Density-driven Transport of Volatile Organic Compounds and its Impact on Contaminated Groundwater Plume Evolution

Jang, Wook; Aral, Mustafa M.

doi:10.1007/s11242-006-9029-8

Cited by 35 publications

(15 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Flow velocities of gas and water phases, shown in Eq. 7, play an important role in determining the migration of contaminants within each phase (Jang and Aral 2006). In order to improve the accuracy and overcome discontinuity problems in calculating flow velocities, a method for globally continuous Darcy velocity, proposed by Yeh (1981), is implemented.…”

Section: Methodsmentioning

confidence: 99%

“…To reduce the numerical difficulty due to the coupling and non-linearity in multiphase flow and transport equations, a sequentially-iterative scheme is applied. This iterative scheme solves a set of decoupled system equations (Diersch and Kolditz 2002;Jang and Aral 2006): The equations are consecutively solved, and the solution procedures are repeated until all solutions are converged below a specified tolerance level. Convergence criteria used here are (Lehmann and Ackerer 1998):…”

Section: Methodsmentioning

confidence: 99%

“…From mass balance equations and Darcy's law, the governing equation of multiphase flow can be given as (Bear 1972;Jang and Aral 2006):…”

Section: Multiphase Flow Equationmentioning

confidence: 99%

“…The equation for advective-dispersive transport of a contaminant in the water and gas phases can be written as (Jang and Aral 2006):…”

Section: Contaminant Fate and Transport Equationmentioning

confidence: 99%

See 3 more Smart Citations

Multiphase Flow Fields in In-situ Air Sparging and its Effect on Remediation

Jang

Aral

2008

Transp Porous Med

Self Cite

View full text Add to dashboard Cite

In-situ air sparging (IAS) is used for the clean-up of soil and groundwater that are contaminated with volatile organic compounds in relatively permeable subsurface environments. In this study, we investigated the secondary groundwater and gas flow fields that develop in the vicinity of single and multiple air sparging wells. The purpose is to evaluate their effects on contaminant plume migration and thus, remediation. Governing equations describing multiphase flow and contaminant transport in a three-dimensional domain were formulated and solved using the Galerkin finite element technique. Trichloroethylene was selected as a target contaminant. The increase in air injection contributed to an increase in the size of the IAS cone of influence and the gas saturation levels within the cone. This reduced the groundwater velocity within the cone and increased the zone of detour of groundwater around the air sparging wells. This outcome was quantified and compared under several IAS operations. Different soil permeability characteristics also affected the groundwater and gas flow patterns, and this impacted the remedial performance of the IAS system. Under high ambient groundwater velocity, an air sparging system that uses a single injection well caused the detour of contaminant plumes around injection wells, regardless of air injection rates, and failed to meet the remedial goal specified here. This system was successful for relatively low ambient groundwater velocity environments used here. An IAS system with multiple injection wells was effective in capturing and remediating the detoured contaminant plume, and showed superior performance when compared to a single injection well IAS system. Using IAS simulation, we also analyzed the impact of injection rates on site remediation using single or multiple wells. Design criteria that are based on the results of this study would be useful in enhancing the performance of the IAS systems.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…From mass balance equations and Darcy's law, the governing equation of multiphase flow can be given as (Bear 1972;Jang and Aral 2006):…”

Section: Multiphase Flow Equationmentioning

confidence: 99%

“…The equation for advective-dispersive transport of a contaminant in the water and gas phases can be written as (Jang and Aral 2006):…”

Section: Contaminant Fate and Transport Equationmentioning

confidence: 99%

See 2 more Smart Citations

Multiphase Flow Fields in In-situ Air Sparging and its Effect on Remediation

Jang

Aral

2008

Transp Porous Med

Self Cite

View full text Add to dashboard Cite

show abstract

“…The lack of knowledge and the challenges related to the understanding of transient processes in field and modeling studies were pointed out. Infiltration was a main feature of their transient review, most of which discussed the numerical models describing the transport from leaching sources or NAPL (Jang and Aral, 2007). For example, Parker (2003) simplified vapor advection resulting from both barometric pumping and groundwater level fluctuation into a dispersion term and compared that with molecular diffusion.…”

Section: Introductionmentioning

confidence: 99%

A numerical investigation of vapor intrusion — The dynamic response of contaminant vapors to rainfall events

Shen

Pennell

Suuberg

2012

Science of The Total Environment

View full text Add to dashboard Cite

The U.S. government and various agencies have published guidelines for field investigation of vapor intrusion, most of which suggest soil gas sampling as an integral part of the investigation. Contaminant soil gas data are often relatively more stable than indoor air vapor concentration measurements, but meteorological conditions might influence soil gas values. Although a few field and numerical studies have considered some temporal effects on soil gas vapor transport, a full explanation of the contaminant vapor concentration response to rainfall events is not available. This manuscript seeks to demonstrate the effects on soil vapor transport during and after different rainfall events, by applying a coupled numerical model of fluid flow and vapor transport. Both a single rainfall event and seasonal rainfall events were modeled. For the single rainfall event models, the vapor response process could be divided into three steps: namely, infiltration, water redistribution, and establishment of a water lens atop the groundwater source. In the infiltration step, rainfall intensity was found to determine the speed of the wetting front and wash-out effect on the vapor. The passage of the wetting front led to an increase of the vapor concentration in both the infiltration and water redistribution steps and this effect is noted at soil probes located 1 m below the ground surface. When the mixing of groundwater with infiltrated water was not allowed, a clean water lens accumulated above the groundwater source and led to a capping effect which can reduce diffusion rates of contaminant from the source. Seasonal rainfall with short time intervals involved superposition of the individual rainfall events. This modeling results indicated that for relatively deeper soil that the infiltration wetting front could not flood, the effects were damped out in less than a month after rain; while in the long term (years), possible formation of a water lens played a larger role in determining the vapor intrusion risk. In addition, soil organic carbon retarded the transport process, and damped the contaminant concentration fluctuations.

show abstract