California ICC UST Inspector Practice Exam

If a UST system uses an overfill alarm, when must the alarm trigger to alert the transfer operator?

1. 85% full

2. 95% full

3. 90% full

4. 80% full

The correct answer is: 90% full

The use of an overfill alarm in a UST (Underground Storage Tank) system is crucial for preventing overfilling, which can lead to environmental contamination and safety hazards. The alarm is designed to provide a timely alert to the transfer operator, ensuring that action can be taken to stop the flow of product before the tank reaches a critical level. When the alarm is set to trigger at 90% full, it allows for a buffer between the alarm activation and the actual maximum capacity of the tank. This 90% threshold is aligned with common regulatory guidelines that promote safety and environmental protection. By alerting the operator at this level, the system ensures that there is enough time for the operator to respond appropriately, minimizing the risk of spill incidents. This triggering point is significant because it strikes a balance between operational efficiency and safety. If the alarm were to trigger too late, such as at 95% or even 85%, there could be insufficient time to address the situation effectively, increasing the risk of overflow. Thus, setting the alarm at 90% full is a proactive measure that enhances the safety protocols necessary for managing the environmental risks associated with UST systems.