Field data and numerical simulation of btex concentration trends under water table fluctuations: Example of a jet fuel-contaminated site in Brazil

• Published in: Journal of contaminant hydrology 2017-03, Vol.198, p.37-47
• Main Authors: Teramoto, Elias Hideo, Chang, Hung Kiang
• Format: Article
• Language: English
• Subjects: Benzene Derivatives - analysis; Brazil; BTEX; Environmental Monitoring; Groundwater - analysis; Hydrocarbons - analysis; LNAPL saturation; Mass-transfer; Models, Theoretical; Porosity; Smear zone; Water Pollutants, Chemical - analysis; Water table fluctuation
• ISSN: 0169-7722; 1873-6009
• DOI: 10.1016/j.jconhyd.2017.01.002

Mass transfer of light non-aqueous phase liquids (LNAPLs) trapped in porous media is a complex phenomenon. Water table fluctuations have been identified as responsible for generating significant variations in the concentration of dissolved hydrocarbons. Based on field evidence, this work presents a conceptual model and a numerical solution for mass transfer from entrapped LNAPL to groundwater controlled by both LNAPL saturation and seasonal water table fluctuations within the LNAPL smear zone. The numerical approach is capable of reproducing aqueous BTEX concentration trends under three different scenarios – water table fluctuating within smear zone, above the smear zone and partially within smear zone, resulting in in-phase, out-of-phase and alternating in-phase and out-of-phase BTEX concentration trend with respect to water table oscillation, respectively. The results demonstrate the model's applicability under observed field conditions and its ability to predict source zone depletion. •A conceptual model and numerical solution for mass transfer from entrapped LNAPL to groundwater is proposed.•Mass transfer is governed by both LNAPL saturation and seasonal water table fluctuations within the LNAPL smear zone.•The numerical approach is capable of reproducing aqueous BTEX concentration trends under different field conditions.