Contaminated Sediments Program
- Great Lakes Monitoring
- Monitoring and Assessment Water Quality
- Global Earth Observation System of Systems (GEOSS)
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Realizing Remediation: A Summary of Contaminated Sediment Remediation Activities in the Great Lakes Basin
Great Lakes National Program Office
Contaminated sediments are of great concern to humans and wildlife that live within the Great Lakes Basin. Years of industrial and municipal discharges, combined sewer overflows and urban and agricultural non-point source runoff have contributed to the creation of vast amounts of highly polluted sediments that pose serious human and ecological health risks. Sediments have been collecting on the bottoms of the Great Lakes ever since they were formed by glacial scouring and melting. The loose, unconsolidated particles that make up the sediment may originate in soil worn away by physical or chemical erosion, or they may come from the decomposition of shells or wood chips. In areas of slow moving water, sediments sink and accumulate on the bottom of lakes and rivers.
Before industry came to the Great Lakes Basin, the natural processes of sedimentation only created changes in the shapes of the lakes and their tributaries. However, in the first century of industrial development, the region began adding chemicals to the water, and in turn, the sediments. Often the approach was simply to run a pipe to the nearest river bank or lakeshore and pump the waste directly into the water. Over the decades, heavy metals and toxic organic chemicals mixed with the particles of rock, soil, and decomposing wood and shell in the sediments collecting in rivers and harbors in the Great Lakes Basin.
Even after serious clean-up efforts began in the late 1960's, little attention was paid to the toxics concealed on the bottom. The first priority was to stop the discharge of new contaminants, and little concern was paid to sediments. It was not until the early 1980's that environmental problems caused by sediment contamination began to generate interest. One example was an increase in concentrations of the pesticide DDT and the widely used group of industrial chemicals called PCBs in the tissues of Great Lakes fish. Although both of these chemicals had been banned from use within the Basin in the 1970's, levels were still increasing in fish tissue. This development sparked interest in the possibility of the sediments as sources of the toxics. Overwhelming evidence now supports the theory that toxics trapped in sediment can adversely impact humans and the environment. By a process known as biomagnification the toxics contained in bottom sediments can increase exponentially in concentration at every level of the food chain, starting with the sediment dwelling benthos, continuing to fish and eventually reaching birds of prey, mammals and even humans. This bioaccumulation of sediment pollutants in fish is one way for humans to become affected by the in place contaminants.
In response to rising concern regarding sediment quality in the Great Lakes, the U.S. Congress authorized a five-year study and demonstration project to identity the best techniques for addressing contaminated sediments. The authorization, contained in the Clean Water Act of 1987, called upon the Great Lakes National Program Office of the USEPA to conduct a study and demonstration project relating to the appropriate treatment of toxic pollutants in sediments. Also in 1987, the U.S. and Canada ratified a second revision of their 1972 Great Lakes Water Quality Agreement which directed the USEPA and its counterpart, Environment Canada, to establish methods to quantify, manage and remediate contaminated sediments.
In response to both policies, USEPA created the ARCS (Assessment and Remediation of Contaminated Sediment) Program. The specific aims of the ARCS Program were to measure concentrations of contaminants at chosen sites on the Great Lakes, to determine ways of gauging the effects of these concentrations on aquatic life, to recommend ways to measure risks to wildlife and to human health posed by the contaminants and to test technologies that might be used to clean up the sediments. Since the onset of the ARCS Program, state and federal agencies, environmental groups, industries and local citizens have worked together to identify contaminated sites, develop remediation plans and restore the sediments to safe levels for the ecosystem at numerous locations around the Basin.
As the process of realizing remediation occurs, it is important to keep all stakeholders apprised of actions that have been accomplished as well as to look ahead to the future. This document presents a summary of the past, current and future sediment remediation projects within the U.S. Great Lakes Basin. While the future will most certainly bring more sites to light, the sites listed here represent the majority of current, significant remediation projects. The summary demonstrates how far sediment remediation in the Great Lakes has progressed since the identification of contaminated sediment problems. It is hoped that this document will serve as a reference and promote information networking among the many people and agencies who work on remediating the Great Lakes sediments.