v-/EPA
United States
Environmental Protection
Agency
UST System Compatibility With Biofuels
EPA 510-K-20-001
July 2020
Printed on Recycled Paper
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EPA wrote this booklet for owners and operators of underground storage tanks (USTs).
This booklet describes the 2015 revised federal UST regulation. Many states and territories
(referred to as states in this booklet) have state program approval from EPA. To find a list of states
with state program approval,
If your UST systems are located in a state with state program approval, your requirements may be
different from those identified in this booklet. To find information about your state's UST
regulation, contact your implementing agency or visit its website. You can find links to state UST
websites at
If your UST systems are located in a state without state program approval, both the requirements
in this booklet and the state requirements apply to you.
If your UST systems are located in Indian country, the requirements in this booklet apply to you.
Publications About UST Requirements
Download or read UST System Compatibility With Biofuels and other UST documents on EPA's
underground storage tank website atE
Also download and read online UST documents on the National Service Center for
Environmental Publications (NSCEP) website at
www.epa.gov/nscep
Image credits:
MVI Field Services (inspector on cover)
Highland Tank & Manufacturing Company (steel tanks on cover and in headers)
OPW (fill sump on cover)
u
UST System Compatibility With Biofuels
July 2020
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Contents
What Is This Booklet About? ........I
How Do You Meet The 2015 Compatibility Requirements? 11
Upgrading Equipment To Meet Compatibility Requirements For Storing Biofuels 16
Resources For More Information ......17
Appendices A-l
Disclaimer
This booklet provides information about underground storage
tank (UST) system compatibility. The booklet is not a substitute
for U.S. Environmental Protection Agency regulations nor is it a
regulation itself—it does not impose legally binding requirements.
For regulatory requirements regarding UST systems, refer to the
federal regulation governing UST systems (40 CFR part 280).
in
UST System Compatibility With Biofuels
July 2020
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What Is This
Booklet About?
Releases from USTs can
threaten human health and
the environment,
contaminating both soil and
groundwater. As of 2020,
more than 557,000 UST
releases have been
confirmed.
Ensuring UST systems are
compatible with the
substances they store is
essential to preventing
releases of regulated
substances to the
environment.
As of 2020, the U.S. Environmental Protection Agency
(EPA) regulates over one-half million underground storage
tank (UST) systems that contain petroleum or hazardous
substances. EPA's Office of Underground Storage Tanks
was formed in response to the discovery in the early 1980s
that thousands of USTs had leaked and contaminated
groundwater supplies in the United States. While the number
of annual releases since that time has gone down
significantly, releases of petroleum from USTs into the
environment are still a significant concern today.
Underground storage tanks form a crucial part of our
country's fueling infrastructure. It is important for USTs to
be constructed, maintained, and operated in a manner such
that petroleum and other regulated substances are stored
safely. EPA developed the UST regulation to help owners
and operators meet those goals.
How EPA Defines Biofuels In This Booklet
Ethanol and biodiesel are commonly called biofuels in the
fuel industry. Ethanol is routinely mixed and stored with
gasoline in concentrations of 10 percent ethanol (E10).
Biodiesel is routinely mixed and stored with diesel in
concentrations up to 20 percent biodiesel (B20). E10 is sold
at nearly every gas station in the United States.
Throughout this booklet, however, EPA uses the term biofuel
to refer only to substances listed in the 2015 UST regulation
that require additional actions of owners and operators
pertaining to compatibility. Those substances are:
About half
of the United States
population uses
groundwater as a source
of drinking water.
• gasoline blends containing greater than 10 percent
ethanol;
• diesel blends containing greater than 20 percent
biodiesel;
• or any other substance identified by the implementing
agency now or in the future.
Ethanol and biodiesel have significantly increased their
volume share of the total national vehicle fuel market over
the last 15 years. Other new fuels made from renewable
sources, including renewable diesel and isobutanol, have
l
UST System Compatibility With Biofuels
July 2020
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entered the market in limited quantities. More biofuels and
other new renewable fuels are likely to enter the market in the
next decade.
Ensuring compatibility of UST systems with the fuel stored—
knowing the materials that make up the UST system will
maintain their respective chemical and physical properties
when in contact with the substance they are storing—is
essential. Storing fuel in an incompatible UST system may
jeopardize the integrity of the UST system and cause a release
to the environment.
All UST systems must be
compatible with the
regulated substances they
store. EPA's June 2019
compliance advisory alerts
UST facility owners and
operators about
compatibility requirements
at 40 CFR 280.32 in the 2015
UST regulation:
www.epa.gov/ust/complian
ce-advisories-about-2015-
underground-storage-tank-
regulation
UST System Compatibility With Biofuels
July 2020
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This booklet will help you understand what you need to do in
order to meet the 2015 UST compatibility requirements when
storing biofuels and petroleum-biofuel blends and minimize
the risk of a release from your UST system due to
incompatibility.
Why Is Compatibility Important?
