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CityofLosAngeles IV.G‐1 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
IV.G SURFACE WATER HYDROLOGY, SURFACE WATER QUALITY, AND GROUNDWATER
1. INTRODUCTION
This section describes the potential impacts of the proposed Barlow Replacement Hospital and
Master Plan Project on surface hydrology and water quality on the Project site and in the
surroundingarea.ThissectionincorporatesandsummarizesinformationcontainedintheBarlow
Replacement Hospital & Master Plan Hydrology technical report prepared by KPFF Consulting
Engineers(December2010).AcopyofthereportisprovidedinAppendixIV.GofthisDraftEIR.
2. REGULATORY SETTING
a. Federal Regulations
i. Clean Water Act
TheCleanWaterAct,formerlyknownastheFederalWaterPollutionControlAct,wasestablished
in1948andamendedinthe1960s,1970s,andthe1980s.TheActistheprimaryregulationatthe
national level for the management of water quality, and its chief goal is the restoration and
maintenanceofthechemical,physical,andbiologicalintegrityofthenation’swaters.Accordingly,
the Act sets forth objectives for themanagement ofwater quality that include the regulation of
pollutants and toxic pollutants discharges; ensuring water quality that protects and fosters the
propagationoffish,shellfish,andwildlife;developingwastetreatmentmanagementprograms;and
developingandimplementingprogramsforthecontrolofnon‐pointsourcesofpollution.
Amendments to theAct in1972established theNationalPollutantDischargeEliminationSystem
(NPDES)permitprogram,whichprohibitsdischargeofpollutantsintothenation’swaterswithout
procurement of a NPDES permit from the U.S. Environmental Protection Agency (U.S. EPA).
Although federallymandated, the NPDES permit program is generally administered at the State
level. As discussed below under the Porter CologneWater Quality Control Act, in California, the
State delegates authority for implementation of the NPDES permit program to its nine Regional
Water Quality Control Boards (RWQCBs). With the 1977 amendment requiring State‐level
developmentofBestManagementPractice(BMP)programs,theActbecamecommonlyknownas
theCleanWaterAct(CWA).
TheWaterQualityActof1987addedSection402(p) to theCWA,whichdirected theU.S.EPA to
establish requirements for stormwater discharges from municipal and industrial sources. In
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐2 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
responsetothe1987amendment,PhaseIoftheU.S.EPA’sNPDESProgramrequirespermitsforthe
following:
1. Municipalseparatestormsewersystemsgenerallyserving,orlocatedin,incorporatedcities
with100,000ormorepeople(referredtoasMS4permits);
2. Elevenspecificcategoriesofindustrialactivity(includinglandfills);and
3. Constructionactivitythatdisturbs5acresormoreofland.
InMarch2003,PhaseIIoftheNPDESProgramextendedrequirementsforpermitstothefollowing:
1. Numeroussmallmunicipalseparatestormsewersystems;
2. Constructionsitesbetween1and5acres;and
3. Industrial facilitiesownedoroperatedbysmallmunicipal separatestormsewersystems,
whichwerepreviouslyexemptedfromstormwaterpermitting.
Section 402 (p) of the CleanWater Act mandates that Municipal Separate Storm Sewer System
(MS4)permitsmust (1) effectivelyprohibit thedischargesof non‐stormwater to the stormwater
system, except under certain circumstances; and (2) require controls to reduce pollutants in
discharges from the stormwater system to the maximum extent practicable, including best
managementpractices,controltechniques,andsystem,design,andengineeringmethods.Although
mandated at the federal level, the permits are issued byRWQCBs tomunicipalities or groups of
municipalitiesencompassinglargemetropolitanareas,andpermitrequirementsareimplemented
locallybythosemunicipalities.
ii. National Flood Insurance Act
TheNationalFloodInsuranceActestablishedtheNationalFloodInsuranceProgram,whichisbased
ontheminimalrequirementsforfloodplainmanagementandisdesignedtominimizeflooddamage
withinSpecialFloodHazardAreas.AccordingtotheFederalEmergencyManagementAgencyFlood
InsuranceRateMap, theentireProject site is inanareaofminimal flooding (FloodZoneC), and
thereforedoesnotrequirefloodinsurance.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐3 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
b. State Regulations
i. Porter‐Cologne Water Quality Control Act (California Water Code)
ThePorter‐CologneWaterQualityControlActof1969establishedtheprincipalStateprogramfor
waterqualitymanagementandauthorizestheSWRCBtoimplementtheprovisionsoftheFederal
CleanWaterAct.ThePorter‐CologneActdividedthestateintonineRegionalWaterQualityControl
Board(RWQCB)areasoperatingundertheCaliforniaEnvironmentalProtectionAgency(CalEPA).
EachRWQCBimplementsandenforcesprovisionsof thePorter‐CologneActandtheCleanWater
Act subject topolicy guidanceand reviewby theSWRCB.TheProject site is located inRegion4,
whichisgovernedbytheLosAngelesRegionalWaterQualityControlBoard(LARWQCB).
Section13050ofthePorter‐CologneWaterQualityControlActdefinespollution,contamination,or
nuisance. Pollution is defined as alteration ofwater quality such that it unreasonably affects the
water’sbeneficialuses;contaminationisdefinedasimpairmentofwaterqualitytothedegreethat
itcreatesahazardtopublichealth;andanuisanceisdefinedasanythingthatisinjurioustohealth,
offensivetothesenses,anobstructiontopropertyuse,andwhichaffectsaconsiderablenumberof
people.
c. Local Regulations
i. County of Los Angeles Hydrology Manual
Drainage and flood control in the City of LosAngeles are subject to review and approval by the
BureauofEngineeringoftheCityofLosAngelesDepartmentofPublicWorks(BOE).Stormdrains
withintheCityareconstructedbyboththeCityandtheLosAngelesCountyFloodControlDistrict.
TheCounty’sFloodControlDistrictconstructsandhasjurisdictionoverregional facilitiessuchas
majorstormdrainsandopenfloodcontrolchannels,whiletheCityconstructsandisresponsiblefor
localinterconnectingtributarydrains.TheCountyDepartmentofPublicWorks’HydrologyManual
requiresthatstormdrainsbedesignedfor25‐yearstormevents,andcombinedstormdrain/street
flowsystemsbedesignedfor5‐yearstormevents.Propertiesrequiringsumpstodischargerunoff
arerequiredtobedesignedfora50‐yearstormevent.
DrainageandfloodcontrolstructuresandimprovementswithintheCityaresubjecttoreviewand
approvalbytheCity’sDepartmentofPublicWorks(DPW)andDepartmentofBuildingandSafety
(LADBS). As required by the Department of Public Works, all public storm facilities must be
designedinconformitywiththestandardssetforthbyLosAngelesCounty.TheCity’sDepartment
of Public Works reviews and approves storm drain plans prior to construction. Any proposed
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐4 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
increasesindischargedirectlyintoCountyfacilities,orproposedimprovementstoCountyfacilities,
requireapproval fromtheCounty’sFloodControlDistrictdepartment toensurecompliancewith
theCounty’sMunicipalNPDESPermitrequirements.
ii. National Pollutant Discharge Elimination System (NPDES) Permit
Although federallymandated, responsibility for implementing theNPDESpermitprogramwithin
California is delegated to the State’s nine Regional Water Quality Control Boards (RWQCBs).
Administrationofthepermitprogramisdiscussedbelow.
Construction: Storm Water Pollution Prevention Plan (SWPPP)
The SWRCB adopted a General Permit for StormWater Discharges from Construction Activities
(ConstructionGeneral Permit) in 2004.1 The ConstructionGeneral Permit regulates construction
activityincludingclearing,grading,andexcavationofareas1acreormoreinsizeandprohibitsthe
discharge of materials other than stormwater, authorized non‐stormwater discharges, and all
dischargesthatcontainahazardoussubstance, unlessaseparateNPDESpermithasbeenissued
for thosedischarges. TheConstructionGeneral Permit requires that developers complywith the
followingrequirements:
1. Eliminateorreducenon‐stormwaterdischargestostormdrainsystemsandotherwatersof
theU.S.;
2. Developand implement aSWPPP that specifies theBMPs intended to reducepollution in
stormwater discharges in compliance with Best Available Technology Economically
Achievable/BestConventionalPollutantControlTechnologystandards;and
3. PerforminspectionsandmaintenanceofallBMPs.
ASWPPPismeanttoidentifypotentialsourcesandtypesofpollutantsassociatedwithconstruction
activityandlistBMPsthatwouldprohibitpollutantsfrombeingdischargedfromtheconstruction
siteintothepublicstormdrainsystem.BMPstypicallyaddressstabilizationofconstructionareas,
minimization of erosion during construction, sediment control, control of pollutants from
constructionmaterials, andpost‐construction stormwatermanagement (e.g., theminimization of
impervioussurfacesortreatmentofstormwaterrunoff).TheSWPPPisalsorequiredto includea
discussionoftheproposedprogramtoinspectandmaintainallBMPs.
