Remediation of DNAPL pools using dense brine barrier strategies.

Although dense nonaqueous phase liquid (DNAPL) pools are an important source of groundwater contamination, little experimental data have been generated to develop a mature level of understanding of the problem, and few strategies specifically aimed at remediation have been advanced. We discuss the dominant importance of these features in subsurface systems, present novel two- and three-dimensional heterogeneous experimental systems, and show results from two evolving strategies for remediating DNAPL pools. These strategies involve the joint use of a dense brine barrier and controlled mobilization of trapped DNAPL using small-volume surfactant flushes. These experiments demonstrate a controlled, substantial reduction of entrapped DNAPL in both two- and three-dimensional heterogeneous domains, using less than a single pore volume of flushing solution in some cases.