsusedtoaddresseachelement.d.Constructionphasing/sequenceandgeneralBMPimplementationschedule.e.TheactionstobetakenifBMPperformancegoalsarenotachieved—forexample,acontingencyplanforadditionaltreatmentand/orstorageofstormwaterthatwouldviolatethewaterqualitystandardsifdischarged.f.Engineeringcalculationsforpondsandanyotherdesignedstructures.2.ThePermitteemustmodifytheSWPPPif,duringinspectionsorinvestigationsconductedbytheowner/operator,ortheapplicablelocalorstateregulatoryauthority,itisdeterminedthattheSWPPPis,orwouldbe,ineffectiveineliminatingorsignificantlyminimizingpollutantsinstormwaterdischargesfromthesite.ThePermitteemustthen:a.ReviewtheSWPPPforcompliancewithSpecialConditionS9andmakeappropriaterevisionswithin7daysoftheinspectionorinvestigation.b.Immediatelybegintheprocesstofullyimplementandmaintainappropriatesourcecontroland/ortreatmentBMPsassoonaspossible,addressingtheproblemsnolaterthan10daysfromtheinspectionorinvestigation.IfConstructionStornn:’aterGeneralPermitDecember1,2010Page26 installationofnecessarytreatmentBMPsisnotfeasiblewithin10days,EcologymayapproveadditionaltimewhenanextensionisrequestedbyaPermitteewithintheinitial10-dayresponseperiod,c.DocumentBMPimplementationandmaintenanceinthesitelogbook.ThePermitteemustmodifytheSWPPPwheneverthereisachangeindesign,construction,operation,ormaintenanceattheconstructionsitethathas,orcouldhave,asignificanteffectonthedischargeofpollutantstowatersoftheState.C.StonriwaterBestManatementPractices(BMPsBMPsmustbeconsistentwith:1.StormwaterManagementManualforWesternWashington(mostrecentedition),forsiteswestofthecrestoftheCascadeMountains;or2.StormwaterManagementManualforEasternWashington(mostrecentedition),forsiteseastofthecrestoftheCascadeMountains;or3.RevisionstothemanualslistedinSpecialConditionS9.C.l.&2.,orotherstormwatermanagementguidancedocumentsormanualswhichprovideanequivalentlevelofpollutionprevention,thatareapprovedbyEcologyandincorporatedintothispermitinaccordancewiththepermitmodificationrequirementsofWAC173-226-230;or4.DocumentationintheSWPPPthattheBMPsselectedprovideanequivalentlevelofpollutionprevention,comparedtotheapplicableStormwaterManagementManuals,including:a.ThetechnicalbasisfortheselectionofallstorniwaterBMPs(scientific,technicalstudies,and/ormodeling)thatsupporttheperformanceclaimsfortheBMPsbeingselected.b.AnassessmentofhowtheselectedBMPwillsatisfyALARTrequirementsandtheapplicablefederaltechnology-basedtreatmentrequirementsunder40CFRpart125.3.D.SWPPP—NarrativeContentsandRequirementsThePermitteemustincludeeachofthe12elementsbelowinSpecialCondition59.D.1-12inthenarrativeoftheSWPPPandimplementthemLLnlesssiteconditionsrendertheelementunnecessaryandtheexemptionfromthatelementisclearlyjustifiedintheSWPPP.1.PreserveVegetatioa/?vlarkClearingLimitsa.Beforebeginningland-disturbingactivities,includingclearingandgrading,clearlymarkallclearinglimits,sensitiveareasandtheirbuffers,andtreesthataretobepreservedwithintheconstructionarea.ConstructionStonnwaterGeneralPermitDecember1,2010Page27 b.Retainthedufflayer,nativetopsoil,andnaturalvegetationinanundisturbedstatetothemaximumdegreepracticable.2.EstablishConstructionAccessa.Limitconstructionvehicleaccessandexittooneroute,ifpossible.b.Stabilizeaccesspointswithapadofquarryspalls,crushedrock,orotherequivalentBMPs,tominimizetrackingsedimentontoroads.c.Locatewheelwashortirebathsonsite,ifthestabilizedconstructionentranceisnoteffectiveinpreventingtrackingsedimentontoroads.d.Ifsedimentistrackedoffsite.cleantheaffectedroadwaythoroughlyattheendofeachday.ormorefrequentlyasnecessary(forexample,during‘vetweather).Removesedimentfromroadsbyshoveling,sweeping,orpickupandtransportofthesedimenttoacontrolledsedimentdisposalarea.e.ConductstreetwashingonlyaftersedimentremovalinaccordancewithSpecialCondition59.D.2.d.ControlstreetwashwastewaterbypumpingbackonsiteorotherwisepreventingitfromdischargingintosystemstributarytowatersoftheState.3.ControlFlowRatesa.Protectpropertiesandwaterwaysdownstreamofdevelopmentsitesfromerosionandtheassociateddischargeofturbidwatersduetoincreasesinthevelocityandpeakvolumetricflowrateofstormwaterrunofffromtheprojectsite,asrequiredbylocalplanapprovalauthority.b.WherenecessarytocomplywithSpecialConditionS9.D.3.a,constructstonnwaterretentionordetentionfacilitiesasoneofthefirststepsingrading.Assurethatdetentionfacilitiesifinctionproperlybeforeconstructingsiteimprovements(forexample,impervioussurfaces).c.Ifpermanentinfiltrationpondsareusedforflowcontrolduringconstruction,protectthesefacilitiesfromsiltationduringtheconstructionphase.4.InstallSedimentControlsThePermitteemustdesign,installandmaintaineffectiveerosioncontrolsandsedimentcontrolstominimizethedischargeofpollutants.Ataminimum,thePermitteemustdesign,installandmaintainsuchcontrolsto:a.ConstructsedimentcontrolBMPs(sedimentponds,traps,filters,etc.)asoneofthefirststepsingrading.TheseBMPsmustbefunctionalbeforeotherlanddisturbingactivitiestakeplace.b.Minimizesedimentdischargesfromthesite.Thedesign,installationandmaintenanceoferosionandsedimentcontrolsmustaddressfactorssuchastheamount,frequency.intensityanddurationofprecipitation,thenatureofConstructionStonnwaterGenera!Permit—Dece,nber1,2010Page28 resultingstormwaterrunoff,andsoilcharacteristics,includingtherangeofsoilparticlesizesexpectedtobepresentonthesite.c.DirectstormwaterrunofffromdisturbedareasthroughasedimentpondorotherappropriatesedimentremovalBMP,beforetherunoffleavesaconstructionsiteorbeforedischargetoaninfiltrationfacility.RunofffromfullystabilizedareasmaybedischargedwithoutasedimentremovalBMP,butmustmeettheflowcontrolperformancestandardofSpecialConditionS9.D.3.a.d.LocateBMPsintendedtotrapsedimentonsiteinamannertoavoidinterferencewiththemovementofjuvenilesalmonidsattemptingtoenteroff-channelareasordrainages.e.Provideandmaintainnaturalbuffersaroundsurfacewaters,directstorrnwatertovegetatedareastoincreasesedimentremovalandmaximizestormwaterinfiltration,unlessinfeasible.f.Wherefeasible,designoutletstructuresthatwithdrawimpoundedstormwaterfromthesurfacetoavoiddischargingsedimentthatisstillsuspendedlowerinthewatercolumn.5.StabilizeSoilsa.ThePemiitteemuststabilizeexposedandunworkedsoilsbyapplicationofeffectiveBMPsthatpreventerosion.ApplicableBMPsinclude,butarenotlimitedto:temporaryandpermanentseeding,sodding,mulching,plasticcovering,erosioncontrolfabricsandmailing,soilapplicationofpolyaciylamide(PAM),theearlyapplicationofgravelbaseonareastobepaved,anddustcontrol.b.ThePenriitteemustcontrolstormwatervolumeandvelocitywithinthesitetominimizesoilerosion.c.ThePermitteemustcontrolstormwaterdischarges,includingbothpeakflowratesandtotalstormwatervolume,tominimizeerosionatoutletsandtominimizedownstreamchannelandstreambankerosion.d.Dependingonthegeographiclocationoftheproject,thePermifteemustnotallowsoilstoremainexposedandunworkedformorethanthetimeperiodssetforthbelowtopreventerosion:WestoftheCascadeMountainsCrestDuringthedryseason(MayI-Sept.30):7daysDuringthewetseason(October1-April30):2daysEastoftheCascadeMountainsCrest.exceptforCentralBasin*Duringthedryseason(July1-September30):10daysDuringthewetseason(October1-June30):5daysTheCentralBasin*,EastoftheCascadeMountainsCrestConstnw/ionStomnni’aierGeneralPer,;zii—December1,20)0Page29 DuringthedrySeason(July1-September30):30daysDuringthewetseason(October1-June30):15days*Note:TheCentralBasinisdefinedastheportionsofEasternWashingtonwithmeanannualprecipitationoflessthan12inches.e.ThePermitteemuststabilizesoilsattheendoftheshiftbeforeaholidayorweekendifneededbasedontheweatherforecast.f.ThePermitteemuststabilizesoilstockpilesfromerosion,protectedwithsedimenttrappingmeasures,andwherepossible,belocatedawayfromstormdraininlets,waterways,anddrainagechannels.g.ThePemiitteemustminimizetheamountofsoilexposedduringconstructionactivity.h.ThePermitteemustminimizethedisturbanceofsteepslopes.ThePermitteemustminimizesoilcompactionand,unlessinfeasible,preservetopsoil.6.ProtectSlopesa.ThePermitteemustdesignandconstructcut-and-fillslopesinamannertominimizeerosion.Applicablepracticesinclude,butarenotlimitedto,reducingcontinuouslengthofslopewithterracinganddiversions,reducingslopesteepness,androugheningslopesurfaces(forexample,trackwalking).b.ThePermitteemustdivertoffisitestormwater(run-on)orgroundwaterawayfromslopesanddisturbedareaswithinterceptordikes,pipes,and/orswales.Off-sitestonrnvatershouldbemanagedseparatelyfromstonnwatergeneratedonthesite.c.Atthetopofslopes,collectdrainageinpipeslopedrainsorprotectedchannelstopreventerosion.i.WestoftheCascadeMountainsCrest:Temporarypipeslopedrainsmusthandlethepeak10-minutevelocityofflowfromaTypeIA,10-year,24-hourfrequencystormforthedevelopedcondition.Alternatively,the10-year,I-hourflowratepredictedbyanapprovedcontinuousrunoffmodel,increasedbyafactorof1.6,maybeused.Thehydrologicanalysismustusetheexistinglandcoverconditionforpredictingflowratesfromtributaryareasoutsidetheprojectlimits.Fortributaryareasontheprojectsite,theanalysismustusethetemporaryorpermanentprojectlandcovercondition,whicheverwillproducethehighestflowrates.IfusingtheWesternWashingtonHydrologyModel(WWHM)topredictflows,baresoilareasshouldbemodeledas“landscapedarea.”ConstructionStormit’aterGeneralPermitDecember1,2010Page30 ii.EastoftheCascadeMountainsCrest:Temporarypipeslopedrainsmusthandletheexpectedpeakflowvelocityfroma6-month.3-hourstormforthedevelopedcondition,referredtoastheshortdurationstorm.d.Placeexcavatedmaterialontheuphillsideoftrenches,consistentwithsafetyandspaceconsiderations.e.Placecheckdamsatregularintervalswithinconstructedchannelsthatarecutdownaslope.7.ProtectDrainInletsa.Protectallstormdraininletsmadeoperableduringconstructionsothatstormwaterrunoffdoesnotentertheconveyancesystemwithoutfirstbeingfilteredortreatedtoremovesediment.b.Cleanorremoveandreplaceinletprotectiondeviceswhensedimenthasfilledone-thirdoftheavailablestorage(unlessadifferentstandardisspecifiedbytheproductmanufacturer).8.StabilizeChannelsandOutletsa.Design.constructandstabilizeallon-siteconveyancechannelstopreventerosionfromthefollowingexpectedpeakflows:i.WestoftheCascadeMountainsCrest:Channelsmusthandlethepeak10-minutevelocityofflowfromaTypeIA,10-year,24-hourfrequencystormforthedevelopedcondition.Alternatively,the10-year,1-hourflowrateindicatedbyanapprovedcontinuousrunoffmodel,increasedbyafactorof1.6,maybeused.Thehydrologicanalysismustusetheexistinglandcoverconditionforpredictingflowratesfromtributaryareasoutsidetheprojectlimits.Fortributaryareasontheprojectsite,theanalysismustusethetemporaryorpermanentprojectlandcovercondition,whicheverwillproducethehighestflowrates,IfusingtheWWHMtopredictflows,baresoilareasshouldbemodeledas‘landscapedarea.”ii.EastoftheCascadeMountainsCrest:Channelsmusthandletheexpectedpeakflowvelocityfroma6-month,3-hourstorniforthedevelopedcondition,referredtoastheshortdurationstorm.b.Providestabilization,includingarmoringmaterial,adequatetopreventerosionofoutlets,adjacentstreambanks,slopes,anddownstreamreachesattheoutletsofallconveyancesystems.9.ControlPollutantsDesign,install,implementandmaintaineffectivepollutionpreventionmeasurestominimizethedischargeofpollutants.ThePermitteemust:ConstructionStormii’aterGeneralFer,njt—December1,2010Page31 a.Handleanddisposeofallpollutants,includingwastematerialsanddemolitiondebristhatoccuronsiteinamannerthatdoesnotcausecontaminationofstormwater.b.Providecover,containment,andprotectionfromvandalismforallchemicals,liquidproducts,petroleumproducts,andothermaterialsthathavethepotentialtoposeathreattohumanhealthortheenvironment.On-sitefuelingtanksmustincludesecondary’containment.Secondarycontainmentmeansplacingtanksorcontainerswithinanimperviousstructurecapableofcontaining110%ofthevolumecontainedinthelargesttankwithinthecontainmentstructure.Double-walledtanksdonotrequireadditionalsecondarycontainment.c.Conductmaintenance,fueling,andrepairofheavyequipmentandvehiclesusingspillpreventionandcontrolmeasures.Cleancontaminatedsurfacesimmediatelyfollowinganyspillincident.d.Dischargewheelwashortirebathwastewatertoaseparateon-sitetreatmentsystemthatpreventsdischargetosurfacewater,suchasclosed-looprecirculationoruplandlandapplication,ortothesanitarysewerwithlocalsewerdistrictapproval.e.Applyfertilizersandpesticidesinamannerandatapplicationratesthatwillnotresultinlossofchemicaltostormwatermnoff.Followmanufacturers’labelrequirementsforapplicationratesandprocedures.fiUseBMPstopreventcontaminationofstormwaterrunoffbypH-modifyingsources.Thesourcesforthiscontaminationinclude,butarenotlimitedto:bulkcement,cementkilndust,flyash,newconcretewashingandcuringwaters,wastestreamsgeneratedfromconcretegrindingandsawing,exposedaggregateprocesses,dewateringconcretevaults,concretepumpingandmixerwashoutwaters.(Alsorefertothedefinitionfor“concretewastewater”inAppendixA--Definitions.)g.AdjustthepHofstormwaterifnecessarytopreventviolationsofwaterqualitystandards.h.Assurethatwashoutofconcretetrucksisperformedoffsiteorindesignatedconcretewashoutareasonly.Donotwashoutconcretetrucksontotheground,orintostormdrains,openditches,streets,orstreams.Donotdumpexcessconcreteonsite,exceptindesignatedconcretewashoutareas.ConcretespillageorconcretedischargetosurfacewatersoftheStateisprohibited.i.ObtainwrittenapprovalfromEcologybeforeusingchemicaltreatmentotherthanCO2ordryicetoadjustpH.10.ControlDewateringa.Permilleesmustdischargefoundation,vault,andtrenchdewateringwater.whichhavecharacteristicssimilartostoimwaterrunoffatthesite,intoaConsiriwlionSionnu’aterGeneralPermitDecember1,2010Page32 controlledconveyancesystembeforedischargetoasedimenttraporsedimentpond.b.Permitteesmaydischargeclean,non-turbiddewateringwater,suchaswell-pointgroundwater,tosystemstributary’to,ordirectlyintosurfacewatersoftheState,asspecifiedinSpecialCondition59.D.8,providedthedewatedngflowdoesnotcauseerosionorfloodingofreceivingwaters.Donotroutecleandewatedngwaterthroughstormwatersedimentponds.Notethat“surfacewatersoftheState”mayexistonaconstructionsiteaswellasoffsite;forexample.acreekrunningthroughasite.c.Othertreatmentordisposaloptionsmayinclude:i.Infiltration.ii.Transportoffsiteinavehicle,suchasavacuumflushtruck,forlegaLdisposalinamannerthatdoesnotpollutestatewaters.iii.Ecology-approvedon-sitechemicaltreatmentorothersuitabletreatmenttechnologies.iv.Sanitaryorcombinedsewerdischargewithlocalsewerdistrictapproval,ifthereisnootheroption.v.Useofasedimentationbagwithdischargetoaditchorswaleforsmallvolumesoflocalizeddewatering.d.Permitteesmusthandlehighlyturbidorcontaminateddewateringwaterseparatelyfromstormwater.II.MaintainBMPsa.PermitteesmustmaintainandrepairalltemporaryandpermanenterosionandsedimentcontrolBMPsasneededtoassurecontinuedperformanceoftheirintendedftmctioninaccordancewithBMPspecifications.b.Pem,itteesmustremovealltemporaryerosionandsedimentcontrolBMPswithin30daysafterachievingfinalsitestabilizationorafterthetemporaryBMPsarenolongerneeded.12.ManagetheProjecta.Phasedevelopmentprojectstothemaximumdegreepracticableandtakeintoaccountseasonalworklimitations.b.Inspectionandmonitoring--Inspect,maintainandrepairallBMPsasneededtoassurecontinuedperformanceoftheirintendedfunction.ConductsiteinspectionsandmonitoringinaccordancewithSpecialConditionS4.c.MaintaininganupdatedconstructionSWPPP--Maintain,update,andimplementtheSWPPPinaccordancewithSpecialConditionsS3,S4and59.ConstructionStornnvaterGeneralPermitDecember1,20)0Page33 E.SWPPP—MapContentsandRequirementsThePermittee’sSWPPPmustalsoincludeavicinitymaporgenerallocationmap(forexample,aUSGSquadranglemap,aportionofacountyorcitymap,orotherappropriatemap)withenoughdetailtoidentifythelocationoftheconstructionsiteandreceivingwaterswithinonemileofthesite.TheSWPPPmustalsoincludealegiblesitemap(ormaps)showingtheentireconstructionsite.Thefollowingfeaturesmustbeidentified,unlessnotapplicableduetositeconditions:1.Thedirectionofnorth,propertylines,andexistingstructuresandroads.2.Cutandfillslopesindicatingthetopandbottomofslopecatchlines.3.Approximateslopes,contours,anddirectionofstomuvaterflowbeforeandaftermajorgradingactivities.4.Areasofsoildisturbanceandareasthatwillnotbedisturbed.5.LocationsofstructuralandnonstrllctlLralcontrols(BMPs)identifiedintheSWPPP.6.Locationsofoff-sitematerial,stockpiles,wastestorage,borrowareas,andvehicle/equipmentstorageareas.7.Locationsofallsurfacewaterbodies,includingwetlands.8.Locationswherestormwaterornon-stormwaterdischargesoff-siteand/ortoasurfacewaterbody,includingwetlands.9.Locationofwaterqualitysamplingstation(s),ifsamplingisrequiredbystateorlocalpermittingauthority.10.Areaswherefinalstabilizationhasbeenaccomplishedandnofurtherconstruction-phasepermitrequirementsapply.SlO.NOTICEOFTERMINATIONA.Thesiteiseligibleforterminationofcoveragewhenithasmetanyofthefollowingconditions:1.Thesitehasundergonefinalstabilization,thePermitteehasremovedalltemporaryBMPs(exceptbiodegradableBMPsclearlymanufacturedwiththeintentionforthematerialtobeleftinplaceandnotinterferewithmaintenanceorlanduse),andallstormwaterdischargesassociatedwithconstructionactivityhavebeeneliminated;or2.AllportionsofthesitethathavenotundergonefinalstabilizationperSpecialConditionS10.A.1havebeensoldand/ortransferred(perGeneralConditionG9),andthePermitteenolongerhasoperationalcontroloftheconstructionactivity;orConstructionStonnii’aterGeneralPennit—December1,2010Page34 3.Forresidentialconstructiononly,thePermitteehascompletedtemporarystabilizationandthehomeownershavetakenpossessionoftheresidences.B.Whenthesiteiseligiblefortermination,thePennitteemustsubmitacompleteandaccurateNoticeofTermination(NOT)form,signedinaccordancewithGeneralConditionG2.to:DepartmentofEcologyWaterQualityProgram-ConstructionStormwaterP0Box47696Olympia,Washington98504-7696TheterminationiseffectiveonthedateEcologyreceivestheNOTform,unlessEcologynotifiesthePermineewithin30daysthatterminationrequestisdeniedbecausethePermitteehasnotmettheeligibilityrequirementsinSpecialConditionS1O.A.Permitteestransferringthepropertytoanewpropertyowneroroperator/permitteearerequiredtocompleteandsubmittheNoticeofTransferformtoEcology,butarenotrequiredtosubmitaNoticeofTerminationformforthistypeoftransaction.ConstructionStorm3I’aterGeneralPennitDecenther1,2010Page35 GENERALCONDITIONSGI.DISCHARGEVIOLATIONSAlldischargesandactivitiesauthorizedbythisgeneralpermitmustbeconsistentwiththetermsandconditionsofthisgeneralpermit.Anydischargeofanypollutantmorefrequentthanoratalevelinexcessofthatidentifiedandauthorizedbythegeneralpermitmustconstituteaviolationofthetermsandconditionsofthispermit.G2.SIGNATORYREQUIREMENTSA.Allpermitapplicationsmustbearacertificationofcorrectnesstobesigned:I.Inthecaseofcorporations,byaresponsiblecorporateofficerofatleastthelevelofvicepresidentofacorporation;2.Inthecaseofapartnership,byageneralpartnerofapartnership;3.Intheeaseofsoleproprietorship,bytheproprietor;or4.Inthecaseofamunicipal,state,orotherpublicfacility,byeitheraprincipalexecutiveofficerorrankingelectedofficial.B.AllreportsrequiredbythispermitandotherinformationrequestedbyEcologymustbesignedbyapersondescribedaboveorbyadulyauthorizedrepresentativeofthatperson.Apersonisadulyauthorizedrepresentativeonlyif:I.TheauthorizationismadeinwritingbyapersondescribedaboveandsubmittedtotheEcology.2.Theauthorizationspecifieseitheranindividualorapositionhavingresponsibilityfortheoveralloperationoftheregulatedfacility,suchasthepositionofplantmanager,superintendent,positionofequivalentresponsibility,oranindividualorpositionhavingoverallresponsibilityforenvironmentalmatters.C.Changestoauthorization.IfanauthorizationunderparagraphG2.B.2aboveisnolongeraccuratebecauseadifferentindividualorpositionhasresponsibilityfortheoveralloperationofthefacility,anewauthorizationsatisfyingtherequirementsofparagraphG2.B.2abovemustbesubmittedtoEcologypriortoortogetherwithanyreports,information,orapplicationstobesignedbyanauthorizedrepresentative.D.Certification.Anypersonsigningadocumentunderthissectionmustmakethefollowingcertification:“Icertifyunderpenaltyoflaw,thatthisdocumentandallattachmentswerepreparedundermydirectionorsupervisioninaccordancewithasystemdesignedtoassurethatqualifiedpersonnelproperlygatheredandevaluatedtheinformationsubmitted.Basedonmyinquiryofthepersonorpersonswhomanagethesystem,orthosepersonsdirectlyresponsibleforgatheringCons/nw/ionStonnig’aterGeneralPennilDecember1,2010Page36 information,theinformationsubmittedis,tothebestofmyknowledgeandbelief,true,accurate,andcomplete.Iamawarethattherearesignificantpenaltiesforsubmittingfalseinformation,includingthepossibilityoffineandimprisonmentforknowingviolations.”G3.RIGHTOFINSPECTIONANDENTRYThePermitteemustallowanauthorizedrepresentativeofEcology,uponthepresentationofcredentialsandsuchotherdocumentsasmayberequiredbylaw:A.Toenteruponthepremiseswhereadischargeislocatedorwhereanyrecordsarekeptunderthetermsandconditionsofthispermit.B.Tohaveaccesstoandcopy—atreasonabletimesandatreasonablecost--anyrecordsrequiredtobekeptunderthetermsandconditionsofthispermit.C.Toinspect--atreasonabletimes—anyfacilities,equipment(includingmonitoringandcontroLequipment),practices,methods,oroperationsregulatedorrequiredunderthispermit.D.Tosampleormonitor—atreasonabletimes—anysubstancesorparametersatanylocationforpurposesofassuringpermitcomplianceorasotherwiseauthorizedbytheCleanWaterAct.G4.GENERALPERMITMODIFICATIONANDREVOCATIONThispermitmaybemodified,revokedandreissued,orterminatedinaccordancewiththeprovisionsofChapter173-226WAC.Groundsformodification,revocationandreissuance,orterminationinclude,butarenotlimitedto,thefollowing:A.Whenachangeoccursinthetechnologyorpracticesforcontrolorabatementofpollutantsapplicabletothecategoryofdischargerscoveredunderthispermit.B.WheneffluentlimitationguidelinesorstandardsarepromulgatedpursuanttotheCWAorChapter90.48RCW,forthecategoryofdischargerscoveredunderthispermit.C.Whenawaterqualitymanagementplancontainingrequirementsapplicabletothecategoryofdischargerscoveredunderthispermitisapproved,orD.Wheninformationisobtainedthatindicatescumulativeeffectsontheenvironmentfromdischargerscoveredunderthispermitareunacceptable.G5.REVOCATIONOFCOVERAGEUNDERTHEPERMITPursuanttoChapter43.218RCWandChapter173-226WAC,theDirectormayterminatecoverageforanydischargerunderthispermitforcause.Caseswherecoveragemaybeterminatedinclude,butarenotlimitedto,thefollowing:ConstructionStonnwaterGeneralPermitDecember1,2010Page37 A.Violationofanytermorconditionofthispermit.B.Obtainingcoverageunderthispermitbymisrepresentationorfailuretodisclosefullyallrelevantfacts.C.Achangeinanyconditionthatrequireseitheratemporaryorpermanentreductionoreliminationofthepermitteddischarge.D.FailureorrefusalofthePermitteetoallowentryasrequiredinRCW90.48.090.E.Adeterminationthatthepermittedactivityendangershumanhealthortheenvironment,orcontributestowaterqualitystandardsviolations.F.NonpaymentofpermitfeesorpenaltiesassessedpursuanttoRCW90.48.465andChapter173-224WAC.G.FailureofthePermitteetosatisfythepublicnoticerequirementsofWAC173-226-130(5),whenapplicable.TheDirectormayrequireanydischargerunderthispermittoapplyforandobtaincoverageunderanindividualpermitoranothermorespecificgeneralpermit.PermitteeswhohavetheircoveragerevokedforcauseaccordingtoWAC173-226-240mayrequesttemporarycoverageunderthispermitduringthetimeanindividualpermitisbeingdeveloped,providedtherequestismadewithinninety(90)daysfromthetimeofrevocationandissubmittedalongwithacompleteindividualpermitapplicationform.G6.REPORTINGACAUSEFORMODTFICATIONThePermitteemustsubmitanewapplication,orasupplementtothepreviousapplication,wheneveramaterialchangetotheconstructionactivityorinthequantityortypeofdischargeisanticipatedwhichisnotspecificallyauthorizedbythispermit.Thisapplicationmustbesubmittedatleastsixty(60)dayspriortoanyproposedchanges.Filingarequestforapermitmodification,revocationandreissuance,ortermination,oranotificationofplannedchangesoranticipatednoncompliancedoesnotrelievethePermitteeofthedutytocomplywiththeexistingpermituntilitismodifiedorreissued.G7.COMPLIANCEWITHOTHERLAWSANDSTATUTESNothinginthispermitwillbeconstruedasexcusingthePermitteefromcompliancewithanyapplicablefederal,state,orlocalstatutes,ordinances,orregulations.G8.DUTYTOREAPPLYThePermitteemustapplyforpermitrenewalatleast180dayspriortothespecifiedexpirationdateofthispermit.ConstructionStonnu’aterGeneralPermitDecember1,2010Page38 G9.TRANSFEROFGENERALPERMITCOVERAGECoverageunderthisgeneralpermitisautomaticallytransferredtoanewdischarger,includingoperatorsoflots/parcelswithinacommonplanofdevelopmentorsale,if:A.Awrittenagreement(TransferofCoverageForm)betweenthecurrentdischarger(Pennittee)andnewdischarger,signedbybothpartiesandcontainingaspecificdatefortransferofpermitresponsibility,coverage.andliabilityisslLbmittedtotheDirector;andB.TheDirectordoesnotnotifythecurrentdischargerandnewdischargeroftheDirector’sintenttorevokecoverageunderthegeneralpermit.Ifthisnoticeisnotgiven,thetransferiseffectiveonthedatespecifiedinthewrittenagreement.Whenacurrentdischarger(Permittee)transfersaportionofapermittedsite,thecurrentdischargermustalsosubmitanupdatedapplicationform(NOl)totheDirectorindicatingtheremainingpermittedacreageafterthetransfer.610.REMOVEDSUBSTANCESThePermitteemustnotre-suspendorreintroducecollectedscreenings,grit,solids,sludges,filterbackwash,orotherpollutantsremovedinthecourseoftreatmentorcontrolofstormwatertothefinaleffluentstreamfordischargetostatewaters.Gil.DUTYTOPROVIDEINFORMATIONThePermitteemustsubmittoEcology,withinareasonabletime,allinformationthatEcologymayrequesttodeterminewhethercauseexistsformodifying,revokingandreissuing,orterminatingthispermitortodeterminecompliancewiththispermit.ThePermitteemustalsosubmittoEcology,uponrequest,copiesofrecordsrequiredtobekeptbythispermit[40CFR122.410)1.612.OTHERREQUIREMENTSOF40CFRAllotherrequirementsof40CFR122.41and122.42areincorporatedinthispermitbyreference.613.ADDITIONALMONITORINGEcologymayestablishspecificmonitoringrequirementsinadditiontothosecontainedinthispennitbyadministrativeorderorpermitmodification.ConstructionStornni’aterGeneralPermit—December1,2010Page39 G14.PENALTIESFORVIOLATINGPERMITCONDITIONSAnypersonwhoisfoundguiltyofwillfullyviolatingthetermsandconditionsofthispermitshallbedeemedguiltyofacrime,anduponconvictionthereofshallbepunishedbyafineofuptotenthousanddollars($10,000)andcostsofprosecution,orbyimprisonmentinthediscretionofthecourt.Eachdayuponwhichawillfulviolationoccursmaybedeemedaseparateandadditionalviolation.Anypersonwhoviolatesthetermsandconditionsofawastedischargepermitshallincur,inadditiontoanyotherpenaltyasprovidedbylaw,acivilpenaltyintheamountofuptotenthousanddollars($10,000)foreverysuchviolation.Eachandeverysuchviolationshallbeaseparateanddistinctoffense,andincaseofacontinuingviolation,everyday’scontinuanceshallbedeemedtobeaseparateanddistinctviolation.G15.UPSETDefinition—“Upset”meansanexceptionalincidentinwhichthereisunintentionalandtemporarynoncompliancewithtechnology-basedpermiteffluentlimitationsbecauseoffactorsbeyondthereasonablecontrolofthePermittee.Anupsetdoesnotincludenoncompliancetotheextentcausedbyoperationalerror,improperlydesignedtreatmentfacilities,inadequatetreatmentfacilities,lackofpreventivemaintenance,orcarelessorimproperoperation.Anupsetconstitutesanaffirmativedefensetoanactionbroughtfornoncompliancewithsuchtechnology-basedpermiteffluentlimitationsiftherequirementsofthefollowingparagrapharemet.APermifteewhowishestoestablishtheaffirmativedefenseofupsetmustdemonstrate,throughproperlysigned,contemporaneousoperatinglogsorotherrelevantevidencethat:1)anupsetoccurredandthatthePermitteecanidentifythecause(s)oftheupset;2)thepermittedfacilitywasbeingproperlyoperatedatthetimeoftheupset;3)thePermitteesubmittednoticeoftheupsetasrequiredinSpecialCondition55.F,and;4)thePermitteecompliedwithanyremedialmeasuresrequiredunderthispermit.Inanyenforcementproceeding,thePermitteeseekingtoestablishtheoccurrenceofanupsethastheburdenofproof.G16.PROPERTYRIGHTSThispermitdoesnotconveyanypropertyrightsofanysort,oranyexclusiveprivilege.G17.DUTYTOCOMPLYThePermitteemustcomplywithallconditionsofthispermit.AnypermitnoncomplianceconstitutesaviolationoftheCleanWaterActandisgroundsforenforcementaction;forpermittermination,revocationandreissuance,ormodification;ordenialofapermitrenewalapplication.ConstructionStonmi’aterGeneralPenn!!