A theoretical investigation of factors affecting the gas phase transport of evaporating organic l... more A theoretical investigation of factors affecting the gas phase transport of evaporating organic liquids in the unsaturated zone is presented. Estimates of density‐driven advective gas flow using a simple analytic expression indicate that significant advective gas flow will result from the evaporation of volatile liquids in soils having a high permeability. Numerical simulations using a two‐dimensional cylindrical geometry and including the effects of phase partitioning between the solid, gas, water, and organic liquid phases show that mass transfer due to density‐driven flow may dominate the gas phase transport of some organic chemical vapors in the unsaturated zone.
A dual-domain approach is developed for calculating the advective and dispersive mass flux of che... more A dual-domain approach is developed for calculating the advective and dispersive mass flux of chemical leaving one or more sub-grid-block-scale DNAPL pool(s) in an integral finite difference numerical simulation. The contaminated zone in a simulation is divided into two fractions: one that contains DNAPL pools and one in which DNAPL is not present. With a dual-permeability formulation the two regions
Field evidence from underground storage tank sites where leaded gasoline leaked indicates the lea... more Field evidence from underground storage tank sites where leaded gasoline leaked indicates the lead scavengers 1,2-dibromoethane (ethylene dibromide, or EDB) and 1,2-dichloroethane (1,2-DCA) may be present in groundwater at levels that pose unacceptable risk. These ...
Field evidence from underground storage tank sites where leaded gasoline leaked indicates the lea... more Field evidence from underground storage tank sites where leaded gasoline leaked indicates the lead scavengers 1,2-dibromoethane (ethylene dibromide, or EDB) and 1,2-dichloroethane (1,2-DCA) may be present in groundwater at levels that pose unacceptable risk. These ...
Thermal methods are promising for remediating fractured geologic media contaminated with volatile... more Thermal methods are promising for remediating fractured geologic media contaminated with volatile organic compounds, and the success of this process depends on the coupled heat transfer, multiphase flow, and thermodynamics. This study analyzed field-scale removal of trichloroethylene (TCE) and heat transfer behavior in boiling fractured geologic media using the multiple interacting continua method. This method can resolve local gradients in the matrix and is less computationally demanding than alternative methods like discrete fracture-matrix models. A 2D axisymmetric model was used to simulate a single element of symmetry in a repeated pattern of extraction wells inside a large heated zone and evaluate effects of parameter sensitivity on contaminant recovery. The results showed that the removal of TCE increased with matrix permeability, and the removal rate was more sensitive to matrix permeability than any other parameter. Increasing fracture density promoted TCE removal, especial...
Proceedings of SPE/DOE Symposium on Improved Oil Recovery, 2006
... Thus a wellbore pressure of atmospheric was assigned to the top element of the producing well... more ... Thus a wellbore pressure of atmospheric was assigned to the top element of the producing wells. ... designated as a very low permeable layer with a no flow boundary below it. The top two layers of the model also have very low permeabilities, with a no flow boundary above them. ...
Abstract. A nonisothermal compositional model has been developed for examining nonaqueous phase l... more Abstract. A nonisothermal compositional model has been developed for examining nonaqueous phase liquid contamination and remediation scenarios. The governing mass balance equations and constraints have been presented, and various type of ...
Skip to main content. AGU Home. FastFind » Lastname: doi:10.1029/ Year: -Select Journal-... Ronal... more Skip to main content. AGU Home. FastFind » Lastname: doi:10.1029/ Year: -Select Journal-... Ronald W. Falta. Environmental Engineering and Science Department, Clemson University, Clemson, South Carolina. Cindy M. Lee. ...
We investigated, using model simulations, the changes occurring in the distribution of dense non-... more We investigated, using model simulations, the changes occurring in the distribution of dense non-aqueous phase liquid (DNAPL) mass (Sn) within the source zone during depletion through dissolution, and the resulting changes in the contaminant flux distribution (J) at the source control plane (CP). Two numerical codes (ISCO3D and T2VOC) were used to simulate selected scenarios of DNAPL dissolution and transport in three-dimensional, heterogeneous, spatially correlated, random permeability fields with emplaced sources. Data from the model simulations were interpreted based on population statistics (mean, standard deviation, coefficient of variation) and spatial statistics (centroid, second moments, variograms). The mean and standard deviation of the Sn and J distributions decreased with source mass depletion by dissolution. The decrease in mean and standard deviation was proportional for the J distribution resulting in a constant coefficient of variation (CV), while for the Sn distribution, the mean decreased faster than the standard deviation. The spatial distributions exhibited similar behavior as the population distribution, i.e., the CP flux distribution was more stable (defined by temporally constant second moments and range of variograms) than the Sn distribution. These observations appeared to be independent of the heterogeneity of the permeability (k) field (variance of the log permeability field=1 and 2.45), correlation structure (positive vs. negative correlation between the k and Sn domains) and the DNAPL dissolution model (equilibrium vs. rate-limited), for the cases studied. Analysis of data from a flux monitoring field study (Hill Air Force Base, Utah) at a DNAPL source CP before and after source remediation also revealed temporal invariance of the contaminant flux distribution. These modeling and field observations suggest that the temporal evolution of the contaminant flux distribution can be estimated if the initial distribution is known. However, the findings are preliminary and broader implications to sampling strategies for remediation performance assessment need to be evaluated in additional modeling and experimental studies.
A theoretical investigation of factors affecting the gas phase transport of evaporating organic l... more A theoretical investigation of factors affecting the gas phase transport of evaporating organic liquids in the unsaturated zone is presented. Estimates of density-driven advective gas flow using a simple analytic expression indicate that significant advective gas flow will result ...
