Thermal Enhancement of In Situ Chemical Oxidation (ISCO) for Remediation of Groundwater Impacted by Chlorinated Solvents

Sean Bryck, Michael R. West, Bernard H. Kueper

In the proceedings of: GeoMontréal 2013: 66th Canadian Geotechnical Conference; 11th joint with IAH-CNC

Session: Contaminated Sites and Remediation I

ABSTRACT: This study focuses on the effects of elevated subsurface temperatures on the application of in-situ chemical oxidation (ISCO) to remediate contaminated groundwater impacted by dense, non-aqueous phase liquids (DNAPLs) such as trichloroethylene (TCE) and tetrachloroethylene (PCE). The numerical model DNAPL3D-RX (West and Kueper, 2012), was utilized to simulate the effects of higher temperatures (20 to 80ûC) on the reaction mechanisms and processes involved with permanganate ISCO treatment. This model incorporates permanganate-TCE/PCE oxidation kinetics as well as subsurface processes that inhibit permanganate ISCO operation. Oxidant consumption by organic aquifer material (OAM) and subsurface pore clogging (i.e., permeability reduction) due to manganese oxide (rind) formation were accounted for in all of the ISCO simulations (similar to the work conducted by West and Kueper, 2012). Each model simulation incorporates the initial base case permeability and DNAPL saturation fields employed by West and Kueper (2012); both fields are illustrated in Figure 1 below. The initial permeability field is representative of a heterogeneous medium sand-to-silt porous medium. The initial DNAPL saturation field has already undergone DNAPL release, migration, redistribution and hydraulic displacement events (Richards et al., 2012); the latter event maximized residual saturations and minimized pooled saturations in order to increase DNAPL-water surface area prior to ISCO treatment. Prior to the start of each simulation, there is no dissolution of the saturation field; plume formation has not yet occurred. A theoretical stoichiometric quantity of permanganate oxidant was injected into the subsurface domain (via an upgradient injection boundary representative of a network of closely spaced wells) in each ISCO simulation in order to satisfy both contaminant and natural oxidant demands. Injection was terminated in every ISCO simulation once this oxidant amount was attained; past this point, only natural dissolution was occurring within these simulations. Figure 1: Initial base case DNAPL saturation and permeability fields utilized by West and Kueper (2012). SNW represents the non-wetting phase (DNAPL) saturation as a percentage of pore space, k represents the intrinsic permeability, hrepresents the hydraulic gradient and v the average linear groundwater velocity.

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Cite this article:
Sean Bryck; Michael R. West; Bernard H. Kueper (2013) Thermal Enhancement of In Situ Chemical Oxidation (ISCO) for Remediation of Groundwater Impacted by Chlorinated Solvents in GEO2013. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoMon2013Paper239,author = Sean Bryck; Michael R. West; Bernard H. Kueper,title = Thermal Enhancement of In Situ Chemical Oxidation (ISCO) for Remediation of Groundwater Impacted by Chlorinated Solvents,year = 2013}