Acknowledgements

Resources

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  Development of DoD Guidance for Monitored Natural Recovery at Contaminated Sediments Sites (Ref. V.1f.2)
  

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  In-Water and Riparian Management of Sediment and Dredge Material (Ref. V.1h.1) - Intended for management of sediments from channel (navigational) dredging, this document provides guidance to minimize the impact of contaminated sediments during dredging, and through underwater or shoreline burial. Numerical screening values are included for select contaminants.
  

Section V.2 Monitoring During Remedial Actions

The goals and objectives of monitoring during contaminated sediment remedial actions are to ensure protection of human health and the environment. Monitoring may involve sediment, water and biota sampling depending on the type of remedial action. The monitoring should be designed to address any corrective actions that may be needed during the remedial action.

Typically, design and post-dredging sediment sampling is performed. The design sediment sampling is used to more accurately determine the depth and locations that require dredging. This is not necessarily the same as the sampling used in assessment, which is used to determine if a site requires a remedial action. The design (or pre-dredge) sampling is particularly important because a large amount of over dredging can significantly increase the amount of sediment to be processed and disposed, thus increasing the cost. Also, dredging is generally disruptive of the ecosystem at and near the dredging location, so limiting the dredging to exactly what is required can help limit any unnecessary ecological damage. Post-dredging sediment sampling should be done to confirm that the dredging was completed and that cleanup goals have been achieved. Depending on the post dredging sampling results adding dredging may be required.

The main concern with monitoring while dredging generally deals with the re-suspension of sediments (clean and contaminated). Monitoring chemical constituents and physical parameters (i.e. turbidity) sampling can be used to evaluate and regulate re-suspension caused by dredging. The sampling location to demonstrate compliance should be chosen carefully and allow a mixing zone.

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  Monitoring Frequency - Real-time monitoring for turbidity is performed at the dredge and designated locations near the dredge. This information is used to evaluate and control dredging. Analytical results for chemical constituents will likely take 24 hours (or more) after the sampling is performed. Costs can be considerably higher for faster results. Close evaluation of dredging should be performed to allow for correct interpretation of the results. Sampling frequency should be decided based on the chemical constituents and site specific concerns. The monitoring should be used to evaluate project compliance. One alternative would be to gather more sampling data during the start of the project and reduce the frequency once dredging is at a consistent production rate. This would provide a basis to modify the monitoring frequency (increasing or decreasing) based on actual data. The sampling location to demonstrate compliance should be chosen carefully and allow for a mixing zone.
  

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  Monitoring Factors - Factors to consider while monitoring included: depth of dredging; cleanup goals for chemical constituents; controlling the rate of dredging to maintain water quality goals; and measuring quantity of sediment and the chemical contaminants removed.
  

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  Monitoring Area and Thickness - Evaluation of the caps effectiveness should be performed during capping. The cap thickness should be monitored during the capping and compared to the minimum cap thickness to ensure the remedial goals are achieved. Cleanup goals for chemical constituents after the cap has been placed should be established.
  
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  Water Quality - A major issue during capping can be trying to maintain water quality goals. The rate of cap placement may help in maintaining water quality (i.e., a slower rate of placement may cause fewer water quality concerns).
  
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  Real Time Monitoring - The results of real-time monitoring of chemical constituents may be at least 24 hours after sampling is performed, and the cost for faster turnaround of results is much higher. Care should be taken when considering the amount of real-time monitoring to be performed.
  

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  Evaluation of Dredged Material Plumes Physical Monitoring Techniques (Ref. V.2.1)
  
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  Acoustic Monitoring of Dredging-Related Suspended-Sediment Plumes (Ref. V.2.2)
  
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  Improving Methods for Correlating Turbidity and Suspended Solids for Monitoring (Ref. V.2.3)
  

1. 
   Removing any top contaminated sediments;
   
2. 
   Removing the clean material (typically sediment or sand) and properly disposing of the clean material;
   
3. 
   Placing the contaminated sediments into the CAD; and
   
4. 
   Placing clean cap material on the top of the CAD. (There are some CADs that are not capped).
   

Once created, a CAD should be considered a permanent facility. CAD locations can potentially be limited. CADs placed in navigational channels would need to be constructed so the top of the CAD will not interfere with future navigational dredging or be disturbed by navigational activities (i.e., dropping anchors, prop wash). The project manager should check any appropriate State/federal regulations regarding all onsite disposal facilities for contaminated sediments or off site disposal of any clean material or contaminated material.

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  Confined Disposal Facility (CDF) Containment Features: A Summary of Field Experience (Ref. V.3a.1)
  
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  Overview of Processes Affecting Contaminant Release form Confined Disposal Facilities (Ref. V.3a.2)
  
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  Liner Design Guidance for Confined Disposal Facility Leachate Control (Ref. V.3a.3)