The Sierra Club has published a bulletin about how dredging is frequently the best mechanism to remove contaminated sediments from the ecosystem. The report offers an overview of when dredging makes sense, as well as an evenhanded discussion of different dredging technologies.
It concludes: “Dredging provides the only opportunity to remove contaminants from the aquatic ecosystem, often breaking their link to the food chain. It is the fastest way of achieving cleanup goals and restoring a site. New dredging technologies enable us to remove polluted sediments more quickly, cleanly, accurately and effectively than ever before.”
“Dredges designed specifically for removing contaminated sediments use special cutting heads and suction to reduce the amount of resuspension. These dredges have successfully removed sediments with extremely low resuspension rates.”
The report quotes Jan Miller, Environmental Engineer with the Chicago Office of the U.S. Army Corps of Engineers as follows:
“Don’t let the differences in dredge cost be the major factor in dredge choice. The physical constraints of the site, the type of dredging, and the ultimate fate of the dredged material are the critical factors that will determine the best dredge for the job.”
Finally, the report notes the following advantages of auger dredges compared to mechanical dredges for sediment removal:
Low resuspension compared to mechanical dredges.
Faster than mechanical dredges.
Closed system reduces environmental exposure.