Managing Surface Water Flooding in Paddock Wood Briefing note - June 2011

Transcription

1 Managing Surface Water Flooding in Paddock Wood Briefing note - June 2011 Information for Editors What is the reason for this initiative? 1. Legal Requirements The main drivers are the Flood Risk Regulations ( which transpose the EU Floods Directive into UK law, and were introduced on 10 December These confirm the Lead Local Flood Authority (LLFA) role for unitary and county authorities. Kent County Council is the LLFA for Paddock Wood. Specific tasks had to be undertaken by these authorities, with completion of Preliminary Flood Risk Assessments and identification of Flood Risk Areas due by June To deliver requirements, the Flood and Water Management Act ( received Royal Assent on 8th April 2010 and commenced in April Risk management authorities were expected to begin putting in place the organisational framework and strategic development ahead of this. The Act aims to improve both flood risk management and the way water resources are managed. It creates clearer roles and responsibilities and instils a more risk-based approach. This includes a new lead role for local authorities in managing local flood risk (from surface water, ground water and ordinary watercourses) and a strategic overview role for all flood risk for the Environment Agency (EA). Water companies and Drainage s are also involved. 2. Outcomes of Defra studies Based on national mapping provided by the Environment Agency, Defra identified that some properties in the Paddock Wood area may be susceptible to surface water flooding. Subsequently, Tunbridge Wells Borough Council (TWBC) undertook a Strategic Flood Risk Assessment (SFRA) which went some way to better understanding any flood risk and where that risk is located. The Surface Water will provide more in depth information and explore initial approaches to tackling this flood risk. What is meant by Surface Water Flooding? Surface water flooding can be caused by intense rainfall before it enters a watercourse or sewer; overland flow resulting from high groundwater levels exceeding the capacity of the sewer network; and out of bank flow from small watercourses which are not designated as Environment Agency Main River. High water levels in the main Medway and Teise rivers also have an important bearing in Paddock Wood as they can impede drainage of the town and surrounding areas. What sort of problems can it cause? Damage can be caused to properties; access to and from areas can be affected causing disruption and concern. Also, the sudden onset of surface water flooding can create road safety issues and risk to pedestrians. Wasn t this all covered in the earlier project the SFRA? Strategic Flood Risk Assessments, including the one undertaken in Paddock Wood in 2009, look at all potential flooding problems in relation to planning and development and provide an overview of the situation. They do not focus on surface water flooding alone, but it is included as part of the bigger flood risk picture. Importantly, SFRA s do not go into any great

2 Managing Surface Water Flooding in Paddock Wood Briefing note - June 2011 depth about cause and effect, nor do they propose measures to manage flood risk beyond what can be applied as part of a development. So what is the purpose of this SWMP? The aim of a SWMP study is to go into greater detail and understand more about surface water flood risk. The work involved maps the flood risk, including how existing properties and locations are being affected or may be affected in different weather conditions, identifies sustainable responses (known as options or measures) to manage surface water flooding, and produces an Action Plan. This Action Plan will provide an evidence base upon which future decisions and funding applications for putting the recommendations into practice can be taken forward. How is this being tackled and who is involved? Preparation of the Action Plan for Paddock Wood is building on previous studies (e.g. the SFRA and the Integrated Urban Drainage Pilot Study). Following Defra guidance, it comprises the following key stages: Preparation: A partnership approach to local flood risk management through integrated working between the County, Borough and Town Councils, the Environment Agency, Southern Water, the Upper Medway Internal Drainage and other strategic stakeholders. Risk Assessment: An initial assessment to determine the highest flood risk areas within Paddock Wood and the key issues upon which the main study should focus. Detailed modelling in these highest risk areas will provide greater understanding of how and why this type of flooding occurs, an economic assessment of the likely damage and the ability to test potential management options to determine their viability. Options: Identification and review of potential options/measures to manage surface water flooding, with a focus on those which will be sustainable and provide as many benefits as possible (e.g. environmental and social). Action Plan: Selection of preferred management options and preparation of an Action Plan to take these options forward and the roles and responsibilities of the different partners in this. What stage is the project at? The SWMP project started in April 2011, and a working partnership has been established with TWBC as the lead partner. The initial risk assessment and modelling has been completed and options are being developed. Following the public event, options will be finalised for the Action Plan. The information collected and analysed includes consultation with stakeholders in the Kent, Borough and Town Councils to identify key issues, as well as desk based assessment of available information and site inspections. What do you mean by stakeholders? Everybody who lives, works or has an interest in Paddock Wood is a stakeholder, as are the project partners and organisations representing local activities. These include Paddock Wood Town Council, the Paddock Wood Succeed Partnership, local businesses, residents associations, directly affected individuals and many others. All will be involved in the project before it finishes and conclusions are reached. How can local communities/individuals have their say? Consultation with partner organisations and stakeholders including the public is very important throughout the entire process. People s experiences of flooding and their

