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Underground Storage Tanks (USTs)

UST Technical Compendium: Applicability, Definitions and Notification

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  • Question 1: Do the Part 280 requirements apply to process waste traps (oil-water separators) located at various Schlumburger manufacturing and metal finishing facilities? 
    [December 2, 1988 letter from Hunt and Hunt Engineering to Region VI]
    Answer: In general, oil water separator systems are either excluded or deferred from the regulations under one of the following provisions: as field constructed tanks and/or as waste water treatment tank systems subject (or not subject) to section 402 and 307(b) of the Clean Water Act. 
    [Undated letter to Mr. Hunt (PDF) (62 pp, 1 MB)]
  • Question 2: Who is responsible for UST tanks that are owned by one party, rented to a second party who in turn subleases them to a third party? 
    [February 2, 1989 letter from Elmer Street]
    Answer: All three parties could be subject to enforcement action should noncompliance be discovered. 

    [Undated letter to Mr. Street (PDF) (62 pp, 1 MB)]
  • Question 3: What does the term "deferred" mean in the context of Part IV-Analysis of Today's Rule (Paragraph A.3) in the September 23, 1988 Federal Register and does the deferral apply to fuel oil storage tanks for emergency generators at hospitals, commercial and industrial facilities? 
    [May 9, 1989 letter from R. G. MacDiarmid of Goetting & Associates]
    Answer: EPA is temporarily deferring Subpart D requirements for all emergency generator tanks regardless of location to allow time to develop workable release detection requirements for these tank systems. 
    [September 8, 1989 letter to Mr. MacDiarmid (PDF) (62 pp, 1 MB)]
  • Question 4: Is a recast concrete vaulted tank system housing a tank below grade exempt from Part 280 requirements? 
    [July 5, 1989 request from Virginia via Region III]
    Answer: Yes, "if the tank sits upon or above the surface of the floor and there is sufficient space to enable physical inspection of the tank bottom." (53 FR 37121) 
    [July 25, 1989 memorandum to Mr. Naylor (PDF) (62 pp, 1 MB)]
  • Question 5: Are mixtures of gasoline and methanol, e.g., M85, to be treated as motor fuel or hazardous substances under 40 CFR Part 280? 
    [July 14, 1989 request from Jim Wisuri of the Steel Tank Institute via Richard Wilson Office of Mobile Sources]
    Answer: M85 must be stored in a hazardous substance UST system because it contains 85 percent of a CERCLA-listed substance. Gasohols containing lesser amounts of methanol (generally, 2.5 to 5 percent) may be stored in petroleum UST systems. M85 can be stored in petroleum UST systems if a variance can be obtained, where allowed, by the implementing agency in accordance with the rule's requirements. 
    [December 3, 1989 letter to Mr. Wisuri (PDF) (62 pp, 1 MB)]
  • Question 6: Are a monastery's two 500-gallon underground storage tanks subject to UST regulations? 
    [September 19, 1989 letter from Senator Howell Heflin]
    Answer: No, as long as they store motor fuel that is non commercially used only by the monastery's residents. The monastery is considered a residence and, therefore, the regulatory exclusion for farm and residential USTs of 1,100 gallons or less storing motor fuel used for noncommercial purposes applies. 
    [October 6, 1989 letter to Senator Heflin (PDF) (62 pp, 1 MB)]
  • Question 7: Are owners of USTs primarily responsible for ensuring compliance with certain section of Part 280 (e.g., 280.21, 280.22, and 280.34)
    [December 27, 1989 letter from Alan Campbell of Dow, Lohnes & Albertson]
    Answer: The regulations do not provide that the owner will be held "primarily" responsible for complying with these requirements. Some provisions impose requirements on owners exclusively and some on both owners and operators. A careful reading is necessary to determine whether only one or both parties may be liable in the event of noncompliance.
