Search Results (17)

This study explores the stabilization of dredged sediments classified as lean clay (CL) using hydrated lime, type III Portland cement, and compaction. While quicklime is commonly used in practice, this research explores alternative calcium-based binders with the aim of valorizing sediments for civil engineering applications. The mechanical behavior of the treated materials was evaluated through an Unconfined Compressive Strength (UCS) test campaign, with the results interpreted using the porosity/volumetric cement content ($\eta /C_{iv}$) index. This relationship assesses the influence of apparent dry density and cement content on the strength improvement of sediments, aiming to evaluate the suitability of the dredged sediments for engineering applications. A key feature of this study is the extended curing period of up to 90 days, which goes beyond the typical 28-day evaluations commonly found in the literature. Interestingly, strength degradation occurred at advanced curing ages compared to shorter curing times. To understand the mechanisms underlying this resistance degradation, the mixtures were subjected to X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). These tests identified the presence of the expansive sulfate-based compound ettringite, which is associated with swelling and failure in soils stabilized with calcium-based stabilizers. This research contributes to the field by demonstrating the limitations of calcium-based binders in stabilizing sulfate-bearing dredged materials and emphasizing the importance of long-term curing in assessing the durability of treated sediments. Full article

Driven by the need to expand urban/industrial complexes, and/or mitigate anticipated environmental impacts (e.g., tropical storms), many coastal countries have long implemented large-scale land reclamation initiatives. Some areas, like coastal Louisiana, USA, have relied heavily on restoration activities (i.e., beneficial use of dredged material) to counter extensive long-term wetland loss. Despite these prolonged engagements, the quantifiable benefits of these activities have lacked comprehensive documentation. Therefore, this study leveraged remote sensing data and advanced machine learning techniques to enhance the classification and evaluation of restoration efficacy within the wetlands adjacent to the Mississippi River’s Southwest Pass (SWP). By utilizing air- and space-borne imagery, land and water data were extracted and used to compare land cover changes during two distinct restoration periods (1978 to 2008 and 2008 to 2020) to historical trends. The classification methods employed achieved an overall accuracy of 85% with a Cohen’s kappa value of 0.82, demonstrating substantial agreement beyond random chance. To further assess the success of the SWP reclamation efforts in a global context, broad-based land cover data were generated using biennial air- and space-borne imagery. Results show that restoration activities along SWP have resulted in a significant recovery of degraded wetlands, accounting for approximately a 30 km² increase in land area, ranking among the most successful land reclamation projects in the world. The findings from this study highlight beneficial use of dredged material as a critical component in large-scale, recurring restoration activities aimed at mitigating degradation in coastal landscapes. The integration of remote sensing and machine learning methodologies provides a robust framework for monitoring and evaluating restoration projects, offering valuable insights into the optimization of ecosystem services. Overall, the research advocates for a holistic approach to coastal restoration, emphasizing the need for continuous innovation and adaptation in restoration practices to address the dynamic challenges faced by coastal ecosystems globally. Full article

Anthropogenic activity leads to changes in sediment dynamics, creating imbalances in sediment distributions across the landscape. These imbalances can be variable within a littoral system, with adjacent areas experiencing sediment starvation and excess sediment. Historically, sediments were viewed as an inconvenient biproduct destined for disposal; however, beneficial use of dredge material (BUDM) is a practice that has grown as a preferred methodology for utilizing sediment as a resource to help alleviate the sediment imbalances within a system. BUDM enables organizations to adopt a more innovative and sustainable sediment management approach that also provides ecological, economic, and social co-benefits. Although location data are available on BUDM sites, especially in the US, there is limited understanding on how these sites evolve within the larger landscape, which is necessary for quantifying the co-benefits. To move towards BUDM more broadly, new tools need to be developed to allow researchers and managers to understand the effects and benefits of this practice. The National Exposed Sediment Search and Inventory (NESSI) was built to show the capability of using machine learning techniques to identify dredged sediments. A combination of satellite imagery data obtained and processed using Google Earth Engine and machine learning algorithms were applied at known dredged material placement sites to develop a time series of dredged material placement events and subsequent site recovery. These disturbance-to-recovery time series are then used in a landscape analysis application to better understand site evolution within the context of the surrounding areas. Full article

