To ensure proper compactness around piping, trenches must be backfilled within clean earth to what minimum height above the top of the pipe?

The requirement to backfill trenches with clean earth to a minimum height above the top of the pipe ensures that the pipe is adequately supported and protected from damage due to surface loads or settlement. Backfilling to a height of 12 inches above the top of the pipe creates a stable environment that minimizes the risk of movement or shifting, which can lead to misalignment or failure of the piping system. This height also helps to facilitate proper compaction, allowing for the earth to closely surround the pipe, thus enhancing the overall integrity of the installation.

While other heights might offer some support, 12 inches strikes a balance between providing enough cover to protect the pipe while also allowing easy access and installation considerations. Proper trench backfilling practices are crucial in plumbing to ensure longevity and reliability in the system.