The storage of all 'opened' oil storage containers, whether it be fresh oil or waste oil must be surrounded by a secondary containment system in case of leaks. If you use a bund, it must hold 110% of the capacity of the largest container or 25% of the total amount being stored, whichever is the higher.
Unfortunately, even with best practices followed, accidents can happen and that's where our spill response products can help. It is better to have them and never use them than to suffer a pollution incident and not have the equipment you need for the clean-up.