An Outline of a Guidance Framework for Assessing Hydrogeological Risks at Early Stages

The prevalent and straightforward routine of impulsively collecting masses of new data for studies relating to ground-water contamination can be inefficient and costly as it does not provide optimal value from existing hydrogeologic and other information. A preliminary guidance framework is outlined, for early stage monetary risk assessments prior to any new measurements, considering both the probability and the economical consequences of contamination. The framework is aimed at providing a basis for cost-effective decision-making regarding ground-water protection and management actions. It centers on improved conceptual hydrogeological site descriptions based on existing information and professional judgments prior to any new measurements. A key aspect of the framework is to derive maximum possible quantitative understanding of risks from limited prior available qualitative information. The framework has a dual-site approach, assuming a situation of a contaminant source site and a receptor site. A two-step procedure leads to the monetary risk assessment with respect to existing compliance levels: (1) conceptual model development, and (2) quantitative model realization, addressing the probability of contaminant release at the contamination source, the hydraulic connection between the source and the receptor, and the contaminant transport conditions. The purpose of the framework is twofold: (1) to provide a risk assessmentmore » framework which optimizes use of professional judgment for studies where data are limited, and (2) to give synergistic interpretive values that complement field measurements and that can be used as prior estimates in more detailed studies.« less