1.1.1.1 LP/Ev/9f

Bracknell Forest Borough Council Level 2 SFRA

Final Report

September 2019

Bracknell Forest Council Time Square Market Street BRACKNELL Berkshire RG12 1JD JBA Project Manager Anna Beasley 8a Castle Street WALLINGFORD Oxfordshire OX10 8DL Revision History Revision Ref / Date Issued Amendments Issued to Draft v1.0 / 11 Jan 2018 Marie O'Sullivan, Julia Greene Draft Final v2.0 / 13 June Comments from Bracknell Marie O'Sullivan, Julia 2018 Forest Council Greene Final v3.0 / 11 January 2019 Comments from Bracknell Natalie Hird, Julia Greene Forest Council and inclusion of additional sites Final v4.0 / 16 July 2019 Comments from Bracknell Natalie Hird, Julia Greene Forest Council, inclusion and removal of sites. Final v5.0 / 05 September Comments from Bracknell Natalie Hird, Julia Greene 2019 Forest Council Contract This report describes work commissioned by Bracknell Forest Council by an email dated 3 October 2017. Bracknell Forest Council's Representative for the contract was Marie O'Sullivan. Anna Beasley, Paul Eccleston, Anna Hastings and Cheryl Briars of JBA Consulting carried out this work.

Prepared by ...... Cheryl Briars BSc MSc Assistant Analyst

...... Anna Beasley BSc MSc CEnv MCIWEM C.WEM Technical Director

Reviewed by ...... Paul Eccleston BA CertWEM CEnv MCIWEM C.WEM Technical Director

Purpose This document has been prepared as a Final Report for Bracknell Forest Council. JBA Consulting accepts no responsibility or liability for any use that is made of this document other than by the Client for the purposes for which it was originally commissioned and prepared. JBA Consulting has no liability regarding the use of this report except to Bracknell Forest Council.

2016s5363 - Bracknell Forest Council - SFRA L2 Final Report v5.0 (Sep 2019) i Acknowledgements With thanks to Marie O'Sullivan and Julia Greene (Bracknell Forest Council), Clark Gordon (Environment Agency), and Thames Water. Copyright © Jeremy Benn Associates Limited 2019 Carbon Footprint A printed copy of the main text in this document will result in a carbon footprint of 82g if 100% post- consumer recycled paper is used and 105g if primary-source paper is used. These figures assume the report is printed in black and white on A4 paper and in duplex. JBA is aiming to reduce its per capita carbon emissions.

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Executive Summary Bracknell Forest Council is undertaking the preparation of a new Bracknell Forest Local Plan (BFLP). As part of this process it is preparing an evidence base which will support the policies and allocations included in the document. This Level 2 Strategic Flood Risk Assessment (SFRA) is one piece of the evidence base, which will help to inform policy development and the selection of site allocations for inclusion within the BFLP. On the basis of the Level 1 SFRA and the Sustainability Appraisal (SA), the Council identified that all the necessary development required over the plan period cannot be accommodated by sites identified as being at low flood risk from all sources (noting that the SA process discounted some low risk sites on other planning grounds), and additional sites would be required to enable delivery of the level of development set out in the BFLP. The Council therefore progressed to a Level 2 SFRA for 28 sites and 3 Clusters to provide further detail and development solutions for prescribed sites and for the application of the Sequential and Exception Test (if required). The Level 2 SFRA draws upon all the information and data sources that were compiled as part of the Level 1 assessment, examining them in more detail on a site-by-site basis for the 20 sites and 4 Clusters. It also examines detailed hydraulic modelling outputs, such as depth, hazard and velocity, for floodplain areas. The impacts of climate change on different sources of flooding has been modelled or investigated in more detail. The cumulative impact of development has been considered. The presence of flood defences and residual risk, and the risk of structure blockage has also been assessed. The flood risk summary sheets and GeoPDF maps in Appendix A give flood risk information for each Level 2 site to support the application of the Sequential Test and inform the Council whether the Exception Test would be required. These summary sheets and maps form the main output of the Level 2 SFRA. If the Council finds them to pass the Sequential Test (and Exception test if appropriate), site-specific detailed flood risk assessments will be required on all of these sites to ensure that they are designed safely. The Level 1 and 2 SFRA has provided thorough recommendations on site specific requirements to be addressed by FRAs, guidance for site design and making development safe from flooding, and requirements for SuDS and surface water management. It is important to recognise that the SFRA has been developed using the best available information at the time of preparation. This relates both to the current risk of flooding from rivers, and the potential impacts of future climate change. In particular, the Environment Agency have indicated that at the time of publication they have commenced re-modelling of The Cut. Developers must ensure that they obtain and use the most up to date model data for detailed site-specific flood risk assessments.

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Executive Summary ...... iii 2 Introduction ...... 1 2.1 Introduction ...... 1 2.2 SFRA objectives ...... 1 2.3 How to use the Level 2 SFRA ...... 1 2.4 Stakeholder engagement ...... 1 3 How were sites identified for a Level 2 assessment? ...... 2 4 What flood risk information has been used? ...... 3 4.1 Data sources ...... 3 4.2 Environment Agency detailed hydraulic models ...... 3 5 How has climate change been assessed? ...... 3 5.2 Fluvial flooding ...... 4 5.3 Surface water flooding ...... 4 5.4 Groundwater flooding ...... 4 6 How has residual risk been assessed? ...... 5 6.2 Flood defence failure and overtopping ...... 5 6.3 Structure blockage ...... 5 7 How has cumulative impact of development been assessed? ...... 5 8 How to interpret groundwater flood risk data ...... 7 8.2 Interpreting the mapping ...... 7 8.3 Consequences for spatial planning ...... 7 9 Level 2 site flood risk summaries ...... 8 9.2 Summary sheets ...... 8 9.3 Site maps ...... 9 10 Future use of SFRA data ...... 12 Appendices ...... I A Level 2 site flood risk summary sheets and maps ...... I

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List of Tables Table 2-1: Level 2 SFRA engagement ...... 2 Table 4-1: Environment Agency detailed hydraulic models within Bracknell Forest at the time of publication ...... 3 Table 5-1: Climate change allowances ...... 4 Table 7-1: Potential for cumulative impact within a catchment ...... 7 Table 9-1: Site map explanatory notes ...... 10

List of Figures Figure 7-1: WFD catchments within Bracknell Forest ...... 6

Abbreviations and Definitions

Term Definition AEP Annual Exceedance Probability AIMS Asset Information Management System (Environment Agency GIS database of assets) AStGWF Areas Susceptible to Groundwater Flooding BFLP Bracknell Forest Local Plan Climate change - Long term variations in global temperature and weather patterns CC caused by natural and human actions. Critical Drainage Area - A discrete geographic area (usually a hydrological catchment) where multiple and interlinked sources of flood risk (surface water, groundwater, sewer, CDA main river and/or tidal) cause flooding in one or more Local Flood Risk Zones during severe weather thereby affecting people, property or local infrastructure. Catchment Flood Management Plan- A high-level planning strategy through which the Environment Agency works with their key decision makers within a river catchment to CFMP identify and agree policies to secure the long-term sustainable management of flood risk. CIRIA Construction Industry Research and Information Association Conveyance A term used to describe a feature of a sustainable drainage system which is designed to feature convey (move) water through the system (e.g. a swale or rill) CSO Combined sewer overflow Defra Department for Environment, Food and Rural Affairs A water-company held register of properties which have experienced sewer flooding due DG5 Register to hydraulic overload, or properties which are 'at risk' of sewer flooding more frequently than once in 20 years. EA Environment Agency EU European Union FCERMGiA Flood and coastal erosion risk management grant in aid FEH Flood Estimation Handbook FFL Finished floor level Infrastructure used to protect an area against floods as floodwalls and embankments; Flood defence they are designed to a specific standard of protection (design standard). An area determined as having a significant risk of flooding in accordance with guidance Flood Risk Area published by Defra and WAG (Welsh Assembly Government). Flood Risk Transposition of the EU Floods Directive into UK law. The EU Floods Directive is a Regulations piece of European Community (EC) legislation to specifically address flood risk by

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Term Definition prescribing a common framework for its measurement and management. Fluvial Flooding Flooding resulting from water levels exceeding the bank level of a main river Flood Risk Assessment - A site specific assessment of all forms of flood risk to the site FRA and the impact of development of the site to flood risk in the area. FRMP Flood Risk Management Plan Floods and Water Management Act - Part of the UK Government's response to Sir FWMA Michael Pitt's Report on the Summer 2007 floods, the aim of which is to clarify the legislative framework for managing surface water flood risk in England. Ha Hectare IDB Internal Drainage Board Indicative Flood Nationally identified flood risk areas, based on the definition of ‘significant’ flood risk Risk Area described by Defra and WAG. Infiltration A term used to describe a feature of a sustainable drainage system which is designed to feature allow water to soak (infiltrate) into the ground (e.g. a soakaway or infiltration basin) JBA Jeremy Benn Associates LFRMS Local Food Risk Management Strategy Lead Local Flood Authority - Local Authority responsible for taking the lead on local LLFA flood risk management LPA Local Planning Authority A watercourse shown as such on the Main River Map, and for which the Environment Agency has responsibilities and powers. However, the Environment Agency are not Main River responsible for all maintenance on Main Rivers, as the Environment Agency have permissive powers but the riparian owner has the responsibility. NPPF National Planning Policy Framework All watercourses that are not designated Main River. Local Authorities or, where they Ordinary exist, IDBs have similar permissive powers as the Environment Agency in relation to Watercourse flood defence work. However, the riparian owner has the responsibility of maintenance. PFRA Preliminary Flood Risk Assessment Comprehensive independent review of the 2007 summer floods by Sir Michael Pitt, Pitt Review which provided recommendations to improve flood risk management in England. Flooding as a result of high intensity rainfall when water is ponding or flowing over the Pluvial flooding ground surface (surface runoff) before it enters the underground drainage network or watercourse, or cannot enter it because the network is full to capacity. PPG National Planning Policy Guidance Resilience Measures designed to reduce the impact of water that enters property and businesses; Measures could include measures such as raising electrical appliances. Is an estimate of the interval of time between events of a certain intensity or size, in this Return Period instance it refers to flood events. It is a statistical measurement denoting the average recurrence interval over an extended period of time. Residual risk The risk that remains after measures have been taken to alleviate flooding. In flood risk management, risk is defined as a product of the probability or likelihood of a Risk flood occurring, and the consequence of the flood. Risk of Flooding from Surface Water map. Environment Agency national map showing RoFfSW risk of flooding from surface water. SA Sustainability Appraisal Sewer flooding Flooding caused by a blockage or overflowing in a sewer or urban drainage system. Strategic Housing and Economic Land Availability Assessment - The Strategic Housing SHELAA Land Availability Assessment (SHLAA) is a technical piece of evidence to support local plans and Sites & Policies Development Plan Documents (DPDs SFRA Strategic Flood Risk Assessment Standard of Protection - Defences are provided to reduce the risk of flooding from a river SoP and within the flood and defence field standards are usually described in terms of a flood event return period. For example, a flood embankment could be described as providing 2016s5363 - Bracknell Forest Council - SFRA L2 Final Report v5.0 (Sep 2019) 3

Term Definition a 1 in 100-year standard of protection. Source Protection Zone - The Environment Agency have defined Source Protection Zones (SPZs) for groundwater sources such as wells, boreholes and springs used for public drinking water supply. These zones show the risk of contamination from any SPZ activities that might cause pollution in the area. The closer the activity, the greater the risk. The maps show three main zones (inner, outer and total catchment) and a fourth zone of special interest, which is occasionally applied, to a groundwater source. STW Sewage treatment works Sustainable Drainage Systems - Methods of management practices and control SuDS structures that are designed to drain surface water in a more sustainable manner than some conventional techniques Flooding from surface water runoff as a result of high intensity rainfall when water is Surface water ponding or flowing over the ground surface before it enters the underground drainage flooding network or watercourse, or cannot enter it because the network is full to capacity, thus causing what is known as pluvial flooding. Surface Water Management Plan - The SWMP plan should outline the preferred surface SWMP water management strategy and identify the actions, timescales and responsibilities of each partner. It is the principal output from the SWMP study. Term used to describe the loss of permeable surfaces within urban areas, which Urban creep generates increased runoff that may contribute to flooding. WCS Water Cycle Study WFD Water Framework Directive

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2 Introduction

2.1 Introduction

2.1.1.1 Bracknell Forest Council is undertaking the preparation of a Local Plan (BFLP). As part of this process it is preparing an evidence base which will support the policies and allocations included in the document. This Level 2 Strategic Flood Risk Assessment (SFRA) is one piece of the evidence base, which will help to inform policy development and the selection of site allocations for inclusion within the BFLP.

2.1.1.2 Once adopted the BFLP will set out a vision, strategy and framework for development in the Borough from 2016/2017 to 2035/2036 for housing, the economy, community facilities and infrastructure, and will address design, climate change and environmental protection. Once the BFLP is adopted, it will replace the saved policies in the Bracknell Forest Borough Local Plan (2002) and the Core Strategy (2008). This issue of the Level 1 SFRA (2018) and Level 2 SFRA (2018) replaces the Level 1 SFRA that was published by Bracknell Forest Council (henceforth referred to as 'The Council') in 2010.

2.1.1.3 The report will provide appropriate supporting evidence to assist the Council in its Sustainability Appraisal and will inform the production of the Local Plan to 2036. The 2018 SFRA update will be used to inform decisions on the location of future development and the preparation of sustainable policies for the long-term management of flood risk from all sources and be used to inform planning applications that come forward outside the development plan process.

2.2 SFRA objectives

2.2.1.1 The Planning Practice Guidance advocates a tiered approach to risk assessment and identifies the following two levels of SFRA: • Level 1: where flooding is not a major issue and where development pressures are low. The assessment should be sufficiently detailed to allow application of the Sequential Test. • Level 2: where land outside flood risk areas cannot appropriately accommodate all the necessary development. In these circumstances, the assessment should consider the detailed nature of the flood characteristics.

2.2.1.2 Bracknell Forest has completed a Level 1 SFRA which identified the need for a Level 2 SFRA. The objectives of the Level 2 SFRA are to consider the detailed nature of the flood characteristics within the Flood Zones, and for areas at risk from other sources of flooding.

2.3 How to use the Level 2 SFRA

2.3.1.1 The Level 2 SFRA report gives a short non-technical summary of how the Level 2 sites were selected, the detailed flood risk data that was used to carry out individual site-level assessments for each of the Level 2 sites, and how climate change, cumulative impact, other sources of flooding and residual risk were assessed.

2.3.1.2 The main output of the Level 2 assessment are the individual site summary sheets, in Appendix A, which offer high level flood risk assessments and conclusions for each site. The sites are presented in alphabetical order by site code.

2.4 Stakeholder engagement

2.4.1.1 Preparation of a SFRA requires significant engagement with stakeholders both within the Local Planning Authority, with water and wastewater utilities, with the Environment Agency and, where there may be cross-boundary issues, with neighbouring local authorities, in order to meet the requirements under the Localism Act's "duty to cooperate" requirements. Table 2-1 forms a

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record of engagement for the Level 2 SFRA. Table 2-1: Level 2 SFRA engagement Date Type of engagement Organisations engaged 04/10/2017 Inception meeting Bracknell Forest Council and JBA Consulting 12/01/2018 Draft SFRA Level 2 report and maps Bracknell Forest Council issued for review 31/05/2018 Draft site summary sheets of interest Wokingham Borough Council shared with neighbouring Borough. 13/06/2018 Draft Final SFRA Level 2 report and Bracknell Forest Council maps issued for review 11/01/2019 Addition of sites and update of Draft Bracknell Forest Council Final SFRA Level 2 report and maps 16/07/2019 Addition and removal of sites and Bracknell Forest Council update of Draft Final SFRA Level 2 report and maps

3 How were sites identified for a Level 2 assessment?

3.1.1.1 As part of the Level 1 SFRA, flood risk from all sources was assessed for 100 SHELAA potential development areas. This information was provided in spreadsheet format and can be used as a 'screening tool', giving more detailed information regarding the risks posed to each development site.

3.1.1.2 This assessment identified all sites located within Flood Zone 1 and at low risk of flooding from all other sources, in order that they can be taken forward for consideration for inclusion in the BFLP. Though a large proportion of the Borough falls within Flood Zone 1, possible flooding from other sources is a factor which may necessitate a Level 2 SFRA. In Bracknell Forest, for a site to be considered at low risk of flooding, it is required to meet the following conditions: • Site is within Flood Zone 1 • Site is not within Flood Zone 3a plus 70% allowance for climate change • Site is <10% at risk from surface water flooding in the 1 in 1000-year event • Site is <10% within highest risk category in JBA Groundwater map (groundwater is <0.025m below the surface in the 1 in 100-year event) • Site is <75% within second highest risk category in JBA Groundwater map (groundwater is between 0.025m and 0.5m below the surface in the 1 in 100-year event) • Site is not within the Historic Flood Map • Site is not at risk of reservoir flooding

3.1.1.3 The Council accepts that low levels of surface water and groundwater risk can be mitigated through appropriate design as part of the planning process and therefore the above criteria (such as up to 10% of the site at risk in the 1 in 1000-year event) have been chosen in collaboration with the Environment Agency and LLFA to identify where other sources of flooding are not likely to represent a significant constraint to development.

3.1.1.4 With regard to groundwater, sites with less than 10% of their area at a level of between 0 and 0.025m below ground or with less than 75% of their area at a level of between 0.025m and 0.5m below ground have been considered low risk. Whilst not considered to be a significant constraint to development, this will still need to be satisfactorily addressed in any development scheme and developers should consult with the council at an early stage to ensure adequate assessment is undertaken.

3.1.1.5 On the basis of the Level 1 SFRA and the Sustainability Assessment (SA), the Council identified

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that all the necessary development required over the plan period cannot be accommodated by sites identified above as low risk from all sources (noting that the SA process discounted some low risk sites on other planning grounds), and additional sites would be required to enable delivery of the level of development set out in the BFLP

3.1.1.6 The Council therefore progressed to a Level 2 SFRA for 28 qualifying sites and 3 Clusters to provide further detail and development solutions for prescribed sites and for the application of the Exception Test, if required. 4 What flood risk information has been used?

4.1 Data sources

4.1.1.1 The Level 2 SFRA draws upon all the information and data sources that were compiled as part of the Level 1 assessment (See Level 1 assessment for full details), examining them in more detail on a site-by-site basis. These sources include: • Environment Agency Risk of Flooding from Surface Water map and input model details • Environment Agency Risk of Flooding from Reservoirs map • Environment Agency Main Rivers GIS layer and OS OpenRivers GIS layer • Environment Agency Recorded Flood Outline • Environment Agency Spatial Flood Defences layer • Thames Water Sewer Flooding Register • LLFA asset and flood history information and GIS • JBA Groundwater Map

4.2 Environment Agency detailed hydraulic models

4.2.1.1 The detailed hydraulic models available for use in the SFRA are shown in Table 4-1. Because of the location of the Level 2 sites, only The Cut (2013) model was used to inform the Level 2 SFRA. The outputs from The Cut model, including extent, depth, hazard and velocity, were used to inform the relevant site assessments.

4.2.1.2 The Environment Agency have indicated that at the time of publication they have commenced re- modelling of The Cut. This was not available within the timeframe of the Bracknell Forest BFLP. When carrying out a FRA for any development site containing Flood Zone or a watercourse, developers should always request the latest modelled data from the Environment Agency. Table 4-1: Environment Agency detailed hydraulic models within Bracknell Forest at the time of publication Model and provider Type Year The Cut, Environment ISIS- TUFLOW 2013 Agency River Blackwater, ISIS 1D 2007 Environment Agency River Blackwater (Sandhurst TUFLOW, 1D and 2D 2009 to Bramshill), Environment Agency Blackwater Tributaries, ISIS- TUFLOW 2012 - 2015 Environment Agency Chertsey Bourne, Linked 1D/2D ISIS 2005 Environment Agency 5 How has climate change been assessed?

5.1.1.1 Updated government guidance on assessing the impact of climate change on flooding in line with

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the UKCP09 Climate Change Projections1 was first released in February 20162 and is updated online periodically.

5.2 Fluvial flooding

5.2.1.1 The guidance provides a range of climate change allowances which are dependent on location (by river basin) and timescale of development (epoch). It also provides several bands (termed ‘central’, ‘higher central’ and ‘upper end’) to test depending on the vulnerability of the development and the Flood Zone within which it is located.

5.2.1.2 Bracknell Forest is within ‘Thames’ river basin district, for which climate change allowances under the guidance are shown in Table 5-1. Table 5-1: Climate change allowances River Allowance Total potential Total potential Total potential basin category change change change district anticipated for anticipated for anticipated for the ‘2020s’ (2015 the ‘2050s’ (2040 the ‘2080s’ (2070 to 2039) to 2069) to 2115) Thames Upper end 25% 35% 70% Higher central 15% 25% 35% Central 10% 15% 25%

5.2.1.3 For the purposes of strategic planning, the key epoch considered is 2070-2115 as this reflects the lifetime of development; and the key vulnerability is ‘more vulnerable’ as this represents a conservative classification incorporating all vulnerabilities. The key allowances to consider for Flood Zone 3a are therefore the higher central and upper end (35% and 70% in Thames river basin district) as shown in Table 5-1.

5.2.1.4 The Environment Agency's detailed hydraulic models were re-run for these two climate change scenarios as part of the Level 1 SFRA.

5.3 Surface water flooding

5.3.1.1 Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for 2085 to 2115). This will increase the likelihood, frequency and extent of surface water flooding.

