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Martin Alexander - One of the best experts on this subject based on the ideXlab platform.
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effect of Nonaqueous Phase Liquids on the availability of polycyclic aromatic hydrocarbons in soil for worm uptake and bacterial genotoxicity
Environmental Toxicology and Chemistry, 2003Co-Authors: Antonio Quinonesrivera, Renee R. Alexander, Martin AlexanderAbstract:A study was conducted to determine the effect of Nonaqueous-Phase Liquids (NAPLs) on the bioavailability of benzo[a]pyrene (BaP) in soil. Sentry 19 oil and pristane reduced the availability of BaP for assimilation by the earthworm Eisenia fetida and for mutagenicity in a rifampicin-sensitive strain of Pseudomonas putida. As much as 80% of the compound could be rendered unavailable to the worms or for genotoxicity. Tests with five alkanes and an oil showed that the extent of reduction in genotoxicity of BaP varied with the identity, viscosity, and hydrophobicity of the NAPL. The magnitude of the decline in availability for genotoxicity differed in tests of three soils. Because little or no BaP was lost from the soil, the diminished bioavailability was not the result of a diminished total concentration of the compound. These findings show that exposure to hydrophobic toxicants can be appreciably altered in soils containing NAPLs.
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Effect of Nonaqueous‐Phase Liquids on the availability of polycyclic aromatic hydrocarbons in soil for worm uptake and bacterial genotoxicity
Environmental toxicology and chemistry, 2003Co-Authors: Antonio Quiñones-rivera, Renee R. Alexander, Martin AlexanderAbstract:A study was conducted to determine the effect of Nonaqueous-Phase Liquids (NAPLs) on the bioavailability of benzo[a]pyrene (BaP) in soil. Sentry 19 oil and pristane reduced the availability of BaP for assimilation by the earthworm Eisenia fetida and for mutagenicity in a rifampicin-sensitive strain of Pseudomonas putida. As much as 80% of the compound could be rendered unavailable to the worms or for genotoxicity. Tests with five alkanes and an oil showed that the extent of reduction in genotoxicity of BaP varied with the identity, viscosity, and hydrophobicity of the NAPL. The magnitude of the decline in availability for genotoxicity differed in tests of three soils. Because little or no BaP was lost from the soil, the diminished bioavailability was not the result of a diminished total concentration of the compound. These findings show that exposure to hydrophobic toxicants can be appreciably altered in soils containing NAPLs.
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biodegradability of Nonaqueous Phase Liquids affects the mineralization of phenanthrene in soil because of microbial competition
Environmental Toxicology and Chemistry, 1997Co-Authors: Douglas E Morrison, Martin AlexanderAbstract:A study was conducted to determine the effects of biodegradability of Nonaqueous-Phase Liquids (NAPLs) and microbial competition on the biodegradation in soil of a constituent of the NAPLs. The rates of mineralization of phenanthrene dissolved in 8 mg of 2,2,4,4,6,8,8-heptamethylnonane (HMN), di(2-ethylhexyl) phthalate (DEHP), or pristane per g of soil were faster than the rates when the compound was dissolved in hexadecane or dodecane. Addition of inorganic N and P to the soil increased the mineralization rate in the first two but not the last two NAPLs. N and P addition did not enhance mineralization of phenanthrene when added in 500 {micro}g of hexadecane, pristane, or HMN per g of soil. Hexadecane was rapidly degraded, pristane was slowly metabolized, DEHP was still slower, and HMN was not mineralized in the test period. Mixing the soil stimulated mineralization of phenanthrene dissolved in HMN but not in hexadecane. Mineralization of phenanthrene dissolved in HMN was the same if the gas Phase contained 21%, 2.1%, or traces of O{sub 2}. In contrast, the biodegradation of phenanthrene dissolved in hexadecane, although the same at 21 and 2.1% O{sub 2}, was not observed if traces of O{sub 2} were present. The mineralization was slower inmore » unshaken soil-water mixtures if phenanthrene was added in hexadecane than in HMN or pristane, but the rates with the 3 NAPLs were increased by shaking the suspensions. The authors suggest that the biodegradability of major components of NAPLs and microbial competition for N, P, or O{sub 2} will have a major impact on the rate of transformation of minor constituents of NAPLs.« less
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effect of viscosity of Nonaqueous Phase Liquids napls on biodegradation of napl constituents
Environmental Toxicology and Chemistry, 1996Co-Authors: Irina Birman, Martin AlexanderAbstract:A study was conducted to evaluate the effect of viscosity of Nonaqueous-Phase Liquids (NAPLs) on biodegradation of phenanthrene in soil slurries and to find means to enhance the process in viscous NAPLs. When present in kerosene, diesel fuel, fuel oil, and mixtures of the NAPLs, phenanthrene was biodegraded rapidly. Gasoline alone or in mixtures with other solvents prolonged the acclimation Phase and reduced the rate of mineralization of the hydrocarbon. The rate and extent of biodegradation decreased with increasing viscosity of nontoxic NAPLs. The slow mineralization of phenanthrene initially in 150 Bright stock or crude oils was enhanced by vigorous agitation of soil slurries, addition of a nonionic surfactant and delayed inoculation, or increasing the temperature. The data suggest means for enhanced bioremediation of toxicants present in viscous NAPLs.
