Strategic Flood Risk Assessment - South Worcestershire ...

Estimated Attenuation Storage Volume (m 3 ) 190 – 272SUDS and the development site:1 in 100 year (plus climate change) 19.3SUDS TypeSource ControlInfiltrationDetentionFiltrationConveyancePotentialSuitabilityCommentsAll forms of source control are likely to be suitableMapping suggests high permeability at this site, site investigationsshould be carried out to assess potential for drainage by infiltrationMapping suggests that site slopes are steep and detention storage‘above ground’ may therefore not be viableMapping suggests that filtrations would be suitable but require a formof liner to prevent ingress of groundwater into the SUDS systemAll forms of conveyance are likely to be suitableFlood Defences:None.This site is located within a flooding hotspot so all efforts should be made tominimise the rate and volume of runoff leaving the site.The site is not located within a groundwater source protection zoneResidential developments should provide at least two independent SUDS features inseries to provide a suitable level of water quality treatmentEffects of Climate Change:Increased rainfall intensity. Increased water levels in the unnamed tributary of the River Avon.Flood Risk Implications for Development:All development should be located within Flood Zone 1, unless appropriate inaccordance with NPPF Technical Guidance.A detailed site-specific flood risk assessment, including hazard mapping, will berequired for any development in Flood Zone 2, or for sites greater than 1ha in FloodZone 1.Proposed for residential use.Resilience measures will be required if buildings are situated in the flood risk area.Green infrastructure should be considered within the mitigation measures for surfacewater runoff from potential developmentAll development should be located within Flood Zone 1, unless appropriate inaccordance with NPPF Technical Guidance.Assessment for runoff should include allowance for climate change effectsNew or re-development should adopt exemplar source control SUDS techniques toreduce the risk of frequent low impact flooding due to post-development runoff.Onsite attenuation schemes would need to be tested against the hydrograph of thereceiving watercourse to ensure flows are not exacerbated downstream within thecatchment.The High Street and King’s Way, the main access roads to the site are at risk fromboth fluvial flooding and \ or surface water. Suitable alternative accessarrangements away from the floodplain will need to be investigated further.Demonstration that development at this location can be made safe.2012s5947 S Worcestershire Level 2 SFRA Update FINAL Report v1.0.doc 131