Geomembranes are impermeable and flexible sheets of material designed to secure, stabilize, or seal exposed earth. They can contain a woven or spun fabric component or consist solely of polymers. Other membranes are available for similar purposes but don’t qualify as geomembranes because they can’t be installed directly in contact with the earth. If a material truly qualifies as a geomembrane, it can be the final underlayment or liner layer under other materials. The methods used for manufacturing these materials can include calendaring, spread coating, and sheet extrusion. Other features common to most geomembranes, such as flexibility, UV resistance, reinforcement grids, exact polymer content, and plant and fish safety all vary greatly between products. This is a broad category that encompasses many different products with hundreds of potential uses across dozens of industries.
Common Uses of Geomembranes
There are hundreds of uses for geomembranes, but some of the most common and critical applications include:
- Lining irrigation ponds, canals, dams, reservoirs, and channels to prevent lost moisture and fertilizer runoff from soaking into the water through the soil.
- Sealing landfills from the bottom up so that leachate formed by rainwater running through the waste won’t soak into the surrounding environment and ground water supplies.
- Capping landfills when they close and are covered in soil. Geomembranes are impermeable enough to serve as the vapor barrier that directs methane gas produced by decomposition to the appropriate vents.
- Serving as a secondary or primary fluid barrier in a spill containment pad or pull-through loading area.
- Building affordable food processing pits for bulk fermentation, brining, or aging without the need to order dozens or even hundreds of custom fabricated metal or fiberglass tanks.
- Creating a barrier against contamination underneath areas with high risks of spills, such as gas stations, processing facilities, and pumping stations.
- Covering contaminated soil until it can be removed or encapsulated in a completely sealed geomembrane system.
- Containing and covering hazardous liquids like fracking fluids, wastewater, manure, industrial sludge and other materials during processing.
- Protecting potable drinking water supplies from contaminants leaching in through concrete or soil, in addition to covering the surface to keep algae and bacteria out.
- Extending the lifespan of road surfaces by acting as an intermediary layer between gravel and asphalt layers in a roadbed, reducing spreading that leads to cracks and ruts in the surface.
Flexible vs Non-Flexible Materials
The various materials sold as geomembranes are easily divided into a number of categories based on their primary features. Flexibility is one of the most important characteristics of the material. It determines how well it will fit unusually shaped areas and how prone it is to cracks and tears. Highly strain resistant geomembranes are considered flexible. Non-flexible products have a semi-crystalline structure and are typically more rigid.
Reinforced vs Unreinforced Geomembranes
Geomembranes are further divided into reinforced and unreinforced categories. It’s easy to assume that reinforced materials are always better, but some applications specifically call for a geomembrane without additional reinforcement. Reinforced varieties, such as BTL Liner’s ArmorPro geomembrane, feature coatings with a molecular bond and multiple layers of laminated material to increase the flexibility, corrosion resistance, and puncture resistance of the material. There’s usually a layer of scrim material worked into the polymer to act as a fibrous base. Unreinforced membranes are extruded or calendared directly out of polymer alone with no base of fabric. The thickest materials are made this way, with the maximum thickness of 200 mil possible. These materials are generally preferred over reinforced materials when permanence in a buried application is essential, such as the long-term storage site for hazardous materials like mining and nuclear wastes. In most other cases, a reinforced geomembrane like BTL’s ArmorPro is the best choice.
Buried vs Exposed Materials
Finally, not all geomembranes can handle direct and daily exposure to the sun’s damaging UV rays. On the other hand, other materials degrade rapidly if buried or covered in gravel instead. Ensure that the product you choose for your specific product is designed for exposure or complete burial before using it in either way.
