WET News

Caption if needed sdkvjb sdkvjnsdlk dvsdvdvsdvsdvsdv dv skjbdv lskdjvbsdkljvbsdkv A mid urban creep and the expectation of more extreme rainfall events, Welsh Water has turned its atten- tions to nature-based solutions. At the 2018 Water Industry Awards on 21 May, the company and its project partners were rewarded as the sustainable drainage-focused RainScape and Greener Grangetown schemes were named Drainage & Flood Prevention Initiative of the Year and Engineering Project of the Year respectively. The judges described Rain- Scape, which has retro‡ tted sustainable drainage and sur- face water separation features into the urban environment of Llanelli, as "an example for oth- ers to follow"; Greener Grange- town Water Sensitive Urban Design, a retro‡ t SuDS scheme in central Cardi' , was hailed as a "breath of fresh air". The judges said the "results being achieved in areas where others are struggling to deliver are remarkable". The situation in Llanelli, Car- marthenshire, had been particu- larly pressing. The area was see- ing almost as much stormwater in its network as neighbouring Swansea, despite the fact Swan- sea serves three times the num- ber of properties. Some of its combined sewer over" ows were operating over 100 times a year, with 115 properties deemed to be at risk of sewer " ooding. The standard approach would have been to build large storage tanks and increase pump capac- ity, but the scale of the problem was prohibitive: it would have required over 200,000 cubic metres of storm tanks for Llanelli Wastewater Treatment Works alone. For an area with a popula- tion of 35,000, the estimated cost of the works using traditional methods stood at around £600 million. Welsh Water is not alone in having to look beyond traditional tactics – Ofwat's climate change policy notes that the principle that "sewerage systems should accom- modate future " ows is unsustaina- ble in the long-term" – but it is making very impressive strides in putting them into action. The company had already seen success with some small, localised SuDS schemes but, when assessing how to deliver a fully sustainable approach to Lla- nelli, it found inspiration from Malmo, Sweden, and Portland, Oregon, where an emphasis on large-scale nature-based solu- tions was showing it was possible to not only deliver practical results at a substantially reduced cost but to make the area more eco-friendly and attractive. As Welsh Water's wastewater strat- egy manager, Fergus O'Brien, said last year: "We realised water doesn't have to be a problem but can be made a feature of the environment." Welsh Water chief operating oŸ cer Peter Perry told the World Water-Tech Innovation Summit recently that the dual challenge of a growing population and an increasingly volatile climate means we are in "uncharted terri- tory", adding: "What we've done in the past just isn't going to be good enough. It's going to need a combination of a lot of small schemes and the odd big oppor- tunity to engineer our way out." RainScape encapsulates that approach perfectly: a combina- tion of green, blue and grey. The ONSITE SUSTAINABLE DRAINAGE 12 WET NEWS JUNE 2018 | wwtonline.co.uk Welsh Water Capital Delivery Alli- ance has overseen the installation of shallow, vegetated channels known as swales; basins and planters, which capture surface water runo' from roofs and roads; porous paving; ‡ lter strips; grass channels; and geocellular systems, which can be installed beneath roads and kerbs to help reduce the speed at which surface water enters the sewer network. New gravity surface water sewers have been connected to existing rivers or new green infrastruc- ture, while existing assets are being brought back into service and improved. The largest individual part of the project, though, is a new 1.5m diameter tunnel through central Llanelli that is due to be completed this autumn. At a cost of £13 mil- lion, the new trunk sewer known as 'The Spine' required six years' design and planning before work began in early 2017. It includes eight 6m diameter sha¤ s 11m deep and an 11m diameter terminal pumping station rated to li¤ 3,300 litres per second. "It's almost like an extra water course because every water course in Llanelli is full," O'Brien said. RainScape has already seen more than 42 hectares of surface water separated from the foul sewer within Llanelli and reduced peak " ow in the sewer by 6,000 litres per second, ensuring 1.5 mil- lion cubic metres of clean rainwater is no longer pumped and can be stored and reused or diverted to green spaces, rivers and streams. Flood risk resilience has been improved to greater than one-in-30- year protection across Llanelli. Greener Grangetown, mean- while, had di' erent objectives. As Ian Titherington, lead oŸ cer at SuDS features in the Grangetown area of Cardi„ Sustainable success ¦ Welsh Water and its project partners soaked up the acclaim at the Water Industry Awards as the SuDS-focused RainScape and Greener Grangetown schemes both picked up prizes Before and after the Grangetown improvements

• Cover