    [January 19, 1990 letter to Mr. Campbell (PDF) (62 pp, 1 MB)]
  • Question 8: Is the language in the UST rule's preamble about the underground areas exclusion intended to imply that tanks in vaults are no different than aboveground tanks and regulated as such?
    [January 30, 1990 letter from Frances Phillips of Gardere & Wayne]
    Answer: The preamble's reference was simply meant to contrast vaulted systems as basically free from the problems that attend USTs and cause them to leak. Typical aboveground tanks are not in an enclosed space that is completely contained by a concrete barrier. The application of aboveground tank standards to vaulted tank systems may not be technically appropriate.
    [March 20, 1990 letter to Ms. Phillips (PDF) (62 pp, 1 MB)]
  • Question 9: Are USTs storing 3 products (alkylate H-2304, Aristol 360, and Aristol 400) comprised of a mixture of the C14-C30 alkyl derivatives of benzene regulated under 40 CFR Part 280?;
    [March 26, 1990 request from the Ohio State Fire Marshal via Region V]
    Answer: They are not regulated because they are not a listed hazardous substance, benzene is only present in de minimis quantities, and they do not belong in one of the general categories of petroleum (and are not derived from crude oil).
    [April 19, 1990 memorandum to Mr. Phillips (PDF) (62 pp, 1 MB)]
  • Question 10: [1990 referrals from several EPA regions] Does my tank qualify for the heating oil tank exemption?
    Answer: A decision tree (with notes) was provided to all the regions.
    [Decision Tree (PDF) (62 pp, 1 MB)]
  • Question 11: Can a form that utilizes slightly modified wording be used as a substitute for Appendix III to the rules?
    [May 29, 1990 letter from Ed Nieshoff of the Fiberglass Petroleum Tank and Pipe Institute (PDF) (62 pp, 1 MB)]
    Answer: Yes, the recommended form can be modified (as provided by Mr. Nieshoff) for use by the tank seller to inform the tank purchaser of their notification responsibilities under the rules.
    [July 11, 1990 letter to Mr. Nieshoff (PDF) (62 pp, 1 MB)]
  • Question 12: Why are municipalities not exempt from UST regulations?
    [September 25, 1990 letter from David England of Stewartstown, Borough, Pennsylvania]
    Answer: The Federal statute (Resource Conservation and Recovery Act as amended, section 9001(1)(A)) exempts farm and residential USTs storing less than 1,100 gallons of motor fuel for "noncommercial" purposes. This exemption does not extend to small USTs owned by municipalities and there is no technical basis to broaden in regulation the law's specific exemption.
    [November 1990 letter to Mr. England (PDF) (62 pp, 1 MB)]
  • Question 13: Are compartmentalized USTs considered one tank for purposes of regulation?
    [May 14, 1991 letter from the National Association of Texaco Wholesalers, Inc.]
    Answer: Compartmentalized tanks, and piping connected to it, are considered one tank system by EPA because they are manufactured, transported, installed, protected from corrosion, and often equipped with leak detection as a single unit. Please check with your State or local agency as they may interpret this question differently.
    [August 12, 1991 letter to Mr. West (PDF) (62 pp, 1 MB)]
  • Question 14: Is a 550 gallon UST storing gasoline at a nursery and landscaping business exempt from Part 280 regulations?
    [May 16, 1991 letter from Congressman Jontz]
    Answer: Generally, the "farm tank" exclusion applies to USTs located at nurseries where products for retail stores, garden centers, or landscaping businesses are grown and the fuel is used for agricultural purposes only.
    [Undated letter to Congressman Jontz (PDF) (62 pp, 1 MB)]
  • Question 15: Do the Part 280 requirements apply to the York Iceball Thermal Storage System consisting of a process whereby a 25 percent ethylene glycol 75 percent water solution is circulated between the ice ball storage tanks and chillers for the purpose of air conditioning a building during daylight hours?