5.3.1.2 The Level 2 assessment of present-day surface water flood risk is based on the Environment Agency Risk of Flooding from Surface Water (RoFfSW) map. To make a high-level assessment of the potential impact of climate change on these risk areas, the rainfall inputs and parameters used in this mapping were examined.

5.3.1.3 Flood Estimation Handbook rainfalls depths3 were compared at a number of sample points across Bracknell Forest. It was found that the 1 in 100-year rainfall plus 40% climate change (the upper end estimate) was less than the 1 in 1,000-year rainfall in all cases. In fact, the 1 in 1,000-year rainfall is on average around 80% higher than the 1 in 100-year rainfall. This suggests that the 1 in 100-year plus 40% climate change surface water flood extent should be well within the present- day 1 in 1,000-year extent on the RoFfSW map.

5.4 Groundwater flooding

5.4.1.1 The effect of climate change on groundwater flooding, and those watercourses where groundwater has a large influence on winter flood flows is more uncertain, and it is not possible to

1 UK Climate Projections (UKCP09) http://ukclimateprojections.metoffice.gov.uk/21678 2 https://www.gov.uk/guidance/flood-risk-assessments-climate-change-allowances 3 Flood Estimation Handbook (FEH) FEH99 rainfalls used.

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quantitatively assess this for an SFRA.

5.4.1.2 Generally, research suggests that milder wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months. 6 How has residual risk been assessed?

6.1.1.1 'Residual risk' refers to the risks that remain in circumstances after measures have been taken to alleviate flooding. It is important that these risks are quantified to confirm that the consequences can be safely managed.

6.2 Flood defence failure and overtopping

6.2.1.1 None of the sites assessed for the Level 2 SFRA were found to benefit from any known formal defences or flood alleviation scheme, therefore there was no residual risk identified from breach, overtopping or failure of defences.

6.3 Structure blockage

6.3.1.1 Culverts and structures susceptible to blockage within or close to proposed sites were identified using OS mapping, the Environment Agency Spatial Flood Defences GIS dataset (which includes culvert assets), and through consultation with the Council. Structures were identified on 12 sites. It was not possible to survey them all and precautionary qualitative assessments were made using existing information.

6.3.1.2 An individual assessment was carried out for each structure, using existing model, survey and LiDAR data, where available, to determine: • The size of the structure and whether it presents a barrier to overland flow in the event of a blockage (e.g. a railway embankment), or whether the structure could be by-passed in the event of a blockage. • The likely impact on the flood risk area within the site considering the topography. The RoFfSW can be used as a proxy for small culverts as it does not take their capacity into account.

6.3.1.3 A description of the findings is included in the site summary sheets. 7 How has cumulative impact of development been assessed?

7.1.1.1 The requirement to consider the cumulative impact of development was introduced into the NPPF in 2018. When allocating land for development, consideration should be given to the potential cumulative impact on flood risk within a catchment. Development increases the impermeable area within a catchment, which if not properly managed, can cause loss of floodplain storage, increased volumes and velocities of surface water runoff, and result in heightened downstream flood risk. Whilst individual developments should only have a minimal impact on the hydrology and flood risk of an area if designed properly, the cumulative effect of multiple developments may be more severe.

7.1.1.2 In considering the potential cumulative impact of the Level 2 sites, they must be considered in combination with all the other SHELAA sites that may also potentially be developed in the same hydrological catchment. The Water Framework Directive (WFD) catchment areas (Figure 7-1) have been used to determine how many SHELAA sites (as provided June 2019) fall within the

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same hydrological catchment, and what percentage of the land area of the catchment they cover. Figure 7-1: WFD catchments within Bracknell Forest

7.1.1.3 A measure of the potential for cumulative impact within a catchment has been determined using the percentage of land area of the catchment covered by potential development (Table 7-1). It should be noted that this is an indicative measure, as not all the sites under consideration will be developed.

7.1.1.4 The Cut (Ascot to Bull Brook confluence at Warfield) had the highest percentage of potential development, with 22% of the catchment area proposed for development.

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Table 7-1: Potential for cumulative impact within a catchment Proposed development as % of Potential for cumulative impact within catchment area catchment <5% Low 5-15% Medium >15% High

7.1.1.5 For each WFD catchment in Bracknell Forest, the susceptibility of the catchment immediately downstream to increased flows was examined. Most of the downstream catchments (the lower Cut and Loddon) are characterised by rural floodplain with relatively few properties or communities at risk, and therefore immediate downstream susceptibility to cumulative impact is relatively low. Ultimately the whole of Bracknell Forest drains to the River Thames, which has a high level of risk to properties and communities. However, is a very large catchment, so the relative impact of tributaries on total flows is reduced.

7.1.1.6 To avoid cumulative impact of development, all development should strive to limit discharge rates and volumes to greenfield rates or better, and this is particularly important where there is a lot of development in the same hydrological catchment.

7.1.1.7 At the time of writing, a further cumulative impact assessment is being undertaken, which includes the impacts of development in neighbouring districts. The results will be presented in a separate stand-alone report. 8 How to interpret groundwater flood risk data

8.1.1.1 The Level 2 SFRA uses the JBA Groundwater Map to assess groundwater risk. More detail on the dataset is given in the Level 1 SFRA main report and Appendix D.

8.1.1.2 Groundwater flood risk is of concern to Bracknell Forest Council due to the potential impact on the function of SuDS measures, however, how to deal with groundwater risk in the planning process is not covered explicitly in the Planning Practice Guidance4. The following section provides some guidance on how planners should interpret the groundwater flood risk data presented in the Level 2 SFRA.

8.2 Interpreting the mapping

8.2.1.1 Environment Agency national mapping showing the extents of flooding from rivers (Flood Zones) and surface water (Risk of Flooding from Surface Water) estimates the extent of areas which are at risk of inundation. Hence, should a flood occur as modelled, all land within that flood envelope would be expected to be inundated.

8.2.1.2 This is not the case for groundwater flood mapping, which estimates the likelihood of experiencing groundwater at shallow depths, or of groundwater rising to and emerging onto the surface. The rate of emergence at any particular location would depend upon the available pressure head, and on the permeability of the soils and near-surface geology. Both can be highly locally variable. Where emergence does occur, water may be expected to either follow overland flow pathways or, where there are local topographic depressions, to pond in these.

8.2.1.3 Groundwater flood risk should be considered in spatial planning, however groundwater risk mapping does not show areas which would be inundated, and hence cannot be treated in the same way as modelled flood outlines for fluvial or surface water risks.

8.3 Consequences for spatial planning

8.3.1.1 The risk of groundwater flooding should always be considered in a site-specific Flood Risk Assessment (FRA) prepared in support of a planning application. This should use the information

4 Planning Practice Guidance: Flood Risk and Coastal Change (Department for Communities and Local Government, April 2015) http://planningguidance.planningportal.gov.uk/blog/guidance/flood-risk-and-coastal-change/

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within the SFRA, but supplement it with local borehole information (both new boreholes sunk as part of the site investigations, and historic borehole records available on the BGS website), and with local knowledge from the landowner, neighbouring residents, flood incident data etc. Detailed site investigations will be required including infiltration testing and groundwater monitoring carried out during the winter months (November through to March).

8.3.1.2 Where SFRA mapping indicates that there is a high risk of groundwater emergence occurring during extreme groundwater events, consideration should be given as to the likely areas where water will flow and pond on the site. Digital Terrain Models (DTMs) and the Environment Agency's Risk of Flooding from Surface Water Map can inform this assessment at the SFRA Level 2 stage. Site-specific FRAs should also use site walkovers, topographic surveys and if necessary, detailed modelling to assess this.

8.3.1.3 Following a detailed FRA, development should be steered away from areas of highest groundwater flood risk, and areas where water might flow and pond. However, it may not be possible to avoid groundwater risk completely, particularly where the risk is predicted to be below ground rather than emerging. Where not possible to do so, risk can be mitigated through good design and resilience measures must be provided for the development, for example: • The design of SUDS schemes must take into account the seasonally high groundwater table and the likely frequency of groundwater reaching within 2m of the ground surface. Infiltration techniques may be ineffective, and may pose a pollution risk. They may be effective for most of the time, but impeded during high groundwater events, which are likely to occur in the winter during prolonged periods of wet weather. SuDS may need to be shallow to avoid interaction with the groundwater table and consequently have a larger land take. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • The presence of shallow groundwater should be taken into consideration when designing below-ground services, particularly foul and surface water sewers, where groundwater infiltration through the fabric of pipes and manholes can lead to system overloading, increasing the risk of pollution incidents and sewer flooding. Lining of structures may be necessary, but consideration must be given to the potential obstruction to sub-surface flow routes. • Raising finished floor levels 300mm above the surrounding ground level is recommended in areas where groundwater emergence risk is indicated. 9 Level 2 site flood risk summaries

9.1.1.1 The flood risk summary sheets and maps in Appendix A give flood risk information for each Level 2 site to support the application of the Sequential Test and inform the Council whether the Exception Test would be required and/or development will be viable. These summary sheets and maps form the main output of the Level 2 SFRA.

9.2 Summary sheets

9.2.1.1 The summary sheets contain the following information.

9.2.2 Site details • Basic site information (area, type of site) • Proposed site use – The Level 1 SFRA and Table 2 and Table 3 of the Planning Practice Guidance provide further detail of the type of development considered appropriate for each Flood Zone (https://www.gov.uk/government/collections/planning-practice-guidance). • Flood risk vulnerability category

9.2.3 Sources of flood risk • Presence of a watercourse or existing drainage features • History of flooding (where information is available)

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• Fluvial flooding description – % of site in each Flood Zone, description of fluvial flood characteristics, extents, hazard, velocity, depths, rate of onset and duration of flooding (where information is available) • Description of the availability and limitations of modelled data • Surface water flooding description - % of site in each uFMfSW category, description of surface water flow paths both on and off-site. • Groundwater flooding description - % of site in the two highest risk JBA Groundwater map categories, description of areas at groundwater risk. • Description of reservoir and canal flood risk • Description of sewer flood risk

9.2.4 Impact of climate change • Climate change allowances for Thames river basin for the 2080's epoch under current government guidelines (February 2016) • Impact of climate change on fluvial flooding and the Flood Zone classification • Impact of climate change on flood risk from other sources

9.2.5 Cumulative impact of development • WFD catchment name (within which site is located) • Number of developments proposed • Proposed development area as % of WFD catchment area • Potential for cumulative impact within WFD catchment • Susceptibility of downstream catchment

9.2.6 Flood risk management infrastructure and residual risk • Assessment of flood defences – description, standard of protection, assessment of residual risk based on the Environment Agency Spatial Flood Defence layer and LLFA asset data. • Assessment of the presence of culverts or other structures which may be prone to blockages, and a qualitative assessment of the potential impacts of blockages.

9.2.7 Emergency planning • Flood warning coverage • An assessment of how flood risk may impact on safe access and egress.

9.2.8 Sustainable drainage and flood risk betterment • Geology (www.bgs.ac.uk) • Soil type (www.landis.org.uk/soilscapes) • Typical slope • Presence of Groundwater Source Protection Zone (SPZ) or Historic Landfill Site

9.2.9 Requirements for planning and NPPF • Sequential Test and Exception Test requirements • Requirements for site-specific Flood Risk Assessment • Guidance for site design and making development safe from flooding • Requirements for SuDS and surface water management

9.3 Site maps

9.3.1 How to use the maps

9.3.1.1 Each site summary sheet has an accompanying 'GeoPDF' map displaying all the relevant available flood risk mapping. GeoPDFs display many different mapped data 'layers', and the user can 'tick' the layers on and off on the legend on the right-hand side. If a layer does not display

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when it is ticked, this means the site is not at risk or there is no relevant data for the site.

9.3.2 What is displayed on the maps?

9.3.2.1 Table 9-1 gives explanatory notes for each of the 'layers' shown on the maps. This table is also embedded in the GeoPDFs for ease of reference. The Level 1 SFRA contains information on the origin of the different risk maps and the planning implications of each of the Flood Zones. Table 9-1: Site map explanatory notes Data type Description/explanation Watercourses Main River - Environment Agency mapping showing locations of designated Main Rivers OS Open Rivers - OS open data mapping showing watercourses. This does not include smaller land drains etc which may be observed on smaller-scale OS maps. Flood Zones Flood Zone 3b – Functional Floodplain Composite outline created for the SFRA. This is composed of the best available data for Functional Floodplain for each watercourse, either: 20- year outlines from a detailed model; or Flood Zone 3a as a precautionary proxy. Flood Zone 3a – from Environment Agency national Environment Agency Flood Map for Planning (Rivers and Sea) Flood Zone 2 – from Environment Agency national Environment Agency Flood Map for Planning (Rivers and Sea) Flood Zone 3a plus 35% climate change (Higher Central allowance for 2080s) Flood Zone 3a plus 70% climate change (Upper End allowance for 2080s) Composite outlines created for the SFRA. These are composed of the best available data for the 100-year plus climate change event for each watercourse, either: 100-year plus 35% or 70% outlines from a detailed model; or Flood Zone 2 as a proxy. Modelled Modelled fluvial flood extents for different return periods from detailed extent Environment Agency hydraulic models, where they were available. Details and dates of the relevant model are given in the site summary sheet. These layers give additional information about the likely frequency of flooding at different return periods: 1 in 5-year, 1 in 20-year, 1 in 75-year, 1 in 100-year, 1 in 1,000-year. The same modelled information has been used to produce the Flood Zones. Modelled Modelled 1 in 100-year plus 35% climate change fluvial flood hazard hazard value from detailed Environment Agency hydraulic models, where they were available. Details and dates of the relevant model are given in the site summary sheet. Hazard is an index calculated from depth, velocity and a debris factor. Its value is used to determine the risk to people that flooding poses (low, danger for some, danger for most, danger for all) based on Defra guidance5. Modelled Modelled 1 in 100-year plus 35% climate change fluvial maximum flood velocity velocity value (in metres per second) from detailed Environment Agency hydraulic models, where they were available. Details and dates of the relevant model are given in the site summary sheet. Velocity is a measure of how fast the flood water is likely to be flowing. Modelled Modelled 1 in 100-year plus 35% climate change fluvial maximum flood depth value (in metres) from detailed Environment Agency hydraulic

5 Defra/Environment Agency Flood Risks to People Guidance Document FD2321/TR2

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depth models, where they were available. Details and dates of the relevant model are given in the site summary sheet. Surface water Environment Agency national Risk of Flooding from Surface Water mapping (showing risk area for 3 different probability events): • High: An area has a change of flooding greater than the 1 in 30 (3.3%) each year; • Medium: An area has a chance of flooding between 1 in 100 (1%) and 1 in 30 (3.3%) each year; • Low: An area has a chance of flooding between 1 in 1000 (0.1%) and 1 in 100 (1%) each year. This information is based on a national scale map identifying those areas where surface water flooding poses a risk. It shows predictions of flooded areas but should not be used to determine whether individual properties will be affected by surface water flooding or have been affected in the past. However, it can be used to identify development sites where surface water risk may be a constraint to development, where further detailed modelling may be required as part of a Flood Risk Assessment. Groundwater JBA Groundwater Map (2017) JBA's Groundwater Flood Map has a resolution of 5m and provides a detailed assessment of groundwater flood hazard: • Groundwater levels are either at or very near (within 0.025m of) the ground surface. Within this zone there is a risk of groundwater flooding to both surface and subsurface assets. Groundwater may emerge at significant rates and has the capacity to flow overland and/or pond within any topographic low spots. • Groundwater levels are between 0.025m and 0.5m below the ground surface. Within this zone there is a risk of groundwater flooding to surface and subsurface assets. There is the possibility of groundwater emerging at the surface locally. • Groundwater levels are between 0.5m and 5m below the ground surface. • There is a risk of flooding to subsurface assets but surface manifestation of groundwater is unlikely. • Groundwater levels are at least 5m below the ground surface. Flooding from groundwater is not likely. • No risk. This zone is deemed as having a negligible risk from groundwater flooding due to the nature of the local geological deposits. No risk will display as transparent on the map. The JBA Groundwater Flood Map should be used in combination with other information, for example local data or historic data. It should not be used as sole evidence for any specific flood risk management, land use planning or other decisions at any scale. The data can however help to identify areas for assessment at a local scale where finer resolution datasets exist. Sewer Number of properties on Thames Water sewer flooding register by 5-digit postcode area. This is a register of flooding from the 'public' sewer system ('public' in this context meaning assets under the control of Water & Sewerage Companies in England & Wales). Properties at risk of flooding are recorded in a register which is made available to OFWAT. Thames Water and OFWAT consider the register to be confidential and do not release the data in more detail than ‘number of properties per 4 or 5-digit postcode’. Reservoir Environment Agency Risk of Flooding from Reservoirs flood extent mapping. The Environment Agency's Risk of Flooding from Reservoirs map has been used to identify areas that may be at risk from failure or overtopping

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of reservoirs. The data was published following the Environment Agency's National Reservoir Inundation Mapping project in 2009. Layers showing depth, extent and speed of flooding are available online, but no information is given on the likelihood of reservoir failure. Flood history Environment Agency Recorded Flood Outline mapping - gives recorded outlines for events with dates and some information on mechanism and source of information. LLFA flood records - made up of two Council GIS layers: • Reported flooded areas - gives area and properties flooded and a date (year only) • Surface water flooding events - gives area and full dates. Highways recorded flood incidents Points showing the locations of incidents of highway and property flooding recorded by the Council’s Highways department call log between 2007 and 2018, provided as a spreadsheet. Location information varied, and points were geo-located by JBA as accurately as possible based on address information and description. Where only a street name was available, the point was placed in the middle of that street. Flood risk The Level 1 SFRA reviewed a number of data sources of flood risk assets assets, from the Environment Agency (national Spatial Flood Defences mapping and local Asset Management Information System (AIMS) data), and from the LLFA archives and asset register. It found that there were no formal defences (e.g. raised flood embankments, walls, or even maintained channels) in the district. The Level 2 maps therefore only display asset data that may impact on flood risk at Level 2 sites: • Culverts, bridges and weirs compiled from AIMS and LLFA asset register datasets. • Thames Water balancing ponds 10 Future use of SFRA data

10.1.1.1 The Level 2 SFRA has examined flood risk from all sources for each of the 20sites and 4 clusters in more detail. The aim of the Level 2 assessments is to provide evidence to support a decision on whether or not the Sequential (and Exception Test if appropriate) could be passed, i.e. development could be achieved safely, for sites that have been found to be at flood risk by the Level 1 assessment.

10.1.1.2 If the Council finds them to pass the Sequential Test (and Exception test if appropriate), detailed flood risk assessments will be required on all of these sites to ensure that they are designed safely. The Level 2 SFRA has provided thorough recommendations on site specific requirements to be addressed by FRAs, guidance for site design and making development safe from flooding, and requirements for SuDS and surface water management.

10.1.1.3 It is important to recognise that the SFRA has been developed using the best available information at the time of preparation. This relates both to the current risk of flooding from rivers, and the potential impacts of future climate change. In particular, the Environment Agency have indicated that at the time of publication they have commenced re-modelling of The Cut. Developers must ensure that they obtain and use the most up to date model data for detailed site- specific flood risk assessments.

10.1.1.4 The SFRA should be periodically updated as appropriate when new information on flood risk, flood warning or new planning guidance or legislation becomes available. New information on flood risk may be provided by Bracknell Forest (in its role as LLFA), Thames Water, the Environment Agency or other relevant stakeholders such as Parish Councils. A further reason for updating the SFRA would be following significant new committed sites and thus a considerable change to the planning context for further growth.

