E315 – King's Lynn and West Norfolk Strategic

Borough Council of King's Lynn and West Norfolk Strategic Flood Risk Assessment: Annex to Level 1

Final Report

April 2010 (Modified October 2010)

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Notice

This report was originally produced in April 2010 and written in the context of the situation which then existed i.e. the recent publication of the Local Development Framework Core Strategy. The Modifications now inserted take account of subsequent suggested revisions identifying the Rural Key Service Centres as discussed in the ‘Background paper to the Settlement Hierarchy (Policy CS02) and changes from the Proposed Submission document (May 2010)’ and ‘Schedule of Focused Changes’. Concurrent with this work the Secretary of State has also revoked the East of England Plan but, in the interests of expediency, the original text has not been revised to reflect this.

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Contents

1. Introduction 9 1.1 Background 9 1.2 Previous Studies 9 1.2.1 Level 1 Strategic Flood Risk Assessment (Bullen Consultants Ltd, 2005 and Faber Maunsell Ltd, 2008) 9 1.2.2 Phase 1 Water Cycle Study (Entec, 2009) 10 1.2.3 Phase 2 Water Cycle Study (commenced July 2009, Entec) 10 1.3 Structure of Report 10

2. Planning Context 12 2.1 National Planning Policy 12 2.1.1 PPS 25: Development and Flood Risk 12 2.1.2 PPS 1: Delivering Sustainable Development and the Supplement to PPS1: Planning and Climate Change13 2.1.3 PPS 3: Housing 14 2.2 Regional Policy 14 2.2.1 East of England Regional Spatial Strategy 14 2.3 Local Planning Policy 15 2.3.1 Borough of King’s Lynn and West Norfolk Local Plan 15 2.3.2 Emerging Local Development Framework 16 2.3.3 Growth Point Status 16 2.3.4 Urban Development Strategy 17

3. Flood Zone Mapping 19 3.1 Environment Agency Flood Maps 19 3.2 Level 1 SFRA Flood Maps 20

4. Sustainability and Regeneration Objectives for Development 22 4.1 Development Needs 22 4.2 The Exception Test for Development in King’s Lynn 23 4.3 Emergency Planning 27

5. Flood Risks to Rural Key Service Centres 28 5.1 Development in Rural Areas 28 5.2 Screening of Flood Risk 28

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5.2.1 Tidal Flood Risks 28 5.2.2 Fluvial Flood Risks 29 5.3 Discussion over Impacts of Screening Results on Rural Communities 36 5.4 Summary of Screening Key Service Centres 36

6. The Lynn South Expansion Area 38 6.1 Present Day Flood Risks 38 6.2 Future Flood Risks 39 6.3 Suitable Development 39

7. Flood Defences Policy and Maintenance 44 7.1 Shoreline Management Plans 44 7.1.1 The Draft Wash Shoreline Management Plan 2 (October 2009) 45 7.1.2 Draft North Norfolk Shoreline Management Plan (July 2009) 47 7.2 The Great Ouse Tidal River Strategy (Draft for Consultation September 2009) 48 7.3 Catchment Flood Management 49 7.4 Flood Defence Maintenance Regime 50

8. Sustainable Drainage 51 8.1 Introduction 51 8.2 Adoption of SuDS 53 8.3 Existing Drainage in the Borough of King’s Lynn and West Norfolk 54 8.4 Suitability of SuDS for Proposed Development 54 8.5 Recommendations for Site-Specific Assessments 56 8.6 Recommendations for Surface Water Management Plans 56

9. Summary and Conclusions 58

10. References 60

Table 4.1 Flood Risk Vulnerability and Flood Zone ‘Compatibility’ (PPS25 Table D.3) 24 Table 4.2 Policy suggestions for Development in King’s Lynn town within Flood Zone 3 (Including Flood Zone 3a with an Allowance for the Potential Impacts of Climate Change) 26 Table 5.1 Results of Flood Risk Screening of Key Rural Service Centres 30 Table 6.1 Summary of Present Day Flood Risks 38 Table 6.2 Summary of Future Flood Risks 39 Table 6.3 Flood Risk Vulnerability and Flood Zone ‘Compatibility’ (PPS25 Table D.3) 40 Table 6.4 Land uses suitable under PPS25 for Lynn (South) 42 Table 7.1 Summary of Issues from The Wash SMP 46 Table 7.2 Summary of Issues from North Norfolk SMP 47 Table 7.3 Proposed Actions from Great Ouse Catchment Flood Management Plan 49 Table 8.1 Examples of SuDS Techniques 51

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Table 8.2 Recommended Discharges for Source Protection Zones 56

Figure 3.1 Extract of Environment Agency’s Flood Mapping, November 2009 (http://maps.environment- agency.gov.uk/wiyby/wiybyController?ep=maptopics&lang=_e) 20 Figure 5.1 Climate Change Flood Risks to Key Service Centres 34 Figure 5.2 Extract of Fluvial Flood Risks Map 35 Figure 6.1 Flood Risks to Lynn South Expansion Area 43

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Glossary

Annual Probability. The annual probability of a flood event occurring, so for the 1% AP the chance of a flood occurring AP with that magnitude is 1% in any year. This can also be expressed as a ratio, for example the 1% probability flood is the same as the 1 in 100 year return period.

Catchment Flood Management Plans are produced by the Environment Agency to facilitate understanding of the factors CFMP that contribute to flood risk within a catchment, and how to manage flood risk within the catchment for the next 50 to 100 years.

CIRIA Construction Industry Research and Information Association.

Culvert A watercourse that is channelled beneath a road or railway, usually in drainage pipe.

DEFRA Department for Environment, Food and Rural Affairs.

DTM Digital Terrain Model.

Flood Resistant Measure to prevent flooding or inundation of water.

Flood Resilient Measures to reduce the impact of flooding.

Fluvial A term relating to rivers.

Flood Risk Assessment. A site specific assessment of flood risk from all sources and proposed mitigation to prevent the FRA development and areas downstream from being susceptible to flooding.

Geographical Information System, a system for storing, analysing and managing data and associated attributes which GIS are spatially referenced to the earth.

Ha Hectare.

LiDAR Light Detection and Rada.r

LDF Local Development Framework.

PDL Previously Developed Land.

PPS25 Planning Policy Statement 25: Development and Flood Risk (2006).

SAR Synthetic Aperture Radar (surveying technique).

Strategic Flood Risk Assessment. The assessment of flood risk at a high level for a local authority unit to guide planning SFRA policy and the Local Development Framework.

Special Protection Areas are protected sites classified in accordance with the EC Directive on the conservation of wild SPA birds (79/409/EEC), also known as the Birds Directive. They are classified for rare and vulnerable birds and for regularly occurring migratory species.

Source Protection Zone, a zone defined by the Environment Agency to protect groundwater sources of public water SPZ supply.

Sustainable Drainage Systems are drainage systems that mimic the natural process of rainfall runoff, which are SUDS advocated as best practice to control flood risk, water quality and enhance groundwater recharge and amenity value, through infiltration and attenuation measures.

RFRA Regional Flood Risk Appraisal. A strategic overview of flood risks on a regional scale.

Residual Risk The risk which remains after all risk avoidance, reduction and mitigation measures have been implemented.

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1. Introduction

1.1 Background

Strategic Flood Risk Assessments (SFRA) are required under Planning Policy Statement 25 “Development and Flood Risk” (PPS25) to be produced by individual planning authorities, in consultation with the Environment Agency, to form part of the authority’s Core Strategy evidence base. The SFRAs should take account of all forms of flooding, refine the information available on the Agency’s Flood Map if appropriate, apply the Sequential Test and, where necessary the Exception Test in the development allocation and development control process and inform the Sustainability Appraisal of the Core Strategy.

SFRAs should be undertaken in two stages. A Level 1 SFRA should be sufficiently detailed to allow application of the Sequential Test and to identify whether development can be steered away from high and medium flood risk areas, based on all sources of flooding, not just river and coastal, or whether application of the Exception Test is necessary. Where the Level 1 SFRA demonstrates that land in Flood Zone 1 (taking climate change into account) cannot accommodate the necessary development then the Exception Test may need to be applied.

A more detailed assessment will be required, to facilitate further application of the Sequential and Exception Tests and is therefore included in this Annex to the Level 1 SFRA. More detailed information on the planning objectives is necessary where there is development pressure in areas that are at medium or high flood risk and no other suitable alternative areas for development are identified after applying the Sequential Test.

1.2 Previous Studies

1.2.1 Level 1 Strategic Flood Risk Assessment (Bullen Consultants Ltd, 2005 and Faber Maunsell Ltd, 2008)

In 2003, Bullen Consultants Ltd, now part of Faber Maunsell, was commissioned by Kings Lynn & West Norfolk Borough Council to undertake a Level 1 Strategic Flood Risk Assessment. The report was published in 2005 and identified and mapped the areas of actual flood risk over the whole of the Borough within the categories defined in the then current Planning Policy Guidance Note 25. The “actual” flood risk included taking account of the flood defences present.

Following advances in hydraulic modelling techniques, topographical surveying of the Borough using airborne light detection and radar (LiDAR) techniques and the publication of PPS25, Faber Maunsell were asked to carry out the work of revising and updating the original Strategic Flood Risk Assessment. The revised Level 1 SFRA also reviewed the flood risks in 11 development areas of the Borough.

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The revised Level 1 SFRA was published in 2008 and included two dimensional TuFLOW modelling to map the “actual” risk to the boroughs. The modelling took into consideration the presence of flood defences and assessed overtopping leading to breaching of these defences when delineating the “actual” flood risk zones. A Rapid Inundation Zone was mapped for the King’s Lynn area, and the effects of climate change were also considered, as set out in PPS25.

1.2.2 Phase 1 Water Cycle Study (Entec, 2009)

Entec has recently completed the Phase 1 Water Cycle Study for Kings Lynn and West Norfolk which included an assessment of flood risk and drainage. Primarily the study summarised the findings of the 2005 and 2008 Level 1 SFRA. Using the mapped outputs from the revised Level 1 SFRA (Faber Maunsell, 2008) and supplied housing data from the Council, it was found that 91 out of 118 sites were in Flood Zone 1. However some of the strategic development sites for the development are located in Flood Zones 2 or 3.

A strategic assessment of SuDS potential across the study area was also undertaken, with a summary of the benefits of using SuDS and potential adoption processes to implement these drainage measures.

1.2.3 Phase 2 Water Cycle Study (commenced July 2009, Entec)

Entec are in the process of preparing a Phase 2 WCS for Kings Lynn and West Norfolk, which includes flood risk and drainage assessments. The scope for this work, as defined in our supplied tender document, includes further assessment of the flood risk to the development sites from surface water flooding and scoping the need for a Surface Water Management Plan. The WCS does not include for providing policy recommendations for development in high flood risk areas, or providing the evidence for the Sequential Test and Exception Tests, therefore this Annex to the Level 1 SFRA is required to provide this information.

1.3 Structure of Report

The scope of works for the Level 2 SFRA has been defined taking into consideration the requirements of PPS25 and the work already undertaken (or that which has been commissioned).

The Annex will become a tool to ensure new development occurs in the most appropriate location, as well as detailing where further work relating to flood risk would need to be undertaken (e.g. what Council should request from a developer’s site specific FRA, see Table 4.2).

As the Level 1 SFRA and Phase 1 WCS have identified strategic development locations are within medium to high probability flood zones (Flood Zones 2 and 3), it is necessary to include in this report the evidence for the Exception Test as to why development should proceed in these areas. The flood zone outputs from the Level 1 SFRA are used for this assessment. The flood zones are also used to undertake a high level screening of flood risks to the rural key service centres across the district.

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A database of the current flood defences across the Borough is included, and an assessment of the proposed maintenance arrangements to keep the level of protection afforded.

