Trenches that are over-excavated and require backfilling below the level of the pipe shall be backfilled in layers not exceeding:

The requirement to backfill trenches in layers not exceeding 6 inches is crucial for maintaining the integrity of the pipeline and ensuring proper support. Backfilling in layers allows for better compaction, reducing the risk of settling or shifting, which can lead to pipe damage or misalignment over time. When backfilling in thicker layers, it becomes challenging to achieve adequate compaction, which could result in voids or weak spots beneath the pipe.

Additionally, this practice helps distribute loads evenly above the pipeline, minimizing the risk of stress on the pipe itself. The 6-inch layer provides a balanced approach: it is thick enough to facilitate effective manual or mechanical compaction while being manageable for laborers. Following this guideline ensures that the backfill offers consistent support and reduces the likelihood of future maintenance issues.