Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | Decmber 2014 | 15 A specialised trencher was used to speed the pipelaying rate T he completion of a 19km pipeline, transferring potable water between two Thames Water Berkshire catchments, has not only safeguarded the new EA reduced raw water abstraction licence, but will also assist the survival of a rare snail. Cold Ash Reservoir near Newbury is the major supply source of potable water to some 35,000 local households. This covered reservoir receives its main treated water from Speen WTW, 8km to the south west, via a 200mm diameter pipeline pumping in up to 5ML/day. Built in the 1960s, Speen also supplies several other smaller reservoirs, but Cold Ash takes 90 per cent of the water that the treatment works abstracts from five nearby boreholes, including the River Kennet. This routing works well and would have needed no technical changes were it not a requirement for water companies to look at ways to reduce borehole abstraction across their water networks. The Environment Agency has ordered a reduction in the current 13.6ML/day raw water abstraction licence at Speen, as part of a nationwide programme, and abstraction rates were to be lowered to an average 4ML/day and maximum 5 ML/day. The new restriction still allows Pipes and pipelines Transfer main reduces borehole abstraction at Speen WTW Project focus ● New 19km potable water pipeline ● Project safeguards new eA reduced water abstraction licence ● chosen route protects a rare snail species Justin seely ThAmes VAlley ProgrAmme DeliVery mANAger, oPTimise ● A reduction in thames Water's abstraction licence from raw water supply boreholes was the driver for the pipeline which transfers potable supplies from tilehurst Reservoir in Reading to Cold Ash Reservoir near newbury. ● Increasing flow into Cold Ash by up to 5Ml/day will allow its former main supply source from speen water treatment works to be shut down. ● speen will considerably reduce its raw water abstraction rates from local boreholes, located in the grass-covered wetland floodplain of rivers, where one of the world's rarest snails, Desmoulin's Whorl, has one of its main european homes. ● several rivers, the M4 motorway, attractive Berkshire villages and even contaminated land complicated the design challenge; while known habitats of badgers, great crested newts, Japanese knotweed and bats added to the no-go areas. • Drivers A riddler bucket was used to grind the excavated material for replacement bedding

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