By using this bomb-made tracer -- tritium -- and other sophisticated testing techniques, a key question in the world's largest chromium-6 contamination site will be finally answered: How much of the chromium-6 plume in Hinkley's underground water supply is naturally occurring, and what was put there by PG&E's operations (which began in 1952)?
An earlier study, which was conducted in 2007, was scrapped last year because an independent scientific review determined it was "completely worthless," the words used by one of the three experts hired by the California Water Resources Board to review the study. Some residents had always questioned the study's findings that chromium-6 occurred naturally in the underground water.
The regional water agency charged with the Hinkley cleanup, which is a subsidiary of the state water board, continues to require PG&E to draw plume boundaries using the maximum background level from the 2007 data of the now discredited first study until conclusions from a new study replace it.
The new study is expected to take four years -- perhaps more.
PG&E, state water agency engineers and the Hinkley community all agree that the right person to lead the new study is John Izbicki, a research hydrologist with the United States Geological Survey in San Diego.
Izbicki has studied the groundwater of the Mojave Desert for 20 years and has pioneered the use of another marker, which when coupled with tritium, could settle the "nature versus PG&E" debate that has swirled over Hinkley for decades.
Many millions of dollars in cleanup costs are at stake because California law requires polluters to decontaminate down to the level that existed prior to their operations.
"Tritium rarely occurs naturally," Izbicki said. Its presence on Earth is largely the result of the energy released during above-ground nuclear testing, which ended on Oct. 10, 1963, due to a globally accepted treaty banning nuclear testing in the atmosphere, space or ocean.
The United States ramped up its above ground nuclear testing after the former Soviet Union ended its monopoly on the nuclear weaponry with its own atmospheric blast on Aug. 29, 1949.
As a result of the nuclear arms race that followed, tritium production surged globally for more than a decade.
Because of that light-switch-like cutoff, this rare type of hydrogen has become a scientifically useful time-marker around the globe, Izbicki said.
In addition to using tritium, Izbicki has pioneered a technique that uses "subtle differences in the physical and chemical properties" within chromium-6 to identify different samples as being from the same source.
Thus chromium-6 from PG&E's compressor station would have a different "atomic fingerprint" than chromium-6 formed naturally in the Hinkley area, Izbicki said.