Tailing reclamation and major equipment replacement
by Mark Reaman
Some major work will take place at the Mt. Emmons Mine site this fall. Reclaiming and consolidation of a couple of mine waste tailings piles and replacing a major piece of equipment in the water treatment plant will start next month.
A public community open house to find out more about the mine site will be held Thursday, August 30 at the Crested Butte Town Hall from 4 to 7 p.m.
Mt. Emmons Mining Company (MEMCO) manager Dave Gosen told the Crested Butte Town Council Monday that since Freeport McMoRan (the owner of MEMCO) acquired the site in 2016 the global mining company has been analyzing the mine site to determine what is necessary to keep the water quality in good condition and make the operation run more efficiently.
This fall the most visible work will be conducted in conjunction with DRMS (Colorado Division of Reclamation, Mining and Safety) and Trout Unlimited. Tara Tafi of DRMS helped design the reclamation efforts and explained the details to council members and county representatives on a Monday afternoon tour of the sites. She said the work would start September 4 and last six to eight weeks. Eventually the sites will hold vegetation.
“We have spent two years since 2016 better understanding what we have and figuring out how to best run the water treatment plant safely,” Gosen said Monday evening. “In terms of safety, we’re serious about safety operations. Frankly, the water treatment plant is old and is at the end of its useful design life.”
Gosen said a major replacement operation would occur this fall with the replacement of one of two big filter presses that extract water from the sludge produced as part of the water treatment process. “That is probably the most critical piece of infrastructure to replace in order to keep the plant running smoothly,” he said.
The new, more modern press should be able to handle most of the water treatment work while the remaining old press will be used as a backup. To get the old one out and the new one in, the roof at the plant will be cut and a giant crane employed. Gosen said fall is the best time to perform such work since sludge generation is at a low point of the year.
Gosen said Freeport is evaluating how to overall best improve the outdated wastewater treatment plant for the long term. He said the analysis would take a few more years before a decision is made to either build a new plant from scratch or continue to update the existing facility. He said no matter the decision, the water treatment at the mine site will be stable and safe. The water is currently treated to go beyond safe drinking water standards, since it is dispersed into Coal Creek, a trout stream with aquatic stream standards.
During the afternoon tour, Jim Frank, owner of the company overseeing the plant, pointed out that while similar plants have a few violations each year, the Mt. Emmons plant has not had a violation in the last 13 years. Frank credited the consistency of the staff. He said the plant treats an average of 320 gallons of water per minute every day of the year. Most of the treated water comes from behind the bulkhead of the old portal located a mile inside Mt. Emmons. He said on an annual basis the treatment plant uses about the same amount of power as the ski area. The mine is also the single biggest client of the Gunnison County landfill, as they deposit between 75 and 100 semi-truck loads of treated sludge at the landfill each year.
In response to council’s questions, Gosen said the company has no plan to mine molybdenum from the mine site.
Town attorney Barbara Green reminded the council that Freeport signed a Memorandum of Understanding when they acquired the site “contemplating there would be no mining there in the future. The exact process to accomplish that has yet to be resolved but it is one element of the MOU they signed along with the town in 2016,” she said.
Water quality continues to be the priority, according to Gosen. “I would like to think at some point we could treat the water without a plant,” he told the council. He said Freeport uses some passive water treatment procedures in other locations but the amount of water treated at the Mt. Emmons site currently prohibits that option.
Overall, Gosen said, the company has taken an “adaptive management approach” to the site. “We look to make the most effective improvements we can, see if they work and move to the next project to improve the water quality and improve operational efficiencies,” he explained. “We work on what we think needs the most immediate attention and go from there.”
The reclamation of two tailings piles and the replacement of the filter press are falling into that category this coming September and October.