What is GCL?
GCL – Geosynthetic Clay Liner is a woven fabric like material sandwich with bentonite clay in the middle. When installed correctly it behaves like a geomembrane, resulting lower permeability slowing down any seepage out of the dam. Due to bentonite clay having a very low hydraulic conductivity it makes for an effective GCL.
A typical GCL roll construction would consist of two layers of geotextile stitched together enclosing a layer of processed sodium bentonite. Approximate thickness of GCL is 6mm.
GCL is predominately used in landfills as a backup to a geomembrane layer.
Engineering wise, GCL is containment as a hydraulic barrier to water, leachate or other liquids. GCL is used as a replacement for compacted clay liners in landfill cells and capping. For best practise liner security, a three component composite of compacted clay liner/ GCL and Geomembrane can be used.
Differences Between Geosynthetic Clay Liners and Compacted Clay Liners – Table Courtesy of Wikipedia.
|Material||Bentonite clay, adhesives, geotextiles and/or geomembranes||Native soils or blends of soil and bentonite clay|
|Construction||Factory manufactured and then installed in the field||Construction and/or amended in the field|
|Thickness||~ 6 mm||300 to 900 mm|
|Permeability of clay||10−10 to 10−12 m/s||10−9 to 10−10 m/s|
|Speed and ease of construction||Rapid, simple installation||Slow, complicated construction|
|Installed cost||$0.05 to $0.10 per m2||Highly variable (estimated range $0.07 to $0.30 per m2)|
|Experience||CQC and CQA are critical||Highly workforce dependent|