Abstract

Soil permeabilities are crucial in the analysis of a soil vapor remediation system. This article presents two methods for determining vertical and horizontal soil permeability (k_z and k_r) from pneumatic test data. Both the first method, the Newton-Raphson procedure, and the second, the sensitivity analysis method, use the analytical solution developed by Shan et al. (1992) to model a steady-state gas flow to a well partially penetrating the vadose zone. The Newton-Raphson method determines soil permeabilities by using gas pressures collected from two or more observation locations. Calculation examples indicate that the method is efficient and reliable in determination of k_r and k_z values. This method was compared with the sensitivity analysis technique, which is more flexible in accommodating the number of data points. Both methods give k_r and k_z values very close to the real solutions. However, calculation examples show that the Newton-Raphson method is more liberal in the selection of initial k_r values for the iteration process. It also requires fewer iteration steps to reach a convergence in the cases where the number of data points is less than six.