&EPA
United States
Environmental Protection
Agency
Source Water Protection
Practices Bulletin
Managing Above Ground Storage Tanks to
Prevent Contamination of Drinking Water
Inside this issue:
Why is it Important 2
to Manage ASTs?
Available Prevention 2
Measures
Additional 4
Information
Basic AST Facts:
• Most storage tanks contain
petroleum products.
• State AST regulations may be
more stringent than Federal
requirements.
• A spill of only one gallon of
oil can contaminate a million
gallons of water.
• ASTs should have a
secondary containment area
to contain spills.
• If a tank is not used for more
than a year it is possible
your State may require you to
declare it as "Out of
Service".
• Inspect any accumulated
water for chemicals prior to
discharge from the AST area.
• Most States require AST
inspections by Fire
Marshalls.
Above ground storage tanks (ASTs) are tanks or other containers that are above ground, partially
buried, bunkered, or in a subterranean vault. These can include floating fuel systems. This fact
sheet focuses on the management of facilities with ASTs to prevent contamination of drinking
water sources (ground water and surface water used as public drinking water supplies).
Above Ground Storage Tank Use
The majority of storage tanks contain petroleum
products (e.g., motor fuels, petroleum solvents,
heating oil, lubricants, used oil). Oil storage
facilities with ASTs are typically found in mar-
keting terminals, refineries, and fuel distribution
centers. Storage tanks may also be found in
airports, school bus barns, hospitals, automotive
repair shops, military bases, farms, and indus-
trial plants. Discharges of chemicals, petroleum,
or non-petroleum oils from storage tanks can
contaminate source water. Product spilled,
leaked, or lost from storage tanks may accumu-
late in soils or be carried away in storm runoff.
1 - Above Ground Storage Tank
Some of the causes for storage tank releases are holes from corrosion, failure of piping systems, and spills
and overfills, as well as equipment failure and human operational error. The Spill Prevention Control and
Countermeasures (SPCQ regulations require owners or operators of certain above ground oil storage
facilities to prepare and comply with written, site-specific, spill prevention plans (see 40 CFR Part 112):
• Facilities with a total above ground oil storage capacity of more than 1,320 gallons;
• Single above ground tanks with an oil storage capacity of more than 660 gallons; and
• Facilities with a combined underground oil storage capacity greater than 42,000 gallons.
Please note, however, that State AST 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 ASTs are
subject to what requirements. All AST facility owners or operators exempt from these regulations
should still consider implementing the prevention measures described in this fact sheet to preclude fu-
ture storage tank problems.
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PAGE
SOURCE WATER PROTECTION PRACTICES BULLETIN
Why is it Important to Manage Above Ground Storage Tanks
Near Sources of Drinking Water?
Storage tank releases can contaminate
soil and drinking water supplies.
Petroleum products are composed of
volatile organic compounds (VOCs).
Any oil spill can pose a serious threat
to human health and the environment,
2 -
Oil in
water.
requires remediation that extends be-
yond your facility's boundary, and
results in substantial cleanup costs.
Even a small spill can have a serious
impact. A single pint of oil released
into the water can cover one acre of
water surface area and can seriously
damage an aquatic habitat. A spill of
only one gallon of oil can contaminate
a million gallons of water. It may take
years for an ecosystem to recover
from the damage caused by an oil spill.
The location of the facility must be
considered in relation to drinking
water wells, streams, ponds and
ditches (perennial or intermittent),
storm or sanitary sewers, wetlands,
mudflats, sandflats, farm drain tiles, or
other navigable waters. Factors such
as the distance to drinking water wells
and surface water, volume of material
stored, worse case weather conditions,
drainage patterns, land contours, and
soil conditions must also be taken into
account.
Available Prevention Measures to Address Above Ground
Storage Tanks
The following list of prevention measures
is not all-encompassing; others can be
found in the references provided at the end
of the document. Furthermore, detailed
explanations of each device mentioned
below are found in the supporting docu-
ments. Please keep in mind that individual
prevention measures may or may not be
adequate to prevent contamination of
source waters. Most likely, individual
Federal AST Requirements under 40 CFR Part 112
A SINGLE PINT OF OIL
RELEASED INTO THE WATER CAN
COVER 1 ACRE OF WATER
SURFACE AREA AND SERIOUSLY
DAMAGE AQUATIC HABITATS.
measures should be combined in an overall
prevention approach that considers the
nature of the potential source of contami-
nation, 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.
Follow standard tank filling practices when
filling tanks to prevent spills and overfills.
