Water & Wastewater Treatment

14 WWT PUMP AND VALVE SUPPLEMENT 2018 Case Study site, assess problems and offer a proposal for upgrading and enhancing equipment. Immediate problems The crucial challenge for the valvolo- gists was in coming up with a solution that was sympathetic not only to the environment but also with respect to the conservation and beauty of the dam, since the fascia of the valve chamber and the Victorian-built bridge below it were listed. The combination of ageing gate valves used for isolation and flow control wasn't an ideal set-up, as gate valves are not for dedicated flow control. Using only gate valves for flow control can lead to turbulence and inaccurate discharge capacity, which can further cavitate the entire piping and valve arrangement. As a result, the discharge system could fail if not upgraded with the right selection and combination of valves. A•er considering all the challenges, external factors and various technical aspects, Blackhall offered Welsh Water a technical proposal that would not only boost the discharge capacity but also increase the degree of control that Caban Coch would have on each of the four discharge lines. The recommendation, which is set to keep Caban Coch's discharge mechanism in top condition for at least another 100 years, was to use a dedicated flow control valve, with a fixed cone valve (downstream) and a gate valve (up- stream) for isolation. It included the design and manufacture of four DN600 fixed cone flow control valves and four DN600 isolation gate valves. The proposal comprised a detailed 3D structural drawing that showed Welsh Water how the valves would be arranged in the chamber in a way that would comply with all the spacing and safety standards. A key consideration was that the discharge footprint had to be designed in such a way that its dispersal pattern wouldn't hit and damage the surround- ing Victorian architecture, including the bridge at the base of the dam. This was accomplished by fine-tuning the hoods and the inclination angles to guide jets into the safe zone of the stilling basin by achieving the perfect angle of incidence. The valves were also painted in Welsh slate grey and emblazoned with a Welsh Dragon, in keeping with Caban Coch's natural and historical setting. 100-year asset life valves The performance of each valve is crucial for the safety of the surrounding environment – with such large volumes of water at stake, there is huge potential for catastrophic damage, but higher quality valves means decreased chance of failure and consequent environmental impact. Blackhall is leading the initiative in creating 100-year asset life valves. By prioritising quality in design and materials, these valves not only reduce environmental risk but provide Totex benefits: the cumulative costs associated with continuously repairing and replacing cheaper alternatives end up far exceeding the cost of the 100-year valve. The company also utilises a local supply chain. Taking all aspects of manufacturing and transporting new and o•en foreign valves manufactured in East Asia into account, the carbon footprint can be significantly higher than Blackhall's valves. Welsh Water, which has targeted a reduction in its carbon footprint by 2020, has ensured the upgrade not only places an emphasis on the Elan Valley's environment and wildlife but respect- fully preserves its Victorian architecture.

• Cover