ASTM E2681-21

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2681 − 21
Standard Guide for
Environmental Management of Underground Storage Tank
Systems Storing Regulated Substances
This standard is issued under the fixed designation E2681; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This guide provides an overview of environmental practices for design, installation, operation,
maintenanceincludingscheduledinspectionsandperiodicequipmenttesting,andwhennecessary,and
corrective action for underground tank systems used for storage of regulated substances. The training
for, and application of these practices should serve to prevent accidental releases of petroleum or
regulated from underground storage tank systems and to facilitate effective detection and response
whenandifsuchreleasesdooccur.Theguideisintendedforusebytanksystemownersandoperators
and other persons concerned with practices for prevention and control of environmental releases and
remediation of affected environmental media. The guide provides an overview of environmentally
sound management practices, identifying key management considerations and referring the user to
other related ASTM standards and industry guidelines for more detailed information. Regulatory
requirements related to underground storage tank systems may vary by regulatory jurisdiction. This
guide provides recommendations to comply with the requirements of 40 CFR Part 280.The user must
review the regulations of the implementing agency to determine if it has more stringent regulatory
requirements. All personal safety considerations are not addressed in this guide, and it is the
responsibility of the user to identify relevant safety and health protection practices and regulations
related to tank system management. Caution is warranted due to the flammable or combustible
property of some materials stored in underground storage tanks. Fire codes should be followed.
1. Scope ments. It is not possible to identify all considerations or
combinations of conditions pertinent to a unique underground
1.1 The framework discussed in this guide is limited to
storage tank system.
facilities with underground storage tanks (USTs) storing regu-
lated substances at ambient temperature and atmospheric
1.2 This guide addresses principal considerations related to
pressure. This guide is not intended to provide detailed
the prevention of, and response to environmental releases from
technical specifications for implementation of the approaches
tank systems and is organized in the sections listed below:
described in this document, nor to be used as an enforcement
tool, but rather to identify the important information used for
Section 1: Scope
environmental management of underground tank systems. The Section 2: Lists relevant ASTM Standards and other industry
or regulatory guidance documents
term “must” is used where United States federal requirements
Section 3: Defines the key terminology used in this guide
apply. References to ASTM standards and other industry
Section 4: Describes the significance and use of this guide
guidelines have been provided to address implementation of Section 5: Tank System Design and Installation
Section 6: Preventive Maintenance and Inspection Plan
the approaches discussed in this guide. Many states and some
Section 7: Fueling Procedure
local agencies have adopted rules that place additional respon-
Section 8: Dispensing Activities
sibilities on the owners/operators of UST systems. Refer to Section 9: Release Response Plan
Section 10: Corrective Action for Affected Environmental
state and local regulations that may contain additional require-
Media
Section 11: Tank System Closure
Section 12: UST Management Practice and Operator Training
ThisguideisunderthejurisdictionofASTMCommitteeE50onEnvironmental Appendix X1: Recurring Release Detection and Cathodic
Protection Requirements (Quick Glance) is
Assessment, Risk Management and CorrectiveAction and is the direct responsibil-
intended to be a quick reference guide for
ity of Subcommittee E50.01 on Storage Tanks.
monitoring information
Current edition approved Sept. 1, 2021. Published September 2021. Originally
Related Material: Documents related to environmental management
approved in 2013. Last previous edition approved in 2013 as E2681–13. DOI:
of underground storage tanks
10.1520/E2681-21.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2681 − 21
1.3 The values stated in inch-pound units are to be regarded 2.3 Underwriters Laboratory (UL) Standards
as standard. No other units of measurement are included in this UL58 StandardforSteelUndergroundTanksforFlammable
standard. and Combustible Liquids
UL 87A Power-Operated Dispensing Devices for Gasoline
1.4 This standard does not purport to address all of the
and Gasoline/Ethanol Blends With Nominal Ethanol Con-
safety concerns, if any, associated with its use. It is the
centrations Up To 85 Percent (E0 - E85)
responsibility of the user of this standard to establish appro-
UL 971 Standard for Nonmetallic Underground Piping for
priate safety, health, and environmental practices and deter-
Flammable Liquids
mine the applicability of regulatory limitations prior to use.
UL 1316 Glass-Fiber-Reinforced Plastic Underground Stor-
Some specific hazards statements are given in Section 7 on
ageTanks for Petroleum Products,Alcohols, andAlcohol-
Hazards.
