Using the Analytic Hierarchy Process for Selecting an Appropriate Fate and Transport Model for Risk-Based Decision Making at Hazardous Waste Sites

Abstract

The management and regulation of hazardous waste sites are increasingly being carried out by assessing risks via different exposure pathways. The selection of an appropriate multimedia fate and transport for carrying out screening level risk assessment is a challenging task given the paucity of data and the need for modeling rigor. The utility of a multicriteria decision-making technique, called the analytic hierarchy process (AHP), is explored in this study to select an appropriate model that satisfies the needs of the stakeholders in an optimal manner. The criteria for model selection focused on various issues ranging from scientific credibility to data availability and end-user requirements, and were compiled from a survey of modeling practices and needs of various agencies of the California/Environmental Protection Agency that was carried out previously. Seven different public-domain multimedia modeling codes were evaluated against these criteria using AHP. The study indicated that the highest ranked model (CalTOX) only satisfied about 31% of the needs of the stakeholders for the site conditions assumed. This result indicates that there is a wide scope for further improvement in all the models that are considered here. The local priority matrix obtained for each criteria was seen to be useful to identify limitations of individual models. Certain improvements are suggested to enhance the available public-domain multimedia models to meet stakeholder needs. AHP is seen as a consistent, flexible, and intuitive approach to assess necessary model complexity and is recommended for use in similar policy and regulatory applications.