This paper investigates the preparation and properties of high-strength artificial blocks made from dredged silt with a clay content of 52.0%. A comparative analysis of the mechanical properties of dredged silt blocks produced using semi-dry pressing and vibration molding methods was conducted. The study examined the effects of using fly ash (FA) and ground granulated blast-furnace slag (GGBS) as substitutes for cement on the compressive strength, splitting tensile strength, and dry shrinkage of the blocks. Additionally, the microstructure of the dredged silt blocks was analyzed using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and thermogravimetric analysis. The results show that specimens prepared using the pressing method exhibit better mechanical performance with compressive and splitting tensile strength reaching 64.8 MPa and 5.6 MPa at 28 d, respectively, which increased by 111.07% and 143.48% compared to specimens prepared through vibration molding. The addition of FA and GGBS reduces the early strength of the block to a certain extent but without a significant adverse effect on later strength. GGBS demonstrates faster hydration and a better filling effect. The addition of GGBS or FA refines the pore structure and reduces the diameter of pores in the paste, which is beneficial for improving the dry shrinkage performance of the block. At 120 d, the dry shrinkage of blocks containing 50% FA and GGBS shows a reduction of 29.7% and 27.1%, respectively, compared to blocks made with cement. The properties of the silt blocks can be notably enhanced through mechanical force, particle gradation, and hydration action. The preparation of artificial blocks such as road bricks and ballast blocks using dredged soil as the main raw material has been applied in projects such as the Yangtze River waterway regulation in China and Skikda Port in Algeria. Full article

Sea level rise and natural disasters, such as hurricanes and tropical storms, are resulting in coastal erosion-related problems across the US. Beach nourishment is one of the most commonly adopted solutions for erosion mitigation. Borrow sources for nourishment are often from offshore or upland mines. However, in some areas, sediment availability from known borrow sources is becoming scarce. This suggests that sediment should be considered a non-renewable resource within the framework of long-term planning and coastal management decisions. Regional Sediment Management (RSM), or the beneficial use of dredge material (BUDM), targets inlets for borrowing material and can also be a more cost-efficient strategy that has widely been supported by the US Army Corps of Engineers as a system-based approach. However, not all states have embraced this approach, and a national-scale evaluation of these projects in coastal management and adaptation is needed. This study examines past RSM/BUDM projects in the top ten most highly nourished states in the US and compares those trends to a selection of minimally nourished states from different coasts. Based on the historical trends identified, the volume of sediment required for future RSM/BUDM projects in these areas over the next 50 years is predicted using Auto Regressive Integrated Moving Average (ARIMA) models. Although growth in the total number of RSM/BUDM projects was measured over time, there was a decline in the volume of sediment placed for these projects. Results of the forecasting model suggest that CA, NC, and the FL Gulf Coast could require the highest volume of sediments for RSM/BUDM activities over the next 50 years. Based solely on proximity to inlets for sediment resources, DE, FL Atlantic, and NJ coasts are potential beaches that can increase BUDM activities. This study aims to provide a framework to evaluate the suitability of future RSM/BUDM projects in efforts to mitigate coastal erosion. Full article

