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BRO SFRA Volume1 User Guide November 2009

1. 2 2 n none nn 37 BT MTC CU CTO seca n 2s sapped cena aana Shug ces anaedai aaa aai radan daaa diaaa 37 5 2 Strategic Approach isiv ceccuhi cp sexe cia yenaet ca scktenstvevsececepeceu die dehasbecenstensanevb uals geste dadeedvaasandenes dey cent oat 37 5 3 Potential Mitigation M ASUreS ceeecceseeeeeeceee eect eeeaeeeeeeeeecaaeeeeaae scenes saeeesaaeeseaeeseeeesaeeeeeeeeee 38 5 4 Mitigation Techniques ccceeecececeeeceeeeeeeeeeeceeeeeceaeeeeeeeeeeaeeeeaaeseeaaeseeeeesaeeeeaaeeseaeeseceessiaeeneneeee 38 5 5 Making Development Safe cccccceccceeeeeeeeneeceeeeeeaeeeeaaeceeaeeesaaeseeaaeseeeeesaeeesaaeeseeeeseeeesaeeeseneeees 39 5 6 Making Space for Water ccccccceceeeeeseeeeeeeeeceeeeecaeeeeeaeeceaeeesaaeeeeaaeseeeeesaeeesaaeeseaeesecaeeesaeeseneeees 40 6 GUIDANCE FOR EMERGENCY PLANNERS 43 Gels IMTPOGUCTION sissien aeea eaa AEE EETAS a EAE AEAEE E KOAA ERER EAEEREN AEA EEE RESANS 43 6 2 Emergency Planning OvervieW s sssssssssssrsssrsssnsssnssrnssrnssressstnnstnsstnnstenstanstenntennnnnnnnnnnannnnnnnnnno 43 6 3 Flood Plan RecommendatONS sieaas iaaa daa iadaaa aaa a 44 6 4 Planning Approval Flood Plans including Flood Warning eeseeeeeseeseeseeseeeseereserenerrenee 45 6 5 FoodAWwWareneSS orrasarc ninenin eanan aranairad eaaa aiia aneia aa aaan 46 JBA Consulting www jbaconsulting co uk ix Bur
2. Volume II Flood Zone Maps or Flood Zones on The development other than minor development Environment Agency website if updated is situated in Flood Zone 2 and 3 See PPS25 Practice Guide section 2 46 for definition of major developments The development is greater than 0 5ha and situated in Flood Zone 1 but there are critical drainage problems i e the development lies within a Critical Drainage Area Volume II Critical Drainage Area Maps Volume Surface Water Maps Volume III Canal Hazard and Refined Surface Water Maps The development is at risk of flooding from other sources of flooding Volume III SFRA Asset Database section 2 The development is situated behind flood and Flood Risk Management Maps defences possibility of overtopping during Volume III Depth and Hazard Maps for both the extreme flood event or breach 1 in 100 and 1 in 1000 year flood events Volume III Fluvial Breach Maps The development exceeds tha in size Consult Environment Agency The development is within 20m of the bank top of a Main River the Environment Agency will have to consent to any work within 5m of a Main Consult Environment Agency River and are likely to object in principal to any development within these areas Any culverting operation or development which controls the flow of any river or stream Consult Ernyironment Agency Please see page vi for map references JBA Consulting www jbaconsu
3. It was also recommended that the Greater Manchester sub regional SFRA should be kept as a living document and to help facilitate the process a Flood Risk Library should be created This should be used as a single point within AGMA for the collection and cataloguing of flood risk data relevant to the sub region This information would include completed FRAs records of flood events and updated flood risk information and studies for the Environment Agency and other organisations The Bury Rochdale and Oldham SFRA should fit into the Flood Risk Library and be used to update the Greater Manchester sub regional SFRA data gaps if required or simply used as separate source of flood risk information All data collected during the Greater Manchester sub regional SFRA was reviewed on receipt and the level of accuracy and relevance was assessed A data register was created providing a list of all data collected and the outcome of the review The purpose of the register was to allow a quick an easy review of data gaps needing review during further work in Level 1 and Level 2 SFRAs JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils P e e Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide CONSULTING JBA Consulting www jbaconsulting co uk 2009s0042 Volume I SFRA User Guide Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment J a C 1 THE PLANNI
4. Figure 2 5 Identifying the likelihood of passing the Exception Test Level 2 SFRA Detailed Flood Risk Information Actual Risks SFRA Evidence Are flood depths gt 1 5m Are flood hazards dangerous for most or higher Yes Climate Change sensitive Are mitigation measures significant Could requirement for compensational storage impact on yields achievable Proposed development site is Will development add more buildings people to the community at risk unlikely to pass the Exception Test on flood risk Ne grounds The site should be avoided at this stage and withdrawn from the Sustainability Appraisal Fluvial Depth Maps Fluvial Hazard Maps Climate Change Sensitivity Maps SFRA User Guide Possible Mitigation Measures Table Residual Risks SFRA Evidence Are they Acceptable Fluvial Overtopping Depth amp Is the community covered by a flood warning system Hazard Maps Can appropriate access amp egress routes be identified No Breach Depth amp Hazard Maps Is flood risk an urban design issue Canal Hazard Zones Maps Are compensation works possible Flood Risk Management Maps Are mitigation measures achievable appropriate and could they reduce risk to the surrounding community Assess alternative development options using Sustainability Appraisal balancing flood risk against other planning objectives 2 5 Flood Risk and other Land Use Policies Flood risk is a
5. The consideration of flood risk within the context of an individual site planning application is shown on Figure 3 1 It highlights how to take account of flood risk using the information provided within the BRO Level 1 and Level 2 SFRA and the guidance provided in PPS25 and by the Environment Agency Standing Advice Development Management officers should refer to page vi of this report for map numbers If an individual site has been identified for development Development Management must check that the development is sound regarding flood risk i e it has passed the Sequential Test and is likely to pass the Exception Test where applicable and that it is supported by a coherent FRA which meets the requirements of PPS25 Development Management officers must always consider development from a strategic view point and the cumulative effect of all proposed development taking place even though applications for developments are submitted at a site level It should not be presumed that flood risk has been understood at a strategic high level and that one application may need to fit within a flood risk management strategy for an area The Sequential Test and Exception Test If the proposed site is already identified in a Sequentially Tested LDD which is supported by the findings of the BRO SFRA and transparent evidence that the Sequential Test has been carried out the site will already have been through the Sequential Test The developer must still ap
6. 4 Adding wind turbines to the essential infrastructure category However in keeping with PPS25 the Sequential Test is not required but Parts A and C of the Exception Test would need to be passed if located in Flood Zone 3a and 3b JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide Until the proposed changes have been agreed and PPS25 updated the current PPS25 2006 and its Practice Guide 2009 should be used for planning policy guidance but users should be aware of possible future changes Classification Description Essential e Essential transport infrastructure including mass evacuation routes which has to cross the Infrastructure area at risk and strategic utility infrastructure including electricity generating power stations and grid and primary substations Highly Vulnerable e Police stations Ambulance stations and Fire stations and Command Centres and telecommunications installations required to be operational during flooding e Emergency dispersal points e Basement dwellings e Caravans mobile homes and park homes intended for permanent residential use e Installations requiring hazardous substances consent 1 More Vulnerable e Hospitals e Residential institutions such as residential care homes children s homes social services homes prisons and hostels e Buildings used for dwelling hous
7. BRO SFRA User Guide This volume has been developed to provide guidance on the use of the SFRA for Local Authority Spatial Planning Regeneration Development Management and Emergency Planning officers and Developers Volume II BRO Level 1 SFRA The BRO SFRA Volume II has used mostly existing data to make an assessment of flood risk from all sources now and in the future and builds on the Association of Greater Manchester Authorities AGMA Sub Regional SFRA It provides evidence for LPA officers to apply the Sequential Test and identifies the need to pass the Exception Test where required Both of these tests are a fundamental part of PPS25 JBA Consulting www jbaconsulting co uk 2 Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume SFRA User Guide 1 2 3 1 2 4 The study area focuses on Bury Rochdale and Oldham Council and key urban areas including Ramsbottom Bury Radcliffe Littleborough Rochdale and Shaw Although Oldham Council has been included in the discussion only areas within the River Beal catchment have been assessed as part of this SFRA Oldham Council are preparing a separate SFRA that will cover all of Oldham including the Beal catchment The main tasks for the BRO SFRA Volume II included e Stakeholder consultation data collection and review e Assessment of current flood risk e Delineation of PPS25 Flood Zones including the Functional Floodplain and the impact
8. Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide appropriate mitigation measures The FRA should define and address the constraints that will govern the design of the drainage system and layout of the development site The Environment Agency Standing Advice allows developers to screen online for the level of flood risk assessment that is appropriate for a development with regard to the PPS25 Flood Zones This highlights the need for a FRA in Flood Zones 2 and 3 and in Flood Zone 1 where there are critical drainage problems The Standing Advice notes that for developments in Flood Zone 1 FRA Guidance Note 1 should be followed In areas where the Local Planning Authority has identified drainage problems through a Strategic Flood Risk Assessment or Surface Water Management Plan and they have indicated that a formal flood risk assessment is required FRA Guidance Note 1 requires FRAs to provide Proposals for surface water management that aims to not increase and where practicable reduce the rate of runoff from the site as a result of the development in accordance with sustainable drainage principles and the Local Planning Authority s published SFRA Proposals for development in Critical Drainage Areas as defined by this SFRA should follow the guidance and standards as set out below for developments that are within any flood zone Allowable Discharge Rates Development sho
9. Definition This zone comprises land assessed as having a 1 in 100 or greater annual probability of river flooding gt 1 and a 1 in 200 or greater annual probability of flooding from the sea gt 0 5 in any year Appropriate uses The water compatible and less vulnerable uses of land listed in Table D 2 of PPS25 and Table A 2 of this report are appropriate in this zone The highly vulnerable uses listed in Table D 2 of PPS25 and Table A 2 of this report should not be permitted in this zone The more vulnerable and essential infrastructure listed in the Table D 2 of PPS25 and Table B 2 of this report should only be permitted in this zone if the Exception Test is passed Essential Infrastructure permitted in this zone should be designed and constructed to remain operational and safe for user in times of flood FRA requirements All development proposals in this zone should be accompanied by a FRA See Annex E of PPS25 for minimum requirements Policy Aims In this zone developers and local authorities should seek opportunities to i reduce the overall level of flood risk in the area through the layout and form of the development and the appropriate application of sustainable drainage techniques ii relocate existing development to land in lower Flood Zones and iii Create space for flooding to occur by restoring functional floodplain and flood flow pathways and by identifying allocation and safeguarding open space for fl
10. SFRA User Guide e To make the Environment Agency river level information available to the public on the internet The biggest change will be the development of new public warning codes These include e Flood Alert Flooding is possible Be prepared e Flood Warning Flooding is expected Immediate action required These new public warning codes will be put into effect from spring 2010 Overview Flooding in urban areas can come from a variety of sources and when flooding occurs it is often not clear where the water has come from The draft Flood and Water Management Bill defines local flood risk for which local authorities will have a local leadership role as the risk of flooding from ordinary watercourses smaller watercourses that are not under the jurisdiction of the Environment Agency surface water and groundwater Prior to the major flood events in summer 2007 the understanding of non Main River flooding was based on anecdotal evidence or described within Critical Ordinary Watercourse COW investigations undertaken by the Environment Agency Little data could be abstracted from the water companies on sensitive drainage catchments where runoff impacts of new development could be significant on combined sewer systems However a significant proportion of recent flood insurance claims are due to flooding from non Main River sources so this issue will become larger with climate change Historically the adopte
11. evidence that the test can that the test can vulnerability be passed by providing be passed to the Appendix F planning justification and Windfall Sites y LPA An area of producing a detailed FRA Sect 4 33 4 35 eS search to be agreed but should be within local community boundary Dependent LPA to advise on the on land use likelihood of passing test Regeneration vulnerability But the developer must Sites Identified N Appendix F provide evidence that the Within LDD 9 i Test can be passed by Sect 4 36 4 38 providing planning justification and producing a detailed FRA LPA to advise on the PPS22 e a iy sree Renewable Renewable UE tG CEVe oper MUS Energy Projects Energy advises provide evidence that the the LPA not to Dependent Test can be passed by No on land use providing planning use a sequential is ere Sect 4 39 approach in the vulnerability justification and producing a detailed FRA Part B of consideration of he E tion Test m such proposals thie Exception test may not apply in accordance with PPS22 JBA Consulting www jbaconsulting co uk 22 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 4 3 Development Sequential Test Exception Test PPS25 PG 7 Who Applies the RETE Required AR Required Who Applies the Test Redevelopment Dependent Developer must provide of Existing on land us
12. o What existing surface water drainage requirements are present on the site See section 4 6 on CDAs and consult with LPA Environment Agency and Untied Utilities Probability o Which Flood Zones are present within the site See Flood Zone Map o What actual and residual risks are associated with the site See FRM depth and hazards and canal hazard maps o What are the existing rates and run off volume generated by the site Climate Change o How is flood risk at the site likely to be affected by climate change See climate change maps Flood Risk Management Measures o How will the site be protected from flooding including the potential impacts of climate change over the development s lifetime Developers should refer to section 5 of this Volume for details on appropriate mitigation They should also refer to section 8 and 9 of Volume Ill regarding the community flood risk reviews and mitigation strategies Off Site Impacts o How will the proposed development and measures be implemented to protect the site from flooding and prevent run off be designed to not increase flood risk elsewhere and where achievable reduce flood risk to the surrounding community o This should also include compensation storage where required Residual Risks o What flood related risks will remain after mitigation measures have been implemented to protect the site from flooding o How and by whom will these risks be managed over the lifetime
13. provide an opportunity to reduce flood risk within the development The PPS25 Practice Guide states that a sequential risk based approach should be applied to try to locate more vulnerable land use to higher ground while more flood compatible development e g vehicular parking recreational space can be located in higher risk areas Waterside areas or areas along known flow routes can be used for recreation amenity and environmental purposes allowing the preservation of flow routes and flood storage and at the same time providing valuable social and environmental benefits contributing to other sustainability objectives Landscaping should ensure safe access to higher ground from these areas and avoid the creation of isolated islands as water levels rise The Environment Agency will have to consent to any works within 5 metres of a main river It is likely that they will object in principle to any development within these areas The Royal Institute of British Architects RIBA have produced a guidance document Designing for Flood Risk which can aid this process The guidance document can be found at http www architecture com FindOutAbout Sustainabilityandclimatechange Flooding DesignGuide as px Modification of Ground Levels Modifying ground levels to raise the land above the required flood level is a very effective way of reducing flood risk to the site in question However in most areas of fluvial flood risk conveyance or
14. will reduce flood risk overall It will be the requirement of Development Management officers to make sure all parts of the Exception Test have been passed in granting planning permission see section 3 Ata Spatial Planning stage only the likelihood of passing the Exception Test can be assessed as actually passing the Test will require the completion of a site specific FRA to determine if the site and its occupiers will be safe during times of flood What should be done at this early stage of the planning process is to identify those sites in which the Exception Test is required and to avoid those sites in which flood risk is too great using the information provided in the BRO SFRA Volume III or there is no overriding planning objectives for that development JBA Consulting www jbaconsulting co uk 9 2009s0042 Volume I SFRA User Guide Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment J a 2 4 2 4 1 Applying the Sequential Test and Assessing the Likelihood of Passing the Exception Test This section provides the following guidance on how Spatial Planners are to apply the Sequential and Exception Test within the Sustainability Appraisal of LDDs Figure 2 1 discussed earlier on identifies how flood risk is taken into account in LDDs and introduces the use of the Sustainability Appraisal in applying the Sequential and Exception Tests What PPS25 does not provide is step by step guidance on how to appl
15. All development applications must be supported by an appropriate site specific FRA in accordance with the guidance provided in PPS25 Practice Guide section 3 80 to 3 90 Further guidance is also provided in section 4 5 and 6 of this Volume At the first possible stage Development Management should refer the developer to the BRO SFRA all Volumes and the flood risk mapping provided within The developer should also be referred to the appropriate LDD and flood risk policies which could potentially influence their proposed development If the site or community has been identified at risk of flooding from any source Development Management and the developer should consult the Environment Agency and other relevant flood risk consultees such as United Utilities or British Waterways to identify known flood related site constraints and agree the scope of an appropriate FRA The Environment Agency Standing Advice should be used at this stage This can be accessed online at http Awww environment agency gov uk research planning 82584 aspx The Environment Agency is a statutory consultee for specific categories of development where flood risk is an issue Table 3 1 outlines a number of considerations which should trigger the involvement of the Environment Agency within the FRA process These also highlight the requirement of a more detailed FRA Table 3 1 FRA considerations and SFRA supporting evidence Considerations Supporting evidence in the SFRA
16. Flood Warning Flood severe flooding is expected Warning All Clear Clear all clear or receding floodwaters The flood warnings are used to reduce the overall impact of flooding of people and property by lowering the vulnerability of the receptor This is done by providing a warning which can then be used to remove people at risk or to relocate valuable possession to higher levels In response to the summer 2007 floods the Pitt Review stated that the Environment Agency flood warning service needed to be improved to stimulate a more effective response from response agencies and the general public In order to tackle these issues the Environment Agency set up the Flood Warning Service Improvements Project FWSIP in December 2008 The project had three objectives e To implement new public flood warning codes which are adaptable for all sources of flooding and are effective at promoting action by people to reduce the impact of floods on their lives and livelihoods e To develop an integrated service which provides professional partners with greater access to expert advisors during an event and a rationalised set of messages alerts warnings from the Met Office Flood Forecasting Centre and the Environment Agency and Environment Agency 2006 Creating a Better Place Corporate Strategy 2006 2011 JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I
17. Have there been past incidences of canal breach which may show that the location of the development site is vulnerable to canal breach Past breach failures may have been caused by overtopping of the canal bank or failure of the canal lining Advice on JBA Consulting www jbaconsulting co uk 28 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide locations of historic breaches is generally available from British Waterways Are any structures such as aqueducts in poor condition Aqueducts in poor condition will have a higher propensity to fail and may have to be considered specifically Are there any local culverts underneath the canal that may have insufficient capacity The most serious breach in the past on the Rochdale Canal has been caused by culvert blockage and floodwater damming behind the canal which led to a breach of the canal If the response to any of these questions is yes canal breach flood risk should be carried forward into Stage 3 If a canal breach is considered unlikely but the site is immediately below a canal then the FRA should consider what if any residual risk could be associated with the canal Mitigation measures could include incorporating flood resilience measures into low level properties and raising ground levels Stage 3 Detailed Assessment The scoping exercise may identify that a detailed assessment is required It is expected that Stage 3 will only b
18. account by raising floor levels increasing the designed freeboard levels to take account of the risk as the depths and flows will be generally low Typically this approach is taken in the design of road and finished floor levels where a 300mm freeboard is provided to ensure that the primary route for exceedence flows from either the surface water system or the canal is along the road network and away from property It is the developer s responsibility to assess whether this freeboard is adequate and the master plan for the site reflects the need to retain and guide overtopping flows to a safe area Within areas of fluvial or surface water flood risk FRAs will need to consider this along with the measures taken to manage these other sources Typically a freeboard value is added to the 1 plus climate change flood level to take into account uncertainty and operational issues Traditionally a value of 600mm is taken Where a FRA is being undertaken in both the direct and indirect canal hazard zone then the freeboard should be assessed from first principles taking into account flood risk from the canal as another source of uncertainty A higher freeboard allowance may be required as a result Assess any residual risks and decide how they should be managed Flood warning and resilience measures may be appropriate The developer should liaise with the LPA and British Waterways to determine suitable emergency planning arrangements Breaching If a third s
19. and considering flooding from all sources e Wherever possible using open land or green infrastructure to reduce risk provide compensatory flood storage or serve a sustainable drainage function e Adopting mitigation solutions that fit with the wider vision of the community in managing flood risk In significant flood risk areas developers should aim to reduce risk to the wider community as provided for in the policy aims of PPS25 e Adopting SUDS e Preparing emergency flood plans JBA Consulting www jbaconsulting co uk 37 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 5 3 5 4 5 4 1 5 4 2 5 4 3 5 4 4 Potential Mitigation Measures Table 5 1 provides links to the evidence in the BRO SFRA Volume Il and Ill to identify what development could be seen as appropriate with a certain flood risk area and what mitigation measures could potentially be adopted to reduce the level of risk As above all mitigation measures should fit in with the wider strategic approach advocated for a community and ensure that there is no increase in flood risk to the surrounding community The developer should liaise closely the Environment Agency and Development Management as to what mitigation measures may be suitable Mitigation Techniques Reducing Flood Risk through Site Layout and Design Flood risk should be considered at an early stage in deciding the layout and design of a site to
20. are currently preparing their LDFs which will be subject to public examination by an independent Planning Inspector who will assess the soundness of the LDF documents This will include assessing that the LDF is based on robust and credible evidence PPS25 requires a SFRA to be carried out in order to inform policy development and to apply the Sequential Test and Exception Test where necessary when allocating sites for development The relevant LPA should be contacted regarding the stage of the LDF in its preparation JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils e e Strategic Flood Risk Assessment a 2009s0042 Volume SFRA User Guide i C 1 5 Environment Agency Policy Catchment Flood Management Plans Bury Rochdale and Oldham Councils are covered by two CFMPs The River Irwell CFMP and the Upper Mersey CFMP The Irwell and Upper Mersey CFMPs are high level policy documents covering the whole of the River Irwell and Upper Mersey catchments The Irwell CFMP is the only one relating to the Level 1 SFRA study area of Bury Rochdale and the Beal catchment The CFMP is investigating what factors influence flood risk at the catchment scale and will assess the impacts that climate change land use change and urbanisation may have on flood risk over the next 50 to 100 years The CFMP will establish a policy framework for flood risk management across the catchment through which future flood al ee SE ey eee
21. as it can improve flood flow routes In these cases attention should always be paid to safe access and egress and legal protection should be given to ensure the ground floor use is not changed Resistance and Resilience There may be instances where flood risk remains to a development For example where the use is water compatible where an existing building is being changed where residual risk remains behind defences or where floor levels have been raised but there is still a risk in a 1 in 1000 year event In these cases and for existing development in the floodplain additional measures can be put in place to reduce damage in a flood and increase the speed of recovery These measures should not be relied on as the only mitigation method The 2007 document Improving the Flood Performance of New Buildings provides further details on possible resistance and resilience measures Temporary Barriers Temporary barriers consist of moveable flood defences which can be fitted into doorways and or windows The permanent fixings required to install these temporary defences should be discrete and keep architectural impact to a minimum On a smaller scale temporary snap on covers for airbricks and air vents can also be fitted to prevent the entrance of flood water Permanent barriers Permanent barriers can include built up doorsteps rendered brick walls and toughened glass barriers Wet proofing This involves designing interiors to reduc
22. carried forward into Table D 3 for application of the Exception Test Proposed Updates to PPS25 Vulnerability Classification On 11 August 2009 CLG published a Consultation Paper on proposed amendments to PPS25 The consultation relates to proposed clarifications to some aspects of the existing national spatial planning policy on development and flood risk to help ensure the policy is applied effectively The consultation process is due to end in November 2009 There are four amendments proposed in Table D 2 including 1 Moving water treatment and sewage treatment works from less vulnerable to essential infrastructure This means they will now need to pass the Exception Test if planned in Flood Zone 3a rather than just Flood Zone 3b As usual they will have to be designed to the appropriate uses and policy aims within Table D 1 2 Allowing police ambulance and fire stations to be defined as less vulnerable only if they are not required to be operational during flooding This will stop the exclusion of new emergency services facilities from communities they service in high flood risk areas 3 To allow facilities requiring hazardous substances consent which are required to be located in flood risk areas due to their need to be co located with other facilities i e the need to be located near ports or processed or manufactured facilities to be defined as essential infrastructure rather than highly vulnerable
23. conjunction with Defra DCLG then provided the recommended climate change contingency allowances for sea level rise and precautionary sensitivity ranges for peak rainfall intensities and peak river flows etc in Annex B of PPS25 These figures should be used in all aspects of flood risk management including the consideration of new developments and changes of land use in flood risk areas RFRA 4 North West The North West Regional Flood Risk Appraisal was prepared in October 2008 for 4NW which is the Regional Planning Body in the North West The primary objective of a Regional Flood Risk Appraisal RFRA is to provide an appraisal of strategically significant flood risk issues in a region in order to guide strategic planning decisions The RFRA assists decisions on key land use factors such as the need for employment inward investment regeneration provision of housing and open green space major road and other infrastructure development provision to deliver sustainable growth whilst taking full account of flood risks now and in the future The appraisal should also drive and inform policy development and setting in the Regional Spatial Strategy RSS for the strategic management of flood risk and in turn assists local authority planners in their consideration and implementation of land use policies in Local Development Frameworks LDFs and Local Development Documents LDDs In addition it provides important strategic flood risk input to t
24. conservation and biodiversity outdoor sports and recreation and essential facilities such as changing rooms e Essential ancillary sleeping or residential accommodation for staff required by uses in this category subject to a specific warning and evacuation plan Water compatible Development Note 1 This classification is based on advice from the Environment Agency on the flood risks to people and the need of some uses to keep functioning during flooding Note 2 Buildings that combine a mixture of uses should be placed into the higher of the relevant classes of flood risk sensitivity Developments that allow uses to be distributed over the site may fall within several classes of flood sensitivity 1 DETA Circular 04 00 para 18 Planning controls for hazardous substances 2 See Planning for Sustainable Waste Management Companion Guide to Planning Policy Statement 10 for definition JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils P e e Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide CONSULTING JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment a 2009s0042 Volume SFRA User Guide S E G 1 1 Sustainable Drainage Systems Sustainable Urban Drainage Systems SUDS are management practices which enable surface water to be drained in a more sustainable manner For Greenfield develo
25. defence infrastructure is residual however the risks can be significant due to sudden onset and velocities reached by flood waters should a defence overtop or fail Flood Warning The Environment Agency has the lead role in providing flood warnings in England and Wales The aim of the flood warning service is to reduce risk to life distress to people and damage to property caused by flooding by providing accurate timely flood warnings to residents within the floodplain of rivers estuaries and coasts to the media and partner organisations It is crucial that people at risk receive appropriate flood warnings and take action to protect themselves and their property Within the Environment Agency corporate plan Creating a Better Place the Agency has highlighted three main targets e To have 80 of properties at risk in the floodplain in England and Wales receiving an appropriate flood warning service e 75 of people who live in flood risk areas take appropriate action by 2011 e To have major incident plans in place for high flood risk areas Currently the Environment Agency operates a flood warning service in specific locations known as Flood Warning Areas where Flood Warning Codes are assigned based on the overall impact of flooding within an area These include Flood A flooding of low lying land and roads is Flood flooding of homes and businesses is Flood Warning iwi Warning VAN expected Severe oe Severe