In an UST system, the regulated substances stored must not
interact with the materials comprising the system in any way that
would cause the material to change its performance. USTs contain
many components made of different materials. If any of these
materials are incompatible with the regulated substance stored and
even temporarily lose their manufactured properties such as shape
or flexibility, the UST system may fail to contain the substance.
This could lead to a release to the environment and possibly a
failure to detect the release. Examples of observed incompatibility
between fuels stored and UST materials include equipment or
components such as tanks, piping, or gaskets and seals that have
become brittle, elongated, thinner, or swollen when compared with
their as-installed conditions. Sealants or pipe dope used to hold
UST connections together could dissolve or become leaky when in
contact with incompatible fuel blends.
Compatibility In The 1988 UST Regulation
EPA has required UST systems to be compatible with the
substance stored in them since the 1988 UST regulation.
Compatibility is required for as long as the UST system is used to
store regulated substances. From the 1988 UST regulation:
• You must use an UST system made of or lined with
materials compatible with the regulated substance
stored in the UST system.
However, the United States' fuel supply has changed significantly
since 1988 and there has been an exponential growth of the use of
biobased fuels. All biobased fuels are made from some type of
renewable resource. But these renewable resources can be
processed through a variety of fuel production processes and result
in many types of finished fuels that have different chemical
characteristics. One category of biobased fuels—biofuels—are the
main focus of this booklet.
Biodiesel is commonly blended into diesel and ethanol into
gasoline. The resulting blended fuels stored in USTs usually
contain 20 percent biodiesel (B20) or less or 10 percent ethanol
(E10) or less of the petroleum based fuel volume. However, in
certain percentages, diesel-biodiesel or gasoline-ethanol blends are
more aggressive toward certain materials used in UST system
UST System Compatibility With Biofuels
July 2020
Remember, compatibility
with the substance stored is
required for all UST systems.
Equipment incompatible
with the fuel stored could
harden, soften, swell, or
shrink and could lead to a
release of fuel to the
environment.
The 2015 UST regulation
clarifies methods for
demonstrating compatibility
for fuels containing greater
than 10 percent ethanol or
greater than 20 percent
biodiesel. However,
implementing agencies may
have different compatibility
requirements for storing
biofuels, so it is important to
contact them before storing
higher blends of biofuels.
Most currently installed UST
systems have at least some
components that may not be
compatible with fuel blends
containing more than 10
percent ethanol or more
than 20 percent biodiesel.
However, components
compatible with higher
blends are now available. If
you choose to upgrade your
UST system, remember to
require that your installer
use compatible equipment.
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construction than petroleum based fuel with biodiesel or ethanol in
lesser amounts. Most UST components are compatible with E10
or B20. But some older, existing UST components are
incompatible with any blends of ethanol, and some are
incompatible with biodiesel blends above B5. In addition to the
compatibility requirement above, the 2015 UST regulation
includes requirements for owners and operators of certain UST
systems to help ensure UST systems are compatible with biofuels
prior to storing them.
Why EPA Updated The Compatibility Requirements In The
2015 UST Regulation
The fuel supply in the United States is constantly evolving.
Ensuring compatibility prior to storing any regulated substance in
an existing or new UST system is important, because your UST
system may have been built with components that were not
intended for use with the biofuel you wish to store today.
One example that demonstrates the importance of knowing the
compatibility of your UST system involves ethanol, an oxygenate
commonly blended into fuel to improve engine efficiency and
emissions. Ethanol became widely used in the United States in
blends up to 10 percent by volume in the mid-2000s when methyl
tertiary butyl ether (MTBE), an oxygenate introduced to enhance
octane as lead was phased out of gasoline, was itself phased out
due to environmental concerns.
Research has shown that some materials, such as some polymers
and elastomers commonly used in UST system construction prior
to ethanol becoming widely used, may swell and lose their shape
when in contact with ethanol. In an UST system, these materials
may be intended to create a seal between components, but if
damaged, may not perform correctly and could lead to a release of
a regulated substance to the environment. These materials may
show the most swelling in gasoline blended with ethanol greater
than 10 percent by volume. Other regulated substances, such as
higher concentrations of biodiesel, may also present compatibility
considerations for these or other UST components.
UST systems are designed for long lifespans and are normally not
frequently replaced. As the fuel supply changed to incorporate
more ethanol, UST and fuels stakeholders found that some
installed UST systems were incompatible with lower level ethanol
blends. The UST system equipment industry responded to the
increasing use of biofuels and the risks identified by creating
equipment compatible with lower blends of these fuels. Over time,
the industry also began producing equipment compatible with
higher blends of ethanol and biodiesel—those that are generally
more aggressive toward more commonly used UST system
UST System Compatibility With Biofuels
July 2020
Adding any amount of
ethanol to petroleum based
fuels changes how the fuel
interacts with materials.
Blends greater than 10
percent ethanol by volume
show the most ability to
affect the performance of
some materials in older UST
systems. Equipment made
with only materials that are
compatible with these fuels
are available, but sometimes
cost more.
These photos of UST system
material incompatibility were
not caused by biofuels, but
provide good examples of
incompatibility. Top to
bottom are pipe elongation,
cracking of the internal tank
lining, and delamination of
product piping (in top left of
the picture.)