In France, the annual volume of dredged sediments is significantly increasing, which has become a real environmental problem. Nevertheless, these sediments can be used beneficially as supplementary cementing material. On the other hand, external sulfate attack is one of the most aggressive causes of deterioration that affects the durability of concrete structures. This study focused on the valorization of river-dredged sediments from Noyelles-Sous-Lens (Hauts-de-France) as a mineral addition in substitution of Portland cement, and it studied their impacts on the mechanical behavior and durability of reinforced mortars. X-ray diffraction (XRD) analysis indicated the presence of clay minerals in the raw sediment. In order to activate this clay fraction, flash calcination was applied at a temperature of 750 °C. In addition, four mixed mortars were formulated by mixing a Portland cement (CEM I 52.5 N) and the calcined sediments as a partial substitute for cement with proportions of 0%, 15%, 20%, and 30%, then stored in water tanks at room temperature (20 ± 2 °C) for 90 days in order to immerse them in a tank containing a 5% MgSO₄ solution and to track the evolution of their corrosion potential as well as their mass variations every 20 days for a period of 360 days. The following additional tests were carried out on these mortars: tests of resistance to compression and flexion and to porosity by mercury intrusion. The results obtained from the majority of these tests showed that the mortar containing 15% calcined sediments is as effective and durable as the reference mortar itself. The main conclusion we can draw from these results is that the presence of these calcined sediments improves the overall behavior of the mortar. Full article

This study systematically examined dredged materials from various aspects, including their sources, the volume generated annually, beneficial uses, and the management processes currently practiced. In addition, this paper presents the relevant policies governing the dredging, reuse, and disposal of dredged materials in the United States. A summary of various sources, types/classifications, and the physical and chemical properties of dredged materials used by various researchers are presented. This paper also summarizes the innovative techniques for the beneficial reuse of dredged materials in a wide range of applications in concrete materials, construction products, roadway construction, habitat building, landfill liner/cap, agriculture soil reconstruction, and beach nourishment. Further, limitations and corresponding solutions related to the beneficial use and management of dredged materials were provided in the end. Full article

Dredged river sediments produce a huge volume of mineral materials, which could be incorporated into building materials. Considering the raw sediment preparation, mineral processing techniques fit perfectly to this purpose. This work describes two procedures to prepare river sediments, according to the final beneficial use. The first is a dry procedure of deagglomeration to prepare river sediments with the aim of being incorporated into a concrete formulation to build a bicycle path. A large amount of deagglomerated sediment was prepared, requiring upscaling of the deagglomeration process. Successive steps of sieving and roll crushing were used to obtain deagglomerated sediments. To use it as raw material to produce pozzolanic materials and lightweight aggregates, a second procedure consisting of a wet classification at 63 µm was carried out. Steps of wet sieving, followed by hydrocycloning and screw classifying, were used to prepare several silt fractions under 63 µm. Full article

An unprecedented rate of construction has profoundly increased the risk of scarcity of natural resources and threatened ecosystem sustainability. To establish an effective sustainable development policy, it is imperative to promote the use of responsible production channels, including waste recycling. Reuse of harbor dredged sediment is commonly investigated as a valuable alternative to non-renewable natural resources needed for construction. Sediment characterization is decisive in the valorization process, aiming to identify potential recycling paths. Existing research efforts, however, have rarely investigated case studies in developing countries. Moreover, they have tended to focus on the technical aspects, ignoring economic feasibility, which carries important implications. This paper fills this gap first by meticulously selecting laboratory tests for characterization within the means available in developing countries and second by conducting a cost-benefit analysis. The port of Safi, Morocco, was chosen for the implementation of the adopted approach. Results showed that dredged sediment is a sand readily reusable as a construction aggregate. Several applications are possible, the most interesting one being concrete works, as a substitute for conventional sand. While treatment by washing and dehydrating proved necessary, cost-benefit analysis confirmed the profitability of recycling. Hence, beneficial reuse of dredged sediment as construction material is technically and economically feasible. Full article

