31 Jul 2020

Boundary line maintenance to begin on Beaver Lake

The U.S. Army Corps of Engineers is advising landowners adjacent to public lands on Beaver Lake that contract work crews are currently conducting boundary line maintenance around Beaver Lake.

31 Jul 2020

Edward MacDowell Lake celebrates 70th year commemoration

 July 31 marks the 70th anniversary of the completion of the U.S. Army Corps of Engineers, Edward MacDowell Lake Dam. The project was completed in 1950 at a cost of $2,014,000 and is named after the late composer, Edward MacDowell. The dam, located on Nubanusit Brook in Peterborough, east of Keene, provides flood protection primarily to Peterborough. The project also provides flood protection to the downstream communities of Hancock, Bennington, Antrim, Deering, Hillsboro, and Henniker, all located on the Contoocook River.

31 Jul 2020

Public invited to comment on planned autumn releases from Rathbun Lake

In 2016 in response to stakeholder input, the Corps of Engineers revised its operating guidance for Rathbun Lake. The new guidance allows for an annual opportunity, every autumn, for the lake to schedule a release of water to benefit state and privately managed conservation and recreational areas downstream in the Chariton watershed. This release of water will not exceed 2,700 cubic feet per second from Rathbun Dam and would be sustained for no longer than 3 or 4 days, excluding ramp up and ramp down.

31 Jul 2020

Virtual public meetings set for Collier County study

The U.S. Army Corps of Engineers and Collier County, Florida, its nonfederal sponsor, have released the Collier County Coastal Storm Risk Management Draft Integrated Feasibility Report and Environmental Impact Statement.

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.

30 Jul 2020

PUBLICATION NOTICE: High-Performance Photocatalytic Degradation of Model Contaminants with Iron Oxide–Based Colloidal Solutions under Broad-Spectrum Illumination

Abstract:  Small molecule contaminants, such as compounds from pharmaceuticals, personal care products, and pesticides, persist through traditional wastewater treatment processes. Heterogeneous photocatalysis with transition metal oxides (TMOs) is an emerging technology for removing these recalcitrant contaminants from wastewater. To leverage this technology, we selectively combined three different TMOs with bandgap energies in different regions of the solar spectrum as a means of harvesting multiple wavelengths of incident radiation to increase the degradation rate of model and real contaminants. Specifically, we combined zincite (ZnO, ultraviolet active), hematite (α-Fe2O3, visible active), and tenorite (CuO, near-infrared active). The combination of tenorite and hematite (2:1 mass ratio) was the most effective, degrading methyl orange with a rate constant of 40±1E-03 min−1. When applied to multicontaminant solutions using laboratory illumination, our multispectral photocatalyst degrades real-world contaminants, methyl orange, carbamazepine, and nitrobenzene, with rate constants of 30±1E-03, 24±1E-03, and 6±1E-03 min−1, respectively. In addition, the material degrades contaminants with a greater efficiency under outdoor solar illumination, with Collector Area per Order values of 4.0, 6.1 and 14.5 kWh/order/m³, for methyl orange, carbamazepine, and nitrobenzene, respectively. These results demonstrate the effectiveness of this approach to purify water for strategic applications.

30 Jul 2020

PUBLICATION NOTICE: Environmental Analysis of Aqueous 3-Nitro-1,2,4-Triazol-5-One (NTO) by Ion Chromatography with Conductivity Detection

Abstract:  The newly fielded insensitive high-explosive compound 3-nitro-1,2,4-triazol-5-one (NTO) is mobile in the environment due to its high water solubility and low affinity for soils. The weak acidity of NTO (pKa 3.67) presents a challenge to environmental analysis by high-performance liquid chromatography but enables direct separation by ion chromatography (IC). Here we developed an IC method for NTO in natural water, soil, and postdetonation residue. A gradient potassium hydroxide separation effectively resolved the inorganic anions (F−, Cl−, NO2−, Br−, SO42−, NO3−, and PO43−) and NTO in 18 minutes. Suppressed conductivity of aqueous NTO was linear from 10 µg/L to 10 mg/L with a detection limit of 3 µg/L and quantitation limit of 9 µg/L. Recoveries of NTO-spiked natural water samples were 93%–118% at concentrations of 30, 100, and 500 µg/L. Recoveries of NTO-spiked soil samples were 91%–114% using deionized water (DI) extraction. NTO was completely recovered with DI-extraction in two postdetonation residue samples of IMX-101 but only partially recovered (58% and 69%) in two higher-concentration residues, potentially due to incomplete dissolution of the energetic particle matrix. These results support IC for confirmation analysis of environmental samples and for screening natural water samples while simultaneously analyzing inorganic ions.

30 Jul 2020

PUBLICATION NOTICE: A Comparison of Frost Depth Estimates from Ground Observations and Modelling Using Measured Values and Reanalysis Data for Vehicle Mobility 

Abstract: Frozen soils can withstand heavy vehicle loads and provide major maneuver corridors in locations where the soils are otherwise too weak to support the loading conditions. Vehicle mobility models require input of the ground conditions to assess seasonal traffickability. Increasingly, measured air temperatures from weather station locations are becoming more widespread, however they lack a global gridded coverage. Similarly, ground profile measurements, such as soil temperature and moisture, are significant inputs to estimate depths of frost. New data products, such as gridded reanalysis data provides weather and soil data on a gridded global scale. This study compared frost depths determined from measured soil temperatures at stations in North Dakota and Minnesota with frost depths determined from soil temperatures from NASA’s Modern Era Retrospective Analysis for Research Application Version 2 (MERRA-2). The objectives of the study were to evaluate the usefulness of the MERRA-2 data to provide estimates of frost depth, and to determine the accuracy of estimated frost depths from modelling using either measured air temperatures or reanalysis air temperature data. To estimate the maximum frost depth a one-dimensional decoupled heat and moisture flow model was used. Differences in estimated frost depth resulted from modelling when compared to the measured soil temperatures. These differences are likely due to the influence of a snow layer. The properties of the snow layer play an important role in estimating the depth of frost. Improved material properties of the snow layer are needed to more accurately estimate the depth of ground freezing.

30 Jul 2020

Corps awards contract to complete levee repairs on multiple levee systems in, Sheridan County, Wyoming

OMAHA, Neb. — The U.S. Army Corps of Engineers, Omaha District awarded a $3.55M construction contract to Relyant Global LLC of Maryville, Tennessee on July 24, for the rehabilitation of Little Goose Creek Left Bank,Big Goose Creek Right Bank and Goose Creek Right Bank Levee Systems damaged by the spring 2019 flooding. The duration of the contract is 150 days after the notice to proceed.