26. defence management strategies and programmes will be Kanina formulated Recognition of these strategic plans is very important to local authority planners when planning for the future and considering long term land use options for re generation inward investment and growth The CFMPs help to prioritise activities focus resources where there is greatest need and determine what flood risk management responses need to be considered further and which responses will not be effective The responses to flood risk will be broader than those traditionally used for flood defence to reflect the full range of management options available CFMPs support an integrated approach to spatial planning and river basin management in line with the Water Framework Directive and the EU Directive on the assessment and management of flood risk they cover all geographical areas in England and Wales and are crucial in the planning of sustainable flood risk management CFMP Policy Units covering Bury Rochdale and Oldham are identified in the Figure C1 below Each colour in the key represents the chosen policy There are a number of chosen sustainable flood risk management policies relating the areas within Bury Rochdale and Oldham These include CFMP Policies e Policy 3 Continue with existing or alternative actions to manage flood risk at the current level accepting flood risk will increase from this baseline e Policy 4 Take further action to sustain the c
27. has to be considered Flooding from reservoirs is noted as an issue within the Pitt Review Recommendations and acknowledged by Hilary Benn the Secretary of State for Environment Food and Rural Affairs 1million has been pledge to improve reservoir safety specifically to produce inundation mapping for all reservoirs falling under the Reservoirs Act i e those with a capacity of over 25 000m Reservoirs are classified on a consequence of failure basis outlined below in Table A1 and it is now suggested that a better risk based approach to reservoir safety is needed focusing on those reservoirs that pose the greatest risk to the public even if they are not currently covered by the Act Table A1 Reservoir Consequence Classification Dam Category Potential Consequence of Reservoir Failure A At least 10 lives at risk and extensive property damage B Fewer than 10 lives at risk or extensive property damage C Negligible risk to human life but some property damage D Negligible risk to human life and very limited property damage The Environment Agency is currently producing simplified inundation maps for all reservoirs under the Reservoirs Act as required by Recommendation 57 of the Pitt Review Trial projects have been run in the North West to develop the specification for these maps and the Environment Agency will be producing maps for all reservoirs under the Act during 2009 The Water Act 2003 which amended the Rese
28. inputs being the evidence provided in both the Level 1 and Level 2 SFRA and the LPA Core Strategy and Sustainability Appraisal The flow diagram begins by the LPA assessing alternative development options at a strategic scale using the Sustainability Appraisal This then works down using evidence provided in the Level 1 and Level 2 SFRA to avoid inappropriate development sites substitution within the site boundary and identifying those sites requiring the Exception Test The flow diagram ends by revisiting and updating the Sustainability Appraisal with the allocation of development sites Figure 2 3 can be linked to Table 2 1 which provides a more detailed descriptive step by step guidance of the flow process illustrated During this process there is a need to identify which sites should be avoided substituted those which can go forward or once the Sequential Test has been applied how to assess if the site will remain safe during the Exception Test This is a step wise process and must be documented but a challenging one as a number of the criteria used are qualitative and based on experienced judgement Figure 2 4 provides more guidance on using the Sequential Test Spreadsheet produced in the SFRA during Steps 1 to 8 Figure 2 5 provides guidance on how to assess the likelihood of sites passing the Exception Test using key questions and evidence provided in the SFRA in assessing whether a site will remain safe or not during Steps 9 to 10 JBA Co
29. may discharge water to a lower pound in storm conditions The size of the bywashes control the water level rise and in some cases may not have capacity to deal with an extreme event There may be additional lateral spillways for the control of water level rise within the pound length Lower canal freeboard may increase the likelihood of canal overtopping in that location Acts of vandalism may have caused overtopping in the past Advice on any locations of historic overtopping is available from British Waterways e Is the nature of the topography surrounding the canal pound length such that the canal is likely to intercept significant slope rainfall runoff in the 1 in 100 year storm conditions with climate change A canal in cutting may intercept rainfall runoff from both banks causing water level rise in the pound length A significant volume of rainfall runoff in the 1 in 100 year event with climate change could cause overtopping within the pound length if the bywashes and spill structures are of insufficient capacity to control water level rise for that event and if there are raised embankments within the same pound length The catchment for the canal pound is the area receiving runoff in a storm event which will include the canal water area the towpath and may include areas beyond the canal on one or both banks as stated above A canal pound with adequate bywashes and spill structure capacities that does not have a receiving catchment significantly l
30. measures should be considered on a strategic basis that avoids a piecemeal approach and advocates partnership between the LPA and the Environment Agency and integration with wider Environment Agency flood risk management works and strategies e g River Irwell CFMP Upper Irwell Strategy The SFRA identified the need for a strategic vision when it comes to managing flood risk to new development An Outline Mitigation Strategy has been undertaken for the following locations in the BRO SFRA Volume III section 9 e Chamberhall and Western Waterside e The River Irwell at Ramsbottom e The River Irwell from the railway bridge at Warth Mills to the railway crossing downstream of the East Lancs Paper Mill e River Roch through the East Central Rochdale and Town Centre East regeneration areas Volume III A preliminary review of mitigation works to deliver regeneration in Rochdale is considered in Volume IV The Outline Flood Risk Mitigation Strategy considers the wider and cumulative impacts of mitigation and involves master planning an area from a flood risk perspective Developers should refer to the recommendations outlined with this strategy when considering on site mitigation As a summary taking a strategic approach requires all that are involved in flood risk management to consider e Avoidance of development in flood risk areas e The sequential approach to site layout substituting higher vulnerability development in lower flood risk areas
31. of all sources of flooding including fluvial tidal surface water and sewer man made bodies of water including canals and reservoirs and groundwater flooding as discussed in the Level 1 SFRA Volume Il and associated mapping for reports Relevant sections and maps include o Understanding the risk from different sources of flooding Volume II section 2 o Flood zone maps o Areas Susceptible to Surface Water Flooding maps JBA Consulting www jbaconsulting co uk 44 2009s0042 Volume I SFRA User Guide Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment J a 6 4 Note that more detailed surface water maps are available for Littleborough Heywood Ramsbottom Radcliffe Derker and Sholver These are provided as part of the Level 2 SFRA o Climate change maps o Flood depth maps e Consider and understand the residual risk associated with flood risk management infrastructure and the management of manmade bodies of water using the information provided in the BRO SFRA Volume IIl o Flood defences overtopping or breaching Volume II section 2 and 3 which also consider climate change o Canal overtopping or breach Volume II section 4 o Refined surface water maps for Littleborough Heywood Ramsbottom Radcliffe Derker and Sholver Volume II section 5 e Use the data in the BRO SFRA Volume II and III to o Update the final Greater Manchester Multi Agency Flood Plan and update to each Local Auth
32. planning supports flood risk management policies and plans River Basin Management Plans and emergency planning In addition to setting out the roles and responsibilities for LPAs and RPBs PPS25 identifies that landowners also have a primary responsibility for safeguarding their land and other property against natural hazards such as flooding Those promoting sites for development are also responsible for e Demonstrating that development is consistent with PPS25 and Local Development Documents LDDs e Providing a Flood Risk Assessment FRA demonstrating whether the proposed development is likely to be affected by current or future flooding satisfies the LPA that the development is safe and identifies management and mitigation measures PPS25 also introduces an amendment to Article 10 of The Town and Country Planning General Development Order 1995 which makes the Environment Agency a Statutory Consultee on all applications for development in flood risk areas and those within 20m of a Main River The Direction also introduces the requirement for LPAs to notify the Secretary of State where they are minded to approve a planning application contrary to a sustained objection by the Environment Agency The introduction of PPS25 enables local authorities to make a direction under Article 4 of the Town and County Planning General Permitted Development Order 1995 This will enable Local Authorities to remove permitted development rights where
33. policies require that the LPA consider flood risk its mechanisms spatial distributions and development vulnerability in all stages of the development planning process PPS25 promotes positive planning to deliver strategic opportunities to reduce flood risk to communities and apply the Government s policy on flood risk management The Practice Guide also provides further advice on how flood risk should be taken into account in the LDF See section 2 20 2 24 of PPS25 Practice Guide Throughout the risk based sequential approach management actions to avoid substitute control and mitigate flood risk should always be kept in mind and opportunities taken to minimise flood risk at every stage of the planning process The principal aim of these actions is to ensure that flood risk to people their property and the environment is reduced to acceptable levels The hierarchy of management decisions and actions include e Avoidance by locating new development outside areas at risk of flooding e Substitution by changing from a more to a less vulnerable land use and e Control and Mitigation of the risks by implementing flood risk management measures through a variety of techniques to reduce the impact and mitigate residual risks The sequential approach is achieved through the successive application of the Sequential Test and Exception Test Both the BRO SFRA Volume II and III provide the evidence base for this decision making process and should form p
34. risk due to overloading of sewers watercourses culverts and other drainage infrastructure It should be borne in mind that the sewer network in places across the Greater Manchester area was designed to drain less development than exists today Development has added flow over time and the network is known to be at capacity in many places The frequent localised flooding experienced in many parts of Greater Manchester and Radcliffe and Heywood in this study area in particular is testament to this problem Managing surface water discharges from new development is therefore crucial in managing and reducing flood risk to new and existing development downstream Carefully planned development can also play a role in reducing the amount of properties that are directly at risk from surface water flooding The Planning System has a key role to play in settings standards for sustainable drainage from new developments and ensuring that developments are designed to take account of the risk from surface water flooding Sustainable drainage plays an important part in reducing flows in the sewer network and in meeting environmental targets alongside investment in maintenance and new capacity by United Utilities United Utilities plan their investment on a five year rolling cycle in consultation with key partners including the Environment Agency Sustainable drainage and the use of Sustainable Drainage Systems SUDS is supported by the policy direction in Future W
35. that this be every 3 to 4 years unless there is a significant flood affecting the area leading to new information on areas at flood risk becoming available A review of the SFRA should also be undertaken if there are any major national policy changes There are a number of outputs and datasets which are known to be regularly updated These should be incorporated in any update to the SFRA Table 1 2 contains a list of SFRA review triggers Table 1 2 SFRA review triggers Source Possible Timescale Irwell and Upper Mersey CFMP Environment Agency Updated every 5 years Flood Zones significant change Environment Agency Updated quarterly NFCDD Environment Agency Ongoing Possible Flood Event All Unknown Sewer Flood Data United Utilities Late 2009 but not made available in time for the Level 1 and Level 2 SFRAs Greater Manchester Multi Agency Flood Plan GM Resilience Ongoing Planning Policy CLG Unknown Surface Water Management Plans LPA On completion JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils 4C Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide CONSULTING JBA Consulting www jbaconsulting co uk 2009s0042 Volume I SFRA User Guide Bury Rochdale and Oldham Councils e e Strategic Flood Risk Assessment J a 2 1 Introduction PPS25 provides the basis for the sequential approach in which its
36. the groundwater levels to rise e Flooding resulting from groundwater rebound groundwater levels in an area can be kept artificially depressed through groundwater abstraction if these activities are stopped groundwater will rise or rebound to their natural level This rise in groundwater levels may cause once dry spring lines to start discharging groundwater e Flooding resulting from mine water rebound When mine dewatering ceases mine water levels rise as water enters the system through mine entries and permeable strata As levels rise mine water can start to issue from previously dry adits shafts etc as increased water levels allow water to flow from sections and subterranean ponds that were previously unconnected forming new pathways and discharge points in the mine system The occurrence of groundwater flooding is usually very local and unlike flooding from rivers and the sea does not generally pose a significant risk to life due to the slow rate at which the water level rises However groundwater flooding can persist for a long period and cause significant damage to property especial in urban areas if not considered in development planning In most cases groundwater flooding cannot easily be eliminated although the impact on buildings can be mitigated to some extent through various measures Flooding from Drainage Systems Flooding from artificial drainage systems occurs when flow entering a system such as an urban s
37. to identify potential evacuation measures that should be taken to protect against the unlikely event of a major reservoir breach Developers should undertake a zone of search in the vicinity of their site to identify smaller reservoirs such as fishing lodges or mill supply ponds The FRA should determine the ownership and maintenance regime of the reservoir and undertake a more detailed investigation into the effects of the reservoir overtopping or failing The developer should then liaise with the LPA and reservoir owner to determine applicable emergency planning requirements or mitigation needs Where there is significant flood hazard identified to the site from such failure and especially from unmaintained reservoirs the developer should liaise closely with the LPA about the suitability of the site for development Groundwater There is not a significant risk of groundwater flooding in Bury Rochdale or Oldham but it should not be dismissed as a possibility and the FRA should consider the potential mechanisms that could affect the development site as outlined in Volume Il If a risk of groundwater flooding is found developers should consult with the LPA and Environment Agency at an early stage as to the next steps The risk of groundwater flooding should be considered when assessing suitable SUDS techniques at a strategic level Groundwater flooding is expected to be a design issue For example basements should not be considered in areas at r
38. 3a E E M 3b tam El Essential Infrastructure HV Highly Vulnerable MV More Vulnerable LV Less Vulnerable WC Water Compatible Development would be permitted An FRA would be required in Zones 2 and 3 to demonstrate that the development will be safe and may be required in Zone 1 sites if other sources are present M The Exception Test is required Development should not be permitted in this zone Once the requirement of the Exception Test has been identified three stringent conditions must all be passed in order to pass the Test If all conditions of the Exception Test cannot be met planning permission cannot be granted These conditions see Paragraph D9 of PPS25 are as follows a It must be demonstrated that the development provides wider sustainability benefits to the community that outweigh flood risk informed by a SFRA where one has been prepared If the LDD has reached the submission stage see Figure 4 1 of PPS12 Local Development Frameworks the benefits of the development should contribute to the Core Strategy s Sustainability Appraisal b The development should be on developable previously developed land or if it is not on previously developed land that there are no reasonable alternative sites on developable previously developed land and c A site specific Flood Risk Assessment must demonstrate that the development will be safe without increasing flood risk elsewhere and where possible
39. A The BRO SFRA Volume III provides evidence on a key community basis where the Exception Test may need to be applied It considers the detailed nature of flood hazard taking account of the presence of flood risk management measures such as flood defences The additional detail can also inform a sequential approach to development allocation within flood risk areas and mitigation options where appropriate Rochdale Preliminary Mitigation Review The BRO SFRA Volume IV provides a preliminary review of mitigation options for delivering regeneration for sites that are part of the East Central Rochdale Pathfinder Housing Market Renewal and Town Centre East initiatives JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils o e Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide ae ee OO Date Issued Draft Report Bury MBC David Hodcroft 3 July 2009 Rochdale MBC Francis Comyn Rochdale Development Agency Richard Duddell Oldham Council Georgina Brownridge Environment Agency Chris Waring Digital copy Draft Final Report LPA and EA Comments Bury MBC David Hodcroft 27 August 2009 Rochdale MBC Francis Comyn Rochdale Development Agency Richard Duddell Oldham Council Georgina Brownridge Environment Agency Chris Waring Digital copy Draft Final Report LPA and EA Comments Bury MBC David Hodcroft 30 October 2009 Rochdale MBC Francis Comyn Rochdale Development
40. Agency Richard Duddell Oldham Council Georgina Brownridge Environment Agency Chris Waring Digital copy Final Report LPA and EA Comments Bury MBC David Hodcroft 23 December 2009 Rochdale MBC Francis Comyn Rochdale Development Agency Richard Duddell Oldham Council Georgina Brownridge Environment Agency Chris Waring Digital and printed copies This report describes work commissioned by Bury Rochdale and Oldham Council s under Contract Number 918 701 of 03 03 2009 The Client s representative for the contract was Francis Comyn Chris Isherwood and Hannah O Callaghan of JBA Consulting carried out the work Prepared by Chris Isherwood BSc MSc DipWEM Analyst Prepared by Hannah O Callaghan BSc MCIWEM Senior Flood Risk Policy Analyst Approved by Jonathan Cooper BEng MSc CEng MICE MICWEM MloD Divisional Manager JBA Consulting www jbaconsulting co uk ii Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment j a 2009s0042 Volume I SFRA User Guide CONSUL This document has been prepared solely as an SFRA User Guide for Bury MBC Rochdale MBC and Oldham Council JBA Consulting accepts no responsibility or liability for any use that is made of this document other than by the Client for the purposes for which it was originally commissioned and prepared JBA would like to acknowledge the support of Housing Market Renewal HMR and the SFRA steering group Francis Comyn Rochdale MBC Dav
41. Directive begin at the end of 2011 England and Wales have recently implemented the Flood Risk Regulations 2009 which came into force on the 10th December 2009 transposing the Directive into law These regulations outline the requirement for the Environment Agency and Lead Local Flood Authorities to create Preliminary Flood Risk Assessments PFRAs PFRAs must be completed by the Environment Agency for flooding from main rivers the sea and reservoirs Lead Local Flood Authorities must complete PFRAs for local flood risk i e other sources apart from rivers the sea and reservoirs therefore focusing on ordinary watercourses surface water and groundwater flooding The aims of these PFRAs are to identify significant flood risk areas For these significant flood risk areas flood hazard and flood risk maps must be created by the Environment Agency or Lead Local Flood Authority dependent on the source of risk as above Flood Risk Management Plans FRMP will also need to be created for each flood risk area identified These FRMP must include e Objectives for the purpose of managing flood risk o With the aim of reducing the adverse consequences of flooding to human health economic activity and the environment and o Reducing the likelihood of flooding e The proposed measures for achieving those objectives The timetable for which these assessments or plans should be carried out is outlined below Organisation to Assessment or Pl
42. Environment Agency Flood Warning data and regional and local Flood Plans This SFRA contains useful data to allow emergency planning processes to be tailored to the needs of the area and be specific to the flood risks faced The detailed maps and GIS layers provided should be made available for consultation by emergency planners during an event Figure 6 1 Local and Regional Flood Plans SUC PERT TPES TERETE eee Links certain data Links specific data EA Local A Flood 3 waming hais Council Flood Plan LNRS Council Major CHNAIN Warning data TACTICAL a Plan Incident Plan Links certain data GMLRF Grealer Manchester ocal Resilience Forums 5a Food Plan Recommendakons n n The BRO SFRA Volume Il and IIl provide a number of flood risk data sources that should be used when producing or updating flood plans Plans currently in place or under preparation in Bury Rochdale and Oldham include 1 Environment Agency Flood Warning Plan 2 Greater Manchester Multi Agency Flood Plan draft 3 Bury Council Operational Flood Response Plan 2008 4 Rochdale Draft Multi Agency Flood Response Plan 2008 5 Oldham Emergency Management Plan 2007 The data in the SFRA can be used to update these Flood Plans and the Local Authority Emergency Planners are advised to e Consider and understand the possibility likelinood and spatial distribution
43. JBA Consulting www jbaconsulting co uk 11 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide BE N Table 2 1 Sequential and Exception Tests key steps Applying the Sequential Test during the SA of Development Options Step 1 State the geographical area over which the Sequential Test is to be applied This can be over the entire LPA area but will usually be reduced to communities to fit with functional requirements of development or objectives within RSS or Core Strategy Step 2 Identify reasonably available areas of strategic growth Step 3 Identify the presence of all sources of risk using the evidence provided in this SFRA Step 4 Screen available land for development in ascending order from Flood Risk Zone 1 to 3 including the subdivisions of Flood Risk Zone 3 This can be achieved using the information provided in the Sequential Test Spreadsheet See Volume Il section 4 The screening spreadsheet provides a spatial assessment of each proposed development site provided by the LPA against Flood Zones and Environment Agency surface water susceptibility zones Could all development be located in lower risk areas If not move onto the next Steps 1 and 2 Pass of the Proposed Development Sites Sequential Test Follow Figure 2 4 using the Sequential Test Spreadsheet to Step 6 Identify those sites which should be avoided where risk is considered too great and there is
44. NG FRAMEWORK C 1 1 C 1 2 Introduction The purpose of this section of the report is to identify and outline those high level documents which must be taken into account in preparing this SFRA from a national to a local level The land use planning process is driven by a whole host of policy guidance on a national regional and local level Whilst the majority of these policies are not aimed at mitigating flood risk there are key links at strategic tactical and operational levels between land use and spatial planning Regional and Local Government and Flood Risk Management FRM planning Environment Agency which should be considered as part of a planned and integrated approach to delivering sustainable development The sustainability appraisal will help draw together these links and balance the application of wider social economic and environmental planning policy and guidance Flood risk assessment is required at all levels of the planning process and for all major developments in flood risk areas these play an increasingly important role in assisting effective delivery of key planning objectives Flood Risk Management Drivers The principal FRM policy drivers are brought together in the Government s recently released draft Flood and Water Management Bill and it is an important part of the Government s response to Sir Michael Pitt s Report on the summer 2007 floods It also gives effect to a number of commitments in the Govern
45. P SPD SUDS SWMP UDP UKCIP UKCP UU JBA Consulting www jbaconsulting co uk Areas Benefiting from Defences Annual Exceedance Probability Association of Greater Manchester Authorities Bury Rochdale and Oldham Councils Critical Drainage Area Catchment Flood Management Plans Communities and Local Government Critical Ordinary Watercourse Core Strategy Development Plan Documents Environment Agency European Union Flood Alleviation Schemes Flood Estimation Handbook Flood and Coastal Erosion Risk Management Flood Risk Assessment Flood Risk Management Flood Risk Management Plan Greater Manchester Resilience Forum Indicative Floodplain Map Local Development Documents Local Development Framework Local Planning Authorities Modelling Inception Report National Fluvial and Coastal Defence Database National Property Dataset Preliminary Flood Risk Assessment Practice Guide Planning Policy Guidance Planning Policy Statement River Basin District River Basin Management Plan Regional Flood Risk Assessment Regional Planning Bodies Regional Planning Guidance Regional Spatial Strategy Receptors Vulnerable to Flooding Database Sustainability Appraisal Strategic Environmental Assessment Strategic Flood Risk Assessment Social Flood Vulnerability Index Standard of Protection Supplementary Planning Document Sustainable Urban Drainage Systems Surface Water Management Plan Unitary Development Plan United Kingdom Cl
46. Planning Policy Statement Planning and Climate Change Supplement to Planning Policy Statement 1 JBA Consulting www jbaconsulting co uk 35 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 4 6 3 Overland Flow Paths Developers should follow the advice on managing exceedance and overland surface water flow paths as set out in section 4 6 1 Integrated Drainage There is the potential for groups of development sites coming forward to share a central and integrated solution for managing surface water runoff This should be investigated further through a SWMP or a Drainage Strategy which may or may not be undertaken at the same time as a SWMP A Drainage Strategy will be required to be prepared by the developer s where an integrated solution is necessary due to issues of land constraints geology connection to public sewers and watercourses Such solutions can provide great benefits besides water management including providing Green Infrastructure enhancements recreational facilities improving biodiversity and making communities a better place to live Where there are several sites that would share a communal facility such sites may be funded through developer Section 106 or Community Infrastructure Levy payments Early discussions with the Local Authority and Untied Utilities is essential Drainage Strategies can be particularly useful for considering recommending the implement
47. RO SFRA Volume IV Rochdale Preliminary Mitigation Review BRO SFRA Volume II Level 1 SFRA Introduction to flood risk from all sources at a strategic level using available information Further investigation into mitigation options in Rochdale JBA Consulting www jbaconsulting co uk iv Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide iba SFRA User Guide The BRO SFRA Volume User Guide has been developed to provide specific guidance for SFRA users and should be the first point of call when using the BRO SFRA Each User specific section links to the evidence provided in the BRO SFRA Volume II and Volume III and their associated mapping Spatial Planners Development Management Chapter 2 Chapter 3 Consult on proposed development t t fone Assess site regarding Sequential Draft LDD Flood Risk Policies and Exception Test t t v Link to Sustainability Appraisal Scope appropriate FRA Allocate Development in LDDs Assess FRA Developers H f Emergency Planners Chapter 4 Chapter 6 Consult on proposed development Update Multi agency flood plans t t JBA Consulting Assess site regarding Sequential and Exception Test Provide input to developer flood plans j t Carry out appropriate assessment of flood risk Raise awareness t 1 Provide assessment of possi
48. This must be achieved through the application of the Sequential and Exception Test as outlined in PPS25 By providing a central store for data guidance and recommendations on flood risk issues at a local level the SFRA is an important planning tool that enables the LPA to carry out the Sequential and Exception Test and to select and develop sustainable site allocations with regard to flood risk SFRAs can also provide a much broader and inclusive vehicle for integrated strategic and local Flood Risk Management FRM assessment and delivery by providing the linkage between Catchment Flood Management Plans CFMPs Regional Flood Risk Appraisals RFRAs and Surface Water Management Plans SWMPs The suite of flood risk policy issues and information on the scale and nature of the risks in these various documents needs to be brought into real settings with the SFRA tasked with improving the understanding of flood risk across the districts The Bury Rochdale and Oldham BRO Level 1 and Level 2 Strategic Flood Risk Assessment SFRA are presented across four separate report Volumes and are referred to as the BRO SFRA Volumes I Il Ill and IV throughout this User Guide BRO SFRA Volume Ill Level 2 SFRA BRO SFRA Volume I SFRA User Guide Detailed assessment of actual and residual flood risk within high risk communities Centred on providing guidance for critical users of the BRO SFRA B
49. a Flooding Impacts on People Flooding has a wide range of social impacts which may be difficult to delineate as they are interconnected cumulative and often not quantifiable JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment b a 2009s0042 Volume I SFRA User Guide In small urban or steep upland catchments which have a very rapid response to rainfall or with flooding due to infrastructure failure flood waters can rise very quickly and put life at risk Even shallow water flowing at 2m s can knock children and many adults off their feet and vehicles can be moved by water of 300mm depth The risks rise if the flood water is carrying debris Hazards associated with flood risk to people were investigated by the Environment Agency in which a flood hazard formula was proposed in Phase 2 of the Risks to People Project Flood hazard d v 0 5 DF The output of this formula can be categorised and coloured in accordance to current guidance as described in Table A3 below Table A3 Flood hazard rating Flood Hazard Rating Hazard to People Colouring 0 No Hazard 0 to 0 75 Very Low Hazard 0 75 to 1 25 Dangerous for some 1 25 to 2 0 Dangerous for most Over 2 0 Dangerous for all The impact on people as a result of the stress and trauma of being flooded or even of being under the threat of flooding can be immense This also extends to who
50. a A a e e a a E REAREA 8 2 4 Applying the Sequential Test and Assessing the Likelihood of Passing the Exception Test 10 2 5 Flood Risk and other Land Use Policies 0 0 ccccecsseceeeeeceeeeeeeaeeeeeeeeeeaeeecaaeseeeeeseaeeeeaeeeeaeeseeeeess 14 3 GUIDANCE FOR DEVELOPMENT MANAGEMENT 17 3A Introductio aceiri aaa es atin esis ein ence be oie ea anaiai 19 3 2 The Sequential Test and Exception TeSt ccccccecsseceeeeeceeeeeeeaeeeeeeeseneeeesaaeseeeeeseaeeesaeeseeeseeeeess 19 3 3 Supporting the FRA Process cccccccceeeseeceeeeeceeeeeceaeeeeeeeeceaeeeeaaeeeeaeeseaeeesaaeeeeaaeseeeeeseaeeesaaeeeneees 20 4 GUIDANCE FOR DEVELOPERS nn nn nnn nnn nn enn en nnn nnennennnne 21 Ai WAtFOAUCUON dodmane e e op pod ph E a Eaa a E E restos 21 4 2 The Sequential Test and Exception Test ccccceceseceeeeeceeeeeeeeeeeeeeeseeeeeesaaeseeeeeseeessaesteaeeeeeeeess 22 4 3 Site Specific Flood Risk ASSESSMENMS cccceeceeeeeceeeeeceeeeeeaaeeeeeeeceeaeeesaaeseeeeeseeeeeaeeseeeseeeeess 23 AAS ERA GUI AIN CO nirera e r aa a ences ss baat evn van de E 26 4 5 Considering Other Sources Of FIOOGING cccceesceceeeeceeeeeeeaeeeeeeeceeaeeesaaeeeeeeeseaeeesaeeeeaeeeeeetess 27 4 6 Drainage for New Development c ccceecceceeeeeecaeeeeeeeceeeeecaaaeeeeneeseaeeesaaeeseaaeeeeeeeseaeeesiaeeneaeees 33 5 FLOOD RISK MANAGEMENT
