For new underground tanks, a high liquid level protection device can be installed. This allows for careful monitoring of fuel levels. For existing underground tanks, regular monitoring as mentioned above is your only option for groundwater protection. However, fiberglass tanks may not be suited for alcohol-blended fuels. A common type of cathodic protection uses sacrificial anodes attached to the underground tank.
Sacrificial anodes are pieces of metal more electrically active than the bare steel tank.
Because the anodes are more active, they are attacked and corroded instead of the metal in the tank. Underground storage tanks used for aboveground storage can easily fail, because the structural support provided by the soil does not exist aboveground. Tanks that are to be out of service for extended periods of time should be removed if feasible. This is also a good way to determine if a tank has been leaking. The tank should be emptied before removal.