An underground storage tank (UST) is any tank and connected underground piping that has at least 10 percent of its combined volume underground. As of 1994, EPA estimated that there were over 1.2 million USTs subject to regulation at over 500,000 sites in the United States. These USTs, most of which contain petroleum, are used for both commercial purposes, such as holding gasoline at service stations, and noncommercial purposes, such as holding heating oil for residential homes and offices.

Properly managed, USTs will not threaten human health or the environment. However, due to improper management, tens of thousands of these USTs are currently leaking, and many more are expected to leak in the future. Leaking USTs can cause fires or explosions that can threaten human safety and can contaminate nearby groundwater. Therefore, federal and state regulations have been created to avoid these threats by ensuring the integrity of all new and existing USTs.

Do These Regulations Apply to Your Community?

These regulations apply if you have one or more storage tanks that have at least 10 percent of their volume underground (including underground piping connected to the tank), and that store either petroleum or certain hazardous substances.

Certain tanks, however, are exempt from the UST regulation. These include tanks storing heating oil to be used on the premises, tanks on or above the floor of underground areas, septic tanks and systems for collecting stormwater and wastewater, tanks holding 110 gallons or less, and emergency spill and overfill tanks. You should contact your regulatory authority (generally your state UST office) if you have questions about whether your tanks are regulated.

Actions Your Community Should Be Taking

All regulated USTs must meet certain construction and operating requirements imposed by EPA and states with approved UST programs. Basically, these requirements ensure that all tanks and piping are properly designed and constructed so as to prevent their contents from escaping.

New tanks, those installed after December 22, 1988, must be properly designed and have all necessary protective equipment in place at the time of installation. Existing tanks must also meet all EPA requirements; however, in order to provide owners and operators enough time to retrofit old tanks, EPA has instituted a "phased-in" approach for these requirements (see Timetable information on page 68). By 1998, all new and existing USTs and their piping must meet EPA requirements for leak detection, corrosion protection, and spill overfill protection, as described below.

Leak Detection

Leaking tanks can pose a serious threat to the environment of the surrounding community. To ensure the integrity of your tanks, you must monitor them at least once a month using a method, or combination of methods, capable of detecting releases from any portion of the tank/piping system that normally holds fluid. Approved monthly monitoring methods include automatic tank gauging, monitoring for soil vapors, interstitial monitoring, and monitoring for liquids on groundwater. Facilities may opt to use monthly inventory control plus tank tightness testing in lieu of any of leak detection methods mentioned above, but this option can only be used for a limited period of time.

Corrosion Protection

Initially, most USTs were made of unprotected steel. Over time, the steel would corrode, allowing tank contents to seep into the environment. In order to prevent these releases, EPA has established corrosion protection requirements for all new and existing tanks and piping.

To meet these requirements, new tanks must be made of one of the following three materials:

1. a noncorrodible material such as fiberglass;
2. steel clad with a thick layer of noncorrodible material; or
3. steel that has a corrosion-resistant coating and has cathodic protection.

Since it is generally not practicable to add coatings to existing tanks, owners/operators must ensure that these tanks are protected from corrosion by:

1. adding cathodic protection;
2. adding an interior lining to the tank; or
3. adding a combination of cathodic protection plus an interior lining. Steel piping must either have cathodic protection or be enclosed in (or entirely made of) a noncorrodible material.

Spill/Overfill Protection

Another common way in which tank contents are released into the environment is through accidents that occur during product transfers, either spills or tank overfills. Tank owners and operators must already have tank filling procedures in place that are designed to prevent these types of releases.

As an extra precaution, EPA has mandated that all tanks have physical mechanisms in place that are designed to prevent tank overflows and catch any product that may otherwise be released. The required physical mechanisms are: catchment basins plus automatic shutoff devices, automatic alarms, or ball float valves.

You should be aware, however, that the spill/overfill requirements apply only to transfers of over 25 gallons at a time -- therefore, if your own or operate a tank that is filled by transfers of no more than 25 gallons at a time, you are exempt from the spill/overfill requirements.

Special Requirements For Hazardous Substance USTs

Several hundred substances are designated as "hazardous" under federal regulations (for information on the substances designated as "hazardous," please contact the RCRA/CERCLA Hotline.). If your UST stores any of these hazardous substances, it must meet certain requirements not imposed on petroleum USTs. Specifically, hazardous substance USTs must have a secondary containment system capable of retaining any releases from the tank. In addition, the tank must have a leak detection system capable of indicating the presence of a leak in the space between the original tank wall and the wall of the secondary containment tank. This type of leak detection is commonly referred to as "interstitial monitoring."

