How many feet of backfill must be placed between adjacent tanks and excavation walls?

The correct amount of backfill that must be placed between adjacent tanks and excavation walls is 2 feet. This specification is critical for maintaining the structural integrity of the underground storage tank (UST) system.

A minimum of 2 feet of backfill provides sufficient space to allow for proper compaction and drainage, thus reducing the risk of potential soil movement that could adversely affect the USTs. This backfill distance helps in evenly distributing the weight of the surrounding soil and minimizes the stresses on the tank walls which could lead to buckling or leaks.

Moreover, having adequate space for backfill aids in protecting the tanks from external forces, such as shifts in the earth due to weather changes or nearby construction activities. It also facilitates access for maintenance and inspection, ensuring that any potential issues can be addressed without extensive excavation.

Strict adherence to this guideline is essential for compliance with safety regulations and for preventing long-term damage to the UST system.