Gasoline Mixtures
1.5 This international standard was developed in accor-
UL 1746 Standard for External Corrosion Protection Sys-
dance with internationally recognized principles on standard-
tems for Steel Underground Storage Tanks
ization established in the Decision on Principles for the
2.4 National Association of Corrosion Engineers (NACE)
Development of International Standards, Guides and Recom-
Standards
mendations issued by the World Trade Organization Technical
NACE RP0285 Control of External Corrosion on Under-
Barriers to Trade (TBT) Committee.
ground or Submerged Metallic Piping Systems
NACE Corrosion Data Survey Metals and Nonmetals Sec-
2. Referenced Documents
tions. Hamner, N.E. (ed.), 1975
2.1 ASTM Standards:
2.5 National Fire Protection Association (NFPA) Stan-
D5745 Guide for Developing and Implementing Short-Term
dards:
Measures or Early Actions for Site Remediation
NFPA 30 Flammable and Combustibles Liquids Code
E1739 Guide for Risk-Based Corrective Action Applied at
NFPA 30A Code for Motor Fuel Dispensing Facilities and
Petroleum Release Sites
Repair Garages
E1990 Guide for Performing Evaluations of Underground
NFPA 326 Standard for the Safeguarding of Tanks and
Storage Tank Systems for Operational Conformance with
Containers for Entry, Cleaning, or Repair
40 CFR, Part 280 Regulations
NFPA 385 Standard for Tank Vehicles for Flammable and
E2081 Guide for Risk-Based Corrective Action
Combustible Liquids
E2616 Guide for Remedy Selection Integrating Risk-Based
Corrective Action and Non-Risk Considerations
2.6 Petroleum Equipment Institute (PEI) Standards:
PEI RP100 Recommended Practice for Installation of Un-
2.2 American Petroleum Institute (API) Standards:
derground Liquid Storage Systems
API RP 1007 Loading and Unloading of MC-306 and
PEI RP900 Recommended Practices for the Inspection and
DOT-406 Cargo Tank Motor Vehicles
Maintenance of UST Systems
API RP 1604 Closure of Used Underground Petroleum
Storage Tanks 2.7 Steel Tank Institute (STI) Standards:
APIRP1615 InstallationofUndergroundPetroleumStorage
STI-P3 System for External Corrosion Protection of Under-
Systems
ground Steel Storage Tanks
API RP 1621 Bulk Liquid Stock Control at Retail Outlets STI F841-01 Standard for Dual Wall Underground Steel
API RP 1626 Storage and Handling of Ethanol and Storage Tanks
Gasoline-Ethanol Blends at Distribution Terminals and STI ACT-100 External Corrosion Protection of FRP Com-
Filling Stations posite Steel Underground Storage Tanks
API Publication 1628 Guide to the Assessment and Reme- STI ACT-100-U External Corrosion Protection of Compos-
diation of Underground Petroleum Releases ite Steel Underground Storage Tanks
STI Document “Keeping Water Out of Your Storage Sys-
API Publication 1629 Guide forAssessing and Remediating
Petroleum Hydrocarbons in Soils tem”
API RP 1632 Cathodic Protection of Underground Petro- STI F922 PERMATANK (trademarked) Double Wall Steel-
Fiberglass Underground Storage Tank
leum Storage Tanks and Piping Systems
API Publication 4509 Design, Construction, Operation,
Maintenance and Inspection of Terminal and Tank Facili-
ties
Available from Underwriters Laboratories (UL), 2600 N.W. Lake Rd., Camas,
WA 98607-8542, http://www.ul.com.
Available from NACE International (NACE), 1440 South Creek Dr., Houston,
TX 77084-4906, http://www.nace.org.
2 6
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from National Fire Protection Association (NFPA), 1 Batterymarch
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Park, Quincy, MA 02169-7471, http://www.nfpa.org.
Standards volume information, refer to the standard’s Document Summary page on AvailablefromPetroleumEquipmentInstitute(PEI),P.O.Box2380,Tulsa,OK
the ASTM website. 74101–2380, http://www.pei.org.
3 8
Available from American Petroleum Institute (API), 1220 L. St., NW, Available from Steel Tank Institute (STI), 944 Donata Ct., Lake Zurich, IL
Washington, DC 20005-4070, http://www.api.org. 60047, http://www.steeltank.com.
E2681 − 21
2.8 United States Environmental Protection Agency (US 3.1.6.1 Discussion—This guide is not applicable to USTs
EPA) Standards: subject to regulation under the Atomic Energy Act.
EPA/510-B-93-005 USEPAManualTank Gauging for Small
3.1.7 implementing agency, n—Environmental Protection
Underground Storage Tanks
Agency(EPA),or,inthecaseofaStatewithprogramapproval
EPA 510-K-16-001 USEPA Operating and Maintaining
(or pursuant to a memorandum of agreement with EPA), the
Underground Storage Tank Systems—Practical Help and
designated State or Local agency responsible for carrying out
Checklists
the UST program.
EPA/510-R-05-001 USEPA UST Systems: Inspecting and
3.1.7.1 Discussion—The EPA is the implementing agency
Maintaining Sumps and Spill Buckets—Practical Help
on tribal land.
and Checklist
3.1.8 maintenance, n—the normal operational upkeep to
Title 40 CFR 280 Technical Standards and Corrective
prevent an UST system from releasing product.
