Underground Storage Tanks

How can Underground Storage Tank releases be prevented?

The U.S. Environmental Protection Agency (EPA) designed part of the technical regulations for underground storage tank (UST) systems to prevent releases from USTs. The regulations require USTs to be protected from spills, overfills, and corrosion.

Spills and overfills result mainly from bad filling practices. Also, unprotected steel tanks and piping can corrode and release product through holes caused by corrosion of the metal tank or piping.

What is spill protection?

Many releases at UST sites come from spills made during delivery. Spills usually result from human error and can be avoided if everyone involved in the fuel delivery follows industry standard practices for tank filling. USTs must also have spill buckets to contain small spills. Basically, a spill bucket is a bucket sealed around the fill pipe.

• Your USTs must have spill buckets to contain spills.
• You and your fuel deliverer must follow industry standard practices for tank filling.

Spill Buckets

Spill buckets are also called catchment basins or spill containment manholes. Basically, a spill bucket is a basin sealed around the fill pipe. To protect against spills, the spill bucket should be large enough to contain what may spill when the delivery hose is uncoupled from the fill pipe. A typical delivery hose can hold about 14 gallons of fuel. Spill buckets range in size from those capable of holding only a few gallons to those that are much larger--the larger the spill bucket, the more spill protection it provides.

You need a way to remove liquid from spill buckets. Manufacturers may equip spill buckets with either a pump or drain (PDF) (1 pg, 33K, About PDF) to remove liquid. Or you can purchase a spark free hand pump. You should try to keep your spill bucket clean and empty. Some spill buckets can collect enough water and sediment, along with spilled product, to make draining this mixture into the tank unwise. If this happens, you may pump out the spill bucket and dispose of the liquid properly. If the liquid contains fuel or chemicals, it could be considered a hazardous waste. Contact your state agency responsible for hazardous waste for information on testing and handling requirements.

Correct Filling Practices

Many releases at UST sites come from spills. Spills often occur at the fill pipe when the delivery truck's hose is disconnected. Although these spills are usually small, repeated small releases can cause big environmental problems. Human error causes most spills. These mistakes can be avoided by following industry standard practices for tank filling. For example, you must make sure there is room in the UST for the delivery so that when the delivery hose is disconnected, the hose is empty. If you and the delivery driver follow standard practices, nearly all spills can be prevented. For this reason, federal UST regulations require that you follow industry standard practices for tank filling. Additional information on Safe Fuel Handling Practices is available.

If an UST never receives more than 25 gallons at a time, the UST does not have to meet the spill protection requirements. Many small used oil tanks fall into this category.

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What is overfill protection?

If delivery drivers or UST owners make fuel delivery mistakes, a tank can be overfilled quickly and large volumes can be released at the fill pipe and through loose fittings on the top of the tank or a loose vent pipe. Overfills usually result from human error and can be avoided if everyone involved in the fuel delivery follows industry standard practices for tank filling.

• Your UST must have overfill protection. New USTs must have overfill protection devices when they are installed. The three main types of overfill protection devices are:
  • automatic shutoff devices,
  • overfill alarms, and
  • ball float valves.
• You and your fuel deliverer must follow industry standard practices for tank filling.

Overfills usually release much larger volumes than spills. When a tank is overfilled, large volumes can be released at the fill pipe and through loose fittings on the top of the tank or a loose vent pipe. The tightness of these fittings normally is not a problem if the tank is not filled beyond its capacity. You can solve overfill problems by:

• Making sure there is enough room in the tank for the delivery before the delivery is made;
• Watching the entire delivery to prevent overfilling or spilling; and
• Using overfill protection devices.

If an UST never receives more than 25 gallons at a time, the UST does not have to meet the overfill protection requirements. Many small used oil tanks fall into this category.

NOTE: If you have "pumped delivery" where fuel is delivered under pressure, you must make sure your overfill protection device works properly with pumped deliveries. Also, remember that overfill protection devices are effective only when combined with careful filling practices.

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What is corrosion protection?

