Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | March 2015 | 19 S peakers at WWT's inaugural Water Scotland 2012 conference, held in Edinburgh on 3 October, gave differing perspectives on how Scotland. He said that Scotland needed to be alert to the "water dependent indus Sustainability David Pirie, director of science and strategy for the Scottish Environmen For further reading on this topic please go to www.Nis inihit volorum quibere rspiducid ente si qui volorem ut modit eaque aut maximax iminciusto. Project focus S ustainable urban drainage (SuDS) is rising up the agenda for water companies in this AMP cycle, as a cost-effective, environ- mentally friendly way of reducing pressure on combined sewer networks. But SuDS solutions on a significant scale – especially when retrofitted in existing urban centres - require effective co-operation between a host of stakeholders, including local authorities, developers and regulators, as well as the water utilities. Can this be achieved? One example that suggests that Sustainable drainage RainScape: Putting it all together Project focus ● Dŵr Cymru Welsh Water installs integrated, large scale SuDS solution in Llanelli ● Sustainable drainage retrofitted in densely popu- lated urban area ● Memorandum of Understanding agreed with key stakeholders for new development ● A large amount of storm water in the Llanelli com- bined sewer network was leading to CSO discharges in shellfish waters in the Loughor Estuary. Some low-lying properties were also at risk of sewer flood- ing ● An engineering solution involving storm tanks would have been impracti- cal and expensive, requir- ing massive infrastruc- ture, and may not have been effective ● A sustainable solution was required to protect Welsh Water customers against flood risk in the longer term given the threat of climate change • Drivers serves 53,000 people, has nearly as much storm water in its network as Swansea, which has three times the population. With nearly 40 low-lying houses vulnerable to sewage flooding, and shellfish waters in the Loughor Estuary at risk from CSO discharges and diffuse pollution, Welsh Water de- cided to focus on an integrated SuDS solution for the area back in 2010/11. "The standard approach to the problem would have been to build big storage tanks, combined with increased pump capacity," explains Fergus O'Brien, RainScape Strategy Manager at Dŵr Cymru Welsh Water. "But when we looked at that we real- ised the amount of storage we would have needed in this area was enor- mous - over 200,000 cubic metres of storm tanks in Llanelli WWTW alone - and even then, the tanks would never drain before the next storm came along and filled them up again. So technically it was never feasible to take that approach. "We were already adopting a sus- tainable drainage approach for some small, localised schemes at the time to protect customers from flooding. So we decide to extend our analysis and modelling across the whole of Llanelli and Gowerton, and ask - what would you have to do in order to deliver a fully sustainable approach?" Aœer studying international exam- ples – such as Malmo in Sweden and Portland, USA – O'Brien knew that retrofitting SuDS was possible despite Stebonheath Primary School in Llanelli. Schoolchildren helped with the design of the green areas in their playground, helping local engagement with RainScape it can is Dŵr Cymru Welsh Water's RainScape initiative, which has made £15M of improvements in Llanelli and Gowerton during AMP5, and will be expanded to the tune of another £25M in AMP6. The Llanelli schemes are the centrepiece of a sustainable drainage programme which will see around £60M spent on SuDS across Wales in the 2015-20 period. As a sloped, coastal town with tra- ditional terraced houses and few gar- dens and green spaces, Llanelli is a particular hotspot for surface run-off: its combined sewer network, which JAmES BrOCkEtt EDITOR, WaTEr & WaSTEWaTEr TrEaTMENT

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