JEFFERSON COUNTY, Colo. (CBS4) – Testing for plutonium continues at Rocky Flats National Wildlife Refuge in Jefferson County. The Jefferson Parkway construction project was put on hold after elevated levels of plutonium were found in a soil sample in August.

(credit: CBS)

It’s believed the plutonium came from the former Rocky Flats nuclear weapons plant. Surrounding area was turned into a wildlife refuge after the facility shut down — and there was a major cleanup effort.

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Future trails are planned in the area, including the Rocky Mountain Greenway Trail. When completed the 80-mile trail would connect the Rocky Mountain Arsenal to Rocky Mountain National Park. It’s currently held up at Rocky Flats.

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Rocky Flats National Wildlife Refuge

(credit: CBS)

Hundreds more soil samples were taken in September and preliminary tests on some of those samples do not show the same spike in plutonium.

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The state health department says it still has more testing to do.