Use of Amendments for In Situ Remediation of Sediment

In Use of Amendments for In Situ Remediation of Sediment, you'll learn ...

• What are amendments and how they are used in sediment remediation
• Various methods for placing amendments
• The four most critical design considerations when selecting and implementing a sediment remedy using amendments
• How modeling and monitoring are used to effect a successful outcome when using amendments

Overview

Credit: 2 PDH

Length: 58 pages

Contaminated sediments are a significant, widespread environmental issue in surface waters throughout the United States. Historically, most sediment remedies have included dredging or excavation as a significant component of the remedy. Other strategies include monitored natural recovery and in situ capping. However, these strategies, whether employed exclusively or in combination, have limitations or drawbacks in terms of their cost-effectiveness or environmental impacts.

An emerging alternative in sediment remediation is the use of in situ amendments, in order to reduce bioavailability of contaminants by sorption or promote the degradation of the contaminants. This innovative technology is being developed and implemented to improve the risk reduction and cost-effectiveness of remedies at sediment sites.

Amendments are specialized materials that can be placed in different ways: directly upon the sediment surface, within a cap, or within a mat to minimize contaminant flux via sequestration and degradation. Some of the better developed amendments, such as activated carbon, have shown large reductions in the bioavailability of contaminants over months to several years with minimal impacts to benthic communities. Although uncertainty remains regarding the long-term effectiveness of these amendments, ongoing studies will continuously improve our understanding.

There are several factors to consider in selecting, designing, and implementing a sediment remedy using amendments. Sediment characteristics, contaminant fate and transport mechanisms, amendment characteristics, and placement methods are four of the most critical design considerations. Modeling is often used to predict the performance associated with these applications, while monitoring (both short-term and long-term) is conducted to ensure proper placement and performance are achieved.

This course is intended for environmental engineers who are interested in emerging techniques for remediating contaminated sites. It is assumed that the student possesses a basic knowledge of aquatic chemistry, hydrology, and environmental law.