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Gas flow to a barometric pumping well in a multilayer unsaturated zone
Author(s) -
You Kehua,
Zhan Hongbin,
Li Jian
Publication year - 2011
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2010wr009411
Subject(s) - vadose zone , volumetric flow rate , flow (mathematics) , soil vapor extraction , environmental remediation , mechanics , pressure gradient , atmospheric pressure , environmental science , materials science , soil science , soil water , meteorology , physics , contamination , ecology , biology
When an open well is installed in an unsaturated zone, gas can flow between the subsurface and the well depending on the gas pressure gradient near the well. This well is called a barometric pumping well (BPW). Quantifying gas flow rate to and from a BPW is indispensable to optimize the passive soil vapor extraction in remediation of volatile organic compounds in the unsaturated zone. This study presents a two‐dimensional (2‐D) semianalytical solution for a multilayer unsaturated zone (ML solution) to determine gas flow rate to and from a BPW. The gas flow rate is approximated by a decomposing method frequently used in previous studies, that is, first solving the one‐dimensional (1‐D) vertical flow equation in response to the surface barometric pressure fluctuations and then superimposing this solution on that of the 1‐D horizontally radial flow equation. The error induced by this approximation is quantified by a 2‐D numerical simulation for the first time in this study. Results show that the maximum error induced is 20% at the peak flow rates. The ML solution is demonstrated to be sufficient for predicting subsurface gas pressure and gas flow rate in a multilayer unsaturated zone by the barometric pumping test at the Hanford site.