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1
Glover, Gordon Jason. "Laboratory modeling of hydraulic dredges and design of dredge carriage for laboratory facility : a thesis." Thesis, Monterey, California. Naval Postgraduate School, 2002. http://hdl.handle.net/10945/3051.
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The deepening and maintenance of the world's ports and navigable waterways has been an
integral part of the world economy for centuries. In recent years, cutterhead and draghead
hydraulic suction dredges have performed a majority of the dredging work. The ongoing design
and testing of hydraulic dredges is important for maintaining efficient dredging operations within
the limits set by increasing environmental regulations.
The high cost of building and operating a hydraulic dredge makes field testing of full-scale
prototypes very expensive and time consuming. Moreover, the testing conditions are generally
difficult to control, and the natural unpredictability of the sea can render experimental results
inconclusive. These factors substantiate the need for laboratory model testing of hydraulic
dredging operations.
The usefulness of any hydraulic model depends on the degree of geometric, kinematic, and
dynamic similarity between the model and its prototype. The primary challenge in establishing
useful similitude criteria for model dredge studies is proper kinematic scaling of the suction inlet
velocity, average particle settling velocity, dredge swing velocity, and cutter rotational speed.
Despite the inherent challenges, model studies of hydraulic dredge equipment have proven useful
for obtaining qualitative results.
The new Coastal Engineering Laboratory at Texas A&M University is equipped with model
dredge testing facilities ideal for performing such experiments. The tow/dredge carriage has a
fully adjustable dredge ladder, a 14.9 kW (20 hp) cutter drive, and a 2.54 cm (3 in) dredge pump.
A Programmable Logic Controller (PLC) provides computer numerical control and real-time data
collection and analysis during model dredging operations.
The purpose of this thesis is to investigate scaling relationships for hydraulic dredge model
studies and to design a model dredge carriage for the new laboratory facilities recently
constructed at the Texas A&M University College Station campus. Pursuant to the design of the
new dredge modeling facilities, a rationale for scaling the model dredge operating parameters
based on previous model studies is put forward. Examples of model studies that could be
performed with the proposed facilities are discussed as well as how the scaling methodology is
applied to each experiment to allow the quantitative interpretation of experimental data.
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Adair, Robert Fletcher. "Estimating production and cost for clamshell mechanical dredges." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/1536.
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Clamshell dredges are used around the United States for both navigational and environmental dredging projects. Clamshell dredges are extremely mobile and can excavate sediment over a wide range of depths. The object of this thesis is to develop a methodology for production and cost estimation for clamshell dredge projects. There are current methods of predicting clamshell dredge production which rely on production curves and constant cycle times. This thesis calculates production estimation by predicting cycle time which is the time required to complete one dredge cycle. By varying the cycle time according to site characteristics production can be predicted. A second important component to predicting clamshell dredge production is bucket fill factor. This is the percent of the bucket that will fill with sediment depending on the type of soil being excavated. Using cycle time as the basis for production calculation a spreadsheet has been created to simplify the calculation of production and project cost. The production calculation also factors in soil type and region of the United States. The spreadsheet is capable of operating with basic site characteristics, or with details about the dredge, bucket size, and region. Once the production is calculated the project cost can be determined. First the project length is found by dividing the total amount of sediment that is to be excavated by the production rate. Once the project length is calculated the remainder of the project cost can be found. The methods discussed in this thesis were used to calculate project cost for 5 different projects. The results were then compared to estimates by the government and the actual cost of the project. The government estimates were an average of 39% higher than the actual project cost. The method discussed in this thesis was only 6% higher than the actual cost.
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Milleville, Kelli A. "Twine-Top Modifications of Sea-Scallop Dredges: Reducing Yellowtail-Flounder Bycatch." W&M ScholarWorks, 2008. https://scholarworks.wm.edu/etd/1539617874.
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Rudders, David B. "A Comparison of Size Selectivity and Relative Efficiency of Sea Scallop Trawls and Dredges." W&M ScholarWorks, 1999. https://scholarworks.wm.edu/etd/1539617978.
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Marquardt, Lisa [Verfasser]. "Looking Beyond The Dredges : The Consideration of Alternatives in the Planning and Approval of Port Development in Germany and New Zealand / Lisa Marquardt." Baden-Baden : Nomos Verlagsgesellschaft mbH & Co. KG, 2014. http://d-nb.info/1107604052/34.
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Jakku, Emma, and n/a. "Murky Waters? Science, Politics and Environmental Decision-Making in the Brisbane River Dredging Dispute." Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040810.131650.
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Environmental sociology and the sociology of scientific knowledge provide a strong theoretical foundation for investigating the role of science in environmental disputes. The field of environmental dispute resolution has built a body of literature, outlining the techniques and practices that underpin the successful resolution of disputes, over controversial environmental issues. However, the literature on dispute resolution has generally neglected the role of science in environmental disputes. This thesis develops a theoretical framework based on concepts from environmental sociology and the sociology of scientific knowledge in order to critically examine the role of science in environmental disputes. In particular, this thesis combines the theory on claims-making from environmental sociology with actor-network theory and the theory on boundary-work from the sociology of scientific knowledge, to analyse the way in which science was involved in the dispute over phasing out extractive dredging from the Brisbane River. Data were collected from qualitative in-depth interviews with key players in the Brisbane River dredging dispute and combined with analysis of relevant documents and newspaper articles. Each of the components of the theoretical framework developed in this thesis contributes to an in-depth analysis of the way in which science was involved in the dredging dispute. The environmental claims-making analysis examines the way in which the claim that extractive dredging was an environmental problem for the Brisbane River was constructed and contested. The actor-network analysis compares the two competing actor-networks that were developed by one of the major concrete companies and by the anti-dredging campaigners. The boundary-work analysis examines the social construction of the science / politics border as an important site of boundary-work, before exploring other related forms of boundary-work within the case study. When combined, these theories highlight the social and political processes that underpin the inherent difficulties associated with applying science to effective environmental dispute resolution. The theoretical framework developed in this thesis highlights the way in which an analysis of environmental claims-making, actor-networks and boundary-work, extends the literature on environmental dispute resolution. This thesis therefore makes a significant contribution to the field of environmental dispute resolution, by illustrating the advantages of drawing on theoretical perspectives from environmental sociology and the sociology of scientific knowledge.
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Jakku, Emma. "Murky Waters? Science, Politics and Environmental Decision-Making in the Brisbane River Dredging Dispute." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/366055.
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Environmental sociology and the sociology of scientific knowledge provide a strong theoretical foundation for investigating the role of science in environmental disputes. The field of environmental dispute resolution has built a body of literature, outlining the techniques and practices that underpin the successful resolution of disputes, over controversial environmental issues. However, the literature on dispute resolution has generally neglected the role of science in environmental disputes. This thesis develops a theoretical framework based on concepts from environmental sociology and the sociology of scientific knowledge in order to critically examine the role of science in environmental disputes. In particular, this thesis combines the theory on claims-making from environmental sociology with actor-network theory and the theory on boundary-work from the sociology of scientific knowledge, to analyse the way in which science was involved in the dispute over phasing out extractive dredging from the Brisbane River. Data were collected from qualitative in-depth interviews with key players in the Brisbane River dredging dispute and combined with analysis of relevant documents and newspaper articles. Each of the components of the theoretical framework developed in this thesis contributes to an in-depth analysis of the way in which science was involved in the dredging dispute. The environmental claims-making analysis examines the way in which the claim that extractive dredging was an environmental problem for the Brisbane River was constructed and contested. The actor-network analysis compares the two competing actor-networks that were developed by one of the major concrete companies and by the anti-dredging campaigners. The boundary-work analysis examines the social construction of the science / politics border as an important site of boundary-work, before exploring other related forms of boundary-work within the case study. When combined, these theories highlight the social and political processes that underpin the inherent difficulties associated with applying science to effective environmental dispute resolution. The theoretical framework developed in this thesis highlights the way in which an analysis of environmental claims-making, actor-networks and boundary-work, extends the literature on environmental dispute resolution. This thesis therefore makes a significant contribution to the field of environmental dispute resolution, by illustrating the advantages of drawing on theoretical perspectives from environmental sociology and the sociology of scientific knowledge.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
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Gurriet, Philippe C. (Philippe Charles). "Geochemistry of Hawaiian dredged lavas." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/54327.
