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

With the ever increasing need for MSE walls, the study of the interaction between soil and geosynthetics has become increasingly relevant. New concepts are constantly being researched, including the use of industrial byproducts as alternative backfill materials. The idea that byproduct material could somehow be a suitable fill for these MSE walls may spark new opportunities. One such byproduct being researched is dredged material. The suitability of dredged material as a backfill would not only contribute to lower construction costs, but would also benefit local confined disposal facilities looking to reduce their already overflowing dredged material accumulation. This thesis further considers the use of dredged material by evaluating its interface shear strength with uniaxial geogrids. A series of laboratory pullout tests were conducted using two types of uniaxial geogrids (UX1400 and UX1700) embedded in three different soil types (Monterey Sand and two different dredged materials). The laboratory results are used to examine the effect on the coefficient of interaction of the various parameters governing the pullout resistance. The results of this study show that: (1) the presence of adhesion to characterize the soil-reinforcement interface shear strength causes a decrease in the coefficient of interaction with increasing normal stress, (2) the reinforcement length of the geogrid was found not to affect the coefficient of interaction; provided that boundary effects are minimized, (3) the dredged material, tested wet of optimum, showed a response consistent with an undrained behavior, which produced pullout resistances significantly lower than that of the Monterey Sand, (4) the coefficient of interaction for the UX1700 was comparatively higher than that for the UX1400; however the differences obtained when testing Monterey Sand were similar to those obtained when testing the dredged materials. / text

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.

Increasing quantities of dredged material (DM) from navigation waterways have led to a growing need to find alternative methods of disposal. Using this material in earthwork construction is a very attractive avenue, but poses concern of quality from a geotechnical standpoint. By blending DM with granular materials like industrial steel slag fines (SSF), studies have showed that the geotechnical properties of the mixture are greatly enhanced. If these materials can be proven to be competitive for use in earthwork construction, they would pose as an economically viable alternative, and would obviate the need for the relatively expensive conventional granular backfill. The scope of this project entailed the characterization of pullout interaction of SSF-DM blends in different proportions with Tensar uniaxial geogrids to determine an optimal combination for usage in earthwork construction. The media used for testing included the individual SSF and DM materials, and the 80/20, 50/50 and 20/80 blends mixed based on dry unit weights of the individual components. The SSF media comprised of particles smaller than 3/8 in. and classified as SW, while the DM was classified OH soil. Two Tensar uniaxial geogrids UX1400 and UX1700 were undertaken for the study. Pullout tests were conducted and performances of all the blends are compared with each geogrid at various normal pressures. Pullout loads and interaction coefficients give an idea of the quality of the interaction, and are studied in this thesis. Also, various variables that could potentially affect the pullout interaction are identified and investigated. Results show remarkably high pullout resistances for the 100% SSF and 80/20 SSF/DM media, and high interaction coefficients indicating excellent pullout interaction, even better than conventional sands. It was also clear that the dredged material exhibits very poor pullout interaction with geogrids. The 50/50 and the 20/80 SSF/DM media were significantly lower than the 80/20 SSF/DM blend in terms of quality of pullout interaction, but still higher than the 100% DM. The results observed with the 80/20 SSF/DM blend show that it is a suitable backfill material and also poses to be a very competitive and cost-effective alternative to be used in earthwork construction. / text

Being able to identify blended dredged material and crushed glass of different proportions as materials suitable for Mechanically Stabilized Earth walls could help the adoption of these materials in civil engineering thereby reducing the environmental impact of these waste materials. The objectives of this thesis include the following: Collect and organize data to facilitate material selection based on interaction properties with uniaxial geogrids; analyze the data for trends for varying percentages of crushed glass vs. dredged materials; compare the properties of different blends with those of a well-documented uniform sand; compare the pullout data with that of previous studies related to the presence of fines in the fill material; and compare the pullout data to that of previous studies on the effect of geogrid rib thickness. The main findings of this thesis study include the following: A blend of 80% crushed glass and 20% dredged material is a legitimate alternative backfill material for reinforced soil slopes. The use of 100% crushed glass as a fill material is not recommended due to glass particles embedding into the geogrid thereby reducing the tensile capacity of the geogrid. Blends with lower percentages of crushed glass and higher percentages of dredged material may be appropriate based on the requirements of individual designs. The increased thickness of the UX1700 geogrid over the UX1400 geogrid contributed to higher a pullout resistance for each combination of fill material and normal stress. / text

No description available.

