Tailings Pond Anti‑Seepage Project (Filament Nonwoven Geotextile)
Tailings Pond Anti‑Seepage Project (Filament Nonwoven Geotextile)
1. Project Background
This is a Grade IV mine tailings pond with a storage capacity of 8.857 million m³. Parts of the pond base contain crushed stone and calcareous concretions with abundant sharp protrusions. The tailings slurry contains heavy metals; once leachate infiltrates downward, it will contaminate groundwater. The anti‑seepage system adopts a composite liner structure: “lower geotextile + HDPE geomembrane + upper geotextile”.
2. Geotextile Specification & Consumption
Type: Polyester filament spun‑bonded needle‑punched nonwoven geotextile
Lower layer (beneath membrane): 600 g/m²; CBR burst strength ≥12 kN, featuring puncture resistance, drainage and filtration functions
Upper layer (above membrane): 400 g/m²; CBR burst strength ≥6.0 kN
Net laying area for each single layer: 500,000 m²; total procurement quantity for two layers: 1,080,000 m² (including 8% wastage for side slopes and anchor trenches)
3. Functions & Performance of Geotextile
✅ Lower layer: Drainage + Protection + Filtration; Upper layer: Puncture‑proof protection
Lower layer: Collect trapped seepage water under the membrane and relieve uplift pressure; isolate sharp aggregates on the base to prevent scratches on the membrane underside.
Upper layer: Separate the HDPE geomembrane from the tailings crushed‑stone drainage layer, distribute concentrated stress and avoid puncturing of the liner by crushed stone; intercept fine tailings particles to prevent clogging of the drainage layer.
✅ Performance outcome: No local bulging or uplift pressure occurs beneath the membrane; very few leakage points are found during weld inspection of the geomembrane. All leachate is collected, and groundwater monitoring meets the standard requirements.
4. Construction Parameters
Laying: Manual spreading, laid from top to bottom on slopes; relaxation allowance controlled at 2%–3%.
Joints: Sewing is preferred; anti‑ageing polypropylene sewing thread shall be used; overlap width ≥30 cm; ≥40 cm at slope break points.
Fixation: U‑shaped geotextile nails, installed at 1.2 m vertical spacing and 1.0 m horizontal spacing on slopes; denser fixing at anchor trenches along slope crests.
Control requirements: Sharp protrusions on the foundation shall be ground and removed in advance; throwing boulders directly onto the geotextile is prohibited.
5. Division of Work with Other Components
Lower geotextile: Base cushioning, under‑membrane drainage and filtration;
HDPE geomembrane (2.0 mm): Core anti‑seepage layer to block contaminated leachate;
Upper geotextile: Membrane protective layer and filter layer;
Crushed stone drainage layer + collection pipes: Gather tailings leachate and convey it to the leachate regulation tank.
