Final answer:
Secondary containment for day tanks must typically have a capacity of at least 100% of the capacity of the tank they serve, as per regulations to prevent spillage in case of tank failure.
Step-by-step explanation:
The question relates to the requirements for secondary containment for day tanks, which are often used in industrial or commercial settings for storing oil, chemicals, or other substances. The National Fire Protection Association (NFPA) and the Environmental Protection Agency (EPA) typically have regulations that dictate the necessary capacity of secondary containment systems.
These requirements can vary, but generally, secondary containment must have a capacity of at least 100% of the capacity of the tank served in order to contain potential spills or leaks. This ensures that in the event of a tank failure, the secondary containment will be able to hold all the contents of the day tank without any spillage.