Action Requirements for Owners and Operators of Under-
ground Storage Tanks (UST) 3.1.9 motor fuels, n—petroleum or a petroleum-based sub-
stance that is motor gasoline, aviation gasoline, No. 1 or No. 2
3. Terminology
diesel fuel, or any grade of gasohol and is typically used in the
3.1 Definitions:
operation of a motor engine.
3.1.1 ancillary equipment, n—any devices that are used to
3.1.9.1 Discussion—This definition applies to blended pe-
distribute, meter, or control the flow of regulated substances
troleum motor fuels such as biodiesel and ethanol blends that
into or out of an UST, including, but not limited to, piping,
contain more than a de minimis amount of petroleum or
fittings, flanges, valves, and pumps.
petroleum-based substance.
3.1.2 cathodic protection tester, n—a person who can dem-
3.1.10 operator, n—any person in control of, or having
onstrate an understanding of the principles and measurements
responsibility for, the daily operation of the UST system. The
of all common types of cathodic protection systems as applied
Underground Storage Tank Compliance Act of 2005 further
to buried or submerged metal piping and tank systems; at a
characterizes three operator classes, A, B, and C.
minimum,suchpersonsmusthaveeducationandexperiencein
3.1.10.1 operator, Class A, n—an individual whose primary
soil resistivity, stray current, structure-to-soil potential, and
responsibility is to operate and maintain the underground
component electrical isolation measurements of buried metal
storage tank system.
piping and tank systems.
3.1.10.1 Discussion—This could include managing re-
3.1.3 corrective action, v—the sequence of actions per-
sources and personnel—such as establishing work
formedinresponsetoareleasethatincludesiteassessmentand
assignments—to achieve and maintain compliance with regu-
investigation, response actions, interim remedial action, reme-
latory requirements.
dial action, operation and maintenance of remediation
3.1.10.2 operator, Class B, n—implements the day-to-day
equipment, monitoring of progress, and termination of the
aspects of operating, maintaining, and record keeping for
remedial action.
underground storage tanks at one or more facilities.
3.1.4 gasoline dispensing facilities, n—also known as a
3.1.10.3 operator, Class C, n—an employee who, generally,
filling station and service station, means any stationary facility
is the first line of response to events indicating emergency
which dispenses gasoline into the fuel tank of a motor vehicle.
conditions.
3.1.5 hazardous substance, n—any substance defined or
listed in the Comprehensive Environmental Response,
3.1.10.4 Discussion—This individual is responsible for re-
Compensation, and Liability Act of 1980 (CERCLA),
sponding to alarms or other indications of emergencies caused
§101(14), (42 U.S.C. §9601(14), and which is not regulated as
by spills or releases from underground storage tank systems.
ahazardouswasteundertheSolidWasteDisposalAct,Subtitle
This individual notifies the Class B or Class A operator and
C, (42 U.S.C. §6921, et seq.).
appropriate emergency responders when necessary. Not all
3.1.5.1 Discussion—A hazardous substance does not in-
employees of the facility are necessarily Class C operators.
clude petroleum product or crude oil. This definition is
3.1.11 overfill, n—a release that occurs when an UST
modeled on 40 CFR §280.12.
system is filled beyond its capacity, thereby resulting in a
discharge of a regulated substance to the surface or subsurface
3.1.6 hazardous substance UST system, n—an UST system
environment.
that contains a hazardous substance defined in the Comprehen-
sive Environmental Response, Compensation, and Liability
3.1.12 owner, n—means any person who owns an UST
Act of 1980 (CERCLA), §101(14), (42 U.S.C. §9601(14) (but
system used for storage, use, or dispensing of regulated
not including any substance regulated as a hazardous waste
substances.
under the Solid Waste Disposal Act, Subtitle C, (42 U.S.C.
3.1.13 petroleum substance—includes crude oil or any frac-
§6921 et seq.)) or any mixture of such substances and
tion thereof that is liquid at standard conditions of temperature
petroleum, and which is not a petroleum UST system.
and pressure.
3.1.13.1 Discussion—The term includes petroleum-based
Available from United States Environmental Protection Agency (EPA), Ariel
substances comprised of a complex blend of hydrocarbons
Rios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20004, http://
www.epa.gov. derived from crude oil through processes of separation,
E2681 − 21
conversion, upgrading, and finishing, (for example, motor 3.1.26 suction piping, n—product or delivery piping in an
fuels, aviation gasoline, gas-turbine fuel oils, illuminating oils, USTsystemthattypicallyoperatesbelowatmosphericpressure
distillate fuel oils, residual fuel oils, jet fuels, lubricants, and transfers fluids from the storage tank as a result of low
petroleum solvents, used oils). pressure of the suction side of a pump.
3.1.27 suspected release, n—released product discovered at
3.1.14 petroleum UST system, n—an underground storage
or near the UST site; observed unusual operating conditions,
tanksystemthatcontainsapetroleumsubstanceoramixtureof
such as apparent loss of product; or results from a release
petroleum substances with de minimis quantities of other
detection method that indicates a release.
regulated substances.
