Introduction

EPA’s underground storage tank (UST) regulations require that tank systems are compatible with the substances stored in them. The use of alternative fuels in the United States is growing, and federal mandates require a significant increase in biofuels production. Many retail facilities, such as gas stations, and private fueling facilities already store and dispense ethanol and biodiesel in their UST systems. Ethanol and biodiesel are commonly blended with gasoline and diesel, respectively, and are referred to by their biofuel percentage of the blend: E10, E15, or B20. These fuels are also available in some retail markets as non-blended biofuels E98 or B100. The development and availability of other alternative fuels, such as isobutanol, are growing rapidly. 

Each alternative fuel or alternative fuel blend has unique chemical characteristics that may be different from those of purely petroleum derived gasoline or diesel fuel. Those chemical characteristics may affect how the fuel interacts with UST system materials. Some materials in some USTs may actually not perform as intended if storing certain fuels or blends and may be incompatible with those fuels. If UST materials are not compatible with substances stored in USTs, releases to the environment can occur. Prior to storing alternative fuels, UST owners and operators should be aware of potential issues and regulations to ensure fuels are stored safely in USTs. 

• 2015 Compatibility Requirements
• 2011 Guidance on Demonstrating Compatibility

2015 Compatibility Requirements

In 2015, EPA revised the underground storage tank (UST) regulations. See below for the 2015 requirements.

Owners and operators must use an UST system made of or lined with materials that are compatible with the substance stored in the UST system.

Compatibility is the ability of two or more substances (for example the tank or piping material and petroleum) to maintain their respective physical and chemical properties upon contact with one another. These substances need to remain compatible for the design life of the tank and under conditions likely to be encountered in the UST.

Beginning on October 13, 2015 owners and operators must notify their implementing agency at least 30 days prior to switching to one of the following:

• Regulated substances containing greater than 10 percent ethanol;
• Regulated substances containing greater than 20 percent biodiesel; or
• Any other regulated substance identified by the implementing agency.

This notification gives the implementing agency an opportunity to inquire about the compatibility of the UST system before the owner and operator begins storing the regulated substance.

In addition, owners and operators storing one of these regulated substances must meet one of the following:

• Demonstrate compatibility of the UST system (this includes the tank, piping, containment sumps, pumping equipment, release detection equipment, spill equipment, and overfill equipment) by using one of the following options:
  • Certification or listing of UST system equipment or components by a nationally recognized, independent testing laboratory for use with the regulated substance stored
  • Equipment or component manufacturer approval – this approval must be in writing, indicate an affirmative statement of compatibility, specify the range of biofuel blends the equipment or component is compatible with, and be from the equipment or component manufacturer
• Use another option determined by the implementing agency to be no less protective of human health and the environment than the two options above.

Owners and operators must maintain records that document compliance with the compatibility requirement if they store regulated substances containing greater than 10 percent ethanol, greater than 20 percent biodiesel, or any other regulated substance identified by the implementing agency. These records must be maintained for as long as the UST system is used to store one of these regulated substances.

2011 Guidance on Demonstrating Compatibility

EPA's 2011 guidance provides options for UST owners and operators to use in complying with the federal compatibility requirement for UST systems storing gasoline containing greater than 10 percent ethanol or diesel containing greater than 20 percent biodiesel.

• Guidance on Compatibility of UST Systems with Ethanol Blends Greater Than 10 Percent and Biodiesel Blends Greater Than 20 Percent
  • July 5, 2011 Federal Register notice includes general information, background, response to public comments, and the guidance. 
  • August 3, 2011 Federal Register corrects a minor typographical error.
  • Biofuels Compatibility Resources provides information to help determine if equipment and components installed in UST systems are compatible with biofuels.

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For more information, contact Ryan Haerer at haerer.ryan@epa.gov or 703-347-0151.

About Alternative Fuels

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These resources provide general information about biodiesel and ethanol.

