Tailing Dam Liner Integrity Testing – Gold Mining
A tailing dam is an earthen embankment used to store the by-products of mining operations. This is created after separating the mineral from the unwanted gangue in the ore. The stored tailings are either liquids, fine particle slurries, or solids all with high toxicity.
Containment of the toxic material is of course important in order to avoid excessive future clean up costs, however a greater concern even than that is the long term stability of the dam wall itself.
We have seen a number of high profile tailing dam failures that have caused billions of dollars worth of damage. Saving a few dollars in construction really does not make sense when storing large volumes of liquid tailings.
The use of SENSOR DDS® technology to manage the integrity of the geomembrane should be a no brainer for tailings given the risks to the operational bottom line. But also SENSOR DDS® LID can be used to continuously test the permittivity of the earthen dam wall itself EVEN WHEN NO GEOMEMBRANE IS INSTALLED!
Testing geomembrane integrity during tailing dam construction can detect and locate all the leaks caused by geomembrane damage. Arc Testing is the recommended first step with SENSOR DDS® MIT. The liner is often covered with gravel and in this case the geomembrane integrity can be tested using SENSOR DDS® Dipole.
SENSOR DDS® MIT and SENSOR DDS® Dipole - South American Mine
Example project info:
- Area tested was 2,830,000sqft
- Single layer of HDPE 60mil geomembrane installed
- Protective layer: 2ft of gravel
- For exposed liner testing SENSOR DDS® MIT arc testing was used
- For covered liner testing SENSOR DDS® Dipole testing was used
During the MIT integrity testing of the exposed geomembrane at this gold mine tailings dam project we detected and located 132 holes. Most of the holes represented cuts or weak extrusion welding, however holes caused by cigarette burns were also very frequently discovered. The average productivity at this project was 95,000sqft per day per operator spread over several visits.
The installation of the gravel (for drainage and protection) was carried out and following this the Sensor DDS® Dipole survey was carried. The total damage found during our testing was 102 holes. The most common cause of leaks by more then 53% was from gravel penetrating through the liner from above. This happens when heavy machinery tracks on top of the gravel over the liner and presses into the geomembrane forcing the gravel through the geomembrane.
Tight turns with made by the machines even on top of two foot of gravel cause rotation that is transmitted by friction to the geomembrane which slips and creates large rips in the geomembrane rendering it useless, the following image shows the repair of this damage.
SENSOR DDS® Leak Location Technologies save the client time and money by identifying leaks during the construction phase. It is disruptive, expensive and technically complex to repair leaks when a Tailing Dam is in full operation.
Some photos from SENSOR DDS® surveys from various Gold Mine Tailing Dams
Tailing Dam
SENSOR DDS® Dipole can detect multiple leaks
At this Tailing Dam the thickness of protective overliner was two foot.
Large scale projects require many operatives to perform SENSOR DDS® surveys.
When testing steep slopes, the daily production rate of each operative is lower.
When anomalies are detected with SENSOR DDS® Dipole the area is excavated and physically checked with SENSOR DDS® MIT
Large rip is typically caused by excavators and trucks tracking over the gravel SENSOR DDS® technology reveals all these issues.
On the slopes operatives must always use safety harnesses during leak location testing.
