Liverpool City Council

Strategic Flood Risk Assessment (SFRA)

January 2008

Contents

Section 1 – Introduction

Section 2 – Liverpool context

Section 3 – Policy context

Section 4 – Roles and responsibilities

Section 5 – Flood Risk Assessment - Background - Risk of flooding - Flood Defences - Residual Risk - Extreme Events and Climate Change

Section 6 - Spatial Development and Flood Risk

Section 7 - Summary and conclusions

Appendices

Appendix A – Methodology and sources of information Appendix B – Guidance for Developers and Development Control Appendix C – RSS and Core Strategy Issues and Options Appraisal

List of Figures Figure 1: Location map Figure 2: Flood Risk Vulnerability and Flood Zone ‘Compatibility’ (Table D.3 – PPS25) Figure 3: Liverpool Bay Shoreline Management Plan (SMP) - Sub Cell 11a - Great Ormes Head to Formby Point Figure 4: CFMP Boundaries Figure 5: Future boundary of SMP Figure 6: Roles and Responsibilities in flood risk - Liverpool Figure 7: Location of Low-Water in the Inner Mersey Estuary between 1956 and 1967 Figure 8: Flood Risk Zones for Mersey Estuary Catchment Figure 9: External DG5 for Mersey Estuary Catchment

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 1 -

List of Tables Table 1: Key features and actions proposed within Draft Mersey Estuary CFMP for Liverpool Table 2: River Alt and Crossens - assessment of flood risk to people and economic damages Table 3: Rivers and Ordinary watercourses within each catchment Table 4a: Summary of Culverts – information from 1989 study that matches with 1999 study Table 4b: Summary of Culverts – information from 1989 study that does not match with 1999 study Table 5: Tidal levels in Liverpool (Gladstone Dock) Table 6: Historical information for the Environment Agency Flood Risk Zones Table 7: Historical areas of flooding Table 8: Flood locations supplied by Highways Table 9: Condition of Culverts Table 10: Incidences of sewer flooding Table 11: Risk of flooding to and from adjoining authorities

List of Maps Map 1: Natural features – topography and watercourses Map 2a: Watercourses – main rivers, canal and catchments Map 2b: Watercourses – main rivers and ordinary watercourses from 1989 Watercourse Flood Alleviation Study and catchments Map 2c: Watercourses – main rivers and ordinary watercourses from 1999 Culverted Watercourse Study Map 3: Culverts Map 4a: Environment Agency flood risk zones – tidal flood risk Map 4b: Environment Agency flood risk zones – tidal and river flood risk Map 5: Flood Risk Zone 3: Estimated functional floodplain (3b) and High Probability Area (3a) Map 6: Historical flooding areas Map 7: Condition of culverts – where information is available, the areas of poorest condition are identified Map 8: Historical sewer flooding Map 9: Summary of identified floodrisk Map 10: Risk of flooding in and from adjoining authorities Map 11: Flood Defences – e.g. river wall, Greenfield sites and open spaces, levees Map 12: Strategic development areas, UDP Allocations and Flood risk Map 13: Predicted Extreme Tide Levels in 2115 Map 14: Predicted Extreme River Levels (Flood Risk Zone 2)

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 2 -

1 Introduction

1.1 This SFRA (Strategic Flood Risk Assessment) has been carried out by Liverpool City Council Planning Policy Department in order to fulfil the requirement set out in Planning Policy Statement (PPS) 251. This document has been undertaken between June 2006 and January 2008.

1.2 The SFRA is a tool that plays an important role in delivering sustainable development for the City of Liverpool, taking account of flood risk issues and climate change. The main objectives of this SFRA are to:

• Identify land at risk of flooding in Liverpool and the degree of risk from river, sea and other sources • Reduce flood risk from and to new development through location, design and mitigation measures • Inform policy formulation and the Sustainability Appraisal for the emerging Local Development Framework concerning land use in flood risk areas • Provide a framework for development control officers and developers for dealing with the flood risk in development proposals

1.3 It is an important distinction that the function of the SFRA is to minimise the risk of flood to new developments and to reduce existing flood risks where possible. The risk of flooding to existing buildings is not within the remit of this assessment.

1.4 It is also important to note that this document is a strategic assessment. Detailed site specific flood risk assessments will still be required in line with PPS25. This assessment also highlights areas where further investigation may be required.

1.5 The role and responsibilities of different agencies concerning floodrisk is complex. This document has been undertaken by Liverpool City Council, but with the assistance of key partners including the Environment Agency, Liverpool 2020, United Utilities and Enterprise-Liverpool.

1.6 The structure of this SFRA builds up the picture of flood risk within Liverpool, starting with the Liverpool context, highlighting for example the need for urban renewal balanced with the need to address any identified flood risks. The policy context (section 3) sets out the main documents which influence the preparation of this SFRA and provides important background information. Due to the complexities of roles and responsibilities, there is also a summary flow chart which is designed to aid the development process, ensuring different agencies are aware of other agencies responsibilities.

1 Planning Policy Statement (PPS) 25 – Development and Floodrisk (2006) - DCLG

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 3 - 1.7 The key section of the document is section 5, the flood risk assessment. This provides basic background information, e.g. the locations of watercourses and culverts and then identifies where the key areas of flood risk are e.g. Environment Agency indicative flood risk maps and historical areas of flooding. This provides the basis in which to identify the level of flood risk in strategic areas (discussed in section 6) but also provides the background information for more detailed site specific flood risk assessments.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 4 - Figure 1: Location Map 2 Liverpool Context

2.1 Liverpool is located on the River Mersey in the North West of England. It covers an area of 112 square kilometres.

2.2 Liverpool is a predominantly Knowsley urban area, with a population of 444,500 (2004 population Sefton estimate). The City has seen St. Helens significant change over the past Liverpool century including a population decline from its peak in 1931 of 846,101 to the present day. Wirral Halton 2.3 The city has a history strongly linked with its river, the Mersey, providing an international seaport and maritime trade, between the 18th and 20th Century. However, the 1980s industrial crisis led to a severe economic decline within Liverpool, the legacy of which is still a major issue today.

2.4 Over the years, the City has mounted a succession of major housing regeneration and redevelopment programmes to address these problems, dealing variously with slum clearance and housing stock rehabilitation. Areas of the city are now designated as priorities for action under the government’s Housing Market Renewal Initiative (HMRI), which is a long-term programme to transform those inner city neighbourhoods dominated by unpopular housing through a comprehensive regeneration process, including housing redevelopment and refurbishment on a major scale.

2.5 Despite these issues, Liverpool is a regional centre for financial and professional services, retail provision, tourism, higher education, hi-tech industries, manufacturing and transportation. The Mersey Ports and Liverpool John Lennon Airport are key transport hubs and perform a central role in the City’s economy.

2.6 The City Council’s aim for the City is: "We aim to build and safeguard a fair, prosperous and open city where no-one is in poverty; where our citizens are well educated and take part in the decisions that affect them and where the cultural and religious differences between people are valued and celebrated." (2006)

2.7 This context demonstrates some of the key assets within Liverpool and the different pressures and issues that the City faces. Without an appropriate assessment of the potential risks of flooding, there is a danger that the success of the City and future developments will be jeopardized by flooding, causing far reaching damage to buildings, economy, image and people though loss of belongings and personal injury. Further detailed consideration of the level of flood risk in key development areas is provided in section 6.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 5 - 3 Policy Context

3.1 There are a variety of planning documents that provide a broad context to planning and floodrisk, as it is a key cross-cutting issue. Planning Policy Statement 1: Delivering Sustainable Development2, provides the overarching principles for the planning system refers to the need to avoid new developments in areas at risk of flooding and sea-level rise. In addition, other guidance relating to different types of development such as PPS3: Housing, PPS6: Planning for Town Centres and PPG4: Industrial, Commercial Development and Small Firms need to be taken into account. The Supplement to PPS1 on Climate Change3 also needs to be considered, particularly with regard to mitigation and adaptation.

3.2 A brief overview of the key policy documents that provide specific guidance relating to planning and floodrisk from a national through to local level are as follows:

National: Making Space for Water – DEFRA (2005)4 3.3 Making Space for Water is the Government’s strategy for flood and coastal erosion risk management in England. The key issues within this document are:

• To assess flood risk in the planning process • To involve people in the decision making process as well as in the prevention of and protection against risk • To have a holistic and global approach to the risk and to collect better data • To test and provide new tools to manage the risk • To be ready to change land use in order to manage the risk

Planning Policy Statement (PPS) 25 (2006): Development and Floodrisk 3.4 PPS25 was adopted in December 2006. It provides the guidance to ensure that floodrisk is taken into account at all stages of the planning process to avoid inappropriate development in areas at risk of flooding, and to direct development away from areas of highest risk.

3.5 PPS25 expects local authorities to apply a risk-based approach to the preparation of development plans and their decisions on development control through a sequential test.

3.6 The detailed provisions of the sequential test are essential to the consideration of planning applications and in determining allocations within the Local Development Framework and direct reference should be made to PPS 25 (Annex D, Table D.1).

2 Planning Policy Statement 1: Delivering Sustainable Development (ODPM) - 2005 3 Planning Policy Statement: Planning and Climate Change - Supplement to Planning Policy Statement 1 (DCLG) - 2007 4 Making Space for Water – DEFRA 2004/2005 http://www.defra.gov.uk/environ/fcd/policy/strategy/1stres.pdf

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 6 - 3.7 In brief, the flood risk zones range from zones 1 to 3. They refer to the probability of flooding from rivers, the sea and tidal sources and ignore the presence of existing defences because these can be breached, overtopped and may not be in existence in the lifetime of the development. The basic principles are that development should be steered towards flood risk zone 1. Where no reasonably available sites exist in Flood Zone 1, Flood Zone 2 can be considered and finally if no available sites are located in flood risk zone 1 and 2, should flood zone 3 be considered.

3.8 PPS25 also implements an ‘exception test’ approach to certain types of development within flood risk zones 2 and 3. The key principles of which are that: • The development provides wider sustainability benefits to the community that outweigh floodrisk • The development is on developable previously developed land or where there are no reasonable alternatives on developable previously developed land • A flood risk assessment demonstrates that the development will be safe, without increasing flood risk elsewhere and, where possible, will reduce flood risk overall

3.9 The Exception Test is only appropriate for use when there are large areas in Flood Zones 2 and 3, where the Sequential Test alone cannot deliver acceptable sites.

3.10 Different land uses are considered to be more appropriate in different flood risk areas. The types of development, their suitability and the need to apply the exception test is summarised within table D.3 of PPS25 and shown in figure 2 below:

Figure 2: Flood Risk Vulnerability and Flood Zone ‘Compatibility’ (Table D.3 – PPS25) Flood Risk Essential Water Highly More Less Land Use Infrastructure Compatible Vulnerable Vulnerable Vulnerable Vulnerability classification Zone 1 ! ! ! ! ! Zone 2 ! ! Exception ! ! Test Required Zone 3a Exception Test ! " Exception ! Required Test

Flood Zones Zones Flood Required Zone 3b Exception Test ! " " " Required

Key: ! Development is appropriate " Development should not be permitted

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 7 - 3.11 PPS 25 (Annex E) sets out the minimum requirements for flood risk assessments: • Consider risk of flooding both from and to a development • Consider the effects of parts of the flood risk management infrastructure including raised defences, flow channels, flood storage areas and other artificial features together with the consequences of their failure • Consider the vulnerability of those that could occupy the development, taking account of the sequential and exception tests and the vulnerability classification including safe access • Consider and quantify the different types of flooding and identify flood risk reduction measures so that assessments are fit for the purpose of the decisions being made. • Consider the effects of a range of flooding events including extreme events • Include an assessment of the remaining risk (residual) after risk reduction measures have been taken into account • Consider how the ability of water to soak into the ground may change with development, along with how the proposed layout of development may affect drainage systems • Consider the affects of climate change

Development and Floodrisk: A Practice Guide Companion to PPS25 ‘Living Draft’ - A Consultation Draft (February 2007) 3.12 A draft Practice Guide to the adopted PPS25 was published in February 2007 providing more detailed guidance for the implementation of PPS25.

3.13 The document focuses on the following aspects: • Further guidance for what PPS25 means for those responsible for preparing Regional Spatial Strategy, Local Development Documents and Sustainability Appraisal and for developers • Further guidance on undertaking Regional Flood Risk Appraisals (RFRA’s), Strategic Flood Risk Assessments (SFRA’s) such as this document and site- specific Flood Risk Assessments (FRA’s) • Further guidance on the application of the sequential approach and Exception Test • Further guidance on the planning implications of a range of measures for mitigating the adverse impacts of conventional drainage systems and provides an overview of the principles of sustainable drainage • Detailed guidance for risk management by design which looks at the individual site level and measures that can be implemented • Further guidance on some of the key residual risk issues

3.14 It should be noted that this SFRA was at a stage close to adoption on the publication on this practice guidance. This document has been used to check that this SFRA complies with the requirements set out within it. However it was not used as the starting point to the process.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 8 - Water Framework Directive 3.15 The WFD entered into force in December 2000 and was transposed into English and Welsh law in December 2003 as the Water Environment (Water Framework Directive) (England and Wales) Regulations 2003.

3.16 The main objectives of the Water Framework Directive are considered to be: • Enhance the status and prevent further deterioration of aquatic ecosystems and associated wetlands - there is a requirement for nearly all inland and coastal waters to achieve ‘good status’ by 2015 • Promote the sustainable use of water • Reduce pollution of water, especially by ‘priority’ and ‘priority hazardous’ substances • Lessen the effects of floods and droughts; • Rationalise and update existing water legislation and introduce a co- ordinated approach to water management based on the concept of river basin planning.

3.17 WFD demands that headline water issues such as the availability of water supplies, maintaining the quality of water in rivers and managing flood risk are considered as a whole rather than in isolation. Increased flood risk can have a significant impact on water quality with increased run-off reaching the watercourses.

3.18 There is also a need to have regard to the River Basin Management Plan (RBMP) for the North West, which is due to be adopted in 2009.

Regional: Adopted Regional Spatial Strategy (RSS) for the North West (2003) Draft Regional Spatial Strategy (RSS) for the North West (2006) 3.19 Adopted RSS for the North West sets out the regional approach within Policy ER8. It requires that the precautionary principle and sequential approach be applied, that inappropriate development in areas of floodrisk should be avoided and encourages the promotion of SuDS in all developments. It highlights the River Mersey network (i.e. the entire river system from the Mersey Estuary to confluence of Goyt and Tame Rivers at Stockport) as one of the areas at greatest risk within the region.

3.20 Guidance is provided within policy EM5 in the Draft RSS for the North West. This policy requires; • The implementation of “Meeting the Sequential Flood Risk Test – Guidelines for the North West Region5”, • Exceptional development that is allowed in flood risk zones be resilient to flooding, • New developments to incorporate SuDS; and • Awareness raising of flood issues.

5 Meeting the Sequential Flood Risk Test – Guidelines for the North West Region (2004) – EA and NWRA

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 9 - 3.21 Policy CZ2B in the Adopted RSS relates to Coastal Defences and the need for plans and policies to contain flood risk assessments in line with the Shoreline Management Plan, direct development away from areas of flood risk, coastal erosion and land instability and avoid development that prejudices existing coastal defences. The Draft RSS, policy EM6 relates to Managing the North West’s Coastline, which supports the Adopted RSS but also includes the need to consider the impacts of climate change.

3.22 An analysis of strategic policies and their impact on floodrisk is provided in Appendix C.

Sub Regional Liverpool Bay Shoreline Management Plan (1999): Sub Cell 11a – Great Ormes Head to Formby Point 3.23 The Liverpool Bay Shoreline Management Figure 3: Sub cell for Liverpool (11a) Plan is split into sub cells. The map in figure 3 shows the sub cell which relates to Liverpool (sub cell 11a).

3.24 The main objectives of the Shoreline Management Plan include enhancing and protecting the rural economy and the fishery industry, monitoring, enhancing the landscape quality and the management and maintenance of coastal defences. Where possible, these should be natural defences and should not have adverse impacts on industries, nature conservation and the historic environment.

3.25 The Shoreline Management Plan does not include any specific details that relate to Liverpool and that need to form the basis for any recommendations or further investigation within this SFRA. This SFRA should however be in line with the overall aims and objectives of the Plan. Work on a revised SMP is due Figure 4: CFMP Boundaries to commence in 2007.

Catchment Flood Management Plans 3.26 There are two catchment flood Alt and management plans (CFMPs) which are Crossens within the Liverpool City Council authority area. These are the Mersey catchments of the River Mersey and the Estuary River Alt. The following map (figure 4) provides an overview of these boundaries:

3.27 The Mersey Estuary Catchment Flood Management Plan is at the draft stage Reproduced from Mersey Estuary Draft Catchment Flood Management Plan (© Crown Copyright All rights reserved 100026380 Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 10 - (March 2007) and the River Alt and Crossens Catchment Flood Management Plan is at the scoping report stage (April 2007). These documents are key reference points for the Liverpool Strategic Flood Risk Assessment and it is important this SFRA is in conformity with these documents. Reference should also be made directly to these documents.

Mersey Estuary Draft Catchment Flood Management Plan (March 2007)6 3.28 The Draft Catchment Flood Management Plan provides an overview of the flood risk in the Mersey Estuary catchment and sets out the preferred plan for sustainable flood risk management over the next 50 – 100 years.

3.29 The aims of the Mersey Estuary Catchment Flood Management Plan are: • To reduce the risk of flooding and harm caused by floods to people, the natural, historic and built environment; • To maximise opportunities to work with nature and to bring about a range of benefits from flood risk management, and make an effective contribution to sustainable development; • To support the implementation of EU directives (Water Framework Directive and the forthcoming Floods Directive), meeting Government and other policies and targets, and our corporate vision; • To promote sustainable flood risk management; • To inform and support planning policies, statutory land use plans and implementation of the Water Framework Directive so that future development in the Mersey Estuary CFMP catchment is sustainable in terms of flood risk.

