View source for Underground storage tank

{{short description|Storage tank that is partially or fully underground}}
{{Globalize|date=June 2015}}
[[Image:Underground.Storage.Tank.with.Anodes.jpg|thumb|A horizontal cylindrical [[steel]] tank with a factory-applied [[coating]] and [[Cathodic protection#Galvanic|galvanic anodes]] prior to installation underground.]]
[[File:412 DSP UndergroundTanks 098 - DPLA - ea412e25b0ed0b9d1c810e1c4bb28ceb.jpg|thumb|right|Underground storage tank removal in Washington, D.C.]]
An '''underground storage tank''' ('''UST''') is, according to United States federal regulations, a [[storage tank]], including any underground piping connected to the tank, that has at least 10 percent of its volume underground.

==Definition & Regulation in U.S. federal law==
"Underground storage tank" or "UST" means any one or combination of tanks including connected underground pipes that is used to contain regulated substances, and the volume of which including the volume of underground pipes is 10 percent or more beneath the surface of the ground.<ref>U.S. Environmental Protection Agency (EPA), Washington, D.C. [http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=3113bdbd55bf563c9663729770e6a78e&rgn=div8&view=text&node=40:26.0.1.1.10.1.47.3&idno=40 "Definitions."] {{Webarchive|url=https://web.archive.org/web/20110612155112/http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=3113bdbd55bf563c9663729770e6a78e&rgn=div8&view=text&node=40:26.0.1.1.10.1.47.3&idno=40 |date=2011-06-12 }} ''Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST).'' ''Code of Federal Regulations,'' {{CodeFedReg|40|280|12}}.</ref> This does not include, among other things, any farm or residential tank of 1,100 gallons or less capacity used for storing motor fuel for noncommercial purposes, tanks for storing [[heating oil]] for consumption on the premises, or [[septic tank]]s.

USTs are regulated in the United States by the [[United States Environmental Protection Agency|U.S. Environmental Protection Agency]] to prevent the leaking of petroleum or other hazardous substances and the resulting contamination of groundwater and soil.<ref>Horinko, Marianne, Cathryn Courtin. [http://www.epaalumni.org/hcp/rcra.pdf “Waste Management: A Half Century of Progress.”] EPA Alumni Association. March 2016.</ref> In 1984, U.S. Congress amended the Resource Conservation Recovery Act to include Subtitle I: Underground Storage Tanks, calling on the [[U.S. Environmental Protection Agency]] (EPA) to regulate the tanks. In 1985, when it was launched, there were more than 2 million tanks in the country and more than 750,000 owners and operators. The program was given 90 staff to oversee this responsibility.<ref>{{Cite web|url=https://www.epaalumni.org/userdata/pdf/602BCE06FAFAB29B.pdf#page=2|title=Transcript of 'The Underground Storage Tank Program's Early Management Challenges' video|last=Brand|first=Ron|date=August 24, 2013|website=EPA Alumni Association|access-date=August 26, 2018}}</ref> In September 1988, the EPA published initial underground storage tank regulations, including a 10-year phase-in period that required all operators to upgrade their USTs with spill prevention and leak detection equipment.<ref>EPA (1988-09-23). "Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST)." ''Federal Register,'' {{USFR|53|37194}}. 40 CFR Part 280.</ref>

For USTs in service in the United States, the EPA and states collectively require tank operators to take financial responsibility for any releases or leaks associated with the operation of those below ground tanks. As a condition to keep a tank in operation a demonstrated ability to pay for any release must be shown via UST insurance, a bond, or some other ability to pay.<ref>{{cite report|url=https://www.epa.gov/sites/production/files/2014-03/documents/dolsens.pdf|title=Financial Responsibility Requirements for Underground Storage Tanks|date=July 1995|publisher=EPA|id=EPA 510-K-95-004|series=Dollars and Sense}}</ref>