—December1,2010Page40 G18.TOXICPOLLUTANTSThePermitteemustcomplywitheffluentstandardsorprohibitionsestablishedunderSection307(a)oftheCleanWaterActfortoxicpollutantswithinthetimeprovidedintheregulationsthatestablishthosestandardsorprohibitions,evenifthispermithasnotyetbeenmodifiedtoincorporatetherequirement.G19.PENALTIESFORTAMPERINGTheCleanWaterActprovidesthatanypersonwhofalsifies,tamperswith,orknowinglyrendersinaccurateanymonitoringdeviceormethodrequiredtobemaintainedunderthispermitshall,uponconviction,bepunishedbyafineofnotmorethan$10,000perviolation,orbyimprisonmentfornotmorethantwoyearsperviolation,orbyboth.Ifaconvictionofapersonisforaviolationcommittedafterafirstconvictionofsuchpersonunderthiscondition,punishmentshallbeafineofnotmorethan$20,000perdayofviolation,orimprisonmentofnotmorethanfour(4)years,orboth.G20.REPORTINGPLANNEDCHANGESThePermitteemust,assoonaspossible,givenoticetoEcologyofplannedphysicalalterations,modificationsoradditionstothepermittedconstructionactivity.ThePermitteeshouldbeawarethat,dependingonthenatureandsizeofthechangestotheoriginalpermit,anewpublicnoticeandotherpermitprocessrequirementsmayberequired.ChangesinactivitiesthatrequirereportingtoEcologyincludethosethatwillresultin:A.Thepermittedfacilitybeingdeterminedtobeanewsourcepursuantto40CFR122.29(b).B.Asignificantchangeinthenatureoranincreaseinquantityofpollutantsdischarged,includingbutnotlimitedto:forsites5acresorlarger,a20%orgreaterincreaseinacreagedisturbedbyconstructionactivity.C.Achangeinoradditionofsurfacewater(s)receivingstormwaterornon-stormwaterfromtheconstructionactivity.D.Achangeintheconstructionplansand/oractivitythataffectsthePermittee’smonitoringrequirementsinSpecialConditionS4.Followingsuchnotice,permitcoveragemaybemodified,orrevokedandreissuedpursuantto40CFR122.62(a)tospecifyandlimitanypollutantsnotpreviouslylimited.Untilsuchmodificationiseffective,anyneworincreaseddischargeinexcessofpermitlimitsornotspecificallyauthorizedbythispermitconstitutesaviolation.Consinwilon&ormi’a1erGeneralPermit—December1,2010Page41 G21.REPORTINGOTHERINFORMATIONWherethePermitteebecomesawarethatitfailedtosubmitanyrelevantfactsinapermitapplication,orsubmittedincorrectinformationinapermitapplicationorinanyreporttoEcology,itmustpromptlysubmitsuchfactsorinformation.G22.REPORTINGANTICIPATEDNON-COMPLIANCEThePermitteemustgiveadvancenoticetoEcologybysubmissionofanewapplicationorsupplementtheretoatleastforty-five(45)dayspriortocommencementofsuchdischarges,ofanyfacilityexpansions,productionincreases,orotherplannedchanges,suchasprocessmodifications,inthepermittedfacilityoractivitywhichmayresultinnoncompliancewithpermitlimitsorconditions.Anymaintenanceoffacilities,whichmightnecessitateunavoidableinterruptionofoperationanddegradationofeffluentquality,mustbescheduledduringnon-criticalwaterqualityperiodsandcarriedoutinamannerapprovedbyEcology.G23.REQUESTSTOBEEXCLUDEDFROMCOVERAGEUNDERTHEPERMITAnydischargerauthorizedbythispermitma)’requesttobeexcludedfromcoverageunderthegeneralpermitbyapplyingforanindividualpermit.ThedischargermustsubmittotheDirectoranapplicationasdescribedinWAC173-220-040orWAC173-216-070,whicheverisapplicable,withreasonssupportingtherequest.Thesereasonswillfullydocumenthowanindividualpermitwillapplytotheapplicantinawaythatthegeneralpermitcannot.Ecologymaymakespecificrequestsforinformationtosupporttherequest.TheDirectorwilleitherissueanindividualpermitordenytherequestwithastatementexplainingthereasonforthedenial.Whenanindividualpermitisissuedtoadischargerotherwisesubjecttotheconstructionstormwatergeneralpermit,theapplicabilityoftheconstructionstormwatergeneralpermittothatPermitteeisautomaticallyterminatedontheeffectivedateoftheindividualpermit.G24.APPEALSA.Thetermsandconditionsofthisgeneralpermit,astheyapplytotheappropriateclassofdischargers,aresubjecttoappealbyanypersonwithin30daysofissuanceofthisgeneralpermit,inaccordancewithChapter43.2lBRCW,andChapter173-226WAC.B.Thetermsandconditionsofthisgeneralpermit,astheyapplytoanindividualdischarger,areappealableinaccordancewithChapter43.218RCWwithin30daysoftheeffectivedateofcoverageofthatdischarger.Considerationofanappealofgeneralpermitcoverageofanindividualdischargerislimitedtothegeneralpermit’sapplicabilityornonapplicabilitytothatindividualdischarger.C.Theappealofgeneralpermitcoverageofanindividualdischargerdoesnotaffectanyotherdischargerscoveredunderthisgeneralpermit.Ifthetermsandconditionsofthisgeneralpermitarefoundtobeinapplicabletoanyindividualdischarger(s),thematterconsinwilonStor,nu’aterGeneralPermit—December1,2010Page42 shallberemandedtoEcologyforconsiderationofissuanceofanindividualpermitorpermits.G25.SEVERABILITYTheprovisionsofthispermitareseverable,andifanyprovisionofthispermit.orapplicationofanyprovisionofthispermittoanycircumstance,isheldinvalid,theapplicationofsuchprovisiontoothercircumstances,andtheremainderofthispermitshallnotbeaffectedthereby.G26.BYPASSPROHIBITEDA.BypassProceduresBypass,whichistheintentionaldiversionofwastestreamsfromanyportionofatreatmentfacility,isprohibitedforstornnvatereventsbelowthedesigncriteriaforstormwatermanagement.EcologymaytakeenforcementactionagainstaPermitteeforbypassunlessoneofthefollowingcircumstances(1,2,3or4)isapplicable.1.Bypassofstormwaterisconsistentwiththedesigncriteriaandpartofanapprovedmanagementpracticeintheapplicablestormwatermanagementmanual.2.Bypassforessentialmaintenancewithoutthepotentialtocauseviolationofpermitlimitsorconditions.Bypassisauthorizedifitisforessentialmaintenanceanddoesnothavethepotentialtocauseviolationsoflimitationsorotherconditionsofthispermit,oradverselyimpactpublichealth.3.Bypassofstormwaterisunavoidable,unanticipated,andresultsinnoncomplianceofthispermit.Thisbypassispermittedonlyif:a.Bypassisunavoidabletopreventlossoflife,personalinjury,orseverepropertydamage.“Severepropertydamage”meanssubstantialphysicaldamagetoproperty,damagetothetreatmentfacilitieswhichwouldcausethemtobecomeinoperable,orsubstantialandpermanentlossofnaturalresourceswhichcanreasonablybeexpectedtooccurintheabsenceofabypass.b.Therearenofeasiblealternativestothebypass,suchastheuseofauxiliarytreatmentfacilities,retentionofuntreatedwastes,maintenanceduringnormalperiodsofequipmentdowntime(butnotifadequatebackupequipmentshouldhavebeeninstalledintheexerciseofreasonableengineeringjudgmenttopreventabypasswhichoccurredduringnormalperiodsofequipmentdowntimeorpreventativemaintenance),ortransportofuntreatedwastestoanothertreatmentfacility.ConstructionStormwaterGeneralPermit—December1,2010Page43 c.EcologyisproperlynotifiedofthebypassasrequiredinSpecialConditionS5.Fofthispermit.4.Aplannedactionthatwouldcausebypassofstormwaterandhasthepotentialtoresultinnoncomplianceofthispermitduringastormevent.ThePermitteemustnotif3’Ecologyatleastthirty(30)daysbeforetheplanneddateofbypass.Thenoticemustcontain:a.adescriptionofthebypassanditscauseb.ananalysisofallknownalternativeswhichwouldeliminate,reduce,ormitigatetheneedforbypassing.c.acost-effectivenessanalysisofalternativesincludingcomparativeresourcedamageassessment.d.theminimumandmaximumdurationofbypassundereachalternative.e.arecommendationastothepreferredalternativeforconductingthebypass.f.theprojecteddateofbypassinitiation.g.astatementofcompliancewithSEPA.h.arequestformodificationofwaterqualitystandardsasprovidedforinWAC173-20lA-I10,ifanexceedanceofanywaterqualitystandardisanticipated.i.stepstakenorplannedtoreduce,eliminate,andpreventreoccurrenceofthebypass.5.Forprobableconstructionbypasses,theneedtobypassistobeidentifiedasearlyintheplanningprocessaspossible.TheanalysisrequiredabovemustbeconsideredduringpreparationoftheStomnvaterPollutionPreventionPlan(SWPPP)andmustbeincludedtotheextentpracEical.Incaseswheretheprobableneedtobypassisdeterminedearly,continuedanalysisisnecessary’uptoandincludingtheconstructionperiodinanefforttominimizeoreliminatethebypass.Ecologywillconsiderthefollowingbeforeissuinganadministrativeorderforthistypebypass:a.Ifthebypassisnecessarytoperformconstructionormaintenance-relatedactivitiesessentialtomeettherequirementsofthispermit.b.Iftherearefeasiblealternativestobypass,suchastheuseofauxiliarytreatmentfacilities,retentionofuntreatedwastes,stoppingproduction,maintenanceduringnormalperiodsofequipmentdowntime,ortransportofuntreatedwastestoanothertreatmentfacility.c.Ifthebypassisplannedandscheduledtominimizeadverseeffectsonthepublicandtheenvironment.ConstructionStonnii’aterGeneralPenileDecember1,2010Page44 Afterconsiderationoftheaboveandtheadverseeffectsoftheproposedbypassandanyotherrelevantfactors,Ecologywillapprove,conditionallyapprove,ordenytherequest.ThepublicmustbenotifiedandgivenanopportuniWtocommentonbypassincidentsofsignificantduration,totheextentfeasible.ApprovalofarequesttobypasswillbebyadministrativeorderissuedbyEcologyunderRCW90.48.120.B.DutytoMitiuateThePermitteeisrequiredtotakeallreasonablestepstominimizeorpreventanydischargeorsludgeuseordisposalinviolationofthispermitthathasareasonablelikelihoodofadverselyaffectinghumanhealthortheenvironment.ConstructionStonmi’a/erGeneralPermit—Dece,nber1,2010Page45 APPENDIXA-DEFINITIONSAKARTisanacronymfor“allknown,available,andreasonablemethodsofprevention,control,andtreatment.”AKARTrepresentsthemostcurrentmethodologythatcanbereasonablyrequiredforpreventing,controlling,orabatingthepollutantsandcontrollingpollutionassociatedwithadischarge.ApplicableTMDLmeansaTMDLforturbidity,tinesediment,highpii,orphosphorus,whichwascompletedandapprovedbyEPAbeforeJanuary1,2011,orbeforethedatetheoperator’scompletepermitapplicationisreceivedbyEcology,whicheverislater.Applicantmeansanoperatorseekingcoverageunderthispermit.BestManagementPractices(BMPs)meansschedulesofactivities,prohibitionsofpractices,maintenanceprocedures,andotherphysical,structuraland/ormanagerialpracticestopreventorreducethepollutionofwatersoftheState.BMPsincludetreatmentsystems,operatingprocedures,andpracticestocontrol:stormwaterassociatedwithconstructionactivity,spillageorleaks,sludgeorwastedisposal,ordrainagefromrawmaterialstorage.Buffermeansanareadesignatedbyalocaljurisdictionthatiscontiguoustoandintendedtoprotectasensitivearea.Bypassmeanstheintentionaldiversionofwastestreamsfromanyportionofatreatmentfacility.CalendarDayAperiodof24consecutivehoursstartingat12:00midnightandendingthefollowing12:00midnight.CalendarWeek(sameasWeek)meansaperiodofsevenconsecutivedaysstartingat12:01a.m.(0:01hours)onSunday.CertifiedErosionandSedimentControlLead(CESCL)meansapersonwhohascurrentcertificationthroughanapprovederosionandsedimentcontroltrainingprogramthatmeetstheminimumtrainingstandardsestablishedbyEcology(seeBMPC160intheSWMM).CleanWaterAct(CWA)meanstheFederalWaterPollutionControlActenactedbyPublicLaw92-500,asamendedbyPublicLaws95-217,95-576,96-483,and97-117;USC1251etseq.CombinedSewermeansasewerwhichhasbeendesignedtoserveasasanitarysewerandastormsewer,andintowhichinflowisallowedbylocalordinance.CommonPlanofDevelopmentorSalemeansasitewheremultipleseparateanddistinctconstructionactivitiesmaybetakingplaceatdifferenttimesondifferentschedulesand/orbydifferentcontractors,butstillunderasingleplan.Examplesinclude:1)phasedprojectsandprojectswithmultiplefilingsorlots,eveniftheseparatephasesorfilings/lotsillbeconstructedunderseparatecontractorbyseparateowners(e.g.,adevelopmentwherelotsaresoldtoseparatebuilders);2)adevelopmentplanthatmaybephasedovermultipleyears,butisstillunderaCons/rite/ionStornni’a/erGeneralPeinillDecember1,2010Page46 consistentplanforlong-termdevelopment;3)projectsinacontiguousareathatmaybeunrelatedbutstillunderthesamecontract,suchasconstructionofabuildingextensionandanewparkinglotatthesamefacility;and4)linearprojectssuchasroads,pipelines,orutilities.Iftheprojectispartofacommonplanofdevelopmentorsale,thedisturbedareaoftheentireplanmustbeusedindeterminingpermitrequirements.CompositeSamplemeansamixtureofgrabsamplescollectedatthesamesamplingpointatdifferenttimes,formedeitherbycontinuoussamplingorbymixingdiscretesamples.Maybe‘time-composite’(collectedatconstanttimeintervals)or“flow-proportional(collectedeitherasaconstantsamplevolumeattimeintervalsproportionaltostreamflow,orcollectedbyincreasingthevolumeofeachaliquotastheflowincreaseswhilemaintainingaconstanttimeintervalbetweenthealiquots.Concretewastewatermeansanywaterusedintheproduction,pouringand/orclean-upofconcreteorconcreteproducts,andanywaterusedtocut,grind,wash,orotherwisemodifyconcreteorconcreteproducts.Examplesincludewaterusedfororresultingfromconcretetrucklmixer/pumper/tool/chuterinsingorwashing,concretesawcuttingandsurfacing(sawing,coring,grinding,roughening,hydro-demolition,bridgeandroadsurfacing).Whenstormwatercomingleswithconcretewastewater,theresultingwaterisconsideredconcretewastewaterandmustbemanagedtopreventdischargetowatersofthestate,includinggroundwater.ConstructionActivitymeanslanddisturbingoperationsincludingclearing,gradingorexcavationwhichdisturbsthesurfaceoftheland.Suchactivitiesmayincluderoadconstruction,constructionofresidentialhouses,officebuildings,orindustrialbuildings,anddemolitionactivity.Contaminantmeansanyhazardoussubstancethatdoesnotoccurnaturallyoroccursatgreaterthannaturalbackgroundlevels.Seedefinitionof“hazardoussubstance”andWAC173-340-200.DemonstrablyEquivalentmeansthatthetechnicalbasisfortheselectionofallstormwaterBMPsisdocumentedwithinaSWPPP,including:I.ThemethodandreasonsforchoosingthestormwaterBMPsselected.2.ThepollutantremovalperformanceexpectedfromtheBMPsselected.3.ThetechnicalbasissupportingtheperformanceclaimsfortheBMPsselected,includinganyavailabledataconcerningfieldperformanceoftheBMPsselected.4.AnassessmentofhowtheselectedBMPswillcomplywithstatewaterqualitystandards.5.AnassessmentofhowtheselectedBMPswillsatisfybothapplicablefederaltechnology-basedtreatmentrequirementsandstaterequirementstouseallknown,available,andreasonablemethodsofprevention,control,andtreatment(AKART).DepartmentmeanstheWashingtonStateDepartmentofEcology.Detentionmeansthetemporarystorageofstormwatertoimprovequalityand/ortoreducethemassflowrateofdischarge.ConstructionStonnii’aterGenera!PermitDecember1,2010Page47 Dewateringmeanstheactofpumpinggroundwaterorstormwaterawayfromanactiveconstructionsite.DirectormeanstheDirectoroftheWashingtonDepartmentofEcologyorhis/herauthorizedrepresentative.DischargermeansanowneroroperatorofanyfacilityoractivitysubjecttoregulationunderChapter90.48RCWortheFederalCleanWaterAct.DomesticWastewatermeanswatercarryinghumanwastes,includingkitchen,bath,andlaundrywastesfromresidences,buildings,industrialestablishments,orotherplaces,togetherwithsuchgroundwaterinfiltrationorsurfacewatersasmaybepresent.EcolouvmeanstheWashingtonStateDepartmentofEcology.EnizineeredSoilsmeanstheuseofsoilamendmentsincluding,butnotlimited,toPortlandcementtreatedbase(CTB).cementkilndust(CKD),orflyashtoachievecertaindesirablesoilcharacteristics.EquivalentBMPsmeansoperational,sourcecontrol,treatment,orinnovativeBMPswhichresultinequalorbetterqualityofstormwaterdischargetosurfacewaterortogroundwalerthanBMPsselectedfromtheSWMM.Erosionmeansthewearingawayofthelandsurfacebyrunningwater,wind,ice,orothergeologicalagents,includingsuchprocessesasgravitationalcreep.ErosionandSedimentControlBMPsmeansBMPsintendedtopreventerosionandsedimentation,suchaspreservingnaturalvegelation,seeding,mulchingandmatting,plasticcovering,filterfences,sedimenttraps,andponds.ErosionandsedimentcontrolBMPsaresynonymouswithstabilizationandstructuralBMPs.FinalStabilization(sameasfullystabilizedorftillstabilization)meanstheestablishmentofapermanentvegetativecover,orequivalentpermanentstabilizationmeasures(suchasriprap,gabionsorgeotextiles)whichpreventserosion.GroundWatermeanswaterinasaturatedzoneorstratumbeneaththelandsurfaceorasurfacewaterbody.HazardousSubstancemeansanydangerousorextremelyhazardouswasteasdefinedinRCW70.105.010(5)and(6),oranydangerousorextremelydangerouswasteasdesignatedbyruleunderchapter70.105RCW:anyhazardoussub-stanceasdefinedinRCW70.105.01004)oranyhazardoussubstanceasdefinedbyruleunderchapter70.105RCW;anysubstancethat,ontheeffectivedateofthissection,isahazardoussubstanceundersection101(14)ofthefederalcleanuplaw,42U.S.C.,Sec.9601(14);petroleumorpetroleumproducts;andanysubstanceorcategoryofsubstances,includingsolidwastedecompositionproducts,determinedbythedirectorConstructionStonmi’alerGeneralPermitDecember1,2010Page48 byruletopresentathreattohumanhealthortheenvironmentifreleasedintotheenvironment.Thetermhazardoussubstancedoesnotincludeanyofthefollowingwhencontainedinanundergroundstoragetankfromwhichthereisnotarelease:crudeoiloranyfractionthereoforpetroleum,ifthetankisincompliancewithallapplicablefederal,state,andlocallaw.InjectionWellmeansawellthatisusedforthesubsurfaceemplacementoffluids.(SeeWell.)Jurisdictionmeansapoliticalunitsuchasacity,townorcounty;incorporatedforlocalself-government.NationalPollutantDischargeEliminationSystem(NPDES)meansthenationalprogramforissuing,modifying,revokingandreissuing,terminating,monitoring,andenforcingpermits,andimposingandenforcingpretreatmentrequirements,undersections307,402,318,and405oftheFederalCleanWaterAct,forthedischargeofpollutantstosurfacewatersoftheStatefrompointsources.ThesepermitsarereferredtoasNPDESpermitsand,inWashingtonState,areadministeredbytheWashingtonDepartmentofEcology.NoticeofIntent(NOl)meanstheapplicationfor,orarequestforcoverageunderthisgeneraLpermitpursuanttoV/AC173-226-200.NoticeofTermination(NOT)meansarequestforterminationofcoverageunderthisgeneralpermitasspecifiedbySpecialConditionSlOofthispermit.Operatormeansanypartyassociatedwithaconstructionprojectthatmeetseitherofthefollowingtwocriteria:•Thepartyhasoperationalcontroloverconstructionplansandspecifications,includingtheabilitytomakemodificationstothoseplansandspecifications;or•Thepartyhasday-to-dayoperationalcontrolofthoseactivitiesataprojectthatarenecessarytoensurecompliancewithaSWPPPforthesiteorotherpermitconditions(e.g.,theyareauthorizedtodirectworkersatasitetocarryoutactivitiesrequiredbytheSWPPPorcomplywithotherpermitconditions).Permitteemeansindividualorentitythatreceivesnoticeofcoverageunderthisgeneralpermit.nilmeansaliquid’smeasureofacidityoralkalinity.ApHof7isdefinedasneutral.Largevariationsaboveorbelowthisvalueareconsideredharmfultomostaquaticlife.pHmonitoringperiodmeansthetimeperiodinwhichthepHofstormwaterrunofffromasitemustbetestedaminimumofonceeverysevendaystodetermineifstormwaterpHisbetween6.5and8.5.Pointsourcemeansanydiscernible,confined,anddiscreteconveyance,includingbutnotlimitedto,anypipe,ditch,channel,tunnel,conduit,well,discretefissure,andcontainerfromwhichpollutantsareormaybedischargedtosurfacewatersoftheState.Thistermdoesnotincludereturnflowsfromirrigatedagriculture.(SeeFactSheetforfurtherexplanation.)ConstructionStornni’aterGeneralPermit—Decenther1,2010Page49 Pollutantmeansdredgedspoil,solidwaste,incineratorresidue,filterbackwash,sewage.garbage,domesticsewagesludge(biosolids),munitions,chemicalwastes,biologicalmaterials,radioactivematerials,heat,wreckedordiscardedequipment,rock,sand,cellardirt,andindustrial,municipal,andagriculturalwaste.Thistermdoesnotincludesewagefromvesselswithinthemeaningofsection312oftheCWA,nordoesitincludedredgedorfillmaterialdischargedinaccordancewithapermitissuedundersection404oftheCWA.Pollutionmeanscontaminationorotheralterationofthephysical.chemical,orbiologicalpropertiesofwatersoftheState;includingchangeintemperature,taste,color,turbidity,orodorofthewaters;orsuchdischargeofanyliquid,gaseous,solid,radioactiveorothersubstanceintoanywatersoftheStateaswillorislikelytocreateanuisanceorrendersuchwatersharmful,detrimentalorinjurioustothepublichealth,safetyorwelfare;ortodomestic,commercial,industrial,agricultural,recreationM,orotherlegitimatebeneficialuses;ortolivestock,wildanimals,birds,fishorotheraquaticlife.Processwastewatermeansanywaterwhich,duringmanufacturingorprocessing,comesintodirectcontactwithorresultsfromtheproductionoruseofanyrawmaterial,intermediateproduct,finishedproduct,byproduct,orwasteproduct(40CER122.1).Receivinuwatermeansthewaterbodyatthepointofdischarge.Ifthedischargeistoastormsewersystem,eithersurfaceorsubsurface,thereceivingwateristhewaterbodytowhichthestormsystemdischarges.Systemsdesignedprimarilyforotherpurposessuchasforgroundwaterdrainage,redirectingstreamnaturalflows,orforconveyanceofirrigationwater/returnflowsthatcoincidentallyconveystormwaterareconsideredthereceivingwater.Representativemeansastormwaterorwastewatersamplewhichrepresentstheflowandcharacteristicsofthedischarge.Representativesamplesmaybeagrabsample,atime-proportionatecompositesample,oraflowproportionatesample.Ecology’sConstructionStormwaterMonitoringManualprovidesguidanceonrepresentativesampling.Sanitarysewermeansasewerwhichisdesignedtoconveydomesticwastewater.Sedimentmeansthefragmentedmaterialthatoriginatesfromtheweatheringanderosionofrocksorunconsolidateddeposits,andistransportedby,suspendedin,ordepositedbywater.Sedimentationmeansthedepositingorformationofsediment.Sensitiveareameansawaterbody,wetland,stream,aquiferrechargearea,orchannelmigrationzone.SEPA(StateEnvironmentalPolicyAct)meanstheWashingtonStateLaw,RCW43.21C.020,intendedtopreventoreliminatedamagetotheenvironment.ShznificantAmountmeansanamountofapollutantinadischargethatisamenabletoavailableandreasonablemethodsofpreventionortreatment;oranamountofapollutantthathasaConstructionStornni’aterGeneralPermitDecember1,2010Page50 reasonablepotentialtocauseaviolationofsurfaceorgroundwaterqualityorsedimentmanagementstandards.Significantconcreteworkmeansgreaterthan1000cubicyardspouredconcreteorrecycledconcreteoverthelifeofaproject.SignificantContributorofPollutantsmeansafacilitydeterminedbyEcologytobeacontributorofasignificantamount(s)ofapollutant(s)towatersoftheStateofWashington.meansthelandorwaterareawhereanyfacilityoractivity’isphysicallylocatedorconducted.SourcecontrolBMPsmeansphysical,structuralormechanicaldevicesorfacilitiesthatareintendedtopreventpollutantsfromenteringstormwater.AfewexamplesofsourcecontrolBMPsareerosioncontrolpractices,maintenanceofstormwaterfacilities,constructingroofsoverstorageandworkingareas,anddirectingwashwaterandsimilardischargestothesanitaryseweroradeadendsump.StabilizationmeanstheapplicationofappropriateBMPstopreventtheerosionofsoils,suchas,temporaryandpermanentseeding,vegetativecovers,mulchingandmatting,plasticcoveringandsodding.SeealsothedefinitionofErosionandSedimentControlBMPs.Stormdrainmeansanydrainwhichdrainsdirectlyintoastormsewersystem,usuallyfoundalongroadwaysorinparkinglots.Stormsewersystemmeansameansaconveyance,orsystemofconveyances(includingroadswithdrainagesystems,municipalstreets,catchbasins,curbs,gutters,ditches,manmadechannels,orstormdrainsdesignedorusedforcollectingorconveyingstormwater.ThisdoesnotincludesystemswhicharepartofacombinedsewerorPubliclyOwnedTreatmentWorks(POTW)asdefinedat4OCER122.2.Stormwatermeansthatportionofprecipitationthatdoesnotnaturallypercolateintothegroundorevaporate,butflowsviaoverlandflow.interfiow.pipes,andotherfeaturesofastormwaterdrainagesystemintoadefinedsurfacewaterbody,oraconstructedinfiltrationfacility.StormwaterMananementManual(SWMM)orManualmeansthetechnicalManualpublishedbyEcologyforusebylocalgovernmentsthatcontaindescriptionsofanddesigncriteriaforBMPstoprevent,control,ortreatpollutantsinstormwater.StormwaterPollutionPreventionPlan(SWPPP)meansadocumentedplantoimplementmeasurestoidentify,prevent,andcontrolthecontaminationofpointsourcedischargesofstormwater.SurfaceWatersoftheStateincludeslakes,rivers,ponds,streams,inlandwaters,saltwaters,andallothersurfacewatersandwatercourseswithinthejurisdictionofthestateofWashington.ConstructionS/ornni’aierGeneralPermitDecember1,2010Page51 TemporaryStabilizationmeanstheexposedgroundsurfacehasbeencoveredwithappropriatematerialstoprovidetemporarystabilizationofthesurfacefromwaterorwinderosion.Materialsinclude,butarenotlimitedto,mulch.riprap,erosioncontrolmatsorblanketsandtemporarycovercrops.Seedingaloneisnotconsideredstabilization.Temporarystabilizationisnotasubstituteforthemorepermanent“finalstabilization.”TotalMaximumDailyLoad(TMDLmeansacalculationofthemaximumamountofapollutantthatawaterbodycanreceiveandstillmeetstatewaterqualitystandards.Percentagesofthetotalmaximumdailyloadareallocatedtothevariouspollutantsources.ATMDListhesumoftheallowableloadsofasinglepollutantfromallcontributingpointandnonpointsources.TheTMDLcalculationsmustincludea“marginofsafety”toensurethatthewaterbodycanbeprotectedincasethereareunforeseeneventsorunknownsourcesofthepollutant.Thecalculationmustalsoaccountforseasonablevariationinwaterquality.TreatmentBMPsmeansBMPsthatareintendedtoremovepollutantsfromstormwater.AfewexamplesoftreatmentBMPsaredetentionponds,oil/waterseparators,biofiltration,andconstructedwetlands.Transparencymeansameasurementofwaterclarityincentimeters(cm),usinga60cmtransparencytube.ThetransparencytubeisusedtoestimatetherelativeclarityortransparencyofwaterbynotingthedepthatwhichablackandwhiteSecehidiscbecomesvisiblewhenwaterisreleasedfromavalueinthebottomofthetube.Atransparencytubeissometimesreferredtoasa“turbiditytube.”Turbiditymeanstheclarityofwaterexpressedasnephelometricturbidityunits(NTV)andmeasuredwithacalibratedturbidimeter.Uncontaminatedmeansfreefromanycontaminant,asdefinedinMICAcleanupregulations.Seedefinitionof“contaminant”andWAC173-340-200.WasteLoadAllocation(WLA)meanstheportionofareceivingwater’sloadingcapacitythatisallocatedtooneofitsexistingorfuturepointsourcesofpollution.WLAsconstituteatypeofwaterqualitybasedeffluentlimitation(40CER130.2[h]).Waterqualitymeansthechemical,physical,andbiologicalcharacteristicsofwater.usuallywithrespecttoitssuitabilityforaparticularpurpose.WatersoftheStateincludesthosewatersasdefinedas“watersoftheUnitedStates”in40CFRSubpart122.2withinthegeographicboundariesofWashingtonStateand“watersoftheState”asdefinedinChapter90.48RCW,whichincludelakes,rivers,ponds,streams,inlandwaters,undergroundwaters,saltwaters,andallothersurfacewatersandwatercourseswithinthejurisdictionofthestateofWashington.Wellmeansabored,drilledordrivenshaft,ordugholewhosedepthisgreaterthanthelargestsurfacedimension.