• Biodiesel and biodiesel blends
• Ethanol and ethanol blends

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Biodiesel and Biodiesel Blends

• Alternative Fuels Storage Information and Links
  Prepared by the Steel Tank Institute, this Web page provides links to alternative fuels storage resources from federal, state, and nongovernmental agencies.
• Biodiesel Blends for Fueling Diesel Engines (PDF) (2 pp, 135 K) 
  Published by University of Missouri Extension in the MU Guide, this article provides an overview of biodiesel, in addition to information on production, storage, and safety.
• Biodiesel Facts
  This fact sheet, developed by the Iowa Renewable Fuel Association, presents a list of biodiesel facts.
• Biodiesel Handling and Use Guide (PDF) (56 pp, 1.6 MB)
  This comprehensive guide, developed by the National Renewable Energy Laboratory, presents detailed information on health and safety, handling, equipment compatibility, conversion of tanks, and other topics related to biodiesel.
• Biofuels: Release Prevention, Environmental Behavior, and Remediation (157 pp, 3.6 MB)
• California Biodiesel Multimedia Evaluation – Final Tier I Report (PDF) (98 pp, 2.4 MB)
  This multimedia assessment provides the state of California with the information needed to allow informed decisions in the impact of biodiesel. Chapters 1, 2, 4, and 8 contain information about biodiesel.
• Clarification of Regulations Applying to Biodiesel-E Stored in Underground Storage Tank Systems (PDF) (3 pp, 44 K)
  Prepared by the California State Water Resources Control Board, this memorandum clarifies state regulations pertaining to storing biodiesel in USTs.
• Fact Sheet: Biodiesel and Underground Storage Tank Systems (PDF) (2 pp, 100 K)
  This fact sheet, developed by the Oregon Department of Environmental Quality, provides information on biodiesel and its potential incompatibility with standard UST systems. Steps to be taken prior to conversion of tanks for biodiesel use are outlined.
• The USTs and LUSTs of Biodiesel (PDF) (28 pp, 662 K)
  This article in L.U.S.T.Line, a technical newsletter for UST stakeholders, presents information on the chemical properties, toxicity, emissions, biodegradation, materials compatibility, regulations, and production of biodiesel. (See pages 11-16 and 27)

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Ethanol and Ethanol Blends

• Alternative Fuel Driver Training Companion Manual (PDF) (24 pp, 1.4 MB)
  Developed by the National Renewable Energy Laboratory, this training guide includes background information on biodiesel and ethanol as well as guidance on storage, handling, safety, and tank conversion.
• E85: An Alternative Fuel
  Developed by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy as part of the E85 Fleet Toolkit, this Web page includes information and links to E85 fuel resources.
• E85 Fuel Ethanol: Industry Guidelines, Specifications, and Procedures (PDF) (26 pp, 236 K)
  This guide, developed by the Renewable Fuels Association, presents comprehensive information on ethanol standards, equipment compatibility and conversion, handling and safety, quality assurance, and tax incentives. (See page 31)
• Handbook for Handling, Storing, and Dispensing E85 (PDF) (44 pp, 1.0 MB)
  Developed by the National Renewable Energy Laboratory, this handbook provides extensive information on standards, storage, health and safety, and other topics relating to E85.
• Regulatory Interpretation; Regulatory Status of E85 Tanks (PDF)(62 pp, 1.0 MB)
  EPA's November 2007 memorandum to regions and states responds to questions from states on the regulatory status of underground storage tanks (USTs) containing E85 (a blend of approximately 85 percent ethanol and 15 percent gasoline).
• Ten Things Missouri Tank Owners And Operators Need To Know About Ethanol (PDF) (2 pp, 246 K)
  Adapted from a Renewable Fuels Association publication by the Missouri Petroleum Storage Tank Insurance Fund, this fact sheet contains information on storing ethanol blends in USTs and includes a store operator checklist.

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Ensuring Compatibility of Alternative Fuels with USTs and Converting Equipment to Store Alternative Fuels

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These resources provide information regarding UST system compatibility with biodiesel, ethanol, and other alternative fuels. They also provide information on how to correctly convert UST systems and store biodiesel, ethanol, and other alternative fuels.

• Alternative Fuel Storage Guidelines for UST Systems (PDF) (2 pp, 133 K)
  Prepared by the North Carolina Department of Environment and Natural Resources, this brochure provides UST stakeholders with information on materials compatibility, regulatory status, and conversion of tanks for storing ethanol and biodiesel.
• Alternative Fuels Equipment Compatibility Guide
  This online database, developed by the Petroleum Equipment Institute, contains information on equipment compatibility with ethanol- and biodiesel-blended fuels. Listings include product specifications and links to manufacturers.
• Alternative Fuels Storage Information and Links
  Prepared by the Steel Tank Institute, this Web page provides links to alternative fuels storage resources from federal, state, and nongovernmental agencies.

