Installation of fine-grained organic dredged materials in combination with geosynthetics in the German DredgDikes research dike facility

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

Functional analysis of the bacterial DNA repair protein complex SbcCD

The genomic integrity of all organisms is constantly challenged by genotoxic stress originating from endogenous and exogenous sources, with stalled replication forks (RFs) and double-strand breaks (DSBs) being among the most deleterious forms of DNA damage. Failure to properly respond to genomic distress can be highly mutagenic and lead to chromosomal aberrations. Thus, cells have evolved distinct DNA repair mechanisms. The Mre11-Rad50-Nbs1 (MRN) complex holds a key position in the DNA damage response (DDR) and is involved in the repair of DSBs, stalled RFs and dysfunctional telomeres. MRN acts by sensing and processing these diverse DNA structures and mediates signaling via the kinases ATM and ATR in eukaryotes. Although the MRN complex has been intensively studied for the last two decades, its fundamental mechanisms of action are still poorly understood. In particular, the nature of its ATP-dependent nuclease activities and how it specifically recognizes DNA ends remains unknown. The aim of this work was to investigate the biochemical activities of the bacterial Mre11-Rad50 homolog, SbcCD. For this purpose, biochemical assays were developed and established to study and functionally connect the enzymatic activities of SbcCD. These assays showed that SbcCD has a low basal ATPase rate. ATP hydrolysis is increasingly stimulated by (i) supercoiled DNA, (ii) double-stranded DNA and (iii) DNA ends. For its nuclease activity, SbcCD strictly requires DNA ends. SbcCD’s exonuclease activity depends on ATP binding, whilst the endonuclease activity requires ATP hydrolysis. A protein-blocked DNA end stimulates SbcCD’s endonuclease, which leads to internal cleavage of both DNA strands approximately 25 base pairs from the DNA end. Upon ATP hydrolysis, SbcCD also distorts the internal structure of the DNA duplex, implying that its DNA melting and endonuclease activities are functionally coupled. The position of SbcCD’s endonucleolytic cleavage is sensitive to 5 nucleotide DNA bubbles, which are cleaved on the 5’ side of the bubble. Therefore, a DNA bubble could be a transient intermediate, which is required for endonucleolytic cleavage. To generate this intermediate, it appears that a native SbcD dimer interface and the plasticity of the dimer interface are important. SbcCD cleaves the scissile phosphate on different sides, producing either 3’ or 5’ phosphates. The distinct cleavage products are determined by both the nuclease activity itself and the strand polarity. This suggests that the exo- and endonuclease activities have distinct cleavage mechanisms and could involve a geometrically flipped SbcCD complex. The presented results provide not only a more detailed knowledge of the mechanochemical performance of the SbcCD’s enzymatic activities, but also provide an important foundation for future structural investigations

The applicability of disintegration tests for cohesive organic soils

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

Overflowing tests at the Polish DredgDikes research dike – stability of the dike surface against erosion

In the project DredgDikes the different research dike embankments were tested with respect to overflowing water induced erosion. Therefore, flumes were installed on the land side embankments in which the effect of overflowing water on the vegetated surface was investigated. On the Polish DredgDikes research dike near Gdansk, Poland, two parallel flumes were installed and the surface of the dike made of different mixtures of ash, silt and sand as well as clay was tested both in vegetated and unvegetated state. The results showed that the grass sods placed on the dike embankment had a comparably low erosion stability, particularly if placed directly on the hardened ash/silt dike cover with better results if placed on a clay cover, while the ash/silt mixture showed a high erosion resistance without vegetation. This results in the recommendation to use a thicker vegetation layer on top of the ash composite dike if the vegetation shall account for the erosion resistance or else, that even if the grass cover is washed away, a very solid cover made of the ash composite can withstand an overflowing event for considerable time

South baltic oil spill response through clean-up with biogenic oil binders project : the SBOIL handbook

