Can atmospheric pressure and water table fluctuations be neglected in soil vapor extraction?

Abstract

Solutions to soil vapor extraction (SVE) are indispensable to characterize the unsaturated zone and to optimize SVE. Most of the existing solutions neglect the fluctuations of atmospheric pressure and water table. This study presents a new semi-analytical solution for SVE by considering the atmospheric pressure and water table fluctuations. Comparisons between the new and previous solutions indicate that the water table effect is negligible but the atmospheric pressure effect is non-negligible for the interpretation of gas pressure in a non-coastal site where the daily water table fluctuation is in centimeters scale; both the water table and atmospheric pressure fluctuations need to be considered in a coastal site where the daily water table fluctuation is in tens of centimeters scale. Tidal-induced downward moving water table increases the depth-averaged radius of influence, which is insensitive to atmospheric pressure fluctuation. Less vertical gas permeability leads to greater atmospheric pressure and water table effect.