Environmental dredging residual generation and management

Area of Science:

• Environmental Science
• Sedimentology
• Environmental Engineering

Background:

• Environmental dredging project success hinges on managing remaining sediment contamination, known as post-dredging residuals.
• Post-dredging residuals are a mixture of sediments from the entire dredge cut, exhibiting fluid mud properties that can spread contamination.
• Understanding and managing these residuals is crucial for minimizing environmental impact.

Purpose of the Study:

• To review and analyze robust dredging residual evaluations from recent projects in the US and Canada.
• To improve the understanding of dredging residual formation and its contributing factors.
• To inform the evaluation, selection, design, and implementation of dredging remedies.

Main Methods:

• Review of data from recent dredging projects with comprehensive characterization programs.
• Analysis of case studies including the Hudson River, Lower Fox River, Ashtabula River, and Esquimalt Harbour.
• Evaluation of the relationship between site conditions, particularly sediment fluidity (dry bulk density), and residual magnitude.

Main Results:

• Post-dredging residuals are a mixture of sediments from the dredge cut with fluid mud properties.
• Sediment fluidity, indicated by dry bulk density, is a primary determinant of residual magnitude.
• Residual generation is unavoidable but manageable through site-specific plans.

Conclusions:

• Improved models for dredging residual formation can be developed based on robust data.
• Site-specific management plans are essential for the successful and efficient management of dredging residuals.
• Effective management of post-dredging residuals ensures the success of environmental dredging projects.