EPA continuing with efforts to clean up Standard Mine site

Mine discharge still an issue

By the end of this summer, the only thing left at the old Standard Mine site will be a graded slope, a fresh layer of topsoil ready for vegetative growth, a meandering stream, a small shack and some solar arrays. This is where, just four years ago, there were crumbling wooden mine structures, more than a thousand tons of waste rock, and a pond that leaked acidic mine drainage into Elk Creek.

 
The Environmental Protection Agency (EPA) is now in its third summer of reclaiming the site of the Standard Mine. The mine operated from 1874 all the way up to 1966, producing zinc, iron, gold, and silver.
The EPA added the Standard Mine to the national priorities list for mine reclamation in 2005, after water testing proved heavy metals were entering Coal Creek, through the Elk Creek tributary. Coal Creek runs through downtown Crested Butte, and is the source of the town’s drinking water supply.
During the first two summers the cleanup process involved removing and containing the waste rock and tailings pond in a separate “repository” site about a half-mile away from the mine. This summer the repository is being capped with a special material that prevents groundwater leeching, and the entire site will be re-vegetated.
Next summer the EPA, in coordination with the Colorado Division of Mined Land Reclamation and Safety, will finish the reclamation process by attempting to contain or otherwise mitigate further contaminated wastewater drainage from leaving the mine site.
According to an August 4 report from EPA on-site coordinator Gina Andrews, crews began capping the repository site on August 11. The EPA had a delayed start on the remediation process this summer, because the site was not entirely clear of snow until the beginning of July. Andrews says the repository should be completely capped by the end of this week.
Members of the Standard Mine Advisory Group and Coal Creek Watershed Coalition (CCWC), two local groups that are serving as watchdogs over the federal cleanup efforts, took a tour of the site earlier this month. CCWC coordinator Anthony Poponi says, “I think the progress has been excellent… They are working 12-hour days, seven days a week.”
According to Colorado Division of Mined Land Reclamation projects manager Jim Lewis, over the next few weeks as the EPA continues to re-vegetate and restore old tailings deposit areas, the Division and U.S. Forest Service will re-route the headwaters of Elk Creek onto what is thought to be its original course prior to the mine’s existence.
CCWC board member Steve Glazer says the historical route of the creek was determined by a segment of smooth cobble and pebbles found underneath the mine tailings. The agencies will also create several wetlands areas to assist the growth of the surrounding environment.
Once all of that is done, Glazer says, the EPA will be tasked with reducing or eliminating discharged water from the mine. The United States Geological Survey studied the site in 2004 and determined that a large percentage of the water exiting the mine portal is coming in through a fault line above the mine. The water gets contaminated through its course of trickling through the old mine workings.
Lewis says to prevent the water from entering the mine, crews will attempt to create a series of diversion structures above the mine entrance, where the headwaters of Elk Creek are collected. “We’re thinking if it’s possible we’ll put in a French drain, or we may put in a cutoff wall, or some sort of barrier or catch basin that would collect (runoff) and then divert it around so it doesn’t go through the mine workings. That will dramatically improve the water quality of Elk Creek,” Lewis says.
Poponi says there are some interesting projects the EPA is also considering to mitigate the remaining discharge. One of those involves a buried chamber with special mulch and bacteria that neutralizes heavy metals.
“What they’re doing is still kind of testing it out to see if they can have good results with the sulfate reducing bioreactor,” Poponi says.
Glazer says there are some troubles with the bio-reactor. For one, it will remove other hazardous metals, but not manganese or iron. So the EPA is considering a second, similar bio-reactor on the surface that will remove those metals.
The other trouble is the bio-reactor is treating only one gallon of water a minute, but discharges from the mine average 20 gallons a minute Glazer says. For the passive bio-reactor to be effective in mitigating all the heavy metals, Glazer says, “They need to figure out if they can reduce the amount of water coming out of the mine.”
Poponi says water quality sampling in Elk Creek and Coal Creek has been ongoing this summer. A water quality sample in Elk Creek taken at the end of last summer’s remediation efforts indicated that some progress was being made toward eliminating heavy metals, but Poponi says, it’s hard to base findings off just one sample. He says, “We think we saw a little bit of improvement last October… It was just one day, so it’s hard to say.”
Poponi says the CCWC is still waiting for results from water testing conducted earlier this summer.
Lewis says this summer’s remediation efforts should provide much better water flowing down Elk Creek. “I would suspect when they sample again in the fall there could be some pretty significant improvements,” Lewis says.