Unprotected underground metal components of the UST system can corrode and release product through corrosion holes. Corrosion can begin as pitting on the metal surface (PDF) (1 pg, 82K, About PDF) . As the pitting becomes deeper, holes may develop. Even a small corrosion hole can leak hundreds of gallons of petroleum into the surrounding environment over a year. In addition to tanks and piping, metal components can include flexible connectors, swing joints, and turbines. All metal UST system components that are in contact with the ground and routinely contain product must be protected from corrosion. All USTs installed after December 22, 1988 must meet one of the following performance standards for corrosion protection:

• Tank and piping completely made of noncorrodible material, such as fiberglass-reinforced plastic (PDF) (1 pg, 74K, About PDF).
• Tank and piping made of steel having a corrosion-resistant coating and having cathodic protection (click here for more information on cathodic protection.)
• Tank made of steel clad with a thick layer of noncorrodible material (PDF) (1 pg, 74K, About PDF) (this option does not apply to piping).
• Tank and piping are installed without additional corrosion protection measures provided that a corrosion expert has determined that the site is not corrosive enough to cause it to have a release due to corrosion during its operating life and owners/operators maintain records that demonstrate compliance with this requirement.
• Tank and piping construction and corrosion protection are determined by the implementing agency to be designed to prevent the release or threatened release of any stored regulated substance in a manner that is no less protective of human health and the environment than the options listed above.

UST systems must also be designed, constructed, and installed in accordance with industry codes and standards and according to manufacturers instructions.

UST systems installed before December 1988 must be protected from corrosion. These USTs must meet one of the corrosion protection standards listed above or meet one of the upgrade options described below (or be properly closed):

• Interior lining,
• Cathodic protection*, and
• Internal lining combined with cathodic protection*.

* NOTE: Prior to adding cathodic protection, the integrity of the tank must have been ensured using one of the following methods:

• The tank is internally inspected and assessed to ensure that the tank is structurally sound and free of corrosion or holes.
• The tank has been installed for less than 10 years and uses monthly monitoring for releases.
• The tank has been installed for less than 10 years and is assessed for corrosion holes by conducting two tightness tests--the first occurs prior to adding cathodic protection and the second occurs 3 to 6 months following the first operation of cathodic protection.
• Alternative Integrity Assessment: the tank is assessed for corrosion holes by a method that is determined by the implementing agency to prevent releases in a manner that is no less protective of human health and the environment than those listed immediately above.

Upgrading bare metal piping is accomplished by adding cathodic protection. NOTE: Metal pipe sections and fittings that have released product as a result of corrosion or other damage must be replaced. Piping entirely made of (or enclosed in) noncorrodible material does not need cathodic protection.

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Why might you fail to be in compliance even if you have the required prevention equipment?

It takes more than equipment to be in compliance and to have a safe facility. You must operate and maintain this equipment properly over time or you will not benefit from having the equipment.

Failure to operate and maintain equipment can lead to new releases. A spill bucket that is allowed to crack or fill up with debris is useless as spill protection. An overfill device that is not maintained may not function and your site will suddenly have a large overfill release to clean up. Corrosion protection devices or systems that are not regularly operated and maintained properly can fail and result in an expensive cleanup at your UST site.

Be sure you review the information sources on our Web pages devoted to "Operating And Maintaining UST Systems".

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How do you properly close an UST?

To properly close an UST:

• Notify the regulatory authority at least 30 days before you close your UST.
• Determine if contamination from your UST is present in the surrounding environment. If there is contamination, you may have to take corrective action. For at least 3 years, keep a record of the actions you take to determine if contamination is present at the site (or you can mail this record to your regulatory authority).
• Either remove the UST from the ground or leave it in the ground. In both cases, the tank must be emptied and cleaned by removing all liquids, dangerous vapor levels, and accumulated sludge. These potentially very hazardous actions need to be carried out carefully by trained professionals who follow standard safety practices. If you leave the UST in the ground, have it filled with a harmless, chemically inactive solid, like sand.

NOTE: Check with your state to determine any state-specific requirements for closing UST systems.

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What are the reporting and recordkeeping requirements?

UST owners must notify state or local authorities of the existence of an UST and its leak prevention measures, or of the permanent closure of an UST. Technical regulations also set guidelines for notifying authorities of spills of more than 25 gallons.

Owners and operators must also keep records on:

• Inspection and test results for the cathodic protection system
• Repairs or upgrades
• Site assessment results after closure
• A corrosion expert's analysis of the corrosion potential of the site if corrosion protection equipment is not used

Click here for more information on reporting and recordkeeping.

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