6 Mar 2025

Norfolk Harbor Navigation Improvements Project: Modeling of Dredged Material Placement Schemes and Long-Term Sediment Transport at the Dam Neck Ocean Disposal Site

Abstract: US Army Corps of Engineers–Norfolk District requested assistance with the development and evaluation of dredged-material-placement schemes that evenly distribute placed material and avoid or minimize unacceptable mounding in accordance with the site management and monitoring plan. A multiple placement fate and transport modeling study was conducted to determine the optimal placement plan for dredged material from Thimble Shoals Channel and Atlantic Ocean Channel at the Dam Neck Ocean Disposal Site (DNODS). Provided the large volume of dredged material to be placed at DNODS over a short duration during the construction period, a modeling study was performed using the Geophysical Scale Multi-Block (GSMB) modeling system to determine the transport and fate of placed dredged material at the DNODS that is resuspended by currents and waves over a 2-year period. Six scenarios were undertaken to determine the best path forward. Scenarios 1 and 4 were excluded due to high exceedance of the depth threshold. Scenarios 2, 3, 5, and 6 yielded an approximate 1%–2% dispersal of placed materials from the DNODS during ambient environmental conditions; Scenario 6 yielded the least. Most dispersion occurred during two simulated hurricanes. The model findings generally support the DNODS Environmental Impact Statement and site-designation documents.

19 Feb 2025

Lower James River Sediment Transport Modeling: Jordan Point

Abstract: US Army Corps of Engineers–Norfolk District (NAO) requested assistance from the US Army Engineer Research and Development Center (ERDC) to examine currently used placement sites within the James River, Virginia, initiative area, determine potential risk to critical environmental receptors during placement, and predict the life cycle of the placement sites. The focus of the analysis within this work is the Jordan Point placement site. The far-field, fate-transport modeling at Jordan Point shows relatively low maximum values of suspended sediment concentration (less than 40 mg/L) and deposition values (less than 0.2 cm). Material that is placed at Jordan Point appears to quickly disperse through the system, depositing in thin layers at specific areas. The life-cycle analysis performed for the Jordon Point placement site yielded an estimated useable project life of the Jordan Point placement sites of 26 years with an uncertainty of ±4 years. Analysis showed that 97% of the net sediment deposition in the navigation channel in proximity to this site is from the upper James River, 2% is from downstream sources, and 1% is from the two Jordan Point placement sites.

3 Feb 2025

Notes on Bedload Sediment Collector Deployment: Eau Claire River, Wisconsin

Purpose: A bedload sediment collector field deployment was conducted during low flow conditions from August 2023 to September 2023 on the Eau Claire River, Wisconsin, to assess the operation and performance of a 12 ft bedload sediment collector (BSC). This initial deployment of the technology served to familiarize the research team with the new 12 ft BSC system in preparation for its potential deployment during high flow conditions and at other locations. The insights from this study are intended to identify opportunities to use this technology, particularly in the Upper Mississippi River navigation system.

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.

27 Sep 2024

Beneficial Use of Dredged Sediment in South St. Paul, Minnesota: 100 Years of Economic, Social, and Environmental Innovation

Purpose: This technical note provides a review of beneficial use (BU) of dredged sediment in a 5-mile river reach of the Upper Mississippi River System (UMRS) that demonstrates the triple-win solutions championed by the US Army Corps of Engineers (USACE) Engineering With Nature® Program. Several case studies exemplifying the BU of dredged sediment are presented along with a more in-depth review of the Pigs Eye Lake Islands ecosystem restoration project.

5 Sep 2024

Next-Generation Water Quality Monitoring during Dredging Operations: Knowns, Unknowns, and Path Forward

Abstract: Water quality monitoring data are routinely collected during dredging and placement operations to address various state and federal requirements, including water quality standards, with the intention of protecting ecosystem health. However, such efforts may be limited by the lack of a standardized national strategic focus and user-friendly streamlined interfaces to interpret the data. Inconsistencies in how and what data are collected and lack of consensus on scientifically backed biological-effects thresholds make it difficult to quantify potential dredging operations impacts (or lack thereof) both within individual projects over time and across multiple projects of differing characteristics. Summarized herein is an initial effort to define a scientifically backed path forward to improve the value of current and future water quality monitoring and management decisions based on water quality data collected. The provided turbidity data were generally below applicable state thresholds for two case studies but for a third case study did periodically exceed thresholds at depth. This includes providing rationale for strategic focus on the most relevant dredging operations and projects, based on three general site-specific data categorizations: (1) sediment type, (2) dredge type, and (3) ecosystem type.

