Draft Environmental Impact Report Appendix L · SEPTEMBER 2016 Draft Environmental Impact Report...

70
SEPTEMBER 2016 Draft Environmental Impact Report (DRAFT EIR) [STATE CLEARINGHOUSE NO. 2015021014] City of Los Angeles Los Angeles World Airports for Los Angeles International Airport (LAX) Landside Access Modernization Program Appendix L

Transcript of Draft Environmental Impact Report Appendix L · SEPTEMBER 2016 Draft Environmental Impact Report...

Page 1: Draft Environmental Impact Report Appendix L · SEPTEMBER 2016 Draft Environmental Impact Report (DRAFT EIR) [STATE CLEARINGHOUSE NO. 2015021014] ... This appendix presents the hydrology

SEPTEMBER 2016

Draft Environmental Impact Report(DRAFT EIR)

[STATE CLEARINGHOUSE NO. 2015021014]

City of Los AngelesLos Angeles World Airports

for Los Angeles International Airport (LAX)Landside Access Modernization Program

Appendix L

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Hyddrology

y and WWater QQuality

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eport

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Page 4: Draft Environmental Impact Report Appendix L · SEPTEMBER 2016 Draft Environmental Impact Report (DRAFT EIR) [STATE CLEARINGHOUSE NO. 2015021014] ... This appendix presents the hydrology

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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i   

Table of Contents  

Acronyms List ....................................................................................................................... v

Section 1 Introduction and Project Overview ..................................................................... 1‐11.1Purpose.........................................................................................................................................................................1‐11.2ProjectOverview.......................................................................................................................................................1‐11.3GeographicScopeofAnalysis..............................................................................................................................1‐41.4AnalysisFramework................................................................................................................................................1‐5

1.4.1Drainage..........................................................................................................................................................1‐51.4.2WaterQuality................................................................................................................................................1‐5

1.1 DocumentOrganization.........................................................................................................................1‐10

Section 2 Regulatory Framework ....................................................................................... 2‐12.1DrainageRegulationsandStandards...............................................................................................................2‐1

2.1.1Federal.............................................................................................................................................................2‐1FederalAviationAdministration...........................................................................................................2‐1

2.1.2Regional...........................................................................................................................................................2‐1CityofLosAngeles.......................................................................................................................................2‐1LosAngelesCountyFloodControlDistrict.......................................................................................2‐2

2.1.3SummaryofDrainageRequirementsatLAX...................................................................................2‐32.2WaterQualityRegulations....................................................................................................................................2‐3

2.2.1Federal.............................................................................................................................................................2‐3CleanWaterAct............................................................................................................................................2‐3NationalPollutantDischargeEliminationSystemProgram......................................................2‐4

2.2.2State..................................................................................................................................................................2‐4Porter‐CologneWaterQualityAct........................................................................................................2‐4WaterQualityControlPlanfortheCoastalWatershedsofLosAngelesandVentura

Counties............................................................................................................................................................2‐5NPDESConstructionGeneralPermit...................................................................................................2‐6NPDESIndustrialGeneralPermit.........................................................................................................2‐6

2.2.3Regional...........................................................................................................................................................2‐7NPDESMunicipalSeparateStormSewer(MS4)Permit.............................................................2‐7TotalMaximumDailyLoadProgram...................................................................................................2‐9

2.2.4Local................................................................................................................................................................2‐11LowImpactDevelopmentOrdinance................................................................................................2‐11StandardUrbanStormwaterMitigationPlan................................................................................2‐13

Section 3  Existing Conditions ........................................................................................ 3‐13.1DominguezNorthFloodZones...........................................................................................................................3‐13.2StormwaterDrainage..............................................................................................................................................3‐1

3.2.1ExistingInfrastructure..............................................................................................................................3‐33.2.2ExistingDrainageDeficiencies..............................................................................................................3‐3

3.3RunoffWaterQuality..............................................................................................................................................3‐43.3.1PollutantsofConcern................................................................................................................................3‐43.3.2ExistingWaterQualityConditions......................................................................................................3‐5

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3.3.3PotentialSourceAreas..............................................................................................................................3‐5

Section 4 Methodology ...................................................................................................... 4‐14.1Hydrology.....................................................................................................................................................................4‐1

4.1.1ThresholdsofSignificance.......................................................................................................................4‐14.1.2ImpactAnalysisMethodology................................................................................................................4‐1

4.2WaterQuality..............................................................................................................................................................4‐24.2.1ThresholdsofSignificance.......................................................................................................................4‐24.2.2WaterQualityImpactAnalysisMethodology..................................................................................4‐2

Section 5  Potential Project Impacts and Project Design Features .................................. 5‐15.1Drainage........................................................................................................................................................................5‐1

5.1.1PotentialProjectImpacts.........................................................................................................................5‐15.1.2ProjectDesignFeatures............................................................................................................................5‐4

5.2WaterQuality..............................................................................................................................................................5‐65.2.1WetWeatherRunoff...................................................................................................................................5‐6

5.2.1.1PotentialProjectImpacts...........................................................................................................5‐65.2.1.2ProjectDesignFeatures...........................................................................................................5‐10

5.2.2StormwaterFlows....................................................................................................................................5‐105.2.3DryWeatherFlows..................................................................................................................................5‐105.2.4ConstructionRunoff................................................................................................................................5‐10

Section 6  Mitigation Measures and Design Features ..................................................... 6‐16.1DrainageMitigationMeasures............................................................................................................................6‐1

6.1.1 Detain/ReduceProject‐RelatedStormwaterFlows............................................................6‐16.1.2 RerouteStormwaterFlows............................................................................................................6‐26.1.3 ConstructImprovementstoExistingStormwaterDrainageSystem...........................6‐2

6.2WaterQualityDesignFeatures...........................................................................................................................6‐36.3SummaryofVolumeRequirementsforOn‐SiteMitigation....................................................................6‐2

Section 7  References ..................................................................................................... 7‐3

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iii 

List of Figures 

Figure1‐1:LAMPComponentFootprint.....................................................................................................................1‐7Figure1‐2:DrainageAreaSubbasins............................................................................................................................1‐8Figure1‐3:DominguezDrainageArea.........................................................................................................................1‐9Figure3‐1:PrimaryStormDrainsinDominguezChannelArea.......................................................................3‐2Figure3‐2:Exisiting(Pre‐Project)ImperviousnessValuesintheDominguezNorthSubBasin.........3‐7Figure5‐1:DrainageAreasforLAMPComponents................................................................................................5‐2Figure5‐2:ProposedCisternsforConRAC.................................................................................................................5‐5

 

List of Tables 

Table1‐1:LAMPProjectComponents..........................................................................................................................1‐2Table2‐1:BeneficialUsesofStateWatersintheDominguezChannelBasinandSantaMonicaBay2‐5Table2‐2:MS4PermitDefinedCategories.................................................................................................................2‐8Table2‐3:MS4CategoriesforPotentialDominguezChannelConstituents.................................................2‐9Table2‐4:TMDLsforReceivingWaterBodies.......................................................................................................2‐10Table2‐5:FutureTMDLCompletionScheduleforDominguezChannel(EstuarytoVermontAvenue)......................................................................................................................................................................................................2‐10Table2‐6.SUSMPProjectTypes....................................................................................................................................2‐13Table3‐1:ExistingCharacteristicsDominguezChannelNorthSub‐Area.....................................................3‐3Table3‐2:PollutantsofConcern.....................................................................................................................................3‐4Table4‐1:EMCValues.........................................................................................................................................................4‐3Table5‐1:CompositePercentImperviousValues...................................................................................................5‐3Table5‐2:10‐yearstormPeakDepths.........................................................................................................................5‐3Table5‐4:LandUseAreasandTypes...........................................................................................................................5‐6Table5‐5:PollutantRunoffConcentrations(lb/yr)orMostProbableNumber(MPN).........................5‐8Table5‐6:RunoffVolumeforthe85thPercentileStorm......................................................................................5‐9Table6‐1:10‐yearStormMitigationVolumes..........................................................................................................6‐1Table6‐2:PotentialDrainageImprovementOptions............................................................................................6‐3Table6‐3:TypicalPollutantRemovalforBMPs(percent)..................................................................................6‐5Table6‐4VolumeRequirementsforOn‐siteAlternatives...................................................................................6‐1Table6‐5VolumeRequirementsforOn‐siteAlternatives...................................................................................6‐3

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v   

Acronyms List 

 

APM AutomatedPeopleMoverBMP BestManagementPracticesCEQA CaliforniaEnvironmentalQualityActcfs cubicfeetpersecondCIMIS CaliforniaIrrigationManagementInformationSystemCIP capitalimprovementprojectsConRAC ConsolidatedRentalCarFacilityCTA CentralTerminalAreaCWA CleanWaterActEIR EnvironmentalImpactReviewEPA EnvironmentalProtectionAgencyESA EnvironmentallySensitiveAreasHTP HyperionWastewaterTreatmentPlantIGP IndustrialGeneralPermitITF IntermodalTransportationFacilityLAMP LandsideAccessModernizationProgramLASAN LosAngelesDepartmentofPublicWorksBureauofSanitationLACDPW LosAngelesCountyDepartmentofPublicWorksLAR‐IAC LosAngelesRegionImageryAcquisitionConsortiumLARWQCB LosAngelesRegionalWaterQualityControlBoardLAWA LosAngelesDepartmentofAirportsLAX LosAngelesInternationalAirportLID LowImpactDevelopmentNAD NationalAmericanDatumNAVD NorthAmericanVerticalDatum1988NEPA NationalEnvironmentalPolicyActNCOS NorthCentralOutfallSystemNDPES NationalPollutantDischargeEliminationSystemSWMM StormwaterManagementModelSMP StormwaterManagementPlanSWPPP StormwaterPollutionPreventionPlanSWRCB StateWaterResourcesControlBoardTMDL TotalMaximumDailyLoad

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1‐1   

Section 1 

Introduction and Project Overview 

1.1 Purpose ThisappendixpresentsthehydrologyandwaterqualitytechnicalanalysisinsupportoftheDraftEnvironmentalImpactReport(DEIR)fortheLandsideAccessModernizationProgram(proposedProject)tobeundertakenbyLosAngelesWorldAirports(LAWA)atLosAngelesInternationalAirport(LAX).ThisProjectwillhelprelievetrafficcongestion,improveaccessoptionstotheairportandprovideaconnectionfromLAXtotheLosAngelesCountyMetropolitanTransportationAgency(Metro)railsystem.

InadditiontosupportingthepreparationoftheDEIR,thetechnicalanalysiscompletedfortheProjectwillalsobeusedinconjunctionwithalargerhydrologyandwaterqualityplanningprogramforLAX.LAWAhasinitiateddevelopmentofacampusairport‐wideStormwaterManagementPlan(SMP)forLAXinordertosupportongoingandfuturecapitalimprovementprojects,suchastheLandsideAccessModernizationProgram.ThehydrologyandwaterqualityanalysispresentedhereinwillbeincorporatedintothatSMP.

1.2 Project Overview TheproposedProjectareaislocatedontheeastsideofLAXandisboundedbytheTomBradleyInternationalTerminal(TBIT)onthewest,I‐405ontheeast,WestchesterParkwayandWestArborVitaeStreetonthenorth,andI‐105onthesouth.TheproposedProjectwouldconnecttheCentralTerminalArea(CTA)ofLAXwithaproposedconsolidatedrentalcarfacilityandintermodaltransportationfacilities.Table1‐1describeseachcomponentoftheproposedProjectandindicatestheapproximatesizeofeachcomponent’sfootprint.Thisanalysisusestheproposedbuildingareaandadjacentassociatedlandtoevaluatewaterqualityimpacts.Theapproximatesizeofthedrainageareaforeachcomponent,whichisusedinthisanalysistoevaluatehydrologyimpacts,isalsoshowninTable1‐1.Figure1‐1illustratestheproposedProjectareaanddelineatesthelocationsoftheindividualcomponentsdescribedinTable1‐1.

TheproposedProjectalsoincludespotentialfuturerelateddevelopment.TheEIRevaluateshydrologyandwaterqualityimpactsoffuturerelateddevelopmentataprogrammaticlevel.Thisappendixdoesnotprovideadditionalinformationonthoseimpacts.

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Section 1   Introduction and Project Overview 

1‐2 

Tabl

e 1-

1: L

AM

P Pr

ojec

t Co

mpo

nent

s

Project Component 

Description 

Location 

Build

ing Area (acres) 

Drainage 

Area (acres) 

Automated

 Peo

ple M

over 

(APM) system

 An elevated guidew

ay connecting the 

CTA

 to proposed ground transportation 

facilities. Six stations would be located 

along the alignmen

t at designated

 facilities and are included

 in the water 

quality analysis for the guidew

ay 

discussed

 in this appen

dix. 

The alignmen

t generally extends from the western 

end of the CTA

 along World W

ay to Sep

ulved

a Boulevard and then

 onto Cen

tury Boulevard. A

t Vicksburg Avenue the guidew

ay turns north and 

then

 east along West 96th until it term

inates east 

of Aviation Boulevard. 

19.8 

 

APM M

aintenance and 

Storage Facility 

Supports the operations and 

maintenance of the APM operating 

system

The southeast corner of West Arbor Vitae

 Street 

and Airport Boulevard. 

2.18 

20 

Passenger Walkw

ay system 

Connects the APM stations to passenger 

term

inals, parking garages, and ground 

transportation facilities. 

Along the APM track. 

N/A  

(included

 in track 

footprint) 

 

Modifications to existing 

term

inals 

Support the APM walkw

ay system. 

In the CTA

. N/A 

 

West Interm

odal 

Transportation Facility 

(ITF) 

Provide parking and pick‐up/drop‐off 

areas outside the CTA

. Bounded

 by West 98th street to the south, A

irport 

Boulevard to the east, W

estchester Parkw

ay to the 

north, and extends just past Jenny Avenue to the 

west. 

14 

71 

East Interm

odal 

Transportation Facility 

(ITF) 

Provide parking and pick‐up/drop‐off 

areas outside the CTA

. Situated

 east of Aviation Boulevard between W

est 

96th and W

est 98th Streets. 

11.71 (21 with 

adjacent land) 

32 

Consolidated

 Rental Car 

Facility (ConRAC) 

A facility designed

 to m

eet the needs of 

future car ren

tal operations. Facility 

users would access the CTA

 via the APM. 

The facility would gen

erally be located west of I‐

405, north of Cen

tury Boulevard., south of West 

Arbor Vitae

 Street, and east of Aviation Boulevard. 

36.73 (67 with 

adjacent land) 

75 

Roadway Im

provemen

ts 

Improve access to the proposed facilities 

and the CTA

. A series of roadway im

provemen

ts would occur 

generally in

 the areas of: 

S. Sep

ulved

a Boulevard and W

. Cen

tury 

Boulevard, just east of the CTA

East of the CTA

, bound generally by W. 

Cen

tury Boulevard to the south, S. 

Sepulved

a Boulevard to the west, the I‐405 

to the east and W

estchester Parkw

ay/W

. Arbor Vitae

 Street to the north; and  

South of W. Century Boulevard along 

Aviation Boulevard south to I‐105 as well as 

areas along 111th Street between Aviation 

N/A 

(May include space 

within the CONRAC 

and ITF areas) 

 

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1S 1‐3 Project Compon

Utilities infrastruc

Source:Nam

e,descrnent 

cture 

Both ne

ription,location,and

Description 

ew and m

odified to 

proposed projec

dsizeofLAMPcomp

 

support the 

ct.  ponents‐Ricondoa

L

Boulevard and  A

andAssociatesInc.,2

 

Location 

S. La Cienega Boule

s needed

 

2015;Drainagearea

Section 1  Int

Build

evard.  

(Ma

with a

asizes–CDMSmithro

dcution and Proj

ding Area (acres) 

N/A  

ay include space 

hin the CONRAC 

nd ITF areas) 

h,2015

ject Overview  

Drainage 

Area (acres) 

 

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Section 1   Introduction and Project Overview 

1‐4 

1.3 Geographic Scope of Analysis Figure1‐2delineatesthegeographicrelationshipbetweentheproposedProjectareaandthedrainagewatershedsatandaroundLAX.Asshown,theProjectareaislocatedmostlywithintheNorthDominguezChannelwatershed.AsmallportionoftheProjectareaissituatedtothewestoftheDominguezChannelwatershed,extendingintotheArgowatershedandtheImperialwatershed.ThetechnicalanalysispresentedhereinfocusesontheProject’spotentialdrainageandwaterqualityimpactsoccurringwithintheDominguezChannelwatershed,asthatistheonlywatershedthatwouldbemateriallyaffectedbyimplementationoftheProject.

