Which of the following best describes "secondary containment" systems for USTs?

The definition of "secondary containment" systems focuses on their fundamental purpose, which is to prevent hazardous substances from escaping into the environment. These systems are an essential component of underground storage tank (UST) regulations because they serve as a safeguard against leaks and spills that could occur from the primary tank.

Secondary containment systems typically involve structures that can hold spilled materials and prevent them from contaminating soil and groundwater, which is crucial for environmental protection and public health. This system can take various forms such as double-walled tanks, containment liners, or external barriers that encircle the primary storage tank. It is specifically designed to prevent environmental damage in case of a failure or breach in the primary containment system.

Understanding the importance of secondary containment emphasizes the need for compliance with regulatory requirements, ensuring safe storage of hazardous materials and protecting the surrounding environment. Other options, while they may refer to different aspects or features of USTs, do not accurately represent the primary function of secondary containment systems.