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Tidal marshes at the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island (PI) are part of a large‐scale restoration project to replace lost island habitat in Chesapeake Bay, United States. However, observations of Spartina alterniflora die‐back prompted questions about the impact on genetic diversity and resilience of restored versus natural marshes, leading to an investigation of genetic diversity and population structure. Transects were established across three distinct restored marshes with different ages and histories of die‐back and across two local, non‐restored native marshes. Plants were genotyped at eight microsatellite markers to examine metrics of genetic diversity, population structure, and clonality. Allelic richness but not heterozygosity was higher in restored marshes compared to reference marshes, which showed significantly higher clonality and spatial genetic autocorrelation. Restored marsh areas experiencing die‐back had slightly lower multilocus diversity indices than non‐die back areas in two third cases, but not a third comparison. Significant genetic differentiation was observed between the native and restored marshes (mean GST approximately 0.06), which reflects the approximately 100 km distance between native marshes and restored seed source in New Jersey. Overall, die‐back in restored marshes did not substantially affect genetic diversity or composition, but substantial differences in diversity were observed between restored and native marshes. Reduced clonal diversity in mature, native marshes may be a function of their greater age, as has been reported elsewhere. Future monitoring of neutral genetic diversity in PI marshes will be useful for understanding longer‐term patterns of genetic change and diversity in planted, restored marshes. [ABSTRACT FROM AUTHOR]

Marsh and mangrove forest habitats are productive at capturing and storing carbon, thus actions to protect and create coastal blue carbon sinks could help mitigate global warming. Dredged material is often used to create coastal habitats and evaluating the carbon impact of placement alternatives (PA) could help inform restoration and climate policies. Output from a Delft3D‐FM morphodynamics and hydrodynamics model informed a Coastal Wetlands Carbon Model at years 2020, 2025, 2030, and 2050. Three model simulations were used and included (1) no restoration (PA1), (2) restoration dominated with mangroves (PA2), and (3) restoration dominated with marshes (PA3) at a different location. Habitats of brackish marsh, saline marsh, mangrove forest, and saline open water that surround Port Fourchon, Louisiana, U.S.A., were evaluated to estimate the net greenhouse gas (GHG) flux of the study area with and without restoration. In years 2020 and 2025, the study area was estimated to be a net GHG sink (−1.1 ± 0.2 MMT CO2e) with or without mangrove and marsh‐dominated restoration. At years 2030 and 2050, even with habitat loss due to sea‐level rise, the study area for all simulations was projected to remain a net GHG sink. At year 2050, +0.1 ± 0.04 MMT CO2e could be avoided with restoration. At the restoration project scale, mangrove‐dominated restoration (PA2) had net GHG sinks (−0.07 to −0.09 MMT CO2e) near the marsh‐dominated restoration (PA3, −0.09 to −0.13 MMT CO2e). Thus, these modeled results could help inform future restoration planning and climate policies. [ABSTRACT FROM AUTHOR]

Tidal marshes provide numerous ecosystem services, but are threatened by recent increases in global sea level rise (SLR). Marsh restoration and creation are important strategies for mitigating marsh loss, restoring ecosystem services, increasing coastal community resilience, and providing much needed habitat for threatened species. Dredged material resulting from navigation channel maintenance can provide a substrate for these restoration projects. Few studies, however, have addressed the sustainability of these marshes. The Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island, where fine-grained, nutrient-rich dredged material from upper Chesapeake Bay is being used to create > 302 ha of tidal marshes, provides a case study. The low supply of inorganic sediment is counteracted by abundant nutrients, stimulating high rates of organic matter production and elevation change. Using > 10 years of data from 39 surface elevation tables, we found that the mean low marsh rate of elevation change (7.7 ± 3.21 mm year−1) was double the mean high marsh rate (3.6 ± 0.47 mm year−1) and exceeded the natural reference marsh (3.0 ± 2.28 mm year−1) and relative SLR (5.7 mm year−1). By stimulating organic matter production, the high nutrient substrate appears to offset the low inorganic sediment inputs in mid-Chesapeake Bay. Spatial variability was correlated with initial elevation, but was also influenced by local factors that may affect sediment redistribution within the marshes. [ABSTRACT FROM AUTHOR]