51. able also provides links to data provided in the BRO SFRA Volume II and III which should be used to inform their preparation More detailed analysis should be done within a site specific FRA that should inform these plans JBA Consulting www jbaconsulting co uk 45 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 6 5 jba Table 6 1 Flood Warning Evacuation Plans and SFRA evidence How flood warning is to be provided BRO SFRA Evidence Availability of existing flood warning system Volume II Map 1 3 Rate of onset of flooding Volume III Animations How flood warning is given What will be done to protect the development and contents BRO SFRA Evidence How easily damaged items will be relocated The availability of staff occupants users to respond to a flood warning The time taken to respond to a flood warning Ensuring safe occupancy and access to and from the development BRO SFRA Evidence Occupants awareness of the likely frequency and duration of flood events Volume II Map 1 2 Designing and location of safe access routes Volume III Map 2 1 3 16 Preparing evacuation routes Volume III Map 2 1 3 16 Identify safe locations for evacuees Volume III Map 6 1 6 3 Vulnerability of occupants Volume Appendix F Expected time taken to re establish normal use following an event Please see pages vi f
52. acy currency and relevance of all datasets used and for a central group to manage and update datasets when needed The Data Register also provides details of contacts who supplied the data The organisations listed should be the first contact for any update to the SFRA to make sure the most up to date datasets are used Supplying SFRA Data Whilst all data collected and produced during the BRO SFRA process has been supplied to each LPA report maps GIS modelled output there should be controls on its use It is anticipated that the SFRA report all volumes and associated maps will be published on each Council website as PDFs as the central source of SFRA data and available to download Each LPA will be able to use the modelled output depths hazards and outlines for internal use The use of this information must consider the context within which it was produced The use of this data will fall under the license agreement between the LPA and the Environment Agency as it has been produced using Environment Agency data It should be remembered that the modelling undertaken for the SFRA is of a strategic nature and more detailed FRAs should seek to refine the understanding of flood risk from all sources to any particular site SFRA data should not be passed on to third parties outside of the LPA Any third party wishing to use existing Environment Agency flood risk datasets should contact External Relations in the Environment Agency North West Regio
53. an carry out study Deadline 1st Review River Basin PFRA Environment Agency 22nd Dec 2011 22nd Dec 2017 Lead Local Flood Local Authority PFRA Authorities 22nd Dec 2011 22nd June 2017 River Basin Flood Hazard and Risk environment Agency 22nd Dec 2013 22nd Dec 2019 Maps Local Authority Flood Hazard and Lead Local Flood Risk Maps Authorities 22nd Dec 2013 22nd June 2019 River Basin FRMP Environment Agency 22nd Dec 2015 22nd Dec 2021 Lead Local Flood Local Authority FRMP 22nd Dec 2015 22nd June 2021 Authorities It is expected that PFRAs will be required by March 2011 Therefore work on PFRAs by Lead Local Flood Authorities needs to begin in March 2010 at the latest which allows one year for PRFAs to be compiled and submitted to the Environment Agency for review This will then allow time for review changes and the consolidation of reports from Local Authorities and the Environment Agency in time for the December deadline The Government proposes to use existing flood risk planning outputs of RFRAs and SFRAs to deliver the requirements of PFRAs It is also proposed that local authorities extend their Level 2 SFRAs to look at the impact of flooding on the environment and cultural heritage when determining SFR areas In addition it is proposed that SWMPs will be FRMPs under the Directive and will also be a tool more generally for local flood risk management This integrated approach will underpin t
54. anals British Waterways supplied very helpful information including historical flood locations the location of critical embankments and overflow structures This information shaped the methodology of assessing flood risk from canals discussed in the BRO Level 1 and Level 2 SFRA D 1 2 SFRA Data Management The BRO SFRA should be viewed as a living document for use in the day to day process of planning and development It is therefore important that datasets collected for the SFRA are transparent and accessible A Data Register has been produced and supplied to the individual Councils listing all data received throughout the SFRA process All data was reviewed on receipt and its quality and confidence rated for use in the SFRA This process was purely based on professional judgement and rated on a high to low scale Most data requested was of the quality and accuracy expected Whilst the majority of the datasets could be mapped geographically using Geographic Information Systems GIS helping to visualise the risk of flooding others were not reducing the quality score Historical flooding information was generally marked as both medium quality and confidence as whilst it could be placed on a map there was generally information on the source of flooding The confidence in its precision was also questionable as expected for historical flood records The Data Register will allow intended users of the SFRA to review the accur
55. are critical drainage problems i e the development lies within a Critical Drainage Area Volume II Critical Drainage Area Maps Volume Surface Water Maps Volume III Canal Hazard and Refined Surface Water Maps The development is at risk of flooding from other sources of flooding Volume lII SFRA Asset Database section 2 The development is situated behind flood defences 4d Flood Risk Management Maps possibility of overtopping during extreme flood event Volume III Depth and Hazard Maps for both or breach the 1 in 100 and 1 in 1000 year flood events Volume III Fluvial Breach Maps The development exceeds tha in size Consult Environment Agency The development is within 20m of the bank top of a Main River the Environment Agency will have to consent to any work within 5m of a Main River and Consult Environment Agency are likely to object in principal to any development within these areas Any culverting operation or development which controls the flow of any river or stream COMEDIE Environmentagenty Please see page vi for map references The detail required for each level of FRA is highlighted in Figure 4 1 below The production of a site specific FRA can be seen as an iterative process with those carrying out a Level 1 FRA before moving on to a Level 2 and finally a Level 3 It is appropriate to review the level of risk present to assess whether development is appropriate and achievable befo
56. arger than the width of the canal and its towpath is unlikely to have an overtopping problem unless historic events suggest otherwise If the response to any of these questions is yes canal overtopping flood risk should be carried forward into Stage 3 and would also prompt a review of breach potential Breaching If screening suggests a second stage for canal breach risk is required the following questions should be addressed to scope the appropriate form of a canal breach and hence the flood risk to the development site This may require expert advice from an engineering consultant e Could overtopping cause a breach of the canal Canal bank overtopping could lead to canal embankment failure depending on the nature of the bank material the surface covering overtopping flows and bank geometry Small overtopping flows would be unlikely to lead to breach formation The erosion potential of canal embankments should be quantified e Is a breach possible from the bank geometry A breach is only likely to occur if the canal top of bank levels are sufficiently high above surrounding ground levels to form a raised embankment with a slope sufficiently steep to be susceptible to breach failure British Waterways record particularly high embankments as principal embankments and they hold a record of the locations Preliminary cross sections of the embankment and its constituent materials should be assessed to determine an appropriate breach mechanism e
57. art of the baseline information for the Sustainability Appraisal of LDDs during the scoping and evaluation stages The BRO SFRA provides the relevant information on flood risk to allow the LPA to e Produce appropriate policies for the allocation of sites and development control which avoids flood risk to people and property e Produce appropriate flood risk indicators to inform the Sustainability Appraisal e Undertake the Sequential Test and Exception Test and e Allocate appropriate land use through the Sustainability Appraisal The BRO SFRA Volume III also provides information to allow planners to make strategic decisions that identify the amount and type of development that may be suitable in the community and the reality of it remaining safe from flooding if allocated It also identifies potential strategic mitigation strategies that may be required for development to be feasible in the area Figure 2 1 illustrates the accountability of flood risk within LDDs and the use of SFRA information The flow diagram has been adapted from PPS25 Practice Guide Figure 2 4 p 18 to link in with guidance provided within this User Guide Each colour represents a key stage in the sequential approach process Identical colours are used throughout this Chapter to make it easier to identify what guidance relates to individual steps within the sequential approach sequence It must be acknowledged that Figure 2 1 is a generic flow diagram with each LPA lik
58. ategic Flood Risk Assessment a 2009s0042 Volume SFRA User Guide Flooding from Canals Canals are artificial navigable watercourses many of which date back to the 18th century In many places they are embanked and raised above the surrounding land Locks on canals help pass boat traffic up and down slopes Canals are fed from reservoirs and watercourses and have overflow structures that pass water out of the canal when levels are high to lower level watercourses Many of the inflow and outflow structures on canals are over 200 years old when they were designed to a rule of thumb Flooding from canals can be caused by a variety of circumstances e During times of high flows in feeder watercourses excess water can enter canals e Reservoir failure could divert excess water into a canal e Canals can intercept surface water running off from higher ground e Surface water or excess water in a culverted watercourse that crosses under a canal can build up behind an embanked section of canal which then causes the canal to fail or excess water to enter a canal e The clay lining of a canal could fail resulting in failure of an embanked section dependent on local geology relatively permeable materials such as sand are more prone to failure than impermeable clay In the event that a canal does fail the height that the canal is elevated above surrounding land will affect to some degree the amount of flood hazard that could be caused by de
59. ater Making Space for Water the Pitt Review and the Draft Flood and Water Management Bill that provides for more sustainable management of the water cycle working in partnership across different agencies and new responsibilities for local flood risk management In particular the Draft Flood and Water Management Bill requires developers where practical to include sustainable drainage in new developments to reduce flood risk and improve water quality It includes a requirement on developers to demonstrate that they have met national standards for the application of SUDS techniques before they can connect any residual surface water drainage to a public sewer amending section 106 of the Water Industry Act 1991 As part of their new responsibility for local flood risk management local authorities will be responsible for approving SuDS for new developments and adopting and maintaining them Recognising the above drainage from new developments should incorporate storage with residual discharge of surface water to the following networks in order of preference e Infiltration drainage e g soakaways e Discharge to a watercourse e Discharge to a public sewer The choice of system will be determined by local ground conditions including groundwater levels Whilst infiltration SUDS may be the most suitable for new development developers must consider the risk of contamination to underlying aquifers The guidance below should be used in a
60. ation of and long term management arrangements for SUDS and setting appropriate runoff rates from new development They can be used to support a Supplementary Planning Document A Drainage Strategy would include the timescales for delivering integrated solutions in line with the requirements of PPS12 having considered the delivery programmes of different operating authorities such as United Utilities and the Environment Agency The SWMP may identify that a surface water credit system could support such solutions via Section 106 or Community Infrastructure Levy payments and deliver reductions in surface water runoff from collections of sites Such a system would work on the basis that the developer should achieve maximum reductions in runoff on site as the preferred option and in accordance with the allowable discharge rates outlined in the SFRA as an interim until a Supplementary Planning Document is available Supported by a SWMP Drainage Strategy Where the allowable discharge rates cannot be achieved on site any residual elements could be bought out to enable investments in strategic and integrated measures that reduce the amount of water in the system within a defined drainage catchment Drainage Strategies should be used to set surface water runoff standards for all developments within a defined drainage catchment including considering surface water runoff from windfall sites that may come forward The Level 2 SFRA has made recommendations fo
61. ave been produced for CDAs following the recommendations in the BRO SFRA Volume I section 5 3 1 They have been produced using the same methodology as the national Areas Susceptible to Surface Water Flooding maps However LiDAR data has been used which was then edited to include flow paths and buildings These maps should be used during the Sequential and Exception Test and scoping of a site specific FRA They should also be used during the master planning and the sequential approach to site layout Fluvial Depth Volume Ill Map 2 1 2 16 Volume Ill section 3 0 Fluvial Hazards Volume Ill Map 3 1 3 16 Volume Ill section 3 0 These maps have been produced using detailed Environment Agency 1D hydraulic rivers models and strategic 2D floodplain models created in Ramsbottom Bury Radcliffe Rochdale and Littleborough They identify both depths and hazards during the 1 in 100 year and 1 in 1000 year fluvial flood events Outputs have also been produced including the impact of climate change Defences are included in the model so should identify areas benefitting from 1 in 100 year SOP or greater defences The output should also identify defences which are overtopped during the extreme 1 in 100 year event or where defences are bypassed The hazards maps have been produced as a function of flood depth flood velocity and a debris factor Flood hazards are categorised as No Hazard Very Low Hazard Dangerous for some Dangerous for most and Dangerous for a
62. be linked to Figure 2 5 illustrated below By following Figure 2 5 Spatial Planners should be able to obtain a greater understanding on the level of flood risk present at each key development site that remains following the application of the Sequential Test A review of the flood risk associated with key communities Ramsbottom Bury Radcliffe Rochdale Littleborough and Shaw has been provided in BRO SFRA Volume III section 8 and should help to support the decision on the likelihood of sites passing the Exception Test in these areas Individual sites have already been assessed for Ramsbottom and Littleborough against a number of these key questions and can be found in BRO SFRA Volume III Appendix A During Steps 9 and 10 following Figure 2 3 Spatial Planners should use the Sustainability Appraisal process to assess alternative sites against flood risk indicators and other planning considerations Whilst a balance is require the Exception Test can be a show stopper in that planning permission cannot be granted if all criteria of the Exception Test cannot be met Once this has been completed Steps 11 and 12 can be carried out producing the evidence base for the Sustainability Appraisal allocating appropriate development sites producing flood risk policies and development guidance JBA Consulting www jbaconsulting co uk 13 Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide
63. ble mitigation measures and emergency planning needs Update Multi agency flood plans www jbaconsulting co uk Bury Rochdale and Oldham Councils e i Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide BRO SFRA Mapping The BRO SFRA Volume II and III have produced a suite of strategic flood risk maps These maps should be used to guide development away from high flood risk areas in conjunction with the guidance in PPS25 and its Practice Guide and the guidance provided in the BRO SFRA Volume this document Future identified development sites should also use the suite of strategic flood risk maps produced along with any additional updated data available at the time from the relevant LPA and the Environment Agency Below is a complete list of maps produced in the BRO SFRA Volume II and Ill Sequential Spreadsheet Results Volume II Map 1 1 A C Volume II section 4 0 These maps provide the results of the analysis of council development sites against the flood zones This map should be used as a high level identification of proposed development sites at risk It highlights those sites that are within Flood Zone 3b red 3a orange 2 yellow and 1 green This map is particularly useful for Spatial Planners Flood Zones FZ Volume Il Map 1 2 A O Volume II section 2 2 and 3 2 These maps show Environment Agency Flood Zones 3b 3a 2 1 and proposed development allocations This map should be used to
64. ch Review in 2008 Whilst the current Flood Zones published by the Environment Agency should be used when carrying out the Sequential Test along the Roch this map should provide an indication of actual risk It is likely that the Flood Zones will be updated to resemble these extents once the Environment Agency undertakes their own review Flood Risk Management Volume II Map 1 3 A O Volume II section 2 9 2 11 3 3 These maps provides the location of current Flood Risk Management FRM Measures within the study area including defences areas benefiting from defences 1 in 100 year standard of protection and Environment Agency Flood Warning Areas This map can be used to identify communities currently protected Proposed development in these locations will still be subject to residual risk and should refer to detailed breach and overtopping assessments carried out in the BRO SFRA Volume III Surface Water Flooding Volume Il Map 1 4 A O Volume II section 2 3 and 3 4 These maps have been produced from the Environment Agency Areas Susceptible to Surface Water Flooding Map Users will need to refer to Environment Agency guidance document issued on its applicability Surface water flooding has been classified as high medium and low susceptibility This map has been used within the BRO SFRA Volume II to help identify Critical Drainage Areas See Volume ll JBA Consulting www jbaconsulting co uk vi Bury Rochdale and Oldham Councils be i Strategic Floo
65. cision making and resource allocation are determined by reference to the Greater Manchester Community Risk Register CRR which considers the likelihood and consequences of the most significant risks facing Greater Manchester over the next 5 years The aim of the SFRA so far has been to try and avoid development in flood risk areas in the first instance However it has also been accepted that there is current development in flood risk areas and there will need to be a level of continued regeneration Minimising flood risk to people property and the environment should be considered Flood defences go some way in reducing the current flood risk by providing a standard of protection however there is still a residual risk associated with them as they can be overtopped or breached Flood Warnings is an integral part of flood risk management for which the Environment Agency are the lead authority responsible for warning the public local authorities and emergency services JBA Consulting www jbaconsulting co uk 43 Bury Rochdale and Oldham Councils bd Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide s Along with the Environment Agency Flood Warning systems there are a range of Flood Plans at a regional and local level outlining the major risk of flooding and the tactical and operation plan for key responders These plans are incorporated in Local Authority Major Incident Plans Figure 6 1 identifies the links between
66. contribution to the improvement of flood defence provision that would benefit both the development in question and the local community JBA Consulting www jbaconsulting co uk 38 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 5 4 5 5 4 6 5 5 5 5 1 Building Design The raising of floor levels within a development avoids damage occurring to the interior furnishings and electrics in times of flood If it has been agreed with the Environment Agency that in a particular instance the raising of floor levels is acceptable they should be raised to 600mm above the maximum water level during a 1 in 100 year flood event plus climate change This additional height that the floor level is raised is referred to as the freeboard Depth maps produce in the Level 2 SFRA Volume III will provide an indication of the height of land raising required to lift the development out of the 1 in 100 year event plus climate change Whilst this will provide an early indication detailed modelling will still be required to define these levels further Making the ground floor use of a building water compatible for example a garage is an effective way of raising living space above flood levels Putting a building on stilts is not considered an acceptable means of flood mitigation for new development However it may be allowed in special circumstances if it replaces an existing solid building
67. criptors discussed above but also their intended purpose as shown in Table G1 Table G1 Suitability of SUDS techniques 24 CIRIA 2008 Sustainable Drainage Systems promoting good practice a CIRIA initiative JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide SUDS Technique Infiltration Storage Conveyance Green Roofs x v v Permeable Paving v x v Rainwater Harvesting x v x Swales v v v Detention Basins v v v Ponds x v v Wetlands x v v Source PPS25 Practice Guide PPS25 stresses that Regional Planning Bodies and LPAs should e Promote the use of SUDS for the management of run off e Ensure their policies and decisions on applications support and complement the Building Regulations on sustainable rainwater drainage giving priority to infiltration over first watercourses then sewers e Incorporate favourable policies within Regional Spatial Strategies e Adopt policies for incorporating SUDS requirements in Local Development Documents e Encourage developers to utilise SUDS wherever practicable if necessary through the use of appropriate planning conditions e Develop joint strategies with sewerage undertakers and the Environment Agency to further encourage the use of SUDS The Greater Manchester sub regional SFRA has produced a SUDS Suitability Map and accompanying report which is a
68. cultural heritage Climate change predictions are that flood risk will increase due to more frequent severe storms bringing higher intensity rainfall and increasing run off from land and buildings This will cause rivers and streams to experience higher than normal flood flows and levels and sewers and drains to surcharge more frequently than at present The focus of activity in meeting these challenges will in future be on flood risk management as opposed to simply providing flood defences It is now widely recognised that whilst we can t always prevent flooding occurring we can manage the risks of it happening and reduce the consequences when flooding does happen All operating authorities should aim to manage flood risk through a variety of measures including e Directing development away from flood risk areas wherever possible e Ensuring planning activities locate vulnerable land uses away from high flood risk areas e Providing flood warning and emergency planning activities in flood risk areas e Generally raising awareness of flood risks amongst vulnerable communities e Constructing and maintaining appropriately designed surface water sewers and culverts e Using temporary and demountable flood defences and various flood prevention systems to buildings where appropriate e Constructing new flood defences where they are sustainable and improving and maintaining those already existing e Constructing weirs sluices and other flood flow con
69. d Risk Assessment a 2009s0042 Volume SFRA User Guide Development in the vicinity of this defence should investigate the residual risk further during a site specific FRA Canal Hazard Zone Volume Ill Map 5 1 and 5 2 Volume Ill section 4 0 A Direct Canal Hazard Zone has been created based on professional judgement of potential areas which could flood if the Rochdale or Manchester Bury and Bolton Canal were to overtop or breach This hazard Zone should not influence the spatial planning of development during the Sequential Test but should trigger the need to investigate the residual risk further during any FRA within the zone An Indirect Canal Hazard Zone was created for Rochdale by modelling the effect of a possible canal breach in Littleborough and East Rochdale during a 1 in 100 year fluvial flood event The impact on increased maximum water levels in the River Roch was also assessed in the BRO SFRA Volume III section 4 3 This hazard zone should influence the spatial placement of development during the Sequential Test especially when considering the substitution of vulnerable development when taking into account other sources of flood risk Both of these zones provide an indication of the residual risk or hazard should the canal overtop or breach It is recommended that detailed investigations should be carried out and results incorporated into the final design finished floor levels of the development Site emergency plans shoul
70. d Risk Assessment a 2009s0042 Volume I SFRA User Guide section 5 3 1 These areas have been further assessed in the BRO SFRA Volume III section 5 0 This map should be used during the Sequential Test and during scoping of individual FRAs Pate Volume II Map 1 5 A K Volume II section 2 12 and 3 5 Climate Change Sensitivity Vol il nano olume Ill section 3 These maps have been produced using information from the Greater Manchester sub regional SFRA and updated using detailed model outputs created during the BRO SFRA Volume IlI They should be used as an early indication of areas in which fluvial flooding may significantly increase over the next 100 years These maps are useful when making an assessment of sites that may require the Exception Test by Spatial Planners Development Management and developers Emergency planners may also find them useful while designating access and egress routes Critical Drainage Areas Volume Map 1 7 A D Volume Ill section 5 0 These maps have been produced showing the boundary of Critical Drainage Areas based on known historical flood events natural catchment boundaries and the Environment Agency national Areas Susceptible to Surface Water Flooding map They do not take into account sewered catchments These maps should be used to scope site specific FRAs and as a starting point in the identification of areas for SWMPs Refined Surface Water Volume III Map 1 1 to 1 6 Volume Ill section 5 0 These maps h
71. d also take the residual risk into account Flooding from Multiple Sources Volume Ill Map 6 1 6 3 Volume Ill section 6 0 The flooding from multiple sources map is a summary of those areas at highest risk of flooding It includes fluvial surface water and canal hazard and highlights those areas that are at risk from all three two or just one source This map could be used during the Sequential Test when considering the sources of flooding or to identify the likelihood of passing the Exception Test Areas or communities at risk from more then one source of flooding could require significant mitigation measures and SUDS which could potentially require large areas of land within the development site Use of SFRA Data Whilst all data collected and produced during the BRO SFRA process has been supplied to each LPA report maps GIS modelled output there should be controls on its use It is anticipated that the SFRA report all Volumes and associated maps will be published on each Council website as PDFs as the central source of SFRA data and available to download Each LPA will be able to use the modelled output depths hazards and outlines for internal use This use of this information must consider the context within which it was produced The use of this data will fall under the license agreement between the LPA and the Environment Agency as it has been produced using Environment Agency data It should be remembered that the modelling u
72. d approach in many SFRAs has been not to consider other sources of flooding as a Spatial or strategic issue Summer 2007 provided a stark reminder that the significance of capacity exceedance of artificial and natural drainage systems can be severe for many communities Therefore a clear example was provided that flooding from all sources should be scoped into a SFRA and they should be taken into account through the planning system and that new methods of rapid screening of these risks are required On the back of the Pitt review the Environment Agency has prepared a national map showing areas susceptible to surface water flooding This was developed by JBA from research for the Making Space for Water programme and has been used within this SFRA Development can increase flood risk elsewhere in the following ways e Upstream by restricting the capacity and conveyance function of the watercourse and floodplain system e Downstream by decreasing the volume available for flood storage on the floodplain altering flow routes on the floodplain or by changes to the channel which can increase the flow discharged to downstream locations e By increasing run off from reduced permeability surfaces such as roads roofs and car parks Flooding Likelihood and Consequence Flood risk is generally accepted to be a combination of the likelihood of flooding and the potential consequences arising It is assessed using the source pathway receptor model as
73. d in areas at medium risk A Maps i Q a Areas Susceptible to Surface Water Flooding Maps Assess viability of development sites considering Avoidance of Development in flood risk implications on yield and site layouts High Risk Areas Other Sources of Flooding Maps l Applying the Exception Test Identification of sites requiring Development vuneraity J E gt W gt n gt A gt gt f Exception Test p 2 Core Strategy D Avoidance of Inappropriate Te Are there any other planning objectives that outweigh Paes 5 flood risk Development in High Risk H Sustainability Appraisal Flood Areas o L Risk Indicators Po i a Can it be demonstrated that the development would gt remain safe and not increase flood risk elsewhere 4 Depth amp Hazard Maps P Identification of Appropriate i Can compensation for loss of floodplain storage be Development Sites Residual Risk Maps gt delivered J a Sustainable amp Transparent T Appreciation of Flood Risk z i ithin LDD Ta Appropriate Development Update Sustainability Appraisal of LDDs wirun 2 Sites amp Allocation of Development Sites Application of Development ale Sites will still need site specific FRA to pass Part C of Identification or Appropriate Q the Exception Test Mitigation Techniques amp Site 2 Detailed Site Specific Layouts w Modelling El Essential Infrastructure HV Highly Vulnerable MV More Vulnerable LV Less Vulnerable WC Water Compatable
74. ddition to the Environment Agency Standing Advice Development Sites in the Wider Local Authority Districts Developers should use the following guidance regarding surface water runoff from new developments Allowable Discharge Rates e Development should deliver Greenfield runoff on Greenfield sites up to a 1 in 100 year storm event considering climate change 7 Defra 2008 Future Water Defra Department for Transport HM Treasury and Office of the Deputy Prime Minister 2005 Making Space for water Taking forward a new Government strategy for flood and coastal erosion risk management in England First Government response to the autumn 2004 Making space for water consultation exercise 9 The Pitt Review 2008 Learning lessons from the 2007 floods 10 Defra 2009 Draft Flood and Water Management Bill Crown Copyright 11 Environment Agency Flood Risk Standing Advice for England PPS25 National Version 2 0 Can be accessed online at http www environment agency gov uk research planning 82584 aspx JBA Consulting www jbaconsulting co uk 33 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 4 6 2 e Development should aim for a reduction in surface water runoff rates of 30 for Brownfield sites up to a 1 in 100 year storm event considering climate change reduction of 30 was discussed with the Environment Agency Development Team when preparing the SFRA e Developm
75. e e Requiring new development including residential commercial and transport development to incorporate sustainable drainage systems and water conservation and efficiency measures to the highest contemporary standard e Encouraging retrofitting of sustainable drainage systems and water efficiency within existing developments e Raising people s awareness of flood risks particularly for vulnerable groups and the impacts of their behaviours and lifestyles on water consumption 22 Communities and Local Governments 2008 The North West England Plan Regional Spatial Strategy to 2021 JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide North West River Basin Management Plan In accordance with the Water Framework Directive WFD implemented in December 2000 a River Basin Management Plan RBMP must be produced for each of the 11 River Basin Districts by 2009 The Environment Agency state that RBMPs will have a number of functions but are primarily water for life and livelihoods intended A draft RBMP for the North West was prepared in December 2008 and it was out for consultation until June 2009 A consultation on the Draft River Basin Management Pian To establish a strategic plan for the long term North Wee River Basin District management of the River Basin District To set out objectives for waterbodies a