1 StateWaterResourcesControlBoard,NationalPollutantDischargeEliminationSystem (NPDES)GeneralPermit for
StormWaterDischargesAssociatedwithConstructionActivity(NPDESNo.CAS000002).2004.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐5 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
ToobtaincoverageundertheConstructionGeneralPermit,adeveloperisrequiredtofileaNotice
ofIntent(NOI)withtheappropriateRWQCBandprovideproofoftheNOIpriortoapplyingfora
grading or building permit from the local jurisdiction, and must prepare a State SWPPP that
incorporatestheminimumBMPsrequiredunderthepermitaswellasappropriateproject‐specific
BMPs.TheSWPPPmustbecompletedandcertifiedbythedeveloperandBMPsimplementedprior
to the commencement of construction, andmay requiremodification by a developer during the
courseofconstructionasconditionswarrant.Whenprojectconstructioniscomplete,adeveloperis
requiredtofileaNoticeofTermination(NOT)withtheRWQCBcertifyingthatalltheconditionsof
theConstructionGeneralpermit,includingconditionsnecessaryfortermination,havebeenmet.
Operation: Standard Urban Storm Water Mitigation Plan (SUSMP)
A Municipal NPDES Permit was issued in December 2001 to Los Angeles County and 84
incorporatedpermitteecitieswithintheCounty.ThepermitdefinestheminimumrequiredBMPs
thatmustbeadoptedbythepermitteemunicipalitiesandincludedbydeveloperswithinplansfor
facility operations. To obtain coverage under this permit, a developermust obtain approval of a
project‐specificSUSMPfromtheappropriatepermitteemunicipality.
A SUSMP addresses the discharge of pollutants within stormwater generated following new
constructionorredevelopment.UnderrecentregulationsadoptedbytheLARWQCB,projectsare
requiredtoimplementaSUSMPduringtheoperationallifeofaprojecttoensurethatstormwater
quantity and quality is addressed by incorporating BMPS into project design. This plan defines
water quality design standards to ensure that stormwater runoff is managed for water quality
concerns and to ensure that pollutants carried by stormwater are confined and not delivered to
receivingwaters. ApplicantsarerequiredtoabidebysourcecontrolandtreatmentcontrolBMPs
from the list approved by the LA RWQCB and included in the SUSMP. These measures include
infiltrationofstormwaterintothegroundaswellasfilteringrunoffbeforeitleavesasite.Thiscan
beaccomplishedthroughvariousmeans,includingtheuseofinfiltrationpits,flow‐throughplanter
boxes,hydrodynamicseparators,andcatchbasinfilters.
In combination, these treatment control BMPsmust be sufficiently designed and constructed to
treatorfilterthefirstthree‐quartersofaninchofstormwaterrunofffroma24‐hourstormevent,
andpost‐developmentpeakrunoffratesandvolumescannotexceedpeakrunoffratesandvolumes
ofpre–developmentconditions.
Tomeetpermitrequirements,municipalitiesarerequired to implement theStormWaterQuality
Management Program prepared for the Report of Waste Discharge filed as part of Los Angeles
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐6 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
County’s Municipal NPDES Permit approval process. Pursuant to this program, municipalities
includingtheCityofLosAngelesarerequiredtoconductavarietyofactivities including,butnot
limitedto,thefollowing:
1. Control discharges at commercial/industrial facilities through tracking, inspecting, and
ensuringcomplianceatfacilitiesthatarecriticalsourcesofpollutants;
2. Implementadevelopmentplanningprogramforspecifieddevelopmentprojects;
3. Implement a program to control construction runoff from construction activity at all
constructionsiteswithinitsjurisdiction;and
4. Implementapublicagencyactivitiesprogram.
TheproposedprojectissubjecttoSUSMPrequirementssinceitproposesahousingdevelopmentof
10unitsormoreandaparkinglotof5,000squarefeetormoreofsurfaceareaorwith25ormore
parkingspaces.
iii. City of Los Angeles Stormwater Program
The Watershed Protection Division of the City of Los Angeles Department of Public Works is
responsible for stormwater pollution control throughout the City in compliance with the Los
AngelesCountyMunicipalNPDESPermit.TheWatershedProtectionDivisionadministerstheCity’s
StormwaterProgram,whichhas twomajorcomponents:PollutionAbatementandFloodControl.
The Watershed Protection Division publishes a two‐part handbook that provides guidance to
developersforcompliancewiththeCounty’sMunicipalNPDESpermitthroughtheincorporationof
water quality management into development planning. The Development Best Management
PracticesHandbook, Part A: Construction Activities (3rd edition) reiterates the policies contained
within the Construction General Permit, provides specific minimum BMPs for all construction
activities,andrequiresthepreparationofaSWPPPandthefilingofanNOItocomplywiththeState
NPDES General Construction Permit requirements with the LA RWQCB. TheDevelopmentBest
Management Practices Handbook, Part B: Planning Activities (3rd edition, June 2004) provides
guidance to developers to ensure the post‐construction operation of newly developed and
redeveloped facilities comply with the County’s Municipal Stormwater Permit. The Handbook
assistsdeveloperswiththeselection,design,andincorporationofstormwatersourcecontroland
treatment control BMPs into project design plans, and provides an overview of the City’s plan
reviewandapprovalprocess.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐7 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
The stormwater pollution controls contained in the Handbook are codified in the LAMC as
OrdinanceNo.173,494.CityapprovalofSUSMPBMPsisrequiredpriortotheissuanceofgrading
andbuildingpermitsbytheDepartmentofBuildingandSafety,andtherequirementtoincorporate
stormwater BMPs into the SUSMP is implemented through the City’s plan review and approval
process.Duringthereviewprocess,projectplansandspecificationsarereviewedbyBOSand,ifthe
project is subject to SUSMP requirements (i.e., falls within a SUSMP project category) or site‐
specific stormwater mitigation measures are necessary because of the potential for generating
pollutants, the Watershed Protection Division of the Bureau of Sanitation (BOS) of the City’s
DepartmentofPublicWorksforcompliancewiththeCity’sGeneralPlans,zoningordinances,and
otherapplicablelocalordinancesandcodes,includingstormwatermanagementrequirements.
TheCity’spreferredSUSMP improvement is infiltrationofstormwateron theprojectsitesince it
allowsforgroundwaterrechargeandreducesthevolumeofstormwaterenteringmunicipaldrains.
If project site conditions are not suitable for infiltration, the City requires one of the following
systems to be implemented, in order of City preference: bio‐filtration/retention systems,
stormwatercaptureandreuse,mechanical/hydrodynamicunits,oracombinationthereof.
iv. Water Quality Compliance Master Plan for Urban Runoff
TheWaterQualityComplianceMasterPlan forUrbanRunoff (MasterPlan)wasdevelopedby the
WatershedProtectionDivisionoftheBOS,incollaborationwithstakeholders,inresponsetoa2007
CityCouncilmotionforthedevelopmentofawaterqualitymasterplanaddressingpollutionfrom
urbanrunoffwithintheCity.TheMasterPlanwasadoptedinApril2009.
TheMasterPlanaddresses planning, budgeting, and funding for achieving clean stormwater and
urban runoff. Within its eight chapters, it presents an overview of the status of urban runoff
managementwithin the City. TheMasterPlan identifies the City’s four watersheds; summarizes
water quality conditions in the City’s receiving waters as well as known sources of pollutants;
summarizes regulatory requirements forwater quality; describes BMPs required by the City for
stormwater quality management; and discusses related plans for water quality that are
implemented within the Los Angeles region, particularly TMDL Implementation Plans and
WatershedManagementPlansinLosAngeles.TheWaterQualityComplianceMasterPlanforUrban
Runoffprovidesanimplementationstrategythatincludesthefollowingthreeinitiatives:
• WaterQualityManagementInitiative‐discussesthevarioustechnicalcomponentsthatgo
into developing projects for the Water Quality Management Plans to comply with
stormwaterregulations;
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐8 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
• Citywide Collaboration Initiative – discusses what is needed to revise and develop City
policies,ordinances,andguidelinesforurbandevelopmentandredevelopmenttofocuson
green solutions, Low Impact Development (LID), and stormwater use while increasing
coordinationCitywide;
• OutreachInitiative–discusseshowtheCitywillenhanceoutreachactivitiestoreachtarget
audiences, andestablishmethods toquantify thewaterqualitybenefits achieved through
outreachactivities.
Thefinalchaptersofthereportaddressthecostsandpossiblefundingsourcesforimplementation
oftheseinitiatives.
v. Los Angeles Municipal Code (LAMC)
LAMC Sections 12.40–12.43, Landscape Ordinance
In 1996, Ordinance No. 170,978 amended LAMC Sections 12.40–12.43 to establish consistent
landscape requirements for new projects within the City. Section 12.40 contains general
requirements, including a point system for specific project features and techniques in order to
determine compliance with the ordinance, and defines exemptions from the ordinance. Section
12.41setsminimumstandardsforwaterdeliverysystems(irrigation)tolandscapes.Section12.43
defines the practices addressed by the ordinance, of which two are applicable to stormwater
management. The Heat and Glare Reduction practice states among its purposes the design of
vehicularuseareasthatreducestormwaterrunoffandincreasegroundwaterrecharge;andtheSoil
andWatershedConservationpracticeisintended,amongotherpurposes,toincreasethe“residence
time of precipitation” within a given watershed. Implementation guidelines developed for the
ordinance provide specific features and techniques for incorporation into projects, and include
WaterManagementguidelinesaddressingrunoff,infiltration,andgroundwaterrecharge.