Mercury (Hg), a neurotoxicant released primarily by anthropogenic activity, is present in all the world’s oceans, estuaries, and freshwater bodies (Giang, 2013). In addition to its toxicity to marine biota, Hg bioaccumulates within fish and other seafoods, presenting a threat to human health since fish remain important sources of protein for people across the world (Giang, 2013). Despite improvements in Hg pollution control, levels in commonly consumed marine fish such as bluefin tuna often exceed human health guidelines causing recommendations to limit fish consumption (Giang, 2013). Organic forms of Hg, such as monomethylmercury (MMHg), are more toxic than other forms and are the main causes of concern for human and ecosystem health. Various forms of Hg can transform into MMHg overtime and in certain environments. Elemental mercury (Hg(0)) can transform into different chemical species before becoming MMHg while divalent mercury (Hg(II)) can transform into MMHg through biotic methylation in the water column and sediments under specific chemical and physical conditions (Ming et al., 2019).The U.S. Environmental Protection Agency (EPA) manages approximately 98 ocean dredged material disposal sites (ODMDS) around the country’s federal waters. Disposal sites are used for the disposal of nontoxic sediments that are routinely removed to maintain navigational depths in ports, harbors, and marinas, as well as to support national maritime commerce, commercial fisheries, and recreation (EPA, n.d.). The U.S. Army Corps of Engineers (USACE) is planning to dredge federal channel segments in Newport Bay in Newport Beach, California. Based on sediment samples collected and analyzed for ocean disposal testing, the USACE project sediments were found to be high in Hg contamination (Anchor QEA, LLC., 2020). However, despite the high Hg levels, toxicity tests indicated suitability for ocean disposal at EPA’s LA-3 ODMDS located offshore of Newport Bay (Anchor QEA, LLC., 2020). The current Hg levels at the LA-3 disposal site are low to non-detect, and the effects of disposing of sediments loaded with Hg from the Federal channel in Newport Bay are unknown (Battelle and DAMOSVision, 2015). To address this issue, a literature review of Hg biogeochemical cycling and Hg-methylation was conducted to assist in the understanding of Hg speciation and transport. A policy review was also completed to assess the policies relevant to sediment dredging in California and ocean dumping in federal waters. Related to the policies in place, manuals utilized by USACE and EPA for testing and analysis purposes were reviewed to determine additional sediment and water column tests to minimize the potential risk of Hg contamination in the marine environment. Through the compilation of information, testing and analysis recommendations in addition to current testing were made for the dredge and disposal site locations.

Sediments are dredged from waterways to maintain maritime activities and prevent floods. Exorbitant amounts of money are budgeted for the removal of dredged material (DM) and its disposal in landfills. We investigated the potential for reuse of DM as a road construction material using so-called bio-enzyme products as stabilizing agents. To improve the mechanical properties of DM, such as compressive strength, compressibility, Atterberg limits and the California bearing ratio (CBR), mixtures of DM were tested with two different amounts of a commercially available bio-enzyme product, which yielded enzymatically stabilized dredged material (ESDM). Unconfined compressive strength (UCS), compaction and Atterberg limits were measured in accordance with ASTM specifications on all samples. Data show that the addition of bio-enzymes resulted in increases in UCS but did not affect the optimum moisture content (OMC), maximum dry unit weight or Atterberg limits of the DM. A comparative field study was carried out to evaluate the CBR of the CH subgrade before and after treatments with the bio-enzyme product and with lime as a traditional stabilizing agent. The results of the field study supported the laboratory findings. Based on these data and results from the literature, models predicting the effect of bio-enzyme treatments on the value of CBR and of UCS were developed statistically. These models also underlined the importance of the clay fraction and PI values for the improvement of the engineering properties of soil using bio-enzyme additives. [ABSTRACT FROM AUTHOR]

The paper deals with the question of whether it is permissible to relocate the dredged material from the seabed from the port of Koper to another location within the territorial sea of the Republic of Slovenia. At first glance, the simple issue is considered from the point of view of the legal permissibility of such conduct, recognizing that it is a highly multidisciplinary issue. Aspects of international law, EU law, Slovenian law, and Italian law are discussed. The latter because Italy faces the same problems of dumping or relocation of dredged material in the Gulf of Trieste basin as Slovenia, unlike Croatia which does not have major ports in this area. The Slovenian and Italian regulation and experiences may be of interest to Croatia for its local ports or major ports in other parts of Adriatic.

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A continuous treatment process using steel slag powder including foam drying and carbonation processes (termed the SSFD-C method) is a novel technology previously developed in our laboratory. It has achieved the first application of carbonation solidification technology to recycle marine dredged material with high moisture content. The aim of this study is to investigate CO2 uptake and performance regulation in the preparation of carbonated eco-aggregates (CEAs) from dredged soils processed using the SSFD-C method. Steel slag and lime hydrate independently contribute to the strength of CEAs. However, the influence they exert on CO2 uptake, along with other properties, such as pH values and water absorption of CEAs, remains unclear. Furthermore, it is important to clarify whether the soluble silica in a CEA originates from dredged soil or steel slag, as a CEA has the potential to provide silica nutrients to plants. The findings indicated that within the initial three hours of carbonation, the strength of CEAs could approximate 65% of the ultimate stable strength. The moisture absorption for CEAs was noted to be in the 26–30% range. Carbonation over a 24 h period can lower the pH of the CEA to less than 10, and the carbonation reaction can penetrate the core of the 10–15 mm CEA pellets. Carbonation of the lime hydrate fraction was more favorable to increase the CO2 uptake of the CEA, and carbonation of the steel slag fraction was more favorable to decrease the pH value and water absorption of the CEA. The water-soluble silicon of the CEA was found to have been mainly derived from steel slag, while it was established that carbonation could increase the water-soluble silicon content of the CEA by 5–8 times. The result of this study could provide theoretical guidance for regulating the performance of CEAs. [ABSTRACT FROM AUTHOR]

