In the prior art, underground storage tanks are frequently used for the storage of various liquids, such as gasoline, fuel oil, diesel oil, toxic fluids, or various chemicals. These underground storage tanks are used in automobile service stations, truck and bus depots, for various industrial and commercial facilities, and occasionally, for homes and consumer purposes. The storage tanks are generally cylindrical, consist of a welded construction of sheet steel of sufficient gage, and have a capacity ranging from 550 to 50,000 gallons.
In the event of a crack or fault developing in the tank, the gasoline or other fluid will leak into the ground. Not only is this wasteful, but more importantly, it pollutes the environment. Many of the existing tanks are fairly old, for example twenty-five years old, and the leakage may occur over a relatively long period of time prior to its detection. The tank must then be dug up and removed, either repaired or replaced, and clean-up operations commenced on the surrounding environment. In gasoline stations, especially, the constant vehicular traffic over the buried tanks may cause the tanks to shift and thus become more susceptible to developing cracks and leaks.
The problem may become especially pronounced in suburban or rural areas where the surrounding homeowners depend upon underground wells for an available supply of fresh water. In the event of gasoline leakage, these fresh water supplies may become spoiled or contaminated.