Underground Storage Tanks (USTs)

Fuel Oxygenates and USTs

You will need Adobe Reader to view some of the files on this page. See EPA’s About PDF page to learn more.Though their use is decreasing, fuel oxygenates are used as a fuel additive and octane enhancer in reformulated gasoline, oxygenated fuel, and premium grades of unleaded gasoline. Water-quality criteria for fuel oxygenates to protect aquatic life have not been established. Available data indicates the presence of MTBE in drinking water. However, limited or no data are available for any other fuel oxygenate.

The major source of groundwater contamination with fuel oxygenates is releases from USTs. In addition to USTs, there are many other potential sources of fuel oxygenate contamination, such as gasoline spills to ground and surface waters, recreational water craft releasing unburned fuel to surface waters, and urban and industrial runoff and wastewater discharges. The public can assist in helping to prevent fuel oxygenate contamination by following safe fuel handling practices.

EPA is continuing to study both the potential health effects and the occurrence of fuel oxygenates, and some oxygenates are included on a list of contaminants (Contaminant Candidate List) for which EPA is considering setting drinking water standards.

About Fuel Oxygenates

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Background Information

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Policy

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Programs

  • Areas Participating in the Oxygenated Gasoline Program (PDF) Exit (12 pp, 136 K) 1999.
    Prepared by the U.S. Department of Energy's Energy Information Administration, this Web page provides state-by-state information on oxygenated gasoline program participation and links to additional resources and regulations.
  • California Reformulated Gasoline Program Exit
    Prepared by the California Environmental Protection Agency, this Web page provides detailed information about the state of California's Gasoline Program, which aids the adoption of regulations that produce the most cost-effective combinations of control measures on motor vehicles and motor vehicle fuels.
  • Program Summary: Research on Oxygenates Added to Gasoline Exit 2004.
    Prepared by the Health Effects Institute, this Web page provides summary information on an oxygenate research program which has funded several toxicologic studies to evaluate metabolism and toxicokinetics of ethers such as MTBE, ETBE, and TAME.
  • Monitoring the Occurrence of Unregulated Drinking Water Contaminants
    Prepared by EPA, this Web page presents information on the Unregulated Contaminant Monitoring Program, which collects data for contaminants suspected to be present in drinking water, but that do not have health-based standards set under the Safe Drinking Water Act (SDWA).

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Standards

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Organizations

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Characteristics and Identification of Oxygenates

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Oxygenate Identification

Oxygenate Names CAS # Chemical Formula Molecular Weight
Methanol Methyl alcohol
Carbinol
Methylol
Methyl Hydroxide
Monohydroxy methane
Wood alcohol
67-56-1 CH40

CH3-0H

32.042
Ethanol Ethyl alcohol
Anhydrol
Alcohol
Methyl carbinol
Ethyl hydrate
Ethyl hydroxide
Denatured alcohol
Grain alcohol
64-17-5 C2H60

CH3CH2-0H

46.069
TBA Tertiary-butyl alcohol
Tert-butyl alcohol
T-butyl alcohol
2-Methyl-2-propanol
1,1-Dimethyl ethanol
Trimethyl carbinol
2-Methylpropan-2-ol
Tert-butanol
T-butyl hydroxide
Trimethyl methanol
Dimethyl ethanol
Methyl-2-propanol
75-65-0 C4H100

(CH3)3C-OH

74.122
MTBE Methyl tertiary-butyl ether
Methyl tert-butyl ether
Methyl t-butyl ether
2-Methoxy-2-methylpropane
1634-04-4 C5H120

CH3-O-C(CH3)3

88.149
DIPE Diisopropyl ether
Diisopropyl oxide
2-isopropoxy propane
Isopropyl ether
2,2'-oxybispropane
108-20-3 C6H140

(CH3)2CH-O-CH(CH3)2

102.18
ETBE Ethyl tertiary-butyl ether
Ethyl tert-butyl ether
2-methyl-2-ethoxypropane
Tert-butyl ethyl ether
Ethyl tert-butyl oxide
2-ethoxy-2-methylpropane
637-92-3 C6H140

CH3CH2-O-C(CH3)3

102.18
TAME Tertiary-amyl methyl ether
Tert-pentyl methyl ether
Butane, 2-methoxy-2-methyl
2-Methoxy-2-methyl butane
Methyl 1,1-dimethyl propyl ether
Methyl tert-amyl ether
Methyl 2-methyl-2-butyl ether
994-05-8 C6H140

