Cleanup Verification Found Plutonium Hot Spots at Rocky Flats

A 9NEWS report highlighted an important finding from the final years of the Rocky Flats cleanup: independent verification identified areas of plutonium contamination that remained above the cleanup action level even after remediation work had been completed.

The issue centered on the 903 Pad and 903 Lip area, one of the most contaminated parts of the former Rocky Flats Plant. According to a 2006 Government Accountability Office review, ground-based scanning found five areas along the perimeter of the 903 Lip with plutonium concentrations above 50 picocuries per gram of soil, the cleanup agreement’s action level for surface soil. Those areas were subsequently remediated.

Independent sampling by the Oak Ridge Institute for Science and Education identified another 13 “hot spots” above the 50 pCi/g action level. The measured concentrations ranged from 65 to 425 pCi/g. DOE initially maintained that additional remediation was not required because the cleanup had been performed according to the approved methodology, which required at least 90 percent of an area to meet the cleanup criteria. After concerns were raised and DOE consulted with EPA and Colorado regulators, the additional hot spots were remediated.

The GAO also found limitations in the broader verification effort. An aerial radiation survey intended to detect plutonium at the cleanup action level achieved that sensitivity over only about 25 percent of the site, largely because of ground moisture and the altitude of the helicopter survey.

These findings are an important part of understanding what “cleanup complete” meant at Rocky Flats. The physical cleanup was declared complete in 2005, but verification continued to identify localized contamination requiring additional attention. The episode also illustrates why independent sampling and verification were important parts of evaluating the final cleanup.

For Rocky Flats Downwinders, this history remains relevant because decisions about stewardship, monitoring, public access and development around Rocky Flats continue to depend on an accurate understanding of what was removed, what remained, and how the cleanup was verified.

Original reporting: 9NEWS — “Contaminated spots found outside cleanup area at Rocky Flats.”

Supporting source: U.S. Government Accountability Office, Nuclear Cleanup of Rocky Flats: DOE Can Use Lessons Learned to Improve Oversight of Other Sites’ Cleanup Activities, GAO-06-352, July 2006