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Great Lakes Science & Policy

Contaminated Sediment

• Introduction
• Research Needs
• Contaminated Sediment in the Detroit River
• Resources

Introduction

Contaminated sediment is a long-standing problem in lakes and rivers, and contributes to many forms of environmental degradation. From 1985-1989 over 15 million m³ were dredged for more efficient navigation through rivers and harbors of the Great Lakes; 51% of this material had to be placed in confined disposal facilities due to high contaminant levels.

From an environmental cleanup perspective, there are currently few ecologically-based decision-making tools available for pinpointing the most effective contaminated sediment management strategies, and often decisions become overwhelmed by regulatory complexity. Sediment contaminants still represent a major factor limiting our ability to reach a healthy, sustainable environment and economy.

All 42 Areas of Concern identified by the International Joint Commission in the Great Lakes Basin have contaminants in sediment that exceed chemical guidelines, but their effects on the ecosystem are only partially quantified. However, there are clear linkages to restrictions on fish and wildlife consumption, fish tumors or other deformities, loss of fish and wildlife habitat, degraded natural communities, and other ecosystem effects identified in Annex 2 of the Canada-U.S. Great Lakes Water Quality Agreement.

Research Needs

In most Areas of Concern, the sediment problem has not been quantitatively coupled to ecological impairments. Therefore, deciding on volumes of sediment to be cleaned up, why, and what ecological improvements can be expected over time has been challenging. It is important not only to know the existing degree of ecological harm associated with sediment contaminants, but also the circumstances under which those relationships and threats might change, making contaminants more bioavailable or detrimental under different environmental conditions. The ability to forecast the expected degree of recovery and the ecological improvements from sediment cleanup must be demonstrated.

A better understanding of the relationships between contaminated sediment and ecosystem quality would provide stronger justification for a particular sediment management strategy. It would help in making management decisions among the following options:

• source control and natural recovery;
• removal and containment;
• removal and treatment;
• in situ capping, and
• in situ treatment.

If relationships between contaminated sediment and beneficial uses were better understood, more compelling cases could be made to fund sediment cleanup. Better public support for sediment management decisions would result, and more corporate involvement could be expected.

From 1986-1999, more than $580 million has been allocated for 38 remediation projects in 19 Areas of Concern. In addition, the rate of increase has accelerated in recent years.

Unfortunately, of these projects, only three (thus far) have produced information on ecological effectiveness gained by monitoring the recovery of environmental quality after a cleanup has taken place. Measuring ecological effectiveness of sediment cleanup is also important where a new environmental technology has been tested, in order to improve innovative approaches. In cases where sediment remediation was undertaken as a result of regulatory action, the projects were designed to remove the worst masses of contaminants to reduce environmental risks. These projects were very effective in meeting the regulatory requirements, and are consistent with a step-wise incremental approach to management of contaminated sediment called for by the Great Lakes Water Quality Board of the International Joint Commission. After remediation of the worst sites, an integrated evaluation of all sources, including sediment, must be undertaken to determine whether or not further remediation is required and to ensure that remediation is sustainable.

Much more effort should be placed on forecasting and measuring the extent and pace of ecological recovery. This will help in future efforts to make decisions on the most appropriate sediment management strategy, thereby advancing restoration of beneficial uses in Areas of Concern.

Contaminated Sediment in the Detroit River

Addressing contaminated sediment in the Detroit River requires both a short- and long-term approach. In the short term, there are plans for sediment cleanup at Black Lagoon (State and Federal funding) and Conner Creek (City of Detroit funding). Remediation of these sites can serve as an example for future cleanups. However, the initiation of sediment remediation activities at these sites has been delayed due to disposal liability and regulatory issues. This situation illustrates the need to address barriers to contaminated sediment cleanup. The least expensive option is disposal in the U.S. Army Corps of Engineers confined disposal site at Point Mouillee, MI. This facility is currently used for the disposal of sediments dredged from the deep draft navigation channels in the Detroit and Rouge Rivers, as well as disposal of sediments dredged from marina operators and other similar permittees. The CDF was not originally intended to accept remedial dredged material (i.e., contaminated sediment). This issue is now being addressed in the court system.

In the long term, there is a need to develop a comprehensive contaminated sediment cleanup strategy for the entire Detroit River (as well as the other tributaries in Southeast Michigan). This strategy must be targeted at restoring impaired beneficial uses. Further, this must be a coordinated interagency effort among federal, state, county, and local interests.

Resources

To learn more about contaminated sediments, consider the following resources.

• Check out these articles on contaminated sediment published in the Journal of Great Lakes Research.
• Contact a contaminated sediment expert. These IAGLR members have agreed to serve as expert contacts for policymakers interested in contaminated sediments.
• Also see Contaminated Sediments in the Great Lakes Region, Great Lakes Information Network.