In-situ characterizations of dense non-aqueous phase liquids using partitioning tracers. Annual progress report, September 15, 1996--September 14, 1997

'This paper describes laboratory research conducted to investigate the use of partitioning tracers for the detection, volume estimation, and remediation performance assessment of vadose zones contaminated by nonaqueous phase liquids (NAPLs). These laboratory studies used Ottawa sand and field soil packed columns. The columns were saturated, then reduced to residual saturations of water and NAPL, creating a three phase system of air, water, and NAPL. Conservative and partitioning gas tracers were injected into the column and their elutions were analyzed. The method of moments was used to estimate partition coefficients between the air and NAPL phases for each of the tracers. The partition coefficients and retardation factors are used to select appropriate tracers for NAPL detection and volume estimation in the field. This research identified several perfluorocarbon tracers suitable for use in the field and demonstrated the feasibility of using partitioning tracers as a tool for NAPL detection and volume estimation in the vadose zone.