A method for controlling vertical migration of contaminants in an aquifer includes introduction of a solubilizing solution having a surfactant and an alcohol or other light co-solvent. The surfactant is selected to solubilize the contaminant. The alcohol or other solvent is selected to provide the microemulsion with a substantially neutral buoyancy with respect to groundwater. The neutral buoyancy of the microemulsion prevents the normal downward movement which is typical of the solubilized dense non-aqueous phase liquid in surfactant-enhanced aquifer remediation. Thus, the risk that any significant amount of the solubilized dense non-aqueous contaminants will migrate vertically can be controlled. The relative tendency for vertical migration may also be reduced by increasing the injection rate or injected fluid viscosity (by adding polymer), or by reducing the well spacing.
CONTRACTUAL ORIGIN OF THE INVENTION
The United States Government has rights in this invention pursuant to Contract No. DE-AC07-94ID13223 between Lockheed Martin Idaho Technologies Company and The United States Department of Energy.