Sustainable Drainage Systems Design Guide
Total Page:16
File Type:pdf, Size:1020Kb
Sustainable Drainage Systems Design Guide Essex County Council April 2016 SuDS Design Guide (i) Terms of Reference and Composition of SuDS The Working Group comprises ECC Officers: The Steering Group comprises those above Guide Working Group and Steering Group plus additional members representing: Planning & Environment The Working Group, formed to look at pro- Keith Lawson Essex Highways: David Ardley ducing a SuDS Design and Adoption Guide, Phil Callow Environment Agency: Graham Robertson consisted of representatives from various de- Lucy Shepherd Mersea Homes: Brad Davies partments within Essex County Council (ECC), Kathryn Goodyear Bellway Homes : Clive Bell/Ben Ambrose who reflect a range of related disciplines. The Tim Simpson Barratt Homes: Rodney Osborne Steering Group consisted of representatives Persimmon Homes: Terry Brunning from Essex County Council as well as external Development Management, Essex Highways Countryside Properties: Andrew Fisher organisations. The objective of the Groups Vicky Presland Essex Legal Services: Alan Timms was to: Peter Wright Tendring District Council: John Russel Peter Morris Basildon District Council: Matthew Winslow “Develop a Design Guide demonstrating Philip Hughes Epping Forest District Council: Quasim Durrani how new developments can accommodate SuDS, the standards expected of any new Place Services SuDS scheme to be suitable for approval and Crispin Downs adoption, provide an overview of the geology Peter Dawson and biodiversity of the county and advice on how SuDS will be maintained and how they should be ensured to be maintainable.” This has been achieved by: • Reviewing background information and current advice • Collecting suitable case studies within Essex • Considering updates from Defra and the National Standards Consultation • Taking on board comments from restricted and public consultations. Essex County Council SuDS Design Guide (ii)3 List of Amendments to Sustainable Drainage Systems Design Guide, Essex County Council, December 2014 Page Section Document Paragraph Amendment number 28 Runoff Rate Paragraph 2 Text added to provide clarification on acceptable runoff rates 28 Runoff Rate New paragraph Text added to provide clarification on minimum flow rates (paragraph 3) 28 Runoff Rate New paragraph Text added to provide clarification on rainfall models (paragraph 4) 29 Runoff Volume New paragraph Text added to provide clarification on runoff volumes 29 Storage Volume Paragraph 2 Text added to provide clarification on storage requirements and exceedance flows 29 Storage Volume Paragraph 2 Text added to provide clarification on urban creep 29 Storage Volume Paragraph 2 Text added to provide clarification on storage requirements for tide-lock 29 Storage Volume New paragraph Text added to provide clarification on half drain times (paragraph 3) 29 Storage Volume Paragraph 6 Text added and removed to provide clarification in relation to long-term storage 29 Storage Volume New paragraph Text added to comply with the latest Environment Agency climate change allowances (paragraph 7) 30 Design for Water Quality Paragraph 5 Text added to comply with the latest guidance on water quality in the CIRIA SuDS Manual C753 30 Design for Water Quality - Table and paragraph deleted 30 Design for Water Quality Paragraph 6 Text added to provide clarification on gullypots and catchpits 35 Design Criteria, Table, - Text amended to comply with the latest CIRIA SuDS Manual C753 Ponds, Local Standard 13: Design of ponds Essex County Council SuDS Design Guide (iii) CONTENTS 4.2.1 Mews Courtyard 43 4.2.2 Informal Street 49 Terms of Reference and Composition of SuDS (i) 4.2.3 Mixed Use Street 55 Guide Working Group and Steering Group 4.2.4 High Density Neighbourhood 61 List of Amendments to Sustainable Drainage (ii) Systems Design Guide, Essex County Council, 4.3 Schools 66 December 2014 4.4 Roads 69 1.0 Introduction 1 5.0 Appendices 70 1.1 Surface Water and Urbanisation 2 Appendix 1: Rainwater Harvesting and Greywater Recycling 72 1.2 The situation 2 1.3 Sustainable Development 3 6.0 Glossary of Terms and Acronyms 82 1.4 The Purpose of this Guide 4 1.5 The Structure of this Guide 4 7.0 References 87 1.6 The SuDS Management Train 5 8.0 Figure Table 88 2.0 SuDS and the Essex Environment 6 2.1 Topography 7 2.2 Rainfall 7 2.3 Geology 8 2.4 Historic Environment 11 2.5 Landscape and Townscape Character 12 2.6 Nature Conservation 12 3.0 Design Criteria 14 3.1 Local Principles 16 3.2 Local Standards 27 4.0 Designing SuDS 37 4.1 The Planning and Design Process 39 4.2 Design Examples 42 Essex County Council >>Rieselfeld, Freiburg, Germany 1.0 INTRODUCTION SuDS Design Guide 2 1.0 INTRODUCTION flooding experienced throughout the UK during the summer of 2007. 