The amount of waste materials such as dredged materials (DM) and waste glass (WG) have been growing exponentially since the middle of the 20th century. The most important problem created by them is the lack of space to be used for storage beside ecological, economic, and environmental problems. The purpose of the presented study is to contribute to the elimination of the mentioned problems by assessing the re-use of related wastes as pavement material. Therefore initially, DM was treated with additives at various contents that are powdered waste glass (GP) (5 %, 10 %, 15 %, 20 %, 25 %), lime (5 %) and cement (5 %). Following, a series of experimental studies and calculations such as Proctor, California bearing ratio (CBR), resilient modulus (MR) were carried out on the blends to define the geotechnical properties of them. Additionally, a cost analysis was made according to the obtained test results and the design inputs for a typical flexible pavement to determine the effect of the additives on the cost of the road construction. The underlying mechanism process of determined effects was defined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The obtained results indicate that CBR of the DM is 5.6 % which means has sufficient strength and stiffness for being used as a subgrade. Increasing the GP content in the blends contributes to achieving more desired results both geotechnically and indirectly economically. Combined use of cement and GP on DM increases the CBR value up to 83 %. This translates to an 89 % reduction in the structural number (SN) and 170 % decrease in cost index. The results of microstructural analysis indicate that the geotechnical improvement of treated DM was provided by CSH and CAH formations. Consequently, the additives used improve index and stiffness properties of DM which means a decrease in the layer thickness in road construction and therefore a decrease in the cost. The presented study confirms the usability of cement, PG, and lime-treated DM as pavement material, according to criteria specified by the Federal Highway Administration.

Tidal marshes are important sites of silicon (Si) transformation, where dissolved Si (DSi) taken up by macrophytic vegetation and algal species is converted to biogenic silica (BSi), which can accumulate in the soil, be recycled within the marsh, or be exported to adjacent coastal waters. The role of restored and created tidal marshes in these processes is not well understood, nor is the impact of nutrient enrichment at either the plant or ecosystem level. Here, Si fluxes were examined to develop a Si mass balance in a nitrogen (N)-enriched marsh created with fine-grained dredged material from the Chesapeake Bay, United States. In addition, the effectiveness of Si soil amendments to ameliorate the negative effects of excess nitrogen on Spartina alterniflora was examined through laboratory and field experiments. Silicon was exported to the estuary as DSi (49 g m−2 y−1) and BSi (35 g m−2y−1) in stoichiometric excess of nitrogen and phosphorus. Rapid recycling of Si within both marsh and the tidal creeks appeared to be important in the transformation of Si and export from the marsh. Enhanced macrophyte SiO2 tissue concentrations were observed in the field experiment, with end-of-season mean values of 2.20–2.69% SiO2 in controls and 2.49–3.24% SiO2 in amended plots, among the highest reported for S. alterniflora; however, improved plant fitness was not detected in either experiment. Thus, tidal marshes created with a fine-grained, N-rich dredged material appear to function as a rich source of Si to the restored marsh and local estuarine environment, an overlooked ecosystem service. Soil Si amendments, however, did not appear likely to alleviate N-induced stress in S. alterniflora.

Sediments are dredged from waterways to maintain maritime activities and prevent floods. Exorbitant amounts of money are budgeted for the removal of dredged material (DM) and its disposal in landfills. We investigated the potential for reuse of DM as a road construction material using so-called bio-enzyme products as stabilizing agents. To improve the mechanical properties of DM, such as compressive strength, compressibility, Atterberg limits and the California bearing ratio (CBR), mixtures of DM were tested with two different amounts of a commercially available bio-enzyme product, which yielded enzymatically stabilized dredged material (ESDM). Unconfined compressive strength (UCS), compaction and Atterberg limits were measured in accordance with ASTM specifications on all samples. Data show that the addition of bio-enzymes resulted in increases in UCS but did not affect the optimum moisture content (OMC), maximum dry unit weight or Atterberg limits of the DM. A comparative field study was carried out to evaluate the CBR of the CH subgrade before and after treatments with the bio-enzyme product and with lime as a traditional stabilizing agent. The results of the field study supported the laboratory findings. Based on these data and results from the literature, models predicting the effect of bio-enzyme treatments on the value of CBR and of UCS were developed statistically. These models also underlined the importance of the clay fraction and PI values for the improvement of the engineering properties of soil using bio-enzyme additives.

The motion of particle clouds (i.e., sediment clouds) usually can be found in engineering applications such as wastewater discharge, land reclamation, and marine bed capping. In this paper, a series of laboratory tests are conducted on coral sand to investigate the shape feature of the single particle and the mixing processes of the coral sand particle clouds. The shape of coral sand particle is measured and quantified. The experimental results demonstrate that the shape of coral sand particles tends to be spherical as the particle size decreases, and empirical equations were established to explain the variation of D50 and fS,50 of coral sand. Compared with the silica sand, the evolution of the coral sand particle cloud still experiences three stages, but the threshold for the Reynolds number of particle clouds entering the next stage changes. Further, the normalized axial distance of the coral sand particle clouds is 58% smaller. The frontal velocity exhibits similar varying tendency for the coral sand particle cloud. Considering the difference in shape between coral sand particles and silica sand particles, a semi-empirical formula was proposed based on the original silica sand prediction formula by adding the shape factor and the experimental data of 122 µm⩽D50⩽842 µm. It can predict the frontal velocity of the coral sand particle clouds. [ABSTRACT FROM AUTHOR]