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materials. Generally, all new tanks and piping produced today are
compatible with blends of up to 100 percent ethanol and biodiesel.
However, many of the ancillary components available in the
market may still be available in versions not compatible with up to
100 percent biodiesel or 100 percent ethanol. The whole UST
system (which includes but is not limited to tanks, pumps, ancillary
equipment, lines, gaskets, and sealants) needs to be compatible
with the fuel stored to prevent releases to the environment.
Generally, most older and even some newer existing UST systems
are not fully compatible with biofuels and require modification
before storing them. For example, the actual tank is often
compatible with El 5, but some of the connectors and pump
components may not be, and that can lead to leaks. EPA updated
the compatibility requirements in the 2015 UST regulation to
ensure higher bl ends of biofuels are stored only in compatible UST
systems.
The 2015 UST regulation describes the steps UST owners and
operators must take to help protect our health and environment
from potential UST releases due to incompatibility. These steps
will also help you avoid the high cost of cleaning up releases and
possible legal actions that can result if your UST system releases
product to the environment.
Compatibility Of Fuel Dispensers
This booklet describes EPA's
requirements for
compatibility, but your
implementing agency may
have requirements that are
somewhat different or more
stringent than the federal
requirements. Contactyour
implementing agency for its
specific compatibility
requirements. Many
agencies may require
owners who store biofuels
follow different
requirements, which could
include submitting
documents that differ from
the examples provided in
this booklet
By EPA's definition, dispensers are not part of the UST system,
but face the same compatibility concerns and are a critical part of
the fueling system. The 2015 UST regulation does not require
owners and operators to demonstrate the compatibility of
dispensers or associated aboveground equipment. However,
compatibility requirements for these components may exist in
other local regulations, such as the fire code. Owners and
operators should check for these requirements with their
implementing agencies. You will see some discussion of
dispensers in this booklet
Check With Your Implementing Agency
Remember, compatibility for
fuel dispensers and fuel
hoses is important.
Compatibility requirements
for these components may
exist in other local
regulations, such as the
fire code.
Many states, territories, and the District of Columbia (referred to
collectively as states) have state program approval from EPA. To
find a list of states with state program approval, see
www.epa.gov/ust/state-underground-storage-tank-ust-programs.
If your UST systems are located in a state with state program
approval, your requirements may be different from those identified
in this booklet. Check with the state UST program in the state
where your USTs are located.
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If your UST systems are located in a state without state program
approval, both the requirements in this booklet and the state
requirements apply to you.
If your UST systems are located in Indian country, the
requirements in this booklet apply to you.
UST System Compatibility With Biofuels
July 2020
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Compatibility Requirements In The 2015 UST
Regulation
The 2015 UST regulation maintains the requirement that all UST
systems must be made of or lined with materials compatible with
the substance stored in the UST system. Remember that
compatibility extends beyond the fuel tank to the entire system.
The 2015 UST regulation provides clarity to the 1988
compatibility requirement by specifying additional compatibility
requirements for owners and operators wishing to store certain
regulated substances, including gasoline containing more than 10
percent ethanol and diesel containing greater than 20 percent
biodiesel. Research has identified these substances as having a
higher likelihood of incompatibility with many existing UST
systems. By targeting the additional compatibility requirements
toward the specific subset of the UST operating universe with the
highest risk of failure due to incompatibility, the overall risk of
releases will be minimized.
Beginning October 2015, in addition to the 1988 requirement of
ensuring that the UST system is compatible, UST owners and
operators intending to store regulated substances must also meet
these additional compatibility requirements:
Notification
• You must notify your implementing agency at least 30
days before switching to any of the following products:
o Regulated substances containing greater than 10
percent ethanol
o Regulated substances containing greater than 20
percent biodiesel
o Any other regulated substance identified by your
implementing agency
See Appendix 1 for a sample letter for notifying your
implementing agency that you plan to switch to store a biofuel.
www.epa. gov/ust/
underground-storage-tank-
ust-contacts#states
UST System Compatibility With Biofuels
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Note: In this list, pumping
equipment refers to the
equipment used to move the
fuel from the underground
storage tank to the fuel
dispenser. The 2015 UST
regulation does not address
the fuel dispenser itself
because the regulation only
covers equipment at or
under the surface of the
ground. Although not
covered in the regulation or
this booklet, you should
make sure your dispenser is
also compatible with the
substance stored. Check
with your implementing
agency to find out which
department or agency
regulates fuel dispensers in
your area and ensure you
meet all requirements for
fuel dispenser compatibility.
Additionally, owners and operators storing one or more of these
regulated substances must meet the compatibility requirement by
demonstrating compatibility of the system with the fuel or by using
an alternative allowed by the implementing agency.
