Application of Observational Method to Hazardous Waste Engineering

Abstract

Uncertainty is a key technical factor in hazardous waste site remediations. It can lead to unreasonable data gathering exercises if the point of diminishing information returns is not recognized. Engineering under uncertainty, however, is not unique to hazardous waste site remediation. Approaches have been used elsewhere to recognize and respond to substantial uncertainty. The observational method, traditionally applied in geotechnical engineering, has a number of key elements applicable to hazardous waste site remediation. The key contributions of the observational method are: (1) Remedial design based on most probable site conditions; (2) identification of reasonable deviations from those conditions; (3) identification of parameters to observe so as to detect deviations during remediation; and (4) preparation of contingency plans for each potential deviation. This paper describes an approach for incorporating the observational method into the current USEPA Superfund process and provides a detailed discussion of that process in the context of ground water remediation. Explicitly recognizing uncertainty in a proper application of the observational method offers the opportunity to reduce project time and costs as well as risks.