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Guidelines for active spreading during in situ chemical oxidation to remediate contaminated groundwater
Citation:
Piscopo, A., R. Neupauer, AND J. Kasprzyk. Guidelines for active spreading during in situ chemical oxidation to remediate contaminated groundwater. Environmental Water Resources Institute Congress, West Palm Beach, FL, May 22 - 26, 2016.
Impact/Purpose:
Contaminated groundwater is often remediated in situ by injecting a treatment chemical into the contaminated aquifer. Because the effectiveness of in situ remediation is limited by the degree of contact between the treatment chemical and plume of contaminant, methods of ‘active spreading’ have been developed to increase contact and accordingly, enhance contaminant degradation. To be effective, any particular active spreading design should reflect the properties of the aquifer and the contaminant. In this research, we optimize active spreading for different combinations of aquifer and contaminant properties to maximize contaminant degradation during in situ remediation.
Description:
The effectiveness of in situ chemical oxidation to remediate contaminated aquifers depends on the extent and duration of contact between the injected treatment chemical and the groundwater contaminant (the reactants). Techniques that inject and extract in the aquifer to ‘actively spread’ the treatment chemical throughout the plume of contaminant have been shown to increase reactant contact, leading to faster rates of contaminant degradation. The design of these injections and extractions should reflect the properties of the aquifer and the contaminant, since the aquifer properties influence the reactant transport (which impacts the extent of reactant contact) and the contaminant properties influence the reaction rate (which is impacted by the duration of reactant contact). In this study, we use a multi-objective evolutionary algorithm to generate designs of injections and extractions that maximize contaminant degradation while minimizing operational costs. We optimize several remediation scenarios characterized by different combinations of aquifer and contaminant properties, including those scenarios known for being challenging to remediate (e.g. rate-limited degradation of contaminant in heterogeneous aquifers with low permeability). The sets of optimized designs are analyzed for all remediation scenarios to develop practical guidelines for active spreading during in situ chemical oxidation at contaminated groundwater sites. The guidelines are tested using a case study, a former manufacturing facility contaminated with chlorinated solvents in California.