What is the recommended compaction percentage of the tank during backfill?

The recommended compaction percentage of the backfill material around an underground storage tank (UST) is crucial to ensure stability and prevent shifting or settling over time. A compaction percentage of 70 is typically advised as it enhances the structural integrity of the containment area.

This level of compaction helps to minimize voids in the backfill, which can lead to settling and potentially compromise the tank's structural support and overall functionality. Proper compaction also helps in mitigating the potential for groundwater contamination, as it ensures that the backfill material remains stable around the tank, thus reducing the risk of leaks.

Selecting a lower compaction percentage, such as 60, may not provide sufficient support, increasing the chances of soil instability and potential structural issues for the tank. Therefore, adhering to the recommended 70% compaction standard is essential for ensuring the long-term performance and safety of the UST installation.