(SeeInjectionwell.)ConstructionStornni’aterGeneralPermitDecember1,2010Page52 Wheelwashwastewatermeansanywaterusedin,orresultingfromtheoperationofatirebathorwheelwash(BMPCl06:WheelWash),orotherstructureorpracticethatuseswatertophysicallyremovemudanddebrisfromvehiclesleavingaconstructionsiteandpreventtrack-outontoroads.Whenstormwatercomingleswithwheelwashwastewater,theresultingwaterisconsideredwheelwashwastewaterandmustbemanagedaccordingtoSpecialConditionS9.D.9.Construe/ionS/ormn’alerGeneralPermitDecember1,2010Page53 APPENDIXB-ACRONYMSAKARTAllKnow-n,Available,andReasonableMethodsofPrevention,Control,andTreatmentBMPBestManagementPracticeCESCLCertifiedErosionandSedimentControlLeadCFRCodeofFederalRegulationsCKDCementKilnDustcmCentimetersCTBCement-TreatedBaseCWACleanWaterActDMRDischargeMonitoringReportEPAEnvironmentalProtectionAgencyESCErosionandSedimentControlFRFederalRegisterNOlNoticeofIntentNOTNoticeofTerminationNPDESNationalPollutantDischargeEliminationSystemNTUNephelometdcTurbidityUnitRCWRevisedCodeofWashingtonSEPAStateEnvironmentalPolicyActSWMMStormwaterManagementManualSWPPPStonrnvaterPollutionPreventionPlanTMDLTotalMaximumDailyLoadUICUndergroundInjectionControlUSCUnitedStatesCodeUSEPAUnitedStatesEnvironmentalProtectionAgencyWACWashingtonAdministrativeCodeWQWaterQualityWWIlMWesternWashingtonHydrologyModelConstructionStornzi,’aterGeneralPermitDecember1,2010Page54 AppendixFEngineeringCalculationsEXISTINGSITEHYDROLOGYWWHM2O12wasusedtomodelthepeakrunofffromtheSite.PerTable3.2.2.boftheManualthesoiltypeismodeledas“Outwash”fortheEverettgravellysandyloamSCSclassification.TheentireSite,withtheexceptionoftheupstreamtributaryarea,ismodeledas‘Forest.”ResultsoftheWWHM2O12analysisareincludedinthissection.TDANorthPre-developedHourlyTimeStepModelingInput:PREDEVELOPEDLANDUSENameTDANorthPredevelopedBypass:NoGroundwater:NoPerviousLandUseAcresAB,Forest,Flat0.435PeMousTotal0.435ImperviousLandUseAcresImperviousTotal0BasinTotal0.435TDANorthPre-developedHourlyTimeStepModelingOutput:FlowFrequencyReturnPeriodsforPredeveloped.POC#1ReturnPeriodFlow(cfs)2year0,0000925year0.00014610year0.00019225year0.0002650year0.000321100year0.00039DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageF-2 TDASouthPre-developedHourlyTimeStepModelingInput:PREDEVELOPEDlANDUSEName:TDASouthPredevelopedBypass:NoGroundwater:NoPerviousLandUseAcresAB,ForestFlat8.771C,Lawn,FIat0.12PeMousTotal8.891ImperviousLandUseAcresROOFTOPSFIAT0.05DRIVEWAYSFLAT0.055ImperviousTotal0.105BasinTotal8.996TDASouthPre-developedHourlyTimeStepModelingOutput:FlowFrequencyReturnPeriodsforPredeveloped.POCflReturnPeriodFlow(cfs)2year0.0329715year0.04459410year0.05344225year0.06601350year0.076444100year0.087842SedimentTrapFacilitySizingTheSitewillutilizetwosedimenttrapsforsedimentcontrol.Themaximumdischargerateforthesiteis00165cfs(50%ofthe2-yearpredevelopedpeak).ThesedimenttrapswilldischargetotheinfiltrationpondinTractB.Belowissizingsummary:SedimentTrap1:2.953acres2yearpeakflowrate:0.715cfsRequiredSurfaceArea:1,487s.f.ProvidedSurfaceArea:2,000s.f.SedimentTrap2:2.659acres2yearpeakflowrate:0.612cfsRequiredSurfaceArea:1,273s.f.ProvidedSurfaceArea:1,800s.f.DR.STRONGConsultingEngineers,Inc.AlpineNurseryStormwaterPollutionPreventionPlanPageF-2 APPENDIX“D”BONDQUANTITYWORKSHEET©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage71TechnicalInformationReportCityofRenton Site Improvement Bond Quantity Worksheet King County Department of Development &Environmental Services 900 Qakesdale Avenue Southwest Renton,Washington 98057-5212 206-296-6600 Tn’206-296-7217 Project Name: Location: Alpine Nursery Renton Date: Project No.: 8-Mar-16 14069 Page 1 of 9 Activity No.: Note:All prices include labor,equipment,materials,overhead and profit.Prices are from RS Means data adjusted for the Seattle area or from local sources if not included in the RS Means database. Unit prices updated:02/12/02 Version:11/26/2008 Report Date:7/28/2016 C Web dale:‘DL2008 For alternate formats,call 206-296-6600. Clearing greater than or equal to 5,000 board feet of timber? X yes If yes, Forest Practice Permit Number (RCW 76.09) no TBD Bond Quantity Worksheetl4O69xlsx Web dale:2/20O8SiteImprovementBondQuantityWorksheet l_Jriit u: Reference#Price Unit Quantity Applications Cost EROSIONISEDIMENT CONTROL Number Backfill &compaction-embankment ESC-1 $5.62 CV Check dams,4”minus rock ESC-2 SWDM 5.4.6.3 $67.51 Each 32 1 2160 Crushed surfacing 1 1/4”minus ESC-3 WSDOT 9-03.9(3)$85.45 CV Ditching ESC4 $8.08 CV 230 1 1858 Excavation-bulk ESC-5 $1.50 CV Fence,silt ESC-6 SWDM 5.4.3.1 $1.38 LF 2365 1 3264 Fence,Temporary (NGPE)ESC-7 $1.38 LF 600 1 828 Hydroseeding ESC-8 SWDM 5.4.2.4 $0.59 SV 29515 1 17414 Jute Mesh ESC-9 SWDM 5.4.2.2 $1.45 SY Mulch,by hand,straw,3”deep ESC-10 SWDM 5.4.2.1 $2.01 SY Mulch,by machine,straw.2”deep ESC-1l SWDM 5.4.2.1 $0.53 SY 29515 1 15643 Piping,temporary,CPP,6”ESC-12 $10.70 LF Piping,temporary,CPP,8”ESC-13 $16.10 LF Piping,temporary,CPP,12”ESC-14 $20.70 LF 335 1 6935 Plastic covering,6mm thick,sandbagged ESC-15 SWDM 5.4.2.3 $2.30 SY 885 1 2036 Rip Rap,machine placed;slopes ESC-16 WSDQT 9-I 3.1(2)$39.08 CV Rock Construction Entrance,50’xlS’xl’ESC-17 SWDM 5.4.4.1 $1,464.34 Each Rock Construction Entrance,l00’xlS’xl’ESC-18 SWDM 5.4.4.1 $2,928.68 Each 1 I 2929 Sediment pond riser assembly ESO-IS SWDM 5.4.5.2 $1,949,38 Each Sediment trap,5’high berm ESC-20 SWDM 5.4.5.1 $17.91 LF 325 1 5821 Sed.trap,5’high,riprapped spilk’ay berm section ESC-21 SWOM 5.4.5.1 $68,54 LF 6 1 411 Seeding,by hand ESC-22 SWOM 5.4.2.4 $0,51 SY Sodding,1”deep,level ground ESC-23 SWDM 5.4.2,5 S 6.03 SY Sodding.1”deep,sloped ground ESC-24 SWDM 5.4.2.5 $7.45 SY TESC Supervisor ESC-25 $74.75 HR 12 1 897 Water truck,dust control ESC-26 SWDM 5.4.7 $97.75 HR 2 4 782 WRITE-IN-ITEMS stl**(see uaueê% Inlet Protection Grate $25.00 Each 47 1 1175 ESU SUBTOTAL:$62,151.89 30%CONTINGENCY &MOBILIZATION:$18,645.57 ESC TOTAL:S 80,797.46 COLUMN:A Page 2 of 9 Unit prices updated:02/12/02 Version:11/26/2008 Bond Quantity Worksheetl4069,xlsx Report Dale:7/28/2016 .Site Improvement Boc%Quantity Worksheet Web dtV)2J2O08 GEE1EIRL.I1Er4S : Backfill &Compaction-embankment Cl-i $562 CV 7000 39,340.00 2698 1516276 Backfill &Compaction-trench 01-2 $853 CV 10 85.30 1850 15,780.50 Clear/Remove Brush,by hand 01-3 $0.36 SY Cleadng/Gmbbingffree Removal 01-4 $8,876.16 Acre 2.5 22,190.40 6.3 55,919.81 Excavation -bulk Cl-S $1.50 CV 7000 10500.00 2698 4,047.00 Excavation -Trench Cl-S $4.06 CV 10 40,60 1850 7.511 .00 Fencing,cedar,6’high 01-7 $18.55 LF Fencing,chain link,vinyl coated,6’high Cl-S $13.44 LF 550 7,392.00 Fencing,chain link,gate,vinyl coated,01-9 $1,271.81 Each 1 1,271.81 Fencing,split rail,3’high 01-10 $12.12 LF Fill &compact -common barrow Cl-li $22.57 CV 12000 270,840.00 5494 123,999.58 Fill &compact -gravel base 01-12 $25.48 CV Fill &compact -screened topsoil 01-13 $37.85 CV Gabion,1 2”deep,stone filled mesh 01-14 $54.31 SY Gabion,15”deep,stone filled mesh Cl-IS $74.85 SY Gabion,36”deep,stone filled mesh Cl-iS $132.48 SY Grading,fine,by hand 01-17 $2.02 SV Grading,fine,with grader 01-18 $0.95 SV Monuments,3’long 01-19 $135.13 Each 1 135.13 15 2,026.95 Sensitive Areas Sign 01-20 $2.88 Each Sodding,1”deep,sloped ground 01-21 $7.45 SV Surveying,line &grade 01-22 $788.26 Day 5 3,941.30 Surveying,lot locationflines 01-23 $1,556,64 Acre 6,3 9,806.83 Traffic control crew (2 flaggers)01-24 $85.18 HR 120 10,221.60 Trail,4”chipped wood 01-25 S 7.59 SV Trail,4”crushed cinder 01-26 $8.33 SY Trail,4”top course 01-27 $8.19 SV Wall.retaining,concrete 01-28 $44.16 SF 1368 60,410.88 Wall,rockery 01-29 $9.49 SF 150 1,423.50 Page 3 of 9 SUBTOTAL 10,482,63 437,263.54 214,300.78 Unit Price Future Public £- Right of Way bc÷ Private Improvements Quantity Completed (Bond Reduction)* Cost Quant. Coihplete Cost Unit prices updated:02/12/02 Version:11/26/08 Report Date:7/28/2016 KCC 27A authorizes only one bond reduction. Bond Quantity Worksheetl4o69,xlsx 0V3UCDCD0CD3CDSa0CDS001VSCDCDCD00NCDaSCD0aCDCD00CDCDCDSCDCDU3-CDCD3-UCaCDCDCDCD3-00VSa5-CD0VCDCD0a’00I0CDCDa5-CDCA)aCDa5-0CU-CDCaCDa00S0CDCD0CU-CDCaCDaCDCoU5-CD0CCD0CDaCD-CSCD000S0CDCDSCDaCDV3-0CUQQ0CCDCCD0CD0CaQocmCCD0CDaCD05-0CaCD>0CDCDCD00CDaCS-o0CDCCD0CDaCD-CUCD-DCD3CDSCDS0CD30CCDCa0CDCDCDVCD0C0CDSa0CCDaCD300SCDSaaCAU0CDCD0cmSaSCDaCD3CD05-SCDVN)000Ca-C0cmSaSCDaCD3CD05-SCD009N)CCC0cmSaSCDaCD3CD05-SCDA0CCCa-C0.0t-UCDCDCD2,CD0CCH0(A)(0CCCCD—I100—IN)CDpCCC*soa0ON)C1CD5-2?CCDWCD5-0.DA0o5aCDCDCDaC00CS-oCDCDa—oCDN)-Lo2.t2-‘CO6,6’606,6,6’6,6’6’6’6’6’6,6,6,6,6,6,6,6,6,6’6,OWN)W-’-A-ACA)O-AN)N)0N)CDCDCD00MflOCDCCD000CD000CD©N)000OCCDCDCD0000001C00000r00000O0rrrrrrr-rrroooo“‘10-<-<-<-<-<-<,1‘1‘1mmmmmmm-<-<-<-<N)CA)01fl.0)CDOOfl..4CDCDCDOC0CDCDC00CCfl.-AN)9)9)9)91C.fl.--A00)-AN)•JCDOCP0CD(00000N)C00CCCCDCDC0000-A-fiN)—JCD0)0CC0)CD-AD-A0)CO0)0)N)CDN)0CDC100C00000C0C00N)CDCbCCoCDBV-‘0CDBCDz-I030t0Ca)D-I0—S‘cci,Z3CDCDP0-E.ooCDIlL‘C4oQC—_n0—30o2—ft .Site Improvement Borg Quantity Worksheet Web dateC2I2008 Future Public Right of Way &Drainage Facilities Cost Quart I Cost Private Improvements S Quanl I Cost Unit prices updated:02/12/02 Version:11/26/08 Report Date:7/28/2016 Existing Right-of-way Unit Price Unit Quant I a ROADSURFACING &k=2&bas &l 5”topeourse)Pot3KCRS(65”Rock=SThase&l 5’”topcourse) Comp1 Cost For KCRS ‘93,(additional 2.5”base)add:RS-1 $3.60 SY AC Overlay.1.5”AC RS-2 $1125 SY AC Overlay,2 AC RS-3 $15.00 SY 2950 44.25000 AC Road,7,4 rock.First 2500 SY RS-4 $21.00 SY AC Road.2,4’rock.Qty.over 2500SY RS-5 $1900 SY AC Road,3”.4”rock,First 2500 SY RS-6 $23.30 SY 2500 58250.00 AC Road,3”,4”rock,Qty.over 2500 SY RS-7 $21.00 SY 4330 90.93000 AC Road,5”,First 2500 SY RS-8 $27.60 SY AC Road.5”,Qty.Over 2500 SY RS-9 $25.00 SY AC Road,6”,First 2500 SY RS-1($33.10 SY 55 1820.50 AC Road,6”,Oty.Over 2500SY S -t $30.00 SI Asphalt Treated Base.4”thick RS-t $20.00 SY Gravel Road,4”rock,First 250031 RS-t $15.00 SY Gravel Road.4’rock,Oty.over 2500 SY RS-1’$8.50 SY PCC Road,5,no base,over 2500 SY RS-V $27.00 SY PCC Road,6’,no base,over 2500 SY RS-1($25.50 SY Thickened Edge RS-i $8,60 LF PageS of 9 SUBTOTAL 46,070.50 149,1 80D KCC 27A authorizes only one bond reduction. Bond Quantity Worksheetl4o69.xlsx .Site Improvement Boç Quantity Worksheet Web data/2/2008 Page 6 of 9 SUBTOTAL 5.039,87 87,193.58 34,094.76 _______________ Unit prices updated:02/12/02 DRAINAGE (CPP =Corw ia’PW,N12 o of 4’coverwasassomécLMiumapi&bd PVC is same Access Road,R/D D-1 $21.00 SY 166 3,486.00 Bollards -fixed 0-2 $240.74 Each Bollards -removable 0-3 $45234 Each (CBs include frame and lid) CBType I 0-4 $1,257.64 Each 17 21,379.88 9 11,318.76 CB Type IL 0-5 $1,433.59 Each 2 2,867.18 CS Type II,48”diameter 0-6 $2,033.57 Each 1 2,033.57 14 28,469.98 for additional depth over 4’D-7 $436.52 FT 1.5 654.78 19.5 8,512,14 CS Type II,54”diameter 0-8 $2,192.54 Each for additional depth over 4’D-9 $486.53 FT CB Type II.60”diameter 0-10 $2.351 .52 Each 1 2,351.52 1 2.351 .52 for additional depth over 4’0-11 $536.54 FT CS Type II,72”diameter 0-12 $3.21264 Each for additional depth over 4’D-13 $692.21 FT Through-curb Inlet Framework (Add)0-14 $36609 Each 6 2.196,54 Cleanout,PVC,4”0-15 $1 30.55 Each Cleanout,PVC.6”0-16 $174.90 Each 20 3.49800 Cleanout,PVC.8”0-17 $224.19 Each Culvert,PVC.4”0-18 $8.64 LF Culvert,PVC,6”D-19 $12.60 LF 1530 19,278.00 Culvert,PVC.8”D-20 $13.33 LF Culvert,PVC.17’D-21 $21.77 LF Culvert.CMP.8”0-22 $17.25 LF Culvert,CMP.17’0-23 $26.45 LF 120 3,174.00 Culvert.CMP,15 0-24 $32.73 LF Culvert,CMI’,18”0-25 $37.74 LF 391 14,756.34 Culvert,CMP,24”0-26 $53.33 LF Culvert,CMP,30”0-27 $71.45 LF Culvert,CMP,36”0-28 $112.11 LF Culvert,CMI’,48”0-29 $140.83 LF Culvert,CMI’,60”0-30 $235.45 LF Culvert,CMP,72”0-31 $302.58 LF KCC 27A authorizes only one bond reduction. Bond Quantity Worksheetl4O69.xlsx Version:11/26/08 Report Date:7/28/2016 .Site Improvement BoCS Quantity Worksheet Web date:,A-0)2]2008 Private Bond R4ction Improvements Unit prices updated:02112102 Version:11/26/06 Report Date:7/28/2016 Culvert.Concrete,8”0 -32 No.IiJn*Pnce I Unit I Quant $21.02 LF Quanil iant.I Cost Camisole!-Cost Culvert,Concrete,12”0-33 $30.05 LF Culvert,Concrete,15’D-34 $37.34 LF Culvert.Concrete.18”0-35 $44.51 LF Culvert.Concrete,24”0-36 $61.07 LF Culvert.Concrete.30”0-37 $104.18 LF Culvert,Concrete.36”0-38 $137.63 LE Culvert,Concrete,42”0-39 $158,42 LE Culvert,Concrete,48”D-40 $175.94 LF Culvert,CPP.6”D-41 $1070 LF Culvert,CPP,8”0-42 $16.10 LF Culvert,CPP,12”D-43 $20.70 LF 37 765.9 1188 24591.6 Culvert,CPP,15”D-44 $23.00 LF Culvert,CPP,18”0-45 $27.60 LF 484 13358.4 Culvert,CPP,24”D-46 $36.80 LE 300 11040 Culvert,CPP.30”D-47 $48.30 LF Culvert,CPP,36”0-48 $55.20 LF Ditching 0-49 $8.08 CV Flow Dispersal Trench (1,436 base.)U-SO $25.99 LF 20 1955.8 French Drain (3’depth)U-Si $22.60 LF Ceotextile,laid in trench,polypropylene D-52 $2.40 SY Infiltration pond testing D-53 $74.75 HR 12 897 Mid-tank Access Riser,48”dia.6’deep D-54 $1,605.40 Each Pond Overflow Spillway 0-55 $14.01 SY 12 168.12 Restrictor/Oil Separator.12”0-56 $1,045.19 Each RestñctorlOil Separator,15”0-57 $1,095.56 Each RestrictorlOil Separator,18”0-58 $1,146.16 Each Riprap.placed 0-59 $39.08 CY 5 195.4 Tank End Reducer (36”diameter)0-60 $1,000.50 Each Trash Rack,12”D-61 $211.97 Each Trash Rack,15”D-62 $237.27 Each Trash Rack,18”D-63 $268.89 Each Trash Rack,21’D-64 $306.84 Each Page7of9 SUBTOTAL 765.9 52206.32 •KCC 27A authorizes only one bond reduction, Bond Quantity Worksheetl4o69.xlsx .Site Improvement Bo(Quantity Worksheet Web date:2I20o8 Page 8 of 9 SUBTOTAL (SUM ALL PAGES): Unit prices updated: Version: Report Date: 02/12)02 11/26/08 7/28)2016 ,rPrtce Existing Right-of-way Urilt :QUant I Future Public Right of Way 4::::[:&Drainage Facilities Price I Quant Private Improvements Cost Quant I Bond Cost. Quant. Complete Cost I UP-2 $3000.00 lEACH I 10,000.00 I RkiI%IGLO1”SURFACING No. 2’AC.2”top course rock &4”borrow PL-1 $21.00 SY 2’AC.1.5”top course &2.5’base cour PL-2 $28.00 SY 4”select borrow PL-3 $4.55 SY 1.5”top course rock &2.5’base course PL-4 $11.41 SY UTILITY POLES £STREET LIGHTING Ulihity pole re(ocatton costsmustbe aceompnied by Franchise Utililjs Cost Statement Utility Pole(s)Relocation I UP-i I $ Street Light Poles wlLuminaiTes 4 12000 36 108000.00 (Such as detention/water quality vaults.)Nc Utility Pole Relocation WI-i $10,000.00 Each 3 30000 Wl-2 Each Wet Biofiltration Swale Wl-3 S 20.00 I.E 130 2,600.00 Wl-4 LE WI -5 WI -6 WI -7 WI-s WI -9 WI -10 SUBTOTAL 42000.00 110,600.00 30%CONTINGENCY &MOBILIZATION:65,458,47 293.22553 96,793.66 GRANDTOTAL:283,653.37 1.270,643.97 419,439.20 218,194.90 977.41844 322,645.54 COLUMN:B C D E KCC 27A authorizes only one bond reduction. Bond Quantity Worksheetl 4069.xlsx C Site Improvement Bond Quantity Worksheet Web date:‘t/2008 Original bond computations prepared by: Name; PE Registration Number; Firm Name: Address: MaherA.Joudi 45232 DR STRONG Consulting Engineers,Inc. 620 7th Avenue,Kirkland,WA 98033 Date; Tel.#: Project No: 8-Mar-16 (425)827-3063 14069 Stabilization/Erosion Sediment Control (ESC) Existing Right-of-Way Improvements Future Public Right of Way &Drainage Facilities Private Improvements Calculated Quantity Completed Total Right-of Way and/or Site Restoration Bond’/t (First $7,500 of bond’shall be cash.) Performance Bond*Amount (A÷B+C÷D)=TOTAL Reduced Performance Bond’Total Maintenance/Defect Bond’Total DRAINAGE FACILITIES FINANCIAL GUARANTEE REQUIREMENTS PUBLIC ROAD &DRAINAGEBONDAMOUNTMAINTENANCE/DEFECT BoND’REQUIRED AT RECORDING OR TEMPORARY OCCUPANCY $ $616,360.2 (r-E)$2,054,534.0 Use larger of Tx30%or (T-E) NAME OF PERSON PREPARING BOND’REDUCTION: *NOTE: **NOTE; Yoshio Piediscaizi,E.I.T.Date:9/23/2015 REQUIRED BOND’AMOUNTS ARE SUBJECT TO REVIEW AND MODIFICATION BY DDES Page 9 of g Check out the DDES Web site at www.kingcounty.govlyermits Unit prices updated:02112102 Version:11/26/08 Report Date:7/28/2016 ROAD IMPROVEMENTS & PERFORMANCE BOND’ AMOUNT (A) (B) (C) (D) (A+B) CO S 80,797.5 $283,653.4 S 1.270,644.0 $419439.2 $364,450.8 S 2,054,534.0 Minimum bond’amount is $2000. (E) T x 0.30 OR NOTE; (B+C)x 025=$388,574.3 The word “bond”as used in this document means a financial guarantee acceptable to King County. KCC 27A authorizes right of way and site restoration bonds to be combined when both are required. The restoration requirement shall include the total cost for all TESC as a minimum,not a maximum.In addition,corrective work,both on-and off-site needs to be included. Quantities shall reflect worse case scenarios not just minimum requirements.For example,if a salmonid stream may be damaged,some estimated costs for restoration needs to be renected in this amount.The 30%contingency and mobilization costs are computed in this quantity. Per KCC 27A,total bond amounts remaining after reduction shall not be less than 30%of the original amount r)or as revised by major design changes. Bond Quantity Worksheetl 4069.xlsx APPENDIX“E’OPERATIONSANDMAINTENANCEMANUAL©20160.R.STRONGConsultingEngineersInc.AlpineNurseryPage72TechnicalInfornmtionReportCityofRenton APPENDIXAMAINTENANCEREQUIREtvNTSFORFLOWCONTROL,CONVEYANCE,ANDWQFACILITSNO.2—INFILTRATIONFACILITIESMaintenancejDefectorProblemConditionsWhenMaintenanceIsNeededResultsExpectedWhenComponentMaintenanceIsPerformedSiteTrashanddebrisAnytrashanddebriswhichexceedIcubicfootTrashanddebrisclearedfromsite.per1DUOsquarefeet(thisisaboutequaltotheamountoftrashitwouldtaketofilluponestandardsizeofficegarbagecan).Ingeneral,thereshouldbenovisualevidenceofdumping.NoxiousweedsAnynoxiousornuisancevegetationwhlcbmayNoxiousandnuisancevegetationconsUtuteahazardtoCountypersonn&ortheremovedaccordingtoapplicablepublic,regulations.NodangerofnoxiousvegetationwhereCountypersonnelorthepublicmightnormallybe.ContaminantsandAnyevidenceofcontaminantsorpollutionsuchMaterialsremovedanddisposedofpollutionasoil,gasoline,concreteslurriesorpaint,accordingtoapplicableregulations.SourcecontrolBMPsimplementedifappropriate.Nocontaminantspresentotherthanasurfaceohfilm.Grass/groundcoverGrassorgroundcoverexceeds18inchesinGrassorgroundcovermowedtoaheighLheightnogreaterthan8Inches.InfiltrationPond,TopRodentholesAnyevidenceofrodentholesiffacilityisactingRodentsremovedordestroyedandorSideSlopesofasadamorberm,oranyevidenceofwaterdamorbermrepaired.Dam,Bermorpipingthroughdamorbermviarodentholes.Embankment.-TreegrowthTreegrowththreatensintegntyofdams,beansorTreesdonothinderfacIlityslopes,doesnotallowmaintenanceaccess,orperformanceormaintenanceInterfereswithmaintenanceactivity.Iftreesareactivities..notathreattodam,berm,orembankmentIntegrityornotinterferingwithaccessormaintenance,theydonotneedtoberemoved.ErosionErodeddamageover2inchesdeepwherecauseSlopesstabilizedusingappropriateofdamageisstillpresentorwherethereiserosioncontrolmeasures.Iferosionpotentialforcontinuederosion.Myerosionisoccurringoncompactedslope,aobservedonacompactedslope,licensedcivilengineershouldbeconsultedtoresolvesourceoferosion.SettlementAnypartofadam,bermorembankmentthathasToporsidesloperestoredtodesignseWed4incheslowerthanthedesignelevation,dimensions.IfsetllementissignIficant,alicensedcivliengineershouldbeconsultedtodeterminethecauseofthesettlement.InfiltrationPond,SedimentIftwoInchesormoresedimentispresentoraFacilityinfiltratesasdesigned.Tank,Vault,Trench,accumulationpercolationtestindicatesfacilityisworkingatororSmallBasinlessthan90%ofdesign.StorageAreaInfiltrationTankPluggedairventAnyblockageofthevent.Tankorvaultfreelyyents.Structure..TankbentoutofAnypartoftank/pipeIsbentoutofshapemoreTankrepairedorreplacedtodesign.shapethan10%ofitsdesignshape.GapsbetweenAgapwiderthan34-InchatthejointofanytankNowaterorsoilenteringtanksections,damagedsectionsoranyevidenceofsoilparticlesenteringthroughjointsorwalls.jointsorcracksorthetankatajointorthroughawall.tearsInwallInfiltrationVaultDamagetowall,Crackswiderthan½-inch,anyevidenceofsoilVaultissealedandstructurallyStructureframe,bottom,and/orenteringthestructurethroughcracksorqualifiedsound,topslabInspectionpersonneldeterminesthatthevaultis‘.notstructurallysound.2009SurfaceWaterDesignManual—AppendixA1/9/200943 APPENDIXAMAINTENANCEREQUThEMENTSFLOWCONTROL,CONVEYANCE,ANDWQFACILITESNO.2—INFILTRATIONFACILITIESMaintenanceDefectorProblemConditionsWhenMaintenanceIsNeededResultsExpectedWhenComponentMaIntenanceIsPerformedInlet/OutletPipesSedimentSedimentfilling2D%ormoreofthepipe.Inlet/outletpipesclearofsediment.accumulationTrashanddebrisTrashanddebrisaccumulatedininlet/outletNotrashordebrisInpipes.pipes(includesfloatablesandnon-floatables).DamagedCrackswiderthan‘A-inchatthejointoftheNocracksmorethan‘A-inchwideatinlet/outletpipesoranyevidenceofsoilenteringthejointoftheinlet/outletpipe.attheJointsoftheinlet/outletpipes.AccessManholeCover/lidnotInplaceCover/lidismissingoronlypartiallyInplace.Manholeaccesscovered.AnyopenmanholerequiresImmediatemaintenance.LockingmechanismMechanismcannotbeopenedbyoneMechanismopenswithpropertools.notworkingmaintenancepersonwithpropertools.Boltscannotbeseated.Self-lockingcover/liddoesnotwork.Cover/liddifficulttoOnemaintenancepersoncannotremoveCover/lidcanberemovedandremovecover/lidafterapplying80lbsofiLreinstalledbyonemaintenanceperson.LadderrungsunsafeMissingrungs,misagnment,rust,orcracks.Laddermeetsdesignstandards.,Allowsmaintenancepersonsafeaccess.LargeaccessDamagedordifficultLargeaccessdoorsorplatescannotbeReplaceorrepairaccessdoorsoitdoors/plaletoopenopened/removedusingnormalequipment.canopenedasdesigned.Gaps!doesn’tcoverLargeaccessdoorsnotfiatand/oraccessDoorscloseflatandcoversaccesscompletelyopeningnotcompletelycovered,openingcompletely.LiftingRingsmissing,LiftingringsnotcapableofliftingweightofdoorLIftingringssufficienttoliftorrustedorplate.removedoororplate.InfiltrationPond,PluggedFilterbagmorethan‘/2full.ReplacefilterbagorredesignTank,Vault,Trench,system.orSmallBasinFilterBagsInfiltrationPond,Sediment6”ormoreofsedimenthasaccumulated.Pre-settlingoccursasdesignedTank,Vault,Trench,accumulationorSmallBasinPresettlingPondsandVaultsInfiltrationPond,PluggedHighwaterlevelonupstreamsideoffilterRockfilterreplacedevaluateneedRockFilterremainsforextendedperiodoftimeorlittleornoforfilterandremoveIfnotwaterflowsthroughfillerduringheavyrainnecessary.storms.InfiltrationPondRockmissingOnlyonelayerofrockexistsabovenativesoilInSpiliwayrestoredtodesignEmergencyOverflowareafivesquarefeetorlarger,oranyexposureofstandards.Spillwaynativesoilatthetopofoutflowpathofspliway.Rip-raponInsideslopesneednotbereplaced.TreegrowthTreegrowthImpedesfloworthreatensstabIlityofTreesremoved.spiliway.1/9/20092009SurfaceWaterDesignManual—AppendixAA-4 APPENDIXAMAINTENANCEREQUEMENTSFORFLOWCONTROL,CONVEYANCE,ANDWQFACILITIESNO.5—CATCHBASINSANDMANHOLESMaintenanceDefectorProblemConditionWhenMaintenanceIsNeededResultsExpectedWhenComponent--MaintenanceIsPertormedStructureSedimentSedimentexceeds60%ofthedepthfromtheSumpofcatchbasincontainsnobottomofthecatchbasintotheinvertofthesediment.lowestpipeintooroutofthecatchbasinorIswithin6inchesoftheinvertofthelowestpipeIntooroutofthecatchbasin.TrashanddebrisTrashordebrisofmorethan¼cubicfootwhichNoTrashordebrisblockingorislocatedimmediatelyInfrontofthecatchbasinpotentiallyblockingentrancetoopeningorisblockingcapacityofthecatchbasincatchbasin.bymorethanID%.TrashordebrisinthecatchbasinthatexceedsNotrashordebrisInthecatchbasin.thedepthfromthebottomofbasintoinvertthelowestpipeIntooroutofthebasin.DeadanimalsorvegetationthatcouldgenerateNodeadanimalsorvegetationodorsthatcouldcausecomplaintsordangerouspresentwithincatchbasin.gases(e.g.,methane).DepositsofgarbageexceedingIcubicfootInNoconditionpresentwhichwouldvolume,attractorsupportthebreedingofInsectsorrodents.DamagetoframeCornerofframeextendsmorethan‘4InchpastFrameisevenwithcurb.and/ortopsiabcurbfaceintothestreet(Ifapplicable).TopstabhashotesLargerthan2squareinchesorTopslabisfreeofholesandcracks.crackswiderthan¼inch.Framenotsittingflushontopslab,i.e.,Frameissiftingflushontopslab.separationofmorethan‘4Inchoftheframefromthetopslab.CracksinwaflsorCrackswiderthan‘Ainchandiongerthan3feet,Catchbasinissealedandbottomanyevidenceofsoilparticiesenteringcatchstructurallysound.basinthroughcracks,ormaintenancepersonjudgesthatcatchbasinisunsound.Crackswiderthan¼Inchandlongerthan1footNocracksmorethan1/4inchwideatatthejointofanyinlet/outletpipeoranyevidencethejointofinlet/outletpipe.ofsoilparticlesenteringcatchbasinthroughcracks.Settiement/Catchbasinhassettledmorethan1inchorhasBasinreplacedorrepairedtodesignmisalignmentrotatedmorethan2inchesoutofalignmenLstandards.DamagedpipejointsCrackswiderthan¼-inchatthejointoftheNocracksmorethan‘h-inchwideatinlet/outletpipesoranyevidenceofsoIlenteringthejointofInlet/outletpipes.thecatchbasinatthejointoftheinlet/outletpipes,ContaminantsandAnyevidenceofcontaminantsorpoiiutionsuchMaterialsremovedanddisposedofpollutionasoh,gasoline,concreteslurriesorpaint,accordingtoapplicablereguiations.SourcecontrolBMPsimplementedifappropriate.Nocontaminantspresentotherthanasurfaceoilfilm.Inlet/OutletPipeSedimentSedimentfilling20%ormoreofthepipe.Inlet/outletpipesclearofsediment.accumulationTrashanddebrisTrashanddebrisaccumulatedIniniet/outietNotrashordebrisinpipes.pipes(includesfioatablesandnon-floatabtes).DamagedCrackswiderthan‘h-inchatthejointoftheNocracksmornthan‘/.