California ICC UST Inspector Practice Exam

What does an interstitial monitor detect?

1. Loss of fuel due to theft.

2. Vapors in the air space above the fuel.

3. Problems with the cathodic protection system.

4. Leaks between the primary and secondary containment.

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

An interstitial monitor is designed to detect leaks specifically between the primary and secondary containment systems of underground storage tanks (USTs). This monitoring system can provide real-time data regarding the integrity of the dual-walled tank system, ensuring that if a leak were to occur in the primary containment (the inner wall), it would be detected before any fuel can escape into the surrounding environment. The primary function of interstitial monitoring is to measure any changes in conditions between these layers, often using sensors that can alert operators to the presence of liquid or vapors in the interstitial space. This is crucial for preventing environmental contamination and adhering to regulatory requirements for UST safety. The other options highlight different concerns. Loss of fuel due to theft is related to security issues rather than containment integrity. Detecting vapors in the air space relates more to vapor recovery systems and not the structural containment of a UST. Problems with the cathodic protection system involve the prevention of corrosion on metal components but do not directly concern leak detection between containment layers.