United States
Environmental Protection
Agency
Office of Water
(4606)
EPA816-F-01-023
July 2001
Source Water Protection
Practices Bulletin
Managing Underground Storage
Tanks to Prevent Contamination of
Drinking Water
This fact sheet focuses on the management of underground storage tanks (USTs) to prevent
contamination of drinking water sources (ground water and surface water used as public
drinking water supplies). USTs are tanks and any
connected underground piping that have at least ten
percent of their combined volume underground. USTs
contain either petroleum or hazardous substances identified
by the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA),
except those substances listed as hazardous wastes. Over
95 percent of USTs contain petroleum.
UNDERGROUND STORAGE TANK USE
You are likely to find many USTs in the
vicinity of the water sources you want to
protect. Currently, the U.S. EPA regulates
about 714,000 active USTs located at about
269,000 sites nationwide. Many USTs are
located at filling stations that fuel vehicles. In
addition to thousands of roadside filling
stations, USTs can be found at airports, school
bus barns, hospitals, automotive repair shops,
military bases, industrial plants, residential
areas and other facilities.
Some USTs, like the following, do not need to meet the Federal requirements:
• USTs not storing either petroleum or certain hazardous substances;
• Farm and residential tanks of 1,100 gallons or less capacity holding motor fuel used for
noncommercial purposes;
• Tanks storing heating oil used on the premises where it is stored;
• Tanks on or above the floor of underground areas, such as basements; and
Septic tanks and systems for collecting storm water and wastewater.
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Please note, however, that State UST regulations may be more stringent or differ in other ways
from the Federal requirements. You must check with local regulatory authorities to make sure
which USTs are subject to what requirements. For example, some States regulate heating oil
tanks and farm and residential tanks. Even if your UST does not need to meet Federal, State, or
local requirements, you should strongly consider implementing some of the prevention measures
mentioned in this fact sheet to preclude future releases.
WHY IS IT IMPORTANT TO MANAGE UNDERGROUND STORAGE TANKS
NEAR THE SOURCES OF YOUR DRINKING WATER?
Most UST releases result from the corrosion of parts, improper installation, failure of piping
systems, poorly conducted fuel deliveries (spills and overfills), and improper operation and
maintenance of the UST system.
UST releases can contaminate soil and drinking water supplies. As of September 2000, almost
412,000 UST releases had been confirmed. Once in the soil, these releases can move rapidly
and threaten drinking water supplies. EPA estimates that about half of UST releases reach
ground water.
Petroleum includes carcinogenic compounds such as benzene.
Even at very low levels, fuel contaminants in water may not be
detected by smell or taste, yet they can affect human health.
Petroleum can also contain the additive methyl tertiary butyl ether
(MTBE), which can make water smell and taste bad enough to be
undrinkable. And it does not take much pollution to create a
drinking water problem. For example, an unrestricted gasoline leak
of one drop per second releases about 400 gallons per year. Even
a few quarts of gasoline in the ground water can pollute a drinking
water well. Also, cleaning up contaminated soil and ground water
involves expensive operations. Average cleanup costs at leaking
UST sites are about $125,000, and ground water cleanup at some
sites exceeds $1 million.
Leaking pipe from UST
AVAILABLE PREVENTION MEASURES TO ADDRESS UNDERGROUND
STORAGE TANKS
Federal UST regulations were promulgated in 1988 to prevent and detect UST releases (see 40
CFR Part 280). The following paragraphs briefly identify some basic UST requirements.
Please keep in mind that individual prevention measures may or may not be adequate to prevent
contamination of source waters. Most likely, individual measures should be combined in an
overall prevention approach that considers the nature of the potential source of contamination,
the purpose, cost, operational, and maintenance requirements of the measures, the vulnerability
of the source water, the public's
acceptance of the measures, and the
community's desired degree of risk
reduction.
Federal UST Requirements
Proper installation. USTs must be
installed according to industry standards
with great care to maintain the integrity
and the corrosion protection of the tank.
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Tanks must also be properly sited
away from wells, reservoirs, and
floodplains. Ideally, all types of
USTs should be located outside of
source water protection areas.
Corrosion protection. UST
systems must be made of
noncorrodible material, such as
fiberglass, or have corrosion
protection provided in other ways,
such as by being made of externally
coated and cathodically protected
metal, having double-walls, metal
having a thick corrosion resistant cladding or jacket, or having an internal tank lining.
Excavated USTs
Spill protection. USTs must have catchment basins that can catch spills that may occur when
the delivery hose is disconnected from the fill pipe. A catchment basin is basically a bucket
sealed around the fill pipe.
Overfill protection. When an UST is
overfilled, large volumes can be released at
the fill pipe and through loose fittings on the
top of the tank or a loose vent pipe. USTs
must have overfill protection devices, such as
automatic shutoff devices, overfill alarms, and
ball float valves. In addition, proper filling
procedures during fuel delivery must be
followed to reduce the chance of spills or
overfills.
Leak detection. Leak detection options include automatic tank gauging, interstitial monitoring,
statistical inventory reconciliation, vapor monitoring, and ground water monitoring. All leaks
must be detected in a timely manner, before they become big cleanup and liability problems.
Proper closure. The regulatory authority needs to be notified 30 days before UST closure, and
a determination must be made if any contamination of the environment has occurred. The tank
must be emptied and cleaned, after which it may be left underground or removed. Standard
safety practices should always be followed when emptying, cleaning, or removing tanks.
