Inc. The Natural Attenuation Research Subcommittee has been evaluating EPA's research program and protocols for monitored natural attenuation of contaminants in groundwater, soils and sediments. The committee met Aug. 14-15 at EPA headquarters in Washington, D.C. to discuss and refine the first draft of its report, which it presented to EPA Administrator Carol Browner. Natural attenuation is a form of site remediation that allows naturally occurring or added microbes to break down and resolve the contamination.
Natural attenuation is one of the least expensive forms of site remediation.
Relatively little is known about the biodegradability of MTBE, in comparison to the BTEX chemicals, according to the report. Areas most susceptible to MTBE contamination, such as subsurface soil and groundwater, generally can have anaerobic conditions. Natural attenuation is more effective if it can take place in both aerobic and anaerobic conditions. Specifically, the committee suggested studying MTBE biodegradation, plume behavior and site history, and conducting MTBE microcosm studies. The committee found that enough research and knowledge is available to accurately predict the migration of BTEX chemicals from petroleum contamination, and therefore the scope of site cleanup, but not enough research is available to accurately predict the migration of MTBE plumes.