“We acknowledge Visser & Smit Hanab’s valued contribution to the scheme,” Barry Gosden, programme delivery manager, 4Delivery
In the spring of 2008 Visser & Smit Hanab, sister company of VBMS, completed the second and final phase of a £15m project to replace a pair of pipelines supplying water to the Isle of Wight, off England’s south coast.
Around 12 million litres of water are pumped to the island every day, drawn from Southern Water’s treatment works in Southampton. But the pipelines installed back in the 1980s were never going to be big enough to cope with the 15 per cent rise in water consumption predicted over the next 25 years. Demand for water from the mainland on the island is expected to increase over the coming years, partly because of population growth, and partly because the amount collected on the island will fall due to climate change. Since the two 200mm diameter pipes were installed, the island’s population has increased by almost a fifth, while beach tourism continues to create a summer spike in demand, just when the availability of water is at its lowest. A new pair of 300mm diameter pipes - stretching across a 2km-wide section of the Solent between Lepe in Hampshire and Gurnard on the Isle of Wight - would increase the maximum amount that could be pumped by 70 per cent, to 20m litres a day. VSH, together with VBMS, became a subcontractor on the project in the summer of 2006. The main aim of the first phase was to establish the shoreline sections of the pipeline. The bulk of this work was finished in early 2007 (see Cross Solent Main (Phase 1)), allowing the team to focus on phase two, which involved laying two 2km-long mid-sections of pipeline underneath the bed of the Solent.
“The period from August 2007 to March 2008 was spent preparing and fine-tuning our ideas and procedures on how to bury the pipes,” says VSH project manager, Eric van der Poel, who worked on the solution together with engineers at VSH’s headquarters in Papendrecht, the Netherlands.
“The biggest part of the job was designing a burial tool we called the ‘Hornblower’. We were not allowed to dredge in the Solent because of possible damage to the natural environment,” says van der Poel. “This tool consisted of a sledge with a water jet device to blast through the sea bed.”
Satisfied that the new device was ready, a transport barge was sent from Rotterdam to Peterhead, in the north east of Scotland, and thence to Kalundborg to pick up the two enormous submersible pipelines.
“We reeled them in and found that this enormous garden hose had a mind of its own, buckling with the slightest force.” The unwieldy pipe was soon brought under control however, and wound onto two 10m-diameter reels which were then shipped to the Solent.
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