Furthermore, all ASTs should have a sec-
ondary containment area that contains
spills and allows leaks to be more easily
detected. The containment area surround-
ing the tank should hold 110 percent of the
contents of the largest tank plus freeboard
for precipitation. Secondary containment
for ASTs must be impermeable to the ma-
terials being stored. Methods include
berms, dikes, liners, vaults, and double-
walled tanks. A manually controlled sump
pump should be used to collect rain water
that may accumulate in the secondary con-
tainment area. Any discharge should be
inspected for petroleum or chemicals prior
to being dispensed.
Routinely monitor ASTs to ensure they
are not leaking. An audit of a newly
installed tank system by a professional
engineer can identify and correct problems
such as loose fittings, poor welding, and
poorly fit gaskets. After installation, inspect
the tank system periodically to ensure it is
in good condition. Depending on the
permeability of the secondary containment
area, more frequent containment area
checks may be necessary. Areas to inspect
include tank foundations, connections,
coatings, tank walls, and the piping system.
Integrity testing should be done
periodically by a qualified professional and
in accordance to applicable standards.
If an AST has remained out of service for
more a year or more, many States require
owners to maintain and monitor the tank,
declare the tank inactive, or remove it. If
the tank is declared inactive, remove all
substances from the AST system (including
pipes) and completely clean the inside.
Secure tanks by bolting and locking all
valves, as well as capping all gauge open-
ings and fill lines. Clearly label tanks with
the date and the words "Out of Service."
Samples may be required when removing
tanks to determine if any contamination
has occurred. Most States require out-of-
service tanks to be inspected and meet leak
detection requirements before they are put
back into service.
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Additional AST Prevention Measures
The following prevention measures go beyond the Federal regulations under 40 CFR Part 112, but are highly recommended:
Facility Location:
The location of the facility
must be considered in rela-
tion to drinking water wells,
streams, ponds and ditches
(perennial or intermittent),
storm or sanitary sewers,
wetlands, mudflats, sandflats,
farm drain tiles, or other
navigable waters. The dis-
tance to drinking water wells
and surface water, volume of
material stored, worse case
weather conditions, drainage
patterns, land contours, and
soil conditions must also be
taken into account.
Inferential Space
(Monitored for Vacuum,
Pressure. Vapor, or Liquid)
Coating to Provide
Corrosion Protection for
External Wall
4 - Cross section of a double-walled tank.
5 - Tanks in a vault.
Corrosion Control:
ASTs should have corro-
sion protection for the
tank. Options include
elevating tanks, resting
tanks on continuous con-
crete slabs, installing dou-
ble-walled tanks, cathodi-
cally protecting the tanks,
internally lining tanks,
inspecting tanks accord-
ing to American Petro-
leum Institute standard,
or a combination of the
options listed above. All
underground piping to
the tank should be double
-walled or located above
ground or cathodically
protected so you can
inspect it when it fails.
To maximize system
safety, seal the floors,
containment area, and
sump pump pit with an
appropriate coating (e.g.,
petroleum resistant coat-
ing). Any accumulated
water should be inspected
for petroleum or chemi-
cals prior to discharge.
Periodic Cleanup:
Accumulated minor spillage, over
time, may result in a film or sheen
on collected rain water, making it
unsuitable for discharge to the soil
or drains. Periodic cleanup of the
containment areas (e.g., sweeping
with a broom and using limited
absorbent) can prevent unnecessary
dirt and contaminant buildup.
A ROOF COVERING
A 10,000 GALLON
TANK WILL
CONSERVE 600-
1,000 GALLONS OF
GASOLINE PER
YEAR, WHICH
WOULD HAVE
ESCAPED BY
EVAPORATION.
7 - Covered
AST with
secondary
containment
(above)
8 - Elevated
AST (left)
Preventing Evaporation:
While not a preventative measure
for source water protection, pre-
venting evaporation has economic
and air quality benefits. To keep
out rain and reduce evaporation
losses and moisture condensation,
paint tanks a reflective color, install
them in an east-west direction,
install a low-pressure valve on top
of the tank, and cover the struc-
ture. A roof structure covering a
10,000 gallon tank will conserve
600 to 1,000 gallons of gasoline per
year, which would have escaped by
evaporation without the shade
cover.
Registration Programs:
Local jurisdictions may want to implement registration
programs for exempt tanks, in order to exercise some
oversight of their construction and operation. Furthermore,
most States also require inspections for ASTs by fire
marshals. Inspection programs can be expanded to cover
water contamination issues.
6 - Floating fuel station in the Amazon.
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PAGE 4
SOURCE WATER PROTECTION PRACTICES BULLETIN
Additional Information
The following documents contain more detailed information on ASTs and are available for free on the Internet. You can
contact your EPA Regional SPCC or Oil Coordinator for more information, as well. There are also State and local
authorities that are often located in Oil, Environmental, or Pollution Control Divisions who can provide you with local
regulations for ASTs.
