Determination of leakage from subsurface containment systems using informational entropy and hydraulic signature assessment methods.

Abstract

The use of physical and hydraulic containment systems for the isolation of contaminated ground water and aquifer materials associated with hazardous waste sites has increased during the last decade. The existing methodologies for monitoring and evaluating leakage from hazardous waste containment systems rely primarily on limited hydraulic head data. The number of hydraulic head monitoring points available at most sites employing physical containment systems may be insufficient to identify significant leakage from the systems. A general approach for evaluating the performance of containment systems, based on relative spatial and temporal hydraulic head distributions is used to introduce two methodologies for estimating the minimum number of monitoring points necessary to identify the hydraulic signature of leakage from a containment system. Three-dimensional ground-water flow modeling results are used to illustrate the utility of a probabilistic method, based on the principles of geometric probability. Leakage from a vertical barrier containment system is simulated using a variety of hydrogeologic conditions ranging from homogeneous to heterogeneous, and isotropic to anisotropic. The second method utilizes informational entropy to quantify the spatial variability of hydraulic signatures associated with containment system leakage in the presence of background noise and trend surfaces.