Contaminated sediment from the Port of Dunkirk has been re-used in road structures since 2002, when the Port started to work with the Ecole des Mines de Douai and various industrial partners in order to design alternative materials for stabilised sub-base road layers. After the first laboratory tests, in 2005, a pilot trial was carried out on a 300 m² plot where a 50m long road was constructed using treated sediment. The objective was to verify the industrial feasibility of the entire process. The trial demonstrated that it was possible to produce alternative road materials. The road had to meet the requirements of the relevant French criteria for roads constructed with conventional road materials.
Following these results, the Port decided to continue to work with industrial partners, and in 2012, it reconstructed 850m of the road ”Route du Quai Freycinet 12”. The road was designed for 15 years of traffic, with an average of 100 heavy goods vehicles per day. The approach used in 2012 was less effective than the earlier 2005 study. However, the road mixture reached the level of mechanical class T2, which was taken into account in the design of the road structure. An environmental monitoring analysis confirmed the effectiveness of the treatment by bio-remediation, revealing no problems with organic pollutant levels (BTEX, PCBs, TPH, TOC, PAH) or heavy metals. There were, however, some problems with soluble fraction, sulphate and chloride in the sediment originating from the marine environment. Tests were conducted on laboratory specimens of the treated mixture and showed a significant reduction in the soluble fraction by using a hydraulic binder.
After finalising the works, analyses of the percolated water in the groundwater, in the nearby dock along the Route du Quai Freycinet 12, and in the piezometer were conducted every month during the first year and every six months over the following 2 years. One year after the works, no notable changes were detected at the three monitoring points.
Main activity field:
- alternative material for road construction designed and developed using contaminated sediment
- 1800 m³ of sediment reused
- 850m of road reconstructed using newly designed material