Strategic Flood Risk Assessment - South Worcestershire ...

FRAs for proposed development in the South Worcestershire area should follow the approachrecommended by the NPPF and associated guidance, and guidance provided by theEnvironment Agency.These documents describe when an FRA is required and are commensurate with the advicegiven in this SFRA Update. All proposed development sites require an initial assessment offlood risk. A detailed FRA will be required for all developments that fall into the medium and highflood risk zones and other sites where significant flood risk is identified. A FRA will also berequired for sites in Flood Zone 1 which are greater than one hectare, concentrating on themanagement of surface water through an appropriate drainage strategy.8.4 Preplanning guidance for developersEarly consideration of flooding and drainage issues in important. The flood risk at a site and thetype of development that would be appropriate should be considered prior to site acquisition.The requirements for flood storage, above ground surface water attenuation and SUDS shouldalso be considered. Developers should consider:Desk studies, site investigations and surveysDevelopment layout8.5 Mitigation measuresMitigation measures should be seen as a last resort to address flood risk issues. Considerationshould first be given to minimising risk by planning sequentially across a site. Once risk hasbeen minimised, only then should mitigation measures be considered.The fact that mitigation measures are discussed in this SFRA should not be taken as apresumption that the Sequential Test has been bypassed. It is included to give a fuller picture ofthe implications of allocating a site, and for use in a subsequent SA. Normally, suitablemitigation measures for a proposed development will be determined through assessment of flooddepths via hydrological and hydraulic modelling (or use of existing models) carried out as part ofa FRA.Often the determining factor in deciding whether a particular development can or cannot proceedis the practical feasibility and financial viability/feasibility of flood risk mitigation rather thantechnical limitations. Detailed technical assessments are required in the FRA to assess thepractical feasibility, together with a commercial review by the developer of the cost of themitigation works. At the SFRA stage, broad assumptions are therefore required regarding thefeasibility of flood risk mitigation to ensure that only sites with realistic development potential areput forward.Some mitigation measures were outlined in the previous guidance (PPS25) and are presented inFigure 8-1. It is assumed that floor level raising will continue to be the traditional mitigationmeasure. It should be noted that the Environment Agency see actual land raising as a lastoption. Thought will also be required to ensure safe access and egress is available for floodevents including climate change. The Emergency Services should be consulted on theevacuation and rescue capabilities and any advice or requirements included.There should be no interruption to flood flows or loss of flood storage as a result of any proposeddevelopment. Flood storage compensation may be appropriate for sites on the edge of theexisting floodplain. Modification of ground levels/compensation works may re-configure thefloodplain but should not be used to increase land available for development.Whilst flooding mitigation measures can be implemented in most sites, it is worth noting that insome instances the findings of individual FRAs may determine that the risk of flooding to aproposed development is too great and mitigation measures are not feasible. In these instances,the development will be subject to an objection by the Lead Local Flood Authority (LLFA) or theEnvironment Agency.2012s5947 S Worcestershire Level 2 SFRA Update FINAL Report v1.0.doc 173