76. e evidence that the test can Single No z vulnerability be passed by providing Properties Appendix F planning justification and Sect 4 40 4 41 producing a detailed FRA Dependent Developer must provide Changes of Use on land use evidence that the test can No vulnerability be passed by providing Sect 4 42 4 45 Appendix F planning justification and producing a detailed FRA Site Specific Flood Risk Assessments Site specific Flood Risk Assessments FRAs are prepared by those proposing development The principal aims of a FRA are to determine the acceptable management of flood risk to the development proposal itself and any impacts elsewhere and to ensure that the development and its users occupants remain safe in times of flood Once the site has been through the Sequential Test and has been identified as being likely to pass the Exception Test a site specific FRA should be undertaken The LPA and Environment Agency should be consulted in order to scope the content and level of the FRA There are three levels of FRA e Level 1 Screening study to identify whether there are any flooding or surface water management issues that need to be considered further e Level 2 Scoping study to be undertaken if the Level 1 FRA indicates that there are flood risk issues needing further consideration and these risk can be readily quantified e Level 3 Detailed study where further quantitative analysis is required to a
77. e Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide CONSULTING JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment a 2009s0042 Volume SFRA User Guide F 1 FLOOD RISK VULNERABILITY CLASSIFICATION Flood risk vulnerability classifications are provided in Table D 2 of PPS25 These provide recognition that not all land uses have the same vulnerability to flooding Some land uses such as residential developments are more vulnerable to the potential loss of life and damage to personal property and possessions than for example shops and offices Five flood risk vulnerability classifications are contained in PPS25 and these are e Essential infrastructure e Highly vulnerable e More vulnerable e Less vulnerable e Water compatible development Flood Zone 1 Low Probability From a flood risk perspective all land uses are acceptable within Flood Zone 1 Flood risk is not considered to be a significant constraint to development and all land uses listed below are appropriate in this zone e Essential infrastructure e Highly vulnerable e More vulnerable e Less vulnerable e Water compatible development A Screening Study as per PPS25 Practice Guide will be required for development in this zone this will determine whether further assessment of flood risk is required This will take account of historical flood records of loca
78. e I SFRA User Guide Transport and strategic utilities infrastructure can be particularly vulnerable to flooding because interruption of their function can have widespread effects well beyond the area of flooding For example flooding of primary roads or railways can deny access to areas for the duration of the flooding as well as causing damage to the road or railway Flooding of water distribution infrastructure such as pumping stations or of electricity sub stations can result in loss of water or power over large areas This can magnify the impact of flooding beyond the immediate community and reinforces why decisions to locate development in floodplain should be taken very carefully Placing new development or regenerating in flood risk areas has its additional short and long term costs The need to build resistant and resilient properties could significantly increase overall costs of development whilst ongoing maintenance and insurance increase future expenditure Flooding Impacts on the Environment Environmental impacts can be significant and include soil erosion bank erosion land sliding and damage to vegetation as well as the impacts on water quality habitats and flora and fauna caused by bacteria and other pollutants carried by floodwater Flooding can have a beneficial role in natural habitats Many wetland habitats are dependent on annual flooding for their sustainability and can contribute to the storing of flood waters to reduce
79. e damage caused by flooding for example e Electrical circuitry installed at a higher level with power cables being carried down from the ceiling rather than up from the floor level e Water resistant materials for floors walls and fixtures Resilience measures will be specific to the nature of flood risk and as such will be informed and determined by the FRA Making Development Safe Safe Access and Egress The developer must ensure that safe access and egress is provided to an appropriate level for the type of development This may involve raising access routes to a suitable level As part of the FRA the developer should review the acceptability of the proposed access in consultation with the Environment Agency 15 Communities and Local Government 2007 Improving the Flood Performance of New Buildings Flood Resilient Construction JBA Consulting www jbaconsulting co uk 39 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 5 5 2 5 6 5 6 1 5 6 2 5 6 3 For the purpose of the SFRA it is considered appropriate to provide a low hazard environment in access and egress routes associated with new housing developments Environment Agency guidance suggests that all development should have a dry access and egress in the 1 in 100 year event Greater depth and velocity may be permitted where elevated and safe access egress to safe ground are provided It should be
80. e required within the direct zone where scoping identifies raised embankments where their breach would cause potential for loss of life and property damage Overtopping If a third stage for canal overtopping risk is required the following should be addressed Construct a hydraulic model A hydraulic model should be constructed in order to understand the inflows and outflows to the canal during a 1 in 100 year flood event considering climate change Inflows should consider runoff from towpaths and embankments and or slopes if applicable culverts and upstream inflows through bywashes around locks and lock gates Identify overland flow paths If significant overtopping is identified by the inflow outflow model then a model should be constructed in order to understand overland flow paths from the canal in the event of overtopping at the location s from which the site could be affected and the potential depth and hazard associated with canal flooding to the development site Any uncertainties and assumptions related to this model should be clearly stated The national Areas Susceptible to Surface Water Flooding map provided in the SFRA and discussions with the Environment Agency will help to identify critical overland flow paths for further detailed modelling Assess the freeboard required Proposed finished floor levels should be assessed in relation to the risk of canal flooding Risks associated with canal overtopping could be taken into
81. e risk it may pose upon existing and future dwellers of the area as a result of flooding The aim of this SFRA is to provide a better understanding of flood risk in Bury Rochdale and Oldham that can feed into the emerging LDF along side the Greater Manchester Sub Regional SFRA and North West RFRA and enable informed and balanced planning decisions to be made JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils P e e Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide CONSULTING JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide D 1 STAKEHOLDER ENGAGEMENT AND DATA MANAGEMENT D 1 1 Introduction The majority of data provided in both the BRO SFRA Volume II and III has been obtained through consultation with those stakeholders with specific interest in or knowledge of sources of flooding within the study area PPS25 outlines a number of key consultees to the planning process Stakeholders and their involvement within the preparation of the BRO SFRA are discussed in Table D1 Table D1 Stakeholder involvement Stakeholder Involvement LPA Bury Rochdale and Oldham Councils were the main stakeholder for the preparation of this SFRA They focused the scope of the SFRA and provided the detail needed for its production An initial SFRA meeting was held to discuss the req
82. ed In particular it proposes 1 Using SWMPs as a tool to improve co ordination between stakeholders involved in drainage and local management of flood risk JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide 2 Increasing uptake of SUDS by clarifying responsibilities for adoption and management 3 Reviewing the ability for premises to connect surface water drainage automatically into the public sewer system Current roles and responsibilities were considered along with various options for improving the current surface water drainage situation In particular the document recognises that SFRAs and SWMPs already form part of the PPS25 planning framework and there is an aim to enhance their role and make stronger links between surface water drainage and strategic planning Making Space for Water Strategy The Making Space for Water Strategy is a milestone document that confirms the Government s strategic direction for Flood and Coastal Erosion Risk Management FCERM Over the 20 year lifetime of the new strategy Government will implement a more holistic approach to managing flood and coastal erosion risks in England The approach will involve taking account of all sources of flooding embedding flood and coastal risk management across a range of Government policies and reflecting other relevant Government policies in the policies and o
83. eeeeaaeseaaeecaeeecaaeseeaaeeeeaeeseaaeseeaaesseneeseaesseaaesseneeenaees 25 Figure 6 1 Local and Regional Flood Plans ccccceesceeeeeeeceneeeeeaeeeeeeeceeeeeeeaaeeeeeeeseaeeesaaeeseaeeseeeeesseessaeeneaes 44 Table 1 1 Relevant Legislation Plans Policies and Strategies as at October 2009 ceccecteeesteeeteeeeees 2 Table 1 2 SFRA review triggers ccccceceeeeeeeeeeeeeeceeeeeceaeeecaaeeseaeeseeeeeceaeeseaaesseneeseaeeessaaesseaeeseaeeesaeeesaeseeeeeseas 4 Table 2 1 Sequential and Exception Tests key Stes csceecececeeeeeeeeeeeeaeeeeeeeecaeeeeeaaeseneeeseaeeesaeeeeaeeeeeeeess 12 Table 3 1 FRA considerations and SFRA supporting CVIGENCE ccccceeeeeeeeeeeeeneeeeaeeeeaeeseeeeesaeeteaeeteeeees 20 Table 4 1 Development types and application of Sequential and Exception Tests 0 ccccccccsseeessteeeeees 22 Table 4 2 FRA considerations and SFRA supporting CVIGENCE ccccceeeeeeeeeeeeeeeeeeaeeeeneeseceeeetaaeeeeaeeteeeeess 24 Table 5 1 Possible mitigation M ASUIES ccccceeceeeeeceeeeeceaeeeeaeeceeeeeecsaeeeeaaeseeeeeseaeeesaaeseeaeeseeeeeseaeeesaeeseenees 41 Table 6 1 Flood Warning Evacuation Plans and SFRA e VIdG NGCE cccccccessteeeeeesneeeeesnneeeeeseneeeeesnaeeeeess 46 JBA Consulting www jbaconsulting co uk x 2009s0042 Volume I SFRA User Guide Bury Rochdale and Oldham Councils e e Strategic Flood Risk Assessment J a RVFD SEA SFRA SFVI SO
84. el of any part of the site lower than the canal bank level and within 1km of the canal e ls the canal embanked above the site JBA Consulting www jbaconsulting co uk 27 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume SFRA User Guide e Have there been past incidences of canal breach which may show that the location of the development site is vulnerable to canal breach If the response to any of these questions is yes canal overtopping and breach flood risk should be considered in a Scoping Stage Stage 2 Scoping Overtopping If the screening identifies a second stage for canal overtopping risk is required the following questions should be addressed e If high water levels occur in the canal close to the site based on an assessment of both bank levels is it possible that canal spill is likely to be towards as opposed to away from the site If the opposite bank to that of the proposed site is lower it is likely that any spill will occur from this canal bank and not from the canal bank adjacent to the site e Have there been past incidences of canal overtopping which may show that the location of the development site is vulnerable to canal overtopping The canal pound is the body of water contained between the lock gates The canal pound length is the distance between the lock gates for the body of water The canal pound length adjacent to the site may receive water from an upper pound and
85. ely to be at different stages of its LDD process It is more likely that the LPA may have produced a Core Strategy prior to undertaking the Sequential Test with the benefit of the data in this SFRA or are preparing their LDDs and allocating development PPS25 Practice Guide assumes a strong link with the Sustainability Appraisal and the SFRA influences all stages of the Sustainability Appraisal Therefore the generic flow diagram in both PPS25 Practice Guide and this User Guide should be amended to take account of steps which may have previously been taken within the first pass of the Sustainability Appraisal stage JBA Consulting www jbaconsulting co uk 6 F Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment a 2009s0042 Volume SFRA User Guide ee e Figure 2 1 Taking flood risk into account in LDDs Undertake a Level 1 SFRA Use the SFRA to identify where development can be located in Use the SFRA to inform scope of the Sustainability Appraisal of LDD Consult on scope of Sustainability Appraisal areas with a low probability of flooding Strategic Sequential Test See steps 1 5 of section 2 4 Assess alternative development options using Sustainability Appraisal considering flood risk and other planning objectives Can sustainable development be achieved through new development located entirely within areas with a low probability of flooding Development Site Sequential Test See st
86. ence should be included within the freeboard of finished floor levels where possible It is the developer s responsibility to assess whether this freeboard is adequate and the master plan for the site reflects the need to retain and guide overtopping flows to a safe area Within areas of fluvial or surface water flood risk FRAs will need to consider this along with the measures taken to manage these other sources Typically a freeboard value is added to the 1 plus climate change flood level to take into account uncertainty and operational issues Traditionally a value of 600mm is taken Where a FRA is being undertaken in both the direct and indirect canal hazard zone then the freeboard should be assessed from first principles taking into account flood risk from the canal as another source of uncertainty A higher freeboard allowance may be required as a result The SFRA has identified that in Rochdale for example the increase in flood level as a result of a coincident breach and flood event is approximately 300 to 400mm It is anticipated that this could be included within a traditional freeboard value although the FRA would need to prove that uncertainty associated with the fluvial sources are not more significant that normal A higher freeboard allowance in the indirect canal hazard zone of 300mm should be adopted if no further analysis is undertaken Reservoirs As part of a FRA developers should liaise with Local Authority Emergency Planners
87. ent should be designed so that there is no flooding to the development in a 1 in 30 year event and so that there is no property flooding in a 1 in 100 year plus climate change event e There may be local variations on this where outfalls are directly to larger watercourses and hence surface water discharges from development sites can pass downstream before the main peak on the watercourse Wherever possible this should be achieved through the implementation of SUDS Source control should be considered firstly There may be opportunities to deliver SUDS though integrated solutions for collections of strategic sites The future ownership and maintenance of SUDS systems should be discussed at the planning application stage with the relevant sections of the LPA including Highways and Drainage United Utilities and the Environment Agency More detail on SUDS is available in Appendix G The developer should liaise closely with the local authority drainage engineer the Environment Agency and United Utilities to determine appropriate discharge rates The developer should prove that surface water discharges from the site will not have an adverse impact on flood risk elsewhere with reference to investment planning by Untied Utilities that may increase the capacity of the sewer network in the area Overland Flow Paths Underground drainage systems have a finite capacity and regard should always be given to larger events when the capacity of the network wil
88. entification of areas of floodplain that should be safeguarded for flood management purposes e identify the level of detail required for site specific flood risk assessments in particular locations e Determine the acceptability of flood risk in relation to emergency planning capability and how the existing and proposed community would respond to a flood event B 1 2 Greater Manchester Sub Regional SFRA The Greater Manchester sub regional SFRA was published in August 2008 on behalf of the Association of Greater Manchester Authorities AGMA The main objective of the SFRA was to bring together existing information and identify where further more detailed assessments are required 20 AGMA 2008 Greater Manchester Sub regional Strategic Flood Risk Assessment JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide The Greater Manchester sub regional SFRA was undertaken to provide a baseline and scope from which more detailed District level assessments can be completed The principal aims of the SFRA were to 1 Assess and identify the different levels of flood risk high medium or low and sources of flooding main river Critical Ordinary Watercourse COW surface water canal reservoir etc across Greater Manchester at both the sub regional level using river catchments and District level and to map these for statutory land use p
89. ep or fast flowing debris laden water alongside the cause of failure there will be a greater volume of water from failures caused by water building up behind an embankment The amount of water that can escape depends on the pound length which is the distance between two locks because the maximum volume of water that will outflow will be contained between the two locks Hazard from canal failure is likely to be lower than that from river defences that fail due to the limited volume of water and the longer time that it takes water to drain linearly towards the location of failure The risk of flooding from canals is reduced by regular inspection by British Waterways or others to identify any problems with inflow and outflow structures canal lining or embankments Defence Failure The condition of existing flood defences is an important consideration for local authority planners when allocating new development PPS25 considers that defended areas i e those areas that are protected to some degree against flooding by the presence of a formalised flood defence are still at risk of flooding and therefore sites within these areas must be assessed with respect to the adequacy of the defences The condition of existing defences is provided in the form of a rating 1 to 5 and is a reflection of any signs of obvious structural problems The condition rating is determined on the basis of visual inspection focussing on obvious signs of structu
90. eps 6 8 of section 2 4 Use the SFRA to apply the Sequential Test Likelihood of passing Exception Test See steps 9 10 of section 2 4 If the Exception Test needs to be applied undertake a Level 2 SFRA Assess alternative development options using Sustainability Appraisal balancing flood risk against other planning objectives a p 2 Use the Sustainability Appraisal to inform the allocation of land in accordance with the Sequential Test Include a policy on flood risk considerations and guidance for each site allocation Where appropriate allocate land to be used for flood risk management purposes Include the results of the application of the Sequential Test and Exception Test where appropriate in the Sustainability Appraisal Report Use flood risk indicators and Core Output Indicators to measure the Plan s success JBA Consulting www jbaconsulting co uk y 2009s0042 Volume I SFRA User Guide Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment J a 2 2 2 3 Sequential Test When allocating or approving land for development in flood risk areas those responsible for making development decisions are expected to demonstrate that there are no suitable alternative development sites of the type and nature proposed by the Core Strategy located in lower flood risk areas PPS25 introduces a Sequential Test that is core to the SFRA process The Sequent
91. er Defra 2005 DCLG 2007 e Learning Lessons from the 2007 Floods Sir Michael Pitt 2008 Regional level e River Irwell Catchment Flood Management e North West Regional Spatial Strategy Plan Environment Agency 2008 Government Office for the North West 2008 e North West Regional Flood Risk Appraisal e North West River Basin Management Plan 4NW 2008 Environment Agency 2008 e Greater Manchester sub regional SFRA AGMA 2008 Local level e Flood risk assessments for development e Emerging Local Development Frameworks sites referred to as necessary in SFRA for Bury Rochdale and Oldham volumes e Existing UDPs for Bury Rochdale and Oldham All legislation plans policies and strategies were relevant as at October 2009 Development of the SFRA A Steering Group was set up for the SFRA comprising of key officers from Rochdale Bury and Oldham Councils Rochdale Development Agency RDA and the Environment Agency EA British Waterways and United Utilities were consulting during the development of the SFRA More information on stakeholder engagement and data management is provided in Appendix D The Bury Rochdale and Oldham BRO Level 1 and Level 2 Strategic Flood Risk Assessments SFRA are provided within four volumes e Volume I SFRA User Guide e Volume Il Level 1 SFRA e Volume Ill Level 2 SFRA e Volume IV Rochdale Preliminary Mitigation Review Volume
92. er level to rise above the normal maintained water level plus this factor of safety If the canal was to breach then a greater volume of water could leave the canal over a much shorter amount of time The SFRA has identified that the residual risk associated with overtopping and breaching from canals is a particularly important issue within the three local authority boundaries Whilst a low probability occurrence the consequences are such that this source should be considered within a flood risk assessment that accompanies a development application The BRO SFRA Volume III has identified indicative canal hazard zones that will aid in scoping where a FRA will be required and what level of detail is appropriate Flood risk from canals may not affect the same areas identified in the flood zone maps or it may add another source of flooding that must be considered It should be noted that the Rochdale Canal is a designated Special Area of Conservation This may affect the way in which any proposed mitigation is delivered or managed including a potential requirement for Appropriate Assessment which would involve consultation with Natural England Indicative Canal Flood Hazard Zones As part of the Level 2 SFRA a direct canal flood hazard zone has been produced to identify those areas potentially at risk from the Rochdale and Manchester Bury and Bolton Canals This zone is indicative and is based on areas geographically adjacent to the canal system and
93. es student halls of residence drinking establishments nightclubs and hotels e Non residential uses for health services nurseries and educational establishments e Landfill and sites used for waste management facilities for hazardous waste 2 e Sites used for holiday or short let caravans and camping subject to a specific warming and evacuation plan Less Vulnerable e Buildings used for shops financial professional and other services restaurants and cafes hot food takeaways offices general industry storage and distribution non residential institutions not included in more vulnerable and assembly and leisure Land and buildings used for agriculture and forestry Waste treatment except landfill and hazardous waste facilities Minerals working and processing except for sand and gravel working Water treatment plants Sewage treatment plants if adequate pollution control measures are in place Flood control infrastructure Water transmission infrastructure and pumping stations Sewage transmission infrastructure and pumping stations Sand and gravel workings Docks marinas and wharves Navigation facilities MOD defence installations Ship building repairing and dismantling dockside fish processing and refrigeration and compatible activities requiring a waterside location Water based recreation excluding sleeping accommodation e Lifeguard and coastguard stations e Amenity open space nature
94. es may still involve new or improving and maintaining existing flood defences where justified to protect increasingly vulnerable communities Current key policy related documents provide LPAs with important and valuable knowledge on the strategic direction of flood risk management and assist their strategic land use planning decision making for re generation inward investment and growth etc Key documents currently influencing FRM policy are e EU Floods Directive EU 2007 e Draft Floods and Water Management Bill Defra 2009 e Future Water Defra 2008 e Improving Surface Water Drainage Defra 2008 e Making Space for Water Defra 2005 e Planning Policy 25 Development and Flood Risk DCLG 2006 e Planning Policy 25 Development and Flood Risk Practice Guide DCLG 2009 e Learning Lessons from the 2007 Floods Sir Michael Pitt 2008 e Catchment Flood Management Plans currently being implemented JBA Consulting www jbaconsulting co uk 2009s0042 Volume I SFRA User Guide Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment J a e Shoreline Management Plans currently being revised EU Floods Directive The EU Floods Directive aims to reduce and manage the risk floods pose to human health the environment cultural heritage and economic activity Member States have two years in which to transpose its provisions into domestic legislation and the first requirements of the
95. ese policies are not aimed at mitigating flood risk there are key links at strategic tactical and operational levels between land use and spatial planning Regional and Local Government and Flood Risk Management FRM planning Environment Agency which should be considered as part of a planned and integrated approach to delivering sustainable development Table 1 1 lists relevant legislation plans policies and strategies More detail on these is provided in Appendix C 1 AGMA 2008 Greater Manchester Sub Regional SFRA 2 Communities and Local Government 2006 Planning Policy Statement 25 Development and Flood Risk 3 Communities and Local Government 2009 Planning Policy Statement 25 Development and Flood Risk Practice Guide JBA Consulting www jbaconsulting co uk 1 2009s0042 Volume I SFRA User Guide Bury Rochdale and Oldham Councils e te Strategic Flood Risk Assessment J a 1 2 1 2 1 1 2 2 Table 1 1 Relevant Legislation Plans Policies and Strategies as at October 2009 Flood risk Planning National level e EU Floods Directive EU 2007 e Planning Policy 25 Development and Flood e Flood Risk Regulations 2009 MISR R A pR Defra 2009 Risk Practice Guide DCLG 2009 _ e PPS1 Delivering Sustainable Development fia Sa a a ODPM 2005 2008 aurane Water Drainage Delra e Planning Policy Statement Planning and Climate Change supplement to PPS1 e Making Space for Wat
96. espect of future coastal erosion planning applications e Local authorities will have an enhanced leadership role in local flood risk management which includes ensuring that flood risk from all sources including from surface run off groundwater and ordinary watercourses is identified taken account of in the spatial planning process and managed as part of locally agreed work programmes e Local authorities will develop a suite of measures for managing local flood risk for example surface water mapping appropriate development planning and collating information on flood risk and drainage assets e County and unitary authorities will be responsible for local flood risk assessment as Lead Local Flood Authorities and lead in ensuring the production of SFRAs and SWMPs e SWMPs will have a stronger role in coordinating development and investment planning e County and unitary authorities will lead new local partnerships and have responsibility for adopting and maintaining sustainable drainage systems SUDS in new development where they affect more than one property e The automatic right to connect surface water drains and sewers to the public sewerage system will be ended and developers will be required to put SUDS in place in new developments wherever practicable e Surface water connection to public sewers will be conditional on meeting new national standards for SUDS and the approval of a SUDS approving body will be needed and a certificate i
97. evel of information available is appropriate to the scale and nature of the flood risk issues and the location and type of development proposed avoiding expensive studies and the development of mitigation measures where it is not necessary Figure B1 highlights the hierarchical approach to flood risk assessment As stated in PPS25 the three principle levels of assessment comprise e Regional Flood Risk Appraisal RFRA a broad overview of flood risk issues across a region to influence spatial allocations for growth in housing and employment as well as to identify where flood risk management measures may be required at a regional level to support the proposed growth e Strategic Flood Risk Assessment SFRA an assessment of all types of flood risk informing land use planning decisions This will enable the LPA to apply the Sequential Test in PPS25 and allocate appropriate sites for development whilst identifying opportunities for reducing flood risk e Site Specific Flood Risk Assessment FRA site or project specific flood risk assessment to consider all types of flood risk associated with the site and propose appropriate site management and mitigation measures to reduce flood risk to and from the site to an acceptable level JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide Figure B1 Hierarchical approach to Flood Risk Assessmen
98. evelopment Developers should primarily focus on lower Flood Zones in preference to Flood Zone 3 Any proposals for development within Flood Zone 3 will require developers to undertake a detailed Flood Risk Assessment It should be noted that constraints to development are likely to be significant and developers should seek advice from the Councils and the Environment Agency as to the specific requirements for assessment Flood Zone 3 is subdivided into Zones 3a and 3b Flood Zone 3b is the portion of floodplain that provides natural and or managed attenuation It can be all or part of the flow area and owing to the frequency of inundation Zone 3b areas are considered to be Functional Floodplain Urban areas are generally considered to be Zone 3a so for the purpose of this SFRA Brownfield sites will be assumed Zone 3a Zone 3a is potentially suitable for water compatible and less vulnerable land uses The more vulnerable and essential infrastructure uses should only be permitted in this zone if the Exception Test is passed Highly vulnerable development should not be permitted in this zone In Zone 3b only essential infrastructure subject to exception testing and water compatible uses may be permitted Where sites are partially located within Flood Zone 3b it is recommended that Councils should avoid development by specifying water compatible uses or Public Open Space for these areas Land use vulnerability classifications and flood zones are
99. f rainfall tides geology topography rivers and streams and man made interventions such as flood defences roads buildings sewers and other infrastructure As was seen in the summer 2007 floods flooding can cause massive disruption to communities damage to property and possessions and even loss of life For this reason it is important to avoid developing in flood risk areas in the first instance Where this is not possible development should be directed to areas with the lowest possible level of flood risk Having exhausted all opportunities to direct development away from areas of flood risk then the allocation of land for development must consider the vulnerability of the proposed land use to flooding and take measures to minimise flood risk to people property and the environment This is the thrust of the risk based sequential approach to managing flood risk and it is the backbone of PPS25 Current Government policy requires local authorities to demonstrate that due regard has been given to the issue of flood risk as part of the planning process It also requires that flood risk is managed in an effective and sustainable manner and where new development is as an exception necessary in flood risk areas the policy aim is to make it safe without increasing flood risk elsewhere and wherever possible reduce flood risk overall Within the hierarchy of regional strategic and site specific flood risk assessment a tiered approach ensures that the l
100. face Water Flooding map Page v of the Practice Guide draws out some of the more substantial changes from the June 2008 version of the guide Some of the key ones relevant to this SFRA are highlighted below e Additional advice on applying the sequential approach at the regional level over a longer time frame e Further advice on the issues relating to guidance provided within SFRAs including on the role of surface water management plans e Updated guidance on climate change impacts e Updated guidance on applying the sequential approach to other sources of flooding e Further advice on the application of the Sequential Test including on the availability of alternative sites e Further clarification on defining functional floodplains21 As mentioned above consultation on proposed amendments to PPS25 are expected in an updated PPS25 in spring 2010 and will be reflected in further iterations of the Practice Guide 21 Communities and Local Government 2009 PPS25 Practice Guide JBA Consulting www jbaconsulting co uk 2009s0042 Volume SFRA User Guide Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment J a C 1 4 Other Planning Policy Statements PPS1 Delivering Sustainable Development published in February 2005 by the Office of the Deputy Prime Minister sets out the overarching planning policies for the delivery of sustainable development across the planning system and sets t
