11 Aug 2020

PUBLICATION NOTICE: Post-Project Monitoring of a Navigation Solution in a Dynamic Coastal Environment, Smith Island, Maryland: Year One of Post-Project Monitoring

Abstract: In 2018, jetties and a sill were constructed by the US Army Corps of Engineers (USACE) adjacent to the Sheep Pen Gut Federal Channel at Rhodes Point, Smith Island, Maryland. These navigation improvements were constructed under Section 107 of the Continuing Authorities Program. Material dredged for construction of the navigation structures and realignment of the channel were used to restore degraded marsh. Following construction and dredging, 1 year of post-project monitoring was performed to evaluate the performance of navigation improvements with respect to the prevention of shoaling within the Sheep Pen Gut channel, shoreline changes, and impacts to submerged aquatic vegetation (SAV). Given the short period of record after the completion of the navigation improvements, it was difficult to draw conclusions regarding stability of the channel, structures, and shoreline. Therefore, this report documents methodology and baseline conditions for monitoring, except for SAV, which was found to be potentially impacted by construction. A second year of monitoring was funded by the USACE Regional Sediment Management Program for fiscal year 2020. Findings can be used to inform plan formulation and design for USACE navigation projects by illuminating considerations for placement of structures to prevent shoaling and by informing SAV management decisions.

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.

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.

10 Jun 2020

PUBLICATION NOTICE: Nearshore Placement Workshop 2019: Sediment Nourishment of the Nearshore Environment

Abstract: The Coastal Inlets Research Program and the Regional Sediment Management Program co-sponsored the 2019 Nearshore Placement Workshop. Thirty-four participants from the US Army Engineer Research and Development Center (ERDC) and numerous districts met in Vicksburg on January 29–30, 2019, as a part of the workshop. This workshop was convened to facilitate discussions on concerns districts face regarding nearshore placements from resource agencies and stakeholders, challenges to placing sediment in the nearshore, and future research needs. The workshop included ERDC presentations on the state of the science regarding nearshore placements; specific implementations of nearshore placements within various US Army Corps of Engineers districts; break-out-style discussions on nearshore placement challenges and potential paths forward; and group discussions on metrics for success, quantification of benefits, Statements of Need (SON), and research priorities. A few of the major recurring themes throughout the workshop were the importance of monitoring, concerns over the fate of fine-grained sediment, and difficulties conveying the benefits of nearshore placements to a wide range of audiences. The workshop culminated in a discussion of possible SON to be put forth to the ERDC research and development community. This special report describes the discussions and outcomes of the 2019 Nearshore Placement Workshop.

27 Apr 2020

PUBLICATION NOTICE: Evaluation of the Potential Impacts of the Proposed Mobile Harbor Navigation Channel Expansion on the Aquatic Resources of Mobile Bay, Alabama

Abstract: This report assesses potential impacts to aquatic resources resulting from proposed navigation channel expansion activities within Mobile Bay, Alabama. This work was conducted for the U.S. Army Corps of Engineers (USACE) Mobile District, to support development of a supplemental Environmental Impact Statement. Changes in water quality and hydrodynamics were evaluated for potential impacts to benthic macroinvertebrates, wetlands, submerged aquatic vegetation, oysters, and fish. The assessment includes extensive characterization of baseline conditions, evaluation of estimated post-project conditions related to aquatic resource habitat (e.g., changes in salinity, dissolved oxygen). An analysis of potential impacts related to a 0.5-m sea level rise scenario were also evaluated. Results suggest that no substantial impacts in aquatic resources within the study area are anticipated due to project implementation, as the area of greatest potential changes to environmental conditions are already adapted to natural shifts in salinity (and other factors), and to conditions resulting from the existing navigation channel. Although sea level rise has the potential to alter aquatic resource habitats with Mobile Bay, additional impacts related to project implementation remain negligible under the 0.5-m sea level rise scenario.