Contact local government authorities in your area to see if there are ordinances in place to manage ASTs. 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.epa.gov/owow/nps/ordinance/http://www.epa.gov/owow/nps/
ordinance /links .htm
The following documents provide additional information on AST prevention measures and regulations:
breather valve
spray nozzle
manhole
automatic tank gauge
secondary Inlet
bund wal
9 - AST diagram.
fixed-roof tank
Florida Cooperative Extension Service, In-
stitute of Food and Agricultural Sciences,
University of Florida.. Above-Ground Fuel
Storage Systems (EES-61). (1992, October).
Retrieved February 9, 2001 from the World
Wide Web: http://www.cdc.gov/niosh/
nasd/docs2/as 04300.html
Minnesota Pollution Control Agency. Above
-Ground Storage Tank Systems. (2000,
OctoberlS). Retrieved February 9, 2001
from the World Wide Web:
http://www.pca.state.mn.us/cleanup/
ast.html
Minnesota Pollution Control Agency.
Out-of-Service Tank Systems. (1998,
November). Retrieved February 9, 2001
from the World Wide Web:
http://www.pca.state.mn.us/cleanup/ast.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.. 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, Office of Solid Waste and Emergency Response. SPCC Requirements and
Pollution Prevention Practices for Bulk Storage Facilities, (n.d.). Retrieved February 9, 2001 from the World Wide Web:
http://www.epa.gov/oilspill/spcc/index.htm
U.S. Environmental Protection Agency, Office of Water. Storm Water Management for Industrial Activities —
Developing Pollution Prevention Plans and Best Management Practices. Section 3.6 - Liquid Storage in Above-Ground
Storage Tanks (EPA 832/R-92-006). (1992,September). Retrieved February 9, 2001 from the World Wide Web:
http://www.epa.gov/owm/sw/indguide/index.htm
U.S. Environmental Protection Agency, Oil Spill Program. Introduction and Background to the Oil Pollution Prevention
Regulation, (n.d.). Retrieved May 1, 2001 from the World Wide Web: http://www.epa.gov/oilspill/spcc/index.html
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Image Credits
1 - Federal Facilities Environmental Stewardship and Compliance Assistance Center. Assistance: Facility Regulatory Tour
for Storage Tanks: Above Ground Storage Tanks. Accessed on July 26, 2010 at:
http://www.fedcenter.gov/assistance/facilitytour/tanks/aboveground/
2 - Flickr Creative Commons: Attribution only search. Psychedelic water uploaded by "notsogoodphotography" on April
24, 2010. http://www.flickr.com/photos/notsogoodphotography/4547807568/
3 - Flickr Creative Commons: Attribution only search. Imperium storage tanks, uploaded by "skidrd" on August 18,
2007. http://www.flickr.com/photos/skidrd/1160891313/
+ stairs
m
floatin
10 - AST Diagram.
floating-roof tank
4, 5,11 - EPA: Office of Solid Waste and
Emergency Response, September 2005. RCRA
Training Module: Introduction to Tanks (40
CFR Parts 264/265, Subpart J)
http://www.epa.gov/epawaste/inforesources/
pubs /hotline /training/tanks 05.pdf
6 - TravelPod Blogs. Amazon floating fuel
stations, uploaded by "Suenson_taylors" on
November 7, 2009.
http://www.travelpod.com/travel-photo/
suenson_taylors/l/1257735331/amazon-
floating-fuel-stations, jpg/ tpod.html
7, 8 - From original AST document.
9, 10 - Merriam-Webster Visual Dictionary
Online. Search for - Energy :: Geothermal and Fossil Energy :: Oil :: Tanks [1] and [3]. Diagrams of ASTs.
http://visual.merriam-webster.com/energy/geothermal-fossil-energy/oil/tanks_l.php
Back Cover - Flickr Creative Com-
mons: Attribution only search. Oil/
water storage tanks, Conroe oil field,
uploaded by "roy.luck" on May 10,
2009.
11 - AST diagram.
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Source Water Protection Practices Bulletin
Managing Above Ground Storage Tanks to Prevent
Contamination of Drinking Water
The mission of EPA is to protect human health
and to safeguard the natural environment — air,
water and land — upon which life depends.
USEPA East (EPA East) [Old ICC Building]
1201 Constitution Avenue N.W.
Washington, DC 20004
United States
Environmental Protection
Agency
Office of Water (4606)
EPA ### ### ### ###
www. epa.gov/safewater
August 2010
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