Hydraulic conductivity of GCL overlap permeated with saline solutions.

Hydraulic conductivity of the overlap region of two needle-punched sodium bentonite (Na-B) geosynthetic clay liners (GCLs) permeated with CaCl solutions under confining stresses of 20, 100, 250, and 500 kPa were evaluated. One of the GCLs consisted of a uniform layer of Na-B encapsulated between a nonwoven (NW) and a woven (W) geotextile, and the other one consisted of NW geotextiles on both sides. Supplemental bentonite was placed within the overlap region. Experiments were conducted with 10, 20, and 50 mM CaCl solutions representing dilute and aggressive leachates. The results indicate that in most of the scenarios there is a possibility that the flow is not completely vertical (meaning flow passes through the overlap region horizontally). As the confining stress increased, the horizontal flow through the overlap region for GCLs reduced effectively when permeated with deionized water and 10 mM CaCl solution, whereas the reduction of horizontal flow was limited to 20 mM and 50 mM CaCl solutions.