3.30 Within the revised Shoreline Management Plan (work on the revised document is expected to commence in 2007), the boundary is due to be amended. This will take the boundary of the Shoreline Management Plan further into the Mersey Estuary. This is demonstrated in figure 5. Figure 5: Future boundary of SMP 3.31 The draft report provides important background information about the catchment, such as topography, geology, hydrology and land use and land management (see summary in section 5, paragraph 5.10). The draft report also provides an overview of flood risk issues which are included within each relevant sub-section of section 5: Risk of Flooding.

3.32 The following table summarises the key features and actions proposed within the Draft Mersey Estuary Catchment Flood Management Plan for the Liverpool area (known as policy unit 11): Reproduced from Mersey Estuary Draft Catchment Flood Management Plan (© Crown Copyright. All rights reserved. 100026380, 2007) 6 Mersey Estuary Catchment Flood Management Plan (CFMP) – Consultation Draft, Environment Agency (March 2007) http://www.environment- agency.gov.uk/regions/northwest/1072087/1697828/?version=1&lang=_e

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 11 - Table 1: Key features and actions proposed within the Draft Mersey Estuary CFMP for Liverpool

Policy Unit 11 Liverpool: Covers the north Mersey Estuary component and includes the city of Liverpool Problem/risk There are approximately 373 properties and 28 commercial properties at risk of flooding with flood risk areas lying in the north of the unit and also near the waterfront. However, there is little history of flooding in this policy unit, and current flood risk management is thought to be appropriate in this heavily urbanised and industrialised unit. Policy Policy number 4 Take further action to sustain the current scale of flood risk into the future (responding to the potential increases in flood risk from urban development, land use change, and climate change). Justification There is a population of approximately 319,000 (approx. 22% of the whole catchment) in this policy unit. The current number of properties at risk for a baseline 100:1 (1%) chance event is approximately 500 (approx. 2% of the total number of properties at risk in the catchment for the same event). Currently, the estimated damages to residential properties in this policy unit are approximately £117M for a 10:1 (10%) chance event, 50:1 (2%) chance event and 100:1 (1%) chance event. Estimated damages for the latter event could increase by 18% and 77% by 2055 and 2105 respectively as a result of the impacts of climate change and any further development planned within the catchment. The current expected annual damages in this policy unit are approximately £12M /yr and amount to 5% of the total damages within the catchment. This policy is selected as flood defence assets are currently more than adequate for current flood risk, although flood risk at these locations may rise in the long- term due to climate change and any possible further development. Although there is a World Heritage Site within the unit, it is subject to a low risk of flooding with tidal issues covered by the SMP. Planned future developments within this policy unit are not extensive and involve development on existing brownfield sites. If development is necessary, flood risk areas should be avoided. There are no environmental designations within flood risk areas although it does border with a number of Mersey Estuary designations. No pollution inventory sites lie within flood risk areas. Maintaining current flood risk means an appropriate level of management is sufficient enough for the unit and adequate enough for tidal levels taking into account aforementioned features. Actions All identified actions in the action plan are considered to be ‘high’ priority – essential to achieve policy aim and has a large effect 11.1: Carry out existing level of maintenance in the short term. Undertaking detailed study to deliver plans such as System Asset Management Plans, Asset Replacement Programmes. Potential schemes will be identified through this process and will be implemented on a priority basis. All plans should seek to address gaps in knowledge. Completed set of System Asset Management Plans. 11.2: Development Control advice to ensure no increase in run-off from new developments and seek opportunities to reduce current run-off rates where possible. Develop integrated urban drainage strategy, implementation of SuDs where feasible. 11.3: Develop integrated urban drainage strategy, with review of receiving watercourses/ catchments, foul and surface water, and consider the effects of climate change. Develop integrated urban drainage strategy Risks, Future flooding risks (including climate change etc.) are an uncertainty. uncertainties SMP and CFMP need to be consistent to ensure no overlap or gaps in policy and dependencies

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 12 - River Alt and Crossens Catchment Flood Management Plan – Scoping Report (April 2007)7

3.33 The Alt-Crossens catchment lies within the administrative local authority areas of: • Liverpool City Council • Sefton Metropolitan Borough Council • Knowsley Borough Council • West Lancashire District Council • St. Helens Borough Council (only a minor part in the south-east)

3.34 The Draft report is due to be published in early 2008.

3.35 The main tributaries entering the River Alt within its upper reaches are: • Hall Brook in Croxteth Park • Sugar Brook, servicing a heavily urbanised area • Fazakerly Brook which serves the densely populated Tue Brook and Anfield areas of Liverpool • Tue Brook - substantially culverted • Deys Brook - substantially culverted • Thornhead Brook - substantially culverted • Knowsley Brook, primarily draining a largely rural area • Kirkby Brook, largely rural but provides drainage for the urban area of Kirkby. This part of the Alt catchment is historically termed the Upper Alt catchment, with its notional boundary at the Kirkby Gauging Station, the only flow monitoring location in the catchment.

3.36 The watercourses of the Alt and Crossens catchments have been modified considerably. The upper Alt catchment has been extensively urbanised, and many sections of the channel have been canalised or culverted. The lower Alt (downstream of Maghull) has been straightened and confined within flood embankments, significantly changing its character and disconnecting the channel from its natural floodplain. The changes to the River Alt have resulted in very flashy, rapid flows from the urban upper catchment but conveyance problems through the shallow-sloped lower reaches, where pumps are required to maintain flow movement through the channels.

3.37 The main areas identified to be at risk within the Alt catchment include: • Acre Lane Brook and Wham ditch, Formby • Kirkby Brook, Kirkby • Simonswood Brook, Kirkby • Whinney Brook, Maghull • Dovers Brook, Maghull • Breach of flood banks of Cheshire Lines, Lydiate

7 River Alt and Crossens Catchment Flood Management Plan (CFMP) – Scoping Report, Environment Agency (April 2007) http://www.environment- agency.gov.uk/regions/northwest/1072087/1697392/?version=1&lang=_e

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 13 - • Aintree • Deys Brook and Tue Brook, Liverpool The majority of flood risk within the urban areas is as a result of insufficient culvert or channel capacity and channel obstruction.

3.38 There is limited information regarding surface water flooding in the catchment. Based on the information available, the risk of flooding from surface water in individual flood risk areas within the catchment can be considered to be relatively high in frequency (i.e. approximately on an annual basis) but low consequence. The following table demonstrates the assessment of flood risk to people and economic damages:

Table 2: River Alt and Crossens assessment of flood risk to people and economic damages

Location (main No. of people Maximum Ranked risk to Current urban at risk* (1% water depth people economic conurbations) a.p. event) (m) (1% 1.p. damages event) (£000’s) Liverpool – West 358 0.63 Low 5,948 Derby Maghull 1165 1.45 High 35,122 Formby 10 0.75 Medium 56 Mere Brow 3 0.24 Unknown 200 * Assuming 2.5 people on average per property (UK Government Statistics)

Local:

Liverpool City Council – Contaminated Land Inspection Strategy (2002) 3.39 This document sets out the manner in which Liverpool City Council proposes to implement its inspection duties under Part IIA of the Environmental Protection Act 1990. It describes the framework within which potentially contaminated land will be identified and dealt with in a rational, ordered and efficient manner.

3.40 The links to flood risk are that areas of flooding are highlighted as potentially contaminated land. In addition increased levels of flooding can lead to increased contamination, through transporting pollutants during times of flood and generating the overflow of sewer systems.

Adopted Liverpool Unitary Development Plan (2002) Emerging Liverpool Local Development Framework (LDF) (ongoing) 3.41 The Adopted Unitary Development Plan (UDP) for Liverpool (2002) sets out the Council’s approach to flood prevention in Policy EP13. The policy states that unless appropriate alleviation or mitigation measures are carried out, planning permission will not be granted for development. This includes developments that would be at a direct unacceptable risk from flooding, be likely to increase the risk of flooding elsewhere and those that would result in an adverse impact on the water environment due to additional surface water runoff.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 14 - 3.42 The Adopted UDP also includes allocations of land for different types of development. A number of these have already been developed, but a large number remain unimplemented and may be brought forward under the UDP in the future. Each unimplemented site has been assessed for the level of identified flood risk and the approach that should be taken (see section 6 – paragraph 6.33 onwards).

3.43 Under the current planning system, Liverpool City Council is producing a Local Development Framework to replace the existing UDP. A Local Development Scheme8 (LDS) has been produced and is regularly updated. This contains details of the documents that are to be produced under the Local Development Framework and a timetable for their completion. Reference should be made to the LDS to determine what documents are to be produced when. This SFRA will inform the production of these documents.

3.44 Preparation of the Core Strategy (Development Plan Document – DPD) is underway. The key milestones in the production of a DPD is:

1. Pre- production/ scoping 2. Consultation on scoping report 3. Drafting of and Issues Options Paper 4. Consultation andon Issues Options Paper 5. Drafting of Preferred Options Report 6. Consultation on Preferred Options Report 7. Drafting of Submission DPD 8. Consultation submission on DPD 9. Examination 10. Adoption

3.45 An Issues and Options Paper9 for the Core Strategy has been published. The two issues and associated options for an appropriate policy approach to flood risk are:

Issue The Core Strategy should control development in identified areas of flood risk Option A The Core Strategy should include a prudent avoid all development in areas of flood risk Option B Development in areas of flood risk will be permitted providing measures are included that reduce the risk of flooding including consequential risks elsewhere

8 Local Development Scheme – Liverpool City Council: http://www.liverpool.gov.uk/Environment/Planning/Local_Development_Framework/adopted_ documents/Local_development_scheme/index.asp 9 Core Strategy Issues and Options Paper – Liverpool City Council (2006) http://www.liverpool.gov.uk/Environment/Planning/Local_Development_Framework/work_in_ progress/core_strategy_dpd/index.asp

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 15 -

Issue The Core Strategy should encourage drainage techniques that reduce the risk of flooding Option A The Core Strategy should encourage the use of Sustainable Urban Drainage Systems (SuDS) in all new development Option B Targets for new development incorporating SuDS, either by use (e.g. residential, commercial) or within particular parts of Liverpool, should be included within the Core Strategy

3.46 The next stage in the process is to publish a Preferred Options Report which provides more detail on the policy options. This stage also highlights a ‘preferred option’ based on the consultation responses to the Issues and Options Report, the findings from the Initial Sustainability Appraisal, national and regional guidance and any relevant evidence, such as this Strategic Flood Risk Assessment. An assessment of the findings of this SFRA against these issues and options is undertaken in Appendix C.

3.47 The Core Strategy should set out the key elements of the planning framework for the area and although this Strategic Flood Risk Assessment will feed into the Core Strategy, it may be of greater importance to the more detailed policies that are produced for example, through the Technical Policies Development Plan Document where sites will be allocated. When allocating sites, the level of flood risk in that area will be an important consideration.

3.48 More detailed policies will follow the Core Strategy through the production of: Land Allocations DPD, Technical Policies DPD, Joint Merseyside Waste DPD and a series of Area Action Plans. Work has commenced on the Joint Merseyside Waste DPD and the North Liverpool Area Action Plan. A series of Supplementary Planning Documents (SPD’s) have also been produced/ will be produced for which again, this SFRA will inform. Information regarding the documents published under the Local Development Framework can be found on the City Council website: www.liverpool.gov.uk/ldf

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 16 - 4 Roles and Responsibilities

4.1 There are a number of different individuals, bodies and agencies involved in flood risk and flood management, ranging from the individual property owner that is located in an area of flood risk to national government agencies that take a strategic role in flood risk management.

4.2 It is important in the context of this SFRA to determine the different roles and responsibilities to aid the development process with regards flood risk. The flow chart in figure 6 below summarises the different roles and responsibilities within Liverpool.

4.3 Annex H of PPS25 sets out in more detail these roles and responsibilities at a more general level.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 17 - Figure 6: Roles and Responsibilities in flood risk - Liverpool

ENVIRONMENT AGENCY - Flood management and funding HIGHWAYS DCLG flood defence works on main DEFRA AGENCY - Overall - Overall policy rivers - Power to maintain and improve - Managing road Responsibility for land responsibility for main rivers drainage from trunk use planning policy flood and coastal - Statutory consultee for planning roads (PPS 25) erosion risk - Information and advice to local authorities - Warning system for flood risk GOVERNMENT OFFICE FOR LIVERPOOL CITY COUNCIL (LCC) THE NORTH WEST - Development control (planning) – ensure new development is not at - Scrutinise planning risk of flooding or exacerbates existing issues policies including flood - Emergency planning risk policies - Highways Maintenance UNITED - Consider whether - Policy planning – LDF – provide framework for development control decisions applications should be UTILITIES - Where appropriate, to reduce flood risk from "ordinary watercourses" and called in (to Secretary - Sewers and water supply from land drainage problems of State) when EA have

- Surface water drainage objected where via adopted sewers

LANDOWNERS (riparian) - Landowners have the primary responsibility for draining their LIVERPOOL ENTERPRISE land and managing the flood risk issues associated with their - Drainage of non-main roads, ditches property (including the City Council where they own the land) and drains

LIVERPOOL 20/20 – Advisory role to Liverpool City Council - culverts on ordinary watercourses and flood defences (where applicable) on a contractual basis

DEVELOPERS – Implement requirements to: - prevent risk of flooding to development, - prevent increased risk of flooding to other areas, - ensure water and sewer supply are adequate, - manage surface water run-off, - implement SuDs etc.

INSURANCE COMPANIES – Development in areas at a significant risk of flooding may create problems with getting insurance which in turn creates problems with property buyers obtaining a mortgage. Responsibility for this can fall to the above agencies. The Association of British Insurers and the Council of Mortgage Lenders will comment on individual proposals on which the Environment Agency object and where there appears to be a high risk. The insurance industry may also make representations about proposals for the location of new development during plan preparation.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 18 - 5 Flood Risk Assessment

5.1 This section sets out the main body of the flood risk assessment, drawing together data from a variety of sources, illustrated by maps and associated descriptions. This information should form the starting point for a detailed flood risk assessment for site specific proposals and is the basis for the assessment provided in section 6, identifying specific risks within strategic sites.

5.2 The Practice Guidance to PPS25 states that: “In local authority areas where flooding is not a major issue and where development pressures are low, a less detailed approach will be required relative to that necessary in areas where there is high development pressure and flooding is a significant issue.”

5.3 This section relies on a desk-top analysis of information previously collected and reported in a variety of different documents and through consultations with different agencies and officers involved in the floodrisk process. The information used therefore varies in level of detail, accuracy and date and as such the source of data is shown where possible.

5.4 In considering the information available, the main point to remember is everywhere is potentially subject to flood risk. Nowhere is free of risk, but some areas are potentially at greater risk. The quality of data does not alter actual risk, but could affect the judgement about whether an area is at high risk or not. For that reason the SFRA takes a cautious approach to the use of data.

5.5 The section builds up the picture of floodrisk within Liverpool, starting with background information and then considering different factors such as culverts, the condition of culverts, historical flooding and flood defences.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 19 - 5.6 Background information

5.7 This section is split into the following sub-sections and maps, which should be viewed as part of this section:

• Natural Features o Map 1A and Map 1B: Natural features – topography and watercourses • Watercourses o Map 2a: watercourses – main rivers and canal o Map 2b: watercourses – main rivers and ordinary watercourses from 1989 Watercourse Flood Alleviation Study and catchments o Map 2c: watercourses – main rivers and ordinary watercourses from 1999 Culverted Watercourse Study • Culverts o Map 3: Culverts

Natural Features (Refer to Map 1A and Map 1B: Natural Features – topography and watercourses)

5.8 The open watercourses within Liverpool are predominantly on low-lying land. The city could be considered to be ‘divided’ between the waterfront which is a flat area lying between 7 and 11m of altitude and the area to the north-east, lying between 16 and 32 m of altitude. This is split by an inner area of land which has higher altitudes, reaching 63m in places. In simplistic terms, water should drain towards each of the watercourse catchments (see paragraph 5.20 below). However, the topography and hydrology of Liverpool is complex and their consequences on flood should be given further consideration.

5.9 Map 1B shows the topography to a much more detailed level than Map 1A as it uses LIDAR data (airborne mapping technique which uses a laser to measure the distance between the aircraft and the ground at 2 metre intervals) which was available specifically for the purposes of this Liverpool SFRA. However, the data does not cover the whole city and this distorts the data in certain areas. Map 1A should therefore be referred to for an overview of the topography.

5.10 The Mersey Estuary Catchment Management Plan (CFMP)10 provides an overview of the natural and physical characteristics of the River Mersey catchment. The following summarises some of the information provided within this document, specific to Liverpool: • Solid Geology – Liverpool is predominantly made up of Permian and Triassic sandstones (this is supported in the River Alt and Crossens Catchment Flood Management Plan which shows the majority of the Liverpool area as Permian and Triassic sandstones, undifferentiated, including Bunter and Keuper. Along an area of the River Alt within Liverpool there is shown to be ‘Lower Westphalian’ (mainly productive coal measures)). • Hydrogeology – the majority of Liverpool is considered to be an aquifer (underground layer of water-bearing permeable rock or unconsolidated

10 Mersey Estuary Catchment Flood Management Plan – Scoping Report – November (2005) and Mersey Estuary Catchment Flood Management Plan – Draft – March (2007)

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 20 - materials), with a series of groundwater contour lines and parts of Liverpool are considered to be ‘Special/source Protection Zones’ (Environment Agency) • Geomorphology – Below the Runcorn Gap, the estuary opens into a wide shallow basin which has extensive inter-tidal banks and large areas of salt marsh on its southern margin. The position of low water channels and the shape and height of the inter-tidal banks and flats has been variable. This is illustrated in figure 7 below. The long-term accumulation of sediment which has resulted from natural sediment deposition and the outer estuary channel has caused a reduction in the fluid volume of the estuary. A reduction in volume of 75 million cubic metres occurred between 1911 and 1961 despite removal by dredging of 200 million cubic metres of material. Downstream of the main basin, the estuary converges to form ‘The Narrows’. The morphology of this section of the estuary has been determined by the underlying geology forming a straight, narrow section which reaches depths of 30m and experiences strong tidal currents, preventing accumulation of sediments.

