QMS/Specific/TBT-QMS-011

Compaction Testing Safety

Quality & InspectionSpecificCompaction Testing Safety

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Compaction Testing Safety

Toolbox Talk Record

Ref: TBT-QMS-011  |  Issue: 1  |  Date: March 2026
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What?

  • Compaction testing verifies that fill material has been compacted to the required density for structural performance.
  • Common methods include nuclear density gauge, dynamic cone penetrometer (DCP), and sand replacement testing.
  • Nuclear density gauges contain sealed radioactive sources that require specific safety controls and licensing.
  • Only trained and authorised persons may operate nuclear gauges under the Ionising Radiations Regulations 2017.
  • The gauge must be transported, stored, and used in accordance with the radiation protection plan.
  • DCP testing involves driving a metal cone into the ground using a sliding hammer — a manual handling hazard.
  • Sand replacement testing requires excavating a small hole and handling wet material on site.
  • Compaction testing often takes place on active haul roads and working platforms near moving plant.
  • Test locations must be marked and protected to prevent plant from running over testing personnel.
  • Results must be accurately recorded and compared to specification requirements before further work proceeds.

Why?

Radiation safetyNuclear density gauges contain radioactive sources — mishandling causes harmful radiation exposure.
Plant interactionTesting operatives working on the ground near moving earthworks plant are vulnerable to being struck.
Quality assuranceIncorrect compaction leads to settlement, structural failure, and costly remedial works.
Do Don't
  • Ensure nuclear gauge operators hold a valid certificate under the Ionising Radiations Regulations
  • Follow the site radiation protection plan for transport, storage, and use of nuclear gauges
  • Wear the personal dosimeter assigned to you at all times when handling the gauge
  • Mark test locations with cones or barriers to warn plant operators of your presence
  • Coordinate with earthworks teams to ensure plant stays clear during testing
  • Use correct manual handling technique when operating the DCP sliding hammer
  • Record all test results accurately and report any failures to the engineer promptly
  • Store nuclear gauges in the locked, designated storage container when not in use
  • Wear high-visibility clothing and maintain awareness of plant movements at all times
  • Report any damage, loss, or suspected theft of a nuclear density gauge immediately
  • DON'T operate a nuclear density gauge without the required training and authorisation
  • DON'T leave a nuclear gauge unattended or unsecured at any time on site
  • DON'T stand directly over the source housing during gauge operation
  • DON'T transport nuclear gauges in a vehicle without the correct packaging and labelling
  • DON'T carry out testing on active haul roads without isolating the test area from plant
  • DON'T use the DCP with excessive force that could cause shoulder or back strain
  • DON'T falsify or estimate compaction test results — accuracy is essential for safety
  • DON'T ignore your dosimeter readings — elevated exposure must be investigated
  • DON'T allow untrained persons to handle or move the nuclear gauge source container
  • DON'T continue testing if plant operators have not acknowledged your presence

See also: Earthworks Compaction | Material Traceability and Certification

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