    [August 5, 1991 letter from York International]
    Answer: No, the exclusion found at 280.10(b)(3) for "operational tanks" exempts this process from the regulations. The Thermal Storage System is similar to hydraulic lift tanks and electrical equipment tanks which are also included within this exclusion.
    [Undated letter to Ms. Thomas (PDF) (62 pp, 1 MB)]
  • Question 16: When are vaulted tank systems excluded from UST regulations?
    [August 21, 1991 letter from William Nowman of Halissco, Inc.]
    Answer: Tanks that are not supported by backfill, can be visually checked for evidence of leaks, and are built and installed to aboveground tank codes are not subject to EPA's UST regulations. In the example given, a vaulted tank system wherein the tank is within six inches of the vault on three sides and set back far enough on the fourth side for entry and inspection is not subject to the agency's UST regulations if the access provided on the fourth side is sufficient to observe evidence of a leak from anywhere on the tank vessel.
    [August 26, 1991 letter to Mr. Nowman (PDF) (62 pp, 1 MB)]
  • Question 17: Are crude oil production gathering lines exempt from jurisdiction under the UST program?
    Answer: Yes, these gathering lines are exempt from jurisdiction under the UST technical regulations. (For more details on gathering lines, see page 37121 of the regulation's preamble, "Liquid Traps or Gathering Lines Related to Oil or Gas Production and Gathering Operations.")
    [There is no additional material included for this answer]
  • Question 18: Are Subtitle C tanks exempt from the UST regulations? Are Subtitle I tanks on a Subtitle C site exempt from the UST regulations?
    Answer: Subtitle C tanks are regulated under Subtitle C; the statute excludes their coverage under Subtitle I. Subtitle I will apply to tanks storing regulated substances, including corrective action on a subtitle C site without a RCRA permit. UST corrective actions underway at facilities having interim status under RCRA may be subject to review under Subtitle C during the development of the final permit (see final rule preamble, page 37176). 
    [There is no additional material included for this answer]
  • Question 19: A new tank system was installed which violated the interim prohibition standards since the piping was not cathodically protected.  The owner of this tank system sold the tank.  Who is responsible for the interim prohibition violation, the previous owner or the new owner?
    Answer: Either can be held responsible by the implementing agency.  the original owner was in violation of the interim prohibition regulations and was responsible for protecting the piping.  An enforceable violation remains at the site, even under new ownership.  the implementing agency can pursue immediate compliance from the present owner or the past owner (if the past owner can be found). 
    [There is no additional material included for this answer]
  • Question 20: Does the emergency spill or overflow containment exemption of 40 CFR 280.10(b)(6) apply to sumps used to contain diesel fuel discharges from electric power generation turbines?
    [August 28, 1991 letter from James Hamula]
    Answer: The sumps are not used for an emergency spill, leak, or other unplanned occurrence. The sumps are designed to collect diesel fuel from an electric power generation turbine immediately after a false start. While these false starts are periodic, they are not emergencies. Therefore, the false start sumps described in your letter are subject to the 40 CFR Part 280 requirements.
    [October 7, 1991 letter to Mr. Hamula (PDF) (62 pp, 1 MB)]
  • Question 21: What substances are regulated as hazardous substances for USTs?
    Answer: Please see the CERCLA hazardous substance list. 
    [CERCLA hazardous substance list]
  • Question 22: Do tanks at a livestock exchange where livestock are sold on a commission basis and are not raised or bred qualify for the farm-tank exclusion?
    [July 16, 1992 letter from Jean Riley of the Montana Petroleum Tank Release Compensation Board]
    Answer: No, although the preamble to the regulation does not deal specifically with livestock exchanges, it clearly excludes from the definition of farm tank retail stores and nursery centers where agricultural products are "marketed, but not produced." A similar situation exists with livestock exchanges where livestock is solely marketed, but not raised. Thus, the mere fact that a tank is somehow associated with agricultural operations does not, by itself, allow the tank to be defined as a "farm" tank for purposes of the farm-tank exclusion under Subtitle I of RCRA.
