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Environmental Health - Toxic Substances

Toxics Program Remediation Activities

Cold-Temperature Biodegradation of Methyl Tert-Butyl Ether (MTBE) in Ground Water

Type Natural Attenuation Evaluation
Location Almena Agricenter Site, Almena, Kansas
Partners Kansas Department of Health and Environment
Technology Monitored Natural Attenuation
  • Methyl tert-butyl ether (MTBE)
  • BTEX

U.S. Geological Survey (USGS) scientists collaborated with the Kansas Department of Health and Environment to study the fate of methyl tert-butyl ether (MTBE) released from a leaking underground storage tank (UST) at the Almena Agricenter Site in northern Kansas (near Almena, Kansas). The Almena site had multiple leaking underground storage tanks (USTs) that resulted in contamination of shallow ground water at the site. Dissolved-phase MTBE concentrations were observed as large as 170 micrograms per liter (µg/L). Since the annual range of ground-water temperatures was 8º Celsius (C) 46.4º Fahrenheit (F) to 18ºC (64.4ºF), questions arose as to whether MTBE could biodegrade at such cold temperatures.

To address the questions, USGS scientists collected sediments from a dilute, downgradient portion of the MTBE plume (dissolved MTBE <100 µg/L) at a depth of approximately 10 meters (31 feet). The scientists conducted laboratory microcosm studies on the sediment samples, and demonstrated that the microbial communities present at the site can biodegrade MTBE at temperatures as cold as 4°C (39.2°F). The scientists also documented the biodegradation of MTBE at another cold climate UST site near Ronan, Montana. The results of this study were used to demonstrate that MTBE was degrading at the Almena site, and that natural attenuation could be used in conjunction with ongoing soil vapor extraction (SVE) as the remediation remedy.

Study results were also used to document the reason why contaminants were continuing to be cleaned up during the winter months when the efficiency of SVE typically decreases because the volatility MTBE and other contaminants is lower due to the colder temperatures. The decrease in volatility is compensated for by the higher solubility of oxygen in cooler water than in warmer water. More dissolved oxygen stimulates higher biodegradation rates. The end result is that the SVE systems at many UST sites in Kansas are being augmented by natural attenuation processes during the winter months when SVE is least efficient.

More Information
  • Jim Landmeyer, USGS South Carolina Water Science Center,
  • Paul Bradley, USGS South Carolina Water Science Center

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Page Last Modified: Friday, 29-Apr-2016 14:09:50 EDT