A theoretical investigation of factors affecting the gas phase transport of evaporating organic l... more A theoretical investigation of factors affecting the gas phase transport of evaporating organic liquids in the unsaturated zone is presented. Estimates of density‐driven advective gas flow using a simple analytic expression indicate that significant advective gas flow will result from the evaporation of volatile liquids in soils having a high permeability. Numerical simulations using a two‐dimensional cylindrical geometry and including the effects of phase partitioning between the solid, gas, water, and organic liquid phases show that mass transfer due to density‐driven flow may dominate the gas phase transport of some organic chemical vapors in the unsaturated zone.
A dual-domain approach is developed for calculating the advective and dispersive mass flux of che... more A dual-domain approach is developed for calculating the advective and dispersive mass flux of chemical leaving one or more sub-grid-block-scale DNAPL pool(s) in an integral finite difference numerical simulation. The contaminated zone in a simulation is divided into two fractions: one that contains DNAPL pools and one in which DNAPL is not present. With a dual-permeability formulation the two regions
Field evidence from underground storage tank sites where leaded gasoline leaked indicates the lea... more Field evidence from underground storage tank sites where leaded gasoline leaked indicates the lead scavengers 1,2-dibromoethane (ethylene dibromide, or EDB) and 1,2-dichloroethane (1,2-DCA) may be present in groundwater at levels that pose unacceptable risk. These ...
Field evidence from underground storage tank sites where leaded gasoline leaked indicates the lea... more Field evidence from underground storage tank sites where leaded gasoline leaked indicates the lead scavengers 1,2-dibromoethane (ethylene dibromide, or EDB) and 1,2-dichloroethane (1,2-DCA) may be present in groundwater at levels that pose unacceptable risk. These ...
Thermal methods are promising for remediating fractured geologic media contaminated with volatile... more Thermal methods are promising for remediating fractured geologic media contaminated with volatile organic compounds, and the success of this process depends on the coupled heat transfer, multiphase flow, and thermodynamics. This study analyzed field-scale removal of trichloroethylene (TCE) and heat transfer behavior in boiling fractured geologic media using the multiple interacting continua method. This method can resolve local gradients in the matrix and is less computationally demanding than alternative methods like discrete fracture-matrix models. A 2D axisymmetric model was used to simulate a single element of symmetry in a repeated pattern of extraction wells inside a large heated zone and evaluate effects of parameter sensitivity on contaminant recovery. The results showed that the removal of TCE increased with matrix permeability, and the removal rate was more sensitive to matrix permeability than any other parameter. Increasing fracture density promoted TCE removal, especial...
Proceedings of SPE/DOE Symposium on Improved Oil Recovery, 2006
... Thus a wellbore pressure of atmospheric was assigned to the top element of the producing well... more ... Thus a wellbore pressure of atmospheric was assigned to the top element of the producing wells. ... designated as a very low permeable layer with a no flow boundary below it. The top two layers of the model also have very low permeabilities, with a no flow boundary above them. ...
Abstract. A nonisothermal compositional model has been developed for examining nonaqueous phase l... more Abstract. A nonisothermal compositional model has been developed for examining nonaqueous phase liquid contamination and remediation scenarios. The governing mass balance equations and constraints have been presented, and various type of ...
Skip to main content. AGU Home. FastFind » Lastname: doi:10.1029/ Year: -Select Journal-... Ronal... more Skip to main content. AGU Home. FastFind » Lastname: doi:10.1029/ Year: -Select Journal-... Ronald W. Falta. Environmental Engineering and Science Department, Clemson University, Clemson, South Carolina. Cindy M. Lee. ...
We investigated, using model simulations, the changes occurring in the distribution of dense non-... more We investigated, using model simulations, the changes occurring in the distribution of dense non-aqueous phase liquid (DNAPL) mass (Sn) within the source zone during depletion through dissolution, and the resulting changes in the contaminant flux distribution (J) at the source control plane (CP). Two numerical codes (ISCO3D and T2VOC) were used to simulate selected scenarios of DNAPL dissolution and transport in three-dimensional, heterogeneous, spatially correlated, random permeability fields with emplaced sources. Data from the model simulations were interpreted based on population statistics (mean, standard deviation, coefficient of variation) and spatial statistics (centroid, second moments, variograms). The mean and standard deviation of the Sn and J distributions decreased with source mass depletion by dissolution. The decrease in mean and standard deviation was proportional for the J distribution resulting in a constant coefficient of variation (CV), while for the Sn distribution, the mean decreased faster than the standard deviation. The spatial distributions exhibited similar behavior as the population distribution, i.e., the CP flux distribution was more stable (defined by temporally constant second moments and range of variograms) than the Sn distribution. These observations appeared to be independent of the heterogeneity of the permeability (k) field (variance of the log permeability field=1 and 2.45), correlation structure (positive vs. negative correlation between the k and Sn domains) and the DNAPL dissolution model (equilibrium vs. rate-limited), for the cases studied. Analysis of data from a flux monitoring field study (Hill Air Force Base, Utah) at a DNAPL source CP before and after source remediation also revealed temporal invariance of the contaminant flux distribution. These modeling and field observations suggest that the temporal evolution of the contaminant flux distribution can be estimated if the initial distribution is known. However, the findings are preliminary and broader implications to sampling strategies for remediation performance assessment need to be evaluated in additional modeling and experimental studies.
A theoretical investigation of factors affecting the gas phase transport of evaporating organic l... more A theoretical investigation of factors affecting the gas phase transport of evaporating organic liquids in the unsaturated zone is presented. Estimates of density-driven advective gas flow using a simple analytic expression indicate that significant advective gas flow will result ...
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