Exposed geomembrane integrity testing at Pregnant pond – Gold mining

Pregnant ponds and Barren ponds are the most crucial ponds in the mining process. They are used to store the chemical solutions containing gold or copper. Due to the aggressive nature of the stored chemicals no leakage is acceptable at such ponds. Therefore usually the pond consists of two layers of HDPE or LDPE geomembrane. The bottom liner is called “secondary” and the top liner is called the “primary” geomembrane.

Layered between the two liners a SENSOR DDS® leak detection system should be installed to make sure neither secondary nor primary geomembranes are leaking the chemicals into the environment. Immediate warning of a leakage is required and for that purpose 24/7 monitoring SENSOR DDS® RMS or CMS system can be installed.

For one time testing of both secondary or primary liner, we can also use our portable device for exposed liner testing SENSOR DDS® MIT Arc Tester. In order to test primary geomembrane a Sensor Leak Detection Geotextile must be installed between primary and secondary geomembrane.

Arc Tester – SENSOR DDS® MIT survey

Example Job Completed.

General project info:

  • Area tested was 120 000m²
  • Two layers of HDPE 1.5mm geomembrane installed
  • For exposed liner testing Arc Tester SENSOR DDS® MIT was used
  • 42 leaks found in total

During the testing of bare geomembrane integrity at Pregnant Pond project we detected and located 42 holes in total. The secondary liner contained 23 holes mostly cuts and weak weldings. 19 leaks with the same origin were identified on primary geomembrane too. After the survey the client repaired all holes and after re-testing we have issued the certificate of geomembrane integrity.

Some photos from the SENSOR DDS® surveys at mine’s Pregnant Ponds

Pregnant Ponds usually consists of two layers of geomembrane. It's necessary to test both using SENSOR DDS® technology.

With SENSOR DDS® portable devices we can test geomembrane integrity when Pregnant Pond is empty as well as when full of liquid.

At this project, slopes of Pregnant Pond were tested with Arc Tester and the bottom part with dipole SENSOR DDS® Mobile.

The most frequent leaks found at Pregnant Ponds by SENSOR DDS® MIT Arc Tester are cuts and weak extrusion and hot wedge welds.

Sensor’s operators are highly experienced engineers backed with SENSOR DDS® technology.

The holes detected by SENSOR DDS® MIT Arc Tester are at most cases impossible to identify by visual control.

The most common Pregnant Pond construction design consists of two layers of HDPE geomembrane.

SENSOR DDS® MIT Arc Testing has been ASTM approved in 2013. For more surveying details look for ASTM D7953.