USGS Research on Fate and Remediation of Point-Source NAPLs (Goode, 2007)
Daniel J. Goode
U.S. Geological Survey
The U.S. Geological Survey (USGS) Toxic Substances Hydrology Program has established intensive field studies at sites representative of predominant types of environmental contamination, in commonly occurring hydrogeologic and geochemical settings. Contaminant sources currently under investigation include chlorinated solvents and petroleum products, including fuel oxygenates. Long-term research projects are conducted by interdisciplinary research teams that identify and characterize physical, chemical, and biological processes that affect contaminant transport, transformation, and fate. Knowledge and tools produced at these representative sites help improve the effectiveness and reduce the cost of characterization and remediation at similar sites across the Nation. The long-term nature of the research provides a unique opportunity to evaluate the potential and limitations of natural-attenuation remediation, engineered remedial alternatives, and remediation-performance monitoring. Highlights include methodologies for >monitored natural attenuation of gasoline-contaminated ground-water, identification of efficient natural attenuation of methyl tert-butyl ether (MTBE) and other gasoline components in the hyporheic zone (stream/ground-water interface), identification of atmospheric and other potential sources for MTBE to ground water, and a simple method for calculating growth rates of petroleum plumes. Research on persistent trichloroethene (TCE) and reaction-daughter-product contamination in a fractured-rock aquifer is focused on migration of dense non-aqueous-phase liquid (NAPL) TCE, exchange of solutes and bacteria between transmissive fractures and low-permeability regions, and monitoring methods for natural attenuation enhanced through bioaugmentation. Quantitative models have been used successfully at several sites for estimating the relative contribution of each natural attenuation process to the overall mass loss. Future research will target gaps in understanding of persistent compounds and existing and new fuel additives or alternatives, subsurface microbial ecology, variability in geochemistry and reaction rates, complexities associated with multi-phase processes and heterogeneous formations, and uncertainties in predicting fate over long time frames.
Citation: Goode, D.J., 2007, USGS research on fate and remediation of point-source NAPLs (abstract): EPA Region III States LUST Technical Workshop, October 22 - 24, 2007, Gettysburg, Pennsylvania.
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