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Hossain, Abdul Siddik. "Improvement of Dredged Sediments : A laboratory study on dredged sediments with different types of binders." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65019.
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tabilization and solidification (S/S) technique have been the most frequently used method for dredgedsediment improvement in Sweden and worldwide. As dredging activities are essential for safe navigationof ships and vessels that may processes harmful substances or organic pollutants to causecontamination of the surrounding environment. Stabilization/solidification technology has beenidentified as the most beneficial handling strategy for contaminated dredged sediments and treatedstabilized materials can be used in civil engineering applications (e.g. backfill or embankment). This (S/S)technique is the easiest way of improving high water content dredged sediments using different types ofbinders. During the stabilization process, dredged sediments are mixed with commonly used binders,such as Portland cement, fly ash and ground granulated blast furnace slag (Merit 5000). Nowadays,supplementary cementitous materials such as (fly ash and blast furnace slag) are being used increasinglyconsidering long term strength development of stabilized dredged materials instead of using morecement. Generally, cement hydration is a complex chemical-reactions. By addition of supplementarycementitious materials, it becomes more complex because of cement hydration and pozzolanicreactions. The overall objective of this thesis work is to improve the understanding of compressibilityand strength behavior of stabilized dredged materials. To achieve these objectives, a series ofunconfined compressive strength tests and consolidation tests were performed on stabilized dredgedmaterials (SDM) with different types and mixing ratios of binders. These lab tests have been focused onthe compressibility and strength properties of stabilized materials. The UCS test determines the amountof binders and curing time needed to achieve the required shear strength of SDM. The outcomes of thisthesis work show that the stabilized dredged sediments constitute of binder mixing ratio (Cement:Flyash:Merit 5000 as a proportion of 10:10:5) which is 25% of the total fresh dredged sediments can’tsustain any superstructure or surcharge load but it can only be used as backfill materials on site.Whereas, stabilized dredged material with binder mixing ratio (Cement:Fly ash:Merit 5000 as aproportion of 20:20:10) which is 50% of the total fresh dredged Sediment becomes stiff after 28 dayscuring and becomes very stiff after 91 days curing. It becomes obvious that the unconfined compressivestrength of SDM increases with higher amount of binders and longer curing time. The pozzolanicreaction continues after 28 days curing period. The presence of supplementary cementitous materials(fly ash, blast furnace slag and merit 5000) can improve the ductility of stabilized dredged materials(SDM) in the post-peak strength degradation zone without changing the unconfined compressivestrength. It is also obvious from the test results that the UCS values of stabilized dredged materialsincrease with decreasing moisture content/increasing bulk density. The consolidation properties of SDMare greatly influenced by the binder mixing ratio, curing time and preloading weight. Due to preloadingweight, the deformation in stabilized dredge sediments is irreversible because of cementation andpozzolanic effects. Considering both curing time and binder ratio, compression index (Cc) and swellingindex (Cs) values for SDM with binder ratio (20:20:10) have been lowered approximately by 75% and67%, respectively than SDM with binder ratio (10:10:5). After 91 days curing of SDM with binder ratio(20:20:10), the maximum value of tangent modulus is estimated about 9624 kPa which indicates thatthe superstructure can be erected on stabilized dredged materials. It is also concluded that physicochemicalvariables control the consolidation behavior of stabilized dredge materials (SDM) as thecoefficient of consolidation (Cv) value decreases with increasing consolidation pressure.
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Smith, Stanley Jarrell II. "Fine Sediment Dynamics in Dredge Plumes." W&M ScholarWorks, 2011. https://scholarworks.wm.edu/etd/1539616859.
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The research presented in this study is motivated by the need to improve predictions of transport and fate of cohesive sediments suspended during dredging operations. Two techniques are presented to quantify vertical sediment flux within dredge plumes. A mass-balance approach using an Acoustic Doppler Current Profiler (ADCP) is described and demonstrated to accurately estimate vertical mass flux and settling velocity for a suspension of fine sand from a dredged material placement operation. A new digital video settling column for simultaneous measurement of particle size and settling velocity is described and evaluated. The Particle Imaging Camera System (PICS) is a single-chambered, digital video settling column, which permits rapid acquisition (within 2--3 minutes) of image sequences within dredge plumes. Image analysis methods are presented, which provide improved estimates of particle size, settling velocity, and inferred particle density. A combination of Particle Tracking Velocimetry (PTV) and Particle Image Velocimetry (PIV) techniques is described, which permits general automation of image analysis collected from video settling columns. In the fixed image plane, large particle velocities are determined by PTV and small particle velocities are tracked by PIV and treated as surrogates for fluid velocities. The large-particle settling velocity (relative to the suspending fluid) is determined by the vector difference of the large and small particle settling velocities. The combined PTV/PIV image analysis approach is demonstrated for video settling column data collected within a mechanical dredge plume in Boston Harbor. The automated PTV/PIV approach significantly reduces uncertainties in measured settling velocity and inferred floc density. Size, settling velocities, and density of suspended sediments were measured with PICS within a trailing suction hopper dredge plume in San Francisco Bay. Results indicated that suspended sediments within the plume were predominantly in the clay and fine silt size classes, as aggregates with d>30 microm. Suspended bed aggregates (defined by densities of 1200 to 1800 kg m-3) represented 0.2--0.5 of total suspended mass, and size and settling velocity of this class were time invariant. Flocs (densities<1200 kg m-3) represented 0.5 to 0.8 of total suspended mass, and size and settling velocity of flocs was seen to increase with time. The peak diameter of bed aggregates and flocs occurred near 90 microm and 200 microm, respectively, corresponding to peak settling velocities of about 1 mm s-1 in each case. Floc settling velocities increased with particle size d1.1, while bed aggregate settling velocity increased like d1.3. Numerical modeling approaches to representing settling velocities for hopper dredge plumes are discussed in light of the experimental findings. Size-dependant settling velocities were well-described by a fractal-based relationship when the suspension was treated with discrete classes for each of the aggregate states. Time-dependent increases in floc size and settling velocity confirm that flocculation is a first-order process which should be included in numerical plume models. Correlations between settling velocity and suspended sediment concentration were weak and statistically insignificant, implying that commonly applied empirical relationships are inappropriate for dredge plumes.
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Tessler, Thomaz Martino. "Weather downtime analysis for cutter suction dredgers." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-26012017-092026/.
