| Abstract |
Road engineering is one way for sediments to he reused and enter the circular economy, instead of being stored in landfill. The so-called "Guide Setra" [1] constitutes the French framework for reusing alternative materials in road engineering, including three kinds of road structures: coated (with an impervious layer), covered (with at least 30 cm of natural material) or uncoated and uncovered. The Sedimed project investigated those three options, settling lysimeters (uncoated and uncovered) and building experimental road (coated) and landforms (covered), incorporating two marine contaminated sediments from the Toulon bay, France (QN and QC). Leachates were collected and sampled on these three experimental structures, and the pollutants (12 metals - As, Ba, Cd, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Se, Zn - 3 anions - Cl-, F- SO42- -16 PAH and 3 emerging pollutants detected in the sediments - DBT, TBT and DEEP), were analyzed on every sample, enabling the determination of the total released quantity of each pollutant on a L/S basis (ratio between the volume of water that percolated through the structure and the mass of sediment in the structure). The total content of organic pollutants of QN would normally disqualify this sediment for road engineering, according to the "Guide Setra". Yet, only considering the potential impact on groundwater, the released quantities of pollutants are far from very protecting limits. For both QN and QC, the anions content (Cl- and SO42-) exceeded the "Guide Setra" limits for some structures, indicating that the control of these parameters and the reduction of their global content during the lagooning period might be triggering the reusing options for marine sediments. Those new data and knowledge is a contribution to the definition of a specific framework for reusing sediments in road engineering. |
