Laboratory experiments on bed deposit scouring during flushing operations

The accumulation of sediments on the bottom of sewer channels is responsible for several hydraulic and environmental problems in urban drainage systems. For the removal of deposits, in the last decades many hydraulic devices based on the use of flushing waves have been successfully adopted in sewer systems instead of the more common and expensive mechanical devices. In this paper, the results of an experimental investigation for the analysis of the scouring effects of flushing waves on sediment bed deposits are presented. The experiments were performed in a laboratory flume using a simple flushing gate and considering different hydraulic conditions and bed deposit characteristics. The effects of successive flushing operations were evaluated in terms of bed profile evolution and sediment weights scoured out of the flume. The experimental data derived from the investigation can be taken into account for the validation of numerical models specifically developed for the simulation of the effects of flushing waves on sewer deposits.