USTs

Scope

An underground storage tank (UST) system is a tank, and any underground piping connected to the tank, that has at least 10 percent of its combined volume underground. The federal UST regulations apply only to underground tanks and piping storing either petroleum or certain hazardous substances.

EPA estimates that there are over one-half million federally regulated USTs buried at thousands of sites nationwide. Nearly all USTs at these sites contain petroleum. These sites include marketers who sell gasoline to the public (such as service stations and convenience stores), and nonmarketers who use tanks solely for their own needs (such as fleet service operators and local governments).

Until the mid-1980s, most USTs were made of bare steel, which is likely to corrode over time and allow UST contents to leak into the environment. Faulty installation or inadequate operating and maintenance procedures also can cause USTs to release their contents into the environment. The greatest potential hazard from a leaking UST is that the petroleum or other hazardous substance can seep into the soil and contaminate groundwater, the source of drinking water for nearly half of all Americans. A leaking UST can present other health and environmental risks, including the potential for fire and explosion.

Exemptions from the UST regulation

The following USTs are excluded from regulation and, therefore, do not need to meet federal requirements for USTs:

• Farm and residential tanks of 1,100 gallons or less capacity holding motor fuel used for noncommercial purposes;
• Tanks storing heating oil used on the premises where it is stored;
• Tanks on or above the floor of underground areas, such as basements or tunnels;
• Septic tanks and systems for collecting storm water and wastewater;
• Flow-through process tanks;
• Tanks of 110 gallons or less capacity; and
• Emergency spill and overfill tanks.

Regulatory citations

• 40 CFR 280 — Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST)
• 40 CFR 281 — Approval of State Underground Storage Tank Programs
• 40 CFR 282 — Approved Underground Storage Tank Programs

