20 Dec 2024

Upper Mississippi River Main Channel Sediment Placement: Purpose, Practice, Effects, and Recommendations

Abstract: Dredged-sediment management in the Upper Mississippi River and Illinois Waterway is constrained by environmental factors and regulations that limit where sediment can be placed. Regulations regarding in-water sediment placement are not consistent among states. In-water placement should be promoted because it keeps sediment in the system and reduces costs for managing sediment dredged from the river. Studies investigating the environmental effects of in-water placement generally conclude that sand-on-sand placement has minimal effect on aquatic resources in the dynamic riverine environment. This report discusses in-water sediment management techniques, including flow- and sediment-regulating structures (i.e., dikes and wing dams) and a bed-load sediment collector by-pass system.

5 Nov 2024

Improving Aquatic Placement Practices for Beneficial Use of Dredged Material in the Great Lakes

Abstract: The Great Lakes Navigation System is an economically critical waterway. To maintain safe and navigable waterways, approximately 3–5 million yd3 (2.3–3.8 million m3) of sediments are dredged annually. The US Army Corps of Engineers (USACE) and others now recognize that beneficial use of these sediments can achieve positive economic, environmental, and social outcomes. However, historically less than 25% of dredged sediments have been beneficially used in the nearshore environment. Improvements are needed in dredged material management practices in the Great Lakes to achieve the goal of using 70% of dredged sediments beneficially by 2030. Therefore, to overcome these challenges this report reviews beneficial use of dredged material projects with the goal of improving and in-creasing beneficial-use-placement practices in the Great Lakes. Identified needs to advance beneficial-use placement in the Great Lakes include the following: (1) improved modeling of sediment-placement methods; (2) better documentation regarding the cost, benefits, and drawbacks of various placement methods; (3) demonstration of some sediment-placement techniques used successfully in other coastal environments; and (4) monitoring before and after conditions, particularly for sediments that contain greater than 10% fines. Several demonstration projects should be implemented to obtain information addressing the data gaps.