The structure of the report is as follows:

• Chapter 1 provides an introductory context;

• Chapter 2 outlines the planning context for national, regional and local policy issues;

• Chapter 3 summarises the flood zoning from the Level 1 SFRA;

• The flood defences across the Borough are discussed in Chapter 4;

• Results of the screening of flood risk against rural key service centres is presented in Chapter 5;

• An assessment of the potential for SuDS is presented in Chapter 6;

• Chapter 7 presents the sustainability and regeneration objectives as evidence for the Exception Test for development in Flood Zone 3 in Kings Lynn;

• Chapter 8 provides the summary and conclusions.

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2. Planning Context

This section provides an overview of the planning policies which relate to flood risk in the Borough.

2.1 National Planning Policy

The Strategic Flood Risk Assessment (SFRA) has been undertaken in the context of the new planning policy system in accordance with the Planning and Compulsory Purchase Act 2004. The changes to the planning policy process require the Borough to replace the 1998 Local Plan with a Local Development Framework (LDF). The latest requirements for local planning authorities to deliver LDFs are set out in Planning Policy Statement (PPS) 12 Local Spatial Planning. The 1998 Local Plan for Kings Lynn and West Norfolk will be replaced by a LDF which comprises a suite of documents including a Core Strategy. The SFRA will form part of the evidence base supporting the planning policy framework set out in these emerging documents.

Planning Policy Statements (PPS) are prepared by the Government after public consultation to explain statutory provisions and provide guidance to local authorities and others on planning policy and the operation of the planning system. They also explain the relationship between planning policies and other policies which have an important bearing on issues of development and land use.

Of relevance to the Strategic Flood Risk Assessment are PPS 25: Development and Flood Risk, PPS3: Housing, PPS 1: Delivering Sustainable Development and the supplement to PPS1: Planning and Climate Change.

2.1.1 PPS 25: Development and Flood Risk

This SFRA has been undertaken in accordance with the guidance provided in PPS25 and the accompanying Practice Guide. The aim of PPS25 is to ensure that flood risk is taken into account at a regional and local planning level to deliver sustainable development and to avoid inappropriate development in flood risk areas. Box 1 summarises the key planning objectives.

Central to the policy statement is a sequential risk-based approach to guide development into areas of lowest flood risk where possible, which should be applied at all levels of the planning process. The ‘Sequential Test’ in Annex D of PPS25 should be applied to show that no other suitable sites in lower flood risk areas are available when considering individual planning applications. PPS25 also sets out the need to consider other sources of flood risk (such as groundwater, overland flow and sewer flooding) in addition to the main fluvial and tidal sources. The implications of climate change on flood risk also require consideration so as to ensure that the LDF takes into account future risk and promotes sustainable development.

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Box 1 Summary of PPS25 Objectives

The key planning objectives as stated in PPS25 are that: “Regional Planning Bodies (RPBs) and LPAs should prepare and implement planning strategies that help to deliver sustainable development by: • APPRAISING RISK Identifying land at risk and the degree of risk of flooding from river, sea and other sources in their areas; Preparing Regional Flood Risk Assessments (RFRAs) or Strategic Flood Risk Assessments (SFRAs) as appropriate, as freestanding assessments that contribute to the Sustainability Appraisal of their plan. ; • MANAGING RISK 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; Only permitting development in areas of flood risk when there are no reasonably available sites in areas of lower flood risk and benefits of the development outweigh the risks from flooding. • REDUCING RISK Safeguarding land from development that is required for current and future flood management e.g. conveyance and storage of flood water, and flood defences; Reducing flood risk to and from new development through location, layout and design, incorporating sustainable drainage systems (SUDS); Using opportunities offered by new development to reduce flood risk to reduce the causes and impacts of flooding e.g. surface water management plans; making the most of the benefits of green infrastructure for flood storage, conveyance and SUDS; re-creating functional floodplain; and setting back defences. • A PARTNERSHIP APPROACH Working effectively with the Environment Agency and other stakeholders to ensure that best use is made of their expertise and information so that decisions on planning applications can be delivered expeditiously; and Ensuring spatial planning supports flood risk management and emergency planning.”

Having applied the Sequential Test, where it is not possible, consistent with wider sustainability objectives, for the development to be located in zones of lower probability of flooding, PPS25 introduces the Exception Test. The criteria for exceptions – all of which must be satisfied – include: development must provide wider sustainability benefits to the community that outweighs flood risk; it must be on previously developed land; it must be safe; it must not increase flood risk elsewhere; and it should reduce overall flood risk. Exceptions can also only be permitted where it can be demonstrated that the residual flood risks are acceptable and are satisfactorily managed.

The Town and Country Planning (Flooding) (England) Direction 2006 has made the Environment Agency a Statutory Consultee on all applications for development in flood risk areas, including areas with critical drainage problems and for developments exceeding 1 hectare outside of flood risk areas. After discussion with the Environment Agency LPAs are required to notify the Secretary of State if they remain minded to approve a planning application contrary to a sustained objection from the Environment Agency.

2.1.2 PPS 1: Delivering Sustainable Development and the Supplement to PPS1: Planning and Climate Change

An important theme in government planning policy is the need to achieve sustainable development which includes dealing with Climate Change. PPS1 ‘Delivering Sustainable Development’ (2005) and the December 2006 supplements to it on: ‘Climate Change’, ‘Zero Carbon Development’ and the ‘Code for Sustainable Homes’ have

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now been incorporated in a Planning and Climate Change Bill. Climate change will have a profound effect on rainfall and hence flood risk, and PPS25 acknowledges that the future risks of flooding are likely to be more frequent and of greater magnitude than they have been in the past.

2.1.3 PPS 3: Housing

Planning Policy Statement 3: Housing (PPS3) underpins the delivery of the Government's strategic housing policy objectives where the goal is to ensure that everyone has the opportunity to live in a decent home, which they can afford in a community where they want to live.

Most future development in the Borough will be for housing. However, the locations where housing can be built or regenerated are constrained by policies which include those relating to the protection of the environment, reduction of flood risk and maintaining the Green Belt, and therefore need to be sustainable locations in accordance with other PPSs. For example, PPS3 requires that ‘new housing should be built on previously developed land before greenfield land’ however in some circumstances there may be environmental constraints existing on previously developed land.

A careful spatial policy approach therefore needs to be taken at the local level to ensure that: development continues to take place so as to meet long term housing needs; opportunities are taken to reduce flood risk when property is regenerated or redeveloped by requiring mitigation and reduction measures to be a part of development proposals; and by providing clear information about flood risk and policy guidance to landowners and developers. The SFRA will assist by providing a clear and robust flood risk evidence base upon which informed decisions can be made by the Council, residents, developers and the Environment Agency (EA). Policy recommendations are presented in Chapter 7.

2.2 Regional Policy

2.2.1 East of England Regional Spatial Strategy

The Regional Spatial Strategy (RSS) for the East of England was adopted in May 2008 and provides the planning and development strategy for the region to 2021. The RSS establishes the broad principles for sustainable development and growth in the region. It provides Local Planning Authorities with a framework to develop their local policies.

Its objectives are to:

• Reduce the region’s impact on, and exposure to, the effects of climate change;

• Address housing shortages in the region;

• Realise the economic potential of the region and its people;

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• Improve the quality of life for the people of the region; and

• Improve and conserve the region’s environment.

The RSS concentrates growth at key centres for development and change, which includes all of the region’s main urban areas, and has potential to accommodate substantial development in sustainable ways to 2021 and beyond. The East of England Plan policies identify the town of King’s Lynn as a key centre for development and change, for achieving sustainable development through the concentration of new development in this location. Policies in the RSS also identify the Borough as a priority area for regeneration due to its weak economic performance. Furthermore, the RSS outlines the aims for the development and growth of King’s Lynn. These are as follows:

• Enhance the quality of the urban environment;

• Make effective use of previously developed land;

• Provide an improved range of services in the town;

• Support economic development, job growth and the regeneration of communities;

• Provide improved transport choices both within the urban area and between the town and its hinterland.

With regards to Flood Risk Management, Policy WAT4 of the RSS states that Local Authorities should:

‘guide development away from areas likely to be at future flood risk unless the benefits of development outweigh the risks and appropriate mitigation measures are incorporated’.

The Regional Spatial Strategy is currently being reviewed, to provide a framework between 2021 and 2031. The revised RSS is due to be complete by end of 2010.

2.3 Local Planning Policy

2.3.1 Borough of King’s Lynn and West Norfolk Local Plan

The Planning and Compulsory Purchase Act 2004, provides for the saving of policies in adopted or approved local development plans for a period of three years from the commencement date of the Act. Policies in the adopted King's Lynn and West Norfolk Local Plan were due to expire on 27 September 2007, however the Secretary of State, on the request of the Council, saved a number of the policies of the Local Plan for a further three years or until superseded by new policies.

The Saved Policies provide the adopted planning policy framework and direct major new development to King’s Lynn. Whilst limited development at Downham Market may be permitted, expansion of Hunstanton will be restrained. New development should be located in areas with adequate essential public infrastructure and the

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Council may require planning obligations to ensure development is supported with appropriately timed infrastructure.

The saved policies will be superseded by the relevant Local Development Framework policies when adopted.

2.3.2 Emerging Local Development Framework

The Borough is currently preparing its Local Development Framework and has made significant progress with the Core Strategy Development Plan Document, which is due to be submitted for examination to the Secretary of State in mid 2010. The Core Strategy in conformity with the RSS sets out the general spatial vision for the Borough and the means to delivering the vision. The Core Strategy is currently at Regulation 27 Stage (Proposed submission document) which has been subject to a period of consultation for representations to be made before being submitted to the Secretary of State. Once adopted it will provide a planning framework for 15 years.

The proposed Spatial Strategy for the Borough includes the commitment to:

• Facilitate and support the regeneration and development aspirations identified in the Regional Spatial Strategy;

• Encourage economic growth and inward investment;

• Improve accessibility for all to services; education; employment; leisure and housing;

• Protect and enhance the heritage, cultural and environmental assets and seek to avoid areas at risk of flooding;

• Foster sustainable communities with an appropriate range of facilities.

This is to be delivered with the majority of development being located in the Borough’s main towns where this is considered to be sustainable. The Core Strategy proposes that housing will be broadly provided as follows.

• King’s Lynn - 7,100;

• Downham Market - 3,000;

• Hunstanton - 530;

• Rural areas - 5,600 (of which 3,800 will be within the Key Service Centres and 500 in the Wisbech fringe).

2.3.3 Growth Point Status

In October 2007 King's Lynn was designated a Growth Point by Communities and Local Government to support the housing and jobs required in the town. The New Growth Point Status provides access to Communities and

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Local Government growth funding and also funding from East of England Development Agency, Homes & Communities Agency (formerly English Partnerships) and Department for Transport, for meeting the growth target.

The Borough Council has a vision for regenerating King’s Lynn and West Norfolk, and as part of that vision it is envisaged that the population of the urban area of King’s Lynn will grow from 41,500 to 50,000 people up to 2021 and will accommodate approximately 7,000 of the 12,000 new houses earmarked for the Borough. New development will primarily be located on previously developed brownfield land.

The King's Lynn Growth Point Integrated Programme of Development was submitted to central government on 25th October 2008 to request funding to support the implementation of Growth Point.

Priorities for funding outlined in the programme included;

• The allocation of Capital Funds in 2009/10 and 2010/11 towards the works associated with infrastructure provision to allow the full development of the Nar Ouse Regeneration Area (NORA) site and the Waterfront Regeneration Area, including the management and disposal of surface water relating to the development of the northern part of NORA and the Waterfront Regeneration Area and the remediation of land to be developed as part of the Waterfront Regeneration Area;

• The allocation of revenue Growth Funds towards the preparation of a Green Infrastructure Strategy, Water Cycle study, Surface Water Management Plan, King’s Lynn Transportation and Land Use Strategy and towards programme management costs.

Although not all the funds requested were granted, a percentage of the requested funds were given to the Borough from Government, which are being used to plan for the projected growth.

