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MTBE (methyl tertiary-butyl ether) and Underground Storage Tanks
EPA's federal underground storage tank (UST) regulations have contributed greatly to reducing soil and groundwater contamination (by MTBE and other fuel components) from USTs. However, not all UST systems are regulated and not all components of regulated UST systems are regulated. Even with the most ideal regulations, there will continue to be equipment failures and installation mistakes which will result in releases of fuel to the environment. Nonetheless, EPA is taking action to implement the UST-related recommendations of the Blue Ribbon Panel on Oxygenates in Gasoline. For example, EPA is working with states to increase the compliance rate with the spill, overfill, and corrosion protection requirements of the federal UST regulations. As of December 22, 1998, all substandard USTs (those not meeting requirements for spill, overfill, and corrosion protection requirements) were required to be upgraded or closed. EPA is also working with states to improve the compliance rate with the leak detection requirements; we are jointly undertaking a major multi-year effort to increase UST owners' and operators' compliance rates through compliance assistance, UST inspections, and enforcement.
In addition to USTs, there are many other potential sources of MTBE contamination, such as discharge of unburned fuel from water craft (especially 2-stroke engines); gasoline spills from automobile and tanker truck accidents; gasoline spills and drips when refueling automobiles, lawnmowers, tractors and other machines; plus leaks from pipelines and aboveground storage tanks. The public can also assist in helping to prevent MTBE contamination by following safe fuel handling practices.
MTBE is found in gasoline (and other petroleum fuels) that is commonly stored in underground storage tanks (USTs). MTBE is typically added to reformulated gasoline, oxygenated fuel, and premium grades of unleaded gasoline. EPA has not set a national standard for MTBE [in drinking water], although some states have set their own limits. In December 1997, EPA issued a Drinking Water Advisory. This advisory established a taste threshold of 40 ppb and an odor threshold of 20 ppb.
EPA is continuing to study both the potential health effects and the occurrence of MTBE, and it is on a list of contaminants (Contaminant Candidate List) for which EPA is considering setting drinking water standards.
Essential Information on MTBE
- Frequent Questions About MTBE and USTs
- GAO Report on MTBE Contamination From Underground Storage Tanks. GAO-02-753T, May 21, 2002 (PDF) (19 pp, 642K, About PDF)
Testimony of John Stephenson, Director, Natural Resources and Environment, Before the Subcommittee on Environment and Hazardous Materials, Committee on Energy and Commerce, House of Representatives. - EPA's MTBE Demonstration Project
The Agency is sponsoring field demonstrations of technologies/processes for drinking water treatment and/or groundwater remediation. Data will be collected to evaluate performance and cost of the selected technologies/processes. - The Blue Ribbon Panel on Oxygenates in Gasoline This panel was formed in November 1998 to review use of MTBE and other oxygenates in gasoline.
- What recommendations for improving UST programs were made by the Blue Ribbon Panel on oxygenates in gasoline?
- Panel Findings - Executive Summary and Recommendations Final, July 27, 1999 (12 pp, 34K, About PDF)
- Achieving Clean Air and Clean Water: The Report of the Blue Ribbon Panel on Oxygenates in Gasoline September 15, 1999 (191 pp, 481K, About PDF)
- Groundwater Clean-up Levels for Oxygenates at LUST Sites: Current & Proposed
Current groundwater regulations (established or site-specific), forthcoming regulations, states waiting for MCL/Health Advisory, and states with no regulations. This information provided courtesy of Michael Martinson, Delta Environmental Consultants, Inc.- U.S. Map of MTBE Levels (1 pg, 56K, About PDF)
- Table (includes all major oxygenates...ethers and alcohols) (9 pp, 32K, About PDF)
- U.S. Map of TBA Levels (1 pg, 53K, About PDF)
- Characteristics of MTBE (including Physical, Chemical, & Toxicological Properties, and Analytical Methods)
- State Investigation Reports on MTBE a list of known state reports--including the New England Interstate Water Pollution Control Commission's (NEIWPCC) 50-state MTBE survey--with links for downloadling.
- State-by-State Survey of Soil and Groundwater Cleanup Standards the Association for the Environmental Health of Soils (AEHS) conducts an annual survey of state standards for petroleum fuel constituents in soil and groundwater
- ASTSWMO MTBE Newsletters produced by the Leaking Underground Storage Tank Task Force of the Association of State and Territorial Solid Waste Management Officials (ASTSWMO).