Effect of natural advection on stabilization of contaminant plume in natural traps at underground disposal of liquid wastes

The migration of a contaminant from a zone of injection disposal of hazardous liquid waste in a deep-seated aquifer is considered. Because of its higher density, the polluted groundwater will accumulate under the effect of gravity in aquifer dips (depressions). A 2D-model of variable-density groundwater flow is used to determine the conditions under which the gravity force will prevent polluted groundwater from leaving depressions driven by regional current. As the result, such depressions can serve as natural traps for polluted waters. The required conditions are based on simple analytical relationships, derived from the analysis of a theoretical model of variable-density groundwater flow in an inclined confined aquifer. The obtained technique is used to estimate the efficiency of such a trap at the site of injection disposal of liquid radioactive waste from Mining and Chemical Combine in Krasnoyarsk region. The analytical estimates of the trap with the use of the proposed technique are shown to be in good agreement with the results of numerical simulation of contaminant migration.