A supplement to the Guildford Borough Strategic Flood Risk Assessment, forming part of the Guildford Development Framework evidence base - November

Transcription

1 A supplement to the Guildford Borough Strategic Flood Risk Assessment, forming part of the Guildford Development Framework evidence base - November

2 Contents Page 3 Vision 3 Executivesummary 4 Introduction 4 FloodZone3 4 Thereasonforthisdocument(policybackground) 6 Whenwillthisdocumentbeusedandbywhom? 7 Howwasthisdocumentprepared? 7 Thecontextofthisdocumentinaccordancewithotherdocuments 9 FloodriskinGuildfordUrbanArea 9 Surfacewaterflooding 10 Criticalinfrastructure 19 FloodriskreductionmeasuresinexistingandnewdevelopmentsinGuildfordUrban Area 19 RiskreductionmeasuresinGuildfordUrbanArea 20 Existingdevelopments 26 Newdevelopments 33 Trackingandmonitoring 34 Othersourcesofinformation(referencestootherdocuments) 34 Contactdetails 34 Usefulwebsites 35 Glossary Page Figure Title 8 1 ReducingfloodriskinGuildfordUrbanArea 16 2a MapofGuildfordUrbanArea 17 2b Locationoflanduse/developmentexamplesinGuildfordTownCentre 18 2c Propertytypewithin1in100floodoutline 19 3 Table2.7anextractfrom Improvingthefloodperformanceofnewbuildings May2007,Defra,CLGandEnvironmentAgency 22 4 Floodprotectionmeasuresforexistingpropertyowners 27 5 Riskreductionmeasuresfornewdevelopment Page Annex Title 41 A ExplanationoftermsusedinFigure1 ReducingFloodRiskinGuildford UrbanArea 43 B Documenthistory 44 C SupplementaryNoteonFloodHazardRatingsandThresholdsfor DevelopmentPlanningandControlPurpose 2

3 Vision To reduce the risk 1 of flooding in Guildford Urban Area, using redevelopment opportunities to provide increased safety, additional floodwater storage and improvedfloodwaterflowswhilstmakingspaceforwaterandtheenjoymentof theriverwey. TheThamesCatchmentFloodManagementPlan(CFMP)addressesfloodriskmanagementoverthe next years. In accordance with this, the vision above is a long term vision which will be reviewed and updated in partnership with the Environment Agency and in accordance with the timescales of the CFMP, the River Wey Flood Risk Management Draft Strategy 2010 and the GuildfordDevelopmentFramework(GDF). Executivesummary ThisFloodRiskReductionMeasuresdocumentformspartoftheGuildfordDevelopmentFramework (GDF) evidence base. This document provides information on the type of flood risk reduction measuresrequiredforallproposedredevelopmentwithinfloodzone3 2 ofguildfordurbanarea.it also offers information to those wishing to improve the flood resilience or resistance of existing properties.thisapproachrecognisesthatduetothechallengesandconstraintsfacingtheborough, an acceptance of some level of flood risk is necessary. This approach is in conjunction with the GuildfordStrategicFloodRiskAssessment(SFRA),PlanningPolicyStatement25:Developmentand FloodRisk(2006,updated2010)andtheThamesCatchmentFloodManagementPlan(CFMP). 1 Risk=probabilityxconsequence 2 TheextentofFloodZone3inGuildfordUrbanAreacanbeseenontheEnvironmentAgency sinteractivemaps,orthe Council sinteractivemapsonline( 3

4 Introduction This document provides details of flood risk reduction measures to be used in Flood Zone 3 in Guildford Urban Area, taking all opportunities through new development to reduce the consequencesofflooding.italsoprovidesadvicetothosepeoplewithpropertiesatriskofflooding inguildfordborough.developmentinfloodzone3mustpassthesequentialandexceptiontests,as setoutinpps25,whererequiredbeforeappropriateriskreductionmeasurescanbeconsidered. ThisdocumentsupportstheGuildfordStrategicFloodRiskAssessment(SFRA)andsetsoutaunique approach to the functional floodplain in Guildford Urban Area. It also forms part of the Guildford Development Framework (GFD) evidence base. This evidence base informs the preparation of policiesindevelopmentplandocuments(corestrategyandsiteallocations)andhasbeenapproved bythecouncilasamaterialplanningconsiderationforthedeterminationofplanningapplications (October 2010). In the longer term, this evidence base document will be progressed to become a SupplementaryPlanningDocument(SPD). FloodZone3 Throughout this document, all references to Flood Zone 3 refer to the detailed 1:100 year flood outlinesofriverfloodingintherevisedfloodoutlinesaspublishedbytheenvironmentagency(june 2010).ThesemapsarebasedondetailedrivermodellingoftheRiverWeycatchmentandsupersede thoseshowninthesfra2009.thisdetailedinformationisnecessarytoallowtheapplicationofthe SequentialTest.SeetheSFRA(chapter2)formoreinformation. Thereasonforthisdocument(policybackground) PlanningPolicyStatement(PPS)25:DevelopmentandFloodRiskwaspublishedbyCommunitiesand Local Government (CLG) in December 2006, and updated in March PPS25 seeks to ensure flood risk is taken into account at all stages of planning and that allowances are made for future climatechange.pps25requireslocalauthoritiestoprepareasfra.thesfrainformstheplanning processoffloodriskandprovidesinformationonfutureriskoverawidespatialarea.itisalsoused as a planning tool to examine the sustainability of potential development allocations in the GDF. GuildfordBoroughCouncilpublisheditsSFRAinJanuary2009andwillbeupdatedinfuture. PPS25setsoutguidelinesforappropriatedevelopmentwithinspecificFloodZones.Inmanycases developmentcanonlybeconsideredoncethesequentialtestandexceptiontesthavebeenpassed. Thesetestsmustbeconsideredbeforethisstageoffloodriskreductionmeasures.PPS25originally definedthefunctionalfloodplainrelativelyrigidlyastheareawithanannualprobabilityofflooding of 1 in 20 or greater, or at any probability to be agreed between the LPA and the Environment Agency.InAugust2009,theGovernmentconsultedonareviseddefinition,andreceivedsupportfor its proposal (Summary of responses and key issues raised, 29 March 2010). The definition has subsequentlybeenupdatedinpps25(march2010)andnowreads; This zone comprises land where water has to flow or be stored in times of flood. Local planning authorities should identify in their SFRAs areas of functional floodplain and its boundaries accordingly, in agreement with the Environment Agency. The identification of functionalfloodplainshouldtakeaccountoflocalcircumstancesandnotbedefinedsolelyon rigidprobabilityparameters.butlandwhichwouldfloodwithanannualprobabilityof1in 20 (5%) or greater in any year, or is designed to flood in an extreme (0.1%) flood, should 4

