Gestion à l'amont des eaux pluviales Incidence sur les flux hydrauliques et la contamination métallique

Growing urbanization leads to excess load on sewers and therefore creates new needs for stormwater management. Best management practices (BMPs) for stormwater are increasingly implemented with hydraulic management aims, for example to prevent flooding, thanks to water storage or infiltration. Effects of BMPs on hydraulic flows and heavy metals contamination are studied through two rain events of different features. A comparison between a watershed, drained by a classic separate sewer, and three others, using combination of different BMPs, reveals reduced flow peaks (up to a factor 20) and increased concentration times (between 2 hours and 7 hours). Discharged water volumes are also proven to be significantly reduced (by a factor of 1.2 up to 2) in comparison with classic sewer simulations. Copper and lead concentrations are lower at BMPs downstream. For other metals, a deeper area study (with roads, gardens, buildings) would be necessary before drawing conclusions. In any case, reduced water flows allow a significant reduction of pollutants discharged in the environment.