High Levels of Plutonium and Americium in Surface Water at Rocky Flats and Long-Term Stewardship at the Site
LeRoy Moore, PhD,
Rocky Mountain Peace & Justice Center, February 11, 2012
Recent findings of high levels of plutonium and americium in surface water at Rocky Flats suggest that the Department of Energy’s program of Long-Term Stewardship at the site is already unraveling.
DOE Rocky Flats recently reported these numbers for composite surface water samples of Pu-239/240 and Am-241 at monitoring point GS-10 on South Walnut Creek (a point of evaluation, not a point of compliance):
• Composite sample 7/21/11–8/24/11: Pu = 0.938 pCi/L, Am = 2.97 pCi/L
• Composite sample 7/21/11–8/24/11: Pu = 4.07 pCi/L, Am = 4.01 pCi/L
• Composite sample 8/24/11–9/29/11: Pu = 0.020 pCi/L, Am = 0.044 pCi/L
• Composite sample 9/29/11–10/25/11: Pu = 0.658 pCi/L, Am = 0.877 pCi/L
Multiple exceedances of the state standard: All but one of these readings, (8/24/11–9/29/11) show levels of both plutonium and americium that exceed the 0.15 pCi/L standard for Pu/Am in surface water. DOE’s report says that the plutonium numbers are being discounted but not the americium ones. In the samples cited above, the highest numbers appear in the second sample for 7/21/118/24/11 when the level for Pu (4.07 pCi/L) is 27.13 times the 0.15 standard, and the level for Am (4.01 pCi/L) is 26.73 times the standard. Whether we look at both Pu and Am, or at Am alone, the quantity is about 27 times the established standard.
Relation to breaching of dams: Last summer DOE issued an environmental assessment and Finding of No Significant Impact, giving itself a green light to breach dams of holding ponds in North Walnut Creek, South Walnut Creek, Woman Creek and the Present Landfill pond. Historically the role of the holding ponds was to prevent contaminants like plutonium from continuing downstream so that when surface water reaches the site boundary it meets the state’s 0.15 pCi/L standard. Given the recent report that plutonium and americium levels in surface water at a point of evaluation exceed the established standard, and given the decision to breach the holding pond dams and to return free-flow to the streams at Rocky Flats, isn’t it reasonable to expect that the surface water standard will be violated downstream where it exits the DOE site?
An overlooked warning: A 2001 report done as part of the Rocky Flats Actinide Migration Evaluation concluded that cleanup of plutonium in soil at Rocky Flats to as low as 10 pCi/g (by contrast to the gradated 50+ actually adopted) would result in failure at areas downstream of the 903 Pad to meet the 0.15 pCi/L standard for Pu/Am in surface water (see Win Chromec, Report on Soil Erosion and Surface Water Sediment Transport Modeling for the Actinide Migration Evaluation at the Rocky Flats Environmental Technology Site, Kaiser-Hill Co., 00-RF-01823/DOE-00-93258, February 2001, pp. E-3, E-4). The author of this report thought it would be impossible to pin down the precise source of the plutonium in surface water that would fail to meet the standard, much less to predict when such failure would occur. The report focused on areas downstream of the 903 Pad, that is, on the Woman Creek watershed. Is it possible that what the report concluded about that watershed could also occur in the Walnut Creek watershed where the recent surprisingly high readings for Pu/Am in surface water were recorded? This report was part of Kaiser-Hill’s AME work, but it was not cited in the final summary of the AME project. While the report warned that elevated levels of plutonium will eventually show up in surface water, the AME’s final summary announced a very contrary conclusion, one that became the foundational assumption for the Rocky Flats “cleanup,” namely, that plutonium left in the Rocky Flats environment will be “relatively immobile” (see Kaiser-Hill, AME Pathway Analysis Summary Report, ER-108, April 2004).
A prediction from the past: A National Academy of Sciences report on long-term stewardship of DOE sites published a dozen years ago concluded that “DOE’s preferred solutions reliance on engineered barriers and institutional controls – are inherently failure prone.” Further, “much of our current knowledge of the long-term behavior of wastes in environmental media may eventually be proven wrong. Planning and implementation at these sites must proceed in ways that are cognizant of this potential fallibility and uncertainty.” (Tom Leschine et al, Long-term Institutional Management of U.S. Department of Energy Legacy Waste Sites, National Academy Press, 2000, pp. 4 and 5). What happened at Rocky Flats was precisely the opposite of what the NAS recommended in that, as noted above, those responsible for the “cleanup” assumed that plutonium left in the environment would be “relatively immobile.” The recently reported high levels of Pu/Am in surface water suggest that this assumption is not simply false but harmfully so.
The NAS authors realized that the very concept of long-term stewardship is foreign to our conventional patterns of thought and action, that we don’t typically take the kind of long-term view necessary for dealing with long-lived radionuclides. What is showing up at Rocky Flats, however, is not something long-term but something very short-term. In 2011, a mere six years after completion of the “cleanup,” we have a very short-term environmental consequence of plutonium migration, and, second, we have a failure of physical or engineered barriers not because those barriers collapsed on their own but because DOE authorities, with the complicity of the regulators, made what appears to be a hasty decision to breach the dams of holding ponds. When the water flows freely, how long before plutonium and americium move with it? How long before we see the surface water standard violated?