101. facilitate the application of the Sequential Test by Spatial Planners and Development Management officers See section 2 and 3 for more guidance Flood Zone 3 Depth Grid Volume II Map 1 6 A O Volume II section 3 6 A strategic depth grid has been created using the extent of Flood Zone 3 and topographic data These maps should provide an early identification of the variation of risk throughout the Flood Zone Users should refer to Maps 2 1 to 2 16 from the BRO SFRA Volume III for detailed model depths and hazards where available Holcombe Brook Revised FZ Volume II Map 1 2 P Volume II section 3 0 The 1 in 100 year Flood Zone 3 and 1 in 1000 year Flood Zone 2 flood events were rerun along Holcombe Brook using the original broad scale modelling methodology but incorporating LIDAR data instead of NEXTMAP Whilst the current Flood Zones published by the Environment Agency should be used when carrying out the Sequential Test along the Roch this map should provide an indication of actual risk It is likely that the Flood Zones will be updated to resemble these extents once the Environment Agency undertakes their own review River Roch Revised FZ Volume II Map 1 2 Q Volume II section 3 0 The 1 in 100 year Flood Zone 3 and 1 in 1000 year Flood Zone 2 flood events were rerun along the River Roch using the detailed 1D 2D model developed for the BRO Level 2 SFRA These models also included hydrology updated by the Environment Agency during the River Ro
102. flood risk elsewhere Itis important to recognise the value of maintenance or restoration of natural riparian zones such as grasslands which protect the soils from erosion and natural meadows which can tolerate flood inundation The use of Green Infrastructure throughout the river corridor can also play a vital role in enhancing the river environment as well as safeguarding land from future development protecting people and buildings from flooding and reducing flood risk downstream A natural floodplain can help accommodate climate change and improve the quality of rivers and associated wetlands to help achieve good status by 2015 under the Water Framework Directive Meeting WFD objectives involves not only ecosystems water quality drought and flood impact considerations but also the physical characteristics and morphology of the river channel floodplain and associated structures JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils a e e Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide CONSULTING JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide B 1 FLOOD RISK ASSESSMENT HIERARCHY B 1 1 Introduction Flooding is a natural process and does not respect political demarcations or administrative boundaries it is influenced principally by natural elements o
103. flood storage would be reduced by raising land above the floodplain adversely impacting on flood risk downstream Compensatory flood storage must be provided and should be on a level for level volume for volume basis on land that does not currently flood but is adjacent to the floodplain in order for it to fill and drain It should be in the vicinity of the site and within the red line of the planning application boundary unless the site is strategically allocated Where the site is entirely within the floodplain it is not possible to provide compensatory storage at the maximum flood level and this will not be a viable mitigation option Compensation schemes must be environmentally sound The need for compensatory storage must been discussed at the earliest stage of planning as this will be a major constraint as this requirement may have significant implications for the yields achieved for individual sites due to the associated land take this may require Raised Defences Construction of raised floodwalls or embankments to protect new development is not a preferred option as a residual risk of flooding will remain Compensatory storage must be provided where raised defences remove storage from the floodplain Temporary or demountable defences are not acceptable flood protection for a new development unless flood risk is residual only Developer Contributions to Flood Defences In some cases it may be necessary for the developer to make a
104. g www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide English and Welsh water companies are required to maintain a register of flooding incidences due to hydraulic capacity problems on the sewage network This database identifies properties where flooding has occurred on a frequency of 1 in 5 years and 1 in 10 years The database is known as DG5 and DG10 registers A register for 1 in 20 years is also recorded which includes properties under investigation Whilst this data can give an idea of those areas with limited drainage capacity it must be acknowledged that it is a register of properties that have flooded due to the hydraulic inadequacies of the sewer systems not properties at risk of flooding Therefore it has limiting usefulness in predicting future flooding Data generated using hydraulic network models such as InfoWorks potentially provides a very useful tool with which to predict more widespread potential for sewer flooding and the use of such tools should be investigated during a Surface Water Management Plan Flooding from Reservoirs Reservoirs can be a major source of flood risk as experienced during the 2007 summer floods where 18 reservoirs were affected across England Whilst the probability of dam failure or breaching occurring is very small the consequences of such an event can be devastating thereby presenting a risk of flooding which
105. g at Developing a Broader Portfolio of Options to Deliver Flooding and Coastal Solutions has been carried out as part of this programme and is very useful to local authorities and other operating authorities in their strategic planning of flood risk management Outputs from this work are available from Defra Quarterly update reports are released providing details of progress made and key achievements These reports can be access via the Making Space for Water website at http www defra gov uk environ fcd policy strategy htm JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide The Pitt Review The Pitt Review was carried out following the severe floods of summer 2007 and is a key document for local authorities in their consideration of flood risk management Sir Michael Pitt was asked by Ministers to conduct an independent review of events and report on the lessons that should be learned The Review collected evidence by visiting affected areas and examining over 600 written statements submitted by victims of the floods The final report was released in June 2008 and contains detailed findings conclusions and 92 recommendations for action covering all aspects of strategic and local flood risk management These interim conclusions are intended to shape the National approach to flood management and can be accessed via the Defra websi
106. ge areas and sewers at capacity was also requested A representative from United Utilities stated that this information would not be available for the SFRA due to the possibility of misinterpretation of data and it would be more effective if the SFRA used United Utilities modelled outputs However United Utilities were also unwilling to share this data United Utilities Drainage Areas and sewer records were not made available for this SFRA Bury Rochdale and Oldham Councils should continue to liaise with United Utilities in conjunction with the Environment Agency and the wider Greater Manchester Authorities to explore how they can contribute to the understanding of flood risk now or in the future United Utilities have recently made additional data available for SFRAs Flood risk data was not available in time for the Level 1 and Level 2 SFRAs British Flood risk from British Waterways Canals was highlighted in the Greater Waterways Manchester sub regional SFRA as a major source of residual risk in Bury Rochdale and Oldham as flooding has been known to occur but information on the risk is relatively unknown JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils bd Strategic Flood Risk Assessment a 2009s0042 Volume SFRA User Guide Stakeholder Involvement An initial meeting was held between British Waterways and a Chartered Engineer from JBA to discuss the risk associated with c
107. gic mitigation requirements identified in Volume III section 9 and or LDD o Refer developers to section 4 5 and 6 of this SFRA User Guide e Consult with Environment Agency over FRA acceptance approval JBA Consulting www jbaconsulting co uk 1z Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume SFRA User Guide Figure 3 1 Planning applications and flood risk Planning Application Preparation Identify proposed development site Has the site been allocated for the proposed land use type in the Local Development Document LDD using the Sequential Exception Tests Does the proposed development have the potential to pass the Sequential Test Does the proposed development have the potential to pass Part A and B the Exception Test Does the proposed development have the potential to pass Part C the Exception Test Developer to confirm with the LPA whether a FRA is required amp if consultation is required with other flood risk consultees Undertake a pre application consultation with flood risk consultees Developer to agree the scope of an appropriate FRA with the LPA amp flood risk consultees Developer to undertake FRA LPA to assess whether FRA fulfils all requirements Submit application to LPA using standard Planning Application Form amp accompanying FRA LPA assessment of planning application with advice from the Environment Agency amp other operating authorit
108. h re occupation sometimes not being possible for over a year The costs of flooding are increasing partly due to increasing amounts of electrical and other sophisticated equipment within developments The damage flooding can cause to businesses and infrastructure such as transport or utilities like electricity and water supply can have significant detrimental impacts on local and regional economies The long term closure of businesses for example can lead to job losses and other economic impacts The vulnerability of buildings is important to understand in terms of their occupants and their type For example it is much more difficult to evacuate the old and ill from hospitals and care homes than people working in offices or industrial areas Building types that need to be operational during and post flood such as ambulance stations and emergency response centres are also vulnerable as if the services they provide are disrupted by flooding it will place the immediate community at greater risk 18 Defra and Environment Agency 2006 Flood Risks to People Phase 2 Gibbs G Surendran S Wade S and Udale Calrke H 2008 Supplementary note on flood hazard ratings and thresholds for development planning and control purpose Clarification of the Table 13 1 of FD2320 TR2 and Figure 3 2 of FD2321 TR1 JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment jb a 2009s0042 Volum
109. he planning system and guide the location of future development to avoid and minimise flood risk whilst also meeting the requirements of the Floods Directive Local authorities through their land use planning activities have a key role to play Draft Flood and Water Management Bill The Draft Flood and Water Management Bill proposes new unifying legislation covering all forms of flooding and shifting the emphasis from building defences to managing risk It aims to JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide e Reduce the likelihood and impacts of flooding e Improve the ability to manage the risk of flooding by clarifying who is responsible for what e Reduce pollution and improve water quality e Give water companies better powers to conserve water during drought e Reduce red tape and other burdens on water and sewerage companies e Improve the overall efficiency of the industry A number of proposals in the draft Bill have particular implications for local authorities land use planning and related flood risk These include e The Environment Agency will be given a strategic overview role covering all forms of flooding and will coordinate maps and plans in relation to the sea main rivers and reservoirs it will also be given the same powers as councils to carry out coastal erosion works and may be a statutory consultee in r
110. he Code for Sustainable Homes More use of sustainable drainage systems in new developments Regional Spatial Strategy and Local Development Frameworks should include policies that address the potential impacts of proposed levels of development to water resources water quality biodiversity river restoration green infrastructure contaminated land and managing surface water and flood risk In 2006 the North West Development Agency NWDA launched the regions Climate Change Action Plan Rising to the challenge A Climate Change Action Plan for England s North West The Action Plan sets out the North West s vision and outlines the associated outcomes to be achieved by 2020 In order to achieve these outcomes the plan recognises that it must focus on twin objectives of reducing regional greenhouse gas emissions and more importantly to this SFRA adapting to those effects of climate change that are now unavoidable One of the unavoidable effects of climate change is its impact on flood risk Rising to the Challenge 23 Environment Agency 2008 A Consultation on the Draft River Basin Management Plan North West River Basin District JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide Flood risk related climate change issues are extremely important to the future management of flood risk in the UK and beyond These is
111. he Regional Sustainability Appraisal RSustainability Appraisal and the Strategic Environmental Assessment SEA The timing of the revised guidance in PPS25 prevented the consideration of a RFRA within the sustainability appraisal for the draft and subsequent RSS It is envisaged that the information in the RFRA alongside knowledge from SFRAs and Catchment Flood Management Plans will provide a useful input to future rounds of the sustainability appraisal for the RSS The outputs of the RFRA help to identify where there may be a need for further flood risk assessment work to be undertaken particularly in respect of Strategic Flood Risk Assessments SFRAs and where strategically significant developments are proposed in areas currently at risk of flooding Even where SFRAs already exist the RFRA helps to place specific local authority flood risks into a regional context showing the variation of risk and the interdependency between neighbouring authorities and river sub catchments Flooding does not respect local authority administrative boundaries and the RFRA provides a mechanism to help local authorities work better together and with key stakeholders to consider communicate and share common or similar flood risk management policy objectives opportunities and constraints The RFRA assessed significant flood risk by e Undertaking a survey of local authorities to gauge their broad assessment of flood risk issues e Reporting on the work unde
112. he tone for other planning policy statements PPS1 explicitly states that development plan policies should take account of flooding including flood risk It proposes that new development in areas at risk from flooding should be avoided Planning authorities are also advised to ensure that developments are sustainable durable and adaptable including taking into account natural hazards such as flooding PPS1 also places an emphasis on spatial planning in contrast to the more rigid land use planning approach which it supersedes Planning authorities will still produce site specific allocations and a proposals map as LDDs but their Core Strategy will be more strategic and visionary in content and will take into account the desirability of achieving integrated and mixed use development and will consider a broader range of community needs than in the past With regard to flood risk it will be important for the Core Strategies and accompanying Supplementary Planning Documents to recognise the contribution that non structural measures can make to flood management Planning Policy Statement Planning and Climate Change a supplement to PPS1 published in December 2007 sets out how the Government expects the planning system to address climate change It explains that there is a compelling scientific consensus that human activity is changing the world s climate The evidence that climate change is happening and that man made emissions are it
113. hen development is sited in such areas e Protection measures to provide at minimum the standards of protection specified in PPS25 e Provision of features such as sacrificial areas and compartmentalisation to reduce the consequences of a flood event should one occur such as functional floodplain e Use of construction techniques that increase the flood resistance and resilience of buildings The document proposes that RSSs and LDFs should take full account of flood risk and incorporate the sequential approach in PPS25 Moreover the document encourages integration with other planning systems in particular Catchment Flood Management Plans Use of European Union EU funding streams such as Interreg IIIB is recommended where applicable to enable Local Authorities to undertake projects aimed at advancing knowledge and good practice in flood risk management Making Space for Water Programme of Work The Making Space for Water Programme of Work was developed following consultation and takes account of any relevant recommendations that emerged from the Pitt Review into the 2007 floods that affected many parts of England One of Defra s and CLG s early outputs from the Making Space for Water Programme was the publication of PPS25 in December 2006 This work together with the Practice Guide forms the Governments required approach to managing and reducing flood risk through the land use planning system A valuable piece of work lookin
114. ial Test is the key driver for the Level 1 SFRA In order to carry out the Sequential Test the LPA need to know e Spatial extent of flood risk within the whole LPA area o Flood Zones See Appendix E Flood Zone 1 Low Probability less than 1 in 1000 year fluvial flood event Flood Zone 2 Medium Probability between a 1 in 100 and 1 in 1000 year fluvial flood event Flood Zone 3a High Probability a 1 in 100 year or greater fluvial flood event Flood Zone 3b Functional Floodplain land where water has to flow or be stored in times of flood o Flooding from other sources e Location of proposed development sites and the proposed vulnerability of that development in flood risk terms See Appendix F There are a number of key challenges faced by the LPA in applying the Sequential Test in accordance with PPS25 and its Practice Guide The Sequential Test is purely based on the Flood Zones as defined by Table D1 of PPS25 but these zones only take account of fluvial and tidal flooding which ignore the presence of flood risk management measures such as defences Other sources of flooding must also be considered in the spatial distribution of development The PPS25 Practice Guide states that other forms of flooding should be treated consistently with river flooding in mapping probability and assessing vulnerability to apply the Sequential and Exception Tests p 83 However it can be problematic to map the spatial exten
115. id Hodcroft Bury MBC Pauline Goodhall and Georgina Brownridge Oldham Council Richard Duddell and Janet Brooks Rochdale Development Agency and Chris Waring and Andy Cameron Environment Agency JBA Consulting www jbaconsulting co uk iii Bury Rochdale and Oldham Councils be te Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide EXECUTIVE SUMMARY Introduction Bury Rochdale and Oldham BRO Councils are required to undertake a Strategic Flood Risk Assessment SFRA as an essential part of the pre production evidence gathering stage of the Local Development Framework LDF and in preparing their Local Development Documents LDDs The SFRA provides baseline information for use in the preparation of the Sustainability Appraisal SA of LDDs for the scoping and evaluation stages The requirement for and guidance on the preparation of SFRAs is outlined in Planning Policy Statement 25 Development and Flood Risk PPS25 and its Practice Guide This requires Local Planning Authorities LPAs to take a more dominant role in local flood risk management They also need to demonstrate that due regard has been given to the issue of flood risk at all levels of the planning process to avoid inappropriate development Local authority planners must demonstrate that a risk based sequential approach has been applied in preparing development plans and that flood risk has been considered during the planning application process
116. ide Figure A1 Flooding from all sources Climate change increase intensity f of storms Overland runoff and muddy flooding due to intense rainfall Groundwater flooding due to raised water table Reservoir or canal breach Surcharged sewer causes basement flooding Direct overland flow and ponding in low spots sinks Flooding through the alluvials Sewer exceedance flooding Urban creep increased paving Impervious paved area Blocked or sewer collapse Major causes of flooding include Fluvial Flooding Flooding from watercourses is associated with the exceedance of channel capacity during higher flows The process of flooding from watercourses depends on a number of catchment characteristics including geographical location variation in rainfall steepness of the channel and surrounding floodplain and infiltration and rate of runoff linked to land use i e degree of urbanisation It is possible to generalise catchments into large and relatively flat or small and steep the two giving very different responses during large rainfall events According to PPS25 in a large relatively flat catchment flood levels will rise slowly and natural floodplains may remain flooded for several days acting as the natural regulator of the flow In small steep catchments local intense rainfall can result in the rapid onset of deep and fast flowing f
117. ies JBA Consulting www jbaconsulting co uk Thought Process Decision An SFRA should have already provided the evidence base amp the LPA carried out the Sequential Test What Flood Zones are present within the site Has a similar site or wider community been assessed in the SFRA amp what was the outcome in the SFRA LDD compare proposed land use location size percentage cover at risk Is development practicable or is flood risk to great Are there any specific land use or mitigation requirements which make the proposal unviable Is the community part of a regeneration strategy If so the development may be required for long term aspirations If not alternative sites or land use must be considered What is the degree of risk associated with the site An FRA will be required for risk areas from all sources of flooding including Critical Drainage Areas Are there any known flooding related site constraints which make the development proposed unviable An FRA needs to be fit for purpose Is it possible to design a new development which is safe and which does not increase flood risk elsewhere Wherever possible it should try and reduce risk to the wider community Requirement of the Sequential Test Has reasoned justification been provided to the LPA wherever they need to apply the Exception Test Have all contentious issues been discussed and agreed with the LPA and flood risk consultees Environment Agency are a sta
118. if located in Flood Zone 3a and 3b Until the proposed changes have been agreed and PPS25 updated the current PPS25 2006 and its Practice Guide 2008 should be used for planning policy guidance but users should be aware of possible future changes PPS25 Development and Flood Risk Practice Guide The Practice Guide to PPS25 was initially published by the Department for Communities and Local Government CLG in June 2008 It provides advice on the practical implementation of PPS25 policy and reflects extensive discussion with local authorities the Environment Agency and other key stakeholders and practitioners The guide provides further guidance on the preparation of SFRA s and FRAs the Sequential and Exception Test and outlines potential mitigation measures e g SUDS and risk management techniques Local Authority planners and developers are advised to refer to and use PPS25 and the practice guide in conjunction with the further advice contained within this report December 2009 PPS25 Practice Guide Update In December 2009 CLG published an update to the PPS25 Practice Guide which replaces the version published in June 2008 It reflects the intention announced at the time of publication to keep the guide fresh and relevant through periodic updates The majority of the updates are relatively minor acknowledging material such as the Pitt Review and new flood risk information such as the Environment Agency national Areas Susceptible to Sur
119. imate Impacts Programme United Kingdom Climate Projections United Utilities xi Bury Rochdale and Oldham Councils be te Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide 1 INTRODUCTION 1 1 Background JBA Consulting was commissioned in March 2009 by Bury MBC Rochdale MBC and Oldham Council to undertake a Level 1 and Level 2 Strategic Flood Risk Assessment SFRA leading on from the Greater Manchester Sub Regional SFRA completed in August 2008 The Level 1 Volume II and Level 2 SFRA Volume III for Bury Rochdale and Oldham BRO has been prepared in accordance with current best practice Planning Policy Statement 25 Development and Flood Risk PPS25 and the PPS25 Practice Guide Flood Risk Assessment Flooding is a natural process and does not respect political demarcations or administrative boundaries it is influenced principally by natural elements of rainfall tides geology topography rivers and streams and man made interventions such as flood defences roads buildings sewers and other infrastructure As was seen in the summer 2007 floods flooding can cause massive disruption to communities damage to property and possessions and even loss of life Flood risk concepts are explored further in Appendix A The risk of flooding from rivers surface water sewers groundwater canals and reservoirs has been explored for Bury Rochdale and Oldham as part of this SFRA For this reason it is
120. imate change 5 and urban growth may increase flood risk Economic damages are high Bury Current level of risk is thought to be low Significant urban development 4 potentially at risk if flood risk management activity is reduced Ramsbottom Recently completed flood defence scheme provides 1 standard of 4 protection and this level is through to be appropriate High economic damages if flooding occurs Rural Current level of flood risk is thought to be low Attenuation here could 6 Rossendale reduce flood risk downstream Whitefield Flood risk is thought to be above the indicative standards Levels of 3 flood risk do not increase significantly under the modelled future changes to the catchment Flood risk management activities are still required to maintain culvert capacities Rochdale Recent flood defence scheme provides 1 in 100 year standard of 4 Whitworth protection and this level is thought to be appropriate High economic and damages if flooding occurs Littleborough Milnrow and Current levels of risk are thought to be high Economic appraisal 5 Shaw suggests potential benefits from flood risk management works Rural Roch Current level of risk in rural areas is low Attenuation of flood waters 6 could reduce flood risk downstream in Whitworth Milnrow and Shaw Heywood Flood risk is thought to be above the indicative standards Levels of 3 flood risk do not increase significantly under the modelled future JBA Cons
121. important to avoid developing in flood risk areas in the first instance Where this is not possible development should be directed to areas with the lowest possible level of flood risk Having exhausted all opportunities to direct development away from areas of flood risk then the allocation of land for development must consider the vulnerability of the proposed land use to flooding and take measures to minimise flood risk to people property and the environment This is the thrust of the risk based sequential approach to managing flood risk and it is the backbone of PPS25 Current Government policy requires local authorities to demonstrate that due regard has been given to the issue of flood risk as part of the planning process It also requires that flood risk is managed in an effective and sustainable manner and where new development is as an exception necessary in flood risk areas the policy aim is to make it safe without increasing flood risk elsewhere and wherever possible reduce flood risk overall The SFRA fits into a hierarchy of Flood Risk Assessments each at an increasing level of detail that are designed to inform different stages of the planning system from Regional Spatial Strategies to site specific Planning Applications More background on this is provided in Appendix B The Planning Framework The land use planning process is driven by a whole host of policy guidance on a national regional and local level Whilst the majority of th
122. inage system is essential Critical Drainage Areas Certain locations are particularly sensitive to an increase in the rate of surface water runoff and or volume from new development There are generally known local flooding problems associated with these areas These areas have been defined as Critical Drainage Areas CDAs in the SFRA Specific drainage requirements are required in these areas to help reduce local flood risk The SFRA has designated CDAs as high flood risk areas These are areas with complex surface water flooding problems that would benefit from a drainage strategy which is most effectively done in a Surface Water Management Plan United Utilities sewer records were not made available for this study and it should be noted that there are likely to be additional areas that contribute flows through the sewer system into CDAs The CDAs provided in the SFRA should be refined over time as more detailed information on flood risk and local flood management assets including sewered catchments becomes available In these areas a detailed FRA is required regardless of which Flood Zone that applies for all developments over 0 5 hectares This should demonstrate that new development is not at risk from flooding from existing drainage systems or potential overland flow routes It should also demonstrate that the development will not adversely affect existing flooding conditions by the use of JBA Consulting www jbaconsulting co uk 34
123. isk of flooding from groundwater rebound or in the floodplain of watercourses where there might be alluvial groundwater flooding Surface Water This is discussed in section 4 6 Sewers Where the SFRA has identified risk from surface water flooding any water that surcharges the sewer system would be expected to follow similar flow paths and pond in similar low spots However the volume of water that emerges from the system will be entirely dependent on the reason for the network surcharging which could be due to rainfall beyond the design level of the sewer system sewer capacity issues or blockage or failure Developers should take account of the guidance in section 4 6 where appropriate and liaise closely with United Utilities over any localised sewer flooding problems that could affect the site Any known sewer flooding locations are prioritised for investment by United Utilities and may be the subject of future investment by the water company Future development should be designed so that it does not contribute to existing sewer flooding problems JBA Consulting www jbaconsulting co uk 32 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 4 6 4 6 1 Drainage for New Developments Development has the potential to cause an increase in impermeable area an associated increase in surface water runoff rates and volumes and a consequent potential increase in downstream flood
124. kelihood of flooding and the potential consequences arising Likelihood Likelihood of flooding is normally expressed as the percentage probability based on the average frequency measured or extrapolated from records over a large number of years A 1 probability indicates the flood level that is expected to be exceeded on average once in 100 years i e it has a 1 in 100 chance of occurring in any one year Considered over the lifetime of development such an apparently low frequency or rare flood has a significant probability of occurring For example a 1 flood has a 22 1 in 5 chance of occurring at least once in a 25 year period the period of a typical residential mortgage and a 53 1 in 2 chance of occurring in a 75 year period a typical human lifetime Consequence The consequences of flooding depend on the hazards caused by flooding depth of water speed of flow rate of onset duration wave action effects water quality and the vulnerability of receptors type of development nature e g age structure of the population presence and reliability of mitigation measures etc Flood risk Flood risk is normally expressed as Flood risk Probability of flooding x Consequences of flooding Flooding Impacts on People Property and the Environment Flood impacts maybe direct or indirect immediate or long term and may affect households and communities individuals as well as the environment infrastructure and economy of an are
125. l Reservoirs El WC HV MV and LV Flood risk from reservoirs is residual Although this will not directly impact on the spatial planning of development it should influence site emergency planning Smaller reservoirs could potentially pose the greatest risk The risk of flooding should be assessed as part of the FRA Smaller reservoirs should be assessed to identify the risk and appropriate mitigation put in place 1El Essential Infrastructure WC Water Compatible HV Highly Vulnerable MV More Vulnerable LV Less Vulnerable Check with Table D 3 of PPS25 to see if Exception Test is required JBA Consulting www jbaconsulting co uk 42 2009s0042 Volume I SFRA User Guide Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment J a 6 6 1 6 2 GUIDANCE FOR EMERGENCY PLANNERS The aim of this section is to provide guidance on the use of the SFRA by Emergency Planners Developers should also refer to the guidance on SFRA maps provided on page vi and background to the SFRA and flood risk concepts in Appendix A and C Emergency Planners should use the guidance in this SFRA User Guide PPS25 and its Practice Guide to e Update Multi agency Flood Plans o Using the overall assessment of flood risk provided in the Level 1 SFRA o Using the assessment of residual risk in the Level 2 SFRA e Provide advice on developer Flood Plans for new development o Using out
126. l approach to site layout Raising floor Maps 3 1 to 3 16 depths Dangerous LV remain safe up to the 1 in 100 climate levels may be a possibility for some and or change event however residual risks Additional measures can be put in place to reduce Dangerous for all must be considered if the development damage to existing properties and increase the is situated behind defences speed of recovery i e temporary and permanent barriers and wet proofing These measures should not be relied on as the only mitigation method Emergency planning must be considered and safe access and egress routes should be identified Flood Zone 3 0 3 El WC MV and Sustainable mitigation and flood risk Sequential approach to site layout Raising floor 1m depths and or LV management may be feasible for both levels is acceptable and they should be raised to Dangerous for housing and employment purposes 600mm above the maximum water level during a 1 in some There is a greater likelihood of passing 100 year flood event plus climate change the Exception Test Areas may still have Compensatory flood storage must be provided and residual risks should be on a level for level volume for volume basis Emergency planning must be considered and safe access and egress routes should be identified Flood Zone 3 1 El WC and LV Mitigation is likely to be costly and may Floor level raising for employment purposes is 1 5m depths and or Dangerous for m
