Relative Importance of Natural Attenuation Processes in a Trichloroethene Plume and Comparison to Pump-and-Treat Remediation at Picatinny Arsenal, New Jersey

by Thomas E. Imbrigiotta and Theodore A. Ehlke

ABSTRACT

The relative importance of naturally occurring fate and transport processes that remove or introduce trichloroethene (TCE) from or to a contamination plume at Picatinny Arsenal, New Jersey, was evaluated. Anaerobic biotransformation removes the most TCE from the plume, destroying 230 kilograms per year, and accounts for approximately 70 percent of the total mass of TCE removed from the plume annually by all natural attenuation processes. Advective transport and advection-driven volatilization each remove 50 kilograms per year. Other removal processes--lateral dispersion, diffusion-driven volatilization, and sorption--are minor in comparison. Desorption is the most significant TCE input process evaluated. A mass-balance analysis shows that the removal of TCE from the plume by natural attenuation processes is of the same order of magnitude as the input of TCE to the plume. The field-scale natural-attenuation rate constants calculated from field TCE concentrations and time-of-travel data are in general agreement with anaerobic-biotransformation rate constants measured in laboratory microcosm studies. A pump-and-treat system operating at the site is removing about 20 percent as much TCE as is being removed from the plume annually by natural attenuation processes.