Master the ground pressure even at 7.5 meters depth

Extra-long sheet pile walls from Euro Verbau enable complex relocation of stream course

"When you stand down there, you only notice how deep it actually is," says Andreas Iks. On several occasions, the foreman from construction and civil engineering company Müller & Bleckmann and his colleagues dug out a 7.5-meter-deep shaft to lay huge concrete pipes with an inside diameter of 2 meters. The individual pipe segments are 2.5 meters long and weigh about 11.5 tons.

In the 10-meter-long construction pit, the sheet piles are built into the sheet pile chambers. Dez guides in the chambers ensure the correct overlap of the profiles. Photo: ZIKOMM / Thomas Masuch

The concrete pipes are being laid in the Neviges district of the German town of Velbert, in the state of North Rhine-Westphalia. From the end of 2020, the Motschenbrucher Brook will flow through these pipes and return to its original bed. For years, the brook's water was mixed with sewage and discharged to a wastewater treatment plant in Essen. From the end of 2020, the stream's water will once again meander through its natural bed at 400 meters, slowed down by natural rock and fringed by shrubs, ferns and trees. This idyllic picture is part of the renaturation plan, but is currently disturbed by a road, the Am Rosenhügel, and by several access roads that traverse the old course of the stream. The course of the stream will be routed over a length of about 70 meters through new concrete pipes, which will be constructed to a depth of 7 meters below the road. A total of 1.25 million euros has been estimated for this construction measure.

At 7.5 meters below ground level, the sheet piling reverses the tons of pressure Photo: Müller & Bleckmann

"Nietal challenge"

"And the depth is an uncommon challenge in this regard," says Ingo Schachtschneider, managing director of Müller & Bleckmann of Heiligenhaus. This applies not only to the placement of the tonne-heavy tube segments, which requires the use of a truck crane each time. "Down there you can feel the pressure of the ground, which is several tons," he says. To find a solution for these challenges in the Nevige soil, Schachtschneider coordinated in advance with Martin Echelmeyer, Sales Manager Rhineland at Euro Verbau GmbH. "In doing so, we came to the conclusion that the deep shafts could best be supported with sheet pile walls 8.5 meters long and 60 centimeters wide," says Echelmeyer.

In the 10-meter-long construction pit, the sheet piles are built into the sheet pile chambers. Dez guides in the chambers ensure the correct overlap of the profiles. Photo: ZIKOMM / Thomas Masuch

Since sheet piles of this length are not a standard rental product, Euro Verbau manufactured them to size at its production facility in Mönchengladbach and delivered them in a matching package with complete sheet pile elements with spindles, spacers and purlins in widths of three, four and five meters. Before the elements and sheet piles were applied, stability calculations were performed based on soil investigations. The static calculations were also of particular interest to Ingo Schachtschneider, whose company employs about 50 people, six to seven of whom are permanently on the Motschenbrucher Brook construction site. "Because safety is our first priority."

Working at depths of more than 7 meters requires high reliability of the equipment. The applied system is particularly suitable for crossing cables and pipelines. Photo: Müller & Bleckmann

Broad offerings for particularly specific projects

Each construction pit section is 10 meters long and 7 meters deep. The soil is first compacted with crushed stone and sand before the pipe segments are brought in and laid by crane. The sheet piles protrude above the construction pit along the sides at different heights, depending on how far into the ground they can be inserted. Sometimes there are stones or rocks in the way.

Once the pipes are connected, Andreas Iks and his colleagues backfill the construction pit section and start digging again 10 meters away and the sides are propped up again with sheet piling. For Ingo Schachtschneider, the fact that everything is running so smoothly is partly due to Euro Verbau's flexible customization: "We have already successfully completed several projects together. There are few companies that can offer the right solution for every application. Euro Verbau also offers solutions for particularly specific projects thanks to its wide range of products."