-inchwideatinlet/outletpipesoranyevidenceofsoilenteringthejointoftheinlet/outletpipe.atthejointsoftheInlet/outletpipes.2009SurfaceWaterDesignManual—AppendixA1/9/2009A-9 APPENDIXAMAINTENANCEREQUWEN’ENTSFLOWCONTROL,CONVEYANCE,ANDWQFACIUTJESNO.5—CATCHBASINSANDMANHOLESMaintenanceDefectorProblemIConditionWhenMaintenanceisNeededResultsExpectedWhenComponentMaintenanceisPerformedMetalGratesUnsafegrateopeningGratewithopeningwiderthan7i8inch.Grateopeningmeetsdesign(CatchBasins)standards.TrashanddebrisTrashanddebristhatisblockingmorethan20%Gratefreeoftrashanddebris.ofgratesurface,footnotetoguidelinesfordisposalDamagedormissingGratemissingorbrokenmember(s)ofthegrate.GrateisinplaceandmeetsdesignAnyopenstructurerequiresurgentstandards.maintenance.ManholeCovedLidCover/lidnotinplaceCover/lidismissingoronlypartiallyinplace.Cover/lidprotectsopeningtoAnyopenstructurerequiresurgentstructure.maintenance.LockingmechanismMechanismcannotbeopenedbyoneMechanismopenswithpropertools.NotWorkingmaintenancepersonwithpropertools.Boltscannotbeseated.Self-lockingcover/liddoesnotwork.Cover/liddifticulltoOnemaintenancepersancannotremoveCover/lidcanberemovedandRemovecover/iidafterapplying80lbs.oflift,reinstalledbyonemaintenanceperson.1/9/20092009SurfaceWaterDesignManual—AppendixAA-lU APPENDIXAMAINTENANCEREQUIREMENTSFORFLOWCONTROL,CONVEYANCE,ANDWQFACILITIESNO.6—CONVEYANCEPIPESANDDITCHESMaintenanceDefectorProblemConditionsWhenMaintenanceisNeededResultsExpectedWhenComponentMaintenanceisPerformedRpesSediment&debrisAccumulatedsedimentordebristhatexceedsWaterfiowsfreelythroughppes.accumulation20%ofthediameterofthepipe.Vegetation/rootsVegetation/rootsthatreducefreemovementofWaterflowsfreelythroughpipes.waterthroughpipes.ContaminantsandAnyevidenceofcontaminantsorpollutionsuchMaterialsremovedanddisposedofpollutionasoil,gasoline,concreteslurriesorpaint,accordingtoapplicableregulations.,SourcecontrolBMPsimplementedifappropriate.Nocontaminantspresentotherthanasurfaceoilfilm.DamagetoprotectiveProtectivecoatingIsdamaged;rustorcorrosionPiperepairedorreplaced.coatingorcorrosionIsweakeningthestructuralintegrityofanypadofpipe.DamagedAnydentthatdecreasesthecrosssectionareaofPiperepairedorreplaced.pipebymorethan20%orIsdeterminedtohaveweakenedstructuralIntegrityofthepipe.DitchesTrashanddebrisTrashanddebrisexceedsIcubIcfootper1000Trashanddebrisclearedfromsquarefeetofditchandslopes,ditches.SedimentAccumulatedsedimentthatexceeds20%oftheDitchcleaned/flushedofallsedimentaccumulationdesigndepth.anddebrissothatItmatchesdesign.NoxiousweedsAnynoxiousornuisancevegetationwhichmayNoxiousandnuisancevegetationconstituteahazardtoCountypersonnelortheremovedaccordingtoapplicablepublic,regulations.NodangerofnoxiousvegetationwhereCountypersonnelorthepublicmightnormallybe.ContaminantsandAnyevidenceofcontaminantsorpollutionsuchMaterialsremovedanddisposedofpollutionasoil,gasoline,concreteslurriesorpaint,accordingtoapplicableregulations.SourcecontrolBMPsimplementedifappropriate.Nocontaminantspresentotherthanasurfaceoilfilm.VegetationVegetationthatreducesfreemovementofwaterWaterflowsfreelythroughditches.throughditches.ErosiondamagetoAnyerosionobservedonaditchslope.Slopesarenoteroding.slopesRockliningoutofOnelayerorlessofrockexistsabovenativesoilReplacerockstodesignstandards.placeormissing(Ifarea5squarefeetormareanyexposednativeAjplicable)soil.2009SurfaceWaterDesignManual—AppendixA1/9/2009A-Il APPENDIXAMAINTENANCEREQUIREMENTSFORFLOWCONTROL,CONVEYANCE,ANDWQFACILITIESNO.10—GATESIBOLLARDSIACCESSBARRIERSMaintenanceDefectorProblemConditionsWhenMaintenanceisNeededResultsExpectedWhenComponentMaintenanceIsPerformedChainLinkFencingDamagedormissingMissinggate.Gatesinplace.GatemembersBrokenormissinghingessuchthatgatecannotHingesintactandlubed.Gateisbeeasilyopenedandclosedbyamaintenanceworkingfreely.person.Gateisoutofplumbmorethan6inchesandGateIsalignedandvertical.morethan1footoutofdesignalignment.Missingstretcherbar,stretcherbands,andties.Stretcherbar,bands,andtiesinplace.LockingmechanismLockingdevicemissing,no-functioningordoesLockingmechanismpreventsdoesnotlockgatenotlinktoallparts.openingofgate.OpeningsinfabricOpeningsinfabricaresuchthatan6-inchFabricmeshopeningswithin50%ofdiameterballcouldfitthrough.gridsize.BarGateDamagedormissingCrossbardoesnotswingopenorclosed,isCrossbarswingsfullyopenandcrossbarmissingorisbenttowhereItdoesnotpreventclosedandpreventsvehicleaccess,vehicleaccess.LockingmechanismLockingdevicemissing,no-functioningordoesLockingmechanismpreventsdoesnotLockgatenotlinktoauparts.openingofgate.SupportpostSupportpostdoeshothoidcrossbarup.Crossbarhelduppreventingvehicledamagedaccessintofacility.BollardsDamagedormissingBollardbroken,missing,doesnotfitintosupportNoaccessformotorizedvehiclestoholeorhingebrokenormissing.getintofacility.DoesnotlockLockingassemblyorlockmissingorcannotbeNoaccessformotorizedvehiclestoattachedtolockbollardInplace.getIntofacility.BouldersDislodgedBouldersnotlocatedtopreventmotorizedvehicleNoaccessformotorizedvehiclestoaccess,getintofacflity.CircumventedMotorizedvehiclesgoingaroundorbetweenNoaccessformotorizedvehiclestoboulders,getintofacility.2009SurfaceWaterDesignManual—AppendixAA-IS1/9/2009 APPENDIXAMAmTENANCEREQUIREMENTSFLOWCONTROL,CONVEYANCE,ANDWQFACILITIESNO.11—GROUNDS(LANDSCAPING)MaintenanceDefectorProblemConditionsWhenMaintenanceIsNeededResultsExpectedWhenComponentMaintenanceisPerformedSiteTrashorlitterAnytrashanddebriswhichexceed1cubicfootTrashanddebrisclearedfromsite.par1000squarefeel(thisisaboutequaltotheamountoftrashitwouldtaketofilluponestandardsizeofficegarbagecan).Ingeneral,thereshouldbenovisualevidenceofdumping.NoxiousweedsAnynoxiousornuisancevegetationwhichmayNoxiousandnuisancevegetationconstituteahazardtoCountypersonnelortheremovedaccordingtoapplicablepublic,regulations.NodangerofnoxiousvegetationwhereCountypersonnelorthepublicmightnormallybe.ContamInantsandAnyevidenceofcontaminantsorpollutionsuchMaterialsremovedanddisposedofpollutionasoil,gasoline,concreteslurriesorpaint,accordingtoapplicableregulations.SourcecontrolBMPsimplementedIfappropriate.Nocontaminantspresentotherthanasurfaceoilfilm.Gras&groundcoverGrassorgroundcoverexceeds18inchesinGrassorgroundcovermowedtoaheight.heightnogreaterthan6Inches.TreesandShrubsHazardAnytreeorlimbofatreeidentifiedashavingaNohazardtreesinfacility.potentialtofailandcausepropertydamageorthreatenhumanlife.Ahazardtreeidentifiedbyaqualifiedarboristmustberemovedassoonaspossible.DamagedLimbsorpadsoftreesorshrubsthataresplitorTreesandshrubswithlessthan5%brokenwhichaffectmorethan25%ofthetotaloftotalfoliagewithsplitorbrokenfoliageofthetreeorshrub,limbs.TreesorshrubsthathavebeenblowndownorNoblowndownvegetationorknockedover,knockedovervegetation.Treesorshrubsfreeofinjury.TreesorshrubswhicharenotadequatelyTreeorshrubinplaceandsupportedorareleaningover,causingexposureadequatelysupported;deadoroftheroots.diseasedtreesremoved.1/9/20092009SurfaceWaterDesignManual—AppendixAA-16 APPENDIXAMAINTENANCEREQUIREMENTSFORFLOWCONTROL,CONVEYAnCE,AflDWQFACILITIESNO.12—ACCESSROADSMaintenanceDefectorProblemConditionWhenMaintenanceisNeededResultsExpectedWhenComponentMaintenanceisPerformedSiteTrashanddebrisTrashanddebrisexceedsIcubicfootper1,000Roadwaydrivablebymaintenancesquarefeet(i.e.,trashanddebriswouldfillupvehicles.onestandardssizegarbagecan).DebriswhichcoulddamagevehicletiresorRoadwaydrivablebymaintenanceprohibituseofroad,vehicles.ContaminantsandAnyevidenceofcontaminantsorpollutionsuchMaterialsremovedanddisposedofpollutionasoil,gasoline,concreteslurriesorpaint,accordingtoapplicableregulations.SourcecontrolBMPsImplementedifappropriate.Nocontaminantspresentotherthanasurfaceallfilm.BlockedroadwayAnyobstructionwhichreducesclearanceaboveRoadwayoverheadclearto14feetroadsurfacetolessthan14feeLhigh.Anyobstructionrestrictingtheaccesstoa10-toAtleast12-footofwidthonaccess12footwidthforadistanceofmorethan12feetroad.oranypointrestrictingaccesstolessthana10footwidth.RoadSurfaceErosion,settlement,AnysurfacedefectwhichhindersorpreventsRoaddrivablebymaintenancepotholes,softspots,maintenanceaccess,vehicles.rutsVegetationonroadTreesorothervegetationpreventaccesstoMaintenancevehiclescanaccesssurfacefacilitybymaintenancevehicles,facility.ShouldersandErosionErosionwIthin1footoftheroadwaymorethan8ShoulderfreeoferosionandDitchesIncheswideand6inchesdeep.matchingthesurroundingroad.WeedsandbrushWeedsandbrushexceed18InchesInheightorWeedsandbrushcutto2inchesInhindermaintenanceaccess,heightorclearedinsuchawayastoallowmaintenanceaccess,ModularGridContaminantsandAnyevidenceofcontaminantsorpollutionsuchMaterialsremovedanddisposedofPavementpollutionasoil,gasoline,concreteslurriesorpainLaccordingtoapplicableregulations.SourcecontrolOMPsimplementedifappropriate.Nocontaminantspresentotherthanasurfaceoilfilm.DamagedormissingAccesssurfacecompactedbecauseofbrokenonAccessroadsurfacerestoredsoI,missingmodularblock,roadinfiltrates.2009SurfaceWaterDesignManual—AppendixA1/912009A-i7 APPENDIXATYLAINTENANCEREQUmnvWNTSFORFLOWCONTROL,CONVEYANCE,ANDWQFACILITIESNO.14—WETBIOFILTRATIONSWALEMaintenanceDefectorProblemConditionWhenMaintenanceisNeededResultsExpectedWhenComponentMaintenanceIsPerformedSiteTrashanddebrisAnytrashand/ordebrisaccumulatedatthesite.Notrashordebrisatthesite.ContaminantsandAnyevidenceofcontaminantsorpollutionsuchMaterialsremovedanddisposedofpollutionasoil,gasoline,concreteslurriesorpaint,accordingtoapplicableregulations.SourcecontrolBMPsImplementedifappropriate.Nocontaminantspresentotherthanasurfaceoilfilm.SwaleSectionSedimentSedimentdepthexceeds2Inchesin10%oftheNosedimentdepositsIntreatmentaccumulationswaletreatmentarea.area.ErosioniscouringErodedorscouredswalebottomduetoNoerodedorscouredareasinchannelizationorhighflows.bioswate.Causeoferosionorscouraddressed.WaterdepthWaternotretainedtoadepthofabout4inchesWalerdepthof4inchesthroughoutduringthewetseason.swaleformostofwetseason.VegetationineffectiveVegetationsparse,doesnotprovideadequateWetlandvegetationfullycoversfiltrationorcrowdedoutbyverydenseclumpsofbottomofswaleandnocattallsorcattailornuisancevegetation,nuisancevegetationpresent.InsufficientwaterWetlandvegetationdiesduetolackofwater.Wetlandvegetationremainshaithy(mayrequireconvertingtograss.linedbioswaleFlowSpreaderConcentratedflowFlowfromspreadernotuniformlydistributedFlowsarespreadevenlyoverentireacrossentireswalewidth.swalewidth.Inlet/OutletPipeSedimentSedimentfilling20%ormoreofthepipe.Inlet/outletpipesclearofsediment.accumulationTrashanddebrisTrashanddebrisaccumulatedininlet/outletNotrashordebrisinpipes.pipes(includesfloatabiesandnon-floatables).DamagedCrackswiderthan34-inchattheJointoftheNocracksmorethan¾-Inchwideatinlet’outletpipesoranyevidenceofsoilenteringtheJointoftheinlet/outletpipe.Iatthejointsoftheinlet/outletpipes.2009SurfaceWaterDesignManual—AppendixA1/9/2009A-19 •APPENDIX“F”WETLANDEVALUATION©2016D.H.STRONGConsultingEngineersInc.AlpineNurseryPage73TechnicalInformationReportCityofRenton Re-AlignEnvironmentalJaunary4,2015Mr.RoyBoyer14609161stAvenueSERenton,WA98059Re:WetlandEvaluation—AlpineNurserySite,Renton,WADearMr.Boyer:ThiscorrespondencefollowsyourrequestthatIconductapreliminarywetlandreconnaissanceontheparcelsoflandlocatedinthesoutheastcorneroftheintersectionofSE14411Streetand160thAveSE.Basedonyourdescriptionofthesite,thepropertyunderinvestigationincludestheAlpineNurseryparcel,locatedtothenorth,andtworesidentialparcelslocatedimmediatelytothesouth.(SeeAttachedLocationandSiteMaps).DataCollectionPriortovisitingthesite,onlineinformationwasobtainedusingtheKingCountyiMapsystem,theUSFishand\VildlifeServiceonlineNationalWetlandsInventory(NWI),andtheNaturalResourceConservationService(NRCS)onlinesoilmappingutility.AsshownintheAttachediMapphotosandNational\VedandsTnvento’Map,nomappedstreamsorwetlandsareshownonthesite.Similarly,thesemapsshownosneamsorwetlandswithin500feetofthesite,indicatingthatnobuffersfromoff-sitecriticalareaswouldaffectthisparcel.AlsoattachedistheNRCSsoilreportforthesite.Asdescribedinthesoilreport,theparcelsappeartobeunderlainbyEverettgravellysandyloam,0to5percentslopes.Thissomewhatexcessivelydrainedsoiliscommonlyfoundonterraces,suchastheRentonHighlandsinwhichthesitelies.Thissoilexhibitsawatertabledepthgreaterthan80inchesbelowthesoilsurface.Thismapunitisnottypicallyknowntoincludehydricinclusions,whichindicatesthatwetlandsarenottypicallypresentwithinthemapunit.Fith/n’orkFieldworkwasconductedonAugust21,2014usingthethree-parameterapproachidentifiedinthel[4tihingtonStateIVet/ant/cIdentificationandDelineationAlannal(WashingtonManual)(WDOE1997)andtheRegionalSupplementtotheCoipsofEn1gineercIVet/andDelineationManual:IVex/en;Alountains,I‘alleysandCoastRegion(RegionalSupplement(USACE2010),whichareconsistentwiththezitmyCorpsofEn&ineersIPitlandsDelineationManual(ACOEManual)(EnvironmentalLaboratory1987)andotherpertinentfederalandlocalguidance(33CFR328.3FaJI1-5]).Duringareviewoftheparcelboundary,Iwalkedtheperimeterofthepropertyandfoundnovisibleindicationofdrainageonto,orleavingthesite.Iobservedthatthesitecontainsonesmalldepressionalareathatisapproximately3feetdeep,30feetwideand50feetlong.Thedepressiondoesnotdrainoffofthesite,nordoesitappeartocaptureanysurfacedrainage.ItappearsthatthisBillGranger14056180”AveSERenton,WA90859(206)790-6132Bill@re-olignenv.corn depressionalareaisman-madeandthesoiliscoveredwithmulch,suggestingthatdieareamayhavcbeenusedasamulchstorageareaassociatedwithdienursery.Onesoilpitwasexcavatedinthedepression,showingagravellyloammaterialwithaMunsellcolorof10Th3/3intheupper0—8inchesandIOYR4/3inthelowerS—16inches.Nogroundwaterwasencounteredinthesoilpitandthesoildoesnotexhibitanyindicatorsofwetlandhydrology.VegetauonacrosstheAlpineNurserysitehasbeenheavilydisturbedbythenurseryactivity,withDouglasfirandbigleafmaplerepresentingthesparsecanopythatremainsonsite.Southofdienurseryparcel,thetwootherlotsaredominatedbyDouglasfir,westernredcedar,andbigleafmapleinthecanopy,withcommonoccurrencesofDouglasfirandIndianpluminthesubcanopyandNootkaroseintheshrublayer.Herbaceousspeciesfoundintheundisturbedforestareasincludebrackenfern,swordfernandOregongrape.Basedonthesespecies,noindicationofahydrophyticplantcommunitywasfound.Baseduponthispreliminaryassessment,thissitedoesnotappeartocontainanystreamsorwetlands.ThesitealsodoesnotappeartobeincludedwithinanyCriticalAreaBuffer.Sincerely,Re-AlignEnvironmentalBillGranger-OwnerAttachmentsBillGranger14056180”AveSERento;i,WA90859(206)790-6132Bhll@re-alignenv.co;n2 AlpineNursery-Renton,WA-ri>P5S\tC)2ooaxrngCeonty.COMMENTS:KingCountyNydiographic&DataTheinformationIncludedonthismaphasbeencompi4&byI9npCountystafffromaIntendedforuseasasurveypioduct.KingCountyshallnotbeliableforanygeneral.pmhibftsdexceptbywdttenpermissionofKingCounty.r_Jrir-;;j._P3L%w___-.t,_-aSEIjStHS:‘*;j•.Q--lkTiRiPI1w—_r”—•Laa!1Lr.Akk{IDate:8121/2014Source:KingCountyMAP-Hy&tgtaphiCWom,abonp,vpJ/W.metTd(c.9OV/GlAP) it‘*—‘—1I4--I‘Pr1:h:TheinbimattcoindudedonthmaphasbeencomØedbylongCountystafffromavarietyofsourcesandissubjecttochangewithoutnotice.KingCountymakesnorepresentativesorwarranties,expressorimplied,astoaJmcy,completeness,timeliness,orrightstotheLisaofsuchInfonatlon.Thisdocumentisnotintendedforuseasasurveyproduct.KingCountyshallnotbeliableforanygeneral,special,indfrect,Incidental,orconsequentialdamagesincluding,butnotJimliodto,batrevenuesorlostprotlisresulting1mmtheuseormisuseofthe‘Inftnnathncontainedonthismap.AnysaleofthismaporthfomwivnonthismapIspcohlbkedexceptbywiltenpflsalonofKingCounty.119041111Date;8a112014Source:KM9CountyiMPS’-Hy&ogcaphiclnfmmabon(httpJNtwwsristmkc.gc4GlS(iMAP)Kt1(CIKingCounQj, .. r ,tOI *wiUtJfllvn Jii)National Wetlands Inventory U.S._Fish_and_Wildlife_Service ____ . Alpine Nursery Site Jan 5,2015 Wetlands — ——aa—a • . • - 11 L —‘ ‘———l_nI4•-I —S f - ---‘--r_____._r!-J ‘:‘&q - -p ‘‘a-4 - — -- -:•: ,.- --—, •L’j ---‘ ‘:!1 - •7 5 - 4 --- -t r -p_______________--•POWMI -.esn Freshwater Emergent Freshwater Forested/Shrub Estuanne and Marine Deepwater Estuarine and Marine Freshwaler Pond Lake Riverine Other Riparian ___Herbaceous Riparian Status Digital Data This map Ii tnt ii e.te,ence nk.The US Fish and Wildife Service is notespocaistsrsheaccusarycurrentnessofmebitedata•hnwn sq this map.AKwedaMsrenddatashouldbeusedisaccordancevisitsthetaynrertadat.tound Mi the Wetland.Mapperweb site.User Remarks: NRCSNaturalResourcesConservationServiceAproductoftheNationalCooperativeSoilSurvey,ajointeffortoftheUnitedStatesDepartmentofAgricultureandotherFederalagencies,StateagenciesincludingtheAgriculturalExperimentStations,andlocalparticipantsUSDAUnitedStatesDepartmentofAgricultureCustomSoilResourceReportforKingCountyArea,Washington08,000January5,2015 PrefaceSoilsurveyscontaininformationthataffectslanduseplanninginsurveyareas.Theyhighlightsoillimitationsthataffectvariouslandusesandprovideinformationaboutthepropertiesofthesoilsinthesurveyareas.Soilsurveysaredesignedformanydifferentusers,includingfarmers,ranchers,foresters,agronomists,urbanplanners,communityofficials,engineers,developers,builders,andhomebuyers.Also,conservationists,teachers,students,andspecialistsinrecreation,wastedisposal,andpollutioncontrolcanusethesurveystohelpthemunderstand,protect,orenhancetheenvironment.VariouslanduseregulationsofFederal,State,andlocalgovernmentsmayimposespecialrestrictionsonlanduseorlandtreatment.Soilsurveysidentifysoilpropertiesthatareusedinmakingvariouslanduseorlandtreatmentdecisions,Theinformationisintendedtohelpthelandusersidentifyandreducetheeffectsofsoillimitationsonvariouslanduses.Thelandowneroruserisresponsibleforidentifyingandcomplyingwithexistinglawsandregulations.Althoughsoilsurveyinformationcanbeusedforgeneralfarm,local,andwiderareaplanning,onsiteinvestigationisneededtosupplementthisinformationinsomecases.Examplesincludesoilqualityassessments(http://www.nrcs.usda.gov/wps/portal/nrcs!main/soils/health/)andcertainconservationandengineeringapplications.Formoredetailedinformation,contactyourlocalUSDAServiceCenter(http://offices.sc.egov.usda.gov/locatorlapp?agency=nrcs)oryourNRCSStateSoilScientist(http://www.nrcs.usda.govMpsfportal/nrcs/detaillsoils/contactus/?cid=nrcsl42p2_053951).Greatdifferencesinsoilpropertiescanoccurwithinshortdistances.Somesoilsareseasonallywetorsubjecttoflooding.Somearetoounstabletobeusedasafoundationforbuildingsorroads.Clayeyorwetsoilsarepoorlysuitedtouseasseptictankabsorptionfields.Ahighwatertablemakesasoilpoorlysuitedtobasementsorundergroundinstallations.TheNationalCooperativeSoilSurveyisajointeffortoftheUnitedStatesDepartmentofAgricultureandotherFederalagencies,StateagenciesincludingtheAgriculturalExperimentStations,andlocalagencies.TheNaturalResourcesConservationService(NRCS)hasleadershipfortheFederalpartoftheNationalCooperativeSoilSurvey.Informationaboutsoilsisupdatedperiodically.UpdatedinformationisavailablethroughtheNRCSWebSoilSurvey,thesiteforofficialsoilsurveyinformation.TheU.S.DepartmentofAgriculture(USDA)prohibitsdiscriminationinallitsprogramsandactivitiesonthebasisofrace,color,nationalorigin,age,disability,andwhereapplicable,sex,maritalstatus,familialstatus,parentalstatus,religion,sexualorientation,geneticinformation,politicalbeliefs,reprisal,orbecauseallorapartofanindividual’sincomeisderivedfromanypublicassistanceprogram.(Notallprohibitedbasesapplytoallprograms.)Personswithdisabilitieswhorequirealternativemeans2 forcommunicationofprograminformation(Braille,largeprint,audiotape,etc.)shouldcontactUSDA’sTARGETCenterat(202)720-2600(voiceandTDD).Tofileacomplaintofdiscrimination,writetoUSDA,Director,OfficeofCivilRights,1400IndependenceAvenue,SW.,Washington,D.C.20250-9410orcall(800)795-3272(voice)or(202)720-6382(TDD).USDAisanequalopportunityproviderandemployer.3 ContentsPreface2SoilMap5SoilMap6Legend7MapUnitLegendSMapUnitDescriptionsSKingCountyArea,Washington10EvB—Everettgravellysandyloam,0to5percentslopes10References114 SoilMapThesoilmapsectionincludesthesoilmapforthedefinedareaofinterest,alistofsoilmapunitsonthemapandextentofeachmapunit,andcartographicsymbolsdisplayedonthemap.Alsopresentedarevariousmetadataaboutdatausedtoproducethemap,andadescriptionofeachsoilmapunit.5 Map5e:1:1,790WpEtedmArntat(8Sx1r)stL47’2826’NCustomSoilResourceReportSoilMap3—4r2826’N47’23t-4’tJa-S250100150Aicet050100200:300MappmjooWebMaratcrerrdinatWGS&4geUrNZonelaNWG584a-CcS6 C 0 Custom Soil Resource Report MAP LEGEND MAP INFORMATION Area of Interest (AOl)Spoil Area The soil surveys that comprise your AOl were mapped at 1:24,000. Area ol Interest (AOl)Stony spoi Soils Warning:Soil Map may not be valid at this scale.Very Stony SpotSoilMapUnitPolygons Wet Spot Enlargement of maps beyond the scale of mapping can cause.,Soil Map unit Lines misunderstanding of the detail of mapping and accuracy of soil lineAOther Soil Map unil Points placement.The maps do not show the small areas of contrasting Special Line Features soils that could have been shown at a more detailed scale.Special Point Features Water FeaturesBlowout Streams and Canals Please rely on the bar scale on each map sheet for mapBorrowPitmeasurements.Transportation *Clay Spol Rails Source of Map:Natural Resources Conservation ServiceoClosedDepression ___ Interstate Highways Wob Soil Survey URL:http:/Mebsoilsurvey.nrcs.usda.gov Gravel Pil Coordinate System:Web Mercator (EPSG:3857)us Routes Gravelly Spot Major Roads Maps from the Web Soil Survey are based on the Web Mercator Landfill projection,which preserves direction and shape but distortsLocalRoadsdistanceandarea.A projection that preserves area,such as theA.Lava Flow Background Albers equal-area conic projection,should be used if more accurate Marsh or swamp Aerial Photography calculations of distance or area are required. *Mine or Quarry This product is generated from the USDA-NRCS certified data as of ©Miscellaneous Water the version date(s)listed below. o Perennial Water Soil Survey Area:King County Area,Washington Rock Outcrop Survey Area Data:Version 10,Sep 30,2014 +Saline Spot Soil map units are labeled (as space allows)for map scales 1:50,000 :•:Sandy Spot or larger. -.Severely Eroded Spot Date(s)aerial images were photographed:Jul 3,2014—Jul 15,O Sinkhole 2014 Slide or Slip The orthophoto or other base map on which the soil lines wereSOdicSPotcompiledanddigitizedprobablydiffersfromthebackground imagery displayed on these maps.As a result,some minor shifting 7 CustomSoilResourceReportMapUnitLegendTotalsforAreaofInterestEverettgravellysandyloam,0to5percentslopesMapUnitDescriptionsThemapunitsdelineatedonthedetailedsoilmapsinasoilsurveyrepresentthesoilsormiscellaneousareasinthesurveyarea.Themapunitdescriptions,alongwiththemaps!canbeusedtodeterminethecompositionandpropertiesofaunit.Amapunitdelineationonasoilmaprepresentsanareadominatedbyoneormoremajorkindsofsoilormiscellaneousareas.Amapunitisidentifiedandnamedaccordingtothetaxonomicclassificationofthedominantsoils,Withinataxonomicclasstherearepreciselydefinedlimitsforthepropertiesofthesoils.Onthelandscape,however,thesoilsarenaturalphenomena,andtheyhavethecharacteristicvariabilityofallnaturalphenomena.Thus,therangeofsomeobservedpropertiesmayextendbeyondthelimitsdefinedforataxonomicclass.Areasofsoilsofasingletaxonomicclassrarely,ifever,canbemappedwithoutincludingareasofothertaxonomicclasses.Consequently,everymapunitismadeupofthesoilsormiscellaneousareasforwhichitisnamedandsomeminorcomponentsthatbelongtotaxonomicclassesotherthanthoseofthemajorsoils.Mostminorsoilshavepropertiessimilartothoseofthedominantsoilorsoilsinthemapunit,andthustheydonotaffectuseandmanagement.Thesearecallednoncontrasting,orsimilar,components.Theymayormaynotbementionedinaparticularmapunitdescription.Otherminorcomponents,however,havepropertiesandbehavioralcharacteristicsdivergentenoughtoaffectuseortorequiredifferentmanagement.Thesearecalledcontrasting,ordissimilar,components.Theygenerallyareinsmallareasandcouldnotbemappedseparatelybecauseofthescaleused.Somesmallareasofstronglycontrastingsoilsormiscellaneousareasareidentifiedbyaspecialsymbolonthemaps.Ifincludedinthedatabaseforagivenarea,thecontrastingminorcomponentsareidentifiedinthemapunitdescriptionsalongwithsomecharacteristicsofeach.Afewareasofminorcomponentsmaynothavebeenobserved,andconsequentlytheyarenotmentionedinthedescriptions,especiallywherethepatternwassocomplexthatitwasimpracticaltomakeenoughobservationstoidentifyallthesoilsandmiscellaneousareasonthelandscape.Thepresenceofminorcomponentsinamapunitinnowaydiminishestheusefulnessoraccuracyofthedata.Theobjectiveofmappingisnottodelineatepuretaxonomicclassesbutrathertoseparatethelandscapeintolandformsorlandformsegmentsthathavesimilaruseandmanagementrequirements.Thedelineationofsuchsegmentsonthemapprovidessufficientinformationforthedevelopmentofresourceplans.Ifintensiveuseofsmallareasisplanned,however,onsiteinvestigationisneededtodefineandlocatethesoilsandmiscellaneousareas.KingCountyArea,Washington{WA633)MapUnitSymbolMapUnitNameAcresInAolPercentofAolEvB10.5Iio.s100.0%100.0%8 