Preventing UST Releases
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 owners and operators to properly install UST systems and protect their USTs from spills, overfills, and corrosion and require correct filling practices to be followed. In addition, owners and operators must report the existence of new UST systems, suspected releases, UST system closures, and keep records of operation and maintenance.
What is spill protection?
Spill protection is containment around the fill pipe that catches small drips or spills that occur when the delivery hose is disconnected from the fill pipe. This containment is typically called a spill bucket (PDF) (1 pg, 33K, About PDF). It may also be referred to as a catchment basin, or spill containment manhole. 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 can provide.
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.
Note: 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.
What is overfill protection?
Overfill protection are devices that either shut off product flow, restrict product flow or alert the delivery operator with an alarm when the tank is close to being full. These devices are installed inside the tank and activate if the product in the UST reaches a certain level in the tank. Typically, your UST must have overfill protection. The three types of overfill protection devices are:
Note: 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.
What are correct filling practices?
Many releases at UST sites come from spills and overfills that occur during delivery. Although these spills are usually small, repeated small releases can cause big environmental problems. To help prevent spills and overfills during tank filling, the UST regulations require owners and operators to meet the following correct filling practices:
- the volume available in the tank is greater than the volume of regulated substance to be transferred to the tank before the transfer is made; and
- the transfer operation is monitored continuously.
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 result in significant releases over time. 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. The two common methods used for protecting metal components from corrosion are cathodic protection and isolating the metal component from the corrosive environment.
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.
- 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 manufacturer’s instructions.
UST systems installed before December 22, 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):
* 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.