Sarah was involved in the rivEAU project to assist a PhD student in the study of the behaviour of a storm basin. The study was done in four phases. First, the closure of the basin and sampling of the input are done during rain events wich causes runoff. After a period of retention, the basin is opened to sample the output. Then, the characterization of the input and output of the basin by various laboratory tests to determine the concentration of suspended solids, heavy metals and N-NH3. We also used the ViCAs protocol to evaluate the settling velocity. Finally, all the data were compiled and analyzed to get an overview of the effects of the retention in the basin.