127. l be exceeded Hence there is a need to design for exceedance This should be considered alongside any surface water flows likely to enter a development site from the surrounding area Master planning should ensure that existing overland flow paths are retained within the development As a minimum the developer should investigate as part of a FRA the likely depths and extents of surface water flooding on a development site when the national Areas Susceptible to Surface Water Flooding map and or the surface water mapping produced for the Level 2 SFRA indicate that there is a risk of surface water flooding This is a precautionary but an appropriate approach to reduce the risk of flooding to new developments Green infrastructure should be used wherever possible to accommodate such flow paths Floor levels should always be set a minimum of 300mm above adjacent roads to reduce the consequences of any localised flooding The effectiveness of a flow management scheme within a single site is heavily limited by site constraints including but not limited to topography geology soil permeability development density existing drainage networks within the site and surrounding area adoption issues and available area The design construction and ongoing maintenance regime of such a scheme must be carefully defined at an early stage and a clear and comprehensive understanding of the catchment hydrological processes i e nature and capacity of the existing dra
128. lanning purposes 2 Undertake District flood risk assessments that will supplement current policy guidelines i e PPS25 and provide a risk based approach to policy making and development control within Greater Manchester This was intended to provide clarity and inform both local authority officers and developers ensuring that where flood risk is identified as a relevant issue that must be addressed as part of the application process the degree of mitigation required is appropriate to the scale of development and or risk faced The Greater Manchester sub regional SFRA is an excellent example of a high level document which introduced the concept of flood risk to all Greater Manchester authorities and the hydrological connectivity that links each council together By carrying out such a strategic document it has allowed a partnership and familiarity to be created between the local authorities and key stakeholders in flood risk issues and the need for a greater understanding and single belief in flood risk management The Greater Manchester sub regional SFRA has also benefitted future work such as the Level 1 and Level 2 SFRA for Bury Rochdale and Oldham By carrying out the majority of the ground work it has allowed a Level 2 assessment to be more focused on the areas at greater risk and where greater detail of residual risks is needed It has also reviewed the majority of flood risk information available from a variety of key stakeholders
129. le communities Long term impacts can arise due to chronic illnesses and stress Flood water contaminated by sewage or other pollutants e g chemicals stored in garages or commercial properties is particularly likely to cause such illnesses either directly as a result of contact with the polluted flood water or indirectly as a result of sediments left behind The degree to which populations are at risk from flooding is therefore not solely dependent upon proximity to the source of the threat or the physical nature of the flooding Social factors also play a significant role in determining risk Although people may experience the same flood in the same area at the same time their levels of suffering are likely to differ greatly as a result of basic social differences These differences will affect vulnerability in a variety of ways including and individuals or community s response to risk communication flood warning and physical and psychological recovery in the aftermath of a flood How individuals and communities experience the impact will also vary depending on their awareness of the risk of flooding preparedness for the flood event and the existence or lack of coping strategies Flooding Impacts on Property Flooding can cause severe property damage Flood water is likely to damage internal finishes contents electrical and other services and possibly cause structural damage The physical effects can have significant long term impacts wit
130. lised flooding site specific considerations and the surface water proposals for the development including mitigation However due to their potential impact on the local flood risk a full Flood Risk Assessment will be required for all developments greater than tha in size This will include further consideration of surface water drainage and onsite mitigation measures that may be required particularly where the capacity of the surface water sewer or receiving watercourse is limited This assessment will be undertaken by the developer of the site and should be appropriate to the scale nature and location of the development The Council s Drainage Engineers and the Environment Agency will be able to advise potential developers as to their specific requirements on a site by site basis Flood Zone 2 Medium Probability Subject to the application of the Sequential Flood Risk Test PPS25 specifies suitable types of development in Flood Zone 2 as e Essential infrastructure e More vulnerable e Less vulnerable e Water compatible development Highly vulnerable uses should only be permitted in this zone if the Exception Test is passed The SFRA is unable to assess whether the site will pass parts a and b of the Exception Test However the council must be able to demonstrate the need for development through the spatial planning process A Flood Risk Assessment will be required for all development in this zone The Flood Risk Assessment will
131. ll Animations have been produced for the 1 in 100 year and 1 in 1000 year fluvial events These can be used to identify rapid inundation zones the development of flow paths and indicative inundation timing These are provided in the SFRA digital deliverables As the outputs have been produced using a 2D model to represent the floodplain the outputs will also identify critical flood paths along roads and around buildings once flood water enters the urban environment These maps should be used during the Sequential Test and provide the evidence to inform the likelihood of sites passing the Exception Test Sites situated in communities with high depths and or hazards should be avoided and would find it difficult the pass the Exception Test Emergency planners may also find this useful in designating access and egress routes Breach Depths Volume Ill Map 4 1 and 4 3 Volume Ill section 3 0 Breach Hazards Volume lil Map 4 2 and 4 4 Volume Ill section 3 0 Following the production of an asset survey a breach assessment was investigated at the upstream extent of the Esplanade Culvert Rochdale town centre on the right hand bank during the 1 in 100 year event The effect of climate change has also been investigated Both depths and hazards have been mapped Currently the defence along this reach is in poor condition and consists of an earth embankment JBA Consulting www jbaconsulting co uk vii Bury Rochdale and Oldham Councils be i Strategic Floo
132. looding with little warning Such flash flooding which may only last a few hours can cause considerable damage and possible threat to life The form of the floodplain either natural or urbanised can influence flooding from watercourses The location of buildings and roads can significantly influence flood depths and velocities by altering flow directions and reducing the volume of storage within the floodplain Critical structures such as bridge and culverts can also significantly reduce capacity creating pinch points within the floodplain These structures are also vulnerable to blockage by natural debris within the channel or by fly tipping and waste Surface Water Flooding Flooding of land from surface water runoff is usually caused by intense rainfall that may only last a few hours and follows natural valley lines creating flow paths along roads and through and around developments and ponding in low spots which often coincide with fluvial floodplains in low lying areas Hence any area at risk of fluvial flooding will almost certainly be at risk of surface water flooding Flooding in urban areas can also be attributed to sewers Sewers are normally designed to a maximum of a 1 in 30 year design standard and hence sewer flooding problems will often be associated with more frequent storm events when sewers can become blocked or fail In the larger events that are less frequent but have a higher consequence surface water will exceed
133. ls be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide waterways and improve water quality supporting regeneration and improving opportunity for leisure economic activity and biodiversity The Greater Manchester Green Infrastructure Study was published in September 2008 by TEP for AGMA and Natural England on the feasibility of a GI framework for Greater Manchester Figure 2 6 is an extract of the Summary Report illustrating the broad GI network in Greater Manchester GI should be incorporated into master planning and individual sites directed by the need to retain exceedance flood paths and natural attenuation of flood flows The evidence provided in the BRO Level 1 and Level 2 SFRA should be used to enhance the Greater Manchester Green Infrastructure Study by identifying opportunities for delivering FRM measures through GI River corridors identified as functional floodplain are an excellent linkage of GI and can provide storage during a flood event Areas identified within the urban environment or upstream of a critical surface water flood areas should be incorporated into council GI strategies Opening up land to create flow paths or flood storage areas can help protect current and future developments JBA Consulting www jbaconsulting co uk 15 Bury Rochdale and Oldham Councils P Strategic Flood Risk Assessment ba 2009s0042 Volume I SFRA User Guide CONSULTING Figure 2 6 Green Infrastructu
134. lting www jbaconsulting co uk 25 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 4 4 FRA Guidance Flood Risk Assessments should follow the approach recommended by 1 2 3 These The Environment Agency Standing Advice this can be found at the website below http www environment agency gov uk research planning 82584 aspx CIRIA Report C624 Development and Flood Risk Guidance for the Construction Industry PPS25 and its Practice Guide documents describe when a FRA is required and what it should contain They guide developers to produce a fit for purpose FRA The key requirements of a FRA are provided in section 3 of the PPS25 Practice Guide The FRA should 1 JBA Consulting answer the following questions Development Description and Locations o What is the type of development and where will it be located o What is the vulnerability classification of the current and future use of the development site using Table D 2 of PPS25 o Has the development site been assessed during the Level 1 and Level 2 SFRA and is in line with LDDs If so the Sequential and Exception Test may have already been applied See guidance in section 4 2 Definition of Flood Hazard o What sources of flooding could affect the site See Volume II and IIl Mapping o For each source how would flooding occur referencing any historical records where these are available
135. lting co uk 20 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 4 GUIDANCE FOR DEVELOPERS 4 1 Introduction Flood risk should first be considered from a strategic view point even though applications for proposed developments are submitted at a site level The SFRA provides the evidence base for developers to assess the flood risk to a site at a strategic level and scope an appropriate site specific Flood Risk Assessment Developers should liaise closely with the LPA during the pre application stage of development to determine if a site is suitable and if so what type of development is appropriate given the application of the Sequential Test and likelihood of passing the Exception Test as required by PPS25 If a site is suitable then developers should prepare a site specific Flood Risk Assessment in close liaison with the LPA and Environment Agency JBA Consulting www jbaconsulting co uk 21 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 4 2 Developers should consider all sources of flood risk when assessing whether a site is suitable for development Guidance on developing in Critical Drainage Areas and areas at risk from sources other than fluvial is provided in this section Figure 3 1 in the Guidance for Development Management section 3 provides a useful overview of the consideration of flood risk within the c
136. ly also for areas that are designed to flood being wrongly excluded from identified functional floodplain JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide There are four amendments proposed in Table D 2 including 1 Moving water treatment and sewage treatment works from less vulnerable to essential infrastructure This means they will now need to pass the Exception Test if planned in Flood Zone 3a rather than just Flood Zone 3b As usual they will have to be designed to the appropriate uses and policy aims within Table D 1 2 Allowing police ambulance and fire stations to be defined as less vulnerable only if they are not required to be operational during flooding This will stop the exclusion of new emergency services facilities from communities they service in high flood risk areas 3 To allow facilities requiring hazardous substances consent which are required to be located in flood risk areas due to their need to be co located with other facilities i e the need to be located near ports or processed or manufactured facilities to be defined as essential infrastructure rather than highly vulnerable 4 Adding wind turbines to the essential infrastructure category However in keeping with PPS25 the Sequential Test is not required but Parts A and C of the Exception Test would need to be passed
137. material consideration in land use planning decision making and can greatly impact on the sustainability of various land uses in all locations Having applied the Sequential Test and Exception Test where necessary the resultant assessment of appropriateness and associated flood risk information will then influence the land use planning decision at whatever level it is being considered Land use policies and wider strategic decisions involving social and economic development in the LDDs will be influenced and shaped by the sequential approach informed by this SFRA For instance the Green Infrastructure Gl of Bury Rochdale and Oldham is part of the council area s life support system It is a planned and managed network of natural environmental components and green spaces that intersperse and connect the urban centres suburbs and rural fringe consisting of e Open Spaces parks woodlands nature reserves lakes e Linkages River corridors and canals pathways and cycle routes and greenways e Networks of urban green private gardens street trees verges and green roofs With regards to flood risk green spaces can be used to manage storm flows and free up water storage capacity in existing infrastructure to reduce risk of damage to urban property particularly in town centres and vulnerable urban regeneration areas Gl can also improve accessibility to JBA Consulting www jbaconsulting co uk 14 Bury Rochdale and Oldham Counci
138. ment s Future Water strategy document In addition the draft Bill responds to a number of climate change challenges including more frequent extreme weather events causing a greater risk of flooding and drought increased population increased water demand and more water quality problems It provides the Environment Agency with a strategic overview role for all sources of flood risk in England and Wales and gives local authorities in England a clear leadership role in local flood risk management An improved integrated and risk based approach is proposed for the future management of flood risk and this requires other concerns such as sustainability biodiversity and the whole water cycle to be taken into account by local authorities and other relevant organisations A core policy thread running through all current policy drivers is the fundamental shift in emphasis from building defences to prevent flooding to one of managing flood risk by using a suite of measures All operating authorities are required to invest in the provision of sustainable flood risk management and this includes LPAs adopting a flood risk management hierarchy of assessing avoiding substituting controlling and mitigating flood risk through the land use planning system They should have regard to flooding from all sources particularly surface water and not just from rivers and the sea Government does however recognise that in some circumstances appropriate mitigation measur
139. n A charge is likely to apply for the use of this data JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils a e e Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide CONSULTING JBA Consulting www jbaconsulting co uk 2009s0042 Volume I SFRA User Guide a Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment J a Please note that proposed changes have been made to this table Table D 1 mainly the definition of the functional floodplain in the upcoming revision of PPS25 This is expected around spring 2010 See Section C 1 3 for further information Definition This zone comprises land assessed as having a less than 1 in 1000 annual probability of river and sea flooding in any year lt 0 1 Appropriate uses All uses of land are appropriate in this zone FRA requirements For development proposals on sites comprising one hectare or above the vulnerability to flooding from other sources as well as from river and sea flooding and the potential to increase flood risk elsewhere through the addition of hard surfaces and the effect of the new development on surface water run off should be incorporated in an FRA Flood Risk Assessment This need only be brief unless the factors above or other local considerations require particular attention See Annex E of PPS25 for minimum requirements Policy aims In this zone developers and local authoritie
140. n excellent source of information It should however be used as a very high level piece of information at the beginning of any discussions regarding the use of SUDS within a community It does not preclude the need for site specific investigations on the suitability of SUDS within a development site JBA Consulting www jbaconsulting co uk
141. nd C When it comes to individual planning applications Planners should use the guidance in this SFRA User Guide PPS25 and its Practice Guide to e Check whether the Sequential Test and or the Exception Test have already been applied o Refer developer to LDD and supporting evidence to identify if the Sequential Test has been applied and development is likely to pass the Exception Test site may have already been assessed o If evidence is available the Sequential Test and likelihood of passing the Exception Test have been assessed If no evidence is available developers must carry out the Sequential and Exception Tests move on to the next stage e Refer developer to the following in order for them to apply the Sequential and Exception Tests o BROSFRA Volume II to inform Sequential Test o Sequential Test Spreadsheet to compare similar sites assessed o BRO SFRA Volume III to inform Exception Test o BRO SFRA Volume II maps to review scale and nature of flood risk o BRO SFRA Volume III maps to identify residual risks o Volume III Chapter 8 to assess likelihood of passing the Exception Test within a reviewed community e Consult with Environment Agency and other relevant stakeholders to o Assess flood risk constraints identified on site using the BRO SFRA e Scope an appropriate FRA o What is the scale and nature of risk from all sources o Does the site lie within a CDA identified in Volume III section 5 o Are there any strate
142. nd in broad terms what measures are planned to meet these objectives Act as the main reporting mechanism to the European Commission According to the draft plan it focuses on achieving the protection improvement and sustainable use of the water environment surface freshwaters including lakes streams and rivers groundwater and ecosystems such as some wetlands that depend on groundwater estuaries and coastal waters out to one nautical mile The main actions proposed in Annex C relevant to this SFRA include Climate Change Action Plan for the North West A commitment to deliver Catchment Flood Management Plans CFMPs to identify and agree policies for sustainable flood risk management for the next 100 years By employing sympathetic flood risk management such as that done at Long Preston Deeps in the Ribble catchment opportunities to enhance sites either designated for their conservation status or to help restore more natural flows to river systems can be created Working closely with partners to deliver Shoreline Management Plans SMPs to manage the current and future flood risk to the North West coast lines Our inputs to the Regional Spatial Strategy and the Local Development Framework will ensure that Water Cycle strategies are incorporated in major planning initiatives We shall continue to influence planners and developers to incorporate sustainable water use in construction maintenance projects and also follow t
143. ndertaken for the SFRA is of a strategic nature and more detailed FRAs should seek to refine the understanding of flood risk from all sources to any particular site SFRA data should not be passed on to third parties outside of the LPA Any third party wishing to use existing Environment Agency flood risk datasets should contact External Relations in the Environment Agency North West Region A charge is likely to apply for the use of this data JBA Consulting www jbaconsulting co uk viii Bury Rochdale and Oldham Councils be te Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide CONTENTS Page REVISION HISTORY ii CONTRACT ii PURPOSE iii ACKNOWLEDGEMENTS iii EXECUTIVE SUMMARY iv CONTENTS ix 1 INTRODUCTION 2 2 2 n nnn n nnn nnn ners nnne 1 ied em Background esantion anana aa reer creer errr a Aa recep recey correc re EEEa 1 1 2 Development of the SFRA 0 c ccccceeeseeceeeeceeeeeeeaeeeeneeeeeeeeeeaeeeeaaeseaeeesaeeeeaaeseeaeeeeeaeeseaaeseeaeeseaneess 2 1 3 SFRA Monitoring and ReView c ccccccceeseceeeeeeeeeeeeeeeceeeeeeaaeeeeaaeseceeeseaeeeeaaeedeaeeesnaeeesaesseaeeseeeeess 4 2 GUIDANCE FOR SPATIAL PLANNERS 0 5 2 WATROGUGUON spirene a tian ives e aa aa Raa test a Ra AAE R AEA aE aaa 6 22 Se ential TESt aiiiar a a a a AA a Aao a tas aa AA OEE NEEE 8 2 3 EXCEDtION TSE assstoredriedrei aa a a a a
144. need to assess the current level of flood risk as well as the level of flood risk JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide following development Development plans for the site will need to demonstrate that flood risk can be effectively and safely managed without increasing flood risk elsewhere Proposals will also need to demonstrate that access and egress to the development can be maintained during an extreme flood event and that development is set at an appropriate level A further level of analysis may be required where development is planned behind or adjacent to existing defences in order to test the sustainability and robustness of the mitigation measures In keeping with Flood Zone 1 other flood risk constraints such as incidents of localised flooding and other site specific considerations will need to be addressed Again detailed FRAs will be undertaken by the developer of the site and the Environment Agency will be able to advise potential developers as to their specific requirements on a site by site basis The Flood Risk Assessment will need to address part c of the Exception Test and should only be commenced when the planning justification is clearly established Flood Zone 3 High Probability A Sequential Flood Risk Test is used to prioritise sites in order of vulnerability to flood risk and their acceptability for d
145. ng process and therefore an understanding of the constraints faced as a result of this additional policy guidance is required Regional Policy Drivers Regional Spatial Strategy The Regional Planning Guidance for the North West RPG13 was published in March 2003 In September 2004 following the implementation of the Planning and Compulsory Purchase Act 2004 the Regional Planning Guidance was converted to the Regional Spatial Strategy RSS in line with Governmental reforms Regional Planning Bodies have the main responsibility for preparing Regional Spatial Strategies RSS In the North West this is the North West Regional Assembly NWRA NWRA launched a Full Review in July 2004 and following informal consultations at issues options and Interim Draft stages submitted the Draft RSS to the Secretary of State on 30th January 2006 The Draft Submitted RSS for North West England also known as The North West Plan was published for public consultation on 20 March 2006 The final RSS was published in September 2008 and now outlines the current adopted planning strategy for the period to 2021 JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be i Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide The RSS sets out housing targets for each local authority under policy L4 which are shown in Table C1 The housing provision targets take account of RSS and Regional Housing Strateg
146. ning They have also been a key driver in shaping the content of the draft Flood and Water Management Bill National Planning Policy This SFRA has been prepared in a period during which planning authorities have been implementing the provisions of the Planning and Compulsory Purchase Act 2004 and accompanying planning guidance including PPS1 Delivering Sustainable Development and PPS12 Local Development Frameworks This affected all tiers of the planning system and has necessitated major changes at both the regional and local level which will impact on the way in which planned development is approached in the regional strategy and delivered locally PPS25 Development and Flood Risk In December 2006 the Government published PPS25 Development and Flood Risk The aim of PPS25 is to ensure that flood risk is taken into account at all stages in the planning process to avoid inappropriate development in areas at risk of flooding and to direct development away from areas at highest risk The key planning objectives are that Regional Planning Bodies RPBs and Local Planning Authorities LPAs should prepare and implement planning strategies that help to deliver sustainable development by e Identifying land at risk and the degree of risk of flooding from river sea and other sources in their areas Fenning bey tempt JS e Preparing Regional or Strategic Flood Risk Assessments RFRAs SFRAs as appropriate as a freestanding assessment
147. no strategic planning objectives identified in Core Strategy Step 7 Identify those sites in which the consequence of flooding can be reduced through substitution within the site boundary Step 8 Assess yield and layout issues for remaining high risk sites to check whether development is viable Identify the Likelihood of passing the Exception Test Follow Key Questions imbedded within Figure 2 5 and SFRA evidence to identify the likelihood of those sites remaining at risk passing the Exception Test The community risk review tables produced in Volume III section 8 can aid this process Step 9 Assess the compatibility of the development vulnerability using Table D 2 of PPS25 and identify the requirement of passing the Exception Test using Table D 3 of PPS25 Step 10 Use the SA to assess alternative development options by balancing flood risk against other planning constraints Proposed sites should be avoided and removed if it is unlikely to pass the Exception Test i e if e Key Questions in Figure 2 5 attributes a significant negative response e Where development will require significant mitigation measures to make the site safe and to reduce impacts downstream Where the requirement of loss of floodplain compensation cannot be delivered JBA Consulting www jbaconsulting co uk 12 Bury Rochdale and Oldham Councils be te Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide Figure 2 4 1 and 2 pass of prop
148. noted that the emergency services are unlikely to regard developments that increase the scale of any rescue that might be required as being safe Flood Warning and Evacuation Emergency evacuation plans should be in place for all properties large and small at residual risk of flooding those developments which house vulnerable people i e care homes and schools will require more detailed plans More information on flood plans for development is provided in section 6 of this User Guide Making Space for Water Opportunities for River Restoration and Enhancement All new development close to rivers should consider the opportunity presented to improve and enhance the river environment Developments should look at opportunities for river restoration and enhancement as part of the development Options include backwater creation de silting in channel habitat enhancement and removal of structures When designed properly such measures can have benefits such as reducing the costs of maintaining hard engineering structures reducing flood risk improving water quality and increasing biodiversity Social benefits are also gained by increasing green space and access to the river Opportunities for Floodplain Restoration It is an objective of PPS25 to safeguard land from development that may be required for current or future flood management In areas of very high flood risk there may be a strong case for allowing previously developed sites to return t
149. nsulting www jbaconsulting co uk 10 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment ae 2009s0042 Volume SFRA User Guide CONSULTING Figure 2 3 Sequential and Exception Tests flow diagram INPUT OUTPUT i Development Options Sequential Test Core Strate H ne 9y i Considering other planning objectives can l Sequential Tested T i development be located entirely within areas of low Development Options within oy Level 1 SFRA i probability of flooding Sustainability Appraisal oO Flood Zone Maps 1st Pass of Proposed Development Sites Sequential Test Propose Development ste i Spatial assessment of proposed development sites Sequential Test Screening o g Level 1 SFRA N and flood risk i Spreadsheet Flood Zone Maps l H 8 a Gan Test Screening Spreadsheet di f Spatial assessment of proposed development sites Avoidance of Development in i and flood risk High Risk Areas Sequential Tested i Development Options i 2nd Pass of Proposed Development Sites Sequential Test i Flood Zone Map D Cana j ppropriate development be located within lower P i H areas within the development sites at risk if not a ce 2 z Climate Change Sensitivity could it be locate
150. nt Plans Water Company Asset Management Plans Catchment Flood Management Plans and the Regional Flood Risk Appraisal Local planning authorities and developers should protect the quantity and quality of surface ground and coastal waters and manage flood risk by e Working with the Water Companies and the Environment Agency when planning the location and phasing of development Development should be located where there is spare capacity in the existing water supply and waste water treatment sewer and strategic surface water mains capacity insofar as this would be consistent with other planning objectives Where this is not possible development must be phased so that new infrastructure capacity can be provided without environmental harm e Producing sub regional or district level strategic flood risk assessments guided by the Regional Flood Risk Appraisal Allocations of land for development should comply with the sequential test in PPS25 Departures from this should only be proposed in exceptional cases where suitable land at lower risk of flooding is not available and the benefits of development outweigh the risks from flooding e Designing appropriate mitigation measures into the scheme for any development which exceptionally must take place in current or future flood risk areas to ensure it is protected to appropriate standards provides suitable emergency access under flood conditions and does not increase the risk of flooding elsewher
151. o Functional Floodplain in urban areas where they can act to convey and store flood water and reduce risk to current development Buffer Strips Developers should set back development from the landward toe of fluvial defences or top of bank where defences do not exist and this distance should be agreed with the Environment Agency This provides a buffer strip to make space for water allow additional capacity to accommodate climate change and ensure access to defences is maintained for maintenance purposes JBA Consulting www jbaconsulting co uk 40 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 200985002 Volume I SFRA User Guide Table 5 1 Possible mitigation measures jba Flood Appropriate Source SFRA Data Source Risk Zone Development Comments Possible Mitigation Fluvial BRO SFRA Volume Flood Zone 1 El WC HV MV All development is viable within Flood None required for fluvial but may be for other Depths ll and LV Zone 1 however other sources of sources Refer specifically to CDAs and Map 1 2 A to Q flooding should be investigated Hazards Map 1 6 A to O Flood Zone 2 El WC HV MV Low depth and hazards can be Sequential approach to site layout lt 0 3m depths and LV manageable with minor mitigation BRO SFRA Volume and or Very Low required Iii Hazard Maps 2 1 to 2 16 Flood Zone 2 gt 0 3 El WC MV and All development must be designed to Sequentia