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Appendices A Level 2 site flood risk summary sheets and maps

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Bracknell Forest Council

Level 2 SFRA Detailed Site Summary Tables

Contents BIN4 ...... 2 BIN5 ...... 7 BIN6 ...... 12 BIN8 ...... 17 BIN9 ...... 22 BIN11 ...... 27 BIN12 ...... 32 BIN16 ...... 37 BIN17 ...... 42 BIN18 ...... 46 BIN19 ...... 51 BRA1 ...... 56 BRA3 ...... 61 BRA4 ...... 66 BRA7 ...... 71 BRA11 ...... 76 BRA12 ...... 81 BRA14 ...... 86 BRA15 ...... 90 BRA16 ...... 95 CLUSTER1 ...... 100 CLUSTER3 ...... 105 CLUSTER7 ...... 111 SAND8 ...... 116 SAND9 ...... 122 WAR3 ...... 127 WAR8 ...... 134 WAR25 ...... 138 WINK7 ...... 143 WINK14 ...... 148 WINK22 ...... 155

1

Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site Details

Site code BIN4 Site name Wyevale Garden Centre, Forest Road

Area 1.87ha

Greenfield or Previously Developed Land previously developed land

Proposed site use Housing and open space or commercial use

Flood risk More vulnerable vulnerability Sources of flood risk

The site is adjacent to The Cut, a Main River, although the channel is outside of the site boundary. There is a small unnamed drain which runs along the eastern boundary Existing of the site before joining The Cut just to the north east. There is also an unnamed drainage watercourse to the south west of the B3034 with several ponds online. It is not clear features on OS mapping whether this flows under the B3034 and is culverted beneath the site, or enters The Cut to the south of the B3034. The Environment Agency Recorded Flood Outline layer contains the outline of an event which occurred on 6 November 1974. The cause of flooding is noted as channel capacity being exceeded. The recorded outline ends at the B3034 bridge, just to the Flood history south of the site. The data source for this outline is unknown and it is possible that the site was also flooded during this event. The nearby Binfield flow gauge has recorded events with similar or greater flows than this in May 1979, June 1981 and October 2000. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 10.7% 12.8% 76.5% 15.0% Available detailed modelling data: Environment Agency (2013) ISIS-TUFLOW model of The Cut, built as part of The Cut Flood Risk Mapping Study. The Environment Agency has indicated, at the time of publication, that they have commenced re-modelling of The Cut. The most recently available model data will be Fluvial used to inform any site-specific Flood Risk Assessments (FRAs). Detailed nature of flood characteristics: The south east corner of the site is inundated during the 1 in 75-year event, with the extent increasing in this corner of the site during the 1 in 100-year event. The 1 in 100- year plus 70% climate change and 1 in 1,000 year events start to encroach on the north eastern area of the site as well. Depths on the floodplain are predicted to reach between 0.1 and 0.6m in a 1 in 100-year plus climate change event across the south- east corner of the site, with the hazard of ‘Danger to some’, increasing to 'Danger for most' within a small area close to the road. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year Surface Water 4.4% 8.6% 33.9%

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Description of surface water flow paths: The RoFfSW map shows small amounts of flooding on site in the 1 in 30 and 1 in 100- year events, wih the 1 in 1,000-year event causing inundation to much of the eastern part of the site. Although some of this flooding may result from the adjacent river floodplain to the east of the site, a flow path also enters the site from the south west. Increasing in extent from the 1 in 30-year event upwards, the flow path follows the course of the unnamed watercourse and ponds to the south of the B3034. This watercourse originates in Emmets Park, east Binfield and flows through sites Bin6 and Bin5 before reaching site Bin4. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m

Groundwater 0.0% 0.0% 0.0%

Description of groundwater risk: No groundwater flood risk is shown in JBA Groundwater Map. A localised high water table may occur in the floodplain during fluvial events. The Environment Agency Risk of Flooding from Reservoirs map predicts that flooding Reservoir / may occur along The Cut, in the event that Fish Pond at Ascot Place failed or impounded overtopped. The extent of flooding is predicted to cover 1.1% of the site in the far south water body east corner, to depths of around 0 to 0.3m. This area is contained within the existing failure Flood Zone 2 and 3. Canal There are no canals in Bracknell Forest. The site is mostly located within postcode boundary RG42 4, which has 1 property on the Thames Water Sewer Flooding Register. This is a very small proportion of the Sewer total properties in this postcode area. A small corner of the site is within RG42 5, which has no properties on the register.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70% Climate change under both the +35% and +70% scenarios is likely to increase the area of Flood Zone 3a, and cause it to be similar in extent to the current Flood Zone 2. The Impact of extent of Flood Zone 2 is also likely to increase slightly. However modelling the climate change impacts of climate change on Flood Zone 2 is not currently a requirement under the on fluvial NPPF. flooding and the Flood Zone classification Flooding is likely to become more frequent under both climate change scenarios, and the impact of an event with a given probability is also likely to become more severe, with water depths, velocities and flood hazard increasing.

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Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitivity range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative impact of development

Water Framework Directive BIN4 is within the Cut (Binfield to River Thames confluence) and (WFD) catchment name Maidenhead Ditch catchment 15 Proposed development 3% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment Medium. The Thames (Cookham to Egham) catchment has a high risk Susceptibility of downstream to properties but a very large catchment area upstream of The Cut catchment which will reduce the relative impact of tributaries.

Flood risk management infrastructure and residual risk

There are no formal (raised) defences present on The Cut at this location, or other known defence schemes which may provide benefit. The Environment Defence type Agency Spatial Defences layer records the banks as 'high ground' with 'no maintenance'. The Environment Agency Spatial Defences layer records the banks to have a Standard of protection ‘design’ standard of 5-years and actual standard of 0-years. This suggests that (SoP) the banks provide no actual flood defence function. The Environment Agency Spatial Defences layer records the general condition Environment Agency’s of the banks to be 2, with a worst condition of 5. defence condition Based on principles of Condition Assessment Manual (Environment Agency, assessment 2012). 1 (Very Good), 2 (Good), 3 (Fair), 4 (Poor), 5 (Very Poor). Risk of defence There is no risk of defence breach / overtopping, as there are no raised breach / overtopping? defences. Just upstream of the B3034 road bridge, The Cut enters Binfield Manor Pond, noted in The Cut modelling report as an attenuation feature - a large lake with shallow banks. The Cut then flows under the B3034 via a large three-arched Risk of culvert / bridge. Just downstream, and adjacent to the site, is the Environment Agency's structure blockage? Binfield Flow Gauge, which consists of two round-nosed weirs which measure high and low flow. Risk of structure blockage on The Cut is low, as the Environment Agency weir is well-maintained, and the three-arched bridge has a large capacity, as well as being located at the upstream end of the site.

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Emergency planning

The area receives a Flood Alert and a Flood Warning under the Environment Agency's Flood Information Service. The site falls within the 'Cut at Ryehurst Lane, Flood warning Westley Mill and Paley Street' Flood Warning Area.

Access would be from the B3034 (Forest Road). This road is likely to be flooded by fluvial events on The Cut with a probability of 1 in 75-year event and above. However, Access and access from the west would remain dry. The RoFfSW predicts that surface water is egress likely to pond on the road during a 1 in 30-year event, with flooding all along the frontage of the site at the 1 in 100-year event and above.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and Soil type clayey soils

Typical slope 0.032

Groundwater Source SPZ3 Protection Zone?

Historic Landfill Site? No

Requirements for planning and NPPF

The Sequential Test must to be passed. Only once the Sequential Test is passed should the Exception Test be applied. The Exception test will be required in the following scenarios: • If More Vulnerable and Essential Infrastructure is located in FZ3a. Sequential • If Highly Vulnerable development is located in FZ2. Test and • If Essential Infrastructure is located in Flood Zone 3b. Exception Development will not be permitted in the following scenarios: Test requirements • Highly Vulnerable infrastructure within FZ3a and FZ3b. • More Vulnerable and Less Vulnerable Infrastructure within FZ3b.

It must be shown that the development will be safe for its lifetime and the risk can be managed through a sequential approach to design. Requirements • Consultation with the LLFA and the Environment Agency should be undertaken at an for site- early stage. specific Flood Risk • A site-specific FRA will be required because the site is within Flood Zone 2 and 3 and Assessment at risk from sources of flooding other than rivers and the sea. Government guidance

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on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk- assessment-for-planning-applications). • All sources of flooding, particularly the risk of the coincidence of fluvial and surface water flooding, should be considered as part of a site-specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed developments in the Cut (Binfield to River Thames confluence) and Maidenhead Ditch catchment must be considered by the FRA and in planning decisions. • The Environment Agency should be consulted to obtain the latest hydraulic modelling information for The Cut at the time of the FRA. They will advise as to whether existing detailed models need to be updated. • A detailed hydraulic model should also be developed for the unnamed watercourse and surface water flow paths, to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. Coincidence of an event on The Cut should be considered. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016, but may be subject to change in the future. • Reservoir risk posed by Fish Pond at Ascot Place should be considered as part of emergency planning. • The impact of blockage of the B3034 road bridge should be modelled as part of the assessment. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing the volume and rate of runoff and creating space for flooding within the Flood Zones. • The development should be designed using a sequential approach. Flood Zones 2 and 3, and Flood Zone 3a plus 70% climate change (subject to a detailed flood risk assessment using up to date model information) should be preserved as green infrastructure, with built development restricted to Flood Zone 1. Development should also be steered away from surface water flow routes, preserving these areas as green infrastructure. Guidance for • Safe access and egress should be demonstrated in the 1 in 100-year plus 35% and, site design in consultation with the LLFA, the 1 in 100-year +70% climate change fluvial event. and making Access should also be safe in the 1 in 100-year plus 40% rainfall event. Raising of development access routes must not impact on flow routes. Consideration should be given to the safe from siting of access points with respect to fluvial and surface water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Resilience measures will be required for any buildings situated in Flood Zone 2. • Compensation storage would need to be provided for any land-raising within the 1 in 100 plus 35% climate change allowance. A safe access route must also be provided. • Flow routes must be preserved when carrying out land-raising within the surface water risk area. A safe access route must also be provided.

Requirements • A site-specific surface water drainage strategy will be required. for SuDS and surface water • Early liaison with Thames Water is recommended to obtain agreement in principle for management connection to the surface water sewer (if required).

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• Detailed site investigations will be required including infiltration testing. • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Low permeability may mean infiltration features cannot meet all drainage requirements. Conveyance features should be designed above ground and following natural flow paths where possible. • The design must consider the effects of modelled fluvial water levels, frequency, duration and velocities on performance and drain-down time of SuDS components. Attenuation storage for runoff from the development in extreme events should be located outside Flood Zone 2. • Choice of SuDS components should be based on detailed site information. Examples of appropriate SuDS may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development. The recommended allowance for climate change and urban creep at the time of the assessment should be included (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The site is within SPZ3. The Environment Agency’s Approach to Groundwater Protection (2017) and best practice design for water quality should be followed. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code BIN5 Site name Land south of Forest Road and east of Cheney Close

Area 1.84ha

Greenfield or previously developed Greenfield land

Proposed site use Housing and open space

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing There is an unnamed watercourse which flows from west to east along the southern drainage border of the site, and an offline pond just to the south. The ditch receives surface features water runoff from adjacent developments.

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No record of historical flooding on site. Note that rural greenfield sites may have experienced flooding that has not been recorded due to the lack of properties affected. Flood history Nearby, Council flood records show: • The junction of York Road and Tilehurst Lane experienced flooding in July 2007. No source or mechanism is identified, but this was predominantly a surface water event. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Available detailed modelling data: Fluvial N/A Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed ordinary watercourse to the south. This watercourse is unmodelled and does not have a Flood Zone. The watercourse is culverted under Wood Lane and culverted through the school playing fields. The RoFfSW gives an indication of possible flood risk from the watercourse. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 0.2% 7.6% 19.6% Description of surface water flow paths: Surface water sewers from the Emmets Park development are shown to discharge to the unnamed watercourse. The RoFfSW map shows surface water would follow and Surface Water be contained by the existing channel along the south boundary of the site in the 1 in 30-year event. In the 1 in 100-year event, three surface water flow routes start to form in the Emmets Park residential area and across the north and south of site Bin6. These paths converge at the western edge of Bin5, and join the unnamed watercourse. Flow is out of bank along the southern edge of the site. In the 1 in 1,000-year event, these flow paths and the areas contributing flow are much more apparent, and flooding will affect a larger area in the south of the site. Runoff from some of the golf course water features would flow towards this site during extreme events. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk Reservoir / There are no known reservoirs likely to pose a risk to this site. impounded An impounded pond is present within the golf course to the south of the site for irrigation water body purposes. Ponds and swales associated with the golf course are likely to overflow to failure the ditch.

Canal There are no canals in Bracknell Forest. The site is within postcode area RG424, which has 1 property on the Thames Water Sewer Sewer Flooding Register. This is a very small proportion of the total properties in this postcode area.

Impact of climate change

River Basin District Central Higher Upper End Central

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Climate change allowances for Thames 25% 35% 70% river flow for the ‘2080s’

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitivity range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of flooding from from other surface water flooding and the unnamed ordinary watercourse. sources

Cumulative impact of Development

Water Framework Directive BIN5 is within the Cut (Binfield to River Thames confluence) and (WFD) catchment name Maidenhead Ditch catchment 15 Proposed development 3% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment Medium. The Thames (Cookham to Egham) catchment has a high risk Susceptibility of downstream to properties but a very large catchment area upstream of The Cut catchment which will reduce the relative impact of tributaries.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping. breach / overtopping? The watercourse is culverted under Emmets Park upstream of the site. At the south east corner of the site it flows under Wood Lane via a 450mm diameter Risk of culvert / culvert. The watercourse continues within 450mm culvert through the school structure blockage? playing fields. Given the currently heavily wooded vegetated nature of the watercourse, the risk of blockage is high.

9 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access to the site would be from the B3034 (Forest Road) with pedestrian/cycle access to Wood Lane. The B3034 road is likely to be flooded by a fluvial event on Access and The Cut with a probability of 1 in 75-year event and above, or an extreme surface egress water event, but access would be dry from the west. The RoFfSW predicts that surface water following the unnamed watercourse would impact Wood Lane at a 1 in 100-year event and above.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils.

Typical slope 0.017

Groundwater Source SPZ3 Protection Zone?

Historic Landfill No Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed Requirements (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). for site- specific • All sources of flooding, particularly the risk of surface water flooding, should be Flood Risk considered as part of a site-specific flood risk assessment. Assessment • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed developments in the Cut (Binfield to River Thames confluence) and Maidenhead Ditch catchment must be considered by the FRA and in planning decisions.

10 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate; including surface water sewers from adjacent development and runoff from the golf course. • A detailed hydraulic model should be developed of the unnamed watercourse, surface water sewer system and surface water flow paths to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of blockage of the structure upstream of the site (under Emmets Park) and on the eastern edge of the site (under Wood Lane) should be considered as part of the assessment. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and the ordinary watercourse, Guidance for preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing. • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. Requirements • All development should adopt source control SuDS techniques. Low permeability for SuDS and may mean infiltration features cannot meet all drainage requirements. Conveyance surface water features should be designed above ground and following natural flow paths where management possible. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. The structure under Wood Lane is relatively shallow and therefore SuDS features may also need to be wide and shallow. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep).

11 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Storage for runoff from the development in extreme events should be located out of flood risk areas as defined by the Flood Risk Assessment. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • The site is within an SPZ3. The Environment Agency’s Approach to Groundwater Protection (2017) and best practice design for water quality should be followed. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code BIN6 Site name Land south of Emmets Park and east of Cressex Close

Area 1.56ha

Greenfield or previously developed Greenfield land

Proposed site use Housing and open space

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing There is an unnamed watercourse apparent on the OS map which appears to be drainage culverted in the vicinity of the northern border of the site, flowing from west to east.The features ditch receives surface water runoff from upsteam of the development. There is no record of historical flooding on the site. Note that rural greenfield sites may have experienced flooding that has not been recorded, due to the lack of properties affected. Flood history Nearby, Council flood records show: •The junction of York Road and Tilehurst Lane experienced flooding in July 2007. No source or mechanism is identified but this was predominantly a surface water event. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Available detailed modelling data: Fluvial N/A Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed ordinary watercourse to the north of the site. This watercourse is unmodelled and does not have a Flood Zone associated with it. The RoFfSW gives an indication of flood risk from the watercourse.

12 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 0.1% 6.4% 14.5% Description of surface water flow paths: The site is at low risk of surface water flooding in the 1 in 30-year event. In the 1 in 100-year event two surface water flow routes form, one along the northern boundary Surface Water of the site, and a second across the southern corner, flowing north east. These routes converge to the west, before flowing into site Bin5. In the 1 in 1,000-year event, these flow paths and the areas contributing flow are much more extensive, and flooding will affect a larger area in the north and south east of the site.

Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The site is within postcode area RG424, which has 1 property on the Thames Water Sewer Sewer Flooding Register. This is a small proportion of the total properties in the postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitivity range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

13 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Cumulative impact of Development Water Framework Directive BIN6 is within the Cut (Binfield to River Thames confluence) and (WFD) catchment name Maidenhead Ditch catchment 15 Proposed development 3% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment Medium. The Thames (Cookham to Egham) catchment has a high risk Susceptibility of downstream to properties but a very large catchment area upstream of The Cut catchment which will reduce the relative impact of tributaries.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present (SoP)

Environment Agency’s No flood defences present defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / The watercourse appears to be culverted under the site within a 600mm structure blockage? diameter pipe. This may have the potential for blockage.

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

It is assumed that access (including pedestrian/cycle access) would be via Emmets Access and Park to the north. This road is at risk of surface water flooding in the 1 in 100-year egress event, which becomes more extensive in the 1 in 1,000-year event.

14 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.083

Groundwater Source Protection No Zone?

Historic Landfill No Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed Requirements developments in the Cut (Binfield to River Thames confluence) and Maidenhead Ditch for site- catchment must be considered by the FRA and in planning decisions. specific • A detailed hydraulic model should be developed of the unnamed watercourse, surface Flood Risk water flow paths and existing sewers to better understand baseline and post- Assessment development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The capacity and condition of the structure carrying the unnamed watercourse under the site should be surveyed and modelled as part of the assessment, and its capacity to convey extreme flows should be demonstrated. The impact of blockage of this structure should be consideredand the potential for deculverting the watecourse investigated.

15 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes, preserving these areas as Guidance for green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing. • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. Consideration should be given to deculverting the watercourse. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • Low permeability may mean infiltration features cannot meet all drainage Requirements requirements. The site is relatively steep and this should be considered in the design for SuDS and (for example permeable paving can become ineffective on steep slopes). Choice of surface water SuDS components should be based on detailed site information, examples may management include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep both to the existing off-site catchment and proposed). • Storage for runoff from the development in extreme events should be located out of flood risk areas as defined by the Flood Risk Assessment. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

16 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BIN8 Site name Land south of Foxley Lane and west of Murrell Hill Lane (Foxley Fields)

Area 41.49ha

Greenfield or previously developed Greenfield land

Proposed site use Housing, open space and SANG

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing There is an unnamed watercourse flowing north westerly across the site. This drains drainage into the Emm Brook catchment, which crosses into Wokingham District. There are also features two small ponds shown on OS mapping on the southern edge of the site.

Flood history BFC Highways note that flooding has occurred on the highway from Popes Meadow. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Available detailed modelling data: Fluvial N/A Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed ordinary watercourse flowing through the site. This watercourse is unmodelled and does not have a Flood Zone associated with it. The RoFfSW gives an indication of possible flood risk from the watercourse. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 3.1% 6.7% 19.4% Description of surface water flow paths: The 1 in 30-year RoFfSW shows a surface water flow route originating on farmland just Surface Water south of Bin9 and flowing north into Bin8, where it follows the unnamed watercourse through the site. In the 1 in 100-year event, this flow route increases in size, and additional flow routes start to develop, entering the site from the north and east. At the 1 in 1,000-year event, all flow paths become more extensive, and flooding spreads across a wider area to the south of the ordinary watercourse. The contributing surface water catchment is evident, comprising the residential area to the north of Foxley Lane, Popes Meadow and farmland to the south bordered by London Road (B3408) Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories Groundwater 0-0.025m surface 0.025 to 0.5m 0.0% 0.0% 0.0%

17 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Description of groundwater risk: No groundwater flood risk Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The site is within postcode area RG424, which has 1 property on the Thames Water Sewer Sewer Flooding Register. This is a very small proportion of the total properties in this postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitivity range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative impact of Development

Water Framework Directive BIN8 is within the Twyford Brook catchment (WFD) catchment name 7 Proposed development 3% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Loddon (Swallowfield to River Thames confluence) is mostly catchment rural with extensive floodplains, and low risk to properties.

18 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping. breach / overtopping? There are several small structures on the ordinary watercourse within the site, Risk of culvert / located at track crossings etc. These have the potential to block easily, but water structure blockage? would flow easily over and around them, so this is unlikely to impact greatly on the extent of flooding.

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

The site is likely to be accessed via Foxley Lane to the north of site and Murrelhill Access and Lane to the east of the site. Both may experience surface water ponding in a 1 in 30- egress year event upwards, and by the 1 in 1,000-year event there would be significant flooding on both routes.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.028

Groundwater Source SPZ3 Protection Zone?

Historic Landfill Site? No

19 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. Requirements • The cumulative impact on flood risk of this development and other proposed for site- developments in the Twyford Brook catchment must be considered by the FRA and in specific planning decisions. Flood Risk Assessment • A detailed hydraulic model should be developed of the unnamed watercourse and surface water flow paths to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of structure or culvert blockage should be considered as part of the assessment. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes, preserving these areas as Guidance for green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area.

Requirements • A site-specific surface water drainage strategy will be required. for SuDS and • Early liaison with Thames Water is recommended to obtain agreement in principle for surface water connection to the surface water sewer (if required). management • Detailed site investigations will be required including infiltration testing.

20 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Low permeability may mean infiltration features cannot meet all drainage requirements. Conveyance features should be designed above ground and following natural flow paths where possible. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas as defined by the Flood Risk Assessment. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • The site is within an SPZ3. The Environment Agency’s Approach to Groundwater Protection (2017) and best practice design for water quality should be followed. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

21 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BIN9 Site name Land at Murrell Hill Grange, Murrell Hill Lane

Area 18.23ha

Greenfield or previously developed Greenfield land

Proposed site use Housing, open space and SANG

Flood risk More vulnerable vulnerability

Sources of flood risk

There is an unnamed watercourse flowing from south to north through the site and out Existing into Bin8. It appears to have been modified for ornamental use. It flows through a drainage large pond within the site. Drainage from the Amen Corner development site drains to features the watercourse via a SuDS system. Flood history BFC Highways note that flooding has occurred on the highway from Popes Meadow. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Available detailed modelling data: Fluvial N/A Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed ordinary watercourse flowing through the site. This watercourse is unmodelled and does not have a Flood Zone. The RoFfSW gives an indication of possible flood risk from the watercourse. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 3.3% 5.3% 12.9% Surface Water Description of surface water flow paths: The 1 in 30-year RoFfSW shows a surface water flow route originating on recently developed land just south of Bin9 and flowing north into Bin8, following the unnamed watercourse. In the 1 in 100-year and 1 in 1,000-year events, the flow path converges with other areas of surface water flood risk, becoming more extensive. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 4.6% 4.6% Description of groundwater risk: There are small areas in the two southern corners of the site where groundwater levels are predicted to be between 0.025 and 0.5m below the ground surface in the 1 in 100- year event. These are in areas where surface water flow paths originate and the two sources may interact.

22 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Reservoir / There are no known reservoirs likely to pose a risk to this site. impounded To the south of the site, a balancing pond associated with the Amen Corner water body development is located. In the event of failure, the water would follow the existing failure surface water flood routes.

