Relief weir

Relief weirs are weir systems that discharge relief water into the natural receiving waters in a controlled manner. Relief weirs have the task of discharging the mixed water , which can no longer be collected by the sewer system , into the receiving water in the event of heavy rain , as otherwise the basement could fill up with the resulting backwater and the water could come out of the manhole covers. If the inflow exceeds a defined limit value, the weir plate moves in a controlled manner to a lower position in which the inflow corresponds to the relief. This prevents a further rise in the water level in the sewer system. The construction of the relief weirs corresponds to the same principle as with a cascade weir: the weir plate consists of a stainless steel jacket with a reinforced concrete core.

The separating structure is a relief device that cannot be adapted to the amount of water flowing in.

Application area

In urban water management, relief weirs are combined with storage sewers. They are built as an alternative to conventional rigid throttling devices or fixed thresholds. In this way, storage ducts can also provide relief in the middle, in addition to at the inlet and outlet. This divides the storage sewer into a retention section and a clarification section: The section below the relief weir blocks the first precipitation runoff and, in a throttled manner, forwards it to the wastewater treatment plant. The part above mechanically cleans the inflowing wastewater through sedimentation .

swell

• Pinnekamp, ​​J. et al .: Final report on the research project "Investigation of the relief and operational behavior of controlled storage sewers with central relief" . RWTH Aachen University, 2004.