Solute transport in partially-saturated deformable porous media: Application to a landfill clay liner

Abstract

Based on the one-dimensional Biot consolidation equations, this paper developed an advection-diffusion equation that incorporates saturation, compressibility of the pore fluid and longitudinal dispersivity of the solute transport in an unsaturated, deforming porous medium. A simplified model was proposed for the case of a landfill liner. Numerical results demonstrated that the longitudinal dispersivity and compressibility of the pore fluid can be significant. Furthermore, the degree of soil saturation and loading rate of the waste surcharge affect significantly the contamination advective emission, namely the cumulative contaminant mass outflow per unit area from compacted clay liner (CCL) due to advective flow.

An analytical model for solute transport in an infiltration tracer test in soil with a shallow groundwater table

“…For a shallow groundwater condition, we consider a low boundary located at the interface of the unsaturated soil and unconfined groundwater (groundwater table). Therefore, the following zerogradient boundary condition is used (Zhang et al, 2012(Zhang et al, , 2013:…”

Contaminant Transport in Capped Deformable Partially Saturated Sediments

“…The consolidation problem in the sediment layer caused by the overlying cap surcharge is solved by the basic equations that link the fluid velocity with excess pore pressure. The consolidation model is governed by one-dimensional unsaturated fluid storage derived by Zhang et al (2012) and the Biot consolidation equation containing the self-weight term introduced by Tsai, Chang, and Huang (2006). They are, respectively,…”

“…The absolute air pressurē p a (ML À1 T À2 ) consists of the gauge air pressure P a (ML À1 T À2 ) and the atmosphere air pressure P 0 (ML À1 T À2 ). Based on previous work (Peters and Smith, 2002), Zhang et al (2012) further developed a one-dimensional transport equation that considered the effect of the degree of sediment saturation (S r ), coefficient of fluid compressibility (b), and constant longitudinal dispersivity (a L ). In this study, the Zhang et al (2012) equation is adopted to describe the contaminant migration through deforming sediments with linear equilibrium controlled absorption, which can be characterized as…”

Forward and back diffusion through argillaceous formations

“…The low permeability of aquitards coupled with high sorption capacity confers importance to them as protective barriers keeping drinking water aquifers safe from contamination [ Bear , ; Neuzil , ; Starr et al ., ; Sudicky et al ., ] or in isolating wastes disposed in the subsurface [ Desaulniers et al ., ; Hendry et al ., ; Starr et al ., ; Sudicky et al ., ]. Recent interest has also focused on aquifer‐aquitard solute exchange related to long‐term contaminant sequestration [ Cuevas et al ., ; Mazurek et al ., ; Sudicky et al ., ; Zhang et al ., ] and aquitards acting as contaminant sources during back diffusion to aquifers [ Chapman and Parker , ; Liu and Ball , ; Parker et al ., ; Tang and Aral , , ; Yang et al ., ].…”

“…The low permeability of aquitards coupled with high sorption capacity confers importance to them as protective barriers keeping drinking water aquifers safe from contamination [Bear, 1988;Neuzil, 1986;Starr et al, 1985;Sudicky et al, 1985] or in isolating wastes disposed in the subsurface [Desaulniers et al, 1981;Hendry et al, 2015;Starr et al, 1985;Sudicky et al, 1985]. Recent interest has also focused on aquifer-aquitard solute exchange related to long-term contaminant sequestration [Cuevas et al, 2009[Cuevas et al, , 2012Mazurek et al, 2011;Sudicky et al, 1985;Zhang et al, 2012] and aquitards acting as contaminant sources during back diffusion to aquifers [Chapman and Parker, 2005;Ball, 1998, 2002;Parker et al, 2004;Aral, 1992a, 1992b;Yang et al, 2015Yang et al, , 2016. aquifers where advection is the primary process, probably due to the high cost and difficulty in obtaining profiles of ions or isotopes and extracting porewaters from aquitards [Desaulniers et al, 1981;Mazurek et al, 2011].…”