PHYTOREMEDIATION OF TRICHLOROETHYLENE IN A SHALLOW ALLUVIAL AQUIFERA FIELD DEMONSTRATION
|S.M. Eberts1, G.J. Harvey2, and S. Rock3, 1U.S. Geological Survey, 975 W. Third Ave., Columbus, OH 43212, 21801 10th St., Bldg. 8, Ste 2, Area B WPAFB, OH 45433, and 326 W. Martin Luther King Dr., Cincinnati, OH 45268||
A field demonstration designed to evaluate the use of phytoremediation to help clean up shallow trichloroethylene-contaminated ground water has been initiated at the Naval Air Station Fort Worth, Texas. The demonstration entails the planting and cultivation of eastern cottonwood trees above a dissolved trichloroethylene (TCE) plume in a shallow (6 - 11 feet below grade) alluvial aquifer. On the basis of published laboratory investigations, the trees are expected to serve as a natural-pump-and-treat system.
Initial site characterization and final site selection were completed in January 1996. Site development, which included planting trees and installing an irrigation system, was completed in April 1996. Monitoring wells and equipment were installed during summer 1996. Baseline sampling also began during summer 1996; demonstration sampling will continue until the year 2000. A mature cottonwood tree adjacent to the site was selected for additional sampling to provide early feedback on the potential fate of the TCE.
Ground water levels and TCE concentrations in the aquifer will be monitored to establish baseline conditions and to map changes within the aquifer throughout the life of the demonstration. Contaminant concentrations will also be monitored in the rhizosphere and in the tree tissues. Microbial activity in the rhizosphere will be monitored and tree transpiration rates will be modeled. These data will be used to determine the fate, and processes that affect the fate, of TCE at the site.
A stand of whips (cuttings) and a stand of 1- to 2-year-old trees are included in the study. These stands were planted and will be monitored in a similar fashion. Costs associated with the planting and cultivation of each tree stand will be compared to help assess the practicability of phytoremediation as a cleanup technology.
Key words: phytoremediation, trichloroethylene, alluvial, aquifer, demonstration
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