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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.

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.

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.

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.

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.

Physical properties of soil material are essential criteria for the suitability of material to be used as cover layers or water retaining (ET) layers of landfills. Important parameters, such as available water capacity and saturated hydraulic conductivity, are usually derived from easily measurable properties (such as soil texture) with the help of tables, or are measured on artificially compacted samples in the laboratory. Both methods do not consider structural changes taking place mainly in the first years after installation. Key factors for the development of the soil structure are freeze-thaw cycles, swelling and shrinkage due to moistening and drying, and the influence of root growth. The investigation was carried out with dredged material (river sediments) which was planned to be used for a landfill cover layer. Freeze-thaw cycles were simulated for a few days each in a laboratory freezer; swelling and shrinkage was simulated by alternating between water saturation and complete drying in a drying oven. The vegetation experiment was carried out in the open on a site filled with 20 cm dredged material. The effects of the environmental factors result in a modification of the pore system. All variants showed a significant increase in air capacity and a significant decrease of the available water capacity at constant total pore volume. With respect to the suitability of the material for landfill cover layers, the results imply that that the legally specified minimum values for available water capacity should be rather increased due to a possible decrease over time. However, the average decline of the available water capacity of 6%v/v with time due to aging, and the assumed penetration depths of the aging processes in the upper third of the cover layer, would result in a rather small increase of a few decimeters in layer thickness necessary to achieve the water storage targets. More important seems the increase in air capacity due to aging processes, which is of considerable importance for the growth of plants especially in the upper part of the cover layer. The risk of too high soil density associated with too low air capacity for optimum plant growth, thus, is somewhat reduced due to the increasing air capacity with aging.

To maintain the navigational depth, 1.15 million cubic meters (1.5 million cubic yards) of sediment is dredged out from the federal harbors every year from Lake Erie, Ohio Coast. Treating this huge amount of dredged material is a major challenge due to the mobilization of potential contaminants causing depreciation in water quality and depletion of valuable land. Rather than treating the dredged material as a waste, we suggest investigating alternative ways to recycle and reuse the material within Green Infrastructure (GI) and living architecture applications. This study identifies potential applications of the dredged material in bioretention and vegetative roof systems, and examines the role of dredged material in these edaphic conditions. The paper discusses the beneficial uses of dredged material in GI by investigating the quality of dredged material and performances of GI built using dredged material through laboratory and field-testing. Preliminary results of a growth media using dredged material for the vegetative roof have been developed in lab/field studies that possess the performance values comparable to the current commercial product. The growth media containing lightweight aggregate, made from the dredged material, is observed to have high water retention capacity and high unit weight in comparison to a commercial product. The growth media leachate water test demonstrated the water quality to be comparable to the drained water from the commercial product. The growth media overwintered and advanced a rare plant species, Viola pedatifida, which is similar to conventional media. The beneficial uses of dredged material in the GI will help maintain the economic viability of harbors and ports along the shoreline of Lake Erie in Ohio and GIs, which were built using dredged material that can help address storm water management issues in urban areas due to extensive impervious surfaces.

The use of ripened fine-grained organic dredged materials as construction materials, e.g. as top soil on slopes such as landfills or dikes, is an important contribution to environmental engineering science. The materials are legally considered a waste and need to be beneficially re-used. Therefore, not only standard geotechnical parameter shave to be determined but also their erosion resistance which is a particularly critical environmental parameter. There is a variety of different tests to determine the flow dependent erosion resistance of soils, such as the erosion function apparatus (Briaud et al. 2001). In this study, however, the focus lays on the aggregate stability as an indicator for the erosion resistance under static loading, which can be determined using wet sieving and disintegration tests. The disintegration tests after Weißmann (2003) and Endell (RPW 2006) have a similar setup; however, the specific boundary conditions for the tests as well as the evaluation procedures are different. Weißmann proposed his test to determine the erosion stability of dike cover materials while the Endell test should be used for mineral sealing liners in navigation channels. In this study both tests have been used to evaluate the aggregate stability of fine-grained organic dredged materials that have been installed in large-scale research dike facilities and in the recultivation layers of different landfills. The materials showed good visual performance with respect to rainfall induced erosion so far; however, problems in determining erosion and aggregate stability indices limit the value of the studies: both disintegration tests investigated have major limitations with respect to the organic soils tested. Particularly the evaluation methods are not suitable for the soils but also some boundary conditions are critical and are discussed in this paper. The gained knowledge is a valuable basis for the development of standard characterisation methods for dredged materials in environmental and geotechnical applications.

