Water & Wastewater Treatment

18 | NOVEMBER 2015 | WWT | www.wwtonline.co.uk Project focus: Pipes and pipelines improvement project. We're using a TBM because we need to link this new pipe into existing water pipes in Ditton and Snodland. As the area is so busy with traffic, we knew that closing various roads would cause an unacceptable level of traffic and community disruption which meant the only way round the problem was to drill under the motorway, river and railway line." The first crossing was completed in August, when the machine dug 24 hours a day, seven days a week, to create a one hundred metre tunnel 15 metres beneath the M20 motorway between New Hythe Business Park and Cobdown Sports Ground. The second tunnel, being dug at the time of writing in September, is deeper (20m) and longer (200m) and is set to take 20 days. "The machine is going through hard sandstone, at up to five revolutions per minute," says Love. "It will take out about 650 cubic metres of material, and ultimately all that material will be reused in filling the sha"s when the pipes come through. We'll put through each of the twin 600mm diameter pipes and then the gaps between the pipes will be pressure grouted. The excavated material is ground up and then mixed with water into a slurry, and the water is spun out of it by centrifugal action, enabling us to reuse the fine material." The earlier stage of the project, which saw the pipeline taken through Leybourne Lakes Country Park and Bushey Wood, involved painstaking environmental work to prepare for the pipe laying. Nightingales, water voles and newts were the species of concern; while doing the work in winter ensured nightingales were unaffected, the pipeline route had to have grass stripped and newt fencing installed to discourage the voles Crossing a stream within the park while keeping the watercourse flowing One of the tunnel sha s under construction Environmental preparations along the pipeline route included vegetation clearance ● A Victorian cast iron water main across Burham Marshes was bursting regularly and in need of replacement ● The new pipeline route needed to avoid the marshland so that it was easier to access when required ● Expanded capacity was required for expected population growth in the South East • Drivers

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