Photo 1: Electrical arc formation through leak in corrugated pipe penetration. Image Courtesy of Sensor. (Click to view larger.)

After having been in commercial use in Europe since 1999, the arc testing method for liner integrity surveys (LIS) has finally found a home among the other electrical leak location methods in the ASTM International standards system.

Arc testing evolved from the spark testing method, but arc testing is quite a different technology. Spark testing is used specifically for coextruded, conductive-backed geomembrane; while, the arc tester has been specially designed to use natural materials (soil, clay, rock) as the conductive medium for the electrical path. While the spark tester uses a build-up of electrical potential to discharge discrete sparks, the arc tester maintains a continuous electrical arc, as shown in Photo 1.

The convenience and effectiveness of arc testing in testing an installed geomembrane for leaks has helped it spread rapidly in the past five years, and not just in Europe where it was developed. The technology has established an impressive track record for locating even the smallest of leaks in projects in Chile, Bolivia, Mexico, Canada, Finland, Turkey, Korea, Japan, China, Peru, Australia, Argentina, and, finally, the United States.

Between 2009 and 2014, roughly five million square meters of geomembrane were surveyed by arc testing around the world. The method located thousands of leaks that may otherwise have remained undetected in containment facilities throughout the world.



Photo 2: Arc testing vertical wall of geomembrane-lined dam. Image courtesy of TRI Environmental. (Click to view larger.)

Although the arc testing method is technically equivalent per ASTM to other exposed geomembrane leak location methodologies (e.g., ASTM D7002 and D7703), the arc tester provides some clear advantages.

Foremost, the method does not require the addition of water to carry the current for the electrical detection path. For the water puddle and water lance methods, a water truck must typically be provided onsite to feed the water-based leak detection equipment. This adds cost to a project. In water-scarce regions, these methods may not even be feasible.

Additionally, the conveyance of water requires a second laborer to assist with movement of the water supply hoses, while the arc tester can be operated by only one person. Multiple arc testing operators can be present in one area, since they don’t maintain water puddles that can interfere with the water puddle of an adjacent operator.

Also, the arc tester is more amenable to testing extremely sloped or vertical surfaces. It is far easier for an electrical arc to travel horizontally through a geomembrane to connect with the concrete or metallic vertical wall than a jet or puddle of water. And water-based methods require that sites contain a low spot where the water used to perform the survey is allowed to collect. If the water flows out of the survey area and touches the earth outside of the lined area, then electrical current will also flow out of the survey area, compromising the survey sensitivity.

As shown in Photo 2, the arc tester can be utilized on projects that do not have a low area for water collection. There is no risk of compromising the survey from water flowing off the liner.


Installations with many leaks pose a similar challenge for water-based methods. It is more difficult for these methods to distinguish between multiple leaks in a small area, since all of the leaks are connected to each other via the water spread over the geomembrane. Similarly, it is difficult to test very close to the edge of a geomembrane or a conductive batten strip with water methods, since the water will tend to splash onto the conductive feature, resulting in a leak signal whether or not a leak is actually present.


Photo 3: Damage located by arc testing method adjacent to conductive batten strip. This type of leak would be almost impossible to find with water-based survey methods. Image Courtesy of Sensor. (Click to view larger.)

As shown in Photo 3, the arc tester has an easier time locating leaks near conductive features.

One capability that the arc tester provides that is not technically possible with the other electrical leak location methods is the testing of geomembrane with a geotextile installed over it. As long as the geotextile is dry, the equipment will have no problem arcing through the geotextile when there is a leak in the geomembrane. The arc tester can also instantaneously detect leaks through the tortuous paths of extrusion-welded patches, which takes more time and can be passed over with the water-based methods.

The arc testing equipment is also easier to calibrate and operate than the water-based methods, which often require sensitivity adjustments during the survey. An operator with no special skills can be trained to use the arc tester in a few minutes; once the unit is on and set to the proper sensitivity level for the thickness of the geomembrane, it simply needs to be passed over the geomembrane and the arc and alarm will be activated in the presence of a leak.

The new Standard Practice for the arc testing method is designated ASTM D7953 and is now available on the ASTM website.

4 Comments to "Electrical Leak Location Method Receives New ASTM Designation"

  • hamidreza
    January 10, 2015 at 10:35 am


    1. Abigail
      January 16, 2015 at 4:19 pm

      Please go to the “Resources” page of this website and click on the first link. That guide will provide you with more information on the methods. 2mm GM thickness is tested no differently than other GM thicknesses.

  • Mason
    March 3, 2015 at 1:27 pm

    Is arc more effective at testing around pipe penetrations through the liner than spark testing?

    1. Abigail
      March 12, 2015 at 1:27 pm

      The methods don’t matter so much as the conditions of the installation. The spark tester needs either conductive-backed geomembrane or a wire embedded in the weld. So, it requires specialty geomembrane and some prep work for testing welds. The arc tester can be used on any geomembrane without any prep work; it is grounded to the subgrade below the geomembrane. Since the limitations of the arc method include the maximum arc length, even though both techniques should yield the same result, I would say that the spark tester would be better if there is a gap between the geomembrane and the subgrade. For the arc tester, if the gap exceeds about an inch, a leak could go undetected. This doesn’t matter for the spark tester because the conductive backing is in intimate contact with the geomembrane so there is no issue about being too far from it for the spark. However, if conductive-backed geomembrane is used, then the arc tester works much better and should perform equally as well as the spark tester.
      So, the answer to your question is that they will be equally accurate if conductive-backed geomembrane is used. By definition, the spark tester needs conductive-backed geomembrane but the arc tester can be used without it (with less success).

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