1 Oct 2020

Development of a HEC-RAS Sediment Model for the Chippewa River, Wisconsin for Use in Predicting Future Dredging Activities

Purpose: This U.S. Army Corps of Engineers (USACE) Regional Sediment Management Technical Note (RSM-TN) describes the process of constructing and calibrating a sediment model that utilizes recent sediment data collection efforts performed by the U.S. Army Engineer Research and Development Center – Coastal and Hydraulics Laboratory (ERDC-CHL) and the U.S. Geological Survey (USGS) along the Chippewa River in Wisconsin. A USACE Institute for Water Resources (IWR), Hydrologic Engineering Center, River Analysis System (HEC-RAS, version 5.0.7) unsteady flow sediment model was developed to perform a continuous simulation of bed-load and suspended load transport and dredging operations through the Chippewa River and Lower Pool 4 of the Upper Mississippi River navigation channel. The resulting model developed through this effort can be useful in forecasting future channel maintenance needs through this reach of river.

1 Oct 2020

Hydrodynamic and Sediment Transport Modeling for James River Dredged Material Management

Abstract: The fate of material placed during dredging operations within the James River (Dancing Point-Swann Point reach) at a channel adjacent placement mound was modeled within this work. The study focuses on the potential migration of the placement mound into the channel as well as the transport of sediment resuspended during placement. A select combination of US Army Engineer Research and Development-developed models was utilized in this work to appropriately simulate hydrodynamic conditions, pipeline discharge near field suspended sediment estimates, far field transport of the pipeline discharge source term, and mound migration. Results show that the material released into the water column during placement remains in the placement area or is transported out of the area of interest downstream. A small fraction of sediment from the placement mound migrates into the channel after placement. The fine-grained nature of these sediments precludes these small volumes of sediment from depositing in the channel where the currents are strong.

1 Oct 2020

Barriers to Innovation in USACE

Abstract: The Dredging Operations and Environmental Research Program (DOER) of the United States Army Corps of Engineers (USACE) develops new tools and practices to support the efficiency, effectiveness, and sustainability of navigation dredging operations and then implements these new approaches (that is, innovations).We analyzed the innovation process to increase the adoption and implementation of new approaches and techniques. We then created a literature review of innovation diffusion theories and developed a mental model that identifies the actual and perceived barriers to innovation diffusion in USACE through a case study of its Navigation Program. We built the final expert mental model using interviews with 25 subject matter experts familiar with the program’s processes and external stakeholders. Interviewees reported environmental and budgetary constraints, time restrictions, and politics as the most common barriers to dredging innovation, including those based on the perceptions and beliefs of stakeholders rather than hard engineering or policy constraints (herein cognitive barriers). We suggest overcoming these barriers through changes in communication channels and social systems, such as public outreach through social media channels; interpersonal face-to-face meetings with decision makers; internal collaboration between local USACE districts and external collaboration with outside stakeholders, such as contractors and environmental regulators.

25 Aug 2020

PUBLICATION NOTICE: Insights: An Update of the USACE Data Strategy Initiative; November 2019 Edition

Abstract: The Data25 strategy was advanced in FY19 by the U.S. Army Corps of Engineers’ Chief Information Officer (USACE CIO) by funding pilots to show the power of data analytics on real USACE operations. This report details pilots that were conducted in three of USACEs Business Lines; Dredging, Hydropower, and Military Construction. The purposes for each of these pilots are listed below. 1. Enterprise value: Demonstrates the power of data analytics and its ability to generate business value by improving decision-making across the organization. 2. Technology value: Helps the CIO understand how cloud technology could support the overall data strategy. 3. Business value: Provides examples of data analytics in action. This view helps the Business Lines, Divisions, and Districts understand what it takes to supplement decision-making with insights generated from data. The main purpose of the pilots was to provide a glimpse of what could be gained from data analytics. From the initial business questions, the pilot Business Lines are seeking to use data to improve decisions through the automation of business processes, more rapid decision cycles, and the layering of previously siloed data on their own to reveal new insights.

25 Aug 2020

PUBLICATION NOTICE: New York/New Jersey Harbor Sedimentation Study: Numerical Modeling of Hydrodynamics and Sediment Transport

Abstract: The New York/New Jersey Harbor (NYNJH) is a vital economic resource for both the local economy and the entire US economy due to the vast quantity of imports and exports handled by the numerous ports in this waterway. As with most ports, there is a significant, recurring expense associated with dredging the navigation channels to the authorized depths. In an effort to determine the impact of channel enlargements (“the project”) on dredging volumes, a numerical model study was performed. The advantage of a numerical model study is the ability to isolate individual system modifications and associated impacts in terms of dredging volumes. Five years (1985, 1995, 1996, 2011, and 2012) were simulated for both the with- and without-project conditions to determine the impact of the channel deepening on the dredging requirements for a wide range of meteorological conditions including storm events. The numerical model results were analyzed to provide insight into which locations will experience increased/decreased deposition and quantify the amount of increase/decrease for a given channel reach. The model results indicate a relatively minor increase in the total dredge volumes for the NYNJH with the increase being insignificant in comparison to the natural variability in dredge volumes across years.

