The impact of hazardous waste leachate on performance of clay liners

Abstract

Penetration of hazardous liquids through waste containment barriers exerts contamination and considerable alterations in geotechnical properties of clay liners. In general, these changes are attributed to the variation of the dielectric constant and the chemistry of the pore fluids which cause changes in soil structure. In the present study, a series of laboratory tests were performed on natural and contaminated clay soil permeated with different hazardous liquids: ethylene glycol and toluene which are generally found in petroleum-contaminated sites, possessing intermediate and low dielectric constants. Toluene was used in its pure form and ethylene glycol was used at various percentages of 0, 20, 40 and 60% by the volume of distilled water. In addition, natural sea water was also utilized as an inorganic fluid for permeation and salinization of the clay soil. The overall test results indicated that plasticity, sedimentation time, unconfined compressive strength, swell and compressibility generally decreased with increasing organic fluid/water concentration, while a slight increase in the permeability values was observed. Pure toluene resulted in diminution of plasticity and considerable flocculation of the particles which caused the soil to become granular. Sea water also caused particle flocculation and reduction in plasticity, swell potential and unconfined compressive strength, although it was noted that compressibility properties remained unchanged compared to distilled water. Finally, the correlation between the electrical resistivity and plasticity index values suggested that the electrical resistivity measurements can be used as a detecting technique for subsurface soil and waste barrier contamination.

Lime pile techniques for the improvement of clay soils

“…The movement of ions in clay soils is attributed to the degree of saturation, magnitude of electric field, temperature difference, the amount of fines, organic content, pore ionic concentration and particle structures (Friedman, 2005;Timo, 1998). The electrical resistivity measurement has been used to study the mechanical properties of soils (Islam et al, 2012;Russell and Barker, 2010;Seladji et al, 2010;Songyu et al, 2008) and the degree of contaminations (Mosavat and Nalbantoglu, 2013;Grellier et al, 2007;Yoon and Park, 2001). The higher the amount of fines, the greater is the specific surface area which proportionally improves the surface conductance of the clay particles (Abu-hassanein et al, 1996).…”

“…The application of direct current can cause significant changes in soils structure, water content and the pore fluid chemistry (Mosavat and Nalbantoglu, 2013). In this study, an alternative current having an electrical potential of 35 V and a constant frequency of 60 Hz was utilized.…”

Effect of solid waste landfill leachate contaminants on hydraulic conductivity of landfill liners

“…Many researchers have reported that most organic chemicals will cause an increase in the hydraulic conductivity of clay soil (Moon et al 2007;Amadi 2013;Mosavat & Nalbantoglu 2013;Mortezaei & Karimpour Fard 2017;Wang et al 2019).…”

Variation of the Hydraulic Conductivity of Clayey Soils in Exposure to Organic Permeants

“…Test results indicated an increase in the permeability of the soil contaminated with different pore fluids. Toluene with a lower dielectric constant (2.4) caused more increase in the permeability of the soil [21].…”