When filtering the water fines are shifted to the lower gravel body, this
reduces the filtering capacity of a basin. The sole under the gravel filter layer of sand is regenerated at regular intervals after removal of the sand to a depth of 1 m.
- Removal of the gravel filter body and screening for coarse and fine gravel
- In the background the gravel washing plant for the fine gravel
- Input of the washed fine gravel to coarse gravel integrated again