Meeting The Compatibility Requirement
• If you store any of these substances, you must either:
o Demonstrate that the following UST system
components are compatible with the regulated
substance: tank, piping, containment sumps,
pumping equipment, release detection
equipment, spill prevention equipment, and
overfill prevention equipment
o Use an alternative determined by the
implementing agency to be no less protective of
human health and the environment than
demonstrating that those components are
compatible
An owner and operator may meet the compatibility requirement in
the 2015 UST regulation by showing that each component listed is
approved for use with the biofuel stored.
Some implementing agencies may allow an alternative to
demonstrating compatibility of the components to meet the
compatibility requirement. Although alternatives are available,
they are uncommon. Contact your implementing agency for the
compatibility requirements that apply to your USTs.
Refer to How Do You Meet The 2015 Compatibility Requirements
section beginning on page 11 for more details on these alternatives.
Recordkeeping
• Beginning October 2015, if you store regulated
substances containing greater than 10 percent ethanol,
greater than 20 percent biodiesel, or other substances
identified by your implementing agency, you must keep
records showing that your UST system is compatible
with those substances. If you choose to follow an
alternative determined to be no less protective of human
health and the environment established by your
implementing agency, then you must keep
documentation of adherence to this requirement as
required by the implementing agency's rules. You must
keep these records for as long as you store these
regulated substances.
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B100
The 2015 UST regulation requires these additional steps for any
regulated substance containing more than 10 percent ethanol or 20
percent biodiesel. Pure B100 contains 100 percent biodiesel,
which is more than 20 percent biodiesel; but it is not a regulated
substance and thus is not covered by the regulation
To be regulated, a substance must be petroleum or a CERCLA-
listed hazardous substance. Petroleum is defined to be a complex
blend of hydrocarbons. B100 is 100 percent biodiesel and it is not
a hydrocarbon; that means B100 stored in an UST does not meet
the definition of petroleum. In addition, B100 is not on the
CERCLA list of hazardous substances. Therefore, USTs storing
100 percent biodiesel are not regulated under the 2015 UST
regulation.
EPA understands that most biodiesel is blended with some regular
diesel. If the biodiesel is blended with even a small amount of
diesel, then USTs storing that blend are regulated as petroleum
USTs under the 2015 UST regulation.
Renewable Diesel Fuel
Renewable diesel fuel, which is also called green diesel, is a
biomass-derived transportation fuel suitable for use in diesel
engines. Renewable diesel is distinct from biodiesel. The 2015
UST regulation revised the regulated substance definition to clarify
that UST systems containing petroleum derived from non-crude oil
products are regulated. Although B100 is not a regulated
substance, renewable diesel fuel is.
While renewable diesel is chemically similar to petroleum diesel,
biodiesel is a mono-alkyl ester, which has different physical
properties and hence different fuel specifications. The two fuels
are also produced through very different processes. B100 meets
the requirements of the ASTM International (ASTM) Standard
D6751, Standard Specification for Biodiesel Fuel Blend Stock
(B100) for Middle Distillate Fuels. Renewable diesel, on the other
hand, meets the ASTM D975 specification for diesel fuel, even
though it is produced from biomass.
Renewable diesel does not on its own contain biodiesel.
Sometimes, however, renewable diesel fuel may be blended with
biodiesel and stored at a gas station or other fuel distribution
facility, just as diesel fuel from crude oil is often blended with
biodiesel. An owner or operator storing renewable diesel does not
need to meet the additional requirements for compatibility outlined
in this section, unless that renewable diesel is blended with other
fuels in any formulation with more than 20 percent biodiesel.
UST System Compatibility With Biofuels
July 2020
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Renewable Jet Fuel
Also called biojet or aviation biofuel, renewable jet fuel is a
biomass-derived fuel that can be used interchangeably with
petroleum-based aviation fuel. Certain biojet fuel can be blended
up to 50 percent with conventional commercial and military jet (or
aviation turbine) fuel by following requirements in ASTM's
D7566 specification. Both commercial and military aviation fuel
and renewable jet fuel are regulated substances under the 2015
UST regulation. But an owner or operator storing conventional or
renewable jet fuel need not meet the additional requirements for
compatibility in this section unless they are blended with ethanol
or biodiesel. EPA understands this is unlikely due to technical
requirements of aviation fuels.
UST System Compatibility With Biofuels
July 2020
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How Do You Meet
The 2015 Compatibility
Requirements?
This section explains how to meet the requirements for compatibility when storing biofuels.
Below is a chart of the requirements for the vehicle fuels most commonly stored in UST systems.
The chart is not a complete list of regulated substances which must meet the additi onal
compatibility requirements in the 2015 UST regulation. The chart is a quick guide to help
owners and operators storing regulated vehicle fuels understand which compatibility
requirements they must meet.
Must
Type of regulated
substance
Must be
compatible
with UST
system
Must notify
implementing
agency before
switching to
store this fuel
demonstrate
compatibility
of UST
system with
the substance
being stored
Must keep
these records
for as long as
the substance
is stored
*Must keep
records of
leak detection
performance
claims
Regulated
substances
containing up to 10
percent ethanol.
This includes the fuel
~
~
commonly referred
to as E10.
Regulated
substances
containing up to 20
percent biodiesel.