3.1.27.1 Discussion—Suspected release does not include
3.1.14.1 Discussion—Such systems include those contain-
situations where a method or equipment is found to be
ing motor fuels, jet fuels, distillate fuel oils, residual fuel oils,
defective, is immediately corrected, and then indicates no
lubricants, petroleum solvents, and used oils.
release.
3.1.15 piping, n—all underground pipes in an UST system,
3.1.28 tank system, n—a tank system consists of the UST;
including valves, elbows, joints, flanges, flexible connectors,
all associated underground piping and ancillary equipment;
and other fittings attached to a tank system through which
spill and overfill prevention equipment; release detection
regulated substances flow, or in which regulated substances are
equipment; corrosion protection system; secondary contain-
contained or stored.
ment equipment (as applicable); and all other related systems
3.1.16 pressurized piping, n—product or delivery piping in
and equipment.
a UST system that typically operates at greater than atmo-
3.1.29 underground storage tank (UST), n—any one or
spheric pressure.
combination of underground tanks and any connecting under-
3.1.17 regulated substance, n—a hazardous substance as ground pipes used to contain an accumulation of regulated
defined in 3.1.5, a petroleum substance as defined in 3.1.13,
substances, the volume of which, including the volume of the
and any mixture of two or more hazardous substances and/or connecting underground pipes, is 10 % or more beneath the
petroleum substances; this definition is considered to be
surface of the ground.
equivalent to the definition in 40 CFR §280.12.
3.1.29.1 Discussion—This term does not include any of the
devices, equipment and facilities excluded from the definition
3.1.18 release, n—any spilling, leaking, emitting,
of underground storage tank in 40 CFR §280.12 or are listed in
discharging, escaping, leaching, or disposing from a tank
40CFR§§280.10(b)&(c)asnotsubjecttoregulationinwhole
system into groundwater, surface water, or soils.
or in part under 40 CFR §280.12.
3.1.19 release detection, n—determining whether a release
3.1.30 upgrading, v—the addition, improvement,
of a regulated substance has occurred from the UST system
retrofitting, or renovation of an existing UST system with
into the environment or into the interstitial space between the
equipment or components as required to meet the corrosion
UST system and its secondary barrier or secondary contain-
protection, spill and overfill prevention, and release detection
ment around it.
requirements.
3.1.20 repair, v—the restoration, renovation, or mending of
a damaged or malfunctioning UST system component.
4. Significance and Use
3.1.21 replaced tank, n—this means to remove a tank and
4.1 Environmentally sound management of underground
install another tank.
storage tank systems involves a broad range of preventative
maintenance activities directed toward preventing accidental
3.1.22 replaced piping, n—this means to remove 50 percent
releases of regulated substances, and effectively detecting and
or more of piping, excluding connectors, connected to a single
responding to such releases when, and if, they do occur.
tank and install other piping.
Numerous technical guidelines are presently available address-
3.1.22.1 Discussion—For tanks with multiple piping runs, ing specific procedures for release prevention and response for
replaced piping applies independently to each piping run. underground tank systems, including guidelines for tank sys-
tem design, installation, operation and maintenance, leak
3.1.23 secondary containment or secondarily contained,
detection,spillcontrol,periodicequipmentinspections,correc-
n—a release prevention and release detection system for a tank
tive action for affected environmental media, tank system
or piping utilizing an inner and outer barrier with an interstitial
closure,andoperatortraining.Thisguidepresentsanoverview,
space that is monitored for leaks.
identifying key management considerations and referring the
3.1.23.1 Discussion—This term includes containment
user to other related ASTM standards and industry guidelines
sumps when used for interstitial monitoring of piping.
for more detailed information.
3.1.24 spill, n—a release of a regulated substance which
4.2 Tank System Design and Installation—The first step in
results during the filling, placement, removal, or transfer of
environmentally sound management of tank systems is to
regulated substances to, or from, a UST system.
design and install the tank system so as to minimize the
3.1.25 standard conditions of temperature and pressure, potential for release of regulated substances to the environ-
n—a temperature of 60 °F and an atmospheric pressure of 14.7 ment. This guide addresses key considerations related to the
psi absolute. types of tank systems to be used, compatibility of regulated
E2681 − 21
substancestoconstructionmaterials,typesofspillcontainment for future releases or safety hazards. This guide reviews the
and overfill prevention devices, corrosion protection, leak general procedures for properly removing tank systems from
detection proper installation practices, and system operation. service,aswellastheoptionsfortanksystemclosurebymeans
of tank excavation and backfill placement or in-place closure
4.3 Preventative Maintenance—Even for properly designed
methods.