    [November 19, 1992 letter to Ms. Riley (PDF) (62 pp, 1 MB)]
  • Question 23: A company stores diesel fuel in an underground tank.  The diesel fuel is burned as a substitute for heating oil in an on-site furnace.  The definition of underground storage tank (UST) in 40 CFR 2801.2(b) excludes any tank used for storing heating oil for consumptive use on the premises where stored.  Does the underground tank storing diesel fuel meet this exclusion?
    Answer: An underground tank storing diesel fuel will meet this exclusion if the diesel fuel will be substituted for heating oil; i.e., burned in a unit designed to use heating oil.  the exclusion to the definition of UST in subsection 280.12(b) as No. 1, No. 2, No. 4-light, No. 4-heavy, No. 5-light, No. 5-heavy, and No. 6 technical grades of fuel oil; residual fuel oils (including navy Special Fuel Oil and Bunker C) and fuel substitutes such as kerosene and diesel fuel when used for heating purposes (53 FR 37117; September 23, 1988).  A tank storing diesel fuel that will be burned as an alternative to one of these eight types of heating oil in a unit designed to burn heating oil is excluded from the definition of UST.  If on the other hand, the diesel fuel is being used for some other purpose, such as to power an internal combustion engine or an emergency generator, the tank would not meet this exclusion.  The question of whether tanks associated with emergency power generators are excluded from the UST definition under the heating oil exclusion is somewhat complex.  A discussion on page 37118 of the September 23, 1988 Federal Register specifically addresses such tanks.  The language indicated that the use of heating oil itself is not limited to heating, but may include other on-site uses, such as emergency generators.  This discussion does not incorporate or address the stipulation that USTs containing fuels other than heating oil are only exempt if the fuel is burned as a substitute for heating oil in units designed for heating oil.  Therefore, the language on page 37117 should be consulted for tanks containing other fuels such as diesel fuel.
    The second part of the exemption involves the meaning of consumptive use.  The exclusion applies to heating oil used at the same site where it is stored, but not to heating oil that is stored prior to resale, marketing or distribution.  Consumptive use of heating oil is not limited to burning in a heater, but instead is defined as an on-site use (53 FR 37117).  Therefore, the subsection 280.12(b) exclusion from the definition os UST applies to (1) tanks storing one of the eight technical grades of fuel oil prior to any on-site use, and (2) tanks storing fuel oil substitutes prior to use for on-site heating purposes only.
    [There is no additional material included for this answer]
  • Question 24: Section 301 of the Clean Air Act Amendments of 1990 modifies the Clean Air Act (CAA) of 1986 by incorporating within subsection 112 a list of 189 hazardous air pollutants. Many of these pollutants were not previously regulated under the CAA. Would an underground storage tank (UST) containing a newly designated CAA hazardous air pollutant be subject to the standards promulgated in 40 CFR Part 280?
    Answer: Yes. Owners and operators of USTs containing regulated substances, as defined in subsection 280.12, must comply with the Part 280 standards. A regulated substance is any hazardous substance designated pursuant to subsection 101(14) of CERCLA (excluding any substance regulated as a hazardous waste under Subtitle C of RCRA), and petroleum products or any fraction thereof. The term hazardous substance under subsection 101(14) of CERCLA is defined as any substance designated pursuant to subsection 3001 of RCRA, subsection 112 of the CAA, subsections 307(a) and 311(b)(2)(A) of the Federal Water Pollution Act, subsection 7 of the Toxic Substances Control Act, and any substance so designated in subsection 102 of CERCLA. When a substance is added under statute identified in CERCLA subsection 101(14) it would then become a CERCLA hazardous substance by statutory definition and therefore become a regulated substance under Part 280. Note that any of the new substances or chemical categories added to the CAA that are CERCLA hazardous substances (e.g., ethylene glycol) or petroleum products are subject to regulation under Part 280 and this would not change.
