A framework for evaluation

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The decision on how to clean-up a site can be divided into several successive phases. The first decision is that of whether a polluted site needs to be cleaned up. If remediation is not necessary, then the investigations can be stopped. Otherwise, the investigations should be focused on the screening of the suitable remedial strategies. The criteria which will influence this last decision are:

- the total impact of remediation strategy on the total risk for humans, ecosystem and infrastructures;

- the total impact of the remediation strategy on scarce commodities, such as soil, ground water, drinking water, space and energy, and on the quality of the environment as a whole;

- the total impact of the remediation strategy and method on the financial assets of the problem owner.

This perspective is the closest to the original evaluation framework aiming at multifunctionality. The environmental merit perspective, stemming from a Life Cycle Inventory approach, aims at minimizing the use of scarce commodities and the contamination of other compartments due to remedial activities. The costs perspective aims at minimizing the total costs in terms of net present value. The methodology aims at producing, for each cleaning-up option, a set of 3 indices: the amount of risk reduction achieved by the remediation; the environmental balance of the operations and the costs involved. Risk reduction is based on the computation of the overall exposure of people, ecosystems and other targets (e.g. workers on the site during remediation) and at the comparison of the exposure levels with acceptability standards. Risks are computed during all phases of the operations, leading to a time-dependent profile of the risk attenuation process. By compating this to the risk profile of the status quo, the amount of risk reduction can be computed. Environmental merit is based on the computation of an additive index for multiple environmental consequences of soil remediation. The non-local positive and negative outcomes of soil clean-up are weighted and summed up leading to an indication of the environmental performance of the operations. These are compared again to the status quo. The index is here measured in Environmental merit Units. Finally, the costs include all expenses involved in the operations, including asset costs. Costs are computed yearly for the full length of the operations. The Net Present Value is then used as an estimate of the total costs. Each cost item is the sum of the expected expenses in a given period plus a safety quantity to guarantee that the real costs will have only a limited probability of exceeding the computed costs.

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