and installed tank systems, practical measures are needed to
4.9 Tank Management Practice Education, and Operator
detect and terminate leaks and respond to releases in a timely
Training—Personnel training is a key element of successful
manner so as to minimize regulated substance losses and
environmental management of UST systems. It is important
associated environmental effects. This guide reviews general
that persons involved in the installation, operation, or mainte-
considerations including release detection measures, possible
nance of tank systems understand the release prevention,
indicators of a release, appropriate record-keeping procedures,
tank system inspection, equipment testing, response planning appropriate leak detection, and response procedures. This
guide outlines the scope and schedule of several key training
and release control measures. Some preventative maintenance
activities are recommended while others are mandated by state areas that may be appropriate depending on individual job
assignments, including: tank system installation and mainte-
orfederalregulations.Thisguideaddressesfederallymandated
activities nance; general measures for release prevention; leak detection
equipment operation and maintenance; release control and
4.4 Inspections—Inspections are a critical component of a
emergency response measures; and regulated substance and
sound UST management plan. Both third-party professional
waste handling measures. This guide outlines the scope of
and operator inspections can identify potential risks associated
federally mandated operator training.
with component compromise and operational issues that may
4.10 Recognized Practice—Some federally mandated test-
increase the risk of an uncontained release. Some inspections
ing and inspection requirements can be satisfied by following
are required by regulatory requirements. The scope, frequency
a practice developed by a nationally recognized association or
and necessary qualifications to perform required inspections
independent testing laboratory such as provided in 40 CFR
varybyjurisdiction.Thisguideoutlinesthescopeandschedule
§280.35(a)(1)(ii)(B) and 40 CFR §280.40(a)(3). Many such
of federally required walkthrough inspections.
practices are referenced in this guide. Not all practices devel-
4.5 Equipment Testing—Testing can confirm the functional
oped by nationally recognized associations or independent
status of various UST components. Some UST equipment and
testing laboratories are accepted by the USEPA or the imple-
components must be tested in accordance with federal regula-
menting agency. To determine if a practice satisfies the federal
tions. Spill prevention equipment and containment sumps used
requirements, the owner or operator should consult with the
for interstitial monitoring of piping must be tested at least once
implementing agency.
every three years. Electronic and mechanical release detection
components must be tested annually. Cathodic protection
5. UST System Design and Installation
systems must be tested within six months of installation, then
5.1 Objectives—The first step in environmental manage-
at least every three years and within six months of any repair
ment of a tank system is to design and install the tank system
activity.Thisguideoutlinesthescopeandscheduleoffederally
to minimize the potential for release of petroleum or hazardous
required equipment testing.
substances into the environment. This involves careful plan-
4.6 Fueling Procedure—Careful loading, unloading, and
ning and an understanding of the importance for proper
dispensing of liquids to and from underground storage tanks is
installation of the appropriate type of tank for the application,
the most important day-to-day activity to ensure proper han-
compatibility of the materials in the system, with the substance
dling of liquids and prevention of releases. This guide is
tobestored,thetypesofspillcontainmentandoverfilldevices,
developed to addresses UST system management. Dispensers
and a comprehensive plan for system operation and mainte-
anddispensingactivitiesmaybesourcesofreleasesbutarenot
nance. Consider options available in the design that can affect
consideredacomponentoftheUSTsystemandarenotinclude
the use and maintenance of the tank, such as manways, striker
in the regulatory requirements addressed by this guide.
plates, and other options. Tanks, piping, and appurtenances
must be installed according to the manufactures’ instructions.
4.7 Corrective Action for Affected Environmental Media—
Following discovery and control of a release regulated sub- Alltanksshouldbetestedpriortoinstallationtoverifythetank
was not damaged during shipment. UST systems and system
stance from an underground tank system, corrective actions
components should only be installed by qualified persons
may be required for affected soil and groundwater as needed to
authorized by the manufacturer to install the equipment.
protect human health, safety, and environmental resources.
This guide reviews a risk-based process for investigation,
5.2 Certification of Installation—All owners and operators
evaluation, and remediation of affected environmental media
of new UST systems must certify in the Notification for
consistent with the guidelines provided in Guide E2081.
Underground Storage Tanks (EPA Form 7530-1) compliance
with the following requirements:
4.8 Tank System Closure—If it is determined that an under-
5.2.1 Installation of the UST system under 40 CFR
ground tank system will no longer be used to store regulated
§280.20(e);
substances, the system must be taken out of service, either
temporarilyorpermanently,and,whenappropriate,decommis- 5.2.2 Cathodic protection of steel tanks and piping under 40
sioned and removed in a manner that minimizes the potential CFR §§280.20 (a) and (b);
E2681 − 21
5.2.3 Releasedetectionunder40CFR§§280.41and280.42. sumps (including submersible turbine sumps and under dis-
penser containment); penetration boots; release detection
5.2.4 All owners and operators of new UST systems must
floats,sensors,andprobes;fillandrisercaps;andproductshear
require that the installer certifies in the notification form that
valve.
themethodsusedtoinstallthetheUSTsystemcomplywiththe
requirements in 40 CFR §280.20(d).
