WET News

8 WET NEWS JUNE 2014 Wessex Water gets to work on its biggest project so far The 74km transfer main is a key component of the water supply grid project. The route has been established in close liaison with local groups PROJECT SPECS • Establish a water supply grid by 2018 • Construct 200km of new pipelines • Construct 24 new or refurbished pumping stations • Construct 12 new storage tanks • Wessex Water is creating a water supply grid in order to meet supply demand for the next 25 years. The £225M project will take eight years to complete. Maureen Gaines has been seeing how work is progressing. W essex Water is in the process of delivering the biggest and most complex project it has ever done – establishing a water supply grid. The £225M, eight- year project involves the con- struction of more than 200km of new pipelines, 24 new or refur- bished pumping stations and 12 new storage tanks ranging from two to eight million litres. In fact, the ambitious scheme incorporates more than 50 individual projects, and a key component is a 74km trans- fer main from Sturminster Mar- shall, Dorset, to Camp Hill just west of Salisbury in Wiltshire. Add to the mix the fact that around 50% of Wessex Water's region is classed as an area of outstanding natural beauty and you wonder how the scheme will blend into the stunning countryside. It does. The whole region is also "rich with archaeology". The water supply grid is Wessex Water's answer to meet- ing future demand and ensur- ing security of supply to cus- tomers. It currently supplies about 350Ml of potable water a year, on average, with a patch covering 7,500km 2 including Dorset, Somerset, Wiltshire as well as parts of Gloucestershire and Hampshire. The grid will enable Wessex Water to move water from areas of surplus to where it is needed to improve resilience to drought and unforeseen events. The scheme maximises the existing assets that the com- pany have, says Drummond Modley, who, as grid pro- gramme manager, is the man tasked with overseeing the project. Modley works for Wessex Water's in-house construction and engineering arm WECS, which is managing the overall delivery project. He says the scheme provides "a backbone that integrates our existing infrastructure, which is very important. "It means we can move water from where we have it in abundance – from Dorset, for instance, where we have an unconfined aquifer, north to where we have areas of pre- dicted deficit going forward". When all the work is done customers will not have to rely on one source of water, he adds. "If something goes wrong with their local source, invariably a borehole [75% of Wessex's water is from boreholes], water will come from a different direc- tion. As we deliver these pro- jects and certainly by 2018, cus- tomers will be able to turn the tap on and water will come out of it, where in the past bottled water would have been supplied." By the end of 2017, Wessex Water's customers will have supply 365 days a year, empha- sises Modley. 'Seed' Modley says the fact that the project is being developed as an TECHKNOW • A new Optimiser control system has been developed to manage and optimise the transfer of water along the new 74km transfer main • Volumes of the new storage tanks along the transfer main have been minimised by dedicating them as transfer storage • The supply grid has been designed to allow existing nitrate removal water treatment works and low nitrate water supply sources to be fully utilised • Pipeline material varies between polyethylene, ductile iron and steel, with diameters ranging from 200mm to 600mm • Open cut techniques have been used, with directional drilling or auger boring where a tunnel or passage is required THE VERDICT • The project is complex and diverse, and the largest ever undertaken by Wessex Water • The grid will enable Wessex Water to re-distribute surplus water to where it is needed across its region • The grid will provide much more flexibility for future water resilience ONSITE WATER SUPPLY GRID Drummond Modley says the scheme is 'a wonderful project'

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