Chemo-hydro-mechanical Coupled Performance of Geosynthetic Clay Liners in the Presence of Synthetic Leachates

¹ CERIS/ Instituto Superior Técnico, Civil Engineering Department, Lisbon, Av. Rovisco Pais 01, Portugal
² Postgraduate Program in Environmental Engineering, Rio de Janeiro State University, R. São Francisco Xavier, 524, Rio de Janeiro, Brazil
³ Laboratory of Comparative and Environmental Virology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Av. Brazil, 4365, Rio de Janeiro, Brazil

^* Corresponding author: layla.aquino@tecnico.ulisboa.pt

Abstract

Worldwide, 70% of municipal solid waste (MSW) is deposited on the ground, and in low- income countries, around 90% of waste is deposited in dumpsites or burned in the open. Current estimates indicate that around 60 million people live within 10 km of the world's fifth largest dumps. The contamination of water resources by the migration of waste leachate is a relevant factor that leads to the environmental deterioration of groundwater and surface water. This study aims to evaluate the quality of Geosynthetic Clay Liners (GCL) used as a waterproofing barrier for waste disposal areas using fluids with different physical and chemical characteristics. Different solutions were investigated to evaluate chemical and pH effects on GCL sealing performance, namely acidic synthetic leachate (pH 3), basic synthetic leachate (pH 8), and distilled water (pH 6). The compressibility of GCL samples fully saturated with the different fluids was evaluated in oedometer tests, being saturated hydraulic conductivity computed during the load increment stages of this test. In addition, swelling or collapse deformations were measured for different vertical stresses. The results indicated that both compressibility and swelling capacity were affected by the chemical components of the solutions, and saturated permeability has increased slightly due to the presence of ions in the fluids, as expected. Even with different test solutions, the hydraulic conductivity remained below 10^-9 m/s, which is in the standards for impervious foundations of solid waste dumpsites.