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Mitigating Toxicity To Permit Bioremediation of Constituents of Nonaqueous-Phase Liquids
Environmental Science & Technology, 1996Co-Authors: Boakai K. Robertson, Martin AlexanderAbstract:A study was undertaken to find means by which bacteria may degrade phenanthrene initially dissolved in toxic Nonaqueous-Phase Liquids (NAPLs). In shaken cultures containing 5% NAPLs, bacteria readily mineralized phenanthrene initially present in di-n-butyl phthalate or 2,2,4,4,6,8,8-heptamethylnonane but not in 1,2-dichlorobenzene, toluene, 2-chlorotoluene, or 1,2,4-trichlorobenzene. Attempts to acclimate bacteria to tolerate higher concentrations of the first two NAPLs were unsuccessful. However, bacteria sensitive to 1,2-dichlorobenzene and toluene extensively degraded phenanthrene initially present in these toxic NAPLs in a system containing the toxic NAPL, a water Phase, and a separate nontoxic NAPL to lower the toxicant concentration in the aqueous Phase.
Varadarajan Dwarakanath - One of the best experts on this subject based on the ideXlab platform.
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Surfactants: Surfactant Enhanced Aquifer Remediation
Surfactants, 2000Co-Authors: Varadarajan Dwarakanath, Gary A. PopeAbstract:The use of surfactants to remediate groundwater contaminated by Nonaqueous Phase Liquids has been under investigation and field testing since at least the 1980s. Surfactant enhanced aquifer remediation (SEAR) is especially important for dense Nonaqueous Phase Liquids such as chlorinated solvents because they are difficult to remediate and because there are few good alternatives to SEAR to remove these contaminants from groundwater. The technology has continued to improve and recent field demonstrations at superfund sites have shown that under certain conditions very favorable results can be obtained with SEAR. Some of these advances can be attributed to the adaptation of technology developed for surfactant enhanced oil recovery over the past 30 years. The emphasis on Phase behavior for screening and evaluating surfactants is especially noteworthy and important. In this chapter, we first briefly review the Phase behavior of surfactants when mixed with organic Liquids of interest, and then give a detailed example of a study done at the University of Texas to further evaluate surfactant candidates in soil column tests in the laboratory. Introduction The contamination of groundwater by Nonaqueous Phase Liquids (NAPLs) is a cause for concern throughout the world. NAPLs can be classified by their density as those lighter than water (LNAPLs) and denser than water (DNAPLs). NAPLs migrate into aquifers because of gravity and capillary forces and may be trapped in the form of immobile blobs or ganglia or when present in sufficient volume DNAPLs may form pools above aquitards.
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Anionic surfactant remediation of soil columns contaminated by Nonaqueous Phase Liquids
Journal of Contaminant Hydrology, 1999Co-Authors: Varadarajan Dwarakanath, Gary A. Pope, Konstantinos Kostarelos, Doug Shotts, William H. WadeAbstract:Abstract A variety of column experiments have been completed for the purpose of selecting and evaluating suitable surfactants for remediation of Nonaqueous Phase Liquids (NAPLs). The various NAPLs tested in the laboratory experiments were tetrachloroethylene (PCE), trichloroethylene (TCE), jet fuel (JP4) and a dense Nonaqueous Phase liquid from a site at Hill Air Force Base, UT. Both Ottawa sand and Hill field soil were used in these experiments. Surfactant candidates were first screened using Phase behavior experiments and only the best ones were selected for the subsequent column experiments. Surfactants which showed high contaminant solubilization, fast coalescence times, and the absence of liquid crystal Phases and gels during the Phase behavior experiments were tested in soil column experiments. The primary objective of the soil column experiments was to identify surfactants that recovered at least 99% of the contaminant. The secondary objective was to identify surfactants that show low adsorption and little or no loss of hydraulic conductivity during the column experiments. Results demonstrated that up to 99.9% of the contaminants were removed as a result of surfactant flooding of the soil columns. The addition of xanthan gum polymer to the surfactant solution was shown to increase remediation efficiency as a lower volume of surfactant was required for recovering a given volume of NAPL. Based on these experimental results, guidelines for designing highly efficient and robust surfactant floods have been developed and applied to a field demonstration.