EPA updated UST and state program approval regulations in 2015, the first major changes since 1988.<ref name="EPA 2015-07-15">EPA (2015-07-15). "Revising Underground Storage Tank Regulations-Revisions to Existing Requirements and New Requirements for Secondary Containment and Operator Training." ''Federal Register,'' {{usfr|80|41565}}</ref> The revisions increase the emphasis on properly operating and maintaining UST equipment. The revisions will help prevent and detect UST releases, which are a leading source of groundwater contamination. The revisions will also help ensure all USTs in the United States, including those in Indian country, meet the same minimum standards. The changes established federal requirements that are similar to key portions of the [[Energy Policy Act of 2005]]. In addition, EPA added new operation and maintenance requirements and addressed UST systems deferred in the 1988 UST regulation. The changes:

* Added secondary containment requirements for new and replaced tanks and piping
* Added operator training requirements
* Added periodic operation and maintenance requirements for UST systems
* Added requirements to ensure UST system compatibility before storing certain biofuel blends
* Removed past deferrals for emergency generator tanks, field constructed tanks, and airport hydrant systems
* Updated codes of practice
* Made editorial and technical corrections.<ref name="EPA 2015-07-15"/>

==Tank types==
{{unreferenced section|date=June 2015}}
Underground storage tanks fall into four different types:

#[[Steel]]/[[aluminum]] tanks, made by manufacturers in most states and conforming to standards set by the Steel Tank Institute.
#[[Composite material|Composite overwrapped]], a metal tank (aluminum/steel) with filament windings like [[glass fiber]]/[[aramid]] or [[carbon fiber]] or a plastic compound around the metal cylinder for corrosion protection and to form an interstitial space.
#Tanks made from [[composite material]], [[fiberglass]]/[[aramid]] or [[carbon fiber]] with a metal liner (aluminum or steel). See [[metal matrix composite]].
# Composite tanks such as carbon fiber with a polymer liner ([[thermoplastic]]). See [[rotational molding]] and [[fibre-reinforced plastic]] (FRP).

Underground storage tanks for water are traditionally called [[cistern]]s and are usually constructed from [[brick]]s and [[mortar (masonry)|mortar]] or [[concrete]].

==Petroleum underground storage tanks==
[[Petroleum]] USTs are used throughout North America at automobile [[filling stations]] and by the US military. Many have [[leak]]ed, allowing petroleum to contaminate the [[soil]] and [[groundwater]] and enter as vapor into buildings, ending up as brownfields or Superfund sites.{{citation needed|date=June 2015}} Many USTs installed before 1980 consisted of bare [[steel]] pipes, which [[corrosion|corrode]] over time.{{citation needed|date=June 2015}} Faulty installation can also cause structural failure of the tank or piping, causing leaks.<ref>{{cite web |url=https://www.epa.gov/ust/resources-ust-owners-and-operators#installing |title=Resources for UST Owners and Operators |publisher=US EPA |website=EPA.gov |access-date=April 20, 2018|date=2014-06-09 }}</ref>

===Regulation in the US===
The 1984 Hazardous and Solid Waste Amendments to the [[Resource Conservation and Recovery Act]] (RCRA) required EPA to develop regulations for the underground storage of motor fuels to minimize and prevent environmental damage, by mandating owners and operators of UST systems to verify, maintain, and clean up sites damaged by petroleum contamination.<ref name="HSWA statute">United States. Hazardous and Solid Wastes Amendments of 1984, P.L. 98-616, {{USStat|98|3224}}, November 8, 1984.</ref>

In December 1988, EPA regulations asking owners to locate, remove, upgrade, or replace underground storage tanks became effective. Each state was given authority to establish such a program within its own jurisdiction, to compensate owners for the cleanup of underground petroleum leaks, to set standards and licensing for installers, and to register and inspect underground tanks.{{citation needed|date=June 2015}}

