Embedding expert knowledge in a decision model: evaluating natural attenuation at TCE sites

This paper describes a generalized methodology that enables the translation of expert knowledge about any complex process involved in a remedial decision into easy-to-use decision tools. The methodology is applied to evaluate reductive dechlorination as a remedial possibility at sites contaminated with trichloroethene (TCE), building on an existing protocol/scoring system put forth by the US Air Force and the US EPA. An alternate scoring system is proposed, which has two major advantages, namely that it: (i) attributes relative weights to findings based on expert beliefs; and (ii) systematically includes negative weights for negative findings. The ability of the proposed scoring system to assess the bioattenuation potential of TCE is demonstrated using data from extensively studied sites.