Stochastic Modeling of Plume Evolution and Monitoring in Heterogeneous Aquifers

Abstract

A Monte Carlo stochastic model was developed to simulate contaminant transport from an instantaneous source inside a landfill into heterogeneous, two-dimensional aquifers. Probabilities of detection Pd were calculated for different arrangements of monitoring wells. The frequency of sampling is critical in heterogeneous aquifers with bi-annual or annual sampling decreasing average percentage Pd by almost 20%, and 50%, respectively, relative to that by monthly sampling. It appears that at a minimum sampling should take place twice a year, with the once- in-a-month sampling appearing the optimum choice considering the effort involved and the improvements in detection. In heterogeneous aquifers a large number of monitoring wells sampled infrequently does not perform any better in terms of detection than a lower number of wells sampled regularly.