Solution for Soil Vapor Extraction from a Pressure-Controlled Well
Publication: Journal of Environmental Engineering
Volume 143, Issue 6
Abstract
This paper presents a new solution for a soil venting problem, in which a vertical, partially penetrating well is operated at a fixed pressure under covered, uncovered, or leaking ground surface conditions. The method of domain decomposition is applied to solve the problem of a mixed-type boundary condition imposed along a well screen, which in previous solutions was usually handled by discretization of the screen. The new solution is also capable of predicting the flow field beneath the well bottom, which is commonly neglected by other solutions. The authors found that the present solution may predict different pressure distributions from those given by a solution employing a constant flux rate at a well screen. The radius of influence for soil vapor extraction (SVE) operations is strongly affected by the radial permeability, the vertical permeability, and the ratio between the two. Vacuum pressure values were predicted with the proposed solution and compared against measurements at different observation wells and depths under venting tests at a former SVE-operated site. The measured vacuum pressure and gas flow velocity values around the wells were found to be substantially lower than the predicted values. Thus, the wellbore soils of the site were suspected to be positive skin zones.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
Funding of this work was provided by the ROC Ministry of Science and Technology under Contract 101-2221-E-035-030-MY2 and 103-2221-E-035-002-MY3. The authors would like to thank Yuroa Lin, Yong-tai Sun, and Raili Chung for their assistance in conducting the field experiments.
References
Armstrong, J. E., Frind, E. O., and McClellan, R. D. (1994). “Nonequilibrium mass transfer between the vapor, aqueous, and solid phases in unsaturated soils during vapor extraction.” Water Resour. Res., 30(2), 355–368.
Baehr, A. L., and Hult, M. F. (1991). “Evaluation of unsaturated zone air permeability through pneumatic tests.” Water Resour. Res., 27(10), 2605–2617.
Baehr, A. L., and Joss, C. J. (1995). “An updated model of induced airflow in the unsaturated zone.” Water Resour. Res., 31(2), 417–421.
Benner, M. L., Mohtar, R. H., and Lee, L. S. (2002). “Factors affecting air sparging remediation systems using field data and numerical simulations.” J. Hazard. Mater., B95(3), 305–329.
Boudouch, O., Daoud, E., Mariem, K., and Benadda, B. (2012). “Influence of soil air permeability change on soil vapour extraction systems design.” CLEAN-Soil, Air, Water, 40(5), 461–471.
Chang, C.-C., and Chen, C.-S. (2003). “A flowing partially penetrating well in a finite-thickness aquifer: A mixed-type initial boundary value problem.” J. Hydrol., 271(1–4), 101–118.
Chang, Y.-C., Chen, G.-Y., and Yeh, H.-D. (2011). “Transient flow into a partially penetrating well during the constant-head test in unconfined aquifers.” J. Hydrau. Eng, 1054–1063.
DePaoli, D. W., Wilson, J. H., and Thomas, C. O. (1996). “Conceptual design of soil venting systems.” J. Environ. Eng., 399–406.
DiGiulio, D. C., and Varadhan, R. (2001). “Development of recommendations and methods to support assessment of soil venting performance and closure.”, National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati.
Falta, R. W. (1996). “A program for analyzing transient and steady-state soil gas pump tests.” Ground Water, 34(4), 750–755.
Kuo, C., Huang, C., and Yeh, H.-D. (2011). “Transient analysis for fluid injection into a dome reservoir.” Advan. Water Resou., 34(12), 1553–1562.
Nobre, M. M. M., and Nobre, R. C. M. (2004). “Soil vapor extraction of chlorinated solvents at an industrial site in Brazil.” J. Hazard. Mater., 110(1), 119–127.
Perina, T. (2014). “General well function for soil vapor extraction.” Advan. Water Resour., 66(4), 1–7.
Perina, T., and Lee, T.-C. (2005). “Steady-state soil vapor extraction from a pressure-controlled or flow-controlled well.” Ground Water Monit. Remed., 25(3), 63–72.
Perina, T., and Lee, T.-C. (2007). “Transient soil vapor extraction from a pressure-controlled well.” Ground Water Monit. Remed., 27(1), 47–55.
Rahbeh, M. E., and Mohtar, R. H. (2007). “Application of multiphase transport models to field remediation by air sparging and soil vapor extraction.” J. Hazard. Mater., 143(1-2), 156–170.
Stehfest, H. (1970). “Algorithm 368: Numerical inversion of Laplace transforms [D5].” Commun. ACM, 13(1), 47–49.
Suthersan, S. S. (1999). “Remediation engineering: Design concepts.” CRC, Boca Raton, Florida.
Switzer, C., and Kosson, D. S. (2007). “Evaluation of air permeability in layered unsaturated materials.” J. Contam. Hydrol., 90(3–4), 125–145.
You, K., Zhan, H., and Li, J. (2010). “A new solution and data analysis for gas flow to a barometric pumping well.” Advan. Water Res., 33(12), 1444–1455.
You, K., Zhan, H., and Li, J. (2011). “Analysis of models for induced gas flow in the unsaturated zone.” Water Resour. Res., 47(4), W04515.
Information & Authors
Information
Published In
Copyright
©2017 American Society of Civil Engineers.
History
Received: Mar 15, 2015
Accepted: Dec 1, 2016
Published ahead of print: Feb 21, 2017
Published online: Feb 22, 2017
Published in print: Jun 1, 2017
Discussion open until: Jul 22, 2017
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.