Geosynthetic clay liners permeated with chemical solutions and leachates

Hydraulic conductivity tests were performed on five geosynthetic clay liners (GCLs) using seven permeant liquids and three conditions of hydration. The condition of hydration was found to be very important: much lower hydraulic conductivity generally resulted when the first wetting liquid was water rather than the chemical solution or leachate. The GCLs had a high hydraulic conductivity when permeated directly with: (1) simulated municipal solid waste (MSW) leachate that was rich in calcium; (2) a strong acid solution; or (3) a strong base solution. The GCLs maintained low hydraulic conductivity (1 x 10(-8) to 1 x 10(-10) cm/s) when they were permeated with (1) simulated hazardous waste (HW) leachate; (2) real MSW leachate; or (3) simulated fly ash leachate. GCLs containing contaminant-resistant bentonite maintained a lower hydraulic conductivity than GCLs that contained regular bentonite for some but not all permeant liquids.