AsfurtherdescribedinSection4,impactstohydrologyareprimarilyafunctionofproject‐relatedchangeswithrespecttoexistingperviousandimperviousareas;changesinsurfaceflowpatterns;andchangestothestormdrainsystem.Impactstowaterqualityareprimarilyafunctionofchangesinexistinglandusetypes.Whilethosetypesofproject‐relatedchangeswouldoccurwithintheNorthDominguezChannelwatershed,asdescribedindetailinSection5,suchchangeswouldnotoccurwithintheArgoandImperialwatershedswithrespecttoimplementationandoperationoftheproposedProject.AsshowninFigure1‐2,theProjectcomponentsoccurringoutsidetheNorthDominguezChannelwatershedwouldincludetheelevatedAPMalignmentthatcrossesaboveSepulvedaBoulevardintotheCTAandassociatedAPMstationsandpedestrianwalkways.Withtheexceptionoflimitedareasofornamentallandscaping,theproject‐relatedimprovementareaswithintheArgoandImperialwatershedsare100percentimpervioussurfaces,withstormwaterdrainingintotheexistingstormdrainsysteminandneartheCTA.ThedevelopmentoftheelevatedAPMsystemandassociatedimprovementswouldnotsubstantiallyaffecttheexistingsurfacecharacteristicsordrainagesystem(i.e.,wouldnotimpactexistinghydrology)withintheArgoandImperialwatersheds.Fromawaterqualityperspective,developmentoftheAPMsystemandassociatedimprovementswouldnotchangetheexistingtypesoflandusesinorneartheCTA;therefore,nosignificantchangeinexistingwaterqualitypollutantloadsassociatedwithspecificlandusetypeswouldoccurwithintheArgoandImperialwatershedsasaresultoftheproposedProject.However,constructionoftheProjectcomponentswithintheArgoandImperialwatershedsmaycausetemporaryconstruction‐relatedimpactstowaterquality:theseimpactsareaddressedinSection5.Basedonthediscussionabove,thehydrologyandwaterqualityanalysesincludedhereinarefocusedonimpactstotheNorthDominguezChannelwatershed.

TheproposedProjectfacilitiesconstituteasmallfraction(<1%)oftheDominguezChannelsubarea.TheentireDominguezChanneldrainageareaoccupiesapproximately133squaremilesinthesouthernportionofLosAngelesCounty.TheDominguezChanneldrainageareaisfurtherdividedintoseveralwatersheds,including:theDominguezChannelwatershed(consistingofapproximately58squaremiles,44%oftheentiredrainagearea);theMachadoLakewatershed;theWilmingtonDrainwatershed;andtheLosAngeles/LongBeachHarborwatersheds,asshowninFigure1‐3.TheDominguezChannelitselfbeginsapproximatelytwomileseastofLAXandextendssouthto,andthrough,theDominguezEstuary,whereitdrainstotheLosAngeles(SanPedro)Harbor.TheChannelcarriesdryandwetweatherurbanrunofffromapproximately72squaremilesofurbanareawithinLosAngelesCounty.Theuppermost6.7milesoftheChannelisconcrete‐linedandtravelsfromWest116thstreetnearI‐105toVermontAvenuenearI‐110.TheproposedProjectwouldnotphysicallyimpactoraltertheDominguezChannel.

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1‐5 

1.4 ATheteccharactwaterqmanagecomponmaybe

MoreovbuilduLAXMarecommdeficienactionsstormwwillbeoptionconsist

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ver,LAWAispontheearliasterPlananmendationsfncies,aswellsassociatedwwaterfacilitieincorporatedtoaddresssptentwiththe

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erty.TheSMPparedin200PwillprovidfacilitiestoadnvironmentadProject.AnyspotentialPrmayidentifyalspecificrec

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Section 1  Introduction and Project Overview 

1‐6   

proposedfacilities.TheLIDPlanand/orSUSMPwouldidentifyanyincreaseincontaminantloadsandproposeBMPstomitigatetheseimpacts.BMPswouldbeestablishedwiththegoalofreducingcontaminantloadingtosurfacewaterbodiesandcomplyingwiththeLIDOrdinanceandNationalPollutantDischargeEliminationSystem(NPDES)permit.LIDBMPsincludeawiderangeofBMPsthatpromoteinfiltration,reuse,orbioretention.BMPswouldbesizedinaccordancewiththeLIDManualandmayinclude:

Oil/waterseparators

Clarifiers,mediafiltration

Catchbasininsertsandscreens

Continuousflowdeflectivesystems

Detentionbasins

Manufacturedtreatmentunits

Hydrodynamicdevices

InadditiontostructuralBMPs,non‐structuralandsourcecontrolBMPscanhelptomitigatepollutantrunoff.Newnon‐structuralandsourcecontrolBMPswouldbeincorporatedintotheLAXStormWaterPollutionPreventionPlan(SWPPP)atacquisitionareaswhereindustrialactivitieswouldpotentiallyimpactwaterquality.

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1F 1‐7 

Figure 1‐1: LA

MP Component Foot  print 

  

Section 1   Introduction and Proeejct Overview 

 

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Section 1  Introduction and Project Overview 

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1F   1‐9 

Figure 1‐3: Dominnguez Drainage Arrea 

  

Section 1   Introduction and Proe

ejct Overview 

 

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Section 1 

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2‐1 

Section 2 

Regulatory Framework 

StormwatermanagementatLAXissubjecttomanyfederal,state,andlocalregulationsanddesignstandardswiththepurposeofprovidingfloodprotectionandmitigatingwaterqualityimpactsbeforebeingdischargedintodownstreamfloodcontrolfacilitiesandreceivingwaters,suchasDominguezChannel.Thissectionsummarizestherelevantfederal,regional,andlocalregulationsregardingfloodcontrolandstormwaterquality,includingcurrentFederalAviationAdministration(FAA)drainagedesigncriteriaandNPDESgeneralindustrial,municipal,andconstructionpermitrequirements.

2.1 Drainage Regulations and Standards DrainagesystemswithinLAXareownedandmaintainedbyLAWA;thesesystemsdischargetofacilitiesownedandoperatedbytheCityofLosAngelesandLosAngelesCountyFloodControlDistrict(LACFCD).Eachagencyhasitsowndrainageregulationsanddesignstandards,whicharesummarizedinthefollowingsections.Inaddition,drainagefacilitiesatLAXmustbedesignedandconstructedinaccordancetoguidelinesissuedbytheFAA.Theregulationsandguidanceestablishedbyeachagencyaresummarizedbelow.

2.1.1 Federal 

Federal Aviation Administration  

TheFAAAdvisoryCircular(AC)150/5320‐5Destablishesguidanceforengineers,airportmanagersandthepublicinthedesignandmaintenanceofairportsurfacedrainagesystemsandsubsurfacedrainagesystemsforpavedrunways,taxiways,andaprons.TheFAAguidanceincludesminimumdesignstormfrequenciesforthreecategories:

1. 2‐yearstormeventforDepartmentofDefense(DOD)airfieldsandheliports

2. 5‐yearstormeventforFAAfacilities

3. 10‐yearstormeventforareasotherthanairfields

However,thedesignfrequencymaybehighertoprotectimportantfacilities.TheACstatesthat,“thedegreeofprotectiontobeprovidedbythedrainsystemdependslargelyontheimportanceofthefacilityasdeterminedbythetypeandvolumeoftraffictobeaccommodated,thenecessityforuninterruptedservice,andsimilarfactors.”Inaddition,theACrequiressurfacerunofftobedisposedofproperlytoavoiddamagingfacilities,saturatingthesubsoil,andinterruptingtraffic.

2.1.2 Regional 

City of Los Angeles 

PertheCityofLosAngelesBureauofEngineeringStormDrainDesignManual‐PartG(1973),designfrequenciesareasfollows:

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Section 2   Regulatory Framework 

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10‐yearstormfrequencyforareaswithoutsumps.

50‐yearstormfrequencyforsumpareas.

10‐yearstormfrequencyforclosedconduitsinnaturalwatercoursesifthewatercourseismaintainedinplace.Thecombinedcapacityofwatercourseandconduitmustcontainastormof50‐yearfrequency.

10‐yearstormfrequencyforopenchannelsinnaturalwatercourseswithfreeboardtocontainastormof50‐yearfrequency.

50‐yearstormfrequencyforanystormdraininanaturalwatercourseifthewatercourseiseliminated.

Thesumpconditionreferstoinletsthatarelocatedatalowpointandtowhichwaterentersfrombothdirections.Sumpconditionsexistattheseinletswheneverwaterponds.WithinLAX,theonlyareathathasasumpconditionistheareawestoftheTomBradleyInternationalTerminal;howeverthissumpconditionwouldberemoveduponconstructionofthenewMidfieldSatelliteConcourseandisnotaddressedinfurtherdiscussionoftheproposedProjectfacilities.

Regardingoutfallcapacitylimits,designfrequenciesmaybemodifiedifthereceivingsystem’scapacityislimited.Newdrainsdischargingintoexistingdrainagesystemsmusthaveaproposedcapacitythatmeetsthereceivingdrainagesystem’scapacity.However,iftheexistingdrainagesystemisplannedtobereplacedtoaccommodatethecapacityofthenewdrain,thenewdrainshouldbesizedtotheappropriatecapacityperthedesignfrequenciesindicatedabove.Undercircumstanceswherelevelofprotectionstandardsmaybechanged,theCityofLosAngelesBureauofEngineeringshouldbeconsulted.

Los Angeles County Flood Control District  

TheLosAngelesCountyDepartmentofPublicWorks(LACDPW)establishedtheirpolicyonlevelsoffloodprotectionforusewithintheCountyofLosAngelesinamemorandumdatedMarch31,1986titledGeneralFilesNo.2‐15.3621;thismemorandumwasincorporatedintothe2006LosAngelesCountyDepartmentofPublicWorksHydrologyManual(Manual).ThethreelevelsofprotectionincludedintheManualarecapitalfloodprotection,urbanfloodprotection,andprobablemaximumfloodprotection.ThefirsttwopoliciesmaybeapplicabletotheLosAngelesFloodControlDistrict(LACFCD)‐ownedormaintainedstormdrainsinthevicinityofLAX.Probablemaximumfloodprotectionisnotapplicablefortheproposedfacilities,asfloodprotectionisonlyrequiredfor“damsanddebrisbasinsthathold1,000acre‐feet,are50feetorhigher,wouldrequireatleast1,000peopletobeevacuated,andhaveadamagepotentialof$25,000,000ormore.”LAXdoesnotincludeanydamsordebrisbasins.

Capitalfloodprotectionappliestonaturalwatercourses,whichincludechannelsandclosedconduits,floodways,naturaldepressionsorsumps,culvertsundermajorandsecondaryhighways,andtributaryareassubjecttoburning.Thecapitalfloodprotectionlevelrequiresthatdrainagesystemshavethecapacitytoconveyrunofffroma50‐yearstormfrequency.ThiscriterionappliestoaportionoftheLACFCD‐ownedDominguezChannel,whichbeginsoffsiteofLAXpropertyandisthewaterbodytowhichtheproposedProjectfacilitiesdrain.

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Urbanfloodprotectionappliestoalldevelopedareasnotcoveredunderthecapitalfloodprotectionlevel.However,sinceallon‐siteareasanddrainagesystemswithintheboundariesofLAXarealsowithintheCityofLosAngeles,theCity’sdesignstandardsapply.

SimilartotheCityofLosAngelesguidelinesonoutfalls,LosAngelesCountyoutfallsmaybemodifiedduetooutletconditions.Iftheexistingoutfallcannothandlethecapacityfromtheproposeddrain,theDesignDivisionofLACDPWshouldbeconsultedtodetermineacompatiblelevelofprotection,ortheLACFCDwillmakeplanstoprovidefuturerelieftotheexistingdrainagesystem.

2.1.3 Summary of Drainage Requirements at LAX Basedontherequirementsofthethreeagenciesdescribedabove,LAXstormdraindesignintheProjectdrainageareamustmeetthefollowrequirements:

On‐sitestormdrainfacilitiesshallbesizedtoaminimum10‐yearstormeventpertheCityofLosAngelescriteria,whichisstricterthantheFAAdesigncriteria.

OutfallstoCityofLosAngelesdrainagesystemsandLosAngelesCountydrainagesystemsmustcomplywiththeagency’scriteriaregardingcumulativecapacityimpactsontheexistingCityorCountyofLosAngelesdrain.Ifanexistingdraindoesnothavethecapacitytoreceivetheflowfromaproposeddrain,theappropriatejurisdictionwoulddecideiftheexistingdrainwillbereplacedorrelieved.Iftheexistingdrainwillnotbechanged,acompatiblelevelofdrainage/floodingprotectioncouldbedeterminedinconsultationandcoordinationwiththeagencyhavingjurisdictionoverthesubjectdrain.

2.2 Water Quality Regulations LAXissubjecttomanyfederal,state,andregionalwaterqualityregulationstomaintainadequatewaterqualitytodownstreamwaterbodiesthatreceiveairportsurfacestormwaterdischarges.Themainobjectiveoftheseprogramsistoprotectwaterbodiesandmitigatewaterqualityimpactsfromdevelopmentandmodernizationtakingplaceattheairport,aswellastomeetwaterqualitystandardsandwastedischargerequirements.

2.2.1 Federal 

Clean Water Act 

TheCleanWaterAct(CWA)of1972istheprincipalstatutethatgovernswaterqualityintheU.S.;itprovideslegalframeworktoseveralstateandlocalregulations.Theobjectiveofthisactistoprotectandrestorethenation’swaterbymonitoringthewaterqualityandcontrollingdischargefrompointsources.ThisactdesignatedtheU.S.EnvironmentalProtectionAgency(EPA)astheagencytoestablishfederalguidelines,objectives,andlimits.TheCWAisadministeredatthestatelevelbytheStateWaterResourcesControlBoard(SWRCB),andenforcedatthelocallevelbynineRegionalWaterQualityControlBoards(RWQCB).

ThroughtheirdelegatedauthorityundertheCWA,theSWRCBandtheRWQCBinLosAngeles(LARWQCB)haveadoptedandenforcedvariouspermitsandotherregulatoryactionsthataffectlocalpermittedentities,includingtheCityofLosAngelesandLAWA.

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National Pollutant Discharge Elimination System Program 

TheCWAprohibitsthedischargeofanypollutantfromapointsourceintowatersoftheUnitedStates,unlessthedischargeisincompliancewithaNationalPollutantDischargeEliminationSystem(NDPES)permit.Pointsourcesaredefinedasdiscreteconveyancessuchaspipesorman‐madeditches.IndustrialandmunicipalfacilitiesthatdischargedirectlytosurfacewatersmustalsoobtainNPDESpermits.

Tocomplywithsection402(p)oftheCWA,theEPAdevelopedatwophaseNPDESstormwaterprogramtoaddressstormwaterdischargesfromindustrialsourcesandmunicipalities.PhaseIbeganin1990andwasappliedtolargeandmediummunicipalstormsewersystems(MS4).MS4saredescribedasstormdrainsystemsandincludestreets,gutters,conduits,naturalorartificialdrains,channelsandwatercourses,orotherfacilitiesthatareowned,operated,maintained,orcontrolledbypermittees(citiesandcounties)forthepurposeofcollecting,storing,transporting,ordisposingstormwater.TheCWArequiresthatpermitsforstormdrainsystems:(i)beissuedonasystemorjurisdictionwidebasis,(ii)includearequirementtoeffectivelyprohibitnon‐stormwaterdischargesintothestormsewers,(iii)requirecontrolstoreducethedischargeofpollutantstothemaximumextentpractical(MEP),includingmanagementpractices,controltechniquesandsystem,design,andengineeringmethods.

TheEPAPhaseIstormwaterregulationsweredirectedatMS4sservingapopulationof100,000ormore,andconstructionprojectsthatdisturbanareaoffiveacresormore.TheLosAngelesmetropolitanareaandLAXarecurrentlyregulatedunderPhaseIoftheNPDESStormWaterProgram.SmallersourcescameunderregulationunderPhaseIIoftheprogram.PhaseIIautomaticallyregulatedallownersandoperatorsofsmallMS4andconstructionactivitiesthatarelessthanfiveacres,butequaltoorgreaterthanone.TheNDPESpermitsystemformunicipal,industrial,andconstructionactivitiesisdiscussedfurtherinSections2.2.2and2.2.3.

