New Malden mean machine strengthens water pipes and cuts disruption

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Thames Water has significantly reduced the time and disruption it traditionally takes to replace and strengthen old Victorian pipes using a cutting edge technique.

A powerful pipe pushing machine imported from Holland has inserted stronger plastic pipes inside the existing cast iron water mains as part of a £7 million replacement scheme in New Malden.

The new pipes will strengthen the network and reduce the risks of disruptive bursts for future generations on three large trunk mains – the biggest being four-foot wide – which supply water to 82,000 customers in south west London.

Traditionally, the job would have required 10 separate work sites. However, the monster machine is able to push the new pipes through the old ones along a 1,100 metre section from just one site to minimise disruption to customers in the area.

Thames Water project lead Mike Dick said: “This is a highly effective method of replacing some of our oldest pipes, which were laid more than 100 years ago, while also reducing the impact it has on customers.

“We’re very conscious that our work to improve the network can often have highly disruptive implications so using this machine is a win-win situation.”

Engineers weld 12-metre long sections of the pipe together as part of the relining process before the machine pushes them through 12 metres at a time. This takes just 15 seconds.

It means the pipe can be fully inserted in 12 days, although the project will take longer to complete due to testing, road surface reinstatement and installing valves and connections.

Although this particular machine has only been used on this project, the majority of pipe replacement work carried out by Thames Water uses the technique of inserting new plastic pipes inside old Victorian pipes, a process known as slip-lining.