The gravel recovered as part of the project correcting the navigation line on the Rhine was reused as gravel filler on the banks of the Rhine between the Schwarzwaldbrücke and Wettsteinbrücke. On one hand, this enhances the ecological qualities of the riverbank area through the creation of new spawning grounds and fish habitats. On the other hand, it also stabilises the existing bank structures and protects them from erosion. Firstly, safety measures such as platforms and islands were installed and the supply lines extended. After filling and rough modelling, fine modelling and structural measures (stones, fascines, cuttings) were carried out.
The works in the water had to be completed by the end of January 2019, as this marked the start of the close season for fish. Due to the extremely limited space available at the loading and unloading point, there were a number of logistical challenges. The work was carried out using floating equipment and required complex intermediate transportation over water. Material was delivered just in time, with a total of 17,700 m3 of gravel filled in seven sections. In order to prevent the loose gravel from becoming rapidly clogged with particles and sludge, the filling works had to be carried out in the direction of river flow. Furthermore, the construction site was also influenced by the changing water levels on the Rhine.