CLEANUP OF CONTAMINATED SITES - EXPERIENCES IN THE NETHERLANDS

The number of more or less strongly contaminated sites in the Netherla nds amounts to about 100,000. For more than ten years soil treatment t echniques have been developed and used to clean-up those contaminated sites. The major clean-up techniques for excavated soil are extraction /wet classification, thermal treatment and biological treatment by lan dfarming. With extraction/wet classification experience is available w ith the treatment of sandy soils with a clay or humus percentage of le ss than 20%. The type of pollutants which have been removed with extra ction/classification varies strongly: PAH, hydrocarbons, mineral oil, cyanides, Cd, Zn, Cr, Cu, Pb and Ni. With thermal treatment, experienc e is available with all types of soil, contaminated with cyanides, PAH , mineral oil, hydrocarbons, gasoline and HCH. With landfarming, exper ience is limited to the treatment of sandy soils polluted with easily biodegradable components such as gasoline hydrocarbons, low molecular PAH and mineral oil. Up to now more than 4,000,000 tonnes of soil have been treated with these methods. The major in situ clean-up methods a re liquid extraction, soil vapour extraction and biorestoration. Howev er, in comparison with the clean-up of excavated soils the practical e xperience with these in situ methods is still limited. Research and de velopment is still going on and is especially focused on the improveme nt of the clean-up techniques for excavated soil, and the improvement and further development of in situ treatment techniques, especially in sis biorestoration. Copyright (C) 1996 IAWQ.