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partition coefficients for alcohol tracers between Nonaqueous Phase Liquids and water from unifac solubility method
Advances in Water Resources, 1998Co-Authors: Peng Wang, Gary A. Pope, Varadarajan Dwarakanath, Bruce A Rouse, Kamy SepehrnooriAbstract:Abstract In this work, we have applied a group-contribution activity-coefficient model, UNIFAC, and the solubility of alcohols in water to estimate partition coefficients for alcohol tracers between water and Nonaqueous-Phase Liquids (NAPLs). The effects of temperature and mutual solubility between NAPL and aqueous Phases on the estimation of partition coefficients were also investigated. By comparing the estimated results with experimental partition coefficients for 30 alcohol tracers between 10 NAPLs and water, we found that: i) the UNIFAC-solubility method, in which the UNIFAC model in its infinite-dilution form is applied to the NAPL Phase and the solubility of tracers in water is used for estimation of the activity coefficient in the aqueous Phase, works better than the UNIFAC model; ii) a linear relation between the logarithm of partition coefficients and the logarithm of tracer solubility in water is observed for those tracers having a similar chemical structure (i.e. the same number of branched methyl groups). This can serve as a useful tool for quick selection of the tracers that exhibit the desired partition coefficients; iii) the effect of mutual solubility between NAPL and aqueous Phases can be neglected because such miscibility is very small, usually of the order of 10 −3 mole/mole unit; and iv) temperature variation between 15° and 25°C does not significantly affect partition coefficients.
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New Approach for Estimating Alcohol Partition Coefficients between Nonaqueous Phase Liquids and Water
Environmental Science & Technology, 1998Co-Authors: Varadarajan Dwarakanath, Gary A. PopeAbstract:The partitioning interwell tracer test (PITT) has emerged during the past few years as a useful tool for characterizing aquifers contaminated by Nonaqueous Phase Liquids (NAPLs) and in particular t...
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partitioning tracer test for detection estimation and remediation performance assessment of subsurface Nonaqueous Phase Liquids
Water Resources Research, 1995Co-Authors: Minquan Jin, Mojdeh Delshad, Gary A. Pope, Kamy Sepehrnoori, Varadarajan Dwarakanath, Daene C Mckinney, Charles E Tilburg, Richard E JacksonAbstract:In this paper we present a partitioning interwell tracer test (PITT) technique for the detection, estimation, and remediation performance assessment of the subsurface contaminated by Nonaqueous Phase Liquids (NAPLs). We demonstrate the effectiveness of this technique by examples of experimental and simulation results. The experimental results are from partitioning tracer experiments in columns packed with Ottawa sand. Both the method of moments and inverse modeling techniques for estimating NAPL saturation in the sand packs are demonstrated. In the simulation examples we use UTCHEM, a comprehensive three-dimensional, chemical flood compositional simulator developed at the University of Texas, to simulate a hypothetical two-dimensional aquifer with properties similar to the Borden site contaminated by tetrachloroethylene (PCE), and we show how partitioning interwell tracer tests can be used to estimate the amount of PCE contaminant before remedial action and as the remediation process proceeds. Tracer tests results from different stages of remediation are compared to determine the quantity of PCE removed and the amount remaining. Both the experimental (small-scale) and simulation (large-scale) results demonstrate that PITT can be used as an innovative and effective technique to detect and estimate the amount of residual NAPL and for remediation performance assessment in subsurface formations.
Gary A. Pope - One of the best experts on this subject based on the ideXlab platform.