5.4 Construction Materials for Tanks:
5.2.5 System Design and Installation—Qualifications for
5.4.1 There are three classes (metal, nonmetal, composite)
installers vary by regulatory jurisdiction. Many states require
of tanks for storing regulated substances. Each tank may have
licensing or certification. Check with the implementing agency
different and/or better applications in certain situations. The
for specific qualification requirements.
benefits and features of a tank system for a particular site can
5.2.6 General Requirements—UST systems installed after
be evaluated by a licensed professional engineer or other
April 11, 2016 must be secondarily contained and must use
competent person. The tank owner has the responsibility of
interstitial monitoring as the primary leak detection method.
determining the appropriate tank for their application. Criteria
a tank owner should use to determine an appropriate type of
5.3 Material Compatibility: Federal regulations require that
tank for use include, but are not limited to:
UST systems be compatible with the substance stored. Incom-
5.4.1.1 Regulated substance that will be stored in the tank.
patibility between regulated substances stored and USTsystem
5.4.1.2 Soil type/corrosiveness of the soil.
materials can result in equipment or components such as tanks,
5.4.1.3 Hydrogeology(depthtowatertable,highpermeabil-
piping,gaskets,orsealsbecomingbrittle,elongated,thinner,or
ity of geologic subgrade, proximity to water wells, amount of
swollen when compared with their condition when first in-
precipitation/climatic conditions).
stalled. When this occurs, the UST system may fail to contain
5.4.1.4 Geologic hazards (seismically induced liquefaction;
the regulated substance resulting in a release to the environ-
landslides; active faulting; strong ground-motion).
ment and possible failure to detect the release.
5.4.2 Fiberglass Reinforced Plastic Tanks (FRP):
5.3.1 Construction materials must include materials that
5.4.2.1 The fiberglass reinforced plastic tank is manufac-
provide protection against corrosion or are resistant to corro-
tured from thermosetting resin reinforced with chopped or
sion. Tank systems including tanks, lines, fittings, and associ-
strand fiberglass. FRP tanks are considered to be resistant to
ated piping must be constructed of, or lined with, materials
exterior corrosion due to contact with the soil. FRP tanks are
compatible with the substance stored. Incompatibility of ma-
relatively lighter than steel tanks, but are typically a bit longer
terials could result in the structural deterioration of the tank
due to dome end caps. These tanks are manufactured to UL
piping, or other system components and potentially cause a
1316 requirements. These tanks meet the corrosion protection
release of regulated substance into the environment. Use
requirements as outlined under UST tank rules (40 CFR
approved or listed corrosion-resistant materials or systems as
§280.20(a)(1)). These tanks are available as single, double, or
indicated in NFPA 30 and NFPA 30A. API RP 1626 provides
triple wall tanks. FRP tanks can be purchased with multiple
information on the storage of ethanol systems. UL87A applies
compartments. FRP tanks with interstitial spaces can be
to tank systems with ethanol blends.
monitored with liquid brine solution (useful in high water table
NOTE 1—The tank system includes ancillary equipment.
applications), dry area sensors, or vacuum.
5.3.2 Arecommended source of material compatibility data
5.4.2.2 UL1316 provides options for testing FRPtanks to a
is the NACE Corrosion Data Survey, Metals and Nonmetals broad spectrum of transportation fuels including all blends of
Section.
ethanol. As with all tanks, it is necessary to check the
compatibility of the regulated substance being stored with the
NOTE 2—The owner/operator may want to obtain an opinion from an
particular resin used by the tank manufacturer. FRP tanks are
independentthird-partytechnicalexpertonthematerialcompatibility,and
tolerant of the presence of normal water bottoms found in
obtain a certificate of compatibility, attesting the materials used for
modifications, repairs, or upgrades made to the existing UST system are
product tanks.
compatible with the material stored and dispensed.
5.4.2.3 In addition to contacting the manufacturers of such
containers, further information on FRP tanks can be obtained
5.3.3 Biofuel Compatibility—Chemical and physical prop-
from the Fiberglass Tank and Pipe Institute.
erties of ethanol and biodiesel blends may make them more
aggressive to certain UST system materials than petroleum, 5.4.3 Steel Tanks:
therefore it is important that all UST system components in 5.4.3.1 An underground steel storage tank consists of a
contact with ethanol or biodiesel blends are materially com- single-wall, or double-wall, carbon steel tank with one of a
patible with that fuel. Owners storing ethanol-blended fuels varietyofexternalcorrosionprotectionsystems.Steeltanksare
greater than 10 percent ethanol or biodiesel-blended fuels generally constructed to UL 58 requirements. Steel tanks are
greaterthan20percentbiodieselmustdocumentthatallsystem available with multiple compartments. UL 1746 addresses
components are compatible with the substance stored in external corrosion protection system for the steel tank. These
compliance with 40 CFR 280.32. Components that must be tanks are compatible with most petroleum products. It is
compatibleincludetankorinternaltanklining;piping;sealants important to determine the possible external and internal
(including pipe dope and thread sealant); line leak detector; corrosionmechanismsandprovidecorrosionprotectionagainst
flexible connectors; drop tube; spill and overfill prevention theexpectedcorrosionmechanisms.Steeltankscanbeaffected
equipment; submersible turbine pump and components, by internal microbial corrosion (MIC). Steel tanks can also be
fittings, gaskets, O-rings, bushings and couplings; containment affectedifwaterisallowedtoaccumulateinsidethetankunless
E2681 − 21
internally coated or unless they have internal cathodic protec- (2) Prior to regulated substances being transferred and
tion.SeeNote3.Adouble-wallsteeltankaffordstheadvantage deposited into a UST system, the available volume in the tank
of an interstitial space between the two steel walls that has the
is to be verified to ensure that this volume is greater than the
capability of being monitored to detect a breach between the volume of the regulated substance to be transferred into the
primary and secondary tank walls. STI F841-01 describes this
tank.
