Plutonium, other contaminants found offsite near NFS

By Kathy Helms-Hughes

   A 13-acre plume of chemical and radioactive contamination, including plutonium, has been identified in groundwater located offsite from Nuclear Fuel Services Inc. in Erwin.
   State and federal regulators say NFS is meeting all compliance standards and the contamination poses no threat to public health. All radionuclides present are below the Maximum Contaminant Level considered safe by the U.S. Environmental Protection Agency which regulates monitoring wells outside the NFS complex. Activities and monitoring inside the fence are relegated to the Nuclear Regulatory Commission, while Tennessee Department of Environment and Conservation's Division of Radiological Health in Knoxville oversees thorium and depleted uranium in association with the facility.
   According to NFS sampling results from monitoring wells located along the property boundary line, Plutonium-234, 238, 239/240 and 241, were detected in groundwater samples as early as September 1993.
   In November 2001, radioactive plutonium, thorium and uranium were observed in monitoring wells located in the county industrial park which parallels NFS on the northwest side. Technetium-99, which does not exist in nature and is radioactive, also was detected in two of nine offsite wells. All were within levels considered safe. Total uranium is present in onsite groundwater above EPA's safe drinking water standard.
   Plutonium and uranium pose minimal risks to human health outside the body, unless exposure is on a sustained basis. However, if plutonium or uranium gets into the body, the alpha radiation can damage cells and cause mutations that can lead to cancer.
   But it's not offsite migration of radionuclides that have federal officials concerned at the moment; it's chemical contaminants leaving NFS property. PCE (tetrachloroethylene), TCE (trichloroethylene), cis-1,2-DCE, and vinyl chloride all were detected beyond acceptable limits. For example, PCE was found in seven of nine offsite wells during fourth quarter 2001. The highest level charted was 1.403 mg/L (milligrams per liter); 0.005 mg/L is considered safe, according to EPA.
   NFS recently completed a six-month pilot study of a promising new technology which it is hoped will stop the spread of contamination of volatile organic compounds such as PCE and its "daughter products," according to EPA's Leo Romanowski. The company plans a full-scale project which includes drilling 17 to 20 injection wells beginning in June.
   According to groundwater modeling simulations conducted for NFS by Geraghty & Miller, PCE concentrations are expected to decline significantly by 2003 and should be limited to onsite locations by 2011 with concentrations falling below the maximum contaminant level by 2018.
   According to future projections, the uranium plume will be almost identical in 2003 to what it is now, with concentrations dipping below the maximum contaminant level by year 3850.
   "But that's modeling. There's a lot of magic in that," Romanowski said. "It's kind of the best guess they could do based on the current technology of the model and what they know at the site."
   Groundwater in the area generally flows in a northwest direction toward the Nolichucky. "Groundwater is very shallow. A lot of times they just go down like 6 feet," Romanowski said. Shallow and deep monitoring wells generally average 15 to 30 feet in depth, he said. Groundwater flow patterns in the bedrock aquifer beneath the site extend to a depth of about 350 feet.
   NFS attempted to install deeper wells offsite, "but they weren't real fortunate," Romanowski said. "I think they lost circulation, meaning that it was like a void where they lost all of their drilling fluids. It just kind of disappeared."
   Romanowski said underlying geological features could have had something to do with the drilling problems. "When the deeper wells were installed, I want to say five years ago, they had problems, and so we said, 'Look, let's just not mess things up any more. We'll just call that off right now.'
   "Hopefully we can go after the shallower plume and attempt something that will destroy that plume, and if we can continue to add the same nutrients, then maybe those nutrients will follow that same pathway and will go deeper and will destroy whatever might be down in the subsurface. Ultimately there could be an issue with needing to rethink the installation of a deeper well. Probably we wouldn't want to put it onsite, because that's where the source of the contamination is. We don't want to drive it any deeper or give it another pathway."
   Romanowski said he wrote a letter to NFS several years ago telling the company it needed to start looking at offsite migration and source remediation.
   "We found a couple of source areas that they were pumping and treating for years ... But that's not a real efficient way to remove the source of contamination. Even though EPA has advocated pump-and-treat for many years, it's kind of like that was the best thing we had going at the time. You can pump and treat forever but you're still going to have contaminants in the ground. The intent now is to destroy the contaminants and try to stabilize the plume."
   Once injections stopped after the pilot test, PCE levels actually increased as more of the contaminant moved into the area where it had just been destroyed, Romanowski said.
   "Where the injection well was placed may not be the absolute, only source in that area," he said. "It might be a 200-foot-wide area, so even though you killed the PCE in a 25-foot section, if you stop the injection of molasses, there could be some migration of PCE from the outlying area back into it."