2.2.2 State 

Porter‐Cologne Water Quality Act 

ThePorter‐CologneWaterQualityAct(Act)istheprimarylawfortheregulationofwaterqualityinCalifornia.TheActappliestosurfacewaters,wetlands,andgroundwater,andtobothpointandnonpointsourcesofpollution.TheActcontainsprovisionsthatprotectwaterqualityanddesignatedbeneficialusesofwater,includingimplementationoftheNPDESprogram,dredgeandfillprograms,andcivilandadministrativepenalties.TheActrequiresprojectsthatcouldaffectthequalityoftheState’swaterthroughdischargetofileaReportofWasteDischarge(ROWD)withtheSWRCBortheappropriateRWQCBtoreceiveWasteDischargeRequirements(WDR).WhenaprojectdischargestoadesignatedwatersoftheU.S.,suchasSantaMonicaBay,DominguezChannelandtheLosAngelesHarbor,ajointNPDESPermitandROWDisissued,whichincorporatesrequirementsconsistentwithboththeCWAandthisAct.

AlsounderthisAct,theSWRCBisauthorizedtoestablishstatewidepoliciesandregulationsfortheimplementationofwaterqualitycontrolprograms,whiletheRWQCBimplementsuchpolicyprograms,developregionalbasinplans,andissueNPDESpermits.Together,theSWRCBandthenineRWQCBprotectwaterqualityandallocatesurfacewaterrights.

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Water Quality Control Plan for the Coastal Watersheds of Los Angeles and Ventura Counties 

UnderthePorter‐CologneWaterQualityAct,theStateofCaliforniaisdividedintonineregionalwaterqualitycontrolboardsforindividualpermitting,inspection,andenforcementactions.EachRWQCBisrequiredtoprepareandperiodicallyupdateaWaterQualityControlPlan(BasinPlan)thatidentifiesexistingandpotentialbeneficialusesforspecificwaterbodies.BasinPlansarethemasterpolicydocumentsthatcontaindescriptionsofthelegal,technical,andprogrammaticbasisforwaterqualityregulationineachregion.

WhiletheoriginalWaterQualityControlPlanfortheCoastalWatershedsofLosAngelesandVentura(whichincludestheCityofLosAngelesandLAX)waspreparedandadoptedbytheLARWQCB(Region4)in1976,anewplanwasadoptedonFebruary23,1995.Sincethattime,theLARWQCBBasinPlanhasbeenamendednumeroustimes.

TheLARWQCBBasinPlangivesdirectiononthebeneficialusesofStatewaters(bothsurfacewatersandgroundwater),provideswaterqualityobjectivesandpolicies,andincludesimplementationplansandmonitoringprogramstocontrolnonpointandpointsourcesofpollutantstotheState’swaters.AlldiscretionaryprojectsrequiringpermitsfromtheRWQCB(i.e.,wastedischargerequirementsandNPDESpermits)mustimplementBasinPlanrequirements(i.e.,waterqualitystandards),takingintoconsiderationthebeneficialusestobeprotected.TheLARWQCBhasdevelopedtheWaterQualityControlPlanfortheLosAngelesRegionwhichidentifiesthebeneficialusesofDominguezChannelandSantaMonicaBay(Table2‐1).

Table 2-1: Beneficial Uses of State Waters in the Dominguez Channel Basin and Santa Monica Bay

Beneficial Use  Abbreviation  Dominguez Channel  Santa Monica Bay 

Industrial Service Supply  IND  N/A  Existing 

Navigation  NAV  N/A  Existing 

Municipal and Domestic Supply  MUN  Existing  N/A 

Contact Recreation  REC‐1  Potential  Existing 

Non‐Contact Recreation  Rec‐2  Existing  Existing 

Commercial and Sport Fishing  COMM  N/A  Existing 

Marine Habitat  MAR  N/A  Existing 

Warm Freshwater Habitat  WARM  Potential  N/A 

Wildlife Habitat  Wild  Existing  Existing 

Preservation of Biological Habitat  BIOL  N/A  Existing 

Rare, Threatened or Endanger Species  RARE  Existing  Existing 

Migration of Aquatic Organisms   MIGR  N/A  Existing 

Spawning, Reproduction, and/or Early Development 

SPWN  N/A  Existing 

Shellfish Harvesting  SHELL  N/A  Existing 

Source:CaliforniaRegionalWaterQualityControlBoardBasinPlanfortheCoastalWatershedsofLosAngelesandVenturaCounties(1994)

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NPDES Construction General Permit 

PursuanttotheCWA,theSWRCBissuedastatewideGeneralConstructionActivityPermit1(ConstructionGeneralPermit)forstormwaterdischargesassociatedwithconstructionactivities(NPDESNo.CAS000002).Underthispermit,constructionactivitiesthatresultinsoildisturbancesofatleastoneacrearerequiredtoobtainanindividualNPDESpermitorbecoveredbyaConstructionGeneralPermit.Thisrequirementappliestobothprivateandpublicagencyconstructionprojects,includingprojectsundertakenatLAX.

CoveragebytheConstructionGeneralPermitisaccomplishedbyfilingaPermitRegistrationDocument(PRD)onlinewiththeSWRCB.PRDsconsistof:

a. NoticeofIntent

b. RiskAssessment

c. SiteMap

d. StormWaterPollutionPreventionPlan

e. AnnualFee

f. SignedCertificationStatement

PRDsincludespecificinformationonthetypesofconstructionactivitiesthatwouldoccuratconstructionsites(i.e.,grounddisturbance).Inaddition,thePRDsmustincludeasite‐specificplancalledtheStormWaterPollutionPreventionPlan(SWPPP)tohelpminimizepollutionfromconstructionactivities.TheSWPPPincludesBMPstoeliminateorreducestormwaterpollutantsfromleavingtheconstructionsite.TheConstructionGeneralPermitcontainsreceivingwaterlimitstopreventviolationsofwaterqualitystandards.Thepermitalsorequiresimplementationofprogramsforvisualinspectionsandsamplingforspecifiedconstituents(e.g.,non‐visiblepollutants).

NPDES Industrial General Permit 

PursuanttoCWA,theSWRCBre‐issuedastatewideIndustrialStormwaterGeneralPermit(IndustrialGeneralPermitorIGP)(SWRCBOrderNo.2014‐057‐DWQ)in2014,whichbecameeffectiveonJuly1,2015.TheIGPregulatesthedischargeof10categoriesofindustrialactivity,includingtransportationfacilities,whichdenoteportionsofLAX.Industrialactivityatatransportationfacility,asdefinedbythefederalregulations,consistsof“thoseportionsofthefacilitythatareeitherinvolvedinvehiclemaintenance(includingvehiclerehabilitation,mechanicalrepairs,painting,fueling,andlubrication),equipmentcleaningoperations,airportdeicingoperations,orwhichareotherwiseidentifiedintheregulations.”

CertainfacilitiesproposedaspartoftheProjectwouldbesubjecttotheNPDESIndustrialGeneralPermit.TheAPMmaintenancefacility,aswellasvehiclerepairandrefuelingareaswithintheConRAC,requirecoverageundertheindustrialpermitbecauseactivitiesfromthesefacilities

1SWRCBOrderNo.2009‐0009‐DWQwasadoptedin2009andbecameeffectiveJuly1,2010;amendedthereafterby2010‐0014‐DWQand2012‐0006‐DWQ.

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contributetothedischargeofindustrialpollutants(EPA,2014).Dependingontheuseofthevariousproposedparkingareas,theIndustrialGeneralPermitmayapply.UndertheIGP,employeeparkinglotsareconsiderednon‐industrialareas;however,ifstormwaterrunofffromthisareacommingleswithrunofffromaregulatedindustrialarea,thecombineddischargewouldrequirepermitcoverage.Inaddition,parkinglotsusedtostorevehiclesawaitingmaintenancealsorequirepermitcoverage(NPDES,1993).

TheIndustrialGeneralPermitrequirestheimplementationoftheBestAvailableTechnologyEconomicallyAchievable(BAT),theBestConventionalPollutionControlTechnology(BCT),andthedevelopmentofanIndustrialSWPPPandmonitoringplan.ThroughtheIndustrialSWPPP,sourcesofpollutantsaretobeidentifiedandthemeanstomanagethesourcesinordertoreducestormwaterpollutionaredescribed.TheIndustrialGeneralPermitalsorequiresimplementationofminimumcontrolmeasuresinsevencategories,listedbelow.

GoodHousekeeping

PreventativeMaintenance

SpillandLeakPreventionResponse

MaterialHandlingandWasteManagement

ErosionandSedimentControl

EmployeeTrainingProgram

QualityAssuranceandRecordKeeping

TheIGPalsoincludesarequirementforadvancedstructuralBMPs(i.e.,relatedtoexposureminimization,stormwaterreductionanddischargereduction,andtreatmentcontrol)ifNumericActionLevels(NALs)areexceeded.NALsareconcentrationsforanumberofconstituentsestablishedintheIGP.AfterJuly1,2015,ifstormwatermonitoringresultsduringtherainyseasonshowanexceedanceofoneormoreNALs,theDischargerentersaLevel1statusrequiringanevaluation,implementationaction,andreportingonmeasurestakentoavoidfutureexceedances.Ifanexceedanceofthesameparameter(s)occursinasubsequentyear,theDischargerentersLevel2statusrequiringadditionalevaluation,BMPimplementation,andreporting.

2.2.3 Regional 

NPDES Municipal Separate Storm Sewer (MS4) Permit 

Since1990,operatorsoflargemunicipalseparatestormsewersystems(MS4s)havebeenregulatedunderNPDESpermits.MS4Permitsrequireeachregulatedentitytodevelopastormwatermanagementprogramdesignedtopreventharmfulpollutantsfromimpactingwaterqualityviastormwaterrunoff.ThestormsewersystemsregulatedunderMS4sincludecurbsandgutters,man‐madechannels,catchbasins,andstormdrainsthroughouttheLosAngelesregion.ThepurposeoftheMS4PermitistoensurePermitteesarenotcausingorcontributingtoexceedancesofwaterqualityobjectivesorimpairmentsofbeneficialusesinthereceivingwatersoftheLosAngelesregion.TheLACFCD,theCountyofLosAngeles,and85incorporatedcities

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therein,includingtheCityofLosAngeles,(collectivelyreferredtoasPermittees)arejointlycoveredunderasingleMS4Permit(OrderNo.R4‐2012‐0175;NPDESPermitNo.CAS004001)forthedischargeofurbanrunofftowatersoftheU.S.

TheMS4Permitestablishesthewastedischargerequirementforstormwaterandnon‐stormwaterdischargeswithinthewatershedsofLosAngelesCounty.TheMS4Permitidentifiesconditions,requirements,andprogramsthatmunicipalitiesmustcomplywithtoprotectregionalwaterresourcesfromadverseimpactsassociatedwithpollutantsinstormwaterandurbanrunoff.UndertheMS4Permit,permitteesarerequiredtoreducepollutantsinstormwaterdischargestothemaximumextentpracticable(MEP).TheMS4Permitcontainseffluentlimitations,waterquality‐basedeffluentlimitations(WQBELS),receivingwaterlimits(RWLs),MinimumControlMeasures(MCMs),TMDLprovisions,aswellasthreecategoriesthatclassifywaterbodypollutantpriorities(Table2‐2).

Table 2-2: MS4 Permit Defined Categories

Category 1 Highest Priority  

Water body‐pollutant combinations for which TMDLs are established in Attachment N of the MS4 Permit. 

Category 2  High Priority 

Pollutants for which data indicate water quality impairment in the receiving water according to the State’s Water Quality Control Policy for Developing California’s CWA Section 303(d) List (State Listing Policy) and for which MS4 discharges could potentially be contributing to the impairment. 

Category 3 Medium Priority 

Pollutants for which there are insufficient data to indicate water quality impairment in the receiving water according to the State’s Listing Policy, but which have exceeded applicable receiving water limitations contained in the MS4 Permit and for which MS4 discharges could potentially be contributing to the exceedance. 

TheMS4PermitalsoincludesprovisionsthatallowPermitteestovoluntarilyimplementanEnhancedWatershedManagementProgram(EWMP)toachievepermitcompliancewithRWLs.TheintentoftheEWMPistocomprehensivelyevaluateopportunities,withintheparticipatingPermittees’collectivejurisdictionalboundaries,forcollaborationamongPermitteesandotherpartnersonmulti‐benefitregionalprojectsthat,whereverfeasible,retainnon‐stormwaterrunoffandalsoaddressfloodcontroland/orwatersupply.TwelveEWMPgroupshaveformedtoimplementacollaborativeapproachtomeettherequirementsoftheMS4Permit.LAXandsurroundingportionsoftheCityofLosAngelesarepartoftheSantaMonicaBayJurisdictions2and3WatershedManagementGroup.

TheEnhancedWaterManagementProgramfortheDominguezChannelWatershedManagementArea(EWMP,2015)wasdevelopedbytheDominguezChannelWaterManagementAreaGroup(DCWMG)toconformtorequirementsissuedbytheNPDESregardingtheMS4.TheEWMPaddressestheregulatoryrequirementsenforcedbytheMS4permitaswellasexistingcontaminantconditionsintheDominguezChannelwatershed.ThedatafrompriorreportsallowedtheEWMPtosortthecontaminantsintooneofthreeMS4permitcategories(Table2‐3).

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Table 2-3: MS4 Categories for Potential Dominguez Channel Constituents

Waterway Category 1 (TMDL) 

Category 2 

(303(d) List) 

Category 3 

(Other) 

Dominguez Channel (lined portion above Vermont Avenue) 

Copper, Lead, Zinc, Toxicity 

Indicator Bacteria, Ammonia, Diazonin 

Cadmium, Chromium, Mercury, Thallium, Bis (2‐Ethylhexl) phthalate, pH, Dissolved 

Oxygen 

Permitteesmustimplementminimumcontrolmeasuresthatidentifypotentialmodificationsthataddresswatershedpriorities,including:(i)DevelopmentConstructionProgram,(ii)Industrial/CommercialFacilitiesProgram,(iii)IllicitConnectionandIllicitDischargesDetectionandEliminationProgram,(iv)PublicAgencyActivitiesProgram,and(v)PublicInformationandParticipationProgram.RunofffromtheproposedProjectfacilitieswouldbetreatedon‐site,andasaresult,thebenchmarkpollutantvaluesdevelopedforprojectsapprovedforoffsitemitigationdonotapply.

Total Maximum Daily Load Program 

PursuanttotheCWA,statesarerequiredtoidentifythewaterbodiesthatdonotmeetwaterqualitystandardsdespitecontrolofpointsourcedischargesunderNPDESpermits(33U.S.C.§1313).The303(d)listindicateswhichpollutantsandstressorsareprioritiesforeachwater‐qualitylimitedor“impaired”waterbody.Priorities(i.e.,high,medium,low)wereestablishedbytheSWRCBbasedonacombinationoffactorsthatincludedthedegreeofnonattainment/complexityoftheproblemandtherelativeimportanceofthewatershed.

Forthesewaterbodies,statesarerequiredtodevelopappropriateTotalMaximumDailyLoads(TMDLs)forthepollutantsorflowscausingtheimpairment.TMDLsarethesumoftheindividualwasteloadallocations(WLAs)forpointsources,nonpointsources,andnaturalbackgroundconditions,withanappropriatemarginofsafetyforadesignatedwaterbody(40CFR130.2).ATMDLrepresentsanamountofpollutionthatcanbereleasedintoaspecificwaterbodywithoutcausingadeclineinwaterqualityandimpairmentofbeneficialuses.TMDLsareestablishedbasedonaquantitativeassessmentofwaterqualityproblems,thecontributingsources,andloadreductionsorcontrolactionsneededtorestoreandprotectanindividualwaterbody.AsopposedtotheNPDESprograms,whichfocusesonreducingoreliminatingnon‐stormwaterdischargesandreducingthedischargeofpollutantstothemaximumextentpracticable,TMDLsprovideananalyticalbasisforplanningandimplementingpollutioncontrols,landmanagementpractices,andrestorationprojectsneededtoprotectwaterquality.Onceestablished,theTMDLallocatesthepollutantloadsamongcurrentandfuturepollutantsourcestothewaterbody.Ingeneral,theimplementationofandcompliancewiththeTMDLrequirementsisnecessarywhereurbanrunoffisidentifiedasasignificantsourceofpollutantscausingimpairments.