Marine sediments may easily accumulate contaminants, posing a high risk to human health and biota. Beneficial use applications exist for natural sediments and sediments contaminated with organic and inorganic pollutants. In this research, the term marine sediments (MSs) was used to refer to all marine sediments, which could be clean, natural marine sediments, as well as contaminated marine sediments and dredged materials, as the main focus of this research. Sediment remediation often involves costly and time-consuming processes. Assessment frameworks are essential for selecting suitable remediation alternatives for MSs. This research aims to provide regulatory frameworks for the sustainable beneficial use of all marine sediments. No studies have been reported on this issue in Colombia until now. The current states of marine sediments on the Colombian Caribbean Coast were mainly investigated. Concentrations of specific harmful heavy metals (HHMs) in Colombia’s sediments were higher than the environmental standards of various nations. Ex situ remediation technologies were evaluated through cost–benefit analysis and environmental feasibility to be adopted in Colombia. The results identified solidification/stabilization (S/S) as promising technologies. Sustainable remediation of MSs may offer ample opportunities for environmental enhancement and economic benefits. Continuous research and adopting appropriate environmental regulations, such as the London Protocol 1996, would contribute to effectively managing all marine sediments in Colombia. More innovative and cost-effective remediation technologies with beneficial uses would still be needed. Decision makers may use the proposed frameworks to select optimal remediation alternatives and implement sustainable MSs management by achieving their beneficial uses. Full article

Nearshore nourishment is a common coastal flood risk management technique that can be constructed beneficially by using dredged sediment from navigation channels. A nearshore nourishment project was completed during the summer of 2021 in Harvey Cedars, NJ, USA, with 67,500 m³ of dredged sediment from Barnegat Inlet placed along approximately 450 m of beach in a depth of 3–4 m. In situ instruments were installed to monitor hydrodynamic conditions before and after dredged material placement, and nine topographic and bathymetric surveys were conducted to monitor nearshore morphological response to the nourishment. Shoreline location was extracted from satellite imagery using CoastSat software to compare historical trends to the shoreline response after construction. Seven months after construction, 40% of the nearshore nourishment was transported from the initial footprint and the centroid of the nourishment migrated towards shore and alongshore (north). The sheltering capacity of the nearshore berm appears to have captured an additional 58% of the placed volume from the longshore transport system and the beach width onshore of the placement increased by 10.9 m. Measured data, satellite imagery analysis, and rapid predictions all indicate that the nearshore nourishment at Harvey Cedars had a positive impact on the adjacent beach. Full article

The management of dredged sediments is a challenging issue since it involves the interconnection of complex economic, social, technical and environmental aspects. The EU LIFE SURE project aimed to apply a more sustainable dredging technique to Malmfjärden Bay in Kalmar/Sweden (a shallow urban water body with a high content of nutrients) and, additionally, it involved beneficial uses for the dredged material, in line with the circular economy concept. To achieve this, a life cycle assessment (LCA) study was carried out to assess the potential environmental impacts associated with two scenarios: sediment landfilling (S1) and soil conditioning (S2). This LCA study also aimed to evaluate and compare the costs related to each scenario. S1 contemplated the construction and operation of the landfill for 100 years, including the collection and discharge of leachate and biogas. S2 included the use of sediments in soils and the avoidance of producing and using fertilisers. Results showed that (S2) soil conditioning (total impact: −6.4 PE) was the scenario with fewer environmental impacts and the best economic evaluation. The S2 scenario was mainly related to the positive environmental savings produced by reducing fertiliser consumption (which also avoided purchase costs). However, S2 was also linked to potential negative effects associated with eutrophication and toxicity categories of impacts due to the possible spread of nutrients and pollutants in terrestrial and aquatic environments. In order to mitigate this problem, the sediments could be pre-treated to reduce their risk of pollution. Moreover, the main impact of the landfilling scenario (S1, total impact: 1.6 PE) was the emission of global warming-contributing gases during the operation of the facility. Implementing the soil conditioning scenario was therefore recommended, in line with the aim of the LIFE SURE project. Finally, it was recommended that LCA studies should be applied more often in the future when selecting beneficial uses for dredged sediments. The decision-making process is facilitated when the positive and negative impacts produced by each handling option are considered. Full article

