GCLs with factory-applied bentonite below geomembrane wrinkle

Abstract

The hydraulic performance of geosynthetic clay liner (GCL) panels with a geotextile impregnated with factory-applied bentonite that are overlapped by 300 mm to form a seam is reported for when a wrinkle in an overlying geomembrane intersects the underlying GCL seam. Two GCLs with impregnated bentonite are examined. It is shown that the details of how a GCL is needle-punched can have a significant impact on the effectiveness of seams formed using bentonite impregnated in the cover geotextile. In one case, the hydraulic performance was quite good. In the second case, the impregnated bentonite was not sufficient to seal the unstressed portion of the seam. However, 400 g/m of powdered supplemental bentonite piled along the centre of the seam provided an adequate seal and decreased the flow by orders of magnitude. The results show the validity of manufacturers’ recommendations that stress be applied to the overlap or, if used in a composite liner, that the geomembrane be installed with no wrinkles. If these recommendations cannot be followed, then the reported experiments show that about 400 g/m of powdered supplemental bentonite piled along the centre of the seam resolved the issue.