3 Managing Surface Water Flooding in Paddock Wood Briefing note - June 2011 concerns for the future have an important role to play in understanding what happens and proposing solutions. Partners, Paddock Wood Town Council, local organisations, residents and the public will be consulted on the draft Action Plan. All views will be taken into consideration before it is finalised. An open get information and have your say event is planned for 14 th July, 2011 in the Wallis Room at St. Andrews Church, Maidstone Road, Paddock Wood, Tonbridge, Kent, TN12 6DZ. This will be well advertised to enable people to come along, better understand the process and have their say. After the event, all information and a views giving form will be on the TWBC website for one week. For further information, or to request this document in an alternative format, please contact TWBC Press Office on , press.office@tunbridgewells.gov.uk Notes to Editors: With help from TWBC s partners (the Environment Agency, Mid Kent Drainage, and Southern Water) and consultation with local organisations such as Paddock Wood Town Council

4 1 Public Information Event 14th July 2011 Event Guide Thank you for coming to this event and welcome! To help you get the most out of your visit, we ve laid out information in specific sections please follow the trail below, as going around in order really will help you, especially when it comes to giving your views. Your information trail Please start at: Where I live poster - put a sticky dot on the map provided to show where you live/work. This will help us see the range of locations amongst those visiting. Then, Setting the SWMP scene information here gives the background to the SWMP, what it s about, who is involved and timescales. Then, What do we know so far? - what we have found out and how; what is likely to happen in exceptional periods of torrential rain. What do you think? Please put your numbered sticky dots on the map provided and write down related comments on your special sheet. Then, What might be done in Paddock Wood potential measures (actions) and where. What do you think? Please put your numbered sticky dots on the map provided and write related comments on your special sheet. And finally, What happens next. Here you can find out how we will give you feedback and likely next steps. Information from you to us Everyone will be given their own uniquely referenced pack with: o Numbered sticky dots o Comments sheet o A briefing note summarising the background to the SWMP o A short questionnaire to help us capture the range of different people visiting and give you a further chance to meaningfully have your say. Kindly complete and leave this with us today. Nothing is compulsory but all information will help the project. We ve tried to make this open and fair to all and there is also a comments book for your use. The Project team is here to help in any way they can.

5 2 About the SWMP What is meant by Surface Water (SW) Flooding? This type of flooding can be caused by: o Extremely intense rainfall before it enters a watercourse or sewer o Flooding from sewers and drains when flows are higher than their capacity. o Out of bank flow from small open and culverted watercourses o Blockages and debris in watercourses and sewers can exacerbate flooding. o High water levels in the rivers Medway and Teise have an important bearing in Paddock Wood; when levels are high they can impede drainage of the town and surrounding areas. What sort of problems can it cause? o Damage can be caused to properties; o Access to and from areas can be affected causing disruption and concern. o The sudden onset of surface water flooding can create road safety issues and risk to pedestrians. Who is involved in this? A group of partners all with a role to play Local stakeholders e.g. Paddock Wood Town Council Local organisations - e.g. schools, businesses People who live and work in the area Anyone who takes an interest. All can have a say and their views will be considered. What is not covered by surface water flooding and this study? o Direct flood risk from the Medway and Teise; o Actually putting the outcomes of the study into practice. The study will prepare a draft Action Plan which will be taken forward and developed by the Partnership.

6 3 Why does Paddock Wood need a SWMP? The Floods and Water Management Act and recent changes to funding arrangements for flood risk management with greater emphasis on local funding are driving increased attention on flooding not from main rivers or the sea. The Tunbridge Wells Borough Council Strategic Flood Risk Assessment (SFRA) identified Paddock Wood as a critical drainage area. land which is not in the fluvial (river) flood zones 2 or 3 but is at risk from surface water flooding. Paddock Wood has a history of existing flooding issues from various sources There is potential for significant development within Paddock Wood. We should consider the risk of flooding at all stages of planning, to ensure that flood risk to new and existing homes and businesses is reduced. The SWMP is not pro or anti development it aims to ensure that flood risk is properly considered, however Paddock Wood develops in the future. The drainage of Paddock Wood is the responsibility of several organisations no single organisation can manage flood risk on its own, so a partnership approach is required. The Surface Water therefore will: o Focus on surface water flooding; o Provide more in depth information including how existing properties and locations are being effected or may be affected in different weather conditions o Provide important baseline information for all future planning decisions (for individuals as well as larger scale) o Explore sustainable initial ways (measures) for reducing risk from flooding o Produce an Action Plan to help future decisions and funding applications to put recommendations into practice.