CustomSoilResourceReportAnidentifyingsymbolprecedesthemapunitnameinthemapunitdescriptions.Eachdescriptionincludesgeneralfactsabouttheunitandgivesimportantsoilpropertiesandqualities.Soilsthathaveprofilesthatarealmostalikemakeupasoilseries.Exceptfordifferencesintextureofthesurfacelayer,allthesoilsofaserieshavemajorhorizonsthataresimilarincomposition,thickness,andarrangement.Soilsofoneseriescandifferintextureofthesurfacelayer,slope,stoniness,salinity,degreeoferosion,andothercharacteristicsthataffecttheiruse.Onthebasisofsuchdifferences,asoilseriesisdividedintosoilphases.Mostoftheareasshownonthedetailedsoilmapsarephasesofsoilseries.Thenameofasoilphasecommonlyindicatesafeaturethataffectsuseormanagement.Forexample,Alphasiltloam,0to2percentslopes,isaphaseoftheAlphaseries.Somemapunitsaremadeupoftwoormoremajorsoilsormiscellaneousareas.Thesemapunitsarecomplexes,associations,orundifferentiatedgroups.Acomplexconsistsoftwoormoresoilsormiscellaneousareasinsuchanintricatepatternorinsuchsmallareasthattheycannotbeshownseparatelyonthemaps.Thepatternandproportionofthesoilsormiscellaneousareasaresomewhatsimilarinallareas.Alpha-Betacomplex,0to6percentslopes,isanexample.Anassociationismadeupoftwoormoregeographicallyassociatedsoilsormiscellaneousareasthatareshownasoneunitonthemaps.Becauseofpresentoranticipatedusesofthemapunitsinthesurveyarea,itwasnotconsideredpracticalornecessarytomapthesoilsormiscellaneousareasseparately.Thepatternandrelativeproportionofthesoilsormiscellaneousareasaresomewhatsimilar.Alpha-Betaassociation,0to2percentslopes,isanexample.Anundifferentiatedgroupismadeupoftwoormoresoilsormiscellaneousareasthatcouldbemappedindividuallybutaremappedasoneunitbecausesimilarinterpretationscanbemadeforuseandmanagement.Thepatternandproportionofthesoilsormiscellaneousareasinamappedareaarenotuniform.Anareacanbemadeupofonlyoneofthemajorsoilsormiscellaneousareas,oritcanbemadeupofallofthem.AlphaandBetasoil5,0to2percentslopes,isanexample.Somesurveysincludemiscellaneousareas.Suchareashavelittleornosoilmaterialandsupportlittleornovegetation.Rockoutcropisanexample.9 CustomSoilResourceReportKingCountyArea,WashingtonEvB—Evereftgravellysandyloam,0to5percentslopesMapUnitSettingNationalmapunitsymbol:1hmt2Meanannualprecipitation:30to45inchesMeanannualairtemperature:50degreesFFrost-freeperiod:180daysFarmlandclassification:PrimefarmlandifirrigatedMapUnitCompositionEverettandsimilarsoils:100percentEstimatesarebasedonobsewations,descriptions,andtransectsofthemapunit.DescriptionofEverettSellingLandfonn:TerracesParentmateriaLGlacialoutwashwithacomponentofvolcanicashintheupperpartTypicalprofileHI-Oto17inches:gravellyashysandyloamH2-17to32inches:verygravellysandyloamH3-32to60inches:verygravellycoarsesandPropertiesandqualitiesSlope:0to5percentDepthtorestrictivefeature:Morethan80inchesNaturaldrainageclass:SomewhatexcessivelydrainedCapacityofthemostlimitinglayertotransmitwater(Ksat):High(1.98to5.95in/hr)Depthtowatertable:Morethan80inchesFrequencyofflooding:NoneFrequencyofpondmg:NoneAvailablewaterstorageinprofile:Low(about5.0inches)InterpretivegroupsLandcapabilityclassification(irrigated):NonespecifiedLandcapabilityclassification(nonirrigated):3sHydrologicSoilGroup:AOthervegetativeclassification:DroughtySoils(GOO2XN4O2WA)10 ReferencesAmericanAssociationofStateHighwayandTransportationOfficials(MSHTO).2004.Standardspecificationsfortransportationmaterialsandmethodsofsamplingandtesting.24thedition.AmericanSocietyforTestingandMaterials(ASTM).2005.Standardclassificationofsoilsforengineeringpurposes.ASTMStandardD2487-0Q.Cowardin,L.M.,V.Carter,F.C.Golet,andE.T.LaRoe.1979.Classificationofwetlandsanddeep-waterhabitatsoftheUnitedStates.U.S.FishandWildlifeServicePNSIOBS-79/31.FederalRegister.July13,1994.ChangesinhydricsoilsoftheUnitedStates.FederalRegister.September18,2002.HydricsoilsoftheUnitedStates.Hurt,SW.,andL.M.Vasilas,editors.Version6.0,2006.FieldindicatorsofhydricsoilsintheUnitedStates.NationalResearchCouncil.1995.Wetlands:Characteristicsandboundaries.SoilSurveyDivisionStaff.1993.Soilsurveymanual.SoilConservationService.U.S.DepartmentofAgricultureHandbook18.http://ww.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcsl42p2_054262SoilSurveyStaff.1999.Soiltaxonomy:Abasicsystemofsoilclassificationformakingandinterpretingsoilsurveys.2ndedition.NaturalResourcesConservationService,U.S.DepartmentofAgricultureHandbook436.http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcsl42p2_O53577SoilSurveyStaff.2010.Keystosoiltaxonomy.11thedition,U.S.DepartmentofAgriculture,NaturalResourcesConservationService.http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcsl42p2_053580Tiner,R.W.,Jr.1985,WetlandsofDelaware.U.S.FishandWildlifeServiceandDelawareDepartmentofNaturalResourcesandEnvironmentalControl,WetlandsSection.UnitedStatesArmyCorpsofEngineers,EnvironmentalLaboratory.1987.CorpsofEngineerswetlandsdelineationmanual.WaterwaysExperimentStationTechnicalReportY-87-1.UnitedStatesDepartmentofAgriculture,NaturalResourcesConservationService.Nationalforestrymanual.http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcsl42p2_053374UnitedStatesDepartmentofAgriculture,NaturalResourcesConservationService,Nationalrangeandpasturehandbook.http://www.nrcs.usda.govMps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdbl04308411 CustomSoilResourceReportUnitedStatesDepartmentofAgriculture,NaturalResourcesConservationService.Nationalsoilsurveyhandbook,title430-VI.http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcsl42p2_054242UnitedStatesDepartmentofAgriculture,NaturalResourcesConservationService.2006.LandresourceregionsandmajorlandresourceareasoftheUnitedStates,theCaribbean,andthePacificBasin.U.S.DepartmentofAgricultureHandbook296.http:Ilwww.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cidnrcsl42p2_053624UnitedStatesDepartmentofAgriculture,SoilConservationService.1961.Landcapabilityclassification.U.S.DepartmentofAgricultureHandbook210.http:IIwww.nrcs.usda.gov/InternetlFSE_DOCUMENTS/nrcsl42p2_052290.pdf12 •APPENDIX“0”TRAFFICIMPACTANALYSIS©20160.ftSTRONGConsultingEngineersInc.AlpineNurseryPage74TechnicalInformationReportCityofRenton THEALPINEPLATTRAFFICIMPACTANALYSISCITYOFRENTONPreparedforMr.RoyBoyer14609161stAve.SERenton,WA98059PreparedbyTraffeNORTHWESTTRAFFICEXPERTS11410NE124thSt.,#590Kirkland,Washington98034Telephone:425.522.4118Fax:425.522.4311December31,2014 T,efjltzz__Nnnri-vwesrTRAFFICExrnra11410NE124thSt.#590Kirkiand.WA98034Phone.425.522.4118Fax.425.522.4311December31,2014Mr.RoyBoyer14609ieiAve.SERenton,WA98059Re:TheAlpinePlat-CityofRentonTrafficImpactAnalysisDearMr.Boyer:Wearepleasedtopresentthistrafficimpactanalysisreportfortheproposed28lotAlpineplatlocatedonthesouthsideofSE144thSt.betweenl60”Ave.SEand161StAve.SEat16023SE144thSt.intheCityofRenton.ThescopeofthisanalysisisbaseduponthepreliminaryplatsiteplanandtheCityofRentonPolicyGuidelinesforTrafficImpactAnalysisforNewDevelopment.Oursummary,conclusionsandrecommendationsbeginonpage5ofthisreport.PROJECTDESCRIPTIONFigure1isavicinitymapshowingthelocationofthesiteandstudyarea.Figure2showsthepreliminarysiteplan.Theinternalaccessstreetsconnectto160°’AveSEandl6?tAveSEthatbordertheeastandwestsidesofthesite.Theinternalsitestreetswillhavecurb,gutterandsidewalkonbothsides.Halfstreetimprovementsincludingcurb,gutterandsidewalkwillalsobeinstalledonthesitefrontageon160thAveSE,161StAveSEandSE144°’Street.DevelopmentofTheAlpinePlatisexpectedtooccurbytheyear2017.Therefore,forpurposesofthisstudy,2017isusedasthehorizonyear.TheexistingAlpineNurserywillberemovedwiththisdevelopment.PageI Avehicletripisdefinedasasingleoronedirectionvehiclemovementtheoriginordestination(exitingorentering)insidethestudysite.TraffwitheitherThetripgenerationiscalculatedusingtheaveragetripratesintheInstituteofTransportationEngineers(lYE)TripGeneration.NinthEditionforSingleFamilyDetachedHousing(lYELandUseCode210).Thesetripgenerationvaluesaccountforallsitetripsmadebyallvehiclesforallpurposes,includingresident,visitor,andserviceanddeliveryvehicletrips.Figure3showstheestimatedtripdistributionandthecalculatedsite-generatedtrafficvolumes.Thedistributionisbasedonexistingtrafficvolumepatterns,thecharacteristicsoftheroadnetwork,thelocationoflikelytriporiginsanddestinations(employment,shopping,socialandrecreationalopportunities),expectedtraveltimes,andprevioustrafficstudies.EXISTINGPHYSICALCONDITIONSStreetFacilitiesThestreetsinthestudyareaareclassifiedpertheCityofRentonComprehensivePlanasfollows:SE144thmothAveSE161StAveSECollectorArterialResidentialAccessResidentialAccessTheAlDinePlatTRIPGENERATIONANDDISTRIBUTIONThe28single-familyunitsintheproposedAlpinePlatareexpectedtogeneratethevehiculartripsduringanaverageweekdayandduringthestreettrafficpeakhoursasshownbelow:TripRateTripsTripsTotalTimePeriodTripsperunitEnteringExiting133134AverageWeekday9.5226750%50%516AMPeakHour0.752125%75%1810PMPeakHour1.002863%37%Page2 TheAlpinePlatTraftj.SE144thSt.hasaspeedlimitof25mphandconsistsoftwo11ft.lanesandapavedshoulderapproximately6to8feetwideinthevicinityoftheprojectsite.SE144°St.isstraightandflatattheintersectionsof160thAveSEand161sAveSEwithapparentgoodsightdistanceobservedinbothdirections.Bothintersectionsarecontrolledwithstopsignsontheminorapproaches.Therearenocurbs,guttersorsidewalksonSE144hu1160thAveSEand161stAve.SEintheprojectvicinity.EXISTINGTRAFFICCONDITIONSTrafficVolumesFigure4showsexisting1futurewithoutprojectandfuturewithprojectPMpeakhourtrafficvolumesatthe160thAveSE/SE144thSt.and161stAveSE/SE144thintersections.PMpeakhourtrafficvolumeturningmovementcountswereconductedonDecember16,2014atthestudyintersectionsandareincludedinthetechnicalappendix.PertheCityofRentonPolicyGuidelinesforTrafficImpactAnalysisforNewDevelopmentintersectionsandroadsegmentsthatexperienceanincreaseof5%intrafficvolumesrequireanalysis.Thetwostudyintersectionsmeettheserequirements.LevelofServiceAnalysisLevelofService(LOS)isaqualitativemeasuredescribingoperationalconditionswithinatrafficflow,andtheperceptionoftheseconditionsbydriversorpassengers.Theseconditionsincludefactorssuchasspeed,delay,traveltime,freedomtomaneuver,trafficinterruptions,comfort,convenience,andsafety.Levelsofservicearegivenletterdesignations,fromAtoF,withLOSArepresentingthebestoperatingconditions(freeflow,littledelay)andLOSFtheworst(congestion,longdelays).Generally,LOSAandBarehigh,LOSCandDaremoderateandLOSEandFarelow.TableIshowscalculatedlevelofservice(LOS)forexistingandfutureconditionsincludingprojecttrafficatthepertinentstreetintersection.TheLOSwascalculatedusingtheproceduresintheTransportationResearchBoardHiQhwayCapacityManualTheLOSshownindicatesoverallintersectionoperation.Atintersections,LOSisdeterminedbythecalculatedaveragecontroldelaypervehicle.TheLOSandcorrespondingaveragecontroldelayinsecondsareasfollows:Page3 TheAlpinePlat____ _ ___ - __ __ _____ __ _ __ _ ____ ___TYPEOFABc1DEFINTERSECTION<Signalized>10.0and>20.0and>35.0and>55.0and>80.<20.0<35.0<55.0<80.000————StopSignControl>10and<15>15ands25>25and<35>35and50>50FUTURETRAFFICCONDITIONSWITHOUTTHEPROJECTFigure4showsprojected2017PMpeakhourtrafficvolumeswithouttheproject.Thesevolumesincludetheexistingtrafficvolumecountsplusbackgroundtrafficgrowth.Thebackgroundgrowthfactoraccountsfortrafficvolumesgeneratedfromotherapprovedbutunbuiltsubdivisions(pipelineprojects)andgeneralgrowthintraffictravelingthroughthearea.A3%peryearannualratewasaddedforeachyearofthetwoyeartimeperiod(foratotalof6%)fromthe2015trafficcounttothe2017horizonyearoftheproposal.Fromotherrecentnearbystudies,the6%increaseissufficienttocovertripsgeneratedbypipelineprojectsplusthegeneralbackgroundgrowthintraffic.FUTURETRAFFICCONDITIONSWITHPROJECTFigure4showstheprojectedfuture2017PMpeakhourtrafficvolumeswiththeproposedproject.Thesite-generatedPMpeakhourtrafficvolumeswereaddedtotheprojectedfuturewithoutprojectvolumestoobtainthefuturewithprojectvolumes.Table1showscalculatedLOSforfuturewithprojectvolumesatthestudyintersections.ThestudyintersectionsoperateatanacceptableLOSBforfuture2017conditions.TRAFFICMITIGATIONREQUIREMENTSTheCityofRentonrequiresaTransportationMitigationFeepaymentof$75pernewdailytripattributedtonewdevelopment.The28singlefamilyunitsintheAlpineplatwillgenerate267newtripsperdayresultinginanimpactfeeof$20,025(267dailytripsX$75perunit).Typically,creditisgivenforreductionintripsduetotheremovalofexistingfacilities.UsingtheITETripGenerationrateof108.1dailytripsperacreforaNursery(landusecode817),the5.62acreAlpineNurserygenerates608tripsperday.TheremovaloftheAlpineNurseryalongwiththedevelopmentoftheAlpineplatshouldPage4 TraffTheAlpinePlatthereforeresultinanetdecreaseof341tripsperday(608tripsminus267tripsperday).Therefore,notransportationmitigationfeeshouldberequired.SUMMARY,CONCLUSIONSANDRECOMMENDATIONSWerecommendthattheAlpinePlatbeconstructedasshownonthesiteplanwiththefoflowingtrafficimpactmitigationmeasures:•Constructthestreetimprovementsincludingcurb,gutterandsidewalkfortheinternalsitestreetsandhalfstreetimprovementsalongthesitefrontageon160thAveSE,lS?tAveSEandSE144thStreet.Noothertrafficmitigationshouldbenecessary.Ifyouhaveanyquestions,pleasecall425-522-4118.Youmayalsocontactusviae-mailatvincenwtraffex.comorIarrvnwtraffex.com.Verytrulyyours,VincentJ.GegliaPrincipalTraffEx2-3/-/4LarryD.Hobbs,P.E.PrincipalTraffExPage5 TABLEIPMPEAKHOURLEVELOFSERVICESUMMARYTHEALPINEPLATTRAFFICIMPACTANALYSISEXISTING12015WITHOUT2015WITHINTERSECTION2013jPROJECTPROJECT[l6othAveSE/1SEl44thStB12.1SBB12.1SBB12.4SB161stAveSE!SE144thB10.6NBB10.8NBB11.0NB*NumbershownistheaveragecontroldelayinsecondspervehiclefortheworstapproachormovementwhichdeterminestheLOSforanunsignalizedintersectionpertheTransportationResearchBoardHinhwayCaøacityManual(XX)LOSandaveragecontroldelayNBnorthboundapproachSBsouthboundapproachPage6 sE.1a4lhsa0C’a-IEnI-1-’S5135,hsrflTheAlpinePlat-CityofRentonFigureIVicinityMapTrailErNORrMWt5r—TRArricEXPERTaiiisNLlstStLJC1SISI-LI>E2ndPI,SEIJWIStSESthPIS5ILSSE7*StSESrhst45E134111S10-çSE13MbS140ThSr-C0SE143rUStSE138lbSTa0CSE142nSET44LhSSS133wSrSF144thSt—.-aProj&tSiteSiiiSrC’—LIC’EnEnInniSE147thSIbithI.r,r2C’-4-ciC,,InU,0’tflSE7.i91,ridS1JciPdCederRiverPerkViI ——£2•1I_)IIII71////—///£4/-Hh-—-—HHppp7$——_______\‘ppIi‘aI______________=3‘I‘--—-—-,\—j_...__—-mlIifIIIIH£1UTheAlpinePlat-CityofRentonFigureSitePlan2 TraitI_ _ _ __SElajNORTHWESTLnflTRArricEXPERTa925%Iabib•ct-e’I-SE1dUllifiSElIIIk,IItC.,flSEethSt:1____ __ _SE1$2rSLrS145%I135%I‘Si0QE14ØI—6-SE1441kSI8—5.4—,.SLI$4th51Project151kSSitei—2\.ShiIJ.—C.r’,—-In—rnenI-nt‘•2•trnr’Vl4tNS1SE1411kSt4’5’SF141en‘-IoCJeN000ilLilLJ®L10_i2Ø3rr4’,r36‘ir3CN—eN(Nl60thAv&SE144thl6lstAveSE144thPMPeakHourTrafficVolumeLegendEnter1815%PercentageofProjectTrafficExit10Total28.—3PMPeakHourTrafficVolumeTheAlpinePlat-CityofRentonFigurePMPeakHourTripGenerationandDistribution C’TheAlpinePlat-CityofRentonPMPeakHourTrafficVolumesSE6thStSE51tiP1SEISE711:SITraffNCRTNWESr=TRArrcExnni-s.,ZdSEElkStSE14aidStC,rncmSEIOtJiSraxeI40;I-JItIt,WI:1C,-4-CC-7,II.1SEN2nd31SE14411iSILiflProjectSitéE3.p.1’51144thSISE11SlhSta-pfl•S•jiVr—UIIn-;C,fl,TnI:’-:2•M3lIip.a-—JSE1411-:StSFExistingFutureSei4cpwStwithoutProject1l2Project31CDItiie-Q3Ircnc’J0Traffic137Future0)tt330—Ct)12Q3-irnc0withProject0J14516OthAv&SE144thcJ4,irCJCNa,-1231334160thAv&SE144thU)1297147400silt133-0-58r0CDC’J160thAv&SE144thU,C,,1044314162160thAv&SE144th00U)OCDr%J1104161stAveSE144th026000‘iir3c.,0r’J161stAveSE144th0o3ilLCDC’J1137161stAveSE144th161stAveSE144th TECHNICALAPPENDIX PepatedforTraffexTrafficCountConsdtant,Incfline:(2)3-€tC9PlX:(2)9.21l1EUI:Tc,,t1ron11‘VRL000Intarsadlon:I60thAveSE&SEI44thStDaofCount:Toes121162014LooreRenton.WuahintonCIte&thBy:Jet,TimeFromNorthon(Sfl)FromSouthon1B)FromEaston.8)Fromston(s)Inffi’vdInterval60thAveSE60thAveStSEt44thStSE144thStTotdEndinoatTLSItTLSHTLSItTLSR4151’3927000020266I4330574301’0924It05I587262601154451’IIIIS0II900ii4t224255SOUPI10020I09I0IS412200655151’016940000I0306I240I995301’03IS000203330415056545)’I0I20000I01950241050600)’0III50000202550I360576151’000000000000000006.30)’000000000000000006451’000000000000000007l’00hI00000000000000Total,ev680837032014I244417232533704PeakIour415I’Mto5:15i’MTotal214613III013121071I11371216111111813364&jjadt67559133364¶iIIV44%45%41%I’IiFamo00.77079I60thAveSE102I67IIr-SE144thSIIs3.iLEZJPedSE144thSI[IPcdifln,krIIriiI‘I__rn_i4:15PMto5:15PML.1J1dAm,,.:,NSEW3I20Lal/0‘j-leakmuiri‘plane.INtelI13P011’%IIV‘NT02IED0.774.5%‘NT030IICheckVD0.6044%lOT040I,,:364NB063n/aINTCSII0111:364SB00430%tNT000TInc.0.794-1%IhTOr01C,tnjIv,rsII’4T1a0INTllOTuS0IOTII60100Nfl0balI0NT:0INTO2.0INTl0OhII21I50SpecialNo:es‘NTI0Tuedr,vewcyonthusoull:side,pata!Ic110Iracs-0thesoutI:legal160thAveSChailernmtr.imo!NTCl0trafficNoeh:cIeoturnedintothedneewavduringlOTItII.IlteCourtperiod,andtI)celticIcmadeaItfiNT11f0outortiredrivewaydoinglie4iIrintervalNT12III0oliiol3TRA1414OM_O1p l”cparcdfor‘rraffexTrafficQ,untConwItant.IncRicn:(2)3L.6fl9FX:(2SJ)9r72ll&MI:T,,@Wt2n.ccnWBEiDBEIntarsadlan:I61s1AreSE&SE(44thSIDeotcount:Toe,12/16/2014LocaboitKenton,WashtotonChecked‘:Jo’sTmcFromNorthon(SB)FromSouthonOIB)FromEaston(S)From%ston(ES)Inl&vdInterval16151ArcSEI6IstArcSESE44thStSE144thSiTotEndinsalTLSRTLSKTLSKTLSK4150000(I040I432802I29127843000II(I0Iaao2I580203051024451’00ai02aiai320I026II745001’000I04aiaitI302896!5151’000I03aaia33I10342294sjoi’ao0I02a2223400031880$451’002a7a4II16aaI34(58060000000I120aII21aa234(3836150o000aaoaaaaaao0006301’000000000aaaao0006451’000000oaoaoaoaaa07.000000000000aaaaaaaTotalSurvey0oa62420I(2924029424695652leakIlour5:00I’MIa6:aaI’MTotalolol0411241064110411ii31133158337j2tach430109193337%IIV11%46%05%15111:01000.760370.90,l6IsIAveSELjEThkcSE144111St4[a]l’edSE1440iStI31PC3IOIBikep(5423%32630Hike193I5:1111PMto6:00PM[-jPcdAm,,,,NSEWI’ed[2306LitI’Hh’leakflourIWw’teNTDl-‘(.4Iflikc!0P1W%IIV(NT02ILII0.870.5%INT03I)I62II30ICl,cckWU0.764.6%INTO4I—0In:337Nm06333%INTOI0I92IOut:337Sm0.50n/aNTot0161stAveSET11,1.0902.1%tNT070BIcyclesFrom:NISIEIwICondihum.IINTOS0INTOI‘‘0KItS0INTt20INIII06fft30INTII0INTt40INTI2, ,,0INTD5.00121D02INTItc!!_l0Snee/atNotesOffalaINTOtItNTtt0tNTlt0INTIIittNTIZ.,ol01iii0/tTRA1414OM_G2p ExistingPMPeakHour3:160thAveSE&SE144thSt12/31/2014)ntersection.9;mtDelay,s/veh2.1Movement*EBLEBTEBRWBLWBTWBRNBLNBTNBRSBLSBTSBRVoLvehTh1211831137313204630ConflictingPeds,#/hr000000000000SignControlFreeFreeFreeFreeFreeFreeStopStopStopStopStopStopRTChannelized--None-.None--None.-NoneStorageLength---.-----VehinMedianStorage,#-0- -0-3-0-Grade,%-0--0--0-0-PeakHourFactor797979797979797979797979HeayVehicles,%440055000303MvmtFlow1514941173394305840KJorIMinor-—.-MajorlMori——Minor2ConflictingFlowAll2130015300379397151379380193Stage1-----182182196196-Stage2----- -197215-183184-CriticalHdwy4.14--4.1- -7.16.56.27.136.56.23CriticalHdwyStg1---- - -6.15.5-6.135.5CriticalHdwyStg2---- -6.15.5-6.135.5-Follow-upHdwy2.236--2.2--3.543.33,52743.327PotCap-iManeuver1345-.1440--582544901577556846Stage1--- --.824753-803742-Stage2- -----809729-816751-Platoonblocked,%---MovCap-iManeuver1345--1440--573537901569549846MovCap-2Maneuver------573537-569549-Stage1------814744-793741-Stage2------804728-803742-Approach—EB- .:**-.*:.WENBZ’WSB“1HCMControlDelay,s0.7011.512.1HCMLOSBBMi&iii&MJoTiAvmtNBLn1EBLEBTESRWAl.WBTWBRSBLn1,*Capacity(veh/h)5581345--1440--568HCMLaneV/CRatio0.0110,011--0.001--0.109HCMControlDelay(s)11.57]0-7.50-12.1HCMLaneLOSBAA-AA-BHCM95th%tileQ(veh)00--0--0.4•BaselineSynchro8LightReportPage1 ExistingPMPeakHour6:161stAveSE&SE144thSt12/31/2014)ntersectionmtDelay,s/veh1.2E,ementEBLfEBRWBLEWgtWBRNBLNBTNBR::SBLSBTSBRVoveh/h313358410412406004ConflictingPeds#/hr000000000000SignControlFreeFreeFreeFreeFreeFreeStopStopStopStopStopStopPTChannelized--None- -None-.None--NoneStorageLength--- --- ----.-VehinMedianStorage,#-0- -0- -0--0-Grade,%-0- -0-0--0PeakHourFactor909090909090909090909090HeavyVehicles,%040050000000MvmtFlow314864411612707004M*rmnorMafIvlajor2NnoriMnor2-iConflictingFlowAll1170021200314313180315344116Stage1. - -187187-125125Stage2-.----127126-190219-CriticalHdwy4.1--4.1--7.16.56.27.16.56.2CriticalHdwyStg1------6.15.5-6.15.5CriticalHd,Stg2------6.15.5-6.15.5-Follow-upHdwy2.2--2.2--3.543.33_B43.3PotCap-iManeuver1484--1370--643606868642582942Stage1------819749-884796-Stage2-----882796-816726-Platoonblocked,%----MovCap-iManeuver1484--1370--638603868635579942MovCap-2Maneuver------638603-635579-Stage1------817748-882794-Stage2------875794-808725-4pproachWB--NFfl._.8BHCMControlDelay,a0.10.310.68.8HCMLOSBAMfiLane/MajorMvmt_:L.__NBLn1__ã1EEftT$EBR_WVWBTLVBRSBLhi-Capacity(veh/h)6741484- -1370--942HCMLaneV/CRatio0M90.002- -0.003--0.0051-1CMControlDelay(s)10.67.40-7.60-8.8HCMLaneLOSBAA-AA-AHCM95th%tileQ(veh)0.20--0--0BaselineSynchro8LightReportPage2 FutureWithoutProjectPMPeakHour3:160thAveSE&SE144thSt12/31/2014htersection.tN2lotDelay,s/veh2.6.lovementEBLEBTEBRWBLWBTWBRNLNBTNBRSBLStVolveh!h12125311453332049519ConctgPeds,#.;’hr000000000000SignControlFreeFreeFreeFreeFreeFreeSlopStopStopStopStopStopRTChannelized--None--None--None- -NoneStorageLength--------- - --VehinMedianStorage,#-0--0--0- -0-Grade,%-0--0--0--0-PeakHourFactor7979797979797979797979°Heavyvehicles,%440055000303MvmtFlow15158411844243062624Maj&?MnthMajori--—Major2-Minorl—-—Minor2———iConflictingFlowAll2250016200413419160399399204Stage1- -----191191-207207-Stage2-----222228-192192CriticalHdwy4.14--4.1- -7.16.56.27.135.56.23CriticalHdStg1------6.15.5-6.135.5-CriticalHdwyStg2---- -6.15.5-6.135.5-Follow-upHdwy2.236--2.2--3.543.33.52743.327•PotCap-iManeuver1332- -1429--553528890560542834Stage1-- ----815746-793734-Slage2-- ----785719-807745-Platoonblocked,%--MovCap-iManeuver1332--1429--527521890552535834MovCap-2Maneuver------527521-552535-Stage1------805737-783733-Stage2------755718-795736-Approath4f:WB-.WE7TSFETIHCMControlDelay,s0.7011.912HCMLOSBBMirToTiTvit.NBLn1_1C_EBI&_EBR_WBL_WBT_WBRSBLn1Capacity(veh/h)5251332--1429--604HCMLaneV/CRatio0.0120.011--0,001- -0.153HCMControlDelay(a)11.97.70-7.50-12HCMLaneLOSBAA-AA-BHCM95th%tileQ(veh)00--0--0.5BaselineSynchro8LightReportPage1 FutureWithoutProjectPMPeakHour6:161stAveSE&SE144thSt12/31/2014friiisedllonmtDelay,s/veh12vñ,enfERLEBTEBAWBLWBTWBRNBL-NBTNBRSRI..SBTSBRVoivehlh314162411012506004ConfhctingPeds,#!hr000000000000SignControlFreeFreeFreeFreeFreeFreeStopStopStopStopStopStopRTChannelized--None--None--None- -NoneStorageLength---- ----- ---VehinMedianStorage,#-0--0--0- -0-Grade,%-0--0--0- -0-PeakHourFactor909090909090909090909090Heat’Vehizles,%040050000000MvmtFlow315769412212807004Major/MinorMajorlMajor2MinoriMinor?ConflictingFlowAll1230022600332330191333364123StageI------198198-132132-Stage2---- --134132-201232-CriticalHdwy4.1--4.1--7.16.56.27.16.56.2CriticalHdwyStg1-----6.15.5-6.15.5-CriticalHdiStg2------6.15.5-6.15.5-Follow-upHd’2.2--2.2--3_S43.33.543.3PotCap-iManeuver1477--1354--625592856624567933Stage1---. --808741-876791-Stage2------874791-805716-Platoonblocked,%--- -MovCap-iManeuver1477--1354--620589856617564933MovCap-2Maneuver------620589-617564-Stage1-----806740-874789-Stage2------867789-797715-pproaciiEBWWSBHCMControlDelay,s0.10.310.86.9HCMLOSBAMinorLane/MajorMvmtNBLn1ERLERTERRWBLWBTWBRSBLn1-.Capacity(veh!h)6551477--1354--933HCMLaneV/CRatio0.0530.002--0.003--0.005HCMControlDelay(s)10.87.40-7.70-8.9HCMLaneLOSBAA-AA-AHCM95th%tileQ(veh)0.20--0--0BaselineSynchro8LightReportPage2 FutureWithProjectPMPeakHour3:160thAveSE&SE144thSt12/31/2014Intersection—________________________-.