The geomembrane stops most flow, and its tight contact with compacted clay or a GCL limits leakage through any hole to a small area beneath it. The pair leaks far less than either layer alone, which is why landfill rules call for composite liners. Contact is everything: wrinkles and gaps under the sheet let liquid spread and undo much of the benefit.
Composite liner is 60-mil HDPE straight on the GCL, so get the wrinkles out before the cover soil goes on.
Also heard as
- composite barrier
- composite lining system
Related terms
Geomembrane
Low-permeability polymer sheet used as a liquid or gas barrier in liners, covers, ponds and tunnels.
GCL
Geosynthetic clay liner: a factory-made barrier of sodium bentonite held between two geotextiles.
Leak detection layer
Drainage layer between the primary and secondary liners of a double liner that collects and reveals leakage.
Waves
Installer word for the wrinkles that form in a geomembrane as it expands in the sun.