5 provide a starting point for consideration and discussions to identify the functional floodplain. (PPS25,revised29March2010). Guildford Town Centre, and the wider Guildford Urban Area, is a sustainable location for development within the borough. The Council intends to help address housing need by providing housing, and other forms of development, within these sustainable locations and other identified sustainablelocationswithintheborough 3.However,astheRiverWeyflowsthroughGuildfordTown CentreandGuildfordUrbanArea,largeareasoflandareidentifiedaswithinthe1in20yearflood outline. Using the identified starting point in the definition in PPS25, these areas 4 would be categorised as Functional Floodplain where development, other than essential infrastructure and watercompatibleuses,wouldnotbepermitted. Basedondetailedrivermodelling,therearearound67hectaresof1in100yearfloodplaininthe Guildford UrbanArea.Ofthis,about47hectaresaredefinedasfunctionalfloodplain.Withahigh proportion of Flood Zone 3 also defined as Functional Floodplain, and a large amount of existing developmentinthisarea,asolutiontonotonlypreventurbanblight,butalsoreducefloodriskin theguildfordurbanareahasbeenexplored. The definition within the original PPS25 allowed for an alternative flood probability to be agreed with the Environment Agency where appropriate, and was thus pursued. This approach has since beensupportedthroughtherevisionstothedefinitionofthefunctionalfloodplainintherevised PPS25(March2010).ThedecisiontoredefinetheFunctionalFloodplainisbasedontheCouncil s commitment to directing development to the Urban Areas of the borough, the identified housing need, the highly constrained nature of Guildford Borough (due to the extensive amount of Green Beltland),therequirementtodelivertheCatchmentFloodManagementPlanand,whenapproved, theriverweyfloodriskmanagementdraftstrategy Theneedtoallowsafeandsustainable development to proceed where appropriate in Guildford Urban Area is agreed between both GuildfordBoroughCouncilandtheEnvironmentAgency. Therefore,asdetailedintheSFRA(p.22), Within the main Guildford Urban Area the definition of Functional Floodplain has been agreedtobedelimitedbythetopofbank,withinthisareathereforethe1in20yearoutline does not equate to the area defined as Functional Floodplain. This definition has been adoptedasitisagreeditisnotappropriatetoclassifybuiltupareasofcentralguildfordas FunctionalFloodplain. In accordance with this document, redevelopment within Flood Zone 3 (1 in 100 flood outline) in GuildfordUrbanAreamustbesupportedbyadditionalfloodriskreductionmeasures.Themeasures containedinthisdocumentarenotdesignedtopromoteguildfordurbanarea,orthetowncentre withinit,asamajordevelopmentsite.instead,theywillprovidetightercontrolsondevelopment withinzone3a(floodzone3)inguildfordurbanareathanthosecontainedinpps25.theapproach appliestoanydevelopmentwhichpassesthesequentialtestandexceptiontest(partsaandb)in 3 GuildfordUrbanArea,AshandTonghamUrbanArea,IdentifiedVillageSettlementsandGuildfordTownCentreare sustainablelocationswithintheboroughfordevelopmentinaccordancewiththelocalplan2003.anyproposalfor developmentissubjecttoallrelevantplanningpolicyandmaterialplanningconsiderations. 4 NoteGuildfordTownCentreiswithinGuildfordUrbanArea 5 SeeAnnexAformoreinformationonthesedocuments. 5

6 FloodZone3.IncorporationofthemeasureswithinthisdocumentwillassistinmeetingpartCofthe PPS25 Exception Test, making development safe, without increasing flood risk elsewhere and reducingriskoverall. Rather than trying to justify development within Zone 3b (Functional Floodplain) on a site by site basis,thismoreflexibleapproachtodevelopmentwithinthewholeoffloodzone3,offersachance to manage flood risk in the Guildford Urban Area at a strategic level and in a more consistent manner.asaresult,redevelopmentinthefloodplainwillprovideanetreductioninfloodriskfor thepeopleandpropertiescurrentlyinfloodzone3inguildfordurbanarea. This corresponds to an increase in people s safety, and a reduction in economic damages to property,providingsocial,economicandenvironmentalbenefitsinguildford. ThisuniqueagreementwiththeEnvironmentAgencyonthedefinitionofthefunctionalfloodplainin Guildford Urban Area requires everyone to follow the advice contained in this document. If the Council or the Environment Agency believes this advice has not been adhered to, the agreed definition of the Functional Floodplain cannot be used. This may result in an objection to the planning application from the Environment Agency and Guildford Borough Council with the subsequentrefusalofplanningpermission. The extent of Guildford Urban Area is shown on the Local Plan (2003) proposals maps and is the boundaryusedinreferencetothisdocument(seepage16ofthisdocumentforamapofguildford Urban Area). The text of the Local Plan (2003) can be viewed on the Council s website at Hard copies of the proposals maps can be viewed at the Council splanninghelpdesk,atthemillmeadoffice,guildford.thefloodzonesreferredtointhis documentarethecurrentfloodzonesataugust2010.itisadvisabletocheckiftherehavebeenany updates since this date using the Environment Agency s maps online ( agency.gov.uk/homeandleisure/floods). Detailed datasets are also available from the Environment Agency. ThisapproachwillinformprogressionoftheCouncil scorestrategy.thelatestversionofthecore Strategycanbeviewedonlineatwww.guildford.gov.uk/corestrategy. Whenwillthisdocumentbeusedandbywhom? Thisdocumentwillbeusedbythoseconsideringsubmittingaplanningapplicationfordevelopment within Flood Zone 3 in Guildford Urban Area.It is also aimed at householders whose property is currentlywithinthisareaandwhowishtoinvestigatewhichresistanceorresiliencemeasures 66could beemployedtoreducetheconsequencesofflooding. Consultants preparing a Flood Risk Assessment (FRA) are advised to consider all potential options listedwithinthisdocumentforinclusionwithinthefratoensuretheconsequencesoffloodingon site,andelsewhereifpossible,arereduced. 6 Resistancemeasuresaimtopreventfloodwaterenteringthebuildingandcausingdamage(forexampledoorguards). Resiliencemeasuresminimisethedamagethatiscausedbyfloodswhichenteraproperty(forexamplewaterproofwall plaster). 6