LAMC Section 62.105, Construction “Class B” Permit
Anyproposeddrainageimprovementswithinaroadwayright‐of‐wayorotherpropertyforwhich
theCity is responsible, including theconstructionofnewconnectionsbetweenaproject siteand
theCity’sstormdrainsystem,requirestheapprovalofa“BPermit”(Section62.105,LAMC).Under
theBPermitprocess,plansforstormdrainconstructionormodificationsaresubjecttoreviewand
approvalbytheBureauofEngineeringoftheCityofLosAngelesDepartmentofPublicWorks.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐9 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
LAMC Section 64.70.01, Stormwater and Urban Runoff Pollution Control Ordinance
LAMCSection64.70.01,theStormwaterandUrbanRunoffPollutionControlOrdinance,wasadded
byOrdinanceNo. 172,176 in1998andprohibits thedischargeof unauthorizedpollutants in the
CityofLosAngeles.Theordinanceappliestoalldischargersandplacesofdischargethatdischarge
stormwater or non‐stormwater into any storm drain system or receiving waters. While this
practice is prohibited under the County’s Municipal NPDES Permit, adoption of the ordinance
allowsenforcementbytheDepartmentofPublicWorksaswellasthe levyof fines forviolations.
Theordinanceprohibitsthedischargeofpollutantsbypersonsoperatingorperformingindustrial
orcommercialactivitiesintothestormdrainsystemandreceivingwaters,exceptasauthorizedby
ageneralor separateNPDESpermit;defines illicit, exempt,andconditionallyexemptdischarges;
prohibits the placement or discharge of trash, sewage, hazardousmaterials, and other waste in
stormdrains or receivingwaters, or the accumulation, storage, or disposal of thesematerials in
such away as to contaminate runoff discharged to these facilities; requires control of pollutants
from parking lots; prohibits the creation or use of illicit connections to municipal storm drain
facilities.
LAMC Section 64.72, Stormwater Pollution Control Measures For Development Planning
and Construction Activities
LAMC Section 64.72, Stormwater Pollution Control Measures For Development Planning and
ConstructionActivities,wasaddedbyOrdinance173,494in2000andsetsforthrequirementsfor
construction activities and facility operations of development and redevelopment projects to
complywiththerequirementsof theNPDESpermitSUSMPrequirements,asdefined intheCity’s
DevelopmentBestManagementPracticesHandbook,PartsAandB(ThirdEdition,2004),adoptedby
theBoardofPublicWorks.
vi. City of Los Angeles Low Impact Development Ordinance
InNovember 2011, the City of Los Angeles adopted a City‐wide Low ImpactDevelopment (LID)
ordinancethatamendstheCity’sexistingStormwaterOrdinance(LAMCSectionNos.64.70.01and
64.72, discussed above). In contrast to conventional stormwater management practices, which
focus on conveying runoff off‐site and into storm drains as efficiently as possible and providing
treatmentatawastewatercollectionendpoint,LIDpracticesrequiretheretentionandinfiltration
ofstormwateratthegenerationsourcetopromotenaturalfilteringofwaterbornepollutants.LID
primarily refers tonatural structuralBMPssuchasvegetatedswales, retentionponds,andgreen
roofs,asopposedtomechanicalstructuralBMPssuchaswatertreatmentfacilities.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐10 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
The Citywide LID strategy addresses land development planning as well as storm drain
infrastructure. Toward this end, LID is implemented throughBMPs that fall into four categories:
site planning BMPs, landscape BMPs, building BMPs, and street and alley BMPs. While the LID
ordinance andBMPs contained thereinare compliantwithLosAngelesCountyMunicipalNPDES
Permitrequirementsforstormwatermanagement,thoserequirementsapplyonlytoproposednew
development and redevelopment of a certain size, primarily address stormwater pollution
preventionasopposedtogroundwaterrecharge,andvaryovertimeasthepermitisreissuedevery
fiveyears.TheLIDordinanceprovidesaconsistentsetofBMPsthatareintendedtobeinclusiveof,
and potentially exceed, SUSMP standards, apply to existing as well as new development, and
emphasizenaturaldrainagefeaturesandgroundwaterrechargeinadditiontopollutionprevention
inreceivingwaters.Theordinancerequiresthecaptureandmanagementofthefirstthree‐quarters
of an inchof runoff flowduring stormeventsdefined in theCity’s SUSMPBMPs, throughoneor
more of the City’s preferred SUSMP improvements: on‐site infiltration, capture and reuse,
evapotranspiration,orbiofiltration/biotreatmentBMPs,tothemaximumextentfeasible.
3. EXISTING CONDITIONS
a. Surface Water Hydrology
i. Project Site Drainage and Storm Drain Infrastructure
TheProjectsiteislocatedintheLosAngelesRiverWatershedManagementArea(WMA),oneofthe
largestsuchareasinthecountry,asshowninFigureIV.G‐1,LosAngelesRiverWatershedMap.The
LosAngelesRiveris51mileslonganddrainsawatershedof834squaremiles.
Project sites
Eastern Parcel
TheeasternProjectsiteisapproximately10.6acresandisrelativelyflatwhereithasbeengraded
and developed along StadiumWay,with an elevation differential of approximately 20 feet from
north to south and approximately 85 feet between Stadium Way and the eastern property
boundaryadjacent toDodgerStadium.ElevationsontheeasternProjectsiterange from435 feet
abovemeansealevel(msl)to515feetabovemsl.
TheeasternProject site is currentlydevelopedwith29buildings, including theexistinghospital,
surface parking lots, pedestrianwalkways, and gardens,which are generally concentrated in the
Figure IV.G-1 Los Angeles River Watershed Map
Source: KPFF Consulting Engineers, Barlow Replacement Hospital & Master Plan: Hydrology Technical Report, December 2010.
Not to Scale
N
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐12 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐13 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
areas closest to StadiumWay.Most of the on‐site buildings and infrastructurewere constructed
before1930.
The eastern Project site is divided into two drainage subareas, DA1‐2 and DA2‐3, as shown in
Figure IV.G‐2, Project Site: Existing Drainage Subareas. Subarea DA2‐3 encompasses a 6.0‐acre
portionof theeasternProjectsitenear the intersectionofStadiumWayandScottAvenue.There
arenoconstructedstormwaterconveyancesystemsordrainagestructureswithinthissubareaand
all runoff is conveyeddownslopevia surface (sheet) flow followingexisting topographyand into
thegutterwithinStadiumWay.Flowsareconveyedsouthbytheguttertothelowestpointwithin
StadiumWay, justwestoftheon‐sitelibrary,wheretheyentertheundergroundmunicipalstorm
drain via 36‐foot‐wide and 38‐foot‐wide curb inlets leading to underground catch basins. These
catchbasinsrepresenttheProjectsite’sinitial“infallpoint”tothemunicipalstormdrain,a60‐inch
reinforcedclaypipe(RCP)beneathStadiumWaythatbeginsmidwaybetweenBoylstonStreetand
Scott Avenue. The Project site is Subarea DA2‐3 encompasses the remaining 9.3 acres on the
easternProject site. In addition to runoff generatedby rainfall directlyonto theProject site, this
subareareceives“run‐on”–surfaceflowfromoff‐site–froma19.8‐acreareanorthofScottAvenue,
showninFigureIV.G‐3,ProjectSite:ExistingStormDrainInfrastructure,assubareaDA1‐1.Subarea
DA1‐1 encompasses theBoylston Street residential neighborhoodaswell as aportionofElysian
Park (MontecillodeLeoPolitiPark).Stormwater flowsgeneratedby thisoff‐site subareaentera
storm drain culvert that passes beneath Scott Avenue and are discharged onto the Project site
througha24‐inch“outfall”indicatedbyaheadwallnearthenorthern‐centralpropertyline.Run‐on
from this off‐site subarea, togetherwith runoff generated on theProject site’s subareaDA1‐2, is
conveyeddownslopeandsouthviasurfaceflowuntilenteringtheon‐sitestormdrainsysteminthe
southernendoftheeasternProjectsite.Surfaceflowsareinterceptedbyfouron‐sitecatchbasins
located near Building No. 6 (Shipping and Receiving), just south of Building 19 (former patient
cottage),andwithinthehospital’ssouthernparkinglot.AllrunofffromsubareasDA1‐2andoff‐site
subareaDA1‐2 is eventually collectedwithin a 48‐foot catchment basin/sumpnear the southern
endoftheeasternProjectsite, justnorthofthe intersectionofStadiumWayandBoylstonStreet.
Runoff is then conveyed from the sump/catch basin via a 54‐inchRCP stormdrain to a 75‐inch
segmentoftheRCPmunicipalstormdrainbeneathStadiumWay.
