Strategic Flood Risk Assessment - South Worcestershire ...

SUDS and the development site:SUDS TypePotentialSuitabilityCommentsSource ControlInfiltrationDetentionFiltrationConveyanceMost source control techniques are likely to be suitable. Permeablepaving is unlikely to be suitable due to high risk of groundwaterfloodingMapping suggests underlying soil is likely to be permeable.However, the high risk of groundwater flooding would makeinfiltration unsuitableMapping suggests that the site slopes are suitable for all forms ofdetentionFiltration techniques may be suitable if a non-permeable liner isprovided to prevent the ingress of groundwaterMapping suggests that the site slopes may not be suitable for allforms of conveyance. Further investigation or ground work would beneed. A non-permeable liner may also required on systems toprevent the ingress of groundwater.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 zone.Residential developments should provide at least two independent SUDS features inseries to provide a suitable level of water quality treatment.Flood Defences:None.Effects of Climate Change:Increased rainfall intensity. Increase water levels in unnamed watercourse.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.Development of the site is proposed to focus on residential uses.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 development.Assessment for runoff should include allowance for climate change effects.New 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 site falls within an area indicated to potentially be susceptible to groundwateremergence. Further assessment of groundwater risk would be required and anassessment of suitable surface water mitigation techniques should be made at thedetailed FRA level.Station Road, the main access road to the site, is at risk from fluvial flooding.Suitable alternative access arrangements away from the floodplain will need to beinvestigated further.Demonstration that development at this location can be made safe.2012s5947 S Worcestershire Level 2 SFRA Update FINAL Report v1.0.doc 150