22 Apr 2020

PUBLICATION NOTICE: Analysis of Nearshore Placement of Sediments at Ogden Dunes, Indiana

ABSTRACT: The harbor structures/shoreline armoring on the southern Lake Michigan shoreline interrupt sand migration. Ogden Dunes, Indiana, and the nearby Indiana Dunes National Lakeshore observed shoreline erosion due to engineered structures associated with Burns Waterway Harbor (east of Ogden Dunes) impeding natural east-to-west sediment migration. To remedy this, USACE placed over 450,000 cubic meters (m3) of dredged material post-2006 in the nearshore of Ogden Dunes. However, the effectiveness of nearshore placements for shoreline protection and littoral nourishment is not fully established. To improve nearshore placement effectiveness, USACE monitored the June/July 2016 placement and subsequent movement of 107,000 m3 of dredged material in the nearshore region at Ogden Dunes. This involved an extensive monitoring scheme (three bathymetry surveys, and two acoustic Doppler current profiler deployments), a Coastal Modeling System (CMS) numerical model of the changes following placement, and a prediction of sediment transport direction using the Sediment Mobility Tool (SMT). The SMT-predicted sediment migration direction was compared to observations. Observations indicated that between 10/11/2016 and 11/15/2016 the centroid of the sediment above the pre-placement survey moved 17 m onshore. These observations agreed with SMT predictions — onshore migration under storm and typical wave conditions. CMS accurately reproduced the hydrodynamic features.

20 Apr 2020

PUBLICATION NOTICE: Design considerations for beneficial use sites along the Channel to Victoria, Calhoun County, Texas

Purpose: This U.S. Army Corps of Engineers (USACE) Regional Sediment Management (RSM) investigation considered implementation of new or historically underutilized beneficial use (BU) sites for the Channel to Victoria (CTV) in Calhoun County, Texas. The utilization of alternative  placement areas is justified on two main grounds: (1) there is cost savings associated with the shorter pump distance compared to the existing upland confined placement areas and (2) shoaling reduction relative to a without project condition. Additional benefits realized by utilizing the proposed sites include (1) increased safety for vessels navigating CTV due to the reduction/elimination of open fetch and currents, (2) additional placement options available in times of emergency dredging, and (3) increased bird habitat, particularly for the endangered whooping crane. These sites have received National Environmental Policy Act (NEPA) clearance in previous project documents, and it is anticipated minimal or no additional NEPA coordination will be required to construct/restore these sites.

14 Apr 2020

PUBLICATION NOTICE: Update to: Use of Engineering With Nature® Concepts on the Savannah Harbor Navigation Project, Dredged Material Containment Areas, Savanna, GA

 NOTE: A new PDF for this report was uploaded on 2/20/2020 to correct an error that was in the previous version. The link to the report on Knowledge Core will still remain the same. If you have downloaded a version of the report prior to now please replace it with the new version now available.Link: http://dx.doi.org/10.21079/11681/35353  Report

1 Apr 2020

PUBLICATION NOTIFICATION: Thin Layer Placement of Sediments for Restoring Ecological Function to Submerging Salt Marshes: A Quantitative Review of Scientific Literature

 Link: http://dx.doi.org/10.21079/11681/35373Report Number: ERDC/TN-DOER-E44Title: Thin Layer Placement of Sediments for Restoring Ecological Function to Submerging Salt Marshes: A Quantitative Review of Scientific Literatureby Christine M. VanZomeren and Candice D. PiercyApproved for Public Release; Distribution is Unlimited January 2020Purpose:

3 Feb 2020

PUBLICATION NOTICE: Use of Engineering With Nature® Concepts on the Savannah Harbor Navigation Project, Dredged Material Containment Areas, Savanna, GA

 Link: http://dx.doi.org/10.21079/11681/35353 Report Number: ERDC/TN EWN-20-1Title: Use of Engineering With Nature® Concepts on the Savannah Harbor Navigation Project, Dredged Material Containment Areas, Savanna, GA By Michael P. Guilfoyle, J. Stevan Calver, Mary E. Richards, and Richard A. Fischer Approved for Public Release; Distribution is