152. of climate change e Assessing flood risk from other sources including surface water groundwater sewers reservoirs and canals e Assessing potential development sites e Producing a range of strategic flood risk maps e SFRA recommendations Volume III BRO Level 2 SFRA The BRO SFRA Volume III provides evidence on a key community basis where the Exception Test may need to be applied It considers the detailed nature of flood hazard taking account of the presence of flood risk management measures such as flood defences The additional detail can also inform a sequential approach to development allocation within flood risk areas and mitigation options where appropriate The study area focuses on Bury Rochdale and the Beal catchment within Oldham and key urban areas including Ramsbottom Bury Radcliffe Littleborough Rochdale and Shaw The risk of fluvial flooding to development sites in Oldham Council was not considered to be high and there was also no planned development identified behind flood defences A detailed Level 2 assessment was therefore not undertaken for all sources of flood risk in Oldham The main tasks for the BRO SFRA Volume III included e Defence Asset Survey carrying out a defence asset investigation in key areas of Bury and Rochdale photographs were taken and visual inspection of the defence assets condition and supplementary comments were made The outputs from this survey were used to focus the more detailed in
153. of the development o Developers should refer to section 6 of this Volume for guidance on developing an emergency Flood Plan for a development site www jbaconsulting co uk 26 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 4 5 4 5 1 Considering Other Sources of Flooding Flood Risk Assessments must take account of flood risk from all sources rather than concentrating on fluvial tidal or surface water flood risk The BRO SFRA Volume II has gone some way in identified the presence of these sources whilst the BRO SFRA Volume III has provided a more detailed analysis of the actual and residual risk associated with them where practicable Canals Developers should be aware that any site that is at or below the top of a canal bank level may potentially be subject to canal flooding The possible flood mechanisms include e Canal bank overtopping e Canal embankment breach Severe cases of canal bank overtopping may lead to breach failure depending on the geometry and characteristics of the canal at that location Flood volumes and flood risk caused by canal bank overtopping are usually much lower than those arising from a breach of a canal embankment This is since canals are usually maintained so that they have additional capacity to deal with storm runoff When overtopping occurs this will be limited to the additional volume of water entering the canal that causes the canal wat
154. ontext of an individual site planning application The Sequential Test and Exception Test The Sequential Test and Exception Test are fundamental to PPS25 in determining the suitability of land for development in regard to flood risk and avoidance of flood risk to new development These tests may still be required at an individual site level Table 4 1 identifies when the Sequential and Exception Tests are required for certain types of development and who is responsible for providing the evidence and those who need to apply the tests Further information is provided in section 4 of the PPS25 Practice Guide If the Developer is required to provide evidence that the site can pass the Sequential Test and or Exception Test if appropriate then further guidance on these can be found in section 2 of this User Guide Table 4 1 Development types and application of Sequential and Exception Tests Development Sequential Test Exception Test esate Required ano APEE ure Required Who Applies the Test LPA should have Dependent LPA to advise on the already carried on land use likelihood of passing test Allocated Sites out the test during vulnerability But the developer must the allocation of Appendix F provide evidence that the se Lo development sites Test can be passed by within their LDD providing planning justification and producing a detailed FRA Developer Dependent Developer must provide provides evidence on land use
155. ood storage Zone 3b The Functional Floodplain Definition This zone comprises land where water has to flow or be stored in times of flood SFRAs should identify this Flood Zone land which would flood with an annual probability of 1 in 20 5 or greater in any year or is designed to flood in an extreme 0 1 flood or at another probability to be agreed between the LPA and the Environment Agency including water conveyance routes Appropriate uses Only the water compatible uses and the essential infrastructure listed in Table D 2 that has to be there should be permitted in this zone It should be designate and constructed to Remain operational and safe for users in times of flood Result in no net loss of floodplain storage Not impede water flows and Not increase flood risk elsewhere Essential infrastructure in this zone should pass the Exception test FRA requirements All development proposed in this zone should be accompanied by a FRA See Annex E for minimum requirements Policy Aims In this zone developers and local authorities should seek opportunities to i Reduce the overall level of flood risk in the area through the layout and form of the development and the appropriate application of sustainable drainage techniques and ii Relocate existing development to land with a lower probability of flooding JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils P e
156. or Strategic Flood Risk Assessment further work in local authority SFRAs including filling in data for Greater Manchester gaps such as surface water flooding ne Loving Document August 2008 Ep Paermante Local Planning Policy Scot ad V Fg Py Hes By we Following the introduction of the Planning and Compulsory Purchase Act 2004 the way in which development plans are prepared is changing With the aim of speeding up and simplifying plan preparation and improving community involvement development plans in their current form are to be abolished and replaced with a new development plan system the Local Development Framework LDF The Emerging Local Development Framework The UDP is currently in the process of being replaced by the Local Development Framework LDF The LDF will take the form of a portfolio of plans and documents made up of several Local Development Documents LDDs Some of them will have statutory status Development Plan Documents DPDs and others will be adopted as local guidance documents LDDs can either deal with different issues or different geographical areas but when taken together they will set out the Council s policies for how it will assess development proposals and direct future growth The LDF includes a Statement of Community Involvement SCI that describes how the local planning authority intends to carry out its public consultation arrangements Bury Rochdale and Oldham Councils
157. or below the impounded lengths of critical embankments These zones are there to trigger the scoping stage of a flood risk assessment and should not be considered as comprehensive It is the developer s responsibility to ensure that where a site is below canal level and within 1km that the screening exercise is undertaken and reported on in the FRA Within the SFRA direct hazard zone a FRA must appraise the actual risk of flooding to the site due to overtopping and or breaching of the canal Guidance on this is provided below As part of the Level 2 SFRA an indirect canal hazard zone has been produced to show the impact that a breach in the canal embankments upstream of Rochdale town centre could have on water levels in the River Roch if it occurred coincidental with a 1 in 100 year flood event on the river It is considered likely that during such an extreme event that critical infrastructure such as canals bridges and weirs fail or are compromised and pose an enhanced flood risk Guidance for Developing in the Direct Canal Hazard Zone If a proposed development site is located within the SFRA direct canal hazard zone then a three stage approach is proposed which may include some or all of site screening scoping and a detailed assessment Stage 1 Site Screening The FRA should address the following questions for overtopping and breach as a first stage e s the site within the SFRA direct canal hazard zone e ls the proposed finished lev
158. or map references Flood Awareness Emergency Planners should also use the outputs from the BRO SFRA Volume II and Ill to raise awareness within local communities This should include raising awareness of measures that people can take to make their homes more resilient to flooding from all sources and encouraging all those at fluvial flood risk to sign up to the Environment Agency s Floodline Warnings Direct service JBA Consulting www jbaconsulting co uk 46 Bury Rochdale and Oldham Councils a e e Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide CONSULTING JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils P e e Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide CONSULTING JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide A 1 FLOOD RISK CONCEPTS A 1 1 A 1 2 Introduction Flooding is a natural process and can happen at any time in a wide variety of locations Flooding is a temporary covering of land not normally covered by water and presents a risk when people human and environmental assets are present in the area which floods Assets at risk from flooding can include housing transport and public service infrastructure commercial and industrial enterprises agricultural land and the environmental and
159. ority Flood Plan to reflect the above findings o Consider the need for evacuation plans for existing vulnerable institutions in the floodplain and other areas at high flood risk o Consider reviewing and updating safe evacuation routes and access routes for emergency services from any existing area of flood risk to rest centres avoiding routes that may be flooded o Review the Greater Manchester Community Risk Register CRR Planning Approval Flood Plans including Flood Warning As a condition of planning approval flood evacuation plans should be provided by the developer which aim to safely evacuate people out of flood risk areas using as few emergency service resources as possible These plans should detail any prearranged emergency arrangements including dry evacuation routes flood warning location of rest centres and safe havens It is recommended that any flood evacuation plan written is forwarded onto Bury Rochdale or Oldham Councils as appropriate and the Environment Agency for review The plan owner must put in place the plan if the development goes ahead and liaise with the council regarding long term maintenance and updating of the plan It should be noted that the emergency services are unlikely to regard developments that increase the scale of any rescue that might be required as being safe According to the PPS25 Practice Guide flood warning and evacuation plans should include the information highlighted in Table 6 1 The t
160. osed development sites Sequential Test Appropriate to Allocate Sustainable Appraisal Flood Risk Indicator not required Avoid Or remove development area at flood risk Flood Zone 1 amp not in CDA Flood Zone 3b Low risk from other sources Sequential Test Spreadsheet Can development be located in lower risk areas within site boundary Flood Zone 2 3a Flood Zone 2 3a and or within CDA Low fluvial cover Can yield be achieved in lower amp low medium surface High fluvial Cover risk areas water risk Are there any Strategic Planning No Objectives Yes Check with Core Strategy Yes Appropriate to y Allocate Level 2 SFRA required Flood Risk avoided Review required using detailed flood risk reduced through information and identify likelihood of substitution passing Exception Test Once the requirement for a Level 2 SFRA has been identified Spatial Planners will need to assess the likelihood of sites passing the Exception Test This is seen as a critical part of the spatial planning process by avoiding inappropriate development being allocated The Environment Agency and or Development Management are likely to object to inappropriate development During Steps 9 and 10 Spatial Planners are asked to assess whether or not a site highlighted at flood risk has the potential to pass the Exception Test This requirement can
161. ost not be economically justifiable for low value land uses Housing allocations are not suitable The likelihood of passing the Exception Test is lower unlikely to be economically viable and employment allocations should be reconsidered in favour of alternative lower risk sites Emergency planning must be considered and safe access and egress routes should be identified Opportunities for floodplain and river restoration and or buffer strips should be investigated JBA Consulting www jbaconsulting co uk 41 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 200985002 Volume I SFIRA User Guide jba Flood Risk Zone Source SFRA Data Source Appropriate Development Comments Possible Mitigation Flood gt 1 5m and or for all Zone 3 depths Dangerous None Flood risk mitigation measures are unlikely to be economically justifiable and all development should be avoided Development is unlikely to be sustainable and the likelihood of passing the Exception Test is low Large mitigation schemes would be required including raised defences However this is not a preferred option as a residual risk of flooding will remain Compensatory storage must be provided where raised defences remove storage from the floodplain Emergency planning must be considered and safe access and egress routes should be identified Opportunities for floodplain and river res
162. oximately 30m s Stage C When the breach in Stage B has formed to canal bed level erosion of a soft canal bed will continue to take place along the length of the canal in two directions away from the breach location As continual erosion of the bed takes place flow from the canal weirs over into the resulting eroded hole The maximum flow weiring into the eroded hole from each leg of the canal is limited by the width of the canal This has been modelled by British Waterways as two broad crested weirs In those circumstances when no data is available a simplistic but conservative approach can be adopted The key parameters to replicate are an appropriate peak flow and correct total outflow volume An example breach hydrograph used in the SFRA is as follows It is the responsibility of the developer within the FRA to establish whether this sample hydrograph is appropriate to the site Figure 4 2 Example breach hydrograph 35 20 Flow m s ul K 5 S 0 100 200 300 400 Timestep 5 mins JBA Consulting www jbaconsulting co uk 31 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 4 5 2 4 5 3 4 5 4 4 5 5 Guidance for Developing in the Indirect Canal Hazard Zone If a proposed site is within the indirect canal hazard zone the risk of canal breach in conjunction with high river levels must be considered The residual risk associated with such an occurr
163. perations of operating authorities for flood and coastal erosion risk management The 2004 consultation document Making Space for Water sets out the following vision we want to make space for water so that we can manage the adverse human and economic consequences of flooding and coastal erosion while achieving environmental and social benefits in line with wider government objectives In other words the aim of the strategy is to balance the three pillars of sustainability managing flood risk and ensuring that the social and economic benefits which accrue from growth and development are attained This balanced approach integrating sustainable development with responsible risk management has underpinned this SFRA Section 7 of the consultation document deals with measures to reduce flood risk through land use planning which emphasises the Government s commitment to ensuring that the planning system aims to reduce flood risk wherever possible and in any event should not add to it However it is acknowledged that 10 of England is already within mapped areas of flood risk and that contained within these areas are some of the Brownfield sites which other areas of Government policy has identified as a priority for future housing provision The document asserts that over the past five years 11 of new houses were built in flood risk areas The document identifies three sets of measures which may be undertaken to manage flood risk w
164. ply the sequential approach to site layout when matching land use vulnerability within flood risk areas as described in PPS25 and pass the Exception Test However where a site has not been identified within a Sequentially Tested LDD the Sequential Test will need to be applied i e the developer will need to provide evidence to the LPA that there are no other reasonable available sites where the development could be located The LPA will then use this information to apply the Sequential Test This particularly applies to Windfall Sites that have not been allocated in the LDF Development Management and developers should refer to section 2 4 of this report for guidance on applying the Sequential and Exception Tests This includes identifying a zone of search to apply the Sequential Test as recommended If the zone of search is reduced from the full council area to an individual community or specific location it is critical that evidence is provided to justify this decision For example the area may have an essential requirement for this type of development or provides essential services for the development Developers will need to provide evidence that the Exception Test can be passed This will be needed for allocated and windfall sites if required according to the vulnerability of the proposed land use areas requiring redevelopment or regeneration redevelopment of existing single properties or changes of use Development Management will then need
165. pments the aim is to not increase runoff from the undeveloped situation for Brownfield re developments the aim is to reduce existing runoff rates Wherever possible this should be achieved through the implementation of a sustainable drainage or flow retention system constructed within the boundaries of the development site There are many different SUDS techniques which can be implemented As a result there is no one correct drainage solution for a site In most cases a combination of techniques using the Management Train principle will be required Figure G1 shows the SUDS Management Train principle where source control is the primary aim Figure G1 SUDS Management Train principle 66666 6 6 Conveyance 4 Conveyance 4 46 Prevention 6 6 2 Source control Site control Regional control Discharge to watercourse or groundwater Discharge to watercourse i or groundwater A Discharge to watercours or groundwater Regarding flood risk those SUDS with a high primary process for dealing with water quantity should first be investigated before other benefits such as water quality and environmental befits are included SUDS can reduce the amount and rate of runoff by a combination of e Infiltration e Storage and e Conveyance There are a number of SUDS techniques which could be used individually or as part of a management train however their suitability relies on the site and catchment des
166. ppropriately assess flood related issues and determine any effective mitigation measures needed to be put in place It should be recognised that the SFRA has assessed flood risk at a strategic level which can be used to provide evidence for a Level 1 and Level 2 FRA However where a more detailed FRA is required the developer should undertake a detailed assessment of the flood risk to the site using the SFRA to scope out flood risk issues and referring to the guidance in the SFRA User Guide PPS25 its Practice Guide and CIRIA Report Development and Flood Risk Developers should satisfy themselves that the data provided in this SFRA is up to date and accurate for their development Table 4 2 scopes when a more detailed FRA is likely to be required The actual scope of the FRA should be agreed between the developer LPA and Environment Agency before it is undertaken JBA Consulting www jbaconsulting co uk 23 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide Table 4 2 FRA considerations and SFRA supporting evidence Considerations Supporting evidence in the SFRA Volume II Flood Zone Maps or Flood Zones The development other than minor development is on Environment Agency website if updated situated in Flood Zone 2 and 3 See PPS25 Practice Guide section 2 46 for definition of major developments The development is greater than 0 5ha and situated in Flood Zone 1 but there
167. puts from the Level 1 and Level 2 SFRAs e Raise awareness of flood risk from all sources o Using outputs from the Level 1 and Level 2 SFRAs Introduction This section provides guidance on how Local Authority Emergency Planners can use the outputs of the SFRA to update Multi agency Flood Plans and provide advice on Flood Plans written by developers for new development Emergency Planning Overview Under the Civil Contingencies Act 2004 Bury Rochdale and Oldham Councils are classified as a category 1 responder During an emergency such as a flood event coordination with the other category 1 responders including the emergency services and the Environment Agency is essential to guarantee the safety of residents Under the Civil Contingencies Act the Local Authority holds a statutory duty to provide civil protection to their communities to ensure human welfare environmental stability and UK security are not affected Under the Act risk assessments and planning is arranged through Local and Regional Resilience Forums LRF RRF Bury Rochdale and Oldham Councils are part of the Greater Manchester Resilience Form GMRF http www gmep org uk ccm navigation greater manchester resilience website GMRF s overall purpose is to ensure that there is an appropriate level of preparedness to enable an effective multi agency response to emergency incidents that may have a significant impact on the communities of Greater Manchester Strategic de
168. r SWMPs and Drainage Strategies JBA Consulting www jbaconsulting co uk 36 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 5 FLOOD RISK MANAGEMENT 5 1 5 2 Introduction Throughout the risk based sequential approach the need to take a sequential approach when allocating land for development should always be kept in mind and opportunities taken to minimise flood risk at every stage of the planning process Mitigation measures should be seen as a last resort to address flood risk issues to new development Mitigation measures must be designed to provide an appropriate level of protection to a site for the lifetime of the development At many sites it may be technically feasible to mitigate or manage flood risk However the potential impacts of mitigation measures on flood risk to the surrounding community must always be considered and where the depth of flooding is substantial these mitigation measures may result in practical constraints to development with significant financial implications There will always be a residual risk remaining that should be accounted for through effective emergency planning The minimum acceptable standard of protection against flooding for new property within flood risk areas is the 1 in 100 year flood event for fluvial flooding with an allowance for climate change over the lifetime of the development Strategic Approach Mitigation
169. ral defect e g slippage cracking poor maintenance designed to inform the maintenance programme The Environment Agency s National Flood and Coastal Defence Database NFCDD condition ratings are shown in Table A2 Table A2 NFCDD condition ratings for flood defences anaes Condition Condition Description 1 Very Good Fully serviceable 2 Good Minor defects 3 Fair Some cause for concern Requires careful monitoring 4 Poor Structurally unsound now or in the future 5 Very Poor Completely failed and derelict The condition of existing flood defences and whether they will continue to be maintained and or improved in the future is an issue than needs to be considered as part of the risk based sequential approach and in light of this whether proposed land allocations are appropriate and sustainable In addition detailed FRAs will need to explore the condition of defences thoroughly especially where these defences are informal and contain a wide variation of condition grades JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide Defences that are not in good condition could be prone to failure during a flood event Defences that offer a low standard of protection are likely to overtop during flood events that are more extreme than the event that they were designed to protect against Flood risk associated with
170. re and District Places Key diagram Key Major roads Canals Rivers Urban areas Ga Town centres Ce Major woodlands and urban parks Conservation areas fy Natural and landscape heritage core areas 1 West Pennines 2 South Pennines 3 Edge of Peak 4 Dunham 5 Mosslands 6 Greenheart Regional Park 7 River Irwell Croal and Roch 8 Huddersfield Narrow Canal Tame Corridor 9 Mersey Valley 10 Rochdale Canal Corridor 11 Irwell City Park 12 Medlock Valley Destination parks 1 Haigh Hall 2 Pennington 3 Rivington Smithills 4 Levenshulme Muses Gale 5 Dunham 6 LIVIA inc Clifton 7 Heaton Park 8 Alexandra Park 9 Sale Water Park 10 Philips Park 11 Alexandra Park UMT data Copyright CURE ASCCUE EPSRC GR S19233 01 Universily of Manchester 2005 0 25 5 10 Data Source AGMA 12 Hollingworth Lake Crown copyright All rahts reserved 13 irwell City Park proposed T O OA LOAR IIO EACBSA G1547 028b JBA Consulting www jbaconsulting co uk 16 Bury Rochdale and Oldham Councils be w Strategic Flood Risk Assessment a 2009s0042 Volume SFRA User Guide 3 GUIDANCE FOR DEVELOPMENT MANAGEMENT The aim of this section is to provide guidance on the use of the SFRA by Development Management Planners should also refer to the guidance on SFRA maps provided on page vi and background to the SFRA and flood risk concepts in Appendix A a
171. re moving onto the next stage A larger number of iterations and or consultations on the FRA maybe needed if significant mitigation measures are proposed and compensational storage is required to assure the LPA and Environment Agency that the development can remain safe and meets all requirements This figure also links the evidence provided in the BRO SFRA which can aid the decision making process Section 5 and Appendix G of this Volume and Volume III section 9 should also be referred to regarding appropriate mitigation measures JBA Consulting www jbaconsulting co uk 24 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume SFRA User Guide Figure 4 1 FRA preparation Level 1 2 SFRA Level 1 2 FRA Level 3 FRA Input Screening amp Scoping Detailed Assessment Determine Types of impact Scale of impact Potential compensation measures Confirm Mitigation measures are suitable for development Broad assessment of flood hazard Simplified assessment of consequences impacts of development i Detailed i assessment of current risks to development with mitigation Test for robustness Design of compensation works Design of flow balancing y Summary Residual risks Off site impacts Mitigation Measures employed Please see page vi for map references JBA Consu
172. rs SUTY HERA Oldham COUNCIL COUNCIL Council BURY ROCHDALE AND OLDHAM STRATEGIC FLOOD RISK ASSESSMENT VOLUME SFRA User Guide December 2009 FINAL REPORT JBA Consulting Client Address The Brew House Rochdale MBC Wilderspool Park Municipal Offices Greenhall s Avenue Smith Street WARRINGTON ROCHDALE WA4 6HL Lancashire UK OL16 1LQ t 44 0 1925 437 020 f 44 0 1925 437 029 www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide jba Structure of the Bury Rochdale and Oldham SFRA The Bury Rochdale and Oldham SFRA is supplied as four Volumes described in the table below Readers should refer to Volume SFRA User Guide for guidance on how to use the information provided in the SFRA SFRA Volume Title of volume Contents User Guide The BRO SFRA Volume has been developed to provide guidance on the use of the SFRA for Local Authority Spatial Planning Regeneration Development Management and Emergency Planning officers and Developers Level 1 SFRA The BRO SFRA Volume II has used mostly existing data to make an assessment of flood risk from all Sources now and in the future and builds on the Association of Greater Manchester Authorities AGMA Sub Regional SFRA It provides evidence for LPA officers to apply the Sequential Test and identifies the need to pass the Exception Test where required Level 2 SFR
173. rtaken by the Environment Agency to evaluate the potential JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide impact of fluvial and coastal flooding in relation to the proposed housing figures set out in the draft RSS e Assessing any potential flood risk implications related to regionally significant economic development e Considering other sources of flooding such as sewers and groundwater e Considering the potential impacts of climate change In a ranking of fluvial and tidal flood risk that takes into account flood risk and development pressures out of a maximum of 15 points Rochdale scores 6 and Bury and Oldham both score 4 A lower position indicates that development could take place outside of the highest risk areas but a SFRA is required for all local authorities regardless of ranking to further define the risks from all sources of flooding AGMA SFRA The Greater Manchester sub regional SFRA was published in August 2008 on behalf of the Association of Greater Manchester Authorities AGMA The main objective of the SFRA was to bring together existing information and identify where further more detailed assessments are required The SFRA looks into flood risk issues across the AGMA area and considers linkages in the river systems between different Ca local authority boundaries It provides recommendations f
174. rvoirs Act 1975 requires all reservoir undertakers to prepare Flood Plans for those reservoirs where the dam failure could put people s lives at risk or lead to major damage These plans are expected to become available in late 2009 The reservoir Flood Plans will include e An inundation analysis to identify the extent and severity of flooding which could result from an uncontrolled release of water i e breaching or failure e An on site plan setting out what the undertaker would do in an emergency to try and to contain and limit the effects of the incident e A communications plan with external organisations mainly the emergency services Defra is currently funding a project to produce a Guide to Emergency Planning for UK Reservoirs which will ultimately use the Flood Plans Until the new Water and Floods Bill is implemented it is unclear how reservoir safety flood risk from breach and planning will be dealt with In the meantime any allocations or applications for development immediately downstream of a reservoir should be considered carefully in liaison with the Environment Agency It should be noted that the hazard is well managed through legislation and it is unlikely that the impact zone downstream of a reservoir would be a reason to stop permitted development It is likely that the flood risk would be mitigated through emergency planning JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Str
175. s main cause is strong The Intergovernmental Panel on Climate Change highlights that we are already experiencing the effects of climate change and if these changes deepen and intensify as they are predicted to do without the right responses locally and globally we will see even more extreme impacts One of the predicted impacts of climate change is more intense periods of rainfall and consequent flooding The PPS1 supplement requires Regional Spatial Strategies and Local Development Frameworks to shape sustainable communities that are resilient to such effects A key objective of the planning system is securing new development and shaping places that minimise vulnerability and provide resilience to climate change in ways that are consistent with social cohesion and inclusion Accordingly new development should be planned to minimise future vulnerability in a changing climate The SFRA incorporates Sequential and Exception Test information that is essential in meeting the objectives of the PPS1 supplement Planning and Climate Change Whilst not directly relevant to the development of an SFRA it is important to recognise that the exercise takes place within the context of other planning policy guidance and statements some of which also require sequential testing of site allocations and development proposals PPS3 Housing emerging PPS4 Planning for Sustainable Economic Development and PPS6 Planning for Town Centres are intrinsic within the planni
176. s should seek opportunities to reduce the overall level of flood risk in the area and beyond through the layout and form of the development and the appropriate application of sustainable drainage techniques Definition This zone comprises land assessed as having between a 1 in 100 and 1 in 1000 annual probability of river flooding 1 0 1 and between a 1 in 200 and 1 in 1000 annual probability of sea flooding 0 5 0 1 in any year Appropriate uses The water compatible less vulnerable and more vulnerable uses of land and essential infrastructure listed in The Flood Risk Vulnerability Classification see Table A 2 are appropriate in this zone Subject to the Sequential Test being applied the highly vulnerable uses in Table D 2 of PPS25 and Table B 2 of this report are only appropriate in this zone if the Exception Test is passed FRA requirements All development proposals in this zone should be accompanied by a FRA See Annex E of PPS25 for minimum requirements Policy Aims In this zone developers and local authorities should seek opportunities to reduce the overall level of flood risk in the area through the layout and form of the development and the appropriate application of sustainable drainage techniques JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide Zone 3a High Probability
177. shown in Figure A2 below This is a standard environmental risk model common to many hazards and should be starting point of any flood risk assessment However it should be remembered that flood risk can occur from many different sources and pathways and not simply those shown in the simple form below JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide A 1 4 Figure A2 Source Pathway Receptor Model Pathway e g defence Receptor e g people in the _ floodplain Overland Flooding Source River or Sea Sewer Flooding Groundwater Flooding The principal sources are rainfall or higher than normal sea levels the principal pathways are rivers drains sewers overland flow and river and coastal floodplains and their defence assets and the receptors can include people their property and the environment All three elements must be present for flood risk to arise Mitigation measures have little or no effect on sources of flooding but they can block or impede pathways or remove receptors The planning process is primarily concerned with the location of receptors taking appropriate account of potential sources and pathways that might put those receptors at risk It is important to define the components of flood risk in order to apply this guidance in a consistent manner Flood risk is a combination of the li
