Bauer Spezialtiefbau GmbH is well underway with the construction of a mixed-inplace (MIP) cut-off wall, an essential part of the work needed to relocate a dike on the Rhine river at Muendelheim district for flood protection.

The Rhine is one of the busiest rivers in the world. With a total length of over 1200km, it is also the second-longest river in the German-speaking region.

A number of dikes along the Rhine river offer permanent flood protection, including one located in immediate proximity to the Muendelheim district in Duisburg. To give the river more room to expand at high water and thus avoid peak flows, the existing dike at Muendelheim will be relocated, creating approximately 60ha of retention space.

In preparation for the relocation, the cut-off wall is being constructed along the line of the future dike to protect the adjacent city district from groundwater pressure. The city of Duisburg comissioned Bauer with the construction of the MIP cut-off wall. In this method, the soil is broken up with a triple auger, shifted, and then mixed with a binder slurry in the resulting bore hole.

"The big advantage of the MIP method is that there is no excavation. The soil doesn't have to be removed from the site; it can be used directly as aggregate. That is a definite plus, especially for the local residents,” said Mike Schwermer, project manager at Bauer Spezialtiefbau. The finished MIP cut-off wall will measure 1.6km in length. With a width of 550mm and a depth of up to 20m, the total volume of the wall will be around 28,000m².

"The strict quality requirements for the MIP wall pose a particular challenge. It must have exceptional leak tightness and a final rigidity within a specific bandwidth," explained Schwermer.

The cut-off wall will be constructed parallel to the Rhine river on the future route of the dike.

Work on the project began in July 2019 using an RTG RG 25 S with MIP equipment. Bauer plans to complete the cut-off wall in March 2020.