Investigation of the Behavior of Geosynthetic Clay Liners Subjected to Thermal Gradients in Basal Liner Applications PDF Download
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Author: JM. Southen
Publisher:
ISBN:
Category : Desiccation
Languages : en
Pages : 13
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Book Description
Composite liners comprised of geomembranes and geosynthetic clay liners can be an effective means of minimizing fluid flow and associated groundwater contamination from municipal solid waste landfills. There remains uncertainty, however, regarding the long-term performance of such systems under conditions of elevated temperature that may occur at the base of landfills attributable to exothermic waste degradation processes. The heat generated by these processes may lead to the development of a thermal gradient through the lining system that creates a risk of desiccation within the uppermost portion of the subsoil and the geosynthetic clay liner itself. To investigate this issue, a series of small-scale laboratory experiments were developed in an effort to simulate the hydraulic and thermal conditions existing at the base of a landfill. This paper presents the results of investigations into the influence of various parameters on the behavior of a composite liner. The distribution of temperature and water content over time is discussed, as well as potential impacts on the performance of the geosynthetic clay liner.
Author: JM. Southen
Publisher:
ISBN:
Category : Desiccation
Languages : en
Pages : 13
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Book Description
Composite liners comprised of geomembranes and geosynthetic clay liners can be an effective means of minimizing fluid flow and associated groundwater contamination from municipal solid waste landfills. There remains uncertainty, however, regarding the long-term performance of such systems under conditions of elevated temperature that may occur at the base of landfills attributable to exothermic waste degradation processes. The heat generated by these processes may lead to the development of a thermal gradient through the lining system that creates a risk of desiccation within the uppermost portion of the subsoil and the geosynthetic clay liner itself. To investigate this issue, a series of small-scale laboratory experiments were developed in an effort to simulate the hydraulic and thermal conditions existing at the base of a landfill. This paper presents the results of investigations into the influence of various parameters on the behavior of a composite liner. The distribution of temperature and water content over time is discussed, as well as potential impacts on the performance of the geosynthetic clay liner.
Author: Robert E. Mackey
Publisher: ASTM International
ISBN: 0803134843
Category : Clay
Languages : en
Pages : 161
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Book Description
Soon after the inception of ASTM D35.04 Subcommittee on Geosynthetic Clay Liners, the first symposium on Testing and Acceptance Criteria for Geosynthetic Clay Liners (GCLs), STP 1308, was held on 29 January 1996, in Atlanta, Georgia. The intention of the symposium was to bring together the current knowledge and understanding regarding this relatively new product used in containment systems. Since that symposium, numerous GCL standards have been developed along with a greater appreciation of the product's capabilities and limitations. ASTM D35 determined it was time to assess the current state of GCL technology to better address possible revisions of the present ASTM GCL standards and determine what new standards will be required in the future.
Author: Bogdan Księżopolski
Publisher: CRC Press
ISBN: 1138000604
Category : Computers
Languages : en
Pages : 734
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Book Description
Introducing the Quality of Protection Modeling Language (QoP-ML), this book provides for the abstraction of security systems while maintaining emphasis on the details of quality protection . It delineates the steps used in cryptographic protocol and introduces a multilevel protocol analysis that expands current understanding. Every operation defined by QoP-ML is described within parameters of security metrics, therefore evaluating the impact of the operation on the entire system's security.
Author:
Publisher:
ISBN:
Category : Engineering
Languages : en
Pages : 404
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Book Description
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309134064
Category : Science
Languages : en
Pages : 134
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Book Description
President Carter's 1980 declaration of a state of emergency at Love Canal, New York, recognized that residents' health had been affected by nearby chemical waste sites. The Resource Conservation and Recovery Act, enacted in 1976, ushered in a new era of waste management disposal designed to protect the public from harm. It required that modern waste containment systems use "engineered" barriers designed to isolate hazardous and toxic wastes and prevent them from seeping into the environment. These containment systems are now employed at thousands of waste sites around the United States, and their effectiveness must be continually monitored. Assessment of the Performance of Engineered Waste Containment Barriers assesses the performance of waste containment barriers to date. Existing data suggest that waste containment systems with liners and covers, when constructed and maintained in accordance with current regulations, are performing well thus far. However, they have not been in existence long enough to assess long-term (postclosure) performance, which may extend for hundreds of years. The book makes recommendations on how to improve future assessments and increase confidence in predictions of barrier system performance which will be of interest to policy makers, environmental interest groups, industrial waste producers, and industrial waste management industry.
