Soil-Gas Investigations for the Deliniation of VOC Contaminations in the Subsurface

Delineation and remediation of subsurface contamination have become a major focus of environmental science during the past ten years. Owing to the high cost of installing groundwater wells, soil-gas monitoring is often used as a preliminary technique for determining the presence and extent of underlying groundwater contamination and to assist in the design of monitoring well networks. This practice is based on the assumption that volatile contaminants in groundwater are transported upward in sufficient quantity to be detected in the overlying soil-gas. Several field studies have indicated that mass exchange between the saturated and unsaturated zones does occur (Rivett 1995; Dagvis 1998; Lahvis et al. 1999), but the relationship between contaminant concentrations in the groundwater and the soil-gas is not entirely understood.