Just off Interstate 90, an excavator perched atop an unloading ramp has been filling a steady supply line of 40-ton haul trucks with the jet-black soil.
Packing an 18-cubic-yard load, the trucks roar over a two-mile stretch of gravel road to a pair of bulldozers waiting to spread the sediment two feet deep atop the first 20 acres of yellowish-brown mill tailings at the BP-Arco Waste Repository, formerly known as the Opportunity Ponds.
The cell was about half-filled with Milltown sediment.
“That's a week's worth of trains,” said the U.S. Environmental Protection Agency's Anaconda Smelter Superfund Site project manager. “That's 10 acres done and 1,000 more acres to go.”
Almost daily - over the course of about 800 days - a train hauling 4,500 tons of contaminated sediment mined from Milltown Reservoir will roll into the loading dock at Opportunity.
By the time the project is completed, an estimated
2.2 million cubic yards of sediment will be used to cover close to 1,000 acres of mill tailings left from a century of smelting ore in Anaconda, in hopes of forever capping the toxic material under fields of grass.
The work is just one part of a long-term project to cover the 3,500-acre Opportunity Ponds - where about
160 million cubic yards of mill tailings have been stored for decades.
Smelters built the town of Anaconda. The tons of mill waste is the legacy they left behind.
The first smelter in Anaconda was built in 1884 near the site of today's Old Works Golf Course. In 1902, Marcus Daly's Amalgamated Copper Co. opened the Washoe Smelter above the town.
The Opportunity Ponds were built to contain the waste produced in the milling process.
Smelters crushed copper ore from the mines in Butte and then mixed with it with water and chemicals like arsenic to extract valuable metals. With the riches gleaned from the ore, the remaining noxious concoction was sluiced down the hill into large settling ponds.
The heaviest contaminants drifted to the bottom, while most of the water was siphoned off by decanting towers until all that was left was a toxic sludge. As soon as one pond filled, another was built.
The ponds started near town and slowly worked their way east. By the time Atlantic Richfield Co. closed the Anaconda smelter in the early 1980s, the tailings covered more than 3,500 acres and in some places were 40 feet deep.
It takes some elevation to fully appreciate the extent of the contaminated landscape.
Stand in the shadow of the smelter's smokestack on Anaconda's skyline and look east. Bordered by Mill Creek to the right and Warm Springs Creek on the left is a seven-mile-long span that ends at Interstate 90.
“When I bring people out here, they just can't believe how big it is,” said Ken Brockman, a U.S. Bureau of Mines civil engineer assigned to the site. “Even many of the local people don't really know just how large this is.”
The Anaconda Smelter Superfund Site was designated for cleanup by the Environmental Protection Agency in 1983. The BP-Arco Waste Repository is just one of about 20 different projects identified in the 300-square-mile upper Clark Fork Superfund site.
Atlantic Richfield merged with Anaconda Copper in 1979, and inherited the task of cleaning up mine and smelter tailings that extended from Butte and Anaconda all along the upper Clark Fork River to Milltown Reservoir just east of Missoula.
Arco has since merged with BP Amoco.
Standing on the hillside above Anaconda, Coleman points to some of the cleanup work that's already been accomplished.
On the northeast corner of Anaconda, the bright green Jack Nicklaus-designed Old Works Golf Course with its signature deep black slag traps serves as a cap over mill tailings at the town's first smelter site.
Just to the east of the smokestack are several grass-covered hills that mark repository sites for some of the most contaminated materials produced by the smelting process.
And scattered here and there are fields of brown grass where Arco has finished capping hundreds of acres of tailings.
“There's been a lot of work completed,” Coleman said. “There's still lots more that needs to be done. Š This site is huge. If it's not the biggest Superfund site, it's one of the biggest in both size and the volume of contaminants.”
The cost of the cleanup has been staggering.
“Arco doesn't give out good numbers, but the costs at this site alone are probably approaching a quarter of a billion (dollars) and there's still work to be done,” he said.
At the Opportunity Ponds site alone, Coleman said there may be as much 160 million cubic yards of tailings. Combine all the tailings in the upper Clark Fork Superfund site and that number could more than double.
“We looked at a variety of options of cleaning up this site years ago,” he said. “We considered removing all these tailings. Š The cost would run into the multiple billions of dollars. It was decided to leave the wastes and deal with them here.”
Compared to other Superfund sites, the cleanup itself is relatively straightforward, Coleman said.
“We do have sites that are smaller but more complicated due to the kinds of chemicals that need to be addressed,” Coleman said. “The challenge here is its size and the stigma for surrounding communities.”
Gavin Scally, Arco's deputy regional manager, said the company hopes to finish capping the Opportunity Ponds by the end of the 2009 construction season. Some additional seeding might be required the following year.
