Water is entering a highway drainage trench and softening the bottom. What is the primary reason to dewater before placing pipe and bedding?

1. Water in the trench automatically classifies the soil as stable rock
2. A wet, unstable bottom will not support the pipe or allow specified compaction of bedding and haunches
3. Dewatering is required only so that nuclear gauges will read zero moisture
4. Standing water improves pipe flotation resistance during backfill