Cleanup crews will begin this July to chase down and capture runaway arsenic in Manning Canyon just west of Cedar Fort.
They'll then bring the deadly dust back to the mounds of tailings in the canyon, where it will all be capped and covered, part of a multimillion-dollar effort to make the area safe for recreationists again.
Last year, EPA officials became acutely aware of the problem. Mounds of mine tailings from the gold and silver mines that operated between 1890 and 1930 had eroded. The tailings, covering about 1,470 acres of land and amounting to 720,200 cubic yards of material, were threatening not only the people running their off-road vehicles over them but downstream residents of Cedar Fort and Fairfield.
Enough arsenic was found in some test areas to alarm officials.
Anything above 500 parts per million is unacceptable, said Bureau of Land Management field representative Jack Brown. Levels of arsenic in some areas have been as high as 10,000 parts per million.
In addition to the arsenic, there are concentrations of lead and mercury in the soil near the mine sites.
Utah County Commissioners Tuesday agreed to periodic closure of Lewiston Road, the eastern access to the canyon, over the next three years while cleanup is conducted.
County Engineer Clyde Naylor said the county is cooperating with the Bureau of Reclamation to facilitate the cleanup operation.
"We don't have any more responsibility than that," he said.
Kerry Southworth, a civil engineer with the Bureau of Reclamation, said contracts for the cleanup operation will probably be signed in July, depending on how soon everything comes together.
"We're looking at bringing back all of that material that's eroded and putting a cap over it. We'll then put clean fill around the perimeter and take steps to protect it from future erosion."
Southworth said soil tests have identified the areas that have enough arsenic to exceed acceptable limits.
He also said workers will probably have to don protective apparatus for the cleanup process.
"We will need a site safety and health plan," he said.
In the meantime, warning signs have been posted advising motorcyclists, four-wheelers and ATV drivers to stay off the mounds.
However, many ignore the signs and continue to play in the canyon.
Brown said he's tried in the past to warn those in the canyon about the hazard, but few have taken him seriously.