Dissolution of a multicomponent DNAPL pool in an experimental aquifer

This paper presents the results from a well-defined, circular-shaped, multicomponent dense nonaqueous phase liquid (DNAPL) pool dissolution experiment conducted in a three-dimensional, bench scale model aquifer. The multicomponent pool is a mixture of tetrachloroethylene (PCE) and 1,1,2-trichloroethane (1,1,2-TCA); PCE was the major component and 1,1,2-TCA was the minor component. Downgradient plume concentrations were measured at five specific locations over time until the majority of the 1,1,2-TCA was depleted from the DNAPL pool source. The experimental results suggest distinct spatial-temporal plume patterns for minor DNAPL components versus major DNAPL components. The downgradient concentration varied over time for 1,1,2-TCA while a stable plume developed for PCE. A semi-analytical solution for contaminant transport resulting from dissolution of multicomponent nonaqueous phase liquid pools successfully simulated the plume structure and dynamics for both the major and minor DNAPL components.