Solution for Soil Vapor Extraction from a Pressure-Controlled Well

Ching Lin Kuo, Chiu Shia Fen*, Kai Hsin Chen, Hund-Der Yeh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish
Article number04017012
JournalJournal of Environmental Engineering (United States)
Volume143
Issue number6
DOIs
StatePublished - 1 Jun 2017

Keywords

  • Gas phase pressure
  • Mathematical model
  • Soil vapor extraction (SVE)
  • Unsaturated soils
  • Vertical well

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