In 2017, the Institute of Underground Infrastructure (IKT), Gelsenkirchen, Germany, utilized low voltage conductivity to test a variety of trenchless Cured-In-Place Pipe (CIPP) short-liners to locate and quantify leaks, several of which were utilized in a multi-million rehabilitation project in Kansas City, Missouri (USA).
While CIPP suppliers participating in. the IKT government-funded research project had the opportunity to install their liners in IKT test facilities, trained & licensed contractors were responsible for installing the same liners in Kansas City, with subsequent flow monitoring indication that significantly less flow reductions had occurred. Utility management and consulting engineers determined that either (1) the wrong pipes were selected to rehabilitate, and/or (2) trenchless rehabilitation had leaks. High resolution Closed-Circuit Television (CCTV) inspection was used to both select pipes requiring rehabilitation and post-rehabilitation watertightness.
This paper describes the use of low voltage conductivity to test pre- and post-rehabilitation of sanitary sewerage pipes.
By introducing electric current inside a non-conductive pipeline (i.e. non-metallic) using a tethered probe, the locations low voltage conductivity, also referred. to as focused electrode leak location. (FELL) is able to locate leak location to within 1cm. By identifying where and how much electric current escapes to earth, i.e. a grounding source, algorithms can estimate a liters per second of each individual leak. The larger the dissipation of current to earth, the larger the defect, allowing low voltage technology to detect leaks missed by conventional CCTV cameras, acoustic sensors, lasers, sonar, smoke testing, and air & water pressure testing.
Similar to traditional holiday testing to assess protective coating, this paper will describe the science of low voltage, field operations, data formats, and international adoption that includes ASTM F2550-13 (2018), Standard Practice for Locating Leaks in Sewer Pipes By Measuring the Variation of Electric Current Flow Through the Pipe Wall.