Water & Wastewater Treatment Magazine
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www.wwtonline.co.uk | WWT | AUGUST 2016 | 19 Project focus Pipes and pipelines Pipeline boosts resilience for Dee Valley Water Project focus D ee Valley Water is progressing well with a £14M pipeline project which will boost resilience of supply and tackle incidents of discoloured water experienced by customers. The discoloured water issue is the result of naturally-occurring manganese in the raw water passing through the water-only company's Legacy Water Treatment Works on the outskirts of Wrexham. Over time, manganese deposits can build up in the pipe network, causing discolouration when eventually ● 8.5km pipeline connects supply areas south of Wrexham ● Legacy Treatment Works to be decommissioned to end manganese discolouration ● Water company uses in-house design and build expertise be made to Boughton Treatment Works and to neighbouring water companies, boosting resilience by allowing greater transfers of water within the system and bulk imports when required. "In our review of our business plan last year, we focused on outcomes and Totex in line with the new Ofwat regulatory model, and it led us to challenge whether we really should be rebuilding Legacy Treatment Works," says Oliver Twydell, Head of Quality and Environment at Dee Valley Water. "The estimate for rebuilding Legacy was £17M, but looking at our existing treatment works, we realised that we actually had enough resources not to need Legacy: all we had was the age-old problem in the water industry of how you get the water where it needs to be. So we costed out some network solutions, and when we saw that we could achieve our goals with a £14M project, that's when we really started focusing in on this as the right solution." Project challenges In addition to the new trunk main, which will be made of 600mm ductile iron, the project also involves increasing the size of the storage reservoir at Llwyn Onn from 18ML to 24ML, the construction of one new pumping station and the installation of additional pumps at another. The pipeline's route is largely across agricultural land and it will be laid using an open trench method, but directional drilling will be required dislodged. Dee Valley Water had originally planned to rebuild the treatment works to put in additional manganese treatment, but later came up with a new plan which it says is a more outcome-based, resilient and cost-efficient solution. The new project involves the building of an 8.5km new trunk main which can take high quality water from Llwyn Onn Treatment Works – where manganese treatment using catalysis was installed in 2013 - and put it into the network around the Legacy works. Connections will also L-R: Oliver Twydell (Head of Quality & Environment), Stuart Owen (Construction Manager), Susan Elan Jones MP, Ian Lucas MP, Lesley Griffiths AM and Ian Plenderleith (CEO, Dee Valley Water). ● Dee Valley Water had 4.9 discolouration complaints per 1000 customers in 2013, due to manganese in its water sources. It has now reduced this to 1.32 and the completion of this project should allow it to hit its ODI target of 1.01 per 1000 ● Decommissioning Legacy WTW and making more use of Llwyn Onn WTW and Boughton WTW was a smarter Totex solution, saving £7.5M over 40 years ● Linking up the different supply areas within the region boosts the transferability of water and therefore the resilience of supply for customers • Drivers JaMes BrOCkeTT EDItOr WATER & WASTEWATER TREATMENT