22 Aug 2024

Application of Existing Tools to Systematically Identify Nearshore Placement Sites for Beneficial Use of Navigation Sediments in Lake Michigan

Purpose: The Great Lakes includes 140 federally maintained harbors with an annual dredging program of 2–4 million cubic meters (3–5 million cubic yards)[1] of sediment. Many small harbors are not dredged regularly, and there is an undredged backlog of over 9 million cubic meters (12 million cubic yards) of sediment (USACE-LRD 2021). Current policy (Spellmon 2023) is to maximize the beneficial use (BU) of sediment, with a goal of beneficially reusing 70% of the federal navigation dredging volume by 2030 (that is, the 70/30 goal). In the Great Lakes, clean sands have often been placed on beaches or in the nearshore littoral zone to beneficially nourish the shoreline, but since many harbors are not dredged regularly, no plans exist to beneficially reuse dredged sediments. This lack of existing BU plans is particularly true for harbors with finer grained or mixed sediment. To achieve the 70/30 BU goal and support navigation maintenance and coastal management requires a strategic and systematic approach to identifying BU sites. The purpose of the technical note is to (1) provide an approach to identify potential nearshore placement sites using existing information and models; (2) describe available tools for placement site identification, coastal condition information, and the long-term fate of the sediment; and (3) provide a pertinent case study to describe this approach in practice.

21 May 2024

Site Selection and Conceptual Designs for Beneficial Use of Dredged Material Sites for Habitat Creation in the Lower Columbia River

Abstract: Channel maintenance in most major rivers throughout the United States requires ongoing dredging to maintain navigability. The US Army Corps of Engineers explores several options for placement based on sediment characteristics, material quantity, cost, operational constraints, and minimization of potential adverse effects to existing resources and habitat. It is a priority to beneficially reuse dredged sediments to create habitat and retain sediments within the river system whenever possible. Nonetheless, there can be discrepancies among state and federal resource agencies, landowners, tribes, and various other stakeholders about what constitutes a benefit and how those benefits are ultimately weighed against short- and long-term tradeoffs. This work leveraged prior Regional Sediment Management efforts building consensus among stakeholders on a suite of viable strategies for in-water placement in the lower Columbia River. The goal was to identify suitable locations for applying the various strategies to maximize habitat benefits and minimize potential adverse effects. A multistep site-selection matrix was developed with criteria accounting for existing site conditions, overall placement capacity, tradeoffs, long-term maintenance, cost, stakeholder concerns, and landscape principles in the context of other habitat restoration projects implemented in the lower river. Three highly ranked sites were selected for conceptual design and exemplify results of collaborative beneficial use implementation.

17 May 2024

Rolling Prairie, Minnesota, Beneficial Use Area: A 100-Year Plan for Multiuse Land Management and Restoration Using Dredged Sediment

Purpose: Inland waterway dredged sediment management is challenged by a lack of capacity in existing dredged material confined disposal facilities (CDFs) and a lack of available land to place sediment near frequently dredged navigation channels. Navigation operation and maintenance (O&M) dredging, material management, and coordination costs are increasing, and alternative long-term solutions are required. In response, the US Army Corps of Engineers (USACE), St. Paul District has addressed the challenge by investigating regional sediment management and beneficial use of dredged material when updating navigation pool–specific dredged material management plans (DMMP). The recently completed Pool 5 DMMP planning identified a 950 acre (384 ha)[1] placement site consisting of several land parcels available from willing sellers that will accommodate a “100-year plan” for dredged material management (USACE 2019). This technical note describes the multiple-use site plan that creates sand prairie and wetland habitat, provides public access to sand stockpiles, and implements agriculture studies with the University of Minnesota to evaluate the benefits of dredged material (i.e., sand) amendments in alluvial cropland soils, which has not been widely investigated. The Rolling Prairie site will demonstrate benefits of “distributed DMMPs” in which thin-layer placement on agricultural land near dredging locations can supplement traditional disposal methods. It also shows the advantage of having a large placement site to achieve multiple objectives.