Additionally, some large capacity UST owners — those who have more than 42,000 gallons of
oil storage capacity at one site — may need to comply with Federal Spill Prevention Control and
Countermeasures (SPCC) regulations. Refer to the above ground storage tank fact sheet or 40
CFR Part 112 for information.
Additional Prevention Measures
Local jurisdictions may want to implement registration programs for exempt tanks, in order to
exercise some oversight of their construction and operation.
Local governments can use land use controls to address some of the potential risks from
USTs. For example, zoning can restrict these activities to specific geographic areas that are
away from drinking water sources. Prohibition of gas stations (which use USTs) or residential
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heating oil tanks in source water protection areas can reduce the risk that harmful contaminants
may enter source water. Local governments may also require permits that impose additional
requirements such as setbacks, open spaces, buffers, walls and fences; street paving and control
of site access points; and regulation of hours and methods of operation.
Work with your State and local UST regulatory authorities to ensure that adequate inspection
of UST sites takes place regularly — inspections that verify whether USTs are properly
equipped, operated, and maintained so they will not pose a threat to your water source. State
UST program contacts are among the many resources found at the Web site described below.
FOR ADDITIONAL INFORMATION
Information and publications on UST regulations and best management practices can be
obtained at no cost on the Internet at the following Web site address maintained by EPA's
Office of Underground Storage Tanks: http://www.epa.gov/OUST/. You can also call an EPA
Hotline at 1-800-424-9346 for assistance and to order helpful publications about USTs. The
most useful general publication is called "Musts For USTs," a basic plain language description of
UST types and Federal requirements. Also, see EPA's Drinking Water Academy Web site at
http://www.epa.gov/safewater/dwa.html for a listing of documents on management measures.
Contact local government authorities in your area to see if there are ordinances in place to
manage USTs. Numerous examples of local source water protection-related ordinances for
various potential contaminant sources can be found at:
http://www.epa.gov/r5water/ordcom/
http: //www. ep a. gov/o wow/nps/ordinance/
http://www.epa.gov/owow/nps/ordinance/links.htm
The following documents provide additional information on UST prevention measures and
regulations:
American Petroleum Institute. Preventing Spills in Storage Tanks. (1999, February 16).
Retrieved February 9, 2001 from the World Wide Web: http://www.api.org/oilspills/tanks.htm
Iowa Department of Natural Resources. Groundwater Protection Fact Sheet -
Underground Storage Tanks. (1996, August). Retrieved February 9, 2001 from the World
Wide Web: www.state.ia.us/dnr/organiza/wmad/lqbureau/ust/genustl.htm
Iowa Department of Natural Resources, Waste Management Assistance Division.
Underground Storage Tanks — Frequently Asked Questions. (2001, January 15). Retrieved
February 9, 2001 from the World Wide Web:
http://www.state.ia.us/dnr/organiza/wmad/lqbureau/ust/index.htm
Minnesota Pollution Control Agency. Underground Storage Tank (UST) Systems. (2000,
December 27). Retrieved February 9, 2001 from the World Wide Web:
http://www.pca.state.mn.us/cleanup/ust.html
Purdue University Extension Service. Petroleum Product Storage Practices on the Farm.
(1991). Retrieved February 12, 2001 from the World Wide Web:
http://pasture.ecn.purdue.edu/~epados/farmstead/fuel/src/title.htm
South Dakota Department of Environment and Natural Resources, Ground Water Quality
Program. Don't Wait Until 98. (n.d.). Retrieved February 9, 2001 from the World Wide
Web: http://www.state.sd.us/denr/DES/Ground/tanks/dont-2.htm
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South Dakota Department of Environment and Natural Resources, Ground Water Quality
Program. Frequently Asked Questions about UST and AST Systems, (n.d.). Retrieved
February 19, 2001 from the World Wide Web:
http ://www. state. sd.us/denr/DES/Ground/tanks/FAQTANK.htm
U. S. Environmental Protection Agency, Region 7. Region 7 Underground Storage Tank
Fact Sheet — Understanding the 1998 Requirements. (1998/1999, winter). Retrieved
February 9, 2001 from the World Wide Web:
http: //www. epa. gov/region7/program s/artd/ustbx/index2. htm
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response.
Musts for USTs -A Summary of Federal Regulations for Underground Storage Tank
Systems (EPA 510/K-95-002). (1995, July). Retrieved January 31, 2001 from the World Wide
Web: http://www.epa.gov/swerustl/pubs/
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response.
Straight Talk on Tanks - Leak Detection Methods for Petroleum Underground Storage
Tanks and Piping (EPA 510/B-97-007). (1997, September). Retrieved January 31, 2001 from
the World Wide Web: http://www.epa.gov/swerustl/pubs/
U.S. Environmental Protection Agency, Office of Underground Storage Tanks. Upgrading
UST Systems. (1998, May 27). Retrieved January 31, 2001 from the World Wide Web:
http://www.epa.gov/swerustl/ustsystm/upgrade.htm
U.S. Environmental Protection Agency, Office of Underground Storage Tanks. What Do You
Need to Know about Underground Storage Tanks? (1999, June 7). Retrieved January 31,
2001 from the World Wide Web: http://www.epa.gov/swerustl/cmplastc/knowneed.htm
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