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The dredging activity is increasing worldwide due to ships that require bigger drafts, and consequently deeper navigation channels. Some dredging projects requires the operation of cutter suction dredgers on open waters, once these are capable of removing compact sediments and rocks while still maintaining a good productivity. These facts motivated the creation of a weather driven downtime prediction software for this type of operation, based on simplified calculations of the main dredging systems of a CSD. The motions caused by waves, and the forces and moments caused on these dredgers by winds, waves and currents were analyzed in order to evaluate the influence of each parameter magnitude and direction on the behavior of the vessel. The main criteria of the dredger influenced by this conditions were determined by a literature review as being the swing winch required power, the interaction between the cutterhead and the soil, and the anchoring system resistance, this that can be both a spud pole system stress or the Christmas tree cable tension. In this research, only the spud pole system bending stress was considered. Three mathematical models were developed to represent those systems. Since the non-linearity of the relation between the reaction forces of the dredger and the soil was not an object of the study, this process is represented by a constant user defined reaction force and a horizontal cutterhead velocity model. The efficiency of these models were tested by applying them on a case study of the dredging of the Açu port on the Brazilian coast by the Taurus II dredger. Simultaneous wind, wave and current data data were used as input to these models by creating a time series scenario of the operation period. The results for both scenarios showed that the operation would be close to impossible due to wave generated dynamic stress on the spud pole.A atividade de dragagem no mundo é cada vez mais significativa em função do aumento dos navios que operam em portos, estes que possuem maior calado e requerem, consequentemente, canais de navegação mais profundos. Alguns projetos de dragagem utilizam dragas de sucção e recalque em mar aberto, dada a capacidade destes equipamentos de remover sedimento compactado e rochas, ainda mantendo uma boa produtividade. Estes fatos motivaram a criação de um programa de previsão de downtime gerado por condições ambientais de dragas de sucção e recalque baseado em modelos matemáticos simplificados. Os movimentos causados por ondas, e as forças e momentos causados na draga por ventos, ondas e correntezas foram analisados de forma a se obter a influência da magnitude e direção de cada um destes parâmetros no comportamento da embarcação. Os principais sistemas da draga influenciados por estas condições foram determinados com base em uma revisão bibliográficas como sendo a potência requerida nos guinchos de varredura, a interação do cortador com o solo e a resistência do sistema de ancoragem, sendo este a tensão de flexão dinâmica na trave do spud ou as tensões de ancoragem pelo sistema de árvore de natal. Três modelos matemáticos foram desenvolvidos para representar estes sistemas. Considerando a não linearidade da interação entre a draga e o solo, este processo foi representado por uma força de reação definida pelo usuário e pela velocidade horizontal do cortador. A eficiência destes modelos foi testada ao aplicá-los em um estudo de caso da dragagem do porto de Açu, na costa brasileira pela draga Taurus II. Valores simultâneos de ondas, ventos e correnteza foram utilizadas como entrada nestes modelos, através da criação de um cenário hipotético de série temporal. Os resultados para ambos os casos demonstraram que a operação seria impossibilitada em função de tensões de flexão dinâmicas no spud maiores que o limite determinado.
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Haus, Nicholas Wes. "Beneficial Reuse of Dredged Materials in Upland Environments." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/36317.
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Sediments excavated from dredging operations are known as dredged materials. Beneficial reuse of dredged materials in confined utilization facilities (CUFs) is a new approach that has the potential to productively utilize large quantities of dredged materials. However, several factors can inhibit the use of dredged materials in CUFs. In this study, high levels of salts and polycyclic aromatic hydrocarbons (PAHs) were investigated. In the first part of this study, 176,000 m3 of saline dredged materials was placed into a CUF. In less than 4 years, most of the dredged materials had developed horizonation and converted to Inceptisols. The formation of pedogenic Bg horizons in these soils occurred after a polygonal prism network had developed which partially disintegrated into a blocky structured, oxidized horizon with an abundance of redoximorphic features. During the study period, the soil chemistry of the weathering dredged materials shifted from Na-dominated to Ca and Mg-dominated system, allowing plant invasion. In the second part of the study, a bench-scale greenhouse bioremediation experiment was conducted to test the effectiveness of biosolids, compost, and straw at enhancing PAH degradation. Initial concentrations of PAHs decreased significantly after 150 days using standard methods of extraction. However, at 327 days the concentrations of many PAHs, especially those with higher molecular weights, had rebounded close to initial levels. This indicates that PAH bioremediation studies using organic matter additions and conducted using standard methods of extraction need to be carried out longer periods of time or that extraction methods need to be improved.Master of Science
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de, Ruyter Marcus J. M. "Two-dimensional cut plan optimization for cutter suction dredgers." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/79367/.
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Optimal cut plans for cutter suction dredgers aim to maximize operational efficiency. Maximizing operational efficiency involves minimization of stoppage time resulting from non-productive dredger movements. To automate a systematic search for optimal twodimensional cut plans for cutter suction dredgers two models with an adaptive simulated annealing-based solution approach were developed. The first model, the dredge cut nesting model, optimizes irregular stock cutting problems where stencils represent dredge cuts and sheets represent dredging areas. Stencils are collections of unit dredge cuts with dimensions related to an effective cutting width which can be achieved with the cutter suction dredger considered. The objectives of the dredge cut nesting model are to maximize sheet coverage and to minimize stencil overlap. Centroids of unit dredge cuts of final nest layouts are extracted and used as grid nodes in the second model. The second model, the dredger routing model, optimizes asymmetric travelling salesperson problems with turning costs. The objectives of the dredger routing model are to minimize total route length and sum of turning angles, and to maximize average link length. A link consists of two or more route edges which are aligned with each other to within specified limits. A significant result of this research is that an engineering application of both models showed that two-dimensional cut plans for cutter suction dredgers can be systematically optimized and that dredger routes with minimum turning costs can be found. However, results also showed that the dredger routing model is not yet sophisticated enough to find cut plans for cutter suction dredgers for which overall project execution time is minimal.
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De, Silva Michael S. W. "Chemical and biological aspects of using dredged river Clyde sediments for land restoration." Thesis, University of Strathclyde, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292081.
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Makusa, Gregory Paul. "Mechanical properties of stabilized dredged sediments : for sustainable geotechnical structures." Licentiate thesis, Luleå tekniska universitet, Geoteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17437.
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Dredging activities at Ports and Harbors are inevitable for the safe navigation of ships and vessels. Dredged material may range from very fine and contaminated sediments to sand and gravels. While, granular dredged material can be directly utilized in civil engineering applications, fine sediments may require further treatment before use. In geotechnical context, fine sediments are characterized by low shear strength and high compressibility. However, these unfavorable properties do not rule out the suitability of these fine dredged sediments for use in geotechnical construction, such as, road embankment, building foundation or as structural backfill in land reclamation. Mass stabilization solidification provides a comprehensive technology for amending fine sediments at high initial water content, resulting into construction materials of improved strength and reduced compressibility. The ultimate in-situ soil behavior types, stiffness and strength properties of stabilized mass depend on various factors such as binders, mixing equipment, curing temperature, in-situ boundary conditions and mostly important the applied preloading weight during the period of curing. However, despite improved mechanical properties for geotechnical applications, the performance of treated materials becomes susceptible to repeated freeze-thaw cycles. Understanding geotechnical design process, which includes evaluation of material properties, loading condition and selection of appropriate constitutive model, is an important task for settlement and stability analysis of structures founded on stabilized mass. The selection of suitable material model is vital for successful finite element analysis. Nevertheless, among all existing constitutive soil models, none of them can capture all aspects of soil behavior. Therefore, the meaningful and quantifiable predictions of field behaviors are possible only if, undisturbed samples or in-situ tests are used for determination of mechanical properties, and the predictive capacity of selected constitutive model comes from the comparison with field observations In the present research work, utilization of cone penetration test (CPT) data for evaluating the mechanical properties of stabilized dredged sediments for geotechnical design and analysis was presented. A large-scale field test at the Port of Gävle was utilized as a case study, to verify the simulated settlement of preloaded stabilized dredged sediments. The stabilized mass–soil classification behavior type was studied utilizing CPT classification charts. Computation of the primary consolidation settlement due to preloading weight were carried out in PLAXIS 2D geotechnical software and verified against field measurements. A suggestion to protect the stabilized mass against severe weather condition was discussed.Godkänd; 2013; 20130409 (makusa); Tillkännagivande licentiatseminarium 2013-04-25 Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Gregory Paul Makusa Ämne: Geoteknik/Soil Mechanics and Foundation Engineering Uppsats: Mechanical Properties of Stabilized Dredged Sediments for Sustainable Geotechnical Structures Examinator: Professor Sven Knutsson, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Civ.ing. Forskningsdirektör Göran Holm, Statens Geotekniska Institut, Linköping Tid: Torsdag den 16 maj 2013 kl 10.00 Plats: F1031, Luleå tekniska universitet
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Gorham, Richard Arthur. "All dredged up and no place to go : the disposal of contaminated dredged material from greater Vancouver, British Columbia, into the neighbouring strait of Georgia." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24673.