TMDLshavenowbeenadoptedforallofthemajorimpairmentsidentifiedforDominguezChannelabovetheestuary,andtheLosAngelesHarbor,towhichtheDominguezChannelistributary,andareshowninTable2‐4.

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Table 2-4: TMDLs for Receiving Water Bodies

Waterway  Pollutant  Effective Date 

Dominguez Channel  Nutrients  July 31, 2013 

Dominguez Channel  Toxics  March 21, 2012 

Dominguez Channel  Metals   August 31, 2011 

Dominguez Channel  Trash  March 18, 2008 

Los Angeles Harbor  Bacteria  March 10, 2005 

Source:StateofCalifornia,StateWaterResourcesControlBoard,October29,2015.

Table2‐5liststheTMDLconstituentsunderreviewandtheirestimatedcompletiondate,whichindicatesthedatethatTMDLsmustbeestablishedforeachpollutant. Table 2-5: Future TMDL Completion Schedule for Dominguez Channel (Estuary to Vermont Avenue)

Pollutant/Stressor  Expected Completion 

Ammonia  01/01/2019 

Benthic Community Effects  01/01/2019 

Benzo[a]pyrene (3,4‐Benzopyrene ‐7‐d)  01/01/2019 

Benzo[a]anthracene  01/01/2019 

Chlordane (tissue)  01/01/2019 

Chrysene (C1‐C4)  01/01/2019 

Coliform Bacteria  01/01/2019 

DDT (tissue and sediment)  01/01/2019 

Dieldrin (tissue)  01/01/2019 

Lead (tissue)  01/01/2019 

PCBs   01/01/2019 

Phenanthrene  01/01/2019 

Pyrene  01/01/2019 

Sediment Toxicity  01/01/2019 

Zinc (sediment)  01/01/2019 

Source: StateofCalifornia,StateWaterResourcesControlBoard,July19,2009.

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2.2.4 Local 

Low Impact Development Ordinance 

In2011,theCityofLosAngelesBoardofPublicWorksapprovedtheStormwaterLIDOrdinance(Ordinance)toimposerainwaterLIDstrategiesonprojectsrequiringbuildingpermits.2Unliketraditionalstormwatermanagement,whichcollectsandconveysstormwaterrunoffthroughstormdrains,pipes,orotherconveyancestoacentralizedstormwaterfacility,LIDusessitedesignandstormwaterBMPstomaintainthesite’spre‐developmentrunoffratesandvolumes.ThefollowingOrdinancecategoriesmaybeapplicabletotheProjectArea:

Industrial/Commercialdevelopmentswithoneacreormoreofimpervioussurfacearea

Automotiveservicefacilities

Parkinglotsof5,000squarefeetormoreofsurfaceareaorwith25ormoreparkingspaces

TheStormwaterLIDOrdinancecallsfordevelopmentandredevelopmentprojectstomitigaterunoffthroughrainwatercapturemethodsandBMPs(e.g.,rainbarrels,permeablepavements,rainwaterstoragetanks,orinfiltrationswales).TheStormwaterLIDOrdinancerequires100percentofrainwaterfromathree‐quarterinchrainstormtobecompletelycaptured,infiltrated,and/orusedonsite.IfsiteconstraintsdonotallowforLIDstrategiestobeimplemented,off‐sitemitigationorfeepaymentforoff‐sitemitigationisallowed.CompliancewiththisordinancesatisfiesthePlanningandLandDevelopmentrequirementsoftheMS4Permit.

TheCity’sDevelopmentBestManagementPracticesHandbook3(Handbook),andtheLowImpactDevelopmentStandardsManual4weredevelopedtoassistdevelopers,aswellasCitydepartmentsforpublicworksprojectssuchasthoseatLAX,incomplyingwiththeOrdinance.TheHandbookprovidesthenecessarystepsrequiredfortheprojectreviewandpermittingprocessforobtainingapprovalofaLIDPlanincompliancewiththeOrdinance.

ProjectsmustmeetoneormorecriteriabeforetherequirementsoftheOrdinancearesatisfied.AlldevelopmentandredevelopmentprojectsthatfallintooneoftheapplicableprojectcategorieswouldberequiredtocomplywiththeOrdinanceandtheHandbook.However,theextentofcomplianceisgovernedbythefollowing:

Ifdevelopmentorredevelopmentresultsinanalterationofatleast50%ormoreofimpervioussurfacesonanexistingdevelopedsite,thentheentiresitemustcomply;

Ifdevelopmentorredevelopmentresultsinanalterationoflessthan50%oftheimpervioussurfacesofanexistingdevelopedsite,thenonlytheincrementaldevelopmentsurfacesofthesitemustcomply;and

2CityofLosAngeles,CityofLosAngelesMunicipalCode,ChapterIVArticle4.4Section64.70.01andSection64.72asamendedbyOrdinanceNo.181899,2011.Accessibleonlineat:www.lastormwater.org/wpcontent/files_mf/finallidordinance181899.pdf.3CityofLosAngeles,DevelopmentBestManagementPracticesHandbook,LowImpactDevelopmentManual,PartB,4thEdition,June2011.4CountyofLosAngeles,DepartmentofPublicWorks,LowImpactDevelopmentStandardsManual,February2014.

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Ifdevelopmentorredevelopmentofanysizethatwouldcreate2,500squarefeetormoreofimpervioussurfaceareaandislocatedwhollyorpartlyinanenvironmentallysensitivearea,thentheentiresitemustcomply.

TheCity’sOrdinancestipulatesthevolumeofstormwaterrunoffthatmustbetreatedfordevelopmentprojects.Onsitestormwatermanagementmeasuresmustbesizedtopreventanystormwaterrunofffromleavingthesitebasedonthefollowingtypesofevents:

85thpercentile24‐hourrunoffeventdeterminedasthemaximizedcapturestormwatervolumefortheareausinga48‐to72‐hourdrawdowntimebasedontheformularecommendedinUrbanRunoffQualityManagement5;or

VolumeofannualrunoffbasedonaunitbasinstoragewaterqualityvolumebythemethodrecommendedintheCaliforniaStormwaterBestManagementPracticesHandbook–Industrial/Commercial6;or

Volumeofrunofffroma0.75‐inchstormevent.

TheOrdinanceandHandbookspecifythatstormwatermanagementtechniquesbeimplementedinthefollowingorderofpriority:

1. Infiltrationsystems

2. Evapotranspiration

3. Captureanduse

4. Treatmentthroughhighremovalefficiencybiofiltration/biotreatment

TheHandbookprovidesspecificperformancestandardsandrequirementsforhighremovalefficiencybiofiltration/biotreatmentsystems.Anywaterleavingthesitefromhighremovalefficiencybiofiltration/biotreatmentsystemsisallowableastheyaredeemedincompliancewiththerequirementthatthefulldesigncapturevolumeberetainedonsite.

LIDPlansarerequiredtobecompletedandsubmittedforapprovalforallprojectsthatfallintothecategoriescoveredbytheOrdinance.TheseplansmustdemonstratehowcompliancewiththeOrdinanceandHandbookwouldbeachieved.IfimplementationofLIDrequirementsisdeemedtechnicallyinfeasible,theninfeasibilitymustbedemonstratedintheLIDPlans.However,allSUSMPrequirementsmustbemetandforanyrunoffthatcannotbemanagedonsite,offsitemitigationmustbeimplementedwithinthesamewatershed(e.g.Dominguez,SantaMonicaBay)onpublicorprivateland.ThereareanumberofconditionsorcircumstancesthatmayresultintheinfeasibilityofinstallationofLIDstormwatermanagementtechniques.Examplesinclude:

5UrbanRunoffQualityManagement,WEFManualofPracticeNo.23/ASCEManualofPracticeNo.87,19986CaliforniaStormwaterQualityAssociation,IndustrialandCommercialBestManagementPracticesOnlineHandbook,September2014.

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Locationswhereseasonalgroundwaterisbelow5feetofthesurfacegrade;

Siteswithsoiland/orgroundwatercontamination;

Locationswithin100feetofagroundwaterdrinkingwell;

Sitesonbrownfieldsorlocationswherepollutantmobilizationisadocumentedconcern;

Locationswithpotentialgeotechnicalhazards;and

Locationswithimpermeablesoiltypesasindicatedinapplicablesoilsandgeotechnicalreports.

TheHandbookshouldbeconsultedfordetailsregardingallofthepotentialconditionsthatmayresultinafindingofinfeasibilityforvarioustypesofLIDBMPs.

Standard Urban Stormwater Mitigation Plan  

OfparticularimportancetoLAWAaretherequirementsoftheSUSMPPlanningandLandDevelopmentProgramforallnewdevelopmentandredevelopmentprojectswithintheMS4Permit.AnyprojectthatcannotcomplywiththeLIDrequirementsmust,atminimum,fulfilltheSUSMPcriteria.SUSMPisapplicabletoprojectsincludingsingle‐familyhillsideresidences,100,000‐squarefootcommercialdevelopments,automotiverepairshops,restaurants,andhomesubdivisionswith10ormorehousingunits.AdditionaltypesofprojectsthataresubjecttoSUSMPrequirementsarelistedinTable2‐6.TheSUSMPrequiresthatredevelopmentprojectsthatcreate,add,orreplace5,000squarefeetormoreofimperviousareaonanalreadydevelopedsitearesubjectedtothesameconditionsasnewdevelopmentprojects.

Table 2-6. SUSMP Project Types

Development Project  Area of disturbed area 

All development projects  1 acre or greater and adding more than 10,000 square feet of impervious surface area 

Retail gasoline outlets  5,000 square feet or more of surface area 

Parking lots  5,000 square feet or more of impervious surface area or with 25 or more parking spaces 

Street and road construction  10,000 square feet or more of 

impervious surface area 

Automotive service facilities  5,000 square feet or more of surface area 

Projects located in or directly adjacent to, or discharging directly to a Significant Ecological Area where the development would discharge stormwater runoff that is likely to impact a 

sensitive biological species or habitat 

2,500 square feet or more of impervious surface area 

Source:StandardUrbanStormWaterMitigationPlanforLosAngelesCountyandCitiesinLosAngelesCounty(2000.)

DevelopmentprojectswithinthelistedcategoriesarerequiredtoincorporatethefollowingSUSMPrequirementsintotheirdesignplans:

1.Controlpeakstormwaterrunoffdischargerates

2.Conservenaturalareas

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3.Minimizestormwaterpollutantsofconcern

4.Protectslopesandchannels

5.Providestormdrainsystemstencilingandsignage

6.Properlydesignoutdoormaterialsstorageareas

7.Properlydesigntrashstorageareas

8.ProvideproofofongoingBMPmaintenance

9.DesignstandardsforstructuralandtreatmentcontrolBMPs

RelevanttoLAWA,theSUSMPincludesspecificrequirementsforprojectcategoriessuchascommercialdevelopment,retailgasolineoutlets,andautomotiverepairshopsthataddressstormwaterissues,suchastheproperdesignofparkinglotstolimitoilcontaminationandeasilyperformmaintenance.

SimilartotheLIDrequirementsdescribedabove,SUSMPBMPdesigncriteriarequirearetentionvolumeequaltothe0.75‐inch,24‐hourraineventorthe85thpercentile,24‐hourrainevent.ToassistwiththeselectionanddesignofBMPs,theSUSMPprovidesalistofexampleBMPsthatcanbeusedtoreducepollutantsgeneratedfromsiterunofftothestormwaterconveyancesystems.Sincestormwaterhasthepotentialtocontaminategroundwater,infiltrationBMPsarenotrecommendedforindustrialareasorareassubjecttohighvehiculartrafficunlessproperpretreatmentisprovided.RetentionandinfiltrationBMPscanbeimplementedforcontrollingrunofffromimpervioussurfaces.

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3‐1 

Section 3   

Existing Conditions  

ExistingconditionsintheDominguezChannelNorthdrainageareawereassessedastheypertaintopotentialfloodzones,stormwaterdraincapacityrestrictions,andexistingwaterqualityimpacts.Asdiscussedbelow,theDominguezChannelareaisnotlocatedwithinaFederalEmergencyManagementAgency(FEMA)floodzone.ExistingdrainagepatternsarediscussedbasedonpriorreportsfortheDominguezChannelarearelativetothe10‐yearstormconveyancerequirementforconduitsandthe50‐yearstormcapacityforfloodevaluationinDominguezChannel.Descriptionsofcurrentlanduseandwaterqualityconditionsarealsodescribed.ThesedescriptionsprovideabasiswithwhichtoassesstheimpactsoftheproposedProjectatLAX.

3.1 Dominguez North Flood Zones The100‐yearfloodplainistheareanearawaterwaydefinedbya1percentchanceofannualflood,whilethe500‐yearfloodplainexperiencesa0.2percentchanceofflood.TheBestAvailableMapsfromtheCaliforniaDepartmentofWaterResources(DWR,2015)indicatesthattheDominguezNorthstudyareaisnotlocatedina100‐yearfloodplain.TheFEMAFloodMapServiceCenter(MSC)wasaccessedtoviewavailableinformationonfloodplainsinthestudyarea,whichindicatethatthestudyareaisalsolocatedoutsidethe500‐yearfloodplain.

3.2 Stormwater Drainage  TwoseparatedrainagesystemsconveywaterfromtheeastsideoftheLAXpropertytoDominguezChannel(ParsonsBrinckerhoff,2002andLAWA,2005);thesestructuresincludethe“ProjectNo.13”stormdrainandtheDominguezChannelConcreteConduit,whichdividetheProjectAreaintonorthernandsoutherndrainageareas,respectively.SomeoftheproposedProjectfacilitiesintheDominguezChannelNorthSubbasinwouldbelocatedneartheProjectNo.13stormdrain,whichisshowningreeninFigure3‐1.TheProjectNo.13stormdraincapturesrunofffromthenorthernportionsoftheDominguezChanneldrainagebasin,andconveystherunoffparalleltotheconcreteconduitunder116thStreetuntilthetwostormdrainsintersect(andProjectNo.13ends)atInglewood.TheDominguezChannelConcreteConduitcontinueseasttoKornblumAvenuewhereitflowsintoanopenchannel.

DrainagesystemsegmentswithflowrestrictionsupstreamofandalongtheProjectNo.13stormdrainareidentifiedintheredboxesdepictedinFigure3‐1,andarediscussedinSection3.2.2.

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Figure 3‐1: Primary Storm

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3.2.1 Existing Infrastructure  TheProjectNo.13stormdraincollectsrunofffromthenorthernsubbasinina10’x11’6”reinforcedconcretebox(RCB)thatbeginsattheintersectionofCenturyandAviationBoulevards.ThestormdrainflowsalongCenturyBoulevard,changesdimensionsto11’6”x10’andthenturnssouthonLaCienegawhereitstartsatdimensions11’9”x10’andgraduallyreaches13’x11’.AtLaCienegaand116thStreet,thestormdraindimensionschangeto13’6”x10’6”;thesedimensionsincreaseto14’9”x14’astheProjectNo.13stormdrainflowstoajunctionwiththeDominguezChannelconcreteconduitatInglewoodAvenueon116thstreet.Theoriginaldesigncalculatedwatersurfaceprofilesfortheupstreamportionofthe10’x11’6”RCBresultedinadesignflowcapacityof730cubicfeetpersecond(cfs)whilethe14’9”x14’ReinforcedConcretePipe(RCP)outletatInglewoodAvenueprovideddesignflowcapacityof1,230cfs.Norecordswerefoundthatidentifythedesignstormforwhichtheseconduitsweresized(ParsonsBrinckerhoff,2002).Table3‐1summarizestheProjectNo.13stormdraincontributingareadesignflow.

Table 3-1: Existing Characteristics Dominguez Channel North Sub-Area

Parameter  Description 

Drainage Area  1,100 acres 

Drainage Boundaries  Manchester Boulevard to midway between Airport and Aviation, cross‐country to Arbor Vitae Street, easterly to La Cienega Boulevard, South to I‐105, west to Aviation Boulevard, north to Aviation Boulevard/Century 

Boulevard intersection, west to Century Boulevard/Sepulveda Boulevard Intersection, north to Manchester Boulevard/La Tijera Boulevard 

intersection. 

