Underground Storage Tanks

What is an UST?

An underground storage tank system (UST) 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.

When the UST program began, there were approximately 2.1 million regulated tanks in the U.S. Today there are far fewer since many substandard UST systems have been closed. For the most current statistics available, see the UST And LUST Program Performance Measures. 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). EPA estimates that less than 10,000 tanks hold hazardous substances covered by the UST regulations.

Why be concerned about USTs?

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.

How have Congress and EPA responded to concerns about USTs?

In 1984, Congress responded to the increasing threat to groundwater posed by leaking USTs by adding Subtitle I to the Resource Conservation and Recovery Act (RCRA). Subtitle I required EPA to develop a comprehensive regulatory program for USTs storing petroleum or certain hazardous substances.

Congress directed EPA to publish regulations that would require owners and operators of new tanks and tanks already in the ground to prevent, detect, and clean up releases. At the same time, Congress banned the installation of unprotected steel tanks and piping beginning in 1985.

In 1986, Congress amended Subtitle I of RCRA and created the Leaking Underground Storage Tank Trust Fund, which is to be used for two purposes:

1. To oversee cleanups by responsible parties.
2. To pay for cleanups at sites where the owner or operator is unknown, unwilling, or unable to respond, or which require emergency action.

The 1986 amendments also established financial responsibility requirements. Congress directed EPA to publish regulations that would require UST owners and operators to demonstrate they are financially capable of cleaning up releases and compensating third parties for resulting damages.

The Energy Policy Act of 2005 amended Subtitle I of the Solid Waste Disposal Act. The UST provisions of the Energy Policy Act focus on preventing releases. It expands the use of the LUST Trust Fund and includes provisions regarding inspections, operator training, delivery prohibition, secondary containment and financial responsibility, and cleanup of releases that contain oxygenated fuel additives.

Do all tanks have to meet federal EPA regulations?

The following USTs 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. 

Some state/local regulatory authorities, however, may include these tank types--be sure you check with these authorities.

What are the federal requirements for USTs?

In 1988, EPA issued UST regulations divided into three sections: technical requirements, financial responsibility requirements, and state program approval objectives (as described below).

• Technical requirements for USTs

  EPA's technical regulations for USTs are designed to reduce the chance of releases from USTs, detect leaks and spills when they do occur, and secure a prompt cleanup. UST owners and operators are responsible for reporting and cleaning up any releases. (See "Preventing Releases", "Detecting Releases", and "Cleaning Up Releases.") OUST produced a 36-page booklet called "Musts For USTs" that clearly presents the UST regulatory requirements.

• Financial responsibility regulations for USTs

  The financial responsibility regulations designed to ensure that, in the event of a leak or spill, an owner or operator will have the resources to pay for costs associated with cleaning up releases and compensating third parties. (See "Financial Responsibility.") OUST produced a 16-page booklet called "Dollars And Sense" that clearly presents these regulatory requirements.

• State program approval objectives

  EPA recognizes that, because of the large size and great diversity of the regulated community, state and local governments are in the best position to oversee USTs. Subtitle I of RCRA allows state UST programs approved by EPA to operate in lieu of the federal program, and EPA's state program approval regulations set standards for state programs to meet. (See "State Program Approval (SPA)" for more information.) States may have more stringent regulations than the federal requirements. If you are interested in requirements for USTs, contact your state UST program for information on state requirements.

Need more information?

See basic information EPA developed about the underground storage tank program.

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