AscanbeseeninthemapcontoursinFigureIV.G‐3,previouslyreferenced,overtimethevolume
andvelocityof stormwater flowsacross subareaDA2‐3have resulted in the creationof a broad,
curvingswalethatextendsfromtheheadwalloutfallwhereoff‐siterun‐onenterstheProjectsite,
nearScottAvenue,allthewaytothe48‐footcatchbasin/sumpatthesouthernendoftheeastern
Projectsite.Theswalehasbeencreatedbytheerosionofsoilaswellasunderlyingbedrock.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐14 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
Western Parcel
ThewesternProjectsite,approximately14.2acres,slopessteeplyupfromStadiumWaytoElysian
ParkDrive,withelevationsrangingfromapproximately435feetabovemslto572feetabovemsl.It
contains10buildings, includingeightcottagesat thebottomof theslopealongStadiumWayand
two single‐family residences at the top of the slope on Elysian Park Drive. The majority of the
westernProjectsiteisundevelopedandvegetationconsistsofnonnativegrasses(regularlydisked
forfirepreventionpurposes),shrubs,andmaturetrees.
ThewesternProjectsiteisdividedintotwodrainagesubareas,DA4‐1andDA3‐4.SubareaDA4‐1
comprises4.2acresatthesouthernendofthewesternProjectsiteandsubareaDA3‐4comprises
theremainderof theProject site, approximately11.6acres.SubareaDA3‐4receives run‐on from
1.4 acres of off‐site land to the north, subarea DA3‐3; these flows enter the Project site at its
northwestcorner.
Unlike the eastern Project site, there are no constructed runoff conveyance systems or drainage
structuresonthewesternProjectsite.Allrunoffisconveyeddownslopeviasheetflowtothegutter
inStadiumWay.RunofffromsubareaDA4‐1isconveyedsouthtoa36‐footcurbinletcatchbasinon
thewest sideof StadiumWay, at its lowestpoint, across from the36‐foot curb inlet catchbasin
servingtheeasternProjectsite.RunofffromsubareaDA3‐4drainstoa40‐footcurbinletandcatch
basininStadiumWay,about200feetnorthofthedrainagestructureservingsubareaDA4‐1.
ii. Project Site Hydrological Conditions
Table IV.G‐1, Summary of Existing Hydrologic Analysis Results, provides a summary of runoff
volumesfor1)Projectsitedrainagesubareas,2)off‐sitedrainagesubareasthatcontributerun‐on
totheProjectsite,and3)off‐sitedrainagesubareasthatcontributerunofftothemunicipalstorm
drain system beneath Stadium Way. Runoff volumes were calculated based on the City of Los
AngelesDepartmentofPublicWorksPeakRateMethod.Thecalculationsperformedforthistable
indicate that the majority of stormwater runoff from the Project and surrounding drainage
subareas is conveyed as runoff into the municipal storm drain system, with the remainder, a
relatively small proportion of the overall runoff volumes, percolating into the ground. The
municipalstormdrainsystemservingtheProjectsite,includinginfall/outfallstructuresandstorm
waterconveyancepipes,areadequatelysizedtoconveythepeakrunoffratesgeneratedbyupto
50‐year design storm events, and are therefore considered adequate to prevent flooding during
stormsofthisfrequency.
Figure IV.G-2Project Site: Existing Drainage Subareas
Source: KPFF Consulting Engineers, Barlow Replacement Hospital & Master Plan: Hydrology Technical Report, December 2010.
LEGEND
0 300 600
Scale (Feet)
N
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐16 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
Figure IV.G-3 Project Site: Existing Storm Drain Infrastructure
Source: KPFF Consulting Engineers, Barlow Replacement Hospital & Master Plan: Hydrology Technical Report, December 2010.
LEGEND
0 100 200
Scale (Feet)
N
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐18 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐19 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
Table IV.G‐1
Summary of Existing Hydrologic Analysis Results
Drainage Subarea
Acres Peak Discharge by Storm Return Frequency (cfs)a
100‐YEAR 50‐YEAR 10‐YEAR 5‐YEARDA1‐1 19.8 20.5 18.3 13 7.1
DA1‐2 9.3 13.6 12.1 8.6 4.7
DA2‐1 6.8 7 6.1 4.4 2.4
DA2‐2 12.9 19 17 12.1 6.6
DA2‐3 6.0 9.1 8.2 5.8 3.2
DA3‐1 27.7 28.5 25.5 18.1 9.9
DA3‐2 5.2 6.6 5.9 4.2 2.3
DA3‐3 1.4 2.1 1.8 1.3 0.7
DA3‐4 11.6 15.8 14.1 10.0 5.4
DA4 4.2 5.8 5.2 3.7 2.0
POA 104.9 128 114.2 81.2 44.3 Note:acfs=cubicfeetpersecond
Source:KPFFConsultingEngineers,BarlowReplacementHospitalandMasterPlan:Hydrology,(2010).
According to the Federal EmergencyManagement Agency Flood Insurance RateMap, the entire
Projectsiteisinanareaofminimalflooding(FloodZoneC).
iii. Off‐Site Storm Drain System
OntheeasternProjectsite,a38‐foot‐wideeasementnearthesouthernendoftheparcelcontains
the54‐inchRCPstormdrainthatdischargestheon‐sitecatchbasin/sumptothemunicipalstorm
drainbeneathStadiumWay.A38‐foot‐wideeasementonStadiumWaycontains the38‐footcurb
inlet towhichsubareaDA2‐3drains (thenorthwesternportionof theeasternProjectsite).A36‐
foot‐wide easement across StadiumWay onto both parcels; it contains the two 36‐foot catch
basinsoneithersideofStadiumWayatitslowestpoint.TheeasternProjectsitealsocontainsa20‐
footeasementthatcontainstheculvertandinfall/outfallstructuresforoff‐siterun‐onthatenters
theProjectsiteatthenorthernpropertylineonScottAvenue.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐20 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
ThewesternProjectsitecontainsthe36‐footeasementandcurbinlet/catchbasinattheStadium
Waylowpointaswellasa40‐footeasementonStadiumWaycontainingthecurbinletandcatch
basintowhichsubareaDA4‐1drains(thesouthernendofthewesternProjectsite).
ThemunicipalstormdrainbeneathStadiumWayadjacenttotheProjectsiteisinitially60inchesin
width,to75inchesasitapproachesBoylstonStreet;itcontinuessouthbeneathStadiumWayand
other roadway alignments, gradually increasing in size to a 120‐inch arch elliptical pipe that
dischargesintotheLosAngelesRiveratCesarChavezAvenue,approximately1.95milesfromthe
Project site. Figure IV.G‐4, Project Vicinity StormDrain System, and Figure IV.G‐5, ProjectArea
StormDrainSystem,showthemunicipalstormdrainsystemontheimmediateProjectvicinityand
largerProjectarea.
b. Surface Water Quality
i. Potential Sources of Erosion, Sedimentation, and Pollution
Erosion and Sedimentation
The potential for erosion and sedimentation (waterborne sediment) existwhere steep slopes or
undevelopedandunvegetatedlandaresubjecttouncontrolledsheetorchannelstormwaterflows
duringevents.
Aspreviouslydiscussed,theeasternProjectsitecontainsabroadswalecreatedbytheheavy of
runoffthatflowsoverlandbetweentheoutfall/headwallneartheScottAvenuepropertyboundary
andthecatchbasin/sumpatthesouthernendofthisparcel.Thisrunoffincludesstormwaterthat
flowsontotheProjectsitefromtheoff‐sitedrainageareatothenorth.Althoughsomestormwater
is intercepted by on‐site drainage structures in low‐lying areas, and the remaining runoff is
directed into the 48‐foot catch basin/sump at the southern end of the parcel, the volume and
velocityofflows erodedawaysoilaswellasunderlyingbedrockalongthepathoftravelacross
the eastern Project site, especially near the outfall/headwall. Slope gradients on the eastern and
northernedgesoftheeasternProjectsiterangefromamoderate5:1upto2:1,whichexacerbates
thepeakrunoffvolumesinthispartoftheProjectsite.
The lessdevelopedwesternProject site is steeplysloped,withgradients ranging from7:1 to2:1
and steeper slopesup to1.5:1.Although theundevelopedportionsof thisparcel are generally
vegetated,theslopesareregularlydiskedforwildfirecontrolpurposes,reducingopportunitiesfor
runoff percolation on‐site. Since all runoff generated on the western Project site is conveyed
downslope to Stadium Way via uncontrolled sheet flow, some potential exists for erosion and
Figure IV.G-4Project Vicinity Storm Drain System
Source: KPFF Consulting Engineers, Barlow Replacement Hospital & Master Plan: Hydrology Technical Report, December 2010.
N
Not to Scale
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐22 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
Figure IV.G-5Project Area Storm Drain System
LEGEND
Source: KPFF Consulting Engineers, Barlow Replacement Hospital & Master Plan: Hydrology Technical Report, December 2010.
N
Not to Scale
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐24 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐25 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
sedimentation,particularlyifchannelflowsdevelopinareaswhererunoff is locallyconcentrated.
Atpresent,however,thereisnoevidenceoferosionorsedimentationonthewesternProjectsite.