Canal There are no canals in Bracknell Forest. The site is within postcode area RG42 4, which has 1 property on the Thames Water Sewer Sewer Flooding Register. This is a very small proportion of the total properties in this postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows, is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

23 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Cumulative Impact of Development Water Framework Directive BIN9 is within the Twyford Brook catchment (WFD) catchment name 7 Proposed development 3% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Loddon (Swallowfield to River Thames confluence) is mostly catchment rural with extensive floodplains, and low risk to properties. Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present (SoP)

Environment Agency’s No flood defences present defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping? There are several small footbridges on the ornamental section of the Risk of culvert / watercourse, and it appears to be culverted downstream of the pond into Bin8. structure blockage? Structures/controls associated with the pond need to be investigated further.

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

The site is likely to be accessed via Murrelhill Lane (enhancements would be Access and required) to the east of the site. This is likely to experience surface water ponding in egress events of a 1 in 30-year probability upwards, and by the 1 in 1,000-year event there would be significant flooding on this route.

24 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.031

Groundwater Source Protection No Zone?

Historic Landfill No Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding and groundwater risk, should be considered as part of a site-specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed Requirements developments in the Twyford Brook catchment must be considered by the FRA and in for site- planning decisions. specific • A detailed hydraulic model should be developed of the unnamed watercourse and Flood Risk surface water flow paths to better understand baseline and post-development surface Assessment water risk flowing into the site, on site and downstream. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months (see below). • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The operation of structures on the ornamental sections of the watercourse and potential for blockage should be considered as part of the assessment.

25 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater is likely to be close to the ground surface, preserving these areas as green Guidance for infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • The design of SUDS schemes must take into account the seasonally high groundwater table in the south of the site and low permeability. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be Requirements shallow and take up larger areas. Above ground conveyance and attenuation can be for SuDS and used but care must be taken that groundwater does not enter the SuDS feature and surface water reduce the storage capacity and structural integrity of the design. management • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas as defined by the Flood Risk Assessment. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

26 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BIN11 Site name Popes Farm, Murrell Hill Lane

Area 1.89ha

Greenfield or previously developed Greenfield land

Proposed site use Housing and open space

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. drainage features BFC Highways note that flooding has occurred previously on the highway from Popes Flood history Meadow. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: This site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 0.5% 1.4% 9.1% Surface Water Description of surface water flow paths: A surface water flow route starts to develop on Bin11 at the 1 in 30-year return period, becoming linked downstream through neighbouring sites Bin9 and Bin8 at the 1 in 100- year return period. At the 1 in 1,000-year return period, the flow route starts off site to the south and flows through the western part of Bin11. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 100.0% 100.0% Description of groundwater risk: Groundwater levels are predicted to be between 0.025 and 0.5m below the ground surface across the whole site for the 1 in 100-year event. This area of groundwater risk coincides with surface water flow paths, and the two sources of flooding may interact.

27 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. This site covers 2 postcode areas. The northern part of the site is within RG42 4, which has 1 property on the Thames Water Sewer Flooding Register. The south east Sewer of the site is within RG12 8, which has 2 properties on the register. This is a very small proportion of the total properties in these postcode areas.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows, is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development Water Framework Directive BIN11 is within the Twyford Brook catchment (WFD) catchment name 7 Proposed development 3% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Loddon (Swallowfield to River Thames confluence) is mostly catchment rural with extensive floodplains, and low risk to properties.

28 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

The site would be accessed via Murrell Lane with suitable improvement to aid access. Access and Pedestrian/cycle access would be to B3408 London Road. Both are at risk of some egress isolated surface water flooding ponding in the 1 in 1,000-year event.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Sands and silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.024

Groundwater Source No Protection Zone?

Historic Landfill No Site?

29 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, groundwater flooding and the interaction between them, should be considered as part of a site- specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must Requirements be considered and modelled where appropriate. for site- • The cumulative impact on flood risk of this development and other proposed specific developments in the Twyford Brook catchment must be considered by the FRA and in Flood Risk planning decisions. Assessment • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater risk is highest, preserving these areas as green infrastructure. Guidance for • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate site design change rainfall event. Raising of access routes must not impact on flow routes. and making Consideration should be given to the siting of access points with respect to surface development water flood risk areas. safe from flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area.

• A site-specific surface water drainage strategy will be required. Requirements for SuDS and • Early liaison with Thames Water is recommended to obtain agreement in principle for surface water connection to the surface water sewer (if required). management • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March).

30 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • The design of SUDS schemes must take into account the seasonally high groundwater table and low permeability. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

31 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BIN12 Site name Eastern Field, land south of London Road

Area 0.31ha

Greenfield or previously developed Greenfield land

Proposed site use Housing

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. drainage features No record of historical flooding. Note that rural greenfield sites may have experienced Flood history flooding that has not been recorded, due to the lack of properties affected. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: This site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year Surface Water 0.0% 0.0% 0.0% Description of surface water flow paths: Risk of surface water flooding is low. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 100.0% 100.0% Description of groundwater risk: Groundwater levels are predicted to be between 0.025 and 0.5m below the ground surface across the whole site for the 1 in 100-year event. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure There are no canals in Bracknell Forest. Canal

32 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

The site is within RG42 4, which has 1 property on the Thames Water Sewer Sewer Flooding Register. This is a very small proportion of the total properties in this postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows, is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive BIN12 is within the Cut at west Bracknell catchment (WFD) catchment name 9 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties

33 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

The site may be accessed by a smaller road called London Road, which runs parallel Access and to the B3408. The main B3408 has some isolated areas of ponding surface water egress flooding in the 1 in 1,000-year event, but the smaller road is a low risk within the vicinity of the site.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Sands and silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.011

Groundwater Source Protection No Zone?

Historic Landfill No Site?

34 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because though the site is under 1ha in area in Flood Zone 1 it is at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly groundwater risk, should be considered as part of a site-specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must Requirements be considered and modelled where appropriate. for site- specific • The cumulative impact on flood risk of this development and other proposed Flood Risk developments in the Cut at west Bracknell catchment must be considered by the FRA Assessment and in planning decisions. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from areas where groundwater is likely to be highest, Guidance for preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing and Requirements groundwater monitoring during the winter months (November through to March). for SuDS and • SuDS are possible on all sites including small ones such as this. surface water • All development should adopt source control SuDS techniques. Conveyance management features should be designed above ground and following natural flow paths where possible. • The design of SUDS schemes must take into account the seasonally high groundwater table and low permeability. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger

35 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

36 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BIN16 Site name Land between Cain Road and Turnpike Road (3M recreational land)

Area 0.85ha

Greenfield or previously developed Previously Developed Land land

Proposed site use Housing and open space.

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site, although a drain is shown on OS mapping to the west drainage of the site which may be piped or culverted through the site. features

Flood history No incidents have been recorded on the site or surrounding roads. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: The site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 5.6% 13.5% 28.9% Description of surface water flow paths: Surface Water The RoFSW map shows the northern part of the site is at risk of surface water flooding as a result of the flow path following Turnpike Road from west to east. This may be associated with the drain shown on OS mapping. In the 30-year event there is ponding in the northern corner of the site. In the 1 in 100-year event a connected flow path forms, and there is extensive flooding from a 1 in 1,000-year event. The roads surrounding the site are also affected. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk shown on the JBA Groundwater map

37 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in the Borough. This site falls within RG42 1 which has no properties on the Thames Water Sewer Sewer Flooding Register.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitive range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative Impact of Development Water Framework Directive BIN16 is within the Cut at west Bracknell catchment (WFD) catchment name 9 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties

38 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Proposed access is from Turnpike Road or Cain Road. Both of the proposed access Access and routes have no recorded flood incidents however are at risk of surface water flooding egress in all return periods. The surface water flooding affects large stretches of both roads, potentially limiting access to the site.

Sustainable drainage and flood risk betterment

Bedrock Clay, silt, sand and gravel Geology

Superficial N/A Geology

Soil type Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey soils

Typical slope 0.032

Groundwater Source No Protection Zone?

Historic No Landfill Site?

39 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because is under 1ha in area in Flood Zone 1 but could be affected by sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). Requirements • All sources of flooding, particularly the risk of surface water flooding, should be for site- considered as part of a site-specific flood risk assessment. specific • The impact of the development on flood risk from all sources both on and off-site must Flood Risk be considered and modelled where appropriate. Assessment • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater Guidance for is likely to emerge, preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Resilience measures will be required if buildings are situated in the flood risk area. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area, including to provide a safe access route. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer if required. Requirements • Existing surface water flow routes from off-site must be accommodated within the for SuDS and masterplan. surface water • features should be designed above ground and following natural flow paths where management possible. • Low permeability may mean infiltration features cannot meet all drainage requirements. • SuDS are possible on all sites, even previously developed sites such as this one.

40 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Example features may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

41 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BIN17 Site name Land north of Tile House and Honeysuckle Cottage, Tilehurst Lane

Area 0.62ha

Greenfield or previously developed Greenfield land

Proposed site use Housing and open space.

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. drainage features No flood incidents have been recorded on site. Note that rural greenfield sites may have experienced flooding that has not been recorded due to the lack of properties that Flood history would be affected. LLFA records show that Tilehurst Lane, particularly the junction with York Road close to the site, has experienced highway flooding on multiple occasions in July 2007, June 2008, and May 2012. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A. Detailed nature of flood characteristics: The site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 0.4% 10.5% 44.9% Description of surface water flow paths: Surface Water The RoFfSW map shows risk from surface water is low in the 1 in 30-year event. However in the 1 in 100-year event two flow paths have formed conveying runoff from Binfield towards The Cut, along the road to the west and through the centre of the site. 1,000In the 1 in 1,000-year event, flooding is extensive. The roads surrounding the site are also significantly affected by surface water. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk shown on the JBA Groundwater map.

42 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in the Borough. This site falls within RG42 5 which has no properties on the Thames Water Sewer Sewer Flooding Register.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitive range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative Impact of Development

Water Framework Directive BIN17 is within the Cut (Binfield to River Thames confluence) and (WFD) catchment name Maidenhead Ditch catchment 15 Proposed development 3% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment Medium. The Thames (Cookham to Egham) catchment has a high risk Susceptibility of downstream to properties but a very large catchment area upstream of The Cut catchment which will reduce the relative impact of tributaries.

43 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Proposed access to the site is via a gravel track (serving Binfield Park/Binfield Park Farm) which is accessed off of Tilehurst Lane. Both of these access roads are Access and affected by surface water flooding in all return periods. Additionally, LLFA records egress show that Tilehurst Lane experienced highway flooding on multiple occasions in July 2007, June 2008, and May 2012.

Sustainable drainage and flood risk betterment

Bedrock Clay, silt, sand and gravel Geology

Superficial N/A Geology

Soil type Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey soils

Typical slope 0.026

Groundwater Source SPZ3 Protection Zone?

Historic No Landfill Site?

44 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because is under 1ha in area in Flood Zone 1 but could be affected by sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must Requirements be considered and modelled where appropriate. for site- • The cumulative impact on flood risk of this development and other proposed specific developments in the Cut (Binfield to River Thames confluence) and Maidenhead Ditch Flood Risk catchment must be considered by the FRA and in planning decisions. Assessment • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of the development on any existing sewer flooding issues should be discussed with Thames Water at an early stage • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater Guidance for is likely to emerge, preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Resilience measures will be required if buildings are situated in the flood risk area. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area, including to provide a safe access route. Requirements • A site-specific surface water drainage strategy will be required. for SuDS and surface water • Early liaison with Thames Water is recommended to obtain agreement in principle for management connection to the surface water sewer if required.

45 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites, and a greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • Low permeability may mean infiltration features cannot meet all drainage requirements. • Example features may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code BIN18 Site name Beehive Road (Hewlett Packard)

Area 2.39ha

Greenfield or previously developed Greenfield land

Proposed site use Along with Cain Road ( BIN19), housing and open space.

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing drainage There is a large balancing pond in the centre-east of the site, believed to be a Thames features Water asset.

46 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

No flood incidents have been recorded on site, however the adjoining North View road has 2 recorded LLFA flood events (December 2012 and February 2010). Note that rural Flood history greenfield sites may have experienced flooding that has not been recorded due to the lack of properties that would be affected. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A. Detailed nature of flood characteristics: The site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 24.5% 36.7% 65.3% Description of surface water flow paths: Surface Water This site is at high risk of surface water flooding, with three separate flow paths entering the site in the 1 in 30 year event and above, and entering the pond on site. One of these flow paths comes from Bin19. In the 1 in 1,000-year event a large area of the site is affected and flows continues to the west. This flooding also affects multiple roads surrounding the site. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk shown on JBA Groundwater map. Reservoir / The balancing pond is not raised, and is surrounded by higher ground. Water levels impounded may be raised on site in a flood event, but the risk of overtopping or breach causing water body flooding downstream is low. failure

Canal There are no canals in the Borough. This site falls within RG12 8 which has 2 properties on the Thames Water Sewer Sewer Flooding Register. This is a small proportion of the total properties in the postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

47 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Climate change is predicted to increase rainfall intensity in the future by a range of Impact of between 20% and 40% (the recommended national precautionary sensitive range for climate change 2085 to 2115). This will increase the likelihood, frequency and extent of surface water on flood risk flooding. from other Climate change is likely to reduce the design standard of the existing balancing pond sources on site. It is likely to have been designed to a 1 in 30-year standard, and this may reduce significantly with climate change.

Cumulative Impact of Development

Water Framework Directive BIN18 is within the Cut at west Bracknell catchment (WFD) catchment name 9 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties

Flood risk management infrastructure and residual risk

Defence type This site includes a balancing pond which has a beneficial impact downstream.

Standard of protection Estimated to be 1 in 30-year (SoP)

Environment Agency’s N/A defence condition assessment The balancing pond is not raised, and is surrounded by higher ground. Water Risk of defence levels may be raised on site in a flood event, but the risk of overtopping or breach breach / overtopping? causing flooding downstream is low. Risk of culvert / There is a risk the outlet of the balancing pond may become blocked. structure blockage?

48 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Proposed access is from Beehive Road which has predicted flooding in both the 1 in Access and 30-year and 1 in 100-year surface water events. The adjoining North View road also egress has 2 recorded LLFA flood events (December 2012 and February 2010).

Sustainable drainage and flood risk betterment

Bedrock Clay, silt, sand and gravel Geology

Superficial N/A Geology

Soil type Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey soils

Typical slope 0.093

Groundwater Source No Protection Zone?

Historic No Landfill Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

Requirements • Consultation with the LLFA should be undertaken at an early stage. for site- • A site-specific flood risk assessment will be required because the site is over 1ha in specific area within Flood Zone 1 and could be affected by sources of flooding other than rivers Flood Risk and the sea. Government guidance on flood risk assessments must be followed Assessment (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications).

49 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed developments in the Cut at west Bracknell catchment must be considered by the FRA and in planning decisions. • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of the development on any existing sewer flooding issues should be discussed with Thames Water at an early stage • The design standard of the existing balancing pond on site must be confirmed and accounted for in the FRA. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater Guidance for is likely to emerge, preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Resilience measures will be required if buildings are situated in the flood risk area. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area, including to provide a safe access route. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer if required. • The existing balancing pond must be included in any surface water drainage strategy. • The ownership of the balancing pond and associated infrastructure must be established, and maintenance and management agreed in the long-term. • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites, and a large greenfield site such as this should be Requirements able to implement an exemplar scheme to deliver multiple benefits including water for SuDS and quality, biodiversity, amenity, green infrastructure etc. surface water management • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • Low permeability may mean infiltration features cannot meet all drainage requirements. • Example features may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of

50 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code BIN19 Site name Cain Road (Hewlett Packard)

Area 7.24ha

Greenfield or previously developed Previously Developed Land land

Proposed site use Along with Beehive Road ( BIN18), housing and open space.

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. drainage features No flood incidents have been recorded on the site. LLFA records show flooding along Flood history the adjacent North View Road in December 2012 and February 2010, however the mechanism was not identified in either event. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change Fluvial 0.0% 0.0% 0.0% 100.0% 0.0% Available detailed modelling data: N/A.

51 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Detailed nature of flood characteristics: The site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 1.6% 5.3% 13.6% Surface Water Description of surface water flow paths: The RoFfSW map shows flooding predominantly occurs along roads within the site and along the western boundary at the 1 in 30-year return period and above. Thes flow path along the western boundary, contributes to the ponding occuring in BIN18. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk shown on the JBA Groundwater map. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in the Borough. This site is partially within RG12 8 which has 2 properties on the Thames Water Sewer Flooding Register. However, the majority is within RG12 1 which has no properties on Sewer the Thames Water Sewer Flooding Register. This is a low proportion of the total properties in these postcode areas.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitive range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative Impact of Development

52 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Water Framework Directive BIN19 is within the Cut at west Bracknell catchment (WFD) catchment name 9 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation scheme. Defence type Surface water from the western edge of the site would flow into the balancing pond within BIN18 during a flood event. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping? No known structures on site. Risk of culvert / structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access is proposed from Cain Road or Beehive Road which are both predicted to Access and experience flooding in all surface water return periods. Flooding is also predicted on egress existing roads within the site.

53 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Sustainable drainage and flood risk betterment

Bedrock Clay, silt, sand and gravel Geology

Superficial N/A Geology

Soil type Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey soils

Typical slope 0.022

Groundwater Source No Protection Zone?

Historic Yes - a large area in the south of the proposed site overlies the Beehive South West Landfill Site? landfill site.

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and could be affected by sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. Requirements • The impact of the development on flood risk from all sources both on and off-site must for site- be considered and modelled where appropriate. specific • The cumulative impact on flood risk of this development and other proposed Flood Risk developments in the Cut at west Bracknell catchment must be considered by the FRA Assessment and in planning decisions. • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments-climate-change- allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of the development on any existing sewer flooding issues should be discussed with Thames Water at an early stage

54 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater Guidance for is likely to emerge, preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Resilience measures will be required if buildings are situated in the flood risk area. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area, including to provide a safe access route. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer if required. • Existing drainage/SuDS on site should be understood and taken into account in the design. • Existing surface water flow routes from off-site must be accommodated within the masterplan. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • Low permeability may mean infiltration features cannot meet all drainage requirements. Requirements • SuDS are possible on all sites, including previously developed sites such as this one. for SuDS and • Example features may include swales, attenuation features, green roofs, rainwater surface water capture and reuse and permeable paving. management • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

55 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BRA1 Site name Land at Parkview Farm, Old Wokingham Road

Area 38.29ha

Greenfield or previously developed Greenfield land

Proposed site use Housing, open space, SANG and primary school

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing There is an unnamed watercourse flowing along the southern border of the site, and a drainage smaller tributary in the north of the site. Both flow west into the Emm Brook catchment features in Wokingham District. There is also a large pond in the south west corner of the site. No record of historical flooding. Note that rural greenfield sites may have experienced Flood history flooding that has not been recorded due to the lack of properties affected. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.9% 0.0% 0.2% 98.9% 1.1% Available detailed modelling data: The Flood Zones for the unnamed watercourse are assumed to be based on broad- Fluvial scale national JFlow modelling. Detailed nature of flood characteristics: A very small area of the site along the southern border is at risk from the unnamed watercourse in the 1 in 100-year event and above. However, the site slopes steeply upwards away from the channel and the floodplain appears to be contained. As the watercourse has not been modelled in detail, no information is available about risk at lower return periods, or depths, hazards or velocities. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 2.7% 4.7% 13.5% Description of surface water flow paths: Surface Water In the 1 in 30-year event, surface water follows the two ordinary watercourses, with some ponding on the existing road through the site. This increases slightly during the 1 in 100-year event, but in the 1 in 1,000-year event there is a substantial flow route between the two tributaries, along the road. This surface water clearly originates across a large catchment including residential areas of west Bracknell such as Great Hollands, and flows out to the west into Wokingham District. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories Groundwater 0-0.025m surface 0.025 to 0.5m 6.3% 2.2% 8.6%

56 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Description of groundwater risk: There is an area in the centre-west of the site where there is a risk of groundwater emergence (within 0.025m of the ground surface) in a 1 in 100-year event. A small area to the centre-east of the site may experience groundwater levels of between 0.025 and 0.5m below the ground surface in the 1 in 100-year event. These areas do not coincide with the major surface water flow paths on site. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The site is within postcode area RG40 3, which has 3 properties on the Thames Water Sewer Sewer Flooding Register. This is a very small proportion of the total properties in the postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70% Climate change under both the +35% and +70% scenarios is likely to increase the area Impact of of Flood Zone 3a slightly to be similar to the current Flood Zone 2. The floodplain is climate change well-contained by the topography and the overall extent of the areas at flood risk is not on fluvial likely to increase significantly. flooding and Fluvial flooding is likely to become more frequent under both climate change scenarios, the Flood Zone and the impact of an event with a given probability is also likely to become more classification severe, with extents, depths, velocities and flood hazard increasing. Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

57 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Cumulative Impact of Development

Water Framework Directive BRA1 is within the Emm Brook catchment (WFD) catchment name 6 Proposed development 5% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Loddon (Swallowfield to River Thames confluence) is mostly catchment rural with extensive floodplains, and low risk to properties.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping? The ordinary watercourse flows under the minor road and Old Wokingham Road. Risk of culvert / These structures have the potential for blockage. Structures/controls associated structure blockage? with the pond need to be investigated further and blockage scenarios tested.

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access is likely to be either directly off Old Wokingham Road or via the existing minor Access and road which comes through the site, which has limited visibility. Both may experience egress some isolated flooding from the 1 in 30-year and above, with access likely to be very difficult in a 1 in 1,000-year event.

58 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.021

Groundwater Source No Protection Zone?

