Multi-Parameters Study on Landfill Pole-Dipole Leak Detection
The theoretical model of pole- dipole landfill leak detection and the parameters that influence the location results are studied in this paper. Parametric curves for a single leak show that the greater the thickness of the media above the liner, and the greater the distance from dipole and HDPE, the lower of the detection sensitivity; in a certain range, expand the dipole spacing, leaks can be detected effectively. To identify and resolve multiple leaks, the potential measurements must be made close to the liner and the detector dipole spacing must smaller than the separation of the leak.
Tracer verification and monitoring of containment systems (II)
A tracer verification and monitoring system, SEAtrace{trademark}, has been designed and field tested which uses gas tracers to evaluate, verify, and monitor the integrity of subsurface barriers. This is accomplished using an automatic, rugged, autonomous monitoring system combined with an inverse optimization code. A gaseous tracer is injected inside the barrier and an array of wells outside the barrier are monitored. When the tracer gas is detected, a global optimization code is used to calculate the leak parameters, including leak size, location, and when the leak began. The multipoint monitoring system operates in real-time, can be used to measure both the tracer gas and soil vapor contaminants, and is capable of unattended operation for long periods of time (months). The global optimization code searches multi-dimensional {open_quotes}space{close_quotes} to find the best fit for all of the input parameters. These parameters include tracer gas concentration histories from multiple monitoring points, medium properties, barrier location, and the source concentration. SEAtrace{trademark} does not attempt to model all of the nuances associated with multi-phase, multi-component flow, but rather, the inverse code uses a simplistic forward model which can provide results which are reasonably accurate. The system has calculated leak locations to within 0.5 meters andmore » leak radii to within 0.12 meters.« less
Model studies of electrical leak detection surveys in geomembrane-lined impoundments
Pole‐dipole array electrical potential distributions are calculated for a geomembrane‐lined liquid impoundment having single or multiple leaks. A three‐dimensional numerical model is employed to represent a small circular leak in the highly resistive plastic liner. The liquid waste material, the liner, and the soil under the impoundment are simulated by infinite horizontal layers, with approximate corrections for the finite size of the impoundment. Parametric curves for a single leak show that with optimum selection of electrode spacing and positioning and other field survey parameters, leaks can be detected effectively. To identify and resolve the presence of a cluster of leaks, the potential measurements must be made close to the liner and the detector dipole spacing must be smaller than the separation of the leaks. The results also indicate that the survey speed may be increased when portable leak detection equipment employing a vertical dipole detector is used.