An experimental investigation into the drainage properties of coarse Loy Yang pond ash
- Authors: Stipcevich, Jack
- Date: 2018
- Type: Text , Thesis , Masters
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- Description: The Latrobe Valley mines, Victoria, Australia, are facing some major challenges as they approach the end of their mining life. Most of these challenges surround current rehabilitation practice and the ability to create safe and stable landforms for future land uses well after the mines have closed. As there has been no developed alternative use for the brown coal at this stage, stopping power generation leads to the cessation of mining. AGL Loy Yang is undertaking rehabilitation cover trials on exposed coal batters to investigate optimal cover materials that will enable safe and stable batters well beyond mine closure. A series of rehabilitation trials using coarse coal ash have been constructed by AGL to assess the performance of coarse coal ash as a ‘subsurface drainage layer’. One of the trials includes the use of a 1 metre coarse coal ash layer placed below a 1 metre thick clay cover and above a coal surface shaped to approximately 18 degrees (1V:3H). Without a drainage layer, water may percolate through the clay cover or seep through the intact brown coal, resulting in a build of pore water pressure at the coal – clay interface and increasing the potential for slope failure. The aim of this research work was to assess the spatial distribution of ash properties known to affect drainage behaviour at the field scale; to test and calibrate field-monitoring equipment that can be used to assess drainage behaviour at the field-scale; to provide recommendations for further research on the use of coal ash drainage layer; and to provide a benchmark for future testing and monitoring. Through an experimental investigation, it was shown that there no significant variation exists in the coarse fraction of Loy Yang pond ash’s physical and chemical properties. Monitoring equipment used to determine the field drainage performance of the ash included a T8 Tensiometer and EnviroPro (multi-capacitance sensor) that were calibrated and tested in the laboratory. It was determined that monitoring devices used in this study were suitable for measuring the ash’s hydraulic behaviour only once calibrations had been performed. As a result the tested field equipment were included in the design of a future monitoring program.
- Description: Masters by Research
Liquid limit and hydraulic conductivity of brown coal composites
- Authors: Stipcevich, Jack , Kim, Sungho , Xue, Jianfeng
- Date: 2016
- Type: Text , Journal article
- Relation: Environmental Geotechnics Vol. 3, no. 6 (2016), p. 364-371
- Full Text: false
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- Description: Adequate waste disposal is currently under high demand in Australia, due to a rapid growth in population. Australia’s scarcity and cost for the use of clays (most commonly used landfill liner material) have resulted in a search for alternative materials to achieve satisfactory performance in landfill design. This study explored liquid limit and hydraulic conductivity (HC) of coal composites for potential landfill liner use. Brown coal (lignite) was mixed with polyacrylamide (PAM) or sodium bentonite (Bt) to investigate liquid limits (LL), HC, and swelling behaviour. Each additive was subject to distilled water and sodium chloride solution (50 g/l) to investigate the effects of pore fluid chemistry. The addition of 2 wt% PAM resulted in approximately 82 percentage point (pp) increase in the LL of lignite with distilled water and 76 pp increase with 50 g/l sodium chloride (NaCl) solution. The HC of lignite also decreased by more than two orders of magnitude as the PAM content increased. The swell index of lignite composites increased with the addition of PAM. This exploratory study has found the unique property of brown coal and its composites that the LL, HC and swell index do not deteriorate significantly in the presence of highly concentrated electrolyte solution (50 g/l NaCl). Such distinct properties will be beneficial over currently used landfill liner materials.