A continuous treatment process using steel slag powder including foam drying and carbonation processes (termed the SSFD-C method) is a novel technology previously developed in our laboratory. It has achieved the first application of carbonation solidification technology to recycle marine dredged material with high moisture content. The aim of this study is to investigate CO2 uptake and performance regulation in the preparation of carbonated eco-aggregates (CEAs) from dredged soils processed using the SSFD-C method. Steel slag and lime hydrate independently contribute to the strength of CEAs. However, the influence they exert on CO2 uptake, along with other properties, such as pH values and water absorption of CEAs, remains unclear. Furthermore, it is important to clarify whether the soluble silica in a CEA originates from dredged soil or steel slag, as a CEA has the potential to provide silica nutrients to plants. The findings indicated that within the initial three hours of carbonation, the strength of CEAs could approximate 65% of the ultimate stable strength. The moisture absorption for CEAs was noted to be in the 26–30% range. Carbonation over a 24 h period can lower the pH of the CEA to less than 10, and the carbonation reaction can penetrate the core of the 10–15 mm CEA pellets. Carbonation of the lime hydrate fraction was more favorable to increase the CO2 uptake of the CEA, and carbonation of the steel slag fraction was more favorable to decrease the pH value and water absorption of the CEA. The water-soluble silicon of the CEA was found to have been mainly derived from steel slag, while it was established that carbonation could increase the water-soluble silicon content of the CEA by 5–8 times. The result of this study could provide theoretical guidance for regulating the performance of CEAs.

Nowadays, dredged materials, which are obtained from variable dredge operations, is no longer considered as waste, instead the potential reuse areas are studied by researchers. In this study, the impacts of cement or lime treatment on the engineering properties of dredged material, which is obtained by dredging operations into the sea, and the potential reuse of treated dredged materials for road construction were examined. Atterberg limit tests, miniature compaction test and unconfined compression test was performed on raw and cement/lime treated dredged materials. The samples were cured for 1 day,7 and 28 days for unconfined compression test. The test results show that the plastic limit of treated samples increases with addition additives when their plasticity index decreases. The unconfined compression strength of treated dredged material improved with increase in additive content and curing time. It has been determined that cement/lime treatment improves engineering properties of dredged material and it is suitable for different phase of road layers. [ABSTRACT FROM AUTHOR]

The Huangmao Island dumping area is adjacent to the Pearl River Estuary in the South China Sea. From its first dumping activity in 1986 to 2017, 6750 × 104 m3 dredged materials were dumped in this dumping area. Sediment pollution levels, ecological risk, and benthic communities in 2011–2017 were evaluated; the results showed that the concentrations of the heavy metals (HMs; except Hg) in surface sediments of the dumping area met the class I standard of marine sediment quality (GB 18668-2002). HMs in the surface sediments were relatively high in the northern and central areas but relatively low in the south of the dumping area. Speculation was that the spatial variation in HM concentrations might be caused by dumping activities. The Nemerow index implied that the contaminated area was mainly in the north of the dumping area (S1, S2, and S3), where the dumping amount was the largest. The potential ecological risk (Eir) indices of Zn, As, Cu, and Pb indicate that these metals posed a low risk to the ecosystem of the dumping area, whereas Cd and Hg posed a high risk at some stations. The geoaccumulation indices (Igeo) of Zn, As, Cu, and Pb specified no pollution or light pollution in the study area, whereas those of Cd and Hg in most years indicated mild contamination levels. Benthic organisms in the study area were arthropods, chordates, annelids, mollusks, echinoderms, nemertinean, coelenterate, and echiuran, among which arthropods were the most abundant. The abundance of taxa and density of benthic organisms had a little difference among the stations within the dumping area, but were significantly lower than those of the stations outside the dumping area. In addition, non-metric multidimensional scaling analysis confirmed that the observed patterns separated the stations within the dumping area from stations outside the dumping area. The evaluation results of the HMs revealed that the dumping area with a large dumping amount was more severely polluted. Dumping dredged materials seemed to have a negative impact on the benthic community in the dumping area. [ABSTRACT FROM AUTHOR]

Millions of cubic meter of sediments are dredged annually to open channels for navigation of ships in ports and harbors. Beneficial reuse of these dredgings is typically possible upon their stabilization with calcium-rich amendments. A series of long-term laboratory column leaching tests and contaminant transport models were employed to study metal leaching behavior of bottom-sea dredged material (DM) and their blends with quarry by-products in the natural environment. Column leach tests yielded generally low or non-detectable metal concentrations. The results of the transport modeling indicated that the analyzed metals leached from the DM and the blends were below the national water quality limits at the point of entry to surface water or upon reaching groundwater. Model results showed a significant reduction in leached porewater concentrations due to adsorption and natural attenuation onto a simulated natural formation located between the DM or treated DM and the body of surface water. The overall findings showed that dredged sediments can be considered for reuse following amendment with quarry by-products. [ABSTRACT FROM AUTHOR]

When terminating sediment bioaccumulation tests with the oligochaete Lumbriculus variegatus, varying amounts of detrital material are retained along with the recovered worms after sieving, necessitating time‐consuming, labor‐intensive manual separation of worms from detritus prior to tissue residue analysis. A method to facilitate the worms self‐extracting out of the detrital material into a column of gravel was developed, resulting in approximately 90% recovery test organisms (on a mass basis) at test termination. Following exposure to contaminated sediment, polychlorinated biphenyl tissue residues and residual sediment in the gut of self‐extracted animals were not significantly different compared to worms recovered by manual separation followed by purging of gut contents. Environ Toxicol Chem 2021;40:1673–1677. Published 2021. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Dredged clays are commonly used in land reclamation works. These clays are excavated as lumps varying in size from few tens of millimeters to a meter. When the lumps are dumped, they are made to merge due to consolidation. But before that, the lumps invariably swell and start to disintegrate if sufficient time between the dumping of the lumps in water and the application of surcharge is permitted. The magnitude of swelling and disintegration of the clay lump would indirectly affect the magnitude of the applied surcharge needed to merge the lumps. This paper investigates the effect of size, strength and saturation on swelling and disintegration of the clay lumps submerged in water. The loss in lump's weight was the measure of disintegration. Small lumps with large specific surface area, disintegrated at a faster rate. Likewise, unsaturated lumps were also noted to swell and disintegrate quickly. On the other hand, the lumps with water content close to their liquid limit were least likely to disintegrate. [ABSTRACT FROM AUTHOR]