Historic Landfill Site? No

Requirements for planning and NPPF

The Sequential Test must to be passed. Only once the Sequential Test is passed should the Exception Test be applied. The Exception test will be required in the following scenarios: • If More Vulnerable and Essential Infrastructure is located in FZ3a. Sequential • If Highly Vulnerable development is located in FZ2. Test and • If Essential Infrastructure is located in Flood Zone 3b Exception Development will not be permitted in the following scenarios Test requirements • Highly Vulnerable infrastructure within FZ3a and FZ3b. More Vulnerable and Less Vulnerable Infrastructure within FZ3b.

It must be shown that the development will be safe for its lifetime and the risk can be managed through a sequential approach to design. • Consultation with the LLFA and the Environment Agency should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is within Flood Zone 2 and 3 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, groundwater flooding, and the interaction between them, should be considered as part of a site- Requirements specific flood risk assessment. for site- • The impact of the development on flood risk from all sources both on and off-site must specific be considered and modelled where appropriate. Flood Risk • The cumulative impact on flood risk of this development and other proposed Assessment developments in the Emm Brook catchment must be considered by the FRA and in planning decisions. • A detailed hydraulic model should be developed of the unnamed watercourse and surface water flow paths to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. Particular attention should be paid to the upstream densely developed catchment draining through the site. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months (see below).

59 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of structure or culvert blockage and the operation of the pond should be considered as part of the assessment. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Flood Zones 2 and 3, and Flood Zone 3a plus 70% climate change (subject to a detailed flood risk assessment using up to date model information) should be preserved as green infrastructure, with built development restricted to Flood Zone 1. Development should be steered away from surface water flow routes and areas where groundwater is likely Guidance for to emerge, preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 35% and, and making in consultation with the LLFA, the 1 in 100-year +70% climate change fluvial event. development Access should also be safe in the 1 in 100-year plus 40% rainfall event. Raising of safe from access routes must not impact on flow routes. Consideration should be given to the flooding siting of access points with respect to surface water flood risk areas. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features Requirements should be designed above ground and following natural flow paths where possible. for SuDS and • The design of SUDS schemes must take into account the seasonally high surface water groundwater table and low permeability. Infiltration techniques may be ineffective, management and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • Designing to provide adequate water quality treatment stages should be considered at the outset. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep).

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• Storage for runoff from the development in extreme events should be located out of flood risk areas as defined by the site-specific Flood Risk Assessment. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code BRA3 Site name The Hideout, Old Wokingham Road (West Road)

Area 22.61ha

Greenfield or previously developed Greenfield land

Proposed site use Housing, open space, SANG and care home

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing Small unnamed land drains in the north and centre-east of the site are evident on OS drainage mapping. features BFC Highways records show three properties were flooded at Easthampstead Caravan Park in 2000, which borders the site to the west. The flood mechanism was not Flood history recorded. BFC Highways note that flooding has occurred in the past on the south side of Pinewood roundabout. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed land drains within the site. These watercourses are unmodelled and are not covered by a Flood Zone. Proportion of site at risk in Risk of Flooding from Surface Water Map Surface Water 1 in 30-year 1 in 100-year 1 in 1,000-year

61 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

1.4% 3.2% 19.1% Description of surface water flow paths: At the 1 in 30-year and 1 in 100-year event, surface water may pond in topographically isolated areas across the site. At the 1 in 1,000-year event, these areas are likely to join up into two coherent flow paths following the natural topography across the site (rather than the land drains). The surface water originates in the east of the site, and the Woodenhill area of Bracknell, and eventually flows into the Emm Brook catchment in Wokingham District. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m 73.4% 18.5% 91.9% Groundwater Description of groundwater risk: Most of the site is at risk of groundwater emergence in the 1 in 100-year event. Smaller areas to the north and south west of the site may experience groundwater levels of between 0.025 and 0.5m below the ground surface. The highest risk area coincides with surface water flow paths shown in the RoFfSW map, and the two sources of flooding may interact. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The site falls within postcode area RG40 3, which has 3 properties on the Thames Sewer Water Sewer Flooding Register. This is a very small proportion of the total properties in the postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

62 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Cumulative Impact of Development

Water Framework Directive BRA3 is within the Emm Brook catchment (WFD) catchment name 6 Proposed development 5% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Loddon (Swallowfield to River Thames confluence) is mostly catchment rural with extensive floodplains, and low risk to properties.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

63 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access to the site would be via West Road, Old Wokingham Road and/or possibly in association with BRA4, Nine Mile Ride (B3430). Old Wokingham Road is at risk from Access and flooding by a surface water flow path in the 1 in 30-event and above, but dry access egress is still possible from the north via West Road. Nine Mile Ride is also dry up to the 1 in 100-year event, but experiences some flooding in the 1 in 1,000-year event.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Sands and silt

Superficial Geology N/A

Soil type Naturally wet very acid sandy and loamy soils

Typical slope 0.012

Groundwater Source No Protection Zone?

Historic Landfill Site? No

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed Requirements (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). for site- • All sources of flooding, particularly the risk of surface water flooding, groundwater specific flooding, and the interaction between them should be considered as part of a site- Flood Risk specific flood risk assessment. Assessment • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed developments in the Emm Brook catchment must be considered by the FRA and in planning decisions.

64 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months (see below). The assessment should consider the potential risk of displacement of groundwater and the potential for increases in base flow to watercourses off-site. Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments-climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater is likely to emerge, preserving these areas as green infrastructure. Guidance for • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate site design change rainfall event. Raising of access routes must not impact on flow routes. and making Consideration should be given to the siting of access points with respect to surface development water flood risk areas. safe from • The design must ensure that surface water flows resulting from rainfall in excess of a flooding 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance Requirements features should be designed above ground and following natural flow paths where for SuDS and possible. surface water • The design of SUDS schemes must take into account the seasonally high management groundwater table and low permeability. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep).

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• The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code BRA4 Site name Beaufont Park, Nine Mile Ride (South Road)

Area 34.16ha

Greenfield or previously developed Greenfield land Housing, open space and SANG Proposed site use

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing Small unnamed land drains evident on the OS map in the south of the site. drainage features BFC Highways records show three properties were flooded at Easthampstead Caravan Park in 2000, to the west of the site. The flood mechanism was not recorded. BFC Flood history Highways note that flooding frequently occurs to the east of BRA4 across the recreation ground, and of Nine Mile Ride south of the site between the TRL site and Old Wokingham roundabout and the south side of Pinewood roundabout. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed land drains within the site. These watercourses are unmodelled and are not covered by a Flood Zone. Proportion of site at risk in Risk of Flooding from Surface Water Map Surface Water 1 in 30-year 1 in 100-year 1 in 1,000-year 0.4% 1.2% 9.1%

66 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Description of surface water flow paths: At the 1 in 30-year year event there are a few, very minor, isolated areas of ponding. In the 1 in 100-year event these are still minor, but a small flow route forms from South Road and along the minor access road, towards the existing building. At the 1 in 1,000- year event, a distinct flow path has developed, following the natural topography. It originates to the east of the site in the Woodenhill area of Bracknell, and flows across the site into BRA3. Flooding in the area east of the site across the recreation ground is experienced frequently. Drainage from Nine Mile Ride and the TRL site flows into the site.

Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 15.2% 84.0% 99.3% Description of groundwater risk: Most of the site may experience groundwater levels of between 0.025 and 0.5m below the ground surface in the 1 in 100-year event, with the west of the site predicted to be at risk of groundwater emergence (within 0.025m of the ground surface). These areas coincide with surface water flow paths, and the two sources of flooding may interact. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The site falls within postcode area RG40 3, which has 3 properties on the Thames Sewer Water Sewer Flooding Register. This is a very small proportion of the total properties in this postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification

67 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive BRA4 is within the Emm Brook catchment (WFD) catchment name 6 Proposed development 5% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Loddon (Swallowfield to River Thames confluence) is mostly catchment rural with extensive floodplains, and low risk to properties.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

68 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access is likely to be via South Road, Nine Mile Ride (B3430) and/or West Road. Both South Road and Nine Mile Ride experience minor flooding at the 1 in 100-year Access and event, which also affects the current minor access road into the site. Both roads egress experience more extensive flooding in the 1 in 1,000-year event. West Road would provide dry access in a 1 in 1,000-year event. Access may be provided in association with BRA3.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Sands and silt

Superficial Geology N/A

Soil type Naturally wet very acid sandy and loamy soils

Typical slope 0.018

Groundwater Source No Protection Zone?

Historic Landfill Site? No

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. There are likely to be significant issues with the condition of the existing drainage and its suitability to receive runoff. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the Requirements sea. Government guidance on flood risk assessments must be followed for site- (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). specific • All sources of flooding, particularly the risk of surface water flooding, groundwater Flood Risk flooding, and the interaction between them, should be considered as part of a site- Assessment specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed developments in the Emm Brook catchment must be considered by the FRA and in planning decisions.

69 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Detailed assessment of drainage catchments entering the site will be required, • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The existing land drainage must be improved to ensure on and off-site flooding is reduced. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater Guidance for is likely to emerge, preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the masterplan,particularly highway drainage and drainage from off-site developments. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. Requirements • All development should adopt source control SuDS techniques. Conveyance for SuDS and features should be designed above ground and following natural flow paths where surface water possible. management • The design of SUDS schemes must take into account the seasonally high groundwater table and low permeability. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of

70 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code BRA7 Site name Town Square, The Ring (comprising Easthampstead House, Bracknell Library, Magistrates Court and Police Station) Area 1.16ha

Greenfield or previously developed Previously Developed Land land

Proposed site use Housing, employment, open space and off-site SANG .

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. drainage features No record of historical flooding on the site. However BFC Highways records show flooding occurred in 2007 at Horsneile Lane, around 300m to the north-west. This area Flood history is downstream of the site, in the same surface water catchment. BFC Highways note that flooding has previously occurred in the underpass outside Easthampstead House and at the Met Office roundabout underpass leading to Bracknell College. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: This site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map Surface Water 1 in 30-year 1 in 100-year 1 in 1,000-year 2.2% 5.4% 11.6%

71 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Description of surface water flow paths: There is isolated ponding between the existing buildings in the centre of the site at the 1 in 30-year event, increasing slighly in the 1 in 100-year event. In the 1 in 1,000-year event, these areas of ponding converge with minor flow routes, flowing to the north- west. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. This site covers three postcode areas. Most of the site is within RG121 and RG429, which have no properties on the Thames Water Sewer Flooding Register. The far Sewer north of the site is within RG122, which has 2 properties on the register. This is a very small proportion of the total properties in this postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitivity range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative Impact of Development

72 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Water Framework Directive BRA7 is within the Cut (Warfield to north Bracknell) catchment (WFD) catchment name 8 Proposed development 11% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Medium within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access is likely to be from Weather Way/The Ring, and connections with existing Access and cycle/pedestrian routes from the Met Office Roundabout. There are small areas of egress ponding of surface water flooding on Weather Way from the 1 in 30-year event upwards, which may also affect pedestrian and cycle routes.

73 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.029

Groundwater Source No Protection Zone?

Historic Landfill No Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is under 1ha in area in Flood Zone 1 but at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. Requirements • The impact of the development on flood risk from all sources both on and off-site must for site- be considered and modelled where appropriate. specific • The cumulative impact on flood risk of this development and other proposed Flood Risk developments in the Cut (Warfield to north Bracknell) catchment must be considered Assessment by the FRA and in planning decisions. • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future.

74 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes, preserving these areas as Guidance for green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing. • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites, even small previously developed sites such as this one. • All development should adopt source control SuDS techniques. Low permeability may mean infiltration features cannot meet all drainage requirements. Other options should be considered to ensure interception of the first 5mm of rainfall can occur. Conveyance features should be designed above ground and following natural flow Requirements paths where possible. for SuDS and • Choice of SuDS components should be based on detailed site information, examples surface water may include, rain gardens, green roofs, rainwater capture and reuse and permeable management paving. Green roofs, permeable paving and rain gardens are suitable in urban settings. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

75 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BRA11 Site name Bus Depot (Coldborough House), Market Street

Area 0.61ha

Greenfield or previously developed Previously Developed Land land

Proposed site use Housing, employment and off-site SANG

Sources of flood risk

Existing No known watercourse on site. drainage features

Flood history No record of historical flooding. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: This site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 1.8% 2.3% 11.9% Description of surface water flow paths: Surface Water Risk of surface water flooding is confined to minor ponding along the eastern side of the existing bus depot building in the 1 in 30-year and 1 in 100-year. At the 1 in 100- year event, this extends to the north of the building, and a small flow route develops on the west of the site. It joins a signficantly larger flow route off-site emerging from the south, which flows around The Peel Centre. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest.

76 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

The site is within postcde area RG12 1, which has no properties on the Thames Water Sewer Flooding Register. This is a very small proportion of the total properties Sewer in this postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitivity range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative Impact of Development

Water Framework Directive BRA11 is within the Cut at west Bracknell catchment (WFD) catchment name 9 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

77 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access would be via Market Street, which experiences minor surface water ponding Access and in the 1 in 30-year and 1 in 100-year. Surface water flooding becomes more egress significant and likely to disrupt transport across Bracknell town centre in the 1,000- year event.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.007

Groundwater Source No Protection Zone?

Historic Landfill No Site?

78 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because though the site is under 1ha in area in Flood Zone 1 it is at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. Requirements • The impact of the development on flood risk from all sources both on and off-site must for site- be considered and modelled where appropriate. specific • The cumulative impact on flood risk of this development and other proposed Flood Risk developments in the Cut at west Bracknell catchment must be considered by the FRA Assessment and in planning decisions. • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes, preserving these areas as Guidance for green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). Requirements • Detailed site investigations will be required including infiltration testing. for SuDS and • Existing surface water flow routes from off-site must be accommodated within the surface water masterplan. management • SuDS are possible on all sites, even small previously developed sites such as this one. • All development should adopt source control SuDS techniques. Low permeability may mean infiltration features cannot meet all drainage requirements. Conveyance

79 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

features should be designed above ground and following natural flow paths where possible. • Choice of SuDS components should be based on detailed site information, examples may include attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

80 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BRA12 Site name Former Bus Depot, Market Street, Bracknell

Area 0.48ha

Greenfield or previously developed Previously Developed Land land

Proposed site use Housing and employment

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. drainage features

Flood history No record of historical flooding. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: This site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 4.9% 14.0% 37.7% Description of surface water flow paths: Surface water risk is low during the 1 in 30-event, with a small area of ponding in the Surface Water south west corner and on Market Street. In the 1 in 100-year event, this has developed into a more continuous flow route from the south. In the 1 in 1,000-year event, flow is more extensive across the site, and on Market Street. The flow route originates to the south of the site, flows around The Peel Centre and continues northwards along the western boundary, between the site and neighbouring cinema. Flow continues to the western roundabout before heading west through Priestwood Avenue, where flooding was recorded in 2007. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk

81 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The site is within postcode area RG12 1, which has no properties on the Thames Sewer Water Sewer Flooding Register. Impact of climate change

Climate River Basin District Central Higher Upper End change Central allowances for river flow for Thames 25% 35% 70% the ‘2080s’

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitivity range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative Impact of Development

Water Framework Directive BRA12 is within the Cut at west Bracknell catchment (WFD) catchment name 9 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

82 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access would be be via Market Street and/or Skimped Hill Lane Market Street experiences minor surface water ponding in the 1 in 30-year and 1 in 100-year. Access and Skimped Hill Lane is flooded significantly even in these lower return periods. Surface egress water flooding becomes more widely significant and likely to disrupt transport across Bracknell town centre in the 1 in 1,000-year event.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Soil type Naturally wet very acid sandy and loamy soils

Typical slope 0.003

Groundwater Source No Protection Zone?

Historic Landfill Site? No

83 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because though the site is under 1ha in area in Flood Zone 1 it is at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. Requirements • The impact of the development on flood risk from all sources both on and off-site must for site- be considered and modelled where appropriate. specific • The cumulative impact on flood risk of this development and other proposed Flood Risk developments in the Cut at west Bracknell catchment must be considered by the FRA Assessment and in planning decisions. • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes, preserving these areas as Guidance for green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). Requirements • Detailed site investigations will be required including infiltration testing. for SuDS and • Existing surface water flow routes from off-site must be accommodated within the surface water masterplan. management • SuDS are possible on all sites, even small previously developed sites such as this one. • All development should adopt source control SuDS techniques. Low permeability may mean infiltration features cannot meet all drainage requirements. Conveyance

84 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

features should be designed above ground and following natural flow paths where possible. • Choice of SuDS components should be based on detailed site information, examples may include attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

85 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BRA14 Site name Jubilee Gardens & British Legion, The Ring, Bracknell

Area 0.57ha

Greenfield or previously developed Greenfield land

Proposed site use Housing and employment

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. drainage features

Flood history No record of historical flooding. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: This site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 8.0% 12.2% 27.4% Surface Water Description of surface water flow paths: There is ponding in the north west and south east parts of the site in the 1 in 30-year event. This increases slightly in extent during the 1 in 100-year and converges during the 1 in 1,000-year event to form a minor flow route towards Princess Square shopping centre. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 63.9% 63.9% Description of groundwater risk: A large area of the east of the site is predicted to experience groundwater levels of between 0.025 and 0.5m below the ground surface in the 1 in 100-year event. This area coincides with surface water flow paths shown in the RoFfSW map, and the two sources of flooding may interact.

86 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. This site covers two postcode areas. Most of the site is in RG12 9, which has one property on the Thames Water Sewer Flooding Register. This is a very small Sewer proportion of the total properties in this postcode area. The north west corner of the site is within RG12 1, which has no properties on the register.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive BRA14 is within the Cut at west Bracknell catchment (WFD) catchment name 9 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

87 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access would be from The Ring, and the adjacent road serving the delivery yard and Access and church. Both experience minor surface water ponding in the 1 in 30-year and 1 in egress 100-year events. Surface water flooding becomes more significant and likely to disrupt transport across Bracknell town centre in the 1 in 1,000-year event.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and Soil type clayey soils

Typical slope 0.041

Groundwater Source No Protection Zone?

Historic Landfill Site? No

88 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because though the site is under 1ha in area in Flood Zone 1 it is at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, groundwater flooding, and the interaction between them, should be considered as part of a site- specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must Requirements be considered and modelled where appropriate. for site- • The cumulative impact on flood risk of this development and other proposed specific developments in the Cut at west Bracknell catchment must be considered by the FRA Flood Risk and in planning decisions. Assessment • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater is likely to emerge, preserving these areas as green infrastructure. Guidance for • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate site design change rainfall event. Raising of access routes must not impact on flow routes. and making Consideration should be given to the siting of access points with respect to surface development water flood risk areas. safe from flooding • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area.

• A site-specific surface water drainage strategy will be required. Requirements for SuDS and • Early liaison with Thames Water is recommended to obtain agreement in principle for surface water connection to the surface water sewer (if required). management • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March).

89 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites, even small previously developed sites such as this one. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • The design of SUDS schemes must take into account the seasonally high groundwater table and low permeability. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code BRA15 Site name Southern Gateway, The Ring, Bracknell

Area 0.94ha

Greenfield or previously developed Greenfield land

Proposed site use Housing and employment

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. drainage features

Flood history No record of historical flooding. Proportion of site at risk in Flood Zones FZ3 plus 70% Fluvial FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0%

90 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Available detailed modelling data: N/A Detailed nature of flood characteristics: This site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 0.0% 0.0% 0.3% Surface Water Description of surface water flow paths: The site is at low risk of surface water flooding. The surrounding roads are affected by surface water, and this encroaches slightly on the site boundary in the 1 in 1,000-year event. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 100.0% 100.0% Description of groundwater risk: The whole site is predicted to experience groundwater levels of between 0.025 and 0.5m below the ground surface in the 1 in 100-year event. There are no known reservoirs or impounded water bodies likely to pose a risk to this Reservoir / site. impounded water body failure

Canal There are no canals in Bracknell Forest. The site is within postcode area RG12 9, which has one property on the Thames Sewer Water Sewer Flooding Register. This is a very small proportion of the total properties in this postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification

Impact of The effect of climate change on groundwater flooding, and those watercourses where climate change groundwater has a large influence on winter flood flows is more uncertain. Milder on flood risk wetter winters may increase the frequency of groundwater flooding incidents in areas from other that are already susceptible, but warmer drier summers may counteract this effect by sources drawing down groundwater levels to a greater extent during the summer months.

91 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Cumulative Impact of Development

Water Framework Directive BRA15 is within the Cut at west Bracknell catchment (WFD) catchment name 9 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access would be from The Ring or Station Way, which experience minor surface Access and water ponding in the 1 in 30-year and 1 in 100-year events. Surface water flooding egress becomes more significant and likely to disrupt transport across Bracknell town centre in the 1 in 1,000-year event.

92 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Sands and silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.038

Groundwater Source Protection No Zone?

Historic Landfill No Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is under 1ha in area in Flood Zone 1 but at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of groundwater flooding, and the risk of surface water flooding to access routes, should be considered as part of a site-specific flood risk assessment. Requirements • The impact of the development on flood risk from all sources both on and off-site must for site- be considered and modelled where appropriate. specific • The cumulative impact on flood risk of this development and other proposed Flood Risk developments in the Cut at west Bracknell catchment must be considered by the FRA Assessment and in planning decisions. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future.

