Upscaled modeling of complex DNAPL dissolution

Stewart, Lloyd; Chambon, Julie Claire Claudia; Widdowson, Mark A.; Kavanaugh, Michael C.

doi:10.1016/j.jconhyd.2021.103920

Cited by 8 publications

(35 citation statements)

References 37 publications

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“…This test would induce breakthrough of nonequilibrium concentrations through forced hydraulic gradients and flushing in the source zone, generating monitoring profiles suitable for the inverse modeling techniques applied in this study. Conversely, situations where available MD data is uncertain with respect to source depletion trends, upscaled, dual‐domain models with explicit mass transfer parameters constrained by direct site characterization, provide a viable alternative to estimate source zone depletion behavior (Stewart et al., 2022). Furthermore, sites where natural attenuation mechanisms are significant may benefit from several monitoring transects along the flow direction, differentiating attenuation capacity from NAPL dissolution rates for decision‐support modeling (McMillan et al., 2018; Rivett et al., 2014).…”

Section: Resultsmentioning

confidence: 99%

Numerical Modeling and Data‐Worth Analysis for Characterizing the Architecture and Dissolution Rates of a Multicomponent DNAPL Source

Estrada

Widdowson

Stewart

2023

Water Resources Research

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Remediation and long-term dissipation of contaminant source zones comprised of dense nonaqueous phase liquids (DNAPLs) in the subsurface encompasses technical challenges related to uncertainty of DNAPL spatial distribution and dissolution rates (Kueper et al., 2014;Mayer & Hassanizadeh, 2005; NRC, 2005). Entrapped DNAPL mass and saturation distributions in the porous medium, referred to as the source zone "architecture", are key parameters controlling source-zone longevity and depletion behavior (Dekker & Abriola, 2000;. Typical multistage and nonmonotonic depletion profiles observed in monitoring data reflect the gradual dissolution of NAPL accumulations with characteristic saturations (Brusseau et al., 2013;

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Section: Resultsmentioning

confidence: 99%

Numerical Modeling and Data‐Worth Analysis for Characterizing the Architecture and Dissolution Rates of a Multicomponent DNAPL Source

Estrada

Widdowson

Stewart

2023

Water Resources Research

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“…Furthermore, the proposed framework is not specific to the PB upscaled model, as the CVAE‐based inversion method can be combined with any upscaled DNAPL dissolution models that allows for SZ parameters to be updated with time. Alternatively, one may use predictive upscaled models (e.g., Guo et al., 2020; Stewart et al., 2022) within the proposed framework, in which only the SZ metrics at initial time are required to predict the future state of mass discharge. Such prediction approaches have the advantage of fewer data required, and the disadvantage that data‐informed metrics are not used to update the DNAPL dissolution model.…”

Section: Discussionmentioning

confidence: 99%

Integration of Deep Learning‐Based Inversion and Upscaled Mass‐Transfer Model for DNAPL Mass‐Discharge Estimation and Uncertainty Assessment

Kang

Kokkinaki

Shi

et al. 2022

Water Resources Research

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Dense nonaqueous phase liquid (DNAPL) contaminants present a challenging groundwater issue that has gained increasing attention worldwide since the 1980s (National Research Council, 2013). Once released to the subsurface, DNAPLs can penetrate through the groundwater table and appear as immobile liquids relative to groundwater flow, due to their physicochemical properties, that is, high density, low solubility, and low interfacial tension (Pankow and Cherry, 1996). Driven by gravity and capillary forces, a fraction of the DNAPL may become trapped within the soil pores as discontinuous ganglia, while another fraction may pool on locally low-permeability media (e.g., clay lenses) (Dekker & Abriola, 2000;Lenhard et al., 1989). These DNAPL source zones (SZ) are long-term sources that slowly release dissolved contaminant downstream until they are depleted by dissolution due to natural or imposed concentration gradients. During this time, the resulting plumes of dissolved DNAPL could pose a significant risk to humans and ecosystems. Mass discharge from DNAPL SZs is often used a remediation metrics to determine when the risk is such that warranties active remediation versus more passive approaches (National Research Council, 2013). A significant and sustained reduction in mass discharge can be used to justify less intrusive and more cost-efficient remediation. Overall, accurate prediction of DNAPL mass discharge and source longevity play a critical role in all aspects of site stewardship, from remedial program design to remedial performance assessment (Abriola et al., 2012;Kavanaugh et al., 2003).In practice, the contaminant mass discharge at a location of interest downstream is typically obtained by aggregating local measurements of concentrations and flow rates (or the local mass flux) from multilevel sampling

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“…Mass discharge is a key metric for evaluating the effectiveness of source zone control to diminish risks through remedial efforts. Recognizing the need for practical tools to estimate mass discharge under varying site and remedial conditions, a spreadsheet tool was recently developed for estimating mass discharge from a NAPL source zone using the VA model (Stewart et al 2022).…”

Section: Volume‐averaged Modeling Of Napl Dissolutionmentioning

confidence: 99%

“…The VA model was shown to provide accurate mass discharge predictions from NAPL sources with limited information. The framework allows multiple mass accumulations of varying architecture, that is, ganglia and pools, to yield complex, multi‐stage source zone discharge data without detailed numerical transport modeling (Stewart et al 2022). Importantly, the VA model can rapidly generate more reasonable estimates for NAPL source lifespans compared to relying on estimates using models that assume NAPL partitioning equilibrium.…”

Section: Volume‐averaged Modeling Of Napl Dissolutionmentioning

confidence: 99%

“…Recently, a practical and cost‐effective method has been established to assess remediation at NAPL sites based on a volume‐averaged (VA) model with site‐ and technology‐specific NAPL dissolution rates (Stewart et al 2022). The VA approach: (1) incorporates core mass transfer processes with mass balances; (2) avoids the intensive input parameter requirements of numerical simulators; and (3) bypasses the requirement of a calibrated numerical groundwater flow and transport model.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of Complex, Multi‐Component NAPL Remediation for Decision Support

Stewart

Nyman

Estrada

et al. 2023

Groundwater Monitoring Rem

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In situ remediation of nonaqueous phase liquid (NAPL)-impacted sites is difficult and costly. Even with enhancements (e.g., chemical and thermal) and partial NAPL recovery, mass transfer constraints associated with partitioning from residual NAPL typically control the depletion rate of sources and attainment of cleanup goals. Practical methodologies are needed to support strategic evaluation, planning, and implementation of cost-effective remedial approaches that are considered protective. A modeling system averaging over the NAPL-impacted saturated soil volume was developed and demonstrated at the former Williams Air Force Base. The system combines upscaled, physically based mass transfer coefficients for multi-component NAPL dissolution with theoretical enhancements specific to multiple remediation processes. Dissolution increases in the presence of aqueous phase reactions, according to first-or second-order kinetics, by increasing concentration gradients. Slow biological processes are considered first order in modeling natural attenuation and enhanced biological degradation. Fast reactions associated with chemical oxidation are considered second order. These enhancement models are equally applicable to numerical simulations of NAPL remediation. Pump and treat enhances dissolution in proportion to increases in the characteristic velocity associated with dissolution. The demonstration yielded realistic predictions, with greater certainty, for outcomes from of multiple technologies intended to reduce remedial timeframes and life cycle costs. The enhanced dissolution modeling provides a site-specific, quantitative assessment of changes in NAPL source discharge concentration and mass discharge over time for various remedial options that is equivalent to assessments from complex numerical transport models, given typical input data limitations.

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Upscaled modeling of complex DNAPL dissolution

Cited by 8 publications

References 37 publications

Numerical Modeling and Data‐Worth Analysis for Characterizing the Architecture and Dissolution Rates of a Multicomponent DNAPL Source

Numerical Modeling and Data‐Worth Analysis for Characterizing the Architecture and Dissolution Rates of a Multicomponent DNAPL Source

Integration of Deep Learning‐Based Inversion and Upscaled Mass‐Transfer Model for DNAPL Mass‐Discharge Estimation and Uncertainty Assessment

Modeling of Complex, Multi‐Component NAPL Remediation for Decision Support

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