What are the signs of an underground leak in a UST system?

When assessing the signs of an underground leak in a UST system, the correct identification includes unexplained product loss, product odors, or visible stains on the ground. These indicators are primary symptoms of leakage. Unexplained product loss refers to a noticeable decrease in the amount of stored product without a clear cause, which could suggest a leak. Product odors can be a strong indicator as they signify the presence of volatile organic compounds escaping from the tank. Additionally, visible stains on the ground, especially near the tank or piping, can reveal the location of a leak and the type of product that might be escaping, making it essential to address the situation promptly to prevent environmental contamination and regulatory violations.

The other choices, while they may reflect issues associated with UST operations, do not directly indicate leaks. Increased customer complaints could stem from various issues unrelated to leaks, such as service quality or product quality concerns. Unexpected maintenance bills might occur due to general wear and tear or other system inefficiencies rather than necessarily indicating leaks. Improved environmental conditions is not a sign of a leak; in fact, it would be an unlikely outcome of such a failure, making this option incorrect in the context of leak signs. Therefore, option A provides the most relevant and direct signs of an