In natural tidal marshes, nutrient fertilization stimulates complex responses, bringing into question the suitability of nutrient-rich dredged material as a substrate for tidal marsh restoration. We examined vegetation and elevation trends in the constructed tidal marshes at Poplar Island, Maryland where fine-grained dredged material (high nutrient) and locally dredged sand (low nutrient) were used as substrates. Macrophyte production was higher and root:shoot ratios lower in dredged material marshes. Measured vertical accretion was similar in dredged material (7.4 ± 0.6 mm y−1) and sand (6.4 ± 0.9 mm y−1) marshes, and is keeping pace with local sea-level rise. A detailed carbon budget was developed for one dredged material marsh to examine carbon dynamics under high nutrient availability. High annual macrophyte production combined with small exports via tidal exchange and methane emissions resulted in an annual carbon burial of 206 g C m−2 y−1, and calculated vertical accretion of 6.5 mm y−1 from organic matter. This is attributed to the contribution of organic matter from aboveground biomass due to protection from perimeter dikes constructed to contain dredged material during placement, reducing marsh exposure and organic matter export. With appropriate design and management, fine-grained, high-nutrient dredged material makes a suitable substrate for tidal marsh restoration. [ABSTRACT FROM AUTHOR]

• Marine dredged materials of Marmara Sea taken from five pilot areas were analyzed. • Environmental tests classify the samples of dredged sediments as non-hazardous waste. • Beneficial use of dredged material in landfills were evaluated by geotechnical tests. • Raw or processed dredged material is applicable as cover, barrier or restoration layer. • Beneficial use is cheaper than terrestrial disposal, and ecologically more sustainable than dumping at sea. Worldwide production of large volumes of dredged materials (DMs) has become a pressing environmental problem. In Turkey, the government has yet to develop management strategies that successfully prevent or minimize dumping into the Marmara Sea. One potential solution is the utilization of the DMs as a source of material for earthworks, particularly in sanitary landfills in Istanbul and Kocaeli. The most economically developed cities in Turkey, they were evaluated in terms of potential environmental impacts and regulatory compliance. Five ports/harbors representing specific portions of the study area and different industrial activities were selected as pilot regions. Physical, chemical, mineralogical, toxicological, and leaching potential measurements of DMs dredged from the seabed revealed they qualify as non-hazardous waste. Index and engineering tests performed on raw and processed DMs were assessed to determine the geotechnical requirements for soil-based materials (SBM) used in sanitary landfills. The results showed that non-hazardous DMs could be utilized as a cover, base/cap liner, and/or fill material at various sections within the landfills. This method provides environmental advantages not seen with other management strategies for DMs such as dumping at sea or upland disposal. [ABSTRACT FROM AUTHOR]

Large strain self-weight consolidation is widely used for the management of the dredged material (DM) in dredged material disposal sites. A multilayer vacuum extraction method, which consists of a settling column, pore pressure measurement apparatus and multilayer vacuum extraction apparatus, is developed. The interface height, water content, excess pore water pressure, grain size distribution, as well as the compressibility and permeability relationships involved in self-weight consolidation are determined. Experimental results show that the measured data are reasonable and the method is feasible. Gibson's governing equation for one-dimensional finite strain consolidation is discretised using a modified upwind difference form, and a corresponding computer program is compiled. It is found that the interface height settlement, void ratio and excess pore water pressure approximate laboratory experimental results. Therefore, the rationality of the analytical model and finite difference numerical solution as well as the correctness of the computer program are validated. The model possibly provides a satisfactory prediction for the self-weight consolidation of the DM. [ABSTRACT FROM AUTHOR]

In order to increase the handling capacity of ports in Singapore, the Maritime and Port Authority of Singapore (MPA) has embarked on massive port development projects for the past decade. One of the major projects was the Reclamation for Pasir Panjang Terminal Phases 3 and 4, completed in April 2015. The project provided 200 hectares of port land equipped with 5.7 km of berthing facilities to accommodate ultra-large container ships. In this project, MPA embraced sustainable development by reusing dredged and excavated clayey soil as reclamation fill and as fill material to form a containment bund within the footprint of the project. Nearly half of the reclamation fill consisted of clayey soil, which was improved using prefabricated vertical drains with surcharge. The containment bund, which served as a temporary earth-retaining system during reclamation filling, was formed using geotextile tubes filled with clayey soil treated with cement. This paper describes the innovative design and construction in the project. [ABSTRACT FROM AUTHOR]

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.

