A Guide to Geomembrane Installation [+Examples]
Geomembranes: What are they and what is it used for?
A geomembrane is a geosynthetic, flexible and impermeable barrier with a thickness of at least 0.50 mm that serves mainly for the containment of fluids or solids in a construction project.
Geomembranes are manufactured from thermoplastic or thermosetting polymer materials, this allows the creation of a barrier with very low permeability that prevents the escape of harmful contaminants or substances into the surrounding environment.
Despite how simple it may seem, these sheets have endless applications ranging from the construction of roads, reservoirs, boat protection to the storage of waste and/or chemical substances.
Geomembranes, along with geotextiles, are the most widely used geosynthetic products in the world.
Geomembranes function and applications
Geomembranes are very versatile and resistant materials that are used in many industries. Some of its most frequent uses are:
- Fluid handling.
- Industrial facilities.
- Civil construction.
- Mining operations.
- Waste confinement.
- Agriculture and fish farming.
Fluid handling
Water storage is usually the most common use of geomembrane installations. These membranes can prevent the presence of contaminants or sediments from the ground, as well as water filtration. In some installations, additional sheets are used on the surface -as a protective floating cover- to guarantee maximum water tightness or waterproofing.
Thanks to their impermeable characteristics, in addition to the creation of reservoirs or cisterns, geomembranes allow the transport of water through lined channels, spillways and prefabricated pipes.
However, water is not the only fluid where this material can be used. Due to their physical, chemical and mechanical properties, geomembranes can also be used as a secondary containment system in fuel stations to provide additional protection against leaks.
Civil construction
Structural moisture represents a major challenge on construction sites. Beyond the humidity caused by precipitation, many structures such as tunnels, basements and pavements are more prone to be affected by soil moisture.
Geomembranes, together with other geosynthetics, function as an effective barrier against soil permeability. They ensure good structural properties of buildings by protecting them from groundwater and dangerous gasses such as radon.
Other purposes these sheets have in the civil sector are:
- The protection of slopes and walls, since it reduces the detachment of rocks or erosion.
- Recreational architecture, it can be used in the construction of artificial lagoons, swimming pools and golf courses.
- Conventional structures, they are used as anti-leak protection layers on roofs.
- Industrial mat, for the protection of the floor against the leakage of liquids from the equipment or the loss of material.
Industrial facilities
The installation of geomembranes has been growing rapidly in the oil industry. Geotextile and geomembrane bases protect the soil surface in the drilling, completion and hydrocarbon production phases.
Geomembrane liners are used as an additional containment system in hydraulic fracturing operations. In the event of a well fracturing, this geosynthetic can be used for the construction of buried and above ground reservoirs to help with the recovery of fluids.
As if that was not enough, the use of this material has taken on a major role in cleaning up oil spills by allowing the construction of highly impermeable artificial lagoons for the storage of spilled crude oil.
- Mining operations
Mining activities are likely to expose the environment and soil to harmful chemicals. For this reason, geomembranes are frequently used in leaching operations, a technique for extracting minerals through chemical solutions such as cyanide or sulfuric acid.
In other areas, geomembranes reduce soil contamination and protect water resources by allowing the creation of dikes to contain mining waste and tailings deposits (mineral residues).
In addition, economic changes cause sudden changes in the metals market (gold, iron, copper, etc.), this affects the activities in the mines. During a price decline, a mine could be closed in order to cut costs. When the demand for the mineral grows, its value will increase, therefore, the mine becomes attractive again and its operations are reactivated.
To guarantee the activation of a mine, geomembranes, together with other geosynthetics, can efficiently isolate the contaminated soil, prevent the infiltration of substances and allow the assembly of clean land for the reestablishment of vegetation.
Waste confinement
Geomembranes have many advantages in landfill design. They are an economical and efficient solution for waste containment, significantly reducing the environmental impact of waste.
According to a study on garbage production by the World Bank (WB), a person produces an average of one kilogram of garbage per day, this represents 231 million tons of waste per year. This figure shows the importance of having adequate solutions that facilitate the construction of containers with the least possible impact.
Dumps (also called landfills) are a frequent solution in some regions of the world, however, their design is more likely to contaminate the soil, affecting groundwater courses and surrounding vegetation.
