Leach Pad

SENSOR DDS® technology applied to Leach Pad in gold mine

Leach Pad or Heap Leach Pad is a pond for the process where precious metals like gold, silver, copper or uranium is extracted from their ore. The ore is placed on the geomembrane (a base pad) with a heap and sprinkling a leaching solvent. As a solvent can be used cyanide or acids. This process dissolves the metals and they collect at the bottom of the pad called collection ditch.

If the geomembrane installed at Leach Pad is leaking, dissolved metals are then penetrating to the ground instead of the collection pit and so the mine is continuously loosing money and environmental consequences are even more serious. In some cases, mine is shut down for an unknown period of time.
On leach pads can be used either permanent geomembrane leak monitoring system or applied one time survey of exposed and covered geomembrane.


Leach Pad’s design cross section (from bottom to top):

  • Compacted clay
  • Geomembrane HDPE (2.0mm)
  • Protective geotextile
  • Drainage layer – gravel (50cm)
  • Ore

The size of the Leach Pad was 300.500m2 and total number of leaks detected straight after geomembrane installation was 582. If this high number of damage was not located prior to the Leach Pads operation, this mine would lost thousands of dollars every day and would eventually end up closed until those leaks were not found.

SENSOR DDS® MIT Arc Testing survey has been completed in 27 days on this site. The client has repaired located damage which were tested again afterwards. Sensor then has issued report including official certificate of geomembrane integrity of the Leach Pad.

Examples of detected and located damage at Leach Pad project:

One operator can test around 7000 m² of a leach pad a day depending on site conditions.

Once leak is localised, the gravel is excavated and liner damage on leach pad is repaired

Many times multiple damage is detected using our dipole SENSOR DDS® Mobile

Once the leak is repaired using patches and extrusion welding, the area is re-checked with Arc Tester

Overliner with thickness of 500mm are at most of the leach pads

First step to zero leak on leach pad is to test exposed liner with SENSOR DDS® MIT

The most frequent leaks found at leach pads are punctures caused by overliner penetrating through the liner

We can deploy as many operators as needed to complete the project on time