Strategic Flood Risk Assessment - South Worcestershire ...

Sources of Flood Risk:The main source of flood risk to the site is from surface water, shown to inundate alarge central portion of the site. Further development and creation of impermeablesurfaces may result in an increase of surface water flood risk.The central and western portion of the site falls within Flood Zone 3b. Primary fluvialrisk is to the central and western portions of the site resulting from overtopping of theunnamed tributary of Hadley Brook. The central and western portion of the site fallswithin the Blue Zone of the Policy Maps.Surface Water Drainage:As an indication of requirements to manage surface water runoff at the development site anassessment of the soil types, greenfield runoff rate and attenuation storage volume is includedbelow. Storage volumes displayed are calculated with an assumption that 75% of the site will bedeveloped impermeable ground. A 25% increase in rainfall depths has been included torepresent predicted future climate change effects.PLEASE NOTE: This assessment has been carried out using broad-scale datasets and aims toprovide an indication of the likely opportunities and constraints for this development site. Adetailed drainage assessment based on site-specific conditions should be carried out by asuitably qualified professional and submitted with any planning application. The values belowshould not be used for design purposes.Soil TypeGreenfield Runoff Rate (l/s/ha)Unknown – Less PermeableEstimated Attenuation Storage Volume (m 3 ) 2,530 – 3,6801 in 2 year 9.41 in 100 year (plus climate change) 35.82012s5947 S Worcestershire Level 2 SFRA Update FINAL Report v1.0.doc 59