Stormwater from just outside the fence line of the West Lake Landfill complex, the dumping ground for Manhattan Project-era radioactive waste, contains a variety of radioactive isotopes, according to test results released late last month by the Missouri Department of Natural Resources.
The sampling of stormwater overflow, conducted on April 30 as heavy rains pounded the region, found levels of alpha particle activity that exceed the threshold allowed for drinking water. Uranium, radium and gross beta readings all registered within acceptable limits for drinking water, which the department used as a comparative baseline because of its stringent standards.
Regional officials from the Environmental Protection Agency, the entity tasked with overseeing the cleanup of the landfill through its Superfund program, expressed interest in the findings and in further testing, but said that the new data do not signal that public health is at risk.
Additionally, the agency said that without further analysis, a connection cannot be established between the radioactivity found in the tests and the contents of the landfill.
"It doesn't necessarily fingerprint it to the landfill," said Curtis Carey, the public affairs director for EPA Region 7.
Alpha particles, a form of radiation that cannot pierce the skin, need to be ingested to pose a significant health threat. The alpha readings from the sampling could not be attributed to isotopes of uranium and radium that were tested for, so DNR is conducting additional tests for thorium as a possible cause for the exceedance.
EPA officials said that even those additional tests would not be able to conclusively trace radionuclides to the landfill, since low levels of radioactivity can occur naturally.
Republic Services, the landfill operator and one of the parties responsible for financing the Superfund cleanup, echoed the view that the stormwater data do not reveal any health risks since it does not represent a source of drinking water.
"This is not drinking water and drinking water standards are inapplicable," said Russ Knocke, the company's vice president of communications and public affairs, in a statement. "We don't see anything of concern in these results, nor did DNR express any concern when it posted them."
Knocke added that capping the site — a remedy the company supports and one that was nearly pursued in 2008 — would "eliminate community concerns like this once and for all."
But given the relative frequency of heavy rains, others say the test results point to another potential pathway for contamination if waste is not fully removed through the cleanup process.
"It's always been our opinion that this stuff needs to be removed," said Ed Smith, policy director for Missouri Coalition for the Environment. "There are plenty of examples in the historical record of how radioactive material could've moved off site at the landfill."
At the very least, Smith says additional stormwater testing is merited, including a comparison of the site's radioactivity levels to ambient readings found elsewhere in the area. And he feels that more sweeping, systematic testing of the landfill and its surroundings is also justified.
"The EPA hasn't adequately tested the landfill," Smith said. "There's been some off-site testing but there hasn't been close to comprehensive off-site testing of the landfill, just like there hasn't been close to comprehensive on-site testing."