Abstract
Use of contaminant mass discharge (CMD) or mass-flux measurements to characterize site conditions and assess remediation performance of nonaqueous phase liquid (NAPL) is becoming popular. The main objective of this study is to determine how groundwater flux variations in the source zone can affect nonaqueous phase liquid (NAPL) dissolution dynamics. In particular, the authors develop interplays among groundwater flux variations, NAPL aqueous concentration, NAPL CMD, and other source strength dynamics. A power-law functional form is used to describe groundwater flux variations in illustrating how NAPL source strength functions can be affected. The developed analytical models can capture a wide range of NAPL source zone dynamics encountered in real-world applications. The results demonstrate the significance of groundwater flux variations in influencing the NAPL source dynamics. If groundwater flux decreases with time, the CMD declines initially at higher rate, but the rate decreases at later stages. In contrast, when groundwater flux increases with time, the NAPL CMD exhibits a slower decline initially and faster decrease at later stage. When groundwater flux in the source zone increases with time, the reduction in CMD (CMDR) increases slower than the NAPL mass reduction (MR), leading to a concave downward CMDR versus MR curve. If groundwater flux decreases with time, the CMDR versus MR curve is convex upward. When the groundwater flux does not change with time, CMDR versus MR follows a 1:1 linear relationship. The models are also compared with the observed dynamics of a trichloroethene (TCE) contaminated field. Although the root mean square error (RMSE) for the TCE aqueous concentration does not change much for both the constant and variable groundwater flux conditions, that for the CMD can be reduced significantly using the model of power-law groundwater flux variations.
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Acknowledgments
This research was funded by the Faculty Grant-In-Aid program at the University of Wyoming (1100-21266-2015) and the Wyoming Center for Environmental Hydrology and Geophysics.
References
Basu, N. B., et al. (2009). “Integration of traditional and innovative characterization techniques for flux-based assessment of Dense Non-aqueous Phase Liquid (DNAPL) sites.” J. Contam. Hydrol., 105(3–4), 161–172.
Basu, N. B., Rao, P. S. C., Falta, R. W., Annable, M. D., Jawitz, J. W., and Hatfield, K. (2008). “Temporal evolution of DNAPL source and contaminant flux distribution: Impacts of source mass depletion.” J. Contam. Hydrol., 95(3–4), 93–109.
Bockelmann, A., Zamfirescu, D., Ptak, T., Grathwohl, P., and Teutsch, G. (2003). “Quantification of mass fluxes and natural attenuation rates at an industrial site with a limited monitoring network: A case study.” J. Contam. Hydrol., 60(1–2), 97–121.
Brooks, M. C., et al. (2004). “Controlled release, blind test of DNAPL remediation by ethanol flushing.” J. Contam. Hydrol., 69(3–4), 281–297.
Brusseau, M. L., et al. (2011a). “Impact of in-situ chemical oxidation on contaminant mass discharge: Linking source-zone and plume-scale characterizations of remediation performance.” Environ. Sci. Technol., 45(12), 5352–5358.
Brusseau, M. L., et al. (2013). “Characterizing long-term contaminant mass discharge and the relationship between reductions in discharge and reductions in mass for DNAPL source areas.” J. Contam. Hydrol., 149, 1–12.
Brusseau, M. L., and Guo, Z. (2014). “Assessing contaminant-removal conditions and plume persistence through analysis of data from long-term pump-and-treat operations.” J. Contam. Hydrol., 164, 16–24.
Brusseau, M. L., Hatton, J., and DiGuiseppi, W. (2011b). “Assessing the impact of source-zone remediation efforts at the contaminant-plume scale: Application to a chlorinated-solvent site.” J. Contam. Hydrol., 126(3–4), 130–139.
Brusseau, M. L., Nelson, N. T., Zhang, Z., Blue, J. E., Rohrer, J., and Allen, T. (2007). “Source-zone characterization of a chlorinated-solvent contaminated superfund site in Tucson, AZ.” J. Contam. Hydrol., 90(1–2), 21–40.
Christ, J. A., Ramsburg, C. A., Pennell, K. D., and Abriola, L. M. (2010). “Predicting DNAPL mass discharge from pool-dominated source zones.” J. Contam. Hydrol., 114(1–4), 18–34.
Chrysikopoulos, C. V., Hsuan, P.-Y., Fyrillas, M. M., and Lee, K. Y. (2003). “Mass transfer coefficient and concentration boundary layer thickness for a dissolving NAPL pool in porous media.” J. Haz. Mater., B97(1–3), 245–255.
Chrysikopoulos, C. V., and Kim, T.-J. (2000). “Local mass transfer correlations for nonaqueous phase liquid pool dissolution in saturated porous media.” Transp. Porous Media, 38(1/2), 167–187.
DiFilippo, E. L., and Brusseau, M. L. (2008). “Relationship between mass flux reduction and source-zone mass removal: Analysis of field data.” J. Contam. Hydrol., 98(1–2), 22–35.
DiFilippo, E. L., and Brusseau, M. L. (2011). “Assessment of a simple function to evaluate the relationship between mass flux reduction and mass removal for organic-liquid contaminated source zones.” J. Contam. Hydrol., 123(3), 104–113.