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The thesis provides an integrated review and analysis of strategic scientific information from which management procedures for the environmentally acceptable disposal of dredged materials from Greater Vancouver into the Strait of Georgia are determined. An analysis of reported and suspected contamination of Vancouver's waterways identifies trace metals and hydrophobic organic chemicals that warrant concern by authorities responsible for the management of dredged material disposal. The processes, transformations and pathways of these contaminants in the marine environment subsequent to dredged material disposal are reviewed. It is argued that a really confined degradation of suitable disposal sites is of negligible concern, but that release of contaminants from the disposal area, were it to occur, could have unpredictable and perhaps substantial environmental consequences. The major potential pathway of contaminant release from dredged material during or subsequent to disposal is via the resuspension and transport of fine particulate material. Biological accumulation of contaminants and their transport through the food chain is a potentially significant release pathway for hydrophobic organic contaminants. Biological transformation to more soluble metabolites is also potentially significant for mercury and some of the less chlorinated and lower molecular weight organic compounds of concern. Desorptive release of contaminants from the disposed sediments into solution is usually negligible, with the possible exceptions of cadmium and mercury. A review of the physical factors that promote contaminated sediment erosion and dispersion during or subsequent to dredged material disposal identifies oceanographic characteristics where such release will be minimal. There are only four areas within the Strait of Georgia that exhibit these characteristics. Two of these areas are adjacent to valuable and sensitive biological resources and are consequently unsuitable as ocean dumping sites. Dredged material disposal at the other two sites, one near Smelt Bay, Cortes Island, and the other off McNaughton Point, Sechelt Peninsula, should result in minimal adverse environmental impact. Available methodologies to identify dredged materials with contaminant levels that preclude their environmentally acceptable disposal at these recommended sites are discussed.Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate
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Betteker, James Michael. "A laboratory study of solidification/stabilization technology for contaminated dredged material." Thesis, Virginia Tech, 1986. http://hdl.handle.net/10919/45748.
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Safe disposal of contaminated dredged material has become a significant issue especially as public environmental awareness and concerns increase. Solidification/ stabilization technology potentially may provide for a safer, more effective and more economical means of disposal.
This research investigated the technical feasibility of applying solidification/stabilization technology to contaminated sediment from Indiana Harbor Canal, Indiana. Specifically, physical strength and reduction of chemical leachability resulting from solidification/stabilization A with various cement based, pozzolanic, and proprietary additives were analyzed. Also investigated was the immobilization capability of a proprietary polymer for selected organic contaminants when used in conjunction with solidification/stabilization processes.
Physical strength is an important parameter in determining the ultimate bearing capacity, stability of embankments and pressure against retaining walls. Physical stabilization of contaminated dredged material is a viable treatment option. Application of cement-based and pozzolanic—based processes uses the sediment moisture to form hydration products, therefore dewaterimg is not required. All process formulations produced a solidified sediment.Master of Science
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Crawford, Anika. "Beneficial reuse of Baltimore dredged sediments as vertical cutoff wall backfill material." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1473.
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Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Civil and Environmental Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Ma, Kit-cheong James, and 馬傑昌. "Hong Kong Government criteria for assessing contamination levels of dredged marine sediments." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31254718.
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Reed, Jaqueline. "Polychlorinated biphenyls in marine sediments and dredged material around England and Wales." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395670.
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Mattson, Gregory A. II. "Characterization of Dredged Sediment Used in Coastal Restoration and Marsh Creation Projects." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1823.
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To minimize coastal land loss and create new land, dredged sediment has been in use in coastal Louisiana during the last several years. Engineering properties and material characteristics of dredged material are input parameters in several mathematical models used to predict the long-term hydrodynamic behavior of the coast. Therefore, proper characterization of the dredged material is of utmost importance in the correct design of coastal restoration and land creation projects. The sedimentation characteristics of the dredged material, among other factors, depends on the (a) grain size distribution of the dredged material, (b) salinity (fresh, brackish, or saltwater environment) of the composite slurry, and (c) concentration of the solid particles in the slurry. In this research, dredged sediments obtained from actual coastal restoration projects were characterized. Furthermore, the effects of grain size distribution, salinity and solid particle concentration on sedimentation characteristics have been evaluated.
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Ma, Kit-cheong James. "Hong Kong Government criteria for assessing contamination levels of dredged marine sediments /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22264474.
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Flaim, Bryna K. "The Continental Shelf as a Site for Dredged Material Disposal, Northeast New Zealand." The University of Waikato, 2008. http://hdl.handle.net/10289/2445.
Full textAbstract:
Disposal of dredged material has been an on-going problem in the Auckland Coastal Marine Area (CMA) since the early 1980s in New Zealand. Many disposal grounds have been established and used, but public concern over adverse effects resulted in their ultimate closure. Presently, dredged material is disposed off-shore at a site simultaneously accessed by the Royal New Zealand Navy for disposal of WWII munitions recovered from coastal areas. As early as the mid-1990s, parliamentary focus groups established the need for a more suitable disposal option for dredged material. Establishment of a disposal site north of Cuvier Island in waters deeper than 100 m was one of the key recommendations presented by these groups. The need for a new site was compounded after the establishment of the Hauraki Gulf Marine Park in 2000. Taking up the majority of the Auckland CMA this culturally significant Park makes the consent for open water disposal a complex process. A site east of Great Barrier Island in 140 m of water has been identified as a potential suitable site for disposal of dredged material. The main goal of the present study is to determine the suitability of this site and provide the necessary information required by enforcing authorities for permit submission. Investigations to determine the suitability of the site were undertaken in several ways. An extensive literature review of previous studies was carried out to gain insight into the physical and biological characteristics of the northeast coast and shelf. The main hydrodynamic features of the region and the observed behaviours were determined. Attentions were then directed at determining the more specific site characteristics. Analytical calculations were undertaken using known site parameters to estimate the potential for transport of sediment away from the site after disposal. Through analysis of known wave and current measurements it was estimated that only rarely would sediment be entrained off the seafloor. Samples were then collected from the site in November 2007, which were used for sediment textural analysis and benthic identification. It was determined that the main textural component of the site sediments is muddy/sand. Diversity of benthic species is relatively high, but abundance is low. Polychaetes were the most diverse and abundant taxon identified at sample locations across the site. Next, the 3DD model was used to numerically simulate 2-dimensional tidal currents. Depth-averaged spring tidal currents at the site were predicted to be less than 0.2 ms-1. The derived bottom velocity for such a current is 0.08 ms-1, which is much less than the velocity required for initiation of sediment movement in this case. The numerical simulation also showed that residual spring tidal flow is directed to the southeast. Finally, an assessment of potential impacts was done by reviewing previous studies of ecological impacts caused by disposal of dredged material. Based on the preliminary studies summarised above, the review of potential impacts indicates that there will only be minimal effects at and surrounding the proposed site. The result of this study is an encouraging step toward establishment of a new disposal option, but further research is required to confidently declare that the site is suitable for disposal operations.
