California Department of Transportation

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Laboratory Policies and Procedures




Nuclear Density and Asphalt Content Gauge Procedures

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To receive a nuclear gauge for field use, a CalTrans Certified Materials Tester holding a valid Radiation Training Certificate must contact and take delivery of the nuclear gauge from the District 01 Radiation Safety Officer (RSO), or the Alternate Radiation Safety Officer (ARSO) and comply with all pertinent sections of CTM 121.  When a gauge is returned, either the RSO, the ARSO or their appointed delegate must be present to receive, log in and secure the gauge.

In an emergency contact the RSO and /or the ARSO immediately.

RSO, George Thorpe

Office (707) 445-6375

Cell (707) 498-3249

ARSO, Loren Lee

Office (707) 445-6374

Cell (707) 498-9721

Tips and Reminders:

  1. The nuclear gauge must be transported and stored with the corresponding 3-ring binder and under a minimum of three (3) locks.
  2. Never leave a gauge unattended.
  3. Never use a gauge in the rain, not even light rainfall.
  4. CalTrans’ license with the California Department of Health Services, Radiological Health Branch, requires annual wipe/leak tests and analysis on all gauges.  These tests are performed at the end of January.  Therefore, all gauges must be returned to the Lab during that time.  Replacement gauges will be available to those with testing needs.
  5. It is the Field Tester's is responsibility to notify the RSO if the gauge is moved to a different location from the location originally reported.