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Erection of a fish ladder, Hamburg-Bergedorf

The Serrahn weir in Hamburg-Bergedorf is a barrier to fish migration. Fish coming from ‘Schleusengraben’ are not able to pass the weir with its height difference of approx. 1.70 m towards ‘Schlossteich’/‘upper Bille’. Since uncompromised fish passage is a prerequisite for improving water quality and fish population replacement, the erection of a fish ladder in the weir area has been planned.

The facts.

WK Consult deliverables:
Structural design

The task.

The new plant is meant to be positioned on the right river bank along the weir, measuring 95 m in length. For the execution, steel troughs with a segment length of up to 9 m and a width of approx. 1.50 m to 2.30 m were produced from corten steel with a sheet thickness of up to 25 mm. Each trough has a dead weight of up to 11 t.

The individual segments were then screwed together on-site to create three sections. The total length of the fish ladder is approx. 86 m. Expansion joints were installed between the three sections to absorb axial expansions. In order to prevent different vertical and horizontal transverse shifts of the sections, they were coupled together with welded cleats. This aims to prevent damage to the seals around the expansion joints.