Partitioning tracers for in situ detection and quantification of dense nonaqueous phase liquids in groundwater systems. 1998 annual progress report

Abstract

'The overall goal of the proposed project is to explore the use of an innovative in-situ method for the detection and quantification of dense nonaqueous phase liquids (DNAPLs) in water-saturated and unsaturated heterogeneous media. Effective risk assessment and remediation of DNAPL contaminated sites is constrained by the limitations of current site characterization techniques. A major weakness of the current methods is that they provide data at discrete points, such that the probability of sampling a zone of localized DNAPL is quite small. The results of the proposed research will lead to improved techniques for characterizing DNAPL contaminated sites and will enhance the understanding of the distribution of DNAPLs in the subsurface. The use of this methods will reduce the uncertainty associated with risk assessments and remediation planning. The project objectives include exploring partitioning tracers for the detection and quantification of DNAPLs in saturated systems using aqueous tracers and in unsaturated systems using gas-phase tracers. This report summarizes work completed mid-way through year 2 of a 3-year project. Batch experiments have been conducted for a suite of bulk-phase partitioning tracers to determine water- trichloroethene (TCE) partitioning coefficients. Interfacial tension measurements have been made between TCE and solutions of several potential interfacemore » partitioning tracers. Preliminary column experiments have been conducted for the aqueous bulk-phase partitioning tracers using columns packed with a homogeneous sand and containing a residual saturation of TCE. These preliminary sets of experiments have enabled selection of suitable tracers for the water-saturated experiments and have lead to improved experimental designs and methods.'« less