THE IMPACT OF CONTAMINANT CONTACT TIME AND POROUS-MEDIA WEATHERING ON TRANSPORT OF TRICHLOROETHENE IN AQUIFER MATERIAL

This study investigates the impact of two aspects of aging, sorption contact time (i.e., contaminant aging) and the magnitude of water flooding (i.e., weathering) on the transport of trichloroethene in a low organic-carbon content aquifer material. The influence of the former was investigated by comparing elution curves for media exposed to trichloroethene for a few days and for four years. The latter was investigated by comparing elution curves for media that were subjected to several hundred pore volumes of water flooding to those that were not. Two fractions of media were used, one with a low fraction of fines and one with a higher fraction. Elution of trichloroethene exhibited extensive low-concentration tailing for all treatments, despite minimal retention of trichloroethene by the aquifer material. For the media with low fines, the elution behavior of trichloroethene for the aged treatments was essentially identical to that observed for the non-aged treatments, indicating that aging did not significantly influence the transport and fate behavior of trichloroethene for this media. Conversely, aging did affect trichloroethene transport for the media with a higher fraction of fines, wherein elution tailing was greater for the media that were pre-flooded. This observed behavior suggests that sorption of trichloroethene was influenced by weathering of the clay-sized fraction.