Contaminated Sediment Management

Conducting a scientifically sound evaluation of risks associated with contaminated sediments requires a focused application of multi-disciplinary expertise. HydroQual has supported our clients needs by assembling the required expertise within our multi-disciplinary staff of scientist and engineers. HydroQual’s contaminated sediment modeling expertise has been developed over approximately three decades, beginning with models of PCB contamination in the Hudson (NY) and Kalamazoo (MI) Rivers and Kepone in the James River (VA). The level of complexity of contaminated sediment modeling approaches has developed from the early analytical solutions of Donald O’Connor (1988a, b, c) to the linked three-dimensional, time-variable hydrodynamic – sediment transport – contaminant fate – bioaccumulation framework typically applied today. The latter comprehensive framework can be applied to answer questions such as:

• Recovery time to various targets:
  • water or sediment concentrations
  • biota concentrations
• Ecological risk and/or human health risk
• Effects of legacy sediments vs. present-day inputs
• Pathway-damage analysis for Natural Resource Damage Assessments (NRDA)
• Evaluation of remediation alternatives
• Effect of potential extreme events

This integrated modeling framework is a particularly valuable tool for evaluating remediation alternatives and the effect of potential extreme events (e.g., extreme flood flows or hurricanes) because data are rarely available for use in a data-based approach for addressing theses questions. HydroQual staff have worked in a leadership capacity with EPA and municipal and industrial research groups to develop methods for evaluating the effects of sediment characteristics on bioavailability and toxicity of organic chemicals and metals to exposed biota. The fruits of these research efforts are incorporated into the modeling framework applied in contaminated sediment investigations to account for the influence of site-specific conditions on biological and risk-based endpoints.

O’Connor, D.J., 1988a. Models of sorptive toxic substances in freshwater systems. I: Basic equations. J.Envr.Engr. (ASCE) 114(3): 507-532.

O’Connor, D.J., 1988b. Models of sorptive toxic substances in freshwater systems. II: Lakes and reservoirs. J.Envr.Engr. (ASCE) 114(3): 533-551.

O’Connor, D.J., 1988c. Models of sorptive toxic substances in freshwater systems. II: Streams and rivers. J.Envr.Engr. (ASCE) 114(3): 552-574.