• Compatibility of biodiesel and biodiesel blends
• Compatibility of ethanol and ethanol blends
• Converting equipment to ensure compatibility

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Compatibility of Biodiesel and Biodiesel Blends

• Brief Overview to Fuels and Materials Compatibility (PDF) (81 pp, 1.9 MB)
  This presentation, from the 2007 National Tanks Conference, provides extensive information on UST system compatibility with petroleum, biodiesel, and ethanol.
• FAQs on the Storage, Handling and Sale of B2
  This Web page, developed by the Minnesota Department of Agriculture, presents information on Minnesota's requirement that diesel fuel sold in Minnesota contain at least 2 percent biodiesel.
• Materials Compatibility (PDF) (4 pp, 156 K)
  This fact sheet, prepared by the National Biodiesel Board, provides guidance on UST system compatibility with biodiesel blends and includes several tables of material compatibility ratings.
• STI/SPFA Announces the Release of a Final Report for Testing for Compatibility of Steel with Biodiesel (PDF) (2 pp, 16 K)
  This press release, prepared by the Steel Tank Institute and Steel Plate Fabricators Association (STI/SPFA), announces the publication of a report on testing of steel UST compatibility with biodiesel.

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Compatibility of Ethanol and Ethanol Blends

• Analysis of Underground Storage Tank System Materials to Increased Leak Potential Associated with E15 Fuel (PDF) (48 pp, 1.3 MB)
  Published by the Oak Ridge National Laboratory (ORNL), this report covers whether or not increased leak potential will result from the transition to E15 fuels in UST systems based on compatibility studies of metals, plastics, fiberglass resins, elastomers, and pipe thread sealants.
• Compatibility and Permeability of Oxygenated Fuels to Materials in Underground Storage and Dispensing Equipment (PDF) (80 pp, 310 K)
  This report, prepared for the California State Water Resources Control Board, presents information on the compatibility and permeability of oxygenated fuels to UST equipment.
• Converting Existing Underground Storage Tank (UST) Systems to Ethanol Compatible (PDF) (5 pp, 134 K)
  Prepared by the Iowa Department of Natural Resources, this fact sheet provides guidance on equipment compatibility and conversion of USTs for storing ethanol.
• E15 Retailer Handbook (PDF) (44 pp, 2.1 MB)
• E85 Fuel Ethanol: Industry Guidelines, Specifications, and Procedures (PDF) (26 pp, 236 K)
  This guide, developed by the Renewable Fuels Association, presents comprehensive information on ethanol standards, equipment compatibility and conversion, handling and safety, quality assurance, and tax incentives. (See page 21)
• Fuel Ethanol and Underground Storage Tank Systems (PDF) (2 pp, 60 K)
  Developed by the Oregon Department of Environmental Quality, this fact sheet presents guidance on equipment compatibility and the conversion of USTs for storing ethanol.
• Historical Timeline for Fiberglass Storage Tank Ethanol Compatibility (PDF) (1 pg, 20 K)
  The Wisconsin Department of Commerce's Bureau of Storage Tank Regulation created this diagram, which outlines dates of historical import relating to ethanol storage tank compatibility.
• Intermediate Ethanol Blends Infrastructure Materials Compatibility Study (PDF) (109 pp, 2.1 MB) 
  Published by the ORNL, this report covers the compatibility of elastomers, metals, and sealants with intermediate ethanol blends.
• Letter to Licensed Installers re: Checklist for Storing and Dispensing E-blend Fuels and New UL 971 Standards (PDF) (2 pp, 104 K)
  Prepared by the Iowa Department of Natural Resources, this letter presents guidance for Iowa licensed installers of UST equipment on new requirements for evaluating systems for ethanol blend compatibility.
• Matrix of Pipe Monitoring Applications
  The California Environmental Protection Agency State Water Resources Control Board prepared this Web page to provide guidance on the regulation of piping standards in UST systems.
• National Ethanol Vehicle Coalition (PDF) (5 pp, 72 K)
  This is a listing of E85-compatible tank equipment and manufacturers, prepared by the National Ethanol Vehicle Coalition.
• Preparing Your Dispensing System for Ethanol Blended Motor Fuel (PDF) (2 pp, 122 K)
  Developed by the Wisconsin Department of Commerce, this brochure provides guidance on equipment compatibility and the conversion of USTs for storing ethanol.
• Underground Storage Tank Systems and Ethanol Compatibility (PDF) (3 pp, 24 K)
  Developed by the Indiana Department of Environmental Management, this fact sheet provides guidance on equipment compatibility and the conversion of USTs for storing ethanol.