7 Those seeking planning permission are advised to liaise with the Council and the Environment Agencyattheearlystagesofpreparingaplanningapplication.Preapplicationadvicecanbesought fromthecouncilandtheenvironmentagency,usingthecontactdetailsonpage34. Howwasthisdocumentprepared? AsakeystakeholderinthedeterminationofplanningapplicationsandthepreparationoftheSFRA, theenvironmentagencyhasanimportantroletoplayinassistinglocalauthoritiesinachievingthe objectives of PPS25. This document has, therefore, been prepared in partnership with the Environment Agency and is recognised by both organisations as sound evidence informing the preparationofthegdfandthedeterminationofplanningapplications. Drawing on the expertise of the Council s planning policy, development control and engineering officers, and the Environment Agency s expertise from development and flood risk, regional flood risk management, asset system management and planning liaison, this document has been produced by all of the aforementioned in partnership during a series of workshops. Any future updates to this document will be made by the partnership group established. This is the second publishedversion(seeannexbfordocumenthistory). Thecontextofthisdocumentinaccordancewithotherdocuments Figure1showshowthisdocumentrelatestootherworkpreparedbytheEnvironmentAgencyand thecouncil.seeannexaforanexplanationofthetermsused.alsoseeappendixa1ofthesfra (volume1)forhowthesfralinkswithotherplansandpolicies. 7

8 Figure1ReducingFloodRiskinGuildfordUrbanArea(seeAnnexAforanexplanationofterms) GuildfordBoroughCouncilEnvironmentAgency GuildfordDevelopmentFramework(GDF) (LocalDevelopmentFramework) ThamesCatchmentFloodManagementPlan (CFMP) Strategicpolicies(CoreStrategy),development GuildfordPolicyUnit GDFevidencebase:FloodRisk managementpoliciesandsiteallocations Flood ReductionMeasuresdocument Floodriskreduction GDFevidencebase:StrategicFloodRisk measures Assessment(SFRA) SitespecificFloodRiskAssessment(FRA) carriedoutbydevelopersandsubmittedas partofaplanningapplicationwhererequired Reducedfloodrisk (probabilityand consequence) RiverWeyFloodRiskManagementDraft Strategy2010 FloodRiskManagementMeasures(Structural andnonstructural) 8

9 FloodRiskinGuildfordUrbanArea GuildfordisanestablishedriversidetownandthelargesturbanareaalongthecorridoroftheRiver Wey.Ithasaheavilydevelopedfloodplain,withbothcommercialandresidentialdevelopmentbuilt uptothebanksoftheriver(seefigure2cforamapofthelandusesinfloodzone3inguildford TownCentre).Thefloodplainisflatbutconstrainedbythesurroundingtopography.Therefore,for thelargerfloodevents,theextentofthefloodingdoesnotsignificantlyincrease.insteaditisthe depthoffloodingthatchanges.thereareapproximately620propertiesatriskfroma1in100year eventwithinguildfordurbanarea. TheprinciplefluvialwatercourseistheRiverWeywhichflowsthroughthetowncentre.Thisincludes theweynavigation,whichisacombinationofnavigableriverandmanmadesectionsmaintainedby thenationaltrust. TheprimarysourceoffloodingwithinGuildfordisfromfluvial(river)floodingfromtheRiverWey althoughsurfacewaterflooding,groundwaterfloodingandfloodingfromlanddrainagesystemsand sewers can also be locally significant. Any further development could potentially increase surface waterrunoffsifnotdesignedcorrectly. ManagingandreducingfloodriskisapriorityforGuildfordBoroughCouncilandtheEnvironment Agency. A bypass tunnel has been considered in Guildford, but is a high risk option that is not economically viable and will become less effective with flow increases due to climate change 7. In addition, the solution, involving the construction of a tunnel, would not be the best option environmentally. Consequently,ourfocusisonreducingtheconsequencesofflooding.Wherepossiblewealsowant toensurethatwereducetheprobabilityoffloodsoccurringthroughprovidingadditionalfloodwater storageandimprovingfloodwaterflows.astheurbanlandscapeofthetownchangesweneedto: makeitasaferplacetolive, reducethetimeandcostofrecoveryafterafloodingevent,and enhancetheriverweyenvironmentforwildlifeandrecreation. To achieve these aims we have developed this plan for future development and land use in the floodplain in Guildford Urban Area. We have considered the floodplain through Guildford Urban Areaandits contentsasawholeratherthanlookingatitonasitebysite basis,ashasbeenour practiceinthepast.thishasallowedustoidentifystrategicprinciplesforhowandwherewewant tobringaboutthegreatestchangeinthefuture. SurfaceWaterFlooding Surface water flooding was recorded in the Guildford Urban Area during the flood events of November2000,August2006andJuly2007.ThemaincauseofthefloodinginJuly2007wasfrom thehighwayduetodrainsbeingoverwhelmedbylargevolumesofrainfallinashorttimespan. 7 RiverWeyFloodRiskManagementDraftStrategy2010PublicConsultationDocument 9

10 TheEnvironmentAgencyisduetopublishdetailedsurfacewatermapsbytheendof2010.These can be obtained from the Environment Agency once completed. Surface water flooding can be causedbyanisolatedincidentsuchaspoorlymaintaineddrains,culvertsandgullies.itisdifficultto predictsucheventsbymodellinginthesamewayasfluvialflooding.thesurfacewatermapshave been created using ground modelling and on the ground inspections for verification. Only on the groundinspectioncandeterminewhereproblemsarelikelytooccurduetolackofmaintenance. Groundconditionscanalsoaffecttheextenttowhichsurfacewaterfloodingcanbecomeaproblem. Inthesummersof2006and2007,flashfloodingcausedbyheavyrainoverashortperiodoftime occurred in the Guildford Urban Area. Ground conditions inaugust 2006 after a long dry period, meantthatsurfacesweredryandhard.injuly2007thesoilwasalreadysaturatedwithwaterdueto highrainfalltotalsinmayandjune.extremelyhighrainfalltotalsandintensitiesthenfellonalready saturatedsoilsonthe19thand20thjuly2007.asaresult,inboth2006and2007,therewasless soakageandinfiltrationofsurfacewaterintogreenfieldsites.consequentlythevolumesofwater flowingovergroundanddirectlyintosurfacewaterdrainagesystemsincreased.nofluvialflooding wasexperiencedfromtheriverweyinguildfordurbanareain2006or2007. In January 2008 the opposite scenario occurred. Continuous heavy rain caused the River Wey to comeoutofbankinthemillmeadareaofthetowncentre.theextentofthefloodingonlyaffected riverside car park areas and no properties were flooded. There was no surface water flooding in January2008.Groundconditionsweresoftandnotfullysaturatedsomuchoftherainfallsoaked intothegroundandenteredstreamsthatflowintotheriverwey.thiscausedtherivertoswelland consequentlycomeoutofbankatmillmead. ThemaintoolformanagingsurfacewaterfloodingthroughdevelopmentisviaaSustainableUrban DrainageSystems(SUDS)approach.DetailsofSUDSsystemscanbefoundinfigure5.Avarietyof techniques are available for reducing runoff rates from a site, but many of these require early considerationinthedevelopmentproposals.forexample,greenroofs,permeablepaving,balancing ponds and a host of other SUDS features, can be used together to attenuate and convey water betweendifferentfeatures.theyslowdowntheflowofwatertosewersandwatercoursesduring rainfallandcanprovideadditionalamenity,waterquality,waterresources,natureconservationand evenenergyefficiencybenefits.whensudstechniquesareusedbeforesurfacewaterdrainsintoa sewerorwatercourse,theexistingsurfacewaterdrainsarelesslikelytobecomeoverwhelmed.itis importantthatownershipandregularmaintenanceisarrangedatanearlystageofthedevelopment toensuresudssystemscontinuetofunctionasintended. CriticalInfrastructure GuildfordPoliceStationislocatedwithinFloodZone3andGuildfordFireStationisjustoutsideof Flood Zone 3. Many of the major roads which link Guildford Urban Area with other parts of the boroughcouldpotentiallybeblockedduringafloodevent.thisincludestheroutebetweenthefire station and Royal Surrey Hospital. The main road between Guildford Urban Area and the Royal SurreyHospitalispronetofloodingfromhighwaydrainsbeingoverwhelmed.ItisalsoinFloodZone 3. Many of the churches which have been identified as emergency shelters during nonflood emergenciesareinfactinfloodzone3,andtherefore,couldnotbeusedduring1in100yearreturn 10

