Importance of implementation and residual risk analyses in sediment remediation.

Management strategies for addressing contaminated sediments can include a wide range of actions, ranging from no action, to the use of engineering controls, to the use of more aggressive, intrusive activities related to removing, containing, or treating sediments because of environmental or navigation considerations. Risk assessment provides a useful foundation for understanding the environmental benefits, residual hazards, and engineering limitations of different remedy alternatives and for identifying or ranking management options. This article, part of a series of panel discussion papers on sediment remediation presented at the Third International Conference on Remediation of Contaminated Sediments held 20-25 January 2005 in New Orleans, Louisiana, USA, reviews 2 types of risk that deserve careful consideration when evaluating remedy alternatives. The evaluation of remedy implementation risks addresses predominantly short-term engineering issues, such as worker and community health and safety, equipment failures, and accident rates. The evaluation of residual risks addresses predominantly longer-term biological and environmental issues, such as ecological recovery, bioaccumulation, and relative changes in exposure and effects to humans, aquatic biota, and wildlife. Understanding the important pathways for contaminant exposure, the human and wildlife populations potentially at risk, and the possible hazards associated with the implementation of different engineering options will contribute to informed decision making with regard to short- and long-term effectiveness, implementability, and potential environmental hazards.