Drainage Pattern  East and South 

Outfall  Dominguez Channel (Los Angeles Harbor) 

Existing Capacities  Century Boulevard: 730 cfs 

South of 104th Street (under La Cienega between 104th and 111th): 1080 cfs 

Outlet at Inglewood Avenue into Dominguez Channel: 1230 cfs 

Downstream Control  14’‐9”Wx14’H RCB outlet into Dominguez Channel Concrete Conduit at Inglewood Avenue 

Source:LAXMasterPlanDraftEIR,2005

DrainagedeficienciesupstreamofandalongtheProjectNo.13stormdrainarediscussedinthefollowingsub‐sectionastheypertaintothefutureproposedfacilities.

3.2.2 Existing Drainage Deficiencies DrainagedownstreamofthefutureProjectfacilitiesmusthaveampleconveyanceforthe10‐yearstormevent.The10‐yearstormiscurrentlyconstrainedbystormdrainsthatdrainweston96thstreet,southonAirportBoulevard,andwestonCenturyBoulevard(LAWA,2015andPB,2002).

SeveralstudiesacknowledgethatthesectionoftheProjectNo.13stormdrainalongLaCienegaBoulevardbetween104thstreetand111thstreetisinadequatelysizedtoconveytheLADPW50‐yeardesignstorm.

Capitalfloodprotectionforthe50‐yeareventforDominguezChanneliscurrentlybeinginvestigatedbytheUSArmyCorpsofEngineers(2015).Additionally,LAWAeffortsmayhelpreducefloodrisksforthe50‐yeareventalongDominguezChannel,asfurtherdiscussedinSection5.

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3.3 Runoff Water Quality  ThissectionaddressespollutantsofconcernthataregeneratedintheDominguezChannelsubarea,aswellaswaterqualityconcernsobservedinthedownstreamreceivingwaters.

3.3.1 Pollutants of Concern TMDLsfortoxics,metals,nutrients,PCBs,pesticides,andtrashhavebeendevelopedforDominguezChannel(CASWRCB).TwentyfivepollutantsthathaveshownrecentexceedancesinDominguezChannelanditstributaries,orthatareclassifiedinthe2015EWMPasWaterBody‐PollutantCombinations(WBPCs)arepresentedinTable3‐2.SeveraloftheseconstituentshaveareasonablelikelihoodtobepresentinstormwaterrunofffromtheproposedProjectfacilities.BecauseproposedrentalcarandAPMcarmaintenanceareaswouldbelocatedwithintheDominguezChannelsub‐basin,oilandgreasemaybepresentinrunoffenteringthestormwaterconveyancesystemfromLAWAproperties(CampDresser&McKeeInc.,2001).

Table 3-2: Pollutants of Concern

Pollutant of Concern  Description  Reasonable Likelihood to be Present 

Ammonia  Fertilizer Component   

Arsenic Used in pesticides, 

herbicides, and insecticides  

Bis (2‐Ethylhexl) phthalate 

Plasticizer   

Cadmium  Heavy metal   

Chlordane  Insecticide, banned in 1988   

Chromium  Heavy metal   

Coliform Bacteria  Plastic Component   

Copper  Heavy metal 

Yes. Weathered soils, atmospheric deposition, automobile emissions and residuals (brake pad and tire wear), applied 

chemicals, and industrial and other sources can contribute to this contaminant 

Cyanide Used in processes such as 

rubber and plastic production 

 

Dichloro‐diphenyl‐trichloroethane (DDT) 

Pesticide, not been manufactured since 1985 

 

Diazinon  Insecticide   

Dieldrin  Insecticide   

Dissolved Oxygen Oxygen dissolved/carried in 

water  

E. coli  Bacteria   

Fecal Coliform  Bacteria   

Indicator Bacteria  Disease‐causing organisms   

Lead  Heavy metal 

Yes. Weathered soils, atmospheric deposition, automobile emissions and residuals (brake pad and tire wear), applied 

chemicals, and industrial and other sources can contribute to this contaminant 

Mercury Used for manufacture of 

chemicals  

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Nickel  Metal plating material   

Polycyclic Aromatic Hydrocarbon (PAHs) 

Component of fossil fuels   

Polychlorinated Biphenyl (PCBs) 

Component of coolants, banned since 1976 

 

Selenium Refining element for heavy 

metals  

Silver  Heavy metal   

Thallium  Byproduct of metal refining   

Zinc  Heavy metal 

Yes. Weathered soils, atmospheric deposition, automobile emissions and residuals (brake pad and tire wear), applied 

chemicals, and industrial and other sources can contribute to this contaminant 

Source: Pollutants of Concern from 2015 EWMP, likelihood to be present from Camp Dresser & McKee Inc., 2001 (EIS‐EIR Tech Report 6) 

BestmanagementpracticesrecommendedfortheproposedProjectfacilitiesinordertoaddressthepollutantsofconcernthatmaybepresentinstormwaterrunoffaredescribedinSection5.

3.3.2 Existing Water Quality Conditions WaterqualityintheDominguezChannelisaffectedbyseveralpointandnonpointsourcesofcontamination.Waterqualitydatacollectedfrom1993to2013intheDominguezChannel(CDMSmith,2015)showthataluminum,zinc,andcopperconcentrationswerefoundtobeapproximately25timestheannualaverageNumericActionLevel(NAL)intheIGP(asintroducedinSection2).Thiscorrespondsto0.75mg/lforaluminum,0.16mg/lforzincand0.0189mg/lforcopper(CAWaterBoard).Maximumtotalcoliformandfecalcoliformconcentrationswereabout15timestheTMDLtargets,whereasmaximumenterococcusconcentrationsweremorethan50timestheTMDLtargets.Themaximumobservedconcentrationsofoilandgrease,BOD,andCODalsoexceededNALsandmaybeapollutantofconcernincertainyears.

AfinalreportbytheEnhancedWatershedManagementProgramfortheDominguezChannelWatershedGroupalsoreportedexceedancesindissolvedmetalsfromwaterqualityassessmentsduringtheperiodof2002to2013.TheEWMPreportalsonotedexceedancesindissolvedmetalshardness‐adjustedCaliforniaToxicsRule(CTR)criteriaforcopper,lead,andzincinwetweathersamples.HighlevelsofbacteriaconcentrationsandpHvaluesabovetheBasinPlanobjectiveswerealsoobserved.TheestuarineportionofDominguezChannelshowedadverseimpactstobenthiccommunitieswith3of5stationsclassifiedasbeinginpoorcondition.

3.3.3 Potential Source Areas ExistingactivitiesatLAXandsurroundingareasgeneratepollutantsthatrunofftoDominguezChannel,whichcancontributetoexceedancesinwaterqualitystandards.Itshouldbenoted,however,thatnotalloftheseactivitiesoccurwithintheProjectArea.Runoffischaracterizedintotwomajorsourcesofwater,dryweatherflowsorwetweatherflows.Dryweatherflowsattheairportlikelyoriginatefromoutdoormaintenanceofaircraftsandvehicles,buildingandgroundsmaintenance,aircraftandgroundvehiclefueling,painting,stripping,washing,andchemicalandfueltransportandstorage.Wetweatherflowsattheairportoccurswhenthereisprecipitationthatflowsacrossthegroundbeforeandafterarainevent.

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3‐6   

Inadditiontobeingcomponentsofdryweatherflows,heavymetals,suchascopper,zinc,andleadmayexistinwetweatherflowsthatdraintoDominguezChannel.Constructionactivitiesattheairportmayalsogeneratepollutantsourcesthatadverselyaffectwaterquality,includingerosion‐inducedsediments,nutrients,tracemetals,toxicchemicals,andconstructionwaste.

Existing(pre‐projectconditions)imperviousandperviousareaswereidentifiedbasedonaerialphotographstakeninOctober2015fortheregionandareshowninFigure3‐2.Streets,parkinglots,andbuildingsareconsidered100percentimperviouswhilestreetmediansandareasofgrassorvegetationareconsideredpervious.LowdensityhousingislocatedinthenorthwestcorneroftheDominguezNorthDrainageAreaandtheManchesterSquarearea;ManchesterSquarereferstotheareaboundedbyW.CenturyBlvdtothesouth,AviationBlvd.tothewest,W.ArborVitaeSt.tothenorth,andS.LaCienegaBlvd.totheeast.Lowdensityresidentialareasareassumedtohaveanexistingimperviousvalueof25percent.ResidentialcommunitiesonlyaccountforasmallpercentageoflanduseinManchesterSquareandmostoftheexistinglanduseintheareaiscategorizedasopenspace,leadingtoexistingrunoffconditionscomprisedmainlyoftotalsuspendedsolids(TSS)suchasdirtandgravelassociatedwithopenspace.

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 Section 3   Existing Conditions 

3‐7 

Figure 3‐2: Exisiting (Pre‐Project) Im

perviousness Values in the Dominguez North SubBasin 

 

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Section 3   Existing Conditions 

3‐8 

 

Thispageintentionallyleftblank.

 

 

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        4‐1 

Section 4 

Methodology  

ThissectiondescribesthemethodologyusedtoassesspotentiallysignificanthydrologicandwaterqualityimpactsfortheproposedProject.Theimpactanalysesarebasedonavailableinformation.

4.1 Hydrology 4.1.1 Thresholds of Significance Impactstodrainageandhydrologyareevaluatedforsignificancerelativetoidentifiedsignificancethresholds.ThisappendixpresentsthresholdsusedinpreviousLAXreportstoassessthesignificanceofhydrologyimpactsthatarerelevanttothisanalysis.AsignificanthydrologyimpactwouldoccuroftheProjectwouldeither:

Increaserunoffthatwouldcauseorexacerbatefloodingwiththepotentialtoharmpeople,damageproperty,damagesensitivebiologicalresources,orwouldexceedthecapacityofexistingorplannedstormwaterdrainagesystems

Causesubstantialalterationoftheexistingdrainagepatternofthesiteinamannerwhichwouldresultinsubstantialerosionorsiltationon‐oroff‐site.

TheimpactanalysispresentedinthistechnicalappendixutilizesthequantitativeclassificationofasignificanthydrologicimpactasdescribedinSection4.1.2below(i.e.,floodprotectionfora10‐yeardesignstormandfora50‐yeardesignstorm).Specificdesignstormsareanalyzedforpre‐andpost‐developmentconditionsforpotentialexceedanceofexistingdrainagesystemcapacity.

4.1.2 Impact Analysis Methodology AsdescribedinSection2,stormsizesareusedbyagenciesandengineersasstandardstodictateconveyancedesignstoattenuatefloodingandhydrologicimpacts.TheFAA,LACDPW,andtheCityofLosAngelesdesigncriteriastatethatthedesignandimprovementsofstormdrainsshouldprovidefloodprotectioncapacityforaminimumofa10‐yearstormevent.ForopenchannelsandotherregionalfacilitiessuchasDominguezChannel,theLACDPWHydrologyManualrequiresprotectionfromtheCapitalFloodwhichisdefinedasthe50‐yeardesignstorm.Asaresult,thesignificanceofincreasesinrunoffduetodevelopmentoftheproposedProjectisevaluatedfortheimpactonstormdrainsfroma10‐yeardesignstorm,andonDominguezChannelfromthe50‐yeardesignstorm.Existingsiterunoffratesandvolumeswerecomparedtositerunoffunderdevelopedconditions.Peakrunoffflowratesfromthedevelopedconditionsthatwouldexceeddrainagesystemcapacityforeitherofthesedesignstorms,dependinguponthedesignstormfrequencyforspecificdrainagefacilities,isconsideredasignificantimpactasitmaycauseupstreamsurfaceflooding.Stormdrainagesystemsthatcannotachieve10‐yearcapacityareconsidereddeficient.

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Section 4   Methodology 

4‐2   

TheLosAngelesCountyHydrologyManual(2006)definesthe50‐year,24hourdesignstormdepthoverthearea,andtheappropriatecoefficientsbywhichtomultiplythisdepthtodownscaletothe10‐yearstormintensity.Ahyetograph(i.e.,graphindicatingdistributionofrainfalleventsovertime)fortheVeniceBeachareaindicatesthattheManchesterSquareandDominguezChannelareashavea50‐year,24‐hourdesignstormvaluebetween5.0and5.2inches(LosAngelesCountyDepartmentofPublicWorksHydrologyManual,2006).Anaverage50‐yearrainfallof5.1inchesisutilizedforthisanalysis.Amultiplicativecoefficientof0.714yieldsthe10‐yearstorm,asspecifiedintheLosAngelesCountyHydrologyManual.

Toassessthepotentialoffloodingandhydrologyimpact,thepeakflowratefortheproposedProjectareawascalculatedandcomparedtothedesigncapacityoftheexistingdrainagesystemusinganEPASWMMmodeltoassessanypotentialincreasesindownstreamstormdrainwatersurfaceelevations.Thisapproachcomparestwodrainageareasbasedontheamountofimperviousareaandassociatedlanduse.Achangeinlandusewithallotherparametersheldconstantwouldproduceachangeintheamountofimperviousareaandacorrespondingchangeinstormwaterpeakflowrates.Theincreaseinpeakflowrunoffratefromtheincreaseinpercentageofimperviousareamayexceedthedesigncapacityforthedrainagestructure,andthus,increasethelikelihoodofflooding.

4.2 Water Quality  4.2.1 Thresholds of Significance SurfacewaterflowsthataregeneratedwithintheProjectAreaboundariesultimatelydraintotheDominguezchannel.Thequalityoftherunoffcanimpactthewaterqualityofthereceivingwaterbodies.TheL.A.CEQAThresholdsGuide(2006)defineasignificantwaterqualityimpactasdirectandindirectchangestotheenvironmentthatmaybecausedbytheProject.Morespecifically,theProjectwouldcauseasignificantimpactifdischargesassociatedwiththeProjectwouldcreatepollution,contamination,ornuisanceasdefinedinSection13050oftheCleanWaterCode(CWC)orthatcauseregulatorystandardstobeviolated,asdefinedintheapplicableNPDESstormwaterpermitorWaterQualityControlplanforthereceivingwaterbody.TheimpactanalysisinthistechnicalappendixrecognizesNPDESLIDspecificationsastheapplicableregulatorystandardbywhichtodeterminesignificantwaterqualityimpacts(i.e.,wouldtheprojectprovideforwaterqualityBMPssufficienttocaptureandtreatrunofffromthe85thpercentiledesignstorm).

4.2.2 Water Quality Impact Analysis Methodology Theeventmeanconcentration(EMC)isusedtoestimateProjectpollutantloadings.Sincelandusecanbequantifiedbyamountandtype,theEMCshavebeenusedtocharacterizepollutantconcentrationsinurbanrunoff.TheEMCrepresentstheaverageconcentrationofapollutantduringastormevent.Itdoesnot,however,considerfluctuationsofloadswithinstormevents.LocalEMCdataforlandusecategorieshavebeencompiledbytheseveralmunicipalitiesthatparticipatedinanextensivestormwatermonitoringprogramtosupportstormwaterqualitymanagementinLosAngelesCounty.EMCsforallthelandusecategories,withtheexceptionofairportoperationsandairportopenspace,isbasedondatacollectedbetween1994and2000bytheLosAngelesCountyDepartmentofPublicWorks,asshowninTable4‐1.

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 Section 4   Methodology 

4‐3 

Table 4-1: EMC Values

Pollutant  EMC for Industrial (mg/l) 

EMC for Commercial 

(mg/l) 

EMC for Open Space 

(mg/l) 

EMC for Mixed 

Residential (mg/l) 

EMC for Transportation 

(mg/l) 

Total Suspended Solids (TSS)  240  66  186  63  78 

Total Phosphorus  0.41  0.39  0.16  0.26  0.44 

Total Kjeldahl Nitrogen (TKN) 

3.00  3.40  0.79  2.50  1.90 

Total Copper  0.03  0.04  0.02  0.02  0.06 

Total Lead  0.02  0.02  0  0.01  0.01 

Total Zinc  0.64  0.24  0.05  0.20  0.29 

Oil and Grease  1.70  3.30  0  0  3.10 

Biological Oxygen Demand (BOD) 

20  27  12  18  21 

Chemical Oxygen Demand (COD) 

80  98  17  64  50 

Ammonia  0.59  1.26  0.13  0.67  0.29 

Fecal Coliform (MPN/100ml)  338,220  528,750  1,397  100  328,750 

Fecal Enterococcus (MPN/100ml) 

98,200  86,250  679  0  32,000 

Source: LACDPW (http://ladpw.org/wmd/npdes/9400_wq_tbl/Table_4‐12.pdf) 

Developmentorredevelopmentprojectsthat,asrequiredbytheSUSMP,create,add,orreplace5,000squarefeetormoreofimperviousareaonanalreadydevelopedsite,shallprepareanLIDplantoreducestormwaterandpollutantrunofffrom100percentofthesitearea.BasedontheLIDplan,BMPsshouldbeadoptedtoinfiltrate,evapotranspirate,capture,andtreatstormwaterrunoff.Thevolumeofrunoffproducedfromthe85thpercentile,24‐hourstormeventcanbeusedtospecifythedesignofvolumetric‐basedstormwaterqualityBMPs.

