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Case

Water supply

Cross Solent Water Main

19. October 2015

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In 2005, Southern Water awarded National Oilwell Varco Denmark (NOV) an additional 4 km flexible AQFlex pipeline for transportation of drinking water to the Isle of Wight in UK. The original two parallel 8”ID flexible pipes, each 3900 m in length, were supplied and installed by NOV in 1980. After 25 years of operation, these lines have now reached the end of their intended operational life and need replacement. NOV’s AQFlex design is approved for drinking water by Drinking Water Inspectorate in London.

Over the next 25 years, Isle of Wight is expected to see an increase in water usage of 15%, and new pipelines are needed to meet that demand. Up to a quarter of the water is used by people living on the Isle of Wight for drinking, cooking, washing, and toilet flushing and the water comes from mainland Hampshire. There is not sufficient water on the Island itself to supply all of the 126,000 population and the extra visitors during summer. The water from the mainland is vital to top up the Island’s own resources predominantly coming from underground aquifers and the Eastern Yar.

The current Cross Solent Water Main supplies the Island with more than 25% of its drinking water. This water is taken from Testwood Lakes, near Southampton, where it is treated and disinfected before being pumped to the Island. The new pipelines, from Lepe in the New Forest to Gurnard on the Island, will take over this job, while the existing main will be left in position to be used as a back-up if necessary. The replacement line will be able to handle 70% more water - up to 20 million liters of water each day.

On both the mainland and Isle of Wight side, directional drilling technique has been used for drilling of two 56cm diameter tunnels in order to prolong to the fixed land pipe installation, keeping disruption to residents and the sensitive environment to a minimum. The NOV flexible pipelines are connected to the fixed piping by subsea connections at both sides of the Solent.