Reclamation takes root at mine site near Aspen
June 27, 2011
ASPEN – Reason for hope has sprung up this month at the Hope Mine south of Aspen, where the seeds of an experiment in mine reclamation were planted last fall.
Last September, representatives of the U.S. Forest Service, Aspen nonprofit For the Forest and the Carbondale-based Flux Farm Foundation stood atop a nearly barren tailings pile at the defunct silver mine, located off Castle Creek Road.
The mine tailings, dirt and rock laced with heavy metals, plunge down to the edge of Castle Creek, a key source for Aspen’s municipal water. While elevated levels of metals have been recorded in the water at the base of the pile, but not at the city’s water plant, the potential for a significant slumping of the mine waste into the creek bed made the site an obvious choice for a pilot effort to revegetate the steep, infertile tailings.
Hints of possible success poked through the landscape this spring, where three cameras are snapping photos every three hours while there’s daylight, capturing what will become time-lapse footage of native grasses taking hold in the challenging landscape. Or not.
Though pockets of green dot the expansive tailings pile now, it’s too early to predict any lasting success, according to the man keeping close tabs on the vegetation’s progress.
“The next question is how these seedlings will survive in the next few months, over the heat of the summer,” said Morgan Williams, executive director of the Flux Farm Foundation. The organization has an interest in a broader application of the methods used at the Hope Mine – advancing the viability of agriculture in the West.
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Still, Williams is encouraged.
On the flat area atop the tailings pile, thick grass has filled in among dandelions. The steepest slopes of the pile are showing the least amount of new growth, but other areas are greener, and 42 test plots on a more gently sloping area of the mine waste are producing even more telling results.
Revegetating the tailings pile involved the placement of biodegradable netting to hold the application in place; it was covered by a seed mix, compost, biochar, hydromulch and naturally occurring mycorrhizal fungi, which help plant roots take in nutrients, particularly in sterile soils.
Most of the pile received the same treatment, but in the 7-by-7-foot test plots, each delineated with orange flags poking upward among the grasses, the mix of components is varied. The idea is to identify the optimal mixture, Williams explained.
Already, some plots are faring better than others. On test plots that received no application of the growth mixture, the difference is startling. They are essentially bare.
“What I’m excited about is that there’s variation, even in this early stage,” Williams said. “We can actually learn from this.”
Williams is keeping particularly close watch on the effect of biochar, a carbon-rich product created when biomass is heated in a closed container with limited air. Mixed with soil – possibly even the challenging dirt of a tailings pile – biochar increases its ability to retain both moisture and nutrients.
Biochar could create a market for the dead trees that the bark beetle epidemic has left around Colorado, according to For the Forest. The trees could be converted into biochar, a product that offers the added advantage of locking in the carbon from organic materials, keeping it out of the atmosphere. In that sense, its use addresses climate change, as well.
For the Forest provided most of the $80,000 spent on the Hope Mine reclamation, according to John Bennett, the organization’s executive director.
“What’s really going to bring the price down is when biochar is more readily available and cheaper,” he said. “For the Forest was the largest single purchaser of biochar last year. That is both impressive and depressing.”
So far, Williams has noted a considerable difference in the condition of the test plots that contain biochar versus those that don’t. On a recent afternoon, with the sun baking the southwest-facing slope, the soil temperature in one test plot treated with biochar was 58 degrees. It’s moisture level stood at 12 percent. Six feet away, on a plot that had not received any application, the soil temperature was 79 degrees and the moisture content was 3 percent.
While the monitoring of the Hope Mine reclamation is ongoing, Williams is already a believer in biochar, joining Denver-based soil scientist Andrew Harley in a business venture, Biochar Solutions Inc. Harley was a consultant on the Hope Mine project.
Biochar Solutions has merged with Biochar Engineering Corp. in Golden, a manufacturer of the product. The goal, Williams said, is producing a mixture that contains all of the elements applied separately at the Hope Mine site.
“We really feel a first market for biochar is in the reclamation space,” Williams said.
The public will have a chance to see the reclamation project on July 23, during a field trip to the Hope Mine hosted by For the Forest and the Aspen Center for Environmental Studies. The cost is $15 for ACES members and $20 for non-members. Go to http://www.aspennature.org/programs/summer-fall/adults to register and for more information.