40 n WATER INDUSTRY October 2023 www.drivesncontrols.com Motor upgrade helps to secure London’s water supplies Thames Water’s Ashford Common water treatment works in Surrey is one of Europe’s biggest water treatment works. With a maximum output of around 680 megalitres a day, it delivers about a third of London’s water supply, with the remaining supply being delivered by 20 or so smaller works. Inaugurated in 1953, the Ashford site underwent an extensive infrastructure upgrade in the 1990s, including the building of a pumping station. The pumping assets on site were therefore about 25 to 30 years old before the upgrade, and thus getting towards the end of their service lives. The vast plant has five Weir Group axial-flow pumps powered by 7.5-tonne motors, each capable of pumping about 180 megalitres of water. The stored water pumping station brings untreated river water from large storage reservoirs onto the site for treatment. When levels are low – for instance, during the drought in the summer of 2022 – four out of the five pumps are needed. If two of the pumps failed in a situation like this, the results could be catastrophic. Losing a single pump represents a 25% loss of output from the site and, because Ashford Common is so large, this is equivalent to the complete closure of two smaller treatment works. The network doesn’t have the resilience to take such a big hit. If two of the pumps failed, the result would be low pressure and loss of water – problems that the water industry hasn’t seen in decades. The pumps are therefore essential to maintaining the supply of water into London. Breakdown worries In 2018, equipment breakdown became a real concern. Two key issues were afflicting the motors. The first was overheating, which was causing their insulation to degrade. And although the bearings had been maintained, they were also coming to the end of their lives. Massive pump motors at one of Europe’s biggest water treatment works were starting to fail, threatening water supplies to London. Replacing the motors has safeguarded supplies, although Brexit complicated the delivery of the new machines. The new 600kW pump motor has solved the problem of motors failing at Thames Water’s Ashford Common water treatment works
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