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Cimino, Vito A. "Optimal placement of dredged material for wetland development within the Charles Mill Reservoir." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1173810919.
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Morello, Elisabetta Lavinia Betulla. "Assessment of the impact of hydraulic dredgers for chamelea gallina in Italian waters." Thesis, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406542.
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Jeoung, JaeHyeung. "Solidification/stabilization of dredged sludge with low alkalinity additives and geo-environmental assessment." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/148536.
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Rudders, David B. "Incorporating industry based dredge surveys into the assessment of sea scallops, Placopecten magellanicus." W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539616833.
Full textAbstract:
Cooperative research utilizing industry vessels represents a viable approach to acquire the data necessary to meet the increasing needs associated with the modern management of marine resources. This dissertation addresses a variety of topics associated with the integration of commercial vessels into the stock assessment of the sea scallop, Placopecten magellanicus. In this study we evaluate the efficacy of utilizing industry vessels with respect to topics that range from rotational closed area survey design, sampling gear evaluation as well as an experiment that broadens the scale of the traditional use of industry vessels in this fishery and provides data to support the use of commercial vessels for surveying sea scallops resource wide. The first paper presents a methodology to evaluate candidate sampling designs for closed area surveys. We simulated scallop populations within a closed area based upon both empirical data and an analysis of the autocorrelation structure of the scallops in that area. From the simulated realizations of the scallop abundance and distribution, three different sampling designs at three levels of sampling were evaluated with respect to bias and accuracy of both mean abundance and variance of the sample mean. The second and third papers take advantage of the ability of commercial vessels to simultaneously tow two dredges. Based on this ability, in the second paper, we estimate the size selectivity of the currently mandated New Bedford Style sea scallop dredge. In addition to estimating the size selective characteristics of this piece of gear, we also estimate the efficiency of the dredge. Both measures are important with respect to correctly estimating the exploitable biomass of sea scallops in rotational sea scallop closed areas. The third paper again used paired data to evaluate the relative changes in the performance of the NMFS sea scallop survey dredge. We utilize a Generalized Linear Mixed Modeling (GLMM) approach to analyzing these data with the goal of characterizing any structural changes in the performance of the dredge that is used to survey both specifically scallop closed areas as well as the entire resource via the annual NMFS time series since the 1970's. The final paper broadens the scale of the utilization of industry vessels and calibrates two of these platforms to the NMFS annual sea scallop survey. We evaluated four separate vessel gear combinations relative to the R/V Albatross IV, throughout the range of the U.S. sea scallop resource and present information to either utilize these vessels to conduct the survey, or at least form a link to a future platform. The results in this dissertation demonstrate that industry vessels represent a feasible option for the collection of sea scallop stock assessment information and present both methods and current information to facilitate their use. These approaches are especially applicable for sea scallops, where the management for this species embraces the spatial characteristics of the underlying population and crafts appropriate management strategies.
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Gedamke, Todd. "Estimating Commercial Scallop Dredge Efficiency through Vessel Tracking, Catch Data, and Depletion Models." W&M ScholarWorks, 2002. https://scholarworks.wm.edu/etd/1539617795.
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Thorpe, Jonathan Francis. "The assessment of cementitious additives used for the stabilisation/solidification of dredged harbour sediments." Thesis, University of Canterbury. Department of Civil Engineering, 1996. http://hdl.handle.net/10092/2397.
Full textAbstract:
This research examined the use of cementitious additives to physically and chemically
stabilise dredged harbour sediments for use as fill or for land reclamation purposes.
Different combinations of Cement, Stabilime, Old Cement Kiln Dust (OCKD)
Diatomite and Amorphous Silica additives were used to stabilise fine dredged harbour
sediments from the Nelson and Bayswater (Auckland) marina developements. The
relative performance of these different additive combinations were measured in terms of
unconfined compressive strength (UCS), and their ability to bind metals using the TCLP
leach test. These results were then compared with those obtained using only lime or
cement as the additive.
This research showed that the two sediments behaved quite differently. This was
predominantly due to differences in their clay content and mineralogy. Ofthe different
additives, a combination of stabilime and diatomite at a ratio of 75/25 gave best strength
results for the Bayswater sediment. Nelson sediment was best stabilised using cement,
however, significant substitution of cement with OCKD was shown to be possible
without large strength losses.
Leaching of zinc, copper, lead, chromium, nickel and cadmium was measured using the
TCLP leach test. For the majority of formulations tested, levels of metals leached were
found to be less than 10% of their original total content.
A link between the final leachate pH and the percentage of each metal leached was the
most significant trend identified from the TCLP leach tests. This indicated that
precipitation as hydroxides and other similar exchangeable compounds is one of the
primary mechanisms binding these metals.
The results from this research cannot be used directly in other applications; however, the
procedures and methodologies outlined, and the conclusions that have been made,
provide a good starting point for identifying a suitable additive for a particular sediment
solidification/stabilisation application.
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Stephens, Samantha Rose. "Trace element associations in dredged canal sediments : implications for disposal of dredgings to land." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390619.
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FitzGerald, Scott T. 1974. "Use of Geographic Information Systems (GIS) to aid in siting dredged material disposal areas." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50059.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and, (S.M.)--Massachusetts Institute of Technology, Technology and Policy Program, 1998.Includes bibliographical references (leaves 60-62).
Dredging of the ports and waterways in the United States has implications for the economy and military preparedness and is hampered by a lack of disposal areas. Current dredged material disposal site selection methodologies have several limitations, such as a lack of early public involvement in the decision making process, inadequate documentation of the assumptions entering into decisions, lack of a holistic view, and inadequate consensus building among stakeholders. The use of an interactive Geographic Information System (GIS) approach to site dredged material disposal areas is seen as a way of updating and improving current site selection methodologies. There were three specific goals of this project: 1. To develop a management approach to improve the identification and selection of dredged material disposal sites; 2. To use GIS technology as a tool to facilitate the implementation and use of that approach; and 3. To evaluate the use of GIS technology and the new approach in siting dredged disposal areas. Any useful site selection methodology must acknowledge that site selection is an inherently political process based on interpretations and perceptions of the underlying science. A two part process for evaluating, ranking, and weighting data was adopted as an effective management methodology. This process allows for public involvement built upon good science and scientific interpretation of data. The development of an interactive GIS provides the tools needed to implement this methodology. The use of visual analysis, a holistic approach, and better documentation of the assumptions inherent in any decision contribute to adaptive management of disposal areas. In addition, the interactive capability of the GIS tool allows 'what if' scenarios to be examined and allows users to immediately understand the various factors affecting disposal site location and to examine the tradeoffs inherent in any siting decision. Feedback from public demonstrations of the proposed methodology confirms that this approach to siting disposal areas is an improvement over current methods. Because it aids consensus building and fosters an adaptive management approach, this methodology has the potential to site disposal areas with less time, cost, and opposition, resulting in a better selection.
by Scott T. FitzGerald.
