Modeling feedback driven remediation

Abstract

Over the past two decades, In Situ Chemical Oxidation (ISCO) has proved to be an effective remediation technique to clean up DNAPL (dense non aqueous phase liquid) contaminated sites. ISCO involves the introduction of chemical oxidants into the soil to convert hazardous contaminants into nonhazardous or less toxic compounds. However, efficiency losses of injected oxidants occur due to the presence of natural oxidant demand, as well due to inaccurate targeting of the contamination source zone. In this study it is investigated if feedback driven remediation can improve the efficiency of ISCO remediation. Feedback driven remediation implies the use of indicators to adjust remediation characteristics (such as injection rate, oxidant concentration, location of injection) during the remediation process. A two dimensional MODFLOW/PHT3D-based reactive multi-component transport model has been created to model permanganate based ISCO remediation of a tetrachloroethylene (PCE) contaminated site. Focus has been to find indicators amongst field parameters that could quantify the remediation progress during an ISCO process. Results from this study show that pH and chloride concentration are effective indicators of the remediation effeciency.