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> Great Lakes > Monitoring > Contaminated Sediments > ARCS > Guidance for In-Situ Subaqueous Capping of Contaminated Sediments: Recommendations

Contaminated Sediments Program

Sediment Assessment and Remediation Report

Guidance for In-Situ Subaqueous Capping of Contaminated Sediments

Recommendations

As more designs are completed and additional field experience is gained, the technical guidelines in this report should be refined and expanded. Additional research is also recommended to develop improved tools for capping evaluations. Specific recommendations for further research are summarized as follows:

1. Refine and verify models that predict long-term erosion of caps.

2. Refine existing estimates of resuspension of contaminated material during cap placement. This work will assist in determining the costs vs. benefits of "sprinkling" cap material versus conventional bottom dumping of cap material.

3. Develop engineering guidance on acceptable rates and methods of application of capping material over contaminated material of varying density and shear strength.

4. These techniques should consider the geotechnical behavior related to displacement and mixing of contaminated and capping sediments and resistance of the sediments to bearing failure. Extend the investigation to include penetration of dense (e.g., rock) cap material into contaminated material or other cap layers.

5. Refine existing models for prediction of cap and sediment consolidation. This effort will likely require developing or refining instrumentation for in situ geotechnical measurements.

6. Develop predictive tools for evaluation of long term cap integrity, considering chemical migration via advection, bioturbation, and diffusion. Both analytical and modeling approaches should be considered.

7. Conduct laboratory and field verification studies of long-term cap integrity. Laboratory approaches should include refinement of existing cap effectiveness tests. Field studies should include periodic monitoring and sampling of capped sites to include analysis of core samples.