Retention basin

A stormwater retention basin ( RRB ) is an artificial basin, which is used to store larger amounts of precipitation water. In contrast to the high water retention basin that is not in or on a river. One often finds it in cities where there when it rains, the excess water from the sewer between stores and slows to the subsequent receiving water releases to relieve this.

While a combined sewer overflow ( in Austria also called rain or combined sewer overflows ), only the separation in the inflow to the treatment plant ( 7 - to 15 -fold waste water discharge ) and discharge permits for water in retention basins the diverted water is buffered and delayed in the storage chamber passed (catch basins ) or after mechanical cleaning routed to the receiving water (run pool).

Stormwater retention basins are built in earth and concrete. Benefits of earthen construction costs are lower and the possible natural design. Advantage of the concrete construction is the lower space requirements; the basin can also be built underground.

Retention basins usually have a useful volume of 150-250 cubic meters per hectare connected paved areas, depending on local conditions but also more or less.

Similar to the flood retention basins described above, there are also in the stormwater retention basin arrangements in the main circuit or shunt; in the latter the constant flow of water at the pool flows past and a subset will be diverted at high water into the basin.

Stormwater Overflow received in Germany generally 20-30 cubic meters, in individual cases, 40 or more cubic meters of usable volume per hectare of connected paved areas. Usually relieve overflow basins approximately 30 to 40 times per year. In other countries ( eg in the Netherlands) higher standards are partly common.

In 2002, in Germany approximately 24,000 stormwater retention basins in operation.

Underground rainwater retention basins

Underground rainwater retention basins are artificially created large chambers that are flooded during heavy rain and often for 20 minutes of heavy rain are designed. The pressure compensation from these chambers escaping air passes through ventilation shafts to the outside.

The chamber is then emptied later, the pressure compensation in the opposite direction via the uptake shaft, which then functions as a supply air duct.