11 periodfloodevent.thereareanumberofotheremergencyrestcentresthatdonotfallintheflood Zonewhichcouldbeaccessibleinanemergency.ThemainrailwaylinesinGuildfordUrbanAreaare elevatedsowouldnotbeaffectedbysuchafloodevent.manyelectricitysubstationsaresituated withinfloodzone3sopotentiallyelectricitysuppliescouldbeaffectedwithintheguildfordurban Area. The Council is currently preparing a Multi Agency Flood Plan which details how the Council will supporttheemergencyservicesduringaseverefloodevent. Currentlanduses reducingfloodriskthroughredevelopment To help us understand how we need to manage flood risk in Guildford, we have looked at the floodplain according to the current (see figure 2b) and potential future land use (based on initial workings from the Guildford Development Framework). To inform us about where the greatest changes in Guildford s river corridor and urban environment are required, we have combined existinginformationonlandusetype,floodriskandtheconsequencesofflooding. Different flood risk reduction measures will apply to different areas, depending on the type of development.foreachdevelopmenttypethereisapotentialproposalgivenasanexampleofwhat wewanttoachieve.asredevelopmentofsomeoftheseareascanassistinreducingfloodrisk,any site that comes forward in the future can be classified according to the categories belowand the relevantguidanceapplied(seefigures4and5formoredetails). As a general principle, along the stretch of the River Wey that flows through the Town Centre, settingdevelopmentbackfromtheriverwillprovidemorespacetoaccommodatewaterduringa flood.creatingadditionalfloodplainstoragehasmultiplebenefitsincludingreducingthefrequency offloodingtotheadjacentdevelopment,providingpossiblecommunitybenefitbycreatingpublic accesstotheriverside(dependingonsitedesign)andalsoimprovingthenaturalriverenvironment through landscaping opportunities. Our target is thatwhen asite is redeveloped, the new buildingshouldnotbeanycloserthantheexistingbuildingfootprintandshouldbesetbackatleast 8metres(andmorewherepossible)fromtheriver. Undevelopednaturalfloodplain These are areas where the basic floodplain function remains intact and there are no significant buildings. Open land uses such as playing fields and parkland are permitted with only necessary essentialinfrastructureorwatercompatibledevelopmentensuringthereisnolossoffloodplainor obstructionoffloodplainflows. TheseareasareshownasArea1andArea2infigure2b(p.17).Theyarethefieldstothenorthof the A3 (Area 1 over 20Ha/0.2km) and Shalford Meadows (Area 2), an extensive area of undevelopedfloodplaintothesouthofthetowncentre. Thepriorityhereistosafeguardundevelopedfloodplainforfloodstoragepurposes.Thiswillensure thatthefloodplaincontinuestoprovidefloodriskbenefitslocallyandalsofurtherdownstream. 11

12 Nonresidentialredevelopment Industrialareasconsistingofwarehouses,workshopsandstorageuseshavehighconsequencesin termsofeconomicdamages.thesehavebeenidentifiedashighprioritybecauseredevelopmentof thesesitescanprovidealargereductioninthetotalpropertydamagesinguildfordtowncentre. Forexample,WalnutTreeClose,highlightedasArea3infigure2b,containsanumberofindustrial propertiesthathaveveryhigheconomicdamagesduetotheiruseandfloorarea. The aim for nonresidential redevelopment is to reduce overall flood risk within these areas and beyond.theprobabilityoffloodingcanbereducedbycreatingspaceforfloodingtooccurwithina site.methodsincluderestoringfloodplainandfloodflowpathways,settingpropertiesbackfromthe watercourse,raisingfloorlevelsandbyidentifyingopenspaceforfloodstorage 8 whichcreatespace forfloodingtooccursafely.carparks,ifdesignedappropriately,cancontributetothesegoals. Anyredevelopmentofthesesitesalsoprovidesanidealopportunitytoreducetheconsequencesof flooding. This can be done through layout and design. For example incorporating appropriate resistanceorresiliencemeasures,dependingonhowfrequentlythesitefloodsandtowhatdepth. Seefigures4and5formoredetailaboutindividualresistanceandresiliencemeasures. Permanentresistancemeasuresarepreferablehereratherthantemporaryonestoavoidissuessuch as incorrect deployment (who is responsible, training requirements, staff turnover) and ability to deploy (flooding may occur outside of working hours). Additional investment in permanent resistance(e.g.permanentfloodproofdoorsandwindows)reducesthecostsofdamagebybetween 65%and84%perpropertycomparedtoabout50%fortemporarymeasures 93. Our target is to reduce property damages to individual properties by employing a range of risk reduction measures, as described above, depending on what is most appropriate on site. As an example of what could be achieved, if all new nonresidential development in Area 3 was either floodresistantupto0.6metresorresilientupto2metres(dependingontheaverageflooddepth for each area), this could reduce the total property damages in Guildford Urban Area by approximately15%forthe1in10yearfloodevent. Increaseinresidentialunits Thesecommentsapplytoareaswhereanintensificationofresidentialuseisproposed,forexample, replacingarowoftownhouseswithflats.itequallyappliestothesplittingofoneresidentialunit intomultipleseparateunits. Therisktolifeandpropertyarethetopprioritiesfortheseformsofdevelopment.Consequently,the identificationofpotentialopportunitiestorelocateexistingmorevulnerablepropertiestoanareaof lower flood risk, ideally outside the floodplain, must be sought. For example, the swapping of a residentialsiteinfloodzone3withacommercialsiteinfloodzone2(landswapping). 8 SeePPS25PracticeGuide(CLG,2009)forusefulcasestudies. 9 Developingtheevidencebaseforfloodresistanceandresilience:summaryreport(JointEA/DefraR&DSummaryReport, June2008). 12

