Print this page Environmental Dredging of Contaminated Sediments
Michael J. Dickey, P.E.
Course Outline
This online course provides an introduction to environmental dredging as a remedial approach for contaminated sediment sites. Specific topics include advantages and limitations of dredging and excavation alternatives, types of dredging and excavation technologies available for site remediation, selection of dredging equipment and operational considerations, transportation/staging/dewatering of dredged materials, and treatment and disposal of dredged material from contaminated sediment sites.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
Learning Objective
At the conclusion of this course, the student will
- Have an understanding of the challenges associated with removing contaminated sediments from a water body;
- Understand the potential advantages and limitations of environmental dredging as a remedial strategy;
- Develop an understanding of how various site conditions can effect the appropriateness, effectiveness, or viability of a contemplated dredging strategy;
- Understand how various technologies can be used to physically isolate contaminated sediment from the environment to facilitate excavation (i;e; – sheet piles, inflatable dams, etc;);
- Become familiar with the different types of mechanical and hydraulic dredging technologies available for removal of contaminated sediment;
- Develop a basic understanding of the operational characteristics and equipment selection factors for environmental dredging applications;
- Understand the concepts of sediment re-suspension and residuals;
- Understand how various containment barriers can be used to reduce, control, or minimize transport of re-suspended particles;
- Understand the various methods used to convey sediment from the removal site to the staging and dewatering area;
- Develop a basic understanding of how contaminated sediment is staged and dewatered following dredging or excavation;
- Become familiar with various ex-situ treatment methods for contaminated sediment; and
- Understand common disposal options for contaminated sediment.
Intended Audience
This course is intended primarily for civil and environmental engineers.
Benefit to Attendees
Attendees of this course will obtain practical knowledge pertaining to environmental dredging as a remedial alternative, which is useful for environmental professionals who have been, or will be, tasked with evaluating various remediation strategies for a contaminated sediment site.
Course Introduction
Contaminated sediments pose serious risks to human health and the environment, and therefore have received significant regulatory attention at the local, State, and Federal levels in recent years. Options commonly considered for remediation of contaminated sediment sites include monitored natural recovery (MNR), in situ capping, and environmental dredging. The focus of this course will be to provide the attendee with an introduction to environmental dredging as a cleanup strategy for contaminated sediment sites. For the purposes of this course, environmental dredging is defined as the removal of contaminated sediments from a waterbody for purposes of sediment remediation, either while it is submerged (dredging) or after water has been diverted or drained (excavation).
Course Content
The focus of this course will be to provide the attendee with an introduction to environmental dredging as a cleanup strategy for contaminated sediment sites. The course is offered within the context of guidance provided by the Environmental Protection Agency (EPA) for sites regulated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and Resource Conservation and Recovery Act (RCRA) programs. You are required to study the following guidance document from the EPA:
Chapter 6 of Contaminated Sediment Remediation Guidance for Hazardous Waste Sites, 37 pages, PDF file.
Chapter 6 - Dredging and Excavation
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the above underlined hypertext to view, download or print the document for your
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Course Summary
Physical removal of contaminated sediment (either through dredging or excavation) has been the selected remedial strategy at more than 100 Superfund sites across the United States. Physical removal has several advantages over MNR and in-situ capping strategies in that it often has the lowest level of uncertainty regarding long-term effectiveness, and typically offers higher flexibility in terms of the future use of the water body. However, environmental dredging is not without its limitations, including the complexities and costs associated with implementation of an environmental dredging remedy. Accordingly, this course will explore several aspects of environmental dredging as a remedial strategy, including:
a. Advantages and limitations of environmental dredging over other remedial approaches.
b. Various types of environmental dredging technologies.
c. How the physical environment at a contaminated sediment site plays a role in the development of an environmental dredging program.
d. Typical considerations in the selection of appropriate dredging equipment for a specific project.
e. Considerations related to particle re-suspension and dredging residuals, and the effectiveness of certain types of containment barriers on controlling or reducing undesirable effects from dredging operations.
f. Typical methods of transport, staging, and dewatering of dredged materials.
g. Ex-situ treatment technologies to reduce the toxicity, mobility, or volume of the contaminated material prior to disposal.
h. Sediment disposal alternatives.
Related Links
For additional technical information related to this subject, please visit the following websites:
a. Technical Guidelines for Environmental Dredging of Contaminated Sediments, U.S. Army Corps of Engineers, Engineer Research and Development Center, Technical Report Number ERDC/EL TR-08-29, September 2008
b. The Four Rs of Environmental Dredging: Resuspension, Release, Residual, and Risk, U.S. Army Corps of Engineers, Engineer Research and Development Center, Technical Report Number ERDC/EL TR-08-4, January 2008
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
