Under stable bottom conditions, after ensuring bottom is dry, what is the required action for the trench?

• A. The trench shall be left unbackfilled until site grading.
• B. The trench shall be bedded and initially backfilled to grade.
• C. The trench shall be filled with concrete only.
• D. The trench shall be sealed with tar.

Answer: (B)

When the trench bottom is dry and stable, the next step is to bed the pipe and begin backfilling up to grade. Bedding creates a uniform, cushioned support for the pipe, eliminating sharp rocks or uneven spots that could crush or misalign it. Backfilling to grade at this stage stabilizes the trench, helps distribute loads, and prevents settlement as the rest of the fill is placed. The initial backfill is placed in lifts and compacted to remove voids and protect the pipe as it goes deeper. Leaving the trench open or filling with concrete only or tar does not provide the proper support and long-term stability for typical trench installations.