13 Whereitisnotpossibletorelocatetoareasoflowerrisk,carefulconsiderationtothedesignand layout will be required. The aim is to provide a development which is safe to occupy and escape frominafloodevent,whilstreducingfloodrisktoothers. Forthistobeachieved,newbuildingsshouldbelaidoutanddesignedsothatnopropertieswillbe inundatedbyfuturefloodevents(i.e.allpropertiesaremaderesistant),futureresidentshavesafe accessandegresstotheirhomes,and also,thatthewiderurbanenvironment(streetscape,open spaces,carparking)isdesignedtoberesilienttoflooding. Ascarsareeasilymovedpriortoafloodevent,givensufficientwarning,damagestocarsshouldbe considered in emergency plans for residential sites. Where residents parking is provided on the ground floor of a development, there must be measures to prevent them being swept away in a floodevent. Mixeduseredevelopment Areaswheretherecurrentlyismixedusedevelopmentandanypotentialredevelopmentislikelyto contributetothatmix,consistingofbothresidentialandcommercialusesinthearea. AnexampleofthisistheareamarkedasArea4infigure2bwheretherearecommercialuses(for examplethebusdepotandpembrokehouse)butalsoresidentialuses(forexampleleasroadand MaryRoadarea).Allofthesepropertiesshouldbeconsideredaspartofanyredevelopmentofthe area around the bus depot to achieve an overall increase in the resilience of the local area to flooding. Theobjectiveintheselocationsistoreducerisktolife,reducepropertydamagefromthecurrent estimatedamount,andincreasethespeedatwhichpeoplecanreturntotheirpropertiesfollowinga flood.thiscanbeachievedbyfollowingthespecificguidancesetoutinthisdocumentforthistype ofdevelopment.forexample,byapplyingthesequentialtestatasitelevelorintroducingresistance andresiliencemeasuresaspropertiesareredevelopedorrefurbishedbyindividualpropertyowners. InthecaseoftheBusDepotandsurroundingareas,thisisanideallocationtoincreasetheresilience ofanareaofthetowntoflooding.asaminimumwewouldrequireallnewpropertiesheretoeither befloodresistantupto0.6metresorresilientupto2metresdependingontheaverageflooddepth. Ascarsareeasilymovedpriortoafloodevent,givensufficientwarning,damagestocarsshouldbe considered in emergency plans for residential sites. Where residents parking is provided on the ground floor of a development, there must be measures to prevent them being swept away in a floodevent. Redevelopmentthatincludesachangeofusetoamorevulnerablelanduse Thisrelatesspecificallytositeswhereredevelopmentwouldresultinachangeofusethatwouldbe considered highlyvulnerable or morevulnerable development. For example, this would be the case should redevelopment of the car park in Mary Road be considered(shownasarea5infigure2b). Where this type of redevelopment is shown to be necessary to progress in accordance with the GDF,itwillneedtocomplywithallmaterialplanningconsiderations.TheSFRA(volume1)provides 13

14 useful decision support information to assist in determining whether a development will be safe. Developmentneedstobedesignedtobesafewithbothsafeaccessandegress.Thedeveloperwill need to show that future users of the development will not be placed at risk from flood hazards throughout the lifetime of the development (taking into account climate change). Mitigation measures will be needed and developers should ensure that appropriate evacuation and flood response procedures are in place. Where possible, developers should also demonstrate flood risk benefitstonearbyproperties. Theobjectiveintheselocationsistoreducerisktolife,reducepropertydamagesfromthecurrent estimatedamountandincreasethespeedatwhichpeoplecanreturntotheirpropertiesfollowinga flood.thiscanbeachievedbyfollowingthespecificguidancesetoutinthisdocumentforthistype ofdevelopment.resistanceandresiliencemeasuresshouldbeappliedtoallnewbuildingssincethis providesbenefitbothtothedeveloperintermsofreducedreestablishmentcostsfollowingaflood andfortheoccupierintermsofminimaldamagetothepropertyandtheirpossessionsandashorter recoverytime. Ascarsareeasilymovedpriortoafloodevent,givensufficientwarning,damagestocarsshouldbe considered in emergency plans for residential sites. Where residents parking is provided on the ground floor of a development, there must be measures to prevent them being swept away in a floodevent. Existingresidential(noredevelopmentplannedintheshorttomediumterm) This document has identified where, considering the nature of the existing flood hazard, re development would deliver a reduction in flood risk, and could be promoted through GDF policy. Theobjectiveofsuchapolicy,inlinewiththeCatchmentFloodManagementPlan(CFMP),wouldbe to prioritise redevelopment where it achieves a net reduction in flood risk by providing a flood resilient urban environment and safer properties to live in. However, when the age of existing properties is considered and where the likelihood of redevelopment in the next 25 years is low, policiestopromoteresistanceandresilienceduringrefurbishmentofexistingpropertiesshouldbe prioritised. Examples include the Leas Road/Mary Road/Wharf Roadarea where there areapproximately 70 residentialpropertiesinthe1in100yearfloodextentandapproximately75residentialpropertiesin thefloodplainontheothersideoftheriverinwalnuttreeclose. Differentresistanceorresilienceproductscanberetrofittedtothesepropertiesdependingonflood depthsandcostbenefits.forexample,floodresilienceismoreeffectivethanresistancefordeeper floods (above 6090cm) which would overwhelm barriers such as door guards and could cause structuraldamagetothepropertyifthewaterwasheldback. Thelower costofresistancemeasures meantheyarelikely tobeeconomicallyworthwhile,ifthe annualchanceoffloodingis2%ormore(1in50years)fortemporarymeasuresand4%ormore(1 in25years)forpermanentmeasures(astheyaremoreexpensive).tobeeffective,thesemeasures doneedtobeappliedtothewholehouseatoncewhereasresiliencemeasurescouldbeinstalled graduallyovertime,forexamplewhenrefittingakitchenorduringrepairfollowingafloodevent. 14

