A nuclear density test on a utility trench backfill lift fails the specified compaction. The next truckload of base course is already waiting. What should happen?
Correct Answer
B) Rework moisture and density, recompact the lift, and retest before placing the next lift
A failed backfill lift must be corrected and retested before it is covered, because later lifts cannot reliably fix inadequate density below. Other choices bury the deficiency or average away a localized failure.
Why This Is the Correct Answer
A failed backfill lift must be corrected and retested before it is covered, because later lifts cannot reliably fix inadequate density below. Other choices bury the deficiency or average away a localized failure.
Why the Other Options Are Wrong
Option A: Cover the lift before it dries out
The trap in A is Cover the lift before it dries out. That selection is wrong because it answers the Compaction failure prompt with the wrong practical move.
Option C: Average the failed test with passing tests from another area, leaving compaction failure unverified
Choice C (Average the failed test with passing tests from another area) is rejected because the choice would not get the project to Rework moisture and density, recompact the lift, and retest before placing the next lift, which is the Compaction failure result verified by the source.
Option D: The site crew should accept the lift if the surface looks tight
In site construction, Accept the lift if the surface looks tight is the wrong selection for Compaction failure: the option does not produce the required Compaction failure outcome, Rework moisture and density, recompact the lift, and retest before placing the next lift.
Memory Technique
Tag the scene with compaction failure: wrong actor or wrong timing means the fix is not Rework moisture and density, recompact the lift, and retest before placing the next lift.
Reference Hint
Open Pipe and Excavation Contracting, 2011; use the index entry or section for "Backfill compaction testing and lift control" to confirm that A failed backfill lift must be corrected and retested before it is covered, because later lifts cannot reliably fix inadequate density below.
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