Sewage treatment plant Obernhain

Useful ballast

KREBS+KIEFER was commissioned with design of the structure and excavation for new construction of a rainwater overflow basin at the Obernhain clarification plant. The open reinforced-concrete basin is divided into two compartments by a partition wall. Its average foundation level is 4 metres below ground and 5 metres at the deepest point under the control room. Buoyancy control had to be included, because the peak level of local groundwater reaches the basin rim.

KREBS+KIEFER solved this task cost-effectively. First, the engineers used the profile concrete in the basin interior as mass. They then provided the necessary ballast with a projection around the base slab and the earth lying on top of it.


  • Structural design, service phases 1 to 6
  • Excavation planning, 1 to 6