Backfill should be completed at what distance before the wheel is loaded?

Backfill should be completed at what distance before the wheel is loaded?

• A. 12 inches
• B. 24 inches
• C. 36 inches
• D. 48 inches

Answer: (C)

Wheel loads over a trench need a solid, compacted backfill to spread the pressure and keep the pipe in place. If you apply a heavy load before there’s enough surrounding material, the weight can cause the pipe to shift, settle unevenly, or be crushed locally. Building backfill up to three feet before the wheel passes provides a thick cushion of compacted material that distributes the load more evenly and supports the pipe’s sides as traffic moves over it. This staged filling, done in lifts, helps prevent differential settlement and pavement distress. The other depths don’t give the same reliable combination of cushioning and lateral support.

Wheel loads over a trench need a solid, compacted backfill to spread the pressure and keep the pipe in place. If you apply a heavy load before there’s enough surrounding material, the weight can cause the pipe to shift, settle unevenly, or be crushed locally. Building backfill up to three feet before the wheel passes provides a thick cushion of compacted material that distributes the load more evenly and supports the pipe’s sides as traffic moves over it. This staged filling, done in lifts, helps prevent differential settlement and pavement distress. The other depths don’t give the same reliable combination of cushioning and lateral support.