6 May 2024

Monitoring Geomorphology to Inform Ecological Outcomes Downstream of Reservoirs Affected by Sediment Release

Abstract: Increasingly, reservoir managers are seeking techniques that improve sediment management while considering long-term sedimentation and reduced operational flexibility. These techniques, often termed sustainable sediment management, involve passing sediment through reservoirs and into downstream rivers. Conceptually, restoring sediment continuity can benefit ecosystem function by increasing floodplain connectivity, contributing to the heterogeneity of channel geomorphology, and supporting the continuity of nutrient cycling. However, when a change is made to operations, geomorphic changes may need to be monitored to document benefits and mitigate any unexpected effects of the change. This investigation develops a geomorphic monitoring plan for downstream reaches affected by sediment-release operations at reservoirs. The monitoring objectives are aligned with potential geomorphic change caused by changes to sediment supply and the associated effects on river function. A tiered approach is presented to explain the quality of information that can be assessed from increasing levels of data collection. A general conceptual model is described in which geomorphic data may be linked to physical habitat conditions and, therefore, ecological processes. The geomorphic monitoring plan for the Tuttle Creek Reservoir water injection dredging (WID) pilot project is presented as a case study. This technical note establishes a general framework for monitoring the design for sustainable sediment management in different ecological and geomorphic contexts.

30 Apr 2024

Evaluating Soil Conditions to Inform Upper Mississippi River Floodplain Restoration Projects

Abstract: The US Army Corps of Engineers (USACE) has designed and constructed thousands of acres of ecosystem restoration features within the Upper Mississippi River System. Many of these projects incorporate island construction to restore geomorphic diversity and habitat, including floodplain forests. Soils are the foundation of the ecological function and successful establishment of floodplain forests as they are the basis through which plants obtain water and nutrients and provide critical ecosystem services. To improve floodplain forest island restoration outcomes, three natural and four recently (<10 years) constructed restoration sites were studied to compare soil physical, chemical, microbial, and fungal characteristics. Constructed islands had lower soil organic matter and dissolved organic carbon and differed in nutrient concentrations, bacterial assemblages, and fungal communities compared to reference sites. However, soil enzyme activity and some microbial community characteristics were functionally similar between the natural and created sites. Results align with previously established restoration trajectory theories where hydrological and basic microbial ecosystem functions are restored almost immediately, but complex biologically mediated and habitat functions require more time to establish. Data from this and future studies will help increase the long-term success of USACE floodplain forest restoration, improve island design, and help develop region-specific restoration trajectory curves to better anticipate the outcomes of floodplain forest creation projects.

30 Apr 2024

Bioaugmentation for Enhanced Mitigation of Explosives in Surface Soil

Abstract: Residual munition constituents (MCs) generated from live-fire training exercises persist in soil and can migrate to groundwater, surface waters, and off-range locations. Techniques to mitigate this potential migration are needed. Since the MC hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) can be biodegraded, soil inoculation with RDX-degrading bacteria (i.e., bioaugmentation) was investigated as a means to reduce the migration potential of RDX. Metagenomic studies using contaminated soils have suggested that a greater diversity of bacteria are capable of RDX biodegradation. However, these bacteria remain uncultivated and are potentially a source of novel enzymes and pathways for RDX biodegradation. In situ soil cultivation of a novel soil array was used to isolate the uncultivated bacteria that had been inferred to degrade RDX. Approximately 10.5% of the bacteria isolated from the soil arrays degraded RDX by the aerobic denitration pathway. Of these, 26.5% were possibly novel species of RDX-degrading bacteria, based on 16S rRNA sequence similarity. Both cell encapsulation in hydrogels and coating cells onto granules of polymeric carbon sources were investigated as carrier/delivery approaches for soil inoculation. However, neither of these approaches could confirm that the observed RDX degradation was by the inoculated bacteria.

16 Apr 2024

Financing Natural Infrastructure: The Elizabeth River Project, Chesapeake Bay, VA

Purpose: Knowledge gaps surrounding natural infrastructure (NI) life cycles and performance thwart widespread implementation of NI in civil works projects. In particular, information about funding or financing the scoping, design, construction, monitoring, and adaptive management of NI projects constitutes a key need as there is no standard process for securing funds. This technical note is part of a series documenting successful examples of funding NI projects and sharing lessons learned about a variety of funding and financing methods to increase the implementation of NI projects. The research effort is a collaboration between the Engineering With Nature® (EWN®) and Systems Approach to Geomorphic Engineering (SAGE) programs of the US Army Corps of Engineers (USACE). This technical note explores how the Elizabeth River Project (ERP), a nonprofit organization based in Norfolk, Virginia, developed a homeowner cost-sharing program to fund NI projects—living shorelines, rain gardens, and riparian buffers—within an urban watershed.

16 Apr 2024

The Use of Rhodamine Water Tracer (RWT) Dye to Improve Submersed Herbicide Applications

Abstract: The inert fluorescent dye rhodamine water tracer (RWT) has been widely used in freshwater aquatic systems for many years to quantify bulk water exchange patterns and as a tracer for submersed herbicide movement. The dye is well-suited for tracer work due to its high solubility and detectability in water (<0.01 μg/L). Federal guidelines limit the aqueous concentration 0f RWT to <10 μg/L at drinking water intakes. The dye has proven to be harmless to aquatic organisms and humans in low concentrations and is relatively inexpensive. Since 1991, RWT has been used by Engineer Re-search and Development Center (ERDC) researchers to simulate aqueous herbicide applications in large, hydrodynamic systems in over 12 states. Such simulations have improved the effectiveness of herbicide treatments by linking in situ water exchange processes with appropriate herbicide selection and application rates. Understanding these parameters can be critical for mitigating herbicide exposure in environmentally sensitive settings and around potable water and irrigation intakes. A data-based estimate of water exchange patterns usually results in successful submersed herbicide applications—both with target-plant efficacy and limited injury to nontarget vegetation. Using RWT dye to simulate submersed herbicide applications is an important predictive and real-time tool in both experimental and operational settings.

