Before placing material for which zone do we excavate, lay pipe, and hand ramp material below the pipe haunch that cannot be reached by mechanical tampers?

• A. Cover Zone
• B. Top Zone
• C. Bedding Zone
• D. Lowest Zone

Answer: (A)

The idea is about how pipe trenches are backfilled in stages and how each stage is prepared. When installing a pipe, you first form a bedding layer at the bottom to give the pipe a solid, even bearing surface. Then you build up the sides with haunch material to support the pipe and keep it in position. In spots where a mechanical tamper can’t reach under the pipe haunch, you manually compact that material to avoid voids and settlement.

Only after those bottom and side preparations are properly done do you place the top backfill—the material that forms the cover over the pipe. So the material you’re about to place is the covering, which goes above the pipe once bedding and haunching are complete.