—mtDelay,s/veh2.8MdithintEBJEBTEBRWBWBR]LNBTNBRSBLSBTSBRVol,veh/h13129741473453251519ConfctingPeds,#/hr000000000000SignControlFreeFreeFreeFreeFreeFreeStopStopStopStopStopStopRTChannelized--None--None--None--NoneStorageLength----- -------VehinMedianStorage,#-0--0--0--0-Grade,%-0--0--0--0-PeakHourFactor797979797979797979797979Hea’Vehictes,%440055000303MvmtFlow16163951864364365624MiEi?Mmnor-MaJ&rIiKajo&-MinorlMinor2%.ConflictingFlowAll2290017200434440168422423208Stage1------201201-218218-Stage2------233239-204205-CriticalHdwy4.14--4.1--7.16.56.27.136.56.23CriticatHdwySIg1---- --6.15.5-6.135.5-CriticalHdwyStg2---- --6.15.5-6.135.5-Follow-upHdwy2.236--2.2--3.543.33.52743.327PotCap-iManeuver1327--1417--536514881540526830Stage1---- --805739-782726-Stage2---- --775711-796736-Platoonblocked,%----MovCap-iManeuver1327--1417--509505881528517830MovCap-2Maneuver---- --509505-528517Stage1------795729-772723-Stage2------743708-779726-oWWE:iW-NB•EWSBEE1HCMControlDelay,s0.70.211.612.4HCMLOSBBM[nortane/MrajorMvmtNBLn1EAtEB]WBR:WBT:;.:WBRSBLn1ICapacity(veh/h)5551327--1417--581HCMLaneV/CRatio0.0230.012--0.004--0.163HCMControlDelay(s)11.67.70-7.50-12.4HCMLaneLOSBAA-AA-BHCM95th%tileQ(veh)0.10- -0--0.6BaselineSynchro8LightReportPage1 FutureWithProjectPMPeakHour6:161stAveSE&SE144thSt12/31/2014ntersedionIntDelay,s/veh1.3MmentLEfE-WLWãtWBRNBLNBTNBRSBLSBT*SBRVol1veh/h314368711312808004ConfctingPeds#/hr000000000000SignControlFreeFreeFreeFreeFreeFreeStopStopStopStopStopStopRTChannelized--None--None--None--NoneStorageLength------ ------VehinMedianStorage,#-0--0--0--0-Grade,%-0- -0- -0--0-PeakHourFactor909090909090909090909090HeaiVehicles,%040050000000MvmtFlow315976812613109004Major/MinorMajorlMajor2MinoriMinor2ConflictingFlowAll1270023400347345197350383126Stage1--- ---203203-142142-Stage2--- ---144142-208241-CriticalHdwy4.1--4.1--7.16.56.27.16.56.2CriticalHdwyStg1------6.15.5-6.15.5-CñticalHdwyStg2------6.15.5-6.15.5-Follow-upHdwy2.2--2.2--3.543.33.543.3PotCap-iManeuver1472--1345--611581849608553930Stagel------804737-866783-SIage2------864783-799710-Platoonblocked,%----MovCap-iManeuver1472--1345--604576849598549930MovCap-2Maneuver------604576-598549-Stage1- -----802736-864778-Stage2--- ---855778-789709-4pproachEB*WB-NBSBHCMControlDelay,a0.10.4118.9HCMLOSBAMinorLane/MalorMvmtNäLñf_L_EBT__EBRWL_WBT_WBRLrfi——Capacity(veh/h)6451472--1345--930HCMLaneV/CRatio0.0620.002--0.006--0.005HCMControlDelay(s)ii7.50-7.70-8.9HCMLaneLOSBAA-AA-AHCM95th%tileQ(veh)0.20--0--0BaselineSynchro8LightReportPage2 Traft—NCRTI-/WESTTRAFFICEXPERTS11410NE124thSb,#59DKirkland.WA98034Phone.425.522.4118Fax.425.522.4311October12,2015Mr.RoyBoyer14609161’Ave.SERenton,WA98059Re:TheAlpinePlat-CityofRentonAddendumtotheTrafficImpactAnalysisWearepleasedtopresentthisaddendumtotrafficimpactanalysistoprovideadditionalinformationrequestedbytheCityofRenton.Therequestedinformationincludesthefairsharecalculationoftheconstructingatrafficsignalat156thAveSE/SE142ndintersectionandalevelofservicecalculationforthe156thjAveSE/SE144thintersection.TheCityhasdeterminedthatdevelopmentsintheareaarerequiredtocontributetotheconstructionofatrafficsignalatthe156thAveSE/SE142ndSt.intersection.Thefairshareisbasedonthenet,newPMpeakhourtripsgeneratedbythedevelopmentthatpassthroughtheintersection,dividedbythetotal1310tripsattheintersection,timesthe$500,000costofthesignal.TheAlpinePlatwillgenerate28PMpeakhourtripsasshownintheTIA.However,usingtheITETripGenerationrateof8.06PMpeakhourtripsperacreforaNursery((landusecode817),the5.62acreexistingAlpineNurserycurrentlygenerates45PMpeakhourtrips.TheremovaloftheAlpineNurseryinconjunctionwiththedevelopmentoftheAlpineplatshouldthereforeresultinanetdecreaseof17PMpeakhourtrips.Therefore,nofairsharecontributionshouldberequiredforconstructionofthesignal.ThenetdecreaseintripsresultingfromtheAlpinePlatdevelopmentshouldalsoimprovethelevelofserviceattheSElS6AveSE/SEl44St.intersection.Ifyouhaveanyquestions,pleasecall425-522-4118.Youmayalsocontactusviae-mailatvincenwtraffex.comorlarrv(nwtraffex.com.Verytrulyyours,VincentJ.GegliaLarryD.Hobbs,P.E./0-/Z-/rTraffExTraffEx APPENDIX“H”GEOTECHNICALENGINEERINGSTUDY02016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage75TechnicalInformationReportCityofRenton EarthSolutionsNWLLCJanuary12,2015ES-3377.02Mr.RoyBoyer14609—lel5tAvenueSoutheastRenton,Washington98059Subject:AlpineNursery—BoyerProperties16023Southeast144°’StreetRenton,WashingtonReference:EarthSolutionsNW,LLCGeotechnicalEngineeringStudyES-3377,June5,2014EarthSolutionsNWLLC•GeotechnicalEngineering•ConstructionMoniloring•EnvironmentalSciencesDearMr.Boyer:Asrequested,EarthSolutionsNW,LLC(ESNW)hasreviewedthereferencedgeotechnicalengineeringstudywithrespecttotheapplicabilityofthereporttothecurrentlyproposedproject.•Basedonourreview,therecommendationsincludedinthereportremainapplicabletothecurrentlyproposedproject.Ifyouhavequestionsorrequireadditionalinformation,pleasecall.Sincerely,•cc:D.R.StrongAttention:Mr.MaherJoudi(Emailonly)EARTHSOLUTIONSNW,LLCKyleR.Campbell,P.E.Principal1805-136thPlaceN.E.,Suite201Bellevuc,WA98005•(425)449-4704•FAX(425)449-4711 EarthSolutionsNWacGeotechnicalEngineeringGcologyEnvironmentalScienEistsConstructionMonitoring-- PREPAREDFORJAYMARCHOMESJune5,2014StephenH.AvriIStaffGeologistPrincipalGEOTECHNICALENGINEERINGSTUDYALPINEGARDENSPRELIMINARYPLAT16023SOUTHEAST144thSTREETRENTON,WASHINGTONES-3377EarthSolutionsNW,LLC1805-136thPlaceNortheast,Suite201Bellevue,Washington98005Phone:4254494704Fax:425449-4711KyleR.Campbell,P.E.TollFree:866-336-8710 ImporlaniIn!ormahonAboutYourGeotechoicalENgiNeeriNgReportICeotechnicalServicesArePerformedforSpecificPurposes,Persons,andProjectsGeotechnicafengineersstructuretheirservicestomeetthespecificneedsoftheircUents.Ageotechnicalengineeringstudyconductedforacivilengineermaynotfulfilltheneedsofaconstructioncontractororevenanothercivilengineer.Becauseeachgeotechnicalengineeringstudyisunique,eachgeolechnicalengineeringreportisunique,preparedsolelyfortheclient.Nooneexceptyoushouldrelyonyourgeotechnicalengineeringreportwithouttirsconferringwiththegeotechnicalengineerwhopreparedit.Andnoone—notevenyou—shouldapplythereportforanypurposeorprojectexcepttheoneoriginallycontemplated.bReadtheFullReportSeriousproblemshaveoccurredbecausethoserelyingonageotechnicalengineeringreportdidnotreaditall.Donotrelyonanexecutivesummary.Donotreads&ectedelementsonly.ACeotechnicalEngineeringReportIsBasedonAUniqueSetofProject-SpecificFactorsGeotechnicalengineersconsideranumberofunique,project-specificfactorswhenestablishingthescopeofastudy.Typicalfactorsinclude:theclienrsgoats,objectives,andriskmanagementpreferences;thegeneralnatureofthestructureinvolved,itssize,andconfiguration;thelocationofthestructureonthesite;andotherplannedorexistingsiteimprovements,suchasaccessroads,parkinglots,andundergroundutilities.Unlessthegeotechnicalengineerwhoconductedthestudyspecificallyindicatesotherwise,donotrelyonageotechnicalengineeringreportthatwas:•notpreparedforyou,•notpreparedforyourproject,•notpreparedforthespecificsiteexplored,or•completedbeforeimportantprojectchangesweremade.Typicalchangesthatcanerodethereliabilityofanexistinggeotechnicalengineeringreportincludethosethataffect:•thefunctionoftheproposedstructure,aswhenit’schangedfromaparkinggaragetoanofficebuilding,orfromalightindustrialplanttoarefrigeratedwarehouse,•elevation!configuration,location,orientation,orweightoftheproposedstructure,•compositionofthedesignteam,or•projectownership.Asageneralrule,alwaysinformyourgeotechnicalengineerofprojectchanges—evenminorones—andrequestanassessmentoftheirimpacLGeotechnicalengineerscannotacceptresponsibilityorliabilityforproblemsthatoccurbecausetheirreportsdonotconsiderdevelopmentsofwhichtheywerenotinlormed.SubsurfaceConditionsCanChangeAgeotechnicalengineeringreportisbasedonconditionsthatexistedatthetimethestudywasperformed.Donotrelyonageotechnicalengineering,epo#whoseadequacymayhavebeenaffectedby:thepassageoftime;byman-madeevents,suchasconstructiononoradjacenttothesite;orbynaturalevents,suchasfloods,earthquakes,orgroundwaterfluctuations.Alwayscontactthegeotechnicalengineerbeforeapplyingthereporttodetermineifitisstillreliable.Aminoramountofadditionaltestingoranalysiscouldpreventmajorproblems.MostCeotechnicalFindingsAreProfessionalOpinionsSueexplorationidentfiessubsurfaceconditionsonlyatthosepointswheresubsurfacetestsareconductedorsamnpfesaretaken.Geotechnicalengineersreviewfieldandlaboratorydataandthenapplytheirprofessionaljudgmenttorenderanopinionaboutsubsurfaceconditionsthroughoutthesite.Actualsubsurfaceconditionsmaydiffer—sometimessignificantly—fromthoseindicatedinyourreport.Retainingthegeotechnicalengineerwhodevelopedyourreporttoprovideconstructionobservationisthemosteffectivemethodofmanagingtherisksassociatedwithunanticipatedconditions.AReport’sRecommendationsAreNotFinalDonotoverretyontheconstructionrecommendationsincludedinyourreport.Thoserecommendationsarenotfinal,becausegeotechnicalengineersdevelopthemprincipallyfromjudgmentandopinion.GeotechnicalengineerscanfinalizetheirrecommendationsonlybyobservingactualJ subsurfaceconditionsrevealedduringconstruction.Thegeotechnicalengineerwhodevelopedyourreportcannotassumeresponsibilityorliabilityforthereport’srecommendationsifthatengineerdoesnotperformconstructionobservation.AGeotechnicalbigineeringReportIsSubjecttoMisinterpretationOtherdesignteammembers’misinterpretationofgeotechnicalengineeringreportshasresultedincostlyproblems.Lowerthatriskbyhavingyourgeotechnicalengineerconferwithappropriatemembersof(hedesigntearaftersubmittingthereport.Msoretainyourgeotechnicalengineertoreviewperil—rentelementsofthedesignteam’splansandspecifications.Contractorscanalsomisinterpretageotechnicalengineeringreport.Reducethatriskbyhavingyourgeotechnicalengineerparticipateinprebidandpreconstructionconferences,andbyprovidingconstructionobservation.DoNotRedrawtheEngineer’sLogsGeolechnicalengineerspreparefinalboringandtestinglogsbasedupontheirinterpretationoffieldlogsandlaboratorydata.Topreventerrorsoromissions,thelogsincludedinageotechnicalengineeringreportshouldneverberedrawnforinclusioninarchitecturalorotherdesigndrawings.Onlyphotographicorelectronicreproductionisacceptable,butrecognizethatseparatinglogsfromthereportcanelevateriskGiveContractorsaCompleteReportandGuidanceSomeownersanddesignprofessionalsmistakenlybelievetheycanmakecontractorsliableforunanticipatedsubsurfaceconditionsbylimitingwhattheyprovideforbidpreparation.Tohelppreventcostlyproblems,givecontractorsthecompletegeotechnicalengineeringreport,butprefaceitwithaclearlywriffenletteroftransmittal.Inthatlellecadvisecontractorsthatthereportwasnotpreparedforpurposesofbiddevelopmentandthatthereport’saccuracyislimited;encouragethemtoconferwiththegeotechnicalengineerwhopreparedthereport(amodestfeemayberequired)and/ortoconductadditionalstudytoobtainthespecifictypesofinformaticntheyneedorprefer.Aprebidconferencecanalsobevaluable.Besurecontractorshavesufficienttimetoperformadditionalstudy.Onlythenmightyoubeinapositiontogivecontractorsthebestinformationavailabletoyou,whilerequiringthemtoatleastsharesomeofthefinancialresponsibilitiesstemmingfromunanticipatedconditions.ReadHesponsthihtyProvisionsCloselySomeclients,designprofessionals,andcontractorsdonotrecognizethaigeotechnicalengineeringisfarlessexactthanotherengineeringdisciplines.Thislackofunderstandinghascreatedunrealisticexpectationsthathaveledtodisappointments,claims,anddisputes.Tohelpreducetheriskofsuchoutcomes,geotechnicalengineerscommonlyincludeavarietyofexplanatoryprovisionsintheirreports.Sometimeslabeled‘limitations”manyoftheseprovisionsindicatewheregeotechnicalengineersresponsibilitiesbeginandend,tohelpothersrecognizetheirownresponsibilitiesandrisks.Read(baseprovisionscloselyAskquestions,Yourgeolechnicalengineershouldrespondfullyandfrankly.GeoenvironmentalConcernsAreNotCoveredTheequipmenttechniques,andpersonnelusedtoperformagecenv/ron-mentalstudydiffersignificanflyfromthoseusedtoperformageotechnleststudy.Forthatreason,ageotechnicalengineeringreportdoesnotusuallyrelateanygeoenvironmentalfindings,conclusions,orrecommendations;e.g.,aboutthelikelihoodofencounteringundergroundstoragetanksorregulatedcontaminants.Unanticipatedenvironmentalproblemshaveledtonumerousprojectfailures.Ifyouhavenotyetobtainedyourowngeoenvironmentalinformation,askyourgeotechnicalconsultantforriskmenagementguidance.Donotrelyonanenvironmentalreportpreparedforsomeoneelse.ObtainProfessionalAssistanceToDealwithMoldDiversestrategiescanbeappliedduringbuildingdesign,construction,operation,andmantenancetopreventsignificantamountsofmoldfromgrowingonir,doorsurfaces.Tobeeffective,allsuchstrategesshouldbedevisedfortheexpresspurposeofmoldprevention,integratedintoacomprehensiveplan,andexecutedwithdiligentoversightbyaprofessionalmoldpreventionconsultant.Becausejustasmallamountofwaterormoisturecanleadtothedevelopmentofseveremoldinfestations,anumberofmoldpreventionstrategiesfocusonkeepingbuildingsurfacasdry.Whilegroundwater,waterinfiltration,andsimifarissuesmayhavebeenaddressedaspartofthegeotechnicalengineeringstudywhosefindingsareconveyedin-thisreport,thegeotechnicalengineerinchargeofthisprojectisnotamoldpreventionconsultant;noneoftheservicesper-(armedinconnectionwiththegeotechnicalengineer’sstudyweredesignedorconductedforthepurposeofmoldprevention.ProperimplementationoftherecommendationsconveyedInibisreportwillnotofitselfbesufficienttopreventmoldfromgrowinginoronthestructureinvolved.Rely,onYourASFE-MemherGeotechncialEngineerforAdditionalAssistanceMembershipinASFEJTheBestPeopleonEarthexposesgeotechnicalengineerstoawidearrayofriskmamgementtechniquesthatcanbeofgenuinebenefitforeveryoneinvolvedwithaconstructionprojectConferwithyouASFE-membergeotechnicalengineerformoreinformation.ASFETbUleilrilal,‘Itaut8811ColesvilleRoad/SuiteClOG,SilverSpring,MD20910Telephone;301/565-2733Facsimile:301/589-2017e-mail:inb@asfe.crgM%wasfe.orgGop%gh!2001&ASFE,incDuiion,repmducllo,,,orcopyingofthisdocument,hiwholeorInpartbyanymeanswhaoeverIsstrictlyprohibited,exceptwithA5FFsspecificwrittenpermission,Ewerpling,quotIng,orotherwiseextractingwordingfromthisdocumentispermittedonlywiththeexpresswrittenpermissionofASFE,andonlyforpurposesofscholarlyresearchorbookreview.OnlymembetsofASFEmayusethisdocumentasacomplementtoorasanelementofageotechnicalengineeringreport.Anyotherfirm,Individual,orotherentitythatsousesthisdocumentwilhoufbeinganASFEmembercouldbecommittingnegligentorintentional(fraudulent)misrepresentation.(:GER0S345,oM EarthSolutionsNWLLCJayMarcHomes7525Southeast24thStreet,Suite487MercerIsland,Washington96040Attention:Mr.JayMezistranoDearMr.Mezistrano:June2014EarthSolutionsNWLLC•CeotechnicalEngineering•ConstructionMoniloring•EnvironmentalSciencesEarthSolutionsNW1LLC(ESNW)ispleasedtopresentthisreporttitled“GeotechnicalEngineeringStudy,AlpineGardensPreliminaryPlat,16023Southeast144thStreet,Renton,Washington”.Ingeneral,thesiteisunderlainprimarilybyglacialoutwashandlimitedareasoffillsurroundingtheexistingstructuresandutilityalignments.Inouropinion,theproposedresidentialstructurescanbesupportedonconventionalcontinuousandspreadfootingfoundationsbearingoncompetentnativesoilencounteredatdepthsbetweentwotofourfeet;orstructuralfill.Groundwaterseepagewasnotobservedatanyofthetestlocations.However,seepageshouldbeexpectedduringgradingactivities,particularlyduringwinter,springandearlysummermonths.preparation,drainage,andotherpertinentappreciatetheopportunitytobeofservicetoregardingthecontentofthisgeotechnical1805136thPlaceN.E.,Suitc201•Bellevue,WA98005•(425)449-4704•FAX(425)449-4711Recommendationsforfoundationdesign,siterecommendationsareprovidedinthisstudy.Weyouonthisproject.Ifyouhavequestionsengineeringstudy,pleasecall.Sincerely)EARTHSOLUTIONSNW,LLCStephenH.AvdlStaffGeologist. TableofContentsES-3377PAGEINTRODUCTION1GeneralIProlectDescription2SITECONDITIONS2Surface2Subsurface2Fill3Topsoil3NativeSoil3GeologicSetting3Groundwater3DISCUSSIONANDRECOMMENDATIONS4General4SitePreparationandGeneralEarthwork4WetSeasonGrading5In-situSoils5ImportedSoils5StructuralFill6Foundations6SeismicDesignConsiderations6Slab-On-GradeFloors7RetainingWalls7Drainage8ExcavationsandSlopes9UtilityTrenchBackfill9PavementSections9LIMITATIONS10AdditionalServices10EarthSolutionsNW,LLC TableofContentsCont’dES-3377GRAPHICSPlateIVicinityMapPlate2TestPitLocationPlanPlate3RetainingWallDrainageDetailPlate4FootingDrainDetailAPPENDICESAppendixASubsurfaceExplorationTestPitLogsAppendixBLaboratoryTestResultsEarthSolutionsNW,LLC GEOTECHNICALENGINEERINGSTUDYALPINEGARDENSPRELIMINARYPLAT16023SOUTHEAST144thSTREETRENTON,WASHINGTONES-3377INTRODUCTIONGeneralThisgeotechnicalengineeringstudywaspreparedfortheproposedresidentialdevelopmenttobeconstructedonthesouthsideofSoutheast144thStreetinRenton,Washington.Thesiteiscomprisedofthreetaxparcels;andislocatedsouthofSoutheast144thStreet,between160thAvenueSoutheastand161stAvenueSoutheast.Thepurposeofthisstudywastodevelopgeotechnicalrecommendationsfortheproposeddevelopment.Ourscopeofservicesforcompletingthisgeotechnicalengineeringstudyincludedthefollowing:•Reviewingtheprojectdetails;•Excavation,loggingandsamplingoftestpitsexcavatedatthesite;•Engineeringanalysesofdataobtainedthroughthesiteexploration,and;•Preparationofthisreport.Thefollowingdocuments/mapswerereviewedaspartofourreportpreparation:•ConceptualSitePlan-OptionC,byESMConsultingEngineers,LLC.,SheetPL-03,datedApril18,2014;•KingCountyiMaponlineresource;•GeologicMapofWashington,SouthwestQuadrant,byWalsh,etal,1987,and;WashingtonStateUSDASoilConservationSurvey(SCS). JayMarcHomesES-3377June5,2014Page2ProiectDescriptionWeunderstandthesitewillbedevelopedwith30single-familyresidentialstructures,on-siteroadways,parkingareas,andassociatedimprovements.Gradingplanswerenotavailableatthetimeofthisreportproduction;however,giventhetopographicchangeacrossthesite,weanticipategradingactivitieswilllikelyinvolvecutsandfillsontheorderofeightfeetorlesstoestablishthefinaldesigngrades.Finalbuildingloadswerenotavailableatthetimeofourreport.However,weanticipatewallloadsforonetotwo-storysingle-familyresidentialstructureswillbeontheorderofIto2kipsperlinealfoot;andslab-on-gradeloadingof150poundspersquarefoot(psf).Astormwaterpondisproposedtobelocatedonthesouthsideofthesite.Designparameterswerenotavailableatthetimeofreportproductionforthepond.Iftheabovedesignestimatesareincorrectorchange,ESNWshouldbecontactedtoreviewtherecommendationsinthisreport.ESNWshouldreviewthefinaldesigntoconfirmthatourgeotechnicalrecommendationshavebeenincorporatedintothefinaldesign.SITECONDITIONS•SurfaceThesiteislocatedonthesouthsideofSoutheast144thStreet,andeastof160thAvenueSoutheastinRenton,Washington.TheapproximatelocationofthepropertyisillustratedonPlateI(VicinityMap).Thesiteisroughlyrectangularinshapeandconsistsofthreetaxparcels.Themajorityofthesiteiscurrentlydevelopedwithaplantnursery.Greenbeltsandseveralsingle-familyresidencesarealsolocatedonthesubjectsitewithintheproposeddevelopmentenvelope.Theexistingsitetopographydescendsverygentlyfromthestreetelevationtowardsthesouth;withelevationchangeontheorderofapproximately15feet.Vegetationconsistedprimarilyofgrassylandscapedareaslocatedbetweenplanterstripsandgreenhouses.ESNWobservedsecond-growthfirandcedartreesonthesiteperipheryduringourfieldwork.SubsurfaceArepresentativeofESNWobserved,loggedandsampledseventestpitsexcavatedwithatrack-hoeacrossthesite.Thetestpitswereexcavatedforthepurposesofcharacterizingthesubsurfaceconditions.TheapproximatelocationsofthetestpitsaredepictedontheTestPitLocationPlan(Plate2).PleaserefertothetestpitlogsprovidedinAppendixAforadetaileddescriptionofthesubsurfaceconditions.EarthSolutionsNW,LLG JayMarcHomesES-3377June5,2014Page3FillFillwasencounteredattestpitlocationTP-4,locatedinthesouthernportionofthesite.Fillsoilshouldbeanticipatedsurroundingtheexistingresidentialstructuresandoutbuildingsthroughoutthesite.Thefillwasobservedtoextendtothreeandonehalffeetbelowexistinggrades.Thesiltysandwithgravel(UnifiedSoilClassification,SM)fillmaybesuitableforsupportoffoundations;howeverarepresentativeofESNWshouldberetainedduringtheconstructionphasesofthesitedevelopmenttoevaluatethesuitabilityofanyon-sitesoilsforuseasstructuralfillorbearingoffoundations.TopsoilTopsoilwasencounteredatallbutoneofthetestpitlocationsextendingtodepthsofbetweenabouttwotosixinchesbelowexistinggrade.Topsoilisnotsuitableforuseasstructuralfillnorshoulditbemixedwithmaterialtobeusedasstructuralfill.Topsoilorotherwiseunsuitablematerialcanbeusedinlandscapingareasifdesired.NativeSoilUnderlyingthetopsoilandfill,nativesoilconsistingprimarilymediumdensetodenseglacialoutwashconsistingofpoorlygradedsandwithsiltandgravel(SP)wasencounteredextending•tothemaximumexplorationdepthoffivefeetbelowexistinggrades.Thenativesoilconsistedofsiltysandwithgravel(SM);andpoorlygradedsandwithsiltandgravel(SF).Thenativesoiltransitionedfromamediumdenseconditiontodenseatapproximatelythreefeetindepthatmostofthetestpitlocations.GeologicSettingThereferencedgeologicmapresourceidentifiesglacialoutwash(Qgo)depositsacrossthesiteandsurroundingareas.ThereferencedSCSsoilsurveyidentifiesEverettGravellySandyLoam(EvE)seriessoilsacrossthesiteandsurroundingarea.Everettgravellysandyloamsoilsconsistofglacialoutwashformedonterracesandtypicallypresentalowtomoderateerosionhazard;andaresomewhatexcessivelydrained.Thesoilconditionsobservedatthetestpitlocationsaregenerallyconsistentwithglacialoutwashdeposits.GroundwaterGroundwaterwasnotobservedatanyofthetestpitlocationsduringthefieldwork(May2014).However,seepageshouldbeexpectedatsomelocations,particularlyduringthewinter,springandearlysummermonths.Groundwaterseepageratesandelevationsfluctuatedependingonmanyfactors,includingprecipitationdurationandintensity,thetimeofyear,andsoilconditions.Ingeneral,groundwaterflowratesarehigherduringthewetter,wintermonths.EarthSolutionsNW,LLC JayMarcHomesES3377June5,2014Page4DISCUSSIONANDRECOMMENDATIONSGeneralInouropinionconstructionoftheproposedresidentialdevelopmentisfeasiblefromageotechnicalstandpoint.Theproposedbuildingscanbesupportedonconventionalcontinuousandspreadfootingfoundationsbearingoncompetentnativesoil,existingcompetentfilloratleasttwofeetofstructuralfill.Slab-on-gradefloorsshouldbesupportedonafirmandunyieldingsubgrade.Recommendationsforfoundationdesign,sitepreparation,drainage,andotherpertinentgeotechnicalrecommendationsareprovidedinthefollowingsectionsofthisstudy.ThisstudyhasbeenpreparedfortheexclusiveuseofJayMarcHomesandtheirrepresentatives.Nowarranty,expressedorimpiled,ismade.Thisstudyhasbeenpreparedinamannerconsistentwiththelevelofcareandskillordinarilyexercisedbyothermembersoftheprofessioncurrentlypracticingundersimilarconditionsinthisarea.SitePreparationandEarthworkSitepreparationactivitieswillinvolveremovalofexistingstructures,siteclearingandstripping,andimplementationoftemporaryerosioncontrolmeasures.Theprimarygeotechnical•considerationsassociatedwithsitepreparationactivitiesincludebuildingpadsubgradepreparation,undergroundutilityinstallations,andpreparationofpavementsubgradeareas.Temporaryconstructionentrancesanddrivelanes,consistingofatleast12inchesofquarryspallscanbeconsideredinordertominimizeoff-sitesoiltrackingandtoprovideastableaccessentrancesurface.Erosioncontrolmeasuresshouldconsistofsiltfencingplacedalongthedowngradientsideofthesite.Soilstockpilesshouldbecoveredorotherwiseprotectedtoreducesoilerosion.Temporarysedimentationpondsorotherapproachesforcontrollingsurfacewaterrunoffshouldbeinplacepriortobeginningearthworkactivities.Topsoilandorganic-richsoilwasencounteredgenerallywithintheuppersixtoeightinchesatthetestpitlocations.Topsoilandorganic-richsoilisnotsuitablefordirectfoundationsupport,norisitsuitableforuseasstructuralfill.Topsoilororganic-richsoilcanbeusedinnon-structuralareasifdesired.ArepresentativeofESNWshouldobservetheinitialstrippingoperations,toproviderecommendationsforstrippingdepthsbasedonthesoilconditionsexposedduringstripping.Subgradeconditionsexpectedtobeexposedthroughouttheproposedbuildingandpavementareaswilllikelybecomprisedofpoorlygradedsandwithsiltandgravelglacialdeposits.AfterthecompletionofsitestrippingthesubgradeconditionsshouldbeevaluatedbyarepresentativeofESNW.Aproofrollutilizingafullyloadedsolodumptruckmaybenecessarytoevaluatethesuitabilityoftheexposednativesoilspriortoplacementoffill.ESNWshouldberetainedduringthisphaseofearthworktoobservethesubgradeconditionsandotherearthwork•activities.Thesoilsexposedthroughoutsubgradeareasshouldbecompactedtostructuralfillspecificationspriortoconstructingthefoundation,slab,andpavementelements.Thesubgradethroughoutpavementareasshouldbecompactedasnecessaryandexhibitafirmandunyieldingconditionwhensubjectedtotheproofrollingwithaloadedsolodumptruck.EarthsolutionsNW,LLC JayMarcHomesES-3377June5,2014Page5Overexcavationandreplacementwithcrushedrockmaybenecessary,dependingontheconditionsencounteredduringconstruction.Structuralfillsoilsplacedthroughoutfoundation,slab,andpavementareasshouldbeplacedoverafirmbase.Looseorotherwiseunsuitableareasofnativesoilexposedatsubgradeelevationsshouldbecompactedtostructuralfillrequirementsoroverexcavatedandreplacedwithasuitablestructuralfillmaterial.Wherestructuralfillsoilsareusedtoconstructfoundationsubgradeareasthesoilshouldbecompactedtotherequirementsofstructuralfilldescribedinthefollowingsection.Foundationsubgradeareasshouldbeprotectedfromdisturbance,constructiontraffic,andexcessivemoisture.Whereinstabilitydevelopsbelowstructuralfillareas,useofawovengeotextilebelowthestructuralfillareasmayberequired.ArepresentativeofESNWshouldobservestructuralfillplacementinfoundation,slab,andpavementareas.WetSeasonGradingThemoderatemoisturesensitivityoftheon-sitesoilwillmakegradingduringperiodsofrainsomewhatdifficult.Massgradingshouldtakeplaceduringthelatesummermonthswhenconditionsaremorefavorable.Ifgradingtakesplaceduringthewetterwinter,springorearlysummermonths,acontingencyintheprojectbudgetshouldbeincludedtoallowforexportofnativesoilandimportofstructuralfillasdescribedbelow.In-situSoilsThesoilsencounteredthroughoutthemajorityofthetestsiteshaveamoderatesensitivitytomoistureandweregenerallyinamoistconditionatthetimeoftheexploration(May2014).Inthisrespect,thein-situsoilsmaynotbesuitableforuseasstructuralfillifthesoilmoisturecontentismorethan4to5percentabovetheoptimumlevelatthetimeofconstructioninthecaseofthesiltysandandpoorlygradedsandwithsiltsoilencounteredatanumberofthetestpitlocations.Ingeneral,soilsencounteredduringthesiteexcavationsthatareexcessivelyovertheoptimummoisturecontentwillrequiremoistureconditioningpriortoplacementandcompaction.Conversely,soilsthatarebelowtheoptimummoisturecontentwillrequiremoistureconditioningthroughtheadditionofwaterpriortouseasstructuralfill.Ifthein-situsoilsaredeterminedtonotbesuitableforuseasstructuralfill,thenuseofasuitableimportedsoilmaybenecessary.Inouropinion,acontingencyshouldbeincludedintheprojectbudgetforexportingunsuitablesoilandimportingstructuralfill;ormoistureconditioningrecommendationscanbeprovideduponrequestbasedonfieldobservationsduringtheconstructionphaseofon-sitework.ImportedSoilsImportedsoilintendedforuseasstructuralfillshouldconsistofawellgradedgranularsoilwithamoisturecontentthatisatorneartheoptimumlevel.Duringwetweatherconditions,importedsoilintendedforuseasstructuralfillshouldconsistofawellgradedgranularsoilwith•afinescontentof5percentorlessdefinedasthepercentpassingthe#200sieve,basedontheminusthree-quarterinchfraction.EarthSolutionsNW,LLC JayMarcHomesES-3377June5,2014Page6StructuralFillStructuralfillisdefinedascompactedsoilplacedinfoundation,slab-on-grade,androadwayareas.Fillsplacedtoconstructpermanentslopesandthroughoutretainingwallandutilitytrenchbackfillareasarealsoconsideredstructuralfill.Soilsplacedinstructuralareasshouldbeplacedinlooseliftsof12inchesorless,atmoisturecontentsabovetheoptimumlevelandcompactedtoarelativecompactionof90percent1basedonthelaboratorymaximumdrydensityasdeterminedbytheModifiedProctorMethod(ASTMD-1557).Soilplacedinutilitytrenches,pavementareasandintheupper12inchesofslab-on-gradeareasshouldbecompactedtoarelativecompactionofatleast95percent.Additionally,morestringentcompactionspecificationsmayberequiredforutilitytrenchbackfillzones,dependingontheresponsibleutilitydistrictorjurisdiction.FoundationsBasedontheresultsofourstudy,theproposedresidentialbuildingscanbesupportedonconventionalspreadandcontinuousfootingsbearingoncompetentnativesoilsencounteredbetweentwoandfourfeetbelowexistinggrades,competentexistingfillornewstructuralfill.Loosesoilexposedatfoundationsubgradeelevationscanbecompactedin-place.