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NFIPMappingIssuesWendyLathrop,PLS,CFMCadastralConsulting,LLC
NFIPBasicObjectives:Reducetheexposuretoflooddamagesthroughtheuseofminimumstandardsfortheplacementanddesignofstructureslocatedinfloodhazardareas.NFIPPurposes(42USC§4001)
• Identifyandmapfloodhazardareas• Provideaframeworkforfloodplainmanagementregulations• MakefloodinsuranceavailableincommunitiesparticipatingintheNFIP
Whymappingmatters
• Inaccuratemap=improperinsuranceandregulation• Nomap=insuranceand/orregulatoryrepercussions
NFIPRegulationsTitle44CFR-Part59-GeneralProvisions
• Definitions• Programdescription• Eligibilityrequirements
Terminology
• Flood• Floodfrequency• Floodplain• Floodfringe• Floodway• Basefloodelevation• Floodplainmanagement
FloodingtypesThreemaincategories:
• Riverineflooding• Coastalflooding• Shallowflooding
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NFIPZones:44CFR64.3• ZoneA• ZonesA1-A30,AE• ZonesAO,AH• ZonesA99,AR• ZonesB,ShadedX• ZonesC,UnshadedX
• ZoneV• ZonesV1-V30,VE• ZoneVO• ZoneD• ZoneE• ZoneM
RiverineWatershedandFloodplain
Floodway/FloodFringe
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CoastalHazards
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Other“Unique”FloodHazards• AlluvialFans• Migratingstreams• MudFlows• Ice/debrisJams• DamFailures• Tsunamis
LegacysedimentsMapevolution
• FloodHazardBoundaryMaps(FHBM)• FloodInsuranceRateMaps• FloodBoundary/FloodwayMaps(FBFW)• Digitalformat• DigitalFloodInsuranceRateMaps(DFIRM)
Thebirthofamap
• Mappingneedsassessment• Determinationofresources• Scoping• DataCollection• DataAnalysisandcompilation
HowtomakeaFIRM/DFIRM44CFR65:IdentificationandMappingofSpecialHazardAreas“ThepurposeofthispartistooutlinethestepsacommunityneedstotakeinordertoassisttheAgency'seffortinprovidingup-to-dateidentificationandpublication,intheformofthemapsdescribedinpart64…”
GuidelinesandStandards:MasterIndexGuidelinesandSpecificationsforFloodHazardMappingPartners
• Acompilationofresources• 3volumes,14appendices• Someitemsmarked“superseded”butnotfullyreplaced;useasbackground• http://www.fema.gov/media-library/resources-documents/collections/361
ThemultiplepurposesofFIRMs
• Insurancerating• LendercompliancewithNFIP• Eligibilityfordisasterassistance• Landuseregulation
• Planning• Emergencymanagement• Landdevelopment• Appraisal
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Approachestomappingfloodplains• Approximatemethods• Limitedstudymethods• Detailedmethods• Limitedmapmaintenanceprojects• Restudies
WhataFIRM/DFIRMtellsus
• Floodrisklevels• Flood“protection”• Floodcontainment• Levelofdetail• Limitofdetail• RefertoFIS
FloodInsuranceStudyReport-Thedetails“MapModisDead,LongLiveRiskMAP”“…todeliverqualitydatathatincreasespublicawarenessandleadstoactionthatreducesrisktolifeandproperty.”Digitalmapping“Digital”mappingmayormaynotbeofbetterqualitythannon-digitalversions
• Scannedpapermaps• Fielddataconvertedtodigitalfilesforanalysisanddigitalmapcreation• Fielddatacollectedasdigitalfilesforanalysisanddigitalmapcreation• Digitalphotography• 3-DLaserscanning
ProcedureMemorandum38
• Dataconsistencystandard,not“accuracy”standard
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Lookatthemetadata“BaseMapSource:1:100,000USGSDigitalLineGraphs.Mapusersshouldbeawarethatthisbasemapsourcecausesroadalignmentdistortionsatandnearroadintersections.Thesealignmentproblemshavebeencorrectedinthevicinityofidentifiedfloodplains.”Theadoptionofamap
• Preliminarymapping• Publichearings• FEMAreviewofappeals• LetterofFinalDetermination
NFIPRegulations-Title44CFR,Part67AppealsfromProposedFloodElevationDeterminations
• Rightofappeal• Typesofappeals• Appealprocedures
Keepingmapscurrent
• Originallackofmappingdetail• Topographicchanges• Imperviouscoverchanges• Structuralchanges• Hydrologicandhydraulicchanges• Jurisdictionalchanges
Remember-themapisasnapshotofconditionsatagiventimeResponsibilityformapping44CFR65.3–Requirementtosubmitnewtechnicaldata“…notlaterthansixmonthsafterthedatesuchinformationbecomesavailable,acommunityshallnotify[FEMA]ofthechangesbysubmittingtechnicalorscientificdata…”
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FutureconditionsAdvisorymappingThevolatilityoferosion(and/orsubsidenceand/orsealevelrise)LOMCs
• OfficiallyamendorrevisetheFloodInsuranceRateMap(FIRM)WhyLOMCs?
