Introduction
Putting a geomembrane liner into a hole entails more than just throwing a sheet on the ground. In a proper construction project—landfill, aquaculture pond, mining containments—the manner of installation has huge ramifications for performance, service life, and risk of leakage.
A good geomembrane can be “killed” very early by careless or uncontrolled installation, while even a mediocre HDPE, or LLDPE geomembrane can “last for decades of service with minimal problems.”
This guide is strictly concerned with practicalities of site installation. Nothing too heavy in terms of the ‘why’—more focused on what is important when your project demands you to “get your hands dirty.”
Key Consideration
Geomembrane acceptance and installation is a matter of procedure that, by and large, should be followed. Skipping items, or cutting corners somewhere, will lead to installation problems later on.
Subgrade Preparation
Your subgrade must not only be smooth and compact, but also free of anything that can stab. Either stones, or tree roots, or miscellaneous rubbish that can penetrate the liner is the prime cause of punctures. A good subgrade preparation helps eliminate hard spots, and contributes to longer life for the liner itself.
Material Inspection
Prior to deployment of geomembrane rolls, inspect for visible damage, regularity of thickness, and so on. Reject any roll not in accordance with the specification (ASTM, etc).
Panel Layout Planning
Site (i.e., project site, wind, and other ambient conditions) will dictate the direction in which you lay out the panels. Usually, they are laid up and down on slopes, with the rationale being the minimization of tension. Generally speaking, try to reduce the number of seams otherwise, unless you had a fancy reason, of course.
Seaming (Welding)
Thermal welding methods including hot wedge or extrusion are generally used for HDPE geomembranes, with key controls being, temperature, pressure and speed. Trial welds should be tested prior to commencing production welding.
6. Seam Testing
Non-destructive tests, usually of seam integrity by air pressure testing or vacuum box testing, is carried out as a second step; many failures are found to have originated at seams.
7. Anchorage
The edges are secured to anchor trenches in order to prevent movement from the action of wind or load. Proper anchoring is often neglected but is of great importance if stability is to be maintained in the long term.
8. Protection Layer (if applicable)
In some instances, geotextiles or soil cover can be placed above the geomembrane to prevent it from exposure to UV rays or mechanical loads.
Applications / Use Cases
Method of application of geomembranes are similar in concept across both industries but details of execution vary from one to the other.
Landfill Liners
In a landfill liner, the requirement for installation control is most rigid, with provision for a double-liner system provided with effective leak detection. Seaming must be of high quality.
Aquaculture Pond Liners
Water retention and UV resistance come uppermost in this type of installation, and the eliminating of unintentional wrinkles that might trap waste is an object of care.
Mining Projects
Use of geomembranes in heap leach pads and tailing ponds is always accompanied by consideration of the minimum slopes to be employed, and chemical resistance.
Water Reservoirs and Dams
The action of wind is countered in the design, while the large surface areas necessitate a planned layout of panels and anchoring systems.
Biogas Digesters
In such devices the geomembrane lends itself both to acting as a liner, and provides the roof. Its gassed tightness and durability are of interest.
Comparison or Benefits
Compared to clay liners or concrete channels, the advantages are compelling.
High Impermeability
Provides essentially no permeability, and outperforms compacted clay.
Faster Installation
The large panels make installation quicker than laying down a layered system.
Cheap
Reducing material and labor expenses, and especially on big projects works out cheaper to install than any other type.
Flexibility
This moves with the ground settling, and will not crack.
Chemical Resistance
Perfect for landfill and mining site use.
If the installation is done properly the geomembranes will perform hard over long periods of time.
How to Choose / Buy
How you will be using the geomembrane and how it is to be installed will influence your choice.
Material
If you require a highly durable geomembrane then HDPE is your best bet. For slightly rocky ground use LLDPE which has a bit more give in it, and may be the better choice in those situations.
Thickness
Are their technically 0.5 mm to 2.5 mm, and the thicker the liner, the better it resists puncturing but is more expensive.
Surface Type
Smooth geomembranes are the norm. Textured geomembranes tackle the slopes a little more firmly.
Standards & Certification
Manufacturers who meet with ASTM standards and certification ensure a quality product.
Supplier support
When buying the geomembrane your supplier should help you with ‘how to’ questions as a minimum, so far as welding and pressure testing. It is only a sales pitch otherwise.
Buying geomembrane is not as simple as simply multiplying the length by the breadth price per square meter is perhaps the most misleading factor, the most critical is where you install the geomomembranes used if incorrectly they will fail.
FAQ
What is geomembrane?
Simply put a manmade material used to line a trench which controls any fluids or gases migrating through it in Engineering projects.
How does it work?
Forms a continuous watertight barrier, preventing liquid, preventing liquids or gases passing; protecting the soil and especially the groundwater.
Cost or lifespan?
Different thickness costs vary considerably, thickness and ‘footplate’age increase and dependant on ground, size of project/depths with geosynthetics and meroughly , having high-density ie. HDPE geomembrane will enjoy 20 to perhaps 30 years service.
Best option?
None, except on a case by case basis! HDPE for disposal area sites hard above ground, whereas in other project types, perhaps LLDPE, more suited?
Common issues?
Puncturing from being ruptured in unknown holes
Weak stitching/seaming as done wrongly
Wrinkling
A lack of anchoring in lots departments of project area.