Evaluating the reliability of equilibrium dissolution assumption from residual gasoline in contact with water saturated sands

Lekmine, Greg; Lari, Kaveh Sookhak; Johnston, Colin D.; Bastow, Trevor P.; Rayner, J. C. W.; Davis, Gordon B.

doi:10.1016/j.jconhyd.2016.12.003

Cited by 29 publications

(11 citation statements)

References 51 publications

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“…The proposed model represents an upscaled mass transfer approach that explicitly assumes the rate-limiting dissolution process. Seagren et al [28] and Lekmine et al [29] experimentally demonstrate that the local equilibrium assumption best reproduces the mass transfer from LNAPL to groundwater. On the other hand, Mobile et al [27], Nambi and Powers [30], and Zhu and Sykes [34] indicate that the local equilibrium is unsuitable, and the rate-limiting assumption offers the most realistic simulations.…”

Section: Applications In Real Contamination Casesmentioning

confidence: 98%

“…Teramoto and Chang [15], Mackay et al [23], Huntley and Beckett [24], and Thornton et al [25], among others, demonstrated that the continuous loss of water-soluble compounds leads to continuous depletion of LNAPL in the source zone. Actually, there are a large number of analytical and numerical approaches, varying in scale and complexity, to simulate NAPL dissolution into the aqueous phase [18,[26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Most of these approaches are based on empirical Sherwood-Gilland models that do not consider explicitly the NAPL/water interface area and were exclusively validated by lab-scale experiments.…”

Section: Introductionmentioning

confidence: 99%

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A Screening Model to Predict Entrapped LNAPL Depletion

Teramoto

Chang

2020

Water

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Accidental leakage of hydrocarbons is a common subsurface contamination scenario. Once released, the hydrocarbons migrate until they reach the vicinity of the uppermost portion of the saturated zone, where it accumulates. Whenever the amplitude of the water table fluctuation is high, the light non-aqueous phase liquid (LNAPL) may be completely entrapped in the saturated zone. The entrapped LNAPL, comprised of multicomponent products (e.g., gasoline, jet fuel, diesel), is responsible for the release of benzene, toluene, ethylbenzene, and xylenes (BTEX) into the water, thus generating the dissolved phase plumes of these compounds. In order to estimate the time required for source-zone depletion, we developed an algorithm that calculates the mass loss of BTEX compounds in LNAPL over time. The simulations performed with our algorithm provided results akin to those observed in the field and demonstrated that the depletion rate will be more pronounced in regions with high LNAPL saturation. Further, the LNAPL depletion rate is mostly controlled by flow rate and is less sensible to the biodegradation rate in the aqueous phase.

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Section: Applications In Real Contamination Casesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

A Screening Model to Predict Entrapped LNAPL Depletion

Teramoto

Chang

2020

Water

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“…The source code for the multiphase, multicomponent TMVOC software, which is a FORTRAN 77 integral finite‐difference simulator, is commercially available containing subroutines with simple constitutive relations for fluid relative permeabilities, saturations, and capillary heads. The Commonwealth Scientific and Industrial Research Organization (CSIRO), an Australian Government corporate entity, purchased, modified, and used the multiphase, multicomponent TMVOC to investigate subsurface contamination issues with LNAPL (Sookhak Lari et al , ; Lekmine et al ). To conduct numerical simulations of LNAPL saturation distributions to test the assumption in the Lenhard et al () model, we modified subroutines in TMVOC to incorporate equivalent relative permeability‐saturation‐capillary head constitutive relations in Lenhard et al ().…”

Section: Numerical Model Modificationmentioning

confidence: 99%

Evaluating an Analytical Model to Predict Subsurface LNAPL Distributions and Transmissivity from Current and Historic Fluid Levels in Groundwater Wells: Comparing Results to Numerical Simulations

Lenhard¹,

Lari²,

Rayner³

et al. 2018

Groundwater Monitoring Rem

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This column reviews the general features of PHT3D Version 2, a reactive multicomponent transport model that couples the geochemical modeling software PHREEQC-2 (Parkhurst and Appelo 1999) with three-dimensional groundwater flow and transport simulators MODFLOW-2000 and MT3DMS (Zheng and Wang 1999). The original version of PHT3D was developed by Henning Prommer and Version 2 by Henning Prommer and Vincent Post (Prommer and Post 2010). More detailed information about PHT3D is available at the website http://www.pht3d.org.The review was conducted separately by two reviewers. This column is presented in two parts. PART I by C.A.J. Appelo IntroductionPHT3D is a computer code for general reactive transport calculations, coupling MODFLOW/MT3DMS for transport and PHREEQC for chemical reactions. It was developed by Henning Prommer in the 1990s and has been applied by him and his coworkers to various groundwater problems of practical interest. The resulting publications (http://www.pht3d.org/pht3d public.html) show an impressive applicability of the code and illustrate the underlying understanding of quite complicated interactions (e.g., Prommer and Stuyfzand 2005; Prommer et al. 2008 Prommer et al. , 2009). In the original version, transport is calculated during a time step, an input file is written for PHREEQC for calculating reactions such as ion exchange and precipitation or dissolution of minerals, and these steps are repeated for subsequent time steps until finished. This loose coupling has the advantage that updates of the master programs can be installed without much effort. A disadvantage is that the calculation of the chemical reactions needs to be initialized time and again for each cell in the model, which adds another time-consuming step to calculations that are already computer-intensive. Another disadvantage is that surface complexation reactions need to be calculated first using the water composition from the previous time step and then reacted with the changed water concentrations. This procedure was not implemented in the original version of PHT3D, and surface complexation reactions could not be calculated.Prommer and Post recently released the second version of PHT3D that resolves the shortcomings and works very well. The improvement is owing firstly to the implementation of total-variation-diminishing (TVD) scheme that MT3DMS uses for calculating advective and dispersive transport (Zheng and Wang 1999). Secondly, it is because PHREEQC is now being used for storing the chemical data of the model, including the chemical activities and the composition of surface complexes from the previous time step. In addition, the procedure to transport total oxygen and hydrogen has been adapted from PHAST (PHAST is the 3D reactive transport model developed by Parkhurst et al. 2004, based on HST3D and PHREEQC). This enables the user to obtain the redox state of the solution without having to transport individual redox concentrations of the elements (e.g., C being distributed over carbon-dioxide, C(4), and methane, C...

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“…The effectiveness of a recovery plan in removing LNAPL mass and reducing risk is challenged by the multiphase, multicomponent nature of the fluids involved. Thousands of compounds comprise petroleum products, all having different solubilities, volatilities, sorption potential, and biodegradability (Lang et al 2009;Vasudevan et al 2016;Lekmine et al 2017). Natural phenomena, such as water table fluctuations and natural source zone depletion (NSZD) change LNAPL mass and composition over time; further challenging assumptions of uniformity or constancy of LNAPL mass and characteristics over long periods.…”

Section: Introductionmentioning

confidence: 99%