• Lessexpensivethanrepublishingthemaps• Fasterthanrepublishingthemaps• Scalelimitations• Timeandnoticeconsiderations
Elevationmatters!
• Whereis“zero”?• Heightoffloor• Heightofwater• Inherentuncertainties• Benefits/costs
KeyTermsforLOMCs
• LowestAdjacentGrade(LAG)• HighestAdjacentGrade(HAG)inZoneAO• BaseFloodElevation(BFE)• Fill• LowestFloor• Basement
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Mapupdates–amendments• LetterofMapAmendment–sitespecific• Inadvertentinclusionstofloodplain• Structuresorlegallydefinedparcels• Donotinvolvehydrologicorhydraulicanalyses(unlessZoneA)• UseMT-1(orMT-EZ)• e-LOMAconsiderations
NFIPRegulations-Title44CFR,Part70-ProcedureforMapCorrection“MappingDeficienciesUnrelatedtoCommunity-WideElevationDeterminations”
• Righttosubmittechnicalinformation• LettersofMapAmendment• Reviewofproposedprojects
TheFIRMtakesprecedenceoverelevation.IfthegradeisaboveBFE,requestaLOMA.44CFR70.3–LOMADataintheapplicationmayinclude:
• Topographicmapping• NotopographyneededifaplotontheFIRMshows“outasshown”• LAG(includingattacheddecks,garages)• Mapshowinglocationofstructure• Curvilinearlinerepresentingareasubjecttoinundationbythebaseflood
HomeownercansubmitapplicationCrossSectionalViewofaLOMARequest
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TypicalSourcesofBFEs• FEMAFloodInsuranceStudyReportprofile• FEMAFloodInsuranceRateMap• Other1%annual-chanceFloodStudy• FEMAQuick-2software• Streamgaugedata• Extrapolationofdetailedstudyupstream• Newdetailedstudy
NoBFE–nowwhat?FEMAPublication265(1995):
• “ManagingFloodplainDevelopmentinApproximateZoneAAreas:AGuideforObtainingandDevelopingBase(100-Year)FloodElevations"
ApproximateBFEmethods
• Historicalhighwatermarks+safetyfactor• Watercontrolstructure+freeboard• Matchtopography• “Contour”method(a.k.a.“pointonboundary”)
LOMAinZoneA
• MAYbeabletocompleteLOMAwithoutengineer:o Includeallavailableinformationregardingstructurelocation,topography,
FIRMs.• Iftooclosetocall,considerotherapproaches:
o ExtrapolationofBFEsfromnearbylocations• Ifnoneofthesimplifiedmethodsareappropriate,surveyedcrosssectionsand
engineeringmethodsarerequired.ApplyingforaLOMAOutcome(whatisremovedfromSFHA)
FloodZone BFE LAG LFE LowestLotElevation
Building200 X(unshaded)
13.8feet 21.8feet 23.3feet -
Outcome(whatisnotremovedfromSFHA)
FloodZone BFE LAG LFE LowestLotElevation
Structure AE 1494.9 1493.2 1495.8 -
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Outcome(whatisoutsideSFHA)
FloodZone BFE LAG LFE LowestLotElevation
Residentialstructure
C - - - -
e-LOMA
• On-lineapplication• Restrictions:nofill;BFEavailable• Auditing• ImplicationsforlocalcommunitiesandotherswhoutilizeLOMAs• DiffersfromonlineLOMCapplication
