To address the lack of controls that allowed the falsification of gamma gamma logging testing data by Technician A and the engineer, we recommend that Caltrans require that Foundation Testing Branch technicians submit to an engineer both the raw data file and log ASCII data file for every gamma gamma logging test performed for a project to help ensure that testing data has not been falsified. (See I2009-0640, p. 24)
In November 2011, the supervisor of the Foundation Testing Branch instructed staff to submit to the assigned project engineer both the raw data file and the log ASCII file for every gamma gamma logging test performed. In addition, the supervisor and the office chief developed and implemented a gamma gamma quality control checklist to ensure that technicians follow appropriate testing procedures.
In October 2012, the Foundation Testing Branch implemented a new process in which a second Foundation Testing Branch engineer, different from the engineer assigned to evaluate a gamma gamma logging test, performs a secondary review of the test data to ensure the accuracy and quality of the test. In addition, the supervisor of the Foundation Testing Branch performs a final review of all gamma gamma logging test results. Finally, in October 2012, the Gamma Gamma Logging Data Integrity Review Team provided the Foundation Testing Branch with a gamma gamma logging data checker tool, which it immediately placed in use.