4936
510R87001
United States
Environmental Protection
Agency
Office of
Underground Storage Tanks
Washington, D.C. 20460
January 1987
Underground Storage Tanks
oEPA
Designing and Installing
Underground Storage Tanks
Under the New Federal Law
US,
Region V,Ubrary
230 South
Chicago, ,«Hnpit
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LEAKING TANKS:
A NATIONAL PROBLEM
In recent years, thousands of leaking
underground storage tanks have been discovered
and thousands more probably will be found.
Underground tanks containing motor fuels and
hazardous chemicals are found in many places,
including service stations, transportation and
delivery services, manufacturing plants, and even
dry cleaners. Petroleum or chemical leaks from
underground tanks or pipes create environmental
and safety hazards and cost tank owners and
operators a lot of money. For these reasons, proper
design and installation of tanks is important to
prevent future damage to the nation's resources.
A TEMPORARY SOLUTION:
THE INTERIM PROHIBITION
In response to this situation, Congress passed a
law regulating underground tanks containing
petroleum products or hazardous chemicals. The
U.S. Environmental Protection Agency is studying
the leaking underground storage problem and, in
1987, will propose standards for all new and
existing tanks and regulations for leak detection,
prevention, and corrective action. Final standards
and regulations will be issued in 1988 after a period
of public comment.
In the interim, the law requires that any tanks
and piping installed after May 7, 1985 be designed,
constructed, and installed to ensure prevention of
leaks. Called the "Interim Prohibition," this part of the
law bans bare steel tanks and requires controls for:
H Corrosion protection;
• Structural integrity; and
• Chemical compatibility
WHAT DOES ALL THIS MEAN?
This brochure explains each of these
requirements and various ways to comply with them.
For those wanting more detailed information, "The
Interim Prohibition: Guidance for Design and
Installation of Underground Storage Tanks" can be
obtained by sending in the attached business reply
card. Answers to the most frequently asked
questions about the Interim Prohibition are provided
on the back of this brochure.
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CORROSION:
WHAT YOU CAN DO ABOUT IT
What is Corrosion?
The external surface of a steel tank, when it
comes in contact with the soil, will naturally seek to
return to its original state, iron oxide, or the more
commonly known term, rust. This is a complex
electrochemical process that creates a flow of current
between two materials with different electrical
characteristics. Metal corrodes under almost any
naturally occurring soil condition, but the rate of
corrosion is affected by the amount of oxygen and
moisture in the soil and other site-specific factors.
How Can Corrosion Be Controlled?
The Interim Prohibition identifies three different
methods of corrosion control:
« Cathodic protection;
* Noncorrosive materials of construction; (i.e.,
fiberglass reinforced plastic) and,
* Noncorrosive coating of steel.
The Interim Prohibition also allows the use of
other corrosion controls if "...they are designed in a
manner to prevent the release or threatened release
of any stored substance." Regardless of the
technology chosen, corrosion protection is required
for both the piping and the tank.
Cathodic Protection
Cathodic protection reverses the electrical
forces that cause corrosion and can be achieved in
two ways:
a Connecting zinc or magnesium anodes to a
steel tank, (sacrificial anode system); or
" Applying a continuous electrical current to
the tank (impressed current system).
You can check the effectiveness of either of
these systems by measuring voltage between the
tank and the soil. In both systems this voltage must
be checked periodically for damage requiring repaifs.
Galvanized (zinc coated) pipe was developed
and is effective for above ground use. However, it
does not satisfy EPA's Interim Prohibition
requirements for corrosion protection of
underground storage tanks because zinc coating
only provides a limited amount of protection.
Noncorrosive Materials of Construction
The Interim Prohibition allows tanks and piping to
be constructed of noncorrosive materials as an
alternative to cathodic protection. The most widely
used noncorrosive material in the manufacture of
tanks and piping is fiberglass reinforced plastic
(FRP). Tank systems constructed of FRP satisfy the
corrosion protection requirements of the Interim
Prohibition. It is the only material that contains
sufficient corrosion resistance without additional
cathodic protection or coating.
Noncorrosive Coating
Another type of protection that complies with the
Interim Prohibition is a steel tank coated with
fiberglass reinforced plastic. There is some debate
among corrosion control experts regarding the
advisability of using any coating without cathodic
protection; however, the Interim Prohibition allows
the use of "steel clad with a noncorrosive material."
Only FRP-coated steel is acceptable. The key
factors in the success of this coating include its
thickness, insulating strength, durability, and good
bonding to the steel. Manufacturers' standards
currently require:
m A minimum thickness of completed coating
equal to 0.10 inch; and
* Electric testing to ensure complete coating
of the tank.
These should be considered minimum
standards for acceptability of fiberglass reinforced
plastic coatings. As consensus codes or other
national standards become available, they may
supplement or replace these minimum standards.