Figure 7: Location of Low-Water in the Inner Mersey Estuary between 1956 and 1967 (reproduced from the Dee and Mersey Estuaries – Environmental Background – August 1987 – University of Liverpool and the CFMP7)

Within the estuary, water floods rapidly upstream following the topography until the banks are covered. Ebb tides are slower and more variable in direction as water gradually drains off the inter-tidal banks. Current flows in the estuary and the nearshore region comprise two main components: tidal currents, which are generally predictable and associated with the tidal rise and fall, and residual (or non-tidal) currents including those driven by winds. The dominant currents are caused by the tide but other long-term water movements are significant in terms of sediment and pollution transport. From Speke to Hale there are low cliffs which rise to a height of about 15m. The river water reaches the cliffs at high tide levels and can suffer damage during storms. • Bathymetry (Variation of Estuary Depths) and sediments - the main features are the extensive inter-tidal sand banks and the deep channels carrying the main tidal flows of the estuary. Regular surveys are undertaken in the

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 21 - navigable reaches by the Mersey Docks and Harbour Company with results in the form of Admiralty Charts available on request. • Soil – Liverpool is shown to be predominantly diamicton. There are patches of sand predominantly to the southern tip and south of the city centre along the Mersey. There is a strip of clay, silt and sand around the River Mersey to the City Centre. From the River Mersey to the east of the local authority boundary, south of the city centre, there is a strip of a composite of several solid rock lithologies.

The whole Mersey Estuary CFMP area is almost entirely covered by small superficial deposits of glacial till with subordinate sands and gravels. More localised areas of alluvial and Aeolian (wind blown) deposits exist in significant thicknesses around the Mersey Estuary. These deposits tend to have a high porosity and high permeability which means that, apart from urban areas; runoff will be relatively low and soil infiltration relatively high. It should be noted that during a tidal flooding event, the soil types will have a negligible impact on the flooding of the low lying parts of the catchment.

Watercourses (Refer to Maps 2a – 2c: watercourses (main and ordinary watercourses, canal and catchments) Key sources of information for this section are: Watercourse Flood Alleviation Study (1989) and Culverted Watercourse Study (1999)

5.11 Main river – Main rivers are usually larger streams and rivers, but also include smaller watercourses of strategic drainage importance. Main rivers are designated by the Department for Environment, Food & Rural Affairs in England. The Environment Agency’s powers to carry out flood defence works apply to main rivers only.

5.12 The main rivers in Liverpool are (shown in dark blue on map 2a): • River Mersey/Mersey Estuary • River Alt • Deys Brook (partial) • Sugar Brook • Fazakerley Brook • Croxteth Brook • Knowsley Brook (located on the Liverpool/Knowsley boundary) • Netherley Brook • Halewood Brook • Childwall Brook (partial)

5.13 Ordinary watercourse – Ordinary watercourses refers to all other watercourses not designated as a main watercourse. They fall within a Local Authorities responsibility for strategic flood risk management, although private land owners along the watercourse will be responsible for their land.

5.14 Under the provisions of the Land Drainage Act 1991, the local (Land Drainage) Authority have exactly the same powers of carrying out and funding

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 22 - improvement works on ordinary watercourses, that the Agency has toward the main rivers.

5.15 A large proportion of the ordinary watercourses in Liverpool are culverted and it is therefore difficult to determine exactly where the watercourses are. The ordinary watercourses identified in the 1989 Watercourse Flood Alleviation Study differ from those identified as part of the 1999 Culverted Watercourse Study. The 1999 study is more up-to-date and considered to be more reliable, however both sources of information are shown on separate maps.

5.16 The ordinary watercourses identified in the 1989 Watercourse Flood Alleviation Study are (not all watercourses are named): (shown in light blue on map 2b): • Mab Lane Drain • Thornhead Brook • Hall Brook • Deys Brook (partial) • Upper and Lower Tue Brook • Becher’s Brook • Lower Brook • Upper Brook • Jordan River • Old Garston River • Oglet Brook • Childwall Brook (partial)

5.17 The ordinary watercourses identified in the 1999 Culverted Watercourse Study are: (shown in light blue on map 2c): • Mab Lane Drain • Thornhead Brook • Deys Brook (partial) • Upper and Lower Tue Brook • Upper Brook • Jordan River • Upper Jordan • Old Garston River • Oglet Brook • Childwall Brook (partial) • Lee Park • Allerton Brook • Forty Pits Drain • Stamfordham Drive Drain • Brunswick Street Drain • Wavertree Culvert

5.18 It should be noted that irrespective of whether it is a main or ordinary watercourse, the riparian landowner (any watercourse within or adjacent to the boundaries of your property) is ultimately responsible for the ownership and therefore maintenance and repair. This applies equally to culverted watercourses.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 23 -

5.19 Canal: The Leeds and Liverpool Canal is located to the north of the city and is shown on map 2a. Plans are underway to provide a link between the canal and Pier Head.

5.20 Catchment (can also be known as river drainage basin) – the area of land that drains into a particular watercourse. The 1989 Watercourse Flood Alleviation Study identifies three main catchments in Liverpool, referred to as North (River Alt catchment), South and West (Direct to Mersey Estuary) and East (Ditton Brook Catchment), shown in red on maps 2a to 2c. The rivers and ordinary watercourses which fall within each catchment are:

Table 3: Rivers and Ordinary watercourses within each catchment North (River Alt South and West (Direct East (Ditton Brook catchment) to Mersey Estuary) Catchment) River Alt Kirkdale Childwall Brook Mab Lane Drain Beacon’s Gutter Netherley Brook Thornhead Brook Pool River Halewood Brook Hall Brook The Mill Stream Deys Brook Dingle Drain Sugar Brook Dickinson’s Dingle Tue Brook Lower Brook Fazakerley Brook Upper Brook Croxteth Brook Jordan River Knowsley Brook Cressington Park Drain Becher’s Brook Old Garston River Speke Hall Drain Oglet Drain

For the remaining maps, the ordinary watercourses identified in the 1999 Culverted watercourse Study are used (as shown in map 2c). Reference should still however be made to map 2b when considering a development proposal.

Culverts (Refer to Map 3: Culverts)

5.21 A Culvert is a pipe used to enclose a watercourse, which may be used to allow water to pass underneath the ground. There are a large number of culverts in Liverpool.

5.22 A summary of the culverts in Liverpool is shown in table 4a and 4b below and illustrated on map 3: The 1999 Culverted Watercourse Study provides a table and map showing where the culverts are – this is illustrated in Map 3 (culverts are shown in red and open channels as blue). The 1989 Watercourse Flood Alleviation Study describes where some of the culverts are across the city. This can be in conflict with the information in the 1999 study. As such the following tables summarise the information and are split according to whether they match with the information in the 1999 study or are in conflict with it.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 24 -

Table 4a: Summary of Culverts – information from 1989 study that matches with the 1999 study

Those that are completely open channels: • River Mersey • Croxteth Brook • Sugar Brook • Knowsley Brook • Fazakerley Brook • Netherley Brook • Halewood Brook ((small section culverted at end) Upper Tue Culverted over most of its length for many years. There is a Brook short open section between Green Lane and Gardner Road Thornhead Culverted over much of its length to facilitate development. Brook There is still a section of open channel upstream of the Sefton Rugby Union Football Ground. Lower Tue From the ‘Walton Triangle’ to Long Lane the watercourse is Brook culverted except for a short length at Harper Road. From Long Lane to Higher Lane, the watercourse flows in open channel, except for a section at Wareing Road that was culverted. Childwall Watercourse has been culverted from its source down to the Brook Netherley Brook as development has proceeded. There is a section of open channel on the upstream ‘ordinary’ river at the King George’s Memorial Field Deys Brook There has been extensive urban development within the Brook’s catchment and substantial culverting has taken place. The only open channels are thought to be at West Derby Golf Course and from Croxteth Hall Lane to the River Alt River Alt Predominantly an open channel. Some major culverts have been constructed to facilitate development. Located at Hambleton Close and Hare Croft

Table 4b: Summary of culverts – information from the 1989 study that does not match with the 1999 study

Upper and Drainage function transferred to sewers. Sections of the Lower Brook original watercourse have been maintained and incorporated in the landscaping of Sefton Park, discharging into the boating lake Jordan Drainage function transferred to a constructed sewer. There is a short section immediately downstream of Aigburth Road just inside the entrance to Otterspool Park, where the entrance to the old brick culvert, constructed in the 19th century is partially visible. Becher’s Located on the border of Liverpool City Council. East to West Brook section along Aintree Race Course is an open channel. North of the racecourse to the River Alt is culverted

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 25 - Oglet Brook Largely culverted as the development of the airport and Speke Housing Estate has taken place. There is still a section of open channel that runs east to west along the southern edge of the playing fields that lie between Hale Road and the airfield Watercourses that are completely culverted: Hall Brook Mab Lane Drain Old Garston River Former watercourses that have incorporated into the sewerage system and can no longer be identified as arterial watercourses: Kirkdale Beacon’s Gutter Pool River The Mill Stream Dingle Drain Dickinson’s Dingle Cressington Park Drain Speke Hall Drain

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 26 - Risk of flooding

5.23 This section is split into the following sub-sections and maps, which should be viewed as part of this section:

• Tidal flooding: River Mersey o Map 4a: Environment Agency flood risk zones – tidal flood risk • River flooding o Map 4b: Environment Agency flood risk zones – tidal and river flood risk o Map 5: Flood Risk Zone 3: Estimated functional floodplain (3b) and High Probability Area (3a) o Map 6: Historical flooding areas • Condition of culverts o Map 7: Condition of culverts – where information is available, the areas of poorest condition are identified • Sewer flooding o Map 8: Historical sewer flooding • Summary of identified flood sources o Map 9: Identified flood risk – Environment Agency flood risk zones, historical flooding areas, historical sewer flooding and condition of culverts • Risk of flooding in and from adjoining authorities o Map 10: Risk of flooding in and from adjoining authorities • Groundwater

Tidal flooding: River Mersey (Refer to Map 4a: Environment Agency flood risk zones – tidal flood risk)

5.24 The River Mersey originates at the confluence of the River Tame and the River Goyt in the town centre of Stockport. It flows west, towards Liverpool, becoming tidal at Howley Weir (Warrington) and this is where the Upper Estuary starts. It widens to form the Inner Estuary at Runcorn. The Mersey Estuary continues through the ‘Narrows’ a straight narrow channel with depths of up to 30 m driven by a change in geology. It forms the Outer Estuary, a large area of inter-tidal sand and mud banks as it flows into Liverpool Bay on the Irish Sea.

5.25 Environment Agency Indicative flood plain map of England is shown for the River Mersey in Liverpool in Map 4a and identifies: • Flood Risk Zones 1 (no shading) - low probability – annual probability of flooding: river or sea flooding <0.1% • Flood Risk Zone 2 (shaded pale blue) – medium probability – annual probability of flooding: river 0.1 – 1.0%; sea flooding 0.1 – 0.5% • Flood Risk Zone 3a and b (shaded dark blue) – high probability and the functional floodplain – annual probability of flooding: river >1.0%; flooding from the sea >0.5%

5.26 Although areas of flood risk are identified within the Environment Agency Indicative Flood Risk Maps and are a serious consideration, it is a relatively

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 27 - limited inland area affected. This Figure 8: Flood Risk Zones for Mersey is demonstrated in the Mersey Estuary Catchment Estuary Catchment Flood Management Plan (draft) which shows the Environment Agency Flood Risk Zones for the whole catchment (see figure 8).

5.27 PPS25 defines a Functional Floodplain as land where water has to flow or be stored in times of flood. Specifically, this land: • Would flood with an annual probability of 1 in 20 (5 per cent) or Reproduced from Mersey Estuary Draft greater in any year, or at another Catchment Flood Management Plan (© Crown probability to be agreed between Copyright. All rights reserved. 100026380, the LPA and the Environment 2007) Agency (EA), or • Is designed to flood in an extreme (0.1 per cent) flood, or at another probability to be agreed between the LPA and the EA

5.28 The Companion Guide to PPS25 (Draft) takes the definition further, stating that whilst developed areas are not generally considered to comprise Functional Floodplains, the definition within PPS25 does not differentiate between developed and undeveloped areas. The functionality of such areas should be considered when defining Zones 3a and 3b, taking into account strategic flood risk management policies. All areas within Zone 3 should be considered as Zone 3b (Functional Floodplain) unless, or until, an appropriate FRA shows to the satisfaction of the EA that it can be considered as falling within Zone 3A (High Probability). Map 5 provides an estimate of which watercourses are within the functional floodplain (3b) and which are within the high probability (3a) flood zone. It is however expected that developers proposing to develop within any of Flood Risk Zone 3 demonstrate whether the site is within a functional floodplain or high probability zone to the satisfaction of the Environment Agency.

5.29 There is considerable information available regarding the River Mersey from a number of sources. Two of the key sources are: • Shoreline Management Plan/Catchment Flood Management Plan11 (predominantly at the moment in the CFMP but future revision of the SMP may provide further guidance) and • ‘National Tidal and Sea Level Facility12’/ Proudman Oceanographic Laboratory – Natural Environment Research Council13 which although a national resource is based within Liverpool.

11 Mersey Estuary Catchment Flood Management Plan – Scoping Report (November 2005) and Mersey Estuary Catchment Flood Management Plan – Draft (March 2007) 12 National Tidal and Sea Level Facility - reflects the importance of national sea level monitoring to the public, academic community and government - http://www.pol.ac.uk/ntslf/

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 28 -

5.30 Some of the information included within these sources is as follows: • Tidal elevations – measurement locations at Liverpool Gladstone Dock (north of Liverpool local authority boundary) – measured by National Tidal & Sea Level Facility network (NTSLF) and at Gladstone Lock by Mersey Docks & Harbour Company • Tidal predictions – 7 day forecast and highest and local tidal predictions for the years 2005 – 2025 at Gladstone Lock • Sea level trends – from 1850 to 2005 at Gladstone Dock • River flows – measurement point unknown • Various different types of modelling and forecasting.

5.31 Some of the key points from this data are as follows:

• The River Mersey has the second highest tidal range in the UK, varying from 4m at neap tides to 10m at spring tides. The river flow is about 1% of the tidal flow. Tidal levels are as follows in table 5:

Table 5: Tidal levels in Liverpool (Gladstone Dock) Highest Astronomical Tide 10.25m Lowest Astronomical Tide -0.02m (HAT) (LAT) Mean High Water Spring 9.31m Mean Low Water Spring 1.04m (MHWS) (MLWS) Mean High Water Neap 7.42m Mean Low Water Neap 3.10m (MHWN) (MLWN) Highest 2000 9.84m Lowest 2000 0.27m Highest 2001 10.08m Lowest 2001 0.04m (Mean Spring Range) MSR 8.27m (Mean Neap Range) 4.32m MNR

Tidal levels are quoted relative to chart datum (approximately the lowest level due to astronomical effects and excluding meteorological effects). The heights of chart datum (CD) relative to ordnance datum (OD, at Newlyn) in the UK is -4.93m for Liverpool, e.g. if there is a data value for Liverpool of 10.25m relative to CD and the data is required relative to OD, then this would be 5.32m (i.e. 10.25m - 4.93m). • A general trend of sea-level rising has been recorded from 1850 to 2005. If this trend continues, this could have dramatic impacts on the frequency and extent of flood risk along the River Mersey. This is due to various factors but includes climate change (see climate change section below (paragraphs 5.73 to 5.84) • A storm surge is defined as an increase or decrease in sea level in relation to the predicted tide level. It is usually caused by the action of wind stress on the water surface which may be coupled with a change in level caused by variation in barometric pressure. The shallow north-eastern part of the Irish Sea including Liverpool Bay and the Mersey estuary is particularly

13 Proudman Oceanographic Laboratory - research focuses on oceanography encompassing global sea-levels and geodesy, numerical modelling of continental shelf seas and coastal sediment processes. In addition, they undertake activities of surveying, monitoring, data management and forecasting - http://www.pol.ac.uk/home/

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 29 - susceptible to storm surges whereas surges have been shown to be less likely in the Irish Sea at spring tides rather than at neap tides. The highest astronomical tide (HAT) for Liverpool is 5.37 m14 above Ordnance Datum Newlyn (ODN). A theoretical maximum value of 6.1 m ODN has been suggested for Liverpool Bay. This height was exceeded in November 1977 when a severe storm coincided with a spring tide. Sea conditions arising from storm surges have caused considerable damage to natural and artificial sea defences.

5.32 The western most boundary of Liverpool, fronting onto the River Mersey includes a variety of land uses. In addition, the boundary itself varies in its structure from mud flats to the south of the city to the river wall, docks, promenades, industrial buildings and apartments towards the north of the city.

5.33 The only recording of flooding along the length of the Mersey within Liverpool is at Pier Head. This is reportedly due to exceptionally high tides backed up by strong winds from the west, causing the river to overtop the river wall at Pier Head. A small amount of water is reported to cover a restricted area of the Pier Head promenade lasting for approximately 1 – 2 hours. Due to the frequency of this occurrence and the location, an emergency plan of sandbagging is in place.

5.34 Additional information indicates that the docks are not designed to fulfill a flood defence role, with any such role being incidental. This information also indicates that in the event of extreme surges, flood waters can enter the port via lock gates at Gladstone so flood defence is ultimately provided by the east quays rather than the river wall.

