Aquifer remediation by pumping: A model for stochastic-advective transport with nonaqueous phase liquid dissolution

The coupled effects of advection and rate-limited mass transfer to the aqueous phase from residual dense nonaqueous phase liquid (DNAPL) in the saturated zone are investigated within an analytical stochastic-advective framework. The transport domain is assumed to consist of a source zone where mass transfer takes place and a down-gradient plume zone where transport is by advection only. The mass flux in the aquifer is evaluated from an analytical solution to coupled advection-reaction and nonlinear mass transfer equations. The results emphasize the importance of the parameters associated with the source zone: its length in the mean flow direction, the residual DNAPL saturation, and the mass transfer rate coefficient. The sensitivity to the hydraulic conductivity variance is low for significantly rate-limited mass transfer. It is found that advection in the plume zone has small effect on mass fluxes and cleanup times for the considered lengths of the source and plume regions.