construction.
(3) During the entire time that the regulated substance is
being transferred into the UST system, the owner/operator
NOTE3—Alltanksystems,includingFRP,andallfuelscanbeimpacted
must ensure that the transfer operation is monitored constantly
by microbiological activities.
to prevent overfilling and spilling.
5.4.3.2 STI-P3 covers a method of underground exterior
(4) All spill and overfill prevention devices are to be
corrosion control for steel tanks. The method combines three
maintained in good operating condition, and the devices are to
basic corrosion control approaches. Namely, these are: (1)
be inspected and serviced in accordance with federal require-
protective coating to minimize metal exposure to the soil, (2)
ments and the manufacturer’s specifications.
cathodic protection using galvanic anodes to protect any
(5) ThetransfersofregulatedsubstancestoorfromanUST
exposed metal and to electrically isolate the UST from stray
system are to be in accordance with a nationally recognized
current corrosion, and (3) isolation devices to limit the area to
standard or code of practice. Refer to API RP 1007.
be cathodically protected.
5.5.2 Spill Prevention Equipment:
5.4.4 Composite Clad Steel Tanks:
5.5.2.1 Containment—The fill pipe of the tank is either
5.4.4.1 Composite clad steel underground storage tanks are
equipped with an attached spill container, sometimes referred
generally a UL 58 and UL 1746 listed steel tank with a thick
to as a spill bucket or catchment basin, or is enclosed in a
nonmetallic laminate such as fiberglass or urethane applied to
liquid-tight manway, riser, or sump.
thetankexteriorwhichprovidesasignificantdi-electricbarrier
(1) The spill containment device is to be equipped with a
between the steel tank and the electrically conductive solution,
liquid-tight lid or cover designed to minimize the entrance of
that is, electrolyte. The following specifications are two types
any surface water, groundwater, or other foreign substances
of these tanks:
into the device. Spill containment devices must be clean and
5.4.4.2 STI ACT-100, FRP Composite Steel Underground
empty prior to transfer operation so that they are capable of
Storage Tank, which consists of an FRP laminate to eliminate
holding any drips or spills that may occur when the transfer
metal-to-soil exposure.
hose is disconnected from the fill pipe.
5.4.4.3 STI ACT-100-U, Clad Composite Steel Under-
(2) Manufacturers may equip the spill container with either
ground Storage Tank, which includes a urethane cladding to
eliminate metal-to-soil exposure. a drain or a spark-free pump to remove liquids. The drain
allows any spilled product to be drained into the tank.
5.4.5 Jacketed Steel Tanks:
However, any water or other fluids or sediment that have
5.4.5.1 This tank design utilizes an inner UL 58 steel tank
accumulated within the spill container should be removed and
within an outer nonmetallic jacket (such as FRP) that is
disposed of properly. Spill containers are also available with a
typically UL 1746 listed. STI F922 describes one type of this
secondary container with monitor sensors.
construction.
(3) Spill containment device must be tested once every
5.4.5.2 Theouternonmetallictankjacketprovidescorrosion
three years for proper operation unless the device is double
resistance and secondary containment. There is a polyester
walled with periodic monitoring of the integrity of both walls
film/mesh standoff between the tanks and a factory installed
of the device.
vacuum gauge to monitor the interstitial space between the
tanks. The resulting tank has the strength of a steel tank with 5.5.2.2 Tight-fill Fitting—The fill pipe of the tank is to be
the corrosion resistance of a nonmetallic tank.
equipped with a tight-fill fitting, or similar device that provides
a liquid-tight seal during the transfer of regulated substances
5.5 Spill and Overfill Prevention and Control—Spill and
into the tank.
overfillcontainmentdevicesaredesignedtopreventreleasesof
5.5.3 Types of Overfill Protection Devices:
regulated substances that occur during the filling of the UST
5.5.3.1 Automatic Flow Restrictor—A device that restricts
system due to spills and overfills. Regulated substance UST
systems, where more than 25 gallons of product will be the flow of regulated substances into the tank when the liquid
transferred at any one time, must meet the minimum require- level in the tank reaches a preset level which is no higher than
ments of 40 CFR §280.20(c), EPA/510-R-05-001, and any the 95 % capacity level for the tank or at 30 minutes prior to
additional regulations required by the implementing agency. overfilling, provided that such flow restricting device also
alerts the person responsible for the delivery when such preset
5.5.1 General Requirements:
level is reached.
