The impact of intentional stormwater infiltration on soil and groundwater

Stormwater infiltration is a principle which is more and more utilized on urban sites in France. However, given the characteristics of urban surfaces, and notably the amounts of the different pollutants that stormwater is likely to contain, it is important to try to assess the impact of intentional stormwater infiltration systems on the soil, and on groundwater. To try to answer that type of question, we present an experiment that was carried out in Valence (France) on two infiltration facilities. Situated in the same street, and serving equivalent catchment areas (i.e, a road network, along with a "classical" urban type of habitat), the first one is a recent cylindrical soakaway (1994) and the second one is a rectangular chamber which is around thirty years old. After explaining the experimental protocol, we shall present a body of data that we monitored. We shall then present our conclusions concerning the role of the soil and the groundwater in the process of "clearing up" the different pollutants that are present in stormwater, as well as the migration patterns of these pollutants. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.