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Surfactants: Surfactant Enhanced Aquifer Remediation
Surfactants, 2000Co-Authors: Varadarajan Dwarakanath, Gary A. PopeAbstract:The use of surfactants to remediate groundwater contaminated by Nonaqueous Phase Liquids has been under investigation and field testing since at least the 1980s. Surfactant enhanced aquifer remediation (SEAR) is especially important for dense Nonaqueous Phase Liquids such as chlorinated solvents because they are difficult to remediate and because there are few good alternatives to SEAR to remove these contaminants from groundwater. The technology has continued to improve and recent field demonstrations at superfund sites have shown that under certain conditions very favorable results can be obtained with SEAR. Some of these advances can be attributed to the adaptation of technology developed for surfactant enhanced oil recovery over the past 30 years. The emphasis on Phase behavior for screening and evaluating surfactants is especially noteworthy and important. In this chapter, we first briefly review the Phase behavior of surfactants when mixed with organic Liquids of interest, and then give a detailed example of a study done at the University of Texas to further evaluate surfactant candidates in soil column tests in the laboratory. Introduction The contamination of groundwater by Nonaqueous Phase Liquids (NAPLs) is a cause for concern throughout the world. NAPLs can be classified by their density as those lighter than water (LNAPLs) and denser than water (DNAPLs). NAPLs migrate into aquifers because of gravity and capillary forces and may be trapped in the form of immobile blobs or ganglia or when present in sufficient volume DNAPLs may form pools above aquitards.
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Anionic surfactant remediation of soil columns contaminated by Nonaqueous Phase Liquids
Journal of Contaminant Hydrology, 1999Co-Authors: Varadarajan Dwarakanath, Gary A. Pope, Konstantinos Kostarelos, Doug Shotts, William H. WadeAbstract:Abstract A variety of column experiments have been completed for the purpose of selecting and evaluating suitable surfactants for remediation of Nonaqueous Phase Liquids (NAPLs). The various NAPLs tested in the laboratory experiments were tetrachloroethylene (PCE), trichloroethylene (TCE), jet fuel (JP4) and a dense Nonaqueous Phase liquid from a site at Hill Air Force Base, UT. Both Ottawa sand and Hill field soil were used in these experiments. Surfactant candidates were first screened using Phase behavior experiments and only the best ones were selected for the subsequent column experiments. Surfactants which showed high contaminant solubilization, fast coalescence times, and the absence of liquid crystal Phases and gels during the Phase behavior experiments were tested in soil column experiments. The primary objective of the soil column experiments was to identify surfactants that recovered at least 99% of the contaminant. The secondary objective was to identify surfactants that show low adsorption and little or no loss of hydraulic conductivity during the column experiments. Results demonstrated that up to 99.9% of the contaminants were removed as a result of surfactant flooding of the soil columns. The addition of xanthan gum polymer to the surfactant solution was shown to increase remediation efficiency as a lower volume of surfactant was required for recovering a given volume of NAPL. Based on these experimental results, guidelines for designing highly efficient and robust surfactant floods have been developed and applied to a field demonstration.
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partition coefficients for alcohol tracers between Nonaqueous Phase Liquids and water from unifac solubility method
Advances in Water Resources, 1998Co-Authors: Peng Wang, Gary A. Pope, Varadarajan Dwarakanath, Bruce A Rouse, Kamy SepehrnooriAbstract:Abstract In this work, we have applied a group-contribution activity-coefficient model, UNIFAC, and the solubility of alcohols in water to estimate partition coefficients for alcohol tracers between water and Nonaqueous-Phase Liquids (NAPLs). The effects of temperature and mutual solubility between NAPL and aqueous Phases on the estimation of partition coefficients were also investigated. By comparing the estimated results with experimental partition coefficients for 30 alcohol tracers between 10 NAPLs and water, we found that: i) the UNIFAC-solubility method, in which the UNIFAC model in its infinite-dilution form is applied to the NAPL Phase and the solubility of tracers in water is used for estimation of the activity coefficient in the aqueous Phase, works better than the UNIFAC model; ii) a linear relation between the logarithm of partition coefficients and the logarithm of tracer solubility in water is observed for those tracers having a similar chemical structure (i.e. the same number of branched methyl groups). This can serve as a useful tool for quick selection of the tracers that exhibit the desired partition coefficients; iii) the effect of mutual solubility between NAPL and aqueous Phases can be neglected because such miscibility is very small, usually of the order of 10 −3 mole/mole unit; and iv) temperature variation between 15° and 25°C does not significantly affect partition coefficients.
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New Approach for Estimating Alcohol Partition Coefficients between Nonaqueous Phase Liquids and Water
Environmental Science & Technology, 1998Co-Authors: Varadarajan Dwarakanath, Gary A. PopeAbstract:The partitioning interwell tracer test (PITT) has emerged during the past few years as a useful tool for characterizing aquifers contaminated by Nonaqueous Phase Liquids (NAPLs) and in particular t...
