Cascade weir
A cascade weir is a movable weir that creates artificial cascades .
functionality
A cascade weir is a weir system that can be moved hydraulically vertically and is used in mixed water sewers for the intermediate storage of rainwater. Mixed water canals convey sewage (e.g. toilet flushes) and rainwater from paved surfaces (e.g. streets and roofs) to the sewage treatment plant . Since the sewage treatment plant cannot process the much larger inflow in rainy weather, the rainwater that has flowed into the combined sewer must be buffered. Rainwater buffers can be implemented in an expensive basin construction or in an inexpensive sewer storage space. The cheaper realization of sewer storage spaces with cascade weirs also enables the automated cleaning of sewers.
The weir body usually consists of a stainless steel jacket, which is reinforced with a reinforced concrete core. The weir is driven into the bottom to clear the flow cross-section . In order to create a retention effect, the weir is moved to different heights and thus water is backed up. The weir system is positioned in different positions depending on the retention volume requirement. This creates an artificial cascade.
Application area
In urban water management, cascade weirs can be built with rigid throttling devices as an alternative to rain overflow basins or storage canals. Cascade weirs are preferably used in mixed water or wastewater sewers and thus offer the possibility of controlling the sewage flows. The primary goal of the weir system is therefore the temporary storage of precipitation runoff and restricted forwarding to the underlying sewage treatment plant. With this method, the natural receiving water is polluted with less mixed or waste water. Another advantage of this technology is the possibility of dry weather flushing. As a result, the channel is permanently freed from deposits and sedimentation . If a relief weir system is used at the same time , this technology is called KSE technology: cascade, surge and relief technology. In addition to urban water management , the cascade weir systems can also be used in river engineering as an alternative to other weir systems, such as fish-belly flaps . The advantage lies in the faster and more precise flow regulation.
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 " (2004)