178. sideration of canal breach mechanisms should be referred to where necessary A description of typical breach mechanisms is provided below Proposed finished floor levels in relation to the risk of canal flooding Risks associated with canal breach should be taken into account by raising habitable floor levels increasing the designed freeboard levels to take account of the risk but FRAs will need to consider this along with the measures taken to manage other sources of flood risk See note on developing in the indirect canal hazard zone Residual risks and how they should be managed Flood warning and resilience measures may be appropriate It is acknowledged that depending on the likelihood of canal failure and its consequence that the management of this risk should be balanced between resistance and resilience measures see PPS25 Practice Guide The developer should liaise with the LPA and British Waterways to determine suitable emergency planning arrangements It is for the FRA to conclude on that balance and demonstrate that the risk can be managed through design and appropriate awareness raising and flood warnings British Waterways 2008 British Standards Hydraulic Design of Canal Works Good Practice Guide i Dun R W 2006 Reducing uncertainty in the hydraulic analysis of canals Proceedings of the Institution of Civil Engineers Water Management 159 pages 211 224 6 Dun R W 2007 An improved understanding of canal h
179. ssued before development can begin e Increased emphasis is needed on enabling flood water to safely flow overland with green infrastructure and safe flow routes being identified as part of flood risk assessments e County or unitary authorities the Environment Agency and IDBs will have powers to formally designate natural and man made features similar in principle to the Listed Buildings classification which help to manage flood or coastal risk they will give formal consent before anyone can change or remove the feature and use enforcement powers where needed e All relevant authorities will be required to co operate and share information The content and implications of the draft Bill provide considerable opportunities for improved and integrated land use planning and flood risk management by local authorities and other key partners The integration and synergy of strategies and plans at national regional and local scales is increasingly important to protect vulnerable communities and deliver sustainable re generation and growth Improving Surface Water Drainage The Improving Surface Water Drainage consultation document was produced in support of the Government s water strategy and in line with Sir Michael Pitt s initial conclusions Many of the proposals identified have been carried forward into the new draft Flood and Water Management Bill The consultation considers policy measures to improve the way surface water runoff is manag
180. sues need to be taken seriously and mitigation and adaptation measures planned and adopted by Regional and Local Authorities Principle adverse flood risk effects of climate change threatening people and property include e More frequent and intense rainfall events causing flash flooding to low lying areas e More and faster surface water runoff and overland flows causing sewers drains rivers and streams to overflow e Increased sea level rise storminess and frequency of storm surges threatening low lying coastal communities e Rising groundwater levels causing increased spring source activity and higher spring flows increasing the risk of flooding If not addressed these effects are likely to have a significant impact on many communities and in particular new developments in areas at high risk of flooding Recent climate change trends are contained within a UK Climate Impacts Programme document The Climate of the United Kingdom and Recent Trends which was published in December 2007 The next UKCPO9 report that includes revised climate change predictions was launched in late 2009 In recognition of the Governments increasing concerns about the effects of climate change on flood risk management Defra produced a Supplementary Note to Operating Authorities Climate Change Impacts in October 2006 in which they updated the climate change policy for flood and coastal management This document is available on the Defra website In
181. t of flooding from other sources as well as matching the level of risk associated with other sources with those presented within the three Flood Zones For instance Flood Zone 3 cannot be directly related to a high susceptible area at risk of surface water flooding as the probability and consequences are significantly different Whilst it may not be appropriate to avoid development at risk from other sources of flooding risk should be considered when taking a sequential approach to land use or the substitution of lower development vulnerability in higher risk areas within a development site Exception Test If the Sequential Test has been successfully applied following the steps in Figure 2 3 and the LPA cannot allocate development in lower flood risk areas Table D 2 of PPS25 and the vulnerability of development should be referred to A copy of this Table can be found in Appendix F Only once the vulnerability of the development is defined using Table D 3 of PPS25 should an assessment be made of whether or not that development is appropriate within that Flood Zone and whether the Exception Test needs to be applied Figure 2 2 below has been produced from Table D 3 of PPS25 JBA Consulting www jbaconsulting co uk 8 Bury Rochdale and Oldham Councils e te Strategic Flood Risk Assessment a 2009s0042 Volume SFRA User Guide Figure 2 2 Where the Exception Test applies Category Flood El HV MV LV WC Zone 1 mm ae 2 mm
182. tage for canal breach risk is required the following should be addressed JBA Consulting Assess materials used for the construction of the embankment British Waterways advise that some sections of the Rochdale Canal are likely to be constructed of Castleton Sand Granular materials are likely to be more susceptible to failure than cohesive materials and will have a different breach mechanism www jbaconsulting co uk 29 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide The structural geotechnical condition of the canal embankment Raised embankments in poor condition now or in the future for example with animal burrows are more likely to fail in breach Are these principal embankments This will affect the final breach mechanism adopted The condition and capacity of any culverts underneath the canal The condition of any structures such as aqueducts An assessment of the likely mechanisms of canal breach and consequence at the location s from which the site could be affected A hydraulic model should be constructed in order to understand peak flow volumes and overland flow paths in the event of a breach and the potential depth and hazard to the development site associated with canal flooding The canal should be assumed to be at maximum capacity at the time of breach Any uncertainties and assumptions related to this model should be clearly stated Additional guidance on the con
183. te Some of the recommendations which are relevant to this SFRA include e Recommendation 11 Building Regulations should be revised to ensure that all new or refurbished development in high flood risk areas are flood resistant or resilient e Recommendation 14 Local Authorities should lead on the management of local flood risk with support of the relevant organisations e Recommendation 17 All relevant organisations should have a duty to share information and cooperate with local authorities and the Environment Agency to facilitate the management of flood risk e Recommendation 18 Local Surface Water Management Plans as set out under PPS25 and coordinated by local authorities should provide the basis for managing all local flood risk e Recommendation 52 In the short term the Government and infrastructure operators should work together to build a level of resilience in critical infrastructure assets that ensures continuity during worst case flood event e Recommendation 57 The Government should provide Local Resilience Forums with the inundation maps for both large and small reservoirs to enable them to assess risks and plan for contingency warning and evacuation Pitt s findings conclusions and recommendations for action are challenging but will be extremely important in guiding local authorities and other operating authorities in their consideration of future flood risk management activities including land use plan
184. that contributes to the Sustainability Appraisal of their plans JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment jb a 2009s0042 Volume I SFRA User Guide e Framing policies for the location of development which avoid flood risk to people and property where possible and manage any residual risk taking account of the impacts of climate change e Only permitting development in areas of flood risk when there are no suitable alternative sites in areas of lower flood risk and the benefits of the development outweigh the risks from flooding e Safeguarding land from development that is required for current and future flood management e g conveyance and storage of flood water and flood defences e Reducing flood risk to and from new development through location layout and design incorporating sustainable drainage systems SUDS e Using opportunities offered by new development to reduce the cause and impacts of flooding e g SWMPs making the most of the benefits of green infrastructure for flood storage conveyance and SUDS re creating functional floodplain and setting back defences e Working effectively with the Environment Agency other operating authorities and other stakeholders to ensure that best use is made of their expertise and information so that plans are effective and decisions on planning applications can be delivered expeditiously and e Ensuring spatial
185. the sewer JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide system and flow across the surface of the land often following the same flow paths and ponding in the same areas as overland flows Both Making Space for Water and Future Water recognise the importance of integrated urban drainage and the summer flooding of 2007 highlighted that surface water flooding can cause mass distress damage and disruption The Foresight Report 2004 estimated that 80 000 properties are at very high risk from surface water flooding 1 in 10 chance of occurring in any one year Groundwater Flooding There are several mechanisms which produce groundwater flooding these include e Flooding resulting from prolonged rainfall this is associated with but not particular to Chalk Aquifer areas Flooding resulting from high in bank river levels a particular problem in very large river basins with a large catchment long flood durations and wide valleys with extensive alluvial deposits Occurs in situations where the in bank river water level is at a higher elevation than the surround floodplain e Flooding resulting from artificial obstructions can exacerbate groundwater flooding within floodplains by placing artificial obstructions such as foundations into the ground creating impermeable boundaries damming groundwater up gradient and causing
186. those rights threaten to have a direct significant and adverse effect on a flood risk area or its flood defences and their access or the permeability and management of surface water or flood risk to occupants Proposed Updates to PPS25 On 11 August 2009 CLG published a Consultation Paper on proposed amendments to PPS25 The consultation relates to proposed clarifications to some aspects of the existing national spatial planning policy on development and flood risk to help ensure the policy is applied effectively The consultation process is due to end in November 2009 The proposed amendments affect tables D 1 Flood Zones and D 2 Flood Risk Vulnerability Classification in Annex D of PPS25 It is proposed that the definition of the functional floodplain is updated to The identification of functional floodplain should take account of local circumstances and not be defined solely on rigid probability parameters But land which would flood with an annual probability of 1 in 20 5 or greater in any year or is designed to flood in an extreme 0 1 flood should provide a starting point for consideration and discussions to identify the functional floodplain The reasoning behind this was that by simply stating it should be based on probability rather than local circumstance leads to areas of land that are not intended to allow for floodwater to flow or be stored being inappropriately identified as functional floodplain and potential
187. though integrated solutions for collections of strategic sites The future ownership and maintenance of SUDS systems should be discussed at the planning application stage with the relevant sections of the LPA including Highways and Drainage United Utilities and the Environment Agency This approach should be taken unless the developer can demonstrate that this is not feasible and that there will be no adverse impact caused by the development elsewhere This is supported by Category 4 of the Code for Sustainable Homes which requires developers to ensure that peak run off rates and run off volumes will be no greater than the pre development conditions as a minimum However the code recommends that attenuation of the additional flows caused by development should be related to the degree of flood risk in an area In high flooding risk areas 100 of the additional volume should be attenuated Planning Policy Statement 1 4 allows local planning authorities to stipulate high levels of the code where there are local circumstances that allow and warrant it The SFRA has designated CDAs as high flood risk areas 12 Environment Agency Flood Risk Assessment FRA Guidance Note 1 Development Greater Than 1 Hectare ha in Flood Zone 1 and Critical Drainage areas less than tha Can be accessed online at http www environment agency gov uk static documents Research F RAGuidanceNote1 padf 13 DCLG 2006 Code for Sustainable Homes 14 DCLG 2007
188. to review the evidence provided and decide whether a site passes the Exception Test The community flood risk review tables provided in the BRO SFRA Volume Ill section 8 should help Development Management identify where windfall development may be appropriate on flood risk grounds Development in certain communities may find it difficult to pass both the Sequential Test and Exception Test due to the nature of flood risk and or the scale of mitigation which would be required in order to make the development safe Some communities may require a strategic approach when it comes to planning development due to the possibility of large off site impacts caused by piecemeal development In this case individual developments must adhere to the wider strategic approach towards flood risk management outlined in the BRO SFRA Volume Ill section 9 These should be transformed into flood risk policies within the appropriate LPA LDDs More detail on mitigation options is also provided in section 5 of this Volume JBA Consulting www jbaconsulting co uk 19 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 3 3 PPS25 Practice Guide section 4 23 to 4 45 provides more detail and recommended approach on how to apply the Sequential Test and Exception Test to individual planning applications windfall sites existing and single properties and change of use and must be referred to Supporting the FRA Process
189. toration and or buffer strips should be investigated Surface BRO SFRA Volume Water II Map 1 4 A to O Map 1 7 A to D BRO SFRA Volume Ili Maps 1 1 to 1 6 Low Critical Areas High Medium and Drainage El WC HV MV and LV Although surface water flooding will not directly impact on the spatial allocation of development it should be considered within site layout Surface water will also need to be controlled on site Opportunities should be sought to open up land were surface water is expected to flow or pool SUDS should also be adopted to reduce risk on site and to the surrounding community by first storing water and managing run off rates The additional guidance for developing in CDAs should be considered if appropriate BRO SFRA Volume Hl Maps 5 1 to 5 4 Canals Direct and Indirect El WC HV MV and LV Flood risk from canals is residual Although this will not directly impact on the spatial planning of development it should influence building design and finished flood levels The risk of canals should be mitigated through increasing the freeboard of proposed development finished floor levels Volume III has identified the possible increase in flood level if a breach occurs If a development is situated directly adjacent to a canal flood warning would not be beneficial as breaching would be sudden However raising the awareness of the risk is critical BRO SFRA Volume l
190. torm water drainage system exceeds its discharge capacity it becomes blocked or it cannot discharge due to a high water level in the receiving watercourse Foul sewers and surface water drainage systems are spread extensively across the urban areas with various interconnected systems discharging to treatment works and into local watercourses Typically foul systems will comprise a network of drainage sewers sometimes with linked areas of separate and combined drainage all discharging to sewage treatment works Combined Sewer Overflows CSOs provide an overflow release from the drainage system into local watercourses or surface water systems during times of high flows Surface water systems will typically collect surface water drainage separately from the foul sewerage and discharge directly into watercourse A major cause of sewer flooding is often due to the connection of surface water drains to discharge into the combined sewer systems Sewer capacity can then become an issue in large rainfall events causing the backing up of flood waters internally within properties or discharging through manholes Insufficient capacity can also become an issue where urban areas develop over time with improved sewerage infrastructure provision not always provided to accommodate the additional flows 18 Environment Agency 2007 Making Space for Water Groundwater Flooding Records Collation Monitoring and Risk Assessment Reference HA5 JBA Consultin
191. trol management structures Pro active land use planning has a key role to play in flood risk management as it is one of the few activities that can result in the avoidance of flood risk as opposed to other activities that can only aim to reduce it Effective flood risk management through the planning system is achieved through a hierarchy where e Avoidance of inappropriate development in high risk zones must take priority before e Substitution of lower vulnerability uses where avoidance is not possible is considered Only if avoidance and substitution are not possible e Control and Mitigation of the risks by implementing flood risk management measures through a variety of techniques to reduce the impact and mitigate residual risks Flood risk assessment at all levels of planning and for all major developments is critical to inform decision making by planners and developers Sources of Flooding Flooding can occur from many different and combined sources and in many different ways Different types and forms of flooding present a range of different risks and the flood hazard since the speed of inundation depth and duration of flooding can vary greatly See Figure A1 below With climate change the frequency pattern and severity of flooding are expected to change and become more damaging JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils be Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Gu
192. ts RFRA Sub Regional SFRA Site i Specific FRA SFRA Level 1 SFRA Level 2 Implementation of the sequential risk based approach requires forward planning Policy decisions are best made within RSSs and LDF LDDs guided by information on flood risk ensuring that the allocation of land inappropriate for development does not unnecessarily raise expectations of landowners and developers Policy decisions should be informed through the preparation of RFRAs and SFRAs These assessments are broad brush assessments of the risk of flooding to guide strategic planning decisions They involve the collection and collation of data on flooding and flood risk management to provide information at the appropriate level of detail to allow decision makers to e Prepare appropriate policies for flood risk management within RSSs and LDFs e Understand the scale extent and nature of the flood risk at a community level and how that would alter in the event of a proposed development e Apply a risk based sequential approach to the allocation of land for development and confirm for example the compatibility of the likelihood of flooding and flood risk vulnerability e Assess whether application of the Exception Test is required and if so whether or not it is likely to be passed e Inform the preparation of the Strategic Environmental Assessment of RSSs and LDFs e Translate national guidance into locally specific guidance including for example the id
193. tutory consultee who will advise on the technical side of the FRA CONSULTING iba Supporting Evidence Base SFRA Volume II amp III amp LPA LDDs Environment Agency Flood Map LPA LDD BRO SFRA Volume III Section 8 amp 9 LDD Regeneration Strategy Areas BRO SFRA Volume III Mapping depths hazards amp residual risks BRO SFRA Volume III Section 8 BRO SFRA Volume Section 3 amp 4 Consultation Process Environment Agency Standing Advice http Awww environment agency gov uk researcl planning 82584 aspx BRO SFRA Volume Section 4 Planning Application Form 1app http www planningportal gov uk FRA Pro Forma PPS25 Practice Guide Appendix B PPS25 Practice Guide p 25 18 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 3 1 3 2 Introduction The LPA are the principal decision makers on applications for new development This is carried out through Development Management Whilst it is the overall responsibility of the developer to carefully consider flood risk issues regarding their proposed development site the LPA should be involved at the earliest possible stage during pre application discussions Following on from recommendations made in the Pitt Review Development Management must take some of the roles and responsibilities from the Environment Agency as the first point of call in Flood Risk Management and planning applications
194. uirements of PPS25 in producing a Level 1 SFRA and to determine the main tasks that needed to be completed The meeting also outlined the councils own timetable relating to preparing an evidence base for their LDF process There have been regular progress meetings outlining progress to date and further data requests A member of the Environment Agency has always been present to inform the decision making process Environment The Environment Agency is a statutory consultee for RSSs LDDs Sustainability Agency Appraisals and Strategic Environmental Assessments They are also a statutory consultee for planning applications With regards to the BRO SFRA the Environment Agency has discretionary powers under the Water Resources Act 1991 to manage flood risk and as a result hold the majority of flood risk data in the UK Separate departments were consulted via the External Relations Team including Development Management Flood Risk Mapping and Data Management and Reservoir Safety Teams on the SFRA approach and available data The Environment Agency was also one of the main consultees throughout the preparation of the SFRA and their comments and guidance have been included within report revisions United The main source of information requested from United Utilities was a copy of their Utilities DG5 records After further discussions with the main SFRA project team and the Environment Agency further information such as the location of draina
195. uld seek to reduce existing local flooding problems and not add to them The AGMA authorities are currently developing drainage standards for developments within Critical Drainage Areas In the interim the following guidance should be followed e Development should deliver Greenfield runoff on Greenfield sites up to a 1 in 100 year storm event considering climate change e Development should aim for a reduction in surface water runoff rates of 50 for Brownfield sites with an aim of reducing runoff to Greenfield rates up to a 1 in 100 year storm event considering climate change e Development should be designed so that there is no flooding to the development in a 1 in 30 year event and so that there is no property flooding in a 1 in 100 year plus climate change event Over time it is envisaged that local authorities will commission drainage strategies see below to determine in more detail and establish the evidence base for set reductions in surface water runoff from development sites With regard to this the developer should liaise closely with the Environment Agency United Utilities and LPA as soon as possible to determine an appropriate reduction in runoff rate and volume with reference to discharge limits as laid down by any completed SWMP or drainage strategy for that area Wherever possible this should be achieved through the implementation of SUDS Source control should be considered firstly There may be opportunities to deliver SUDS
196. ulting www jbaconsulting co uk Bury Rochdale and Oldham Councils e Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide Policy Unit Notes Policy changes to the catchment Flood risk management activities are required to maintain culvert capacities C 1 6 Summary In accommodating future development in Bury Rochdale and Oldham there is a range of planning policies to consider and balance on a national regional and local level Future development needs have been broadly specified in regional plans and are being refined on a local level in the emerging LDF PPS25 and its Practice Guide provides the overarching national guidance with respect to development and flood risk emphasising the need to effectively manage flood risk within the planning system rather than relying on reactive solutions to flooding This includes a responsibility for LPAs to reduce flood risk to people and property as a result of new development It also identifies the preparation of SFRAs as a key process in the understanding and management of flood risk for planning purposes It is widely recognised that flood risk is one of a whole raft of policy constraints placed upon the local planning system Development must facilitate the socio economic needs of a community and spatially must sit within an existing framework of landscape and infrastructure For this reason a balance must be sought between development need and th
197. urrent level of flood risk into the future responding to the potential increase in risk from urban development land use change and climate change e Policy 5 Take further action to reduce flood risk e Policy 6 Take action with others to store water or manage run off in locations that provide overall flood risk reduction or environmental benefits locally or elsewhere in the catchment Table C2 below outlines Policy Units covering Bury Rochdale and Oldham generic risk and policy chosen for the area JBA Consulting www jbaconsulting co uk Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume SFRA User Guide Figure C1 Bury Rochdale and Oldham CFMP policy units jba al 1 i 6 a ae eG a Ke re el he aq i 53 ER l 7 eye Sp jae We kis ener s RA A 6 tn ee ras yy nS i 5 TA ay Lay ao Rochdale 4 ea WA af Sap oe D Oe f eas 3 o Na f g f 7 J k An f T Ps hal di a d nds a Ron 2 S ry PIRES Sin y AVA eg lee ge ith _ a Ky 2 be Phi 3h e Chadderton L io a L m j Ji k J CHAS Oldh f hg PA 6 hee 5i x Cip eh me ING 4 4 Fi 5 s y Vv F a lt ee res a ra 5 us ah ste FAL YBRIVGE Fecon cram wiper rem oe 7 a TR Two Uk INFIELD Ls Table C2 River Irwell CFMP policies covering Bury Rochdale and Oldham Policy Unit Notes Policy Radcliffe The standard of protection is currently below target Cl
198. vestigations discussed below e Development of detailed 1D 2D hydraulic river models along the River Irwell and Roch in key development locations e Production of fluvial depth and hazard maps for a range of scenarios including breaching overtopping and the impacts of climate change e Detailed surface water flooding maps e Assessment and modelling of residual risks associated with canals e Assessment of the consequences of upstream development e Producing an outline mitigation strategy for Rochdale and Bury e Maintenance recommendations for Rochdale and Bury e Recommendations for future work Volume IV Rochdale Preliminary Mitigation Review Rochdale MBC commissioned a preliminary review of mitigation options for delivering regeneration for sites that are part of the East Central Rochdale Pathfinder Housing Market Renewal and Town Centre East initiatives This has involved considering the viability of mitigation options in light of constraints including costs and land availability and investigating different routes to delivering development JBA Consulting www jbaconsulting co uk 3 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume I SFRA User Guide 1 3 SFRA Monitoring and Review jba Whilst the BRO SFRA has been produced using the most up to date national guidance and flood risk data it is recommended that the SFRA should be updated on a regular basis The Environment Agency has suggested
199. y Rochdale and Oldham Councils e Strategic Flood Risk Assessment a 2009s0042 Volume I SFRA User Guide E e APPENDICES APPENDIX A FLOOD RISK CONCEPTS APPENDIX B FLOOD RISK ASSESSMENT HIERARCHY APPENDIX C THE PLANNING FRAMEWORK APPENDIX D STAKEHOLDER ENGAGEMENT AND DATA MANAGEMENT APPENDIX E FLOOD RISK ZONES APPENDIX F APPENDIX G FLOOD RISK VULNERABILITY CLASSIFICATION SUSTAINABLE URBAN DRAINAGE SYSTEMS Figure 2 1 Taking flood risk into account in LDDS ceccccceeeeeeeeeeeee eee eeeeaeeeeeeeeeeeeeceaeeeeaaeseneeeseaeeeseaaeseeeeees 7 Figure 2 2 Where the Exception Test applies cccccceeececeeeeeeeeeeeeeeeceaeeeeeaeeseaeeseaeeeseaeeseaaesecieessaeeeeeeseneeees 9 Figure 2 3 Sequential and Exception Tests flow diagram cceccceceeceeeeeeeeeeeeeeeeeeeeeaaeseeeeeseaeeesaeeseaeeeeaees 11 Figure 2 4 1 and 2 pass of proposed development sites Sequential TeSt c cssssssssessesessessesseeseeseeee 13 Figure 2 5 Identifying the likelihood of passing the Exception TeSt c cccsecseceeceeeteeeeeeeeneeseeeeeseaeeseeeeeaees 14 Figure 2 6 Green Infrastructure and District Places Key GiaQram c ccccceeeceeeeeeeeeeeeeeseeceeeeeseaaeeteaeeeeaees 16 Figure 3 1 Planning applications and flood riSk cccccceceeeeeeeeeeeeneeceeeeecaeeeeaaeeeeaeeeseaeeeeaaeseeeeesaaeeesaeeseeeeeaees 18 Figure 4 1 FRA preparation eccceccsccessceceeececeeceeaaeeeeneeca
200. y each Test rather the concept in which they are applied What the guidance below will do if followed appropriately is produce clear and transparent evidence that both the Sequential and Exception Test have been applied which can then feed into the Sustainability Appraisal process of LDDs This can either be reported within the Sustainability Appraisal itself or a supporting stand alone document which then feeds into the Sustainability Appraisal The guidance provided in this BRO SFRA User Guide should not supersede PPS25 or other plans and policies but should be seen as a practicable approach in how the LPA should apply the Sequential and Exception Tests within the preparation of the LDF Spatial Planning Flow Diagrams and Tables The following flow diagrams and tables provide a recommended approach for Spatial Planners in applying the two tests keeping in mind the flood risk management hierarchy of avoid substitute control and mitigate whilst identifying and allocating sustainable development sites Colours have again been used to represent key stages in the sequential approach process as identified in Figure 2 1 previously The same colours are used in the flow diagrams and tables below the aim of which is to make it easier to identify what guidance relates to individual steps within the sequential approach sequence Figure 2 3 below illustrates the Sequential and Exception Tests as an input process and output flow diagram The main
201. y objectives regional development framework and sub regional policies within the RSS and various strategic priorities and functional linkages Both Rochdale and Oldham are classified as Pennine Manchester where there is support for potential economic growth and regeneration particularly in Housing Market Renewal Pathfinder areas including replacing and renewing existing housing and where appropriate developing a wider range of housing types Bury is classified as Northern Manchester where there is support for potential economic growth and local regeneration and developing a wider range of housing types Table C1 Housing targets Local Housing target to Annual housing Target for development on Authority 2021 provision previously developed land Rochdale 7 200 400 80 Bury 9 000 500 80 Oldham 5 200 289 80 AGMA has been identified as a national growth point which will enable the delivery of additional housing up to 2017 This will initially focus on Manchester Salford Trafford and Bolton but may also increase housing targets in Bury Rochdale and Oldham The published RSS when compared to the previous demonstrates an increased emphasis and heightened awareness of flood risk Under the emerging RSS Policy EM 5 Integrated Water Management states In achieving integrated water management and delivery of the EU Water Framework Directive plans and strategies should have regard to River Basin Manageme
202. ydraulics and flood risk from breach failures Water and Environment Journal 21 9 18 JBA Consulting www jbaconsulting co uk 30 Bury Rochdale and Oldham Councils Strategic Flood Risk Assessment 2009s0042 Volume SFRA User Guide Typical Breach Mechanisms British Waterways have experience of assessing canal breach mechanisms Canal breaches typically occur in a 3 stage mechanism and this is the recommended approach for a detailed breach assessment at Stage 3 Stage A In a few breach cases overtopping may lead to progressive erosion of the canal embankment face In most breach cases failure of the canal lining leads to piping sub surface flow through the canal embankment which gradually erodes the embankment material from within Stage B Overtopping erosion of the canal may lead to a failure of the embankment and a breach of the raised canal bank The size of the breach in Stage B is typically governed by the depth of the canal The depth of the breach is down to canal bed level and the width is typically twice the depth so that the breach is approximately semi circular in shape For example on a 1 5 m deep canal the breach width may be typically 3 m The time taken to form this breach is dependent on the embankment material Granular materials will erode faster than cohesive materials The breach dimensions govern the maximum flow from the canal Initial tests for the SFRA suggested that an indicative maximum flow is appr

BRO SFRA Volume1 User Guide November 2009

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