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partitioning tracer test for detection estimation and remediation performance assessment of subsurface Nonaqueous Phase Liquids
Water Resources Research, 1995Co-Authors: Minquan Jin, Mojdeh Delshad, Gary A. Pope, Kamy Sepehrnoori, Varadarajan Dwarakanath, Daene C Mckinney, Charles E Tilburg, Richard E JacksonAbstract:In this paper we present a partitioning interwell tracer test (PITT) technique for the detection, estimation, and remediation performance assessment of the subsurface contaminated by Nonaqueous Phase Liquids (NAPLs). We demonstrate the effectiveness of this technique by examples of experimental and simulation results. The experimental results are from partitioning tracer experiments in columns packed with Ottawa sand. Both the method of moments and inverse modeling techniques for estimating NAPL saturation in the sand packs are demonstrated. In the simulation examples we use UTCHEM, a comprehensive three-dimensional, chemical flood compositional simulator developed at the University of Texas, to simulate a hypothetical two-dimensional aquifer with properties similar to the Borden site contaminated by tetrachloroethylene (PCE), and we show how partitioning interwell tracer tests can be used to estimate the amount of PCE contaminant before remedial action and as the remediation process proceeds. Tracer tests results from different stages of remediation are compared to determine the quantity of PCE removed and the amount remaining. Both the experimental (small-scale) and simulation (large-scale) results demonstrate that PITT can be used as an innovative and effective technique to detect and estimate the amount of residual NAPL and for remediation performance assessment in subsurface formations.
Cass T. Miller - One of the best experts on this subject based on the ideXlab platform.
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dissolution fingering during the solubilization of Nonaqueous Phase Liquids in saturated porous media 1 model predictions
Water Resources Research, 1996Co-Authors: Paul T Imhoff, Cass T. MillerAbstract:The dissolution of Nonaqueous Phase Liquids (NAPLs) trapped at residual saturation is an important problem at many contaminated groundwater sites. It is well known that NAPL ganglia trapped within the pore space reduce the permeability of the medium to aqueous Phase flow. When fluid flow is imposed on such a system, the aqueous Phase may interact with the dissolution-induced permeability changes, leading to fingered patterns. This mechanism is very similar to that of mineral dissolution instabilities, which are a particular example of reactive infiltration instabilities. Extending that literature, we present a nonlinear model describing the dissolution of NAPL ganglia and perform a linear stability analysis of the resultant moving free boundary problem, demonstrating that instabilities may develop from a planar dissolution front. Predicted finger wavelengths are a function of both residual NAPL saturation and the imposed aqueous Phase flow rate; they range from centimeters to meters. Experimental observations of dissolution fingering are presented in a companion paper [Imhoff et al., this issue] and are compared with predictions from this model. Dissolution fingering may affect the solubilization of NAPL ganglia in natural environments and in experimental studies of NAPL dissolution intended to quantify mass transfer rates.
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cosolvent enhanced remediation of residual dense Nonaqueous Phase Liquids experimental investigation
Environmental Science & Technology, 1995Co-Authors: Paul T Imhoff, Simon N Gleyzer, John F Mcbride, Laura A Vancho, Itaru Okuda, Cass T. MillerAbstract:The removal of denser than water Nonaqueous Phase Liquids (DNAPLs) trapped at residual saturation is an important problem at many contaminated groundwater sites. Because pump-and-treat technologies have been ineffective in removing DNAPLs, alternative strategies have been suggested, one of which is enhancing the mobilization and dissolution of DNAPLs by flushing with a cosolvent. Tetrachloroethylene (PCE)/methanol/water systems were studied to evaluate the effect of methanol on the remediation of PCE-contaminated porous media. Experimental measurements of interfacial tension, equilibrium Phase composition, and Phase density at various methanol/water fractions were combined with other published properties to characterize these systems. In methanol flushing experiments, PCE mobilization, non-equilibrium PCE dissolution, and flow bypassing were all observed. The results demonstrate that (a) small-scale heterogeneities may lead to locally high residual DNAPL saturations that are more easily mobilized than DNAPL residuals in homogeneous media ; (b) mass transfer rate coefficients for PCE/methanol/water systems can be predicted to within 30% using an existing correlation developed for systems with similar NAPL emplacement procedures ; and (c) flow bypassing, due to nonuniform distributions of DNAPL residual or dissolution fingering, can occur in even small-scale experiments.