On the other hand, sanitary landfills have multiple mechanisms that guarantee soil protection, such as the high impermeability layers of geomembranes. In addition, these sheets make it possible to create a safe final cover that prevents toxic gasses from escaping into the atmosphere.
Agriculture and fish farming
Geomembranes are also widely used in the design of hydroponic crops. Its low permeability and resistance to sunlight favors water saving. Generally, the use of these materials can minimize the danger of chemical leaching in plants.
Fish farming with geomembranes has competitive characteristics compared to conventional methods, since it is not a danger to the health of the fish and it is also a more profitable alternative.
According to an article on fish farming systems geomembrane ponds in optimal conditions can house more fish, almost 100 kilos per cubic meter, while traditional techniques only allow 5 kilos per square meter.
Types of geomembranes
Geomembranes are manufactured in different thicknesses and from various polymers. These characteristics give the material a higher degree of impermeability, chemical resistance, puncture resistance, among other useful properties for a given application.
The most common types of geomembranes are:
- PVC geomembrane (Polyvinyl chloride).
- HDPE geomembrane (High Density Polyethylene).
- LDPE geomembrane (Linear Low Density Polyethylene).
- EPDM Geomembrane (Ethylene Propylene Diene Terpolymer).
- FPP geomembrane (Flexible Polypropylene).
- RPP geomembrane (reinforced polypropylene).
What is PVC geomembrane?
It is a polyvinyl chloride (PVC) sheet that stands out for being light, resistant, very flexible and economical. The PVC geomembrane is the most common waterproofing method that exists.
Its high versatility allows it to have many functions such as the lining of tunnels and steep slopes, soil remediation, landfill design, among other applications.
What is HDPE geomembrane?
It is a high-density polyethylene (HDPE) coating that has great durability, low permeability, high resistance to deformation, chemicals, UV rays and temperature.
Due to these characteristics and its low cost, HDPE sheets are widely used in an infinity of applications ranging from the construction of water tanks to the containment of chemical substances.
How is a geomembrane installed?
In the process of installing a geomembrane, several aspects must be taken into account, such as: the type of material selected (PVC, HDPE, LDPE, etc.), the area of application, the fluids or solids involved, as well as the environmental conditions and the equipment to be used.
Below we present an assembly guide that corresponds to the installation process of PVC geomembranes for the protection of slopes for water storage:
- Step 1: Clean the area
Before laying the lining, the surface must be inspected. Make sure there are no sharp rocks, roots or any other type of objects that can damage the HDPE sheets and prevent uniform deployment.
The use of geotextiles as support covers is very useful to counteract irregularities in the ground, it also reduces the appearance of whale backs or air bubbles produced by gasses trapped during installation.
- Step 2: Unfold the lining
Geomembrane rolls should be unloaded carefully to avoid material damage. Only the rolls that are going to be used should be unrolled, in order to reduce thermal elongation. This effect must also be taken into account when storing the rolls somewhere.
If the geomembrane is going to be placed on a slope, it should be done from its highest point to the lowest. It should be unrolled carefully, while avoiding wrinkles
During geomembrane deployment, the sheets can be supported by sandbags or other heavy objects (without sharp edges) to prevent them from being blown away.
- Step 3: Fuse the sheets
For the union of the HDPE geomembranes, the sheets must overlap between 10 cm or a little more, according to the chosen welding technique.
HDPE sheets are generally joined through hot melting which involves softening the sheets with heat until the material melts and eventually bonds after cooling. This operation is accomplished using hot wedge, hot air, or extrusion welding machines.
Before welding, the welder must be calibrated taking into account the ambient temperature and the thickness of the sheet.
- Step 4: Inspect the result
Lastly, the strength of the joint is tested, in order to avoid future leaks.
The recommended inspection methods for welds on HDPE sheets are vacuum test, air pressure test or spot tension test.
Each of these tests are described respectively by the American Society for Testing and Materials (ASTM) in standards D5641, D5820 and D4437. If, when testing, some of the seams do not meet the specifications, they must be repaired and tested again to ensure that they are welded correctly.
The installation of geomembranes is a rigorous process that requires the participation of trained engineers and technicians in order to guarantee proper assembly and maximize the useful life of the material.
COMOP CA. puts at your disposal our professional and technical experience, which guarantees the ideal use of this product. On our website you will find the product catalog and construction consulting service to accompany you at each stage of your project.