5.5.1.1 Thedesignofthespillandoverfillpreventionforthe
5.5.3.2 Pipe Ball Float Valve (or flow vent valve)—This
UST system must allow the system to be operated properly.
The general operational requirements that must be considered device is a form of flow restrictor which consists of a hollow
aluminum ball inside of a wire cage directly beneath the vent
for spill and overfill prevention are:
(1) All spill and overfill containment equipment are to be pipeopeninginsidetheUST.Asproductrisestowardthetopof
the tank, the ball floats up and closes the vent pipe, which
designed to prevent release of regulated substances to the
environment when the tank system is being filled. slowsthefuelcomingintothetank.Ballfloatvalvesshouldnot
E2681 − 21
be used if the tank receives pressurized deliveries, uses suction 5.6.2.1 Galvanic Anodes—In these systems, sacrificial an-
piping, or uses single point (coaxial) stage I vapor recovery. odes are attached to a coated steel UST to provide corrosion
protection.Likeitsnameimplies,sacrificialanodessacrificeor
5.5.3.3 Automatic Tank Gauge High Level Alarm—The
deplete in favor of the steel allowing the steel protection from
automatic tank gauge can be set to sound an alarm audible to
corrosion.
thefueltransferoperatorwhenthetankis90 %fulloriswithin
5.6.2.2 Impressed Current—These systems use direct cur-
one minute of being overfilled. The fuel transfer operator can
rent to combat rust and decay that affect metal. Current is
then shut off the fuel, thereby preventing an overfill.The alarm
supplied by an integral component of the system, a rectifier.
should be located in an area where the fuel transfer operator
5.6.2.3 CathodicProtectionInspections,TestingandRecord
can hear or see it to be effective.
Keeping:
5.5.3.4 Automatic Shut-Off—Adevicethatshuts-offtheflow
(1) All cathodic protection systems must be tested within
of regulated substances into the tank when the liquid level in
six months of installation, then at least every three years, and
the tank reaches a preset level, which is no higher than the
within six months of any repair activity by a cathodic protec-
95 % capacity level for the tank or before any of the fittings
tion tester to ensure that the cathodic protection system is
locatedontopofthetankareexposedtoproduct.Oneexample
operating properly. The criteria used to determine if cathodic
of an automatic shutoff device is a drop tube flapper valve
protection is adequate must be in accordance with a code of
which is installed on a drop tube in the fill pipe.Afloat rises as practicedevelopedbyanationallyrecognizedorganization(for
thetankisbeingfilled.Asthefuelnearsthetopofthetank,the example, NACE, API), such as API RP 1632. Owners and
operators must keep records of the last two tests and have a
valve closes and prevents liquid from coming into the UST.
qualified professional fix any problems discovered during
5.5.4 Overfill prevention equipment inspection—Overfill
testing.
preventionequipmentmustbeinspectedforproperoperationat
least once every three years according to requirements devel- NOTE 5—NACE RP0285 is a widely recognized standard and is written
into the federal regulations for determining adequate cathodic protection.
oped by the manufacturer, a code of practice developed by a
(2) Impressed current cathodic protection systems must be
nationally recognized association or independent testing labo-
inspected at least once every 60 days to make sure the
ratoryorrequirementsdeterminedbythestateorimplementing
equipment is running properly. Owners and operators may
agency to be no less protective than those developed by the
perform this inspection. Owners and operators must keep
manufacturer or in the code of practice.
records of the last three inspections and have a qualified
professionalfixanyproblemsdiscoveredduringtheinspection.
5.6 Corrosion Protection of Tank System—Tank and piping
See Note 5.
components that are in contact with the ground and routinely
contain product must be protected from corrosion in accor-
5.6.2.4 Internal Lining—A method of corrosion protection
dance with a code of practice developed by a nationally
for existing tanks (those where installation began on or before
recognized association or independent testing laboratory. If not
December 22, 1988) where the tank is inspected, prepared, and
properly protected, all metal components, including storage
internally lined with a noncorrodible material. Tanks installed
tanks, piping, connectors, and other metallic components, can after December 22, 1988 may not use this method to meet the
corrosion protection requirements.
deteriorate and permit leakage. Corrosion can be minimized
5.6.3 Records for Corrosion Protection:
with proper design and use of cathodic protection or the use of
nonmetallic materials. 5.6.3.1 There are a number of records that must be kept
related to corrosion protection. They are as follows:
5.6.1 General Requirements:
(1) Records must be maintained for testing that must be
5.6.1.1 Existing UST Systems (those where installation be-
accomplished within the following time periods: within the
gan on or before December 22, 1988)—Existing tanks must
fi
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