Risk-based design of cost-efficient remediation strategies at megasites

Remediation planners and decision makers at megasites are usually confronted with vast and complex distributions of pollutants in soil and groundwater. Due to the size of the problem and a typically scarce database on hydrogeological and geochemical parameters, megasites represent a particular challenge; and specifically adapted methods are required to assist site managers in the design of effective cleanup solutions. The proposed methodology is based on a system dynamics modelling approach where the system is represented by a risk based source-pathway-receptor concept and the dynamics predominantly by a mass flux model. Effects of possible remedial actions, either tackling the contaminant source or managing the groundwater plume, are described as mass flux change over time. The concept allows for a straightforward check of effects (risk reduction) and costs of any particular remediation scenario. Working on a relatively high abstraction level and making use of various simplified analytical relationships, quick information on economic as well as technical feasibility of possible scenarios is provided.