7 4 What stage is the project at? Activity Status Date Appointment of study consultants Completed 24 March 2011 Project start up including first partnership meeting Completed 28 March 2011 Initial historic flood data review/review of potential problem areas Site visits to potential at-risk locations with Partnership Communications and Engagement Plan identifying exactly who would be involved and when Further information seeking from partners included meeting with Paddock Wood Town Council (PWTC) First stage integrated modelling mapping what has happened, where, when. Effects of torrential rain. Completed April 2011 Completed End May 2011 Completed June 2011 Completed Mid End June 2011 Completed June 2011 Identifying potential measures/actions Completed Mid June 2011 Risk assessment and potential measures workshop with partners and PWTC Model review meeting technical meeting to review modelling supported by Environment Agency and Southern Water Advertising of public information event (direct written/ ed invitations; article in Contact, posters/flyers, press release) Completed 20 June 2011 Completed 28 June 2011 Completed End June 13 July 2011 Paddock Wood SWMP Public Information Event!We are here! 14 July 2011 Feedback from public information event via To be End of August s and Contact magazine. completed Modelling and costing of measures Ongoing July 2011 Action Plan Workshop partners and PWTC will include refined modelling and potential measures to include public views available Arranged 20 July 2011 Final modelling and potential measures + prepare draft Action Plan Agree draft Action Plan with partners To be completed To be completed July 2011 Aug Sep 2011

8 5 How have we assessed the risk of flooding? Assess historic flooding Information about historic flooding in Paddock Wood has been collated from a wide range of sources and organisations: Collate drainage records Information on the location, dimensions and condition of drainage assets supplied by all partners. This has been put together to produce the first map of all drainage assets in the town. Site visit MIDB photos / records TWBC records / SFRA Historic flood risk Paddock Wood Town Council meeting Southern Water sewer flooding records EA historic outlines / photos Modelling flood risk A single model has been developed which represents: All foul and surface water sewers The Tudeley Brook, Gravelley Way Stream, Paddock Wood Stream, the East and West Rhoden The effects of severe rainstorms falling on Paddock Wood and the surrounding area. Assessing the present and future risk We model: A range of storms of different length (duration) and frequency (return period). The added impact of more intense rainfall due to climate change. The impacts of increased paving of gardens known as urban creep. The impact of new developments Urban Creep: Loss of front gardens to hard-standing driveways increases runoff and has been shown to increase flooding in many towns and cities.

9 6 What do we know so far? Flood risk to existing areas The town has been divided into 5 subcatchments based on the drainage network: Sub-catchment Flood history Potential flooding in an extreme event Allington Rd / Station car park stream Gravelley Way Stream / Tudeley Brook Paddock Wood Stream (south of railway) Rhoden system (south of railway) Flood risk to potential developments The SWMP is considering the flood risk to and drainage of six potential development areas: Potential Development Site Flood history Potential flooding in an extreme event Little Rhoden Farm Land at Church Farm Land off Mascalls Court Road Land at Mascalls Farm Land West of Maidstone Road Commercial Road West Extensive, mainly external flooding in Allington Rd, Lax ton Gardens, Ribston Gardens Link to flooding in Laxton / Ribston Gardens. Issues with land drainage inflow to sewers, Goldings / Ringden Ave. Frequent issues including Maidstone Rd, Forest Rd, Old Kent Rd and Church Rd. When Medway / Teise high, backs up to Letemple Rd. Flooding in cemetery believed to be due to local drainage. Flood history primarily related to Medway / Teise Northern half of site flooded in 1960 and Surface water flooding reporting near sewage treatment works. History of ponding and possibly high groundwater. Localised flooding at cemetery. None reported None reported at site, but site partially drains into the Paddock Wood Stream River flooding in Surface water flooding and sewer flooding has affected houses on Maidstone Rd. River flooding in Flooding could be up to 1m deep. Flooding could be up to 1m deep. Flooding could be up to 1m deep. Moderate flood risk predicted near to watercourses Priority for SWMP HIGH significant modelled risk. Open channel through car park currently not maintained. MEDIUM relief to Tudeley Brook beneficial but blockage risk and capacity at higher return periods a concern. HIGH significant modelled and recorded risk. Capacity and maintenance issued MEDIUM System capacity reasonable but vulnerable when Medway / Teise are high Paddock Wood Extensive areas in MEDIUM significant risk but Stream / Rhoden Fluvial Flood Zones primarily due to downstream system (north of 2 and 3. river levels railway) Key issues identified: o Six culverts beneath railway capacity, access for maintenance o Open channel in railway station car park access and maintenance o Ponds 4 detention ponds managed by Paddock Wood Town Council, without proper funding. Northern half of the site remains at risk from river flooding Some fluvial / surface water risk from East and West Rhoden, increased in the event of culvert blockage. Some fluvial / surface water risk from East and West Rhoden Limited risk to site from small streams. However, management of flow out of site would be critical given risk downstream. Site almost entirely within Fluvial Flood Zone 3. Site predicted to be at risk from fluvial flooding (Flood Zone 3) and surface water flooding.

