EPA Sets Standards For Underground Storage Tanks

[EPA press release - September 13, 1988]

The U.S. Environmental Protection Agency today issued comprehensive and stringent requirements for nearly two million underground storage tanks, half of which are used to store gasoline at service stations.

EPA Administrator Lee M. Thomas said: "Today's action will ensure that underground storage tanks no longer pose a public health or environmental threat. EPA's new controls will protect local water supplies from contamination by petroleum and chemical products stored underground. The standards will ensure that tanks are operated safely during their lifetime and closed properly when removed from service. For the thousands of tanks which are now leaking, EPA is providing funds to states to identify and clean up existing contamination."

EPA's new rules require owners and operators of underground tanks containing petroleum products or certain hazardous chemicals (not hazardous wastes, which are regulated separately) to monitor tanks for leaks and, in the event of a leak, notify appropriate authorities and clean up the contamination. In October, EPA expects to issue financial standards requiring owners and operators to maintain the financial capability to clean up contamination and to compensate third parties for damages.

Underground storage tanks are those with 10 percent or more of their volume underground, including pipes. The Resource Conservation and Recovery Act (RCRA) excludes a number of tanks from federal requirements, including farm and residential tanks storing less than 1,100 gallons of motor fuel for non-commercial purposes, tanks storing heating oil for use on the premises and tanks on or above floors in underground areas, such as basements or tunnels.

EPA estimates that over 95 percent of the nation's two million underground storage tanks hold petroleum products. Of all tanks in use, an estimated 80 percent are unprotected bare-steel tanks, which are most likely to corrode and leak; the other 20 percent are protected tanks, either steel, fiberglass or some combination of both.

Based on a study of the causes of releases from underground storage tanks, EPA has determined that corrosion of bare steel accounts for almost all leaks from underground tanks and a significant portion of the leaks from connected bare-steel pipes. Improper installation and structural failure due to accidents also cause leaks. The most frequent types of leaks are caused by spills and overfills.

Some standards concerning underground storage tanks are already in effect. Under a congressional mandate effective May 7, 1985, under RCRA, all newly installed tanks now must be protected from corrosion, either through "cathodic" protection (preventing the electrical charge which leads to the corrosion of bare steel when placed in the ground) or through the use of corrosion-resistant materials, such as fiberglass. In addition, the materials must be compatible with the stored products, and the tanks must be installed using certain procedures to prevent damage.

Notification requirements also are in effect. Owners of all new tanks brought into use after May 8, 1986, must notify their states within 30 days. The notifications require information about the age, size, type, location and use of each tank. Today's rule additionally requires owners or operators to certify that the tanks are installed properly.

The new rules differ for new and existing petroleum storage tanks and new and existing chemical storage tanks.


Tank owners installing new, corrosion-protected tanks will have to certify that the tank was installed correctly to ensure the structural integrity of the system to provide leak-free performance. Owners of existing tanks (defined as those tanks in service before December 1988) will have to provide corrosion protection within 10 years.

Leak detection methods will have to be developed or installed at all tanks. Leak detection can be accomplished by a variety of methods ranging from tank testing with inventory controls (requiring daily measurements) to the installation of monitoring wells around the tank.

Existing petroleum tanks must use a leak-detection system within five years, depending on the age of the tank. For example, bare-steel tanks 25 years old or older have only until December 1989 to begin to use, at the minimum, monthly testing methods using leak-detection equipment or annual tightness testing combined with daily inventory controls to detect leaks. Tanks less than 10 years old have until 1993 to provide leak detection.

If a leak is detected from any tank, the tank must be repaired in accordance with established industry standards. Piping cannot be repaired and must be replaced, with the exception of loose fittings which can be tightened.

Within 10 years, existing tanks must be equipped with devices that prevent spills and overfills, such as overfill alarms and catch basins. Correct tank-filling practices must be immediately followed at all tanks. Stored products are often spilled during transfer operations from the delivery truck to the tank. Although these spills are often small, they can build up over time and become an environmental threat.

Leak-detection, corrosion-protection and spill- and overfill-prevention equipment must be used immediately at installation of new tanks.


Underground tanks holding one or more of 701 chemicals listed under the Superfund law are affected by today's rules. There are an estimated 54,000 chemical tanks, accounting for nearly four percent of the total tank population.

New chemical tanks are now required to have dual containment (called secondary containment), either through the installation of double-walled tanks, or concrete vaults or impenetrable liners around the tank. In addition, they must have lead-detection systems installed between the two layers of containment. Spill and overfill equipment is also required. Some variances are allowed.

At the end of 10 years, existing chemical tanks must meet the same dual-containment and leak-detection requirements as new tanks. In the meantime, the same leak-detection requirements are imposed for existing chemical tanks as for existing petroleum tanks, including the same schedule, depending on the age of the tank.

All requirements apply to new tanks at the time of installation.


EPA is requiring certain actions by tank owners to ensure that leaks and any resulting contamination are cleaned up. Petroleum tank owners and operators who discover a leak, or an above-ground spill over 25 gallons, are required to report the leak to state regulatory authorities within 24 hours. Chemical tank owners also must report all leaks; spills and overfills must be reported in accordance with certain Superfund requirements. In all cases, the owner may want to check with the local fire department to ensure there is no fire hazard. Any fire or explosive threats and free product must be removed and, under certain circumstances, a more thorough investigation must be conducted to confirm the leak and whether there is any damage to nearby soil and groundwater. All additional information on the leak or spill must be reported to the appropriate regulatory agency within 20 days and again at 45 days from the spill. At 45 days, the owner must report whether or not groundwater has been contaminated and, if necessary, submit a plan for recovering any free product. More extensive examination of soil and groundwater contamination may be required, as well as a corrective-action plan for cleaning up groundwater.


Any tank temporarily not used must maintain leak-detection (unless the tank is emptied) and corrosion-protection systems. All temporarily closed bare-steel tanks must be permanently closed after 12 months, unless the temporary closure period is extended by the implementing agency. Regulatory authorities must be notified 30 days prior to permanent closure of the tank. At final closure, the tank must be emptied and cleaned. Also, the owner must determine if there is any environmental damage at the site and either remove the tank or fill it with inert materials.

Certain recordkeeping is required, including the maintenance of leak-detection reports and information on corrosion-protection systems, repairs and closure.


EPA is providing all states with federal funds to identify and address leaking tanks and to ensure cleanup. In most cases, the cleanup will be accomplished by the responsible private party. The funds are available from the Leaking Underground Storage Tank Trust Fund, set up by Congress in October 1986. The fund will collect $500 million over five years through a tax of one-tenth of a cent on gasoline.


EPA estimates the incremental cost to industry of the technical standards to be $2.5 billion a year, with an incremental benefit of $2.8 billion. The net benefit is estimated to be $0.3 billion a year.

A leak detection system could cost a typical gas station with three 5,000 gallon tanks between $3,000 to $8,000. The cost of retrofitting cathodic protection to existing tanks could range anywhere from $10,000 to $48,000.

Costs of installing three new 10,000 gallon tanks can range from $76,000 to $100,000, depending on the level of leak detection. Secondary containment can cost up to one-third more than single-wall tanks. However, the increased cost should be weighed against the significant cost of cleanup from leaks into the environment, which could approach $225,000 or more in cases of groundwater contamination.


Violators of the regulations can be fined up to $10,000 per violation per day for each tank. Fines up to $25,000 can be assessed for violations of enforcement orders for each day of continued non-compliance.


The final rules are effective 90 days after publication in the Federal Register, which is expected in mid-September.