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:r
United States Environmental
Protection Agency
Office of Underground Storage
Tanks (OUST), WH - 562A
Washington, DC 20460
Bulk Rate
U.S. Postage
PAID
Rockville, MD
Permit No. 5032
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STRUCTURAL INTEGRITY:
PROPER INSTALLATION IS
CRUCIAL
The Interim Prohibition requires that tanks be
properly installed so structural failure does not occur.
One of the keys to achieving this is proper selection
and installation of the backfill material used to support
the tank. For fiberglass reinforced plastic tanks, the
backfill provides as much as 90 percent of the tank's
support. For both steel and fiberglass tank systems,
failure to properly backfill the tank can cause
structural damage and result in contamination of soil
and ground water, and serious liability.
Tank manufacturers provide installation
instructions which should be strictly followed. Many
states and local jurisdictions have additional
requirements which tank owners and installers also
must follow. Check with your fire, health, and
environmental agencies for requirements.
The EPA's guidance document is limited in
scope. A manual covering all aspects of tank
installation has recently been developed by the
Petroleum Equipment Institute (PEI),
"Recommended Practices for Installation of
Underground Liquid Storage Systems." Single
copies of PEI RP 100-86 cost $10.00 ($8.00 for PEI
members). Quantity discounts are available for 25 or
more copies. Order prepaid from: Petroleum
Equipment Institute, P.O. Box 2380, Tulsa, OK
74101.
The American Petroleum Institute (API) also has
a booklet of recommended practices, "Installation of
Underground Petroleum Storage Systems" (#1615),
published in 1979. It can be purchased for $4.00
from API, 1220 L Street, NW, Washington, D.C.
20005.
COMPATIBILITY: WILL YOUR
PRODUCT DISSOLVE YOUR
TANK'S INTERIOR?
The liquid stored in a tank must not dissolve the
material of the tank's interior or coating. Some stored
liquids do; this is called chemical incompatibility.
Incompatibility can result in cracks and openings in
the tank that allow chemicals to seep into the soil.
Common examples of chemicals that are
incompatible with specific types of tank liners and
construction materials are:
Mineral acids including nitric, hydrochloric, and
dilute sulfuric acids which are incompatible with
steel.
Sulfuric acid (95 percent), nitric acid (50
percent), hydrofluoric acid (40 percent),
aromatic solvents, and chlorinated solvents
which are incompatible with some types of
fiberglass reinforced plastic.
Organic solvents which are incompatible with
chlorinated rubber liners.
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ANSWERS TO QUESTIONS ABOUT THE INTERIM PROHIBITION
Q.
A.
Q.
A.
Q.
A.
Q
How will the proposed regulations affect a tank designed and installed in compliance with the Interim
Prohibition?
The regulations, as proposed, are the same as the Interim Prohibition Standards for new tanks, but will also
include regulations for leak detection and reporting, corrective action, and financial responsibility. Tank
owners and operators should read the final regulations very carefully so they will know what they must do to
comply with them.
Are any classes of tanks entirely exempt from the Interim Prohibition?
Yes. Tanks that are specifically exempt include tanks storing heating oil foruse on the premises,
residential and farm tanks storing motor fuels if the tank volume is 1,100 gallons or less, and tanks whose
volume (including piping) is less than 10 percent beneath the surface of the ground.
Is a tank installed in noncorrosive soil exempt from the corrosion protection requirement of the Interim
Prohibition?
Possibly. If soil tests conducted in accordance with ASTM Standard G57-78 show that soil resistivity is
12,000 ohm/cm or more, a storage tank without corrosion protection may be installed. The tank must still
comply with the structural integrity and compatibility requirements of the Interim Prohibition.
Are double-walled tanks, lined tanks, or tanks with other secondary containment systems exempt from the
corrosion protection requirements of the Interim Prohibition?
A. No.
Q. Does the Interim Prohibition apply to "recycled" tanks?
A. Yes. A tank that is removed and reinstalled at the the same or another location is subject to the Interim
Prohibition.
Q. What is the penalty for noncompliance with the Interim Prohibition?
A. The maximum penalty is $10,000 per tank for each day of violation.
Q. How can I obtain more information?
A. You can call the EPA toll free Hotline at (800) 424-9346 or direct at (202) 382-3000. To receive the Interim
Prohibition Guidance Document and be put on the mailing list for copies of EPA's proposed regulations
and other information, return the attached card.
BUSINESS REPLY MAIL
FIRST CLASS PERM IT NO. 1566 ROCKVILLE, MD.
POSTAGE WILL BE PAID BY ADDRESSEE
U.S. Environmental Protection Agency
Office of Underground Storage Tanks
Box 6044
Rockville, MD 20850
NO POSTAGE
NECESSARY
IF MAILED
IN THE
UNITED STATES
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U.S. Environmental Protection Agency
Region V, Library
230 South Dearborn Street
Chicago, Illinois' 60604
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