Caractérisation du fonctionnement d'un ouvrage de stockage-décantation en ligne des eaux pluviales Cas de la galerie Tolbiac-Masséna

Few data are available on the efficiency of on-line stormwater settling tanks. A study was conducted in 2008 on the Tolbiac-Massena storage system in Paris in order to evaluate the contamination level and the settlability of the collected stormwater, and to analyse the efficiency of the on-line treatment system. Moreover, in situ turbidity data was used to analyse the dynamics of sediment transport over the different sequences of a storage/discharge event. Observed settling efficiencies ranged from 40% to 60% for SS. The SS settling velocities measured in this study were lower than the settling velocity used for the conception of the tank. This result could explained the limited efficiencies observed. Moreover, the perturbations induced by permanent inflow and by the resuspensions during the discharge of the treated water could contribute to a large extent to the weak efficiency.