Leaks and Spills From Hazardous Substance And Petroleum USTs

If there has been a confirmed leak or spill from your UST, you must take immediate action to stop and contain the leak or spill. You must also identify and mitigate potential immediate hazards such as explosions, vapors, and fire hazards. You are further required to notify the regulatory authority within 24 hours of discovering a leak or spill (except in the case of petroleum spills and overfills of less than 25 gallons that can be and are cleaned up within 24 hours). Once the immediate threat from the leak/spill has passed, you must investigate to determine if any damage was done to the environment, and report your findings within 45 days. Based on the information you provide in your report, the regulatory authority will decide if you must take further action, such as developing and submitting Corrective Action Plan.

Closing USTs

Your UST can be closed either permanently or temporarily. Contact your state UST program for more details on how to properly close your tank.

Reporting And Recordkeeping Requirements

Your state must have a record of every regulated UST you own or operate. When you install a new UST, you must fill out and submit a notification form available from your state (you should have already used this form to identify all of your existing USTs; if you have not done this yet, be sure to do so now). You must also notify the regulatory authority 30 days before you permanently close any UST. All releases and suspected releases from your USTs must be reported. Confirmed releases must be followed up with a report that details the actions you have taken or plan to take to correct any environmental damage caused by your UST.

Financial Responsibility Requirements

Since undetected leaks and accidental spills can lead to very expensive cleanup and liability costs, federal and state regulations now require that UST owners and/or operators demonstrate their financial ability to take corrective action and compensate third parties for bodily injury and property damage. There are separate compliance requirements and schedules for different sizes and classifications of UST owners and operators. Most small communities will have to show responsibility for $500,000 per occurrence, and $1 million in the aggregate.

The federal regulations list a number of ways to establish your ability to pay the required minimum amount for cleanup costs and liability claims. There are four compliance mechanisms that are exclusively available to local governments for demonstrating financial capability:

1. a bond rating test;
2. a financial test;
3. a dedicated fund; and
4. an intergovernmental guarantee.

You can also use private insurance, letter of credit, surety bond, or state assurance fund. Be sure to check with your state to see if you are already covered under a state UST fund. Local governments were required to prove their compliance with the financial responsibility requirements by February 18, 1994.

EPA's New Strategic Framework for UST Regulation

EPA has traditionally taken a lead role in the regulation of USTs. Under a new "strategic framework for UST Regulation," however, EPA has indicated that it intends to relinquish its role as supervisor of the UST program by the turn of the century. The new strategic framework has four basic components:

1. privatization of many UST compliance mechanisms, relying on the insurance, banking, and real estate industries to adopt many of the existing standards;
2. engaging the public in UST compliance by boosting their understanding and awareness of UST issues;
3. persuading companies to stop using USTs entirely, whenever possible; and
4. significantly diminishing EPA's role in UST regulation and enforcement.

EPA expects to formally unveil the new strategic plan shortly. Timetable

Leak detection equipment must be installed according to the following schedule:

• New tanks and piping: At tank installation
• Existing tanks and piping: No later than December 22, 1993 (1990 for pressurized piping)

Corrosion protection equipment must be installed according to the following schedule:

• New tanks and piping: At tank installation
• Existing tanks and piping: No later than December 22, 1998

Spill/overfill protection equipment must be installed according to the following schedule:

• New tanks and piping: At tank installation
• Existing tanks: No later than December 22, 1998

Local governments were required to prove their compliance with the financial responsibility requirements by February 18, 1994.

Additional Information

The UST regulations are published in Title 40 of the Code of Federal Regulations, Part 280

Check with your state UST program for additional information and state-specific requirements.

EPA has published several guidance documents that are available to help you comply with the federal UST regulations, including "Musts for USTs: A Summary of the Regulations for Underground Storage Tank Systems," and the "UST Program Fact Sheets." Call the RCRA Hotline for information on titles available and how you can order them.
Hours: 8:30 a.m. to 7:30 p.m. EST, Monday-Friday.
Telephone: 1/800/424-9346
TDD (hearing impaired): 1/800/553-7672
Washington metro area: 1/703/920-9810
TDD: 1/703/486-3323

"Getting Out From Under, Underground Storage Tank Alternatives for Small Towns" is available from the National Association of Towns and Townships (NATAT), at 202/737-5200.

(See Resource Section for UST contacts)