Dust

Dust rolls off the mine tailings at Freeport McMoran's Sierrita Mine in October 2018.

Freeport McMoran will contribute $200,000 to build a two-mile walking path at Green Valley's new county park as part of a settlement reached over several mine dust violations in 2018.

The walking path will be at the defunct 130-acre Canoa Hills golf course, which is being turned into a natural, open-space park. The proposed name for the park is Canoa Hills Trails – An Open Space Park.

Green Valley Council president Thao Tiedt is thrilled by the news. Had the settlement not been reached, it likely would've been a year or more before the walking path could be built. The path will be primarily be along the road, she said.

"People will be safe while they're walking adjacent to the park and going into the park," Tiedt said.

The mining company must also pay a $30,000 civil penalty, according to a news release from the Pima County Department of Environmental Quality. The penalty will help cover the cost of the investigation.

Hundreds of Green Valley residents reported being inundated by dust from the Sierrita Mine in early October. Some compared the thick dust clouds to snowstorms; layers of dust were found inside homes and medical issues were reported. In November, dust swept past the mine's boundaries again.

The PDEQ sent two Notice of Violation letters to Freeport about the incidents. In each, officials said the company allowed mine dust to escape the boundaries on eight days in September, October and November. They also alleged the company allowed its visible emissions to exceed the 20 percent limit. At one point, it reached 63 percent opacity, according to the county.

The county informed the company it was evaluating a civil penalty for the violations that resulted in both notices. In February, Freeport spokeswoman Linda Hayes said the company had assisted about 800 residents in getting their homes cleaned at a cost of more than $200,000.

David Rhoades, general manager of Freeport's Sierrita operation, responded to the Notices of Violation with nearly identical letters Dec. 14 and Jan. 30. In each, he explained that wetting the tailings dam with water and magnesium chloride have “largely proven effective,” but because of the size of the dam, weather conditions and high wind events can overwhelm those measures.

In the December letter, Rhodes said the tailings dam was damaged by what he called a “six-hour, 500-year storm event,” and that sustained high winds caused the October dust events. He cited NOAA — the National Oceanic and Atmospheric Administration — for the 500-year figure.

In an emailed statement, Hayes said: "We are pleased the final agreement will benefit the community and appreciate the Pima County Department of Environmental Quality working closely with us on reaching that agreement. We have added a new crew dedicated solely to dust control and purchased additional equipment to mitigate potential future dust events. The PDEQ has found these control measures to be effective following recent inspections of the tailings facility."

The golf course was signed over to Pima County on Dec. 21 with the intention of making it a natural, open-space park. It was donated by businessman Morgan North, and does not yet have a name.

The golf course closed in 2013, and was purchased by North a year later along with San Ignacio golf course. North, who owns Borderland Construction, a civil contracting business, never reopened Canoa Hills.

"A lot of work has been done over the summer and it looks wonderful," Tiedt said.

Kim Smith | 520-547-9740

Assistant Editor Kim Smith moved to Arizona from Michigan when she was 16. She graduated from the University of Arizona with a degree in journalism in 1989. She has worked at seven newspapers of varying size in Arizona, Texas and Nevada.

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