    [There is no additional material included for this answer]
  • Question 25: In a manufacturing operation a coating which contains regulated substances is applied to metal part that is manufactured on-site. The metal part is coated using the following steps. After machining processes are completed, individual metal parts are clipped to the bottom of a chain which is attached at its top to an overhead conveyor system. The conveyor carries the metal part to an open-topped tank containing a coating solution. The tank meets the definition of "underground" provided in 40 CFR 280.12. Once over the tank, the conveyor system lowers the metal part into the coating solution. The metal part remains submerged in the solution as the conveyor travels the length of the tank, then the conveyor system raises the metal part out the tank. The metal part is then transported via the conveyor to any area where a facility employee unclips the part and places it on a drying pad. Would this tank be exempt from the UST regulations of 40 CFR Part 280, under the "flow through process tank" exclusion of 40 CFR 280.12?
    Answer: Yes, the tank would qualify for the exclusion because it meets the three necessary conditions to be considered a "flow-through process tank": it (1) forms an integral part of a production process; (2) has a steady, variable, recurring, or intermittent flow of materials through the tank during the operation of the process; and (3) is not used for the storage of materials prior to their introduction into the production process or for the storage of finished products or byproducts from the production process. These conditions are met because the production process (coating) actually occurs in the tank and therefore it is integral, and it does not store prior to or after production. The flow is intermittent, satisfying the second condition.
    [There is no additional material included for this answer]
  • Question 26: Are USTs storing pure toluene considered to be "petroleum" or "hazardous substance" UST systems, and are owners and operators of such tanks required to maintain proof of financial responsibility? 
    [May 27, 1993 letter from Robert C. Galbraith, General Counsel to the Iowa UST Fund Board]
    Answer: Toluene is a hazardous substance as defined under section 101(14) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Therefore, for regulatory purposes under Subtitle I, an UST storing pure toluene is considered to be a "hazardous substance UST system," as defined in Part 280.12 of the UST regulations. Although EPA has the statutory authority to require financial responsibility for hazardous substance USTs, such as those containing toluene, EPA does not currently require owners and operators of hazardous substance USTs to maintain financial responsibility for taking corrective action or compensating third parties for releases from those USTs.
    [June 4, 1993 letter to Mr. Galbraith (PDF) (62 pp, 1 MB)]
  • Question 27: Our office requests the term "annual" be defined for tank tightness testing, which is used in combination with monthly inventory control by many USTs to meet the release detection requirements. 
    [Initiated by January 8, 1993 letter from Walter Huff, Mississippi DEQ (PDF) (62 pp, 1 MB)]
    Answer: "Annual," as used in 280.41(a)(2) and 280.44(b) for tank and line tightness tests, means on or before the same date of the following year. Similarly, "every 5 years," as used in 280.41(a)(1), means on or before the same date five years later. States may have imposed more stringent requirements than EPA's, and regulators may take into consideration efforts taken by owners an operators to meet the requirements.
    [March 7, 1993 memorandum to UST/LUST Regional Program Managers (PDF) (62 pp, 1 MB)]
  • Question 28: For an UST properly lined prior to December 22, 1988, when does the time period begin for the initial 10 year-year and subsequent 5-year inspections of the lining? More specifically, must the lining be inspected within 10 years from the date the UST was properly lined or within 10 years of the effective date of the regulations? 
    [May 1994 inquiry from Virginia through Region III]
    Answer: For an owner/operator to comply with 40 CFR 280.21's lining requirements, the lining must be inspected (and found to be performing in accordance with original design specifications) within 10 years of properly lining the UST (i.e., on or before the same date ten years later) followed by subsequent 5 year inspections.
    [March 9, 1995 memorandum to Ms. Tan (PDF) (62 pp, 1 MB)]
  • Question 29: Request for clarification on the qualifications for "corrosion expert" and "cathodic protection tester."