•Providedfoundationsarebesupportedasdescribedabove,thefollowingparameterscanbeusedfordesignofnewfoundations:•Allowablesoilbearingcapacity2,500psf•Passiveearthpressure300pcI(equivalentfluid)•Coefficientoffriction0.40Aone-thirdincreaseintheallowablesoilbearingcapacitycanbeassumedforshod-termwindandseismicloadingconditions.Theabovepassivepressureandfrictionvaluesincludeafactor-of-safetyof1.5.Withstructuralloadingasexpected,totalsettlementintherangeofoneandonehalfinchanddifferentialsettlementofaboutoneinchisanticipated.Themajorityofthesettlementsshouldoccurduringconstruction,asdeadloadsareapplied.SeismicDesignConsiderationsThe2012IBCrecognizedtheAmericanSocietyofCivilEngineers(ASCE)forseismicsiteclassdefinitions.InaccordancewithTable20.1-1oftheASCEMinimumDesignLoadsforBuildingsandOtherStructuresmanual,SiteClassDshouldbeusedfordesign.Liquefactionisaphenomenonwheresaturatedorloosesoilssuddenlyloseinternalstrengthin•responsetoincreasedporewaterpressuresresultingfromanearthquakeorotherintensegroundshaking.ThereferencedliquefactionsusceptibilitymapofKingCountyindicatesthesiteandsurroundingareasexhibitaverylowtolowliquefactionsusceptibility.EarthSolutionsNW,LLc JayMarcHomesES-3377June5,2014Page7inouropinion,sitesusceptibilitytoliquefactioncanbecharacterizedaslow.Theabsenceofauniformlyestablishedshallowgroundwatertableistheprimarybasisforthischaracterization.Slab-On-GradeFloorsSlab-on-gradefloorsforresidentialbuildingsconstructedatthissiteshouldbesupportedonafirmandunyieldingsubgrade.Wherefeasible,theexistingnativesoilsexposedattheslab-on-gradesubgradelevelcanbecompactedinplacetothespecificationsofstructuralfill.Unstableoryieldingareasofthesubgradeshouldberecompactedoroverexcavatedandreplacedwithsuitablestructuralfillpriortoconstructionoftheslab.Acapillarybreakconsistingofaminimumoffourinchesoffreedrainingcrushedrockorgravelshouldbeplacedbelowtheslab.Thefreedrainingmaterialshouldhaveafinescontentof5percentorless(percentpassingthe#200sieve,basedontheminusthree-quarterinchfraction).Inareaswhereslabmoistureisundesirable,installationofavaporbarrierbelowtheslabshouldbeconsidered.Ifavaporbarrieristobeutilizeditshouldbeamaterialspecificallydesignedforuseasavaporbarrierandshouldbeinstalledinaccordancewiththemanufacturer’sspecifications.RetainingWallsRetainingwallsmustbedesignedtoresistearthpressuresandapplicablesurchargeloads.Thefollowingparameterscanbeusedforretainingwalldesign:•Activeearthpressure(yieldingcondition)35pcf(equivalentfluid)•At-restearthpressure(restrainedcondition)55pcf•Trafficsurchargeforpassengervehicles70psf(rectangulardistribution)(whereapplicable)•Passiveearthpressure300pcf(equivalentfluid)•Coefficientoffriction0.40•Seismicsurcharge(activecondition)6H*•Seismicsurcharge(restrainedcondition)14H**whereHequalsretainedheightAdditionalsurchargeloadingfromadjacentfoundations,slopedbackfill,orotherloadsshouldbeincludedintheretainingwalldesign.Drainageshouldbeprovidedbehindretainingwallssuchthathydrostaticpressuresdonotdevelop.Ifdrainageisnotprovided,hydrostaticpressuresshouldbeincludedinthewalldesign.EarthSolutionsNW,Lic JayMarcHomesES-3377June5,2014Page8Retainingwallsshouldbebackfihledwithfreedrainingmaterialthatextendsalongtheheightofthewall,andadistanceofatleast18inchesbehindthewall.Theupperonefootofthewallbackfillcanconsistofalesspermeablesoil,ifdesired.Aperforateddrainpipeshouldbeplacedalongthebaseofthewall,andconnectedtoanapproveddischargelocation.AtypicalretainingwalldrainagedetailisprovidedonPlate3.DrainageGroundwaterwasnotobservedduringthefieldwork(May2014).However,groundwatershouldbeanticipatedindeepersiteexcavationsparticularlyduringthewetterwinterandearlyspringmonths.Temporarymeasurestocontrolsurfacewaterrunoffandgroundwaterduringconstructionwouldlikelyinvolveinterceptortrenchesandsumps.ESNWshouldbeconsultedduringpreliminarygradingtoidentifyareasofseepageandtoproviderecommendationstoreducethepotentialforinstabilityrelatedtoseepageeffects.Infiltrationofstormwaterrunofffromdownspoutsandroadwaysisfeasibleonthesubjectsite,giventhesubsurfaceconditionsESNWobservedatthetestpitlocations.However,furtherinfiltrationtestingwillberequiredtoprovidetheallowableratesofinfiltrationinaccordancewithlocalandstateregulations.Inouropinion,foundationdrainsmaynotbenecessaryiffree-drainingsandisexposedinfoundationexcavations.ArepresentativeofESNWshouldobservethefoundationexcavationsduringconstructiontoevaluatetheneedforfoundationdrains.AtypicalfoundationdraindetailisprovidedasPlate4.ExcavationsandSlopesTheFederalOccupationSafetyandHealthAdministration(OSHA)andtheWashingtonIndustrialSafetyandHealthAct(WISHA)providesoilclassificationintermsoftemporaryslopeinclinations.Basedonthesoilconditionsencounteredatthehandholelocations,thesoilsencounteredwithinthemajorityofthedevelopmentenvelope,andwheregroundwaterseepageisexposed,areclassifiedasTypeCbyOSHAIWISHA.TemporaryslopesoverfourfeetinheightinTypeCsoilsmustbeslopednosteeperthan1.5H:1V(Horizontal:Vertical).Thepresenceofperchedgroundwatermaycausecavingofthetemporaryslopesduetohydrostaticpressure.ESNWshouldobservesiteexcavationstoconfirmthesoiltypeandallowableslopeinclination.Iftherecommendedtemporaryslopeinclinationcannotbeachieved,temporaryshoringmaybenecessarytosupportexcavations.Permanentslopesshouldmaintainagradientof2H:1V,orflatter,andshouldbeplantedwithvegetationtoenhancestabilityandtominimizeerosion.ArepresentativeofESNWshouldobservetemporaryandpermanentslopestoconfirmtheslopeinclinations,andtoprovideadditionalexcavationandsloperecommendations,asnecessary.EarthSolutfonsNW,LLC JayMarcHomesES-3377June5,2014Page9UtilitySupportandTrenchBackfillInouropinion,thesoilsanticipatedtobeexposedinutilityexcavationsshouldgenerallybesuitableforsupportofutilities.Organicorhighlycompressiblesoilsencounteredinthetrenchexcavationsshouldnotbeusedforsupportingutilities.Someofthenativesoilsaremoisturesensitiveandwillthereforebedifficulttouseasstructuraltrenchbackfillifthemoisturecontentofthesoilishigh.Moistureconditioningofthesoilswilllikelybenecessarypriortouseasstructuralbackfill.Utilitytrenchbackfillshouldbeplacedandcompactedtothespecificationsofstructuralfillprovidedinthisreport,ortothespecificationsoftheapplicablejurisdiction.Seepageshouldbeanticipatedwithinutilitytrenchexcavations.Cavingofthetrenchsidewallsduetohydrostaticpressureorthecohesionlessnatureofthesitesoilsshouldbeanticipatedbythecontractor.PavementsTheperformanceofsitepavementsislargelyrelatedtotheconditionoftheunderlyingsubgrade.Toprovideadequatepavementperformance,thesubgradeshouldbeinafirmandunyieldingconditionwhensubjectedtoproofrollingwithaloadeddumptruck.Structuralfillinpavementareasshouldbecompactedasrecommendedinthe“SitePreparationandEarthwork”sectionofthisreport.Itispossiblethatsoft,wet,orotherwiseunsuitablesubgradeareasmaystillexistafterbasegradingactivities.Areasofunsuitableoryieldingsubgradeconditionswillrequireremedialmeasuressuchasoverexcavation,placementofageotextileandthickercrushedrockorstructuralfillsectionspriortopavement.Forlightlyloadedpavementareassubjectedprimarilytopassengervehicles,thefollowingpreliminarypavementsectionscanbeconsidered:•Twoinchesofhot-mixasphalt(HMA)placedoverfourinchesofcrushedrockbase(CR8),or;•TwoinchesofHMAplacedoverthreeinchesofasphalttreatedbase(ATS).TheHMA,ATBandCRBmaterialsshouldconformtoWSDOTspecifications.Allsoilbasematerialshouldbecompactedtoatleast95percentofthemaximumdrydensity.Finalpavementdesignrecommendationscanbeprovidedoncefinaltrafficloadinghasbeendetermined.Ifareasofseepageareexposedinroadwayexcavations,drainsshouldbeinstalledintheseareastoallowremovalofthewater.Specificrecommendationsanddetailsforroadwaydrainagecanbeprovideduponrequest.EarthSolutionsNW,LLC JayMarcHomesES-3377June5,2014PagelO.LIMITATIONSTherecommendationsandconclusionsprovidedinthisgeotechnicalengineeringstudyareprofessionalopinionsconsistentwiththelevelofcareandskillthatistypicalofothermembersintheprofessioncurrentlypracticingundersimilarconditionsinthisarea.Awarrantyisnotexpressedorimplied.Variationsinthesoilandgroundwaterconditionsobservedatthetestlocationsmayexist,andmaynotbecomeevidentuntilconstruction.ESNWshouldreevaluatetheconclusionsinthisgeotechnicalengineeringstudyifvariationsareencountered.AdditionalServicesESNWshouldhaveanopportunitytoreviewthefinaldesignwithrespecttothegeotechnicalrecommendationsprovidedinthisreport.ESNWshouldalsoberetainedtoprovidetestingandconsultationservicesduringconstruction.EarthSolutionsNW,LLc Reference:KingCounty,WashingtonMap657ByTheThomasGuideRandMcNally32ndEditionItrrWi,U1t’F-I-%‘t’.cm?JL_-__itiSn9tE1J”14IIft%‘t—.r‘%t9t4ck5r;____ _ _ _ _ _ ___________iM.MAPLESEF1195VAEYSE98O8-tr--.—:-z.4-Zt.JL26t.tS.lbEYMtWtWVACt.hnr!raIFI!3ThNORTHnEarthSolutionsNWacVicinityMapNOTE:Thisplatemaycontanareasofcolor.ESNWcannotberesponsrbleforanysubsequentmisinterpretationoftheinformationresultingfromblack&whitereproductionsofthisplate.AlpineGardensKingCounty,WashingtonDrwn.GLSDate05/21/2014Proj.No.3377CheckedSSRDateMay2014Plate1 —--IS.L141111S1RIHJjflUiI-J‘7‘0---hLEGEND—I—ApproximateLocationofIESNWTestPit,Proj.No.ES-3377,May2014Ii13Iil17‘IHTP-6II/INORTHFOczzz=D,456II—-—-22I—————-fl2324075150300ZEJScaleinFeetScale1”=150’IP2621‘ITP420v—HIfTP1I—ISubjectSite27ProposedLotNumberExistingBuildingEarthSolutionsNWacNOTE:Thegraphicsshownonthisplatearenotintendedfordesignpurposesorprecisescalemeasurements,butonlytoillustratetheapproximatetestlocationsrelativetotheapproximatelocationsofexistingand/orproposedsitefeatures.TheinformationillustratedislargelybasedondataprovidedbythedientatIhetimeofourstudy.ESNWcannotberesponsibleforsubsequentdesignchangesorinterpretationofthedatabyothers.NOTE:Thisplatemaycontainareasofcolor.ESNWcannotberesponsibleforanysubsequentmisinterpretationoftheinformationresultingfromblack&whitereproductionsofthisplate.SolutionsNWttcw,c.%hnicalEngineering,ConstructionMonitoringHandEnyironmentalSciencesTestPitLocationPlanAlpineGardensKingCounty,WashingtonDrwn.GLSDate05/21/2014Proj.No.3377CheckedSSRDateMay2014Plate2 418”Mm.00000000000000a000000°°°:d00000:00’b00:0000o°Q00000000000/0000cc000Ooo7o0000000/‘o:d’°°°00000oo0Q::000,oQStructural0°00oono°0p00o3cFilla095°c°°coo°pon0°:°0Q°°0000°p0/,i:00//0°°00000000000,:°0°Oo00Qeo7/_I08oOOo%Oo°eQ00:flPerforatedDrainPipeNOTES:(SurroundInDrainRock)•FreeDrainingBackfillshouldconsistofsoilhavinglessthan5percentfines.Percentpassing#4shouldbe25to75percent.•SheetDrainmaybefeasibleinlieuSCHEMATICONLY-NOTTOSCALEofFreeDrainingBackfill,perESNWNOTACONSTRUCTIONDRAWINGrecommendations.•DrainPipeshouldconsistofperforated,rigidPVCPipesurroundedwith1”DrainRock.LEGEND:____________________00000FreeDrainingStructuralBackfillop0k111inchDrainRockrEarthSolutionsNWacRETAININGWALLDRAINAGEDETAILAlpineGardensKingCounty,WashingtonDiwn.GLSDate05/27/2014Proj.No.3377CheckedSSRDateMay2014Plate3 •DoNOTtieroofdownspoutstoFootingDrain.•SurfaceSealtoconsistof12”oflesspermeable,suitablesoil.Slopeawayfrombuilding.LEGEND:Slope:18!’:(Miri4:SCHEMATICONLY-NOTTOSCALENOTACONSTRUCTIONDRAWINGSurfaceSeal;nativesoilorotherlowpermeabilitymaterial.1”DrainRockEarthISolutionsiNWrEanhSolutionsNWacotahnicalEngineering,ConstnjctionMonitoringandEnvironmentalSciencesFOOTINGDRAINDETAILAlpineGardensKingCounty,WashingtonDrwn.GLSDate05/27/2014Proj.No.3377CheckedSSRDateMay2014Plate4+2”(Mm.)NOTES:(SurroundDrainPipe1”Rock) AppendixASubsurfaceExplorationES-3377Thesubsurfaceconditionsatthesitewereexploredbyexcavatingatotalofseventestpitsexcavatedacrossaccessibleportionsoftheproperty.ThesubsurfaceexplorationswerecompletedinMayof2014.TheapproximatetestpitlocationsareillustratedonPlate2ofthisreport.LogsofthetestpitsareprovidedinthisAppendix.Thetestpitswereexcavatedtoamaximumdepthof11feetbelowexistinggrades.EarthSolutionsNW,LIC EarthSolutionsNWLLCSOILCLASSIFICATIONCHARTSYMBOLSTYPICALMAJORDIVISIONSGRAPHLEUERDESCRIPTIONS—S•SWELL-GRADEDGRAVELS,GRAVEL-CLEANOWSANDMIXTURES.LITTLEORNDGRAVELGRAVELSAND••FINESGRAVELLYPOORLY-GRADEDGRAVELS.SOILSQQS(OPGRAVEL-SANDMIXTURES,LITTLE(LITTLEORNOFINES)bo000’0CORNOFINESCOARSE‘D4Ct,GRAINEDGRAVELSWITH34jY<SILTYGRAVELS,GRAVEL-SAND-SILTMIXTURESOFCOARSESOILSMOREThAN50%FINESGMFRACTIONRETAINEDONNO.CLAYEYGRAVELS,GRAVEL-SAND-4SIEVE(APPRECIABLECLAYMIXTURESAMOUNTOFFINES)GCWELL-GRADEDSANDS.GRAVELLYMOREThAN50%SANDCLEANSANDS•X’.’,v:’SWSANDS,LITTLEORNOFINESOFMATERIALISANDNO.200SIEVESOILSLARGERTHANSANDYPOORLY-GRADEDSANDS.GRAVELLYSAND,LITREORNOSIZE(UTTLEORNOFINES)FINESSANDSWITHSMSILTYSANDS,SAND-SILTMIXTURESMORETHAN50%FINESOFCOARSEFRACTIONPASSINGONNO.CLAYEYSANDS,SAND-CLAY4SIE(APPRECIABLECLAYFINESANDSORCLAYEYMIXTURESAMOUNTOFFINES)INORGANICSILTSANDVERYFINEMLSANDS,ROCKFLOUR,SILTYORSILTSWITHSLIGHTPLASTICITYINORGANICCLAYSOFLOWTOSILTSMEDIUMPLASTiCITY,GRAVELLYFINEANDUQUIDLIMITCLAYS.SANDYCLAYS,SILTY/%ciGRAINEDCLAYSLESSTHAN50CLAYS,LEANCLAYSSOILS————OLORGANICSILTSANDORGANICSILTYCLAYSOFLOWPLASTICITYMORETHAN50%INORGANICSILTS,MICACEOUSOROFMATERIALISSMALLERTHANSILTYSOILSGREATERTHAN50MRDIPJOMACEOUSFINESANDORNO.200SIEVESIZESILTSANDUQUIDUMITCRINORGANICCLAYSOFHIGHPLASTICITYCLAYS—OHORGANICCLAYSOFMEDIUMTOHIGHPLASTICITY.ORGANICSILTSa.--.nt,‘%“G”’,HIGHLYORGANICSOILS———PTPEAT,HUMUS,SWAMPSOILSWITHHIGHORGANICCONTENTSDUALSYMBOLSareusedtoindicateborderlinesoilClasSifications.ThediscussioninthetextofthisreportisnecessaryforaproperunderstandingofthenatureofthematerialpresentedintheattaChedlogs. EarthSolutionsNW1805-136thPlaceN.E.,Suite201Bellevue,Washington98005Telephone:425-4494704Fax:4254494711CLIENTJayMarcHomes—______________________________PROJECTNUMBER3377________DATESTARTED5/13114COMPLETED5/13/14EXCAVATIONCONTRACTORNWExcavating-—-EXCAVATIONMETHOD__________LOGGEDBYSI-IA_______CHECKEDBYSHA______NOTESDepthofTopsoil&Sod8”:baresoil-—_____PROJECTNAMEAlpineGardensPROJECTLOCATIONjgCounty,WashingtonGROUNDELEVATION________-GROUNDWATERLEVELS:ATTiMEOFEXCAVATION—ATENDOFEXCAVATION—AFTEREXCAVATION—Earth‘SolufiondNi’iitTESTPITNUMBERTP-1PAGE1OF1TESTPITSIZEUi0°MATERIALDESCRIPTIONoETESTSz0<0,IPSISMSPMC=12.00%MC=3.80%Fines=10.70%MC=3.50%5I,I’,,xTOPSOIL1.0___ __ ___ __ __ __ __ ___ __ __ __ ___ __BrownsiltySANDwithgravel,loose,moist-Ironoxidestaining3M________________________________________________BrownpoorlygradedSANDwithgravel,dense,moist8 . 0 ____ __ _ __ _ __ _ __ _ __ _ __ ___ ___ ___ __ __ ___ __ __ __ __ ___ __ __ __ ___ __ __ __ __ _Testputerminatedat8.0feetbelowexistinggrade.Nagroundwaterencounteredduringexcavation.Bottomoftestpitat8.0feet. EarthSolutionsNW1805-136thPlaceN.E.,Suite201Bellevue,Washington98005Telephone:425-4494704Fax:425449471111.0__ __ _ ___ ___ _ _ _ ____ _ ____ __ ___ __ __ __ __ ___ __ __ __ ___ __ __ __ __ ___ __ __ __ ___ __ __ __ __ __Testpitterminatedat11.0feetbelowexistinggrade.Nogroundwaterencounteredduringexcavation.SolutionNWutTESTPITNUMBERTP-2PAGE1OFICLIENTyMarcHomes_ ____ _ ____ _ ____ _ __-.PROJECTNAMEjpineGardens-___ ____ _ ____ _ _!ROJECTNUMBER3377___ _ __PROJECTLOCATIONKingCounty,Washington_________________DATESTARTED5/13114—COMPLETED5/13/14GROUNDELEVATIONTESTPITSIZE___ __ ___ _EXCAVATIONCONTRACTORNWExcavating—GROUNDWATERLEVELS:EXCAVATIONMETHOD--___ __ ___ __ __ __ __——ATTIMEOFEXCAVATION—-____ ___ ___ __ _LOGGEDBYSHACHECKEDBYSHAATENDOFEXCAVATION—__ __ __ __ -- __ __ __ ___ __NOTESDepthofTopsoil&Sod6”:baresoil-AFTEREXCAVATION—_ _ _ _ _ _ _ ____________ _ _ _ _ _ _ _ _In0.>-F-uiTESTS0<00MATERIALDESCRIPTIONBrownsiltySANDwithgravel,loose,moist-ironoxidestainingMC=5.80%MC=22,40%Fines=41.50%BrownpoorlygradedSANDwithgravel,dense,moist-slightcaving510BrownIgraysiltySANDwithgravel,dense,moistMC=3.00%Bottomoftestpitat11.0feet. EarthSolutionsNW1805-136thPlaceN.E.,Suite201Bellevue,Washington98005Telephone:425-449-4704Fax:4254494711w0r€TESTSMATERIALDESCRIPTIONozS4:U,-Q____5.0__ __ __ ___ __ __ __ ___ __ __ __ __ ___ __ __ __ ___ __ __ ____ _ __ __ _ __ __ _ __ __ _ __ __ _ __ __ _ __ __ _ _Testpitterminatedat5.0feetbelowexistinggrade.Nogroundwaterencounteredduringexcavation.Earth‘SolutionNWucCLIENTJayMarcHomes___ ____ ___— .__ ____ ___ ___ _PROJECTNUMBER3377__ _ __ ___ ___ ___ ___ __ _ __ _ _DATESTARTED5/13/14-COMPLETED14_____EXCAVATIONCONTRACTORNWExcavating______—-EXCAVATIONMETHOD___ __LOGGEDBYSI-IA—CHECKEDBYSHA___ _ __NOTESçpthofTopsoil&Sod6’jrass—___ _ __ __TESTPITNUMBERTP-3PAGE1OF1PROJECTNAMEjpineGardensPROJECTLOCATIONKingCounty.WashingtonGROUNDELEVATIONTESTPITSIZEGROUNDWATERLEVELS:ATTIMEOFEXCAVATION—ATENDOFEXCAVATION-—AFTEREXCAVATION.. - _ ___ ___ _ __ _ _MC=3.70%5TPSL0.5TOPSOILBrownpoorlygradedSANDwithsiltandgravel,dense,moistSr.SM-becomesfinegrainedBottomoftestpitat5.0feet. Earth‘SolutionNWittEarthSolutionsNW1805-136thPlaceN.E.,Suite201Bellevue,Washington98005Telephone:425-449-4704Fax:425-4494711TESTPITNUMBERTP4PAGE1OF1CLIENTyMarcHomes__ __ __ _ __ __ _ __ __ _ __ __ _ _PROJECTNUMBER3377_____ _ _ _ ______ _ _ _ _ _DATESTARTED-5/13/14—COMPLETED5/13/14—EXCAVA11ONCONTRACTORNWExcavatingEXCAV A1 1 ON METhO D -—_____ _ _ _____ _ _ ____LOGGEDBYSHACHECKEDBYSHANOTESDepthofTopsoil&Sod8’:fieldgrassLU0>-I-LUTESTSa<Go0I0Boftomoftestpitat10.0feet.PROJECTNAMEAlpineGardensPROJECTLOCATIONKingCounty,WashinflGROUNDELEVA11ON-_____ _TESTPITSIZEGROUNDWATERLEVELS:AT11MEOFEXCAVATiON—ATENDOFEXCAVATION—AFTEREXCAVATiON—MATERIALDESCRIPTIONBrownsiltySANDwithgravel,mediumdense,moist(Fill-AsphaltDebris)-endfill-nativecontactMC=1440%MC=7.10%5.0510BrownpoorlygradedSANDwithsiltandgravel,dense,moistMC=3.70%-decreasingfines,becomesmorecoarsegrained10.0Testpitterminatedat10.0feelbelowexistinggrade.Nogroundwaterencounteredduringexcavation. EarthSolutionsNW1805-136thPlaceN.E.,Suite201Bellevue,Washington98005Telephone:425-449-4704Fax:4254494711CLIE NT Ja y Ma rc Homes ____ ___ _ __ _ ____ __ __ __ __PROJECTNUMBER3377- -—_________DATESTARTED5/13114COMPLETED5/13114EXCAVATIONCONTRACTORNWExcavating__ ___ ___ _ __ - - -EXCAVATIONMETHOD____________ _ _ __LOGGEDBYSHA——CHECKEDBYSHANOTESDepthofTopsoil&Sod6”:grass- - - -____ _ _ _w0->-xF-uiTESTSC<Co0tinpoorlygradedSANDwithsiftandgravel,mediumdense,moistEarth‘SolutionN%ViscTESTPITNUMBERTP-5PAGE1OF1PROJECTNAMEAlpineGardens-___________ _ _ _PROJECTLOCATIONJçjflflCounty,Washington—_ _ ___ _ _ ___ _ _ ___GROUNDELEVATiON——TESTPITSIZEGROUNDWATERLEVELS:ATrIMEOFEXCAVATION—ATENDOFEXCAVATION——AFTEREXCAVATION—MATERIALDESCRIPTIONMC=2.40%5MC=2.70%BrownpoorlygradedSANDwithgravel,mediumdense,moist-becomesdense,slightcaving-lightironoxidestaining,becomesmorecoarsegrainedTestpitterminatedat8.0feetbelowexistinggrade.Nogroundwaterencounteredduringexcavation.Bottomoftestpitat8.0feet. CLIENTJayMarcHomesPROJECTNUMBER3377EarthSolutionsNW1805-136thPlaceN.E.,Suite201Bellevue,Washington98005Telephone:425-4494704Fax:4254494711DATESTARTED5/13114COMPLETED5/13/14_---—EXCAVATIONCONTRACTORNWExcavating__ __ _ __ ___ ___ _EXCAVATIONMETHOD___ ___ _LOGGEDBYSHACHECKEDBYSI-IA-NOTESDepthofTopsoil&Sod6”:grass—___ __ __ __ _wL,-XF-UigTESTS0<U,05MC=2.60%BrownpoorlygradedSANDwithsiltandgraveldense,moist-—TestpittermTnatedat5.0feetbelowexistinggrade.Nogroundwaterencounteredduringexcavation.EarthSolutionNIi’LLLTESTPITNUMBERTP-6PAGE1OF1PROJECTNAMEAlpineGardens-—PROJECTLOCATIONfgCounty,WashingtonGROUNDELEVATION_____ _ _—TESTPITSIZEGROUNDWATERLEVELS:ATTIMEOFEXCAVATION—ATENDOFEXCAVATION—AFTEREXCAVATION-—MATERIALDESCRIPTION-coarsegrained-heavycaving5.0Bottomoftestpitat5.0feet. Earth‘SolutionEarthSolutionsNW1805-136thPlaceN.E.,Suite2OlTESTPITNUMBERTP-7Bellevue,Washington98005PAGE1OF1Telephone:4254494704Fax:425449-4711CLIENT4yMarcHomesPROJECTNAMEAlpineGardens—-PROJECTNUMBER3377PROJECTLOCATIONKingCounty,WaJntonDATESTARTED5/13/14COMPLETED5/13/14GROUNDELEVATIONTESTPITSIZEEXCAVATIONCONTRACTORNWExcavatingGROUNDWATERLEVELS:EXCAVATIONMETHOD---- -ATTIMEOFEXCAVATION—-____LOGGEDBYSI-IACHECKEDBYSI-IAATENDOFEXCAVA11ON—NOTESflpthofTopsoil&Sod6H:grass—AFTEREXCAVATIONUi:a‘Or€TESTSMATERIALDESCRIPTION00FPSLTOPSOILBrownpoorlygradedSANDwithsiltandgravel,mediumdensetodense,mo’stSP.o-becomesmorefinegrained,decreasingsiltiv-t:—BrownpoorlygradedGRAVELwithsiltandsand,dense,moist.o,GPoo,‘5.0.. -5MC=4.50%SPLaBrownpoorlygradedSANDwithsiltandgravel,dense,moistTestpitterminatedat8.0feetbelowexistinggrade.Nogroundwaterencounteredduringexcavation.Bottomoftestpitat8.0feet. AppendixBLaboratoryTestResultsES-3377EarthSolutionsNW,LIC HI0GRAINSIZEINMILLIMETERSCOBBLESGRAVELSANDcoarsemediumfine—ISILTORCLAYI0CCC-Cl,Cl,zSpecimenIdentiflcatian-CIassiflcatonLLPLP1CcCu2TP-13.Oft.USGS:BrownPoorlyGradedSANDwithGravel,SP0.865.28TP-26.Dft.USDA:TanGravellyLoam.USGS:SM.SpecimenIdentificationDiOCD60D30—D1O%Gravel%Sand%Silt%CIay2TP-i3.Oft.192.7461.110.5215.084.30.7TP-26.Oft.190.80310.248.341.5-EaiIhSok’Ihns%I4LttEarthSolullonsNWGRAINSIZEDISTRIBUTION1805-136thPlaceNE,Suite201Bellevue,WA98005Telephone:425-2843300CLIENTJayMarcHomesPROJECTNAMEAlpineGardensPrellninaryPlatPROJECTNUMBERES-33flPROJECTLoCKflONKthqCountyU.S.SIEVEOPENINGININCHESIU.S.SIEVENUMBERSIH\VROAETER64321.51411231634661014162030405060100140:coarsefIneC ReportDistributionES-3377EMAILONLYJayMarcHomes7525Southeast24thStreet,Suite487MercerIsland,Washington98040Attention:Mr.JayMezistranoEarthSolutionsNW,LLC March3,2015ES-3377.02Mr.RoyBoyer14609—161StAvenueSouthwestRenton,Washington98059Subject:AlpineNursery—BoyerPropertiesStormwaterManagementConsultation16023Southeast144thStreetRenton,WashingtonDearMr.Boyer:EarthSolutionsNWLLCEarthSolutionsNWLLC•GeotechnicalEngineering•ConstructionMonitoring•EnvironmentalSciencesAsrequested,EarthSolutionsNW,LLC(ESNW)haspreparedthislettersummarizingouropinionregardingthepotentialimpactofstormwaterinfiltrationonneighboringproperties.Stormwaterrunoffonthesubjectsitewillbecollectedandconveyedtotheproposedinfiltrationfacilityinthesouthernportionofthesubjectsite.Aconcernoverthepotentialforgroundwatercontaminationhasbeenlodgedbythepropertyownertothewestoftheprojectarea(parcelnumber2323059138).Thisneighboringpropertyobtainsdrinkingwaterfromawell.Wehavebeenaskedtoprovideanopinionregardingthepossibilityforcontaminationofthegroundwaterthroughtheproposedstormwaterinfiltration.ThesubjectsiteislocatedonthesouthsideofSoutheast144thStreet;andeastof160thAvenueSoutheastinRenton,Washington.Thesiteisoccupiedbytworesidentialstructuresandaplantnursery.Thesubjectsiteislocatedinanareainwhichglacialoutwash(geologicmapdesignation,Qgo)soilhasbeenidentifiedonthegeologicmapswhichESNWusedasareferencepriortothesiteexploration.ArepresentativeofESNWpreviouslyobservedtheexcavationofeighttestpitsusinghandtools,aswellasanexcavatorandoperator,contractedbyESNW,throughoutthestormwaterpondfootprintinsouthernportionofthesubjectsite.ESNWobservedpoorlygradedgravel(UnifiedSoilClassification,GP),andwellgradedgravel(GW)inadenseconditionatallthreetestlocationsatthebottom-of-pondelevation.Theexcavationswereterminatedinthewellgradedsandandgravelsoilsatmaximumof15feetbelowexistinggrade,whichequatestoa•minimumofsixfeetbelowbottom-of-pondelevation.ThesoilconditionswhichESNWobservedwereconsistentwiththegeologicmapdesignationofglacialoutwash.1805-136thPlaceN.E.,Suite201Bellevue,WA98005•(425)449-4704•FAX(425)449-4711. Mr.RoyBoyerMarch3,2015ES-3377.02Page2Nogroundwaterwasobservedatthetestpitsduringourfieldwork(December2014andJanuary2015),andnoconfiningsoillayerwasencounteredduringthesubsurfaceexploration.Itisouropiniontheinfiltrationofstormwateronthesubjectsitewillposenodeleteriouseffectstotheneighbor’swellwater,given(asdesigned)waterqualitytreatmentisapartoftheprojectplansupstreamfromtheproposedpond.Additionally,theinfiltrationpondwillprovideforwaterqualityfunctionalityasdesignedwhentakingintoconsiderationthefactthatparticulatematterwillbefilteredthroughthepercolationprocessinthesoilpresentinthesubgrade,priortothestormwaterreachingtheaquifer.Ifyouhavequestionsorrequireadditionalinformation,pleasecall.Sincerely,EARTHSOLUTIONSNW,LLCcc:D.R.StrongAttention:Mr.MaherJoudi(Emailonly)StephenH.AvrilProjectGeologistKyleR.Campbell,P.E.PrincipalEarthSolutionsNW,LLC APPENDIX“I”INFILTRATIONEVALUATION©2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage76TechnicalInformationReportCityofRenton January9,2015ES-3377.02Mr.RoyBoyer14609—161StAvenueSoutheastRenton,Washington98059Subject:AlpineNursery—BoyerPropertiesInfiltrationEvaluation16023Southeast144thStreetRenton,WashingtonDearMr.Boyer:EarthSolutionsNWLLCEarthSolutionsNWLLC•CeotechnicalEngineering•ConstructionMonitoring•EnvironmentalSciencesAsrequested,EarthSolutionsNW,LLC(ESNW)haspreparedthislettersummarizingourfindingsregardingstormwaterinfiltrationforthesubjectsite.ThesubjectsiteislocatedonthesouthsideofSoutheast144thStreet;andeastof160th•AvenueSoutheastinRenton,Washington.Thesiteisoccupiedbytworesidentialstructuresandaplantnursery.Thesubjectsiteislocatedinanareainwhichglacialoutwash(geologicmapdesignation,Qgo)soilhasbeenidentifiedonthegeologicmapswhichESNWusedasareferencepriortothesiteexploration.ArepresentativeofESNWwason-sitetoobservethesubsurfaceconditionsinDecemberof2014,andJanuaryof2015.ESNWobservedtheexcavationofeighttestpitsusinghandtools,aswellasanexcavatorandoperator,contractedbyESNW,throughoutthestormwaterpondfootprintinsouthernportionofthesubjectsite.Thetestpitswereadvancedtoapproximately13feetdeepintothenativesoil.ESNWobservedpoorlygradedgravel(UnifiedSoilClassification,GP),andwellgradedgravel(OW)inadenseconditionatallthreetestlocationsatthebottom-of-pondelevation.Thewellgradedgravelcontainedafinescontentofabout2.6percentand2.3percent;andaUSDAdescriptionofExtremelyGravellyCoarseSand.Pleaseseethesoillogslaterinthisreportforadetaileddescriptionofthesubsurfaceconditions.EPAfallingheadinfiltrationtestingwasperformedwithinthewellgradedsandandgravelsoilsinthreeofthetestpits.Theexcavationswereterminatedinthewellgradedsandandgravelsoilsatmaximumof15feetbelowexistinggrade,whichequatestoaminimumofsixfeetbelowbottom-of-pondelevation.ThesoilconditionswhichESNWobservedwereconsistentwiththegeologicmapdesignationofglacialoutwash.Nogroundwaterwasobservedatthetestpitsduringourfieldwork(December2014andJanuary2015).Noconfiningsoillayerwasencounteredtoanelevationsixfeetbelowthepondbottom.1005-136thPlaceN.E.,Suite201Bellevue,WA98005•(425)449-4704•FAX(425)449-4711. ES-3377.02Page2Theinfiltrationtestingwasperformedingeneralaccordancewiththe2005DOEStormwaterManagementManualforWesternWashington(DOE),Section3.6.ESNWrepresentativesconductedasitevisitonDecember24,2014toexcavatetestpitsusingatrackhoeandoperatorretainedbyESNW,atlocationswithinthepotentialinfiltrationareas.EPAfalling-headinfiltrationtestingwasconductedduringoursitevisit.MeasuredInfiltrationRatesTestingwascompletedwithinthewellgradedgravelsoilsinordertodemonstratetheinfiltrationratesatthebottom-of-pondsoiltypes.Themeasuredinfiltrationrateswere70in/hourwithintheundisturbednativesoils.Ifyouhavequestionsorrequireadditionalinformation,pleasecall.Sincerely,EARTHSOLUTIONSNW,LLC•SteijenH.Avril4Stf/GeologistAttachment:TestPitLogscc:D.R.StrongAttention:Mr.MaherJoudi(Emailonly)Mr.RoyJanuaryBoyer9,2015InfiltrationTestingKyleR.Campbell,P.E.PrincipalEarthSolutionsNW,LLC TestPitLogsES-3377.02TP-1O1SoilTypeDepthLooseTopsoil0-6”MediumDenseSiltySandwithGravel6”-3’DensePoorlyGradedGravel3’-6’TP-102SoilTypeDepthLooseTopsoilMediumDenseSiltySandwithGravel6’-3’DensePoorlyGradedGravel365’TP-103SoilTypeDepthLooseTopsoil0’-6”MediumDenseSiltySandwithGravel6”-3’DenseWellGradedGravel3’-13’TP-104SoilTypeDepthLooseTopsoilMediumDenseSiltySandwithGravelDenseWellGradedGravel3’-lO’DenseWellGradedSand10’-12’TP-105SoilTypeDepthLooseTopsoilMediumDenseSiltySandwithGravel6”-3’DenseWellGradedGravel3’-6’DensePoorlyGradedSand6’-6.5’DenseWellGradedSand6.5-15’EarthSolutionsNW,LL.C APPENDIX“J”ARBORISTREPORT©2016D.R.STRONGConsultingEngineersInc.AlpineNurseryPage77TechnicalInformationReportCityafRenton GreenforestIncorporatedConsultingArboristJanuary5,2015MaherioudiD.R.STRONGConsultingEngineers,Inc.6207thAvenueKirkland,WA98033RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059DearMr.Joudi:Youcontactedmeandcontractedmyservicesasaconsultingarborist.Myassignmentistoinspectandevaluatetheconditionofsurveyedtreesattheabovereferencedsite.Ireceivedatreesurveyfromyoushowingthelocationandnumbersofthesignificanttrees.Ivisitedthesitelastweekandinspectedthetreesindicatedonthesheet,whicharethesubjectofthisreport.TREEINSPECTIONMyinspectionislimitedtovisualobservationfromthesubjectparcels.Sometrees,bothoffsite,andwithinexistingandproposedrights-of-way,arealsoincludedinthisreport.Iidentifiedthespeciesandconfirmedtrunkdiameter(DBH)forthesurveyedtrees.Ialsoidentifiedindividualtreesthataredead,dying,defectiveordangerous.Youidentifiedspecifictreestobesavedandretained.Forthesetrees,Ifurtherevaluatedhealthandstructure,recordedvisibledefectsandcalculatedlimitsofdisturbance.Theresultsofthisinspectionarebasedonwhatisvisibleatthetimeoftheinspection.4547SouthLucileStreet,Seattle,WA98118Tel.206-723-0656 Maherioudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page2of24Theattachedinventoryprovidesthefollowinginformationforeachtree:Treenumberasshownontheattachedplan.TreeSpeciesCommonname.DBHStemdiameterininchesmeasured4.5feetfromtheground.DangerousTreeCertificationTreesthatarecertifiedasdead,terminallydiseased,damaged,orotherwisedangerous.’