1.1 Surface water and urbanisation 1.2 Planning requirements Sustainable Drainage Systems (SuDS) are nothing new. They have been nature’s way of The Sustainable drainage systems: Written dealing with rainfall, since time began. At its statement (HCWS161) laid in the House of simplest, rain falling on the land may evaporate Commons on 18 December 2014 set out or be absorbed into the soil, nourishing our changes to planning that will apply for natural habitat, or else flows overland into major development from 06 April 2015. ponds, ditches, watercourses and rivers, This confirmed that in considering planning helping to sustain life by replenishing our applications, local planning authorities should precious water resource. consult the relevant Lead Local Flood Authority (LLFA) on the management of surface water; It is only recently that the balance of this natural satisfy themselves that the proposed minimum water cycle has been disrupted. Modern standards of operation are appropriate and urban development with its houses, roads and ensure through the use of planning conditions other impermeable surfaces has increasingly or planning obligations that there are clear altered the way that rainwater finds its way arrangements in place for ongoing maintenance into our soils, rivers and streams. Surface over the lifetime of the development. water has for many years been allowed to be collected and piped directly into our ditches On 24 March 2015, the Government laid and rivers. Conveying water away as quickly as a statutory instrument making the LLFA a possible from a development may adequately statutory consultee in relation to these major protect the immediate development from applications which applies from 15 April 2015. flooding but increases the risk of flooding As part of this role, in advising on ‘surface occurring downstream. This unsustainable water’ the LLFA will consider surface water approach to surface water drainage, together flood risk to and from the development as well with the potential effects of a changing as the provision of appropriate SuDS in line climate, has contributed to some very serious with best practice and the criteria outlined in consequences on life, property and the this Guide. environment as evidenced by the disastrous Bio-retention planters, Portland, Oregon, USA 1.0 Introduction Essex County Council SuDS Design Guide 3 This document forms the local standards Control the quantity Manage the quality of for Essex and, together with the National of runoff to the runoff to prevent • support the management of pollution Standards, strongly promotes the use of SuDS flood risk, and • maintain and protect which help to reduce surface water runoff and the natural water mitigate flood risk. cycle Water Water Quantity Quality A return to more natural, sustainable methods of dealing with surface water from development SuDS Design will also have additional benefits for: • Water quality – SuDS can help prevent Amenity Biodiversity and treat pollution in surface water runoff, protecting and enhancing the environment and contributing towards Water Framework Create and sustain Create and sustain better places for better places for Directive objectives. people nature • Amenity – SuDS can have visual and community benefits for the community. Figure 1.2.1 What are SuDS? (Adapted from CIRIA SuDS Manual, 2015) • Biodiversity – SuDS can provide the opportunity to create and improve habitats for wildlife, enhancing biodiversity. 1.3 Sustainable development Essex County Council is committed to making See also: our county a place which provides the best Water Framework Directive on the possible quality of life for all who live and Environment Agency’s website: http:// work here. Making it more sustainable is an www.wfduk.org/ important part of supporting this vision and it is therefore implicit that new development should incorporate sustainability measures that help achieve this goal. Appropriately designed, constructed and maintained SuDS support the ideal of SuDS wetlands, Wellesley College, USA 1.0 Introduction Essex County Council SuDS Design Guide 4 sustainable development. SuDS are more surface water drainage in Essex. It provides applications relating to sustainable drainage. sustainable than conventional surface water information on the planning, design and Pre-application advice may be sought from the drainage methods as they can mitigate many delivery of attractive and high quality SuDS County Council as early on in the process as of the adverse effects that stormwater run-off schemes which should offer multiple benefits possible. This guide provides a steer as to what has on the environment. This can be achieved to the environment and community alike. is expected and should complement national by: It should also show that meeting these