The purification performance of infiltration basins fitted with pretreatment facilities: a case study

In the south-east of France, the evacuation of stormwater by infiltration i nto the ground is being developed for large aquifer systems such as the gro und water in the Rhone valley and in the eastern part of Lyons. A study pro posal has been presented to the water management department of the conurbat ion of Lyons, aimed at quantifying, within a reasonably short space of time , the effects, in terms of transport of pollutants, of the stormwater infil tration system in the underground water in eastern Lyons. To this end, a on e year duration experiment was carried out on the Venissieux infiltration b asin which drains stormwater from a 380 hectares industrial catchment area. Its peculiar configuration also made ii possible to acquire new knowledge on the qualitative operation of a few pretreatment facilities. After descri bing the operation of the basin and the experimental protocol, we shall pre sent a body of data that we monitored and our conclusions about the behavio ur of the pollution throughout the facilities. Then, we present methods use d to assess the pollution removal performance of the infiltration basin and its pretreatment devices, the results obtained, and our conclusions about the impact of the infiltration basin on groundwater and soil.