California ICC UST Inspector Practice Exam

Which type of single-wall UST must NOT be upgraded to double-wall UST systems?

1. Tanks containing liquids with a pH>13

2. Waste oil tanks

3. Solvent tanks

4. Motor vehicle fuel tanks

The correct answer is: Motor vehicle fuel tanks

The requirement for upgrading single-wall underground storage tanks (USTs) to double-wall systems primarily focuses on the potential for environmental contamination and the risks associated with the stored substances. Motor vehicle fuel tanks, despite being commonly used and subject to regulations, have not been designated for mandatory upgrade to double-wall systems under certain regulatory frameworks. This is primarily due to existing safety measures such as regular inspections and monitoring protocols that are already in place for these tanks. These measures help mitigate risks associated with leaks. Additionally, the types of fuels stored in motor vehicle fuel tanks, along with the industry's established practices for maintenance and monitoring, allow for a different regulatory approach that assumes a lower environmental risk compared to other types of tanks. In contrast, single-wall tanks containing hazardous materials—such as those with a high pH, waste oils, and solvents—are subjected to stricter controls and upgrade requirements due to their higher potential to cause environmental harm in case of a leak. Thus, motor vehicle fuel tanks can be an exception to the upgrade rule, focusing instead on other preventive measures.