Pollution
TheProjectsitecontainsapproximately18.8acresofundevelopedandunpavedperviousarea(75
percentoftheProjectsite),muchofwhichislandscapedwithgrasslands,lawn,shrubs,tree,grass
and/ormiscellaneousvegetation.Theseareasmayusepesticidesand/orfertilizers,whichcanbea
sourceofpollutionifcarriedoff‐sitebystormwaterrunoff.
The remainder of the Project site, approximate 6.2 acres, is impervious. Nearly all of this
impervious area is on the eastern Project site and includes areas developed with buildings,
roadways and driveways, parking lots, and hardscape such aswalkways. All impervious surface
areascollectdustandparticulatematterthatareconveyedtothestormwaterdrainagefacilitiesby
stormwaterrunoff.Inaddition,drivewaysandparkinglotareascollectoilandgreasedepositsand
brakedustfromautomobiles,whichcanbewashedoffanddepositedintotheexistingcatchbasins.
ii. Measures to Control Erosion, Sedimentation and Pollution
Sump
MostofthestormwaterrunofffromthemajorityoftheeasternProjectsite,inthe9.3‐acredrainage
subareaDA1‐2, is collected in thecatchbasin/sumpat thesouthernendof theparcel.Thesump
allows sediment and pollutants to settle out prior to stormwater conveyance off‐site into the
municipal stormdrain system. There are also four catchment basins at low spots in the eastern
Projectsitethatinterceptsurfaceflows;thesehavedraingratestopreventtrashfromenteringthe
catchbasins.Thison‐sitesystemisdesignedtohandleupto50‐yeardesignstormflows.
StormwaterelsewhereontheProjectsiteisconveyeddownslopeviasurfaceflowanddischarged
offsite, into gutters lining StadiumWay that, in turn, convey flows to themunicipal stormdrain
system.
c. Groundwater
AsstatedinSectionIV.E,GeologicHazards,ofthisDraftEIR,theProjectsiteoccupiesthelowpoint
of a small north‐south trending valley infilled with permeable alluvial deposits underlain by
bedrock.ElevationsontheProjectsiterising from435feetabovemslalongStadiumWayto515
feetabovemslat theeasternpropertyboundarynearDodgerStadiumand572 feetabovemslat
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐26 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
the western property boundary along Elysian Park Drive. According to the Seismic Hazard
Evaluation of the Los Angeles 7.5 Minute Quadrangle, the Project site is not located within a
groundwaterbasin.
Boringsencounteredgroundwaterwithinthealluvialdepositsinlow‐lyingportionsoftheeastern
Project site, between5 and39 feet below the surface.This is considered to represent aperched
(confined)groundwatercondition,nothydrologicallyconnectedtoaregionalgroundwatersource.
Groundwater is continually recharged by an influx of groundwater and runoff from surrounding
hillsideareas,and therefore thedepth togroundwatervarieswith topographyacross theProject
site,annualprecipitation,andtheresultingmigrationofgroundwaterthroughthealluvialdeposits.
GroundwaterwasnotencounteredatthehigherelevationsalongtheeasternandwesternProject
sites,whichareunderlainbyshallowbedrock;bedrockisconsiderednon‐waterbearingbecauseof
its impermeability. Groundwater would not normally be expected in these areas unless it is
generatedbyrunoffandseepage;however,groundwaterlevelsandflowratesvaryseasonallyand
perchedgroundwatermaydevelopwherenonepreviouslyexisted,especiallyinimpermeablefine‐
grainedsoilsorbedrockfollowingheavyirrigationorrainfall.
4. ENVIRONMENTAL IMPACT ANALYSIS
a. Methodology
ThisanalysiswaspreparedbasedonthetechnicalreportpreparedfortheproposedProject,titled
BarlowHospitalandMasterPlan:Hydrology(December2010)byKPFFConsultingEngineers,which
is provided inAppendix IV.G of this Draft EIR. The technical report includes all calculations
performedtodeterminepre‐andpost‐developmentrunoffvolumes,duringa50‐yearstormevent,
in order to determine potential impacts on conveyance systems and drainage structure on the
ProjectsiteandinthemunicipalstormdrainsystemservingtheProjectsite.
b. Significance Thresholds
i. Surface Water Hydrology
The City of Los Angeles CEQA Thresholds Guide states that a project would normally have a
significantimpactonsurfacewaterhydrologyifitwould:
• Cause floodingduring the projected 50‐year developed stormevent,whichwouldhave
thepotentialtoharmpeopleordamagepropertyorsensitivebiologicalresources;
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐27 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
• Substantiallyreduceorincreasetheamountofsurfacewaterinawaterbody;or
• Result in a permanent, adverse change to themovement of surface water sufficient to
produceasubstantialchangeinthecurrentordirectionofwaterflow.
ii. Surface Water Quality
The City of Los Angeles CEQA Thresholds Guide states that a project would normally have a
significantimpactonsurfacewaterqualityif:
DischargesassociatedwiththeProposedProjectwouldcreate“pollution,”“contamination”
or“nuisances”asdefinedinSection13050oftheCaliforniaWaterCode.
Pollutionmeans an alterationof the quality of thewaters of the state to adegree,which
unreasonably affects either of the following: (1) the waters for beneficial uses;2 or (2)
facilitieswhichservethesebeneficialuses.PollutionmayincludeContamination.
Contaminationmeansanimpairmentofthequalityofthewatersofthestatebywastetoa
degreewhichcreatesahazardtothepublichealththroughpoisoningorthroughthespread
of disease.3 Contamination includes any equivalent effect resulting from the disposal of
waste,whetherornotwatersofthestateareaffected.
Nuisancemeansanythingwhichmeetsallofthefollowingrequirements:(1)isinjuriousto
health,orisindecentoroffensivetothesensesoranobstructiontothefreeuseofproperty,
soastointerferewiththecomfortableenjoymentoflifeorproperty;(2)affectsatthesame
time an entire community of neighborhood, or any considerable number of persons,
althoughtheextentoftheannoyanceordamageinflicteduponindividualsmaybeunequal;
and(3)occursduring,orasaresultofthetreatmentordisposalofwastes.
The proposed Projectwould cause regulatory standards to be violated, as defined in the
applicable National Pollutant Discharge Elimination System stormwater permit orWater
QualityControlPlanforthereceivingwaterbody.
2 Section13050oftheCaliforniaWaterCodeprovidesthatthefollowingdefinitionforbeneficialuses:“Beneficialuses’
ofthewatersofthestatethatmaybeprotectedagainstqualitydegradationinclude,butarenotlimitedto,domestic,municipal, agricultural and industrial supply; power generation; recreation; aesthetic enjoyment; navigation; andpreservationandenhancementoffish,wildlife,andotheraquaticresourcesorpreserves.”
3 Section13050oftheCaliforniaWaterCodeprovidesthefollowingdefinitionforwaste:“’Waste’includessewageandany and all otherwaste substances, liquid, solid, gaseous, or radioactive, associatedwith humanhabitation, or ofhuman or animal origin, or from any producing, manufacturing, or processing operation, including waste placedwithincontainersofwhatevernaturepriorto,andforpurposesof,disposal.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐28 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
iii. Groundwater Quality
Groundwater Level
The City of Los Angeles CEQA Thresholds Guide states that a project would normally have a
significantimpactongroundwaterlevelif:
Theprojectwouldchangepotablewaterlevelssufficientlyto:
Reducetheabilityofawaterutilitytousethegroundwaterbasinforpublicwatersupplies,
conjunctive use purposes, storage of imported water, summer/winter peaking, or to
respondtoemergenciesanddrought;
Reduceyieldsofadjacentwellsorwellfields(publicorprivate);or
Adverselychangetherateordirectionofflowofgroundwater.
Theprojectwouldresultindemonstrableandsustainedreductionofgroundwaterrecharge
capacity.