Beneficial use of dredged sediments, either in harbours or waterways, is based on their potential as alternative resources. Such sediments can be considered as bulk materials for industrial needs, which is predicated on their current waste status or meeting end-of-waste constraints. They also can be an integral part of beneficial use projects using sediments as a bulk component, including civil engineering and landscaping. This is particularly important for beneficial use projects focusing on climate change effects mitigation, such as flood protection works, coastline defence or littoral urban areas redevelopment. When dredged sediment is used as a bulk material, its acceptability is based on an assumed homogeneity of its properties. On-site analyses allow pre-dredging detailed mapping at a denser scale than laboratory ones; monitoring dredgings during operations and during processing; and continuous control of their properties at the implementation site. This is currently possible only for a selection of inorganic analytes. When dredgings are part of a larger beneficial use project, on-site analyses facilitate first the baseline survey and the sediment source characterisation. Continuous monitoring of the sediment load allows a fast detection of contamination hot spots and their adequate management. Site survey via on-site instruments allow end users and communities to check themselves the contamination level, hence acceptability is better. On-site dredged sediment analyses monitor both building properties and environmental compliance; soil and sediment analyses at receiving sites; surface and groundwater, either for impact assessment or for monitoring works. On-site instruments provide immediate results and allow dynamic or adaptive sampling strategies, as well as allowing operational decisions in real time. Confirmation by laboratory analyses is required for validation, but on-site sample screening for laboratory analyses improves their efficiency. The present paper was developed on the basis of an earlier presentation, which it developed and updated extensively. Full article

The Dredged Material Decision Tool (DMDT) was developed by the United States Environmental Protection Agency (USEPA) to allow project managers, stakeholders, and communities to quantify environmental, economic, and social considerations of using dredged material for beneficial purposes. Dredged material may be disposed in a confined disposal facility (CDF); however, this option is unfavorable because of the finite capacity problems these facilities pose. A more sustainable option is to use dredged materials beneficially such as construction material, for habitat restoration, or for brownfield remediation projects. This study demonstrates the applicability of the DMDT to three relevant candidate projects: (1) Dog Beach, Greenwood, and Lee Street Beaches (Evanston, IL, USA); (2) New York-New Jersey Harbor (New York/New Jersey); and (3) Poplar Island (Chesapeake Bay). The DMDT requires the project information and then completion of worksheets with each criteria (biophysical environment, economic, governance, social, and built environment) ranked, weighed, and scored. The DMDT is applied for all potential alternatives and the results are then analyzed to select the best beneficial reuse alternative. It was found that for the beaches in Evanston, the most beneficial option was on-beach placement with hydraulic dredging. The best option for the New Jersey Harbor was found to be using for brownfield and landfill remediation. The best option for Poplar Island was the lateral and vertical expansion of 50% uplands and 50% wetlands. Overall, DMDT is found to be a valuable tool to facilitate the evaluation of multi-criteria based on the project-specific data and help select the best beneficial use alternative for the dredged material. Full article

Maintenance dredging for shipping channels is required to maintain safe and efficient navigational channels and berths in ports around the world. Sediment that refills dredged channels can enter ports via alluvial transport of eroded materials from upstream and adjacent catchments, from marine transport due to tidal currents and wind driven currents and from longshore drift. Identifying the provenance of sediment infilling navigational channels allows port operators to mitigate and manage sediment transport, potentially reducing dredging requirements and costs. Further, understanding sediment sources can inform options for beneficial reuse or disposal of dredged sediments. A multi-faceted approach was used to assess whether sediment provenance in the Port of Gladstone could be characterized. A combination of particle size analysis, rare earth element composition, carbon stable isotope ratios, strontium isotopes, and beryllium-7 radioisotopes was employed. Samples were collected at accumulation locations within the navigational channel. Potential sediment sources were sampled from sites of longshore drift to the south of the Port of Gladstone, and intertidal sand and mud representative of transport from currents. Fluvial sediment samples were collected during dry and wet season conditions and from the three main local catchments. Potential source sediment samples yielded identifiable differences with respect to rare earth elements, while beryllium-7 isotope analysis indicated recent deposition of sediments from mudflats or catchment within the channels. The approach used here provided insights into the source of recently deposited sediments to the dredged channels, enabling managers to make informed decisions on mitigation and management strategies. Full article