Peter Van den bossche (DEME Group) presented the remediation of a chemical waste landfill by means of ex-situ immobilisation. This is a case of classic landfill mining for the reuse of land.
A chemical waste landfill and the above landfill were leaching heavy metals and sulphates in the underlying soil and groundwater. The landfill used an area of about 18.000 m², depth of the landfill was about 6m and contained about 160.000 ton of waste. Initially the remediation plan was to cover the landfill and monitor for 30 years. Afterwards an alternative solution was proposed: excavation of the waste and removal to a hazardous and non-hazardous waste landfill, or immobilisation of the metals to allow storage on an non-hazardous landfill.
A feasibility study was performed in 2016 and indicated that a tailor-made immobilisation process was needed to avoid leaching of heavy metals in the soil. The project was executed from the end of 2017 and started with the excavation of the landfill containing chemical waste, sampling sieving before being (internally) transported to the immobilisation plant. This project proves that the removal of a landfill containing chemical waste and storage of immobilised waste on external landfills is possible. This remediation project eliminated the risks of capping and created new land.