A typical gasoline station has a storage capacity of 30,000 to 40,000 gallons in underground tanks. In the past, these tanks were sometimes subject to spills from overfilling and to leaks caused by corrosion. Today, station owners have taken several important steps to reduce these risks.
When in contact with moisture in the air or ground, steel slowly rusts, causing corrosion of metal storage tanks and pipelines. When the moisture combines with the carbon dioxide in the air, a weak carbonic acid is formed, which dissolves the steel tanks or pipelines, appearing as rust. The application of a small positive electrical charge to the tank helps prevent this corrosion process.
New fiberglass tanks and steel tanks coated with fiberglass or other durable casings help prevent corrosion caused by underground moisture. The same high-tech coatings and linings also protect the nation's pipelines and above-ground storage tanks.
All tanks are equipped with large "buckets" located around the fill pipe, which catch any motor fuel that may spill when the delivery hose is disconnected from the fill pipe.
Sensors can detect even small leaks in underground storage tanks and piping. An automatic tank gauging system monitors the volume of petroleum product within a storage tank versus the amount of product dispensed to consumers.