This includes fuels
~
~
such as diesel fuel,
B5, B10, B20, and
renewable diesel.
Regulated
substances
containing greater
than 10 percent
ethanol. This
~
~
~
includes fuels such
as E15 or E85.
Regulated
substances
containing greater
than 20 percent
diesel, including
fuels such as B50 or
~
~
S
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How Do You Meet The Compatibility Requirements?
Owners and operators must meet the compatibility requirement in
the 2015 UST regulation by demonstrating compatibility of their
UST systems, or by using an alternative that is no less protective
than demonstrating compatibility. An alternative must be allowed
by the implementing agency.
Demonstrating That Your UST System Is Compatible With
Biofuels
Two options are available to demonstrate that your UST system is
compatible with fuels containing greater than 10 percent ethanol or
greater than 20 percent biodiesel.
• Certification or listing of UST system equipment or
components by a nationally recognized, independent testing
laboratory for use with the regulated substance stored; or
• Equipment or component manufacturer approval. This
manufacturer's approval must:
o be in writing,
o indicate an affirmative statement of compatibility,
o specify the range of biofuel blends the component is
compatible with, and
o be from the equipment or component manufacturer
See Appendix 2 for a sample checklist to help owners and
operators determine compatibility of UST systems.
Demonstrating compatibility of an UST system requires first
identifying what equipment is installed as part of your UST
system. Equipment manufacturers should be able to provide
information on the substances for which their equipment is
compatible. Determining the compatibility status of some older
UST equipment or components for which paperwork has been lost
could be challenging, so remember to keep your documentation. If
you cannot determine a component's manufacturer and year or
model of production, you will not be able to demonstrate
compatibility.
In addition to your UST implementing agency, the resources on
page 17 may help identify the compatibility status of your installed
UST system components. EPA anticipates that most older UST
systems will require retrofitting of some equipment with
compatible equipment, if the owners or operators choose to store
higher level biofuel blends in these systems.
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July 2020
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Meeting The Compatibility Requirement Through Use Of An
Alternative Allowed By The Implementing Agency
The 2015 UST regulation allows implementing agencies to
determine alternatives to meet the compatibility requirement for
regulated substances containing greater than 10 percent ethanol,
greater than 20 percent biodiesel, or other substances identified by
the agency.
Although alternatives are available, they are uncommon. Before
allowing an alternative for owners and operators to meet the
requirements in 40 CFR 280.32, implementing agencies must
ensure the alternative is at least as protective of human health and
the environment as the manufacturer's approvals or certifications
or listings by a nationally recognized, independent testing
laboratory for components that demonstrate your UST system is
compatible. Contact your implementing agency for the
compatibility requirements that apply to your USTs.
What Records Must You Keep?
The 2015 UST regulation requires you keep documentation
showing that your system is compatible when storing certain
biofuels:
• Beginning October 2015, if you store regulated
substances containing greater than 10 percent ethanol,
greater than 20 percent biodiesel, or any other
substances identified by your implementing agency, you
must keep records showing that your UST system is
compatible with those substances. You must keep these
records for as long as you store these regulated
substances.
Generally follow this useful
rule of thumb for
recordkeeping: When in
doubt, keep it.
• If you choose to follow an alternative that the
implementing agency determined is no less protective of
human health and the environment, then you must keep
documentation demonstrating compliance with this
requirement as required by the implementing agency's
rules. You must keep these records for as long as you
store these regulated substances.
You should also contact your implementing agency about the
particular recordkeeping requirements that apply to your USTs.
If you repair any component
of your UST system, you must
ensure it is repaired only
with components compatible
with the fuel you store. Keep
repair records because they
help demonstrate
compatibility of your UST
system.
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Compatibility Of Pipe Dope And Sealants
Pipe dope or sealants used anywhere in an UST system must be
compatible with the regulated substance stored in the system. Pipe
dope is used to seal together threaded connections. Sealants are
generally used to seal together non-threaded joints. The 1988 UST
regulation required compatibility for all components of the UST
system and the 2015 UST regulation reiterated that requirement.
EPA did not include pipe dope on the 2015 UST regulation list of
UST system components that owners and operators must
demonstrate to be compatible when storing regulated substances
containing greater than 10 percent ethanol or greater than 20
percent biodiesel. Nonetheless, all components and all pipe dope
in all UST systems must be compatible with substances stored.
Pipe dope that is compatible with ethanol blends higher than E10 is
available, but much of the pipe dope on the market is not. If
storing or considering storing greater than E10, owners and
operators should explicitly check to ensure the pipe dope on their
UST system connections is compatible; installers and installation
records are sources for that information. Ensuring UST systems
are compatible with the pipe dope and sealant used is critical
because EPA thinks that pipe dope used prior to 2007 is probably
not compatible with ethanol blends greater than 10 percent. Most
older pipe dope was soft set pipe dope and not intended to be used
with ethanol blends over 10 percent.
