When are diked areas required for storage tanks?

Diked areas are specifically required for bulk storage tanks to manage potential leaks or spills, ensuring that any accidental releases of hazardous materials are contained and do not escape into the environment. This requirement is rooted in environmental safety regulations, which are designed to prevent contamination of soil and water resources. By using diked areas, operators can minimize the risk of pollution and facilitate easier clean-up in case of a spill, as these areas can hold the contents of a tank until they are dealt with appropriately.

The other scenarios mentioned in the options do not reflect the comprehensive need for diked areas. For example, while certain regulations may apply to liquid fertilizers, not all storage scenarios necessitate diked areas, particularly for smaller residential containers or during specific weather conditions like rain events. The focus on bulk storage tanks highlights the significant volumes typically involved, which pose a greater risk and therefore require more stringent preventative measures like secondary containment systems.