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Mine Closure and Remediation: The Role of Geomembranes in Environmental Legacy

Written by Paulina Encinas | Jan 7, 2026 7:00:13 PM

The closure of a mining operation is perhaps the most critical challenge in the life cycle of a project. It is not simply about dismantling structures, but about ensuring that the ecosystem regains its balance and that the waste generated over decades remains permanently isolated. For environmental directors and sustainability managers in regions such as the Andes or the Amazon, the central concern is acid mine drainage and the infiltration of heavy metals into watershed systems.

In this context, geomembrane installation is not a final operating expense, but rather the core component of a long-term environmental insurance policy. A poorly executed closure capping system can result in leaks that require costly and perpetual water treatment, destroying the company’s reputation and its social license to operate future projects.

 

Risks of an Inadequate Cover System

  • Water Infiltration: If the sealing system fails, water interacts with sulfides in tailings, generating sulfuric acid.
  • Erosion of the Cover Soil: Without a design that integrates geomembranes and drainage geocomposites, the vegetative soil layer above the cover can slide.
  • Groundwater Contamination: Failure of the liner integrity allows leachate to reach the water table, impacting downstream communities.

 

Design of Multilayer Cover Systems

A successful mine closure uses a “flow barrier” approach. SAI implements solutions in which the geomembrane works in conjunction with other geosynthetics to maximize geomembrane durability / lifespan.

  • Regulating Layer: Preparation of tailings or waste rock to receive the sealing system.
  • Primary Barrier: Typically an HDPE geomembrane (high-density polyethylene) of a specified thickness, selected for its very low permeability.
  • Upper Drainage Layer: A geocomposite that evacuates rainwater percolating through the vegetative soil, preventing hydrostatic pressure from damaging the geomembrane.
  • Protection and Soil Layer: Selected soil that allows site revegetation.

 

Critical Components of the Closure System

Component
Technical Function
Importance in Closure
HDPE Geomembrane
Absolute impermeable barrier
Prevents O₂ and H₂O ingress into waste
Nonwoven Geotextile
Mechanical protection
Prevents puncturing by rocks in the cover soil
Drainage Geonet
Fluid management
Reduces saturation of the upper soil, preventing slope instability

 

The Importance of Texturing on Closure Slopes

Tailings storage facilities often have steep slopes to optimize space. In these cases, the use of smooth geomembranes is technically unfeasible due to their low friction angle. SAI recommends the use of textured geomembranes, which increase friction with the cover soil and ensure post-closure stability. A sliding failure in a closure cover is one of the most complex and costly repairs in the industry.

 

Technical Execution and Quality Control in Closure

Since the cover system will be buried under meters of soil and vegetation, precision during geomembrane installation must be absolute. There will be no opportunity to repair a failed weld once the site has been revegetated.

At SAI, we apply CQA (Construction Quality Assurance) protocols that include destructive and non-destructive testing on every meter of seam. Traceability of every panel deployed in a mine closure is what ensures that the company’s environmental legacy is positive and compliant with international closure standards.

Mine closure is the final act of responsibility for an operator. Choosing a certified installation partner with experience in difficult terrain is the only way to ensure that investments in environmental protection are effective. SAI provides the engineering expertise and precision required for geomembranes to perform their barrier function for decades, transforming an industrial site into a safe environment for future generations.

Do you have a mining project coming? Contact us, SAI is your best ally to maintain quality while protecting your operations. 

 

Frequently Asked Questions (FAQ)

  1. What geomembrane thickness is recommended for mine closures?

    Typically, HDPE geomembranes with thicknesses between 1.5 mm and 2.0 mm are used, depending on the overlying soil load and the aggressiveness of the waste.
  2. How long can a geomembrane last in a cover system?

    Under buried conditions (protected from UV radiation), the geomembrane durability / lifespan of a high-quality resin can exceed 100 years.
  3. Can geomembranes be installed over soft tailings?

    Yes, but it requires the use of reinforcing geogrids prior to geomembrane installation to provide a stable and safe working platform.