Action Levels (ALs) are thresholds which are used to determine whether dredged material is suitable for disposal at sea by providing a proxy risk assessment for potential impacts to biological features such as fish and benthos. This project tested proposed scenarios for changes to the UK Action Levels to determine the likely implications for navigational dredge licensing in England and Wales. Approximately 3000 sample data records from 2009 to 2018 were collated with varying numbers of concentrations for contaminant parameters including trace metals, organotins, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). Initially, these data were assessed using current ALs to determine the percentages of the samples with levels below AL1 (generally acceptable for disposal), between AL1 and AL2 and those showing levels above AL2 (generally unacceptable for disposal). These results were then used to compare with the results of the proposed new AL scenarios for each contaminant type derived from literature reviews and historic data. The results indicate that there are changes to the ALs which could be made such as updating the current ALs with the revised ALs, as well as the introduction of ALs where there are currently none set. The benefits of changing the ALs include reducing contaminant disposal to the marine environment and increased transparency in decision making. Any proposed scenarios will need to be phased in carefully in full liaison with stakeholders.

The Huangmao Island dumping area is adjacent to the Pearl River Estuary in the South China Sea. From its first dumping activity in 1986 to 2017, 6750 × 104 m3 dredged materials were dumped in this dumping area. Sediment pollution levels, ecological risk, and benthic communities in 2011–2017 were evaluated; the results showed that the concentrations of the heavy metals (HMs; except Hg) in surface sediments of the dumping area met the class I standard of marine sediment quality (GB 18668-2002). HMs in the surface sediments were relatively high in the northern and central areas but relatively low in the south of the dumping area. Speculation was that the spatial variation in HM concentrations might be caused by dumping activities. The Nemerow index implied that the contaminated area was mainly in the north of the dumping area (S1, S2, and S3), where the dumping amount was the largest. The potential ecological risk (Eir) indices of Zn, As, Cu, and Pb indicate that these metals posed a low risk to the ecosystem of the dumping area, whereas Cd and Hg posed a high risk at some stations. The geoaccumulation indices (Igeo) of Zn, As, Cu, and Pb specified no pollution or light pollution in the study area, whereas those of Cd and Hg in most years indicated mild contamination levels. Benthic organisms in the study area were arthropods, chordates, annelids, mollusks, echinoderms, nemertinean, coelenterate, and echiuran, among which arthropods were the most abundant. The abundance of taxa and density of benthic organisms had a little difference among the stations within the dumping area, but were significantly lower than those of the stations outside the dumping area. In addition, non-metric multidimensional scaling analysis confirmed that the observed patterns separated the stations within the dumping area from stations outside the dumping area. The evaluation results of the HMs revealed that the dumping area with a large dumping amount was more severely polluted. Dumping dredged materials seemed to have a negative impact on the benthic community in the dumping area.

As known, marine dredged materials (DMs) are highly nuisance wastes if they are not correctly reused or removed. In this work, the usability of DMs to the technical terms as manufactured topsoil (MT) in the urban landscaping works is discussed. Firstly, the leaching potentials of DMs were determined according to the related legislations to identify their hazardousness features. Secondly, DMs were subject to some treatment stages such as sieving, desalination, organic amelioration via peat and sheep manure, and pH adjustment to turn into an alternative natural soil pursuant to the British Standard in the scope of soil quality improvement studies as there is not any national standard in Turkey for the production of topsoil from different materials. Then, MT mixtures were prepared with washed and unwashed DM, peat and sheep manure in different mixing ratios (v/v); 33%, 50% and 67% DM, respectively. Consequently, high quality grass seed mixtures used for the landscaping applications were monitored for six months. The results demonstrate the availability of DM as alternative MT in the urban landscaping areas. Thus, important data were obtained as to the use of DM at alternative areas such as green city, green roof, shopping centers, organized industry, etc.

• Mineral liners from pre-treated dredged material may fail in distinct phases. • A mineral liner from pre-treated dredged material performed well for 20 years. • The design of the entire cover system is important for the liner performance. • A "slow" lateral drainage layer keeps the liner surface moist. • Hydro-chemical data are helpful for identifying hydrologic processes. The water balance and effectiveness of a landfill cover containing a liner from fine-grained dredged material ('METHA-material') and a drainage layer from sandy dredged material ('METHA-sand') from the Port of Hamburg (Northern Germany) was investigated for 20 years using two test fields (lysimeters), each 500 m2 in size. The layering within the standard design test field (FS) is identical to the layering of the cover on the landfill, whereas the alternative design test field (FA) was designed to provoke desiccation of the liner. The setup abstained from continuous side walls cutting through the liners in order to allow for material properties representative for the landfill cover, at the cost of possible minor lateral inflows or outflows, which were, however, considered negligible. By example of the lysimeter FA the risk of desiccation-induced failure of a liner from METHA-material under the given climate could be shown. In contrast, the discharges and hydro-chemical parameters measured for the lysimeter FS indicate continuous high efficiency of the liner until today. The average discharge below the liner was 14.9 mm/yr. The entire cover contributes to the good liner performance. Reason are (1) the low hydraulic conductivity of the liner (5 × 10−10 m/s) and its large thickness (1.5 m); (2) the increased stresses on the liner due to the 2.5 m thick overlaying cover; (3) the 1.0 m thick drainage layer from slowly-draining METHA-sand, allowing for a continuous nearly water-saturated fringe above the liner; and (4) the sufficient amount of plant available water in the recultivation layer. [ABSTRACT FROM AUTHOR]

