Nuclear Testing of Utility Trench Backfill

by Vincent J. Perricelli, Resident Engr.; Chas. H. Sells, Inc., Webster, N.Y.,

Serial Information: Civil Engineering—ASCE, 1979, Vol. 49, Issue 11, Pg. 68-70

Document Type: Feature article


For many years, Westchester County municipalities were resigned to the fact that compaction of utility trenches could not be done satisfactorily and that settlement and road failure would inevitably occur. To reduce the impact of such settlement, they established natural-consolidation time-delay periods which extend up to 6 months. The use of the nuclear moisture-density gauge for testing backfill compaction has proven that settlements need not occur. Advantages of this type testing versus conventional methods are: simplicity, speed; immediate test results while backfill is taking place; no disturbance of the compacted soil. Disadvantages are initial cost of the gauge; need for specially trained personnel; need for a State Radiological Materials License. Twenty-eight governmental agencies in Westchester County have relaxed their time-delay periods and now permit immediate permanent pavement restorations on those projects where nuclear moisture-density testing is used for control. Ancillary benefits include fewer complaints, reduced claims for vehicle damage, and improved public relations.

Subject Headings: Compacted soils | Trenches | Backfills | Moisture | Compaction (material) | Soil tests | Local government | Lifeline systems

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