California ICC UST Inspector Practice Exam

An interstitial monitor is primarily used to detect what?

1. Loss of fuel due to theft.

2. Vapor concentrations above the fuel.

3. Leaks between primary and secondary containment.

4. Water contamination in the tank.

The correct answer is: Leaks between primary and secondary containment.

An interstitial monitor is specifically designed to detect leaks that occur between the primary and secondary containment systems of underground storage tanks (USTs). In the context of UST systems, the primary containment is the tank itself which holds the fuel, while the secondary containment is typically the surrounding structure that protects against leaks. If a leak occurs in the primary containment, the interstitial monitor will sense the presence of fuel in the space between the two containment layers. This capability is crucial for environmental safety and regulatory compliance, as it allows for early detection of leaks to prevent soil and groundwater contamination. Other options, while relevant to UST monitoring, do not directly relate to the primary function of the interstitial monitor. For instance, the option regarding theft does not pertain to the interstitial monitoring function, as that is usually managed by inventory control systems rather than leak detection systems. The detection of vapor concentrations is typically handled by vapor monitors, and while water contamination is an issue, it falls outside the primary purpose of an interstitial monitor in monitoring for leaks specifically.