Environmental studies of land near cinnabar mine yield encouraging results

The Prineville City Council voted Wednesday to follow through with the purchase of 460 acres of IronHorse property from Brooks Resources.

The city entered a purchase agreement for the property in August and has since been conducting due diligence work to determine if they would follow through with the $1.2 million transaction.

The decision to buy the property also included council approval to borrow $700,000 to help fund the purchase.

The city has shown interest in the property because it includes 305 acres of water rights and would also enable the municipality to connect Combs Flat Road to Peters Road or Barnes Butte Road, secure future recreational space, or protect the Barnes Butte area, a popular historical landmark.

A significant portion of the due diligence process involved an environmental assessment of the property, particularly near the northeast border of the property where cinnabar mining had taken place many years earlier. A study conducted by Farallon Consulting, an environmental firm, found that most of the property was free of mercury following a clean-up effort by BLM last summer, but not all areas.

Of the 49 samples taken, 41 of them contained 0 parts per million, and of the remaining eight, the highest sample contained 129 ppm and the second, only 23 ppm. According to DEQ risk-based concentration thresholds, residential development is acceptable if contamination is 23 ppm or less.

While those results were encouraging, the city wanted more information about the property before they decided to buy it, so additional tests were conducted during the past month.

"We went up and sampled nine different spots, which is where the portals of the mineshafts are," explained City Engineer Eric Klann. "The actual mineshafts are right on the edge of the property the city would be acquiring. The material was actually processed on the BLM property where the clean-up occurred last summer."

The results came back even more encouraging than before. The majority of the nine soil samples found small amounts (1.6 to 2.3 parts per million) of contamination, while two others were 23.1 and 45.4. Although that exceeds the residential limit, it comes in well under DEQ's recreational limit of 132 ppm.

"Somebody could be there 300 days a year for two hours a day and wouldn't have a problem," Klann said. "We were very, very happy with the results."

Regarding the contaminated portions of the property, Klann said that Brooks Resources has agreed to obtain a No Further Action determination from the DEQ, meaning no additional clean-up of the property is necessary.

"They have committed to getting that within one year of us purchasing it," Klann said. "If they are unable to get that, they would take back those small mining areas so we would not have the liability associated with that site."

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