Laboratory characterization of non-aqueous phase liquid/tracer interactionin support of a vadose zone partitioning interwell tracer test

Contaminant characterization is important for successful remediation of non -aqueous phase liquids (NAPLs) in the unsaturated zone. A partitioning inte rwell tracer test (PITT) can provide a good estimate of average subsurface NAPL saturations. Screening experiments were completed in the laboratory to evaluate several gas tracers for a PITT study to be completed in the vados e zone at Kirtland Air Force Base in Albuquerque, NM. Four perfluorocarbon tracers were found to be suitable for this PITT. Further laboratory column studies were completed using contaminated field soil to measure the partiti on coefficients between the tracers and the NAPL. The results from the colu mn studies showed that the air/NAPL tracer partition coefficients ranged fr om 8.8 +/- 0.6 to 71 +/- 3. This range of partition coefficients is suitabl e for detection of NAPL saturations in the field of 0.002 to 0.14. (C) 2000 Elsevier Science B.V. All rights reserved.