2.3.4 Urban Development Strategy

The Integrated Programme of Development is based on the regeneration policy framework called the Urban Development Strategy. The Strategy was adopted in 2006 to guide the overall regeneration of King's Lynn.

Regeneration is the number one priority in the Borough Council’s corporate strategy. The renaissance of the town is underpinned by the Urban Development Strategy (UDS) which provides an overarching framework to guide the regeneration of King’s Lynn over the next 20 years.

There are four broad headings which form the strategy for regenerating King's Lynn:

• Making the most of existing assets and facilities:- Create a marina at Boal Quay; reinstate the town's historic urban structure and grain; increase and diversify activity in South Quay and waterfront; improve first impressions of the town;

• Focusing development in the town centre: - Focus residential development in the town centre; create new and improve existing open spaces in the town;

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• Improving economic viability: - Provide employment premises; strengthen north-south movement in the town centre to increase viability of the markets and town centre shops; provide mixed use development in the town centre;

• Improving transport: - create two or three multi-storey car parks to replace surface parking from the town centre; investigate business case for park and ride facilities from the outskirts of the town; provide better bus services; promote green travel plans; create a heritage trail and pedestrian and cycle Green Route through and around the town.

Within the UDS, it is stated that King’s Lynn has to be the focus of growth, development and improvement in West Norfolk. By focussing the growth into the centre of the region, all the necessary services and public transport are grouped together making them more accessible to the majority of the population. More compact development, in and around town centres, and where possible on previously-used (‘brownfield’) land, also helps to protect the countryside.

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3. Flood Zone Mapping

3.1 Environment Agency Flood Maps

The Environment Agency has been mapping the likelihood of flooding across England and Wales since 2000. The current map available on their website (www.environment-agency.gov.uk/floodmap) was launched in 2004, and receives regular updates (each quarter) as their modelling programme progresses; to greater define the extent of the probability of flooding. The mapping also locates flood defences.

The map shows the extent of flood zones, based on the probabilities set out in PPS 25. They are:

• Flood Zone 3 (Dark Blue) – the extent of a fluvial flood with a 1% (1 in 100) probability of occurring in any year, or the extent of a tidal flood with a 0.5% (1in 200) probability of occurring in any year; and;

• Flood Zone 2 (Light Blue) - the extent of a fluvial or tidal flood with a 0.1% (1 in 1000) probability of occurring in any year.

All other parts of the flood map that are un-shaded represent the extent of Flood Zone 1, with less than 0.1% probability of a flood occurring in any year.

PPS25 also defines an additional high risk zone, Flood Zone 3b, the Functional Floodplain. This zone comprises ‘land where water has to flow or be stored in times of flood’. The benchmark probability for defining and mapping this zone is the flood event with 5% (1 in 20) probability of occurring in any one year. However, the Practice Guide for PPS25 states that ‘The definition in PPS25 allows flexibility to make allowance for local circumstances and should not be defined on rigid probability parameters. Areas which would naturally flood with an annual exceedence probability of 1 in 20 (5 per cent) or greater, but which are prevented from doing so by existing infrastructure or solid buildings, will not normally be defined as functional floodplain’. It is advised in the Practice Guide that the SFRA for each local authority area defines the functional floodplain for that area, and as such this Flood Zone 3b is not mapped on the Agency’s flood map on their website. The definition for this zone is presented in Section 3.2 below.

The Environment Agency’s flood zones are mapped ignoring the presence of flood defences. However, as the defences do afford some level of protection, the online map also shows which areas benefit from protection of flood defences overlaid on top of the Flood Zones 2 and 3, where this information is available from detailed modelling and mapping.

An extract of the mapping from the Environment Agency website for part of the Borough is presented in Figure 3.1 below.

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Figure 3.1 Extract of Environment Agency’s Flood Mapping, November 2009 (http://maps.environment- agency.gov.uk/wiyby/wiybyController?ep=maptopics&lang=_e)

Flood Zone 3 (1% annual probability of a fluvial flood, 0.5% annual probability of a tidal flood)

Flood Zone 2 (0.1% annual probability of flooding)

Location of Flood Defences

Areas benefitting from defences

The Environment Agency’s flood mapping is carried out on a national scale, using national data on river flows, sea level and topography. The flood map is supplemented by more detailed flood models where available and updated every three months to take account of new data and actual records of flooding.

3.2 Level 1 SFRA Flood Maps

Detailed flood modelling was undertaken in the Level 1 SFRA (2005 and updated in 2008) to map the probable extent of flooding, taking account of the presence of flood defences. The Level 1 SFRA in 2008 used two- dimensional hydraulic modelling, in conjunction with more detailed topographical data to refine the Environment Agency’s Flood Maps in the Borough. The strategic maps are based on the assumption that if the defences are overtopped in the 1% fluvial or 0.5% tidal (Flood Zone 3) and/or 0.1% (Flood Zone 2) events the corresponding flood extent in that flood cell as a result of a breach will be shown.

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The modelling software Tuflow was used, together with digital terrain data from LiDAR. Where gaps in the LiDAR were present, Ordnance Survey radar data (Synthetic Aperture Radar, SAR) was used to infill. Two scenarios were modelled:

• Present Day scenario (2008); and

• Climate Change scenario (for 2115).

In addition to refining the Flood Zones 2 and 3, the Level 1 SFRA undertook flood hazard mapping to map the potential flood extent if a flood defence was to fail or be overtopped. The flood hazard mapping takes account of the potential combination of depth and velocity of flood water behind a defence in the event of a defence failure, to provide a hazard rating.

Where the flow velocity is greater than 0.5 metres per second or the depth of flooding is greater than 0.25 metres, the 2008 Level 1 SFRA defines a ‘Rapid Inundation Zone’, as defined by the Environment Agency.

Flood Zone 3b, the Functional Floodplain, is defined in the Level 1 SFRA (Faber Maunsell 2008) as being any washland or area within the Borough in which the actual annual probability of flooding equals or exceeds 5%.

Flood zones were also mapped for the year 2115 to take account of the effects of climate change on sea level rise and peak river flows.

The Flood Zones mapped in the 2008 Level 1 SFRA for the present day situation (2008) are presented on the Council’s website at the following address (http://www.west-norfolk.gov.uk/PDF/MapIndex51.pdf).

A SFRA protocol was developed by the Environment Agency and the Council in February 2009 (see http://www.west- norfolk.gov.uk/pdf/Strategic%20Flood%20Risk%20Assessment%20KingsLynn%20Protocol.pdf). This advised that as the SFRA mapping was the most up to date, the flood zones should be used in applying the Sequential Test, rather than the flood mapping on the Environment Agency website flood zones. Specifically, the climate change flood zones (representing flood risk up to the year 2115) should be used to ensure sustainable planning for flooding. These are presented on the Council’s website at the following address:- http://www.west- norfolk.gov.uk/PDF/MapIndex52.pdf. The SFRA protocol may be subject to change depending upon the outcome of any revision to the Environment Agency flood map.

The present day situation and predicted future (2115) flood zones produced in the Level 1 SFRA have been used to inform the assessments in this Annex to the Level 1 SFRA.

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4. Sustainability and Regeneration Objectives for Development

4.1 Development Needs

Sections 2.2 and 2.3 discuss the regional and local planning policies for the Borough. The Borough’s Core Strategy vision is essentially seeking to achieve the delivery of sustainable development in conformity with the Regional Spatial Strategy. The Borough has an incredible wealth of environmental assets and is predominantly rural. This presents challenges for the need to provide new homes and associated infrastructure without causing a detrimental impact upon the environment. King’s Lynn is the main town and service centre within the predominantly rural sub region. It has a unique heritage and provides for 55% of all jobs in the Borough, acting as the Borough’s economic driver. Key areas for employment uses include the Hardwick area covering the industrial estates to the south of the town and the Docks, riverside and North Lynn Industrial Estates.

The regeneration of King’s Lynn is one of the Council’s highest corporate priorities and the town has been identified by Communities and Local Government as a Growth Point, therefore a key location for delivering the Government’s housing strategy. This designation will help facilitate the delivery of approximately 7,000 houses and the provision of new jobs in the urban area of King’s Lynn and allow the Borough to access funding from Central Government, and other agencies including East of England Development Agency, Department for Transport and the Homes and Community Agency (formally English Partnerships). The Core Strategy identifies the following goals for the town:

• Regeneration and growth – provision of new homes and jobs in line with designations as both a Growth Point and a Key Centre for Development and Change within the East of England Plan;

• Fostering economic growth and inward investment;

• Improved accessibility for all.

The Core Strategy considers the option of locating new development primarily on previously developed ‘brownfield’ land and mitigating the risk of tidal flooding and fluvial flooding through the provision of effective defences and the design of new developments in lower lying areas, where possible (Vision for the Future, Core Strategy Regulation 27 proposed submission document). The Growth Point Integrated Programme for Development proposes to allocate funding to facilitate the development, in particular of proposed regeneration areas. King's Lynn already has a number of large regeneration programmes and projects underway which are incorporated into the Growth Point Integrated Programme of Development. The Urban Development Strategy published in 2006 sets out the overall sustainable development objectives of development and regeneration of the town. These include:

• Providing opportunities for a lively waterfront;

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• The introduction of more housing and diversifying the town’s shopping, leisure housing and services;

• Fulfilling the needs and aspirations of local people;

• Promoting tourism and inward investment and strengthening the town’s identity;

• Ensuring there is a well preserved historic core.

These objectives all need to be achieved within the context of the environmental constraints upon the town which include fluvial and tidal flood risk. Clearly there are distinct challenges facing the development of King’s Lynn growth point with regard to flood risk, that are separate from the over-riding need of the Borough and of the rural areas. Section 4.2 below discusses the policy for growth with regard to flood risk in King’s Lynn town in more detail. Section 5 discusses the flood risk issues facing the Key Service Centres in the rural part of the Borough.

The delivery of the Nar Ouse Regeneration Area (NORA); the Waterfront Regeneration and Marina; and a framework for a new bus station and retail expansion of the town centre are key priorities of the Urban Development Strategy. The Waterfront Regeneration Area ‘The Quays’ is considered to be the flagship project for the Borough Council and the highest priority in the Growth Point Integrated Programme of Development. The masterplan promotes mixed use development including a 250 berth Marina, up to 980 houses, hotel, café/restaurants and boating facilities for the area at Boal Quay. This scheme will include the regeneration of a brownfield site and a derelict former industrial site adjacent to the historic core of King’s Lynn and provide approximately 300-600 direct and indirect jobs. The NORA is a mixed use regeneration scheme providing housing, employment and enterprise, education, retail and community uses on a site previously derelict and contaminated former industrial land which has recently been remediated. The scheme will provide 900 houses, improvements to the transport network and the provision of facilities for education, employment and the community. The town centre retail expansion will provide additional retail floor space, enhance public transport and community facilities as well as provide 1100 additional jobs.

4.2 The Exception Test for Development in King’s Lynn

The emerging Core Strategy’s proposed spatial strategy and area based policies plan to locate development predominantly in and, where appropriate, adjacent to the urban area of King’s Lynn. Some parts of King’s Lynn are at risk of fluvial and/or tidal flood risk. In accordance with PPS25, the Council is required to demonstrate the Exception Test. This is because large site allocations could potentially be made within flood zone 3 for residential development. This type of development is classified by PPS25 as ‘more vulnerable’ development and therefore it is more appropriate for this type of development to be located in flood zones 1 and 2 where possible. Table 4.1 below reproduces the matrix from PPS25 showing the compatibility of development against the flood zones.

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Table 4.1 Flood Risk Vulnerability and Flood Zone ‘Compatibility’ (PPS25 Table D.3)

PPS25 sets out that if, following the application of the Sequential Test, it is not possible or consistent with wider sustainability objectives for the development to be located in zones of lower probability of flooding then the Exception Test must be applied. PPS25 states that for the Exception Test to be passed:

• 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 DPD has reached the ‘submission’ stage the benefits of the development should contribute to the Core Strategy’s Sustainability Appraisal;

• 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

• A Flood Risk Assessment must demonstrate that the development will be safe, without increasing flood risk elsewhere, and, where possible, will reduce flood risk overall.

