Experimental Assessment of Stormwater Infiltration Basin Evolution

Infiltration basins are frequently used for stormwater drainage. They can operate for periods over 20 years but long-term evolution is not well understood or controlled. The two main problems encountered are clogging, which compromises the hydraulic capacity of the basin, and possible contamination of underlying soil and groundwater. This paper focuses on studying long-term evolution of clogging and soil pollution of infiltration basins. Basins of different ages are compared. Also, clogging and soil pollutant concentrations are explored for four infiltration basins in Lyon, France. Ages of the sites range from 10 to 21 years old. Clogging is characterized by the hydraulic resistance. Soil samples were collected at different depths in each basin and analyzed for different pollution parameters (metals, hydrocarbons, pH, and particle size distribution). All four basins have good infiltration capacities. Their hydraulic resistance is low. Such uniformity is surprising because of the age difference between the basins. Pollutant concentrations decrease rapidly with depth whereas pH and grain size increase. Concentrations reach an acceptable value at a 30 cm depth, even after 21 years of operation. Multivariate data analysis does not show significant relation between age, hydraulic resistance, and pollution.