Themodifiedrationalmethod(CityofLA,2011)wasusedtodeterminethevolumerequiredfortreatment.Thismethodrequiresthataunithyetographforthedesignstormbeestablishedbeforerunoffcomputationscantakeplace.AssumptionsregardingthehyetographtimingandhighestintensityweremadeinaccordancewiththeLosAngelesCountyHydrologymanual.ThemaximumintensityforaspecifieddurationwasfoundusingtheLosAngelesCountyspecifiedIntensity‐Duration‐Frequency(IDF)equationthatrelatesthestormintensity,duration,andfrequency(Equation4‐3).Thetotalstormvolumeiscomputedasthesumoftherunoffvolumeunderthehydrographgeneratedfromthedesignhyetograph.

Equation4‐1wasimplementedateachtimestepandsummedtodeterminetherunoffvolume.Thedesignstormintensity(It)ismultipliedbyadevelopedrunoffcoefficient(Cd)andthesubbasinarea(A)toyieldapeakflow(Q,incfs)thatmustbemitigatedduetodevelopment(CityofLAAppendixF,2011).

Equation 4-1:

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Section 4   Methodology 

4‐4   

ThevariableCdisthedevelopedrunoffcoefficientforthebasinandrepresentstheratioofrunoffratetorainfallintensityperEquation4‐2.

Equation 4-2: 0.9 1.0

Thepercentoftheimperviousarea,Imp,isspecifiedas0to1andCu,theundevelopedrunoffcoefficient,isafunctionofsoiltypeandrainfallintensity.Soiltype20,andtherelatedCuasafunctionofrainfallintensityfromLosAngelesCounty,wasusedfortheManchesterSquarearea.

Therainfallintensityforthesub‐areainEquation4‐1iscomputedinEquation4‐3.

Equation 4-3: .

Thevariabletrepresentsthedurationinminutes;thisisspecifiedasthetimeofconcentrationforasub‐basin.Therainfallintensityfortheduration(ininchesperhour),It,isdividedbythe24‐hourrainfallintensityI1440toyieldadimensionlessratio.ThetimeofconcentrationsubstitutedfortinthisequationiscomputedforasshowninEquation4‐4.

Equation 4-4: . .

. .

ThelongestflowpathlengthfromthewatershedboundarytotheoutletisgivenasL,theslopeofthisflowpathisS,andItrepresentstherainfallintensityasexpressedinEquation4‐3.NotethataninitialapproximationforthetimeofconcentrationmustbegiveninEquation4‐3inordertodeterminearainfallintensitythatisusedinEquation4‐4.ThetimeofconcentrationfortheseareasintheDominguezChannelNorthSubbasinwascalculatedbypartitioningdevelopmentintosubareastoyieldanexistinganddevelopedpercentimperviousnesscausedbyeachProjectcomponent.Theslopewasdeterminedbysubtractingtheelevationofthemostremotepointinthesubareatothesubareaoutletanddividingtheresultbythelengthbetweenthetwopoints.

TherunoffcoefficientinEquation4‐2wasdevelopedassumingthateachProjectcomponentwouldaddanareathatis100%impervioustothesite.Themostconservativewaytoensurethe85thpercentilerequirementisaddressedwastoaddresstheflowfromthe100%imperviousnewfootprint,assumingnorunofffrompre‐developedconditions.Thisanalysisprovidesconservativehighpeakflowratecalculations.

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5‐1 

Section 5   

Potential Project Impacts and Project Design 

Features 

PotentialimpactsoftheproposedProjectrelativetoexistingconditionswereaddressedaschangesinpeakflowratesfordrainage,andchangesinthedischargeofpollutantsofconcernforwaterquality.HydrologicimpactswereassessedbycombiningProjectelementswithneighboringroadwaysandAPMGuideway.Hydrologicimpactsforthefollowingdrainageareasaredescribedinthissection.

ConRACandadjacentroadwaysandAPMGuideway

ITFEastandadjacentroadwaysandAPMGuideway

APMStorageandMaintenanceFacilityandadjacentroadwaysandAPMGuideway

ITFWestandadjacentroadwaysandAPMGuideway

Approximately1.7acresofproposedroadwayneartheintersectionof111thSt.andAviationBlvd.

WaterqualityimpactswereassessedfortheseparatefootprintofeachProjectcomponent.Methodsusedtoexaminehydrologyandwaterqualitywerediscussedintheprevioussection;thischapterpresentsdetailsforandtheresultsoftheanalysis.

5.1 Drainage  5.1.1 Potential Project Impacts Drainageimpactsweredeterminedbasedonchangesinlanduseandsitegradingasopposedtobuildingfootprint;drainagebasinsweredefinedforeachProjectcomponentasshowninFigure5‐1.AnEPASWMMmodelwasusedtoassessanypotentialincreasesindownstreamstormdrainwatersurfaceelevationsthatwouldresultfromdevelopment.

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S   F Section 5   Potent

Figure 5‐1: Drainaia

l Project Im

pacts

age Areas for LA

Ms and Project Desig

MP Components 

n Features 

5‐2 

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Section 5   Potential Project Impacts and Project Design Features  

5‐3 

ThechangeinimpervioussurfacesareshowninTable5‐1fordrainageareasdefinedinFigure5‐1.Section4indicatesthatperviousareasareassignedtheundevelopedlanduserunoffcoefficientbasedonareasoiltype.ThePre‐ProjectConditionsrowsinthetableconstitutesthedrainageareaswithvaryingpercentimperviousnessbeforetheproposedProjectdevelopment.

Table 5-1: Composite Percent Impervious Values

Project Component 

Project Condition 

Total Drainage Area 

 (Acres) 

Area 100% Impervious (Acres) 

Area 25% Impervious (Acres) 

Area Pervious (Acres) 

Composite Percent 

Impervious1  

ConRAC 

Pre‐Project   75  22  3  50  30% 

Proposed Project  

75  72  0  3  96% 

East ITF 

Pre‐Project  32  14  4  14  47% 

Proposed Project 

32  27  0  5  84% 

West ITF 

Pre‐Project   71  69  0  2  97% 

Proposed Project  

71  70  0  1  99% 

APM Maintenance 

Facility 

Pre‐Project   20  7  0  13  35% 

Proposed Project  

20  11  0  9  55% 

Roadways near South Airfield 

Pre‐Project  34  5  0  29  15% 

Proposed Project 

34  7  0  27  20% 

1Composite Percent imperviousness =  % . % %  

 

ParkinglotscurrentlycovertheWestITFdevelopmentarea,andadditionofanewstructurewouldhaveminimalimpactonthepercentofimpervioussurface.TheAPMmaintenancefacilitywouldbeconstructedonamostlyemptylotwithmulti‐familyandcommerciallanduseinthenorthwestcorner.Existing(pre‐project)conditionsinManchesterSquareincludeopenspace,roads,andexistinglowdensityresidentialdevelopment.

Table5‐2delineates,foreachoftheProject’smaincomponents:

Theexisting(i.e.,pre‐project)downstreamdrainagesystempeakdepthsforthe10‐yeardesignstorm,thefuturedownstreampeakdepthsthatwouldoccurwithimplementationoftheproposedProject(i.e.,estimatedincreaseindownstreamflowsresultingfromtheProject)

Theestimatedvolumeofstormwaterdetentionthatwouldberequiredforeachprojectcomponentinordertomaintaintheexisting/pre‐projectdownstreampeakdepthsforthe10‐yeardesignstorm.

Table 5-2: 10-year storm Peak Depths

Component Existing Downstream Peak 

Depth (ft) Future  Downstream Peak 

Depth (ft) Detention Volume Required (ft3) 

ConRAC  4.44 (to the north)  6.28 (to the north)  571,000 

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Section 5   Potential Project Impacts and Project Design Features 

5‐4 

12.81 (to the south)  15.13 (to the south) 

East ITF  9.57  12.04  200,000 

West ITF 12.41 (to the south) 

12.45 (to the east) 

12.80 (to the south) 

12.87 (to the east) 94,000 

APM Maintenance 

Facility 5.21  7.67  23,000 

Roadways near South Airfield 

1.39  1.39  0 

ItshouldbenotedthatalthoughtheWestITFisbeingconstructedonanexistingparkingareasandtherewouldbeanegligibleincreaseinimpervioussurfaceareaandassociatedrunoffassociatedwiththatcomponentoftheProject,rerouteddrainagepatternsintheareawouldrequiredetentionvolumeabovethatwhichiscurrentlyavailable.

ItshouldalsobenotedthattheincreasedstormwaterflowattributabletotheproposedProjectwouldaddtoanalreadysurchargedcondition(i.e.,theexistingdrainagedeficienciesdescribedaboveinSection3.3.3),whichistheresultofbothLAWAexistingflows(i.e.,runofffromLAWAproperties)andnon‐LAWAexistingflows(runofffrompropertiesowned/controlledbyothers)reachingthedownstreamdrainagesystem.Assuch,theproposedProjectmaybeonlypartiallyresponsibleforfuturedrainagesystemimprovementsnecessarytoaddresssuchdrainagedeficiencies,asfurtherdescribedbelow.

5.1.2 Project Design Features Undergroundcisternswithatotalvolumeof500,000ft3areincludedintheproposedProjectdesignforstormwatercapturebeneaththeConRACfacilityasshowninFigure5‐2.Althoughthecisternsareproposedandsizedprimarilytoaddresspotentialwaterqualityimpacts,asfurtherdiscussedinSection5.2below,theirfunctioninstoring/retainingstormwaterwouldalsoservetoreducehydrologyimpacts,specificallyasrelatedtoreducingProject‐relatedpeakflows.

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Section 5

Figure 5

DistribuConRACcisternretain3designrequirepeakde

TheothWhilerdetailedmainlymeasurresultithatharunoffwsystemproposdamagehydrolo

5   Potential P

5‐2: Proposed 

utionofthepCrunoffisdiswouldreta389,000ft3infeaturewouledfortheproepthtonote

herLAMPfacrunoffdetentdplanninganinresponseresarenotcunsignificantsexistingdowaterwhichs,sotheimpedProjectweproperty,Sogyimpacts.

Project Impacts

Cisterns for C

proposedcisirectedtothein111,000ftnthesouthfoldaccommodoposedConRxceedtheex

cilities,ascurtionmeasurenddesignoftomeetingLurrentlydefithydrologyimownstreamdwouldexcee

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ninFigure5‐ortion,whilenthenorthertentionvolumimately88%eareainordestreampeak

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ecifieddetencorporatedinmeasuresfoSection5.2beascurrentlyowswithinauldcreateordstormwaterbesignificanntialtoharmstoaddress

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Section 5   Potential Project Impacts and Project Design Features 

5‐6 

5.2 Water Quality  AssessmentofpollutantrunoffutilizesthedrainageareasandimperviousvaluesdiscussedinSection5.1;thewaterqualityimpactforthe85thpercentilestormisconservativelycalculatedassumingtheProjectcomponentfootprintsare100%impervious;potentialsmallperviousareasincludingcourtyards,grassbetweensidewalks,andplantersareignored

5.2.1 Wet Weather Runoff 

5.2.1.1 Potential Project Impacts 

WetweatherrunofffromtheproposeddevelopmentareaswouldresultinsomeincreasedpollutantloadsthatwouldbedischargedtotheDominguezChannelNorthsubbasinandeventuallytotheDominguezChannelanddownstreamreceivingwaters.Eventmeanconcentrations,listedinTable4‐1,togetherwithtotalrunoffvolumeswereusedtocalculatepre‐andpost‐Projectpollutantloadsintheabsenceofanyproject‐specificmeasurestoreduceloads.FivetypesoflanduseforwhichEMCvaluesareavailablewereassumedtorepresentdifferentportionsofexistingand/orfuturelandusesintheProjectArea:industrial,commercial,openspace,transportation,andmixedresidential.

Changestothelandcoverasaresultofthedevelopment(proposedProjectconditions)oftheConRACandEastITFfacilitieswouldreduceopenspaceareaby56acresandreducemixedresidentialby7acres.Thefacilitieswouldincreasecommercialareaby27acresandincreaselanddevotedtotransportationby36acres.ThereductioninopenspacelandusewouldresultinanetincreaseinimperviousareaandanassociateddecreaseininfiltrationvolumewithintheManchesterSquarearea.Thischangeintotalimpervioussurfaceareawouldincreasecontaminantloadinsurfacewaterrunoff.TheannualtotalpollutantloadinstormwaterrunofftoDominguezChannelforbacteria,oilandgrease,totallead,andammoniawouldincreaseduetoadditionalimpervioussurfacessuchasroadsandparkingfacilities.

Similarly,conversionofopenspaceareatotransportationareaforthedevelopmentoftheWestITFandAPMfacilitieswouldincreaseimpervioussurfacesanddecreaseinfiltrationintheprojectarea.TheconversionofopenspacetotransportationlanduseforthedevelopmentoftheWestITFwouldincreasecontaminantloadsforallconstituentsexceptfortotalsuspendedsolids(TSS)comparedtoexistingconditions.DevelopmentoftheAPMmaintenancefacilitywouldalsoconvertopenspacetoindustrialandtransportationlanduse,impactingsurfacerunoffandwaterquality.Greaterestimatedloadsarepredictedforbacteria,lead,zinc,andoilandgreaseasaresultofincreasedimpervioussurfaces.

Table5‐4categorizesthelandusetypesforpre‐andproposedprojectconditionsbasedonthedrainageareasdepictedinFigure5‐1.Table5‐4areaswereusedtoassesscontaminantvolumesinrunoff,percentimperviousisderivedfromtheselandusetypesbydenotingopenspaceas0%impervious,mixedresidentialas25%impervious,andallotherlandusetypesas100%impervious.Thetotalpercentimperviousisacompositedpercentimperviousforthetotalprojectcomponentdrainagearea.

Table 5-4: Land Use Areas and Types

Project  Land Use  Pre‐Project Conditions  Proposed Project Conditions 

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Section 5   Potential Project Impacts and Project Design Features  

5‐7 

Component Area (Acre) 

Percent of Total Area 

Area (Acre) Percent of Total 

Area 

ConRAC 

commercial  1  1%  37  49% 

transportation  21  28%  35  47% 

mixed residential  3  4%  0  0% 

open space  50  67%  3  4% 

total  75  30%  75  96% 

ITF East 

commercial  9  28%  0  0% 

transportation  5  16%  27  84% 

mixed residential  4  13%  0  0% 

open space  14  44%  5  16% 

total  32  47%  32  84% 

APM 

Maintenan

ce 

and Storage

 Facility 

commercial  3  15%  0  0% 

transportation  4  20%  8  40% 

open space  13  65%  9  45% 

industrial  0  0%  3  15% 

total  20  35%  20  55% 

ITF West 

commercial  0  0%  0  0% 

transportation  69  97%  70.2  99% 

open space  2  3%  0.8  1% 

industrial  0  0%  0  0% 

total  71  97%  71  99% 

Source:RicondofacilitymapandArcGISaerialimagery(accessed2015)

UndertheproposedProject,theestimatedannualtotalpollutantloadgeneratedwithintheprojectareawouldincreaseforallconstituentsevaluatedcomparedtoexistingpre‐projectconditions.TheAPMmaintenancefacilityisconsideredanindustrialbuildingbeingplacedonopenspace;withacommercialareaadjacenttotheproposedfacility.TheConRACandEastITF,tobedevelopedintheManchesterSquarearea,wereconsideredtobeconstructedonopenspacewithaportionofmixedresidentialandtransportationlandusestodeterminethemaximumloadvolume.DevelopmentoftheManchesterSquareareawouldincreasetheoverallpercentofimpervioussurfacesbyconvertingopenspaceandresidentiallandusetopredominantlycommercialandtransportationlanduses.PortionsoftheAPMMaintenanceandStorageFacilityandConRACmaybecoveredbyaroof,andanypotentialindustrialactivitieswithinthesefacilitieswouldbeunlikelytocontributetothisincreaseduetoroofrunoffcontrol.

