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New findings on Exposed Geomembrane Leak Location methods, with a focus on the Water Puddle and Arc Test Methods

The electrical leak location methods used on exposed geomembranes are typically the Water Puddle method (ASTM D7002) and the Arc Test method (ASTM D7953). Other methods do exist, including the Water Lance method and the Spark Test method, similar to the Arc Test method but only suitable for surveys performed on conductive backed HDPE geomembrane. Both the Water Puddle method and the Arc Test method are commonly used on PVC, HDPE and bituminous geomembranes, but the question remains as to whether the two methods can be seen as equivalent. An obvious difference is found in their voltage use and leak location methodologies: the Water Puddle method applies low voltage (around 40 V) to water passed through defects in the geomembrane, whilst the Arc Test method applies high voltage (up to 35,000 V) to pass electrical arcs directly through any defects. But the differing effects on the two methods used in specific conditions are still not widely understood and may not be equivalent. The first part of the paper will present how each of the two leak location methods work, highlighting their differences and their respective limitations. Results from tests of both methods on different types of geomembranes of varying thicknesses will then be presented. The goal of this paper is to educate engineers and leak location practitioners on the differences between the available exposed membrane leak location methods and on which methods are more suitable given the types of geomembrane tested, weather and site conditions, and project particularities.