When the project is completed, Scally said the company envisions a haven for wildlife in both the wetlands and uplands.
“We expect the area to have significant value for wildlife,” he said. “It's adjacent to the Warm Springs Ponds area, which is already valuable wildlife habitat.”
“It's very gratifying to be getting toward the end of this portion of the project,” he said.
The sediment from Milltown will cap about a third of the Opportunity Ponds. The remainder is being covered by either clean soil scooped from areas nearby or with slightly contaminated dirt from other Arco Superfund cleanup sites along the Clark Fork River.
There isn't a good source of topsoil anywhere close to the site, Coleman said.
In most cases, Arco has needed to add organic material like manure to the local soils or lime to neutralize acidic levels in the contaminated material. On many of the areas that have already been capped and seeded, clumps of grass grow among the rocks.
“Arco has been forced to look everywhere to find compost for most of the local soils,” Coleman said. “There just isn't much organic material in it. The availability of compost has been one of the company's biggest headaches.”
That's what makes the sediment from Milltown so appealing.
While it contains many of the same contaminants as the Opportunity Ponds' tailings, they are at much lower levels. More importantly, the sediment is filled with the kind of rich organic material necessary for plants to grow.
“We can work with even the worst of the Milltown stuff,” Coleman said. “Arco will test it and see if it needs to add any lime, but I expect if it does, it will be in pretty low amounts.
“It's really the stuff of choice when we consider all our alternatives,” he said.
The contaminated sediment arrived on the heels a tremendous flood in 1908 that washed mine and smelter tailings downstream from Silver Bow Creek and the upper Clark Fork into the reservoir behind Milltown Dam.
Over the years, additional sediment has settled out on top of the most contaminated material. Arsenic pollution was found in Milltown's water supply 26 years ago.
Removing Milltown Dam and the tons of sediment removes that source of arsenic and will eventually result in a clean aquifer.
Moving the arsenic-contaminated sediment from a wet environment to a dry one will lessen the risk for groundwater contamination in the Opportunity area, Coleman said.
Arsenic is more mobile when deprived of oxygen.
Milltown Reservoir provided that kind of setting. The hydraulic pressure of water downward behind the dam carried arsenic through the sediment and into the groundwater and contaminated domestic water wells.
Coleman said the capped tailings are designed so precipitation won't pool. The water should either evaporate or be used by the vegetation.
Not everyone is happy to see railcars hauling even more contaminated soil into the Opportunity area.
Becky Guay, Anaconda-Deer Lodge County's chief executive, said local residents are concerned.
“Anytime you bring hundreds of thousands of cubic yards of contaminated material into a community, it's a big concern,” Guay said.
Locals wish there had been more research conducted to ensure the Milltown sediment won't create even more long-term problems.
“I don't think anyone knows for sure how it's going to react after being taken from an aquatic environment to a dry environment,” she said. “There could be chemical reactions that will impact its ability to grow anything.”
People realize the sediment isn't as contaminated as most of the other mill tailings stored at the repository. For the most part, if the sediment was located in an Anaconda resident's front yard, it wouldn't meet the parameters necessary for Arco to replace it.
The company has replaced about 300 residential yards where arsenic was found to be about 250 parts per million.
Still people worry.
“This is just such a huge site,” she said. “We're not sure that there's been enough study to determine if it's really going to be a good thing for the area.”
George Niland of the Opportunity Citizens Protective Association said residents of the small town of Opportunity aren't happy that more toxic dirt is being dumped in their backyard.
“People just feel like this is adding insult to injury,” Niland said. “It's being spread out less than a mile and a half from the community and there's nothing we can do about it.”
Over the last century, Niland said locals have watched the company experiment with a variety of methods to reclaim the mill tailings.
“They all failed,” he said. “Over the long term, I don't think it's going to work myself. People here are skeptical of the plan.”
Over the past several years, Opportunity residents and others living nearby have dealt with large clouds of dust coming off the repository. Niland said Arco's efforts to keep the dust under control appeared to work better this summer.
And folks worry about the potential for pollution of their groundwater.
“There are just lots and lots of concerns here about accepting even more contaminated soil from Milltown and other places,” he said. “People have accepted its coming. We're hoping for the best.”
The 52-year-old Niland has reason to worry.
He's already lost a sister to ovarian cancer. Another sister is fighting brain cancer. He's dealt with a bout of spinal cancer. And his family has lost three dogs to cancer.
“I was born and raised here,” Niland said. “I've seen a lot of young people die from leukemia and MS (multiple sclerosis). I don't really even know why I live here anymore.
“It's my home. It's a beautiful little town. It's just really hard to leave your home.”
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