River Flooding (Refer to Map 4b – Environment Agency Flood Risk Zones – Tidal and River Flooding and Map 6: Historical flooding areas)

5.35 Environment Agency Flood Risk Zones – Environment Agency Indicative flood plain map of England is shown for the rivers in Liverpool in map 4b and identifies: • Flood Risk Zones 1 (no shading) - little or no risk – annual probability of flooding: river, tidal and coastal <0.1% • Flood Risk Zone 2 (shaded pale blue) – low to medium risk – annual probability of flooding: river 0.1 – 1.0%; tidal and coastal 0.1 – 0.5% • Flood Risk Zone 3 (shaded dark blue) – high risk – annual probability of flooding, with defences where they exist: river 1.0% or greater; tidal and coastal 0.5% or greater

5.36 Paragraphs 5.27 and 5.28 above provide details on flood risk zones 3a (high probability) and 3b (functional floodplain) which applies to rivers as well. Reference should therefore be made to Map 5.

14 Level differs to table 3 due to different sourcing – Table 3 is taken from http://www.pol.ac.uk/ntslf/tgi/live.html (last updated 2003) and the reference to storm surge is taken from the Mersey Estuary Catchment Flood Management Plan (CFMP) which also sources the Proudman Oceanographic Laboratory

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 30 -

5.37 The sequential test (and exception test) of PPS25 should be applied.

5.38 Additional information from the 1989 study regarding Environment Agency indicative flood risk areas:

Table 6: Historical information for the Environment Agency Flood Risk Zones Lower Tue Subject to persistent flooding problems over a long period of Brook time. In the upper culverted section between Hazeldale Road and Long Lane, the culvert is of an inadequate size to deal with present day storm flows due to its age and doubtful structural condition. Flooding has been experienced north of Cavendish Drive and the housing estate on the North side of Walton Park. Flooding has also occurred in the vicinity of Stalmine Road, near Harper Road and at Sefton Road, bordering the Rice Lane Recreation Ground. Rubbish and the condition of culverts in this area are thought to contribute to this problem. An inadequate sized culvert at Wareing Road has created flooding in this area. River Alt Well maintained and improvements made to cater for the additional run-off from the Croxteth Park Estate. This improvement was not allowed to proceed through Croxteth Park and a potential flooding problem occurs. Fazakerley The only major problem is the constriction caused by the Brook inadequate waterway of the Lower Lane Bridge and the channel immediately upstream is of limited capacity. Croxteth There are no current flooding problems affecting urban property Brook but there is some inundation of agricultural land on the left and right banks of the watercourse Childwall Persistent flooding problems at Walsingham Road. Thought to be Brook due to the inadequate size and design of the screen at its entrance. There is also thought to be a collapsed culvert upstream of the King George’s Memorial Field. Further problems have been experienced at the upstream end of the City’s Childwall Valley culvert where a blockage of the screen at the upstream end of the culvert and blockage of the channel a short distance upstream. Flooding has also occurred in Naylor’s Road and the Childwall Valley Road which may be caused by debris obstructing flow.

5.39 Historical flooding areas – areas where flooding has occurred historically (according to studies undertaken in 198915 (reporting on flood events in 1967, 1988 and other sources undated) and 199216). The length of the watercourse affected has been identified in Map 6, either as an area that has suffered a significant number of flooding incidences (red dashed line) or a more localised area that has suffered a more limited number of incidences (yellow dashed line). There is no set definition of ‘significant’ but generally applies where

15 Watercourse Flood Alleviation Study – Summary Report – Liverpool City Council (1989) 16 Report to Liverpool City Council – Flooding to Liverpool 6 District of the City (1992)

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 31 - there are a number of incidents and/or a large number of times per year and/or affecting houses. Those historical areas that fall within the Environment Agency flood risk zones have not been shown as they are accepted designated flood risk areas. A description of the areas of historical flooding and some of the potential reasons identified in the 1989 study are included below (some of this information overlaps with the culvert condition information provided below in table 9). Table 7: Historical areas of flooding Significant number of historical flooding incidences: Upper Tue Significant number of incidences from 1967, 1988 and 1992 from Brook Edge Lane to Queens Drive Walton/Utting Avenue. Roads, gardens and houses. 1967 – 11 reported incident locations ranging from once in two years to 5 times per year 1988 – 14 reported incident locations ranging from once a year to 7 times a year One other record stating ‘frequent flooding’ at Carlton Cinema, Green Lane, Gardners Lane 1992 – Approx 14 incident locations Additional description from 1989 study: From Edge Lane to Fazakerley Brook this is the most severely affected in the city. The culverts are in various sizes and shapes and are generally in poor condition. Collapsed and derelict lengths under the bus depot and water depot at Green Lane were replaced in 1986 but other sections require further inspection and survey. Railway drainage discharging to the brook is affected by the lack of capacity giving rise to additional flooding risks.

The inadequate size, poor debris screen arrangement and frequent blockage of the Gardner Road open length leads to heavy silt deposition which exacerbates flooding in Russian Drive and surrounding streets and adds to the problems at the junction of West Derby Road and Muirhead Avenue. Thornhead Number of incidences from 1967, 1988 and 1992 along Leyfield Brook Close. Roads, gardens and houses. Houses particularly around Leyfield Road. 1967 – 3 reported incident locations ranging from two times a year to 7 times per year 1988 – 1 reported incident location flooding 7 times per year One other record stating ‘severe flooding’ at Leyfield Road 1992 – Approx 9 incident locations Additional description from 1989 study: Flooding of property, roads and gardens at Leyfield Road and Close and Aylescourt. Likely causes of problem are the inadequate capacity of the upstream culvert and poor maintenance and silting of the open channel

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 32 - Deys Number of incidences from 1967, 1992 and other sources within Brook 1989 study. Predominantly affecting roads and gardens, although (north) along Deysbrook Lane, there was flooding of properties in 1967. 1967 – 1 reported incident location flooding 5 times per year 1992 – Approx. 5 flooding locations Additional information from 1989 study: From River Alt to St Andrews Avenue (in 1989 this was playing fields) there are constrictions due to the limited capacity of the Yew Tree Lane culvert and the limited capacity of the Deys Brook Lane Bridge and the short length of culvert linking it to the large culvert downstream

Limited number of historical flooding incidences: Upper Tue A small number of reported incidences in 1988. Roads and Brook gardens only. (north of 1967 – 1 reported incident location flooding 4 times per year Utting 1988 – 7 reported incident locations ranging from once a year to 8 Avenue) times a year 1992 – Approx. 3 incident locations Additional description from 1989 study: Flooding has also been experienced at points downstream of Utting Avenue. Part of the overall problem may be due to the inability of surface water to reach the brook due to blockage of road gullies or their branch pipes. Upper A small number of reported incidences in 1967. Roads and Brook gardens only 1967 – 2 reported incident locations both flooding 2 times per year No other reported incidents Jordan A small number of reported incidences in 1967 and 1992. Roads, River gardens and houses. 1967 – 1 reported incident location flooding once a year One other record stating ‘periodic’ flooding at Aigburth Road 1992 – Approx. 2 incident locations Additional description from 1989 study: Flooding has occurred between Aigburth Vale and Ashfield Road. Whilst the primary drainage functions has been transferred to a nearby sewer, the overflow from Sefton Park boating lake still follows the line, in culvert of the original river channel. Deys A small number of reported incidences along this lower stretch of Brook the watercourse in 1967, 1988 and 1992. Roads, gardens and (south) houses 1967 – 1 reported incident location flooding 5 times per year 1998 – 2 reported incident locations flooding 2 times per year One other record flooding 2 times per year 1992 – Approx 4 flooding locations

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 33 - Oglet Continuous reported incidence of ponding of the watercourse from 1967 Flood Records. 1967 – 1 reported incident location of continuous ponding of watercourse No other reported incidents Additional description from 1989 study: Permanent ‘ponding’ of this small watercourse is evident, immediately upstream of the airport perimeter fence. This is thought to be due to an obstruction at the culvert entrance.

Additional information from the 1989 study – limited or no flooding identified: Sugar There are no major flooding issues identified. However due to an Brook ordinary watercourse tributary that discharges onto the right bank of the watercourse, land on the cemetery site is subject to waterlogging. It is not clear if this is due to obstruction in the culvert or lack of capacity in this or the downstream ditch. Becher’s Flooding is experienced in Barlow Close due to the inadequacy of Brook the pipe linking the estate to the brook Lower Only reported flooding is at Ullet Road, on the upstream Brook culverted section of the watercourse. Old Flooding is experienced at Waylands Drive, Woolton Golf Course Garston and at Stairhaven Road. It would appear that this is due to a lack River of capacity in the downstream culverts. (This is not within the identified watercourse route.) No major Mab Lane Drain flooding Hall Brook issues Knowsley Brook identified: Netherley Brook Halewood Brook

5.40 The reported incidences predominantly affects roads and gardens but there are some more limited incidences where houses are also affected. For full information refer to the 1989 study available from the City Council Planning Policy Department – [email protected]. In addition, the study provides recommendations as to how to reduce the flood risk.

5.41 It should also be noted that the 1992 study also states that, it would appear that on every occasion that flooding to property has occurred an exceptional storm has been the contributing factor.

5.42 The most recent recordings of flood incidences are taken from 1992 with the previous recordings in 1967, 1988 and other flood sources prior to 1989. As such, measures may have been put in place that have solved or at least partially solved the source of flooding. In addition, increased development may have taken place increasing the pressure on the existing structure or providing the opportunity to improve the situation.

5.43 The 1989 study identifies that at many locations, flooding is experienced on a number of occasions annually and in all the situations identified by this study, inundation occurs at a mean interval of 5 years or less. These levels of risk

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 34 - compare unfavourably with the Environment Agency where the level of risk within flood risk zone 3, the highest risk zone is at a 1 in 100 years or greater.

5.44 A number of other flooding incident locations have been identified by Liverpool City Council Highways Department through their role in managing and maintaining the highway (October 2006). These flooding locations remain the same in January 2008, with Leyfield Road having an increase in the frequency of flooding. Whilst these incidents may affect nearby residential areas, the information has been gathered for the purposes of highways maintenance only. In addition, the cause of flooding may not be river flooding; it could be due to a range of sources/issues. Map 6 identifies these locations and they are summarised in Table 8 below:

Table 8: Flood locations supplied by Highways Flooding Locations Additional information received through consultation Speke Road L24 between Speke Hall Road & Last recorded incident was in September Speke Retail Park L24 2002 East Lancashire Road O/S Showcase Cinema Frequent flooding occurs with heavy rain (Sugar brook capacity) and East Lancashire Road J/O Stonebridge Lane Walton Hall Avenue Central Reservation J/O Periodically flooding occurs, particularly in Blackthorn Road L4 Autumn. West Derby Road (Tuebrook roundabout). Tuebrook culvert capacity – only needs a small amount of rain for standing water to occur. Greenwich Road L9 and Seeds Lane L9 (under Surface water sewer capacity due to heavy bridge). rain. Walton Vale L9 / Warbreck Moor / Longmoor Issue has been improved but not fully Lane (Black Bull public house). resolved. Deysbrook Lane L14 Surface water capacity issue due to Mab Lane L14 extreme rainfall/flash floods. Deysbrook Lane / Crawford Close L12 Dumbrees Road / Mab Lane L12 Maiden Lane L13 Linked with Tuebrook culvert. Ullet Road L17 O/S no 13 Heavy rainfall causes flooding to occur. Lower Lane L9 J/O Brookfield Drive L9 Surface water issue – options for improvements are being considered. East Prescot Road L14 / J/O Finch Lane L14 Surface water capacity issue. Leyfield Road L14 Increased frequency of flooding. Silted sewer system and vegetation creating obstacles in the brook

Condition of Culverts (Refer to Map 7: Condition of culverts)

5.45 Due to the large number and age of culverts in Liverpool, condition is a key issue in Liverpool. The risks associated with the poor condition and maintenance of a culvert is as follows: • exceptional storm rainfall • inadequate channel or culvert capacity

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 35 - • blockage of channel or culvert by silt or debris. Culvert screens are particularly prone to blockage even when regularly maintained. • remote obstructions preventing flood water reaching channel or culvert e.g. blockage of gullies flowing into culverts, resulting in additional overland flow • structural failure

5.46 Information provided within the 1989 Watercourse Flood Alleviation Study provides an overview of the key issues regarding culverts: “The present day drainage arrangements are comprised of sewers, open channels and culvert structures built mainly in the 19th century. Although still operational, the hydraulic performance of these works is poor because of aging… Many were designed using old methods and criteria which are unsatisfactory in the light of modern practice. Structurally many of the works are in, or approaching, a life expired state and major collapses could occur under the stress of flood conditions. The situation has been exacerbated by the piecemeal nature of the past development and lack of adequate planning controls, in the early years. … Further deterioration has been caused… by insufficient maintenance, attributable due to the lack of legislation making any authority directly responsible for ‘ordinary’ watercourses.”

5.47 The Environment Agency considers it beneficial for watercourses to remain open wherever possible for both flood defence and environmental purposes. In addition, the Practice Guide to PPS25 states that: Perhaps most in the spirit of the Government’s Making Space for Water strategy are proposals that seek to combine new development with measures to restore heavily-modified watercourses and their floodplains to a more natural state. Such measures can include removing culverts, restoring meanders and reconnecting river channels with areas of floodplain obstructed by artificial features. All of these measures can result in reductions in flood risk, as well as significant improvements in amenity, biodiversity and water quality.

5.48 Limited information is available regarding both a comprehensive and up-to- date assessment of the condition of culverts. The information available is summarised as follows, beginning with the most recent information and the areas of poorest condition are identified on Map 7:

Table 9: Condition of culverts Source: Recent report from the Emergency Planning department

Name of Description watercourse Childwall Culvert collapsed at Chelwood Avenue in early 2006. Repair Brook work is underway (See map 7, shown in yellow)

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 36 -

Source: Environment Agency Asset Inspection 2003/2004 – assessment of the condition of river assets (such as raised defences, bridges and other structures) All inspection points rated as poor or very poor are shown on Map 7 in pink Name of Description of condition (Inspection Number of Watercourse condition ratings: 1- very good, 2 – good, 3 – inspection fair, 4 – poor, 5 – very poor) points Deys Brook Adjacent to Croxteth Hall Lane considered to 4 be good (2). Within West Derby Golf Course was considered to be fair (3). South of Yew Tree Lane, two inspection points in close proximity considered to be fair (3) and good (2). Knowsley Brook Condition assessed on section of Brook within 2 Liverpool. Considered to be fair (3) Croxteth Brook Considered to be fair (3). 6 River Alt Section between Knowsley Brook and 12 Fazakerley Brook considered to be poor (4) and very poor (5) condition. Section adjacent to Stonebridge Lane considered to be fair (3). Section adjacent to East Lancs. and Altcross Road considered to be poor (4). From north of Oak Lane to Deysbrook – considered to be fair (3). South of Deysbrook at Coachman’s Drive and Harecroft were considered poor (4). Sugar Brook Considered to be fair (3). 1 Fazakerley Brook Considered to be fair (3). 2

Source: Culverted Watercourse Study (August 1999) (Liverpool City Council) – specific assessment of culverts All sections of culverts identified as serious structural defects or collapsed are shown on Map 7 in red Name of Description of condition (from a partial assessment of watercourse watercourses – 1 – no structural defects, 2 – minor structural defects, 3 – some structural defects, 4 – serious structural defects and 5 – collapsed). (General summary of information provided) Upper Tue Between Edge Lane and Prescot Road have some structural Brook defects (3). Childwall Between Rocky Lane and Gregory Close – section collapsed (5) Brook and a section with serious structural defects (4). South of Childwall Valley Road, by Napps Close – serious structural defects (4). Large sections of the brook are considered to have no structural defects (1). The condition was unknown for small sections. Deys Brook South of East Prescott Road, the condition was largely unknown. The majority of the rest of the brook northwards, was considered to have no (1) or minor structural defects (2).

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 37 - Hall Brook Considered to have no structural defects (1)

Jordan River Sefton Park Lake to Jericho Court considered to have some structural defects (3), with the exception of one point which was considered to have serious structural defects (4). The remainder of the Jordan River towards the River Mersey is considered to have serious structural defects (4), with one section collapsed (5). River Alt Culverted section around Steers Croft considered to have no structural defects (1) (EA Asset Register above 2003/2004 considers this section to be poor). The majority of the remainder of the watercourse is either not applicable (as open) or unknown Thornhead Measurement starts north of Leyfield Close heading north to Brook Deys Brook, with some sections unknown. Section around Deysbrook Lane considered to have serious structural defects (4). The remainder of known measurements were of no structural defects (1) or minor structural defects (2). Upper Greenbank Lane to Sefton Park Nurseries has serious structural Jordan (part defects (4). of Upper Brook) Upper Tue Section along Green Lane, adjacent to Cheadle Avenue/Bus Brook Depot – culvert collapsed (5). Section until around Moscow Drive considered to have no (1) or minor structural defects (2). From Moscow Drive to Rockbank Road the culvert is collapsed (5). From Gardner Road to West Derby Road, considered to have serious structural defects (4) and from West Derby Road to Sandringham Road, the culvert is collapsed (5). From Portrush Street to Worcester Drive, the culvert is also collapsed (5). From here to Cherry Lane, there are no structural defects (1) and between Cherry Lane and Queens Drive there are some structural defects (3). Along Richard Kelly Drive at Daneville Road, the culvert has serious structural defects (4) and until Kingsland Crescent has some structural defects (3). A section between Kingsland Crescent and Long Lane has serious structural defects (4), with the remaining up to this point having minor structural defects (2). From Swallowfields the remainder is unknown.

