In the Netherlands the application of a decision
support system to determine the urgency for remediation (hereafter the
urgency system) when a site is contaminated above the standards for soil
contamination (intervention values combined with criteria for polluted
volume and surface area) is advised by the Soil Protection Act. The urgency
system is now in function for about 5 years. New technical and scientific
insights, bottlenecks in the application of the urgency system, and new soil
protection policy are pressing towards reflection and reformulation of the
current practice. The aim of this study is to create applicable proposals
for site-specific ecological risk assessment possibly to improve the current
urgency system, accommodating the current trends. The first proposal is
focussed on a central role of the calculation of the toxic pressure per
chemical and of the combined toxic pressure of all chemicals together at the
site, rather than comparison of concentrations of chemicals with HC50 values
or soil quality standards. The second proposal is focussed on elaboration
of the assessment with site specific biological information such as the
results from bioassay testing and ecological field observations. The
combination of three disciplines in a Triad approach (environmental
chemistry, bioassay testing, ecological field observations) will improve the
reliability of the assessment, because it will efficiently eliminate
intrinsic and conceptual uncertainties in assessment
techniques.