20 Aug 2020

PUBLICATION NOTICE: Sediment Sorting by Hopper Dredging and Pump-Out Operations: Sampling Methods and Analysis

Abstract: Hopper dredging operations for beach and nearshore placement typically include periods of overflow, which produces some degree of separation between the size fractions of the dredged sediment. The degree of separation and the controlling factors are presently poorly known. This report focuses on laboratory experiments aimed at determining (1) suitable sampling methods on a dredge, (2) composite sampling techniques to reduce analysis cost, (3) associated sampling intervals to achieve suitable sediment representation of a hopper load, and (4) a hydraulic means of sample splitting. Results showed that no statistical difference exists among the three methods used to sample the hopper weir overflow. The method used to sample deposited hopper sediment identified a bias in the percent fines that resulted from flow sheltering. Further, it was found that composited samples were able to quantify the concentration and percent fines accurately, although an analytical data experiment showed that the accuracy of a composited sample is dependent on the sampling intervals. The accuracy of the fines and concentration from a hydraulic sample splitter was found to be dependent on median grain size, with fine sediment being evenly distributed and coarser sediment increasing the error in concentration and grain size distribution.

30 Jul 2020

PUBLICATION NOTICE: Erosion Thresholds and Rates for Sand-Mud Mixtures

Abstract: Differences in erosion behavior of non-cohesive and cohesive sediments are widely recognized. In many natural environments, sand and mud are not completely separated and occur as mixtures. Significantly less research has been conducted on the erosion behavior of sand-mud mixtures compared to the separate treatment of sand and mud erosion. Sedflume erosion experiments were conducted on sand-mud mixtures with varying mud content to define the relationships between mud content, critical stress for erosion (τc), and erosion rate. Sand-mud mixtures were prepared with three mud sources: (1) non-swelling clay (kaolinite), (2) swelling clay (kaolinite/bentonite), and (3) a swelling, natural mud from the Mississippi River. Test results showed that critical shear stresses of the mixed sediments departed from that of pure sand with mud fractions on the order of 2% to 10%. Peak τc was observed between 30% to 40% mud content, with swelling muds achieving a ten-fold increase in τc while a five-fold increase in τc was measured for kaolinite. Additionally, this study demonstrated that the introduction of small amounts (≤5%) of mud to sand reduced erosion rates by a factor of 10 to 100. This observed abatement of erosion rate has implications for the use of dredged materials in civil and environmental engineering projects.

30 Jul 2020

PUBLICATION NOTICE: Investigation of Shoaling in the Federal Navigation Channel, Waukegan Harbor, Illinois

Abstract: Persistent and excessive shoaling occurs in the Outer Harbor and Approach Channel of the Waukegan Harbor, Illinois. This report describes a numerical modeling study performed for the US Army Corps of Engineers, Chicago District, to evaluate the existing harbor and 11 structural alternatives for three crest elevations. This report provides details of numerical modeling study, analysis of field data, and estimates of shoaling. The focus of the study is the investigation of a variety of structural solutions intercepting and/or diverting sediments to reduce shoaling in the navigation channel. These include breakwaters, groins, spurs, and structural extensions with varying length and crest elevation connecting to the north beach and existing north breakwater. Estimates of both shoaling volume and height are developed with and without project using an integrated wave-flow-sediment transport numerical modeling approach. Quantitative reduction estimates are provided for each structural alternative investigated.

25 Jun 2020

PUBLICATION NOTICE: Characterization of eroded mud aggregates with the Flume Imaging Camera System (FICS) and its added value to sediment management projects

Abstract: The goal of this technical note (TN) is to describe the functionality and added research value of the Flume Imaging Camera System (FICS), a US Army Engineer Research and Development Center (ERDC)-developed system designed to measure the size of sediment particles immediately following erosion.

25 Jun 2020

PUBLICATION NOTIFICATION: Effect of Tropical Storms and Precipitation on Dredging Volumes: Houston-Galveston, TX, and Mayport, FL

Abstract: This study characterizes infilling responses within dredged navigation channels to rainfall from tropical storms and hurricanes. This project created a web tool based on the methods described in this report. This report discusses the different analysis methods considered to relate storm and rainfall to dredging volumes at two pilot sites, Galveston, TX, and Mayport, FL. A comprehensive storm Impact Factor for hurricanes was developed to quantify the impact at a site based on proximity, duration, and wind speed. The methods vary based on the length and timing of periods of storms and rainfall prior to a dredge event. At Galveston, TX, when 2-year dredging volume totals were compared to hurricane activity occurring in the previous 2 years, the maximum dredging volume removed was higher after higher hurricane activity when compared to low activity periods. The average amount dredged was higher following periods of high hurricane activity. At Mayport, FL, dredging volumes were compared to hurricane activity occurring since the last dredging action took place. Similarly to Galveston, TX, the maximum dredging volume removed was higher after higher hurricane activity periods when compared to low activity periods. The average amount dredged was higher following periods of high hurricane activity.