1st Move
After he had finished purchasing the container, the first thing he did was make sure that the lid was on tightly. Instead of utilizing massive double doors, he closed off this entrance in order to guarantee that nothing could enter or exit the building, particularly any leaks. After that, he put a door that swings inward on the opposite side of the opening.
No Room For Mistakes
The most significant error that Wayne could have made was to excavate a hole that was too small to accommodate his container. Because of this, he made sure to dig a hole that is at least two feet deeper than the height of the container, in addition to leaving two feet of open space on each side of the hole.