Author: Hywel R. Thomas
Publisher: Thomas Telford Publishing
ISBN:
Category : Science
Languages : en
Pages : 852
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Book Description
Author: Farzad Meysami Azad
Publisher:
ISBN:
Category : Geomembranes
Languages : en
Pages : 420
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Geosynthetic Clay Liners (or GCLs) are often used in conjunction with a geomembrane for landfills and heap-leach pads, where their function is to minimize leakage that may occur through holes in the geomembrane. GCLs are installed with overlapping panels and powdered bentonite placed between the overlaps to provide a better seal. Recent field exhumations of GCLs installed beneath a geomembrane left exposed to solar radiation have shown panel shrinkage; in some cases, this shrinkage was enough to leave exposed areas unprotected by the GCL. One hypothesized cause of this shrinkage is cyclic wetting and drying of the GCL. To investigate the hypothesis that wet/dry cycles have the potential to cause irrevocable shrinkage of GCL panels, a total of 8 different products were tested under idealised conditions in the laboratory. Shrinkage was measured using both hand measurements and digital image correlation techniques. A number of variables were tested for their effects on panel shrinkage, including mass per unit area, size and aspect ratio, restraint, moisture content and wetting conditions, and GCL type. Wet/dry cycles were found to cause sufficient shrinkage to explain the shrinkage observed in all but one field case. The shrinkage of any particular product was found to be variable. In particular the shrinkage was found to be sensitive to the distribution of the mass of bentonite within a specimen with the highest shrinkage being observed when there was the greatest variability in mass distribution. It is shown that some GCL products are more prone to shrinkage than others. Consideration is also given to the potential effectiveness of heat-tacking of GCL seams to reduce panel shrinkage in the field. Specimens of GCL which had been heat-tacked in the field were tested under similar cyclic conditions as used in the abovementioned laboratory tests, and the shrinkage response noted. The results indicate that such a technique has promise as a method of inhibiting shrinkage o.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner–subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner.
Author: Mohamed Said Hussein Hosney
Publisher:
ISBN:
Category :
Languages : en
Pages : 1730
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Book Description
The use of geosynthetic clay liners (GCLs) as (i) covers for arsenic-rich gold mine tailings and landfills, (ii) subsurface barrier for migration of hydrocarbons in the Arctic, and (iii) basal liner for sewage treatment lagoons were examined. After 4 years in field and laboratory experiments, it was found that best cover configuration above gold mine tailings might include a layer of GCL product with polymer-enhanced bentonite and a geofilm-coated carrier geotextile serving above the tailings under [greater than or equal to] 0.7 m overburden. However, acceptable performance could be achieved with using a standard GCL with untreated bentonite provided that there is a minimum of 0.7 m of cover soil above the GCL. When GCL samples were exhumed from experimental landfill test cover with complete replacement of sodium in the bentonite with divalent cations in the adjacent soil, it was observed that the (i) hydraulic head across the GCLs, (ii) size of the needle-punched bundles, and (iii) structure of the bentonite can all significantly affect the value of the inferred in-situ hydraulic conductivity measured at the laboratory. The higher the hydraulic head and the larger the size of the needle-punched bundles, the higher the likelihood of internal erosion/structural change of bentonite at bundles that will cause a preferential flow for liquids to occur. A key practical implication was that GCLs can perform effectively as a single hydraulic barrier in covers provided that the water head above the GCL kept low. The hydraulic performance of a GCL in the Arctic was most affected by the location within the soil profile relative to the typical groundwater level with the highest increase in the hydraulic conductivity (by 1-4 orders of magnitude) for GCL below the water table. However, because the head required for jet fuel to pass through the GCL was higher than that present under field conditions, there was no evidence of jet fuel leakage through the barrier system. The leakage through GCLs below concrete lined sewage treatment lagoons was within acceptable limits, in large part, due to the low interface transmissivity between GCLs and the overlying poured concrete.