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• Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from areas where groundwater is likely to be highest, Guidance for preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites, even small previously developed sites such as this one. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • The design of SUDS schemes must take into account the seasonally high Requirements groundwater table and low permeability. Infiltration techniques may be ineffective, for SuDS and and may pose a pollution risk. SuDS may need to be shallow and take up larger surface water areas. Above ground conveyance and attenuation can be used but care must be management taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

94 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code BRA16 Site name Pinecroft, Old Wokingham Road

Area 0.73ha

Greenfield or previously developed Greenfield land

Proposed site use Housing and open space

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing There are no known watercourses on the site, but there is a roadside ditch along Old drainage Wokingham Road. features No flood incidents have been recorded on site. Note that rural greenfield sites may have experienced flooding that has not been recorded due to the lack of properties that Flood history would be affected. Frequent flooding occurs along Old Wokingham Road to the east of the site. Flooding here was recorded by the Local Authority in the July 2007 event, when the source of flooding was noted as overtopping of drains. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: The site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 0.0% 0.0% 1.5% Surface Water Description of surface water flow paths: The RoFfSW map shows the site is at low risk from surface water flooding. Land north of the site is affected in all return periods by a significant surface water flow route flowing east to west, which encroaches onto the northern boundary of the site. Some surrounding roads are also impacted including Old Wokingham Road (access route). Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 100.0% 0.0% 100.0% Description of groundwater risk: The whole site is predicted to experience groundwater levels within 0.025m of the ground surface in the 1 in 100-year event.

95 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in the Borough. This site falls within the postcode RG403 which has 3 properties on the Thames Water Sewer Flooding Register. This is a very small proportion of the total properties in this Sewer postcode area. There is a Thames Water Sewage Treatment Works located 200m to the east of the site.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitive range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive BRA16 is within the Emm Brook catchment (WFD) catchment name 6 Proposed development 5% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Loddon (Swallowfield to River Thames confluence) is mostly catchment rural with extensive floodplains, and low risk to properties

96 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Proposed access to the site is from Old Wokingham Road. North of the site, this road Access and is affected by surface water flooding in all return periods. A flood event has also been egress recorded along this road, when the source of flooding was noted as overtopping of drains.

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Sustainable drainage and flood risk betterment

Bedrock Clay, silt and clay Geology

Superficial N/A Geology

Soil type Freely draining slightly acid loamy soils

Typical slope 0.017

Groundwater Source No Protection Zone?

Historic No Landfill Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage, given the lack of drainage outfalls in the area. • A site-specific flood risk assessment will be required because is under 1ha in area in Flood Zone 1 but could be affected by sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, groundwater flooding, and the interaction between them should be considered as part of a site- Requirements specific flood risk assessment. for site- • The impact of the development on flood risk from all sources both on and off-site must specific be considered and modelled where appropriate. Flood Risk • The cumulative impact on flood risk of this development and other proposed Assessment developments in the Emm Brook catchment must be considered by the FRA and in planning decisions. • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current

98 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

allowances were published in February 2016 but may be subject to change in the future. • The impact of the development on any existing sewer flooding issues should be discussed with Thames Water at an early stage (including proximity to the existing sewage treatment works). • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater is likely to emerge, preserving these areas as green infrastructure. Guidance for • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate site design change rainfall event. Raising of access routes must not impact on flow routes. and making Consideration should be given to the siting of access points with respect to surface development water flood risk areas. safe from • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year flooding event are managed via exceedance routes that minimise the risks to people and property. • Resilience measures will be required if buildings are situated in the flood risk area. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area, including to provide a safe access route. • A site-specific surface water drainage strategy will be required. • Establishing a suitable outfall from the development should be undertaken at an early stage. Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer if required. • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. Requirements • All development should adopt source control SuDS techniques. Conveyance for SuDS and features should be designed above ground and following natural flow paths where surface water possible. management • The design of SUDS schemes must take into account the seasonally high groundwater table. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Example features may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep).

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• Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code CLUSTER1 Site name Land west of Murrell Hill Lane, and south of Foxley Lane (comprising Foxley Fields, Whitehouse Farm, Murrell Hill Grange, Popes Manor and Popes Farm) (made up of sites Bin7, Bin8, Bin9, Bin10 and Bin11) Area 70.33ha

Greenfield or previously developed Greenfield land Housing, open space, SANG, primary school, neighbourhood centre, Proposed site use community centre and doctor’s surgery Flood risk More vulnerable vulnerability

Sources of flood risk

There is an unnamed watercourse flowing into the site from the south, which curves Existing towards the north west. This drains into the Emm Brook catchment which crosses into drainage Wokingham District. The watercourse appears to have been modified for ornamental features use and there are several large ponds in the south east of the site. BFC Highways note that flooding has occurred previously on the highway from Popes Flood history Meadow. Proportion of whole Cluster at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Available detailed modelling data: Fluvial N/A Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed ordinary watercourse flowing through the site. This watercourse is unmodelled and therefore is not covered by a Flood Zone. The RoFfSW gives an indication of possible flood risk from the watercourse.

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Proportion of whole Cluster at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 2.7% 5.4% 15.6% Description of surface water flow paths: The 1 in 30-year RoFfSW extent shows a surface water flow route originating on recently developed land just south of Bin9 and flowing north into Bin8, where it follows the unnamed watercourse through the site. In the 1 in 100-year event, this flow route Surface Water increases in size, and additional flow routes start to develop, entering the site from the north and east. At the 1 in 1,000-year event all flow routes become more extensive, and flooding spreads across a wider area to the south of the ordinary watercourse. The contributing surface water catchment is evident, comprising the residential area to the north of Foxley Lane, Popes Meadow and farmland to the south bordered by London Road (B3408).

Proportion of whole Cluster in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 11.4% 11.4% Description of groundwater risk: In parts of the south of the site, groundwater levels are predicted to be between 0.025 and 0.5m below the ground surface in the 1 in 100-year event, with a small area where levels are predicted to be between 0.5 and 5m below ground. These areas coincide with surface water flow routes developing from the south and therefore the two sources of flooding may interact. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. This site covers two postcode areas. Most of the site is within RG42 4, which has one property on the Thames Water Sewer Flooding Register. The far east of the site Sewer is within RG12 8, which has two properties on the register. This is a very small proportion of the total properties in the postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification

101 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive CLUSTER1 is within the Cut at west Bracknell catchment (WFD) catchment name 9 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping? There are several small structures on the ordinary watercourse within the site, located at track crossings, footbridges etc. These have the potential to block, Risk of culvert / but water would flow easily over and around them so this is unlikely to impact structure blockage? greatly on the extent of flooding. There may be a longer culvert or structures/controls associated with the ornamental ponds, and these should be investigated further.

102 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

The site is likely to be accessed via Foxley Lane to the north of site and Murrelhill Access and Lane to the east of the site. Both may experience surface water ponding in a 1 in 30- egress year event upwards, and by the 1 in 1,000-year event there would be significant flooding on both routes.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.025

Groundwater Source Protection No Zone?

Historic Landfill No Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed Requirements (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). for site- • All sources of flooding, particularly the risk of surface water flooding, groundwater specific flooding, and the interaction between them, should be considered as part of a site- Flood Risk specific flood risk assessment. Assessment • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed developments in the Cut at west Bracknell catchment must be considered by the FRA and in planning decisions.

103 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• A detailed hydraulic model should be developed of the unnamed watercourse and surface water flow paths to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. Note that the recent development to the south may have changed the runoff charactieristics since the RofFSW map was created, this will need to be taken into account. • Careful design and assessment of any new crossings will need to be undertaken. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of structure or culvert blockage and the operation of the pond should be considered as part of the assessment. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater is likely to be highest, preserving these areas as green infrastructure. Guidance for • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate site design change rainfall event. Raising of access routes must not impact on flow routes. and making Consideration should be given to the siting of access points with respect to surface development water flood risk areas. safe from • The design must ensure that surface water flows resulting from rainfall in excess of a flooding 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site (for example existing residential areas Requirements around the site) must be accommodated within the masterplan. for SuDS and • SuDS are possible on all sites and a large greenfield site such as this should be able surface water to implement an exemplar scheme to deliver multiple benefits including water quality, management biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • The design of SUDS schemes must take into account the seasonally high groundwater table and low permeability. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be

104 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015). • With Cluster developments it is important that the drainage strategy and its phasing are considered as a whole and opportunities to link features maintaining surface water flow routes through the area are provided. With complex sites such as this early engagement with the LLFA is recommended.

Site details

Site code CLUSTER3 Site name Land at the Hideout and Beaufont Park, Nine Mile Ride (made up of sites BRA3 and BRA4) Area 56.76ha

Greenfield or previously developed Greenfield. land

Proposed site use Housing, open space, SANG and care home

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing There are several small unnamed drains on site shown on Ordnance Survey mapping. drainage features BFC Highways records show three properties were flooded at Easthampstead Caravan Park in 2000, which borders the site to the west. The flood mechanism was not recorded. Flooding occurs frequently on the recreation ground to the east and along Flood history Nine Mile Ride between the TRL site and Old Wokingham roundabout, and on the south side of Pinewood roundabout. It is unlikely due to the heavily wooded nature of most of the site that flooding would have been recorded.

105 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Proportion of whole Cluster at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed land drains within the site. These watercourses are unmodelled and are not covered by a Flood Zone. Proportion of whole Cluster at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 0.8% 2.0% 13.0% Description of surface water flow paths: At the 1 in 30-year and 1 in 100-year events, surface water may pond in small topographically isolated areas across the site. At the 1 in 1,000-year event, these areas Surface Water are likely to join up into coherent flow paths, which flow from adjacent land in the Woodenhill area of Bracknell to the east, across the centre of the site. The flow paths widen around The Lodge, converging at Seven Acre Farm on the western side of the site, and eventually flow into the Emm Brook catchment in Wokingham District.

Proportion of whole Cluster in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 38.4% 57.9% 96.3% Description of groundwater risk: There is a likelihood of groundwater reaching to less than 0.5m below the surface or higher across almost the entire site during a 1 in 100-year groundwater event. The western part of the site is at risk of groundwater emergence at the surface in the 1 in 100-year event. This high risk area coincides with surface water flow paths, and the two sources of flooding may interact. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The site falls within postcode area RG40 3, which has three properties on the Sewer Thames Water Sewer Flooding Register. This is a very small proportion of the total properties in the postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

106 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive CLUSTER3 is within the Emm Brook catchment (WFD) catchment name 6 Proposed development 5% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Loddon (Swallowfield to River Thames confluence) is mostly catchment rural with extensive floodplains, and low risk to properties

107 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access likely to be from Old Wokingham Road, South Road, Nine Mile Ride (B3430) and/or West Road. A small area of the Old Wokingham Road is at risk of surface water flooding in the 1 in 30-year event, but there is dry access to the south Access and up to the 1 in 100-year event. Both South Road and Nine Mile Ride experience egress localised flooding at the 1 in 100-year event, which also affects the current minor access road into the site. All of these roads experience more extensive flooding in the 1 in 1,000-year event, however West Road would provide dry access in a 1 in 1,000-year event.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, sand and silt

Superficial Geology N/A

Soil type Naturally wet very acid sandy and loamy soils

Typical slope 0.015

Groundwater Source Protection No Zone?

Historic Landfill No Site?

108 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, groundwater flooding, and the interaction between them, should be considered as part of a site- specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. Requirements • The cumulative impact on flood risk of this development and other proposed for site- developments in the Emm Brook catchment must be considered by the FRA and in specific planning decisions. Flood Risk • A detailed hydraulic model should be developed of the land drains and surface water Assessment flow paths to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. This must take into account drainage from existing highways and off-site catchments. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater is likely to emerge, preserving these areas as green infrastructure. Guidance for • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate site design change rainfall event. Raising of access routes must not impact on flow routes. and making Consideration should be given to the siting of access points with respect to surface development water flood risk areas. safe from • The design must ensure that surface water flows resulting from rainfall in excess of a flooding 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. Requirements for SuDS and • Early liaison with Thames Water is recommended to obtain agreement in principle for surface water connection to the surface water sewer (if required). management • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March).

109 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Existing surface water flow routes from off-site must be accommodated within the masterplan and existing drainage improved where necessary . • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • The design of SUDS schemes must take into account the seasonally high groundwater table and low permeability. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. Given the current undeveloped, wooded nature of the site, SuDS scheme must be designed to intercept the first 10mm of rainfall. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015). • With Cluster developments it is important that the drainage strategy and its phasing are considered as a whole and opportunities to link features maintaining ‘blue routes’ through the area are provided. With complex sites such as this early engagement with the LLFA is recommended.

110 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Site details

Site code CLUSTER7 Site name Land south of Bracknell Road, north of Forest Road, and west of Cricketers Lane, Hayley Green Made up of War13, War14, War15, War16, War22 Area 15.72ha

Greenfield or previously developed Greenfield land

Proposed site use Housing, open space and off-site SANG

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing A small unnamed drain is apparent on Ordnance Survey mapping. It runs from south drainage to north across the site and along the eastern boundary, before disappearing under features Bracknell Road (B3022). No record of historical flooding on the site. Nearby, BFC Highways flood records show: •The Brock Hill area just upstream on The Cut experienced flooding in July 2007 and in 2008. No source or mechanism is identified. Flood history • The Bracknell Road/Cricketers Lane junction flooded in August 2002, November 2006 and July 2007. No source or mechanism is identified. BFC Highways note that flooding has previously occurred on the carriageway at Hayley Green.

Proportion of whole Cluster at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.1% 0.1% 99.8% 0.1% Available detailed modelling data: Environment Agency (2013) ISIS-TUFLOW model of The Cut, built as part of The Cut Flood Risk Mapping Study. The Environment Agency has indicated that at the time of publication they have commenced re-modelling of The Cut. The most recently available Fluvial model data will be used to inform any site-specific FRAs. Detailed nature of flood characteristics: The north-east corner of the site, close to the B3022, encroaches onto the floodplain of The Cut, and is at risk of inundation in the 1 in 100-year event and upwards. The edge of the floodplain is well-defined and the extent and depth of flooding increase only slightly with a +70% climate change scenario and at the 1 in 1,000-year event. Depths are very shallow (0.05m in a 1 in 100-year plus 70% climate change event) and hazard is classed as low (Defra Flood Risks to People Guidance FD2321/TR2). Proportion of whole Cluster at risk in Risk of Flooding from Surface Water Map Surface Water 1 in 30-year 1 in 100-year 1 in 1,000-year 4.9% 8.3% 21.1%

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Description of surface water flow paths: Two surface water flow routes drain from the south into the site, and both have sizeable off-site catchments. One drains residential areas of Bracknell off Westmorland Drive and follows the unnamed drain into the site. The other forms in the area of open space just to the east, and the two flow paths converge on the site. There is a risk of flooding close to the drain in the north-east of the site at the 1 in 30-year return period, with another small area of ponding to the west. At the 1 in 100-year and 1,000-year return periods, the flow routes become more interconnected and cover an increasingly large area. Proportion of whole Cluster in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 2.6% 18.2% 20.8% Description of groundwater risk: Part of the south-eastern corner and south-centre of the site are predicted to experience groundwater levels of between 0.025 and 0.5m below the ground surface in the 1 in 100-year event, with a small band at risk of groundwater emergence. This high risk area coincides with the surface water flow paths, and the two sources of flooding may interact. Reservoir / The Environment Agency's Risk of Flooding from Reservoirs map predicts that flooding impounded may occur along The Cut if Fish Pond at Ascot Place were to fail or overtop. The extent water body of flooding is not predicted to reach the site. failure

Canal There are no canals in Bracknell Forest. This site covers two postcode areas. The majority of the site is within RG42 6, which has four properties on the Thames Water Sewer Flooding Register. This is a very small proportion of the total properties in the postcode area. Part of the south east Sewer corner of the site is within RG42 7, which has no properties on the register. The LLFA are aware of issues associated with surcharging foul sewers in the vicinity of the site.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70% Climate change under both the +35% and +70% scenarios is likely to increase the area Impact of of Flood Zone 3a slightly to be similar to the current Flood Zone 2. The extent of Flood climate change Zone 2 is also likely to increase slightly, but modelling the impacts of climate change on fluvial on Flood Zone 2 is not currently a requirement under the NPPF. flooding and Flooding is likely to become more frequent under both climate change scenarios, and the Flood Zone the impact of an event with a given probability is also likely to become more severe, classification with water depths, velocities and flood hazard increasing.

112 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive CLUSTER7 is within the Cut (Ascot to Bull Brook confluence at (WFD) catchment name Warfield) catchment 46 Proposed development 22% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact High within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

Flood risk management infrastructure and residual risk

There are no formal (raised) defences present on The Cut at this location, or other known flood alleviation schemes which may provide benefit. The Defence type Environment Agency Spatial Defences layer records the banks as 'high ground' with 'no maintenance'. Environment Agency Spatial Defences layer records the banks as having a Standard of protection ‘design standard of 5-years and an actual standard of 0-years. This suggests (SoP) that the banks provide no actual flood defence function. The Environment Agency Spatial Defences layer states the overall condition of Environment Agency’s the banks as 3; with the worst condition for any section within the site being 5. defence condition Based on principles of Condition Assessment Manual (Environment Agency, assessment 2012). 1 (Very Good), 2 (Good), 3 (Fair), 4 (Poor), 5 (Very Poor) Risk of defence No risk of defence breach / overtopping as there are no raised defences. breach / overtopping? There is low risk of a blockage affecting the site at the Malt Hill Bridge on The Cut, which is a relatively large structure 600m downstream of the site. The small drain which flows across the site from the south appears to pass under Risk of culvert / Bracknell Road (B3022) via a pipe or culvert, from which it does not emerge, structure blockage? presumably flowing straight into The Cut. There is a risk of this structure blocking and increasing surface water flood risk on the site. Further investigation is needed on the size, capacity and type of structure.

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Emergency planning

The area receives a Flood Alert under the Environment Agency's Flood Information Flood warning Service. The site falls within 'The Cut' Flood Alert Area. The site could be accessed from a number of surrounding roads. Bracknell Road (B3032) and Forest Road (B3034) are both at risk from fluvial flooding from Bull Brook. Bracknell Road (B3032)/Cricketers Lane junction is at risk from fluvial flooding Access and from The Cut. Any access from Cricketers Lane would require improvements to the egress Lane. Surface water flooding only affects a small part of Forest Road at the 1 in 30- year event, but by the 1 in 100-year it could cause problems at several points along Forest Road and Bracknell Road. By the 1 in 1,000-year event, flooding would be significant on all access routes.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.016

Groundwater Source No Protection Zone?

Historic Landfill Site? No

Requirements for planning and NPPF

The Sequential Test must to be passed. Only once the Sequential Test is passed should the Exception Test be applied. The Exception test will be required in the following scenarios: • If More Vulnerable and Essential Infrastructure is located in FZ3a. Sequential • If Highly Vulnerable development is located in FZ2. Test and • If Essential Infrastructure is located in Flood Zone 3b Exception Development will not be permitted in the following scenarios Test requirements • Highly Vulnerable infrastructure within FZ3a and FZ3b. More Vulnerable and Less Vulnerable Infrastructure within FZ3b.

It must be shown that the development will be safe for its lifetime and the risk can be managed through a sequential approach to design. • Consultation with the LLFA and the Environment Agency should be undertaken at an Requirements early stage. for site- specific • A site-specific flood risk assessment will be required because the site is within Flood Flood Risk Zone 2 and 3 and at risk from sources of flooding other than rivers and the sea. Assessment Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications).

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• All sources of flooding, particularly the risk of surface water flooding, groundwater flooding, and the interaction between them, should be considered as part of a site- specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed developments in the Cut (Ascot to Bull Brook confluence at Warfield) catchment must be considered by the FRA and in planning decisions. • The Environment Agency should be consulted to obtain the latest hydraulic modelling information of The Cut at the time of the flood risk assessment. They will advise as to whether existing detailed models need to be updated. • A detailed hydraulic model should be developed of the unnamed watercourse and surface water flow paths to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. Coincidence of an event on The Cut should be considered. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of blockage of the structure under Bracknell Road (B3022) should be investigated as part of the assessment. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Flood Zones 2 and 3, and Flood Zone 3a plus 70% climate change (subject to a detailed flood risk assessment using up to date model information) should be preserved as green infrastructure, with built development restricted to Flood Zone 1. Development should be steered away from surface water flow routes and areas where groundwater is likely Guidance for to emerge. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 35% and, and making in consultation with the LLFA, the 1 in 100-year +70% climate change fluvial event. development Access should also be safe in the 1 in 100-year plus 40% rainfall event. Consideration safe from should be given to the siting of access points with respect to surface water flood risk flooding areas. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area.

• A site-specific surface water drainage strategy will be required. Requirements for SuDS and • Early liaison with Thames Water is recommended to obtain agreement in principle for surface water connection to the surface water sewer (if required). management • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March).

115 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • The design of SUDS schemes must take into account the seasonally high groundwater table and low permeability. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events must be located out of flood risk areas. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015). • With Cluster developments it is important that the drainage strategy and its phasing are considered as a whole and opportunities to link features maintaining ‘blue routes’ through the area are provided. With complex sites such as this early engagement with the LLFA is recommended.

Site details

Site code SAND8 Site name Eagle House Field, Crowthorne Road, Sandhurst

Area 2.28ha

Greenfield or previously developed Greenfield land

Proposed site use Care home (C2 use) and open space.