S.M.
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Bayer, David Michael. "Choreographing Sediment." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/54029.
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In 2016 the Panama Canal expansion is set to open, allowing a new class of ships to call on east coast ports. The dredging involved in deepening navigation channels to ensure safe passage of these vessels will place an increased amount of pressure on containment facilities up and down the coast. With limited disposal space, and increasing volumes, many ports have begun to rethink the treatment of this excess material. This thesis explores the prospect of dredge material being more than engineered fill. It suggests that dredge processing can become the basis for a new form of productive recreational landscape, one that can engage the public in a conversation of the spatial and material operations that sustain our lives. It works blur and dissolve the boundaries that have been erected between working landscapes and the public realm, and seeks to create a landscape that establishes a new sense of place prepared to mark the future of the new working urban waterfront; one where industrial operations generate new ecological substrates, and where productive frameworks become recreation networks.Master of Landscape Architecture
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Dorvinen, Jared Ian. "A Method for Interpreting the In-Situ Consolidation State of Surficial Seabed Sediments using a Free-Fall Penetrometer." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73216.
Full textAbstract:
Free-fall penetrometers (FFP) are useful instruments for the rapid characterization of seabed sediments. However, the interpretation of FFP data remains largely a skilled task. In order to increase the reliability of results obtained using these instruments, in both expert and non-expert hands, it is advantageous to establish well defined and repeatable procedures for instrument use and data interpretation. The purpose of this research was therefore to develop and refine methods for the interpretation of FFP data.
Data were gathered with the FFP Nimrod during two surveys following dredging in Sydney Harbour, Nova Scotia. The challenge of interpreting the data from these two surveys in an efficient and consistent manner was the basis of this work and led to the development of new techniques for improving resolution of the mud-line, identifying areas of erosion and deposition, and qualitatively evaluating the consolidation state of cohesive marine sediments.
The method developed for improving the resolution of the mud-line simply describes a procedure of combining the data from different accelerometers with different accuracies and ranges to more clearly define the point of impact with the sea-floor. The method developed to evaluate in-situ sediment consolidation state combines theories of self-weight consolidation and ultimate bearing capacity to predict a range of potential bearing capacities for normally consolidated cohesive sediments. Finally, by combining the previous two methods a third method is proposed for locating areas of potential erosion and deposition.Master of Science
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Bhairappanavar, Shruti. "POTENTIAL USE OF DREDGED MATERIAL - CEMENT BRICKS IN THE DESIGN OF SUSTAINABLE INTEGRATED GREEN WALL." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1532967974666973.
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Panasik, Gina M. "Effects of the addition of dredged sediment to a marsh ecosystem on benthic microalgal biomass /." Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/panasikg/ginapanasik.html.
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Brigham, Russell D. "Assessing the Effects of Lake Dredged Sediments on Soil Health: Agricultural and Environmental Implications on Midwest Ohio." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1593902126203743.
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Yochum, Noelle. "Size-Selectivity of the Commercial Sea Scallop (Placopecten magellanicus) Dredge: Evaluation the Performance of the New Bedford Style Dredge Configured with 4-Inch Rings and a 10-Inch Twine Top using the SELECT Model." W&M ScholarWorks, 2006. https://scholarworks.wm.edu/etd/1539617841.
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A size-selectivity curve was constructed to characterize the performance of the New Bedford style Atlantic sea scallop (Placopecten magellanicus) dredge when it is configured to meet the requirements of Amendment #10 to the Sea Scallop Fishery Management Plan. The curve was generated using the SELECT model on catch-at-length data, obtained by simultaneously towing a New Bedford style dredge and a non-selective National Marine Fisheries Service sea scallop survey dredge from commercial scallop vessels. Data were collected during three cruises in the Northwest Atlantic between 2005 and 2006. One cruise was completed in Georges Bank (Groundfish Closed Area II) and two cruises were completed in the mid-Atlantic (both in the Elephant Trunk Closed Area). The resulting selectivity curve for all cruises combined yielded a 50% retention length of 100.1 mm, a selection range of 23.6 mm and a relative efficiency value of 0.77. A length of 100.1 mm corresponds to an age of 4.6 years in Georges Bank and 5.8 years in the mid-Atlantic and a meat-weight of approximately 16 g. This implies that entry into the fishery is being delayed, potentially increasing yield-per-recruit and the population’s total reproductive output. The resultant selectivity curve can assist fisheries managers with stock assessments, mortality calculations and with the interpretation of catch data from government and industry-based surveys. Additionally, the curve can be used to evaluate the effect of future changes to sea scallop dredge design.
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Mebust, Christine M. "Analysis of Sedimentation Characteristics of Dredge Sediment Used in Coastal Restoration and Marsh Creation Projects." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/1988.
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There is a demand to reestablish a healthy coastal ecosystem by rebuilding wetlands with river diversion or dredged sediments in coastal Louisiana. Land building projects using dredged sediments from adjacent canals and river beds, can be used to protect the coastal properties and infrastructure systems from flood and storm surges. To predict the sediment’s long term behavior, math models require input parameters based on sediment engineering properties and material characteristics. Proper characterization is critical for accurate design of coastal restoration projects. The dredge material sedimentation characteristics and their effects on the settlement rate of suspended solid particles and underlying foundation soil depend, among other factors, on the grain size distribution of the dredged material, salinity of the composite slurry, and slurry solid particles concentration. This research evaluated the effects of grain size distribution, salinity, and initial solids concentration on the sedimentation characteristics of fine grained dredged sediments in Coastal Louisiana.
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Benson, Kaitlyn Suzanne. "Assessment of Soil Quality Parameters of Long-Term Biosolids Amended Urban Soils and Dredge Blends." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492601621133386.
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Croft, Alex. "The effects of thin layer dredge material disposal on tidal marsh processes, Masonboro Island, NC /." Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/crofta/alexcroft.html.
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Pahuja, Sanjay 1970. "Capping of very weak dredged materials in confined aquatic disposal : modeling of strength and transport behavior." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/87170.
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Brown, Stephen Nicholas. "Ecology and enhancement of the flat oyster Ostrea chilensis (Philippi, 1845) in central New Zealand." Thesis, University of Canterbury. Biological Sciences, 2011. http://hdl.handle.net/10092/6203.
Full textAbstract:
Human activities are causing a global loss of plant and animal species, degrading ecosystem properties and threatening ecosystem services. One indicator of these losses is the increasing proportion of fish stocks in decline, and the Challenger oyster fishery in Tasman Bay, central New Zealand is an example of one such fishery. Anthropogenic effects from land-based activities, and towed-gear fishing have been implicated as contributors to the decline of shellfisheries and degradation of the marine ecosystem in Tasman Bay. Increased sedimentation in the bay caused by soil erosion and runoff associated with forestry, agriculture and subdivision is likely to have a range of negative effects on the benthic community. Also towed-gear fishing, dredging and trawling homogenise benthic habitat structure (reduce habitat heterogeneity) and facilitate sediment resuspension as well as causing removal and direct physical damage to benthic biota. There is an imperative to seek to mitigate these effects and look at ways to restore the benthic community including the commercial shellfish species.