Vid utvidgning av befintliga hamnar kan den relativt nya metoden stabiliserade/solidifierade (S/S) förorenade muddermassor användas i anslutning till spont. S/S metoden används för att binda föroreningarna fysikaliskt eller stänga in dem samt för att förbättra massornas hållfasthets- och deformationsegenskaper. Istället för att deponera dessa, ofta förorenade, muddermassor till ett högt pris kan det återanvändas i hamnkonstruktionen som ett byggmaterial. Det finns få rapporter som behandlar stabiliserade massor i anslutning till spont och hur de samverkar, vilket gör att det inte finns tydliga riktlinjer för hur metoden ska användas. Dessutom finns det stora osäkerheter kring hur utvecklingen av den odränerade skjuvhållfastheten ökar över tid och hur den kan tas hänsyn till vid projekteringen och därför kan metoden inte utnyttjas på ett effektivt sätt. Den odränerade skjuvhållfastheten utvärderas som halva tryckhållfastheten. Syftet med studien är att kunna prognostisera hur jordtrycket mot en spont beror på de S/S -behandlade muddermassornas egenskaper. Vidare har en projekteringsmetodik till S/S massor i anslutning till spont föreslagits. För att svara på detta har en litteraturstudie gjorts för att samla bakgrundsinformation och skapa en djupare förståelse för ämnet. Därefter gjordes en parameterstudie i FEM-programmet PLAXIS. Resultatet från parameterstudien kunde sedan jämföras med tidigare fält- och laboratorieförsök där egenskapernas förändringar över tid har studerats. Med detta som bakgrund kunde en projekteringsmetodik föreslås. Muddermassorna kan initialt liknas vid en vätska som orsakar ett hydrostatiskt tryck mot sponten. Med tiden kommer massorna härda och därigenom ökar hållfastheten, detta gör så att det horisontella jordtrycket minskar samtidigt som en vertikal pålastning sker vilket ökar det horisontella jordtrycket. Från litteraturstudien kunde det även ses att muddermassornas slutgiltiga hållfasthet och tillväxt beror på bindemedelsmängd och kombination som i sin tur måste anpassas efter muddermassornas vattenkvot och organisk halt. Från parameterstudien kan slutsatsen dras att en av faktorerna som har en större påverkan är hur hög skjuvhållfastheten är efter första härdningen när alla muddermassor har pumpats på plats samt förhållandet mellan skjuvhållfastheten och elasticitetsmodulen och hur de utvecklas. I den föreslagna projekteringsmetoden rekommenderas att dräneringstyp odränerad A och materialmodell Mohr-Coulomb ska användas vid simuleringar. Då det finns så stora osäkerheter kring S/S muddermassor anses materialmodell Mohr-Coulomb vara fullt tillräcklig jämfört med andra mer avancerade modeller då det finns stora osäkerheter kring indatan. Dräneringstyp odränerad A är den mer avancerade dräneringstypen av de tre och tar hänsyn till fler parametrar. Eftersom det kommer ske en utveckling av friktionsvinkel kommer modellen ge en bättre representation. / When expanding existing ports, the relatively new method ofvstabilized/solidified (S/S) contaminated dredged material can be used in connection with a sheet pile wall. The S/S method is used to physically bind the contaminants or trap them and to improve the strength and deformation properties of the masses. Instead of depositing these, often polluted, dredged materials at a high price, it can be reused in the port construction as a buildingmaterial. There are few reports that deal with stabilized masses in connection with a sheet pile wall and how they interact, which means that there are no clear guidelines for how the method should be used. In addition, there are great uncertainties about how the development of the undrained shear strength increases over time and how it can be taken into account in the design and therefore the method cannot be used in an efficient manner. The undrained shear strength is evaluated as half of the compressive strength. The purpose of the study is to be able to forecast how the earth pressure against a sheet pile wall depends on the properties of the S/S-treated dredged material. Furthermore, a design methodology for S/S material in connection with sheet pile wall has been proposed. To answer this, a literature study has been done to gather background information and create a deeper understanding of the subject. A parameter study was also done in the FEM-program PLAXIS. The results from the parameter study could then be compared with previous field and laboratory experiments where the changes in properties over time have been studied. With this as a background, a design methodology could be proposed. The dredged masses can initially be likened to a liquid which causes a hydrostatic pressure against the sheet pile wall. Over time, the masses will harden and thereby increase the shear strength, this means that the horizontal earth pressure decreases at the same time as a vertical loading takes place, which increases the horizontal earth pressure. From the literature study, it could also be seen that the final shear strength and growth of the dredged material depends on the amount of binder and combination, which in turn must be adapted to the water content and the organic content. From the parameter study, it can be concluded that one of the factors that has a greater impact is how high the shear strength is after the first hardening when all dredged materials have been pumped in place and the relationship between the shear strength and modulus of elasticity and the development. In the proposed design method, it is recommended that drainage type undrained A and material model Mohr-Coulomb should be used in simulations. As there are such large uncertainties regarding S/S dredged materials, the Mohr-Coulomb material model is considered to be fully sufficient compared with other more advanced models as there are large uncertainties regarding the input data. Drainage type undrained A is the more advanced drainage type of the three tested and takes the materials friction angle into account. Which will give a better representation.