A Novel Multiple-liner Design For Preventing Desiccation Of Geosynthetic Clay Liners

Geosynthetic clay liners (GCLs) covered by geomembranes (GMB) often constitute a major component in barrier systems. They are used in waste containments systems such as landfills, brine ponds and solar ponds. In many of these cases, high temperatures can develop as a result of exothermic biodegradation or direct solar radiation and can cause significant desiccation of the bentonite in the GCLs. In addition, the self-healing ability of bentonite may be compromised by exposure to chemically aggressive permeants that are commonly found in such applications.

A new multiple-liner design is proposed in this paper, with two GMB-GCL composite liners sandwiching one layer of geocomposite (GC). The new design is able to actively hydrate top and bottom GCLs through the middle GC layer with clean water. A set of column model experiments simulating a typical bottom profile under a brine pond were conducted to investigate GCL hydration before and after continuous heating at 78±1oC for 14 days. The results were compared to the more conventional GCL-GMB designs. The findings revealed that the new multiple-liner system speeds up hydration of bentonite in the GCL by a factor of more than 3, increase its water content at the end of the hydration stage by up to 50%, and prevent its desiccation when exposed to high temperatures.