【国外标准】 Standard Guide for Selection of Techniques for Electrical Leak Location of Leaks in Geomembranes

4.1 Geomembranes are used as barriers to prevent liquids from leaking from landfills, ponds, and other containments. For this purpose, it is desirable that the geomembrane have as little leakage as practical.4.2 The liquids may contain contaminants that, if released, can cause damage to the environment. Leaking liquids can erode the subgrade, causing further damage. Leakage can result in product loss or otherwise prevent the installation from performing its intended containment purpose.4.3 Geomembranes are often assembled in the field, either by unrolling and welding panels of the geomembrane material together in the field, unfolding flexible geomembranes in the field, or a combination of both.4.4 Geomembrane leaks can be caused by poor quality of the subgrade, poor quality of the material placed on the geomembrane, accidents, poor workmanship, manufacturing defects, and carelessness.4.5 Experience demonstrates that geomembranes can have leaks caused during their installation and placement of material(s) on the geomembrane.4.6 Electrical leak location methods are an effective and proven quality assurance measure to locate leaks. Such methods have been used successfully to locate leaks in electrically insulating geomembranes such as polyethylene, polypropylene, polyvinyl chloride, chlorosulfonated polyethylene, and bituminous geomembranes installed in basins, ponds, tanks, ore and waste pads, and landfill cells.4.7 The principle behind these techniques is to place a voltage across a sufficiently electrically insulating geomembrane and then locate areas where electrical current flows through leaks in the geomembrane (as shown schematically in Fig. 1). Other electrical leak paths such as pipe penetrations, flange bolts, steel drains, and batten strips on concrete and other extraneous electrical paths should be electrically isolated or insulated to prevent masking of leak signals caused by electrical short-circuiting through those preferential electrical paths. The only electrical paths should be through leaks in the geomembrane. These electrical detection methods for locating leaks in geomembranes can be performed on exposed geomembranes, on geomembranes covered with water, or on geomembranes covered with an earthen material layer.FIG. 1 Schematic of the Electrical Leak Location Method (Earthen Material-Covered Geomembrane System is Shown)1.1 This guide is intended to assist individuals or groups in assessing different options available for locating leaks in installed geomembranes using electrical methods. For clarity, this guide uses the term “leak” to mean holes, punctures, tears, knife cuts, seam defects, cracks, and similar breaches in an installed geomembrane (as defined in 3.2.6).1.2 This guide does not cover systems that are restricted to seam testing only, nor does it cover systems that may detect leaks non-electrically. It does not cover systems that only detect the presence, but not the location, of leaks.1.3 (Warning—The electrical methods used for geomembrane leak location could use high voltages, resulting in the potential for electrical shock or electrocution. This hazard might be increased because operations might be conducted in or near water. In particular, a high voltage could exist between the water or earth material and earth ground, or any grounded conductor. These procedures are potentially very dangerous, and can result in personal injury or death. The electrical methods used for geomembrane leak location should be attempted only by qualified and experienced personnel. Appropriate safety measures must be taken to protect the leak location operators as well as other people at the site.)1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.