WET News

MARCH 2015 WET NEWS 19 New planning rules come into e ect next month but the drivers for retro• tting SuDS are much less clear, says Alex Stephenson. The challenge: Achieving best practice with SuDS Housing developers will need to demonstrate how SuDS compo- nents will be e ectively maintained throughout their life L ong-awaited regulations for the design and con- struction of Sustainable Drainage Systems (SuDS) in new developments nally come into force on April 6, 2015. The hope is that the new rules will help clarify best practice. However, they are not as detailed or prescriptive as was originally conceived by Sir Michael Pitt in his review of the 2007 „ oods, in particular where water quality is concerned. Planning authorities will now be responsible for oversee- ing an 'expectation' for SuDS to be built on new developments of ten properties or more as part of the National Planning Policy Framework (NPPF) in England. Implications The government's revised plans leave local authorities, develop- ers, contractors and water com- panies concerned to understand the implications of new rules and what will constitute good practice in SuDS installation, adoption and maintenance. To get planning approval, developers will need to demon- strate how SuDS components will be eŽ ectively maintained throughout their life. In theory this should avoid the potential for schemes to be le' neglected or rendered inef- fective through lack of regular care and inspection. The rules only apply to England; diŽ erent regulations apply in Scotland, Wales and Northern Ireland. In Scotland, for example, there has historically been a much greater emphasis on achieving water quality objectives. Overall, the new rules could leave the design and construc- tion of SuDS more open to inter- pretation and more subject to local priorities. But what might become a "postcode lottery" on the one hand, could also result in „ ood risk and water quality protection best suited to the local conditions. Many local authorities, and some water companies, have already developed their own design guidance which provide excellent sources of reference. CIRIA's expected update to C697, the SuDS Manual will be more important than ever in providing a national framework for best practice. The need to encourage good SuDS practice with developers and housebuilders, has recently been the main focus of concern. However, SuDS are also regu- larly built by highways authori- ties and by water companies, who can build, own and main- tain SuDS to prevent „ ooding and over-capacity of their sewer networks. Concerted focus Indeed, water companies are a key stakeholder in surface water control and treatment, as the sewer network may be the last line of defence for poorly- designed or maintained SuDS features and will be an impor- tant statutory consultee in plan- ning applications. The new regulations for Eng- land only apply to new develop- ment, of course. To truly achieve comprehensive management of surface water quality and „ ood risk is going to require a con- certed focus on retro tting SuDS, but the drivers for retro t SuDS are much less clear and far more complex. "The new rules could leave the design and construction of SuDs more open to interpretation" Alex Stephenson THE CONCEPT ž Sustainable Drainage Systems (SuDS) are surface water management trains engineered to mimic natural paths and processes ž SuDS use a sequence of natural and / or manufactured components to slow the flow and manage volume and water quality ž Where possible, SuDS should engage, and provide multiple bene• ts for, the community by promoting local amenity and biodiversity NEED TO KNOW 1 Considering the whole 'tool box' of natural and proprietary SuDS components and techniques will achieve the best solutions 2 SuDS should perform as designed with repeatable, predictable maintenance regimes 3 A wide range of guidance and knowledge on SuDS is available, e.g. engineeringnaturesway.co. uk and Susdrain.org THE VERDICT ž Now that the arguments for widespread use of SuDS have been won, the challenge for the industry is to bring about "back to basics" SuDS principles that are sensible, practical and repeatable. There is also a growing acceptance that SuDS are not merely a pastoral vision of 'natural', green, above-ground features. Instead, they represent a best practice engineering and management approach, using a full "toolbox" of components to achieve sustainable Ÿ FLOOD RISK MANAGEMENT

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