9 Apr 2024

Embracing Biodiversity on Engineered Coastal Infrastructure through Structured Decision-Making and Engineering With Nature

Abstract: Extreme weather variation, natural disasters, and anthropogenic actions negatively impact coastal communities through flooding and erosion. To safeguard coastal settlements, shorelines are frequently reinforced with seawalls and bulkheads. Hardened shorelines, however, result in biodiversity loss and environmental deterioration. The creation of sustainable solutions that engineer with nature is required to lessen natural and anthropogenic pressures. Nature-based solutions (NbS) are a means to enhance biodiversity and improve the environment while meeting engineering goals. To address this urgent need, the US Army Corps of Engineers (USACE) Engineering With Nature® (EWN) program balances economic, environmental, and social benefits through collaboration. This report presents how design and engineering practice can be enhanced through organized decision-making and landscape architectural renderings that integrate engineering, science, and NbS to increase biodiversity in coastal marine habitats. When developing new infrastructure or updating or repairing existing infrastructure, such integration can be greatly beneficial. Further, drawings and renderings exhibiting EWN concepts can assist in decision-making by aiding in the communication of NbS designs. Our practical experiences with the application of EWN have shown that involving landscape architects can play a critical role in effective collaboration and result in solutions that safeguard coastal communities while maintaining or enhancing biodiversity.

4 Apr 2024

Cut and Capture System Technology for Demilitarization of Underwater Munitions

Abstract: Munitions are encountered in a variety of underwater environments as unexploded ordnance (UXO) or munitions and explosives of concern (MEC). These items can cause unacceptable explosive risks to critical infrastructure, recreational divers, and fishermen. The primary goal of the demonstrations was to validate an underwater suite of tools that can be used to render underwater UXO and MEC safe in shallow water (i.e., up to 100 ft). US Navy underwater ranges in the Gulf of Mexico, south of the Naval Support Activity–Panama City, were selected for the first two demonstrations to fully display the integrated system by processing inert munitions, such as the Navy 5 in./38 cal and the Army 105 mm High Explosive (HE) M1 projectile. The third demonstration, however, occurred at the Naval Surface Warfare Center (NSWC), Crane, Lake Glendora Test Facility, in Sullivan, Indiana. Twenty US Army 105 mm HE M1 projectiles filled with TNT were successfully processed. Overall, this project showed that Gradient Technology’s high-pressure waterjet demilitarization technology can be reliably operated underwater at depths less than 100 ft of seawater when the supporting equipment is located on the deck of a vessel or floating pier system.

3 Apr 2024

Deployable Resilient Installation Water Purification and Treatment System (DRIPS): Geoenabled Water Production and Disinfection Systems for Installations

Abstract: The Deployable Resilient Installation water Purification and treatment System (DRIPS) was delivered to aid an Organic Industrial Base in increasing their Installation Status Report–Mission Capacity (ISR-MC) score from black to green as part of a Course of Action (COA) within their Installation Energy and Water Plan (IEWP). DRIPS was also intended to help them be better prepared for the future in meeting their water and energy requirement goals for sustainment of critical missions. The IEWP ISR-MC requirements were met upon implementation of this project. Overall, the purpose of the DRIPS is to be a critical asset in disaster response and military operations, providing a reliable and effective means of producing potable water and disinfection in challenging and unpredictable environments. Its adaptability, mobility, and comprehensive water treatment capabilities make it an invaluable resource for addressing water-related emergencies and water disruptions and for sustaining critical missions. It also addresses a point of need by improving the ability to meet demands, reducing convoy requirements and the logistical footprint, facilitating the endurance of expeditionary forces, and ensuring the well-being of affected installations during times of disaster response, training operations, normal water disruptions, and emergency preparation.

2 Apr 2024

Evaluation of an Operational Demonstration of a Potential Aquatic Plant Control and Nutrient Mitigation Technology in Lake Okeechobee, Florida

Purpose: This technical note describes the findings from a field-demonstration project conducted in 2022 that aimed to mechanically harvest water hyacinth (Eichhornia crassipes (Mart.) Solms) in Lake Okeechobee, Florida; macerate the harvested plant material; and pump it as a slurry to a terrestrial disposal site as a potential novel technology to reduce total phosphorus (TP) in the system.

2 Apr 2024

Employing Ultrafiltration and Reverse Osmosis (UF/RO) for Treatment of Source-Separated Graywater: ER-201636

Abstract: In field operating environments, military units must ensure access to a critical water supply to maintain mission readiness. Increasing complexity of logistics and costs to transport water and climate change are driving the development and demonstration of water treatment units. The treatment unit described uses ultrafiltration (UF) and reverse osmosis (RO) membrane technologies with a disinfection step to treat low-strength graywater from shower facilities at Camp Shelby Joint Force Training Center in Hattiesburg, Mississippi. Samples were collected from human shower sampling events. During the demonstration, greater than 100,000 gal. of graywater were treated, supplied by two battalion training rotations over a 6-month period. Characterization of the source graywater continued throughout the system demonstration. Based on the literature, these are among the largest source-separated graywater sampling events to date. The combined treatment train of UF/RO met all compliance metrics for all analytes of interest for potability and met nonpotable metrics except for special use cases in three states. Both the quality of the treated water and the effective volume gains from an 85% multiplier effect directly support DoD water sustainment goals for both installations and operational environments.