The bottom of a trench for a drinking water installation should have compacted soil to provide what?

• A. To provide continuous firm support for the pipe barrel
• B. To increase drainage
• C. To improve insulation
• D. To speed up backfill

Answer: (A)

A uniform, dense bearing surface under the pipe is essential. Compacted soil at the trench bottom creates a continuous, solid bed that distributes load along the pipe and prevents voids. This stable foundation minimizes differential settlement and reduces the risk of pipe movement, deformation, or joint leaks as backfill settles and the trench is backfilled above. In short, it keeps the pipe in proper alignment and grade, protecting the integrity of the installation.

The other ideas aren’t the primary goal here: compacting the bottom doesn’t mainly improve drainage; soil compaction reduces voids and permeability anyway, which isn’t about insulation; and compacting the bottom isn’t intended to speed up backfill—proper bedding and controlled compaction of the entire trench are what ensure a stable, long-lasting installation.