Source: Watercourse Flood Alleviation Study (April 1989) Liverpool City Council

Name of Description of condition (description of flood risk on certain watercourse watercourses makes a number of references to the condition of culverts – not shown on map 7) Upper Tue The culverts are in various sizes and shapes and are generally in Brook poor condition. Collapsed and derelict lengths under the bus depot and water depot at Green Lane were replaced in 1986 (Information in the 1999 study indicates that this section is collapsed) but other sections require further inspection and

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 38 - survey.

Thornhead One of likely reasons for flooding at Leyfield Road and Close Brook and Aylescourt is the inadequate capacity of the upstream culvert Deys Brook From River Alt to St Andrews Avenue (in 1989 this was playing (north) fields)there are constrictions due to the limited capacity of the Yew Tree Lane culvert and the limited capacity of the Deys Brook Lane Bridge and the short length of culvert linking it to the large culvert downstream Lower Tue In the upper culverted section between Hazeldale Road and Brook Long Lane, the culvert is of an inadequate size to deal with present day storm flows due to its age and doubtful structural condition. Rubbish and the condition of culverts in the area around Rice Lane Recreation Ground is thought to contribute to this problem. An inadequate sized culvert at Wareing Road has created flooding in this area. Childwall Flooding at Walsingham Road is thought to be due to the Brook inadequate size and design of the screen at its entrance. There is also thought to be a collapsed culvert upstream of the King George’s memorial Field. Further problems have been experienced at the upstream end of the City’s Childwall Valley culvert where a blockage of the screen at the upstream end of the culvert and blockage of the channel a short distance upstream.

5.49 The recent report of a culvert collapse in an area not previously identified (although it is close to King George’s Memorial Field) demonstrates that full information regarding the condition of culverts is not available without a comprehensive up-to-date assessment.

Historical Sewer Flooding (Refer to Map 8: Historical sewer flooding (United Utilities DG5 Register))

5.50 This shows post code areas that have properties within them that have experienced internal or external sewer flooding. This is based on information supplied by United Utilities through the DG5 At Risk Register which they are required to keep by OfWat, the Water Services Regulation Authority.

5.51 Internal sewer flooding - For the purposes of DG5, internal flooding is defined as flooding which enters a building or passes below a suspended floor. For reporting purposes, buildings are restricted to those normally occupied and used for residential, public, commercial, business or industrial purposes.

5.52 External flooding: For the purposes of DG5, external flooding is defined as flooding which is not classed as internal. For reporting purposes, external areas will be split into curtilages, highways and other external areas.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 39 - 5.53 It is an important distinction that the DG5 register and Map 8 shows the number of properties that have flooded rather than those that are at risk of flooding. Properties within these areas remain at risk of future flooding. However, other areas may still be at risk from future flooding that cannot be identified with the level of detail available for this assessment

5.54 The exact location of the properties within this area is not Figure 9: External DG5 for Mersey Estuary known, although United Utilities Catchment hold a record. It is also therefore important to note that the areas shown in Map 8 do not represent a true picture of exactly where the flooding has occurred. In most cases, only one property will have been affected within the whole postcode area. The number of properties that have flooded is relatively low and is illustrated by Map 8 which shows the majority of postcode areas have between 0 and 4 properties flooded. Figure 9 shows the level of sewer flooding from Reproduced from Mersey Estuary Draft Catchment Flood Management Plan (© Crown Copyright. All rights DG5 data (external flooding only reserved. 100026380, 2007) – 1st April 2005) for the Mersey Estuary catchment. This demonstrates the relatively low level within Liverpool (grey represents ‘no recorded flooding’ and light yellow represents ‘1-4 properties affected by sewer flooding’.

5.55 OfWat use risk levels to demonstrate the level of risk within the area as follows: 1 in 20 risk level, 1 in 10 risk level, 2 in 10 risk level. However, this essentially only indicates the number of times properties have flooded. The majority of incidences are in the 1 in 20 which is the lowest incidence of reported flooding. The following table (Table 10) shows the total number of properties that have flooded in each postcode area (using 2006 figures) which is then considered against the Ofwat rating.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 40 - Table 10: Incidences of sewer flooding

Total Internal / External Total Internal / External Number of Incidence of flooding Number of Incidence of flooding properties properties that have that have Postcode experienced 1 in 1 in 2 in Postcode experienced 1 in 1 in 2 in Area flooding 20 10 10 Area flooding 20 10 10 L12 6 66 27 39 0 L3 0 1 1 00 L12 9 12 11 1 0 L26 8 1 1 00 L4 2 12 12 0 0 L16 3 1 1 00 L18 8 11 11 0 0 L16 4 1 1 00 L18 1 10 10 0 0 L19 4 1 1 00 L25 5 9 9 0 0 L17 1 1 1 00 L27 5 7 7 0 0 L6 1 1 1 00 L15 6 7 7 0 0 L19 1 1 1 00 L14 8 4 4 0 0 L18 9 1 0 10 L19 0 3 3 0 0 L14 7 1 1 00 L25 9 3 3 0 0 L18 5 1 0 10 L4 3 3 3 0 0 L20 0 1 1 00 L15 7 3 2 1 0 L17 6 1 1 00 L19 6 2 2 0 0 L16 5 1 1 00 L14 3 2 0 1 1 L6 9 1 1 00 L25 3 2 2 0 0 L17 7 1 1 00 L16 7 2 1 0 1 L13 5 1 1 00 L14 4 2 2 0 0 L9 3 1 1 00 L13 7 2 2 0 0 L9 9 1 1 00 L9 2 2 2 0 0 L25 2 1 1 00 L8 3 2 2 0 0 L14 0 1 1 00 L20 8 2 2 0 0 L15 4 1 1 00 L11 1 2 2 0 0 L25 0 1 1 00 L20 9 2 1 0 1 L7 0 1 1 00 L36 5 2 2 0 0 L6 5 1 1 00 L26 5 1 1 0 0 L8 9 1 1 00 L10 1 1 0 1 0 L13 3 1 1 00 L8 8 1 1 0 0 L14 6 1 1 00 L4 4 1 1 0 0

Summary of identified flood sources (Refer to Map 9: Identified flood risk – Environment Agency flood risk zones, historical flooding areas, historical sewer flooding and condition of culverts)

5.56 Map 9 brings together maps 4, 5, 6, 7 and 8 showing all the identified flood risk areas and historically at risk areas. This summarises all the information regarding known flood risks and is used as the basis for the assessment in section 6.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 41 - Risk of Flooding to and from adjoining authorities (Refer to Map 10: Risk of flooding to and from adjoining authorities)

5.57 Although there is a relatively limited area at risk of flooding in Liverpool, development within Liverpool could have a negative impact on the risk of flooding in adjoining authorities and vice versa.

Table 11: Risk of flooding to and from adjoining authorities Catchment Description of watercourse Major …could development increase in … floodrisk levels in: North River Alt flows north through Knowsley, Sefton Liverpool into Sefton Liverpool North River Alt crosses Knowsley, Liverpool Knowsley/Liverpool boundary, Liverpool and in turn flowing northwards into Liverpool Sefton North Croxteth Brook flows northwards Knowsley Liverpool along the edge of the Liverpool/Knowsley boundary. Flukers Brook flows into the Croxteth Brook within Knowsley North Knowsley Brook flows from within Knowsley Liverpool Knowsley to the border of Liverpool where it joins the Croxteth Brook East Court Hey Brook (within Liverpool, Knowsley Knowsley), Childwall Brook, Knowsley and in turn Netherley Brook and Halewood Halton local Brook all flow south through authority Knowsley towards Halton local areas. authority area

5.58 Large greenspaces, in excess of 1ha in size have therefore been identified within the north and east catchments (as shown in Map 10). Due to their large size, if they were to be developed, they would be more likely to have a significant impact on the surface-water run-off which in turn could affect the level of floodrisk in the adjoining authorities. This is particularly the case where greenspaces are in close proximity to watercourses.

Groundwater

5.59 Groundwater levels could be an issue in Liverpool as the water table is rising. It is not possible to map the risk as the water does not rise in an even way and detailed modelling is required to provide a full assessment. It depends on the thickness of the impermeable soil surface, the geomorphic soil layers and the pumping of the water. Groundwater flooding is most likely to be encountered in low-lying areas and should be investigated on a site by site basis.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 42 -

5.60 The groundwater level is rising in Liverpool due to the decreased need from local industries that used to abstract it. The main areas of water level increase are the City Centre and the tunnels underneath the Mersey.

5.61 The draft Mersey Estuary Catchment Flood Management Plan provides the following information about groundwater: “There is no known documented evidence of flooding from groundwater in the Mersey Estuary CFMP catchment. So, we consider the current risk of flooding from this source is small compared to other sources of flooding. We have already established that a large proportion of the Mersey Estuary catchment lies upon a significant aquifer, which, in the past, was pumped extensively for mining, water supply and other industrial purposes. Current groundwater flooding in the UK is best summarised in the Defra commissioned study: Groundwater Flooding Scoping Study (2004). In 1990, rising groundwater was reported to be causing the underground railway in the centre of Liverpool to flood when groundwater abstraction was reduced. Mersey Rail (Network Rail) subsequently installed a permanent abstraction system (dewatering boreholes) to solve this problem. Water levels are continuing to rise gradually in the north-eastern part of the city but this does not appear to be causing an increased risk of flooding.”

5.62 The Draft Plan also states that the issue of groundwater in the Mersey Estuary catchment is being addressed in a regional study of groundwater.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 43 - Flood defences

5.63 The following map should be viewed as part of this section:

• Map 11: Flood Defences – e.g. river wall, Greenfield sites and open spaces, levees

5.64 There are very limited flood defences within Liverpool. However, the following summarises, the known existing defences: • Culverts - there are a large number of culverts which can cause flooding where maintenance, capacity or structure is poor. (See Maps 3 and 7 and Tables 4a, 4b and 9) • Greenspaces - can also provide a flood defence function, acting as a storage basin and allowing the water to infiltrate into the ground, rather than flowing as surface water run-off. Map 11 shows all the greenspaces in close proximity to a main watercourse (taken from an Open Space Study undertaken by Atkins Consultants in 200517, including an audit of open spaces) and may therefore fulfil this function • River wall and cliffs– (Map 11) currently considered to be in good condition. The river wall runs along 13.2km of the 18km within the local authority area. There are a variety of ownerships including, Mersey Docks and Harbour Company, English Partnerships, Associated British Ports, the City Council and other private undertakings. The remaining 4.8km frontage consists of natural glacial till cliff at the back of sandy/muddy foreshore in private ownership. Within the general locality erosion rates are considered to be less than 0.25m per year. Erosion of the cliffs around the location of Liverpool John Lennon Airport has been identified. • Raised flood defences – (Map 11) there are only two acknowledged flood defence assets under the Environment Agency’s definition of: “Any structure artificially raised above the level of surrounding land with the express purpose of providing protection from flooding. Flood storage areas and their associated control structures are to be treated as flood defences”. These are along the River Alt (raised defence bank – man-made) and Netherley Brook. • Private landowners - there may also be flood defences implemented by private landowners which are not known.

17 Liverpool Open Space Study – Atkins Consultants (2005)

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 44 - Residual risk

5.65 The residual risk is the risk after mitigation measures have been put in place. It is due to the potential of defences breaking or overtopping, of bad emergency planning or poor construction in the flood zone.

5.66 The areas at risk shown within the Environment Agency indicative flood risk areas (Maps 4a and 4b) indicate areas that are at risk assuming there are no flood defences in place and therefore takes account of residual risk. With the level of risk being relatively low, there are only limited acknowledged flood defences (i.e. the raised defences at Netherley Brook and the River Alt) in Liverpool.

5.67 The main residual risks are: • Netherley Brook and River Alt flood defences collapsing or being overtopped – the flood defences are located in areas of Environment Agency flood risk zones and the flood defences may reduce the level of risk in this area. Any development in these areas would need to ensure that the flood defences provide an acceptable standard of protection for the lifetime of the development, taking into account climate change • Culvert collapse or lack of maintenance causing blockage – due to the large number of culverts city-wide, this could have serious consequences causing flooding to property, roads and gardens. The collapsed culvert could lead to road accidents and/or buildings collapsing. During a flood event, the flow may be strong enough to extract some bricks from the culvert. In this case the water would gather just upstream of the collapse and be deep enough to cause threat to human life. • River wall collapsing or being overtopped – the walls are in good condition and are regularly checked and it is not expected that they will collapse. They are not intended as a flood defence but in some places fulfil this function. Risks of erosion of the defended frontages are low. Overtopping already occurs at Pierhead in some circumstances and the area and level may increase due to climate change. There is an ongoing risk of local instability in the glacial till cliffs between Garston and Hale. In this locality general erosion rates are less than 0.25m per year. • Development of existing greenspaces increasing surface water run-off and removing a storage basin – development in existing greenspaces that are in close proximity to a watercourse could increase flooding downstream of the development • Private landowners – protecting their own property but causing problems downstream

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 45 - Extreme events and climate change

Extreme events

5.68 Extreme weather events, by their nature, may create higher levels of flooding than usually experienced within Liverpool. It can be directly due to the extreme event itself or through a combination of circumstances that creates an extreme impact.

5.69 In the context of this SFRA, it is important to recognise the potential for extreme events, but it is difficult to establish the level at which they can be planned for. The level of probability of an extreme event is considered to be low.

5.70 The 1992 Study (Flooding to Liverpool 6 District of the City) used as an evidence base within this SFRA reports on what were considered to be ‘severe and exceptional storms’ leading to ‘extensive flooding’. It did however consider that in this circumstance, the flooding that occurred were in a number of well-recognised flooding blackspots throughout the city.

5.71 The main measures that should be taken into account in terms of extreme weather events are therefore: • General good practice with regards development in flood risk areas – by following the advice provided within this SFRA and the guidance/sequential test within PPS25, the impact of an extreme event should be reduced • Flood defences – appropriate flood defences to cope with existing flood risks to an appropriate level. Extreme events may however exceed this level • Warnings - Environment Agency Advance Flood Warnings, Liverpool City Council Emergency planning, National weather and other media, general public awareness – there are various mechanisms in place which would react to a predicted extreme event minimising the impact for example through the use of sand bags

5.72 It is therefore unlikely to be necessary to put in place any additional measures from a planning perspective with regards an extreme event due to the low probability of it occurring, the difficulty in predicting the impact of an unspecified event and the need to follow good practice within flood risk areas at all times. In addition, the impacts of climate change could increase the intensity and frequency of storm events.

Impacts of climate change

5.73 The following map should be viewed as part of this section: • Map 13: Predicted Extreme Tide Levels in 2115 • Map 14: Predicted Extreme River Levels (Flood Risk Zone 2)

5.74 PPS25 Appendix B relates specifically to flooding and climate change. In addition, a Supplement to PPS1 on Climate Change has also been published.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 46 -

5.75 There is an increasing body of scientific evidence that the global climate is changing as a result of human activity. As a result, sea levels will rise globally. In addition to this there is a predicted increase in rainfall and stormy weather. This could all have significant impacts on the likelihood and frequency of flooding.

5.76 Within the north-west region, the summers are set to get significantly warmer while the winters will get stormier and wetter. Sea levels will rise, wind levels (and consequent damage) will increase and there will be a pronounced increase in flood risk18

Impact of climate change on coastal flooding 5.77 Allowances for the regional rates of relative sea level rise (based on figures used by Defra for coastal defence schemes which should be used as a starting point in preparing flood risk assessments) indicates the following annual increases for the North West and North East of England (north of Flamborough Head): Net sea level rise (mm/yr). Relative to 1990 1990 - 2025 2025 - 2055 2055 - 2085 2085 - 2115 2.5 7.0 10.0 13.0

5.78 It is expected that the greatest impact from climate change in Liverpool will be along the coast line. A minimum floor level is required for developments along the coastline (within flood risk zones 2 and 3) taking into account extreme tide levels and the impact of climate change over the lifetime of the development.

5.79 Extreme tide levels are measured north of the city at Gladstone Dock, for a 200 year and 1000 year level as follows (Royal Haskoning 2006): • 1 in 200 year level: 6.44 mAOD • 1 in 1,000 year level: 6.76 mAOD

5.80 Using the sea-level rise predications for the North West and applying to these extreme levels (up to 2115 on the basis that this is the furthest date available and that the development lifetime of buildings is considered to be 100 years for residential development and 60 years for non-residential. Whilst 2115 is currently 107 years away, this ensures this document provides a full precautionary approach for 7 years). This gives extreme tide levels as follows: • 1 in 200 year level: 7.39 mAOD • 1 in 1,000 year level: 7.71 mAOD

5.81 It should be noted that the Environment Agency Flood Zone maps do not take account of climate change. The hatched area in Map 13 identifies a climate change allowance zone (using the 1 in 1000 year level estimate for 2115 and plotting the elevations) which may become at greater risk of tidal flooding due to climate change. Any development within the climate change allowance zone will need to consider the impacts of climate change with regard to flood

18 Rising to the Challenge – A Climate Change Action Plan for England’s Northwest (Consultation Draft) – NWDA (2006)

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 47 - risk over the lifetime of the development and potentially through a site specific flood risk assessment.

5.82 It is also expected that the rise in sea level will change the frequency of occurrence of high water levels relative to today’s sea levels, assuming no change in storminess. There may also be secondary impacts such as changes in wave heights due to increased water depths, as well as possible changes in the frequency, duration and severity of storm events. On a long term basis the surface water run off may also increase due to increased levels of development coupled with more intense rainfall during winters.

5.83 The current Environment Agency advice (June 2007) with regards floor levels for development within flood risk zone 3 (tidal) is included in Appendix B.

Impact of climate change on river flooding 5.84 PPS25 provides a precautionary assessment for increases in rainfall intensity, peak river flows and wind speeds within PPS25 (Annex B - Table B.2) and shown below. In conjunction with the increased sea levels, this is recommended for consideration particularly within estuaries.

