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Radiation Health and Safety Scanning Survey: Final Progress Update FAQs


1. What were the major elements of the scan on A-2?

The CDPH survey included the scanning of all of Parcel A-2 accessible to CDPH staff, in order to assess the radiological health and safety of the public and the environment. This survey employed the use of highly sensitive handheld radiation survey detectors with trained and experienced CDPH health physicists performing gamma walkover surveys of soils and vegetation in accessible areas. In addition, CDPH used a Radiation Solutions RS-700 system that consists of two large volume, highly sensitive gamma mapping detectors to perform gamma scans of the two dirt roads and other accessible hardscaped areas and areas where vegetation was absent or less than four inches in height. Any anomalies that were detected were subsequently investigated by using gamma spectroscopy radioisotope identifiers, Model-Canberra Inspector 1000, that measure the energy range of the suspected anomaly and therefore exactly identify the radioisotope causing the anomalous reading.

2. What were the key findings?

The CDPH found no evidence of any health and safety risks to the public or the environment at Parcel A-2. Key preliminary findings upon completion of the Parcel A-2 fieldwork were that surveyors discovered a total of 100 radiation anomalies, all of which were naturally occurring potassium-40. Final findings (after quality checks and verification) will be included in the final Parcel A-2 report.

3. How does parcel A-2 differ from parcel A-1, and what differences were made in survey techniques to account for these differences?

Parcel A-2 is a large open field with hilly slopes and embankments. There are no residences yet constructed. It has two unpaved dirt roads marked and contoured for future development (Navy Road and Oakdale Avenue). The survey techniques used by staff were the same as those during the Parcel A-1 scan. However, because much of the area contains some form of debris such as paper, metal wires, plastic tubing and other such similar materials, staff had to be more cognizant of the terrain to avoid debris hazards.

4. Were there any rainfall issues within the parcel A-2 surveying period?

No, all scanning work was completed before rain occurred. It rained lightly during the last two days of follow-up fieldwork, but readings were unaffected as they were finished before it started raining heavily. ​​

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