Effects of a porous pavement with reservoir structure on the quality of runoff water and soil

The comparison between the quality of runoff waters either collected at the outlet of a porous pavement with reservoir structure or coming from a nearby catchment drained by a conventional separate system, on the experimental site of Rezé near Nantes (Loire-Atlantique, France) was studied. Four years after the beginning of the experiment, the results obtained from about 30 rainfall events show that runoff waters which went through the porous pavement contain a markedly lower polluting load than those from the reference catchment. The filtration effect of runoff waters by the reservoir structure can decrease the pollutant concentrations of about 64% for suspended solids and 79% for lead. Analyses carried out on materials from both the reservoir structure and the soil show that metallic micropollutants (lead, copper, cadmium, zinc) from runoff waters, accumulate on the surface of the pervious asphalt for the most part, and at the level of the geotextile layer separating the structure from the underlying soil for a small part. This soil does not appear significantly contaminated even after the 4-year period during which the structure has been in operation.