Strategic Flood Risk Assessment - South Worcestershire ...

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Sources of Flood Risk:Surface water presents the primary flood risk to the site. Further development andcreation of impermeable surfaces may result in an increase of surface water floodrisk. The B4482 Bilford road and the Droitwich road, the main access routes to thesite, are at risk from surface water.Fluvial flood risk investigations indicate the site is not within an area of flood risk.The site falls completely within Flood Zone 1.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)Fluvial DepositsEstimated Attenuation Storage Volume (m 3 ) 4,054 – 5,5651 in 2 year 9.11 in 100 year (plus climate change) 34.52012s5947 S Worcestershire Level 2 SFRA Update FINAL Report v1.0.doc 78
SUDS and the development site:SUDS TypeSource ControlInfiltrationDetentionFiltrationConveyancePotentialSuitabilityCommentsAll forms of source control excluding previous pavements would besuitableMapping 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 ofdetentionMapping suggests that filtrations would be suitable but require a formof liner to prevent ingress of groundwater into the SUDS systemAll forms of flow conveyance are likely to be suitableFlood Defences:None.The site is not located within a groundwater source protection zone.Residential and commercial developments should provide at least two independentSUDS features in series to provide a suitable level of water quality treatment.Effects of Climate Change:Increased rainfall intensities. Increased water levels in the Barbourne Brook.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.Resilience measures will be required if buildings are situated in the flood risk area.Redevelopment or alternative use of the site will focus on commercial, recreationand leisure uses, either singly or as mixed use proposals.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.There is a culvert through the site that is in a bad state of repair. Consider culvertremoval.The site is located on a historic landfill site, at Bilford Road Depot.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.Onsite attenuation schemes would need to be tested against the hydrograph of thereceiving watercourse to ensure flows are not exacerbated downstream within thecatchment.All current access roads to the site are at risk from surface water. Suitablealternative 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 79
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2012s5947 South WorcestershireStrat
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ContractThis Level 2 Strategic Floo
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Executive SummaryThis report is an
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Table 7-16: SWDP8/1 (Broomhall Comm
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NRDOrdinary WatercourseOS NGRPFRAPi
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identify the level of detail requir
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1.4 Approach1.4.1 General Assessmen
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1.5.3 Severn Trent WaterSevern Tren
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2 The Planning Framework and Flood
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Additionally Provision 110 of the A
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Risk ManagementAuthority (RMA)Distr
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3 Understanding Flood Risk in South
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earth embankment, flood wall and fl
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4 How Flood Risk is Assessed4.1 Def
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Zone 1Zone 2Zone 3aZone 3bTable 4-1
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etween the proposed level of commit
Page 36 and 37: 5 Mapping and risk based approach5.
Page 38 and 39: The ability to manage flood risk fo
Page 40 and 41: Stage 3 - Applying the Sequential T
Page 42 and 43: 6 Overview of future developmentThe
Page 44 and 45: A proposed 340 dwelling have been a
Page 46 and 47: Figure 6-5: Proposed Pershore Alloc
Page 48 and 49: 6.3 Windfall sitesWindfall is unall
Page 50 and 51: 7 Summary assessment of SWDP develo
Page 52 and 53: SUDS TypeSource ControlsTable 7-2:
Page 54 and 55: 7.4 Summary tables and mapsTable 7-
Page 56 and 57: SUDS and the development site:SUDS
Page 58 and 59: Sources of Flood Risk:Primary flood
Page 60 and 61: Table 7-5: LP1 (Ivy Lane)OS NGR: SP
Page 66 and 67: Table 7-7: 2012SC (Stonebridge Cros
Page 72 and 73: emergence. Further assessment of gr
Page 76 and 77: Table 7-10: SWDP6/NEWJ (Land North
Page 78 and 79: Estimated Attenuation Storage Volum
Page 82 and 83: Table 7-12: SWDP6/6 (Old Northwick
Page 84 and 85: Soil TypeGreenfield Runoff Rate (l/
Page 88 and 89: Table 7-14: SWDP6/21 (Former Hallow
Page 90 and 91: SUDS and the development siteSUDS T
Page 94 and 95: Table 7-16: SWDP8/1 (Broomhall Comm
Page 96 and 97: Surface water presents a risk to th
Page 98 and 99: Table 7-17: SWDP8/2 (Temple Laugher
Page 100 and 101: A44 Bromyard road, the A4440 Grove
Page 102 and 103: Table 7-18: SWDP8/3 (Land to the re
Page 104 and 105: impermeable surfaces may result in
Page 106 and 107: Table 7-19: SWDP9/2 (Land east of S
Page 108 and 109: impermeable surfaces may result in
Page 110 and 111: Table 7-20: SWDP9/3 (Boxing Club)OS
Page 112 and 113: Estimated Attenuation Storage Volum
Page 116 and 117: Table 7-22: SWDP9/7 (Canal Basin Pr
Page 118 and 119: Soil TypeGreenfield Runoff Rate (l/
Page 120 and 121: Sources of Flood Risk:The main sour
Page 122 and 123: Table 7-24: SWDP13/4 (Former playin
Page 124 and 125: Surface Water Drainage:As an indica
Page 126 and 127: Table 7-25: SWDP13/5 (Former Recrea
Page 128 and 129: Surface Water Drainage:As an indica
Page 130 and 131: Table 7-26: SWDP13/9 (Land off Mayf
Page 132 and 133: Greenfield Runoff Rate (l/s/ha)Esti
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eceiving watercourse to ensure flow
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Sources of Flood Risk:The main sour
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Table 7-29: SWDP18/6 Land rear of t
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Estimated Attenuation Storage Volum
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Sources of Flood Risk:Primary flood
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New or re-development should adopt
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Table 7-32: SWDP23/26 (Land between
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Sources of Flood Risk:The main sour
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Table 7-34: SWDP24/8 (Site behind H
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SUDS and the development site:SUDS
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Table 7-36: SWDP24/11 (Site behind
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overtopping of an unnamed tributary
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Table 7-37: SWDP24/13 (Land east of
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Table 7-39: SWDP25/9 (Land at Park
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access roads to the site are at ris
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Table 7-40: SWDP/VPx (Vale Park ext
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Surface Water Drainage:As an indica
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8 FRA requirements for developers8.
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Figure 8-1: Rationale for flood res
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Local planning bodies should:Promot
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Temporary BarriersTemporary barrier
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flood risk. Development locations s
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9 Recommended policy for management
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10 Outcomes10.1 Summary of work und
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Appendices2012s5947 S Worcestershir
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AFlood Zone mapping2012s5947 S Worc
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BClimate change mapping2012s5947 S
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CHazard mapping2012s5947 S Worceste
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DSurface water flood risk mapping20
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D.2 200 years2012s5947 S Worcesters
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EFloodplain policy mapping2012s5947
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FSummary of risk to all proposed al
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GProperty and critical infrastructu
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Number of environmental sites at ri
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HConsultation and communication2012
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Offices atAtherstoneDoncasterEdinbu
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