20 Aug 2020

PUBLICATION NOTICE: Utilizing Stream Flows to Forecast Dredging Requirements

Abstract: In recent years, the United States Army Corps of Engineers (USACE) has spent an average of approximately a billion dollars annually for navigation channel maintenance dredging. To execute these funds effectively, USACE districts must determine which navigation channels are most in need of maintenance dredging each year. Traditionally, dredging volume estimates for Operations and Maintenance budget development are based on experiential knowledge and historic averages, with the effects of upstream, precipitation-driven streamflows considered via general-rule approximations. This study uses the Streamflow Prediction Tool, a hydrologic routing model driven by global weather forecast ensembles, and dredging records from the USACE Galveston District to explore relationships between precipitation-driven inland channel flow and subsequent dredged volumes in the downstream coastal channel reaches. Spatially based regression relationships are established between cumulative inland flows and dredged volumes. Results in the test cases of the Houston Ship Channel and the Sabine-Neches Waterway in Texas indicate useful correlations between the computed streamflow volumes and recorded dredged volumes. These relationships are stronger for channel reaches farther inland, upstream of the coastal processes that are not included in the precipitation-driven hydrologic model.

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.

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.

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 Number: ERDC/TN EWN-20-1 Title: 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 Unlimited January 2020 Purpose: This document summarizes the management approach for the Dredged Material Confinement Areas (DMCAs) (located in Jasper County, SCa) at the Savannah Harbor Navigation Project (SHNP) in the Savannah Harbor, Chatham County, GA. The LTMS was initiated to mitigate wetland losses in Georgia and South Carolina from ongoing dredged material deposition, harbor deepening efforts, and normal operating activities from maintenance of the Savannah Harbor. Since the inception and implementation of the LTMS in 1996, USACE has recognized that engineering operations, particularly those that involve dredged material deposition, can provide opportunities for infrastructure enhancement by applying improved engineering practices, and by incorporating natural features in the final product, which yield additional environmental benefits. The Engineering With Nature® (EWN) initiative incorporates both infrastructure development and enhancement with environmental management.  The purpose of this technical note is to: (1) summarize the creation and management of the DMCAs from implementation of the LTMS, (2) identify and describe features of the LTMS in common with EWN principles, and (3) discuss how this approach improves USACE’s ability to meet mission objectives while providing environmental benefits to the local and regional ecosystem.

1 Apr 2020

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

Purpose: The inundation of salt marshes, due in part to sea level rise, can result in elevation loss and a corresponding reduction in marsh ecological function. Several small-scale marsh restoration pilot projects have involved the addition of a thin layer of sediment to offset excessive inundation caused by loss of salt marsh elevation and resulting submergence. However, a comprehensive review, as well as a synthesis of project designs and the effects of sediment additions on ecological function, is lacking. This technical note reviews the impacts of thin layer placement of sediment on salt marsh ecological function and will serve as a resource for salt marsh restoration projects utilizing thin layer placement of sediments.

3 Feb 2020

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

This document summarizes the management approach for the Dredged Material Confinement Areas (DMCAs) (located in Jasper County, SCa) at the Savannah Harbor Navigation Project (SHNP) in the Savannah Harbor, Chatham County, GA.

27 Jan 2020

PUBLICATION NOTICE: Evaluation of Iron Sulfide Soil Formation Following Coastal Marsh Restoration – Observations from Three Case Studies

 Link: http://dx.doi.org/10.21079/11681/35275 Report Number: ERDC/EL TR-20-1Title: Evaluation of