Flood risk More vulnerable vulnerability

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Sources of flood risk

Existing The OS mapping shows a small unnamed watercourse running from east to west along drainage the northern boundary of the site. There is also a small pond on the eastern edge of features the site. No flood incidents have been recorded on site. Note that rural greenfield sites may have experienced flooding that has not been recorded due to the lack of properties that Flood history would be affected. There is frequest ponding of surface water observed on the site and LLFA records show that Sandhurst Road has experienced flooding, north of the site, in November 2015. No mechanism was identified for this event. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: The site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 0.8% 6.8% 24.6% Description of surface water flow paths: Surface Water The RoFfSW map shows the site is at risk of surface water flooding in all return periods. In the 1 in 30-year event risk is low and only a small area of flooding is concentrated in the east. A fully connected flow path forms from west to east in the 1 in 100-year event and is extensive in the 1 in 1,000-year event. There is also a risk of 1 in 30-year surface water flooding on Crowthorne Road adjacent to the western site boundary. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 58.0% 58.0% Description of groundwater risk: A large area of the east of the site is predicted to experience groundwater levels of between 0.025 and 0.5m below the ground surface in the 1 in 100-year event. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in the Borough. This site falls within GU47 8 which has 11 properties on the Thames Water Sewer Flooding Register. This is one of the highest incidences of sewer flooding within a Sewer postcode area in Bracknell Forest, but is still a small proportion of total properties in the postcode area.

Impact of climate change

River Basin District Central Higher Upper End Central

117 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Climate change allowances for Thames 25% 35% 70% river flow for the ‘2080s’

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitive range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive SAND8 is within the Blackwater (Hawley to Whitewater confluence at (WFD) catchment name Bramshill) catchment 6 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Blackwater (Bramshill to River Loddon confluence at catchment Swallowfield) is a rural catchment, with low risk to properties. Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

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Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Proposed access to the site is form Crowthorne Road. Surface water flooding is Access and predicted to occur along this road in all return periods. Flooding has also been egress recorded north of Crowthorne Road along the adjoining Sandhurst Road which may present a problem for access.

Sustainable drainage and flood risk betterment

Bedrock Sand, silt and clay Geology

Superficial N/A Geology

Soil type Naturally wet very acid sandy and loamy soils

Typical slope 0.039

Groundwater Source No Protection Zone?

Historic No Landfill Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

Requirements • Consultation with the LLFA should be undertaken at an early stage. for site- • A site-specific flood risk assessment will be required because the site is over 1ha in specific area within Flood Zone 1 and could be affected by sources of flooding other than rivers Flood Risk and the sea. Government guidance on flood risk assessments must be followed Assessment (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications).

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• All sources of flooding, particularly the risk of surface water flooding, groundwater flooding, and the interaction between them, should be considered as part of a site- specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed developments in the Blackwater (Hawley to Whitewater confluence at Bramshill) catchment must be considered by the FRA and in planning decisions. • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of the development on any existing sewer flooding issues should be discussed with Thames Water at an early stage • Given the low-lying nature of the site, and difficulty in achieving a drainage outfall, early consideration of these issues are required. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater is likely to emerge, preserving these areas as green infrastructure. Guidance for • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate site design change rainfall event. Raising of access routes must not impact on flow routes. and making Consideration should be given to the siting of access points with respect to surface development water flood risk areas. safe from • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year flooding event are managed via exceedance routes that minimise the risks to people and property. • Resilience measures will be required if buildings are situated in the flood risk area. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area, including to provide a safe access route. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer if required. • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the Requirements masterplan. for SuDS and • SuDS are possible on all sites, and a large greenfield site such as this should be surface water able to implement an exemplar scheme to deliver multiple benefits including water management quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • Low permeability may mean infiltration features cannot meet all drainage requirements.

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• The design of SUDS schemes must take into account the seasonally high groundwater table. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Example features may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

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Site details

Site code SAND9 Site name Land at Lower Church Road, Sandhurst

Area 0.99 ha

Greenfield or previously developed Greenfield. Currently used for equestrian. land

Proposed site use Residential (C3 use) 25 dwellings

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. drainage features The southern site boundary meets the historical recorded flood outline for the March 1947 flood event. The source of the flood was the Blackwater River. The flood mechanism is recorded as being the exceedance of channel capacity, with no raised defences. The BFC Highways flood record shows a flood incidence at the north site boundary on the highway in Lower Church Road, in March 2007. The source of flooding was Flood history reported as pluvial/surface water with possible blocked highway gullies. Flooding also occurred in November 2014 on High Street (A321). The source of flooding was surface water/highway gullies. Although this is not within the site boundary, the A321 road is likely to be a main access route to the site. No flood incidents have been recorded within the site boundary. Note that rural greenfield sites may have experienced flooding that has not been recorded due to the lack of properties that would be affected. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 1.2% 2.0% 96.8% 2.6% Available detailed modelling data: Environment Agency (2009) ISIS-TUFLOW model of the Blackwater River, built as part of the River Blackwater Model Update. Fluvial Detailed nature of flood characteristics: An area along the southern boundary is predicted to be at risk of fluvial flooding in the 100-year event and above. Predicted depths are low (less than 0.3m), and velocities are low. Hazard results are not available, but danger to people is likely to be low. A small area in the south east of the site is in Flood Zone 3b, 3a and 3a plus climate change, and a small area along the south boundary is also in Flood Zone 2. Flood Zone 2 is based on the March 1947 recorded outline at this location. Proportion of site at risk in Risk of Flooding from Surface Water Map Surface Water 1 in 30-year 1 in 100-year 1 in 1,000-year

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0.4% 0.5% 1.2%

Description of surface water flow paths: The RoFfSW map shows a small area in the south east corner along the boundary to be at risk of surface water flooding in all return periods. This area is associated with the Blackwater River and is within the fluvial Flood Zones. The remaining site area is predicted to be at low risk of flooding from surface water. Parts of Lower Church Road and the A321 Wokingham Road which are likely to provide access to the site are at risk of flooding from surface water in all return periods, although they are dry in the immediate vicinity of the site. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m 0.0% 23.8% 23.8% Groundwater Description of groundwater risk: Groundwater levels in the south east of the site are between 0.025m and 0.5m below the ground surface in the 1 in 100-year event. Within this zone there is a risk of groundwater flooding to surface and subsurface assets. There is the possibility of groundwater emerging at the surface locally. For the remainder of the site there is predicted to be negligible risk of flooding from groundwater. Reservoir / There are no known reservoirs or impounded water bodies likely to pose a risk to this impounded site. There are a number of small gravel pit lakes to the south of the site, which are at water body a lower elevation and will only cause flooding in extreme fluvial events. failure

Canal There are no canals in the Borough. This site falls within GU47 8 which has 11 properties on the Thames Water Sewer Flooding Register. This is one of the highest incidences of sewer flooding within a Sewer postcode area in Bracknell Forest, but is still a small proportion of total properties in the postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70% Climate change under both the +35% and +70% scenarios is likely to increase the area Impact of of Flood Zone 3a slightly.. Fluvial flooding is likely to become more frequent under both climate change climate change scenarios, and the impact of an event with a given probability is also on fluvial likely to become more severe, with extents, depths, velocities and flood hazard flooding and increasing. the Flood Zone However, most of the site is likely to remain within Flood Zone 1 accounting for the classification effects of climate change.

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Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitive range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive SAND9 is within the Blackwater (Hawley to Whitewater confluence at (WFD) catchment name Bramshill) catchment. 6 Proposed development 1% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment

Susceptibility of downstream Low. The Blackwater (Bramshill to River Loddon confluence at catchment Swallowfield) is a rural catchment, with low risk to properties. Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping. breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

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Emergency planning

The area receives a Flood Alert and a Flood Warning under the Environment Agency's Flood Information Service. The south east boundary of the site falls within Flood warning the River Blackwater at Camberley and Sandhurst ' Flood Warning Area, however most of the site is not within the Flood Warning Area.

Access to the site is likely to be from Lower Church Road, Lynch Gate Close or Belfry Mews. Surface water flooding is not predicted to occur on the roads at the site boundary. Flooding has been predicted from the 1 in 30-year return period upwards Access and in the northern part of Lower Church Road, where it joins Lower Sandhurst Road, egress which may cause restrictions. Flooding is predicted to occur at different points on the A321 road in all return periods, which may create traffic problems in the area.

Sustainable drainage and flood risk betterment

Bedrock Bracklesham Group and Barton Group (undifferentiated). Geology

Superficial None recorded within the site boundary. Geology

Soil type Loamy soil with naturally high groundwater.

Typical slope 0.06

Groundwater Source The site is not within a designated groundwater Source Protection Zone. Protection Zone? There are no historic landfill sites within the site boundary, however Mill Lane is located Historic approximately 350m to the north west and Chandlers Farm is located approximately Landfill Site? 650m to the west of the site.

Requirements for planning and NPPF

The Sequential Test must be passed. Only once the Sequential Test is passed should the Exception Test be applied. It is expected that all development will be sequentially located within Flood Zone 1. For this site, the Exception Test would be required: • If More Vulnerable and Essential Infrastructure is located in FZ3a or FZ3a plus Sequential climate change. Test and • If Highly Vulnerable development is located in FZ2. Exception • If Essential Infrastructure is located in Flood Zone 3b Test Development will not be permitted in the following scenarios: requirements • Highly Vulnerable development within FZ3a or FZ3a plus climate change and FZ3b. • More Vulnerable and Less Vulnerable development within FZ3b.

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• Consultation with the LLFA should be undertaken at an early stage. • At the planning application stage, a site-specific flood risk assessment and surface water drainage strategy will be required. • Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is within Flood Zone 2 and 3 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed Requirements (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). for site- specific • Climate change should be assessed using recommended climate change allowances Flood Risk at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- Assessment climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • All sources of flooding should be considered as part of a site-specific flood risk assessment. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken in the southern part of the site, including groundwater monitoring during the winter months. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater is likely to emerge, preserving these areas as green infrastructure. • Safe access and egress should be demonstrated in the 1 in 100 plus climate change event and raising of access routes must not impact on floodplain storage capacity. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year Guidance for event are managed via exceedance routes that minimise the risks to people and site design property. and making development • Resilience measures will be required if buildings are situated in the flood risk area. safe from • Mitigation for seasonal high groundwater levels must be considered (for example by flooding raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within an area of surface water flood risk area, and a safe access route provided. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas.

• A site-specific surface water drainage strategy will be required. Requirements for SuDS and • Early liaison with Thames Water is recommended to obtain agreement in principle for surface water connection to the surface water sewer if required. management • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March).

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• Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites, and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • Low permeability may mean infiltration features cannot meet all drainage requirements. • The design of SUDS schemes must take into account the seasonally high groundwater table in the southern part of the site. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Example features may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code WAR3 Site name Jealotts Hill International Research Centre, and land at Jealotts Hill, Maidenhead Road

Area 241.96ha

Greenfield or previously developed Greenfield land

Proposed site use Housing, open space, SANG, schools and community facilities

Flood risk More vulnerable vulnerability

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Sources of flood risk

There is a small unnamed watercourse identified on OS mapping which flows south Existing along the eastern boundary of the site, joining The Cut to the south of the site. A pond drainage is situated in the north west corner of the site. There are road side drainage ditches features along the roads. No flood incidents have been recorded on the site itself. Note that rural greenfield sites may have experienced flooding that has not been recorded due to the lack of properties that would be affected. Flood history LLFA records show that highway flooding has occurred on Maidenhead Road, Bowyer's Lane, Tickleback Row and the A3095 to the south of the site, with the mechanism noted as highway drainage problems. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Available detailed modelling data: Fluvial Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed ordinary watercourse running along the eastern boundary of the site. This watercourse is unmodelled and does not have a Flood Zone associated with it. The RoFfSW gives an indication of flood risk from the watercourse. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 1.6% 3.1% 11.5% Description of surface water flow paths: There are several flow paths which affect the development site. There are two Surface Water flowpaths originating in the centre of the site and flowing west towards the cut, with minor flow paths feeding into them. Both of these are a high risk, occuring in the 1 in 30-year event and becoming more substantial as return period increases. Along the eastern boundary there are multiple smaller flow paths flowing east into the unnamed watercourse, which develop at the 100 to 1000 year return period. There are also areas of ponding across the site which are associated with the natural topography. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 1.0% 0.0% Description of groundwater risk: A large proportion of the site is determined to have no groundwater flood risk in a 1 in 100-year flood event. In the south, there is an area whereby groundwater is estimated to be beween 0.5 and 0.5m. In the north of the site, the groundwater flood risk increases to between 0.025m and 0.5m below the surface, during a 1 in 100-year flood event. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in the Borough. This site falls within RG42 6 which has 4 properties on the Thames Water Sewer Flooding Register. This is a small proportion of the total properties in the postcode Sewer area. Aerial imagery shows a private wastewater treatment works in the centre of the site.

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Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitive range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative Impact of Development

WAR3 is partly within two catchments: Water Framework Directive The western side is within The Cut (Binfield to River Thames (WFD) catchment name confluence) and Maidenhead Ditch 15 Proposed development 3% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Low within WFD catchment Medium. The Thames (Cookham to Egham) catchment has a high risk Susceptibility of downstream to properties but a very large catchment area upstream of The Cut catchment which will reduce the relative impact of tributaries.

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WAR3 is partly within two catchments: Water Framework Directive The eastern side is within The Cut (Ascot to Bull Brook confluence at (WFD) catchment name Warfield) 46 Proposed development 22% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact High within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties

Flood risk management infrastructure and residual risk

Defence type No flood defences present

Standard of protection No flood defences present (SoP)

Environment Agency’s No flood defences present defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

The main access routes are proposed to be from Maidenhead Road (A3095), Ascot Road (A330) and Wellers Lane, with additional routes from Gough's Barn Road, Bowyers Lane and Tickleback Road. LLFA records show that flooding has occurred Access and on Maidenhead Road, Bowyer's Lane, Tickleback Row and the A3095 to the south egress of the site. Surface water mapping shows that all of these roads are at risk of flooding to various degrees from flow paths crossing them and from surface water ponding on the road surface in all return periods.

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Sustainable drainage and flood risk betterment

Bedrock Clay, silt, sand and gravel Geology

Superficial Sand and gravel in the south east of the site Geology

Soil type Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey soils

Typical slope 0.010

Groundwater Source SPZ3 Protection Zone?

Historic No Landfill Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because/ is over 1ha in area within Flood Zone 1 and could be affected by sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding and groundwater flooding and the interaction between them should be considered as part of a site- specific flood risk assessment. Requirements • The impact of the development on flood risk from all sources both on and off-site must for site- be considered and modelled where appropriate. specific • The cumulative impact on flood risk of this development and other proposed Flood Risk developments in the Cut (Ascot to Bull Brook confluence at Warfield) catchment must Assessment be considered by the FRA and in planning decisions. • A detailed hydraulic model should be developed of the unnamed watercourse and surface water flow paths to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current

131 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

allowances were published in February 2016 but may be subject to change in the future. • The impact of the development on any existing sewer flooding issues should be discussed with Thames Water at an early stage. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate change rainfall event. Raising of access routes must not impact on flow routes. Guidance for Consideration should be given to the siting of access points with respect to surface site design water flood risk areas. and making • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year development event are managed via exceedance routes that minimise the risks to people and safe from property. flooding • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Compensation storage would need to be provided for any land-raising within the 1 in 100 plus 35% climate change allowance, including to provide a safe access route. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area, including to provide a safe access route.

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• A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer if required. • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • Low permeability may mean infiltration features cannot meet all drainage requirements. • The design of SUDS schemes must take into account the seasonally high groundwater table. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas. Above Requirements ground conveyance and attenuation can be used but care must be taken that for SuDS and groundwater does not enter the SuDS feature and reduce the storage capacity and surface water structural integrity of the design. management • Example features may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • Improvements to off-site drainage infrastructure to support the scale of development may be required. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • This is a very large site and there may be scope to reduce the flow off-site and achieve a flood risk betterment with an appropriately designed scheme. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

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Site details

Site code WAR8 Site name Land between Newell Hall and Cuckoo Cottage, Warfield Street

Area 0.53ha

Greenfield or previously developed Greenfield land

Proposed site use Housing

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing A small unnamed land drain is apparent on OS mapping running from south to north drainage along the eastern boundary of the site. features BFC Highways note that flooding has been experienced on the highway at the site Flood history when ditches were at full capacity. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Available detailed modelling data: Fluvial N/A Detailed nature of flood characteristics: The site may be at risk of flooding from the unnamed land drain flowing along the border of the site. This watercourse is unmodelled and is not covered by a Flood Zone. The RoFfSW gives an indication of possible flood risk from the watercourse. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 2.8% 5.1% 14.1% Surface Water Description of surface water flow paths: Flooding occurs for all three return periods along the eastern border of the site, extending further into the site at the 1 in 1,000-year event. This flooding follows the flow path of the unnamed land drain. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface Groundwater 0.025 to 0.5m 0.0% 0.0% 0.0% Description of groundwater risk: No groundwater flood risk

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Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The site falls within postcode area RG42 6, which has four properties on the Thames Sewer Water Sewer Flooding Register. This is a very small proportion of the total properties in the postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification

Impact of Climate change is predicted to increase rainfall intensity in the future by a range of climate change between 20% and 40% (the recommended national precautionary sensitivity range for on flood risk 2085 to 2115). This will increase the likelihood, frequency and extent of surface water from other flooding. sources

Cumulative Impact of Development

Water Framework Directive WAR8 is within the Cut (Warfield to north Bracknell) catchment (WFD) catchment name 8 Proposed development 11% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Medium within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties

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Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping. breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access to the site would be via Warfield Street (B3034) or Osborne Lane with suitable enhancements. Warfield Street is affected by a surface water flow route which crosses the road from south to north from the 1 in 30-year event upwards. However, dry access would be possible from the west during the 1 in 30-year and 1 in 100-year Access and events. At the north end of the site, Osborne Lane is at risk of fluvial flooding in a 1 egress in 5-year event and above, and at risk of surface water flooding in the 1 in 30-year and above. However, the road is dry to the south and at the junction with Warfield Street. At the 1 in 1,000-year event the surrounding roads are affected more extensively by flooding.

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Sands and silt

Superficial Geology Clay and Gravel of uncertain age and orgin

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.016

Groundwater Source Protection No Zone?

Historic Landfill No Site?

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Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because though the site is under 1ha in area in Flood Zone 1 it is at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must Requirements be considered and modelled where appropriate. for site- specific • The cumulative impact on flood risk of this development and other proposed Flood Risk developments in the Cut (Warfield to north Bracknell) catchment must be considered Assessment by the FRA and in planning decisions. • A detailed hydraulic model should be developed of the unnamed watercourse and surface water flow paths to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater Guidance for is likely to emerge, preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing. Requirements for SuDS and • Existing surface water flow routes from off-site must be accommodated within the surface water masterplan. management • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Low permeability may mean infiltration features cannot meet all drainage requirements. Conveyance

137 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

features should be designed above ground and following natural flow paths where possible. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code WAR25 Site name Steeple View, Gibbins Lane

Area 2.11ha

Greenfield or previously developed Greenfield land

Proposed site use Housing and open space.

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. There are small roadside ditches either side of Gibbins drainage Lane. features

Flood history No incidents have been recorded on the site or surrounding roads. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change Fluvial 0.0% 0.0% 0.0% 100.0% 0.0% Available detailed modelling data: N/A.

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Detailed nature of flood characteristics: The site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 1.1% 2.2% 11.5% Surface Water Description of surface water flow paths: In the 1 in 30-year and 1 in 100-year events, the RoFfSW map shows small areas of surface water ponding on the site. In the 1 in 1,000-year these connect to form flow paths that efxit the site to the north to join The Cut. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 0.0% 0.0% Description of groundwater risk: The site is at medium risk of groundwater flooding. None of the site is in the high risk categories, however, the eastern side of the side is predicted to have groundwater levels between 0.5 and 5m below the surface during a 1 in 100-year event. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in the Borough. This site falls within RG42 6 which has 4 properties on the Thames Water Sewer Sewer Flooding Register.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change The site is likely to remain within Flood Zone 1 accounting for the effects of climate on fluvial change. flooding and the Flood Zone classification

Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitive range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

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Cumulative Impact of Development

WAR25 is partly within two WFD catchments: Water Framework Directive The western side is within The Cut (Warfield to north Bracknell) (WFD) catchment name and Bull Brook catchments. 8 Proposed development 11% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Medium within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

Water Framework Directive WAR25 is partly within two WFD catchments: (WFD) catchment name The eastern side is within the Bull Brook catchment. 16 Proposed development 13 Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Medium within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

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Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access to the site is via Gibbins Lane. Access from this road may be difficult due to Access and the risk from surface water (from all return periods). Additionally, the B3034 (the egress adjoining road to Gibbins Lane) is also at a risk from surface water flooding. There are no recorded highway flood events.

Sustainable drainage and flood risk betterment

Bedrock Clay, silt, sand and gravel Geology

Superficial N/A Geology

Soil type Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey soils

Typical slope 0.009

Groundwater Source No Protection Zone?

