Answer to Question #4676 Submitted to "Ask the Experts"

What are normal background radiological readings for either groundwater or storm-water runoff? How would I go about finding background readings if I work at a radiological waste site?

Normal background radioactivity levels in groundwater or storm water are variable and depend to a large extent on the geology of the area and the specific mineral content of the soil. The chief radioactive component in natural fresh waters is tritium, an isotope of hydrogen, that is produced by cosmic ray interactions in our atmosphere. Concentrations of cosmogenic tritium in natural fresh waters are typically on the order of a few tens of picocuries per liter. Radium and uranium are also found in surface waters, but at much lower concentrations—typically 1 picocurie per liter or less for radium and a few micrograms per liter for uranium. These levels are so small that the dose rate from radioactivity in surface water natural waters is not measurable.

As for the specific levels in the environs of the radiological waste site where you work, there is likely an ongoing comprehensive environmental monitoring program, including radioactivity levels in surface waters, and the company would likely make these data available to you upon request. Alternatively, the licensing agency for the site and state health department should also have these data and will provide them to you upon request.

Ron Kathren, CHP