The paper reports investigation results on the use of fine sediments to replace a part of the raw materials in Portland cement (PC) clinker. Representative samples of sediments from three different French dam reservoirs are studied. These materials have a mineral composition that includes some of oxides components essential to cement manufacturing, such as SiO2, CaO, Al2O3 and Fe2O3. Their potential for use as replacement of clays in cement industry was considered. Nine mixes of PC clinkers were synthesised with feedstock mixtures containing between 20.6 and 31.1% of sediments according to their chemical composition. In all cases studied, usual clay materials are completely substituted by dam sediments. Clinkers were characterised using ICP-AES, XRD and optical microscopy. Results showed that synthesised clinkers have similar chemical and mineralogical composition than ordinary PC clinker. Finally fine-grained sediments might be considered as natural resource, they are an interesting alternative raw material for PC clinker production. [ABSTRACT FROM AUTHOR]

Nowadays, sustainable environmental management of high quantities of marine dredged material (DM) together with other industrial wastes is a common problem across Turkey. The beneficial use/recovery of DM and wastes in the production of lightweight aggregate (LWA) instead of dumping at sea/disposal will provide substantial environmental savings in terms of circular economy. In this study, the production of LWA by using marine DM, coal fly ash and waste foundry sand were investigated. Three different mixtures of raw materials were granulated in pelletizing disc, dried at 105°C and sintered in muffle furnace at 1100, 1150, 1170, 1180 and 1190°C with 5-10°C/min heating rates and 10-20 min sintering period. Sintered LWAs were analyzed in terms of physical, mechanical, microstructural, mineralogical and leaching properties. LWA produced at 1190°C sintering temperature, 5°C/min heating rate and 20 min sintering period resulted in better aggregate properties. Furthermore, according to the leaching test results; it is observed that the parameters of the eluate and original waste were lower than the Class III (inert waste) landfilling limit values due to the entrapment of those into the silicate matrix in sintering process; thus, causing no environmental risk to be used at construction sector. [ABSTRACT FROM AUTHOR]

A variety of studies recently proved the applicability of different dried, fine-grained dredged materials as replacement material for erosion-resistant sea dike covers. In Rostock, Germany, a large-scale field experiment was conducted, in which different dredged materials were tested with regard to installation technology, stability, turf development, infiltration, and erosion resistance. The infiltration experiments to study the development of a seepage line in the dike body showed unexpected measurement results. Due to the high complexity of the problem, standard geo-hydraulic models proved to be unable to analyze these results. Therefore, different methods of inverse infiltration modeling were applied, such as the parameter estimation tool (PEST) and the AMALGAM algorithm. In the paper, the two approaches are compared and discussed. A sensitivity analysis proved the presumption of a non-linear model behavior for the infiltration problem and the Eigenvalue ratio indicates that the dike infiltration is an ill-posed problem. Although this complicates the inverse modeling (e.g., termination in local minima), parameter sets close to an optimum were found with both the PEST and the AMALGAM algorithms. Together with the field measurement data, this information supports the rating of the effective material properties of the applied dredged materials used as dike cover material.

Li, H.; Beck, T.M.; Moritz, H.R.; Groth, K.; Puckette, T.; Marsh, J., and Sánchez, A., 2019. Sediment tracer tracking and numerical modeling at Coos Bay inlet, Oregon. Journal of Coastal Research, 35(1), 4–25. Coconut Creek (Florida), ISSN 0749-0208. An investigation was conducted on transport of dredged material placed in the nearshore area of an ocean dredged material disposal site (ODMDS) adjacent to the Coos Bay inlet, Oregon. A sediment tracer release/sampling and field data collection program was carried out and a numerical hydrodynamic, wave, and sediment transport model, the Coastal Modeling System, was developed to perform the analysis of sediment transport around the inlet system and the ODMDS. The data were used to calibrate and validate model calculations, and the model was set up to calculate sediment fluxes and to simulate the process of sediment tracer release and movement, and determine the pathways of sediment tracer under combined wave, current, and wind conditions within and around the immediate vicinity of the Coos Bay ODMDS. The calculations and the measurements indicate that sediment tracer movement is primarily controlled by tidal current inside Coos Bay and at the inlet entrance, and responding to wave and storm conditions in the open coastal area. A divergence in net sediment transport directions in the adjacent nearshore beach was apparent in the results of the tracer release and numerical simulations. This methodology may be used to determine sediment bypassing pathways and optimal placement of sediment within a nearshore environment adjacent to tidal inlets. [ABSTRACT FROM AUTHOR]

Abstract Previous research has found butyltin pollution at dumping sites, which are the final fate of dredged material mostly originating from harbors and navigation systems. The distribution and impacts of butyltins were assessed in sediments at 12 dumping sites of China. Total butyltins (monobutyltin, dibutyltin, and tributyltin) concentrations ranged from 1.76 to 486.62 ng Sn g−1 dw. This study also presents evidence of considerable historic inputs of tributyltin (TBT) to Dumping sites 01, 05, 06, 08, 09 and 11, with evidence of heavier recent TBT input at Dumping site 04 and 10. The butyltin contamination at dumping sites was comparatively light and historic compared to research in other countries, but was more serious than other sea regions. TBT levels at Dumping site 09 probably have negative effects on biological systems. Overall, more attention should be paid to the level and impacts of butyltins in the sediment at dumping sites in China. Highlights • Levels of butyltins in sediment at dumping sites in China were investigated. • The results presented historic TBT source at Dumping site 01, 05, 06, 08, 09, 11. • It showed evidence of heavier recent input of TBT at Dumping site 04 and 10. • The butyltin levels at dumping sites were higher than other sea regions in China. • TBT level at dumping sites probably has negative effects on biology of organisms. [ABSTRACT FROM AUTHOR]

