California ICC UST Inspector Practice Exam

Which of the following methods is NOT approved for release detection of single-walled tanks?

1. Vadose Zone monitoring

2. Ground Water monitoring

3. Automatic tank gauging

4. Interstitial monitoring

The correct answer is: Interstitial monitoring

In the context of release detection for single-walled tanks, interstitial monitoring is not an approved method. Single-walled tanks do not have an outer layer or barrier, which means there is no interstitial space to monitor. Release detection methods approved for single-walled tanks include groundwater monitoring, vadose zone monitoring, and automatic tank gauging, as each of these methods enables the identification of leaks or releases without the necessity of an additional containment layer. Groundwater monitoring involves checking the water table and surrounding soil for contamination, while vadose zone monitoring focuses on the area between the ground surface and the water table. Automatic tank gauging utilizes sensors to detect changes in the tank’s contents, providing real-time data on potential leaks. Since interstitial monitoring relies on a secondary containment layer to detect leaks in the space between two tank walls, it is suitable for double-walled tanks, but not for single-walled tanks. Hence, it cannot be employed for release detection in single-walled systems.