A PICTURE IS WORTH A THOUSAND WELLS: NAPL TRANSPORT EVALUATED WITH ELECTRICAL IMAGING

Present understanding of the subsurface is most often derived from samples at discrete points (wells) and interpolations or models that fill in the space between these points. Direct push electrical resistivity tomography (DPERT) combined with advanced computing techniques has produced an improved capability to map contaminants (especially NAPLs) away from traditional wells using actual field data. At a number of different sites, this methodology has provided the ability to map NAPLs, but these data have altered the interpretation of NAPL flow and transport. The data, confirmed by drilling, have demonstrated that NAPLs move as blobs similar to that seen in pore scale laboratory experiments. Often, these blobs exist between monitoring and remediation wells that show low to no detectable contaminants when sampled. Future work will be able to use these techniques to refine, improve and in some cases redefine our conceptual and numerical models of contaminant transport.