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Underground storage tanks (known as USTs) are big containers placed underground to hold large quantities of liquids or gases. USTs also have piping and a pump station to move the tank contents to where they are used. About 95% of all USTs store petroleum products like gasoline or oil. Tanks may hold industrial chemicals, pesticides, or even food products.
IDEM closely regulates under-ground storage tanks, because leaking tanks can easily contaminate ground water. A spill of only three gallons of gasoline can spoil drinking water for a small town. It is important to protect ground water, because about 60% of Hoosiers get drinking water from ground water supplies.
Previously, most tanks were made out of unprotected steel, and would rust and leak after about 10 years (less time under certain conditions). Many tanks and connected piping exposed to ground water have rusted through, allowing the contents to seep out. Since 1998, tank owners and operators are required to use tanks lined with materials that do not rust to help prevent leaks.
For safety, tanks containing petroleum products and other substances are placed underground to lessen the risk of explosion. Unfortunately, this placement makes it difficult to detect leaks that can enter ground water supplies. Here are the most common places to find USTs.
Since 1989, approximately 4300 sites have been cleaned up where USTs leaked. The Leaking Underground Storage Tank Section is working to address about 3500 more sites contaminated by leaking tanks. With so many spills to address, sites are prioritized to ensure that the spills with the greatest chance of impacting people are cleaned up first. Spills are placed into one of three categories: high, medium, or low priority.
The health effects from leaking USTs vary depending on the chemicals in the tank, the duration and size of the leak, specifics about the surrounding environment, duration of human contact to the chemicals, whether the contact was made to the skin, breathed in, or swallowed, and other factors.
Petroleum products such as gasoline, kerosene, diesel, and heating oil are made of many chemicals that have the potential to cause health problems. The health effects can range from skin and respiratory irritation, to dizziness and headaches, to cancer.
For more information about health effects: