Estimation of emission from an LNAPL contaminated zone considering groundwater recharge

Peter, Anita; Miles, B.; Teutsch, Georg

doi:10.1007/s00254-007-0978-1

Cited by 13 publications

(8 citation statements)

References 20 publications

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“…Hence, there is continuing simultaneous long‐term partitioning of their components directly from the NAPL into air and water. This contrasts somewhat to the case for dense NAPLs, which penetrate further into the saturated zone with less tendency to spread laterally and vertically in the interval of water table fluctuations (Huntley and Beckett, 2002; Peter et al, 2008). For the case of LNAPLs, partitioning of components to the air phase also has significant potential to modify the LNAPL composition.…”

contrasting

confidence: 63%

Gasoline Multiphase and Multicomponent Partitioning in the Vadose Zone: Dynamics and Risk Longevity

Lari

Johnston

Davis

2016

Vadose Zone Journal

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The multiphase and multicomponent dynamics of the release of light nonaqueous-phase liquid (LNAPL) petroleum hydrocarbons into the subsurface determines the longevity of health and environmental risks. Gasoline is of particular concern, with a wide range of volatilities and solubilities. A Darcyscale, three-dimensional, multiphase and multicomponent approach simulated the effects of the release depth and duration (20-500 d) on the distribution, partitioning, and fate of gasoline components, highlighting major changes in composition and mass during the initial release period. The simulated release occurred at either the ground surface (shallow) or immediately above the water table (deep). The LNAPL mass losses were directly related to the duration of the release. As much as 20% of the initial LNAPL mass was lost from shallow releases mainly as a result of ongoing volatilization of C4-C6 alkanes in the vadose zone over the release period. This was up to 59% higher than the deep releases, mostly resulting from the greater penetration of the deep release below the water table. Over the longer term, the mole fraction of the components within the LNAPL plume from the shallow releases asymptoted to values observed for a weathered gasoline sampled from the field. The mole fraction of toluene increased from 13 to 17% and short-chain alkanes decreased from 49 to 19%. Interestingly, the particular balance of partitioning processes left the benzene mole fraction approximately constant over the time of release and for an appreciable period beyond. This has important implications for long-term risk in the vapor and water phases.

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contrasting

confidence: 63%

Gasoline Multiphase and Multicomponent Partitioning in the Vadose Zone: Dynamics and Risk Longevity

Lari

Johnston

Davis

2016

Vadose Zone Journal

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“…We initially considered using a numerical scheme and accounting for the mass depletion in each cell, but this was deemed too computationally demanding for a screening model. Full details of the analytical equations used to describe multicomponent LNAPL dissolution are reported in the literature (Huntley and Beckett 2002; Peter et al 2008; Yoon et al 2009), so only equations for each flux term from the source zone are summarized here. The unique aspects of our model are combining these equations with a vapor flux term, and accounting for source zone size depletion over time.…”

Section: Szdm For a Multicomponent Lnaplmentioning

confidence: 99%

“…The advective flux term is a function of relative permeability, which depends on NAPL saturation, and the dispersive flux term accounts for NAPL mass transfer to adjacent pore water (Hunt et al 1988). These models have primarily been used to model source zone depletion of single‐component NAPLs (Falta 2003; Yoon et al 2009); for multicomponent NAPLs, source zone depletion has not been considered (Huntley and Beckett 2002; Hansen and Kueper 2007; Peter et al 2008). There is a need to extend these semi‐analytical models to consider multicomponent NAPLs including similar mixtures (e.g., petroleum hydrocarbon and chlorinated organic mixtures) and dissimilar mixtures (e.g., ethanol blended gasoline), and to incorporate other mass removal mechanisms such as volatilization to the overlying soil, particularly, for LNAPLs that are trapped near capillary fringe.…”

Section: Introductionmentioning

confidence: 99%

“…Existing upscaled mass transfer expressions have only been developed for single-component NAPLs; they cannot be easily extended to multicomponent NAPLs because they do not account for the mole fraction of NAPL components in a mixture or potential cosolvent effects. Another approach to describe NAPL mass transfer to groundwater has been to develop simplified analytical or semi-analytical models that assume NAPL is locally in equilibrium with pore water, and dissolution is limited by advection and dispersion of pore water away from the NAPL source (Huntley and Beckett 2002;Falta 2003;Peter et al 2008;Yoon et al 2009). The advective flux term is a function of relative permeability, which depends on NAPL saturation, and the dispersive flux term accounts for NAPL mass transfer to adjacent pore water (Hunt et al 1988).…”

Section: Introductionmentioning

confidence: 99%

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NAPL Source Zone Depletion Model and Its Application to Railroad‐Tank‐Car Spills

et al. 2011

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We developed a new semi-analytical source zone depletion model (SZDM) for multicomponent light nonaqueous phase liquids (LNAPLs) and incorporated this into an existing screening model for estimating cleanup times for chemical spills from railroad tank cars that previously considered only single-component LNAPLs. Results from the SZDM compare favorably to those from a three-dimensional numerical model, and from another semi-analytical model that does not consider source zone depletion. The model was used to evaluate groundwater contamination and cleanup times for four complex mixtures of concern in the railroad industry. Among the petroleum hydrocarbon mixtures considered, the cleanup time of diesel fuel was much longer than E95, gasoline, and crude oil. This is mainly due to the high fraction of low solubility components in diesel fuel. The results demonstrate that the updated screening model with the newly developed SZDM is computationally efficient, and provides valuable comparisons of cleanup times that can be used in assessing the health and financial risk associated with chemical mixture spills from railroad-tank-car accidents.

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“…It currently consists of a source release module, a contaminant transport module and a human health impact assessment module. Both mass release and contaminant transport in groundwater are quantified using transient models that are based on analytical approaches (Sauty, 1980;Huntley and Beckett, 2002;Eberhardt and Grathwohl, 2002;Peter et al, 2008). The existing contamination and its further development can be evaluated on the basis of contaminant mass fluxes, concentrations, and risk indices (carcinogenic/non-carcinogenic).…”

Section: Methodology: Integrated Modeling Frameworkmentioning

confidence: 99%

An integrated model for assessing the risk of TCE groundwater contamination to human receptors and surface water ecosystems

McKnight

Funder

Rasmussen³

et al. 2010

Ecological Engineering

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a b s t r a c tThe practical implementation of the European Water Framework Directive has resulted in an increased focus on the hyporheic zone. In this paper, an integrated model was developed for evaluating the impact of point sources in groundwater on human health and surface water ecosystems. This was accomplished by coupling the system dynamics-based decision support system CARO-PLUS to the aquatic ecosystem model AQUATOX using an analytical volatilization model for the stream. The model was applied to a case study where a trichloroethylene (TCE)-contaminated groundwater plume is discharging to a stream. The TCE source will not be depleted for many decades; however, measured and predicted TCE concentrations in surface water were found to be below human health risk management targets. Volatilization rapidly attenuates TCE concentrations in surface water. Thus, only a 30-m stream reach fails to meet surface water quality criteria. An ecological risk assessment found that the TCE contamination did not impact the stream ecosystem. Uncertainty assessment revealed hydraulic conductivity to be the most important site-specific parameter. These results indicate that contaminant plumes with g L −1 concentrations of TCE entering surface water systems may not pose a significant risk.

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Estimation of emission from an LNAPL contaminated zone considering groundwater recharge

Cited by 13 publications

References 20 publications

Gasoline Multiphase and Multicomponent Partitioning in the Vadose Zone: Dynamics and Risk Longevity

Gasoline Multiphase and Multicomponent Partitioning in the Vadose Zone: Dynamics and Risk Longevity

NAPL Source Zone Depletion Model and Its Application to Railroad‐Tank‐Car Spills

An integrated model for assessing the risk of TCE groundwater contamination to human receptors and surface water ecosystems

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