Historic No Landfill Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

Requirements • Consultation with the LLFA should be undertaken at an early stage, given the lack of for site- drainage outfalls in the area. specific • A site-specific flood risk assessment will be required because the site is over 1ha in Flood Risk Assessment area within Flood Zone 1 and could be affected by sources of flooding other than rivers

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and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, should be considered as part of a site-specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. • The cumulative impact on flood risk of this development and other proposed developments in the Bull Brook catchment must be considered by the FRA and in planning decisions. • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The impact of the development on any existing sewer flooding issues should be discussed with Thames Water at an early stage • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater Guidance for is likely to emerge, preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Resilience measures will be required if buildings are situated in the flood risk area. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area, including to provide a safe access route. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer if required. • Existing surface water flow routes from off-site must be accommodated within the masterplan. • Establishing a suitable outfall from the development should be undertaken at an early stage. • All development should adopt source control SuDS techniques. Conveyance Requirements features should be designed above ground and following natural flow paths where for SuDS and possible. surface water • Low permeability may mean infiltration features cannot meet all drainage management requirements. • SuDS are possible on all sites and a greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • Example features may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of

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the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

Site details

Site code WINK7 Site name Ronans, Forest Road, Winkfield Row

Area 1.35ha

Greenfield or previously developed Greenfield land

Proposed site use Housing

Flood risk More vulnerable vulnerability

Sources of flood risk

Existing No known watercourse on site. There is limited formal drainage in the area. Highway drainage drainage is to ditches present at the boundary of the site. features No record of historical flooding at the site. Note that rural greenfield sites may have experienced flooding that has not been recorded due to the lack of properties that Flood history would be affected. BFC Highways note that flooding has occurred previously on Forest Road (B3034) further to the east, near Mill Ride golf club. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: This site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map Surface Water 1 in 30-year 1 in 100-year 1 in 1,000-year 0.0% 0.0% 1.4%

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Description of surface water flow paths: The site is not at risk of surface water flooding in the 1 in 30-year and 1 in 100-year events. In the 1 in 1,000-year event flooding is predicted on all the surrounding roads, with slight encroachment into the north and south edges of the site. Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 88.4% 88.4% Description of groundwater risk: The majority of the site, except the north-west corner, is predicted to have groundwater levels between 0.025 and 0.5m below the ground surface in a 1 in 100-year groundwater event. Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The majority of the site falls within postcode area RG42 7, which has no properties on the Thames Water Sewer Flooding Register. The north east corner falls within RG42 Sewer 6, which has four properties on the register. This is a very small proportion of the total properties in the postcode area.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

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Water Framework Directive WINK7 is within the Cut (Ascot to Bull Brook confluence at Warfield) (WFD) catchment name catchment 46 Proposed development 22% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact High within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / No known structures on site. structure blockage?

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Access is likely to be on Chavey Down Road, with suitable pedestrian enhancements. Access and Surface water flooding occures at the 1 in 1,000-year rainfall event on all surrounding egress roads - Winkfield Row, Forest Road (B3034) and Chavey Down Road (B3017)

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Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.021

Groundwater Source No Protection Zone?

Historic Landfill No Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, groundwater flooding, and the interaction between them, should be considered as part of a site- specific flood risk assessment. Requirements • The impact of the development on flood risk from all sources both on and off-site must for site- be considered and modelled where appropriate. specific • The cumulative impact on flood risk of this development and other proposed Flood Risk developments in the Cut (Ascot to Bull Brook at Warfield) catchment must be Assessment considered by the FRA and in planning decisions. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future.

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• Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater Guidance for is likely to emerge, preserving these areas as green infrastructure. site design • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • The design of SUDS schemes must take into account the seasonally high groundwater table and low permeability. Infiltration techniques may be ineffective, Requirements and may pose a pollution risk. SuDS may need to be shallow and take up larger for SuDS and areas. Above ground conveyance and attenuation can be used but care must be surface water taken that groundwater does not enter the SuDS feature and reduce the storage management capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • The condition and location of the outfall from the development must be established. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

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Site details

Site code WINK14 Site name Land west of Braziers Lane/Locks Ride and north and south of Forest Road (Winkfield Row) Note: this summary is for the whole of WINK14 site, which comprises two areas (north and south of the B3034) Area 57.35ha

Greenfield or previously developed Greenfield land Housing, open space, SANG and primary school, neighbourhood centre and Proposed site use community centre Flood risk More vulnerable vulnerability

Sources of flood risk

Existing Northern edge of the site adjoins The Cut, a Main River. There are two raised ponds drainage in the north west corner of the site. features A number of reported flood events have occurred on The Cut, and it is likely that they may also have affected the northern edge of the north site. No flood history was found for the south site. The Environment Agency’s The Cut Flood Risk Mapping Study notes ten events on The Cut: November 1894, January 1915, March 1947, September 1968, November 1974, May 1979, June 1981, October 2000, August 2002 and July 2007. Downstream of the site there have been flood outlines mapped for March 1947, November 1974, December 1981 and February 1990 (Environment Agency Recorded Flood Outline). Nearby, BFC Highways flood records show several reported flooding incidents just Flood history downstream at Winkfield Row/Brock Hill: • the Brock Hill area experienced flooding in July 2007. No source or mechanism is identified. • the B3017 as it crosses The Cut experienced flooding in 2008. No source or mechanism is identified. • the Bracknell Road/Cricketers Lane junction as it crosses The Cut experienced flooding in August 2002, November 2006, July 2007 and 2008, May 2018. The source was overtopping from The Cut. BFC Highways note that flooding has occurred previously on Forest Road (B3034) further to the east, near Mill Ride golf club. Proportion of whole site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 4.0% 0.8% 1.0% 94.0% 5.4% Available detailed modelling data: Fluvial Environment Agency (2013) ISIS-TUFLOW model of The Cut, built as part of The Cut Flood Risk Mapping Study. The Environment Agency have indicated at the time of publication that they have commenced re-modelling of The Cut. The most recently available model data will be used to inform any site specific FRAs.

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Detailed nature of flood characteristics: The north-west corner of the north site is likely to be inundated in the 1 in 5-year event, and the north-east corner starts to flood at the 1 in 20-year event (Flood Zone 3b). Flood extents get gradually larger as return period increases. Depths on the floodplain could reach 0.7m in a 1 in 100-year plus climate change event, with hazard of ‘Danger to some’ in these floodplain areas. Proportion of whole site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 4.4% 8.3% 21.7% Description of surface water flow paths: The two parts of the site form almost an entire surface water catchment, with water Surface Water from the area to the south of Forest Road (B3034) draining northwards across the northern part of the site, towards The Cut. One main flow route forms during the 1 in 30-year event and flows from the south site across the road and through the southern site just east of the centre. At the 1 in 100-year event, an additional smaller route flows past the ponds in the north west corner. At the 1 in 1,000-year event, several smaller routes flow in parallel. Proportion of whole site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m Groundwater 0.0% 2.1% 2.1% Description of groundwater risk: The site is almost entirely at ‘no risk’ of groundwater flooding, except for a small area to the south of Forest Road (B3034), where groundwater levels in a 1 in 100-year event are predicted to reach between 0.025 and 0.5m below the surface. The Environment Agency's Risk of Flooding from Reservoirs map predicts that flooding Reservoir / may occur along The Cut if Fish Pond at Ascot Place were to fail or overtop. The extent impounded of flooding is predicted to cover 4.3% of the north edge site in the far south east corner water body to depths of around 0.3 to 2.0m closer to the river, decreasing to 0 to 0.3m further away failure from the channel. This area is almost entirely contained within the existing Flood Zone 2 and 3, with just a small strip extending beyond Flood Zone 2. Canal There are no canals in Bracknell Forest. The site falls within postcodes RG42 7, RG42 6 and SL5 8. RG42 6 has four properties on the Thames Water Sewer Flooding Register, RG42 7 has no properties and SK5 8 has two properties registered. This is a very small proportion of the total Sewer properties in the postcode areas. The LLFA are aware of issues associated with surcharging of foul sewers in the vicinity of the site, to the east of the Cricketers Lane/Bracknell Road junction, reported by the Parish Council.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

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Climate change under both the +35% and +70% scenarios is likely to increase the area Impact of of Flood Zone 3a slightly to be similar to the current Flood Zone 2. The extent of Flood climate change Zone 2 is also likely to increase slightly, but modelling the impacts of climate change on fluvial on Flood Zone 2 is not currently a requirement under the NPPF. Flooding is likely to flooding and become more frequent under both climate change scenarios, and the impact of an the Flood Zone event with a given probability is also likely to become more severe, with water depths, classification velocities and flood hazard increasing. Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

Cumulative Impact of Development

Water Framework Directive WINK14 is within the Cut (Ascot to Bull Brook confluence at Warfield) (WFD) catchment name catchment 46 Proposed development 22% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact High within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties

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Flood risk management infrastructure and residual risk

There are no formal (raised) defences present on The Cut at this location, or other known defence schemes which may provide benefit. The Environment Defence type Agency Spatial Defences layer records the banks as 'high ground' with 'no maintenance'. The Environment Agency Spatial Defences layer records the ‘design standard Standard of protection as 5-years and actual standard 0-years. This suggests that the banks provide (SoP) no actual flood defence function. The Environment Agency Spatial Defences layer records the general condition Environment Agency’s as 3, with the worst condition of sections of the bank within the site being 5. defence condition Based on principles of Condition Assessment Manual (Environment Agency, assessment 2012). 1 (Very Good), 2 (Good), 3 (Fair), 4 (Poor), 5 (Very Poor) Risk of defence No risk of defence breach / overtopping as there are no formal (raised) defences. breach / overtopping?

Risk of culvert / No known structures on site. No structures are apparent on OS mapping. The structure blockage? presence or absence of any structures under the B3034 should be confirmed.

Emergency planning

The area receives a Flood Alert under the Environment Agency's Flood Information Flood warning Service. The site falls within 'The Cut' Flood Alert Area. There are likely to be multiple access points from Braziers Road, Forest Road (B3034), Locks Ride and/or Winkfield Row, and changes to the alignment of any of these roads may be required. Braziers Road to the north may be affected by flooding Access and from The Cut in the 1 in 20-year event and above, but access would be possible from egress the south. In a surface water event, a flow route develops flowing northwards along Braziers Lane in a 1 in 30-year event and above. Flow routes also cross Forest Road (B3034) in the 1 in 30-year event and above. In the 1 in 1,000-year event all of the available access roads would be affected by surface water.

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Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Gravel, Sands and Silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.021

Groundwater Source No Protection Zone?

Historic Landfill There is a small historic landfill site in the west of the southern part of the site. Site?

Requirements for planning and NPPF

The Sequential Test must to be passed. Only once the Sequential Test is passed should the Exception Test be applied. The Exception test will be required in the following scenarios: • If More Vulnerable and Essential Infrastructure is located in FZ3a. Sequential • If Highly Vulnerable development is located in FZ2. Test and • If Essential Infrastructure is located in Flood Zone 3b Exception Development will not be permitted in the following scenarios Test requirements • Highly Vulnerable infrastructure within FZ3a and FZ3b. More Vulnerable and Less Vulnerable Infrastructure within FZ3b.

It must be shown that the development will be safe for its lifetime and the risk can be managed through a sequential approach to design. • Consultation with the LLFA and the Environment Agency should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is within Flood Zone 2 and 3 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding and groundwater Requirements risk, and any interaction between them, should be considered as part of a site-specific for site- flood risk assessment. specific • The impact of the development on flood risk from all sources both on and off-site must Flood Risk be considered and modelled where appropriate. Assessment • The cumulative impact on flood risk of this development and other proposed developments in the Cut (Ascot to Bull Brook confluence at Warfield) catchment must be considered by the FRA and in planning decisions. • The Environment Agency should be consulted to obtain the latest hydraulic modelling information of The Cut at the time of the flood risk assessment. They will advise as to whether existing detailed models need to be updated. • Detailed surface water modelling should be undertaken to better understand baseline and post-development surface water risk flowing into the site, on site and downstream.

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• A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future. • The presence or absence of any flow routes under the B3034 should be confirmed.The impact of structure or culvert blockage should be considered as part of the assessment. • The impact of the development on existing sewer flooding issues should be discussed with Thames Water at an early stage. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Flood Zones 2 and 3, and Flood Zone 3a plus 70% climate change (subject to a detailed flood risk assessment using up to date model information) should be preserved as green infrastructure, with built development restricted to Flood Zone 1. Development should be steered away from surface water flow routes and areas where groundwater is likely to be highest, preserving these areas as green infrastructure. • Safe access and egress should be demonstrated in the 1 in 100-year plus 35% and, Guidance for in consultation with the LLFA, the 1 in 100-year +70% climate change event. Safe site design access and egress should also be demonstrated in the 1 in 100-year plus 40% climate and making change rainfall event. Raising of access routes must not impact on flow routes. development Consideration should be given to the siting of access points with respect to surface safe from water flood risk areas. flooding • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • The site should be designed to avoid putting property at risk from the small area of high groundwater risk. • Compensation storage would need to be provided for any land-raising within the 1 in 100 plus 35% climate change allowance, including to provide a safe access route. • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • Reservoir risk posed by Fish Pond at Ascot Place should be considered as part of emergency planning for the site.

• A site-specific surface water drainage strategy will be required. Requirements for SuDS and • Early liaison with Thames Water is recommended to obtain agreement in principle for surface water connection to the surface water sewer (if required). management • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March).

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• Existing surface water flow routes from off-site and areas at risk of high groundwater risk must be accommodated within the masterplan. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where possible. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep). • Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

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Site details

Site code WINK22 Site name Land to south of London Road, east of Bog Lane and west of Swinley Road (Whitmoor Forest) Area 45.67ha

Greenfield or previously developed Greenfield land Housing, open space, SANG, primary school, neighbourhood centre, Proposed site use community centre and care home Flood risk More vulnerable vulnerability

Sources of flood risk

Existing A number of unnamed drains converge in the centre of the site, before exiting in the drainage south west corner towards Bull Brook. features No records of historical flooding were found. The road along the west edge of the site is called Bog Lane, which indicates that historically conditions may have been Flood history waterlogged in this area. Note that the LLFA does not generally hold records of flooding unless property has been affected. Rural greenfield sites may have experienced flooding that has not been recorded. Proportion of site at risk in Flood Zones FZ3 plus 70% FZ3b FZ3a FZ2 FZ1 climate change 0.0% 0.0% 0.0% 100.0% 0.0% Fluvial Available detailed modelling data: N/A Detailed nature of flood characteristics: This site is at very low risk of fluvial flooding. Proportion of site at risk in Risk of Flooding from Surface Water Map 1 in 30-year 1 in 100-year 1 in 1,000-year 4.7% 7.7% 14.9% Description of surface water flow paths: There are a number of clearly defined flow routes at the 1 in 30-year event, some of which originate on site, however some flow onto the site site from an area just to the north of London Road. The flow paths are parallel with, but do not follow, the drains on the OS mapping. The flow routes converge and flow off site at the south west Surface Water corner. The railway embankment appears to present a barrier, causing water to pond, with excess surface water predicted to flow north westwards into the residential area of Martin’s Heron. The mapped drain disappears here, and it is unclear whether there is a route for surface water to flow under the railway, through The Warren residential area and join the Bull Brook.

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Proportion of site in JBA Groundwater Map 1 in 100-year risk categories Depth below surface Depth below Total in highest risk categories 0-0.025m surface 0.025 to 0.5m 75.2% 24.8% 100.0% Groundwater Description of groundwater risk: The site is at high risk of groundwater flooding. The majority of the site is at risk of groundwater emergence at the surface in the 1 in 100-year event, with the remaining 25% towards the north of the site likely to have water between 0.025 and 0.5m below the surface. These high risk areas coincide with surface water flow paths, and the two sources of flooding may interact.

Reservoir / impounded There are no known reservoirs or impounded water bodies likely to pose a risk to this water body site. failure

Canal There are no canals in Bracknell Forest. The site falls within postcode areas SL5 8 and RG12 9. SL5 8 has two properties on the Thames Water Sewer Flooding Register, RG12 9 has one property registered. Sewer This is a very small proportion of the total properties in the postcode area. There is a sewage treatment works just to the south of the site.

Impact of climate change

Climate change River Basin District Central Higher Upper End allowances for Central river flow for the ‘2080s’ Thames 25% 35% 70%

Impact of climate change on fluvial The site is likely to remain within Flood Zone 1 accounting for the effects of climate flooding and change. the Flood Zone classification Climate change is predicted to increase rainfall intensity in the future by a range of between 20% and 40% (the recommended national precautionary sensitivity range for Impact of 2085 to 2115). This will increase the likelihood, frequency and extent of surface water climate change flooding. on flood risk The effect of climate change on groundwater flooding, and those watercourses where from other groundwater has a large influence on winter flood flows is more uncertain. Milder sources wetter winters may increase the frequency of groundwater flooding incidents in areas that are already susceptible, but warmer drier summers may counteract this effect by drawing down groundwater levels to a greater extent during the summer months.

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Cumulative Impact of Development

Water Framework Directive WINK22 is almost entirely within the Bull Brook catchment. (WFD) catchment name 16 Proposed development 11% Number of developments area as % of WFD proposed catchment area Potential for cumulative impact Medium within WFD catchment

Susceptibility of downstream Low. The Cut (Binfield to River Thames confluence) and Maidenhead catchment Ditch is a rural catchment, with low risk to properties.

Flood risk management infrastructure and residual risk

This site does not benefit from any known formal defences or flood alleviation Defence type scheme. Standard of protection No flood defences present. (SoP)

Environment Agency’s No flood defences present. defence condition assessment

Risk of defence No risk of defence breach / overtopping breach / overtopping?

Risk of culvert / Presence or absence of a flow route and structure under/through the railway structure blockage? embankment should be confirmed. This may pose a blockage risk.

Emergency planning

Flood warning This site is not covered by the Environment Agency’s Flood Information Service.

Work is on-going on the access points for this site. It could be accessed from New Forest Ride (B3430) to the west, London Road (A329) to the north or the B3017 to Access and the east. These routes are almost entirely dry in the 1 in 30-year surface water event, egress with some small areas of ponding in the 1 in 100-year event. In the 1 in 1,000-year event there is more ponding and flow routes cross both New Forest Ride and London Road, but the B3017 is dry adjacent to the site.

157 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

Sustainable drainage and flood risk betterment

Bedrock Geology Clay, Sands and silt

Superficial Geology N/A

Slowly permeable seasonally wet slightly acid but base-rich loamy and clayey Soil type soils

Typical slope 0.015

Groundwater Source No Protection Zone?

Historic Landfill No Site?

Requirements for planning and NPPF

Sequential The site is within Flood Zone 1 but at risk from other sources of flooding. The Sequential Test and Test must be passed. The Exception Test is not required under the NPPF, but it must be Exception shown that the development will be safe for its lifetime and the risk can be managed Test through a sequential approach to design. requirements

• Consultation with the LLFA should be undertaken at an early stage. • A site-specific flood risk assessment will be required because the site is over 1ha in area within Flood Zone 1 and at risk from sources of flooding other than rivers and the sea. Government guidance on flood risk assessments must be followed (https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications). • All sources of flooding, particularly the risk of surface water flooding, groundwater flooding, and the interaction between them, should be considered as part of a site- specific flood risk assessment. • The impact of the development on flood risk from all sources both on and off-site must be considered and modelled where appropriate. Requirements for site- • The cumulative impact on flood risk of this development and other proposed specific developments in the Bull Brook catchment must be considered by the FRA and in Flood Risk planning decisions. Assessment • A detailed hydraulic model should be developed of the unnamed drains and surface water flow paths to better understand baseline and post-development surface water risk flowing into the site, on site and downstream. • A detailed assessment of the risk and location of high groundwater levels and groundwater emergence should be undertaken, including groundwater monitoring during the winter months. • Climate change should be assessed using recommended climate change allowances at the time of the assessment (https://www.gov.uk/guidance/flood-risk-assessments- climate-change-allowances) for the type of development and level of risk. The current allowances were published in February 2016 but may be subject to change in the future.

158 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Presence or absence of a route under/through the railway embankment should be confirmed. The impact of structure or culvert blockage should be considered as part of the assessment. • Development must seek opportunities to reduce overall level of flood risk both on and off-site, for example by reducing volume and rate of runoff and creating space for flooding. • The development should be designed using a sequential approach. Development should be steered away from surface water flow routes and areas where groundwater is likely to emerge, preserving these areas as green infrastructure. Guidance for • Safe access and egress should be demonstrated in the 1 in 100-year plus 40% climate site design change rainfall event. Raising of access routes must not impact on flow routes. and making Consideration should be given to the siting of access points with respect to surface development water flood risk areas. safe from • The design must ensure that surface water flows resulting from rainfall in excess of a flooding 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • Mitigation for seasonal high groundwater levels must be considered (for example by raising finished floor levels to an appropriate height above ground level). • Flow routes would need to be preserved if carrying out land-raising within the surface water risk area. • A site-specific surface water drainage strategy will be required. • Early liaison with Thames Water is recommended to obtain agreement in principle for connection to the surface water sewer (if required). • Detailed site investigations will be required including infiltration testing and groundwater monitoring during the winter months (November through to March). • Existing surface water flow routes from off-site must be accommodated within the masterplan. • SuDS are possible on all sites and a large greenfield site such as this should be able to implement an exemplar scheme to deliver multiple benefits including water quality, biodiversity, amenity, green infrastructure etc. • All development should adopt source control SuDS techniques. Conveyance features should be designed above ground and following natural flow paths where Requirements possible. Given the current undeveloped, wooded nature of the site, SuDS scheme for SuDS and must be designed to intercept the first 10mm of rainfall. surface water • The design of SUDS schemes must take into account the seasonally high management groundwater table. Infiltration techniques may be ineffective, and may pose a pollution risk. SuDS may need to be shallow and take up larger areas.This may impact on the developable area. Above ground conveyance and attenuation can be used but care must be taken that groundwater does not enter the SuDS feature and reduce the storage capacity and structural integrity of the design. • Choice of SuDS components should be based on detailed site information, examples may include swales, attenuation features, green roofs, rainwater capture and reuse,and permeable paving. • The level of detail and method of assessment of surface water runoff rates and volumes should be appropriate to the scale and risk of the development and should include recommended allowance for climate change and urban creep at the time of the assessment (currently +40% allowance for climate change and a 10% increase in impermeable area for urban creep).

159 Bracknell Forest Council Level 2 SFRA Detailed Site Summary Tables

• Storage for runoff from the development in extreme events should be located out of flood risk areas. • The design must ensure that surface water flows resulting from rainfall in excess of a 1 in 100-year event are managed via exceedance routes that minimise the risks to people and property. • SuDS design must follow the Bracknell Forest Council Design SPD, meet the Defra National Non-Statutory Technical Standards, and follow current best design practice (CIRIA Manual 2015).

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