Application of a Mass Balance-Based Stochastic Transport Model

The definition of contaminant source release is a necessary element of contaminant mass transport simulation in the saturated zone. At many sites the release history is unknown, and there has been a significant body of research to develop inverse models to define finite release histories. Instead of rigorously defining the source history, a mass balance-based approach is tested to explicitly account for uncertainty in rectangular pulse release variables. The approach has been incorporated into a spreadsheet model which uses a one-dimensional solution to the advection dispersion equation, which readily lends itself to Monte Carlo applications. After the model was tested with synthetic data sets, the model was calibrated and verified using a concentration data set collected at a Superfund site. Model calibration with synthetic and actual data resulted in a reasonable domain of source history parameters and the model provided reasonable results when the mass of contaminant in the aquifer was assumed to be random