An evaluation of the standard elutriate test as an estimator of contaminant release at the point of dredging

Abstract

While release of contaminants during dredged material disposal operations has long been the subject of environmental concern, the potential release of pollutants during the dredging process has recently come under the scrunity of federal and state regulatory agencies. The mechanical action of a dredging operations causes resuspension of sediment particles and release of soluble contaminants to the water column. A predredging test is essential to estimate the amount of soluble release at or near the point of dredging to ascertain potential water quality impact. The Standard Elutriate Test has proven to be a good estimator of soluble contaminant release for dredged material disposal operations and researchers have recognized that the processes involved at the point of dredging are similar to those involved with the open-water disposal of dredged material.

This research is an evaluation of the Standard Elutriate Test as an estimator of soluble contaminant release at the point of dredging. Data and field studies were conducted by the U.S. Army Corps of Engineers Waterways Experiment Station at five sites around the United States. A direct comparison was made between elutriate test data from predredging bottom sediment and water sample analysis taken at or near the point of dredging.

The Standard Elutriate Test satisfactorily predicted the release of soluble contaminants at or near the point of dredging in four out of the five sites in this study. The fifth site had extenuating circumstances that may account for the failure at this site. In this investigation, the elutriate test appears to overestimate the release of organics, nutrients and some heavy metals (Hg, Mn, Fe, and Cr).

Statistical analysis provided a predictive equation that can be used to estimate the upper-bound value a constituent concentration will approach based on elutiate test data and a specified confidence level.