Higher-ethanol compatible pipe dope was available beginning
around 2007. Despite that, UST systems installed then and since
to store lower levels of ethanol, such as E0 or E10, probably have
pipe dope compatible only with lower levels of ethanol. Storing
greater than 10 percent ethanol in those UST systems means the
pipe dope is incompatible. Because higher-ethanol compatible
pipe dope is more expensive, pipe dope compatible only with
lower levels of ethanol may have been used, rather than higher-
ethanol compatible pipe dope.
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Compatibility Versus Functionality For Release
Detection Equipment
Compatibility of equipment, or the ability of two or more
substances to maintain their respective chemical and physical
properties when in contact with one another, is different from
functionality of equipment. Functionality is the ability of
equipment to perform the job it was designed to do.
Some biofuels could potentially affect both the compatibility and
functionality of UST equipment. Biofuels containing ethanol can
affect the amount of water absorbed or retained in fuel. Some
types of release detection equipment rely on sophisticated
technologies to evaluate product levels in underground storage
tanks. These methods for leak detection could be adversely
affected by ethanol's ability to dissolve and mix with water, which
could prevent them from functioning as designed as a release
detection device in fuels blended with ethanol. Owners and
operators should ensure that their release detection equipment is
both compatible with the biofuel stored and meets EPA's release
detection performance standards for use with the biofuel.
Remember, compatibility is
different from functionality.
You can use testing protocols
to evaluate the functionality
of various release detection
technologies in different
regulated substances.
EPA released in May 2019 updated protocols, Standard Test
Procedures for Evaluating Various Leak Detection Methods', these
help manufacturers verify that their leak detection equipment
meets federal performance standards for functionality. The
updated protocols account for new fuels and technologies. You
can access the protocols at www.epa. gov/ust/standard-test-
procedures-evaluating-various-leak-detection-methods. The
National Work Group on Leak Detection Evaluations (NWGLDE)
reviews leak detection equipment that was third-party evaluated
using EPA's test protocols or equivalent protocols. Owners and
operators may wish to check if their leak detection method meets
performance requirements for use in biofuels at NWGLDE's
website: www.nwglde.org/.
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Upgrading Equipment To Meet
Compatibility Requirements For
Storing Biofuels
It is possible that many owners and operators of existing UST
systems wishing to store biofuels will find, after evaluating
their systems and documentation, they are not able to
demonstrate compatibility for their entire UST system.
These owners have three options.
One option is to use targeted retrofits of specific equipment
to upgrade their existing UST systems. Many owners may
already be able to demonstrate compatibility for the tanks and
piping in their UST systems. These components are often the
largest expenses associated with an UST system installation
and owners may have documentation available for this
equipment. In this situation, owners may be able to upgrade
other components of their UST system with less operational
downtime and less cost because they will not need to break
the concrete pad over the UST system to replace tanks or
piping.
Another option is to install a new UST system that can be
demonstrated compatible with the substance to be stored.
When installing a new system for this purpose, an owner
should specifically request equipment that is compatible with
regulated substances containing greater than 10 percent
ethanol and greater than 20 percent biodiesel. The marginal
upgrade cost for equipment that is compatible with ethanol or
biodiesel blends up to 100 percent is a small percentage
increase compared with the overall cost of a new system.
However, owners must ensure they request such equipment
prior to equipment installation.
The other option is to not store the substance. This will
ensure no releases occur due to incompatibility of the
substance and the UST system. This could prevent an owner
from being out of compliance with the compatibility
requirements or becoming responsible for cleaning up a
release to the environment from an incompatible system.
Owners and operators can explore options for upgrading their
UST systems to meet compatibility requirements by
consulting with their implementing agency, UST servicing
contractor, or the resources listed on page 17.
Remember, keeping records
of equipment or
components installed or
repaired now may help to
determine compatibility of
that equipment at a later
date, even if you aren't
currently storing biofuels. If
you are already storing
biofuels, you may already be
required to keep such
documentation to
demonstrate compatibility
of the UST system.
Owners and operators
having a new UST system
installed may wish to choose
equipment that will be
compatible with gasoline
containing greater than 10
percent ethanol or diesel
containing greater than 20
percent biodiesel. This
provides owners with the
option of storing biofuels
later, even if they do not
store them now.
Remember that you must
specifically request
equipment that is
compatible with higher
biofuel blends from the
installer prior to the
installation or the installer
may install less expensive
equipment that may not be
compatible with biofuels.
