Effects of heterogeneity on active spreading strategies to remediate contaminated groundwater

Abstract:

The effectiveness of in situ chemical oxidation (ISCO) to remediate contaminated aquifers is constrained by the amount of contact between the groundwater contaminant and the injected oxidant. Contaminant degradation during ISCO can be enhanced using innovative active spreading strategies, which involve injecting and extracting water at wells in the vicinity of the plume to generate flow fields that spread the contaminant and oxidant plumes in a manner that increases their contact. Because aquifer heterogeneity affects the transport of the contaminant and oxidant during injection and extraction, aquifer heterogeneity also affects the amount of contact and the degree of contaminant degradation achieved using active spreading strategies during ISCO. Consequently, we can improve the effectiveness of active spreading strategies by generating sequences of injection and extraction that take the aquifer heterogeneity into account. In this study, we optimize sequences of injections and extractions to maximize contaminant degradation in aquifers with zonal and spatially-correlated heterogeneity for three contaminant-oxidant pairings with different reaction kinetics. Analysis of the transport and degradation corresponding to the optimal sequences of injection and extraction demonstrates that the underlying aquifer and contaminant properties are reflected by the optimal sequences.