PollutantloadsdischargedtoDominguezChannelbysurfacewaterrunoffwouldincreaseintheabsenceofanycontrolmeasures.ThelargestpercentileincreasesduetoProjectconstructionareforoilandgrease,lead,zinc,andammoniaasshowninTable5‐5.

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pacts and Project Design Features 

5‐8 

Tabl

e 5-

5: P

ollu

tant

Run

off

Conc

entr

atio

ns (l

b/yr

) or

Mos

t Pr

obab

le N

umbe

r (M

PN)

Drainage Area 

TSS 

Total 

Phosphorus 

TKN 

Total 

Copper 

Total 

Lead

 To

tal 

Zinc 

Oil an

Grease 

BOD 

COD 

Ammonia 

Fecal Coliform

 (M

PN) 

Fecal Enterococcus  

(MPN) 

ConRAC 

Pre‐Project 

9,503 

16 

77 

1.94 

0.22 

58 

953 

1,859 

13 

2.90E+13 

3.06E+12 

Proposed Project 

12,025 

64 

409 

2.29 

40 

484 

3,715 

11,388 

120 

2.96E+14 

4.11E+13 

Percent Change 

from Pre‐Project 

26.5% 

306.9% 

432.9% 

279.2% 

934.6% 

401.8% 

733.3% 

289.9% 

512.7% 

791.0% 

923.7% 

1245.8% 

ITF East 

Pre‐Project 

4,469 

10 

71 

53 

685 

1,892 

20 

3.40E+13 

5.00E+12 

Proposed Project 

5,700 

24 

104 

15 

157 

1,177 

2,694 

16 

7.58E+13 

7.40E+12 

Percent Change 

from Pre‐Project 

27.5% 

127.6% 

45.7% 

161.3% 

57.0% 

154.9% 

198.7% 

71.9% 

42.4% 

‐20.9% 

123.1% 

47.9% 

APM M

aintenance Facility 

Pre‐Project 

2,746 

26 

21 

301 

670 

1.24E+13 

1.69E+12 

Proposed Project 

3,979 

41 

39 

443 

1,045 

2.19E+13 

3.34E+12 

Percent Change 

from Pre‐Project 

44.9% 

73.7% 

56.8% 

67.1% 

96.2% 

160.5% 

88.5% 

47.1% 

55.9% 

11.5% 

76.1% 

97.8% 

ITF West 

Pre‐Project 

12,205 

65 

281 

43 

454 

3,124 

7,389 

43 

2.19E+14 

2.13E+13 

Proposed Project 

12,111 

67 

289 

44 

469 

3,195 

7,587 

44 

2.26E+14 

2.20E+13 

Percent Change 

from Pre‐Project 

‐0.8% 

2.6% 

2.5% 

2.6% 

3.3% 

3.0% 

3.3% 

2.3% 

2.7% 

2.5% 

3.3% 

3.2% 

All Drainage Facilities 

Pre‐Project 

28,923 

96 

456 

12 

59 

585 

5,063 

11,810 

83 

2.94E+14 

3.10E+13 

Proposed Project 

33,815 

162 

842 

20 

106 

1,149 

8,530 

22,714 

187 

6.20E+14 

7.39E+13 

Percent Change 

from Pre‐Project 

16.9% 

69.4% 

84.8% 

65.9% 

114.7% 

78.8% 

96.3% 

68.5% 

92.3% 

125.7% 

110.8% 

137.9% 

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5‐9 

InTable5‐5,thespecificlandusetypesfactorintotheEMCcalculationsastherunoffvolumeofeachcontaminantisweightedpertheappropriateboundariesofeachlanduseinthedrainagearea.ThetotalannualrainfallintheLAXareaisrecordedbytheWesternRegionalClimateCenter(WRCC,2015).Theaveragerainfallbetweentheyears1936to2015is12.02inches;thisvaluewasmultipliedbytheProjectareaandEMCvaluestodeterminepollutantloading.Multiplyingtheannualrainfallbythemeanconcentrationsyieldsacontaminantrunoffvolume.

Increasesinestimatedloadswouldrangefrom96percentforoilandgreaseto17percentforTSS.AlthoughEMCvaluesforTSSundertransportationlandusearelessthanopenspace,conversionfromopenspacetotransportationwouldresultingreaterestimatedTSSloadsasaresultofincreasesinimperviousarea,whichwouldgeneratelargerrunoffcoefficientsandmoreaverageannualrunoffs.Similarly,changestolandusewiththeadditionofanAPMmaintenancefacility,WestITF,andotherProjectcomponentsarepredictedtoproducegreaterestimatedloadsforallconstituents.TSS,however,isreducedasaresultoftheproposedWestITFdevelopment.ThisdevelopmentwoulddecreaseTSSby0.8percent.SincemodernizationinthewesternportionsoftheProjectareawouldbeonpreviouslyexistingimpervioussurface,developmentinthisregionwouldresultinsmallerincreasesinthepercentofimpervioussurfaces.

Overall,theproposedProjectwouldincreasepollutantloadingduetotheeffectsoflanduseintensificationandchangesinimperviousarea,andrelativeincreasesandpercentagechangesincontaminantloading.

BMPstoaddressstormwaterquantityandqualityassociatedwithdevelopmentoftheproposedProjectwouldbedefinedinconjunctionwithmeetingLIDOrdinancerequirements.TheoverallBMPprogramfortheProjectwouldbesizedtomeettheLIDspecificationsrelativetoaddressingrunoffvolumesforthe85thpercentilestormevent,whichisapproximately1‐inchin24‐hours.Table5‐6delineatestherunoffvolumeassociatedwiththe85thpercentilestormeventthatwouldneedtobeaddressedintheBMPprogramforeachProjectcomponent.AsnotedaboveinSection2.2.4,theSUSMPrequiresthatredevelopmentprojectsthatcreate,add,orreplace5,000squarefeetormoreofimperviousareaonanalreadydevelopedsitearesubjecttothesameconditionsasnewdevelopmentprojects.Assuch,thewaterqualityvolumespresentedinTable5‐6aredeterminedbyassumingallnewdevelopmentis100%imperviousandtheentirefootprintmustbeaccountedfor;newroadwaysandAPMguidewayareasarebrokenoutfromaggregateddrainageareasandincludedseparatelyinthiscalculation.

Table 5-6: Runoff Volume for the 85th Percentile Storm

Project Component  Total Area (acres)  Volume to be Mitigated (ft3) 

ConRAC  67  220,000 

ITF East  21  70,000 

ITF West  14  45,000 

APM Maintenance and Storage Facility  

2.2  7,000 

Roads  39  130,000 

APM Guideway  16.5  54,000 

Roads near South Airfield  1.7  5,600 

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5‐10     

5.2.1.2 Project Design Features 

TheproposedundergroundcisternsbeneaththeConRACfacility,introducedinSection5.1.2,aresizedtohold500,000ft3,avolumemorethantwicetheamountneededtoaddressthewaterqualitytreatmentvolumeof220,000ft3associatedwiththatProjectcomponent.Cisternwaterwouldbetreatedandusedforcarwashingon‐site;suchreuseofstormwaterisconsistentwithgoodwaterqualitymanagementpracticesandwouldmeetLIDrequirements.

5.2.2 Stormwater Flows AsdescribedaboveinSection5.2.1,implementationoftheproposedProjectwouldresultinincreasedpollutantflowsinstormwaterrunoff.ThedesignoftheproposedConRACfacilityincludestheuseofundergroundcisternsthatcollect,store,andsupporton‐sitereuseofstormwater,whichwouldmeetLIDrequirementsandfullyaddressthestormwaterqualityimpactsassociatedwiththatProjectcomponent.ThewaterqualityimpactsoftheConRACwouldbelessthansignificantbecausepollution,contaminationornuisanceasdefinedinSection13050oftheCWCorviolationofregulatorystandardsasdefinedintheapplicableNPDESstormwaterpermitorWaterQualityControlPlanforreceivingwaterbodywouldbeminimized..

SpecificwaterqualityBMPswouldbeidentifiedduringmoredetailedprojectplanninganddesignfortheothercomponents,inconjunctionwithmeetingLIDrequirements;however,inthecurrentabsenceofsuchdesignfeaturesforthoseothercomponents,thestormwaterqualityimpactsassociatedwiththoseaspectsoftheProjectareconsideredtobesignificant.Section6belowidentifiesmitigationmeasuresforthoseimpacts.

5.2.3 Dry Weather Flows ProjectedsourcesofdryweatherflowswithintheProjectareaareassociatedwithactivitiesthatincludeoutdoorcleaningandmaintenanceofrentalvehicles;maintenanceoftheAPMsystemandequipment;andbuildingandgroundsmaintenance.TheseactivitiescouldpotentiallyresultinreleaseofspillsandleaksofhazardousmaterialstotheDominguezChannelwatersheds.Compliancewithexistingregulationsandairportprocedures,particularlytheLAXSWPPPwhichwouldbeupdatedtoincludethenewfacilities,wouldreducethelikelihoodofanydryweatherdischargesandthepotentialimpactsassociatedwithhazardousmaterialsspills.Withsuchcontinuedcompliance,thepollutantloadgeneratedfromdryweatherflowswouldnotincreaseandtheassociatedimpactswouldbelessthansignificantbecausepollution,contaminationornuisanceasdefinedinSection13050oftheCWCorviolationofregulatorystandardsasdefinedintheapplicableNPDESstormwaterpermitorWaterQualityControlPlanforreceivingwaterbodywouldbeminimized..

5.2.4 Construction Runoff ConstructionoftheproposedProjectfacilitiesmaygeneratepollutantsourcesthatadverselyaffectwaterquality,includingerosion‐inducedsediments,nutrients,tracemetals,toxicchemicals,andconstructionwaste.BecauseimprovementsundertheproposedProjectwouldaffectanareagreaterthanone‐acre,LAWA'sexistingconstructionpolicywouldrequirethedevelopmentofproject‐specificconstructionSWPPPsincompliancewiththeState'sGeneralConstructionPermit.TemporaryconstructionBMPsthatwouldlikelybeconsideredandincorporatedintoeachproject‐specificSWPPP,asappropriate,wouldinclude:

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5‐11 

Soilstabilization(erosioncontrol)techniquessuchasseedingandplanting,mulching,andcheckdams

Sedimentcontrolmethodssuchasdetentionbasins,siltfences,anddustcontrol

Contractortrainingprograms

Materialtransferpractices

Wastemanagementpracticessuchasprovidingdesignatedstorageareasandcontainersforspecificwasteforregularcollection

Roadwaycleaning/trackingcontrolpractices

Vehicleandequipmentcleaningandmaintenancepractices

Fuelingpractices

ByfollowingtheproceduresoutlinedintheSWPPPandemployingtheappropriateBMPsfromthelistaboveandanyadditionalBMPsrequiredinproject‐specificconstructionSWPPPs,impactstowaterqualityassociatedwithconstructionactivitieswouldbelessthansignificantbecausepollution,contaminationornuisanceasdefinedinSection13050oftheCWCorviolationofregulatorystandardsasdefinedintheapplicableNPDESstormwaterpermitorWaterQualityControlPlanforreceivingwaterbodywouldbeminimized..

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5‐12     

Thispageintentionallyleftblank.

    

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Section 6  Mitigation Measures 

6‐1 

Section 6   

Mitigation Measures and Design Features  

ProjectimpactsandproposeddesignfeatureswerediscussedinSection5.Designfeatureshavenotbeenproposedforallprojectelements,andmitigationmeasuresdiscussedinthissectionprovideabasisforreducingthehydrologyimpactstolevelsthatarelessthansignificant.

6.1 Drainage Mitigation Measures  Potentialdrainage(flooding)impactsduringthe10‐yearstormthatresultfromtheproposedProjectwouldbemitigatedinoneoffollowingthreeways,orsomecombinationthereof:

1. DetainorreduceonsiteProject‐relatedflowsinordertomaintainexisting(pre‐Project)downstreampeakdepths;

2. Re‐routeflowsthroughabypassdrain,orconnectanewstormdraintothelargerstormdrain;or

3. Constructimprovementstotheexistingstormwaterdrainagesystemsegments/facilitieswheredeficienciesexist.

Thefollowingidentifiespotentialoptionsforeachofthesethreewaystoreduceimpacts,recognizingthattheselectionandrefinementofaparticularoptionforimplementationwouldbedeterminedinconjunctionwiththemoredetailedplanning,design,andpermittingofeachProjectcomponent.

6.1.1  Detain/Reduce Project‐Related Stormwater Flows Thestoragevolumesneededtomaintainpre‐projectdownstreampeakdepthsforthe10‐yearstormareportrayedinTable6‐1.Projectdesignfeaturevolumesassociatedwitheachfacilityareshown,andTable6‐1indicatesthattheConRACcisternsreducetheamountofremaining10‐yearstormvolumetobemitigated.

Table 6-1: 10-year Storm Mitigation Volumes

Component Detention Volume Required (ft3) 

Project Design Feature Volume (ft3) 

Remaining Volume to be Mitigated (ft3) 

Manchester Square  571,000  500,000  71,000 

East ITF  200,000  0  200,000 

West ITF  94,000  0  94,000 

APM Maintenance Facility  23,000  0  23,000 

Roads near South Airfield  0  0  0 

Atotalvolumeof571,000ft3isrequiredtofullymitigateimpactsforthe10‐yearstormfortheConRAC.The500,000ft3cisternstorageincorporatedintothefacilitydesignalleviatessomeof

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Section 6  Mitigation Measures 

6‐2 

theimpacts,butanadditional40,000ft3ofdetentioninthenorthand31,000ft3inthesouthisneeded.

Inadditiontotheoptionofon‐sitedetentionofstormwater,above‐grademeasurestoreducedrainageimpactsincludedecreasingtheimperviousareaofadevelopmentand/ordivertingrunoffwatertoperviousareas.AsfurtherdescribedbelowinSection6.2,potentialoptionsforwaterqualityBMPsinclude,butarenotlimitedto,biofiltration,infiltration,evapotransporation,andvariouswaterqualitystructuraltreatmentsystems,allofwhichcanalsoservicetoreducepeakflowsfromtheProjectandmitigatedrainage/floodingimpacts.

6.1.2  Reroute Stormwater Flows InconjunctionwithmoredetailedengineeringanddesignofdrainageinfrastructureimprovementsassociatedwiththeProjectcomponents,moredetailedevaluationsoftherunoffcharacteristicsofeachcomponentrelativetothereceivingstormdrainlinescanbeconductedtoassessthepotentialforreroutingflows,eitherbymodifyingexistingorproposedsurfaceelevationsanddirectionsoffloworbyinstallationofnewstormdrainlinesonsitetocarryrunofftoexistingstormdrainthathavesufficientdownstreamcapacity.

6.1.3  Construct Improvements to Existing Stormwater Drainage System Aspartofthedetailedplanninganddesignoftheproposedfacilities,LAWAwouldevaluateandidentifyimprovementstosegmentsoflocalstormdrainsystemshavingexistingorfuturepeakflowsthatexceedthedesigncapacityofthefacilities.AsapartoftheproposedProject,LAWAwouldconstruct,orsupportonafair‐sharebasis,improvementsneededtoaddressexistingorfuturedeficienciesandaccommodatestormwaterattributabletotheProject.

InaddressingtheexistingdownstreamdrainagedeficienciesattheDominguezChanneloutlet,whichisaCountyregionalfacility,LAWAwouldworkincoordinationwiththeCountyandotheraffectedjurisdictionsinthedevelopmentofacomprehensivesolutiontothatdeficiency,understandingthatLAWA’sparticipationinimplementingsuchasolutionwouldneedtobeonafair‐sharebasisinlightoftheProject’scontributiontoincreasedflows.Table6‐2outlinesmeasuresthatLAWAcouldimplementtomitigatethesignificantimpactsoftheproposedProjectonexistingdrainagedeficienciesidentifiedinSection3.3.3.