With regards to demonstrating part a) of the test, it has been shown through the policies in the adopted Regional Spatial Strategy and emerging Core Strategy, as well as the key aims of the Integrated Development Programme and Urban Development Strategy, that there is a need to provide new development within King’s Lynn. The delivery of growth for the town is focusing on areas such as the Waterside Regeneration Area, the NORA programme and the town centre. Some parts of these sites are potentially at flood risk, and the Waterfront Regeneration Area may be susceptible to a residual risk of rapid inundation if flood defences were to fail on the tidal River Great Ouse.

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Although potentially at a high risk of flooding, the redevelopment of these areas is necessary to deliver the wider sustainability objectives for King’s Lynn benefitting the local community and therefore could be considered to outweigh the risk of flooding. These developments will:

• Deliver the remediation of derelict and contaminated land;

• Provide homes for an increasing population;

• Improve social and environmental conditions for the local population;

• Enhance transport infrastructure and links; and

• Provide new jobs through attracting investment into the town by increasing retail and commercial floorspace.

This will help to address issues of deprivation and weak economic performance currently experienced; will regenerate core areas of the town; promote tourism; and strengthen the town’s identity.

The proposed submission document of the Core Strategy states in its policy CS01, Spatial Strategy, that new development will be:

Guided away from areas at risk of flooding now or in the future, however recognising development may be required within flood risk areas to deliver regeneration objectives within Kings Lynn and maintain the sustainability of local communities in rural areas.

The proposed policy CS08 Sustainable Development states:

The Council’s Strategic Flood Risk Assessment outlines potential flood risk throughout the Borough. In order to ensure future growth within the Borough is sustainable:

• The findings of the Strategic Flood Risk Assessment will be used to guide planned growth and future developments away from areas of high flood risk;

• The Council will work in conjunction with the Environment Agency and ensure that decisions take into account coastal flooding and climate change adaptation issues.

The emerging Shoreline Management Plan will also serve to highlight the future needs and changes that may affect coastal communities arising from changes in climate. The adopted Shoreline Management plans will be material considerations in planning applications.

Policy CS01 acknowledges that some development may be required in flood risk areas to meet regeneration objectives and maintain the sustainability of local communities. Development proposals in high flood risk areas will need to demonstrate that:

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• The type of development is appropriate to the level of flood risk identified in the Strategic Flood Risk Assessment, or

• If the development vulnerability type is not compatible with the flood zone as set out in PPS25, proposals will need to demonstrate that the development contributes to the regeneration objectives of Kings Lynn or the wider sustainability needs of rural communities;

• The development is on previously developed land, or where proposals are for development of greenfield sites, the development must demonstrate a contribution to the regeneration objectives of Kings Lynn or the wider sustainability needs of rural communities;

• Flood risk is fully mitigated through appropriate design and engineering solutions.

In relation to meeting part b) of the test, the Core Strategy and Integrated Development Programme promote the redevelopment of previously developed land. Potential development locations to meet the growth required, which are located within flood zone 3, will be required to be on previously developed land. Many of the development sites will include the remediation of derelict and contaminated land.

With regards to part c) of the test, a Flood Risk Assessment will be required to be prepared with any development application within flood zone 3. The following policy recommendations could be included as part of the Core Strategy and the subsequent Site Allocations Development Plan Documents to ensure development located in flood zone 3 or areas of rapid inundation will be safe without increasing flood risk elsewhere and where possible reduce flood risk overall.

Table 4.2 Policy suggestions for Development in King’s Lynn town within Flood Zone 3 (Including Flood Zone 3a with an Allowance for the Potential Impacts of Climate Change)

Recommendations

1. The development must pass the requirements of the PPS25 Sequential Test and where necessary the Exception Test (as indicated by Table D.3 of PPS25). To pass part (a) of the Exception Test the application must demonstrate that the development meets the sustainability and regeneration objectives of King’s Lynn town, as set out in Chapter 4 of this report; 2 Development should be for the replacement and redevelopment of existing buildings with no increase in building footprint, unless it can be reasonably demonstrated that the design reduces flood risk through physical measures; 3 Development should include SUDS to reduce surface water runoff where possible; 4 Finished ground floor levels should be raised with at least 300 mm freeboard above the 1% AP plus climate change predicted flood level1 5 The developer should identify safe escape and access routes in the event of a flood to an area wholly outside the floodplain2; 6 Consider flood resilient or resistant construction measures that could be incorporated into the design and construction of new development3; and 7 Developments should sign up to the EA’s Floodline Warnings Direct Service.

1 As advised by the Environment Agency at the time of planning application

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4.3 Emergency Planning

In recognition of the flood risks in the King’s Lynn urban area it is advised that the Council reviews and updates its emergency planning for flood events. PPS 25 and the associated Practice Guide (paragraphs 7.23 to 7.31) places responsibilities on Local Planning Authorities to consult their Emergency Planners and the Emergency Services with regard to specific emergency planning issues relating to new development. In all circumstances where warning and evacuation are significant measures in contributing to managing flood risk, the Environment Agency will expect local authorities to formally consider the emergency planning and rescue implications of new development in making their decisions.

2 Where dry access/ escape routes are not available in the event of a flooding incident the role of the emergency planning and the ability of the emergency services to rescue people must be considered.

3 dependant on the vulnerability of the development and in accordance with the Department for Communities and Local Government, "Preparing for Floods" guidance document.

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5. Flood Risks to Rural Key Service Centres

5.1 Development in Rural Areas

The core strategy proposed submission directs the majority of growth and regeneration to King’s Lynn, reflecting the East of England Plan which designates King’s Lynn as a Key Centre for Development and Change, and the Government’s award of the town as a Growth Point. For development in the remainder of the borough, the core strategy will seek to develop a settlement hierarchy, steering development after King’s Lynn to: Downham Market and Hunstanton; and identified Key Rural Service Centres.

The Key Rural Service Centres are areas that will maintain the sustainability of the rural communities and provide a range of services to meet everyday requirements as well as public transport to allow access to and from the settlement. The growth numbers will be in the order of 2,800 between these centres in the rural area.

A screening exercise has been undertaken to review the settlements that are being considered as future Key Rural Service Centres against the level of flood risk expected from both present day and climate change fluvial and tidal flood risks. The list of Key Service Centres was provided by the Council, as those being considered during the preparation of the draft core strategy.

5.2 Screening of Flood Risk

The screening was undertaken in the geographic information system (GIS) ArcMap, to overlay the flood zone extents with the locations of the Key Service Centres. In this manner, the nature of flood risk present is identified. A traffic light system has been used to classify the centres against flood risk, from red, dark amber, light amber to green, representing decreasing risks from tidal or fluvial flooding. These traffic light results are presented in Table 5.1, and on Figure 5.1.

5.2.1 Tidal Flood Risks

By intersecting the tidal flood zones for the present day scenario with the list of potential Key Service Centres, Brancaster, Brancaster Staithe and Burnham Deepdale are the only settlements located partly located within the high risk tidal flood zone 3 based on present day flood risks. However, when considering the flood risk from tidal sources in the future, taking account of climate change and potential sea level rise, a further three sites are considered to be at high risk of flooding. The additional centres are at Heacham, Clenchwarton and Terrington St Clement. Of those at risk from future tidal flooding, both the northern area of the Brancaster settlements and parts of Clenchwarton are within the high hazard zone, and therefore these settlements have been awarded the highest classification of flood risk. Development should be steered away from the hazard zones and tidal flood zone 3 areas of these centres if possible. As Heacham and Terrington St Clement are not within the high hazard zone, and are not wholly within climate change tidal flood zone 3, these have been awarded a slightly lower (dark amber)

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classification. The council should be aware of the location of the flood risks to steer development in these centres into the lowest risk areas wherever possible.

Watlington and the combined centre of Upwell and Outwell are located partly in the climate change tidal zone 2 and /or partly within the hazard zone. However, the majority of the centres are located within Flood Zone 1. These settlements have been awarded a light amber classification to draw attention to the fact that some flood risk exists, but the risks should not prevent development to occur as they are mainly on the settlement outskirts. The settlements of Burnham Market, Terrington St John and Tilney St Lawrence are similarly located on the edge or very near to climate change tidal flood zone 2, but also have some areas of fluvial flood zones present.

5.2.2 Fluvial Flood Risks

Out of the 29 centres being considered to offer key services, 12 are located within the climate change fluvial flood zone 3, as presented by the GIS manipulation in Figure 5.1. However, on closer inspection, the overlaps of the flood zones with the settlements are minor areas on the settlement outskirts. Figure 5.2 presents an extract of the fluvial flood risk map, zoomed in to show Gayton, Grimston, Pott Row, Great Massingham, Castle Acre and Marham as examples. This figure is at a scale where it is possible to see that only a small area of these settlements is in the fluvial flood zones. It is likely therefore that there would be areas suitable for development outside the areas of flood risk from fluvial sources, therefore these settlement should not be wholly discounted for consideration as key service providers to the rural parts of the Borough. These are awarded the lowest risk classification for flood risk.

A summary of the screening exercise is presented in the table below.

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Table 5.1 Results of Flood Risk Screening of Key Rural Service Centres

Fluvial Tidal Flood Flood Flood Flood Zone Flood Flood Hazard Flood Zone Flood Zone Key Service Centre Nature of Flood Risk Probability Zone 2 Zone 3 + climate Zone Zone Zone 2 + climate 3 + climate 3 change 2 3 change change

Clenchwarton High Settlement located within the climate Change Partial Significant Significant tidal Flood Zones 2 and 3; Partly located within the Hazard Zone.

Brancaster/ Brancaster High Located adjacent to North Sea coastline; Partial Partial Partial Partial Partial Brancaster Settlement located partly in Tidal Flood; Staithe/ Zones 2 and 3 and within the climate change tidal Flood Zones 2 and 3; Burnham Hazard Zone also present; Deepdale Existing settlement north of A149 road at high probability of tidal flooding, existing settlement south of A149 at low probability of tidal flooding.

Brancaster High Located adjacent to North Sea coastline; Partial Partial Partial Partial Partial Staithe Settlement located partly in Tidal Flood; Zones 2 and 3 and within the climate change tidal Flood Zones 2 and 3; Hazard Zone also present; Existing settlement north of A149 road at high probability of tidal flooding, existing settlement south of A149 at low probability of tidal flooding.

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Table 5.2 (continued) Results of Flood Risk Screening of Key Rural Service Centres

Burnham High Located adjacent to North Sea coastline; Partial Partial Partial Partial Partial Deepdale Settlement located partly in Tidal Flood; Zones 2 and 3 and within the climate change tidal Flood Zones 2 and 3; Hazard Zone also present; Existing settlement north of A149 road at high probability of tidal flooding, existing settlement south of A149 at low probability of tidal flooding.

West Walton Medium to High Within Climate Change tidal FZ2 and FZ3. Partial Significant Significant Partly located within the Hazard Zone.

Heacham Medium to High Parts of settlement in CC tidal FZ 3 and Partial Partial Partial Hazard Zone. Some risks from Heacham River close to riverpath.

Terrington St Clement Medium to High Within Climate Change tidal FZ2 and FZ3. Significant Significant

Walton Highway Medium to High Within Climate Change tidal FZ2 and FZ3. Partial Significant Significant

Watlington Medium Settlement located partly in the climate Partial Change tidal Flood Zones 2 and 3.

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Table 5.1 (continued) Results of Flood Risk Screening of Key Rural Service Centres

Upwell / Outwell Medium Settlement located partly located within the Partial Partial Hazard Zone.

Burnham Market Medium to Low Potential flood risk from the River Burn, and Partial Partial Partial close to tidal flood zones.

Terrington St John / Tilney St Medium to Low Risks present from climate change tidal flood Significant Partial Significant Partial Lawrence / St John’s Highway zone 2 and present day fluvial flood zone 2.