Recommended national precautionary sensitivity ranges for peak rainfall intensities, peak river flows, offshore wind speeds and wave heights Parameter 1990 - 2025 - 2055 - 2085 – 2025 2055 2085 2115 Peak rainfall intensity +5% +10% +20% +30% Peak river flow +10% +20% Offshore wind speed +5% +10% Extreme wave height +5% +10%

5.85 At this stage it is not possible to map the impact of climate change on river flooding. Following advice from the Environment Agency, the ‘climate change allowance zone’ for all main rivers in Liverpool is the 1 in 1000 year extreme event - flood risk zone 2 as shown in Map 14. Ideally, an additional area would be identified to take account of climate change on top of an extreme event (i.e. in addition to the 1 in 1000 year event). However, the Environment Agency considers that in practice this additional boundary is unlikely to make a significant difference. Further modelling would be required to establish an exact boundary.

5.86 Any development within the climate change allowance zone (and potentially development in close proximity to flood risk zone 2) will need to consider the impacts of climate change with regard to flood risk over the lifetime of the development and potentially through a site specific flood risk assessment.

5.87 Flood Risk Zones are not identified for ordinary watercourses and as such it is not possible to identify a climate change allowance zone. Consideration should therefore be given to any development in close proximity to an ordinary watercourse to the potential for flood risk over the lifetime of the development.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 48 - 5.88 With levels of flood risk relatively low within Liverpool, it is not expected that climate change will have significant consequences for the majority of Liverpool within the lifetime of the Local Development Framework (2021). The lifetime of new development will need to be considered in addition to the lifetime of the plan. However an increase in extreme weathers could lead to an increased frequency and severity of flooding in the remaining flood risk areas, including a potentially significant impact on the sewer system and system of watercourses (which are largely culverted) due to the current systems being unable to cope. There may also be changes in the future where existing lower level risk areas are re-classified to higher level risk areas.

5.89 More detailed information is increasingly available on climate change and this should be incorporated into this Strategic Flood Risk Assessment and development based Flood Risk Assessments as and when it is available. A continual monitoring process will be applied.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 49 - 6. Spatial Development & Flood Risk

6.1 This section of the SFRA looks at where development activity is likely to occur in the future and attempts to assess the impact of the flood risk assessment (found in section 5) on these key development / regeneration priority areas. It also looks at the level of floodrisk associated with undeveloped allocated sites within the Unitary Development Plan (based on those watercourses identified in the 1999 Culverted Watercourse Study).

6.2 Through the Local Development Framework, the Site Allocations DPD and Area Action Plans will identify sites appropriate for different types of development. The level of floodrisk and the application of the sequential approach will be a key consideration in this process. However, until that process is undertaken, the strategic areas of development pressures are identified and assessed for likely floodrisk issues.

6.3 Strategic development areas are the key focus for development in the city of Liverpool. These areas can be divided into five categories: • Liverpool city centre and waterfront • Housing regeneration areas • Strategic investment areas (SIAs) • Other development / regeneration priorities • Sites allocated in Liverpool’s UDP which are yet to be implemented

6.4 The following map should be viewed as part of this section: • Map 12: Summary of all identified floodrisk, Strategic Development Areas and UDP Allocations

Liverpool City Centre and waterfront

6.5 The city centre of Liverpool is a key focus for development and regeneration at the regional, sub-regional and local scale. In addition, the waterfront and the potential for development along it, is one of the key assets of the city in terms of achieving the vision of the Council to become a prosperous city. It contains a large amount of development activity for all different types of development. This can be for retail, housing, leisure, employment or mixed use projects.

6.6 The main flood risk issue in the city-centre is due to the River Mersey. Special requirements have already been implemented in this area to take this risk into account. A minimum floor level is required for developments along the coastline (within flood risk zones 2 and 3) taking into account extreme tide levels and the impact of climate change over the lifetime of the development.

6.7 Other flood risk issues may occur with increased surface-water run-off, flash floods, sewer floods and groundwater floods. Moreover, in the city centre, some old brooks and drains have been integrated into sewers and this might be a problem in the case of an extreme event, if the sewer pipes do not have sufficient capacity to deal with the flow.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 50 - 6.8 Rising groundwater levels is also a concern for the City Centre. Older buildings have been built when the industry in Liverpool abstracted water from the aquifer. Therefore the water level was lower and the basements were built with respect to this original level. As the industry no longer needs to abstract water, the table has risen and can cause flooding.

6.9 The World Heritage Site designation is located within the City Centre and waterfront. Paragraph 19 of PPS25 states that it may be appropriate to use the Exception Test where restrictive national designations exist such as World Heritage Site designations, preventing the availability of unconstrained sites in lower risk areas. A large proportion of the City Centre is not within the World Heritage Site designation. However at the same time, heritage led regeneration is also supported within the World Heritage Site.

Housing regeneration areas

6.10 The main development area for housing is inside the Housing Market Renewal Initiative (HMRI) area boundaries. This is known as the “Pathfinder” area which aims to develop and implement a comprehensive approach to the renewal of the urban housing market.

6.11 The Liverpool HMRI boundary covers a wide area from Festival Park (Garden Festival Site) south of the city to the northern city boundary. It covers the City Centre and the inner areas as far east as Wavertree Park in the south and Anfield Cemetery in the north.

6.12 There is a small area to the north within Walton Hall Park which falls within an Environment Agency indicative flood risk area (zones 2 and 3).

6.13 In addition, Tue Brook and a small section of Lower Brook are also located within the HMRI boundary. As largely culverted watercourses, the condition of the culverts will be of particular importance in the areas that cross the watercourses. The only area that has suffered historical incidences of flooding is a small section of the Tue Brook north of West Derby Road, close to the eastern boundary. Comprehensive redevelopment of these areas may be an opportunity to reduce and manage the flood risk in these areas.

6.14 Within the HMRI area, smaller Zones of Opportunity are identified. Tue Brook runs through parts of these Zones, although not through any areas that have historical incidences of flooding.

6.15 Focusing on postcode areas with 2 properties and above which have suffered from sewer flooding, there is part of a postcode area (which has had between 4 and 12 incidences of sewer flooding) that overlaps with the boundary of the HMRI area and a zone of opportunity. The suitability of the sewer system for any additional development would need to be considered, although this is a consideration in all areas.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 51 - 6.16 In addition to the small areas identified that fall within a historical area of flooding or within the Environment Agency indicative flood risk areas; sewer flooding, flash flooding and groundwater flooding will need to be considered.

Strategic Investment Areas

6.17 There are five major areas in Liverpool which have been targeted for business investment and economic development. These are called the Strategic Investment Areas (SIAs).

Speke Garston SIA 6.18 Speke Gaston SIA in the south of Liverpool is not generally at risk. The river Mersey is not a threat as there are cliffs along the banks here. Over a longer term, there may be a risk due to climate change and erosion. This should be considered while developing the area especially given the plans for the expansion of Liverpool John Lennon Airport.

6.19 Speke Hall Drain and Brunswick Street Dock are located within the Speke Garston SIA which are both culverted. The Oglet is also located within this SIA. A historical incidence of flooding has been located within this area. Part of this flooded area is designated as a Site of Nature Conservation Value.

Liverpool City Centre SIA 6.20 The main known flood risk within this area is the River Mersey. Those developments that are in close proximity to the waterfront itself will be within the indicative Environment Agency flood risk areas. Similarly, areas further inland may be affected by flood in the future due to the effects of climate change (sea level rises), an extreme event or for example at the Pier Head where the flood defences are inadequate.

6.21 In addition, the main city centre area may be at risk from those sources identified in paragraphs 6.5 to 6.9 above.

Atlantic Gateway SIA 6.22 As with the City Centre SIA, the main known flood risk within the Atlantic Gateway SIA is along the River Mersey. The developments that are in close proximity to the waterfront itself will be within the indicative Environment Agency flood risk areas. Similarly, areas further inland may be affected by flooding in the event of an extreme event.

6.23 The World Heritage Designation and parts of the Leeds and Liverpool Canal are also within part of the Atlantic Gateway SIA (see paragraph 6.9 above).

Eastern Approaches SIA 6.24 Parts of the TueBrook fall within this SIA boundary. There are a significant number of historical incidences of flooding along the stretch of the Tue Brook, adjacent to Green Lane. The Tue Brook is culverted within this area and the condition of these culverts may affect the susceptibility to flooding. Any development within this area will need to mitigate against this issue, possibly

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 52 - through planning obligations. In addition, sewer flooding, flash flooding and groundwater flooding should be a consideration.

Gillmoss/Approach A580 SIA 6.25 The fifth area is the Gillmoss/Approach 580 SIA. This is a main flood risk area which contains the River Alt, brooks and lowland drainage. Nevertheless this is a key corridor into the city and also an area identified for major regeneration and investment. This area will need careful management (i.e. mitigation and defence solutions) given the possible conflict between the need for development and the risk of flooding.

6.26 The River Alt, Fazakerley Brook, Tue Brook, Croxteth Brook, Knowsley Brook and Sugar Brook all fall in part, within the boundary of this SIA and are identified within the Environment Agency indicative flood risk areas.

6.27 Provided the appropriate level of flood defence is in place, PPS25 considers that this type of area may be suitable 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, subject to the application of a sequential approach. Other developments, classed as ‘more vulnerable’ in Table D.2 of PPS25 would need to meet the ‘exception test’.

6.28 Some areas may already be protected due to levees and open spaces. As demonstrated in section 5, the condition of parts of the culverts in this area is considered to be poor. To ensure adequate flood defences, a detailed assessment would be required to assess the level of flood risk with any existing defences and the residual flood risk.

Other Development / Regeneration Priorities

Transport 6.29 Some main road corridors may be at risk of flooding, which can prevent movements into, out of and within the city. In addition, due to groundwater levels rising there may be a threat to the underground rail system. The main risk is for the lower parts of the city and the underground transport corridors.

6.30 Within the UDP, there are new road schemes, neither of which are located in an identified area of floodrisk. Access roads to new developments such as within the SIA’s and HMRI areas need to consider the level of flood risk to the access roads leading to and from the development.

Essential Civil Infrastructure 6.31 Essential civil infrastructure includes things such as hospitals, fire & police stations and schools. Feasibility work has been undertaken since the production of the UDP to consider alternative locations for some of Liverpool’s essential civil infrastructure. These facilities, particularly emergency services need to function normally in the event of floods as their role is to provide help when needed. New facilities should therefore not be built in flood risk zones and their access should not be compromised by any potential flood.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 53 -

6.32 There are currently no essential civil infrastructure buildings within areas of flood risk identified by the Environment Agency, although some access roads will be. Any plans for expansion to existing sites, such as Fazakerley Hospital, that are in close proximity to an area of flood risk need to be carefully considered within this context.

Sites allocated in Liverpool’s UDP which are yet to be implemented

6.33 As part of the Local Development Framework process, the existing UDP allocations which have not been implemented will be assessed to determine whether they are still appropriate and required, and therefore taken forward into the LDF. In the transition between the UDP and LDF, the UDP and policies within it are saved until September 2007 and may be extended further. These sites could also therefore come forward under the UDP. The following identifies sites located in areas of flood risk and assesses the level of acceptability of development in these areas. The proposal for development of each site would need to demonstrate how it complies with the sequential test.

Flood Risk Zone 3: 6.34 Major development sites: • Sites (over 4ha) for industrial/business development - Gillmoss Business Park (Site E6) – part of the site has been developed but a large proportion is still available for development and is currently open space in flood zone 3. With the ‘flood risk vulnerability classification’ within PPS25 Table D.2 industrial development on the site should be acceptable subject to adequate defences. In order to complete the development of the site, there may be a need to undertake a comprehensive masterplan and detailed Flood Risk Assessment. These might include: o the design of open areas (i.e. water compatible uses) within the parts of the business park that are in flood risk zone 3 o the consideration of flood defence measures such as levees o the impact of any development or flood defences on the risk of flooding elsewhere particularly downstream o as an existing open area, the need to consider the level of surface water run-off created and measures to reduce it o transport infrastructure may be required across the areas of high flood risk (i.e. road system) and should be designed accordingly

• Sites for Various Types of Development – Clarence Dock/Trafalgar Dock (Site M54) and Stanley/Salisbury/Collingwood Docks (Site M65) – the edge of this site is within floodrisk zones 2 and 3. As a major development site, consideration should be given to the design of the development and how this relates to the floodrisk. Different types of development within the overall development may be more acceptable than others in line with Table D.2 of PPS25 – Flood Risk Vulnerability Classification. To comply with PPS25, the exception test would therefore only need to be met for some types of development. For example residential development (on the whole) would need to meet the exception test whereas buildings for shops may not need to and basement dwellings would not be acceptable at all.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 54 -

In terms of meeting the exception test, this area should be in general conformity due to it being a large area of brownfield land a key location in terms of regenerating the city. However the specific details of any proposal would need to be considered against the exception test, considering for example transport links in terms of creating a sustainable community. A flood risk assessment will therefore be required for this site, including in particular minimum floor levels. Information within paragraphs 6.5 – 6.9 above should also be referred to.

6.35 Minor development sites: Parts of the following allocations fall within flood risk zone 3: • Housing Site H140 - Land adjacent Dorchester Park, Naylorsfield Drive • Housing Site H141 - Naylorsfield Drive/ BelleVale Pumping Station The exception test within PPS25 and the need for adequate flood defences for the lifetime of the development should be considered. These allocated sites are relatively small in size and approximately half of their area is within flood risk zone 3, therefore an assessment as to whether these allocations are required should be undertaken in any future review within the Local Development Framework process.

• Two small sites – part of a large allocation – Sites for Various Types of Development – Princes Dock (Site M3) remain unimplemented. These two sites are immediately on the waterfront and therefore floodrisk is an important consideration. As with sites M54 and M65 above, various types of development may be more acceptable than others with the exception test applying to certain types of development. With regards meeting the exception test, the location of these sites in closer proximity to the City Centre than M54/M65 ensures it is a sustainable location and again is on brownfield land. A flood risk assessment will be required for this site and it is essential that buildings comply with a minimum floor level (through advice from the Environment Agency). Again information contained within paragraphs 6.5 – 6.9 should be referred to.

Flood Risk Zone 2: 6.36 All of the following UDP allocations also fall within Flood Zone 3. It is a relatively insignificant area of land of each site that falls within flood zone 2 (with the possible exception of Gillmoss Business Park).

6.37 Major development sites: • Sites over 4ha for industrial/business development - Gillmoss Business Park (Site E6) – See flood risk zone 3 above. Within the masterplan and detailed Flood Risk Assessment, consideration should be given to the fact that the areas that fall within flood risk zone 2 are suitable for most types of development (excluding highly vulnerable uses which may need to meet the exception test) but measures should be taken to reduce the overall level of floodrisk elsewhere through the application of SuDS and to consider reducing floodrisk in the layout and form of the development.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 55 -

• Sites for Various Types of Development – Clarence Dock/Trafalgar Dock (Site M54) and Stanley/Salisbury/Collingwood Docks (Site M65) – see floodrisk zone 3 above. There is one particular part of this site that has a larger area within floodrisk zone 2.

6.38 Minor development sites: The areas of housing that fall within flood risk zone 2 are suitable for housing development subject to an adequate flood risk assessment and appropriate mitigation such as SuDS and careful design and layout. • Housing Site H140 - Land adjacent Dorchester Park, Naylorsfield Drive • Housing Site H141 - Naylorsfield Drive/ BelleVale Pumping Station Again, these allocated sites are relatively small in size and approximately half of their area is within flood risk zone 3, therefore an assessment as to whether these allocations are required should be undertaken in any future review within the Local Development Framework process.

• Two small sites – part of a large allocation – Sites for Various Types of Development – Princes Dock (Site M3) remain unimplemented. See flood risk zone 3 above.

Historical areas of flooding and sewer flooding

6.39 There are no unimplemented UDP allocations that are located in a historical area of flooding.

6.40 There are no unimplemented UDP allocations that are located in a historical postcode area of sewer flooding.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 56 -

7 Summary and conclusions

7.1 The main rivers in Liverpool are: • River Mersey/Mersey Estuary • Croxteth Brook • River Alt • Netherley Brook • Deys Brook (partial) • Halewood Brook • Sugar Brook • Childwall Brook (partial) • Fazakerley Brook • Knowsley Brook (located on the Liverpool/Knowsley boundary)

7.2 A large proportion of the ordinary watercourses in Liverpool are culverted and it is therefore difficult to determine exactly where the watercourses are. The ordinary watercourses identified in the 1989 Watercourse Flood Alleviation Study differ from those identified as part of the 1999 Culverted Watercourse Study. The 1999 study is more up-to-date and considered to be more reliable, however both sources of information are identified within the study.

