Underground Storage Tanks

The definition given by the EPA of an UST is any tank and associated underground piping that has at least 10% of its volume underground. USTs cause problems for four reasons. Most USTs in the ground are constructed of bare steel. This offers no corrosion protection, as bare steel buried in the ground corrodes rapidly. Installation mistakes are another cause of tank leakage. Inadequate backfill and poor pipe fittings are examples of installation mistakes that result in leakage. Spills and overflows also contribute to UST pollution. When too much fuel is delivered to the UST, it overfills and enters the ground. When the operator disconnects the hose incorrectly, a spill often results. The final cause of UST problems is piping failure. Underground piping is smaller and less durable than the UST. This piping is located near the ground surface and suffers greatly from the effects of installation mistakes, surface loads, and underground movement.

Goals of the Federal UST Regulations

-- To prevent leaks and spills

-- To find leaks and spills

-- To correct the problems created by these leaks and spills

-- To ensure that each state's UST regulations are stricter that the federal regulations

Subtitle I of the Hazardous and Solid Waste Amendments (HWSA) to the Resources Conservation and Recovery Act (RCRA) mandate requirements for Underground Storage Tanks(USTs). Included in these amendments are requirements for tank notification, interim prohibition, new tank standards, reporting and record keeping for existing tanks, corrective action, financial responsibility, compliance monitoring and enforcement, and approval of State programs. The laws also require the Environmental Protection Agency to establish a comprehensive program for the regulation of UST systems “as may be necessary for the protection of human health and the environment.” Copy of Text of Subtitle I..

Underground Storage Tank (UST) regulations are outlined in Part 280 of Title 40 of the Code of Federal Regulations(CFR). Subpart A discusses program scope and Interim Prohibition, which defines UST systems that fall under regulation. Subpart B outlines the acceptable design, construction, installation, and notification procedure. Subpart C includes general operating requirements. Subpart D and E regulate monitoring systems. Subpart F defines common procedure for release response and corrective action for UST systems holding petroleum or other hazardous substances. Subpart G identifies recommended practices for UST closure and existing out-of-service systems. To read a copy of 40 CFR 280 please click here. For more information please visit the EPA Office of Underground Storage Tanks' homepage.

Potential Threat to Soil and Ground Water

Fifty percent of the United States' population uses groundwater as a source of drinking water. Underground storage tanks are of concern to our water supply for two reasons. One, they usually contain a toxic or potentially dangerous chemical, and two, they can leak undetected for a long duration without the owner/operator being aware of their condition. For these two reasons, the regulations associated with USTs have increased (See "Regulations.") Not only are the tanks of concern but a release can originate from any part of the underground system associated with the tank. Since the buried apparatus includes pumps lines and the fill pipes contain joints in the connections, there is also the chance of leak from this part of the underground system. As of August 1996, there were 314,720 reported releases from USTs. Additionally, about 30,000 new leaks are reported each year. This is of concern to government and the general public as both our groundwater reserves and the soil in direct contact with the contaminant are subsequently contaminated. Potentially, toxic or explosive vapors can travel in the soil subsurface endangering lives and property. Gasoline is one of the most prevalent contaminants in the above instances especially in groundwater. Pollutants that are not detected relatively soon after leak development could cause extensive ground water contamination.

1998 Regulation Deadline

The Office of Technology Assessment has estimated that the number of underground storage tanks, both abandoned and in use, is about 2.5 million. In order to help control some of the previously mentioned probems, existing USTs must be protected from spills, overfills, and corrosion by December 22, 1998. Of all USTs, approximately 45% comply with the 1998 Regulation Deadline in process right now. The other 55% have either not met the new requirement or are in the process of repairing, replacing, or closing their USTs.

Tank Closure

One effective way to eliminate the threat of groundwater contamination from USTs is tank closure. Tanks can be closed temporarily or permanently. Temporary closure can last for up to 12 months if certain requirements are met as stated by EPA’s Office of Underground Storage Tanks. First, they must be continuously monitored for leaks. If a release is found, the appropriate regulatory agency must be notified and action must be taken for clean up. Second, if the UST remains temporarily closed for more than 3 months, vent lines must be left open but all other lines, pumps, and so on must be capped and secured. After those 12 months, the tank can be permanently closed, an extension may be provided, or the tank may remain temporarily closed if it meets the requirements for new or upgraded USTs.

For permanent closure of a UST, the regulatory agency must be notified at least 30 days prior to closure. If contamination from the UST is present in the surrounding environment, corrective action must be taken. A record must be maintained for at least 3 years of the action taken regarding contamination. The UST can either be removed from the ground or left in the ground. The tank must be emptied in both cases and cleaned by removing all liquids, dangerous vapor levels, and accumulated sludge. If the UST is left in the ground, it should be filled with a harmless, inactive solid such as sand. Regardless of which procedure is used, standard safety practices must be used. Removing the tank could be a hazardous procedure and should be executed by a trained professional.

UST removal from ground

Photograph obtained from VA Tech Env. Eng. Home Page

Underground Storage Tanks (USTs)

By Eric Emenheiser, Michelle DeCaire, Mike Boike, Mike Grafton, and Eric Whitney

Spring 1997

What is a UST?

Federal Regulations Concerning USTs

Potential Threat to Soil and Ground Water

1998 Regulation Deadline

Tank Closure

Goals of the Federal UST Regulations

Potential Threat to Soil and Ground Water

1998 Regulation Deadline

Tank Closure

References