Tomography-measured Spatial Distributions of Non-Aqueous Phase Liquids in Porous Media

Challenges with transport of dense non-aqueous phase liquids (DNAPLs) in geomedia have been observed by scientists and engineers. Detection of residual amounts of dense non-aqueous phase liquids in porous earth materials is important to understand the extent of contamination at sites where these materials have been released. The objectives of this study were to develop and test x-ray computed tomography (CT) methods for detection of DNAPL mass in sand cores. Two methods were used to assess the mass balance of trichloroethane (TCA) injected into selected samples. These methods included the spatial distribution method (SDM) which determined the mass from the point of injection and the mass frequency distribution method (MFDM) which used noise correction algorithms. Results showed that these methods can be used to detect the distribution of DNAPL in sand cores. Methods to assess the effective energy of the CT scanner are critical in obtaining accurate information. This study indicates that the scanning methods generally agree with the mass of DNAPL injected.