Flooding and Development
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DUMFRIES AND GALLOWAY COUNCIL Local Development \ Plan Supplementary Guidance Flooding and Adopted 1st December 2014 Development www.dumgal.gov.uk DUMFRIES AND GALLOWAY LOCAL DEVELOPMENT PLAN SUPPLEMENTARY GUIDANCE FLOODING AND DEVELOPMENT CONTENTS PAGE Introduction 2 Planning Framework 5 Roles and Responsibilities: Flooding and Planning 7 Matters to Consider for Planning Proposals 9 Flood Risk Assessment (FRA) 9 Certification and Checklists 13 APPENDIX 1: FRA Reference Documents 13 APPENDIX 2: FRA Requirements 15 APPENDIX 3: Self Certification 19 ANNEX 1: SEPA Hazard Maps and LDP Allocated Sites 20 ACRONYMS 45 GLOSSARY 45 1 INTRODUCTION In order to satisfy the Council in respect of FRAs and DIAs, parties will be expected to The purpose of this Supplementary Guidance is provide independent verification of their to provide practical detail for the professional competence, unless it is clear that application of Local Development Plan Policy this is not required. IN7: Flooding and Development. The consequences of flooding, wherever it This policy is supported by supplementary happens, can be devastating and can pose a guidance. risk to life. Within the Dumfries & Galloway Council (DGC) area around 6% (approximately Flooding is primarily a natural phenomenon 4,000) of properties are at risk of flooding which cannot be prevented entirely. Despite from a variety of sources including this fact, it is not surprising that pressures for watercourses, the sea, groundwater and development can encourage proposals for surface water. land which may be susceptible to flooding, or that could exacerbate existing problems Policy IN7: Flooding and elsewhere. Additionally, global climate Development change is predicted to increase the likelihood of both coastal and inland flooding. However, The avoidance principle is the most sustainable if flooding is left un-managed it can have a form of flood management, in accordance devastating effect on people, property, with the first principle of Scottish Planning businesses and land. Policy (this is a reference to the now superseded SPP that was published in 2010. This is a reference to the now superseded SPP There is different wording in the current SPP, that was published in 2010. There is different however, the substance of the current SPP is wording in the current SPP. However, the the same as the 2010 version in respect of this substance of the current SPP is the same as the reference to flood management) relating to 2010 version in respect of this reference to sustainable development and the Flood Risk flood management. Management (Scotland) Act 2009. Where Note: The meaning of ‘flood risk’ is from SPP. proposed development could lead to an It is ‘the combination of the probability of a unacceptable onsite or off site flood risk (The flood and of the potential adverse meaning of ‘flood risk’ is from SPP. It is ‘the consequences, associated with a flood, for combination of the probability of a flood and human health, the environment, cultural of the potential adverse consequences, heritage and economic activity’. associated with a flood, for human health, the environment, cultural heritage and This Supplementary Guidance also explains the economic activity), as defined by the Risk wider context to DGC’s flooding policy and the Framework in SPP, then it will not be responsibilities of the main parties with permitted. Where a proposed development particular interests. It intends to encourage an could lead to an unacceptable flood risk, it increased interest, understanding and may be that a Flood Risk Assessment (FRA) is knowledge about flooding and drainage issues able to clarify to the satisfaction of the Council for everyone involved in the development and SEPA that the level of risk both on and off process, and thus make Dumfries and site would be acceptable. Galloway a safer place to live, work and visit. For any site a Drainage Impact Assessment DGC is committed to working with developers (DIA) may be required to ensure that surface to ensure that appropriate forms of water flows are properly taken into account in development take place in appropriate the development design. Consideration locations and so do not generate unacceptable should be given to pluvial flows (Those which flood risk and are not liable to exacerbate exceed the capacity of any formal drainage flood risk elsewhere. Flooding and drainage system). Design of development must avoid are material planning considerations. flood risk from exceedance flows. (See also Policy for Surface Water Drainage and SuDS.) 2 This guidance document is aimed at helping of flooding cannot be simply separated out DGC achieve its long term flood management and covered in a single policy. There are aspirations which include: important connections with other planning Addressing flood risk issues as early as policies and other Council possible and prior to any development responsibilities. These are: commencement; The arrangements for surface water Achieving good-quality and reliable treatment, including sustainable flood risk assessment of proposed drainage systems (SuDS) and avoidance development sites; of exceedance flows for developments; Provision of adequate access to bodies of Waste water arrangements for water for maintenance and inspection developments; purposes; Standards of development construction; To reduce flood risk to existing and development if possible, without The management of development increasing risk elsewhere; and infrastructure. Working with the water environment, including support for the principles of These connections are recognised and in the sustainable flood management. context of Flooding and Development this Supplementary Guidance takes them into DGC has several different responsibilities in account. respect of flooding. This Supplementary Guidance is focussed on part of one of them, DGC wants to ensure that the built the responsibility that arises from the Council’s environment works with the water role as planning authority. The roles and environment by steering new development responsibilities of Dumfries & Galloway away from areas at unacceptable risk of Council (DGC) in connection with planning and flooding and by requiring developers to flood risk are significantly influenced by new consider how their development is likely to general duties outlined in Section 1 of the impact on flood risk elsewhere. Flood Risk Management (Scotland) Act 2009 (see Appendix 1, Document 1). These require DGC recognises that managing flood risk and the Scottish Ministers, SEPA and all responsible surface water is a material consideration for authorities (including local authorities) to: any development which should be assessed Exercise their flood risk related functions from the outset by an appropriately qualified, with a view to reducing overall flood competent and experienced professional risk; (Appendix 3 sets out the Self Certification Act in the way best calculated to manage requirements for Flood Risk Assessment). The flood risk in a sustainable way; location, layout and design of new developments are the most critical factors Promote sustainable flood management; determining both the probability and impacts Act in the way best calculated to of flooding. contribute to the achievement of sustainable development; and, Detailed information on the concept of ‘flood Adopt an integrated approach by risk’ i.e. the probability that a particular co-operating with each other so as to magnitude of flood will occur sometime in the co-ordinate the exercise of their future coupled with the impact that such a respective functions. flood is likely to have, is available from publications such as CIRIA C624 (See Appendix This Supplementary Guidance aims to support 1, Document 22) and SEPA’s Technical Flood the avoidance of flood problems and to Risk Guidance for Stakeholders document (See improve the design and implementation of Appendix 1, Document 9). developments and their related drainage arrangements. However, the various aspects 3 Potential sources of flood risk are described in first published in January 2014. (See Appendix SEPA’s Technical Flood Risk Guidance for 1, Document 8) These replace the Indicative Stakeholders. They are: Map first published in 2006, and are Fluvial – flooding originating from a considered to be more accurate by SEPA and watercourse either natural or culverted. DGC. Flood hazard resulting from; river, Coastal – flooding originating from the coastal and pluvial (rainfall) sources is sea (open coast or estuary) where water presented on separate maps. In viewing the levels exceed the normal tidal range maps it is important to be aware that they are and flood onto the low-lying areas that still ‘indicative’ and have certain limitations. define the coast line. These include: Pluvial – urban or rural flooding which Whilst they provides a high quality and results from rainfall-generated scientifically robust indication of areas overland flow before the runoff enters which may flood, this is for a any watercourse, drainage system or presentation scale no greater than sewer. Note: this can be from within or 1:25,000; outwith the site. They have been developed to give an Groundwater - flooding due to a indication of whether a general area, not significant rise in the water table, individual properties, may be affected by normally as a result of prolonged and flooding; heavy rainfall over a sustained period The fluvial maps only include the of time. effects of hydraulic structures such as Drainage -