Most upgrades to USTs consisted {{when|date=June 2015}} of the installation of corrosion control ([[cathodic protection]], interior lining, or a combination of cathodic protection and interior lining), overfill protection (to prevent overfills of the tank during tank filling operations), [[oil spill|spill containment]] (to catch spills when filling), and [[leak#Leak testing|leak detection]] for both the tank and piping.{{citation needed|date=June 2015}}

Many USTs were removed without replacement during the 10-year program. Many thousands of old underground tanks were replaced with newer tanks made of corrosion resistant materials (such as [[fiberglass]], steel clad with a thick [[Fibre-reinforced plastic|FRP]] shell, and well-coated steel with [[galvanic anodes]]) and others constructed as double walled tanks to form an interstice between two tank walls (a tank within a tank) which allowed for the detection of leaks from the inner or outer tank wall through monitoring of the interstice using vacuum, pressure or a liquid sensor probe. Piping was replaced during the same period with much of the new piping being double-wall construction and made of fiberglass or [[plastic]] materials.{{citation needed|date=June 2015}}

Tank monitoring systems capable of detecting small leaks (must be capable of detecting a 0.1 gallons-per-hour with a probability of detection of 95% or greater and a probability of false alarm of 5% or less) were installed and other methods were adopted to alert the tank operator of leaks and potential leaks.{{citation needed|date=June 2015}}

U.S. regulations required that UST cathodic protection systems be tested by a cathodic protection expert (minimum every three years) and that systems be monitored to ensure continued compliant operation.<ref>EPA. [http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=3113bdbd55bf563c9663729770e6a78e&rgn=div8&view=text&node=40:26.0.1.1.10.3.47.2&idno=40 "Operation and maintenance of corrosion protection."] {{webarchive|url=https://web.archive.org/web/20110612155036/http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=3113bdbd55bf563c9663729770e6a78e&rgn=div8&view=text&node=40:26.0.1.1.10.3.47.2&idno=40 |date=2011-06-12 }} ''Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST).'' ''Code of Federal Regulations,'' {{CodeFedReg|40|280|31}}.</ref>

Some industrial owners, who previously stored fuel in underground tanks, switched to above-ground tanks to avoid environmental regulations that require monitoring of fuel storage. Many states, however, do not permit above-ground storage of motor fuel for resale to the public.

The EPA Underground Storage Tank Program is considered to have been very successful.{{according to whom|date=June 2015}} The national inventory of underground tanks has been reduced by more than half, and most of the rest have been replaced or upgraded to much safer standards.{{citation needed|date=June 2015}} Of the approximately one million underground storage tanks sites in the United States as of 2008, most of which handled some type of fuel, an estimated 500,000 have had leaks.<ref>Eileen Sullivan, [http://talkingpointsmemo.com/news/2008/08/ap_impact_underground_fema_fue_1.php "Cold War era fuel tanks could be leaking hazardous material into environment"] {{Webarchive|url=https://web.archive.org/web/20080822083617/http://talkingpointsmemo.com/news/2008/08/ap_impact_underground_fema_fue_1.php |date=2008-08-22 }}, ''Associated Press'', August 12, 2008</ref> {{As of|2009}}, there were approximately 600,000 active USTs at 223,000 sites subject to federal regulation.<ref name="EPA UST 2009">EPA (2010). [http://www.epa.gov/oust/pubs/fy09_annual_ust_report_3-10.pdf "FY 2009 Annual Report On The Underground Storage Tank Program."] Document no. EPA-510-R-10-001.</ref>
In 2012, EPA published how to screen buildings vulnerable to petroleum [[vapor intrusion]],<ref name=screen>{{cite web|author1=John T. Wilson, James W. Weaver, Hal White|title=An Approach for Developing Site-Specific Lateral and Vertical Inclusion Zones within which Structures Should be Evaluated for Petroleum Vapor Intrusion due to Releases of Motor Fuel from Underground Storage Tanks (EPA 600/R-13/047)|url=http://www.epa.gov/oust/cat/pvi/epa600r13047.pdf|publisher=US EPA|access-date=13 June 2015|pages=34|date=December 2012}}</ref> and in June 2015, U.S. EPA finally released its
"Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air"
and "Technical Guide For Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites"<ref name=pvidocs>{{cite web|title=EPA Technical Documents, Tools and Other Resources to Support Vapor Intrusion Assessment and Mitigation Activities|url=http://www.epa.gov/oswer/vaporintrusion/guidance.html#EO12866OSWERVI|publisher=US EPA|access-date=13 June 2015|date=12 June 2015}}</ref>