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the influence of porous medium characteristics and measurement scale on pore scale distributions of residual Nonaqueous Phase Liquids
Journal of Contaminant Hydrology, 1992Co-Authors: Alex S. Mayer, Cass T. MillerAbstract:Abstract A series of experiments was performed to characterize the morphologic distribution of Nonaqueous-Phase Liquids (NAPL's) at residual saturation, as a function of porous medium size. Morphologic characterization of NAPL distributions was accomplished using a novel in situ polymerization technique. The porous medium consisted of glass beads. Blob length, volume and shape characteristics were determined for each experiment, and pore size distributions were determined through capillary pressure-saturation experiments. Both the blob lenght and pore size distributions were fitted to a van Genuchten function. Both blob lenght and pressure-saturation data could be scaled with the same averaged porous medium characteristics. The blob length distributions were found to be wider than the pore size distributions. Estimates of representative elementary volumes (REV's) were generated from statistical analysis using a van Genuchten cumulative frequency distribution function for blob lenght and an empirical function for blob volume as a function of blob length. Simulations were also performed using a Monte Carlo method. The size of the REV needed for a given level of prediction of the residual saturation level was found to increase as a function of mean particle volume for the similar used in this study. Extrapolation of the REV analysis suggests that the size of an REV will increase rapidly as uniformity of the medium decreases. If this extrapolation holds true, significant uncertainty would exist in most determination of residual saturation for poorly sorted media that have been reported to date.
Kamy Sepehrnoori - One of the best experts on this subject based on the ideXlab platform.
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partition coefficients for alcohol tracers between Nonaqueous Phase Liquids and water from unifac solubility method
Advances in Water Resources, 1998Co-Authors: Peng Wang, Gary A. Pope, Varadarajan Dwarakanath, Bruce A Rouse, Kamy SepehrnooriAbstract:Abstract In this work, we have applied a group-contribution activity-coefficient model, UNIFAC, and the solubility of alcohols in water to estimate partition coefficients for alcohol tracers between water and Nonaqueous-Phase Liquids (NAPLs). The effects of temperature and mutual solubility between NAPL and aqueous Phases on the estimation of partition coefficients were also investigated. By comparing the estimated results with experimental partition coefficients for 30 alcohol tracers between 10 NAPLs and water, we found that: i) the UNIFAC-solubility method, in which the UNIFAC model in its infinite-dilution form is applied to the NAPL Phase and the solubility of tracers in water is used for estimation of the activity coefficient in the aqueous Phase, works better than the UNIFAC model; ii) a linear relation between the logarithm of partition coefficients and the logarithm of tracer solubility in water is observed for those tracers having a similar chemical structure (i.e. the same number of branched methyl groups). This can serve as a useful tool for quick selection of the tracers that exhibit the desired partition coefficients; iii) the effect of mutual solubility between NAPL and aqueous Phases can be neglected because such miscibility is very small, usually of the order of 10 −3 mole/mole unit; and iv) temperature variation between 15° and 25°C does not significantly affect partition coefficients.
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partitioning tracer test for detection estimation and remediation performance assessment of subsurface Nonaqueous Phase Liquids
Water Resources Research, 1995Co-Authors: Minquan Jin, Mojdeh Delshad, Gary A. Pope, Kamy Sepehrnoori, Varadarajan Dwarakanath, Daene C Mckinney, Charles E Tilburg, Richard E JacksonAbstract:In this paper we present a partitioning interwell tracer test (PITT) technique for the detection, estimation, and remediation performance assessment of the subsurface contaminated by Nonaqueous Phase Liquids (NAPLs). We demonstrate the effectiveness of this technique by examples of experimental and simulation results. The experimental results are from partitioning tracer experiments in columns packed with Ottawa sand. Both the method of moments and inverse modeling techniques for estimating NAPL saturation in the sand packs are demonstrated. In the simulation examples we use UTCHEM, a comprehensive three-dimensional, chemical flood compositional simulator developed at the University of Texas, to simulate a hypothetical two-dimensional aquifer with properties similar to the Borden site contaminated by tetrachloroethylene (PCE), and we show how partitioning interwell tracer tests can be used to estimate the amount of PCE contaminant before remedial action and as the remediation process proceeds. Tracer tests results from different stages of remediation are compared to determine the quantity of PCE removed and the amount remaining. Both the experimental (small-scale) and simulation (large-scale) results demonstrate that PITT can be used as an innovative and effective technique to detect and estimate the amount of residual NAPL and for remediation performance assessment in subsurface formations.