    [February 2, 1994 letter from Kevin Garrity of NACE International]
    Answer: OUST revised this answer on March 31, 2011 to reflect revised NACE International certifications. Two NACE International certifications meet EPA’s regulatory definition of corrosion expert. These certifications are: "Corrosion Specialist" and "Cathodic Protection Specialist."
    EPA’s regulatory definition for cathodic protection tester does not require any specific certification; however, it does require education and experience in various corrosion areas. The following NACE International certification levels meet EPA’s definition of cathodic protection tester: “Cathodic Protection Technologist”; "Cathodic Protection Technician"; "Cathodic Protection Tester"; "Senior Corrosion Technologist"; "Corrosion Technologist"; and "Corrosion Technician". In addition, persons meeting EPA’s definition of corrosion expert would also meet EPA’s definition of cathodic protection tester.  Please note that NACE International requires persons holding a NACE certification of "Corrosion Technician" to be appropriately supervised when serving as a cathodic protection tester.
    [March 31, 2011 memorandum to state and federal UST/LUST Programs (PDF) (62 pp, 1 MB)]
    SUPERSEDED - [April 16, 2001 memorandum to state and federal UST/LUST Programs (PDF) (62 pp, 1 MB)]
    SUPERSEDED - [September 27, 1994 memorandum to state and federal UST/LUST Programs (PDF) (62 pp, 1 MB)]
  • Question 30: How does Subtitle I of RCRA apply to certain water covered tanks containing carbon disulfide?
    [Question from Region 4]
    Answer: These tanks are not regulated because they are not underground and do not meet the definition of an underground storage tank.
    [February 24, 1997 memorandum to Mr. Mason (PDF) (62 pp, 1 MB)]
  • Question 31: What is the definition of "every 3 years" as it applies to cathodic protection testing at 280.31(b)(1)? 
    [Question from Ms. Dorcee Lauen]
    Answer: The term "every 3 years" as it relates to 280.31(b)(1) means that a cathodic protection test must be conducted on or before the same day of the third year after the previous cathodic protection test has occurred.
    [September 20, 1999 letter to Ms. Dorcee Lauen (PDF) (62 pp, 1 MB)]
  • Question 32: Are UST systems containing E85 (approximately 85 percent ethanol and 15 percent gasoline) regulated under 40 CFR Part 280?
    Answer: Yes. UST systems storing E85 contain more than a de minimis concentration of regulated substances and are regulated under 40 CFR part 280.
    [November 27, 2007 Memorandum to State and Federal UST Programs (PDF) (62 pp, 1 MB)]
  • Question 33: Are UST systems containing diesel exhaust fluid (DEF) regulated under 40 CFR Part 280?
    Answer: No. UST systems storing DEF contain less than a de minimis concentration of regulated substances and are not regulated under 40 CFR Part 280.
    [September 22, 2009 Memorandum to State and Federal UST Programs (PDF) (62 pp, 1 MB)]
  • Question 34: How can UST owners and operators who wish to store ethanol blends greater than 10 percent or biodiesel blends greater than 20 percent demonstrate compliance with the federal compatibility requirement?
    Answer: EPA published June 2011 guidance in the Federal Register for UST owners and operators who wish to store biofuel blends. EPA developed this guidance to help owners and operators comply with federal regulations in 40 CFR §280.32 that require UST systems be compatible with the substances they store.
  • Question 35: What are some examples of locations that are and are not considered residential for the purposes of "residential tank" under the definition of underground storage tank in 40 CFR part 280?
    Answer: 40 CFR part 280 defines residential tanks as tanks located on properties used primarily for dwelling purposes. Based on this definition, EPA considers residential tanks to include those at homes, apartments, nursing homes and assisted living facilities. EPA would not consider tanks on properties such as prisons, hotels and camps to be residential tanks. Note that the residential tank exclusion only applies to tanks of 1,100 gallons or less in capacity that are used to store motor fuel for noncommercial purposes. [There is no additional material included for this answer.]

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