Impregnation of GCLs

Q: We are confused with the term “impregnation” as it relates to seaming geosynthetic clay liners (GCLs). There are two types of impregnations: (1) Edge impregnation, and (2) complete nonwoven (cap layer) impregnation of GCLs. How does a manufacturer do this?

A: The edge impregnation of GCLs (1) is done in the field by an installer with a bentonite paste or powder for sealing the longitudinal or butt-seamed edges. The supplemental bentonite would need to be placed continuously along the edges at a width of 5.9 to 7.9 inches (150 to 200 mm). The complete nonwoven (cap layer) impregnation situation (2) is typically accomplished with a polymer spread coating applied in the factory.