DiGiulio, D. C., Ravi, V., and Brusseau, M. L. (1999). “Evaluation of mass flux to and from ground water using a vertical flux model (VFLUX): Application to the soil vacuum extraction closure problem.” Ground Water Monit. Rem., 19(2), 96–104.
Einarson, M. D., and Mackay, D. M. (2001). “Predicting impacts of groundwater contamination.” Environ. Sci. Technol., 35(3), 66A–73A.
Falta, R. W., Rao, P. S., and Basu, N. (2005). “Assessing the impacts of partial mass depletion in DNAPL source zones: I. Analytical modeling of source strength functions and plume response.” J. Contam. Hydrol., 78(4), 259–280.
Freeze, R. A., and McWhorter, D. B. (1997). “A framework for assessing risk reduction due to DNAPL mass removal from low-permeability soils.” Ground Water, 35(1), 111–123.
Geller, J. T., and Hunt, J. R. (1993). “Mass transfer from nonaqueous phase organic liquids in water-saturated porous media.” Water Resour. Res., 29(4), 833–845.
Imhoff, P. T., Jaffe, P. R., and Pinder, G. F. (1994). “An experimental study of complete dissolution of a nonaqueous phase liquid in saturated porous media.” Water Resour. Res., 30(2), 307–320.
Jawitz, J. W., Annable, M. D., Demmy, G. G., and Rao, P. S. C. (2003). “Estimating nonaqueous phase liquid spatial variability using partitioning tracer higher temporal moments.” Water Resour. Res., 39, 1192.
Jawitz, J. W., Fure, A. D., Demy, G. G., Berglund, S., and Rao, P. S. C. (2005). “Groundwater contaminant flux reduction resulting from nonaqueous phase liquid mass reduction.” Water Res. Res., 41(10), W10408.
Johnston, C. D., et al. (2013). “The use of mass depletion-mass flux reduction relationships during pumping to determine source zone mass of a reactive brominated-solvent DNAPL.” J. Contam. Hydrol., 144(1), 122–137.
Johnston, C. D., et al. (2014). “Mass discharge assessment at a brominated DNAPL site: Effects of known DNAPL source mass removal.” J. Contam. Hydrol., 164, 100–113.
Khachikian, C., and Harmon, T. C. (2000). “Nonaqueous phase liquid dissolution in porous media: Current state of knowledge and research needs.” Transp. Porous Media, 38(1/2), 3–28.
Kim, T.-J., and Chrysikopoulos, C. V. (1999). “Mass transfer correlations for nonaqueous phase liquid pool dissolution in saturated porous media.” Water Resour. Res., 35(2), 449–459.
Leij, F. J., and van Genuchten, M. T. (2000). “Analytical modeling of nonaqueous phase liquid dissolution with Green’s functions.” Transp. Porous Media, 38(1–2), 141–166.
Parker, J. C., Kim, U., Widdowson, M., Kitanidis, P., and Gentry, R. (2010). “Effects of model formulation and calibration data on uncertainty in dense nonaqueous phase liquids source dissolution predictions.” Water Resour. Res., 46(12), W12517.
Powers, S. E., Abriola, L. M., Dunkin, J. S., and Weber, W. J. (1994a). “Phenomenological models for transient NAPL-water mass-transfer processes.” J. Contam. Hydrol., 16(1), 1–33.
Powers, S. E., Abriola, L. M., and Weber, W. J. (1994b). “An experimental investigation of nonaqueous phase liquid dissolution in saturated subsurface systems-transient mass transfer rates.” Water Resour. Res., 30(2), 321–332.
Soga, K., Page, J. W. E., and Illangasekare, T. H. (2004). “A review of NAPL source zone remediation efficiency and the mass flux approach.” J. Haz. Mater., 110(1–3), 13–27.
Stroo, H. F., et al. (2003). “Remediating chlorinated solvent source zones.” Environ. Sci. Technol., 37(11), 224A–230A.
Wang, F., Annable, M. D., Schaefer, C. E., Ault, T. D., Cho, J., and Jawitz, J. W. (2014). “Enhanced aqueous dissolution of a DNAPL source to characterize the source strength function.” J. Contam. Hydrol., 169, 75–89.
Zhou, D., Dillard, L. A., and Blunt, M. J. (2000). “A physically based model of dissolution of nonaqueous phase liquids in the saturated zone.” Transp. Porous Media, 39(2), 227–255.
Zhu, J. (2014). “Dissolution dynamics and temporal variations of groundwater flux in the subsurface source zone of nonaqueous phase liquids.” J. Haz. Toxic Radioact. Waste, 04014032.
Zhu, J., and Sykes, J. F. (2004). “Simple screening models of NAPL dissolution in the subsurface.” J. Contam. Hydrol., 72(1–4), 245–258.
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Published In
Journal of Hazardous, Toxic, and Radioactive Waste
Volume 20 • Issue 3 • July 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Sep 8, 2015
Accepted: Jan 14, 2016
Published online: Mar 24, 2016
Published in print: Jul 1, 2016
Discussion open until: Aug 24, 2016
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