The Crested Butte News Serving the Gunnison Valley since 1999
Work could begin in 2013
After five years of studying the old Standard Mine site south of Scarp Ridge, the Environmental Protection Agency (EPA) has approved a remediation plan for the superfund site. The two-phase plan would control the flow of water through the mine to reduce contamination, and if needed, use passive water treatment to further treat runoff.
The record of decision, signed in September, has the support of the local nonprofit Standard Mine Technical Advisory Group but still needs to be selected for federal funding. It could take until 2013 before the plan is implemented, complementing remediation work already done from 2007 through 2009.
The Standard Mine, which is about five miles west of Crested Butte and drains into Elk Creek, was added to the National Priority List in 2005 because of elevated levels of metals in the soil and the creek. Elk Creek flows into Coal Creek, which is the site of the municipal water intake for Crested Butte.
“We were really fortunate that when the EPA first came in 2006, they had the funding to do some surface cleanup first,” said Anthony Poponi, executive director of Coal Creek Watershed Coalition and grant administrator for the advisory group.
That work included building a repository for mine tailings that included waste rock and tailings rich in pyrite, a metal that creates acid mine drainage when exposed to air. After removing waste rock and tailings from Elk Creek, the EPA also reconfigured the creek.
“The miners had produced a creek channel around and through the mill site, which was not the natural orientation, so once we took the tailings out, we dropped the creek back to its natural alignment,” explained EPA superfund project manager Christina Progess.
That alignment includes small wetlands and riparian areas and has led to a measureable reduction in metals in Coal Creek and Elk Creek. According to data provided by Poponi, water quality monitoring shows reduced levels of cadmium and zinc in Elk Creek and even downstream in Coal Creak. Between 2006 and 2010, cadmium levels in Elk Creek of decreased from approximately five parts per billion (ppb) to about one ppb, and zinc fell from 1,125 ppb to just over 200 ppb. But that still left the matter of water coming out of the mine workings.
“There are three connected mine levels,” said Poponi, “and the EPA knew water coming in at the highest level was in pretty good condition and by the time it came out at level 1 [at the bottom] it was really bad, so they did some investigations and what they came up with was the proposed plan.”
The first phase of the remediation plan proposes filling the entrance at level 3, toward the top of the mine, with a flowable fill and foam. That fill, a concrete mixture, would seal off the entrance to the mine so that clean water could be prevented from entering mine workings and would reduce the amount of water coming out of level 1.
“We’re calling [the first phase] control work, to keep water from percolating and moving through from top of the mine to the bottom where it gets contaminating,” said Progess. “We’re diverting it there rather than allowing it to infiltrate into the wasterock that remains in the mine.”
A flowthrough bulkhead would be installed at level 1 to control the water flowing out of the bottom of the mine. The bulkhead would allow for what Progess calls the “metered release” of water from the mine.
According to Progess, monitoring will be conducted for three years after the completion of the first phase to determine whether the second phase—the installation of what the EPA calls a bioreactor to clean the water using microbial degradation—would be required.
Poponi explained, “The Mount Emmons water treatment plant is an active treatment system, removing contaminants from the water by running it through filters. What they are proposing in this case is to create wetland conditions that are favorable for natural removal of those metals.”
The EPA studied a range of remediation plans to arrive at September’s record of decision, balancing feasibility with cost to determine the approach that will work the best while also being the most cost-effective.
“They chose what we think is a pretty reasonable approach,” Poponi said.
In the coming months, the EPA will develop engineering plans for the Standard Mine, determining exact materials and cost. Progess expects those plans to be submitted to the EPA priority panel, which meets twice a year to prioritize superfund projects for funding, in March 2013. If selected for funding, work could begin in 2013.
Residents interested in learning more about the plan are invited to attend an EPA-hosted community meeting on November 30, at 1 p.m. in Town Hall.