Without international cooperation, individual countries are usually lacking sufficient resources and assets for successfully responding to large-scale oil spill incidents. This end-result might be related to the vast quantities of oil involved in those incidents, or just to the fact that the necessary special equipment for dealing with the tasks at hand is not available/possessed by that one country under the need to respond, although it can be rather easily provided by a neighboring one. For successfully resolving oil spill incidents, close and effective international cooperation (especially between neighboring countries that usually face similar issues and “share the burden” of oil pollution in case the response is unsatisfactory) is obviously a vital necessity. The contemporary world relies heavily on oil to cover its energy needs. Unfortunately, oil spills at the locations of production, or during the associated transport endeavors continue to be one of the major threats to both society and the environment at the global level. Oil spills actually pose a greater threat in areas associated with major shipping routes, areas around pipelines and onshore/offshore rigs, as well as in the vicinity of oil and gas processing infrastructures. The United Nations Sustainable Development Goal 14, requires protection of our ocean, marine life and resources; therefore, minimizing possible oil spill incidents and their adverse impacts should be deemed as a very high priority.The project “South Baltic Oil spill response” (SBOIL) was co-funded by the European Union’s (EU) South Baltic Program, covering the period from summer of 2016 to the end of 2019. The University of Rostock, as the leading partner, cooperated with the World Maritime University and the Maritime University of Szczecin on the issue of “Oil Spill Response within the South Baltic Sea Region”, following the clean-up with biogenic oil binders perspective. SBOIL is a continuation of the project BioBind, which mainly focused on the creation and introduction into service of an oil recovery system designed for coastal waters, shallow areas and adverse weather conditions. The BioBind approach established a methodology relying on biodegradable oil binders that are deployed by airplanes and/or helicopters. The removal process involves a special net-boom, comprising of fishing nets and conventional containment booms. The project SBOIL aims to use this new “green” technology to improve present cross-border oil spill response capabilities. This handbook will provide the reader with basic knowledge about oil spills, response measures and the structural approaches of the individual South Baltic (SB) countries of Sweden, Denmark, Germany, Lithuania, Poland and Russia. It aims to close an existing information gap in relation to oil spill response without contradicting existing regulations and already established policies and guidelines. Furthermore, it aspires to improve international collaboration between local and regional authorities and facilitate their better interaction with the respective national incident managers. A certain number of both national and international workshops, as well as an expanded portfolio of capacity building activities based on a table top exercise have been implemented as part of this project; their most important findings and recommendations are summarized in the sections that follow.The SBOIL project has designed and implemented a very wide range of activities (various SBOIL spill response exercises, national workshops and an international table top exercise), developed spill response scenarios and a biogenic spill response training kit to inform and train people engaged with oil spill response during and after the project. Furthermore, a designated station to be used in the future during a relevant emergency situation was created. Additionally, a biogenic spill response training package in the simulator setting (via a nautical simulator) was developed to cover the needs of the people that will handle this new equipment/technique. As a starting point, this handbook will focus primarily on providing a comprehensive overview on oil spills in the South Baltic (SB) Sea area, including the related response measures in general. It will also summarize the above mentioned Baltic Sea countries’ structural approaches, as well as their respective legal frameworks in relation to the issue of oil spill response.This handbook will also provide an insight into the lessons learnt from the tabletop exercise in Poland in 2018, as well as those derived from the national workshops that took place during the 2017-2019 timeframe in Sweden and Poland.https://commons.wmu.se/lib_books/1003/thumbnail.jp

South Baltic Oil Spill Response Project (SBOIL)—Development and Implementation of Models of Drift and Fall Trajectories of Biogenic Oil Binders

This paper presents the methodology, assumptions, and functionalities of an application developed during the realization of the project “South Baltic Oil Spill Response through Clean-up with Biogenic Oil Binders” (SBOIL). The SBOIL project is a continuation of the BioBind project, the primary goal of which was to develop and deploy an oil recovery system designed for use in coastal waters and adverse weather conditions. The goal of the SBOIL project was to use this new technology to improve the current response capabilities for cross-border oil spills. The developed application allows for the determination of the position of an aircraft at the time of dropping the oil binders, the determination of the oil binders’ position after falling in terms of a specific aircraft’s position, the determination of the position of oil binders after a certain time in order to plan the action of recovering it from the water surface, and the determination of the time when the binders will be in their assumed position

Geosynthetics in geoenvironmental engineering

Geosynthetics are planar polymeric products, which are used in connection with soil, rock or other soil-like materials to fulfill various functions in geoenvironmental engineering. Geosynthetics are of ever-growing importance in the construction industry. Sealing of waste storage facilities to safely prevent the emission of wastewater, landfill gas and contaminated dust as well as the diffusion of pollutants into the environment and coastal protection against storms and floods and reconstruction after natural disaster are important fields of application. We will give an overview of the various geosynthetic products. Two examples of the material problems related to geosynthetics are discussed in detail: the effect of creep on the long-term performance of geocomposite drains and the numerical simulation of the interaction of soil with geogrids. Both issues are of importance for the use of these products in landfill capping systems. The various functions, which geosynthetics may fulfill in the protection of coastal lines, are illustrated by case studies. The geosynthetic market is evaluated and economical and environmental benefits, as well as environmental side effects related to the use of geosynthetics, are discussed

Infiltration behaviour of dike covers made of dredged material on the Rostock Research dike

The knowledge about the infiltration behaviour of a dike body is an important issue in dike design and flood risk assessment. To reduce the risk of stability failures during flood events, the infiltration rate of a dike should be kept low and the elapsing time to reach the saturated steady state should be long. A number of full-scale physical flood simulation experiments on the Rostock research dike, on which different processed dredged materials were applied in the dike body (cover layers in particular) showed that the infiltration time and rate is much higher as can be expected from comprehensive laboratory test data. To obtain information about the unsaturated/saturated hydraulic soil properties of the installed dredged materials in situ, an automatic multi-objective model calibration method for a minimizing problem is used to reduce the residuals between simulated and observed time series (hydraulic head pressure, suction pressure and rate budget). The measured suction pressure time series of these physical experiments lets us suppose, that it is not possible to simulate the suction pressure behaviour of the installed dredged material using RICHARD’s unsaturated flow equation with a proper water retention function and unsaturated flow conductivity. It seems that the hysteresis effects are negligibly small and the hydraulic behaviour is governed by the inter-aggregate pore structure. In the paper, different back-calculation methods to fit the soil hydraulic parameters to the full-scale measurements are discussed and compared a proposal for the evaluation of the data is provided