Water & Wastewater Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/1016624
12 | SEPTEMBER 2018 | WWT | www.wwtonline.co.uk • SUDS BACKGROUND • Sustainable drainage systems (SuDS) hold back surface water in urban areas in a way that mimics the processes of land and vegetation in nature. They can include both constructed elements (e.g. permeable paving, channels and gullies) and vegetative elements (e.g. swales, ponds). While most associated with preventing sewer flooding, SuDS can actually fulfil four functions: improving water quantity, water quality, amenity and biodiversity. • Following the devastating flood events of 2007, the Government- commissioned Pitt Review made more than 90 recommendations for improved flood risk management and implementation of SuDS in the UK. Some of the Review's recommendations were embodied in the 2010 Flood and Water Management Act, although not all parts of the Act have subsequently been implemented. • In England, SuDS implementation has been governed via the planning system since April 2015. The National Planning Policy Framework (NPPF) includes an expectation for SuDS to be used to manage surface water flood risk, but only for major developments or housing schemes with 10 properties or more and only if they are 'not demonstrated to be inappropriate'. • In Wales, the Welsh Government has stated its intention to make SuDS mandatory on all new developments, with approvals managed via separate local authority SuDS Approving Bodies (SABs). In Scotland, SuDS is already effectively mandatory under the Water Environment (Controlled Activities) Regulations 2011; in Northern Ireland it is Government policy to encourage SuDS 'where possible' although currently only a small percentage of developments use it. • Developers and property owners are ultimately responsible for implementing SuDS on private land, while local authorities, water companies or NGOs can play an important role by funding and implementing retrofit SuDS projects on public land and highways. • Water companies can be asked to take ownership of (adopt) surface water assets that meet suitable standards under Section 104 of the Water Industry Act 1991 via a document called Sewers for Adoption. Until recently, most SuDS did not fall under the definitions included in the document. However, Water UK has recently published of the eighth edition of Sewers for Adoption which clarifies the conditions under which water companies can adopt sustainable drainage schemes. The Works: sustainable drainage • NEW DEVELOPMENTS AND PLANNING T he standard of implementation for new-build SuDS in England through the planning system since 2015 has been "very patchy through the country" according to Paul Shaffer, Associate (Water Management) at construction standards association CIRIA. "The areas that have good SuDS outcomes are those with strong local planning policy resources and staff looking at the quality of the SuDS schemes that are coming through," says Shaffer. "What you see is an over- emphasis on flood risk at the neglect of some of the other benefits of SuDS. A lot of the time you will get a system that delivers benefits with regard to flood risk – such as a pipe leading to a pond – but that doesn't necessarily mean to say that it's a great scheme: it might be quite difficult to maintain, quite unattractive and doesn't really contribute to the quality of that space." Retrofit projects, which are usually led by local authorities, water companies or partnerships involving the two, tend to achieve a higher quality, says Shaffer. This implies that greater water company involvement with new SuDS, both at the planning stage and in adopting the schemes created, might be one way of raising the standard. So will Sewers for Adoption 8 will be the spur for making this happen? "Water companies have been quite constrained by their definition of what they can adopt, in terms of whether it conforms to a sewer or not," says Shaffer. "For the most part they haven't really been forward-thinking in terms of their adoption of SuDS until now. Even with Sewers for Adoption 8 coming through, it's still uncertain how many sewerage undertakers will be adopting SuDS – because it's not mandatory, it's something they are supposed to consider. So while SfA8 is a step in the right direction, whether it's a step change or just a A rain garden at Cheeseman's Terrace, London (a Thames Water/Life+/Groundwork project) stumble along the path that SuDS has been taking for the last five or ten years, I don't really know." Ofwat still needs to give its approval to SfA8, and water companies will need reassurance from the regulator that they will be able to reclaim the maintenance costs for assets that they adopt under the code through customer bills. And while SfA8 widens the definition of a sewer to include surface water drains and channels, it is worth noting that SuDS features such as permeable paving, green roofs and bioretention strips will still not be included in this.