15 Tointroducepackagesofresiliencemeasuresinhomesnotalreadyinneedofrefurbishmentisonly costbeneficialinareaswitha4%orgreaterannualchanceofflooding 10. Foreveryresidentialpropertyinthe1in20yearfloodplainthatis: (a) inanareawherethemaximumdepthoffloodingis0.6metresorless,homeownersshould looktoinstallpermanentresistancemeasurestoreducepropertydamagesbyupto80%. (b) in an area where flood depths are over 0.6 metres, resilience measures should be incorporatedduringrepairormajorrenovation.whererefurbishmentisnotbeing carried out,theremaybeapossibilityoffundingthroughthedefrapropertylevelfloodprotection andresiliencegrant. TheCouncilwillapplyforthesegrantswhenandiftheybecomeavailable.TheEnvironmentAgency willletthecouncilknowwhengrantsbecomeavailableandopentobids. Guildford Borough Council is actively applying for central government grant funding for flood protectionprojectswithintheborough.althoughoutsideofguildfordurbanarea, 60,000ofDefra funding has already been awarded through the Environment Agency for a 120,000 project to protectthevillageofashgreenfromflooding.theschemeisscheduledforcompletionin2011. Existingcommercial(noredevelopmentplannedintheshorttomediumterm) Propertiesathighriskbutwithlowerconsequences(intermsofcosts)thanthesitesidentifiedin Area3above. Whenredevelopmentopportunitiesariseinthelongerterm(in25yearsormore),looktoreturn these areas to less vulnerable land uses or those that are flood compatible, for example through landswappingopportunities.intheshorttomediumterm,considerretrofittingwithresilienceor resistance measures. For the average officebased business that floods more than once every 10 years,thebenefitsofinstallingresistancemeasuresoutweightheupfrontinvestmentbybetween sixandeleventimes 1112 (overthelifetimeoftheresistancemeasure). 10 consultationonpolicyoptionsforpromotingpropertylevelfloodprotectionandresilience(defra,july2008) 11 DevelopingtheEvidenceBaseforFloodResistanceandResilience.SummaryReport.R&D TechnicalReportFD2607/TR1http://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More& Location=None&ProjectID=

16 Figure2aGuildfordUrbanArea 16

17 Figure2b Locationoflanduse/developmentexamplesinGuildfordTownCentre 17

18 Figure2cPropertyTypewithin1in100FloodOutline 18

19 FloodRiskReductionMeasuresinExistingandNewDevelopmentsinGuildfordUrbanArea RiskReductionMeasuresinGuildfordUrbanArea Theprobabilityoffluvialfloodingcanbereducedbutnevereliminated.Forsustainabledevelopment to take place in towns that are within the floodplain, it is likely that some infrastructure and buildingswillbeatriskfromfloodwater. Forpropertiesvulnerabletoflooding,itisimportanttolimittherisktolife,damagecostsandthe amountoftimethat the propertybecomesuninhabitable.inguildfordurbanarea,implementing flood risk reduction measures has been accepted as the most sustainable way of reducing the consequencesofflooding(seethamescfmpandriverweyfloodriskmanagementdraftstrategy 2010). Therangeoffloodriskreductionmeasuresoutlinedinfigures4and5arebasedonevidencefrom laboratorytests,technicalevidenceandindustryexperience.theyaredesignedtohelpdevelopers identifythebestoptionordesignstrategyformanagingfloodriskatbothapropertyandsitelevel. Thetechniquesthatreducefloodriskandprovideresistanceandresiliencetofloodingcanalsobe retrofittedtoexistingproperties,asdescribedinfigure4.theymust,however,beconsideredforall newdevelopments,asdescribedinfigure5.themajorityofmeasures,particularlyfloodresilience and resistance (also defined as flood proofing) involve any combination of structural or non structuralchangesoradjustmentsincorporatedinthedesign,constructionoralterationofindividual properties that will reduce flood damage. The type of damage which some of the flood risk reductionmeasurescanpreventarelistedinfigure3. Figure3Table2.7Anextractfrom Improvingthefloodperformanceofnewbuildings May2007, Defra,CLGandEnvironmentAgency Depthof Floodwater Belowground floorlevel Damagetothebuilding Possibleerosionbeneathfoundations, causinginstabilityandsettlement Possiblecorrosioninmetalcomponents(e.g. joisthangers) Excessivemoistureabsorptionintimber, causingwarping Crackingofgroundfloorduetouplift pressures Accumulationofcontaminatedsilt Structuralandmaterialweaknessesfrom inappropriatedrying Rotandmould Damagetoservicesandfittings Damagetoelectricalsocketsand otherservicestobasementsand cellars Damagetofittingsinbasements andcellars 19

20 Groundlevel tohalfa metreabove floorlevel Halfametre andabove Buildupofwaterandsiltincavitywalls,with potentialreductionininsulatingproperties, forsomematerials Immersedfloorinsulationmaytendtofloat andcausescreedstodebond Damagetointernalfinishes,suchaswall coveringsandplasterlinings Floorsandwallsmaybeaffectedtovarying degrees(e.g.swelling)andmayrequire cleaninganddryingout Timberbasedmaterialslikelytorequire replacement Damagetointernalandexternaldoorsand skirtingboards Corrosionofmetalfixings Rotandmould Increaseddamagetowalls(asabove) Differentialheadsofgreaterthan0.6macross wallscouldcausestructuraldamage, althoughthiswillvarydependingonthe structureofthebuilding.damagetowindows canbecausedbymuchsmallerdifferential pressures Highspeedflowaroundthebuilding perimetercanleadtoerosionoftheground surface;thereisalsothepotentialriskof damagetothestructurefromlargeitemsof floatingdebris,e.g.treetrunks ExistingDevelopment Damagetowater,electricityand gasmeters Damagetolowlevelboilersand someunderfloorheating systems Damagetocommunication wiringandservices Carpetsandfloorcoveringsmay needtobereplaced Timberbasedkitchenunitsare likelytorequirereplacement Electricalappliancesmayneedto bereplaced Insulationonpipeworkmay needreplacing Damagetohigherunits, electricalservicesandappliances Figure 4 lists some examples of the possible flood resistance and resilience measures that can be retrofittedtoexistingproperties.thesemeasuresmayreducethedamage,costandtimetorepaira propertyifitisflooded. Theprobabilityoffloodingandthelikelydepthofwaterarebothkeyfactorsdeterminingthescale andnatureofthetechniquechosen.thetypeofmeasureselectedwilldependonthedepthofflood wateraroundtheproperty.themaximumreturnperiodforwhichresistanceandresilience measuresarecosteffectiveforexistingpropertiesis1in50years.the1in50floodoutlineis availablefromtheenvironmentagency,however,the1in20floodoutline,asshowninthesfra,is ausefulguideinthefirstinstance. N.B.Theflooddepthsoutlinedinfigure4shouldbetakenasageneralguidespecifiedbytheDCLG Improvingthefloodperformanceofnewbuildings May2007.Forfurtherspecificinformationon flooddepths,pleaserefertotheguildfordsfraannexe. 20

