Islanders Receive a Long Drinking Water Pipeline

Hamburg orders a new drinking water pipeline which will be laid across 9 kilometres of tidal mudflats by the company Christoffers.

This mud trencher is named "Nessie III". It will bury the polyethylene water pipe 4 metres into the mud. The pipe will be subjected to a pressure test to make sure there is no damage. Jörg Fischer (small photo) manages the project for the Hamburg Port Authority.

On Wednesday the works have begun in the mudflats near Sahlenburg to lay a new drinking water pipeline to the island of Neuwerk. A special trencher will bury the 9-kilometre long polyethylene water pipe 4 metres deep into the mud, all in a single operation. This way the disturbance in the ecosystem in the tidal mudflats will be minimal. The job should be done by next Tuesday.

By Thomas Sassen, Cuxhavener Nachrichten

27 May 2010, CUXHAVEN/NEUWERK -  The upkeep of an inhabited island in the tidal mudflats is expensive, as the Hamburg authorities have found out once again. The 9-kilometre long pipeline which will cost almost one million Euros will be laid between the island of Neuwerk and Sahlenburg in the next few days. Large quantities of drinking water had been seeping into the soil recently from the clearly faulty, old pipeline.

'Nessie III' is the name of the 85-tonne mud trencher which will bury a new polyethylene water pipe 4 metres deep into the ground. The machine, which is just two years old, was designed by the company Christoffers from Wiefelstede / Conneforde especially for deployment in the nature reserves in the North Sea mudflats. It was first brought into action in 2008 to bury a new electrical cable for the offshore oil rig 'Mittelplate'. 'Nessie III' and its 'escort' carrying a drum loaded with the water pipe are effective and environmentally friendly, explained the Managing Director, Michael Jäger. In a single procedure the trencher digs a narrow trench and simultaneously buries the 14-centimetre thick blue water pipe.  Afterward, the soil falls back into the trench and is immediately compacted.

In optimal conditions, the convoy manages to cover 1200 metres an hour. Jäger and his colleague Tammo Christoffers calculate that the 9-kilometre long water pipe to Neuwerk will take about a week to lay. "By Tuesday next week we should be done," said Christoffers.

The project in the mudflats started on Wednesday. The works proceed only during low tide. The advantage of "Nessie III" is the ability of the tracked vehicle to remain in the mudflats during high tide which saves driving back and forth to shore. This is possible because of a built-in lifting mechanism which can elevate the cockpit with the driving unit up to 8 metres above the ground. "It is also sufficient to drive through the water channels in the mudflats", confirmed Michael Jäger.

To avoid having to excavate the dikes at Sahlenburg and Neuwerk, the project team decided to deploy a horizontal directional drilling method in which the polyethylene water pipe is pressed through the soil underneath the shore structures. The connections will be made later in shafts. At the midway point in the mudflats, another shaft will be excavated in which the two 4.5 kilometre long water pipes will be connected into one continuous pipeline. When the project is completed, the 20 households on the island of Neuwerk will be supplied with drinking water from the EWE water supply network.  The island has a waterworks for distribution as well as a sewage water treatment plant. Until 2009 the water the islanders received came from a well that belonged to the former Nordheim Foundation. The new plastic water pipe manufactured by Rehau from Brake is made of crack-resistant PE 100-RC and should last for at least the next 100 years without any damage.

Photo: Tammo Christoffers and Michael Jäger
With special equipment in an interesting market: the Managing Directors Tammo Christoffers and Michael Jäger from Christoffers Onshore and Subsea GmbH.