10 7 What we think we know. What do you think? Have we missed anything important from the flood history? Is there anything specific about an area that you want to tell us? To give us your views please use the numbered sticky dots in your pack for this section. Stick them on the maps below, and write related comments on the special sheet that goes with the dots. Comments sections are numbered to match the dots. (Ask one of the team if you need further help with this).

11 8 What could be done? Working with measures. Flooding cannot be entirely eliminated, only managed down to acceptable levels. Measures are individual or combined actions that might be taken to help manage and alleviate flooding impacts. Defra has defined a long list of measures that we are working from. Each measure must deliver a clearly identifiable benefit (objective), and be practical, sustainable and cost effective. All partners will have a measures role in some way, depending on the individual circumstances. Government policy and funding will also govern what is possible. We started with this long-list of possible measures: Source Control Measures including Sustainable Drainage Systems (SUDS) Retro-fit SUDS at property level (green roofs, water butts etc.) Retro-fit SUDS at street/area level (swales, rain gardens etc.) SUDS on new developments at property level SUDS on new developments at development level Remove surface water misconnections from foul sewers Strategic measures Increased conveyance of water increase capacity of watercourses and sewers Storage within drainage systems Strategic flood water storage outside urban areas Improved maintenance regimes Land management to reduce run-off Raised defences Temporary defences (community scale) Resistance and Resilience Measures Management of overland flood water flows (e.g. allowing flow along roads) Property-level resilience temporary e.g. demountable door guards Property level resilience permanent e.g. raise thresholds Non-structural measures no building required Flow/level monitoring to help improve response Restrict expansion Public awareness and education (e.g. permeable drives, ad hoc extensions, fly tipping, flood preparation Refining and reviewing planning policy SUDS seek to mimic the natural drainage of land by slowing flow and allowing infiltration into the ground. They have benefits for flood management, water quality and wildlife. Images 2 and 3 by kind permission of SUDSnet at Larger-scale schemes, probably requiring greater degrees of investment and co-ordination Resistance designing or adaptingbuildings to keep out shallow flood waters. Resilience enabling faster recovery after a flood Measures based around people and policies

12 9 Measures being considered for Paddock Wood We have assessed all potential measures and, with inputs from partners and Paddock Wood Town Council, below are those we feel would work best in various types of situation/location. These are being tested and where found to be beneficial, costed. Those measures attracting most support from the partnership were: Sustainable Drainage Systems (SUDS) Focus on both new developments and on fitting SUDs into existing areas where appropriate. Land management to reduce run off working with farmers / landowners Strategic storage of water outside of urban areas Improved maintenance regimes. Improving capacity of culverts beneath the railway Public awareness and education. All saw an urgent need for ongoing public education and awareness raising about what they can do to help themselves and the profound effects of individual actions on surface water flooding Property level resilience measures Policy against culverting (piping) watercourses in new developments except where short culverts are required over access roads. Strengthening and informing planning policy and guidelines to include individual homes and driveways plus larger scale developments. These measures are currently being investigated and where appropriate tested in the model.

13 10 What do you think could be done? In principle, do you agree with the approach taken/measures being investigated, bearing in mind that we are governed by Defra approved measures, what partners can do and funding. To give us your views please use the numbered sticky dots in your pack for this section. Stick them on the map below, and write related comments on the special sheet that goes with the dots. Comments sections are numbered to match the dots. (Ask one of the team if you need further help with this).

14 11 Next Steps Dealing with surface water flooding in Paddock Wood will be made up of a series of steps and actions over time. It will not be a quick fix because there are many factors involved, including Government decisions about funding. In principle though, next steps will consist of the following: Complete SWMP Complete the evidence base documenting the level of risk and the costs and benefits of possible measures Draft version - Late July / Early August Action Plan The Draft Action Plan will consider what actions are appropriate, which organisations could deliver them and possible sources of funding. The Action Plan will become a working document to be developed and delivered by the Partnership, subject to funding... Secure Funding The way flooding schemes are funded in England is changing, and detailed guidance is still being developed by Defra. In future, local funding and funding from various sources including SWMP partners and private developers will play a larger role. A continued partnership is likely to be important to securing funding for Paddock Wood. Thank you for your interest. Look out for updates in the press, through your Town Council and on TWBC s website

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