Dersingham Low Minor risks present from fluvial sources Partial Partial Partial through the village.

East Rudham Low Minor risks present from fluvial sources Partial Partial Partial through the village.

Gayton / Gayton / Low Minor risks present from fluvial sources Partial Partial Partial through the village. Grimston / Grimston Pott Row Pott Row Low Minor risks present from fluvial sources in Partial Partial Partial the west of the village.

Marham Low Potential flood risk from River Nar when Partial Partial Partial taking account of climate change.

Stoke Ferry Low Minor risks present from fluvial sources in Partial Partial Partial the South and East of the village.

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Table 5.1 (continued) Results of Flood Risk Screening of Key Rural Service Centres

Methwold / Methwold Low Minor risks present from fluvial sources Partial Partial Northwold through the village.

Northwold Minor risks present from the River Wissey in Partial Partial the North East of the village

Castle Acre Low Minor risks present from fluvial sources Partial Partial through the village.

Feltwell / Feltwell Low Minor risks present from fluvial sources Partial Partial through the village. Hockwold Cum Wilton Hockwold Nil No flood zones present. Cum Wilton

Docking Nil No flood zones present.

Great Massingham Nil No flood zones present.

Snettisham Nil No flood zones present.

Significant = centre is entirely within the flood zone being considered

Partial = centre is only partly within the flood zone being considered

535000 540000 545000 550000 555000 560000 565000 570000 575000 580000 585000 590000 595000 600000 605000 Key

Borough Boundary Brancaster

345000 345000 Hazard Zone (! (!Brancaster Staithe/Burnham Deepdale N Burnham Market (! Climate Change Flood Zones Tidal Flood Zone 3 340000 340000 Tidal Flood Zone 2 Heacham Docking (! (! Fluvial Flood Zone 3 Key Rural Service Centres Snettisham 335000 335000 (! Low Flood Risk

Medium Flood Risk Dersingham (! High Flood Risk

330000 East Rudham 330000 (! Very High Flood Risk

Definition of Flood Risks Low = Minor or No flood Zones 325000 325000 Great Massingham Medium = Partly within Climate Pott! Row (! Change Zone 3 ! (Grimston High = Within Climate Change Zone 3 Clenchwarton ( Terrington St Clement Very High = Hazard Zone (! (! Gayton 320000 320000 (!

Terrington St John (! Castle Acre Tilney St Lawrence (! 315000 315000 West Walton (! (! Walton Highway (! Watlington (! (!Marham 310000 310000

Upwell 305000 305000 (!

(!Stoke Ferry 300000 300000 0 5,000 Northwold Meters (! Scale: 1:250,000 @ A3 Methwold H:\Projects\HM-255\26655 Kings Lynn Level 2 SFRA\GIS\MXD 295000 295000 (! King's Lynn Level 2 Strategic Flood Risk Assessment Feltwell (! Figure 5.1 290000 290000 Hockwold Cum Wilton Climate Change Flood Risks (! to Key Service Centres 285000 285000 September 2010 26655-b002 fiell 535000 540000 545000 550000 555000 560000 565000 570000 575000 580000 585000 590000 595000 600000 605000 Based upon the Ordnance Survey Map with the permission of the Controller of Her Majesty's Stationery Office. © Crown Copyright. AL100001776 565000 570000 575000 580000 Key

Borough Boundary 325000 325000 Fluvial Flood Zone 3 + CC N Fluvial Flood Zone 2

Fluvial Flood Zone 3 Great Massingham (! (! Key Service Areas Grimston Pott Row(! (!

320000 Gayton 320000 (!

Castle Acre (! 315000 315000

0 500 1,000 1,500 Meters Marham (! H:\Projects\HM-255\26655 Kings Lynn Level 2 SFRA\GIS\MXD King's Lynn Level 2 Strategic Flood 310000 310000 Risk Assessment

Figure 5.2 Extract of Fluvial Flood Risks Map

September 2010 26655-b002 fiell 565000 570000 575000 580000 Based upon the Ordnance Survey Map with the permission of the Controller of Her Majesty's Stationery Office. © Crown Copyright. AL100001776

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5.3 Discussion over Impacts of Screening Results on Rural Communities

The review of existing and future flood risk to existing villages and communities has classified the three centres of Clenchwarton, Brancaster (joint with Brancaster Staithe and Burnham Deepdale) and West Walton as being at high risk to flooding. This is a result of all or part of the villages lying within the High Hazard / Rapid Inundation Zone. It is considered that this zone represents a higher risk to livelihood than Flood Zone 3 due to potentially fast flowing and / or deep water threatening human life.

PPS25 advocates that residential development should not be permitted in Flood Zone 3 or higher risk zones due to the vulnerability of people and property. However, it is recognised that these villages are already providing a wider social and economic service to the surrounding rural communities. The development strategy of the Key Rural Service Centres is yet to be confirmed in the emerging Core Strategy and there is therefore a possibility that some of these villages, including those within the Rapid Inundation Zone, may be identified as centres for future development where the need to provide social and/ or economic services to local communities overrides the risk of flooding.

It is recommended that where possible the Sequential Test is applied for new developments. Where development is needed in Flood Zone 3 or the Rapid Inundation Zone to service the wider area (yet to be determined), developments must ensure that they pass all stages of the Exception Test. In order to pass part a) the development must demonstrate that it contributes to the overriding social, economic and sustainable benefits of the wider community in order to be granted planning permission.

5.4 Summary of Screening Key Service Centres

The comparison of the proposed Key Rural Service Centres with the flood zones, and in particular the climate change flood zones for the year 2115, suggest that the future viability of the villages of Brancaster, Clenchwarton and West Walton providing Key Service Centre to the surrounding rural areas should be seriously considered: parts of these lie entirely within the Hazard Zone and climate change flood zones representing high probability of flooding. Significant mitigation and investment might be required if these villages were to be considered for other reasons to continue to provide key services and for future development, to ensure those services are protected from potential flooding now and in the future.

Heacham and Terrington St Clement are also considered to be at a relatively high risk of flooding located in both present day and future predicted flood zones.

The villages considered most suitable in terms of flood risk, being located predominantly in flood zone 1 based on the Level 1 SFRA flood maps, are listed below: -

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• Dersingham;

• East Rudham;

• Gayton / Grimston / Pott Row;

• Marham;

• Methwold / Northwold;

• Castle Acre;

• Feltwell / Hockwold Cum Wilton;

• Docking;

• Great Massingham;

• Snettisham.

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6. The Lynn South Expansion Area

The current Local Plan includes proposals for large scale provision of housing and employment land south of Kings’ Lynn within the Lynn South Expansion Area:

• Saddlebow Estate West (50ha employment land);

• White House Farm (55ha employment land);

• Lynn (South) (30ha residential land);

• Lynn (South East) (24ha residential land).

The Council requested that a specific task in the SFRA should be to review the flood risks specific to this area.

This section reviews flood risks to these four allocations based on the Level 1 flood mapping and impacts of climate change.

6.1 Present Day Flood Risks

The Level 1 SFRA flood maps for the present day (2008) have been used to overlay the present day fluvial and tidal flood risks onto the four allocations that form the Lynn South Expansion Area. Table 6.1 presents a summary of the flood risks to each site.

Table 6.1 Summary of Present Day Flood Risks

Allocation Flood Risks from present day sources

Lynn (South) Most of the site is located in Fluvial Flood Zone 2 (medium probability of 0.1% annual flood risk), from Nar Valley and local drainage channels; Low risk of tidal flooding (Flood Zone 1).

Lynn (South East) Fluvial flood zone 1 (low probability of less than 0.1% flood risk); Low risk of tidal flooding (Flood Zone 1).

Saddlebow Estate Fluvial flood zone 1 (low probability of less than 0.1% flood risk); West Low risk of tidal flooding (Flood Zone 1).

White House Farm Entire site located in Fluvial Flood Zone 2 (medium probability of 0.1% annual flood risk), from Nar Valley and local drainage channels; Low risk of tidal flooding (Flood Zone 1).

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6.2 Future Flood Risks

The Level 1 SFRA flood maps that include the impacts of climate change for the year 2115 have been used to overlay the likely future fluvial and tidal flood risks onto the four allocations that form the Lynn South Expansion Area. Table 6.2 presents a summary of the future flood risks to each site.

With regard to fluvial flood risks, the Level 1 SFRA has only mapped the impacts of climate change on the highest probability flood event (Flood Zone 3, 1% annual probability of flooding).

Table 6.2 Summary of Future Flood Risks

Allocation Flood Risks taking account of Climate Change

Lynn (South) More than half of the site is located in Fluvial Flood Zone 3a, from Nar Valley and local drainage channels Low risk of tidal flooding (Flood Zone 1).

Lynn (South East) Fluvial flood zone 1 (low probability of less than 0.1% flood risk); Low risk of tidal flooding (Flood Zone 1).

Saddlebow Estate Fluvial flood zone 1 (low probability of less than 0.1% flood risk); West Approximately half of the site is located in Tidal Flood Zone 2 and 3 (high probability of 0.5% annual chance of flooding occurring), from the Tidal Great Ouse.

White House Farm Approximately half of the site is located in Fluvial Flood Zone 3a, from Nar Valley and local drainage channels; Approximately half of the site is located in Tidal Flood Zone 2 and 3 (high probability of 0.5% annual chance of flooding occurring), from the Tidal Great Ouse.

6.3 Suitable Development

PPS25 sets out the requirements for consideration of flood risk during each stage of the planning process. The Sequential Approach aims to steer development away from areas of high flood risk, and to prevent increased flood risk in other areas of the catchment as a result of increased runoff or impediment of flood water from new developments. Developments are classified according to their vulnerability which is used to determine the compatibility of the development type against the existing Flood Zone.

According to PPS25, residential development is classified as being ‘more vulnerable’ to flood risks. Buildings used for: shops; financial, professional and other services; restaurants and cafes; hot food takeaways; offices; general industry; storage and distribution; and assembly and leisure are classified as being ‘less vulnerable’.

The majority of the Lynn (South) and Lynn (South East) will therefore be classified as ‘more vulnerable’, with the retail services being classified as ‘less vulnerable’. The land uses proposed for the Saddlebow Estate and White House Farm sites will be classified as ‘less vulnerable’.

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Table 6.3 reproduces Table D.3 form PPS25, which defines the suitability of development based on the vulnerability classification and flood zone location. For development in the Borough, the joint protocol (http://www.west- norfolk.gov.uk/pdf/Strategic%20Flood%20Risk%20Assessment%20KingsLynn%20Protocol.pdf) advises that the Level 1 SFRA climate change maps should be used to apply this sequential approach.

Table 6.3 Flood Risk Vulnerability and Flood Zone ‘Compatibility’ (PPS25 Table D.3)

Employment uses for business, general industry and storage and distribution on the Saddlebow and White House Farm sites would be considered compatible with the flood zones, being less vulnerable to flood risk and located in Flood Zone 2 and 3. The functional floodplain refers to fluvial floodplain that flood regularly. This zone is not mapped on any of the four allocated sites for the Lynn South Expansion Area.

Residential development on the Lynn (South East) site would also be a compatible land use for the level of flood risk. It is classified as more vulnerable and is located in Flood Zone 1. N.B. The Core Strategy identifies this current allocation, together with land extending southwards, to be a suitable direction of growth for urban expansion both within and beyond the plan period.