In this context, my central hypothesis was that enhancement of the benthic habitat by returning waste shell to the seabed would increase oyster production for the fishery. Related to this main goal of oyster fishery enhancement, a primary objective of the study was to fill knowledge gaps relating to the biology and ecology of the oyster in Tasman Bay. The second main topic of my thesis was to investigate how this form of habitat enhancement would alter the benthic community structure, and potentially aid in restoration of the wider ecosystem in the bay. I sought to link the twin goals of fishery enhancement and ecological restoration by considering potential management measures to promote a sustainable oyster fishery and at the same time facilitate ecological restoration within Tasman Bay. The investigations focused on four main themes: temporal patterns of oyster larval abundance, spatial patterns of spatfall and larval dispersal, effects of habitat enhancement on oyster population productivity, and effects of habitat enhancement on the benthic faunal community. Laboratory and field studies were conducted between October 2004 and May 2009.
A peak period of oyster reproductive activity began in late spring and continued through summer in each year. Maximum rates of adult oysters brooding larvae were 17% in November 2004 and 2005, and 23 % in December 2006. Over the entire summer breeding period it was estimated that 55 to 78 % of adult oysters incubated larvae. A very low level of brooding activity (1 %) occurred during winter. Temporal trends in larval settlement closely tracked brooding patterns. Settlement on collectors deployed in Tasman Bay was greatest between November and January, and there were very low rates in winter. Results are useful in optimising the timing of substratum deployment in an enhancement program for the oyster fishery.
Spat settlement density was strongly related to background adult oyster density. Spat settlement on experimental arrays deployed through the water column only occurred within a narrow vertical range very close to (<1 m above) the seabed. If suitable habitat is available for settlement, oysters tend to settle within a few hours after release, but approximately half of the larvae settled in a laboratory experiment were capable of remaining viable for several days. Oyster distribution assessed at the scale of the shellfishing industry’s annual biomass survey (median distance between sample tows ~ 1 km) is adequate to broadly predict spat settlement distribution in the subsequent settlement season, and the distribution of mature oysters is a key determinant in the placement of shell for habitat enhancement to maximise spat settlement.
Deployment of waste whole scallop shell on the seabed as settlement substratum increased oyster spat density significantly. Available settlement surface on enhanced shell plots decreased by 82% in the five months after deployment, due to fouling by numerous invertebrates and sedimentation. Survival of oysters recruited to enhanced habitat was generally very low, and varied greatly among 4 experimental sites and through time. After 3+ years, survival among site/treatment combinations ranged from 0% to 0.04%. At the site where survival was greatest, the absolute density of oysters surviving to 3.41 years on enhanced habitat was estimated as 0.4 m⁻². This equated to an increase in relative density of commercial sized oysters from ~0.01 m⁻² prior to enhancement, to ~0.14 m⁻² at the end of the experiment, and demonstrated that habitat enhancement can elevate adult oyster densities to commercial levels on areas of seabed where oysters were previously below threshold densities for commercial fishing (0.02 m⁻²). Peaks in mortality occurred within experimental plots when oysters were less than one year old, and three years old. Growth modeling indicated that after 4.25 years, 98% of living oysters would attain legal size (≥ 58mm length), and 92% would attain sufficient shell depth (≥ 20 mm) to provide high grade (grade A in the industry) meat. Shell depth was a better morphometric predictor of meat weight than either shell height or shell length.
The species assemblages on the shell-enhanced habitat were distinct from those on adjacent non-enhanced seabed. Measures of taxonomic and functional richness, faunal densities, and taxonomic redundancy within functional groups all increased in enhanced habitat. Beta and gamma diversity also increased due to patchiness of the habitat created within enhanced experimental sites. Large scale habitat enhancement in Tasman Bay via the deposition of waste shell on the seabed is likely to confer benefits to ecosystem function associated with those community level effects.
To sustain an oyster fishery in Tasman Bay, an ecosystem-based approach to fishery management is recommended to facilitate restoration of benthic habitats and communities and to help maintain ecosystem function supporting all components of the benthic community, including the oyster population. Planning and implementation of a combination of specific management measures including habitat enhancement, rotational fishing, permanent exclusion of towed fishing gear from a network of protected areas, and integration of the management of the oyster, scallop, and finfish fisheries would provide the best chance for restoration and maintenance of a sustainable oyster fishery.
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Tolle, Carly. "Assessing the litter removal and invertebrate communities of soybean stem detritus grown in dredge-amended soils: a Northwest Ohio field study." Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1626984325564693.
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Mitchell, Elaine. "Implications of the nature and quality of dredged material and its beneficial placement in the coastal environment." Thesis, University of Hull, 2007. http://hydra.hull.ac.uk/resources/hull:16066.
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Dredged sediment is increasingly being used in mudflat recharge schemes and in habitat restoration/recreation to counter the effect of erosion and sea-level rise. For this reason it is necessary to determine the response of indigenous mudflat fauna to anthropogenic sediment deposition and so in 2001 a manipulative experimental laboratory study was used to assess the biological response to the alternative beneficial use of uncontaminated maintenance dredged material. The experiment assessed the response of common temperate macro-benthic organisms to the addition of increasing amounts of simulated dredged material on to the surface of mudflat cores. Between 0 cm and 20 cm of defaunated sediment was added as both high and low frequency treatments and the vertical migration of species per 1 cm or 3 cm sediment increment was determined. The experiment showed that the bivalve Macoma balthica (Linnaeus) was able to vertically migrate into the surface layers of low or high depositions of sediment treatments but the Spionid polychaete Pygospio elegans (Claparede) and nematodes were less able to reach the surface layers with increased sediment deposition. The oligochaete Tubificoides benedii (Udekem) ability to vertically migrating into larger low frequency depositions of fine-grained sediment treatment placements was less when compared to coarser sand treatments. Hence the study showed that specific errant macro-zoobenthic species vertically migrated through increasing depths of sediment overburden. This concept was investigated further in the winter of 2001 as manipulative experimental field studies at the Skeffiing mudflats along the Humber Estuary and included an investigation to assess the biological response to increased depositions of simulated dredged material at the high-shore area. The main focus of these studies was to understand the relationship between the amounts of fine-grained simulated dredged material deposition and macro-faunal re-colonization through vertical and lateral migration. Defaunated sediment treatments were added as single low frequency amounts of 27 cm and 50 cm and the ability of macro-invertebrate species to migrate to a natural position within the vertical profile of the manipulated sediment was assessed. The re-colonization of defaunated fine-grained sediment via the below surface horizontal migration of macro-fauna occurred when 27 cm of sediment was deposited and the main colonizers were M balthica, juvenile Tellinacea and T. benedii. The macro-faunal re-colonization of a 50 cm deposition of defaunated fine-grained material occurred within 6 weeks via vertical migration. The main vertical migration colonizers were M balthica, juvenile Tellinacea and T. benedii. The deposition of a single large amount of fine-grained sediment had a detrimental affect on macro-faunal nematode recolonization. Further experimental investigations concerning the impact of burial following the high-frequency depositions of simulated fine-grained dredged material on a temperate intertidal mudflat community during the spring-summer period were carried out during 2002 and 2003. Additionally, the logistics of dredged material deposition at different tidal heights was investigated. This was achieved by examining the responses of key mudflat macro-fauna to burial by manipulated water content of fine-grained sediment treatments deposited at the upper-, high- and mid-shore areas of an estuarine intertidal mudflat and determining the macro-faunal re-colonization potential via settlement from the water column. Tubificoides benedii demonstrated a high ability to colonize an increased sediment water content treatment throughout the experiment when deposited at the high- and mid-shore areas but colonized the upper-shore sediment treatment from the middle to end period of the experiment. The polychaete Hediste diversicolor (O.F. Muller), in particular the juvenile stage demonstrated a good ability to colonize the upper-shore fine-grained sediment treatment. The high-shore early treatment colonizers included T. benedii and nematodes, other species colonized the treatment microcosms from July onwards; T. benedii, H. diversicolor, the Spionid polychaete Streblospio shrubsolii (Buchanan) and the gastropod Hydrobia ulvae (pennant) and M balthica throughout the experiment. At the mid-shore the early colonizers included T. benedii, M balthica, P. elegans and S. shrubsolii. The colonization ability of M balthica, juvenile Tellinacea and H. ulvae were negatively correlated to an increase in sediment water content especially when deposited at the high-shore. Tubificoides benendii was the only species to show a sediment-associated pattern at the high-shore and was positively correlated to the sediment water content of the treatments. When simulated fine-grained dredged material was deposited as small multiple amounts over time, the mudflat height was slowly recharged and allowed to build up, this allowed the gradual macro-faunal re-colonization of the recharge material over time. In general, the deposition of manipulated water content fine-grained sediment treatments did not inhibit macro-faunal recovery. This information may be used during the decision making process upon the feasibility of the alternative beneficial uses of dredged material such as when determining the type of dredged material used during a sediment recharge scheme or during simulated dredged material deposition studies.
