The mismatch between (in-situ) soil site investigation and (ex-situ) excavated soil quality
Based on the statistical analysis of an extensive database, the mismatch between in-situ and ex-situ qualified soil stockpiles from remediation sites was determined. On average, the environmental quality of the excavated soil stockpile is better than the in-situ qualified soil, independent of the destination of the soil.
For soil wich had been selected for treatment, approximately 20% could be directly reused. For soil wich had been selected for landfilling, approximately 30% could be directly reused whilst 15% could be thermally treated. From an environmental point of view, the additional ex-situ qualification of soil is beneficial. However, additional ex-situ qualification results in additional costs. For this reason, the impact of incorporating an ex-situ qualification step in the remediation process was assessed in economic terms. It was concluded that at a national level, the financial effect is approximately cost-neutral. Since the national policy aims at maximising reuse and minimising landfilling, it was decided that all disposable soil should be ex-situ qualified prior to landfilling. This measure became effective in November 2001. In addition, the Dutch organisation of soil treatment facilities has adopted a code of conduct, which strongly promotes the identification of reusable soil lots prior to treatment.