(Treeswithobviousterminaldiseasesareidentifiedinthiscolumnasdefinedby§4-11-200.Othertrees,eventhoughdiseased,arelistedasretainedtreesbecausetheirdiseaseisnotterminal,andthediseasecanbemanagedifthetreeisretained.)VisibleDefectsObviousstructuraldefectsordiseasesvisibleattimeofinspection,whichincludes:Asymmetriccanopy—thetreehasanasymmetriccanopyfromspaceandlightcompetitionfromadjacenttrees.Bowintrunk—trunkwithbowordefectivebendintrunk.Brownrotfungus—commonfoliarandstemdiseaseoncherryspecies.Dead—treeisdead.Decline/Dying—treeisinanobviousstateofdeclinefromwhichitwillunlikelyrecover.Deformed—poor/weakbranchstructure.Diseased—foliageandtrunk/stemsarediseased.Doubleleader—thetreehasmultiplestemattachments,whichmayrequiremaintenanceormonitoringovertime.Hatchetgirdled—treeisgirdledatbasefromahatchetoraxe.Slender—treelacksadequatetrunktapertostandlone.Suppressed—treecrowdedbylargeradjacenttrees;withdefectivestructureand/orlowvigor.Retaintreeonlyasagrovetree,notstand-alone.Sweep—treeleansawayfromadjacenttrees.Topped—thetreeispreviouslytoppedandhaspoorstructureand/orstemdecay.Wound/decaybaseoftrunk-Openwoundwithvisibledecayintrunk.RentonMunicipalCode.§4-11.200DEFINITIONST:(Accessedonline1/2/15)GreenforestRegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SEi44Street,RentonWA98059January5,2015Page3of24SIGNIFICANTTREESTheattachedtreeinventoryidentifiesover600significantsurveyedtrees,598ofwhicharelocatedonsite.Fourteen(14)ofthesetreesareconsidereddangerousasdefinedbyCitycode.Onehundredtwo(102)areproposedforretention.About246treesarewithinproposedrights-of-way.RETAINEDTREES&LIMITSOFDISTURBANCEThefollowingtableidentifiesthe102treesproposedforretention.Theseareallviabletrees,however,somehaveminorvisibledefectsthatarenotedintheattachedtable.Treeswithstructuraldefectsshouldberetainedinagrove,andnotasstand-alonetrees.Someretainedtreescurrentlystandwithinanexistinggrove,andtheproposedclearingwillputthemattheedgeofaretainedgrove.Forthesenewlyexposedtrees,thenumberofexposededgesareindicated.Icalculatedlimitsofdisturbanceforthesenewedgetreesbasedontheircurrentsize,speciesandtheproposedencroachment.Theyaredeterminedusingrootplate2andtrunkdiameter,34andISABestManagementPractices.5Thesearetheminimumdistances(infeet)fromthetreesforanysoildisturbance,andrepresenttheareatobeprotectedduringconstruction.TheseLODaremalleableandmaybeadjustedduringthedesignandconstructionprocess.AnytreeremovaltobeperformedwithintheseLODshallbedonebycuttingthetreeatgrade,andleavingthestumpinplace.TableofRetainedTreesandLimitsofDisturbanceTreeNo.OfLimitsOfDBH.SpeciesNo.ExposedEdgesDisturbance(Ft.)568020”311’Douglas-fir568130Douglas-fir568420Douglas-fir568620311Douglas-fir56888Douglas-fir569214Douglas-fir56931427Douglas-fir56968Douglas-fir56981015Douglas-fir570214Douglas-fir57041618Douglas-fir2Coder,Kim0.2005.TreeBiomechanicsSeries.UniversityofGeorgiaSchoolofForestResources.Smiley,E.Thomas,Ph.0.AssessingtheFailurePotentialofTreeRoots,ShadeTreeTechnicalReport.BartlettTreeResearchLaboratories.Fite,KelbyandE.ThomasSmiley.2009.ManagingTreesDuringconstruction;PartTwo.ArboristNews.ISA.CompanionpublicationtotheANSIA300Series,PartS:ManagingTreesDuringConstruction.2008.ISA.RegisteredConsultingArboristGreenforest MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreetRentonWA98059January5,2015Page4of24TreeNo.OfLimitsOfDBH.SpeciesNo.ExposedEdgesDisturbance(Ft.)57061427Douglas-fir570818Douglas-fir571010Douglas-fir57121438Douglas-fir571422Douglas-fir57151025Douglas-fir571616Douglas-fir•571722211Douglas-fir571818Douglas-fir57201427Douglas-fir572116Douglas-fir57221618Douglas-fir572314Douglas-fir572412Douglas-fir57251216Douglas-fir57261829Douglas-fir572718Douglas-fir572820Douglas-fir573028Douglas-fir5885824Douglas-fir58931237Westernred-cedar5894824Westernred-cedar58951639Douglas-fir5896935Westernred-cedar590236320Douglas-fir590322312Douglas-fir590436320Douglas-fir590522111Douglas-fir590634218Westernred-cedar59071226Bigleafmaple590938221Westernred-cedar591030115Westernred-cedar59117Bigleafmaple59391025Westernred-cedar594020Westernred-cedar594120Westernred-cedar59421628BigleafmapleCreenforest(WIRegisteredConsultingArborist MaherJoudi,0.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015•TreeNo.OfLimitsOfDBH.SpeciesNo.ExposedEdgesDisturbance(Ft.)594420Douglas-fir5945834Pacificdogwood594624Douglas-fir594710Douglas-fir594817Douglas-fir594918Douglas-fir595016Douglas-fir595126Douglas-fir595210Douglas-fir595312Douglas-fir59548Douglas-fir595518Douglas-fir595614Douglas-fir595714Douglas-fir595816Douglas-fir595932Douglas-fir596026Douglas-fir5961714Douglas-fir596316Douglas-fir596422211Douglas-fir59651417Douglas4ir59661819Douglas-fir596724Douglas-fir596826Douglas-fir596918Douglas-fir597114Douglas-fir59721226Douglas-fir597326Westernred-cedar597424Douglas-fir605224313Douglas-fir605832217Douglas-fir605915Douglas-fir60608Douglas-fir60618Douglas-fir606220Douglas-fir606326Douglas-fir[606424[_____________ __Douglas-firGreenforestRegisteredConsultingArborist Maherioudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page6of24TreeNo.OfLimitsOfDBHSpeciesNo.ExposedEdgesDisturbance(Ft.)6065925Douglas-fir6066623Douglas-fir60671427Douglas-fir60681226Douglas-fir627138422Douglas-fir628218,28421Douglas-fir708024213Douglas-fir70811628Douglas-fir708222211Douglas-fir70831025Pacificdogwood710330316Douglas-fir710420210Douglas-fir710510,1039Pacificdogwood732020411Kwanzancherry732124414Douglas-fir841612417ItalianPrune84171236.5KwanzancherryAttachments:1.AssumptionsandLimitingConditions2.TreeInventoryRegisteredConsultingArboristSincerely,GreeiInc.ISACertifiedArborist#PN-0143AASCARegisteredConsultingArborisC#379PNW-ISACertifiedTreeRiskAssessor#579Greenforest Maherioudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page7of24AttachmentNo.1-Assumptions&LimitingConditions1)Afieldexaminationofthesitewasmade12/22/2014.Myobservationsandconclusionsareasofthatdate.2)Carehasbeentakentoobtainallinformationfromreliablesources.Alldatahasbeenverifiedinsofaraspossible;however,theconsultant/arboristcanneitherguaranteenorberesponsiblefortheaccuracyofinformationprovidedbyothers.3)Unlessstatedotherwise:1)informationcontainedinthisreportcoversonlythosetreesthatwereexaminedandreflectstheconditionofthosetreesatthetimeofinspection;and2)theinspectionislimitedtovisualexaminationofthesubjecttreesfromthesubjectproperty,withoutdissection,excavation,probing,orcoring.Thereisnowarrantyorguarantee,expressedorimpliedthatproblemsordeficienciesofthesubjecttreemaynotariseinthefuture.4)Alltreespossesstheriskoffailure.Treescanfailatanytime,withorwithoutobviousdefects,andwithorwithoutappliedstress.5)Constructionactivitiescansignificantlyaffecttheconditionofretainedtrees.Allretainedtreesshouldbeinspectedafterconstructioniscompleted,andtheninspectedregularlyaspartofroutinemaintenance.6)Theconsultant/appraisershallnotberequiredtogivetestimonyortoattendcourtbyreasonofthisreportunlesssubsequentcontractualarrangementsaremade.7)Lossoralterationofanypartofthisreportinvalidatestheentirereport.8)Unlessrequiredbylawotherwise,possessionofthisreportoracopythereofdoesnotimplyrightofpublicationoruseforanypurposebyanyotherthanthepersontowhomitisaddressed,withoutthepriorexpressedwrittenorverbalconsentoftheconsultant/appraiser.9)Thisreportandanyvalues/opinionsexpressedhereinrepresenttheopinionoftheconsultant/appraiser,andtheconsultant’s/appraiser’sfeeisinnowaycontingentuponthereportingofaspecifiedvalue,astipulatedresult,theoccurrenceofasubsequentevent,noruponanyfindingtobereported.10)Ownershipanduseofconsultant’sdocuments,workproductanddeliverablesshallpasstotheClientonlywhenALLfeeshavebeenpaid.GreenforestRegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Pagesof24AttachmentNo.2-TreeInventoryRetainTree.DangerousDBHSpecies*Visibledefects/notesTreeNo.Tree?537936”Douglas-fir538026Douglas-fir538122Douglas-fir538222Douglas-fir538326Douglas-fir538420Douglas-fir538519Douglas-fir538628Douglas-fir538718Douglas-fir5388i11Douglas-fir538915Douglas-fir539018Douglas-fir539112Douglas-fir539216Douglas-fir539330Douglas-fir53949Pacificdogwood541811Douglas-fir555212Birch555312Bigleafmaple555615Portugallaurel55578Hinokicypress55586Hinokicypress55596Hinokicypress55607Leylandcypress556124Leylandcypress556224Leylandcypress556315Leylandcypress556413Leylandcypress556515Leylandcypress556610Leylandcypress55676Leylandcypress556810Leylandcypress556910Leylandcypress557011Leylandcypress557116Leylandcypress55728Douglas-firGreenforestIt)RegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreetRentonWA98059January5,2015Page9of24RetainTreeDangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?t55738Douglas-fir55747Douglas-fir55759Douglas-fir55768Douglas-fir557713Douglas-fir557814Douglas-firX568020Douglas-firX568130Douglas-fir568216Douglas-fir568322Douglas-firX568420Douglas-fir568512Douglas-firX568620Douglas-fir568724Douglas-firX56888Douglas-fir568914Douglas-fir569016Douglas-fir569124Douglas-firX569214Douglas-firX569314Douglas-fir569422Douglas-fir56956Douglas-firYesDeadX56968Douglas-firISuppressed569738Douglas-firX569810Douglas-fir569938Douglas-fir570028Douglas-fir570132Douglas-firX570214Douglas-fir570328Douglas-firX570416Douglas-firX570614Douglas-fir570730Douglas-firX570818Douglas-fir570934Douglas-firX571010Douglas-firToppedX571214Douglas-firGreenforestRegisteredConsultingArborist Maherioudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page10of24RetainTreeDBHSpeciesDangerousVisibledefects/notesTreeNo.Tree?571322IDouglas-firX571422Douglas-firX571510Douglas-firAsymmetriccanopyX571616Douglas-firX571722Douglas-firX571818Douglas-fir571910Douglas-firX572014Douglas-firX572116DougLas-firX572216Douglas-firX572314Douglas-firWoundatbaseoftrunkX572412Douglas-firX572512Douglas-firSuppressedX572618Douglas-firX572718Douglas-firX572820Douglas-firX573028Douglas-fir573132Douglas-fir57686Bigleafmaple57696Douglas-fir57706Douglas-fir577126Douglas-fir577210Douglas-fir57736Douglas-fir577416Douglas-fir57758Bigleafmaple577612Douglas-fir577716Douglas-fir5778J28Douglas-fir577916Douglas-fir578012Douglas-fir578126IDouglas-fir578226Douglas-fir578324Douglas-fir578412Douglas-fir578532Douglas-fir57868Douglas-firGreenforestRegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page11of24RetainTreeDangerousDBHSpecies*iVisibledefects/notesTreeNo.Tree?57878Douglas-fir578828Douglas-fir578910Douglas-fir579024Douglas-fir579110Douglas-firI_____________57928Douglas4ir579318Douglas-fir579414Douglas-fir579530Douglas-fir579618Douglas-fir57979Douglas-firYesDead579820Douglas-fir579910Douglas-fir580024Douglas-fir580126Douglas-fir580222Douglas-fir580310Douglas-fir580418Douglas-fir580536Douglas-fir580624Douglas-fir580720Douglas-fir58089Douglas-fir58096Douglas-fir581028Douglas-fir581114Douglas-fir581230Douglas-fir581322Douglas-fir581428Douglas-fir581518Douglas-fir58166Douglas-fir581720Douglas-fir58187Douglas-fir58198Douglas-fir58209Douglas-fir582110Douglas-fir582222Douglas-fir582330Douglas-firGreenforestRegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SEl44Street,RentonWA98059January5,2015Page12of24RetainTreeDangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?*58246Douglas-firYesHatchetgirdled582510Douglas-fir582614Douglas-fir582712Douglas-fir582810Douglas-fir582910Douglas-firYesDying583024Douglas-fir58328Douglas-fir58336Douglas-fir583720Westernred-cedarYesTopoftreedead583822Douglas-fir583920Douglas-fir584018Douglas-fir584112Douglas-fir58428Douglas-firYesCutdown584332Douglas-fir584432Douglas-fir584512Douglas-fir584614Douglas-fir584722Douglas-fir584820Douglas-firYesDead58499Douglas-fir585016Douglas-fir58519Douglas-fir585216Douglas4ir58539Douglas-fir585426Douglas-fir585512Westernred-cedar585616Westernred-cedar585710Westernred-cedar585830Westernred-cedar58599Westernred-cedar586022Douglas-fir586122Douglas-fir586230Douglas-fir586320IDouglas-firYesHatchetgirdled586422Douglas-firGreentorestIt)RegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SEhAY”Street,RentonWA98059January5,2015Page13of24RetainTreeDangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?t586524Douglas-fir586636Douglas-fir586728Douglas-fir586822Douglas-fir586938Douglas-fir587016Douglas-fir587110Douglas-fir58728Douglas-fir587322Douglas-fir58746Douglas-fir587518Douglas-fir587610Douglas-fir587712Douglas-fir587816Douglas-fir587926Douglas-fir58808Douglas-fir588114Douglas-fir588210Douglas-firTopped588318Douglas-firX58858Douglas-firTopped58868Douglas-fir58879Westernred-cedar588812Westernred-cedar58899Westernred-cedar589012Douglas-fir589110Douglas-fir58928Douglas-firX589312Westernred-cedarX58948Westernred-cedarSweepintrunkX589516Douglas-firX58969Westernred-cedarBowintrunk589718Douglas-fir589818Douglas-fir589920Douglas-fir590048Douglas-fir59019Douglas-firX590236Douglas-firDeclineGreenforestRegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page14of24RetainTreeDangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?*X590322Douglas-firX590436Douglas-firX590522Douglas-firX590634Westernred-cedarX590712Bigleafmaple59088RedalderYesDeadX590938Westernred-cedarX591030Westernred-cedarX59117Bigleafmaple59128Westernred-cedar591320Douglas-fir591416Douglas-fir591522Douglas-fir591618Douglas-fir59176Douglas-fir59186Douglas-fir591916Douglas-fir592016Douglas-fir592118Douglas-fir59229Douglas-fir592312Douglas-fir592416Douglas-fir592620Douglas-fir592712Douglas-fir592815Douglas-fir592910Douglas-fir593015Douglas-fir593115Douglas-fir593222Douglas-fir59336Douglas-fir593415Douglas-firX593910Westernred-cedarX594020Westernred-cedarX594120Westernred-cedarX594216,7BigleafmapleX594420Douglas-firX59458PacificdogwoodGreenforestRegisteredConsultingArhorist Maherioudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page15of24RetainTree.DangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?*X594624Douglas-firX594710Douglas-firSuppressedX594817Douglas-firBowintrunkX594918Douglas-firX595016Douglas-firX595126Douglas-firX595210Douglas-firSuppressedX595312Douglas-firSlendertrunkX59548Douglas-firSuppressedX595518Douglas-firX595614Douglas-firX595714Douglas-firX595816Douglas-firX595932Douglas-firX596026Douglas-firX59617Douglas-fir59626Westernred-cedarYesDeadX596316Douglas-firX596422Douglas-firX596514Douglas-firX596618Douglas-firX596724Douglas-firX596826Douglas-firX596918Douglas-firX597114Douglas-firX597212Douglas-firX597326IWesternred-cedarX5974241Douglas-fir599526Douglas-fir599626Douglas-fir599718Douglas-fir599828Douglas-fir600814Douglas-fir600924Douglas-fir601016Douglas-fir601110Douglas-fir601214Douglas-firGreenforestRegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page16of24RetainTree.DangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?t602324Douglas-fir601422Douglas-fir60158Douglas-fir60167Douglas-fir601716Douglas-fir601812Douglas-fir601926Douglas-fir60206Douglas-fir60218Douglas-fir602212Douglas-fir602712Douglas-fir602815Douglas-fir602910Douglas-fir603036Douglas-fir603120Douglas-fir603220Douglas-fir60339Douglas-fir603427Douglas-fir603522Douglas-fir603618Douglas-fir603718Douglas-fir603830Douglas-fir60397Douglas-fir60408Douglas-fir604918Douglas-fir605020Douglas-fir605113Douglas-firX605224Douglas-fir605314Douglas-fir605436Douglas-fir605524Douglas-fir605622Douglas-fir605730Douglas-firX605832Douglas-firI___________________________X605915Douglas-fir1SuppressedX60608Douglas-firSuppressedX60618Douglas4irSuppressedGreenforest(W)RegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page17of24RetainTreeDangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?*X606220Douglas-firX606326Douglas-firX606424Douglas-firX60659Douglas-firSuppressedX60666Douglas-firSuppressedX606714Douglas-firX606812Douglas-fir60699Douglas-fir607036Douglas-fir607112Douglas-fir607232Douglas-fir607330Douglas-fir607416Douglas-fir607530Douglas-fir607626Douglas-fir607712Douglas-fir607810Douglas-fir607915Douglas-fir608020Douglas-fir608119Douglas-fir608230Douglas-fir608321Douglas-fir60846Douglas-fir60856Douglas-fir608632Douglas-fir608730Douglas-fir608824Douglas-fir608924Douglas-fir609022Douglas-fir609124Douglas-fir609228Douglas-fir609332Douglas-fir609426Douglas-fir609528Douglas-fir609634Douglas-fir609714Douglas-fir60987Douglas-firGreenforest(W)RegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page18of24RetainTree.DangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?t609912Douglas-fir610032Douglas-fir610120Douglas-fir610213Douglas-fir61039Douglas-fir61048BigleafMaple610522Douglas-fir61066Douglas-fir610736Douglas-fir612110BigleafMaple612234Douglas-fir612328Douglas-fir61838Pinkdogwood61847Pacificdogwood61857Bigleafmaple61869Katsura61879Bigleafmaple61889Katsura61899Bigleafmaple61907Redmaple61928Redmaple619310Redmaple61949Redmaple61959Redmaple619611Redmaple620016Westernred-cedar620120Douglas-fir620216Douglas-fir620318Douglas-fir620420Douglas-fir622510Westernred-cedar622612Westernred-cedar622716Westernred-cedar622814Westernred-cedar622930Douglas-fir623012Douglas-fir623124Douglas-firGreenforestRegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page19of24RetainTree.DangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?t62328Douglas-fir62338Douglas-fir623412Douglas-fir623516Douglas-fir62368Douglas-fir623]28Douglas-fir623830Westernred-cedar524020Douglas-fir624118Douglas-fir624222Douglas-fir624310Douglas-fir524434Douglas-fir624528Douglas-fir624616Douglas-fir626036Douglas-fir626326Douglas-fir626424Westernred-cedarYesDiseasedanddying626734Douglas-firX627138Douglas-firI627320Douglas-fir627428Westernred-cedar627522Westernred-cedar627612Westernred-cedar627]30Westernred-cedar627826Douglas4ir627938Westernred-cedar628024Douglas-fir628124Douglas-firX628218,28Douglas-firDoubleleader628610Douglas-fir628720Douglas-fir628810Douglas-fir62896Douglas-fir629422Douglas4ir629516Douglas-fir629614Westernred-cedar629710Westernred-cedarGreenforest()RegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144tFiStreet,RentonWA98059January5,2015Page20of24RetainTree.DangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?629926Westernred-cedar630116Douglas-fir632514Bigleafmaple632628Douglas-fir632716Douglas-fir632822Douglas-fir632916Douglas-fir633024Douglas-fir633130Douglas-fir633226Douglas-fir633312Dougla5-fir633420Douglas-fir633526Douglas-fir633638Douglas-fir633710Pacificdogwood633816Douglas-fir633930Douglas-fir634020Douglas-fir634128Douglas-fir634214Pacificdogwood634326Douglas-fir634424Douglas-fir634526Douglas-fir634622Douglas-fir634728Douglas-fir634830Douglas-fir634922Douglas-fir635024Douglas-fir635136Douglas-fir635236Douglas-fir635340Douglas-fir635424Douglas-fir635538Douglas-fir702140Douglas-fir702232Douglas-fir702326Douglas-fir702422Douglas-firGreenforest(W)RegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page21of24RetainTreeDBHSpeciesDangerousVisibledefects/notesTreeNo.Tree?t70251isDouglas-fir702640Douglas-fir702]26Douglas-fir702820Douglas-fir702920Douglas-fir703026Douglas-fir703128Douglas-fir703224Douglas-fir70796PacificdogwoodX708024Douglas-firX708116Douglas-firAsymmetriccanopyX708222Douglas-firX708310Pacificdogwood708428Douglas-fir708512Douglas-fir708634Douglas-fir708724Douglas-fir708812Pacificdogwood708928Douglas-fir709014Douglas-fir709112Douglas-fir709218Douglas-fir709326Douglas-fir709426Douglas-fir709532Douglas-fir709612Douglas-fir709716Douglas-fir709816Douglas-fir709914Douglas-fir710046Douglas-fir710120Douglas-fir710220Douglas-firX710330Douglas-firX710420Douglas-firAsymmetric..Anthracnosefungus,doubleX710510,10Pacificdogwoodleader725318MosscypressGreenforest(W)RegisteredConsultingArborist MaherJoudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page22of24RetainTree.DangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?*725416Mosscypress725510Mt.hemlock72568BirchYesDying725710BirchYesDying725820Goldenchaintree725910Hinokicypress726030Mosscypress72616Japanesemaple726224Deodarcedar72638Birch72648Birch72658Birch727410Mt.hemlock727720Whitepine727820Whitepine72796Europeanbeech728010Spruce728110Spruce728320Douglas-fir728530Douglas-fir728610AppleYesDiseased,deformedX732020KwanzancherryBrownrotfungusX732124Douglas-fir73228Redmaple732412Deodarcedar80019Deodarcedar800210Deodarcedar80039Deodarcedar80048Deodarcedar800510Deodarcedar80068Bigleafmaple800710Deodarcedar800810Deodarcedar800910Deodarcedar801012Deodarcedar80116Deodarcedar801210DeodarcedarGreenforest(W)RegisteredConsultingArborist Maherioudi,D.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page23of24RetainTree.DangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?*801310Deodarcedar80146Deodarcedar80156Deodarcedar80166Deodarcedar80177Deodarcedar80419Apple805518Douglas-fir81449Deodarcedar81457Deodarcedar81466Deodarcedar81477Deodarcedar81487Deodarcedar81497Deodarcedar81506Deodarcedar81516Deodarcedar81527Deodarcedar81537Deodarcedar81547Deodarcedar81558Deodarcedar815610Deodarcedar81576Deodarcedar81587Deodarcedar816434Douglas-fir816520Douglas-fir816634Douglas-fir817232Douglas-fir81746Douglas-fir81756Douglas-fir81767Douglas-fir81779Douglas-fir81789Douglas-fir81798Douglas-fir818010Douglas-fir818112Douglas-fir81826Douglas-fir81836Douglas-fir818411Douglas-firGreenforestRegisteredConsultingArborist Maherioudi,0.R.STRONGConsultingEngineers,Inc.RE:AlpineTreeInspection,16023SE144thStreet,RentonWA98059January5,2015Page24of24RetainTree.DangerousDBHSpeciesVisibledefects/notesTreeNo.Tree?818511Douglas-fir818610Douglas-fir81877Douglas-fir818816Douglas-fir83019Birch830415Floweringcherry830515Floweringcherry830815Purpleleafplum836515Sequoia837316Douglas-fir837416Douglas-fir837513Douglas-fir83768Douglas-fir837712Douglas-fir837815Douglas-fir837918Douglas-fir83806Douglas-fir838948Douglas-fir839032Douglas-fir839128Douglas-fir839234Douglas-fir839342Douglas-fir839442Douglas-fir839550Douglas-fir839648Douglas-fir839724IDouglas-fir839824Douglas-fir839930Douglas-fir840236Douglas-firX841612ItalianPruneBrownrotfungusX841712Kwanzancherry84346Grandfir*FromRMC4-11-200DEFINITIONST:A.Tree,Dangerous:Anytreethathasbeencertifiedasdead,terminallydiseased,damaged,orotherwisedangerous,byaprofessionalforester,licensedlandscapearchitect,orcertifiedarborist.TreeswithobviousterminaldiseasesareidentifiedinthiscolumnasdefinedbyRMC.Othertrees,whilediseasedwithbrownrotoranthracnose,arelistedasretainedtreesbecausetheirdiseaseisnotterminal.GreenforestRegisteredConsultingArborist