21 GuidanceontherangeofmeasuresavailableandestimatedcostsisavailableontheEnvironment AgencyandDefrawebsites Ifunfamiliarwiththedifferenttechniquesitisrecommendedtoseek professionaladvice. 13 DevelopingtheEvidenceBaseforFloodResistanceandResilience.SummaryReport.R&DTechnicalReportFD2607/TR

22 22 Figure4FloodProtectionMeasuresforExistingPropertyOwners Flood Depth Measure Typeof Measure Description Benefits Design/OperationalConsiderations Over0.6m allfloods which enter property Moving servicesand electrical socketsabove thefloodlevel Permanent Flood Resilience Placefittingssuchaselectrical appliances,utilitymeterswell abovegroundlevelsothatthey areoutofreachoffloodwater Extremelyeffectiveand relativelyinexpensive, comparedtothecostofflood damage Costsnoextraifundergoinga plannedrefurbishment Ensurethatthepropertyiscompletely drybeforeworkingwithelectrics m Resilient Internalwalls Permanent Flood Resilience Wallscoatedwithinternalcement basedrenders;applytankingon theinsideofeveryinternalwall Permanent effectiveifappliedcorrectly Minimisesdamagestowallsand floors Driesquicker(backinproperty sooner) Requiresgoodworkmanship Mustberegularlycheckedand maintained m Resilient floors Permanent Flood Resilience Groundsupportedfloorswith concreteslabscoatedwith impermeablemembrane Permanent,effective relativelyinexpensivecompared todamagecost Requiresqualityproducts Skilledworkmanship Upto0.6m Basementor cellartanking Permanent Flood Resilience Tankingbasements,cellarsor groundfloorswithwaterresistant membranes Permanent,effectiveifapplied correctly.minimisesdamageto wallsandfloors Driesquicker(backinproperty sooner) Canonlybeappliedwhenpropertyis fullydry Useinconjunctionwithresistantdoors andotherresilientmeasures Requiresgoodqualityworkmanshipby specialists All Resilient internaldoors Temporary Flood Resilience Waterresistantplasticdoorsso thatflooddamageisminimised. Canbefittedwithadjustable hingessothatdoorsmaybeeasily Easilyremovable Lightweight Storagemaybedifficult

23 23 removedbeforefloodwaterenters property Upto0.6m Flood resistant /waterproof external doorsand windows Permanent Flood resistance Useofmaterialsandconstructions withlowpermeability Proveninfloods Reducesfloodingressand damage Extensivegroundworkmayberequired Mustnotbeusedinisolation Mayrequireregularmaintenance Upto0.6m Flood resistance gates Permanent Flood resistance Solidgateswithdiscreet waterproofseals Preventsfloodwaterreaching property Triedandtested Veryeffectiveandunobtrusive Mayrequireancillarypump arrangements Regularmaintenancemustbecarriedout Upto0.3m Airbrick covers Temporary Flood resistance Sealedcoversfittedoutsideofair brickstostopingressofflood waterthroughventsintheair bricks Easyandquicktoapply Effective Easytoremove Requiresoccupanttoremovecoverwhen floodsubsides Upto1m LocalBunds Permanent Flood resistance Lowearthbundtoprovidean effectivelocalflooddefence Preventsfloodwaterreaching property Communityprotection Suitablewherethiswillnotimpacton floodwaterflowsorstorage Mayneedtoprovidepumping arrangementstoremovepotential rainwaterorfloodwaterseepage. Mayneedtoincorporatefloodresistant gates Willrequireexpertengineeringdesignto ensurebreachingwillnotoccur Willrequireassessmenttoshowthat floodriskisnotincreasedelsewhere Mayrequirefloodplaincompensation Upto0.3m Sumpand Pump Permanent Flood resistance Asystemwhichcouldbeinstalled fordomesticpropertiessothat floodwatermaybepumpedaway fasterthanitenters Iffittedcorrectly,andof sufficientcapacity,canremove floodwaterinanemergency Mustbepositionedandsizedcorrectly Mayrequireexternalorancillarypower supply

24 Upto0.3m Upto1.2m StormPorch Boundary Wallsand fencing Permanent Flood resistance Permanent Flood resistance Constructing porches to provide an added barrier to flood water reaching the front or back door. Theporchesarebuiltwithahigher door step level than the existing entrance Designedtocreatefloodresistant barriers.solidgateswithdiscreet waterproofseals,orfencingwhere thelowerelementsare constructedtobemoreresistant toflooding Costisequivalenttoastandard porch Rampscanbebuiltfordisabled access Unobtrusive Designedtocompliment propertydesign Preventsfloodwaterreaching property Gatesaretriedandtested veryeffective modern,aestheticdesigns unobtrusive Moreeffectiveifwaterresistant materialsweretobeused. Requiresgoodworkmanship Mayneedsimilarworkatrearof property Mayaffectfloodrisktoneighbours Requiresregularmaintenance All All All Rainwater Harvesting Permeable Paving Onsite attenuation (e.g. Detention basinsand ponds) Permanent Sustainable Drainage System Permanent Sustainable Drainage System Permanent Sustainable Drainage System Captureofrainwaterfromroofs, andreusingfordomesticpurposes Infiltrationofsurfacewater throughthehardstandinginto underlyinglayer Onsitestoragetechniques, usuallyaboveground,designedto capturesurfacewaterrunoff Reductioninthevolumeand rateofstormwaterrunoff Additionalbenefitofachieving waterefficiencyinnew buildings Reductioninthevolumeand rateofstormwaterrunoff Systemallowsfor sedimentation,filtration, adsorption,biodegradationand volatilisationofpollutants Providestormwater attenuationandvolume reduction Pollutantremovalvia adsorptionandbiodegradation Providegreenopenspace Fordetaileddesignrequirements,refer tociriac609 Fordetaileddesignrequirements,refer tociriac609(section3.6inparticular) Fordetaileddesignrequirements,refer tociriac609 24

25 25 All Improving Flood Warning Permanent SignuptothefreeFloodline WarningsDirectserviceoperated bytheenvironmentagencyby callingfloodlineon orapplyingonthewebsite: agency.gov.uk/floodline Saveslivesbyproviding advancewarningofaflood eventsopeoplecanevacuate propertiesandfindsafeshelter Providesvitaltimetoput damagepreventionmeasuresin place,shoulditbenecessary, suchasstoringvaluables, sentimentalitemsand importantdocumentsupstairs orwellaboveexpectedflood levelsandinstallingtemporary resistancemeasures Requiresanawarenessofwhatthe differentlevelsoffloodwarningareand whattheappropriateactionistotake Doesnotincludesurfacewaterflooding duetothespeedatwhichitcanoccur andtheunexpectedplacesthatcanbe affected All Emergency Planningand response Permanent Ensureyourhouseholdhasan emergencyfloodplaninplaceso youknowwhatactiontotake afterreceivingafloodwarning. Thisinvolvespreparingafloodkit ofessentialitems(e.g.torch, bottledwater,firstaidkit), knowinghowtoturnoffgas, waterandelectricitysupplies, whatpossessionsneedtobe movedabovethefloodleveland knowingwhotocontact. Beingpreparedsaveslivesand reducesthedamagetoyour propertyandpossessions Theremaynotbethetimeavailableto returntoyourhouseandimplementthe planbeforetheonsetoffloodingoccurs