7.3 The ordinary watercourses identified in the 1989 Watercourse Flood Alleviation Study are (some are not identified by name):

• Mab Lane Brook • Becher’s Brook • Thornhead Brook • Lower Brook • Hall Brook • Upper Brook • Deys Brook (partial) • Jordan River • Upper and Lower Tue Brook • Old Garston River • Oglet Brook • Childwall Brook (partial)

7.4 The ordinary watercourses identified in the 1999 Culverted Watercourse Study are: • Mab Lane Drain • Upper Jordan • Thornhead Brook • Old Garston River • Deys Brook (partial) • Oglet Brook • Upper and Lower Tue Brook • Childwall Brook (partial) • Upper Brook • Lee Park • Jordan River • Allerton Brook • Forty Pits Drain • Stamfordham Drive Drain • Brunswick Street Drain • Wavertree Culvert

7.5 A large number of these watercourses are substantially culverted.

7.6 With regards flood risk in Liverpool, the main identified risks and sources are as follows: • Condition of culverts – for which the key issues are: o exceptional storm rainfall o inadequate channel or culvert capacity o blockage of channel or culvert by silt or debris. Culvert screens are particularly prone to blockage even when regularly maintained.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 57 - o remote obstructions preventing flood water reaching channel or culvert e.g. blockage of gullies flowing into culverts, resulting in additional overland flow o structural failure

• Environment Agency Indicative Flood Risk Areas – river and tidal - only 4 % of Liverpool is classified as a flood risk zone from tidal and fluvial sources. The sequential approach (PPS25) should be applied to these areas

• Historical river flooding areas – additional ordinary watercourses have been identified that have flooded on a number of occasions in the past. This is only a limited number of areas but should be considered within any development proposals for the area

• Historical sewer flooding –postcode areas that have experienced internal or external sewer flooding have been identified showing a very low number of properties affected. Information regarding area at risk of sewer flooding is not currently available

• Groundwater – the water table is rising which could be an increasing issue. However, without detailing modelling it is not possible to identify specific areas. It is however thought that the City Centre and the Mersey Tunnels are of particular significance

7.7 Currently and in the future climate change is a key issue which is likely to increase the level of rain, storms, extreme weather and sea levels. In conjunction with climate change, urban development is likely to increase surface run-off. The level of flood risk within Liverpool will therefore rise in the future. A broad climate change allowance zone for the coastline has been identified. Any development within the climate change allowance zone will need to consider the level of flood risk over the lifetime of the development, potentially through a site specific flood risk assessment. Any development within main rivers flood risk zone 2 will also need to consider the impact of climate change.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 58 - Appendix A – Methodology and Sources of Information

This SFRA for Liverpool is essentially a desk-top study drawing together information from a wide range of sources and dates to build up a picture of the flood risk situation within Liverpool. The following steps were undertaken:

Step 1: Meeting with the Environment Agency

The Environment Agency are a key point of contact for undertaking a Strategic Flood Risk Assessment and a meeting was held in June 2006 to scope the extent of the investigation required within Liverpool.

It was agreed, subject to information obtained through the process of the study that the level of risk within Liverpool from watercourses was very limited and detailed hydrological modelling would not be required. The main gaps in information highlighted were with regards sewer flooding and groundwater.

Step 2: Data collection

Information was collected from the following sources: Meetings: o Environment Agency (identified in Step 1) o Liverpool 20/20 – Drainage o Emergency Planning – Liverpool City Council o Enterprise Liverpool & Liverpool City Council – Highways o United Utilities

Key Documents and information o Liverpool City Council - Watercourse Flood Alleviation Study (1989) o Liverpool City Council – Culverted Watercourse Study (1999) o Report to Liverpool City Council – Flooding to Liverpool 6 District of the City (1992) o DG5 Map register 2006 (United Utilities) o Historical information from Liverpool 20/20 Offices o Environment Agency – Groundwater information o Environment Agency – Flood Risk Mapping (River Alt) - Alt Defence data taken from NFCDD, Asset (Defences) references and overall condition, Section 105 Node points location maps, Level and Flow data, Flood History Layer for Liverpool Area, GIS o Liverpool City Council – Policy Statement on Flood and Coastal Defence – Draft 2001 o DCLG – Planning Policy Statement 25: Development and Flood Risk (2006) http://www.communities.gov.uk/index.asp?id=1504639

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 59 -

Other useful sources of information include:

Websites: - British Geological Survey: - Mersey docks: http://www.bgs.ac.uk/ http://www.merseydocks.co.uk/ Maps and geological data Data about the state of the walls and responsibilities - Department of Environment, Flood and Rural Affairs: - Mersey gateway: http://www.defra.gov.uk http://www.mersey-gateway.org/ Data and guidance about flood Historical data

- Environment Agency: - National Flood Forum: http://www.environment-agency.gov.uk/ http://www.floodforum.org.uk/ Data about flood risk, flood defences, flood risk “Flood resilience through partnership” zones, alleviation and protection measures. - Office of Water Services: - Flood risk management research consortium: http://www.ofwat.gov.uk/ http://www.floodrisk.org.uk/ Information about water companies Information about flood risk - Proudman Oceanographic Laboratory and - Glasgow University: National Tidal and Sea Level Facility: http://www.archives.gla.ac.uk/about/dunaskin/2 http://www.pol.ac.uk/ 003-04/edition6/storms.html Information about tides, flows etc. Dunaskin News – 2003 – 2004 – edition 6 – Hurricane affecting Liverpool 1839 - Sefton Coast: http://www.seftoncoast.org.uk/ - IcLiverpool: Information relating specifically to the http://icliverpool.icnetwork.co.uk/ Sefton Coast Various newspaper article about localised flooding in Liverpool Liverpool City Council, 2006, Core Strategy Issues and Options Paper - Laver publishing: http://www.liverpool.gov.uk/Environmen http://www.laverpublishing.com t/Planning/Local_Development_Framewor Provide tide tables k/work_in_progress/core_strategy_dpd/in dex.asp - United Utilities: http://www.unitedutilities.com Information about sewers and water supply

Other documents:

CRU (Climatic Research Unit), October 1998, Home Office Government, 2005, Emergency Climate Change Scenarios for the United Kingdom Preparedness, Guidance on part 1 of The Civil Scientific Report, UK Climate Impacts Programme, Contingency Act 2004, its associated regulations and Technical Report No.1, University of East Anglia, non statutory arrangements, Crown Copyright, York, Norwich, p44. p230

CRU (Climatic Research Unit), OSBORN T., 2001, MLRF (Merseyside Local Resilience Forum), 2006, Information sheet 15: “Changing intensity of rainfall Community Risk Register, Merseyside Emergency over Britain”, University of East Anglia, Norwich, Planning, p32. (Available on: p7. http://www.merseyfire.gov.uk/)

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 60 - CRU (Climatic Research Unit), RAPER S., 2000, EA (Environment Agency), 2006, Strategic Flood Risk Information sheet 10: “Sea Level Rise”, University Assessment - Interim Guidance, Environment Agency, of East Anglia, Norwich, p4. Warrington, p10.

DEFRA, March 2005, Making space for water: Taking DCLG, 2005, Planning Policy Statement 1 – Delivering forward a new Government strategy for flood and Sustainable Development coastal erosion risk management in England, First Government response to the autumn 2004, p46. DCLG, 2007, Planning Policy Statement: Planning and Climate Change - Supplement to Planning Policy DEFRA Flood Management (dir.), June 2005, The Statement 1 Threat posed by Tsunami to the UK, DEFRA London, p170. Environment Agency and NWRA, 2004, Meeting the Sequential Flood Risk Test Salford City Council and JBA Consulting, 2005, City of Salford Strategic Flood Risk Assessment, Final Atkins Consultants (on behalf of Liverpool City report, Salford City Council, Salford, p66. Council ) 2005, Liverpool Open Space Study

EA (Environment Agency), 2005, Multi-Agency Plan NWDA, 2006, Rising to the Challenge – A Climate to Flooding for the Merseyside Area, EA, Change Action Plan for England’s Northwest Warrington, p38. (Consultation Draft)

EA (Environment Agency) March 2007, National SUDS Working Group, July 2004, Interim Draft Mersey Estuary Catchment Flood Code of Practice for Sustainable Drainage Systems Management Plan, Environment Agency, Bristol http://www.environment- CIRIA, 2004, Development and flood risk - guidance agency.gov.uk/regions/northwest/1072087/1697828 for the construction industry (C624) /?version=1&lang=_e Flood Risk Standing Advice for England (PPS25) version 1.0 – Environment Agency (March 2007)

Step 3: Data Analysis

The information has been brought together to provide an overview analysis of the flood risk situation in Liverpool according to the information known. It is recognised that it is a desk-top study only and that some of the data is out of date (although in some cases the situation is unlikely to have changed considerably).

However, due to the different agencies involved with flood risk, this is the first attempt to comprehensively draw together the information and map it, making strategic spatial conclusions.

Step 4: Consultation with partners and interested bodies

Consultation has been undertaken with the following bodies: Liverpool City Council o Emergency Planning Manager o Business Manager - Environmental Health & Trading Standards o Contaminated Land Liverpool 2020 and Liverpool Engineering o Engineering Consultant

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 61 - Enterprise Liverpool: o Culverts and Highway drainage Environment Agency: o Planning Liaison Technical Specialist o Strategy Manager o Mersey Catchment o Groundwater o Development Control (Mersey) o Development Control (Alt) o Alt catchment United Utilities (sewers floods) o Flooding Manager - Wastewater Network Strategy Team o Asset Protection Mersey Ports Government Office North West Adjoining Authorities – Sefton Council and Knowsley Metropolitan Borough Council

Amendments have been made to the document following the comments received from the above agencies and officers. A schedule of comments and the Council response is available on request from the development plans team ([email protected]). It should be noted that the Environment Agency consider that ‘the general overall sufficiency of the draft document for planning and flood risk purposes appears good’.

The limitations of the study are identified as follows. Where a detailed flood risk assessment is required, consideration of the need for more detailed data within these areas should be considered:

Updated information on culverts – where they are, the condition and capacity. Information included within this study identifies where they are and the condition where known, according predominantly to 1999 data. Information is also available as to the size and length of the culvert within the 1999 study if required

Risk of sewer flooding and capacity – the DG5 maps supplied by United Utilities only show the incidences of flooding that have occurred. They do not however show the risk of flooding based on the existing capacity of the sewer system. A detailed assessment of hydrologic models for sewer catchments, linked with overland flow surveys and LIDAR data should be undertaken.

Hydrological modelling of the watercourses – calculating the speed and depth of watercourses. However this was not considered necessary in light of the limited main watercourses within Liverpool and therefore level of flood risk

Groundwater – only limited data was available regarding the groundwater situation in Liverpool

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 62 - Appendix B – Guidance for Developers and Development Control

The susceptibility of land to flooding is a material consideration in determining planning applications. Applicants for planning permission should therefore assess the risk posed by the development.

This SFRA document, particularly section 5 and associated maps provides the basis for flood risk decision making. However it is a strategic document which provides guidelines only.

Guidance for all development proposals: All development proposals in Liverpool should consider the following:

1. The impact of the development on surface water run-off through a Surface Water Runoff Assessment

2. Incorporating Sustainable Drainage methods (SuDS), where possible

3. A consideration of the impact of the development on the identified flood risk issues (see section 5) and a consideration of other potential flood risks – including all sources – tidal, river, streams, ditches, sewers, groundwater, overland surface water flow or any combination of these

4. The application of the sequential and exception test of PPS25

5. The need for any development proposal to consider whether a Flood Risk Assessment is necessary as part of the planning application process

These issues will be of particular importance for: a. larger sites (e.g. greater than 1ha) in Flood Risk Zone 1 (areas that are not shaded on Maps 4a and 4b) b. all development within Flood Risk Zones 2 and 3 (areas shaded blue on Maps 4a and 4b) c. development on large areas of greenspace, impacting on levels of flood downstream (areas shaded green on Map 10) d. Areas historically at risk from flooding (Map 6) and areas that have been affected by sewer flooding (Map 8) e. Sites within a climate change allowance zone

6. The potential risk from groundwater. This issue will be of particular importance for development in the City Centre.

1 PPS25 and the Flood Risk Standing Advice for England (PPS25) should be referred to with associated technical guidance notes to determine whether a Flood Risk Assessment (FRA) is required. As a rough guide - all development in Flood Risk Zones 2 and 3 require a flood risk assessment and any development proposals of 1 hectare or greater in flood risk zone 1 (see also Table A below).

1 Flood Risk Standing Advice for England (PPS25) version 1.0 – Environment Agency(March 2007)

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 63 -

The detail and technical complexity of all FRA’s depends on the location and scale of development. Construction Industry Research Information Association (CIRIA) publication C624 Development and Floodrisk – guidance for the construction industry defines three levels of FRA which can be undertaken. The Practice Guidance to PPS25 also sets out the key outputs of a site-specific Flood Risk Assessment.

Where new development is planned within an area adjoining any watercourse, consideration should be given to ensuring improvement works are carried out as required on the particular watercourse, for example improvements to the capacity or maintenance of a culvert. The potential impact of the development on all sources of flooding should be considered as whilst the flood risk may not be increased at the development site itself, it may increase the risk elsewhere. This could be achieved through a planning obligation or through agreement with developers.

The Draft Practice Guidance to PPS25 (2007) states that the developer is not required to apply the Sequential Test if a proposed development is located on a site which has been allocated for that type of development in a LDD that has been sequentially tested and supported by a SFRA. However the developer should still apply the sequential approach to any flood risk within the site itself when determining the location of appropriate land uses. Liverpool City Council have not commenced work on the Site Allocations DPD and is not at the stage of allocating sites within the Area Action Plans. Therefore no sites can be considered to have undergone this process and therefore, all proposals should be assessed on a site by site basis by the developer.

Specific guidance for Flood Risk Zones 2 and 3 – applying the sequential test to Liverpool:

Points 1 to 6 above have great importance in flood risk zones 2 and 3. The following provides Liverpool specific guidance that should be adhered to alongside national guidance.

Flood Risk Zone 3 – High Risk:

The preference within this area will be for development to occur on lower risk sites and this should be considered.

For flood risk zone 3a, water compatible and less vulnerable uses (see table D.2) will generally be acceptable, more vulnerable uses and essential infrastructure require the ‘exception test’ being applied and highly vulnerable uses are not acceptable. Where the exception test is applied, the onus is on the developer to demonstrate that the exception test has been met. Development within flood risk zone 3, as with the rest of the city should be focused onto previously developed land.

The following issues are of particular significance in Liverpool: There is a large amount of previously developed land in Liverpool – developing on a site that is both Greenfield and located within Flood Risk Zone 3 should therefore be highly exceptional There is only a limited area located within flood risk zone 3 and as such alternative sites to those located in flood risk zone 3 should be considered

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 64 - wherever possible and water compatible development including recreation, sport, conservation and amenity uses should be prioritised The City Centre of Liverpool is a key focus for development and investment, with the waterfront as a key asset. There are therefore likely to be less suitable alternative sites. Development along the waterfront should accord with the requirements of PPS25 and as part of the flood defence measures should include a minimum floor level

Minimum floor levels The current advice (June 2007) from the Environment Agency with regards minimum floor levels for development in Flood Risk Zones 2 and 3, is as follows: • Floor levels to be set at the minimum of the 1 in 200 year level plus climate change over the life of the development plus 600mm freeboard • Using the precautionary approach specified in section 5 of the main SFRA report and the lifetime of commercial development at 67 years and residential at 107 years. • The required floor levels are therefore: Residential = 7.39 metres AOD + 600mm freeboard = 7.99metres AOD Commercial = 6.9metres AOD + 600mm freeboard = 7.5m AOD

This is based on 2006 Extreme Tide Levels (Gladstone Dock) – Royal Haskoning and will need to be updated regularly.

All development proposals should be accompanied by a detailed Flood Risk Assessment. Developers and local authorities should seek opportunities to reduce the overall level of flood risk in the area through the layout and form of the development and the appropriate application of sustainable drainage techniques.

Flood Risk Zone 2 – Low to Medium Risk

In many circumstances within Liverpool, flood risk zone 2 is only a minor extension of flood risk zone 3. Therefore, those development proposals that are within flood risk zone 2 are likely to have parts of the development within flood zone 3.

Development is generally acceptable within this flood risk zone with essential infrastructure, water compatible uses, more vulnerable and less vulnerable uses all being generally acceptable. Highly vulnerable uses will need to meet the exception test. The preference within this area will be for development to occur on lower risk sites (flood risk zones 1) and this should be considered.

PPS25 highlights that ‘highly vulnerable’ uses need to pass the exception test before development is allowed. This includes: Essential civil infrastructure, such as police stations, fire stations etc. should not be built within flood zone 2 or 3. Access to these facilities should also not be cut off by floods. Basement dwellings Caravans, mobile homes and park homes intended for permanent residential use

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 65 -

Minimum floor levels as described above with regards flood risk zone 3, also apply in flood risk zone 2.

All development proposals should be accompanied by a Flood Risk Assessment. Developers and local authorities should seek opportunities to reduce the overall level of flood risk in the area through the layout and form of the development and the appropriate application of sustainable drainage techniques.

Areas historically at risk of river flooding and sewer flooding These areas do hot have the same status as those identified within the Environment Agency indicative flood risk areas. This is because they are not from main rivers and therefore outside of the Environment Agency’s responsibilities.

These areas may be of key importance in determining development proposals but this is also where the accuracy and reliability of the data is not fully known. It is also not fully comprehensive.

As such, the advice for these areas is: Undertake a flood risk assessment, paying particular regard to either the watercourse or sewer system dependent on what the risk is in that area Consult with the Environment Agency in areas of historical flooding and United Utilities in areas of historical sewer flooding Consider whether improvements can be made to the existing system as part of the development proposal

Consultation: The location and scale of the development will also determine whether other bodies (i.e. Environment Agency, Drainage (Liverpool 20/20) and United Utilities) need to be consulted. The flow diagram in section 4 should help to determine the different agencies that should be involved.

The Environment Agency Flood Risk Standing Advice should also be referred to, which provides advice about when to consult the Environment Agency. The following table is taken from the Standing Advice and provides an overview. Developers should also liaise with Liverpool City Council to agree on who should be consulted and refer to paragraphs 26 – 29 of PPS25.

