WET News

JANUARY 2015 WET NEWS 7 Should sewerage undertakers adopt SuDS? • Recent consultation has again offered sewerage undertakers the opportunity to stake their claim to the role, as an alternative to the Lead Local Flood Authority (LLFA). William Savage explains. T he recent Defra / DCLG consultation on delivering sustainable drainage has raised further questions over the likely mechanisms for delivering SuDS. As the fundamental princi- ples of the process are still in abeyance, the industry as a whole is le• asking the same questions regarding adoption and maintenance, to safeguard the benefits that SuDS can undoubtedly bring. Ideally, SuDS should be inte- grated within a design to offer a wide-range of benefits, and to date design guidance has been sought from a variety of sources most notably CIRIA, which pro- motes the use of above-ground features such as swales, ponds and basins. Whilst there continue to be reports of the long-awaited National Standards, the level of detail to be included within them is likely to be low. Hydraulic modelling Were the Lead Local Flood Authority (LLFA) role to be reduced and the sewerage undertaker become responsible for providing pre-application advice as a statutory consultee, the opinions of a range of disci- plines would be necessary to maximise the potential benefit. The traditional hydraulic modelling skills would have to be aligned with that of the land- scape architect, the ecologist and the urban designer. An inclusive communication strategy would be required to safeguard the whole range of benefits on offer, not just those associated with flood protection. The individual preferences of sewerage undertakers could generate conflict between the multiple local authorities they serve, potentially leading to a localised approach to design standards which should be avoided. Like all infrastructure works, for SuDS to be effective they must be carefully constructed – poorly installed SuDS will always require additional main- tenance long-term. In this instance, support from the sewerage undertaker would be welcome, as an inspection regime could be devised based on the current model used within traditional S104 agreements. Private management There is no doubt that an effec- tive SuDS-based solution to sur- face water management can lead to a significant reduction in the quantity of surface water runoff entering the public sewer sys- tem, provided the design and installation is correct. The recent consultation makes reference to a range of parties with the potential to maintain Sustainable Urban Drainage Systems, including pri- vate management companies. Concerns have been raised previously over the long-term stability of some private mainte- nance organisations, together with their perceived value for money, particularly amongst home owners already living within developments built around SuDS. During previous consulta- tions the idea that the Lead Local Flood Authority would maintain such systems seemed to be the obvious solution, particularly as the skills likely to be required would be wide- ranging including landscape maintenance. Should the sewerage under- taker become responsible for this role, is it reasonable to expect that these skills will be available? In order for systems to be effectively maintained, there is surely a risk that design stand- ards may steer towards more tra- ditional pipe-based solutions, which can only address part of the issue. Scenario Were the sewerage undertaker to adopt and maintain SuDS, the potential benefits to surface water management within their operation as a whole would need to offset the additional maintenance costs. The increased use of infiltra- tion, above-ground attenuation, filtration etc that could be pro- vided through appropriate SuDS can clearly offer benefits to a sewerage undertaker by remov- ing a significant volume of run- off from the system, and it would seem only fair that this be achieved without any increase to the bill payer. This scenario would seem to be the quickest to implement, as a baseline for the administration already exists, with the added benefit of long-term financial stability. The need to manage and reduce flood risk in the UK will remain on the political agenda, fuelled by the increased media coverage of severe flooding events over the past few years. The quantity of runoff generated during storm events can be "The need to manage and reduce flood risk in the UK will remain on the political agenda, fuelled by the increased media coverage of severe flooding events over the past few years. " News+ effectively controlled using most SuDS solutions, including those more heavily-engineered sys- tems traditionally associated with the sewerage industry, and there is no doubt that such sys- tems could quickly be delivered with suitable adoption agree- ments in place. Potential It is vital however that should there be a rush to score a politi- cal quick-win, the true potential of SuDS should not be lost. The less obvious benefits associated with biodiversity, water quality, public amenity and increased green space must be an integral part of the deliv- ery, which may require a consid- erable change in policy for some sewerage undertakers. n William Savage is associate for consultant Pick Everard. www.pickeverard.co.uk Support from the sewerage undertaker would be welcome, as an inspection regime could be devised based on the current model used within traditional S104 agreements

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