Which of the following statements regarding UST systems is true?

The correct statement regarding UST (Underground Storage Tank) systems is that they must not leak. This is a crucial requirement because leaks can lead to significant environmental hazards, including soil and groundwater contamination. The integrity of UST systems is essential for protecting public health and the environment, which is why regulations and guidelines surrounding UST operations emphasize leak prevention and detection.

USTs are typically made from a variety of materials, including steel and fiberglass, and not exclusively from copper, which means that the first statement is not accurate. Regular monitoring is mandated by regulations in many jurisdictions to ensure the tanks remain in compliance, so the assertion that they must be monitored weekly is also not always true, as it can vary based on local regulations and the specific type of monitoring system in place. As for leaving USTs unmonitored, that poses substantial risks and is not compliant with best practices. Thus, the requirement for USTs to be leak-proof is fundamental to their safe operation and management.