What happens to a UST system if it is closed but not removed?

When a UST system is closed but not removed, it is considered abandoned. This classification arises from the fact that the tank is no longer being used but remains in place, creating potential environmental concerns. Abandonment implies that the tank is left without sufficient oversight or management, which could lead to contamination risks if any remaining product leaks or if the tank itself deteriorates over time.

In contrast, while still considered abandoned, the tank might still pose a regulatory concern, as unmonitored tanks can lead to significant environmental liabilities. Therefore, even if a UST is not actively monitored or inspected like an operational tank, regulators typically require documentation and potential future actions to mitigate risks associated with abandoned USTs.