For residential development to be permitted on the Lynn (South) allocation, an exception test would need to be passed. This is because more vulnerable development types are not suited to high flood risk areas. The exception test would need to demonstrate that:

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a) The development provides wider sustainability benefits to the community that outweigh flood risk, informed by a SFRA where one has been prepared. If the DPD has reached the ‘submission’ stage 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 Flood Risk Assessment must demonstrate that the development will be safe, without increasing flood risk elsewhere, and, where possible, will reduce flood risk overall. The Core Strategy Proposed submission DPD promotes regeneration of King’s Lynn (notably including the Nar Ouse Regeneration Area and the Waterfront Regeneration Area) together with urban expansion of the town into three separate areas each determined to be at low risk of flooding (Zone 1). These broad locations are west of South Wootton/north of A1078 near North Lynn employment area; east of South Wootton/ on land bounded by A148 and A149 Knight’s Hill roundabout ; and land north and south of the original Lynn (South East) allocation. The latter location is likely to provide sufficient land to supplement long-term demand beyond the current plan period within the lowest risk zone of flooding, Zone 1. Consequently, future promotion of residential development on land at risk of flooding within the Lynn South Expansion Area cannot now be considered to meet the sequential test. This is a necessary pre-cursor to consideration of the exception test.

Large scale housing development on land determined to be at flood risk fails to support Objective 11 of the Core Strategy Sustainability Appraisal – to “Limit or reduce vulnerability to the effects of climate change (including flooding)”. Retention of the Local Plan allocation of the Lynn South expansion area therefore fails to meet test (a).

Much of the land allocated in the Lynn South area is for residential development on greenfield land in high risk flood zones. As demonstrated above, there are reasonable alternative sites available including previously developed land within the regeneration areas and greenfield land not at flood-risk. Retention of the Local Plan allocation for development in this area therefore fails to meet test (b).

Furthermore, if residential development is required on the Lynn (South) site then land may need to be raised to ensure that floor levels are higher than anticipated flood levels. This would potentially increase flood risk elsewhere by reducing the floodplain volume on the site and forcing floodwater to occupy areas outside of the site. To prevent increased flood risk elsewhere, compensatory floodplain storage would have to be provided by the developer. Retention of the Local Plan allocation therefore fails to meet test (c).

It is recommended that a more suitable land use is proposed for the Lynn (South) site that falls into the classification of less vulnerable or water compatible. These land use types are listed in Table 6.4 below.

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Table 6.4 Land uses suitable under PPS25 for Lynn (South)

Classification Land Uses

Less Vulnerable • 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).

Water Compatible • 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); • Lifeguard and coastguard stations; • Amenity open space, nature conservation and biodiversity, outdoor sports and recreation and essential facilities such as changing rooms; • Essential ancillary sleeping or residential accommodation for staff required by uses in this category, subject to a specific warning and evacuation plan.

559000 560000 561000 562000 563000 564000 565000 566000 Key:

SouthLynnHousing

SouthLynnEmpolyment

Fluvial Flood Zone 3 320000 320000 N Tidal Flood Zone 3

Tidal Flood Zone 2 Flood Zones include predicted impacts of climate change up to the year 2115 319000 319000 318000 318000 Saddlebow Estate

White Horse Farm Lynn (South East) Lynn (South) 317000 317000

0 500 1,000 Meters Scale: 1:10,000 @ A4

\Project pathname King's Lynn and West Norfolk 316000 316000 Level 2 Strategic Flood Risk Assessment

Figure 6.1 Flood Risks to South Lynn Expansion Area 315000 315000

December 2009 26655-b006 fiell 559000 560000 561000 562000 563000 564000 565000 566000 Based upon the Ordnance Survey Map with the permission of the Controller of Her Majesty's Stationery Office. © Crown Copyright. AL100001776

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7. Flood Defences Policy and Maintenance

The borough is protected from a range of flooding events through flood defences. These comprise a range of measures including man-made earth embankments, revetments, reinforced dunes, sea walls, groynes, flood relief channels and raised tidal defences and channel sides. In general it is the responsibility of the Environment Agency to ensure these defences are well maintained and operational to their designed standard of protection; however they may choose to exercise permissive powers to maintain and operate flood defences.

Furthermore, the Environment Agency has prepared draft Shoreline Management Plans and the Great Ouse Catchment Flood Management Plan as a means of creating policy for flood and erosion risk management to enable appropriate future development. These plans are currently published for consultation. This chapter therefore summarises the propose draft policies and actions to provide an overarching context of the Agency’s plans for flood risk management in the Borough. It should be noted that these are not the final plans.

Under the Catchment Flood Management Plan recommendations, the draft Great Ouse Tidal Strategy has also recently been published for consultation. A summary of this strategy is provided at section 7.2

The regular maintenance procedures for the existing defences are also presented.

7.1 Shoreline Management Plans

A Shoreline Management Plan (SMP) is a large-scale assessment of the risks associated with coastal processes, which include tidal patterns, wave height, wave direction and sediment movement. The plans are prepared by the Environment Agency and aim to help reduce these risks to people and the developed, historic and natural environments. The coastline is continually changing as a result of natural processes, but human activity and development in coastal areas can also affect the coastline and its processes.

The first Shoreline Management Plans (SMPs) were produced in the mid 1990s. However, following more recent studies including the UK Climate Impacts Programme, Catchment Flood Management Plans and Strategic Flood Risk Assessments, new information has become available. The Environment Agency is in the process of preparing the second generation Shoreline Management Plans (SMP2s) to take account of these studies and issues such as:

• Predictions of sea level rise due to climate change;

• Review of the lifetime of current defences; and

• Potential changes in the shoreline necessary to manage future risks.

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Current coastal management objectives are often widely accepted and embedded in local planning policy. Therefore, wholesale changes to existing flood and erosion defence management practices may not always be appropriate in the very short term, and communities, businesses and wildlife habitats all need time to adjust.

Consequently, the SMP2s will provide a ‘route map’ for local authorities and other decision makers to move from the present situation towards meeting future needs, and will identify the most sustainable approaches to managing the risks to the coast in the short term (0-20 years), medium term (20-50 years) and long term (50-100 years).

Within these timeframes, the SMP2s will also include an action plan that prioritises what work is needed to manage coastal processes into the future, and where it will happen. This in turn will form the basis for deciding and putting in place specific flood and erosion risk management schemes, coastal erosion monitoring and further research on how we can best adapt to change.

The SMP2s are currently out for consultation and summary consultation documents are available on the Agency’s website. The draft plans relevant to the Borough are discussed below.

7.1.1 The Draft Wash Shoreline Management Plan 2 (October 2009)

The Wash SMP is out for public consultation from Monday 12th October 2009 to Friday 15th January 2010 and the final version is due for publication in Spring 2010. The geographical extent of the plan stretched from Gibraltar Point in Lincolnshire to Old Hunstanton in West Norfolk.

Processes operating in The Wash are explained in the SMP. Tidal processes dominate the processes at the largest scale, which result in the formation of mudflats and salt marshes at the shoreline and sand banks in the middle of The Wash. Along the eastern section of the area from King’s Lynn to Hunstanton, land use is dominated by tourism, with shingle ridges and sea banks forming the sea defence rising to the cliffs at Hunstanton.

Policy Development Zones are used to divide the area according to medium scale coastal processes operating. The Borough council is located within all four zones identified. A summary of the management issues for each zone, and the geographic area affected in the Borough are presented in Table 7.1 below.

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Table 7.1 Summary of Issues from The Wash SMP

Policy Geographic Summary of Issues Development Area within Zone Borough

1 River Nene to Issues Wolferton Creek Managing tidal flood risk is an essential part of shoreline management planning. Sea level rise and potential loss of foreshore will increase pressure on sea defences. Realignment of defences would come at the cost of valuable agricultural land, but would create intertidal habitats and sustainable management of flood risk. Even with sea level rise, foreshore might not be lost. A balance between maintaining existing defences or realignment must be considered. Plans - sustain flood defence for the communities and their hinterland in the low-lying areas around the Wash. This includes an increase of management as required to sustain the current level of flood risk in the face of climate change. Short term – maintain existing sea bank alignments. Medium term – maintain existing alignment but consider landward realignment. Monitoring and research required.

2 Wolferton Creek Issues to South Beyond the short term, maintaining the shingle ridge as a frontline defence may not be affordable, Hunstanton (to environmental impacts might be unacceptable and there is already significant risk to people and approximately properties immediately behind the defence. Aquarium location) Changes to the shoreline may adversely affect saline lagoons in this area. Further investigation is needed outside the realm of the SMP, which should involve partner organisations and stakeholders. Plans - jointly develop a sustainable long-term solution by establishing a process of co- operation between the partner organisations and all people and businesses with an interest in the area. Short term - Continue to maintain shingle ridge. Long term – Adaptation. Potential relocation of facilities out of the flood zone, taking into account the impacts on tourism. Combination of flood defences, incident management and land use changes likely.

3 Hunstanton Town Issues (Aquarium to Continued defence against erosion on the seafront is needed to support the tourism industry and the Sensory Park) town’s role as a regional centre. Plans - sustain the viability of Hunstanton Town as a tourist resort and regional commercial centre. The policy to achieve this intent is to hold the shoreline defences in their current alignment. Short term – maintain defences. Long term – maintain defences but review plan if location becomes unsustainable with climate change.

4 Hunstanton Cliffs Issues (Sensory Park to Currently undefended. Old Hunstanton) Erosion of the cliffs is an important issue that required further consideration. Plans – allow natural cliff erosion until cliff top properties are threatened. Prevent further cliff erosion from this point forward. Short and long term – improve knowledge of processes.

Short term (now – 2025), Medium Term (2026 - 2055), Long Term (2056 - 2105)

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7.1.2 Draft North Norfolk Shoreline Management Plan (July 2009)

The North Norfolk SMP consultation period closed on 13th November 2009. The geographical extent of the plan covers the coastline from Old Hunstanton in West Norfolk to Kelling Hard in North Norfolk. This part of the coastline comprises sand dunes and embankments, with grazing marsh and reedbeds behind. Undefended higher ground along the coasts comprises agricultural land, spits and shingle reefs, slat marshes and barrier islands.

A summary of the management issues for each Policy Development Zone relevant to the Borough of King’s Lynn and West Norfolk are presented in Table 7.2 below.

Table 7.2 Summary of Issues from North Norfolk SMP

Policy Geographic Summary of Issues Development Area within Zone Borough

1A Old Hunstanton Plans – maintain defence function of dunes. Allow natural development of dunes. Dunes Short term – maintain defences from dunes. Medium to long term – Natural development of dunes. Restore level of defence is required.

1B Holme Dunes Plans – maintain defence function of dunes through continued minimum intervention. Short to long term – managed realignment to maintain defences if required.

1C Thornham Sea Plans – Maintain flood defences and realignment of sea bank if required. Bank Short term – Maintain defences. Investigate future realignment options in detailed study. Medium term – Construct new defences if required and increase tidal exchange. Long term – Maintain new line of defence.

1D Thornham Plans – Stop maintenance of defence and allow gradual change to intertidal habitat. Short to Long term – No maintenance of defences but sustain footpath during natural development of coastal landscape. Consider need for local adaptation in long term.

2A Thornham to Plans – Continued natural development. Titchwell Short to long term – No intervention with coastal development.

2B Titchwell RSPB Plans – Continued management of realignment and private maintenance of defence line. reserve Short to long term - No intervention with coastal development.

2C Titchwell village Plans – Continued natural development. Short to long term – No intervention with coastal development.

2D Reclaimed grazing Plans – increase tidal exchange. marsh at Short term – Maintain defences. Investigate future realignment options in detailed study. Brancaster Medium term – If required in study, remove defences to allow tidal exchange. Long term – Allow natural development of coastline.

Short term (now – 2025), Medium Term (2026 - 2055), Long Term (2056 - 2105)

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7.2 The Great Ouse Tidal River Strategy (Draft for Consultation September 2009)

The Environment Agency has prepared this document setting out their plan for sustainable management of flood risk over the nest 100 years for the area between Earith and King’s Lynn and between Wisbech and Ely. The document is currently out for consultation until December 7th 2009.

The study area includes the man made Bedford Rivers, which encompass the Ouse Washes, and area 20 miles long by one mile wide designed as a flood storage reservoir and to improve drainage. The Ouse Washes is drained by the Great Ouse Tidal River. Water levels are controlled mainly through the sluice gates at the Denver Complex. A Flood Relief Channel also operates to convey high river flows away from the area south of the Ouse Washes, however this has also lead to higher silt levels in the Tidal River.