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Section 6  Mitigation Measures 

6‐1 

Table 6-2: Potential Drainage Improvement Options

Capacity Restriction 

Design Storm for which Restriction Occurs 

Proposed Solution 

Section along 96th street and Airport Boulevard, and 

Century Boulevard storm drain1 

10‐yr  Approximately 6,100 LF of replacement storm drains would be coordinated with roadway improvements for the proposed Project facilities. These upgraded storm drains are recommended along Westchester Pkwy.,  Airport Blvd., and 96th Street. 

La Cienega between 104th and 111th street for the Project 13 

conduit2 

50‐yr  FAA, LACDPW, and City of Los Angeles design criteria require that storm 

drains provide flood protection capacity for the 10‐year storm event. 

Table 5‐2 lists the volume of  stormwater detention that would be 

required in order to maintain the pre‐project downstream peak depths 

for the 10‐year design storm. By installing these detention volumes on‐

site, the proposed Project components are not expected to increase 

flooding along the Project 13 Conduit. 

 

The capital flood protection level requires that Dominguez Channel has 

the capacity to convey runoff from a 50‐year storm frequency, proposed 

Project facilities are not expected to increase peak flows in to Dominguez 

Channel. However, LAWA would support any additional detention or 

additional storm drain installation on a fair‐share basis.

Source: 1CDP, 2005; 2PB, 2002 

ThroughimplementationofoneormoreoftheaboveoptionsforaddressingincreasedflowsassociatedwiththeproposedProject,withtheresultbeingtoavoidanincreaseinrunoffthatwouldcauseorexacerbatefloodingwiththepotentialtoharmpeople,damageproperty,orexceedthecapacityofexistingorplannedstormwaterdrainagesystems,thehydrologyimpactsoftheprojectwouldbereducedtolessthansignificant.

6.2 Water Quality Design Features AspartoftheproposedProjectduringtheplanninganddesignoftheproposedProjectfacilities,LAWAwouldselectandsizewaterqualityprotectionfeaturesthatmeettherequirementsoftheLIDOrdinanceandtheNPDESPermit.PrioritywillbegiventoLIDBMPs.TheLosAngelesLIDManualprovidesrequirementsandguidancefortheselectionandsizingofBMP’sforagivenstormvolumegivenuserinputparameterssuchassoilporosity,depthofinfiltrationallowed,andthepondingtime.ThesesizingmethodsarecombinedwithresearchdonetoestablishthepollutantremovalefficacyofmanyBMPtypes.Overthepast10years,lowimpactdevelopmentBMPshavebeenimplementedforstormwatermanagementandwaterpollutioncontrol.LIDconsistsofbestmanagementpracticesthataimtoreducetheimpactsofincreasesinstormwaterrunoffthroughtheuseofnaturalandstructuralsystemsforinfiltration,evapotranspiration,andretention.SeveralBMPsarelistedinTable6‐3alongwithpollutantremovalefficienciesbasedonscientificreportsfromfederalandlocalagencies(EWMP,2015).Infiltration‐basedBMPsandevapotranspiration(orotherreuse)BMPs,foraneventequivalenttothe85thpercentilestorm,wouldremove100percentofallpollutantsinthefractionofrunoffdetained.ForotherLID‐basedBMPsandotherBMPs,lessthan100percentofpollutantsareremoved.However,thevaluesin

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Section 6  Mitigation Measures 

6‐2 

Table6‐3showthatovertimeforavarietyofstormevents,thepercentremovedcanfallbelow100percent.

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Section 6  M

itigation M

easures  

6‐3 

Tabl

e 6-

3: T

ypic

al P

ollu

tant

Rem

oval

for

BM

Ps (p

erce

nt)

 BMP Category 

BMP Type 

Total Suspen

ded 

Solid

s Nitrogen 

Phosphorus  

Total Cu 

Total Zn 

Total 

PB 

Oil an

Grease 

Source of Data1 

A

B

A

B

A

B

A

B

A

B

A

A

LID Biofiltration 

BMPs 

Biosw

ales 

49 

  30 

  ‐106 

  63 

  77 

  68 

  

Biofiltration Strip 

69 

  ‐10 

  ‐46 

  85 

  72 

  88 

  

Bioretention 

  59 

  46 

  5 

  81 

  79 

    

Wetlands 

  72 

  24 

  48 

  47 

  42 

    

LID Infiltration 

BMPs 

Infiltration  

  89 

  42 

  65 

  86 

  66 

    

Surface Sand Filters 

81‐90 

  9‐32 

  39‐44 

  50‐66 

  80‐92 

  85‐87 

  

LID 

Evapotranspiration 

BMPs 

Extended

 Detention 

Basins (Unlined

) 72 

  14 

  39 

  58 

  73 

  72 

  

Extended

 Detention 

Basins (Lined

) 40 

  14 

  15 

  27 

  54 

  30 

  

Wet Basin Storm

 (Wet 

Weather) 

94 

  51 

  5 

  89 

  91 

  98 

  

Wet Basin Base Flow 

(Wet Weather) 

21 

  43 

  49 

  54 

  62 

  62 

  

Wet Pond 

  80 

  31 

  52 

  57 

  64 

    

Dry Pond 

  49 

  24 

  20 

  29 

  29 

    

Other BMPs 

Multi‐Cham

bered 

Treatm

ent Train 

75 

  0 

  18 

  35 

  75 

  74 

  

Inlet Insert 

3‐14 

    

    

  0‐2 

  1‐2 

  1‐7 

  

Continuous Deflective 

Separators (CDS) 

  5 

  15 

  8 

  17 

  11 

  

Oil Water Sep

arator 

49 

    

    

  2 

  2 

  7 

89 

1 DatasourceAwasextractedfrom

theCaltransBMPRetrofitPilotProgram

;Breferstodatafrom

theCenterforWatershedProtection

Source:EWMP(2015).

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7‐1 

TheselectionanddesignofBMPswoulddeterminethepercentpollutantremoval,whichinturnaffectsthepollutantloaddischargedtothereceivingwaterbodies.VariousstudieshaveproposeddifferenttypesofBMP’sfortheproposedProjectarea.HighconcentrationsofzincareaffiliatedwithstormwaterrunoffintheDominguezChannelarea,andgreenstreetswereproposed,inthe2015EWMP,inthegeneralareaoftheproposedProjectfacilities.Inaddition,theConceptualDesignPlan(CDP;LAWA,2005)preparedforLAWAtosupporttheoriginalMasterPlanidentifiedseveralBMPoptionsfortheDominguezChannelNorthdrainageareabasedonsite‐specificwatershedcharacteristicsincludingvegetatedswalesandbioretentionforareaparkinglotsandITFareas.

Table6‐4presentsthewaterqualityvolumerequirements.. ForallProjectcomponents,LIDBMPsofadequatesize,orcaptureandreusealternatives,wouldbeincorporatedtoaddressthevolumesshowninTable6‐4.

Table 6-4 Volume Requirements for On-site Alternatives

LAMP Component Water Quality 

Requirement (ft3) Project Design Feature 

Volume (ft3) Remaining Volume (ft3) 

CONRAC  220,000  500,000  0 

ITF East  70,000  0  70,000 

ITF West  45,000  0  45,000 

APM Maintenance Facility  7,000  0  7,000 

APM Track (entire length)  54,000  0  54,000 

New Roadways  130,000  0  130,000 

APMtrackandproposedroadwaysarebeingdesignedwithnewstorm‐drainstosufficientlyattenuateflowsinordertomaintainpeakflowdepthsfurtherdownstream.However,boththetrackandroadswouldalsoincludewaterqualitymeasuresaslistedinTable6‐4.

Tocaptureandinfiltrate,reuseorbiotreattheremainingvolumefortheManchesterSquarearea,additionalLIDBMPswouldberequired.ForallotherProjectcomponents,LIDBMPswouldbeincorporatedofsufficientsizetoaddressthevolumesshowninTable6‐4.BMPswouldbeevaluatedandselectedfromthoseidentifiedintheLIDManualorotherequivalentBMPs.ThelistofBMPsmayinclude:

Infiltrationbasins

Infiltrationtrenches

Permeablepavementswithanunderdrain

Permeablepavementswithoutanunderdrain

Bioretention

Bioretentionwithunderdrain

Drywells

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Section 7  References 

7‐2     

Planterboxes

Bioinfiltration

Vegetatedswalesandstrips

Wetponds

Constructedwetlands

Sandfilters

Extendeddetentionbasins

ImplementingBMPsassetforthintheLIDOrdinance,withthespecificsoftheBMPsassociatedwitheachProjectcomponenttobedefinedinconjunctionwiththedetailedplanning,design,engineering,andpermitting,particularlytheLID/SUSMPcomplianceprocess,wouldassurethepotentialwaterqualityimpactsassociatedwithdevelopmentofproposedProjectwouldbelessthansignificantbecausepollution,contaminationornuisanceasdefinedinSection13050oftheCWCorviolationofregulatorystandardsasdefinedintheapplicableNPDESstormwaterpermitorWaterQualityControlPlanforreceivingwaterbodywouldbeminimized.

ItshouldbenotedthatwhiletheabovediscussionpertainstothemitigationneedsandpotentialoptionsassociatedwiththeproposedLAMPfacilities,asmayoccurinconjunctionwithdevelopmentofeachofthosefacilities,LAWAhasinitiateddevelopmentofacampus‐wide(i.e.,LAXandassociatedLAWA‐ownedproperties)StormwaterManagementPlan,asindicatedaboveinSection1.1.ThatStormwaterManagementPlanwilltakeintoaccounttheproposedLAMPProjectfacilitiesandinfrastructure.WhilecertainBMPsareconceptuallyidentifiedintheframeworkofthecampus‐wideStormwaterManagementPlan,theyarenotformallylocatedordefinedyet,asamoredetailedanalysiswillbecompletedduringfacilityplanninganddesigninconcertwiththedevelopmentofthecampus‐wideStormwaterManagementPlan.Assuch,otherpotentialoptionsforaddressingthehydrologyandwaterqualityimpactsassociatedwiththeLAMPProjectmaybeidentifiedaspartofalarger,morecomprehensivedrainageandwaterqualitymanagementprogram,beyondthosepresentedabove.

6.3 Summary of Volume Requirements for On‐Site Mitigation 

Table6‐5summarizesthevolumeofstormwaterthatwouldrequiremanagementinordertomeetthewaterqualitytreatmentrequirementforeachLAMPfacility,aswellastheadditionalon‐siterunoffstorage/detentionthatwouldbeneededasamitigationmeasureinordertofullymitigatepeakrunoffdepthdownstreamforthe10‐yearstormevent.AsdescribedaboveinSection6.1,itisalsopossiblethatmitigationofhydrologyimpactscanoccurthroughotheroptionsthatmayoccuroffsite.

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Table 6-5 Volume Requirements for On-site Alternatives

LAMP Component Water Quality Requirement 

Additional Drainage Requirement 

Total 

CONRAC  220,000 ft3  351,000 ft3  571,000 ft3 

ITF East  70,000 ft3  130,000 ft3  200,000 ft3 

ITF West  45,000 ft3  49,000 ft3  94,000 ft3 

APM Maintenance Facility  7,000 ft3  16,000 ft3  23,000 ft3 

APM Track (entire length)  54,000 ft3  New Storm Drains  54,000 ft3 

New Roadways  130,000 ft3  New Storm Drains  130,000 ft3 

LAWAcouldcompleteacampus‐wideStormwaterManagementPlanthatincorporatestheproposedProjectfacilitiesandinfrastructure.WhilecertainBMPsareconceptuallyidentifiedinthisdocument,theyarenotformallylocatedasamoredetailedanalysiswillbecompletedduringfacilityplanninganddesigninconcertwiththedevelopmentofthecampus‐wideSMP.

Section 7   

References 

CaliforniaDepartmentofWaterResources.DWR.2015.BestAvailableMaps.http://gis.bam.water.ca.gov/bam/

CaliforniaRegionalWaterQualityControlBoard.(1994).WaterQualityControlPlanLosAngelesRegion:BasinPlanfortheCoastalWatershedsofLosAngelesandVenturaCounties.Availableat:http://www.waterboards.ca.gov/losangeles/water_issues/programs/basin_plan/basin_plan_documentation.shtml

CampDresser&McKeeInc.2001.HydrologyandWaterQualityTechnicalReport,LAXMasterPlanEIS/EIR.

CDMSmithinassociationwithVCAEngineers,Inc.,2015.LAXStormwaterManagementPlanExistingConditionsAssessment.

CityofLosAngeles.2006.L.A.CEQAThresholdGuide:YourResourceforPreparingCEQAAnalysesinLosAngeles.Availableat:<http://www.environmentla.org/programs/Thresholds/Complete%20Threshold%20Guide%202006.pdf>

CityofLosAngeles.2011.DevelopmentBestManagementPracticesHandbook,LowImpactDevelopmentManual,PartB.

CityofLosAngeles.2013.FinalLAXSpecificPlanAmendmentStudyReportforLosAngelesInternationalAirport(LAX)SpecificPlanAmendmentStudy.Availableat:

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Section 7  References 

7‐4     

<http://www.lawa.org/uploadedFiles/SPAS/PDF/LAX%20SPAS%20Final%20SPAS%20Report%20Document%20Final%20CD‐Web%20Version%2001%2030%202013.pdf>

CityofLosAngeles,LosAngelesWorldAirports,LAXLandsideAccessModernizationProgramDraftEIRNoticeofPreparation/InitialStudy.February5,2015.Available:http://connectinglax.com/files/LAX.LAMP.Initial.Study_2015.pdf

CityofLosAngelesBureauofEngineering.1973.StormDrainDesignManual‐PartG.Availableat:<http://eng.lacity.org/techdocs/stormdr/Index.htm>[Dateaccessed:October28,2015]

CountyofLosAngelesDepartmentofPublicWorks.2014.LowImpactDevelopmentStandardsManual.Availableat:<https://dpw.lacounty.gov/ldd/lib/fp/Hydrology/Low%20Impact%20Development%20Standards%20Manual.pdf>

CTC&AssociatesLLC.2007.GrassSwales:GaugingTheirAbilitytoRemovePollutantsfromHighwayStormwaterRunoff.WisconsinDepartmentofTransportation.

DominguezChannelWatershedManagementAreaGroup.2015.EnhancedWatershedManagementProgram.

LosAngelesDepartmentofPublicWorks(LADPW).2014.GuidelinesforDesign,Investigation,andReportingLowImpactDevelopmentStormwaterInfiltration.Availableat:<http://ladpw.org/gmed/permits/docs/policies/GS200.1.pdf>

LosAngelesWorldAirports(LAWA).1996.HydrologyandWaterQuality.Availableat:<http://www.lawa.org/uploadedFiles/OurLAX/Past_Projects_and_Studies/Past_Publications/FEIS_EIR_Part1‐17_0407_HydrologyandWaterQuality.pdf>

LosAngelesInternationalAirport(LAWA).2005.SouthAirfieldImprovementProjectDraftEnvironmentalImpactReport(DraftEIR).

LosAngelesInternationalAirport(LAWA).SPASDraftEIR,Section4.8HydrologyandWaterQuality.Availableat:<http://www.lawa.org/uploadedfiles/spas/pdf/SPAS%20DRAFT%20EIR/LAX%20SPAS%20DEIR%2004.08%20Hydrology%20Water%20Quality.pdf>[Dateaccessed:October28,2015]

LosAngelesCountyDepartmentofPublicWorksHydrologyManual.2006.Availableat:<http://dpw.lacounty.gov/wrd/publication/engineering/2006_Hydrology_Manual/2006%20Hydrology%20Manual‐Divided.pdf>

NPDESStormWaterProgram.1993.(http://www3.epa.gov/npdes/pubs/owm0250.pdf)

ParsonsBrinckerhoffQuadeDouglas,Inc.2002.FinalOn‐siteHydrologyReportforLosAngelesInternationalAirport.

StateWaterResourcesBoardofCalifornia(2000).StandardUrbanStormWaterMitigationPlanforLosAngelesCountyandCitiesinLosAngelesCounty(SUSMP).Availableat:

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G‐5 

http://www.swrcb.ca.gov/losangeles/water_issues/programs/stormwater/susmp/susmp_rbfinal.pdf

TMDLsfromUSEPA:

http://iaspub.epa.gov/tmdl_waters10/attains_waterbody.control?p_list_id=CAE4051200020050203154519&p_cycle=9999&p_report_type=#tmdls

http://iaspub.epa.gov/tmdl_waters10/attains_waterbody.control?p_list_id=CAR4051200019980918161017&p_cycle=2012&p_report_type=#tmdls

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