For decades, the only answer to contaminated sediment remediation has been either dredging or capping.
While these remedial measures certainly have a central place as effective sediment management measures, alternative measures for in-situ sediment treatment, stabilization, and mitigation are now increasingly implemented at a wide range of sites. Analogous to the shift from dig and haul or pump and treat to innovative in-situ remediation approaches at land-side sites, sediment remediation technologies are maturing past direct removal to less intrusive remedies which are more tailored for individual site conditions. Often these alternatives provide equivalent protectiveness to the environment but may be more easily implemented, generate fewer greenhouse gas emissions, reduce the volume of material disposed at landfills, or are more cost effective. As these technologies have matured, an expanding list of successful case studies has led to more widespread regulatory acceptance of alternative approaches to sediment management. This presentation will focus on a range alternative or enhanced management strategies for sediment contamination which may be used as stand-alone measures or as part of an integrated remedy, including: Enhanced Monitored Natural Recovery: an augmentation of natural depositional process to improve the quality of shallow sediment in the bio-active zone; Active Capping: integration of materials such as activated carbon to bind or remediate contaminants and reduce bioavailability; In Situ Bioremediation: Stimulating or enhancing the microbial community in the shallow pore water to more efficiently degrade target contaminants; and Thin Layer Isolation Capping: placement of a thin layer, low-permeability zone to reduce contaminant flux through the pore water. Each of these alternative or enhanced sediment management strategies will be discussed in terms of physical limitations for implementation, types of contaminants that have been successfully addressed, challenges for implementation, regulatory acceptance, cost, and maturity of the technology in implementation for pilot or full-scale designs.