WET News

10 WET NEWS JUNE 2014 The roof of a new storage tank at Summerslade Down will be turfed to help it blend in to the countryside integrated grid "is a seed for what the rest of the country could do". He explains: "Through integration, maximis- ing existing assets and linking them together better you don't end up having to build new water treatment plants locally to deal with the need because you move water from other areas. You have that flexibility. "It's also a seed in the water industry about cooperating with other local water compa- nies. We have agreements with Sembcorp Bouremouth, for example, for reciprocal resil- ience arrangements where, by linking our systems together, if they need water we can provide it and vice versa. "There's water trading potential because legislation so far has had water companies concentrating on their own areas whereas going forward, and I'm a strong advocate through what we've managed here, it's best for customers if water companies cooperate more and share the water they have. "It's a very sustainable approach but it does need water companies to work together." The capital cost of the project may be similar to that of local solutions, says Modley, but "what you get with an integrated grid is a holistic approach, you get the flexibility. Even if you do build local treatment plants they could still go wrong and you're back to the same problem". The grid's engineering design, planning and environ- mental services are the respon- sibilities of WECS, Atkins and AECOM. The project contractors are WECS Civils, WECS ONSITE WATER SUPPLY GRID Mainlaying, Trant Engineering, AECOM, Lewis Civil Engineer- ing and Clancy Docwra. Modley has about £100M-worth of construction work that is currently in pro- gress, with 24 sites having now opened. He estimates that there is £1M-worth of construction a week for the next three years to deliver what needs to be delivered. "So the more good weather we have, the better." Historical heritage Before construction could start, the project was put through an Environmental Impact Assess- ment that reviewed potential impacts and concluded that most of these would be tempo- rary during construction and of negligible significance. Residual permanent impacts have been identified as being limited to minor adverse impacts on ecology, from wash- out discharges to watercourses, the historic environment and the landscape. The historical heritage found in Wessex Water's domain has led to targeted excavation taking place, cataloguing and careful routeing of the pipeline within a 50m planning corridor to accom- modate unforeseen areas of archaeological significance. A major find has been near West Knoyle, where a female skeleton dating back to the Iron Age was uncovered! Also, the scheme will benefit the River Whylye and Bourne as there will be reduced ground- water abstractions for public supply from its more sensitive upper reaches of the river catch- ment areas. Above: It is esitimated that there is £1M worth of construction a week to do over the next three years. Left: One of the project's pumping stations starts to take shape The transfer main will run from Corfe Mullen in the South up to Salisbury. Pumping stations and storage tanks are highlighted where needed SHARE YOUR OPINION... yoursaywn@fav-house.com • 24/7 Emergency Breakdown | Flood Dewatering Planned Maintenance • Bespoke and tailored Rental Solutions • We offer ATEX submersible pumps • We hire only our own Flygt and Godwin pumps • Full range of pipework and accessories available PLUS telemetry and monitoring equipment • Free site survey and system design • Same day installation available* Xylem Rental at Birkenburn Reservoir, Scotland SUBMERSIBLE AND DIESEL PUMP HIRE 24/7 RAPID RESPONSE NATIONWIDE AVAILABILITY DIRECT FROM THE MANUFACTURER FOR ULTIMATE PEACE OF MIND *subject to availability 0845 707 8012 rental@flygt.co.uk | www.xylemwatersolutions.com/uk flygt_godwin rental advert rev B_Layout 1 28/02/2014 17:08 Page 1 Construction of the new pipeline projects commenced in 2011. The pipeline material var- ies between polyethylene, duc- tile iron and steel and in diam- eters ranging from 200mm to 600mm. The new pipelines require more than 120 crossings. With the countryside in mind, the working width for the new pipelines is typically 20-25m with the trenches being 1.2m wide and 1.5m to 2m deep. Topsoil is being reinstated and the ground surface restored to its original condition once the pipe has been laid. Open-cut techniques are mostly being used, with trench- less technology being employed to overcome obstacles such as primary roads, railways and eco- logically valuable hedgerows. The route of the transfer main, providing the key link between the north and south of Wessex Water's region, has been strategically chosen to cover existing supply areas requiring additional resilience. The route was established in collaboration with local groups including landowners and other planning stakeholders. It was established to avoid environmentally sensitive areas wherever possible, such as Spe- cial Areas of Conservation, Sites of Specific Scientific Interest, Count Wildlife Sites and Sched- uled Ancient Monuments. Innovation is being applied as well. A new Optimiser con- trol systems has been devised for that will manage and opti- mise the transfer of water along the transfer main. it will be con- trolled centrally, scheduling transfers in the most efficient way while ensuring security of supply, minimising any risk of water quality issues and keep- ing energy costs to a minimum. Bi-directional links will maximise flexibility. This means there will be some flow rever- sals that result in a requirement to reduce the water pressure within the pipeline. There are plans to install energy recovery turbines within the pipeline with the power generated being used to offset power usage at the pumping stations. The water supply grid has been designed to allow the existing nitrate removal water treatment works and lower nitrate water supply sources to be fully utilised by the targeted blending of the available low nitrate water with sources at risk of exceeding the nitrate standard. This has been achieved through careful segregation or twinning of pipework to allow blending at critical points. Supply chain With the scale of the project being as huge as it is, ensuring the different elements of work is manageable has been vital. For instance, the 74km trunk main, with all its storage tanks and pumping stations, is worth £110M alone. "Breaking down projects into smaller schemes that are worth between £1M and £10M apiece makes them easier to manage through design, pro- curement and construction," says Modley. To ensure security of deliv- ery, Modley believes in having "strength and breadth" in the supply chain. "Not putting all the eggs in one basket ever. I make sure I've got several pipe- line contractors, I make sure I've got several consultants. I make sure I've got a stable of horses I can use for different courses. "If one goes over or one goes bust because these things hap- pen, there's still somebody to fall back on." Modley estimates that at least 500 people are working on the project at any one time. "I have a highly motivated team because as you can see it's a very exciting project. I'm one for having the best people in whatever I do. "I've been in the water industry 30 years and this is just a wonderful project because it is complex, it's diverse and at the end of the day you are bring- ing benefit." Winning over the local com- munities and interested parties has also played an important role in the project. As part of an agreed commu- nication strategy, an interactive website –www.wessexwater. co.uk/grid –was set up. The site contains animated footage showing the construction of a typical pipeline, storage tank and large as well as small pumping stations. The animations proved "very popular" at the pre-planning submission stage and the pre- construction public exhibitions. n

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