Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | march 2015 | 35 In the know Getting to grips with… sustainable drainage systems T he Government's revised plan to regulate the design and con- struction of Sustainable Drain- age Systems (SuDS) in England drew a strong and mixed response when it was first announced last autumn. With the new regime due to begin in April, local authorities, develop- ers, contractors and water companies will need to get to grips with the new rules and how best to interpret them. The existing planning framework will now incorporate an 'expecta- tion' for SuDS to be used to manage surface water flood risk for develop- ments of ten properties or more. There will also be a requirement for developers to demonstrate how SuDS components will be effectively maintained throughout their life, avoiding the potential for schemes to be le„ neglected or rendered ineffec- tive through lack of regular care and inspection. Approval of SuDS designs will now be streamlined as part of the National Planning Policy Framework (NPPF), rather than having a separate approval route via Lead Local Flood Authorities, as originally set out in the Flood and Water Management Act in 2010. What impact will the new regu- lations have? Overall, the new rules could leave the Go with the Flow With SuDS systems set to be regulated through the planning system in England from april, the focus will be on quality of system design design and construction of SuDS more open to interpretation and more sub- ject to local priorities. But what might become a "postcode lottery" on the one hand, could also result in flood risk and water quality protection best suited to the local conditions. Remember, too, that the rules only apply to England; different regula- tions apply in Scotland, Wales and Northern Ireland. In Scotland, for example, there has historically been a much greater emphasis on achieving water quality objectives. It could be argued that Defra and DCLG, in bringing in the new regula- tions, drew a line under years of industry debate. The change should usher in a more sensible, "back to basics" approach for SuDS with prin- ciples that have been well established for many years. The new regulations for England only apply to new development, of course. To truly achieve comprehen- sive management of surface water quality and flood risk is going to require a concerted focus on retrofit- ting SuDS, but the drivers for retrofit SuDS are much less clear and far more complex. The good news is that the techni- cal and philosophical arguments for using SuDS have largely been won. So, the real question is not whether to incorporate SuDS, but what kind of SuDS to insist on. What makes a good SuDS scheme? There is also a growing acceptance that SuDS are not merely a pastoral vi- sion 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 principles. The principles of SuDS are first and foremost to mimic natural drainage paths and processes and deal with rainwater as close as possible to where it falls. As their name suggests, SuDS are a more sustainable ap- proach to surface water management that avoids costly and unsustainable transportation of surface water runoff into the local environment or through an overloaded sewer system. Good SuDS schemes satisfy both quantity and quality objectives and are likely to provide multiple benefits to the community by promoting local amen- ity and biodiversity. How do SuDS work? SuDS use a sequence of 'natural' and/or proprietary techniques to control surface water flow and limit Alex StepHenSon Group markET DEvElopmEnT DirEcTor hyDro inTErnaTional a SuDS system at Berewood housing development in Waterlooville, near portsmouth

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