Exposed Geomembrane Integrity Testing of Pregnant Ponds – Gold Mining
Pregnant Ponds and Barren Ponds (process ponds) are the most crucial liquid storage ponds in the mining process. They are used to store the chemical solutions containing dissolved minerals (e.g. gold an copper). The monetary value of the stored solutions and the head pressure on the geomembrane means that no amount of leakage is acceptable. These process ponds normally consist of two layers of HDPE or LLDPE geomembrane. The bottom one is called “secondary” or "L2" and the top one “primary” or "L1" geomembrane.
Arranged between these two liners a SENSOR DDS® leak location system can be installed to ensure neither secondary or primary geomembranes are leaking the valuable product into the ground. Leak monitoring provides immediate leak alerts and for our range of leak alerting systems provide 24/7 monitoring SENSOR DDS® LAM, RMS or CMS all provide immediate derection of leaks and alert owners or operators electronically by SCADA / SMS / email and even via our proprietary apps. Each leak alarm system differs by the resolution of its positioning accuracy and speed of position calculations.
For the one time testing of both secondary or primary liners, we can use our portable liner leak testing device SENSOR DDS® MIT Arc Tester.
Arc Testing Survey – SENSOR DDS® MIT Test
Example Job Completed.
General project info:
- Area tested was 1,200,000sqft
- Two layers of HDPE 60mils geomembrane installed
- For exposed liner testing Arc Tester SENSOR DDS® MIT was used
- 42 leaks found in total
During the testing of the uncovered geomembrane at this Pregnant Pond project we detected and located 42 holes in total. The secondary liner contained 23 holes mostly cuts and weak welds. The primary geomembrane also had 19 leaks of similar origin which were also detected during the MIT testing process.
After detection of the leaks during the survey, the client repaired all the holes which after re-testing enabled Sensor to issue a Certificate of Geomembrane Integrity.
Some photos from SENSOR DDS® leak detection in Mining Process Ponds
With SENSOR DDS® portable devices we can test geomembrane integrity when Process Ponds are empty as well as when full of liquid.
At this project, the slopes of a Pregnant Pond were MIT tested and the bottom part with SENSOR DDS® Mobile Dipole.
The most frequent leaks found at Pregnant Ponds by SENSOR DDS® MIT are cuts and weak extrusion welding..
Sensor’s has highly experienced engineers backed up with SENSOR DDS® technology.
The holes detected by SENSOR DDS® MIT testing are often impossible to identify by visual examination.
The most common Process Pond construction design consists of two layers of HDPE geomembrane.
SENSOR DDS® MIT Arc Testing was ASTM approved in 2013. For more surveying details look for ASTM D7953.