Updated at 2:45 p.m. on Saturday, April 2, with information from the EPA:

The U.S. Environmental Protection Agency will clean up radioactive contamination confirmed to be found in soil on private property adjacent to the West Lake Landfill in Bridgeton.

Data released Friday by the Missouri Department of Natural Resources shows two soil samples "on private property" have levels of thorium higher than what is allowed for unrestricted use by the EPA, including one sample three times higher than the limit. Those samples were taken on the border of a lot used by AAA Trailer Services.

The new report is an update of interim data released in January of testing done last November. The initial report noted the contaminated soil samples were located "at the unmarked perimeter of the facility and neighboring private property," and could in fact be within the landfill perimeter. This final report makes clear they are located on private property.

Missouri Department of Natural Resources

EPA Region 7 spokesman Ben Washburn said these areas were not new to the agency. He said the area was previously identified as part of a "buffer zone" on the border of the landfill, where contamination was found due to soil erosion and soil movement, as reported in its 2008 record of decision. The EPA is in charge of managing clean-up at Superfund sites like West Lake Landfill, and making potentially responsible parties pay for that process.

Washburn said the EPA will clean up this off-site contamination while it conducts "surface fire mitigation." That process involves clearing brush and chipping it onsite, and then covering the area with fire-proof matting, in order to reduce the possibility of surface fires. The EPA previously said this process will also involve additional surface-level gamma scans to look for any spots missed in earlier tests.

Previously released work schedules indicate the cover and subsequent testing should be completed by the end of June. The EPA has said it will have a final plan for addressing the radioactive waste at West Lake Landfill by December.

In response to the EPA's plans for remidation, a spokesman for landfill owner and one of the potentially responsible parties Republic Services, Richard Callow, wrote in an email, "This is another important step towards an EPA Record of Decision by the end of the year."

Ed Smith of the Missouri Coalition for the Environment calls Friday's findings "fairly significant."

"The EPA has said previously that the radioactivity is not off-site and it appears the Missouri Department of Natural Resources has found radioactivity off-site," he said. "So comprehensive off-site testing all the way around the landfill is needed. We have to know where all the radioactivity is before it can be cleaned up."

Still the report also warns that "it would be inappropriate to use these results by themselves to make definitive conclusions regarding the absence, extent of presence, or potential health risk of radioactive contamination found at investigated sites."

"You have to have an exposure to radioactivity for there to be a health consequence or a health issue," Smith said. "The contamination found would have to either be breathed in by somebody or eaten or they would have to be in very near proximity to it...that’s when you have a health concern."

Previous tests by state experts, as part of a lawsuit by Missouri Attorney General Chris Koster against the landfill's owners, had found radiation had spread off-site. Koster, who is running for governor, has harshly criticized the EPA for missing deadlines in its oversight of the West Lake Landfill.

A Superfund site, the landfill contains radioactive waste leftover from nuclear weapons building during the Manhattan Project.

Area residents have long been concerned that radioactive material was moving off-site and that could be in the adjacent Bridgeton Landfill, where an underground smoldering has been burning for years. Recently, a group of mothers and activists, as well as representatives from Koster's office, met with EPA Administrator Gina McCarthy about a possible buy-out and relocation program for people living around the site.

"She is aware of the areas the EPA has failed our community, and there is no more denying that mistakes have happened at this site," wrote Just Moms STL's Karen Nickel, on Facebook. "The Administrator has committed into looking into relocation."

In a tweet, McCarthy made no promises but wrote that she looks "forward to our continued dialog."

Missouri Department of Natural Resources

Last week, the EPA released data indicating that radioactive contamination was found on the northern edge of the Bridgeton Landfill, farther south than previously reported. That report put the contamination a few hundred feet away from the underground fire. The EPA is currently trying to determine where to construct an isolation barrier between the contamination and the fire.

The MDNR's final report recommends additional investigations by the EPA and the potentially responsible parties. The department also said it shared its data with the EPA and the private property owners.