The key phases of a successful geomembrane installation are:
- Design
- Site preparation
- Deployment
- Welding
Design
The major design considerations for geomembranes are:
- The thickness of the geomembrane required to prevent tensile failure
- The thickness of protective layers to protect the geomembrane against puncture
- The load over the geomembrane
- The friction angle of the various layers to provide slope stability.
Subgrade Preparation
The subgrade to be lined should be smooth and free of all rocks and stones greater than 12 mm diameter, sticks and sharp objects. The surface should provide a smooth, flat, firm, unyielding foundation for the membrane.
Deployment
Installation of a geomembrane can result in scratching or scoring which can affect the geomembrane’s ability to stretch or conform. The method used to unroll and deploy the panels shall not score, scratch or crimp the geomembrane.
Welding
Welding of polyolefin geomembranes is mainly effected with hot-air or hot-wedge equipment, by specialized personnel. Joints and repairs are made with extrusion fillet welding equipment.
Hot wedge welding is a thermal technique where the two opposing geomembrane surfaces to be welded are melted by passing a hot metal wedge between them. In hot air welding high-temperature air is introduced between the two geomembrane surfaces to achieve surface melting. In both cases pressure is simultaneously applied to the top and bottom geomembranes, forcing together the two surfaces, to form a continuous bond. The extrusion fillet welding method involves extruding a ribbon of molten resin at the edge of overlapped geomembranes to form a continuous bond.
The quality of geomembrane welds (or seams) is significantly affected by welding temperature, welding speed, welding pressure and on-site conditions (particularly the ambient temperature). These parameters have a major influence on the long-term behavior of the geomembrane welds. Proper welding of geomembrane liners should not cause a reduction in the tensile strength across the weld as the welded sheets are expected to perform as a single geomembrane sheet.
Detailed information on installation of geomembranes can be found at our Installation Manual.