1 Oct 2020

Eutrophication Management via Iron-Phosphorus Binding

Abstract: The presence of phosphorus (P) in excessive quantities can lead to undesired conditions, such as cyanobacterial/algal bloom. The over-enriched hypertrophic conditions or the excess amounts of nutrients (nitrogen and P, P being the primary nutrient of concern) are the major cause of harmful cyanobacterial blooms, which can be toxic and can also lead to oxygen depletion and anoxic respiration (hypoxia) in the hypolimnion. The presence of iron compounds has been shown to bind phosphorus and diminish harmful algal blooms. Therefore, an iron-plates-packed reactor has been designed to reduce P in surface water. This cost-effective and easy-to-install system has shown promising results in phosphorus reduction.

1 Oct 2020

Physical Factors That Influence Muddy Bed Aggregate Production, Size, and Durability

Abstract: Aggregation state significantly influences the transport characteristics of fine sediments. While research has documented the presence of mud aggregates in multiple coastal and estuarine environments, bed aggregates are largely absent from numerical models used to predict cohesive sediment transport. The U.S. Army Corps of Engineers (USACE) is conducting studies to evaluate the impact muddy bed aggregates have on sediment management issues, and how to account for aggregates in numerical models. In this study, physical properties associated with cohesive behavior were evaluated to determine if they could be used as predictors for bed aggregate production, size, and durability. Results showed that aggregates were consistently produced in cohesive sediments, and that median aggregate size was ~10-450x larger than the disaggregated sediment. Clay content had strong correlation with relative aggregate size, though statistically significant correlations were also found with sand content, water content, and density. Durability testing indicated that aggregate break-up followed exponential models, and that in limited instances, rates of break-up correlated with organic content.

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

Microbiological Indicators Reflect Patterns of Life

Abstract:  Resolving patterns of human movement, specifically for actors of interest, in an urban environment is an extremely challenging problem because of the dynamic nature of human movement. This research effort explores a highly unconventional approach, addressing residual or lingering signatures of interest to the Army in an urban operation. Research suggests that unconventional signatures commonly associated with human presence or prior occupation of a space, such as microbes attached to skin cells or in the gut, may linger for an extended amount of time. In this scoping study, our objectives were to detect microbial communities in the built environment, to examine microbial community composition, and to investigate the longevity of a microbial signature. To do so, we conducted a controlled study to obtain a mechanistic understanding of the fidelity of the biological signatures in the built environment, with a particular focus on their longevity and stability.

1 Oct 2020

Development of a General Anadromous Fish Habitat Model: Phase 2: Initial Model Quantification

Abstract: The General Anadromous Fish Habitat Model (now the General Salmonid Habitat Model) was developed to assist in the plan formulation process for ecosystem restoration and mitigation projects. The model generates relative differences in habitat quality between proposed alternative future scenarios. In order to provide model development transparency, this report presents the initial quantification phase of the model development process. The draft model depicted in this report is scalable, meaning various parameters may be measured at different landscape scales (for example, reach vs. watershed). The model can be applied (model domain) in watersheds that currently or previously supported salmonid fish species. Application outside of the model domain would need further evaluation to ensure appropriate sensitivity to the new system of interest. Although the model is being developed to explicitly capture changes in fish habitat in response to restoration actions, this model would be appropriate for use in any planning project focused on the restoration of streams, rivers and, estuaries (for example, dam removals, in-stream habitat enhancement), because the parameters are measures of ecosystem level structure, function, and process.

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.

1 Oct 2020

Method Selection Framework for the Quantitation of Nanocarbon Scientific Operating Procedure Series (SOP-C-3): Selection of Methods for Release Testing and Quantitation of Solids, Suspensions, and Air Samples for Carbon-Based Nanomaterials

Abstract: There is significant concern regarding the health and safety risk of nanocarbon (for example, nanotubes, graphene, fullerene), and the cur-rent capability gap for accurately determining exposure levels encumbers risk assessment, regulatory decisions, and commercialization. Given the various analytical challenges associated with the detection and quantitation of nanocarbon, it is unlikely that a single method or technique will prove effective for all forms of nanocarbon, all exposure scenarios, or all possible environmental systems. The optimal approach, or series of techniques, will likely depend on the nature of the material being measured, its concentration, and the matrix in which it is contained. In this work, a preliminary decision framework is presented that assists the user in deter-mining which analytical methods are best suited for a given sample.

1 Oct 2020

Acid Sulfate Soils in Coastal Environments: A Review of Basic Concepts and Implications for Restoration

Abstract: Acid sulfate soils naturally occur in many coastal regions. However, the oxidation of acid sulfate soils can decrease soil pH to <4.0, affecting vegetation and aquatic organisms. Acid sulfate soil oxidation typically occurs where anaerobic sediments or soils were exposed to aerobic conditions (for example, extended drought, artificial drainage, or dredged material placement in upland areas). Recently, field observations documented the formation of acid sulfate materials at multiple degraded marsh restoration locations (Rhode Island, New Jersey, California) following intentional dredged sediment placement into wetland environments designed to increase marsh elevation. Unlike previous studies of acid sulfate soils, the in situ dredged material did not contain acid sulfate–bearing materials at the time of placement; instead, the interaction between the marsh substrate and the overlying dredged material appears to have caused the formation of acid sulfate soils. These findings highlight the need for additional studies of acid sulfate soil formation and fate—especially within a marsh restoration context. In response, this report provides a review of literature related to acid sulfate soils, discusses preliminary data collected to evaluate acid sulfate material formation following marsh restoration, and identifies knowledge gaps requiring additional research and technical guidance.

1 Oct 2020

Optimization of LC-MS/MS Parameters for Analysis of Per- and Polyfluoroalkyl Substances (PFAS)

Purpose: Integrate US Environmental Protection Agency (USEPA) Method 537 on current instrumentation to provide per- and polyfluoroalkyl substances (PFAS) analytical capabilities for the US Army Engineer Research and Development Center (ERDC), US Army Corps of Engineers (USACE) and the Department of Defense (DoD).