Key definitions

• Ancillary equipment: Any devices including, but not limited to, such devices as piping, fittings, flanges, valves, and pumps used to distribute, meter, or control the flow of regulated substances to and from an UST.
• Cathodic protection: A technique to prevent corrosion of a metal surface by making that surface the cathode of an electrochemical cell. For example, a tank system can be cathodically protected through the application of either galvanic anodes or impressed current.
• Class A operator: The individual who has primary responsibility to operate and maintain the UST system in accordance with applicable requirements established by the implementing agency. The Class A operator typically manages resources and personnel, such as establishing work assignments, to achieve and maintain compliance with regulatory requirements.
• Class B operator: The individual who has day-to-day responsibility for implementing applicable regulatory requirements established by the implementing agency. The Class B operator typically implements in-field aspects of operation, maintenance, and associated recordkeeping for the UST system.
• Class C operator: The individual responsible for initially addressing emergencies presented by a spill or release from an UST system. The Class C operator typically controls or monitors the dispensing or sale of regulated substances.
• Connected piping: All underground piping including valves, elbows, joints, flanges, and flexible connectors attached to a tank system through which regulated substances flow. For the purpose of determining how much piping is connected to any individual UST system, the piping that joins two UST systems should be allocated equally between them.
• Containment sump: A liquid-tight container that protects the environment by containing leaks and spills of regulated substances from piping, dispensers, pumps and related components in the containment area. Containment sumps may be single walled or secondarily contained and located at the top of tank (tank top or submersible turbine pump sump), underneath the dispenser (under-dispenser containment sump), or at other points in the piping run (transition or intermediate sump).
• Excavation zone: The volume containing the tank system and backfill material bounded by the ground surface, walls, and floor of the pit and trenches into which the UST system is placed at the time of installation.
• Existing tank system: A tank system used to contain an accumulation of regulated substances or for which installation has commenced on or before December 22, 1988. Installation is considered to have commenced if: (1) The owner or operator has obtained all federal, state, and local approvals or permits necessary to begin physical construction of the site or installation of the tank system; and if, (2)(i) Either a continuous on-site physical construction or installation program has begun; or, (ii) The owner or operator has entered into contractual obligations—which cannot be canceled or modified without substantial loss—for physical construction at the site or installation of the tank system to be completed within a reasonable time.
• Free product: Refers to a regulated substance that is present as a nonaqueous phase liquid (e.g., liquid not dissolved in water).
• Gathering lines: Any pipeline, equipment, facility, or building used in the transportation of oil or gas during oil or gas production or gathering operations.
• Hazardous substance UST system: An underground storage tank system that contains a hazardous substance defined in section 101(14) of the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (but not including any substance regulated as a hazardous waste under subtitle C) or any mixture of such substances and petroleum, and which is not a petroleum UST system.
• Hydraulic lift tank: A tank holding hydraulic fluid for a closed-loop mechanical system that uses compressed air or hydraulic fluid to operate lifts, elevators, and other similar devices.
• Liquid trap: Sumps, well cellars, and other traps used in association with oil and gas production, gathering, and extraction operations (including gas production plants), for the purpose of collecting oil, water, and other liquids. These liquid traps may temporarily collect liquids for subsequent disposition or reinjection into a production or pipeline stream, or may collect and separate liquids from a gas stream.
• Overfill release: A release that occurs when a tank is filled beyond its capacity, resulting in a discharge of the regulated substance to the environment.
• Owner:
  (1) In the case of an UST system in use on November 8, 1984, or brought into use after that date, any person who owns an UST system used for storage, use, or dispensing of regulated substances; and (2) In the case of any UST system in use before November 8, 1984, but no longer in use on that date, any person who owned such UST immediately before the discontinuation of its use.
• Regulated substance:
  (1) Any substance defined in section 101(14) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) of 1980 (but not including any substance regulated as a hazardous waste under subtitle C); and (2) Petroleum, including crude oil or any fraction thereof that is liquid at standard conditions of temperature and pressure (60 degrees Fahrenheit and 14.7 pounds per square inch absolute). The term regulated substance includes but is not limited to petroleum and petroleum-based substances comprised of a complex blend of hydrocarbons, such as motor fuels, jet fuels, distillate fuel oils, residual fuel oils, lubricants, petroleum solvents, and used oils.
• Release: Any spilling, leaking, emitting, discharging, escaping, leaching or disposing from an UST into groundwater, surface water or subsurface soils.
• Release detection: Determining whether a release of a regulated substance has occurred from the UST system into the environment or a leak has occurred into the interstitial space between the UST system and its secondary barrier or secondary containment around it.
• Replaced:
  (1) For a tank—to remove a tank and install another tank. (2) For piping — to remove 50 percent or more of piping and install other piping, excluding connectors, connected to a single tank. For tanks with multiple piping runs, this definition applies independently to each piping run.
• Secondary containment: A release prevention and release detection system for a tank or piping. This system has an inner and outer barrier with an interstitial space that is monitored for leaks. This term includes containment sumps when used for interstitial monitoring of piping.
• Septic tank: A water-tight covered receptacle designed to receive or process, through liquid separation or biological digestion, the sewage discharged from a building sewer. The effluent from such receptacle is distributed for disposal through the soil and settled solids and scum from the tank are pumped out periodically and hauled to a treatment facility.
• Storm water or wastewater collection system: Piping, pumps, conduits, and any other equipment necessary to collect and transport the flow of surface water run-off resulting from precipitation, or domestic, commercial, or industrial wastewater to and from retention areas or any areas where treatment is designated to occur. The collection of storm water and wastewater does not include treatment except where incidental to conveyance.
• Surface impoundment: A natural topographic depression, man-made excavation, or diked area formed primarily of earthen materials (although it may be lined with man-made materials) that is not an injection well.
• Tank: A stationary device designed to contain an accumulation of regulated substances and constructed of non-earthen materials (e.g.,concrete, steel, plastic) that provide structural support.
• Under-dispenser containment or UDC: Containment underneath a dispenser system designed to prevent leaks from the dispenser and piping within or above the UDC from reaching soil or groundwater.
• Underground storage tank or UST: Any one or combination of tanks (including underground pipes connected thereto) that is used to contain an accumulation of regulated substances, and the volume of which (including the volume of underground pipes connected thereto) is 10 percent or more beneath the surface of the ground.
• Upgrade: The addition or retrofit of some systems such as cathodic protection, lining, or spill and overfill controls to improve the ability of an underground storage tank system to prevent the release of product.
• Wastewater treatment tank: A tank that is designed to receive and treat an influent wastewater through physical, chemical, or biological methods.

Summary of requirements

• Properly install underground storage tanks.
• Ensure tanks have required secondary containment and corrosion protection.
• Follow correct filling practices.
• Report new UST systems, suspected releases, and UST system closures.
• Keep accurate records of operation and maintenance.
• Ensure Class A and B operators have correct training and pass required exams.
• Ensure Class C operators have correct training.