With so many challenges to storing and containing tailings in the long run, it is important to choose a liner that can handle the material. Many materials used for other commercial and industrial lining purposes will not work for tailings. This is particularly true if oil or coal residues are mixed in with the waste rock. Not only will the weight of the tailings be an issue for any geomembrane that is not up to the job, the abrasiveness of the material does not help. Rips and tears can occur during installation, but they are particularly likely to occur during filling when it’s practically impossible to spot the damage. Make sure to choose a tough liner that will not fail under hundreds of thousands of pounds of tailings or sludge with these recommendations.
PVC: Not a Great Choice
Polyvinyl chloride is one of the most commonly used polymers for crafting flexible liners. It is widely recommended for both pond lining and industrial basin lining, but it is not right for all uses. First, PVC lacks the puncture and tear resistance necessary to handle the weight and shape of the tailings. It’s simply too prone to tears or ripping apart from the wear that occurs from a sharp pile of tailings or the associated sludge. The chemical resistance of this material is also low, increasing the likelihood of early failure when processing chemicals or compounds from the ore soak down and reach it. Finally, many PVC liners feature a higher permeability than RPE and other materials. Save PVC for lining applications where there is far less at risk and use a more reliable material for tailings containment.
HDPE: Too Stiff
High density polyethylene may sound like the ideal material for lining a tailings pond. It is true that it offers good damage resistance, especially against tears during installation. However, this durability comes at the cost of stiffness and thickness. Thick and stiff materials are harder to install, increasing both labor costs and the likelihood of a mistake that leads to leaking in the long run. HDPE does not like to conform to curves and bends as easily as other options, leading to stretched and displaced material when it can’t adapt to voids and variations in the surface. While HDPE may work if it’s the only material available, this is rarely true. RPE should be available almost anywhere HDPE is found and is a much better choice for lining tailings containment areas.
LDPE: Poor Chemical Resistance
Low density polyethylene is not the exact solution to the lining challenges of tailings either. While it is more flexible than HDPE, it is also less strong and offers lower tear and puncture resistance. This is essential for tailings containment, so it is a deal breaker for LDPE liners. Another issue is chemical resistance. LDPE simply does not have the chemical resistance necessary for holding most tailings. Not only will any petroleum byproducts cause degradation of this material over time, it also can react to many of the strong acids and similar chemicals that are used for ore processing. Tailings rich in these chemicals should be stored in impoundments lined with RPE and not LDPE.
RPE: The Best Choice
Reinforced polyethylene may not sound much different than HDPE or LDPE, but it is a completely different product. First, the reinforcement plays a big role in how well the material handles punctures, tears, rips, and more. A reinforcement scrim pressed between the layers of the liner ensures that the material can bend and fold without breaking open. It also assists during installation by increasing the lay-flat of the material, reducing the effort needed to stretch it smooth over a surface. Wrinkles can crack under the weight of tailings, turning into leaks. So, easy to smooth material is worth considering when installing liner on this kind of scale. Of course, RPE offers more than just durability. It is also the best choice for chemical resistance, regardless of the type of tailings that need storage. RPE is appropriate for almost all storage spaces on the mine, from tailings to runoff and liquids stored in ponds as well. There is no need to find a wide range of different liners for different materials when choosing products from BTL Liners.
Is Underlayment Required?
Underlayment is a separate material from the liner, but it is often confused with it. It is generally a thick and felt-like material that is installed against the graded soil and below the liner. Unlike the liner itself, this material is usually not particularly impermeable. So why it is recommended or even needed if it does not block water itself? It is a cushion and protective layer to keep the liner from becoming torn by the surface below. It is especially recommended on large scale projects like tailings impoundments because of the weight pressing down on the liner. Without underlayment, every rock and root left exposed in the soil has a chance to rip the liner open and cause a leak. Putting in a cushion of underlayment does raise the cost of lining the facility, but it may be worth it if it helps eliminate remediation costs by preventing leaks in the long run.
There is no need to settle for less than the best materials for lining tailings impoundments. BTL Liners has the reinforced polyethylene (RPE) liners needed for all kinds of tailings storage areas. From permanent disposal pits to containment for temporary holding tanks and transfer areas, our liners can do it all. Make an investment in environmental protection for the start to keep remediation and recovery costs from growing out of control after the mine shuts down and the profits stop coming in.
