2007a. A soil vapor extraction pilot study in a deep arid vadose zone - Part 2: simulations in support of decision making processes

Soil vapor extraction (SVE) is a vital tool for remediating subsurface volatile organic plumes at waste sites with deep unsaturated zones. Plumes in the vadose zone are affected by many factors including vapor advection and diffusion, liquid movement, and source release processes. Leakage from buried drums may occur at different rates over the lifetime of a waste site, requiring modeling tools that can adequately address uncertain future scenarios. To demonstrate this concept, we present a numerical model of an SVE pilot test on a volatile organic compound (VOC) plume in the subsurface at Material Disposal Area L, Los Alamos National Laboratory. A site-scale numerical model was previously developed to evaluate the impact of subsurface processes on subsurface contaminants associated with waste disposed at the site. One important goal of model development is to support future corrective measures assessment activities. The model has been extensively tested and used to confirm our conceptual model for transport within the very dry mesa-top setting. In this study we present results of simulations of the SVE test. A 2-D radial model is used to test our conceptual model of flow and transport at this site. The 2-D model is calibrated to the SVE pilot test concentration and pressure data using field measure