Geotextile Engineering Case of Tailings Pond

Geotextile Engineering Case of Tailings Pond
Standard Full-pond Anti-seepage Geotextile for Metal Mines

1. Project Overview
Project‌: This tailings pond is a Class IV tailings pond with a total storage capacity of 8.857 million m³, a dam height of 18.5m, and a design service life of 10 years. It stores acidic molybdenum ore tailings slurry, and its leachate contains acid-base corrosive wastewater. Full-pond anti-seepage is mandatory by environmental protection regulations.

The total anti-seepage construction area is 500,000 m². The complete anti-seepage structure adopts a two fabrics one membrane structure: 600g filament geotextile (lower layer) + 2.0mm HDPE anti-seepage membrane (middle layer) + 400g filament geotextile (upper layer). All filament polyester geotextiles are selected as polyester spun-bonded needle-punched geotextiles.

2. Geotextile Laying Zoning & Gram Weight Selection
(1) Pond Bottom Base (under membrane, 600g/m² filament geotextile)
The base is weathered gravel soil with a large number of angular crushed stones. Geotextile acts as a buffer cushion to isolate sharp stones from the foundation and prevent the HDPE membrane from being punctured. Meanwhile, it discharges underground seepage, converges the seepage into the blind drainage system at the pond bottom, and avoids membrane bulging under the membrane that would tear the anti-seepage layer.
(2) Protective Layer Above Membrane (400g/m² filament geotextile)
Tailings sand and crushed stones are laid on the upper part to press the slope. Geotextile isolates tailings aggregate from the anti-seepage membrane, and prevents coarse particles from scratching the membrane through friction. It also intercepts fine tailing sediment, only allowing leachate to penetrate downward, so as to realize filtration and drainage.
(3) Dam Slope Anchor Trench & Around-dam Anti-seepage Zone: 400g filament geotextile
The size of the anchor trench is 0.8×0.8m. The geotextile is embedded in clay for anchoring, to prevent the slope from sliding and tearing the anti-seepage system.

3. Core Functions of Geotextile
① ‌Protection & puncture resistance‌: Adopt the matching combination of high and low gram weight geotextiles: thick geotextile at the bottom buffers the foundation, and thin geotextile at the top protects the covering soil. After construction, spark leak detection of the whole anti-seepage membrane showed zero damage.
② ‌Filtration and drainage‌: It intercepts fine particles of tailings, avoids sediment blocking the gravel drainage layer, and allows leachate to flow smoothly into the collection well for reuse.
③ ‌Acid and alkali corrosion resistance‌: It is suitable for the acidic tailings water environment of molybdenum mines, will not pulverize after long-term immersion, and completely prevents tailings leachate from polluting groundwater.

4. Project Effect
The project has been in operation for 6 years. There is no seepage or dam piping, and groundwater monitoring meets the standards. It has become a general benchmark for anti-seepage construction of metal mine tailings ponds.