Selection of Anti-Seepage Materials for Tailings Storage Facilities
A tailings storage facility (TSF) is a dedicated dam structure used to store tailings — the fine waste residues produced after mineral processing, which still contain trace useful components. It is not a simple dumping site. It is a complex and high-risk engineered system composed of a retaining dam, reservoir area, and drainage & seepage-control systems.
Potential Risks of Tailings Storage Facilities
Tailings storage facilities are widely recognized as high-energy artificial hazard sources. Their risks mainly appear in the following aspects:
（1）Dam failure risk
If the water level rises too high due to dam instability, earthquakes, or heavy rainfall, a dam break may occur. Large volumes of tailings slurry can then evolve into debris flows with strong destructive power.
（2）Pollution from seepage and dust
Tailings often contain heavy metals (such as lead, arsenic, mercury and cadmium) and chemical reagents used in mineral processing (such as cyanide, acids and alkalis). These substances can infiltrate the soil and groundwater with rainwater, causing contamination. Such pollution is wide-ranging and extremely difficult to remediate.
In addition, when tailings dry out, fine particles can be lifted by the wind, forming dust pollution that affects nearby air quality.
Because the placement and long-term maintenance of tailings reservoirs is a large and systematic task, specialized materials and solutions are essential. From the perspective of geosynthetic solutions, we establish four types of systems to address different risks in tailings storage facilities — a “seepage control and sealing system,” a “drainage and seepage-collection system,” a “reinforcement system,” and an “eco-restoration system.”
（Image source: Google）
Ⅰ. Seepage Control and Sealing System
Goal: Prevent harmful leachate from contaminating soil and groundwater.
Materials used:
- HDPE geomembrane (high-density polyethylene liner):
This is the core of seepage-control systems. Its extremely low permeability (≤10⁻¹² cm/s) forms a reliable barrier. It is widely used in basin floors and dam slopes as the main lining material.
- GCL (Geosynthetic Clay Liner):
Often used together with HDPE geomembranes to form a double-liner system. GCL can swell upon wetting and offers self-sealing capability in case of local damage, providing added safety.
- Nonwoven Geotextile:
Used as protection layers above and below HDPE geomembranes to prevent puncture from sharp stones.
Application method:
After the reservoir foundation is leveled and treated, a composite structure is installed: geotextile protection layer + HDPE geomembrane primary liner + geotextile protection layer. This achieves comprehensive seepage control.
（Zhonglong's GCL）
Ⅱ. Drainage and Seepage-Collection System
Goal: Efficiently collect and discharge accumulated water (surface water) and internal seepage from the dam body. Lowering the phreatic line is key to maintaining dam stability.
Materials used:
- Three-dimensional composite drainage net:
It has very high transmissivity and can replace traditional gravel drainage layers. When installed on dam slopes or reservoir floors, it rapidly collects and directs water to collection wells. It improves efficiency and saves space.
- Geosynthetic drainage pipes:
Used together with drainage nets as the main water-conveying channels.
（Image source: Google）
Ⅲ. Reinforcement System
Goal: Increase the overall stability and anti-sliding capacity of the dam.
Materials used:
- Biaxial geogrid:
It has high tensile strength. When placed between different layers of fill at various elevations, the interlocking friction between the geogrid and soil spreads loads over a wider area. This significantly enhances slope stability and helps prevent landslides. It is especially effective when the dam is constructed using tailings sand itself.
(Zhonglong's Biaxial Geogrid)
Ⅳ. Eco-Restoration System
Goal: Ensure safe closure at the end of the facility’s service life and achieve ecological recovery.
Materials used:
- HDPE geomembrane + Three-dimensional composite drainage net:
These form the “capping system.” The geomembrane blocks rainwater from entering the tailings, reducing leachate at the source. The drainage layer above it discharges surface runoff.
- Three-dimensional vegetation net:
Installed on the top layer of the capping system and filled with topsoil. It provides a stable base for vegetation growth, prevents erosion, and supports ecological restoration.
- Dust-control net / erosion-control mat:
Used for temporary or permanent suppression of dust after closure.
(Zhonglong's Composite Drainage Net)
References:
The Application of Geosynthetics in Tailings Storage Facilities: A General Review: https://www.mdpi.com/2673-6489/4/2/26
Seepage stability analysis of geogrid reinforced tailings dam: https://pmc.ncbi.nlm.nih.gov/articles/PMC10799897
Lining of mine residue storage facilities: https://library.geosyntheticssociety.org/wp-content/uploads/resources/proceedings/122021/S22-06.pdf
（Image source: Google）
Products page:
Geogrid: https://www.zhonglonggeo.com/geogrid-1
Composite Drainage Net: https://www.zhonglonggeo.com/three-dimensional-composite-drainage-net
Geosynthetic Clay Liner (GCL): https://www.zhonglonggeo.com/geosynthetic-clay-liner-1
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Sichuan Zhonglong Environmental Protection Co., Ltd.
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