An analytical solution to contaminant advection and dispersion through a GCL/AL liner system

Abstract

An one-dimensional model for contaminant advection and dispersion through a GCL/AL liner system was developed to analyze the equivalence between a GCL (geosynthetic clay liner) and a CCL (compacted clay liner). The continuity of contaminant concentration and flux at the interface between the GCL and the underlying attenuation liner (AL) are obeyed in the model, and background concentrations in the soil liner are also considered. Based on the assumption that contaminant transport through a GCL was a steady state process, an analytical solution was obtained. Increasing the leachate head from 0.3 m to 10 m results in a reduction of the breakthrough time of benzene by a factor of 2.7. The breakthrough time of benzene increases by a factor of 7.0 when the hydraulic conductivity of GCL decreases by one order of magnitude. The breakthrough curves are more sensitive to the hydraulic conductivities of the GCL and AL (attenuation layer) than to the thickness of the AL. The standard 75 cm CCL can be replaced by a combination of a GCL and a 1.0-4.0 m thickness of AL. The proposed method can be used for preliminary design of GCL composite liners, assessing the equivalence between GCL and CCL, preliminary design of a remediation method for contaminated soils, and evaluating experimental results.

An analytical solution for one-dimensional contaminant transport in a double-layered contaminated soil with imperfect diffusion boundaries

“…For the convenience of the following analysis, the average degree of diffusion D a is defined as the ratio of the average concentration diffused to the adjacent layer to its initial concentration as [7]. (22) in which (23) where D di (i = 1, 2) is the average degree of diffusion of contaminant in the ith contaminated soil layer; D a is the average degree of diffusion, which describes the overall degree of diffusion of contaminants in the contaminated soil layers.…”

“…Although the diffusion problem in engineering practice can be analyzed by the numerical simulation schemes [19,20], analytical methods can provide a deep understanding for the essence of the related problem. In addition, the derived analytical solutions are simple, economical and effective, and they can also be used to validate the complex numerical simulation schemes in which it is difficult to accurately determine the valid parameters [21][22][23]. For instance, for the preliminary design of a landfill site, most of the valid parameters are difficult to obtain directly, but the analytical solutions can lead to a smooth design [24][25][26][27].…”

Breakthrough time-based design of landfill composite liners

“…(5). The interface boundary conditions between GCL and SL can be expressed as follows (Rowe and Badv, 1996;Peters and Smith, 2001;Xie et al, 2011a):…”

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

“…The continuous conditions between GM, GCL, and SL can be expressed as (Peters and Smith 2001; Xie et al 2011;Guan et al 2014)…”

“…Analytical solutions are also the basic tools to fit the experimental data and preliminary design of composite liner. The analytical solutions for onedimensional solute advection and dispersion in two-layered media are available (Li and Cleall 2011;Xie et al 2011;Guan et al 2014). To the authors' knowledge, the analytical solutions for volatile organic compounds transport through the composite liners consisting of a GM, a GCL, and a soil liner considering the combined effects of leakage and diffusion are not available in the literature.…”