What is the minimum amount of backfill required above the gravel system in this setup?

The minimum amount of backfill required above the gravel system in a septic installation is essential for several reasons, including proper drainage, structural support, and protection of the system components. A depth of 6 inches allows for adequate covering of the gravel, ensuring that it is adequately insulated from surface elements that could lead to freezing or other damage. This amount is also enough to provide a sufficient barrier to protect the system from disturbances, such as compaction or erosion caused by surface water runoff.

Choosing 6 inches as the minimum backfill ensures that the system functions as intended and maintains its longevity while preventing undue stress on the components. This specification aligns with industry standards and practices to ensure that the septic system operates efficiently and stays protected from various environmental factors.