COLLEGE STATION When Atlantic Richfield Co. was tasked with cleaning up a major superfund site it had purchased in Montana, Dr. Frank Hons, a Texas A&M University professor, got a call to assist the company's consultants, Pioneer Technical Services.
Hons, a soil and crop science professor, spent two years leading a Texas A&M team studying revegetation solutions on land impacted by 100 years of copper mining, mineral processing and smelting in the Anaconda, Mont. area.
The Anaconda Copper Co., a driving force and major employer in the region for 100 years, was purchased by the Atlantic Richfield Co. in 1977. With the purchase came the responsibility for cleaning up more than 3,600 acres of mill tailing settling ponds, Hons said.
"The Anaconda Superfund site is the largest in the U.S., because it includes not just the 3,600 acres of tailings ponds, but thousands of acres surrounding the mineral processing and smelting area," he said. "The Environmental Protection Agency and the state of Montana have been working with Atlantic Richfield to reclaim these areas since the mid-1980s."
Over the years, the smelting and processing of copper ore resulted in millions of tons of waste, Hons said. The vast majority of the mill tailings were captured and stored in settling ponds, but part of these materials escaped to the Clark Fork River. Some of these materials were transported 100 miles downstream and were captured in Milltown Reservoir, where they've remained for up to 100 years.
In 2009, Milltown sediments were dredged and returned to Anaconda, where they were spread over 800 acres of old tailing ponds. The sediments were amended and planted with native plant species with no success, Hons said.
Although Atlantic Richfield has a program for remediating soils in the area, these Milltown sediments represented a unique revegetaion challenge. That's when Dr. Terry Moore, with Atlantic Richfield's Remediation Management te
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Texas A&M AgriLife Communications