Three-dimensional finite-element analyses of seepage and contaminant transport through composite geosynthetics clay liners with multiple defects

El-Zein, Abbas; McCarroll, Ingrid; Touze-Foltz, Nathalie

doi:10.1016/j.geotexmem.2012.02.004

Cited by 33 publications

(11 citation statements)

References 19 publications

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“…However, even when GCLs are able to maintain a low k upon exposure to chemical solutions, diffusion is likely to be a significant, if not dominant, mechanism of chemical transport through the GCLs due to the low k and the relative thinness of GCLs (typically 15 mm) (e.g., Shackelford, 2013a, b). As a result, a significant number of studies have focused on the transport, in general, and diffusion, in particular, of chemicals through GCLs both individually and as components of composite barriers (e.g., Lake and Rowe, 2000;Malusis and Shackelford, 2002a;El-Zein et al, 2012;Mendez et al, 2013;Shackelford, 2013a, b;Xie et al, 2013;Hosney and Rowe, 2014;Chen et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Limiting membrane and diffusion behavior of a geosynthetic clay liner

Shackelford

Meier

Sample-Lord

2016

Geotextiles and Geomembranes

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a b s t r a c tBentonite based geosynthetic clay liners (GCLs) are commonly used as chemical containment barriers to minimize liquid flow and contaminant transport. The preference for GCLs relative to other materials for chemical containment include economy of use and superior engineering properties, including low hydraulic conductivity (k) and the ability to exhibit semipermeable membrane behavior that restricts the migration of solutes through the bentonite. In the case of low k (e.g., 10 À10 m/s), diffusion is likely to be a significant, if not dominant, mechanism of chemical transport. The objective of this study was to evaluate the membrane and diffusion behavior of a GCL in the limit as the salt (KCl) concentration increased to the extent that any observed membrane behavior was destroyed. The results indicated that the observed membrane behavior for the GCL was essentially destroyed when the average KCl concentration across the GCL specimen, C ave , reached 200 mM KCl, which was greater than the value of C ave that would have been predicted on the basis of previous results. The results also indicated that the value of the effective diffusion coefficient, D * , for Cl À at this limiting value for C ave of 200 mM KCl was greater than the value of D * that would have been predicted on the basis of the use of lower values of C ave . However, the differences between the measured and predicted values of D * were relatively minor ( 11.3%), such that the differences likely would be insignificant for most practical applications.

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Section: Introductionmentioning

confidence: 99%

Limiting membrane and diffusion behavior of a geosynthetic clay liner

Shackelford

Meier

Sample-Lord

2016

Geotextiles and Geomembranes

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“…developed the onedimensional semi-analytical model for contaminant transport in the composite liners. Finite element models were developed by El-Zein (2008), El-Zein and Rowe (2008), andEl-Zein et al (2012) to assess the performance of composite liners with intact and leaking geomembranes. One of the limitations of these numerical methods is that they are not tools readily available to engineering practitioners addressing issues of landfill liner designs.…”

Section: Introductionmentioning

confidence: 99%

Steady-state analytical models for performance assessment of landfill composite liners

Xie

Jiang

Zhang

et al. 2015

Environ Sci Pollut Res

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One-dimensional mathematical models were developed for organic contaminant transport through landfill composite liners consisting of a geomembrane (GM) and a geosynthetic clay liner (GCL) or a GM and a compacted clay liner (CCL). The combined effect of leakage through GM defects, diffusion in GM and the underlying soil liners, and degradation in soil liners were considered. Steady state analytical solutions were provided for the proposed mathematical models, which consider the different combinations of advection, diffusion, and degradation. The analytical solutions of the time lag for contaminant transport in the composite liners were also derived. The performance of GM/GCL and GM/CCL was analyzed. For GM/GCL, the bottom flux can be reduced by a factor of 4 when the leachate head decreases from 10 to 0.3 m. The influence of degradation can be ignored for GM/GCL. For GM/CCL, when the leachate head decreases from 10 to 0.3 m, the bottom flux decreases by a factor of 2-4. Leachate head has greater influence on bottom flux in case of larger degradation rate (e.g., half-life = 1 year) compared to the case with lower degradation rate (e.g., half-life = 10 years). As contaminant half-life in soil liner decreases from 10 to 1 year, bottom flux decreases by approximately 2.7 magnitudes of orders. It is indicated that degradation may have greater influence on time lag of composite liner than leachate head. As leachate head increases from zero to 10 m, time lag for GM/CCL can be reduced by 5-6 years. Time lag for the same composite liner can be reduced by 10-11 years as contaminant half-life decreases from 10 to 1 year. Reducing leachate head acting on composite liners and increasing the degradation capacity of the soil liner would be the effective methods to improve the performance of the composite liners. The proposed analytical solutions are relatively simple and can be used for preliminary design and performance assessment of composite liners.

