Effect of Municipal Solid Waste Leachate on Hydraulic Conductivity and Exchange Complex of Geosynthetic Clay Liners

AbstractTests were conducted to assess how permeation with synthetic and real municipal solid waste (MSW) leachate affects the hydraulic conductivity and exchange complex of geosynthetic clay liners (GCLs). GCLs were arranged in a composite barrier configuration for hydration on moist compacted subgrades for 30 or 90 days. After hydration, the geomembrane and subgrade soil were removed and the GCLs were permeated with typical and strong synthetic and real MSW leachates at different confining stresses for 342 to 1,281 days (4.9 to 148.9 pore volumes of flow). For most tests, hydraulic and chemical termination criteria were met (referred to as equilibrium), and in many cases the tests were conducted long after these criteria were achieved. Hydraulic conductivity of the GCLs increased no more than 5.6 times the hydraulic conductivity to deionized water (DIW), even though more than 80% of the sodium (Na) in the bentonite was replaced by other cations [predominantly calcium (Ca) and magnesium (Mg)]. Very long ...