26 NewDevelopments Developmentpressurein Guildford TownCentreandthesurroundingurbanareaisincreasing. As themainsettlementintheborough,thetowncentreisafocalpointfornewdevelopment,andan importantlocationforsustainablegrowth. Much of Guildford has a heavily developed floodplain, where flooding from the River Wey occurs frequently.floodriskisalsopredictedtoincrease.duetochangingweatherpatternsitislikelythat we will see increasing winter river flows and more frequent and intense summer rainfall. This, coupledwiththecompetingdemandforlandintheurbanareawithinandaroundguildfordtown Centremeansthatanacceptanceofsomeleveloffloodriskisnecessary. SubjecttotheSequentialTest,andtheExceptionTest,redevelopmentcanoccurinFloodZone3.It has,however,beenagreedthatsuchaflexibleapproachtothefunctionalfloodplaininguildford Urban Area will not be employed until complementary flood risk reduction measures are implemented. Figure5outlinesarangeoffloodriskreductionmeasureswhichcouldpotentiallybeappliedtopass part C of the PPS25 Exception Test. For the purpose of this document, the flood risk reduction measuresareallocatedaccordingtothelandusetype(asoutlinedinfigure2bandcorresponding text).pps25practiceguide:december2009shouldbeusedtosupplementtheinformationinfigure 5. Thetableprovidespossiblemethodswithadviceonthebenefitstheycouldbring.Itisnotnecessary toincludeallmethodslistedunderarequiredriskreductionmeasurehoweverthetableindicates whichareessentialfordifferentdevelopmenttypes.somemeasureswillbebeneficialdependingon theindividualsitedesign.thisisindicatedinthetable.theframustaddresswhichmeasureshave been included and the reasoning for this. A FRA must show that all possible flood risk reduction measureshavebeenconsideredandasatisfactoryamountincludedinthedevelopmentproposal. The Environment Agency and Guildford Borough Council shall jointly decide whether all possible floodriskreductionmeasureshavebeenincludedinthefra. ThefloodriskreductionmeasuresinFigure5shouldbeworkedthroughasdevelopmentproposals areprepared.somemeasuresneedtobeconsideredattheearlystagesofthedesignprocessand would be difficult to address retrospectively. It is advised that each flood risk reduction measure listedinfigure5isconsideredandincorporatedintothedesignprocessasrequired. NB: Guidance on the range of measures available and estimated costs is available on the EnvironmentAgencyandDefrawebsite 15. If unfamiliar with the different techniques it is recommended to seek professional advice. 15 DevelopingtheEvidenceBaseforFloodResistanceandResilience.SummaryReport.R&DTechnicalReportFD2607/TR

27 27 Figure5RiskReductionMeasuresforNewDevelopment Development Proposal FloodRisk Reduction Measures/ Approach Description Requirements Whentoinclude Benefits F=FloodRisk EC=Environment& Community P=PropertyOwner *Dependingondesign AllRedevelopment Allredevelopment Sustainable DrainageSystems (SUDS) Techniqueswhichcan eitherincreasesurface waterattenuationor encourageinfiltrationand reducetherateofsurface waterrunoff Permeablepaving,infiltrationtrenches,swales,wetlands,rainwater harvestingandgreenroofsallcontributetosustainabledrainage design Thesesystemsreducetheamountofwater,ordelaywater,entering riversinthebuilduptoaflood Essentialforall development F,EC*,P* Allredevelopment Nonstructural ImprovingFloodWarning Encourageallresidentsand businessestosignuptotheflood WarningsDirectserviceoperatedbytheEnvironmentAgency Warningprovidestimetoprepareforaflood,includingsettingup temporarydefencemeasuresandmovingvaluables Essential F,EC,P Allredevelopment Nonstructural EmergencyPlanningand response Ensurerobustemergency(evacuation)plansareimplementedfornew developments Anemergencyplanassistspeopleinreactingtoafloodwarning, allowingtherightactionstobeundertakenattherighttimes Essential F,EC,P

28 28 Allredevelopment MakeSpacefor Water Maintainandimprove floodwaterflows Removeboundarywalls,orreplacewithotherformsof enclosure/screening(hedgesorfencingwithgapsallowingflood waterflows) Makeprovisionsforthedevelopmenttoallowfloodwatertoflowor providediversionroutes Essentialforall development F,EC* Allredevelopment FloodResistant Construction Techniqueswhichaimto reducetheamountof waterthatentersa propertyandmaintains theproperty sstructural integrity Wherepossible,raisethefinishedfloorlevel sothattheundersideof thesuspendedflooris300mmabovethe1in100withclimatechange floodwaterlevel(dataavailablefromtheenvironmentagency)this willallowfloodwaterwithdebristofloweasilyunderthebuilding duringafloodmaximisingfloodstorage,thisisthemosteffectiveway ofprotectingapropertyfromflooding.ifthiscannotbeachievedthen evidencemustbeprovidedinthefra.. Thesetechniquespreventthedisruptioncausedbyfloodwater enteringaproperty: Constructingporchestoprovideanaddedbarriertofloodwater reachingthefrontorbackdoor.buildwithahigherdoorstep levelthanthemainentrance Installfloodresistant,solidgateswithdiscreetwaterproofseals Lowearthbundtoprovideaneffectivelocalflooddefence Sumpandpumpforfloodwatertoextractwaterfasterthanit enters Mustbeconsidered alongsideflood Resilient Construction MeasuresA combinationmay bethebestsolution F,P Allredevelopment andchangeofuse FloodResilient Construction Methodswhichallow floodwatertoenterthe building,buttheamount ofdamagecausedbyany waterreduced,dueto gooddesignandfittings. Maybemoreappropriate Thesemeasuresallowsthepropertytobecomefullyusablefar quickerafterafloodevent: Raisedfittingssuchaselectricalappliances,utilitymeterssothey areoutofreachoffloodwater. Wallscoatedwithinternalcementbasedrenders;applytankingon theinsideofeveryinternalwall Groundsupportedfloorswithconcreteslabscoatedwith Mustbe considered alongsideflood Resistant Construction MeasuresA combinationmay F,P