Through engagement with external stakeholders, the Agency has reviewed options for flood risk management within the study area. The preferred strategy put forward in the draft document is summarised below:

• Maximise flows through Denver Sluice to flush out silt in the Tidal River;

• Maintain and construct erosion protection measures;

• Revise operations of Earith Sluice;

• Replace crest walls on top of embankments in 2035;

• Raise the South Level Barrier Bank when the level of protection falls below 1 in 20 years (expected around the year 2080);

• Raise the West Bank defences of the Tidal River between Old Bedford Sluice and St Germans pumping station when the level of protection falls below 1 in 100 years (expected around the year 2080);

• Raise the East Bank defences of the Tidal River between Wiggenhall St Peter and Saddlebow when the level of protection falls below 1 in 75 years (expected around the year 2100); and

• Continued monitoring to gauge the impact of lowering bed levels and improving drainage of Ouse Washes.

The Agency has estimated that the standard of protection provided by the East Banks of the Tidal River between Wiggenhall St Peters and Downham Market will be lowest reducing to 1 in 90 until around 2085. The standard of protection provided by the South Level Barrier Bank may drop to as low as 1 in 20 by 2080, but the EA has stated they will carry out bank raising work to ensure that the standard does not fall below 1 in 20.

It is also proposed to continue with the existing management activities:

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• Improving the flood warning service and promoting its wider use;

• Channel maintenance, where necessary;

• Maintaining existing flood defences;

• Continuing to influence planning and development proposals; and

• Continuing to provide advice on protecting individual properties to increase their resistance to flooding.

7.3 Catchment Flood Management

The Environment Agency has produced Catchment Flood Management Plans across England and Wales in order to provide a high-level strategic planning tool which sets out the long term investment on sustainable flood risk management for the next 50 to 100 years. The Borough of King’s Lynn and West Norfolk is covered by the Great Ouse CFMP.

In the document, the policy approach for King’s Lynn, West Lynn, Downham Market and North Runcton is to take further action to reduce flood risk (now and in the future).

For smaller watercourses where flood risk management actions can be reduced, the policy is to reduce existing flood risk management actions, accepting that flood risk will increase in time.

Where there is opportunity to use areas as active floodplain, the policy approach is to take action to increase the frequency of flooding to achieve benefits locally or elsewhere, which may lead to an overall reduction in flood risk.

The Catchment Flood Management Plan has also proposed a number of actions on further studies required, who is the responsible party and the timeframe for delivery. The proposed actions for the North West Norfolk Rivers unit in which the Borough lies are presented in Table 7.3 below.

Table 7.3 Proposed Actions from Great Ouse Catchment Flood Management Plan

Action proposed Lead Partner Timescale Priority

The Tidal Great Ouse flood risk management study - To Environment Agency's National 2006 - 2008 High continue to develop this study and implement its outputs. Capital Programme Management Service.

Asset System Management Plan - A detailed plan of works Environment Agency Asset System 2008 - 2010 Medium to continue with our existing or alternative actions to manage Management Team (North). flood risk at the current level.

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Table 7.3 (continued) Proposed Actions from Great Ouse Catchment Flood Management Plan

Action proposed Lead Partner Timescale Priority

Asset System Management Plan - This plan should identify Environment Agency Asset System 2008 - 2010 Medium specific locations where we can reduce our existing flood Management Team (North). risk management actions.

King’s Lynn and North Runcton flood risk management study Environment Agency Strategic and 2012 - 2014 High - This study should identify what further actions can be taken Development Planning Team. to manage flood risk at King’s Lynn and North Runcton.

Downham Market flood risk management study - This study Environment Agency Strategic and 2012 - 2014 Medium should identify what further actions and can be taken to Development Planning Team. manage flood risk at Downham Market.

7.4 Flood Defence Maintenance Regime

The Environment Agency was contacted to request information on their maintenance regime on the existing defences in the Borough. The information below has been provided by the Operations Delivery Team Leader:-

“All flood gates have a monthly minor maintenance check. This comprises of oil/greasing components, seal checks, minor painting, checks for vehicle damage and obstructions to closure.

A six monthly more detailed inspection is carried out by the Maintenance and Engineering team from Ely and normally entails a full closure and checks on major components.

A high risk defence asset all the fixed concrete, wall defences and embankments have a six monthly inspection by Asset System Management inspectors as part of their asset inspection programme. They review the integrity, movement, joints and damage of these assets and raise work requests if anything is found. This is also the route for requesting more detailed inspections by engineers if concerns are raised about any aspect.”

Entec has also been advised by the Environment Agency that a review of the strategy for the Heacham to Hunstanton Defences is due to commence in 2010 (after the finalisation of the Shoreline Management Plan), and a review of the King's Lynn Defences is also due in the financial year 2011/12.

It is advised that the Borough Council and the Environment Agency set up a formal arrangement to keep up to date with flood defence maintenance and management, taking account of the policies and emerging strategies from the Catchment Flood Management Plans and Shoreline Management Plans. This could through quarterly email alerts and / or forums, reporting on maintenance activities undertaken, issues that need addressing and investment needs.

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8. Sustainable Drainage

8.1 Introduction

The benefits of using sustainable drainage systems (SuD) over traditional piped sewer systems are discussed in Chapter 7 of the Phase 1 King’s Lynn and West Norfolk Borough Council Water Cycle Study (Entec 2009): they are designed to reduce the potential impact of new and existing development with respect to surface water drainage discharges by using more natural processes to convey surface water away from development. SuDS are often described in a ‘management train’, a series of progressively larger scale practices to manage runoff and control water quality. The management train is:

• Prevention: application at individual sites, e.g. use of rainwater harvesting;

• Source control: control of runoff at or very near to its source;

• Site control: management of water in a local area or site; and

• Regional control: management of runoff from a site or number of sites.

As well as controlling run-off rates and flood risk, use of SuDS also contribute to reduction of pollution, increased amenity value and protection of water resources from point pollution. SuDS are considered to be a philosophy whereby natural systems can attenuate, infiltrate or allow both processes to control surface water run-off. Examples of SuDS techniques are presented in Table 8.1 below.

Table 8.1 Examples of SuDS Techniques

Technique Attenuation/ Description Example Infiltration

Filter strips Both These are wide, gently sloping vegetated strips of land designed to accept runoff as overland sheet flow from upstream development. They lie between a hard-surfaced area and a receiving stream, surface water collection, treatment or disposal system. They treat runoff by vegetative filtering, and promote settlement of particulate pollutants and infiltration.

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Table 8.1 (continued) Examples of SuDS Techniques

Technique Attenuation/ Description Example Infiltration

Constructed Attenuation Wetlands provide both stormwater attenuation and treatment. They wetlands comprise shallow ponds and marshy areas, covered almost entirely in aquatic vegetation. Wetlands detain flows for an extended period to allow sediments to settle, and to remove contaminants by facilitating adhesion to vegetation and aerobic decomposition. They also provide significant ecological benefits.

Trenches Predominantly Trenches are shallow excavations filled with rubble or stone that Infiltration create temporary subsurface storage for either infiltration or filtration or stormwater runoff. Ideally they should receive lateral inflow from an adjacent impermeable surface, but point source inflows may be acceptable. Infiltration trenches allow water to exfiltrate into the surround soils from the bottom and sides of the trench. Filtration or filter trench can be used to filter and convey stormwater to downstream SUDS components.

Infiltration Both Infiltration basins are depressions in the surface that are designed basins to store runoff and infiltrate the water to the ground. They may also be landscaped to provide aesthetic and amenity value.

Detention Attenuation Detention basins are surface storage basins or facilities that Basins provide flow control through attenuation of stormwater runoff. They also facilitate some settling of particulate pollutants. They are normally dry, though they may have small permanent pools at the inlet or outlet.

Swales Attenuation Swales are broad, shallow vegetated channels in which surface water can be stored or conveyed. They can be designed to allow infiltration, where appropriate. They should promote low flow velocities to allow much of the suspended particulate load in the stormwater runoff to settle out, thus providing effective pollutant removal. Roadside swales can replace conventional gullies and drainage pipes.

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Table 8.1 (continued) Examples of SuDS Techniques

Technique Attenuation/ Description Example Infiltration

Pervious Both Pervious pavements provide a pavement suitable for pedestrian Pavements and/or vehicular traffic, while allowing rainwater to infiltrate through the surface and into the underlying layers. The water is temporarily stored before infiltration to the ground, reuse, or discharge to a watercourse or other drainage system. Pavements with aggregate sub-bases can provide good water quality treatment.

Green roofs Attenuation Green roofs are systems which cover a buildings roof with vegetation. They are laid over a drainage layer, with other layers providing protection, waterproofing and insulation. They are a useful source control feature.

8.2 Adoption of SuDS

The issues and solutions facing the adoption and funding of SuDS techniques is also discussed in the Phase 1 Water Cycle Study (Entec 2009). A summary of the issues is presented below:

• Government thinking steers the implementation of SuDs through the planning process and advocates the grant of planning permission with or without a Section 106 of the Town and Country Planning Act 1990 as the vehicle for ensuring future maintenance and funding. The Town and Country Planning Act 1990 provides for financial payment to local authorities carrying out maintenance of SuDs systems and provision for a local authority to carry out maintenance work themselves if there is a breach of maintenance agreement;

• Recommendation 20 of the Pitt Review of the Summer 2007 floods (December 2008) was for the Government to resolve the issue of which organisations should be responsible for the ownership and maintenance of SuDS. The Government’s interim advice has been that local authorities should be responsible for adoption and maintenance. This was supported in the recently published draft Floods and Water Bill, which is currently under consultation;

• Where there is a requirement to implement SuDs, the local planning authority has two routes available to ensure that the SuDs are properly implemented and maintained. These are:

- Through an agreement under S106;

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- By a condition of planning permission.

• The S106 approach would be used if the development is large or the SuDs scheme complex. This route requires negotiations and legal preparatory work in advance of development, but offers more security as it may only be varied by agreement. It also allows for financial contributions in the form of a bond or a periodic payment.

8.3 Existing Drainage in the Borough of King’s Lynn and West Norfolk

Within the Borough of King’s Lynn and West Norfolk developments generally drain into conventional piped networks, either combined (foul and surface water) or surface water only (i.e. rainfall) although in some cases these discharge into Internal Drainage Board Drains and pumping is required to transfer the water to naturally draining rivers.

The Phase 1 Water Cycle Study has reviewed information provided by Anglian Water on potential capacity issues in the drainage and sewer network. The information provided indicates that a number of flooding incidents have been reported in King’s Lynn, Hunstanton and Downham Market, with the majority of the recorded incidents occurred in Kings Lynn. Furthermore the records show that almost all incidents were a result of blockages, highlighting the important of maintenance in drainage infrastructure management.

The Level 1 Strategic Flood Risk Assessment (Bullens, 2005 and Faber Maunsell 2008) identified that surface water was one of the key mechanisms of flooding in the study area, via:

• Exceedance of pumped drainage capacity in areas with no natural drainage;

• Overflowing of culverted watercourses in urban areas;

• Localised flooding due to overloading of the local surface water drainage system during storms;

• Localised flooding on urban areas due to flood locking.

Anglian Water is addressing these incidents as part of their maintenance and Asset Management planning. Any new development would need to ensure there is sufficient capacity in the existing systems and should limit the discharge into drainage networks through the use of sustainable drainage systems (SuDS) wherever possible.

8.4 Suitability of SuDS for Proposed Development

The Phase 2 Water Cycle Study for the Borough (Entec, ongoing) has reviewed the potential sites and growth areas put forward for development around the main settlements against potential SuDS techniques. The assessment is based on the underlying geology at each site, and forms a high level assessment of potential for infiltration. Infiltration techniques are usually the preferred form of SuDS for new developments where conditions allow as

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they encourage groundwater recharge and reduce the attenuation requirements by disposing of flows directly into the ground rather than discharging to a surface water sewer or watercourse.