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Converting Equipment to Ensure Compatibility

• Checklist of Installing or Converting Equipment to Dispense E85 (PDF) (1 pg, 86 K)
• This checklist, developed by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy as part of the E85 Fleet Toolkit, outlines steps to be taken by owners and operators prior to tank conversion for E85 use.
• Renewable Fuels Association Model E15 Misfueling Mitigation Plan (PDF) (20 pp, 95 K)
• Companies may choose to adopt this model plan and submit it to EPA for approval in meeting the requirement for a misfueling mitigation plan under the E15 partial waivers.
• Preparing Your Dispensing System for Ethanol Blended Motor Fuel (PDF) (2 pp, 122 K)
• Developed by the Wisconsin Department of Commerce, this brochure provides guidance on equipment compatibility and the conversion of USTs for storing ethanol.
• Underground Storage Tank Systems and Ethanol Compatibility (PDF) (3 pp, 24 K)
  Developed by the Indiana Department of Environmental Management, this fact sheet provides guidance on equipment compatibility and the conversion of USTs for storing ethanol.

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Safety and Handling of Alternative Fuels; Cleaning Up Releases

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These resources provide information on safety, handling, releases, and cleaning up releases of alternative fuels.

• Biodiesel and biodiesel blends
• Ethanol and ethanol blends

The following links exit the site Exit

• Environmental and Safety Information (PDF) (1 pg, 24 K)
  This fact sheet, developed by the National Biodiesel Board, presents information on biodiesel's biodegradability, oral and skin toxicity, aquatic toxicity, and flash point.
• Toxicology, Biodegradability and Environmental Benefits of Biodiesel (PDF) (5 pp, 13 K)
  This paper presents the results of research conducted at the University of Idaho's Department of Biological and Agricultural Engineering on the toxicity, biodegradability, and emissions of biodiesel.
• Biodiesel Material Safety Data Sheet (PDF) (3 pp, 43 K)
  This Material Safety Data Sheet, prepared by the National Biodiesel Board, presents detailed information on storing, handling, safety, and regulatory status of biodiesel.
• Fuel Quality and Performance Guide (PDF) (20 pp, 463 K)
  Created by the Iowa Renewable Fuels Association, this guide provides detailed advice on buying, storing, and handling biodiesel. It includes ASTM specifications, a list of additional resources, and a troubleshooting checklist.
• Keeping Water Out of Your Storage System (PDF) (13 pp, 192 K)
  Prepared by the Steel Tank Institute, this resource discusses ways in which water can enter an underground storage tank (UST) system, economic impacts of water intrusion, and methods for the protection of UST systems against water intrusion. Microbial contamination and other issues related to storing ethanol and biodiesel blends are discussed.
• Phytoremediation of Petroleum Diesel and Biodiesel Contaminated Soil
  This Web page contains an abstract summarizing research conducted by the USDA Natural Resources Conservation Service in partnership with the Illinois State University Department of Agriculture regarding remediation of petroleum diesel- and biodiesel-contaminated soil. The Web page includes a link to download a PDF document with additional details on the research.

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Ethanol and Ethanol Blends

• Advisory Guidance: Emergency Response Involving Ethanol and Gasoline Fuel Mixtures (PDF) (2 pp, 135 K)
  This fact sheet, developed by the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration, presents information on safety procedures and chemical properties of ethanol blends.
• A Circle Vicious: What Do We Know About the Other Oxygenates?
  Published in L.U.S.T.Line, a technical newsletter for underground storage tank (UST) stakeholders, this article presents information on ether oxygenates and ethanol. Remediation technologies for ethanol cleanup are discussed.
• E85 Safety Concerns
  Developed by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy as part of the E85 Fleet Toolkit, this Web page includes information and links to resources pertaining to E85 safety concerns.
• International Chemical Safety Card
  Vermont Safety Information Resources, Inc. developed this Web page which includes detailed ethanol safety information including symptoms, first aid, firefighting strategies, and routes of exposure.

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Corrosion of Metal Components in USTs Storing Alternative Fuels or Alternative Fuel Blends Including Ultra-Low Sulfur Diesel