Mapupdates–revisions
• Engineeredchangeso LetterofMapRevisiono LetterofMapRevisionbasedonFillo Physicalmaprevisions
• Morecomplexthanamendments• Notusuallylotorstructurespecific• Typicallyinvolvehydrologicand/orhydraulicanalyses• RequiresubmittalofMT-2forms
NFIPRegulations-Title44CFR,Part65IdentificationandMappingofSpecialFloodHazardAreas
• Requirementtosubmittechnicaldata(65.3)• Righttosubmitnewtechnicaldata• Maprevisions• Floodways• Levees
44CFR65.5-LOMR-FRequestormustsubmit:
• Copiesofrecordeddeedandplats• Topographicmapindicatingpresentgroundelevationsandfill• LocationofstructureandLAGelevation• BFEdatafromauthoritativesource• Communityacknowledgementform(MT-1)
DefinitionofLowestFloor“...thelowestfloorofthelowestenclosedarea,includingbasement.Anunfinishedorfloodresistantenclosure,usablesolelyforparkingofvehicles,buildingaccessorstorageinanareaotherthanabasementareaisnotconsideredabuilding’slowestfloor;providedthat
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suchenclosureisnotbuiltsoastorenderthestructureinviolationoftheapplicablenon-elevationdesignrequirementsofSec.60.3.”DefinitionofBasementThatportionofabuildinghavingitsfloorsubgrade(belowgroundlevel)onallsides.Cross-SectionalViewofaLOMR-FRequest
LOMR-F–Whydidthisapplicationfail?Outcome(whatisnotremovedfromSFHA)
FloodZone BFE LAG LFE LowestLotElevation
Structure AE 63.3feet 62.3feet 60.5feet -Newmap–nowwhat?
Incorporated? ORRevalidatedandreauthorized? ORSuperseded?
ConditionalLetters
• Reviewofproposedprojects• CLOMA:44CFR70.9• CLOMR:44CFR65.8• Noeffectoninsurance• FinalLOMCrequiresas-builtcertification
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NFIPRegulations-Title44CFR,Part72ProceduresandFeesforProcessingMapChanges
• DefinesCLOMA,CLOMR,CLOMR-F,LOMR,LOMR-F,PMR• Feeschedule• Submittalandpaymentprocedures• Feeexemptions• Resubmittals
Ms.Alpha
• Herhouseisawood-framestructurewithFFEof712.3NGVD,abasementelevationof702.8,LAGis711.2.
• Fillwasplacedforconstructionin1999.Thefloodinsurancemap(thenaFHBM)wasfirstprinted1997,butWalnutCreek(floodingsource)wasn’tshownasafloodhazarduntil2003.
• NewstudywillincludearestudyofWalnutCreek.CurrentBFEis710.5, whilerestudyshows711.2
• WhichLOMC?Shoulditbeapproved?Whataboutafterthenewstudyispublished?Mr.Beta
• HishouseisabrickstructurewithaFFEof858.2NGVD,acrawlspaceelevationof849.00,andLAGis853.4.Engineeredfillwasplacedduringconstructionofthehomein2014.
• TheFIRMforthiscommunityisdated1995,anditisthefirstNFIPmapshowingSFHAsinthisarea.Mr.Betapreviouslysubmittedandreceivedaconditionalletterin2013.
• ShouldhishouseberemovedfromSFHA?Whattypeoflettershouldheapplyfor?