Groundwater Quality
The City of Los Angeles CEQA Thresholds Guide states that a project would normally have a
significantimpactongroundwaterqualityif:
The project would affect the rate, or change the direction, of movement of existing
contaminants;
Theprojectwouldexpandtheareaaffectedbycontaminants;
Theprojectwouldresultinanincreasedlevelofgroundwatercontamination(includingthat
fromdirectpercolation,injectionorsaltwaterintrusion);or
Theprojectwouldcauseregulatorywaterqualitystandardsinanexistingproductionwell
tobeviolated,asdefinedintheCaliforniaCodeofRegulations,Title22,Division4,Chapter
15,andintheSafeDrinkingWaterAct.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐29 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
AppendixG of the StateCEQAGuidelinesprovides samplequestions foruse in an initial study to
determine a project’s potential for environmental impacts. According to the sample questions4
included inAppendixGunderSection IX,HydrologyandWaterQuality, andSectionXVI,Utilities
andServiceSystems,aprojectwouldhaveapotentiallysignificantimpactifitwould:
IX.a) Violateanywaterqualitystandardsorwastedischargerequirements;
IX.b) Substantially deplete groundwater supplies or interferewith groundwater recharge
such that therewould be a net deficit in aquifer volume or a lowering of the local
groundwater table level (e.g., theproductionrateofpreexistingnearbywellswould
droptoa levelwhichwouldnotsupportexisting landusesorplannedlanduses for
whichpermitshavebeengranted);
IX.c) Substantiallyaltertheexistingdrainagepatternofthesiteorarea,includingthrough
thealterationof thecourseof a streamor river, inamannerwhichwouldresult in
substantialerosionorsiltationonoroffsite;
IX.d) Substantiallyaltertheexistingdrainagepatternofthesiteorarea,includingthrough
thealterationofthecourseofastreamorriver,orsubstantiallyincreasetherateor
amountofsurfacerunoffinamannerwhichwouldresultinfloodingonoroffsite;
IX.e) Create or contribute runoff water which would exceed the capacity of existing or
planned stormwater drainage systems or provide substantial additional sources of
pollutedrunoff;
IX.f) Otherwisesubstantiallydegradewaterquality;
IX.g) Place housing within a 100‐year flood hazard area as mapped on a federal Flood
HazardBoundaryorFloodInsuranceRatemaporotherfloodhazarddelineationmap;
IX.h) Placewithina100‐yearfloodhazardareastructureswhichwouldimpedeorredirect
floodflows;
IX.i) Expose people or structures to a significant risk of loss, inquiry or death involving
flooding,includingfloodingasaresultofthefailureofaleveeordam;
4 The remainder of the Appendix G Utilities and Service Systems sample questions (XVI.a, ‐b, and –d through ‐g)
pertain towater supply,wastewater, and solidwaste and are addressed inSections IV.L.1,WaterSupply, IV.L.2,Wastewater,andIV.L.3,SolidWaste,respectively.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐30 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
IX.j) Inundationbyseiche,tsunami,ormudflow;or
XVI.c) Require or result in the construction of new storm water drainage facilities or
expansion of existing facilities, the construction of which could cause significant
environmentaleffects.
TheInitialStudypreparedfortheproposedProjectdeterminedthatitwouldhavenoimpactwith
regardtosamplequestionsVIII.gand‐hofAppendixGoftheStateCEQAGuidelines.Theresponses
tothesequestionsarediscussedinSectionVII,EffectsFoundNottobeSignificant.TheInitialStudy
isprovidedinAppendixIofthisDraftEIR.
The thresholds used in the City of Los Angeles CEQA Thresholds Guide to determine significant
impacts on surfacewater hydrology, surfacewater quality, and groundwater quality incorporate
the more general checklist questions contained in AppendixG of the State CEQA Guidelines.
Therefore, based on the more specific City of Los Angeles CEQA Thresholds Guide, the proposed
Projectwouldhaveasignificantsurfacewaterhydrologyimpactif:
HWQ‐1 TheProjectwouldcausefloodingduringtheprojected50‐yeardevelopedstormevent,
which would have the potential to harm people or damage property or sensitive
biologicalresources;
HWQ‐2 TheProjectwouldsubstantiallyreduceor increasetheamountofsurfacewater ina
waterbody;or
HWQ‐3 TheProjectwouldresultinapermanent,adversechangetothemovementofsurface
watersufficienttoproduceasubstantialchange inthecurrentordirectionofwater
flow.
HWQ‐4 Dischargesassociatedwith theProjectwould create “pollution,” “contamination”or
“nuisances”asdefinedinSection13050oftheCaliforniaWaterCode.
HWQ‐5 The Project would cause regulatory standards to be violated, as defined in the
applicable National Pollutant Discharge Elimination System stormwater permit or
WaterQualityControlPlanforthereceivingwaterbody.
HWQ‐6 TheProjectwouldchangepotablewaterlevelssufficientlyto:
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐31 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
Reducetheabilityofawaterutilitytousethegroundwaterbasinforpublicwatersupplies, conjunctive use purposes, storage of imported water, summer/winterpeaking,ortorespondtoemergenciesanddrought;
Reduceyieldsofadjacentwellsorwellfields(publicorprivate);or
Adverselychangetherateordirectionofflowofgroundwater.
HWQ‐7 The Projectwould result in demonstrable and sustained reduction of groundwater
rechargecapacity;
HWQ‐8 TheProjectwouldaffect the rate, or change thedirection, ofmovement of existing
contaminants;
HWQ‐9 TheProjectwouldexpandtheareaaffectedbycontaminants;
HWQ‐10 The Project would result in an increased level of groundwater contamination
(includingthatfromdirectpercolation,injectionorsaltwaterintrusion);or
HWQ‐11 TheProjectwouldcauseregulatorywaterqualitystandardsinanexistingproduction
welltobeviolated,asdefinedintheCaliforniaCodeofRegulations,Title22,Division4,
Chapter15,andintheSafeDrinkingWaterAct.
HWQ‐12 TheProjectwouldrequireorresult intheconstructionofnewstormwaterdrainage
facilities or expansion of existing facilities, the construction of which could cause
significantenvironmentaleffects.
c. Project Design Features
Project implementation would develop the Project site with buildings, subterranean parking,
retaining walls along slopes, paved roadways and walkways, hardscape, and landscaped areas.
Project implementation would increase on‐site impervious area from approximately 6.2 acres,
which is approximately 25 percent of the site, to approximately 12.7 acres or approximately 51
percentoftheProjectsite.Thisisanincreaseofapproximately6.5acresoverexistingconditions.
Project implementation would alter on‐site stormwater drainage patterns and the direction of
flows.IncompliancewithLIDrequirements,theProjectsitewouldbedesignedtomanagerunoff
produced from the stormeventsdefined in the LIDordinance , and runoffwould accordinglybe
designedtoinfiltratethesite,orwouldbetreatedon‐sitepriortodischarge.Oncethisrequirement
ismet,runoffgeneratedontheeasternProjectsitewouldcontinuetobeconveyeddownslopevia
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐32 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
surface flow to the 48‐foot catch basin/sump at the southern end of the Project site. However,
future surface flows would be controlled and directed, and the existing swale created by the
concentrationof runoff fromtheProjectsiteandoff‐sitedrainagesubarea to thenorthwouldbe
regradedtoaccommodateProjectdevelopment.Surfaceflowswouldbemanagedsoastoprevent
futureerosionandsedimentationontheeasternProjectsite.RunoffontheProjectsite’swestern
Project site would be conveyed downslope via a combination of surface sheet flow and
underground conveyance systems.Runoffwould continue to be discharged into the gutter along
StadiumWayandthenintothemunicipalstormdrainviatheexistingcurbinletsandcatchbasins
onthewestsideofStadiumWay.
With respect to groundwater, if active seepage is constructed during construction, temporary
dewateringortheconstructionofFrenchdrainstocollectandcontrolwaterwouldbeconstructed.
Subterranean structures such as parking structures or basements would be waterproofed and
properly drained, or designed for the hydrostatic pressure that results from lack of drainage in
saturatedsoils.
Site‐specificBMPsfortheproposedProjecthavenotyetbeendefined,sincebuildingsitingandthe
locationofallProjectsitehardscapeandlandscapefeatureshavenotyetbeenfinalized.Moreover,
site‐specificconstraints including,butnot limitedto, finalizedparkingneeds,undergroundutility
clearance requirements for Project upgrades, and compliance with American Disability Act
requirements will influence the stormwater management features that are incorporated into
Projectdesign.However,a site‐specificSWPPPwouldbepreparedand implementedprior to the
commencement of each separate Project construction phase. BMPs would include, but not be
limitedto,erosioncontrol,sedimentcontrol,andthemanagementoftrash,debris,andothernon‐
stormwaterdischarges.
FinaldesignforeachconstructionphasewouldincorporateLID‐compliantfeaturesandpracticesto
beimplementedduringtheoperationallifeoftheProjectphase.TheLIDPlanwouldmeetorexceed
allapplicableCountyMunicipalNPDESPermitSUSMPrequirements,includingBMPsforsourceand
treatment controls. Treatment control BMPs to be implemented include increased retention of
stormwater runoff on the Project site for infiltration into the soil and groundwater recharge, in
compliancewiththepost‐developmentpeakstormwaterrunoffdischargeraterequirementsinthe
SUSMPstructuralBMP.
TreatmentcontrolBMPswouldalsobe implementedduring theoperational lifeof theProject, in
compliance with LID Plan SUSMP requirements. Treatment controls (to treat, infiltrate, or filter
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐33 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
stormwaterrunoff)wouldbeeitherflow‐basedBMPsorvolume‐basedBMPs,asdiscussedabovein
Subsection2.a.ii,CityofLosAngelesStormwaterProgram.
d. Project Impacts
i. Surface Water Hydrology
HWQ‐1 Would the Project cause flooding during the projected 50‐year developed
storm event, which would have the potential to harm people or damage
propertyorsensitivebiologicalresources?
HWQ‐2 Would the Project substantially reduce or increase the amount of surface
waterinawaterbody?
HWQ‐3 Would the Proposed Project result in a permanent, adverse change to the
movementofsurfacewatersufficienttoproduceasubstantialchangeinthe
currentordirectionofwaterflow?