16
UST System Compatibility With Biofuels
July 2020
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I 1
Resources For More Information
Government
• EPA's emerging fuels and USTs:
www.epa.gov/ust/emerging-fuels-and-underground-
storage-tanks-usts
• EPA's January 2020 statement about E15's
compatibility with UST systems:
www.epa.gov/ust/el5-compatibilitv-ust-svstems-
statement
• EPA's June 2019 compliance advisory about
compatibility requirements in the 2015 UST
regulation: www.epa.gov/ust/compliance-
advisories-about-2015-underground-storage-tank-
regulation
• EPA's industry codes and standards for USTs:
www, epa. gov/ust/underground-storage-tanks-usts-
laws-and-regulations#code
• Association of State and Territorial Solid Waste
Management Officials' Compatibility Toot
astswmo.org/ust-compatibilitv-tool/
• New England Interstate Water Pollution Control
Commission: www.neiwpcc.org
Industry Organizations And Resources
• UL (formerly Underwriters Laboratories) Fuel
Compatibility Tool, www.ul.com/apps/ul-fuel-
compatibility-tool
• Petroleum Equipment Institute's UST Component
Compatibility Library, www.pei.org/ust-
component-compatibilitv-librarv
• Fiberglass Tank & Pipe Institute:
www, fib ergl as stankand pi pe. com
• Steel Tank Institute: www, steel tank, com
• Fuels Institute's Retailing Biofuels: A Guide to
Reading Applicable Federal Regulations:
www.fuelsinstitute.org/Research/Retailing-Biofuels
17
UST System Compatibility With Biofuels
July 2020
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• American Petroleum Institute's Recommended
Practice 1626, Storing and Handling Ethcmol and
Gasoline-Ethanol Blends at Distribution Terminals
and Filling Stations:
www.apiwebstore.org/publications/item.cgi7278920
88-2705-44bc-8244-4fd6454b8018
• National Workgroup on Leak Detection Evaluations
(NWGLDE): www.nwglde. org/index.html
Publications About USTs
You can access EPA's publications about USTs by
downloading or reading documents on EPA's website at
www.epa.gov/ust/publications-related-underground-
storage-tanks.
You can also access, read, and download online versions of
our documents on the National Service Center for
Environmental Publications (NSCEP) website at
www.epa.gov/nscep. NSCEP is EPA's publication
distributor.
UST System Compatibility With Biofuels
July 2020
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Appendices
Appendix 1: Sample Notification Letter
Below is a sample letter that you can use as a template for
notifying your implementing agency at least 30 days before
you switch to regulated substances containing greater than
10 percent ethanol, greater than 20 percent biodiesel, or any
other substance identified by your implementing agency.
You may also call or email the implementing agency, but
you should include the same information described in this
sample letter.
[Dale]
[jName of UST Implementing Agency
Street Address
City, State, Zip Code \
Dear Sir or Madam:
This letter is notifying you that pursuant to the federal
underground storage tank (UST) regulation at 40 CFR
280.32,1 intend to store [type of regulated substance]
beginning on [date] in my underground storage tank system,
which is uniquely identified as [/1ST system identification
number; compartment number, if applicable']. My
underground storage tank facility is located at [facility
address], I understand my UST system must be fully
compatible with [type of regulated substance]. If you have
questions, please contact me at [phone number].
Sincerely,
[signature]
[owner or operator name]
UST System Compatibility With Biofuels
July 2020
Remember, you must notify
the implementing agency 30
days before you switch to
store a regulated substance
containing greater than 10
percent ethanol or greater
than 20 percent biodiesel.
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Appendix 2: Sample Checklist For Determining UST System Compatibility
This sample checklist can help owners and operators determine and document the compatibility of
their UST systems. Be sure to check with your implementing agency for their specific
compatibility requirements. They may require you submit a compatibility documentation checklist
that differs from the sample checklist provided below.
Sample Checklist For Determining And Demonstrating
UST System Compatibility
Completing all sections in this checklist will help you determine if you possess the required information to
demonstrate compatibility of your underground storage tank (UST) system with regulated substances containing
more than 10 percent ethanol or more than 20 percent biodiesel (hereafter referred to as biofuels).
Owners and operators may meet the compatibility requirement in the 2015 UST regulation by either demonstrating
compatibility of their UST system with biofuels or by using an alternative. Demonstrating compatibility is most
common, and can be performed by using one of these two options:
• an independent laboratory certification or listing of component approval for use with the fuel you intend to
store; or,
• a manufacturer statement of approval to use the component with the fuel you intend to store.
You must demonstrate compatibility for these parts of the UST system: tank, piping, containment sumps, pumping
equipment, release detection equipment, spill equipment, and overfill equipment.
Some implementing agencies may allow an alternative to demonstrating compatibility to meet the compatibility
requirement. Although alternatives are available, they are uncommon. Contact your implementing agency for the
compatibility requirements that apply to your USTs.
Background: 40 CFR 280.32 states that UST owners and operators must use an UST system made of or lined
with materials that are compatible with the substance stored in the system. In the 2015 UST regulation, EPA
defines an UST system as an underground storage tank, connected underground piping, underground ancillary
equipment, and containment system, if any. Owners and operators who store regulated substances that contain
more than 20 percent biodiesel or more than 10 percent ethanol, such as 15 percent ethanol or E15, must notify
their implementing agency 30 days before storing the fuel. Owners and operators must also keep records
demonstrating that their UST system is compatible with the substance stored.
The 2015 UST regulation:
• does not require owners and operators to demonstrate the compatibility of dispensers or associated
above ground equipment. But local regulations, such as fire codes, may require compatibility for these
components. Always check with your implementing agency for requirements applicable to your UST
system and to other above ground components of your fueling system that are not part of your UST
system.