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“…GCLs have been widely used in landfill liner systems to replace the traditional compacted clay liners (CCL) because of their low price, easily controlled construction quality, and low permeability (Koerner 2005;Guyonnet et al 2009;Bouazza and Bowders 2010). GCLs are usually combined with SLs in landfills in many countries Barroso et al 2006;Xie et al 2009bXie et al , 2013El-Zein et al 2012;Guan et al 2014). The Chinese standard (CJJ113-2,007) includes a provision that permits the use of GCL composite liners, provided that a SL of a certain thickness is added beneath the GCL (MCC 2007).…”

Section: Introductionmentioning

confidence: 99%

“…The flux of the VOCs transported into the groundwater caused by the leakage through the defects of the GMs (e.g., wrinkles and holes) could be quite high, especially in the case with high leachate head. The literature works indicated that both leakage through the GM defects and diffusion through intact composite liners should be considered in the assessment of performance of landfill composite liners (El-Zein 2008;El-Zein and Rowe 2008;Du et al 2009;El-Zein et al 2012) especially in the cases with high leachate level and high frequency of holes (Xie et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Two-dimensional finite-element analyses were performed to simulate the transport of dichloromethane (DCM) through a leaking HDPE GM involving composite liners, including both compacted clay liners and geosynthetic clay liners (El-Zein and Rowe 2008). El-Zein et al (2012) developed a 3D finiteelement model to simulate transport of DCM through a typical GCL composite liner system consisting of a GM, a GCL, an attenuation layer, and a thin aquifer. The GM was either free of defects or carried one or multiple defects in their model.…”

Section: Introductionmentioning

confidence: 99%

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An analytical model for volatile organic compound transport through a composite liner consisting of a geomembrane, a GCL, and a soil liner

Xie

Jiang

Zhang

et al. 2014

Environ Sci Pollut Res

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An analytical model for volatile organic compounds (VOCs) transport through a composite liner consisting of a geomembrane (GM), a geosynthetic clay liner (GCL), and a soil liner (SL) was developed for the assessment of the performance of this triple liner system. Both advection through the defects of GM and diffusion in the intact GM were considered in the model, and dimensionless analytical solution was obtained. The soil concentration profiles obtained by the proposed analytical solution have a good agreement with those obtained by the finite-layer-based software POLLUTE v7. The effects of leachate head, length of the connected wrinkles, and the interface transmissivity of GM/GCL on the breakthrough curves of the liner system were then investigated. Results show that the 30-year base flux of the liner system for the case with leachate head = 10 m and length of the connected wrinkles = 1,000 m can be over 60 times greater than that of the pure diffusion case. The length of the connected wrinkles of the GM has greater influence on the base flux of the liner system than on the base concentration. The interface transmissivity has negligible effect on the solute breakthrough curves of the liner system for relatively low values of the length of the connected wrinkles (e.g., <100 m). The groundwater protection level achieved by GM/CCL is more effective than that by GM/GCL/SL in the earlier times. However, the steady state base flux for GM/GCL/SL can be seven to eight times lower than that for GM/CCL. The analytical solution can also be used for experimental data fitting, verification of complicated numerical models, and preliminary design of composite liners.

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Three-dimensional finite-element analyses of seepage and contaminant transport through composite geosynthetics clay liners with multiple defects

Cited by 33 publications

References 19 publications

Limiting membrane and diffusion behavior of a geosynthetic clay liner

Limiting membrane and diffusion behavior of a geosynthetic clay liner

Steady-state analytical models for performance assessment of landfill composite liners

An analytical model for volatile organic compound transport through a composite liner consisting of a geomembrane, a GCL, and a soil liner

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