Construction
ConstructionoftheproposedProjectwouldoccurinphasesoverthecourseof10yearsandwould
require the removal of existing buildings and hardscape; clearing, grading and excavation; and
constructionofnewbuildings,subterraneanparking,andhardscapeandlandscapedareas.Project
implementationwouldnecessitatetheconstructionofnewon‐sitestormdrainfacilitiesandother
underground and aboveground utility infrastructure. As stated in Subsection C, Project Design
Features, a LID Plan would be prepared and implemented prior to the commencement of each
Projectconstructionphase.Constructionwouldhavealessthansignificantimpactwithrespectto
flooding during a 50‐year design storm event, a substantial increase/decrease of the amount of
waterinreceivingwaters,orchangesinthecurrentordirectionofsurfacewaterflows.
Operation
The increase in impervious cover, grading, and new construction, as indicated inFigure IV.G.6,
ExistingConditions: ImperviousArea,andFigure IV.G.7,ProposedProject: ImperviousArea,would
alter existing drainage patterns on the Project site’s eastern and western Project sites, which
presently rely entirely on surface (sheet flow) to convey runoff off‐site. As discussed in under
ProjectDesignFeatures,futurestormwatermanagementontheProjectsitewillcontinuetorelyon
acombinationofsurface(sheetflow)andundergroundstormdrainsystemstoconveyrunofftothe
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐34 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
local municipal storm system beneath Stadium Way. Project implementation is anticipated to
increasethevolumeofrunoffgeneratedontheProjectsitebecauseoftheincreasein impervious
area.However,finalProjectdesignwillberequiredtodemonstratecompliancewithLIDordinance
requirements through the preparation of a LID Plan, which requires runoff to be managed or
capturedon‐siteinoneofseveralways,asprioritizedintheLIDordinance.
All proposed subterranean structures will be waterproofed and properly drained, or will be
designedforhydrostaticpressureresultingfromthepresenceofgroundwater.Ifactiveseepageis
encounteredduringexcavation,atemporarydewateringsystemconsistingofwellsand/orFrench
drainswouldbeconstructedtocollectandcontrolthewater.
Therefore, the proposed Project would not cause, or be subject to, flooding during a 50‐year
developed storm event, which could harm people, damage property, or sensitive biological
resources. Impacts related to flooding,a substantial increase/decreaseof theamountofwater in
receivingwaters,orchangesinthecurrentordirectionofsurfacewaterflowswouldbelessthan
significant.
ii. Surface Water Quality
HWQ‐4 Would the Project create “pollution,” “contamination”, or “nuisances” as
definedinSection13050oftheCaliforniaWaterCode?
HWQ‐5 Would theProject cause regulatory standards tobeviolated, asdefined in
theapplicableNationalPollutantDischargeEliminationSystemstormwater
permitorWaterQualityControlPlanforthereceivingwaterbody?
Construction
ThethreeprimarysourcesofpotentialstormwaterpollutionassociatedwithProjectconstruction
are:(1)thehandling,storage,anddisposalofconstructionmaterialscontainingpollutants,(2)the
maintenanceandoperationofconstructionequipment,and(3)earthmovingactivitieswhich,when
notcontrolled,maygeneratesoilerosionandsedimentationviastormrunoff,wind,ormechanical
equipment.
Thestorage,handling,anduseofchemicalsusedinconstruction,suchasfuels,paints,solvents,and
petroleum products, associatedwith construction activities could causewater quality impacts if
spilled or released in the path of stormwater runoff. Miscellaneous wastes include wash from
concretemixers, solidwasteresulting fromvegetationremovedduring landclearance,woodand
Figure IV.G-6Existing Conditions: Impervious Area
LEGEND
0 200 400
Scale (Feet)
Source: KPFF Consulting Engineers, Barlow Replacement Hospital & Master Plan: Hydrology Technical Report, December 2010.
N
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐36 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
Figure IV.G-7Proposed Project: Impervious Area
LEGEND
0 200 400
Scale (Feet)
Source: KPFF Consulting Engineers, Barlow Replacement Hospital & Master Plan: Hydrology Technical Report, December 2010.
N
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐38 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐39 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
papermaterialsfrombuildingproductspackaging,foodcontainers,andsanitarywastes.Concrete
washwater can be toxic and requires proper control. The discharge of thesewastes can lead to
polluted waterways. The unnecessary or improper application of herbicides, insecticides, and
rodenticidesat constructionsitesmayalsoresult in receivingwatercontaminationandpollution
through drift, or transport of soil particles by wind and rain fall. Generally, routine safety
precautions (“good housekeeping procedures”) for handling and storing construction materials
mayeffectivelyreducethepotentialforpollutionofstormwaterrunoffbythesematerials.
Siteclearanceofvegetationandbuildingdebrisandgradingandexcavationactivities,includingsoil
stockpiling,canalsogreatlyincreaseerosionprocessesandleadtosedimentloadingofstormwater
runoffandsubsequent impactsonstormdrains.Constructionequipmentcantrackmudanddust
off‐siteandintoarearoadways,whereitisabletoenterthemunicipalstormdrainsystem.
Finally,poorly‐maintainedvehiclesandheavyequipmentleakingfuel,oil,antifreeze,orotherfluids
onconstructionsitescanbecommonsourcesofstormwaterpollutionandsoilcontamination.
AsdiscussedinSubsectionc,ProjectDesignFeatures,oneormoreSWPPPswouldbepreparedin
compliancewith applicable local and State regulatory requirements for the Project construction,
includingindividualphasedProjectcomponents.BMPstobeimplementedontheProjectsitewould
beidentifiedindetailintheSWPPP.WithadherencetotheCity’sLIDordinanceandLIDandSWPPP
requirements,constructionisanticipatedtohavealessthansignificantimpactwithrespecttothe
creationofpollution, contamination,ornuisancesasdefined in theCaliforniaWaterCode,or the
violationofregulatorystandardscontainedintheLosAngelesCountyMunicipalNPDESPermit.
Operation
Surface water quality is generally affected by the length of time since the last rainfall, rainfall
intensity,urbanusesofthearea,andquantityoftransportedsediment.Typicalurbanwaterquality
pollutants usually result from motor vehicle operations, oil/grease residues, fertilizer/pesticide
uses,human/animallittering,carelessmaterialstorage/handling,andpoorpropertymanagement.
Themajorityofpollutantloadsareusuallywashedawayduringthefirstflushofastormoccurring
afterthedry‐seasonperiod.
Street and parking lot/garage‐generated pollutants typically contain atmospheric pollution, tire‐
wear residues, petroleum products, oil, and grease, fertilizer and pesticide wash‐offs, chemical
spills,aswellasanimaldroppingsandlittertypesofwastes.Thepollutantsarewashedfromstreet
surfacesbyarainfalladequatetoproducerunoff.Theamountofpollutantswashedoff thestreet
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐40 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
surfaceisafunctionoftheamountofpollutantsthathaveaccumulatedonstreetsurfacesandthe
frequency and amount of surface water flow flushing the pollutants from storm and non‐storm
events(suchashosingdownofwalkwaysandparkinggaragesurfaces).Thesepollutantshavethe
potentialtodegradewaterqualityandmayresultinsignificantimpacts.
The current building standards for parking structures require the installation of oil and grease
traps and other mechanisms to treat water before being sent to the storm drain system. The
proposed Project would replace most of the existing surface lot parking (which do not have
mechanisms in place to treat runoff) with subterranean parking grade. The unnecessary or
improper application of herbicides, insecticides and rodenticides may result in receiving water
contaminationandpollutionthroughdrift,ortransportofsoilparticlesbywindandrainfall.Also,
pesticidesmay inadvertentlybe released to the environment if notproperly labeled, handled, or
stored. Barlow Hospital maintains on‐site storage of all such materials in accordance with
requirementsoftheCaliforniaDepartmentofPesticideRegulation.
Fewmechanisms are in currently inplace to reduce runoff volumesdischarged to themunicipal
stormdrainsystemortotreatrunoffon‐sitebeforedischargeoff‐site,withtheexceptionofthe48‐
footcatchbasin/sumpatthesouthernendoftheeasternProjectsite,whichreceivesmostrunoff
generated on the eastern Project site. As discussed inSubsectionc,ProjectDesignFeatures, the
proposed developer is required to develop a LID Plan and SUSMP in accordance with the Los
AngelesCountyMunicipalNPDESPermitrequirements,whichwouldincludesourceandtreatment
control BMPs. With adherence to the City’s LID and SWPPP requirements, Project operation is
anticipated to have a less than significant impact with respect to the creation of pollution,
contamination,ornuisancesasdefinedintheCaliforniaWaterCode,ortheviolationofregulatory
standardscontainedintheLosAngelesCountyMunicipalNPDESPermit.
iii. Groundwater
HWQ‐6 WouldtheProjectchangepotablewaterlevelssufficientlyto:
• Reduce the ability of a water utility to use the groundwater basin for
public water supplies, conjunctive use purposes, storage of imported
water, summer/winter peaking, or to respond to emergencies and
drought;
• Reduceyieldsofadjacentwellsorwellfields(publicorprivate);or
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐41 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
• Adverselychangetherateordirectionofflowofgroundwater?
HWQ‐7 Would the Project result in demonstrable and sustained reduction of
groundwaterrechargecapacity?
