Level 2 Strategic Flood Risk Assessment (.pdf ... - Wigan Council

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Preparing responses to these questions for each identified locations will generate a profile of:The implications of seeking to manage the actual risks to acceptable levelsThe effects of climate change on existing defence and the residual risk due toovertoppingThe consequences of the residual risk in the event that the defences failThe Sequential Test Spreadsheet provides a summary of flood risks to the key sites acrossthe borough.8.2 Sustainability AppraisalThe Council's Sustainability Appraisal, land allocations and development control policiesshould be informed by the Wigan Level 2 SFRA and carried out in liaison with theEnvironment Agency.Included in the Sustainability Appraisal is a flood risk objective for sustainable and integratedmanagement of the borough's water resources.'Spatial planning should be integrated with river basin management and strategic flood riskassessment. Therefore, we thought it appropriate to give water management greaterconsideration in the appraisal process. Sub-questions relating to water and flooding wereremoved from other objectives.The Wigan SFRA provides information to support this objective and will provide the evidencebase to help direct sustainable development.8.3 Planning considerationsFor the purpose of this SFRA and for any future planning applications the Sequential Testshould be applied to all proposed development, in consultation with Wigan Council to confirmthat there are no reasonable alternatives on land with a lower probability of flooding whichdeliver the same planning objectives.If, following the application of the Sequential Test, it is identified that there is a requirement toplace additional development in areas with a high or medium probability of flooding then thefollowing issues must be considered:The level of “actual” flood risk to the strategic sites should be evaluated,The implications of climate change on the level of “actual” risk should be understood,andThe implications of residual risk, as a consequence of overtopping or breach ofdefences should be determined.This further review is needed to understand whether development can be made safe fromflooding, including whether it has the potential to pass part (C) of the Exception Test if it isneeded. In order to pass the Exception Test, the LPA must demonstrate that all of the threeconditions must be passed (see paragraph D9 of PPS25):a. It must be demonstrated that the development provides wider sustainability benefitsto the community that outweigh flood risk, informed by a SFRA where one has beenprepared. If the LDD has reached the ‘submission’ stage (see Figure 4.1 of PPS12:Local Development Frameworks) the benefits of the development should contributeto the Core Strategy’s Sustainability Appraisal;b. The development should be on developable previously-developed land or, if it is noton previously-developed land, that there are no reasonable alternative sites ondevelopable previously-developed land; andc. A site-specific Flood Risk Assessment must demonstrate that the development will besafe, without increasing flood risk elsewhere, and, where possible, will reduce floodrisk overall.2009s0578 Final SFRA with Environment Agency Comments - L2 Ver5 Wigan.doc 37
Having followed this procedure it is then possible to consider the appropriate responses thatwill be required to protect the strategic sites/ locations in detail. It will be necessary toconsider the full range of responses according to the type of risk being addressed and if newdevelopment is being proposed then this must be done in accordance with the guidancegiven in PPS25 and the associated Practice Guide.8.4 Development sites benefitting from defencesOf the proposed development sites within Wigan, a small proportion benefit from theprotection of defences. These have been defined from Environment Agency flood mappingwhich displays all England and Wales flood defences that have been constructed during thelast five years with a standard of protection equal to or better than 1 per cent from rivers and0.5 per cent from the sea. Some additional defences, which may be older or have beendesigned to a lower design standard, are also displayed.8.4.1 Environment Land Allocation SitesThe table below displays proposed Environment Land Allocation (ELA) sites within theborough which benefit from such defences:Table 8-1: Environmental Land Allocation SitesPEANameType of Land Latest PLA Proposal Comments Area (msq)HopeCarr/LeighCommerceParkLand withplanningpermissionA/04/61949To erect officeand industrialdevelopment(B1, B2 & B8)Part of larger area ofland included inapplicationA/04/61949.Proposed for StageC ofdevelopment(largeindustrial units)19334.077HopeCarr/LeighCommerceParkLand withplanningpermissionA/08/70945 To erect 9,302square metresof business(Class B1)unitsApplication site goesout of the primaryemployment area14576.352These ELA sites are protected by the Environment Agency raised man-made defence ID01323PENT0101L02 which is located upstream of Warrington Road, Leigh. The defenceconsists of flood banks on either side of the watercourse, linked to Pennington Bank. TheEnvironment Agency are responsible for the maintenance of the asset. The defence is508.4m long and 6.7m high.8.4.2 Strategic Housing Land Availability Assessment SitesThe table below displays proposed Strategic Housing Land Availability (SHLAA) sites withinthe borough which benefit from defences:Site Ref Wig137; Wigan Pier Quarter, WiganSite Ref 695; Wigan Pier: Sites off Swan Meadow Road and Pottery RoadThe two SHLAA sites are protected by ABD ID ea01212Smit_001. The modelling approachused to derive the ABD was a quantitative full hydrodynamic study. The ABD is in the FloodZone 3 fluvial event from the River Douglas.This ABD has been created from the following defences:Table 8-2: Areas Benefiting from Defences2009s0578 Final SFRA with Environment Agency Comments - L2 Ver5 Wigan.doc 38
Page 1 and 2: Wigan Borough Hybrid SFRAVolume I:
Page 3 and 4: JBA OfficeJBA ConsultingSouth BarnB
Page 5 and 6: AcknowledgmentsJBA would like to ac
Page 7 and 8: Understanding flood risk from a pla
Page 9 and 10: 8.3 Planning considerations........
Page 11 and 12: AbbreviationsABDAreas Benefiting fr
Page 13 and 14: The key objectives of a SFRA are to
Page 15 and 16: 2 Flooding from RiversA detailed as
Page 17 and 18: 1. Astely Brook2. Bedford Brook3. W
Page 19 and 20: Unique ID Watercourse Description L
Page 21 and 22: 2.7 Understanding flood risk from a
Page 23 and 24: For example, flooding may affect ke
Page 25 and 26: 3 Flooding from CanalsThe SFRA has
Page 27 and 28: 3.2.2 Canal breach methodologyCanal
Page 29 and 30: 4 Flooding from ReservoirsFollowing
Page 31 and 32: direction in Future Water3, Making
Page 33 and 34: oundaries. Nine key CDAs have been
Page 35 and 36: CDA Sites Site TypeLark Hill, Astle
Page 37 and 38: particular hotspots where surface w
Page 39 and 40: important role to play in reducing
Page 41 and 42: In the reverse situation, where flo
Page 43: 8 Summary of riskA summary of flood
Page 47 and 48: 9 Outline Mitigation OptionsChapter
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Page 55 and 56: Table B-1: Flood Risk Balance Sheet
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Site Reference Site Location Soil T
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F . Flood Zone 3 Proposed Developme
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G . Environment Agency comments on
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Flood Hazard MappingThe Level 2 rep
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Planning LiaisonEnvironment Agency
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Guide makes further summation diffi
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Wigan Metropolitan Borough CouncilC
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of the extent of any works required
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Planning & Transport StrategyWigan
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Again, avoiding generalities, we ha
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EA comment:Guidance on the preparat
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Please give me a call to discuss wh
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RECORD OF MEETINGStatus:JBA Project
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Level 2 Strategic Flood Risk Assessment (.pdf ... - Wigan Council

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