C2H5C(CH3)2-O-CH3

102.18
n-Butanol 1-butanol
n-butyl alcohol
proplycarbinol
butanol
butan-1-ol
butyl hydroxide
1-hydroxybutane
methylolpropane
proplymethanol
butalcohol
butylhydrate
butyric alcohol
butyryl alcohol
71-36-3 CH3(CH2)2CH2OH
C4H9OH
C4H10O
74.12

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Oxygenate Properties

Oxygenate Pure Phase Solubility (mg/L) log Koc (log l/kg) Vapor Pressure
(mm Hg)
Henry's Law Constant
(dimensionless)
Specific Gravity
Methanol miscible 0.44 - 0.92 121.6 0.00011 0.791
Ethanol miscible 0.20 - 1.21 49 - 56.5 0.00021 - 0.00026 0.789
TBA miscible 1.57 40 - 42 0.00048 - 0.00059 0.786
MTBE 43,000 - 54,300 1.0 - 1.1 245 - 256 0.023 - 0.12 0.741
DIPE 2,039 - 9,000 1.46 - 1.82 149 - 151 0.195 - 0.41 0.724
ETBE 26,000 1.0 - 2.2 152 0.11 0.7519
TAME 20,000 1.3 - 2.2 68.3 0.052 0.764
n-Butanol 74,000 0.84 7 0.000361 0.81

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Methanol

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Ethanol

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Tert-Butyl Alcohol (TBA)

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Diisopropyl Ether (DIPE)

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Ethyl Tert-Butyl Ether (ETBE)

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Tertiary-Amyl Methyl Ether (TAME)

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N-Butanol

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Assessment, Characterization, Analysis, Remediation, and Treatment

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Assessment, Characterization, and Analysis

Non-Electronic Resources

  • Milkey, N.E. Site Assessment for Gasoline Spills and Leaks. Soil Sediment & Groundwater. July/August 2002.
    This article discusses strategies for the evaluation of the underlying stratigraphy, affected media, and potential migration pathways conducted during site assessments.

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Remediation and Treatment

Bioremediation, Phytoremediation, and Natural Attenuation

Technologies

Workshops and Symposia

  • Oxygenate Contamination: Workshop Report (PDF) Exit (228 pp, 10.3 MB) 2000.
    This report prepared by National Water Research Institute, presents the outcome of a workshop to identify, prioritize, and discuss the most important issues in oxygenate contamination and remediation.

Non-Electronic Resources

  • Wilson, R.D., M. Schirmer, C.N. Naas, A. Smith, C. Smith, K.M. Scow, M.R. Hyman, and D.M. Mackay. Laboratory-Scale Evaluation of In Situ Aerobic MTBE Biodegradation Options for Vandenberg Air Force Base, California. 1999. Proceedings of the 2000 Petroleum Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Detection, and Remediation. Houston, Texas November 17-19, 1999.

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Health, Safety, and Handling

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Health and Safety


Handling and Use

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State Reports

California

Multi-State

New York

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Fate and Transport

  • Diving Plumes and Vertical Migration at Petroleum Release Sites (PDF) Exit (4 pp, 60 K) Undated.   
    Published in L.U.S.T. Line, a technical newsletter for underground storage tank stakeholders, this article presents information on diving plumes at petroleum release sites. Geology, hydrology, land use, assessment, and a case study are discussed and a link is provided to a plume diving calculator.
  • Evaluation of the Impact of Fuel Hydrocarbons and Oxygenates on Groundwater Resources Exit 2004.
    Published in Environmental Science & Technology, this paper presents the results of a study evaluating the potential for groundwater resource contamination by fuel hydrocarbons and oxygenates including TBA, TAME, DIPE, ETBE, and MTBE. Occurrence, distribution, and spatial extent in ground water beneath leaking underground storage tanks are discussed.

Non-Electronic Resources

  • Cowan, R.M., and K. Park. Biodegradation of the Gasoline Oxygenates MTBE, ETBE, TAME, TBA, and TAA by Aerobic Mixed Cultures. 1996. Proceedings of the 28th Mid Atlantic Industrial and Hazardous Waste Conference, Buffalo, New York, July 15-17, 1996. 523-530.
  • Suidan, M.T., M. Esperanza, M. Zein, P. McCauley, R.C. Brenner, and A.D. Venosa. Kinetics of MTBE Biodegradation. Challenges in Biodegradation of Trace Organic Contaminants - Gasoline Oxygenates and Sex Hormones 2005. Water Environment Research 77(1): 4-11.

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