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Wirtschaftsbetrieb Mainz AÖR
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Not in, but out

The "Gaßnerallee" flood pumping station

The flood pump from the outside.k from the outside.

It's pouring with rain, and the sewer system is threatening to become overloaded. Because the heavy rainfall greatly dilutes the wastewater, we are allowed to discharge some of the so-called mixed water directly into the Rhine. This has been stipulated by law. There are a good three dozen of these outlets between Weisenau and Mombach – and they have to be closed when the Rhine water level rises at the same time. So what now?

For this scenario, the flood pump station in Gassnerallee has been in place since 2008. Inside this architecturally unusual building, one of the largest weirs in Europe ensures that the outlet to the river side is sealed off, while two huge, continuously height-adjustable pumps transport the water from the canal over the steel plate into the Rhine. This means that the river floodwater cannot enter the canal, but the water there can still flow out. Great, isn't it?!

Worth knowing

  • Pump capacity: approx. 5,000 liters per second
  • Relief and flood barrier:
    - Weight: 22 tons
    - Dimensions: 26.64 m² (3.70 m wide / 7.20 m high)
    - Steel cladding: 25 cm
  • Construction time: approx. 4 years
  • Cost: approx. €6.25 million
  • Objective: Protection against a so-called 200-year flood (water level 8.30 m)
The open weir.
The weir while the pumps are running.

Explanations and notes

Picture credits

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