HWQ‐8 Would theProject affect the rate, or change thedirection, ofmovementof
existingcontaminants?
HWQ‐9 WouldtheProjectexpandtheareaaffectedbycontaminants?
HWQ‐10 WouldtheProjectresultinanincreasedlevelofgroundwatercontamination
(includingthatfromdirectpercolation,injectionorsaltwaterintrusion)?
HWQ‐11 Would the Project cause regulatorywater quality standards in an existing
production well to be violated, as defined in the California Code of
Regulations,Title22,Division4,Chapter15,andintheSafeDrinkingWater
Act?
HWQ‐12 WouldtheProjectrequireorresultintheconstructionofnewstormwater
drainage facilities or expansion of existing facilities, the construction of
whichcouldcausesignificantenvironmentaleffects?
e. Mitigation Measures
Themitigationmeasureswouldaddressimpactstosurfacewaterhydrologyandwaterqualityand
ensurethatimpactsremainlessthansignificant.
MM‐HWQ‐1 Prior to thestartof soil‐disturbingactivitieson theProject site, aNoticeof Intent
(NOI) and StormWater Pollution Prevention Plan (SWPPP) shall be prepared in
accordancewith,andinordertopartiallyfulfill,theCaliforniaSWRCBOrderNo.99‐
08‐DWQ, National Pollutant Discharge Elimination System General Permit No.
CAS000002 (GeneralConstructionPermit).The StormWaterPollutionPrevention
PlanshallmeettheapplicableprovisionsofSections301and402oftheCleanWater
ActandChapter6Article4.4,StormWaterandUrbanRunoffPollutionControlfrom
theCityofLosAngelesMunicipalCodebyrequiringcontrolsofpollutantdischarges
thatutilizebestavailabletechnologyeconomicallyachievableandbestconventional
pollutantcontroltechnologytoreducetherateandquantityofstormwaterrunoff.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐42 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
MM‐HWQ‐2 TheProjectsiteshallbedesignedtomanageandcapturestormwaterrunoff,tothe
maximumextentfeasible,inpriorityorder:infiltration,evapotranspiration,capture
anduse,treatedthroughhighremovalefficiencybiofiltration/biotreatmentsystem
of all of the runoff on site. High removal efficiency biofiltration/biotreatment
systemsshallcomplywiththestandardsandrequirementsoftheDevelopmentBest
ManagementPracticesHandbook.ALIDPlanshallbepreparedtocomplywiththe
following:
Stormwater runoff shall be infiltrated, evapotranspired, captured and used,
treated through high removal efficiency Best Management Practices, onsite,
throughstormwatermanagementtechniquesthatcomplywiththeprovisionsof
the Development Best Management Practices Handbook. To the maximum
extent feasible, on‐site stormwater management techniques shall be properly
sized, at aminimum, to infiltrate, evapotranspire, store for use, treat through
high removal efficiency biofiltration/biotreatment system, without any storm
water runoff leaving theSite forat least thevolumeofwaterproducedby the
qualitydesignstormeventthatresultsfrom:
The85thpercentile24‐hourrunoffeventdeterminedas themaximized
capture stormwater volume for the area using a 48 to 72‐hour draw
down time, from the formula recommended in Urban Runoff Quality
Management,WEFManualofPracticeNo.23/ASCEManualofPractice
No.87,(1998);or
Thevolumeofannualrunoffbasedonunitbasinstoragewaterquality
volume,toachieve80percentormorevolumetreatmentbythemethod
recommendedintheCaliforniaStormwaterBestManagementPractices
Handbook‐Industrial/Commercial,(2003);or
Thevolumeofrunoffproducedfroma0.75inchstormevent.
Forpurposesofcompliancewith theLIDrequirements,andwithoutchanging
thepriorityorderofdesignpreferencesidentifiedinthisSection,allrunofffrom
the water quality design storm event, as identified in Paragraph (a) of this
Subdivision, that has been treated through an onsite high removal efficiency
biofiltration/biotreatment system shall be deemed to have achieved 100%
infiltrationregardlessoftherunoffleavingtheSitefromanonsitehighremoval
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐43 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
efficiency biofiltration/biotreatment system, and thus any runoff volume shall
notbesubjecttotheoffsitemitigationrequirementofthisArticle.
Pollutants shall be prevented from leaving the Site for awater quality design
stormeventasdefined inParagraph (a)of thisSubdivisionunless ithasbeen
treated through an onsite high removal efficiency biofiltration/biotreatment
system.
Hydromodification impacts shall beminimized to natural drainage systems as
definedintheMS4Permit.
When, as determined by the Director, the onsite LID requirements are
technically infeasible, partially or fully, as defined in the Development Best
ManagementHandbook,theinfeasibilityshallbedemonstratedinthesubmitted
LIDPlan,shallbeconsistentwithotherCityrequirements,andshallbereviewed
inconsultationwiththeDepartmentofBuildingandSafety.
Ifpartialorcompleteonsitecomplianceofanytypeistechnicallyinfeasible,the
project Site and LID Plan shall be required to comply with all applicable
StandardUrbanStormwaterMitigationPlan(SUSMP)requirementsinorderto
maximizeon‐sitecompliance. Fortheremainingrunoffthatcannotfeasiblybe
managedonsite,theprojectshallimplementoffsitemitigationonpublicand/or
privatelandwithinthesamesub‐watershed.Thisshallincludeconstructionand
perpetualmaintenance of projects thatwill achieve at least the same level of
runoffretention,infiltrationand/oruse,andwaterquality.AllCityDepartments
willassistthedeveloper,whenandwherefeasible,inthedesign,permittingand
implementation of LID BMP projects within the public right of way, with a
preference for utilizing the public right of way immediately adjacent to the
subjectdevelopment.
AMulti‐PhasedProjectmaycomplywiththestandardsandrequirementsofthis
Sectionforallofitsphasesby:(a)designingasystemacceptabletotheBureau
of Sanitation to satisfy these standards and requirements for the entire Site
duringthefirstphase,and(b)implementingthesestandardsandrequirements
for each phase of Development or Redevelopment of the Site during the first
phaseorpriortocommencementofconstructionofalaterphase,totheextent
necessarytotreatthestormwater fromsuch laterphase. Forpurposesof this
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐44 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
Section,"Multi‐PhasedProject"shallmeananyDevelopmentorRedevelopment
implementedovermorethanonephaseandtheSiteofaMulti‐PhasedProject
shall include any land and water area designed and used to store, treat or
manage stormwater runoff in connection with the Development or
Redevelopment.
f. Level of Significance After Mitigation
All Project‐specific construction and operational impacts would be less than significant and no
mitigation is required. Nonetheless, mitigation measures MM‐HWQ‐1 and MM‐HWQ‐2 are
recommendedtoensurecompliancewithpertainingtoconstructionandoperationalimpactson
surfacewaterquality.
g. Cumulative Impacts
Thegeographiccontext forevaluationofcumulative impactsonsurfacewaterhydrology, surface
waterqualitystemdownstreamoftheProjectsite.AsdiscussedinSectionIII,GeneralDescription
of Environmental Setting, several related projects are proposed and/or planned in the Project
vicinity.AlltheprojectsarelocateddownstreamoftheproposedProject,and,consideredtogether
withtheproposedProject,havethepotentialtocontributetocumulativelysignificant impactson
surfacewaterhydrologyandsurfacewaterquality.Themajorityoftheseprojects,however,willbe
requiredtoimplementSWPPandSUSMPprogramsincompliancewithCityandStateregulations,
which would result in a cumulative decrease in stormwater runoff rate and volume and,
consequently,adecreaseintheamountofpollutantscarriedbystormwaterrunoff.
The Project site is the most upstream point of direct connection to the municipal storm drain
system that serves it and themunicipal system isadequately sized toaccommodateexistingand
post‐Project runoff volumes. With compliance with SUSMP volumetric or flow‐based treatment
controlBMPsthatregulatethevolumeofrunoffdischargedoff‐site,post‐Projectdischargevolumes
wouldremainunchanged,andmaydecrease,during50‐yeardesignstormevents.Withcompliance
with other SWPPP and SUSMP requirements, the potential for conveyance of pollutants off‐site
wouldalsobelessthansignificant.Projectimpactsonsurfacewaterhydrologyandsurfacewater
qualitywouldbelessthansignificant,andtheProjectisnotanticipatedtoresultinaconsiderable
contribution to cumulatively significant impacts related to surface water hydrology or surface
waterquality.
IV.G Surface Water Hydrology, Surface Water Quality, and Groundwater
CityofLosAngeles IV.G‐45 BarlowHospitalReplacementandMasterPlanProjectENV2009‐2519‐EIR DraftEIR. April2012
TheProjectisunderlainbyaperchedgroundwatertable,oraquifer,thatfluctuatesindepthwith
seasonalrainfallandother factors. Itdoesnotoverlieorproposewithdrawals fromaproduction
wellandwouldnotaffect thewaterquality inawell.TheproposedProjectwouldnotresult ina
considerablecontributiontocumulativelysignificantimpactsongroundwaterlevelsorquality.
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