• does not require owners and operators to demonstrate the compatibility of pipe dope or sealants used in
UST system construction. But pipe dope or sealants used anywhere in your UST system must be
compatible with the regulated substance stored in the UST system, according to 40 CFR 280.32(a). If
pipe dope or sealant is incompatible with the regulated substance, owners and operators may not use
that UST system to store the incompatible substance. Pipe dope is used to seal together threaded
connections. Sealants are generally used to seal together non-threaded joints.
UST system owners and operators may find American Petroleum Institute's Recommended Practice 1626, Storing
and Handling Ethanol and Gasoline-Ethanol Blends at Distribution Terminals and Filling Stations useful in
complying with compatibility requirements.
UST System Compatibility With Biofuels
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Facility Owner:
Facility Name:
Facility Number:
Facility Street Address, City, State, Zip Code:
UST System Identifier:
Type Of Regulated Substance
You Intend To Store, Including
The Biofuel Percentage:
UST Capacity In Gallons:
Instructions: Complete the checklist on the next page. Support all answers with a sufficient description or
documentation to show that your system meets the compatibly requirement for the biofuels you intend to store.
To comply with the 2015 UST regulation compatibility requirements for storing biofuels:
• document how you meet the requirement by demonstrating compatibility or using an alternative, and
• keep the documentation as long as you store the substance.
You should update this checklist each time you repair or replace components of your UST system to ensure you
have all the required compatibility documentation while storing biofuels.
A = demonstration using an independent laboratory certification or listing of component approval for use
with the fuel you intend to store.
A valid demonstration of compatibility from an independent lab must:
• be a certification or listing that specifically includes analysis and testing of the component applicable to
use with the type and blend of regulated substance you listed at the top of this page.
Many independent laboratory certifications or listings for UST system components do not include testing for use
with biofuels. You may find your system's component is listed or certified by an organization, such as UL, and the
listing or certification states the component meets certain performance criteria. But if that listing or certification
criteria does not specifically reference the component's performance with the substance you intend to store, then it
does not meet the criteria necessary to demonstrate the component is compatible with the regulated substance
you intend to store. Many components have UL listings or certifications that are applicable for use only with
gasoline-ethanol blends containing from 0 to 10 percent ethanol.
You can find more information on UL Fuel Compatibility Tool] www.ul.com/apps/ul-fuel-compatibilitv-tool. If you
cannot locate an appropriate listing or certification, a manufacturer's statement of compatibility may be available.
B = demonstration is a manufacturer statement of approval to use the component with the fuel you intend
to store.
A valid manufacturer statement of compatibility must:
• be an affirmative statement in writing;
• be from the equipment or component manufacturer; and
• state the range of blends (for example, 0-30 percent ethanol; 0-85 percent ethanol; 0-100 percent
biodiesel) the equipment or component is compatible with.
A manufacturer's written statement and compatibility claim are the responsibility of the manufacturer; EPA does
not review them. An inspector may accept them as adequate demonstration of compatibility of the component for
use with a regulated substance, if they meet the criteria above.
You can find many manufacturer statements at:
• Petroleum Equipment Institute's UST Component Compatibility Library, www.pei.org/ust-component-
compatibilitv-librarv
• ASTSWMO Emerging Fuels Task Force Fuel Compatibility Tool', astswmo.org/ust-compatibilitv-tool/
C = use only if your implementing agency allows an alternative and has determined it is at least as
protective of human health and the environment as A or B. If using C, list your implementing agency and
describe their allowed alternative to meet the compatibility requirement at the end of the checklist.
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July 2020
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UST System Components
Documentation
Demonstrating
Compatibility With
The Substance
Listed Above?
A, B,
Or C*
Description Of Component Type,
Model Number, And National
Laboratory Certification, Listing Or
Manufacturer Approval
Tank
No
Yes
Piping
(carries product from the tank including
flex connectors and shear valves)
No
Yes
Containment Sumps
(a sump the product piping enters,
including entry boots)
No
Yes
Pumping Equipment
(includes the submersible pump or
suction pump, depending on the type
of system)
No
Yes
Release Detection Equipment—Tank
(includes, but not limited to, automatic
tank gauging probes and float sensors)
No
Yes
Release Detection Equipment—
Piping
(includes line leak detectors; and if
using interstitial monitoring, secondary
containment and sump sensors)
No
Yes
Spill Equipment
(for example, spill buckets)
No
Yes
Overfill Prevention Equipment
(includes, but not limited to, ball float
valves, flapper valves or automatic
shutoff devices, and probes for high-
level alarms, if not listed elsewhere on
this form)
No
Yes
A and B demonstrate compatibility.
*C: If your implementing agency determined this alternative is as protective of human health and the environment
as A or B, then below list your implementing agency and describe the allowed alternative for meeting the
compatibility requirement for each component, as applicable. Attach additional pages if needed.
Implementing Agency:
C Description:
UST System Compatibility With Biofuels
July 2020
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AEPA
United States
Environmental Protection
Agency
United States Environmental Protection Agency
5401R
Washington, DC 20460
EPA 510-K-20-001
July 2020
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