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Boyd, Sian Ellen. "A comparative study of the responses of microfaunal and nematode assemblages to the disposal of dredged material." Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298890.
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Oing, Katja [Verfasser], and Annette [Akademischer Betreuer] Eschenbach. "Suitability of Processed Dredged Material from the Hamburg Harbor for Dike Construction / Katja Oing ; Betreuer: Annette Eschenbach." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/1192913000/34.
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Johnson, Charley R. "Migration of Dredged Material Mounds: Predictions Based on Field Measurements of Waves, Currents, and Suspended Sediments, Brunswick, GA." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04082005-145658/unrestricted/johnson%5Fcharley%5Fr%5F200505%5Fmast.pdf.
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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2005.F. Michael Saunders, Ph.D., Committee Member ; Kevin Haas, Ph.D., Committee Member ; Paul A. Work, Ph.D., Committee Chair. Includes bibliographical references.
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Paavo, Brian Lee, and n/a. "Soft-sediment benthos of Aramoana and Blueskin Bay (Otago, New Zealand) and effects of dredge-spoil disposal." University of Otago. Department of Marine Science, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070928.161657.
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Studies were conducted to broadly describe and understand the sediment benthos of a shallow-water coastal area (Aramoana Beach - Heyward Point - Blueskin Bay) near the entrance to Otago Harbour, a system largely representative for southeastern New Zealand. Benthic assemblages were examined in relation to gradients of wave exposure and disturbance, sediment type and bathymetry, and dredge-spoil disposal.
Sediment and macrofaunal surveys in autumn and spring 2003 found little change in sediment texture gradients from historical studies and a lack of vertical stratification. Macrobenthic samples from spring produced significantly higher abundances of three numerically dominant phyla (Arthropoda, Annelida, and Mollusca) and higher taxon richness compared to autumn. Within water depths of 6-30 m, abundance, richness, and diversity increased with depth. Multivariate analyses identified similar assemblages among deeper sites, despite sediment textural differences, whereas distinct assemblages were found in the shallow portions of the three areas. Meiofaunal abundance patterns did not reflect those of macrofauna, possibly indicating greater vertical penetration of sediments in these hydrodynamic environments. Several new kinorhynch taxa were found.
In a field manipulation, part of the Aramoana dredge-spoil dumpground was protected from spoil disposal for an extended period followed by experimental dumping of sandy and muddy spoil. Macrofaunal samples were collected before dumping and at nine sites < 119 d after disposal. Water velocities at the sediment-water interface were compared to a local sediment disturbance model. Dumpground samples were depauperate in individuals and taxa compared to an area protected from dumping for > 180 d. A drop in abundance and a dissimilar community coincided with muddy spoil, but fine sediments were dispersed within 26 d and macrofaunal assemblages recovered to the pre-existing state. Sandy spoil, while not altering native sediment textures, had a more prolonged impact due to transplantation of macrofauna from the dredged area that persisted for < 41 d after disposal. Side-scan sonar mapping indicated that the disposal footprint model used approximated the extent of sandy spoil impacts well, while local conditions spread muddy sediments beyond the initial impact site.
A novel sediment profile imaging device was constructed that has many advantages over existing devices for spoil mound studies and habitat mapping: it is smaller, can be manually deployed from small boats, is cheaper, and can be modified to work in almost any soft sediment.
Studies of one dominant taxon, the gastropod Zethalia zelandica, showed it was better able to survive sand burial than mud burial, did not vary in overall activity through a range of 5-14� C, and contributed a large proportion of biomass of its community.
The spoil disposal strategy used does not appear as environmentally neutral as originally thought. Only muds are effectively dispersed whereas coarser sediments accumulate, affecting physical and biological benthic processes of a wider area. Two mitigation strategies were evaluated using a heuristic model. Reducing the disposal area and spreading mud disposal events over a longer time span may be an effective interim strategy. Overall, the studies will help guide management of the area.
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Robinson, Arabella Mary Milbank. "Love and drede : religious fear in Middle English." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/280671.
Full textAbstract:
Several earlier generations of historians described the later Middle Ages as an 'age of fear'. This account was especially applied to accounts of the presumed mentality of the later medieval layperson, seen as at the mercy of the currents of plague, violence and dramatic social, economic and political change and, above all, a religiosity characterised as primitive or even pathological. This 'great fear theory' remains influential in public perception. However, recent scholarship has done much to restitute a more positive, affective, incarnational and even soteriologically optimistic late-medieval vernacular piety. Nevertheless, perhaps due to the positive and recuperative approach of this scholarship, it did not attend to the treatment of fear in devotional and literary texts of the period. This thesis responds to this gap in current scholarship, and the continued pull of this account of later-medieval piety, by building an account of fear's place in the rich vernacular theology available in the Middle English of the fourteenth and fifteenth centuries. It takes as its starting point accounts of the role of fear in religious experience, devotion and practice within vernacular and lay contexts, as opposed to texts written by and for clerical audiences. The account of drede in Middle English strikingly integrates humbler aspects of fear into the relationship to God. The theological and indeed material circumstances of the later fourteenth century may have intensified fear's role: this thesis suggests that they also fostered an intensified engagement with the inherited tradition, generating fresh theological accounts of the place of fear. Chapter One begins with a triad of broadly pastoral texts which might be seen to disseminate a top-down agenda but which, this analysis discovers, articulate diverse ways in which the humble place of fear is elevated as part of a vernacular agenda. Here love and fear are always seen in a complex, varying dialectic or symbiosis. Chapter Two explores how this reaches a particular apex in the foundational and final place of fear in Julian of Norwich's Revelations, and is not incompatible even with her celebratedly 'optimistic' theology. Chapter Three turns to a more broadly accessed generic context, that of later medieval cycle drama, to engage in readings of Christ's Gethsemane fear in the 'Agony in the Garden' episodes. The N-Town, Chester, Towneley and York plays articulate complex and variant theological ideas about Christ's fearful affectivity as a site of imitation and participation for the medieval layperson. Chapter Four is a reading of Piers Plowman that argues a right fear is essential to Langland's espousal of a poetics of crisis and a crucial element in the questing corrective he applies to self and society. It executes new readings of key episodes in the poem, including the Prologue, Pardon, Crucifixion and the final apocalyptic passus, in the light of its theology of fear.
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Schmidt, Martin. "Assessment of the physical, chemical and leaching characteristics of a marine sediment dredge spoil at Bing Bong, Northern Territory /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09AR/09ars353.pdf.
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