The US Army Corps of Engineers (USACE) operates and maintains numerous projects in support of its various civil works missions including flood damage risk reduction, navigation, and ecosystem restoration. Originally authorized on an economic basis, these projects may produce a broad array of unaccounted for ecosystem services (ESs) that contribute to overall human, societal, and environmental well‐being. Efforts are underway to capture the full array of environmental, economic, and social impacts of these projects. Methods are needed to identify relevant ESs generated by these nature‐based projects and to measure their contribution to societal well‐being with an emphasis placed on use of readily available data. Performance metrics were collected to capture the benefits of strategic placement of dredged material in river systems to allow formation of islands that produce a wide array of ESs. These performance metrics can be converted to ESs with market value or combined in a decision analytical approach to demonstrate the relative gain in utility. This approach is demonstrated on a riverine island created on the Atchafalaya River, Louisiana, as a result of the strategic placement of dredged material. The outcomes foster integration of ES assessment into project design and management practices and support more comprehensive project evaluation and widespread application. Integr Environ Assess Manag 2018;14:759–768. Published 2018. This article is a US Government work and is in the public domain in the USA. Key Points: Navigational maintenance projects produce a broad array of unaccounted for ecosystem services (ESs) that contribute to overall human, societal, and environmental benefits.On the lower Atchafalaya River, Louisiana, USA, a riverine island self‐formed as a result of strategically placing dredged material from an adjacent federal navigation channel and natural hydrodynamic processes of the river.Performance metrics were developed that capture the benefits of strategic dredged‐material placement generating habitat, climate regulation, nutrient sequestration, and navigational support benefits.Performance metrics were converted to ecosystem services to determine their market values and to identify their relative contribution to the overall utility of the project. [ABSTRACT FROM AUTHOR]

Nowadays, sustainable environmental management of high quantities of marine dredged material (DM) together with other industrial wastes is a common problem across Turkey. The beneficial use/recovery of DM and wastes in the production of lightweight aggregate (LWA) instead of dumping at sea/disposal will provide substantial environmental savings in terms of circular economy. In this study, the production of LWA by using marine DM, coal fly ash and waste foundry sand were investigated. Three different mixtures of raw materials were granulated in pelletizing disc, dried at 105°C and sintered in muffle furnace at 1100, 1150, 1170, 1180 and 1190°C with 5-10°C/min heating rates and 10-20 min sintering period. Sintered LWAs were analyzed in terms of physical, mechanical, microstructural, mineralogical and leaching properties. LWA produced at 1190°C sintering temperature, 5°C/min heating rate and 20 min sintering period resulted in better aggregate properties. Furthermore, according to the leaching test results; it is observed that the parameters of the eluate and original waste were lower than the Class III (inert waste) landfilling limit values due to the entrapment of those into the silicate matrix in sintering process; thus, causing no environmental risk to be used at construction sector. [ABSTRACT FROM AUTHOR]

This paper compares experimental results on the stabilization of clayey dredged material (DM) using quicklime (QL), hydrated lime (HL), portland cement (PC), and Class F fly ash (FA). The DM was a clay, high-plasticity soil, dredged from the US Army Corps of Engineers Port Arthur (USACEPA) facility along the Neches River located in Orange and Jefferson Counties, Texas. The soil consists of a large proportion of clay (66%), has high moisture limits (plasticity index: PI = 52 and liquid limit: LL = 80), and is characterized as a fat clay with silt. Physical properties of the untreated DM, such as unconfined compressive strength (UCS), consistency limits, and compaction behavior, were determined. Stabilizing reagents were mixed in various percentages by dry weight of DM. Results indicate that 12% QL, 6% HL, 6% PC, and 7.5% Class F FA by dry soil weight must be used to meet a minimum benchmark criterion of a PI value below 35, which was established based on Texas Department of Transportation (TxDOT) specifications. Standard compaction tests were carried out in accordance common standards with ASTM D698 to determine the optimum moisture content (OMC) for all mixtures. Stabilized mixtures were prepared at the corresponding OMC, and unconfined compressive tests were run according to common standards. Tests results were compared with the relevant literature, and a linear regression model was developed to predict the PI reduction as a function of initial PI, LL, and stabilizer type and content with good accuracy (R2 = 0.86). Overall, tests showed that stabilization of clayey DM using lime products, PC, or FA significantly improved the DM physical properties, which could then potentially be used as a local fill construction material that is cost-effective and environmentally friendly and reduces the overall use of cement products. [ABSTRACT FROM AUTHOR]

As concerns about sea-level rise mount, municipalities in coastal areas are looking to nature-based protection and adaptation. Oftentimes such projects are marsh creations or restorations, where areas of open water are filled with dredged material to an elevation where emergent vegetation can grow. We are investigating ways biosolids can be used as an amendment to dredged material to enhance project outcomes. Marsh mesocosms were constructed in San Francisco Bay and planted with native cordgrass, Spartina foliosa . Some mesocosms contained a subsurface layer of biosolids. Vegetation grown with biosolids had significantly increased number of new shoots, aboveground biomass, and belowground biomass. Vegetation with only dredged material had greater rooting depths but this result was not significant. By combining natural processes with human infrastructure, the application of biosolids for marsh creation is a sustainable practice. [ABSTRACT FROM AUTHOR]