CHARACTERIZATION OF FLOW PARAMETERS CONTROLLING SOIL VAPOR EXTRACTION

Soil parameters controlling vapor flow in the subsurface are necessary to design soil vapor extraction (SVE) cleanup systems. Previous work assumes a confined flow model, with concrete and asphalt surface cover s providing the confining layer and preventing air leakage into the zo ne of vapor transmission. SVE field tests conducted as part of this in vestigation, however, exhibited responses that are inconsistent with a confined flow model; it appears that the real world leaks. This paper develops a transient soil vapor extraction (SVE) testing method that considers the effects of vertical leakage. Analytic methodologies are developed that allow use of commonly available ground-water flow type curves to evaluate SVE test data. The key implications of leaky compar ed to confined flow are (1) smaller values of derived vapor permeabili ty, and (2) decreased radial cleanup efficacy, both with time and dist ance.