Water & Wastewater Treatment Magazine
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Grid approach beats 'Beast from the East' Wessex Water's integrated supply grid proved its worth during the freeze-thaw event experienced this spring The Knowledge www.wwtonline.co.uk | WWT | AUGUST 2018 | 25 W essex Water's pio- neering water supply grid, which allows water to be moved around its region to areas of need, was key to keeping customers in supply when the 'Beast from the East' struck in March, reports from regulators have confirmed. Ofwat and the Drinking Water Inspectorate recently published two reports into water companies' response to the extremely cold weather ex- perienced in the spring, which saw burst pipes and interrup- tions to supply up and down the country. Approximately 200,000 customers nationally experienced a supply inter- ruption of four hours or longer during this time, and 60,000 customers saw an interruption lasting 12 hours or longer. However, Wessex Water was one company that avoided widespread disruption and the firm's new £228 million stra- tegic pipeline – which links up the north of its region with the south and hence provides greater resilience of supply – was credited in part with keeping the water flowing. "Wessex Water managed its operations without any loss of supplies to consumers despite the company's area being covered by the red weather warning issued for the south- west," said the DWI in its report on the severe weather. "The company attributes this to the robust preparations made in the period leading up to the start of the freeze, and its strategic supply net- work which allows water to be transferred across different parts of the company's area." Ofwat also praised Wes- sex's use of technology during the incident, which was used to identify leaks and bursts and complete repairs quickly. The centrepiece of the water supply grid, which took Wessex Water eight years to build and was completed last year, is a 74km transfer main running from Sturminster Marshall in Dorset to Camp Hill near Salisbury. By linking up the main networks for its whole region, the project enabled Wessex Water to boost its operational resilience by linking up many communities that were previously relying on a single source of water; Optimiser so˜ware means that flows along the transfer main are automated in both direc- tions. In the context of the freeze-thaw event, this meant that it was less likely that com- munities would be cut off from supply in the event of a mains burst because supply could be brought in from elsewhere while a repair to a burst was carried out. The grid approach can be seen as a prime example of the type of operational resilience which Ofwat wants water com- panies to build as part of its PR19 price review process. Ashlea Lane, Wessex Wa- ter's director of water supply, said: "While some people in the UK were without water during the freeze-thaw event, thankfully our careful plan- ning paid off and we were able to keep customers in supply. "There's no doubt that our newly-built water supply grid was key to being able to move water to areas that were affected most by the extreme conditions." Meanwhile, Thames, South- ern, Severn Trent and South East Water are each due to re- port to Ofwat in September on how they will avoid a repeat of the problems they experienced in the cold weather. GOAL 4 SUPPLY INTERRUPTIONS