Characterization & main factors affecting clogging evolution of the bottom of stormwater infiltration systems

The paper presents recent studies on spatial and temporal characterization of the clogging of a large infiltration system and main factors affecting its evolution. Thickness, organic content, density, particle size distribution, biomass and saturated hydraulic conductivity were then evaluated during 10 campaigns from September 2009 to February 2011. The results show that the sediment accumulation over the bottom is heterogeneous and more important in areas often flooded and in particular in the lowest part of the basin. In this part, the grain size is also the finest, the biomass and porosity the highest, the dry bulk density the lowest giving to the soil a peaty aspect. This part is also the more clogged. The heterogeneity of the characteristics of the bottom in time and space is high with no clear tendencies except for organic matter which has doubled in 1.5 years. In general, all the characteristics are in the same range than those observed on similar systems. The results also show a good spatial logarithmic regression in particular with porosity, organic matter, biomass content, and grain size D10 but an insufficient correlation to explain the evolution of clogging both in space and time.