In the project DredgDikes with partners from Poland and Germany different dredged materials from the South Baltic Sea region are investigated with respect to their application in dike construction. Two large-scale experimental dikes have been built, one in Germany and one in Poland. Additionally, an extensive laboratory testing programme has been realised and a considerable monitoring test programme will be followed. Based on a short general description of the project this paper covers the issue of installation technology for the dredged materials used and a discussion of geotechnical parameters to be determined for material evaluation and quality control. Due to the high and variable natural water contents of the organic soils together with their inhomogenous composition the compactability is difficult to predict and proctor values may not be reliably determined. During the installation three different compaction technologies were compared and no extreme differences could be found, which is why the compaction with a caterpillar was chosen for efficiency on site. The critical analysis of the data, however, shows slightly better compaction results for the roller compactors. In general the degree of compaction was comparably low. Therefore, different possibilities to improve compaction are discussed in this paper, such as the homogenisation of the dredged material by simple in situ mixing technologies, which will be issues for further research.

The present paper reports the results of an interlaboratory variability study of a bioassay using larval stages of the marine sea urchin Paracentrotus lividus. This exercise was developed in two different phases and included four laboratories, each of which determined the toxicity of six sediment samples. The samples were collected from different Spanish ports and were characterized by exposing sea urchin embryos for 48 h to sediment elutriates. Phase I was used to redesign test parameters and to avoid possible interfering factors when interpreting test results. Laboratories were more homogeneous in the classification of sediments according to the toxic responses in Phase II despite the high variability of the elutriate testing protocols. Based on our results, the test seems suitable to characterize dredged material, the interlaboratory variability being similar to that found for other bioassays in previous studies.

The Microtox® bioassay was tested in an interlaboratory study to evaluate the variability when using solid-phase samples. The exercise consisted of two consecutive phases each one carried out with six sediment samples from Spanish ports. Phase I included six laboratories that reported results for the solid-phase test (SPT) protocol, while Phase II included seven laboratories for the SPT protocol and three laboratories for the basic solid-phase test (BSPT) protocol. Even though some interfering factors were identified that could affect the results and sample classification, the coefficients of variation (CV) can be considered in the range for biological tests. When these factors are considered for further assessments, interlaboratory variability is significantly reduced. The BSPT showed lower CV values than the SPT despite the small number of participating laboratories. This better performance may be explained either by the simplicity of the methodology.

Interlaboratory variability was studied for the bioassay using crustacean amphipods. Nine series of data were obtained from different laboratories using four different species (Ampelisca brevicornis, Corophium volutator, Corophium multisetosum and Microdeutopus gryllotalpa), all previously used for sediment toxicity assessment in Spain. Results were studied for interlaboratory variability and according to different confounding factors. The coefficients of variation were similar to those previously reported for this bioassay and sample classification was homogeneous among the laboratories that successfully completed the exercise. No significant tendencies related to test species were identified and it seems that the factor most critically affecting test results and the classification of samples is storage time before testing.

Several species of bivalves and procedures have been used to characterize sediment toxicity. Here we report the results of an interlaboratory exercise that included three different laboratories to evaluate the use of the bioassay using the commercial clam Ruditapes philippinarum. Six different dredged sediments were studied using two different endpoints: lethality after two different exposure periods (7 and 14 days) and burrowing activity after 48 h of exposure. The lethal endpoint was only sensitive to characterize samples with high metallic concentration and following the 14-day exposure period. The burrowing activity showed very variable results that evidence the unsuitability of this endpoint for dredged material characterization. According to these results, a new design is recommended for the test using juvenile bivalves if it is to be used to characterize sediment samples on a regulatory context especially if sediments are not affected by metallic contamination.