Table A: Extract from Environment Agency Standing Advice A1 B1 Within 20 C1 Includes D1 Within Flood E1 Within Flood F1 Within Development metres of culverting or Zone 3 Zone 2 Flood Zone 1 Category the top of control of bank of a flow of any Main River river or stream A2 Householder B2 Consult EA C2 Consult EA D2 No E2 No F2 No development with FRA with FRA consultation – consultation – consultation and alterations see EA see EA – No EA standard standard Advice comments comments within Standing within Standing

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 66 - advice advice A3 Non- B3 Consult EA C3 Consult EA D3 No E3 No F3 – No residential with FRA with FRA consultation – consultation – consultation extensions less see EA see EA – No EA than 250m2 standard standard Advice comments comments within Standing within Standing advice Advice A4 Change of use B4 Only C4 No D4 Consult EA E4 No F4 No FROM water consult EA if consultation with FRA consultation – consultation compatible TO site falls – no EA No EA advice – No EA ‘less vulnerable’ within Flood advice advice development Zone 3. FRA Required A5 Change of use B5 Only C5 No D5 Consult EA E5 Consult EA F5 No RESULTING IN consult EA if consultation with FRA with FRA consultation ‘Highly site also falls – no EA – No EA Vulnerable’ or within Flood advice Advice ‘More Zone 3 or 2. Vulnerable’ FRA Required development A6 Operational B6 Consult EA C6 Consult EA D6 Consult EA E6 Consult EA F6 No development with FRA with FRA with FRA and with FRA and consultation less than 1 (and also if Sequential Test Sequential Test – see EA hectare in Flood Zone Evidence (and evidence (and standard 3 Sequential where required where required comments Test confirm confirm within Evidence) Exception Test Exception Test Standing has been has been Advice applied) applied) A7 Operational B7 Consult EA C7 Consult EA D7 Consult EA E7 Consult EA F7 Consult EA development of with FRA with FRA with FRA and with FRA and with FRA hectare or (and also if Sequential Test Sequential Test greater in Flood Zone Evidence (and Evidence (and 3 Sequential where required where required Test confirm confirm Evidence) Exception Test Exception Test has been has been applied) applied) Reproduced from: Flood Risk Standing Advice for England (PPS25) version 1.0 – Environment Agency (March 2007) © Crown Copyright 2007.

Sustainable Drainage Systems (SuDS): Development reduces surface permeability by replacing vegetated ground with roofs and paved areas and through compaction of other areas by vehicular movements. This reduces the amount of water infiltrating into the ground and increases surface run-off. Any built-up area, therefore, needs to be drained to remove excess water. In Liverpool, as elsewhere, this has traditionally been done using underground pipe systems designed for quantity, to convey water away as quickly as possible and thus prevent flooding locally. This increases the speed of run-off and can change the flooding regime of the catchment.

Amenity issues, such as water resources, community facilities, landscaping potential and the provision of wildlife habitats have largely been ignored in past planning and

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 67 - design of drainage systems. Continuing to drain built up areas without taking these wider issues into consideration is not seen as a sustainable long-term option.

Surface water drainage methods that take account of the quantity and quality of water as well as amenity issues are known as Sustainable Drainage Systems (SuDS). These systems are different to conventional drainage methods because they help to control the quantity and improve the quality of run-off water from developments (and thus help towards flood prevention) and at the same time contribute towards nature conservation, landscape improvements and the appeal of a site and its surroundings.

Sustainable drainage systems use techniques to control surface water run-off as close to its origin as possible, before it enters a watercourse. This involves moving away from traditional piped drainage systems to engineering solutions that mimic natural drainage processes.

A number of techniques come under the banner of SuDS including: balancing ponds, reed beds, infiltration devices, rain water recycling and porous paving materials.

PPS25 (Annex F) states that “the surface water arrangements for any development site should be such that the volumes and peak flow rates of surface water leaving a developed site are no greater than the rates prior to the proposed development, unless specific off-site arrangements are made and result in the same net effect”.

It is essential that the ownership and responsibility of maintenance of every sustainable drainage element is clear. This should be addressed as part of the Flood Risk Assessment.

Currently, United Utilities policy is not to adopt SuDS (Sustainable Drainage Systems) structures. This stance has been taken as SuDS structures, typically ponds, do not align with United Utilities asset base and would represent a substantial maintenance liability.

United Utilities will only consider the adoption of surface water sewers draining to a balancing pond (as opposed to any other SuDS structure), providing the following conditions are met: - The Local Authority takes responsibility for the maintenance of the pond The freehold of the land on which the pond lies is transferred to the Local Authority United Utilities is provided with a deed of "Grant of Rights" to discharge into the pond in perpetuity. Such a deed would necessarily contain provisions against development within the balancing pond, and against altering its topography, or making connections to it. That measures have been taken to prevent flooding of properties That a legal agreement is in place between all parties.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 68 - A Section 104 (Water Industry Act 1991) agreement for the surface water sewers draining to the balancing pond will not be entered into until every condition described above has been met.

Prior to the approval of any planning application incorporating SuDS features, a meeting must be arranged to formally discuss the proposal. Any such meeting should include a representative from United Utilities, the Local Authority Drainage Department and the applicant.

There are alternative long term management solutions available through companies that provide this as a specific service.

To manage and reduce future flood risk, it is important SuDs are incorporated into new developments wherever possible. Further information is available within Appendix F of PPS25. In addition, reference should be made to the Interim Code of Practice for Sustainable Drainage Systems19

19 Interim Code of Practice for Sustainable Drainage Systems – National SUDS Working Group – July 2004

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 69 - Appendix C – RSS and Core Strategy Issues and Options Appraisal

Regional Spatial Strategy for the North West The following table appraises the existing North West Regional Spatial Strategy (Draft and Adopted) – Spatial Framework which sets out the regional priorities for development. The appraisal considers the impact of these priorities on the level of flood risk in Liverpool and also the level of new development proposed in areas of risk. This is then assessed as to the level of compatibility with this SFRA.

Policy Brief description and key Compatibility with findings of SFRA principles of the policy SD1(Adopted RSS) – Both policies focus The level of flood risk within Liverpool is relatively limited from ! North West Metropolitan development within Liverpool. rivers and tidal at the present time, particularly in the context of Area – Regional Poles The Adopted RSS focuses on other authority areas within the North West. The impacts of climate and Surrounding Areas NW Metropolitan Area change may exacerbate this situation. including the City Centre and RDF1 (Draft RSS) – Main surrounding inner area. Adopted RSS focuses on the City Centre and surrounding inner area. Development Locations Adopted RSS - Conserve These areas are considered in section 6, regarding the City Centre distinctive architectural and the HMRI area. Although some areas of flood risk were heritage and encourage high identified, predominantly the River Mersey, it is not considered that quality new developments and this should stop all development, but that a sequential approach to greenery each development is applied. Draft RSS – maximizing growth opportunities, promoting As the level of risk from other sources including sewer and environmental excellence and groundwater is not fully known it is not possible to determine providing for a range of local whether the focus of development in Liverpool is entirely compatible facilities and services with the SFRA. However, Liverpool is a highly urbanized area already with a large proportion of development occurring on previously developed land. The grounds of sewer and groundwater flooding are not considered strong enough to prevent development at this strategic level.

Overall conclusion – providing the different flood risks (and the sequential test of PPS25) are taken into account and where appropriate more detailed flood risk assessments are undertaken, this approach is not in conflict with the SFRA

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 70 - SD5 (Adopted RSS) The Adopted RSS Identifies The Green Belt’s continued protection may have benefits as a large ! Green Belts the need for a Strategic study. open area acting as a storage basin, for example Croxteth Park The Draft RSS, having done a acting as a storage basin for the River Alt and to ensure levels of RDF5 (Draft RSS) Green study identifies no substantial surface water run-off is not increased. Belts changes are required until at least 2011 when another Retention of the Green Belt is not in conflict with the SFRA. strategic study should be undertaken SD7 (Adopted RSS) North Adopted and Draft RSS focus As with the Green Belt the focus on protecting the currently ! West Coast on need to conserve and undeveloped parts of the coastline may have benefits in ensuring enhance natural, built and that surface water run-off levels are not increased. Flood risk is also heritage assets recognized within both policies (as integrated water management Adopted RSS - respect within the Draft RSS). RDF4 (Draft RSS) The changing physical nature of There is still however a focus on regenerating and continuing to Coast the coastline, recognize flood develop the developed parts of the coastline. As long as the risk potential flood risk in this area is taken into consideration, including Draft RSS – protection and raised floor levels, this approach is not in conflict with the SFRA. diversification of maritime economy, regeneration – sustainable growth in tourism & regeneration and the regeneration of the developed/undeveloped coast, safeguard undeveloped coastline, promote integrated planning and management SD9 (Adopted RSS) Well planned and effective Careful consideration should be given to access to areas and the ! Regional Transport transport system level of flood risk to the roads. These can act as strategic corridors Strategy into and around the city ensuring access for residents and visitors and flooding of these roads could have significant consequences. Any changes or improvements to the existing system should consider the likelihood of flooding and the impact on surface water run-off levels. This policy is not in conflict with the SFRA but in implementing the policy, the findings of the SFRA need to be taken into account.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 71 - Liverpool City Council – Local Development Framework – Core Strategy Issues and Options – Key Development Principle 1: Spatial Development The following table appraises the issues and options for the Core Strategy – Key Development Principle 1: Spatial development, put forward within the Issues and Options Paper20. Part of the role of this SFRA is to contribute to the Sustainability Appraisal of the Local Development Framework. As the Core Strategy progresses, the subsequent ‘preferred options’ will need to be assessed in light of this SFRA. Similarly options produced for other emerging documents will need to be assessed against this SFRA.

Key development principle 1: Spatial development identifies the broad locations for various types of new development. It was considered that the approach should be informed by the issues of: Regeneration needs of the area, Ensuring development is accessible and Ensuring that Liverpool’s open environment is safeguarded. The following assesses each of these issues and associated options for the impact that it will have on flood risk, providing an overall assessment according to the following scores:

☺ Positive impact on reducing the level of flood risk/ mitigation No major negative impacts on the level of flood risk. Approach not in conflict with the SFRA Negative impact on the level of flood risk ? Not possible to identify the impact

Core Strategy: Core Strategy: Options Impact on flood risk Issue The Core Strategy A – Direct major residential Significant development could have a negative impact on the level of flood risk should identify and commercial due to increased surface water run-off. However the city is already areas of priority development in areas with predominantly urban and this option would utilise brownfield land because investment based the most pressing much of the available land in the Housing Market Renewal Initiative (HMRI) on their regeneration needs areas and the Strategic Investment Areas (SIAs) has been previously developed. regeneration needs (e.g. the City Centre,

20 Core Strategy Issues and Options Paper – Liverpool City Council (2006) http://www.liverpool.gov.uk/Environment/Planning/Local_Development_Framework/work_in_progress/core_strategy_dpd/index.asp

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 72 - Strategic This option focuses mainly on the areas identified in section 6, Housing Market Investment Renewal Initiative Area (HMRI) and Strategic Investment Areas (SIA). The Areas, and greatest known flood risk issues are in the Strategic Investment Area to the Housing Market north east of the city (Gillmoss/A580) where the River Alt meets the Renewal Fazakerley Brook, Croxteth Brook and Knowsley Brook. Pathfinder). It should: A small part of the HMRI area is affected by other ordinary watercourses, particularly the Tue Brook (and a small section of the Lower Brook). Parts of this watercourse to the east of the HMRI boundary has experienced a relatively significant number of flooding incidences. However these areas are already built up and new development/clearance may provide an opportunity to improve the level of flood risk.

Overall conclusion – the level of flood risk city-wide is relatively low. Providing the different flood risks (and the sequential test of PPS25) are taken into account and where appropriate more detailed flood risk assessments are undertaken, this approach is not in conflict with the SFRA. This is particularly the case in the Gillmoss SIA area. B – Direct major residential Significant development could have a negative impact on the level of flood risk and commercial due to increased surface water run-off. However the city is already development to areas predominantly urban and this option would utilise brownfield land because requiring regeneration, much of the available land in the City Centre, HMRI and SIAs has been and which are linked to previously developed. areas of high unemployment by good This option focuses on the areas within option A (i.e. Housing Market Renewal quality public transport Areas and Strategic Investment Areas) but also includes the city centre and a broader range of areas within inner Liverpool and the north eastern and southern parts of the city. This option includes areas of high unemployment and with good transport links. As with option A, this option involves development in the SIA (Gillmoss/A580). In addition, this option involves substantial development along the River Mersey to the north of the city and the very south tip. The extent of the flood risk in these areas is limited inland and although mitigation measures will be required, this should not stop development occurring.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 73 - Again, as with option A, this option will also be affected by other ordinary watercourses, particularly the Upper and Lower Tue Brook to the north of the city. Parts of this watercourse have experienced a relatively significant number of flooding incidences. However these areas are already built up and new development/clearance may provide an opportunity to improve the level of flood risk.

Overall conclusion – the level of flood risk city-wide is relatively low. Providing the different flood risks (and the sequential test of PPS25) are taken into account and where appropriate more detailed flood risk assessments are undertaken, this approach is not in conflict with the SFRA. This is particularly the case in the Gillmoss SIA area. C – Do not identify areas of This option does not identify any specific areas for development and it is not ? priority investment based therefore possible to determine whether this will have a negative impact on solely on regeneration floodrisk in Liverpool. The findings of this SFRA would need to be taken into needs. account when determining proposals for development across the City.

The Core Strategy A - Encourage This option would lead to development predominantly within the city centre, should identify development that radial routes out of the city centre and at transport interchanges within the areas of priority generates a large amount city such as Wavertree Technology Park. The main area that is located within investment based of movement to occur an area of flood risk is the City Centre, for which mitigation measures would on their only in areas of the be required. accessibility by highest existing public This option does not have any major negative impacts on flood risk. the choice of transport accessibility. transport modes B - Give clear priority to This option would lead to development predominantly within the city centre. available. (e.g. the city centre over other As an area of flood risk, mitigation measures would be required. the City Centre, areas for the development This option does not have any major negative impacts on flood risk. district and local of visitor-intensive centres, and employment or retail transport activity. interchanges). It C - Adopt a flexible New investment in transport infrastructure and new development areas needs ? should: approach, which allows for to consider whether it is in an area of flood risk. Flooding of roads can cut off new development to take access to and from areas and is an important consideration. The findings of place in combination with this SFRA would need to be taken into account when determining proposals for investment in new development and new roads across the City. transport infrastructure.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 74 - D – To not identify areas of This option does not identify any specific areas for development and it is not ? priority investment based therefore possible to determine whether this will have a negative impact on solely on transport floodrisk in Liverpool. The findings of this SFRA would need to be taken into accessibility. account when determining proposals for development across the City. The Core Strategy A – Protect all areas with By identifying all areas of open space for protection, this option could have a ☺ should identify open landscape value positive impact on the level of floodrisk by ensuring that open spaces that environmentally against inappropriate currently act as a storage basin can continue to do so and in protecting from sensitive areas development development ensure that surface water run-ff levels are not increased. that require B – Identify strategic areas Strategic open spaces could arguably have a greater impact on flood risk as a ☺ protection of open and natural space storage basin simply due to their larger strategic size. Their impact will against and resist inappropriate however be limited by their location, with the sites of greater impact on flood inappropriate development within these. risk being Croxteth Park (Green Belt) and the Green Belt to the south of the development New open space should city near to Liverpool John Lennon Airport. As with option A, protecting (e.g. green belt, strengthen linkages strategic open spaces will ensure their role continues, if they currently act as a open space, between these areas storage basin and reducing surface water run-off. However, by only identifying parks). It should: strategic sites, other open space sites which also act as a storage basin may be at risk of development. This option also suggests new open spaces which could further reduce surface water run-off and provide a storage basin role dependent on its location. C – Do not identify By not identifying sites for protection, they may be at risk of inappropriate environmentally sensitive development. This could exacerbate existing flood risk areas by increasing areas requiring protection surface water run-off and reducing the amount of open space acting as a storage basin.

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 75 - Liverpool City Council – Local Development Framework – Core Strategy Issues and Options – Issues relating to flood risk The following table appraises the issues and options for the Core Strategy put forward within the Issues and Options Paper21. There are two issues which directly deal with the approach to flood risk. These are assessed using the findings of the SFRA as follows:

Core Strategy: Core Strategy: Options Impact on flood risk Issue The Core Strategy A - The Core Strategy should This option does not accord with national planning policy guidance (PPS25) and should control include a prudent avoid all therefore this SFRA. As section 6 and appendix B of this SFRA identify, even in the development in development in areas of flood areas of highest risk, some development may be appropriate if adequate flood identified areas of risk defences are in place and in line with PPS25, the sequential test and exception test flood risk are met. To comply with this SFRA, this option would need to be more flexible applying the sequential approach to the identified areas of flood risk. B - Development in areas of This option does not accord with national planning policy guidance (PPS25) and flood risk will be permitted therefore this SFRA. As section 6 and appendix B of this SFRA identify some types of providing measures are included development may not be appropriate according to the application of the sequential that reduce the risk of flooding test and the exception test; it is not simply a case of ensuring adequate flood including consequential risks defences (although this is an important mitigation measure). elsewhere To comply with this SFRA, this option would need to apply the sequential approach and exception test of PPS25 to development sites, using the findings of this SFRA, rather than allowing development in all areas. The Core Strategy A - The Core Strategy should As a predominantly urban area with surface water run-off as one of the main potential should encourage encourage the use of Sustainable flood risks within Liverpool, the implementation of SuDS is considered to be drainage Urban Drainage Systems (SuDS) in important. Encouraging the use of SuDS in all new developments is therefore in line techniques that all new development with this SFRA, as indicated in appendix B. reduce the risk of B - Targets for new development As for option A, SuDS techniques are an important flood prevention or management flooding incorporating SuDS, either by use technique within such an urban area. This SFRA does not go to the level of detail as (e.g. residential, commercial) or to recommend targets for incorporating SuDS, however it does indicate that all new within particular parts of developments should consider the implementation of SuDS (Appendix B) and a target Liverpool, should be included based approach may deter from this. Appendix B also indicates that the within the Core Strategy implementation of SuDS is particularly important in existing flood risk areas

21 Core Strategy Issues and Options Paper – Liverpool City Council (2006) http://www.liverpool.gov.uk/Environment/Planning/Local_Development_Framework/work_in_progress/core_strategy_dpd/index.asp

Liverpool City Council – Strategic Flood Risk Assessment January 2008 - 76 -