As groundwater flows through a source zone, small amounts of DNAPL are dissolved

and carried away in a plume of contaminated water. Advection and dispersion forces tend to

dilute and spread this plume as it moves away from the source area. However, the low solubility

of most DNAPLs makes them highly persistent and the DNAPL acts as a reservoir for sustaining

dissolved plumes. Thus, media heterogeneities, sorption to subsurface media, and diffusion into

low permeable layers makes DNAPL source zones highly complex and unique at each site.

 Another difficulty of DNAPL cleanup efforts is finding the source of groundwater

contamination. Although sufficient technologies exist to delineate a source zone, some sites will

require extensive sampling due to the spatial distribution of free phase DNAPL in the subsurface

[EPA, 2003]. Since deposits can be highly localized, multiple methods should be used to locate

the source of dissolved contamination. Therefore, it is important to perform accurate, detailed

site characterization including hydrogeology, source delineation, and biogeochemistry to best

assess site risk and to develop to the proper treatment regimen for the specific site [NRC, 2005].

 Unfortunately, due to their low solubility and recalcitrance many of the sites

contaminated with these compounds will persist for decades or centuries. Although conventional

pump-and-treat measures can contain the dissolved plume and slightly enhance DNAPL

dissolution, there would be great cost to implement and maintain this type of treatment for the

long timescales required [McKay and Cherry, 1989; NRC, 2005]. Thus, innovative methods to

remove DNAPLs have been devised and tested over the past two decades, including

enhancements of aqueous solubility, mobility, volatility, and biodegradation. Many of these new

technologies are highly successful at removing DNAPL mass from the subsurface. However,

due to the complex entrapment architecture of field sites, complete removal of free phase and

residual DNAPL has been thus far not possible [Soga et al., 2004]. Consequently, remediation at