It must be noted that each development put forward should carry out its own site specific assessment of SuDS suitability as local soil conditions and gradients form an important part of the decision process for the preferred SuDS solution. The following points should be noted when using infiltration based SuDS:

• Infiltration SuDS should not be used in areas where there are contaminated land due to the risk of pollution to the groundwater table;

• Care should be taken to ensure that pollutants are removed before entering the infiltration systems otherwise there is a risk that contaminants could enter the groundwater table; and

• Onsite testing should be undertaken at detailed design stage as per the requirements of BRE digest 365, Soakaway design. This will confirm the onsite infiltration rates, which will inform the design of the attenuation storage.

Infiltration of surface runoff from certain developments is restricted where there may be an unacceptable risk of contamination to an underlying aquifer, which is again a factor of the soil and geology types, and the water table depth. The location of a site within an area of high aquifer contamination potential does not necessarily preclude the use of infiltration SUDS, but suitable interceptors or treatment stages may need to be incorporated prior to infiltration.

King’s Lynn is mainly located on estuarine alluvial deposits although on the western side of the town there are areas of glacial till, raised beach deposits and river terrace deposits, which suggest little scope for infiltration SuDS techniques. As such, future development is going to need to rely on attenuation approaches, discharging to the existing system at controlled rates.

Source Protection Zones (SPZs) are located around major public water supply abstractions. Each abstraction has three zones associated with it and these have different requirements in terms of the quality of the water that can be discharged to them and consequently the types of development from which runoff may infiltrate. Table 8.1 shows the development types that are permissible in each zone and the techniques that will be required to control pollution before run off can be discharged based on the recommendations contained in CIRIA Report 156 Infiltration Techniques (1996).

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Table 8.2 Recommended Discharges for Source Protection Zones

Impermeable Area Zone I (Inner Zone) Zone II (Outer Zone) Zone III (Total Catchment)

Roof Drainage No objection (provided for No objection No objection sole use of roof drainage)

Public/Amenity Not acceptable Acceptable Acceptable

Large Car Parks Not acceptable Acceptable (with interceptor) Acceptable (with interceptor)

Lorry Parks Not acceptable Presumption Against Acceptable (with interceptor)

Garage Forecourts Not acceptable Presumption Against Acceptable (with interceptor)

Major Roads Not acceptable Presumption Against. Acceptable only if investigation favourable and Acceptable only in exceptional with adequate precautions circumstances

Industrial Sites Not acceptable Presumption Against Acceptable only if investigation favourable and with adequate precautions

Source: Table 4.9, CIRIA Report 156 Infiltration Drainage – Manual of Good Practice (CIRIA 1996)

Restrictions on infiltration SUDS are unlikely to form constraints on the strategic development, as there are no SPZs in the main settlements in the Borough.

8.5 Recommendations for Site-Specific Assessments

A FRA will be required where the proposed development or change of use to a more vulnerable class may be subject to surface water or other sources of flooding or where the Environment Agency and/or other bodies have indicated that there may be drainage problems. Developers should contact the relevant drainage authority to discuss if a FRA is required for new development. In addition, sites greater than 1 ha will be required to produce a Drainage Assessment, showing calculations of the required attenuation storage, and details of how and when these requirements will be met within the design and construction of the development. These need to be agreed and approved by the relevant drainage authority i.e. the Internal Drainage Board, the EA or Anglian water. To conform to the requirements of PPS25, drainage strategies should follow the approach within the document ‘Preliminary rainfall runoff management for developments’. The CIRIA report C635 – ‘Designing for Exceedance’ provides detailed guidance for engineers and planners on the design of urban surface water management systems to mitigate the impacts of these systems being overwhelmed during extreme rainfall events.

8.6 Recommendations for Surface Water Management Plans

The Phase 1 Water Cycle Study presented information relating to critical drainage issues from Anglian Water records of sewer flooding incidents, representing areas where capacities of the sewers have been exceeded. As discussed above and in the Phase 1 WCS report, Anglian Water is addressing these issues as part of their

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maintenance and AMP planning and it is recommended that all new developments investigate the use of SuDS to reduce surface water run-off.

As a result of the Pitt report, the government’s review of the Summer 2007 floods, funding has been made available for Council’s to prepare Surface Water Management Plans (SWMP) to address surface water flooding. Using a broad brush approach, the Environment Agency has mapped the potential susceptibility of urban settlements to surface water flooding. The top 77 urban settlements with the most properties potentially at risk have already been awarded funding and requested to prepare a SWMP. Other Councils wishing to prepare a SWMP have had to apply to Defra for a proportion of the remaining funds.

The aims of the SWMPs are to bring together the Council, the sewerage providers, Internal Drainage Boards, the Environment Agency and local community forums to review the flood risk in more detail and propose engineering solutions.

In light of the critical drainage issues identified by the Anglian Water sewer records, and also the added complexity of locked outfalls through flood defences in King’s Lynn as well as drainage managed by the Internal Drainage Boards, it is recommended that a SWMP is prepared and focuses on the settlements of King’s Lynn, Hunstanton and Downham Market. Within the urban area of King’s Lynn, the regeneration under the Growth Point status provides a good opportunity to review the surface water drainage systems and promote sustainable measures for both existing and future development. The scope of the SWMP would follow the most recent guidance which includes the four stages: Preparation; Risk Assessment; Options; Implementation and Review. Each stage would be iterative such that the scope of each stage should be confirmed with the steering group during the development of the plan. Nevertheless based on existing information it is viewed that a detailed assessment would be required to determine the causes and consequences of flooding and to test mitigation measures through modelling of surface and sub-surface drainage systems.

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9. Summary and Conclusions

A Level 1 Strategic Flood Risk Assessment was prepared for the Borough in 2005, and later updated in 2008. The assessment identified and mapped the areas of actual flood risk over the whole of the Borough. The modelling took into consideration the presence of flood defences and assessed overtopping leading to breaching of these defences when delineating the “actual” flood risk zones. This Annex report uses the outputs of the refined flood zone modelling to recommend policies for sustainable development in the Borough.

The East of England Plan policies identify the town of King’s Lynn as a key centre for development and change, for achieving sustainable development through the concentration of new development in this location. Furthermore King's Lynn was designated a Growth Point by Communities and Local Government in October 2007 to support the housing and jobs required in the town and the wider area. The Council has a vision for regenerating the Borough of King’s Lynn and West Norfolk, and as part of that vision it is envisaged that the population of the urban area of King’s Lynn will grow from 41,500 to 50,000 people up to 2021 and will accommodate approximately 7,000 of the 15,800 new houses earmarked for the Borough.

Much of the development is proposed for previously developed brownfield land within the town of King’s Lynn, which in parts is at risk of flooding from both fluvial and tidal sources. In accordance with PPS25, development classified as ‘more vulnerable’ such as residential land use would not be considered compatible with Flood Zone 3.

This supplementary report has reviewed the regeneration objectives for the town of King’s Lynn. Although potentially at a high risk of flooding, the redevelopment of the urban area of King’s Lynn is necessary to deliver the wider sustainability objectives benefitting the local community and therefore could be considered to outweigh the risk of flooding. The developments will:

• Deliver the remediation of derelict and contaminated land;

• Provide homes for an increasing population;

• Improve social and environmental conditions for the local population;

• Enhance transport infrastructure and links; and

• Provide new jobs through attracting investment into the town by increasing retail and commercial floorspace.

Proposed developments that are ‘more vulnerable’ and located within Flood Zone 3 in the town of King’s Lynn will need to demonstrate that the development contributes to the regeneration objectives of the town. In reviewing the objectives and through the preparation of the Annex to the Level 1 SFRA, recommendations have been made to the Council for incorporation into the Core Strategy Proposed Submission Document. The proposed policies relevant to flood risk are presented in Box 2.

Creating the environment for business

Box 2 Proposed Core Strategy Submission Policies Relevant to Flood Risk

The proposed submission document of the Core Strategy states in its policy CS01, Spatial Strategy, that new development will be: Guided away from areas at risk of flooding now or in the future, however recognising development may be required within flood risk areas to deliver regeneration objectives within Kings Lynn and maintain the sustainability of local communities in rural areas. The proposed policy CS08 Sustainable Development states: The Council’s Strategic Flood Risk Assessment outlines potential flood risk throughout the Borough. In order to ensure future growth within the Borough is sustainable: - The findings of the Strategic Flood Risk Assessment will be used to guide planned growth and future developments away from areas of high flood risk; - The Council will work in conjunction with the Environment Agency and ensure that decisions take into account coastal flooding and climate change adaptation issues. The emerging Shoreline Management Plan will also serve to highlight the future needs and changes that may affect coastal communities arising from changes in climate. Policy CS01 acknowledges that some development may be required in flood risk areas to meet regeneration objectives and maintain the sustainability of local communities. Development proposals in high flood risk areas will need to demonstrate that: - The type of development is appropriate to the level of flood risk identified in the Strategic Flood Risk Assessment, or; - If the development vulnerability type is not compatible with the flood zone as set out in PPS25, proposals will need to demonstrate that the development contributes to the regeneration objectives of Kings Lynn or the wider sustainability needs of rural communities; - The development is on previously developed land, or where proposals are for development of greenfield sites, the development must demonstrate a contribution to the regeneration objectives of Kings Lynn or the wider sustainability needs of rural communities; - Flood risk is fully mitigated through appropriate design and engineering solutions.

A review has been undertaken of the villages proposed to provide Key Rural Service Centres, against the Level 1 SFRA flood zones. This review identified that in terms of flood risk the villages of Clenchwarton followed by the north of the joint Brancaster settlements (Brancaster, Brancaster Staithe and Burnham Deepdale) were at the greatest risk of tidal flooding. Taking into account climate change impacts on flood risk, it is recommended that future development is not encouraged in Clenchwarton and also to some degree in Terrington St Clement. Heacham is also considered to be at a relatively high risk of flooding located in both present day and future predicted flood zones. Proposed developments that are ‘more vulnerable’ and located within Flood Zone 3 in rural towns and villages will need to demonstrate that the development contributes to the wider sustainability needs of rural communities.

An overview of the suitability of development in the Lynn South Expansion area has identified that employment uses for business, general industry and storage and distribution on the Saddlebow and White House Farm sites would be considered compatible with the flood zones, being less vulnerable to flood risk and located in Flood Zone 2 and 3. Residential development on the Lynn (South East) site would also be a compatible land use for the level of flood risk. Residential development is classified as more vulnerable and this site is located in Flood Zone 1. However, residential development should not be permitted on the Lynn (South) allocation, as a result of the high flood risk, being located in Fluvial Flood Zone 3. Only if the development can pass all three parts of the Exception Test is it likely to be permitted. It is advised that this site is considered for Less Vulnerable development only.

The benefit of Sustainable Drainage Systems is discussed, and it is recommended that all new developments should implement SuDS to reduce the risk of surface water flooding.

Creating the environment for business

10. References

Communities and Local Government, Planning Policy Statement 25: Development and Flood Risk

Entec UK Ltd, King’s Lynn and West Norfolk Borough Council Outline Water Cycle Study, December 2009

Environment Agency, North Norfolk Catchment Flood Management Plan, Summary of Scoping Report, December 2006

Environment Agency, Great Ouse Catchment Flood Management Plan, Summary of Draft Plan, February 2007

Environment Agency, North Norfolk Shoreline Management Plan, Non-technical summary of Draft SMP, July 2009

Environment Agency, The Great Ouse Tidal River Strategy, Draft for consultation, September 2009

Environment Agency, The Wash Shoreline Management Plan 2, Non-technical summary Draft for Public Consultation, October 2009, Gibraltar Point to Old Hunstanton

Faber Maunsell, Kings Lynn & West Norfolk Strategic Flood Risk Assessment (2007/8 Revision) Final Report, December 2008