=== Definition in the UK ===
Similarly to the US, the UK defines an underground tank as having 10% of its combined potential volume below the ground.<ref>{{Cite web|url=https://www.raeng.org.uk/publications/other/3-ust|title=Underground Storage Tank - The Royal Academy of Engineering|last=Dr. Alan|first=Stevens|website=The Royal Academy of Engineering}}</ref>

=== Decommissioning an underground tank in the UK ===
The requirements set by The Environment Agency for Decommissioning an underground tank apply to all underground storage tanks and not just those used for the storage of fuels.<ref>{{Cite web|url=https://www.gov.uk/guidance/prevent-groundwater-pollution-from-underground-fuel-storage-tanks/decommissioning-an-underground-storage-tank|title=Prevent Groundwater Pollution from Underground Fuel Storage Tanks|last=Environment|first=Agency|date=29 February 2016|website=www.gov.uk}}</ref>  They give extensive guidance in [https://apea.org.uk/pages/publications/apea-publications The Blue Book] and [http://products.ihs.com/Ohsis-SEO/313516.html PETEL 65/34]. The Environment Agency states that any tank no longer in use should be immediately decommissioned. This process includes both the closing and removal of a UST system (the tank and any ancillaries connected to it) as a whole and the replacing of individual tanks or lengths of pipe. Regardless of whether the decommissioning of the tank is permanent or temporary; it must be ensured that the tank and all components don't cause pollution. This is true of the removal and of any filling of the tank with inert material.

The Decommissioning of a tank can be via removal from the ground after any volatile gas or liquid has been removed. This is called bottoming and degassing the tank. The other option involved filling the tank with either:

* A Sand and Cement Slurry
* Hydrophobic Foam
* Foamed Concrete

If any plan is made to leave the tank on site, the owner will be responsible for keeping record of:

* The Tank's Capacity
* The Product it Contained
* The Method used to Decommission the tank, if any
* The Date of the Decommissioning

If any tanks and their pipework have been deemed unsuitable for petroleum spirits then they shouldn't be used for the storage of any hydrocarbon based products without first checking their integrity.

==See also==
*[[Environmental impact of the petroleum industry]]

== References ==
{{Reflist|2}}

== External links ==
*[https://www.epa.gov/oust/ EPA UST Program]
*[https://www.epa.gov/ust/revising-underground-storage-tank-regulations-revisions-existing-requirements-and-new EPA summary of 2015 rule and compliance information]
* State UST programs:
**[http://www.swrcb.ca.gov/ust/ California]
**[http://www.nmenv.state.nm.us/ust/ustbtop.html New Mexico]
**[http://occeweb.com/ps/aboutpst1.html Oklahoma]
**[http://www.portal.state.pa.us/portal/server.pt?open=512&objID=20538&PageID=1034424&mode=2 Pennsylvania]
**[https://web.archive.org/web/20110518135447/http://www.tceq.texas.gov/agency/pst_cert.html Texas]
**[https://web.archive.org/web/20120302223237/http://dsps.wi.gov/er/er-bst-homepage.html Wisconsin]

[[Category:Oil storage]]
[[Category:Containers]]
[[Category:Fuels]]
[[Category:Filling stations]]
[[Category:Petroleum infrastructure]]
[[Category:Storage tanks]]